Publications by authors named "Sophia N Sangiorgio"

56 Publications

Taper Material Loss in Total Hip Replacements: Is It Affected by Joint Friction?

J Bone Joint Surg Am 2022 05 15;104(9):796-804. Epub 2022 Feb 15.

The J. Vernon Luck, Sr., M.D. Orthopaedic Research Center, Orthopaedic Institute for Children in Alliance with UCLA, Los Angeles, California.

Background: Metal debris and corrosion products generated from the taper junctions of modular joint replacements have been recognized as contributors to failure. Therefore, understanding the factors associated with increased taper wear and corrosion is fundamental to improving implant performance.

Methods: A cohort of 85 large-diameter metal-on-metal heads and cups retrieved at revision surgery, after 10 to 96 months of service, was evaluated. First, metrology was conducted to quantify head taper material loss and implant articular surface wear. Then, joint frictional moments for each retrieved head-and-cup pair were measured during 10 cycles of simulated physiological gait in a biomechanical model. Taper material loss was evaluated for correlations with frictional moments, articular wear, head diameter, head-cup clearance, and time in vivo.

Results: Peak resultant frictional moments ranged from 9.1 to 26.3 Nm, averaging 17.3 ± 2.7 Nm. Fretting and corrosion damage during in vivo service resulted in material loss from the head tapers ranging between 0.04 and 25.57 mm3, compared with combined head and cup articular wear of 0.80 to 351.75 mm3 in this cohort. Taper material loss was not correlated with higher frictional moments (R = -0.20 to 0.11, p = 0.07 to 0.81). Higher frictional moments from axial rotation were correlated with higher head and cup wear (R = 0.33, p < 0.01). The correlation between taper material loss and head diameter was weak and did not reach statistical significance (R = 0.20, p = 0.07). Taper material loss was not correlated with nominal head-cup clearance (R = 0.06, p = 0.6). Finally, taper material loss increased significantly over time (R = 0.34, p < 0.01).

Conclusions: Despite serious concerns regarding trunnionosis, volumes of head taper wear were generally lower than those of articular surface wear. There was no statistical correlation between taper wear and frictional moments. Therefore, the results suggest that high friction in metal-on-metal implants does not contribute to higher material loss at the head taper, despite high bending moments.

Clinical Relevance: The amount of metal debris and corrosion products from taper junctions of the joint arthroplasties, widely recognized as an insidious cause of failure, was not correlated with joint frictional moments. Multiple factors affect taper wear: implant design, material, size, surface finish, and patient weight and activity level. However, in the present cohort, high friction of metal-on-metal total hip replacements likely did not contribute to increased volume of material loss at taper interfaces, despite increased moments at the locations of taper material loss.
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http://dx.doi.org/10.2106/JBJS.21.00579DOI Listing
May 2022

The lexicon for periprosthetic bone loss versus osteolysis after cervical disc arthroplasty: a systematic review.

Eur Spine J 2022 04 9;31(4):830-842. Epub 2022 Jan 9.

The J. Vernon Luck, Sr., M.D. Orthopaedic Research Center, Orthopaedic Institute for Children in Alliance With UCLA, 403 W. Adams Blvd, Los Angeles, CA, 90007, USA.

Background: Periprosthetic bone loss is a common observation following arthroplasty. Recognizing and understanding the nature of bone loss is vital as it determines the subsequent performance of the device and the overall outcome. Despite its significance, the term "bone loss" is often misused to describe inflammatory osteolysis, a complication with vastly different clinical outcomes and treatment plans. Therefore, the goal of this review was to report major findings related to vertebral radiographic bone changes around cervical disc replacements, mitigate discrepancies in clinical reports by introducing uniform terminology to the field, and establish a precedence that can be used to identify the important nuances between these distinct complications.

Methods: A systematic review of the literature was conducted following PRISMA guidelines, using the keywords "cervical," "disc replacement," "osteolysis," "bone loss," "radiograph," and "complications." A total of 23 articles met the inclusion criteria with the majority being retrospective or case reports.

Results: Fourteen studies reported periprosthetic osteolysis in a total of 46 patients with onset ranging from 15-96 months after the index procedure. Reported causes included: metal hypersensitivity, infection, mechanical failure, and wear debris. Osteolysis was generally progressive and led to reoperation. Nine articles reported non-inflammatory bone loss in 527 patients (52.5%), typically within 3-6 months following implantation. The reported causes included: micromotion, stress shielding, and interrupted blood supply. With one exception, bone loss was reported to be non-progressive and had no effect on clinical outcome measures.

Conclusions: Non-progressive, early onset bone loss is a common finding after CDA and typically does not affect the reported short-term pain scores or lead to early revision. By contrast, osteolysis was less common, presenting more than a year post-operative and often accompanied by additional complications, leading to revision surgery. A greater understanding of the clinical significance is limited by the lack of long-term studies, inconsistent terminology, and infrequent use of histology and explant analyses. Uniform reporting and adoption of consistent terminology can mitigate some of these limitations. Executing these actionable items is critical to assess device performance and the risk of revision.

