Publications by authors named "Kevin Bell"

53 Publications

Subjective and Objective Measures in Assessing Neck Disability and Pain in Head and Neck Cancer.

Laryngoscope 2021 Mar 3. Epub 2021 Mar 3.

Department of Otolaryngology - Head and Neck Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, U.S.A.

Objective/hypothesis: The intensification of treatment for head and neck cancers (HNCs) has created a cohort of patients living with short- and long-term comorbidities and functional deficits. This study aimed to determine whether there is a relationship between patient-reported outcomes (PROs) and objective measures of neck function in survivors of HNCs.

Study Design: Cross-sectional study.

Methods: Thirty-one subjects (aged 64 ± 8.7 years; 28 males and three females) were recruited and completed the Neck Disability Index (NDI) and a numeric pain scale. At the same visit, subjects were fitted with two portable motion sensors to collect range of motion (ROM) and velocity data. Differences between ROM, velocity, and PRO subgroups were assessed using a one-tailed t test (*P < .05). The Pearson correlation coefficient (r) was calculated between the NDI values and the ROM and velocity values for each motion.

Results: A moderate correlation (r = 0.507) was observed between NDI and neck pain. Patients with no disability according to the NDI had significantly higher ROM and velocity than patients with mild to moderate disability. Velocity in all degrees of freedom (axial rotation, flexion and extension, and lateral bending) was significantly lower for patients who perceived higher levels of neck pain and neck disability.

Conclusions: This study notes that patients who report neck disability and pain have more limited ROM and velocity following HNC treatment. These data may improve treatment planning and care delivery by facilitating an understanding of the experiences of HNC survivors and the pathophysiology that must be targeted to address their psychosocial and functional deficits.

Level Of Evidence: 4 Laryngoscope, 2021.
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http://dx.doi.org/10.1002/lary.29488DOI Listing
March 2021

A Portable System for Remote Rehabilitation Following a Total Knee Replacement: A Pilot Randomized Controlled Clinical Study.

Sensors (Basel) 2020 Oct 27;20(21). Epub 2020 Oct 27.

Department of Orthopaedic Surgery, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA.

Rehabilitation has been shown to improve functional outcomes following total knee replacement (TKR). However, its delivery and associated costs are highly variable. The authors have developed and previously validated the accuracy of a remote (wearable) rehabilitation monitoring platform (). The present study's objective was to assess the feasibility of utilizing for the remote management of rehabilitation after TKR and to determine a preliminary estimate of the effects of the system on the value of rehabilitation. Specifically, we tested post-operative outpatient rehabilitation supplemented with (n = 13) by comparing it to a standard post-operative outpatient rehabilitation program (n = 12) using a randomized design. Attrition rates were relatively low and not significantly different between groups, indicating that participants found both interventions acceptable. A small (not statistically significant) decrease in the number of physical therapy visits was observed in the Group, therefore no significant difference in total cost could be observed. All patients and physical therapists in the Group indicated that they would use the system again in the future. Therefore, the next steps are to address the concerns identified in this pilot study and to expand the platform to include behavioral change strategies prior to conducting a full-scale randomized controlled trial. Trial registration: ClinicalTrials.gov NCT02646761 ": A Portable Joint Function Monitoring and Training System for Remote Rehabilitation Following TKA" 6 January 2016.
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http://dx.doi.org/10.3390/s20216118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7663639PMC
October 2020

Preliminary validation of a mobile force Sensing device for clinical and telerehabilitation.

J Biomech 2020 09 25;110:109973. Epub 2020 Jul 25.

School of Health Professions, Department of Rehabilitation and Movement Sciences, Rutgers University, Blackwood, NJ 08012, United States. Electronic address:

Muscle strength and force production are important measures of patient progress during physical rehabilitation. Reliable and objective measurements are important to ascertain throughout rehabilitation. Current methods-manual muscle testing, electromechanical dynamometer, and hand-held dynamometer-are accurate and reliable, but have limitations that prevent wide implementation. As healthcare systems adapt to more patient-centered outcome models, changes to the delivery of rehabilitation, whether at-home or in the clinic, must also change to become more cost effective and accessible and provide quantifiable information regarding patient progress. We developed a novel Force Sensing (FoSe) device to quantify either tensile or compressive isometric muscle strength. The device was tested in a laboratory setting with healthy participants (n = 32) and compared to the commonly used hand-held dynamometer (HHD). Participants used both devices to perform several common isometric muscle tests including: hip abduction, knee extension, knee flexion, shoulder external rotation, and shoulder internal rotation. Compared to the HHD, FoSe was found to be an accurate and reliable measurement of force production. Intraclass Correlation Coefficients ranged from 0.58 to 0.89 without a magnitude dependent variation in force measurement. A second round of clinical testing with a patient population is warranted to determine FoSe's ability to measure clinically relevant asymmetry and progress over time. Further usability testing also needs to be conducted to determine the adequacy of FoSe for at-home use by both patients and clinicians.
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http://dx.doi.org/10.1016/j.jbiomech.2020.109973DOI Listing
September 2020

Assessing the biofidelity of in vitro biomechanical testing of the human cervical spine.

J Orthop Res 2020 Apr 25. Epub 2020 Apr 25.

Ferguson Lab for Orthopaedic Research, Department of Orthopaedic Surgery, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.

In vitro biomechanical studies of the osteoligamentous spine are widely used to characterize normal biomechanics, identify injury mechanisms, and assess the effects of degeneration and surgical instrumentation on spine mechanics. The objective of this study was to determine how well four standards in vitro loading paradigms replicate in vivo kinematics with regards to the instantaneous center of rotation and arthrokinematics in relation to disc deformation. In vivo data were previously collected from 20 asymptomatic participants (45.5 ± 5.8 years) who performed full range of motion neck flexion-extension (FE) within a biplane x-ray system. Intervertebral kinematics were determined with sub-millimeter precision using a validated model-based tracking process. Ten cadaveric spines (51.8 ± 7.3 years) were tested in FE within a robotic testing system. Each specimen was tested under four loading conditions: pure moment, axial loading, follower loading, and combined loading. The in vivo and in vitro bone motion data were directly compared. The average in vitro instant center of rotation was significantly more anterior in all four loading paradigms for all levels. In general, the anterior and posterior disc heights were larger in the in vitro models than in vivo. However, after adjusting for gender, the observed differences in disc height were not statistically significant. This data suggests that in vitro biomechanical testing alone may fail to replicate in vivo conditions, with significant implications for novel motion preservation devices such as cervical disc arthroplasty implants.
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http://dx.doi.org/10.1002/jor.24702DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7606317PMC
April 2020

Biomechanical contribution of the alar ligaments to upper cervical stability.

J Biomech 2020 01 23;99:109508. Epub 2019 Nov 23.

Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, United States; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States. Electronic address:

Acute and chronic whiplash-associated disorders pose a significant healthcare burden due to chronic pain, which is associated with upper cervical instability resulting from ligamentous injury. No standard measure exists for diagnosing alar ligament injury and imaging findings vary widely. Multiple physical examination maneuvers are used to diagnose alar ligament injury including the C2 Spinous Kick, Flexion-Rotation, and Bending-Rotation tests. The objective of the current study was to determine the mechanical contribution of the alar ligaments to upper cervical stability and quantify the biomechanical changes seen during simulated clinical examinations after alar ligament injury. Eight cadaveric C0-C3 specimens were evaluated using a robotic testing system. Range of motion and moment at the end of intact specimen replay were the primary outcomes. Clinical examinations were simulated by rotation through two axes as performed during physical examination. Intact, unilateral and bilateral alar ligament injury states were tested. Unilateral alar ligament injury led to significant increases in lateral bending (12.0 ± 7.2%, p < 0.05), axial rotation (4.1 ± 2.4%, p < 0.05), and flexion-extension (5.3 ± 4.3%, p < 0.05) compared with intact specimens. The alar ligaments also contributed to resistance to intact motion in extension (13.4 ± 6.6%, p < 0.05), flexion (4.4 ± 2.2%, p < 0.05), axial rotation (19.3 ± 2.7%, p < 0.05), and lateral bending (16.0 ± 2.8%, p < 0.05). The C2 Spinous Kick Test showed the largest percentage change (-23.0 ± 14.8%), and the Bending-Rotation Test towards the side of injury significantly increased axial rotation by the largest absolute magnitude (5.5° ± 5.1°). Overall, quantifiable changes to motion measured during simulated physical examinations were found, but the ability of a clinician to feel these changes remains unknown.
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http://dx.doi.org/10.1016/j.jbiomech.2019.109508DOI Listing
January 2020

Novel use of telescoping growth rods in treatment of early onset scoliosis: An and study in a porcine model.

JOR Spine 2018 Dec 8;1(4):e1035. Epub 2018 Oct 8.

Department of Orthopaedic Surgery, School of Medicine University of Pittsburgh Pittsburgh Pennsylvania.

Introduction: Treatment of early-onset scoliosis (EOS) can be difficult. Various forms of growing rods exist to correct deformity while delaying definitive spinal fusion. The disadvantage of traditional growing rods is need for repeated surgical lengthening procedures. Telescoping growth rods (TelGR) are a prototype new, guided growth technology with a rod mechanism that allows spontaneous longitudinal growth over time without manual lengthening. We hypothesized that the TelGR system will permit unrestricted growth with limited complications through 12 weeks , and that the range of motion (RoM) in each of three directions and stiffness of the TelGR system would not be significantly different than the rigid rod system .

Materials And Methods: : Six immature pigs were surgically implanted with TelGR with cephalad fixation at T6-7 and caudal fixation at T14-L1. Radiographs of the involved vertebral segments were measured postoperatively and after 12 weeks. : A robotic testing system was utilized for flexibility tests in flexion-extension (FE), lateral bending (LB), and axial rotation (AR) of eight immature porcine specimens (T3-T15). Testing was performed on both dual rigid rods and bilateral TelGR with instrumentation at T4-5 and T13-14.

Results: : Over the 12-week period, the rod length of the TelGR increased an average of 65 mm. : TelGR demonstrated significantly increased motion in LB and AR RoM compared with rigid rods. No difference was noted in FE RoM.

Discussion: The results in this study showed expected skeletal growth with spines instrumented with TelGR. findings of increased RoM in AR and LB suggest that the TelGR system may be less rigid than traditional growing rods. Treatment with TelGR might, if proven efficacious in the clinical setting, decrease the need for repeated surgical intervention compared with traditional growing rods. This study adds to the limited body of biomechanical evidence examining guided growth technology.
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http://dx.doi.org/10.1002/jsp2.1035DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6686829PMC
December 2018

Biomechanical Analysis of a Growing Rod with Sliding Pedicle Screw System for Early-Onset Scoliosis.

J Healthc Eng 2019 12;2019:9535070. Epub 2019 Jun 12.

Ferguson Laboratory for Spine Research, Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.

Early-onset scoliosis (EOS) remains a challenging condition for which current nonfusion surgeries require iterative lengthening surgeries. A growing rod with sliding pedicle screw system (GRSPSS) was developed to treat spinal deformities without repeated operative lengthening. This study was performed to evaluate whether GRSPSS had similar stability as a conventional pedicle screw system to maintain deformity correction. A serial-linkage robotic manipulator with a six-axis load cell positioned on the end-effector was utilized to evaluate the mechanical stability of the GRSPSS versus conventional fixed scoliosis instrumentation. Ten skeletally mature thoracic female Katahdin sheep spines (T4-L1) were subjected to 2.5 Nm of flexion-extension (FE), lateral bending (LB), and axial rotation (AR) in 2° increments for each state. The overall range of motion (ROM), apical segment ROM, and stiffness were calculated and reported. A two-tailed paired -test was used to detect significant differences ( < 0.05) between the fixed group and GRSPSS fixation. There were no significant differences in overall range of motion (ROM), apical segment ROM, or stiffness for FE or LB between the GRSPSS group and fixed group. In AR, the GRSPSS group showed increased ROM compared to the fixed group for the overall spine (36.0° versus 19.2°, < 0.01) and for the instrumented T8-T10 segments (7.0° versus 2.9°, =0.02). Similarly, the fixed rod elastic zone (EZ) stiffness was significantly greater than the GRSPSS EZ stiffness (0.29 N/m versus 0.17 N/m, < 0.001). The space around the rod allows for the increased AR observed with the GRSPSS fusion technique and is necessary for axial growth. The GRSPSS fusion model shows equivalent flexion and LB stability to current fusion models and represents a stable fusion technique and may allow for longitudinal growth during childhood.
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http://dx.doi.org/10.1155/2019/9535070DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6594281PMC
September 2020

Biomechanical Analysis of Wide Posterior Releases Compared With Inferior Facetectomy and Discectomy in the Thoracolumbar and Lumbar Spine.

Spine Deform 2019 05;7(3):404-409

Department of Orthopaedics, University of Pittsburgh Ferguson Laboratory for Orthopaedic Research, 200 Lothrop St., E1658, University of Pittsburgh, Pittsburgh, PA 15213, USA.

Study Design: In vitro biomechanical analysis.

Objectives: Compare the destabilizing effects of anterior discectomy to posterior spinal releases.

Summary Of Background Data: Posterior release and pedicle screw fixation has become the accepted form of treatment for lumbar and thoracolumbar pediatric scoliotic spinal deformity. A biomechanical evaluation of posterior releases with comparison to traditional anterior releases has not been reported in the lumbar spine.

Methods: Eleven fresh-frozen human thoracolumbar specimens (T9-L5) were tested by a robotic manipulator (Staubli RX90; moment target of 5.0 Nm, force target of 50 N) in axial rotation (AR), plus lateral and anterior translation (LT and AT). Specimens underwent either sequential anterior release (partial and full discectomy) or posterior release (inferior facetectomy and wide posterior release) from T10 to L4. Partial discectomy retained the posterior 50% of disc and posterior longitudinal ligament, whereas full discectomy removed all of the disc and PLL. Wide posterior release included total facetectomy plus ligamentum flavum and spinous process resection.