Level Of Evidence Iv: Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.
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http://dx.doi.org/10.1007/s00586-021-07092-9DOI Listing
April 2022

The insidious risk of periprosthetic fracture in clinically functional total hip arthroplasties: A biomechanical study of willed joints.

J Orthop Res 2021 Oct 25. Epub 2021 Oct 25.

Department of Orthopaedic Surgery, David Geffen School of Medicine, Los Angeles Orthopaedic Center, University of California, Los Angeles, California, USA.

Femoral bone quality is a major risk factor of periprosthetic fracture after total hip arthroplasty (THA), which has mortality similar to native hip fractures but higher short-term morbidity. The goal of this study was to quantify cortical strains at the site of expected Vancouver Type-B periprosthetic fracture as a function of bone mineral density, femoral stem material, and fixation method using a series of 29 autopsy-retrieved, clinically asymptomatic hip joints with THA. Periprosthetic bone mineral content and density was assessed using dual-energy X-ray absorptiometry by Gruen Zone. Specimens then underwent combined cyclic axial and torsional loading, increasing incrementally from 100 N and ±1 Nm to peaks of 700 N and ±5 Nm. All specimens experienced significantly higher strains on the lateral surface than on the anterior surface, indicating that the bending loads in the frontal plane, rather than axial/torsional loads, had the predominant effect. Multiple significant relationships (p = 0.04, p = 0.02) were found between predicted periprosthetic strains calculated from radiographic measurements and observed principal strains. Though THA in the present study were in successful clinical service, the produced results indicated that some femurs with rigid cemented or noncemented implants were potentially at high risk for Vancouver Type-B fractures, which may be predicted radiographically.
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http://dx.doi.org/10.1002/jor.25203DOI Listing
October 2021

Objective analysis of intermediate-term outcome of the Ponseti technique: a review of the experience from Los Angeles.

Ann Transl Med 2021 Jul;9(13):1101

The J. Vernon Luck, Sr., MD Orthopedic Research Center, Orthopaedic Institute for Children and the Department of Orthopedic Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.

The Ponseti method of manipulative treatment for clubfoot deformity became widely adopted by pediatric orthopaedic surgeons beginning in the mid-1990s. The technique allows correction of most idiopathic clubfeet using gentle manipulation and cast application. The treatment represents a marked advance over past efforts to gain correction of the foot through extensive release surgery. In 2006, we began a Clubfoot Clinic at the Orthopaedic Institute for Children in Los Angeles, California dedicated to managing clubfoot patients using Ponseti's method. An IRB-approved database of patient-related, treatment related, and demographic variables was assembled and used to ascertain the outcome of treatment as well as to address parental questions regarding certain aspects of treatment. Here, we present a review of our body of work, which has improved clinical decision making as well as our ability to better inform our patients' parents regarding the treatment and prognosis of the Ponseti method. Studies from our institution showed that while relapses and the need for extra-articular tibialis anterior tendon transfer (TATT) surgery remain common to the Ponseti method, these events do not adversely affect overall patient function or satisfaction. These findings were not unlike those of classic studies reported from Ponseti's institution. We conclude that the Ponseti method is not only a technique to achieve initial correction of an idiopathic clubfoot, but also how to manage relapses that will inevitably occur in many patients. While relapses and tendon transfer surgery are likely to remain common with this treatment method, these events do not adversely affect overall patient function or satisfaction. The parents of infants whose clubfeet are managed using the Ponseti method should be counselled accordingly.
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http://dx.doi.org/10.21037/atm-20-7774DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8339808PMC
July 2021

A novel intramedullary nail to control interfragmentary motion in diaphyseal tibial fractures.

J Orthop Res 2022 05 12;40(5):1053-1064. Epub 2021 Jul 12.

The J. Vernon Luck, Sr., M.D. Orthopaedic Research Center, Orthopaedic Institute for Children in Alliance with UCLA, Los Angeles, California, USA.

Numerous animal and human studies have demonstrated the benefit of controlled interfragmentary motion on fracture healing. In this study, we quantified interfragmentary motion and load transfer in tibial fractures fixed using a novel intramedullary nail (IMN) that allows controlled axial motion. Fifty composite tibias with various fracture patterns were utilized. For all test conditions, two interlocking screws were used to fix the nail in the proximal metaphysis, and two interlocking screws through the distal metaphysis. The nail allowed either no motion (static mode) or 1 mm (dynamic mode) of cyclic axial motion between the two fracture fragments for every fracture pattern tested. As expected, strain shielding was more prominent under static nail conditions. In contrast, specimens tested under dynamic nail conditions transferred axial load between the fracture fragments such that strains near the fracture site were generally similar to those measured on an intact tibia. Maximum shear strains proximal to the fracture were significantly lower in specimens with oblique or butterfly fracture patterns (p < 0.01) compared to intact specimens. This decrease in shear strain indicates that strain shielding effects were likely present due to the implant. However, strain shielding appeared to be reduced in tensile and compressive principal strains. In summary, the novel IMN allowed controlled axial motion between the fragments in a variety of common diaphyseal tibial fracture patterns. Clinical Significance: The present in vitro biomechanical study investigated a novel intramedullary nail capable of controlled axial interfragmentary motion which may potentially enhance fracture healing.
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http://dx.doi.org/10.1002/jor.25134DOI Listing
May 2022

Quantification of Ankle Dorsiflexion in Ponseti-managed Unilateral Clubfoot Patients During Early Childhood.

J Pediatr Orthop 2021 Feb;41(2):83-87

Orthopaedic Institute for Children and the Department of Orthopedic Surgery, David Geffen School of Medicine at UCLA.

Background: Following the initial correction of a clubfoot using the Ponseti method, diminished passive ankle dorsiflexion may be observed over time, which could represent a possible relapsed deformity. Alternatively, the change may be attributable to patient age or other variables. Our purpose was to quantify passive ankle dorsiflexion in the involved and contralateral unaffected limbs of Ponseti-managed unilateral clubfoot patients, and to determine what patient-related variables influence this finding.

Methods: In total, 132 unilateral clubfoot patients were studied. Passive ankle dorsiflexion was measured in both limbs at each visit. Data were excluded from visits in which patients showed clear evidence of a relapse. Mean ankle dorsiflexion for clubfeet and contralateral unaffected limbs were reported for annual age intervals and compared using paired t tests. A general linear model was established to assess the effects of age, severity, sex, and side on ankle dorsiflexion.

Results: Mean ankle dorsiflexion for unaffected limbs declined with age, measuring 53±6 degrees between 0 and 1 year of age and decreasing to 39±7 degrees by 4 to 5 years of age. Similarly, mean ankle dorsiflexion in treated clubfeet declined with age, measuring 44±7 degrees between 0 and 1 year and 29±7 degrees between 4 and 5 years. Overall, the difference between limbs in these patients averaged ~10 degrees for every age interval through 9 years (P<0.001). Ankle dorsiflexion of clubfeet in 95% of patients aged 0 to 2 years was at least 20 degrees, and in 95% of patients aged 3 to 5 years this was at least 15 degrees. Patient age (P<0.001) and severity of deformity (P<0.001) were found to be the only significant factors affecting ankle dorsiflexion in the affected limbs.

Conclusions: Ankle dorsiflexion in the Ponseti-treated clubfeet was influenced by age of the patient and the initial severity of the affected limb. Furthermore, our data suggest that, in patients who showed no relapse, a minimum of 20 degrees of ankle dorsiflexion in the corrected clubfoot is maintained through age 3 years and a minimum of 15 degrees is maintained through age 5 years.

Level Of Evidence: Level IV-this is a retrospective case series.
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http://dx.doi.org/10.1097/BPO.0000000000001719DOI Listing
February 2021

Is load control necessary to produce physiological AP displacement and axial rotation in wear testing of TAR?

J Orthop Res 2021 04 8;39(4):797-805. Epub 2020 Dec 8.

The J. Vernon Luck, Sr., M.D. Orthopaedic Research Center, Orthopaedic Institute for Children, University of California Los Angeles Department of Orthopaedics, Los Angeles, California, USA.

The International Standard Organization, ISO 22622, specifies two options for joint wear simulator evaluation of total ankle replacements (TARs): load-controlled and displacement-controlled. In the present study, the load-controlled testing parameters were applied to cadaveric specimens to quantify and compare the observed sagittal translations and axial rotations to those specified under the displacement-controlled option. Twelve cadaveric specimens were stripped of extraneous tissues, keeping surrounding ankle ligaments. A halo was used to produce plantarflexion and dorsiflexion of the talus through two screws, while a baseplate resisted axial loads. The axial force and torque were applied to the tibia and fibula under force and torque feedback control. An anterior-posterior force was applied to the tibia. Plantarflexion-dorsiflexion were applied using rotation control. To protect the cadaveric specimens, loads were applied at 50% of the specified load profile while plantarflexion-dorsiflexion rotation was applied as specified. There was variation among specimens in magnitudes of anterior-posterior displacement with peaks ranging from 3.3 mm posteriorly to 3.0 mm anteriorly. Likewise, there was variation among specimens in magnitude of axial rotation, with peaks ranging from 11° external rotation to 4.5° internal rotation. However, the mean magnitudes of AP displacement and axial rotation did not exceed those specified by ISO 22622.
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http://dx.doi.org/10.1002/jor.24931DOI Listing
April 2021

Does generalized joint hypermobility influence the Ponseti treatment of clubfoot patients?

J Pediatr Orthop B 2021 Jan;30(1):66-70

David Geffen School of Medicine.