Results: Inferior facetectomy produced an average increase of 1.5° ± 1.0° (p = .0625), 1.0 ± 0.8 mm (p = .0313), and 0.2 ± 0.3 mm (p = .156) in AR, LT, and AT, respectively. Compared with partial facetectomy, wide posterior release produced an average additional increase of 8.1° ± 4.0° (p = .0312), 2.0 ± 2.2 mm (p = .4062), and 1.1 ± 1.0 mm (p = .0625) in AR, LT, and AT, respectively. Full discectomy produced 201%, 161%, and 153% of the motion relative to wide posterior release in AR, LT, and AT, respectively (p = .0043, .0087, and .0173). Partial discectomy and wide posterior release proved statistically equivalent.

Conclusions: Wide posterior release of the thoracolumbar spine allows significant correction and may be superior to inferior facetectomy in axial rotation. Although complete discectomy with PLL resection would likely allow greater correction, a more clinically realistic partial discectomy confers similar corrective potential in vitro compared with wide posterior release.

Level Of Evidence: Not applicable.
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http://dx.doi.org/10.1016/j.jspd.2018.09.004DOI Listing
May 2019

Optimization of compressive loading parameters to mimic in vivo cervical spine kinematics in vitro.

J Biomech 2019 04 7;87:107-113. Epub 2019 Mar 7.

Department of Orthopaedic Surgery, University of Texas Health Science Center, Houston, TX, USA.

The human cervical spine supports substantial compressive load in vivo. However, the traditional in vitro testing methods rarely include compressive loads, especially in investigations of multi-segment cervical spine constructs. Previously, a systematic comparison was performed between the standard pure moment with no compressive loading and published compressive loading techniques (follower load - FL, axial load - AL, and combined load - CL). The systematic comparison was structured a priori using a statistical design of experiments and the desirability function approach, which was chosen based on the goal of determining the optimal compressive loading parameters necessary to mimic the segmental contribution patterns exhibited in vivo. The optimized set of compressive loading parameters resulted in in vitro segmental rotations that were within one standard deviation and 10% of average percent error of the in vivo mean throughout the entire motion path. As hypothesized, the values for the optimized independent variables of FL and AL varied dynamically throughout the motion path. FL was not necessary at the extremes of the flexion-extension (FE) motion path but peaked through the neutral position, whereas, a large negative value of AL was necessary in extension and increased linearly to a large positive value in flexion. Although further validation is required, the long-term goal is to develop a "physiologic" in vitro testing method, which will be valuable for evaluating adjacent segment effect following spinal fusion surgery, disc arthroplasty instrumentation testing and design, as well as mechanobiology experiments where correct kinematics and arthrokinematics are critical.
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http://dx.doi.org/10.1016/j.jbiomech.2019.02.022DOI Listing
April 2019

Non-uniform strain distribution in anterolateral capsule of knee: Implications for surgical repair.

J Orthop Res 2019 05 28;37(5):1025-1032. Epub 2019 Mar 28.

Orthopaedic Robotics Laboratory, University of Pittsburgh, 408 Center for Bioengineering, 300 Technology Drive, Pittsburgh, 15219, Pennsylvania.

The existence of a ligamentous structure within the anterolateral capsule, which can be injured in combination with the anterior cruciate ligament, has been debated. Therefore, the purpose of this study was to determine the magnitude and direction of the strain in the anterolateral capsule in response to external loads applied to the knee. The anterolateral capsule was hypothesized to not function like a traditional ligament. A 6-degree-of-freedom robotic testing system was used to apply ten external loads to human cadaveric knees (n = 7) in the intact and anterior cruciate ligament (ACL) deficient states. The position of strain markers was recorded on the midsubstance of the anterolateral capsule during the resulting joint kinematics to determine the magnitude and direction of the maximum principal strain. The peak maximum principal strain ranged from 22% to 52% depending on the loading condition. When histograms of strain magnitude values were analyzed to determine strain uniformity, the mean kurtosis was 1.296 ± 0.955, lower than a typical ligament, and the mean variance was 0.015 ± 0.008, higher than a typical ligament. The mean angles of the strain direction vectors compared to the proposed ligament ranged between 38° and 130° (p < 0.05). The magnitude of the maximum principal strain in the anterolateral capsule is much larger than a typical ligament and does not demonstrate a uniform strain distribution. The direction of strain is also not aligned with the proposed ligament. Clinical Significance: Reconstruction methods using tendons will not produce normal joint function due to replacement of a multi-axial structure with a uni-axial structure. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.
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http://dx.doi.org/10.1002/jor.24270DOI Listing
May 2019

Verification of a Portable Motion Tracking System for Remote Management of Physical Rehabilitation of the Knee.

Sensors (Basel) 2019 Feb 28;19(5). Epub 2019 Feb 28.

Department of Orthopaedic Surgery, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA.

Rehabilitation following knee injury or surgery is critical for recovery of function and independence. However, patient non-adherence remains a significant barrier to success. Remote rehabilitation using mobile health (mHealth) technologies have potential for improving adherence to and execution of home exercise. We developed a remote rehabilitation management system combining two wireless inertial measurement units (IMUs) with an interactive mobile application and a web-based clinician portal (interACTION). However, in order to translate interACTION into the clinical setting, it was first necessary to verify the efficacy of measuring knee motion during rehabilitation exercises for physical therapy and determine if visual feedback significantly improves the participant's ability to perform the exercises correctly. Therefore, the aim of this study was to verify the accuracy of the IMU-based knee angle measurement system during three common physical therapy exercises, quantify the effect of visual feedback on exercise performance, and understand the qualitative experience of the user interface through survey data. A convenience sample of ten healthy control participants were recruited for an IRB-approved protocol. Using the interACTION application in a controlled laboratory environment, participants performed ten repetitions of three knee rehabilitation exercises: heel slides, short arc quadriceps contractions, and sit-to-stand. The heel slide exercise was completed without feedback from the mobile application, then all exercises were performed with visual feedback. Exercises were recorded simultaneously by the IMU motion tracking sensors and a video-based motion tracking system. Validation showed moderate to good agreement between the two systems for all exercises and accuracy was within three degrees. Based on custom usability survey results, interACTION was well received. Overall, this study demonstrated the potential of interACTION to measure range of motion during rehabilitation exercises for physical therapy and visual feedback significantly improved the participant's ability to perform the exercises correctly.
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http://dx.doi.org/10.3390/s19051021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6427361PMC
February 2019

Biomechanical contributions of upper cervical ligamentous structures in Type II odontoid fractures.

J Biomech 2019 01 22;83:28-33. Epub 2018 Nov 22.

Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA. Electronic address:

Fractures of the odontoid present frequently in spinal trauma, and Type II odontoid fractures, occurring at the junction of the odontoid process and C2 vertebrae, represent the bulk of all traumatic odontoid fractures. It is currently unclear what soft-tissue stabilizers contribute to upper cervical motion in the setting of a Type II odontoid fracture, and evaluation of how concomitant injury contributes to cervical stability may inform surgical decision-making as well as allow for the creation of future, accurate, biomechanical models of the upper cervical spine. The objective of the current study was to determine the contribution of soft-tissue stabilizers in the upper cervical spine following a Type II odontoid fracture. Eight cadaveric C0-C2 specimens were evaluated using a robotic testing system with motion tracking. The unilateral facet capsule (UFC) and anterior longitudinal ligament (ALL) were serially resected to determine their biomechanical role following odontoid fracture. Range of motion (ROM) and moment at the end of intact specimen replay were the primary outcomes. We determined that fracture of the odontoid significantly increases motion and decreases resistance to intact motion for flexion-extension (FE), axial rotation (AR), and lateral bending (LB). Injury to the UFC increased AR by 3.2° and FE by 3.2°. ALL resection did not significantly increase ROM or decrease end-point moment. The UFC was determined to contribute to 19% of intact flexion resistance and 24% of intact AR resistance. Overall, we determined that Type II fracture of the odontoid is a significant biomechanical destabilizer and that concurrent injury to the UFC further increases upper cervical ROM and decreases resistance to motion in a cadaveric model of traumatic Type II odontoid fractures.
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http://dx.doi.org/10.1016/j.jbiomech.2018.11.014DOI Listing
January 2019

Influence of follower load application on moment-rotation parameters and intradiscal pressure in the cervical spine.

J Biomech 2018 07 15;76:167-172. Epub 2018 Jun 15.

Ferguson Laboratory for Spine Research, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, United States.

The objective of this study was to implement a follower load (FL) device within a robotic (universal force-moment sensor) testing system and utilize the system to explore the effect of FL on multi-segment cervical spine moment-rotation parameters and intradiscal pressure (IDP) at C45 and C56. Twelve fresh-frozen human cervical specimens (C3-C7) were biomechanically tested in a robotic testing system to a pure moment target of 2.0 Nm for flexion and extension (FE) with no compression and with 100 N of FL. Application of FL was accomplished by loading the specimens with bilateral cables passing through cable guides inserted into the vertebral bodies and attached to load controlled linear actuators. FL significantly increased neutral zone (NZ) stiffness and NZ width but resulted in no change in the range of motion (ROM) or elastic zone stiffness. C45 and C56 IDP measured in the neutral position were significantly increased with application of FL. The change in IDP with increasing flexion rotation was not significantly affected by the application of FL, whereas the change in IDP with increasing extension rotation was significantly reduced by the application of FL. Application of FL did not appear to affect the specimen's quantity of motion (ROM) but did affect the quality (the shape of the curve). Regarding IDP, the effects of adding FL compression approximates the effect of the patient going from supine to a seated position (FL compression increased the IDP in the neutral position). The change in IDP with increasing flexion rotation was not affected by the application of FL, but the change in IDP with increasing extension rotation was, however, significantly reduced by the application of FL.
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http://dx.doi.org/10.1016/j.jbiomech.2018.05.031DOI Listing
July 2018

Adaptation of a clinical fixation device for biomechanical testing of the lumbar spine.

J Biomech 2018 03 5;69:164-168. Epub 2018 Jan 5.

Ferguson Laboratory for Spine Research, Department of Orthopedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA.

In-vitro biomechanical testing is widely performed for characterizing the load-displacement characteristics of intact, injured, degenerated, and surgically repaired osteoligamentous spine specimens. Traditional specimen fixture devices offer an unspecified rigidity of fixation, while varying in the associated amounts and reversibility of damage to and "coverage" of a specimen - factors that can limit surgical access to structures of interest during testing as well as preclude the possibility of testing certain segments of a specimen. Therefore, the objective of this study was to develop a specimen fixture system for spine biomechanical testing that uses components of clinically available spinal fixation hardware and determine whether the new system provides sufficient rigidity for spine biomechanical testing. Custom testing blocks were mounted into a robotic testing system and the angular deflection of the upper fixture was measured indirectly using linear variable differential transformers. The fixture system had an overall stiffness 37.0, 16.7 and 13.3 times greater than a typical human functional spine unit for the flexion/extension, axial rotation and lateral bending directions respectively - sufficient rigidity for biomechanical testing. Fixture motion when mounted to a lumbar spine specimen revealed average motion of 0.6, 0.6, and 1.5° in each direction. This specimen fixture method causes only minimal damage to a specimen, permits testing of all levels of a specimen, and provides for surgical access during testing.
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http://dx.doi.org/10.1016/j.jbiomech.2017.12.029DOI Listing
March 2018

The Role of Extra-Articular Tenodesis in Combined ACL and Anterolateral Capsular Injury.

J Bone Joint Surg Am 2017 Oct;99(19):1654-1660

1Orthopaedic Robotics Laboratory (D.G., S.I., K.M.B., A.A.R.-A., F.H.F., R.E.D., and V.M.) and Departments of Orthopaedic Surgery (D.G., S.I., A.A.R.-A., F.H.F., and V.M.) and Bioengineering (K.M.B. and R.E.D.), University of Pittsburgh, Pittsburgh, Pennsylvania 2Trauma Department, Hannover Medical School (MHH), Hannover, Germany.

Background: The "gold standard" treatment of anterolateral capsular injuries in anterior cruciate ligament (ACL)-deficient knees has not been determined. The purpose of this study was to determine the effects of ACL reconstruction and extra-articular reconstruction on joint motion in the ACL-deficient knee and in the combined ACL and anterolateral capsule-deficient knee.

Methods: An anterior tibial load of 134 N and internal tibial torque of 7 Nm were applied to 7 fresh-frozen cadaveric knees using a robotic testing system continuously throughout the range of flexion. The resulting joint motion was recorded for 6 knee states: intact, ACL-deficient, ACL-reconstructed, combined ACL and anterolateral capsule-deficient, ACL-reconstructed + anterolateral capsule-deficient, and ACL-reconstructed + extra-articular tenodesis.

Results: Anterior tibial translation of the ACL-reconstructed + anterolateral capsule-deficient knee in response to an anterior tibial load was restored to that of the intact knee at all knee-flexion angles (p > 0.05). However, for this knee state, internal tibial rotation in response to internal tibial torque was not restored to that of the intact knee at 60° or 90° of knee flexion (p < 0.05). For the knee state of ACL-reconstructed + extra-articular tenodesis, internal rotation in response to internal tibial torque was restored to the motion of the intact knee at each of the tested knee-flexion angles (p > 0.05). Compared with the intact knee, 2 of 7 specimens showed decreased internal tibial rotation with ACL reconstruction + extra-articular tenodesis.

Conclusions: In this study, an extra-articular tenodesis was necessary to restore rotatory knee stability in response to internal tibial torque in a combined ACL and anterolateral capsule-deficient knee. The amount of rotatory knee instability should be carefully assessed to avoid over-constraint of the knee in these combined ligament-reconstruction procedures.

Clinical Relevance: On the basis of our findings, the surgical procedure needs to be personalized depending on the amount of rotatory knee instability in the injured knee and the amount of rotation in the contralateral knee.
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http://dx.doi.org/10.2106/JBJS.16.01462DOI Listing
October 2017

In situ force in the anterior cruciate ligament, the lateral collateral ligament, and the anterolateral capsule complex during a simulated pivot shift test.

J Orthop Res 2018 03 29;36(3):847-853. Epub 2017 Aug 29.

Orthopaedic Robotics Laboratory, Department of Orthopaedic Surgery and Bioengineering, University of Pittsburgh, 300 Technology Drive, Pittsburgh, 15219, Pennsylvania.

The role of the anterolateral capsule complex in knee rotatory stability remains controversial. Therefore, the objective of this study was to determine the in situ forces in the anterior cruciate ligament (ACL), the anterolateral capsule, the lateral collateral ligament (LCL), and the forces transmitted between each region of the anterolateral capsule in response to a simulated pivot shift test. A robotic testing system applied a simulated pivot shift test continuously from full extension to 90° of flexion to intact cadaveric knees (n = 7). To determine the magnitude of the in situ forces, kinematics of the intact knee were replayed in position control mode after the following procedures were performed: (i) ACL transection; (ii) capsule separation; (iii) anterolateral capsule transection; and (iii) LCL transection. A repeated measures ANOVA was performed to compare in situ forces between each knee state (*p < 0.05). The in situ force in the ACL was significantly greater than the forces transmitted between each region of the anterolateral capsule at 5° and 15° of flexion but significantly lower at 60°, 75°, and 90° of flexion. This study demonstrated that the ACL is the primary rotatory stabilizer at low flexion angles during a simulated pivot shift test in the intact knee, but the anterolateral capsule plays an important secondary role at flexion angles greater than 60°. Furthermore, the contribution of the "anterolateral ligament" to rotatory knee stability in this study was negligible during a simulated pivot shift test. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:847-853, 2018.
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http://dx.doi.org/10.1002/jor.23676DOI Listing
March 2018

Biomechanical Evaluation of Transpedicular Nucleotomy With Intact Annulus Fibrosus.

Spine (Phila Pa 1976) 2017 Feb;42(4):E193-E201

Department of Orthopedic and Traumatology, University Campus BioMedico of Rome, Rome, Italy.

Study Design: Biomechanical testing of partially nucleotomized ovine cadaveric spines.

Objective: To explore how the nucleus pulposus (NP) affects the biomechanical behavior of the intervertebral disc (IVD) by performing a partial nucleotomy via the transpedicular approach.

Summary Of Background Data: Mechanical loading represents a crucial part of IVD homeostasis. However, traditional regenerative strategies require violation of the annulus fibrosus (AF) resulting in significant alteration of joint mechanics. The transpedicular nucleotomy represents a suitable method to create a cavity into the NP, as a model to study IVD regeneration with intact AF.

Methods: A total of 30 ovine-lumbar- functional spinal units (FSUs) (L1-L6) randomly assigned to 5 groups: control; transpedicular tunnel (TT); TT + polymethylmethacrylate (PMMA) to repair the bone tunnel; nucleotomy; nucleotomy + PMMA. Flexion/extension, lateral-bending, and axial-rotation were evaluated under adaptive displacement control. Axial compression was applied for 15 cycles of preconditioning followed by 1 hour of constant compression. Viscoelastic behavior was modeled and parameterized.

Results: TT has minimal effects on rotational biomechanics. The nucleotomy increases ROM and neutral zone (NZ) displacement width whereas decreasing NZ stiffness. TT + PMMA has small effects in terms of ROM. Nucleotomy + PMMA brings ROM back to the control, increases NZ stiffness, and decreases NZ displacement width. The nucleotomy tends to increase the rate of early creep. TT reduces early and late damping. The use of PMMA increased late elastic stiffness (S2) and reduced viscous damping (η2) culminating in faster resolution of creep.

Conclusion: Biomechanical properties of NP are crucial for IVD repair. This study demonstrated that TT does not affect rotational stability whereas partial nucleotomy with intact AF induce rotational instability, highlighting the central role of NP in early stages of IDD. Therefore, this model represents a successful platform to validate and optimize disc regeneration strategies.

Level Of Evidence: N/A.
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http://dx.doi.org/10.1097/BRS.0000000000001762DOI Listing
February 2017

Biomechanical evaluation of knee endpoint during anterior tibial loading: Implication for physical exams.

Knee 2017 Mar 8;24(2):258-263. Epub 2017 Feb 8.

Orthopaedic Robotics Laboratory, Department of Orthopaedic Surgery, Department of Bioengineering, University of Pittsburgh, 408 Center for Bioengineering, 300 Technology Drive, Pittsburgh, PA 15219, USA; Department of Orthopaedic Surgery, University of Pittsburgh, Kaufman Building Suite 1011, 3471 Fifth Avenue, Pittsburgh, PA 15213, USA; Department of Bioengineering, University of Pittsburgh, 302 Benedum Hall, 3700 O'Hara Street, Pittsburgh, PA 15260, USA. Electronic address:

Background: Physical exams that apply anterior tibial loads are typically used to evaluate knees with anterior cruciate ligament (ACL) injuries. The amount of anterior tibial translation that occurs during these exams can be difficult to assess due to a "soft" endpoint. Therefore, the objective of this study is to determine the biomechanical characteristics of the endpoint for the intact and ACL deficient knee using quantitative criteria.

Methods: Eight porcine knees were tested using a robotic testing system. An 89N anterior tibial load was applied to the intact and ACL deficient knee at 30°, 45°, 60° and 75° of flexion. The stiffness of the toe and linear regions was determined from the load-translation curve. The width of the transition region was defined by the distance between the points where the best-fit lines used to define the stiffness of the toe and linear regions diverged from the load-translation curve.

Results: Stiffness of the toe and linear regions significantly decreased after transecting the ACL at all flexion angles (71-85% and 38-62%, respectively). Width of the transition region was significantly increased in the ACL deficient knee at all flexion angles (approximately four to five times and four to nine times, respectively).

Conclusions: The novel quantitative criteria developed in this study have the potential to be deployed in clinical practice by coupling them with data from knee arthrometers that are commonly used in clinical practice. Thus, additional information from the load-translation curve can be provided to improve the diagnosis of ACL injury.
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http://dx.doi.org/10.1016/j.knee.2016.11.015DOI Listing
March 2017

The Anterolateral Capsule of the Knee Behaves Like a Sheet of Fibrous Tissue.

Am J Sports Med 2017 Mar 8;45(4):849-855. Epub 2016 Dec 8.

Orthopaedic Robotics Laboratory, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.

Background: The function of the anterolateral capsule of the knee has not been clearly defined. However, the contribution of this region of the capsule to knee stability in comparison with other anterolateral structures can be determined by the relative force that each structure carries during loading of the knee. Purpose/Hypothesis: The purpose of this study was to determine the forces in the anterolateral structures of the intact and anterior cruciate ligament (ACL)-deficient knee in response to an anterior tibial load and internal tibial torque. It was hypothesized that the anterolateral capsule would not function like a traditional ligament (ie, transmitting forces only along its longitudinal axis).

Study Design: Controlled laboratory study.

Methods: Loads (134-N anterior tibial load and 7-N·m internal tibial torque) were applied continuously during flexion to 7 fresh-frozen cadaveric knees in the intact and ACL-deficient state using a robotic testing system. The lateral collateral ligament (LCL) and the anterolateral capsule were separated from the surrounding tissue and from each other. This was done by performing 3 vertical incisions: lateral to the LCL, medial to the LCL, and lateral to the Gerdy tubercle. Attachments of the LCL and anterolateral capsule were detached from the underlying tissue (ie, meniscus), leaving the insertions and origins intact. The force distribution in the anterolateral capsule, ACL, and LCL was then determined at 30°, 60°, and 90° of knee flexion using the principle of superposition.