Previous investigators have suggested a role for generalized joint hypermobility (GJH) in the etiology of clubfoot deformity, while others have suggested its presence may influence treatment outcomes. We sought to determine if GJH was associated with the demographics, treatment, or propensity to relapse of patients whose clubfeet were managed using the Ponseti method. Fifty-seven patients with Ponseti-treated clubfeet comprised the cohort; median age 61 months (range, 38-111 months). A physical therapist evaluated each patient using the nine-point Beighton scale to quantify hypermobility. The scores were then correlated with patient sex, laterality, Dimeglio severity score, treatment, relapse, and surgery. The median Beighton score was 5; 49 of 57 patients (86%) had Beighton scores ≥4. All feet were plantigrade without symptomatic overcorrection at the time of evaluation. Although there was a slightly lower probability of relapse in patients with higher Beighton scores, this was not statistically significant (P = 0.10). Accordingly, the sex, laterality, initial severity, number of pretenotomy casts, need for tenotomy, relapse, and need for tendon transfer surgery were not significantly influenced by the Beighton score. The outcome of Ponseti clubfoot treatment is not altered by the presence of GJH in young children. Joint hypermobility does not appear to influence the likelihood of relapse or surgery. Unlike clubfeet reportedly treated with release surgery, Ponseti-treated clubfeet were not prone to excessive overcorrection regardless of joint laxity. Last, the distribution of Beighton scores in the study's cohort supports an association between GJH and clubfoot deformity.
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http://dx.doi.org/10.1097/BPB.0000000000000747DOI Listing
January 2021

A Systematic Review of Unsystematic Total Ankle Replacement Wear Evaluations.

JBJS Rev 2020 03;8(3):e0091

J. Vernon Luck Sr., MD, Orthopaedic Research Center (JVL) at the Orthopaedic Institute for Children (OIC), in alliance with UCLA, Los Angeles, California.

Background: Numerous studies have reported the use of laboratory multistation joint simulators to successfully predict wear performance and functionality of hip and knee replacements. In contrast, few studies in the peer-reviewed literature have used joint simulation to quantify the wear performance and functionality of ankle replacements. We performed a systematic review of the literature on joint simulator studies that quantified polyethylene wear in total ankle arthroplasty. In addition to the quantified wear results, the load and motion parameters were identified and compared among the studies.

Methods: A search was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines to identify articles reporting total ankle replacement polyethylene wear using joint simulators.

Results: Nine studies that used joint simulators and 1 study that used a computer simulation were found. Although all studies used physiological multidirectional motions (i.e., internal/external rotation, plantar flexion/dorsiflexion, anterior/posterior translation), there was large variability among the studies in the magnitudes of these motions. Among these studies, mean non-cross-linked polyethylene wear ranged from 3.3 ± 0.4 to 25.8 ± 3.1 mm per million cycles. In contrast, mean highly cross-linked polyethylene wear ranged from 2.1 ± 0.3 to 3.3 ± 0.4 mm per million cycles. The wide distribution in wear rates was attributable to the highly inconsistent kinematic parameters and loads applied as well as differences in implant design and materials.

Conclusions: There is a severe lack of clinically applicable data on wear performance of total ankle replacements in the peer-reviewed literature. No universal set of kinematic load parameters has been established. Furthermore, only 2 of the published studies have validated their findings using independently derived data, such as retrieval analysis. These shortcomings make it difficult to compare findings as a function of design parameters and materials, or to draw clinically relevant conclusions from these simulations. More work is required to enhance the predictive capability of in vitro simulations of total ankle replacements.

Clinical Relevance: The results of joint wear simulator studies may not accurately represent in vivo wear of total ankle replacements. Joint simulator studies should establish that they are accurately replicating in vivo wear, thus enabling use of their predictive capabilities for new materials and designs.
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http://dx.doi.org/10.2106/JBJS.RVW.19.00091DOI Listing
March 2020

Increasing loads and diminishing returns: a biomechanical study of direct vertebral rotation.

Spine Deform 2020 08 5;8(4):577-584. Epub 2020 Feb 5.

J. Vernon Luck Sr, M.D. Orthopaedic Research Center (JVL), Orthopaedic Institute for Children (OIC)/UCLA, Los Angeles, CA, USA.

Study Design: Biomechanical simulation of DVR and pure-moment testing on thoracic spines.

Objectives: Characterize load-deformation response of thoracic spines under DVR maneuvers until failure, and compare to pure-moment testing of same spines. Despite reports of surgical complications, few studies exist on increase in ROM under DVR torque. Biomechanical models predicting increases from surgical releases have consistently used "pure-moments", a standard established for non-destructive measurement of ROM. Yet, DVR torque is not accurately modeled using pure moments and, moreover, magnitudes of torque applied during DVR maneuvers may be substantially higher than pure-moment testing.

Methods: Cadaveric thoracic spines (N = 11) were imaged, then prepared. Polyaxial pedicle screws were implanted at T7-T10 after surgical releases. Bilateral facetectomies and Ponte osteotomies were completed at T10-T11. A custom apparatus, mounted into an 8-dof MTS load frame, was used to attach to pedicle screws, allowing simulation of surgical DVR maneuvers. Motions of vertebrae were measured using optical motion tracking. Torque was increased until rupture of the T10-T11 disc or fracture at the pedicle screw sites at any level. The torque-rotation behavior was compared to its behavior under pure-moment testing performed prior to the DVR maneuver.

Results: Under DVR maneuvers, failure of the T10-T11 discs accompanied in most cases by pedicle screw loosening, occurred at 13.7-54.7 Nm torque, increasing axial rotation by 1.4°-8.9°. In contrast, pure-moment testing (4 Nm) increased axial rotation by only 0.0°-0.9°.

Conclusions: DVR resulted in substantially greater correction potential increases compared to pure-moment testing even at the same torque. These results suggest increased flexibility obtained by osteotomies and facetectomies is underestimated using pure-moment testing, misrepresenting clinical expectations. The present study is an important and necessary step toward the establishment of a more accurate and ultimately surgically applied model.

Level Of Evidence: III.
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http://dx.doi.org/10.1007/s43390-020-00061-0DOI Listing
August 2020

Relapse Rates in Patients with Clubfoot Treated Using the Ponseti Method Increase with Time: A Systematic Review.

JBJS Rev 2019 05;7(5):e6

Orthopaedic Institute for Children, The J. Vernon Luck, Sr., M.D. Orthopaedic Research Center, Los Angeles, California.

Background: The Ponseti method is the preferred technique to manage idiopathic clubfoot deformity; however, there is no consensus on the expected relapse rate or the percentage of patients who will ultimately require a corrective surgical procedure. The objective of the present systematic review was to determine how reported rates of relapsed deformity and rates of a secondary surgical procedure are influenced by each study's length of follow-up.

Methods: A comprehensive literature search using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was performed to identify relevant articles. The definition of relapse, the percentage of patients who relapsed, the percentage of feet that required a surgical procedure, and the mean duration of follow-up of each study were extracted. Pearson correlations were performed to determine associations among the following variables: mean follow-up duration, percentage of patients who relapsed, percentage of feet that required a joint-sparing surgical procedure, and percentage of feet that required a joint-invasive surgical procedure. Logarithmic curve fit regressions were used to model the relapse rate, the rate of joint-sparing surgical procedures, and the rate of joint-invasive surgical procedures as a function of follow-up time.

Results: Forty-six studies met the inclusion criteria. Four distinct definitions of relapse were identified. The reported relapse rates varied from 3.7% to 67.3% of patients. The mean duration of follow-up was strongly correlated with the relapse rate (Pearson correlation coefficient = 0.44; p < 0.01) and the percentage of feet that required a joint-sparing surgical procedure (Pearson correlation coefficient = 0.59; p < 0.01). Studies with longer follow-up showed significantly larger percentages of relapse and joint-sparing surgical procedures than studies with shorter follow-up (p < 0.05).

Conclusions: Relapses have been reported to occur at as late as 10 years of age; however, very few studies follow patients for at least 8 years. Notwithstanding that, the results indicated that the rate of relapse and percentage of feet requiring a joint-sparing surgical procedure increased as the duration of follow-up increased. Longer-term follow-up studies are required to accurately predict the ultimate risk of relapsed deformity. Patients and their parents should be aware of the possibility of relapse during middle and late childhood, and, thus, follow-up of these patients until skeletal maturity may be warranted.

Level Of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
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http://dx.doi.org/10.2106/JBJS.RVW.18.00124DOI Listing
May 2019

Preclinical biomechanical testing models for the tibiotalar joint and its replacements: A systematic review.

Foot Ankle Surg 2020 Jan 23;26(1):14-18. Epub 2018 Dec 23.

The J. Vernon Luck, Sr., M.D. Orthopaedic Research Center, Orthopaedic Institute for Children, 403 W. Adams Blvd., Los Angeles, CA 90007, United States; University of California, Los Angeles Department of Orthopaedic Surgery, Los Angeles, CA, United States. Electronic address:

In recent years, total ankle replacements have gained increasing popularity as an alternative to fusion. Preclinical testing of TARs requires reliable in vitro models which, in turn, need thorough knowledge of the kinematics of the tibiotalar joint. Surprisingly few studies have been published to simulate the in vivo kinematics of the tibiotalar joint. Among these studies, there is a wide range of methods and magnitudes of applied loads. The purpose of the present review was to summarize the applied loads, positions that were tested during static simulations, and ranges of motion simulated that have been used in human cadaveric models of the tibiotalar joint. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, PubMed and Google Scholar were searched for studies pertaining to cadaveric tibiotalar joint kinematics. Our search yielded 12 appropriate articles that were included in the systematic review. While it is well known that loads at the tibiotalar joint are frequently as high as 5 times bodyweight [1], these studies reported applied loads varying from 200N-750N, below average bodyweight. Three studies used dynamic loading of custom apparatuses to drive cadaver limbs along predetermined paths to simulate gait. Conversely, the other nine studies applied static loads (∼300N), performed at discreet points during the stance phase, considerably lower than physiological conditions. The present systematic review calls for an urgent need to establish a consensus for preclinical evaluation of TARs for biomechanical function.
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http://dx.doi.org/10.1016/j.fas.2018.12.007DOI Listing
January 2020

Sixty Years On: Ponseti Method for Clubfoot Treatment Produces High Satisfaction Despite Inherent Tendency to Relapse.