Results: In the intact knee, the force in the ACL in response to an anterior tibial load was greater than that in the other structures ( P < .001). However, in response to an internal tibial torque, no significant differences were found between the ACL, LCL, and forces transmitted between each region of the anterolateral capsule after capsule separation. The anterolateral capsule experienced smaller forces (~50% less) compared with the other structures ( P = .048). For the ACL-deficient knee in response to an anterior tibial load, the force transmitted between each region of the anterolateral capsule was 434% greater than was the force in the anterolateral capsule ( P < .001) and 54% greater than the force in the LCL ( P = .036) at 30° of flexion. In response to an internal tibial torque at 30°, 60°, or 90° of knee flexion, no significant differences were found between the force transmitted between each region of the anterolateral capsule and the LCL. The force in the anterolateral capsule was significantly smaller than that in the other structures at all knee flexion angles for both loading conditions ( P = .004 for anterior tibial load and P = .04 for internal tibial torque).

Conclusion: The anterolateral capsule carries negligible forces in the longitudinal direction, and the forces transmitted between regions of the capsule were similar to the forces carried by the other structures at the knee, suggesting that it does not function as a traditional ligament. Thus, the anterolateral capsule should be considered a sheet of tissue.

Clinical Relevance: Surgical repair techniques for the anterolateral capsule should restore the ability of the tissue to transmit forces between adjacent regions of the capsule rather than along its longitudinal axis.
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http://dx.doi.org/10.1177/0363546516674477DOI Listing
March 2017

Mechanical role of the posterior column components in the cervical spine.

Eur Spine J 2016 07 6;25(7):2129-38. Epub 2016 Apr 6.

Department of Orthopaedic Surgery, University of Pittsburgh, 200 Lothrop Street, E1641 Biomedical Science Tower, Pittsburgh, PA, 15261, USA.

Purpose: To quantify the mechanical role of posterior column components in human cervical spine segments.

Methods: Twelve C6-7 segments were subjected to resection of (1) suprasinous/interspinous ligaments (SSL/ISL), (2) ligamenta flavum (LF), (3) facet capsules, and (4) facets. A robot-based testing system performed repeated flexibility testing of flexion-extension (FE), axial rotation (AR), and lateral bending (LB) to 2.5Nm and replayed kinematics from intact flexibility tests for each state. Range-of-motion, stiffness, moment resistance and resultant forces were calculated.

Results: The LF contributes largely to moment resistance, particularly in flexion. Facet joints were primary contributors to AR and LB mechanics. Moment/force responses were more sensitive and precise than kinematic outcomes.

Conclusions: The LF is mechanically important in the cervical spine; its injury could negatively impact load distribution. Damage to facets in a flexion injury could lead to AR or LB hypermobility. Quantifying the contribution of spinal structures to moment resistance is a sensitive, precise process for characterizing structural mechanics.
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http://dx.doi.org/10.1007/s00586-016-4541-1DOI Listing
July 2016

Influence of varying compressive loading methods on physiologic motion patterns in the cervical spine.

J Biomech 2016 Jan 27;49(2):167-72. Epub 2015 Nov 27.

Ferguson Laboratory for Spine Research, Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.

The human cervical spine supports substantial compressive load in-vivo arising from muscle forces and the weight of the head. However, the traditional in-vitro testing methods rarely include compressive loads, especially in investigations of multi-segment cervical spine constructs. Various methods of modeling physiologic loading have been reported in the literature including axial forces produced with inclined loading plates, eccentric axial force application, follower load, as well as attempts to individually apply/model muscle forces in-vitro. The importance of proper compressive loading to recreate the segmental motion patterns exhibited in-vivo has been highlighted in previous studies. However, appropriate methods of representing the weight of head and muscle loading are currently unknown. Therefore, a systematic comparison of standard pure moment with no compressive loading versus published and novel compressive loading techniques (follower load - FL, axial load - AL, and combined load - CL) was performed. The present study is unique in that a direct comparison to continuous cervical kinematics over the entire extension to flexion motion path was possible through an ongoing intra-institutional collaboration. The pure moment testing protocol without compression or with the application of follower load was not able to replicate the typical in-vivo segmental motion patterns throughout the entire motion path. Axial load or a combination of axial and follower load was necessary to mimic the in-vivo segmental contributions at the extremes of the extension-flexion motion path. It is hypothesized that dynamically altering the compressive loading throughout the motion path is necessary to mimic the segmental contribution patterns exhibited in-vivo.
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http://dx.doi.org/10.1016/j.jbiomech.2015.11.045DOI Listing
January 2016

Novel technique for evaluation of knee function continuously through the range of flexion.

J Biomech 2015 Oct 28;48(13):3728-31. Epub 2015 Aug 28.

Orthopaedic Robotics Laboratory, Department of Orthopaedic Surgery, Department of Bioengineering, University of Pittsburgh, PA 15219, USA; Department of Bioengineering, University of Pittsburgh, 302 Benedum Hall, 3700O'Hara Street, Pittsburgh, PA 15260, USA. Electronic address:

Previous research has utilized robots to examine joint kinematics and in situ forces in response to loads applied at discrete flexion angles (static method). Recently, studies have applied loads continuously throughout flexion (continuous flexion method). However, the joint kinematics resulting from each of these methods have not been directly compared. Therefore, the objective of this study was to utilize a robotic testing system to compare kinematics and in situ forces of porcine knees in response to 89 N of anterior tibial load and 4 Nm of internal tibial torque between the static method (loads applied at 30°, 45°, 60°, and 75° of flexion) and the continuous flexion method (measured continuously from 30-75° of flexion) for both the anterior cruciate ligament (ACL) intact and ACL deficient (ACLD) knees. When anterior tibial load was applied the average differences in anterior tibial translation between the two methods for the intact state was 0.5±0.0 mm and for the ACLD state was 0.3±0.2 mm. The difference in the in situ forces in the ACL was 1.6±0.9 N. When internal tibial torque was applied the average differences in the resultant internal tibial rotation for the intact state was 0.9±0.4° and for the ACLD state was 1.0±0.5°. The difference in the in situ forces in the ACL was 3.3±2.0 N. Both methods are equally efficient in detecting significant differences (p<0.05) between intact and ACL deficient knee states. The continuous flexion method was also shown to be more efficient than the static method and provides continuous data on knee function throughout the range of motion.
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http://dx.doi.org/10.1016/j.jbiomech.2015.08.019DOI Listing
October 2015

Experimental Execution of the Simulated Pivot-Shift Test: A Systematic Review of Techniques.

Arthroscopy 2015 Dec 28;31(12):2445-54.e2. Epub 2015 Aug 28.

Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, U.S.A.; Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, U.S.A.; Orthopaedic Robotics Laboratory, University of Pittsburgh, Pittsburgh, Pennsylvania, U.S.A.. Electronic address:

Purpose: To conduct a systematic review to identify and summarize the various techniques that have been used to simulate the pivot-shift test in vitro.