J Bone Joint Surg Am 2018 May;100(9):721-728

The J. Vernon Luck, Sr., M.D. Orthopaedic Research Center, Orthopaedic Institute for Children, in alliance with the University of California, Los Angeles, Los Angeles, California.

Background: Developed at the University of Iowa in 1950, the Ponseti method to manage idiopathic clubfoot deformity was slow to gain wide acceptance until the mid-1990s. There is a paucity of intermediate and long-term outcome studies involving this technique, with nearly all such studies coming from a single institution. The purpose of this study is to report the contemporary outcome of patients with clubfoot deformity whose feet were managed with the Ponseti method and who were followed to ≥5 years old, to provide outcome expectations for parents and for clinicians managing patients with idiopathic clubfoot.

Methods: Families of infants seen in our clinic diagnosed with idiopathic clubfoot since July 2006 were prospectively invited to participate in our institutional review board-approved study. Patients who received no prior outside treatment and had a minimum follow-up to the age of 5 years were included. Demographic, treatment, and outcome data were collected. To provide an array of outcome measures, both the Dallas outcome criteria and the Roye disease-specific instrument (DSI) were used.

Results: One hundred and one patients met the inclusion criteria. The mean length of follow-up (and standard deviation) was 81.1 ± 17.1 months. Initial correction was achieved in all feet. Thirty-seven percent of families reported that they were adherent with the bracing protocol; 68% of patients had ≥1 relapse, and 38% underwent a tendon transfer. With the Dallas criteria, 62% had outcomes rated as good, 38% had outcomes rated as fair, and no patient had an outcome rated as poor. With the Roye DSI, most families were generally very satisfied with the function and appearance of the feet.

Conclusions: Satisfactory results at intermediate follow-up were achieved using the Ponseti method. However, despite a better understanding of the Ponseti method and the importance of longer post-corrective brace use, the need for anterior tibial tendon transfer remains an important adjunct to the Ponseti method. Brace adherence also continues to be a critical clinical issue.

Level Of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
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http://dx.doi.org/10.2106/JBJS.17.01024DOI Listing
May 2018

Biomechanical comparison of fixation stability using a Lisfranc plate versus transarticular screws.

Foot Ankle Surg 2019 Feb 23;25(1):71-78. Epub 2017 Aug 23.

Los Angeles County Harbor-UCLA Medical Center, Los Angeles, CA, United States. Electronic address:

Background: To obtain adequate fixation in treating Lisfranc soft tissue injuries, the joint is commonly stabilized using multiple transarticular screws; however iatrogenic injury is a concern. Alternatively, two parallel, longitudinally placed plates, can be used to stabilize the 1st and 2nd tarsometatarsal joints; however this may not provide adequate stability along the Lisfranc ligament. Several biomechanical studies have compared earlier methods of fixation using plates to the standard transarticular screw fixation method, highlighting the potential issue of transverse stability using plates. A novel dorsal plate is introduced, intended to provide transverse and longitudinal stability, without injury to the articular cartilage.

Methods: A biomechanical cadaver model was developed to compare the fixation stability of a novel Lisfranc plate to that of traditional fixation, using transarticular screws. Thirteen pairs of cadaveric specimens were tested intact, after a simulated Lisfranc injury, and then following implant fixation, using one method of fixation randomly assigned, on either side of each pair. Optical motion tracking was used to measure the motion between each of the following four bones: 1st metatarsal, 2nd metatarsal, 1st cuneiform, and 2nd cuneiform. Testing included both cyclic abduction loading and cyclic axial loading.

Results: Both the Lisfranc plate and screw fixation method provided stability such that the average 3D motions across the Lisfranc joint (between 2nd metatarsal and 1st cuneiform), were between 0.2 and 0.4mm under cyclic abduction loading, and between 0.4 and 0.5mm under cyclic axial loading. Comparing the stability of fixation between the Lisfranc plate and the screws, the differences in motion were all 0.3mm or lower, with no clinically significant differences (p>0.16).

Conclusions: Diastasis at the Lisfranc joint following fixation with a novel plate or transarticular screw fixation were comparable. Therefore, the Lisfranc plate may provide adequate support without risk of iatrogenic injury to the articular cartilage.
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http://dx.doi.org/10.1016/j.fas.2017.08.004DOI Listing
February 2019

Opioid Prescription and Usage in Adolescents Undergoing Orthopaedic Surgery in the United States: A Systematic Review.

JBJS Rev 2017 08;5(8):e5

The J. Vernon Luck, Sr., M.D. Orthopaedic Research Center (E.A.D., E.E., and S.N.S.), Orthopaedic Institute for Children (J.J.B. and R.E.B.), in alliance with the Department of Orthopaedic Surgery, University of California, Los Angeles, Los Angeles, California.

Background: The proper use of opioid analgesia for postoperative pain management is controversial. While opioids are considered the standard of care for multimodal postoperative pain modulation in the United States, there is a lack of established protocols for prescribing opioids in adolescents undergoing outpatient orthopaedic surgery. The objective of this review was to identify and report on current literature on opioid prescription for pain management in adolescents undergoing all procedures, as well as in adults undergoing outpatient orthopaedic surgery.

Methods: A comprehensive literature search using PRISMA guidelines was performed to identify all articles relevant to opioid use in adolescents for postoperative pain and in adults following outpatient orthopaedic procedures.

Results: A total of 4,446 results were identified from databases and relevant journal web sites. Of these, 9 articles were selected that fit the criteria for review. Five studies discussed the dosage and type of opioids prescribed in adolescent populations, and 4 quantified patient self-administration in adult populations.

Conclusions: Adolescent opioid pain management following outpatient orthopaedic surgery is not documented. Current recommendations for opioid prescription in adolescents lack support and are primarily based on adult dosages. Adult studies suggest that opioid medications may be overprescribed following outpatient orthopaedic surgery. These results clearly indicate that there is a pressing need for quantitative research on pain management following outpatient orthopaedic surgery in the adolescent population in the United States.

Clinical Relevance: There appear to be no studies on self-administered opioid pain medication following orthopaedic surgery in an adolescent population, suggesting that there is no objective basis for the current prescription recommendations.
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http://dx.doi.org/10.2106/JBJS.RVW.16.00093DOI Listing
August 2017

Strength of Thoracic Spine Under Simulated Direct Vertebral Rotation: A Biomechanical Study.

Spine Deform 2016 Mar 2;4(2):85-93. Epub 2016 Feb 2.

The J. Vernon Luck, Sr., M.D. Orthopaedic Research Center, Orthopaedic Institute for Children/UCLA, 403 West Adams Blvd, Los Angeles, CA 90007, USA. Electronic address:

Background: Direct vertebral rotation (DVR) has gained increasing popularity for deformity correction surgery. Despite large moments applied intraoperatively during deformity correction and failure reports including screw plow, aortic abutment, and pedicle fracture, to our knowledge, the strength of thoracic spines has been unknown. Moreover, the rotational response of thoracic spines under such large torques has been unknown.

Purpose: Simulate DVR surgical conditions to measure torsion to failure on thoracic spines and assess surgical forces.

Study Design: Biomechanical simulation using cadaver spines.

Methods: Fresh-frozen thoracic spines (n = 11) were evaluated using radiographs, magnetic resonance imaging (MRI) and dual-energy x-ray absorptiometry. An apparatus simulating DVR was attached to pedicle screws at T7-T10 and transmitted torsion to the spine. T11-T12 were potted and rigidly attached to the frame. Strain gages measured the simulated surgical forces to rotate spines. Torsional load was increased incrementally till failure at T10-T11. Torsion to failure at T10-T11 and corresponding forces were obtained.

Results: The T10-T11 moment at failure was 33.3 ± 12.1 Nm (range = 13.7-54.7 Nm). The mean applied force to produce failure was 151.7 ± 33.1 N (range = 109.6-202.7 N), at a distance of approximately 22 cm where surgeons would typically apply direct vertebral rotation forces. Mean right rotation at T10-T11 was 11.6°±5.6°. The failure moment was significantly correlated with bone mineral density (Pearson coefficient 0.61, p = .047). Failure moment also positively correlated with radiographic degeneration grade (Spearman rho > 0.662, p < .04) and MRI degeneration grade (Spearman rho = 0.742, p = .01).

Conclusion: The present study indicated that with the advantage of lever arms provided with DVR techniques, relatively small surgical forces, <200 N, can produce large moments that cause irreversible injury. Although further studies are required to establish the safety of surgical deformity correction surgeries, the present study provides a first step in the quantification of thoracic spine strength.
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http://dx.doi.org/10.1016/j.jspd.2015.09.044DOI Listing
March 2016

Biomechanical Comparison of Fixation Devices for First Metatarsocuneiform Joint Arthrodesis.

Foot Ankle Spec 2017 Aug 23;10(4):322-328. Epub 2016 Nov 23.

J. Vernon Luck Sr, M.D. Orthopaedic Research Center, Orthopaedic Institute for Children/UCLA, Los Angeles, California (ARK, EE, NCH, SNS).