Methods: Medline, Embase, and the Cochrane Library were screened for studies involving the simulated pivot-shift test in human cadaveric knees published between 1946 and May 2014. Study parameters including sample size, study location, simulated pivot-shift technique, loads applied, knee flexion angles at which simulated pivot shift was tested, and kinematic evaluation tools were extracted and analyzed.

Results: Forty-eight studies reporting simulated pivot-shift testing on 627 cadaveric knees fulfilled the criteria. Reviewer inter-rater agreement for study selection showed a κ score of 0.960 (full-text review). Twenty-seven studies described the use of internal rotation torque, with a mean of 5.3 Nm (range, 1 to 18 Nm). Forty-seven studies described the use of valgus torque, with a mean of 8.8 Nm (range, 1 to 25 Nm). Four studies described the use of iliotibial tract tension, ranging from 10 to 88 N. Regarding static simulated pivot-shift test techniques, 100% of the studies performed testing at 30° of knee flexion, and the most tested range of motion in the continuous tests was 0° to 90°. Anterior tibial translation was the most analyzed parameter during the simulated pivot-shift test, being used in 45 studies. In 22% of the studies, a robotic system was used to simulate the pivot-shift test. Robotic systems were shown to have better control of the loading system and higher tracking system accuracy.

Conclusions: This study provides a reference for investigators who desire to apply simulated pivot shift in their in vitro studies. It is recommended to simulate the pivot-shift test using a 10-Nm valgus torque and 5-Nm internal rotation torque. Knee flexion of 30° is mandatory for testing.

Level Of Evidence: Level IV, systematic review of basic science studies.
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http://dx.doi.org/10.1016/j.arthro.2015.06.027DOI Listing
December 2015

Biomechanical comparison of ponte osteotomy and discectomy.

Spine (Phila Pa 1976) 2015 Feb;40(3):E141-5

*Department of Orthopaedic Surgery, Ferguson Laboratory, University of Pittsburgh, Pittsburgh, PA †Department of Spinal Surgery, the First Affiliated Hospital of University of South China, Hengyang City, Hunan Province, China ‡Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA; and §Children's Hospital of Pittsburgh of UPMC, Pittsburgh, PA.

Study Design: Biomechanical cadaver study.

Objective: To evaluate the relative effectiveness of Ponte osteotomies for spinal release in deformity correction.

Summary Of Background Data: Controversy exists as to the role of Ponte osteotomy in deformity correction surgery. Very little has been written about the biomechanical effects of Ponte osteotomy. Past biomechanical studies have been limited to application of forces through endplates, single functional units, or lack of comparison with anterior release.

Methods: Twelve fresh-frozen human full thoracic spinal units were tested for motion in axial rotation, flexion/extension, and lateral bending in a custom-designed robotic environment. Testing was repeated after sequential facetectomy and Ponte osteotomy (6 specimens) and compared with partial and full discectomy (6 specimens).

Results: Motion in axial rotation is increased 21% by Ponte osteotomy compared with 35% for full discectomy. Anterior displacement of the spinal column, creating lordosis, was increased 15% by Ponte osteotomy and 40% by full discectomy. Posterior displacement of the spinal column, creating kyphosis, was increased 23% by Ponte osteotomy and 89% by full discectomy. Finally, in coronal force application the Ponte osteotomy had virtually no effect (2%) compared with 40% increased motion by full discectomy.

Conclusion: Posterior Ponte osteotomy releases produced more motion than facetectomy alone in axial rotation and sagittal correction maneuvers, but had no effect on coronal correction. Anterior discectomy release destabilized spinal column significantly more than posterior releases in all force applications. Despite ample clinical experience demonstrating the effectiveness of posterior-only surgery, the biomechanical effect of Ponte osteotomies is modest.

Level Of Evidence: N/A.
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http://dx.doi.org/10.1097/BRS.0000000000000697DOI Listing
February 2015

Needle puncture in rabbit functional spinal units alters rotational biomechanics.

J Spinal Disord Tech 2015 Apr;28(3):E146-53

Departments of *Physical Medicine and Rehabilitation †Bioengineering ‡Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA §Finance and Trade Hospital of Hunan Province, Tianxin, Changsha ∥The First Affiliated Hospital of University of South China, Xiangtan, Hunan, China.

Study Design: An in vitro biomechanical study for rabbit lumbar functional spinal units (FSUs) using a robot-based spine testing system.

Objective: To elucidate the effect of annular puncture with a 16 G needle on mechanical properties in flexion/extension, axial rotation, and lateral bending.

Summary Of Background Data: Needle puncture of the intervertebral disk has been shown to alter mechanical properties of the disk in compression, torsion, and bending. The effect of needle puncture in FSUs, where intact spinal ligaments and facet joints may mitigate or amplify these changes in the disk, on spinal motion segment stability subject to physiological rotations remains unknown.

Methods: Rabbit FSUs were tested using a robot testing system whose force/moment and position precision were assessed to demonstrate system capability. Flexibility testing methods were developed by load-to-failure testing in flexion/extension, axial rotation, and lateral bending. Subsequent testing methods were used to examine a 16 G needle disk puncture and No. 11 blade disk stab (positive control for mechanical disruption). Flexibility testing was used to assess segmental range-of-motion (degrees), neutral zone stiffness (N m/degrees) and width (degrees and N m), and elastic zone stiffness before and after annular injury.

Results: The robot-based system was capable of performing flexibility testing on FSUs-mean precision of force/moment measurements and robot system movements were <3% and 1%, respectively, of moment-rotation target values. Flexibility moment targets were 0.3 N m for flexion and axial rotation and 0.15 N m for extension and lateral bending. Needle puncture caused significant (P<0.05) changes only in flexion/extension range-of-motion and neutral zone stiffness and width (N m) compared with preintervention. No. 11 blade-stab significantly increased range-of-motion in all motions, decreased neutral zone stiffness and width (N m) in flexion/extension, and increased elastic zone stiffness in flexion and lateral bending.

Conclusions: These findings suggest that disk puncture and stab can destabilize FSUs in primary rotations.
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http://dx.doi.org/10.1097/BSD.0000000000000196DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4382369PMC
April 2015

Republished research: Impact of autologous blood injections in treatment of mid-portion Achilles tendinopathy: double blind randomised controlled trial.

Br J Sports Med 2014 Sep;48(17):1334

Department of General Practice and Primary Health Care, School of Population Health, Faculty of Medical and Health Sciences, University of Auckland, New Zealand.

Study Question: Do peritendinous autologous blood injections improve pain and function in people with mid-portion Achilles tendinopathy?

Summary Answer: The administration of two unguided peritendinous autologous blood injections one month apart, in addition to a standardised eccentric training programme, provides no additional benefit in the treatment of mid-portion Achilles tendinopathy.

What Is Known And What This Paper Adds: Several studies have suggested that injection of autologous blood can help in the treatment of various tendinopathies. There is a lack of high quality evidence showing relevant benefit for autologous blood injections, particularly in the management of mid-portion Achilles tendinopathy. We found no additional reduction in pain or improvement in function when these injections were combined with an eccentric calf training programme.
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http://dx.doi.org/10.1136/bjsports-2013-f2310repDOI Listing
September 2014

In vitro spine testing using a robot-based testing system: comparison of displacement control and "hybrid control".

J Biomech 2013 Jun 21;46(10):1663-9. Epub 2013 May 21.

Spine Research Laboratory, Department of Orthopedic Surgery, University of Pittsburgh School of Medicine, 200 Lothrop Street, C-313 PUH, Pittsburgh, PA 15213, USA.

The two leading control algorithms for in-vitro spine biomechanical testing-"load control" and "displacement control"-are limited in their lack of adaptation to changes in the load-displacement response of a spine specimen-pointing to the need for sufficiently sophisticated control algorithms that are able to govern the application of loads/motions to a spine specimen in a more realistic, adaptive manner. A robotics-based spine testing system was programmed with a novel hybrid control algorithm combining "load control" and "displacement control" into a single, robust algorithm. Prior to in-vitro cadaveric testing, preliminary testing of the new algorithm was performed using a rigid-body-spring model with known structural properties. The present study also offers a direct comparison between "hybrid control" and "displacement control". The hybrid control algorithm enabled the robotics-based spine testing system to apply pure moments to an FSU (in flexion/extension, lateral bending, or axial rotation) in an unconstrained manner through active control of secondary translational/rotational degrees-of-freedom-successfully minimizing coupled forces/moments. The characteristic nonlinear S-shaped curves of the primary moment-rotation responses were consistent with previous reports of the FSU having a region of low stiffness (neutral zone) bounded by regions of increasing stiffness (elastic zone). Direct comparison of "displacement control" and "hybrid control" showed that hybrid control was able to actively minimize off-axis forces and resulted in larger neutral zone and range of motion.
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http://dx.doi.org/10.1016/j.jbiomech.2013.04.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3718291PMC
June 2013

Impact of autologous blood injections in treatment of mid-portion Achilles tendinopathy: double blind randomised controlled trial.

BMJ 2013 Apr 18;346:f2310. Epub 2013 Apr 18.

Sydney Sports Medicine Centre, Sydney Olympic Park, NSW 2127, Australia.

Objective: To assess the effectiveness of two peritendinous autologous blood injections in addition to a standardised eccentric calf strengthening programme in improving pain and function in patients with mid-portion Achilles tendinopathy.

Design: Single centre, participant and single assessor blinded, parallel group, randomised, controlled trial.

Setting: Single sports medicine clinic in New Zealand.

Participants: 53 adults (mean age 49, 53% men) with symptoms of unilateral mid-portion Achilles tendinopathy for at least three months. Participants were excluded if they had a history of previous Achilles tendon rupture or surgery or had undergone previous adjuvant treatments such as injectable therapies, glyceryl trinitrate patches, or extracorporeal shockwave therapy.

Interventions: All participants underwent two unguided peritendinous injections one month apart with a standardised protocol. The treatment group had 3 mL of their own whole blood injected while the control group had no substance injected (needling only). Participants in both groups carried out a standardised and monitored 12 week eccentric calf training programme. Follow-up was at one, two, three and six months.

Main Outcome Measures: The primary outcome measure was the change in symptoms and function from baseline to six months with the Victorian Institute of Sport Assessment-Achilles (VISA-A) score. Secondary outcomes were the participant's perceived rehabilitation and their ability to return to sport.

Results: 26 participants were randomly assigned to the treatment group and 27 to the control group. In total, 50 (94%) completed the six month study, with 25 in each group. Clear and clinically worthwhile improvements in the VISA-A score were evident at six months in both the treatment (change in score 18.7, 95% confidence interval 12.3 to 25.1) and control (19.9, 13.6 to 26.2) groups. The overall effect of treatment was not significant (P=0.689) and the 95% confidence intervals at all points precluded clinically meaningful benefit or harm. There was no significant difference between groups in secondary outcomes or in the levels of compliance with the eccentric calf strengthening programme. No adverse events were reported.

Conclusion: The administration of two unguided peritendinous autologous blood injections one month apart, in addition to a standardised eccentric training programme, provides no additional benefit in the treatment of mid-portion Achilles tendinopathy.

Trial Registration: Australian New Zealand Clinical Trials Registry ACTRN12610000824066, WHO U1111-1117-2641.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3629924PMC
http://dx.doi.org/10.1136/bmj.f2310DOI Listing
April 2013

Injection of human umbilical tissue-derived cells into the nucleus pulposus alters the course of intervertebral disc degeneration in vivo.

Spine J 2013 Mar 4;13(3):263-72. Epub 2013 Feb 4.

Department of Orthopedics, University of Pittsburgh Medical Center, 200 Lothrop St., Pittsburgh, PA 15213, USA.

Background Context: Patients often present to spine clinic with evidence of intervertebral disc degeneration (IDD). If conservative management fails, a safe and effective injection directly into the disc might be preferable to the risks and morbidity of surgery.

Purpose: To determine whether injecting human umbilical tissue-derived cells (hUTC) into the nucleus pulposus (NP) might improve the course of IDD.

Design: Prospective, randomized, blinded placebo-controlled in vivo study.

Patient Sample: Skeletally mature New Zealand white rabbits.

Outcome Measures: Degree of IDD based on magnetic resonance imaging (MRI), biomechanics, and histology.

Methods: Thirty skeletally mature New Zealand white rabbits were used in a previously validated rabbit annulotomy model for IDD. Discs L2-L3, L3-L4, and L4-L5 were surgically exposed and punctured to induce degeneration and then 3 weeks later the same discs were injected with hUTC with or without a hydrogel carrier. Serial MRIs obtained at 0, 3, 6, and 12 weeks were analyzed for evidence of degeneration qualitatively and quantitatively via NP area and MRI Index. The rabbits were sacrificed at 12 weeks and discs L4-L5 were analyzed histologically. The L3-L4 discs were fixed to a robotic arm and subjected to uniaxial compression, and viscoelastic displacement curves were generated.

Results: Qualitatively, the MRIs demonstrated no evidence of degeneration in the control group over the course of 12 weeks. The punctured group yielded MRIs with the evidence of disc height loss and darkening, suggestive of degeneration. The three treatment groups (cells alone, carrier alone, or cells+carrier) generated MRIs with less qualitative evidence of degeneration than the punctured group. MRI Index and area for the cell and the cell+carrier groups were significantly distinct from the punctured group at 12 weeks. The carrier group generated MRI data that fell between control and punctured values but failed to reach a statistically significant difference from the punctured values. There were no statistically significant MRI differences among the three treatment groups. The treated groups also demonstrated viscoelastic properties that were distinct from the control and punctured values, with the cell curve more similar to the punctured curve and the carrier curve and carrier+cells curve more similar to the control curve (although no creep differences achieved statistical significance). There was some histological evidence of improved cellularity and disc architecture in the treated discs compared with the punctured discs.

Conclusions: Treatment of degenerating rabbit intervertebral discs with hUTC in a hydrogel carrier solution might help restore the MRI, histological, and biomechanical properties toward those of nondegenerated controls. Treatment with cells in saline or a hydrogel carrier devoid of cells also might help restore some imaging, architectural, and physical properties to the degenerating disc. These data support the potential use of therapeutic cells in the treatment of disc degeneration.
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http://dx.doi.org/10.1016/j.spinee.2012.12.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4868072PMC
March 2013