Common surgical treatment of first tarsal-metatarsal arthritis is by first metatarsocuneiform joint arthrodesis. While crossed-screw and locking plate fixation are the most widely used methods, a novel construct was designed to alleviate soft tissue irritation while still providing stable fixation. Using anatomic first metatarsal and medial cuneiform composites, we compared 3 arthrodesis implants (crossed-screw, dorsal locking plate, and IO Fix) under 2 cyclic bending loading scenarios (cantilever and 4-point bending). Additionally, the optimal orientation (plantar-dorsal or dorsal-plantar) of the IO Fix construct was determined. Failure load, diastasis, joint space angle, and axial and angular stiffness were determined. Both crossed-screw fixation and the IO Fix constructs experienced significantly higher failure loads than the dorsal locking plate during both loading scenarios. Additionally, they had lower plantar diastasis and joint space angle at failure than the plate. Moreover, the plantar-dorsal IO Fix construct was significantly stiffer than the crossed-screw during cantilever bending. Finally, the plantar-dorsal orientation of the IO Fix device had higher failure load and lower diastasis and angle at failure than in the dorsal-plantar orientation. The results suggest that the IO Fix system can reduce motion at the interfragmentary site and ensure compression for healing comparable to that of the crossed-screw fixation.

Levels Of Evidence: Level V: Bench testing.
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http://dx.doi.org/10.1177/1938640016679698DOI Listing
August 2017

Distal fibula fracture fixation: Biomechanical evaluation of three different fixation implants.

Foot Ankle Surg 2016 Dec 9;22(4):278-285. Epub 2016 Sep 9.

The J. Vernon Luck, Sr., M.D. Orthopaedic Research Center, Orthopaedic Institute for Children and UCLA Department of Orthopaedics, Los Angeles, CA, United States. Electronic address:

Background: The goal of this study was to evaluate the biomechanical performance of three distal fibula fracture fixation implants in a matched pair cadaveric fibula model: (1) a 5-hole compression plate with lag screw, (2) a 5-hole locking plate with lag screw, and (3) the 6-hole tabbed-plate with locking screws.

Methods: Three-dimensional motions between the proximal and distal fibular segments were measured under cyclic valgus bending, cyclic compressive axial loading, and cyclic torsional external-rotation loading. During loading, strains were measured on the surfaces of each fibula near the simulated fracture site, and on the plate, to assess load transfer. Bone quality was quantified globally for each donor using bone mineral density (BMD) measured using Dual X-ray absorptiometry (DEXA) and locally at the fracture site using bone mineral content (BMC) measured using peripheral quantitative computed tomography (pQCT).

Results: Mean failure loads were below 0.2Nm of valgus bending and below 4Nm of external-rotational torque. Mean failure angulation was below 1degree for valgus bending, and failure rotation was below 7degrees for external-rotation. In the compression plate group, significant correlations were observed between bone quality (global BMD and local BMC) and strain in every one of the five locations (Pearson correlation coefficients >0.95, p<0.05). In contrast, in the locking and tabbed-plate groups, BMD and BMC correlated with far fewer strain locations.

Conclusions: Overall, the tabbed-plate had similar construct stability and strength to the compression and locking plates. However, the distribution of load with the locking and tabbed-plates was not as heavily dependent on bone quality.
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http://dx.doi.org/10.1016/j.fas.2016.08.007DOI Listing
December 2016

Periprosthetic femoral bone loss in total hip arthroplasty: systematic analysis of the effect of stem design.

Hip Int 2017 Feb 3;27(1):26-34. Epub 2016 Aug 3.

J. Vernon Luck, Sr., M.D. Orthopaedic Research Center Orthopaedic Institute for Children, Los Angeles, California - USA.

Introduction: Periprosthetic bone loss may lead to major complications in total hip arthroplasty (THA), including loosening, migration, and even fracture. This study analysed the influence of femoral implant designs on periprosthetic bone mineral density (BMD) after THA.

Methods: The results of all previous published studies reporting periprosthetic femoral BMD following THA were compiled. Using these results, we compared percent changes in bone loss as a function of: femoral stem fixation, material, and geometry.

Results: The greatest bone loss was in the calcar region (Gruen Zone 7). Overall, cemented stems had more bone loss distally than noncemented stems, while noncemented stems had more proximal bone loss than cemented stems. Within noncemented stems, cobalt-chromium (CoCr) stems had nearly double the proximal bone loss compared to titanium (Ti) alloy stems. Finally, within noncemented titanium alloy group, straight stems had less bone loss than anatomical, tapered, and press-fit designs.

Discussion: The findings from the present study quantified percent changes in periprosthetic BMD as a function of fixation method, alloy, and stem design. While no one stem type was identified as ideal, we now have a clearer understanding of the influence of stem design on load transfer to the surrounding bone.
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http://dx.doi.org/10.5301/hipint.5000413DOI Listing
February 2017

The Objective Measurement of Brace-Use Adherence in the Treatment of Idiopathic Clubfoot.

J Bone Joint Surg Am 2016 Oct;98(19):1598-1605

The J. Vernon Luck, Sr., MD, Orthopaedic Research Center, Orthopaedic Institute for Children, Los Angeles, California Department of Orthopaedic Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California

Background: A successful outcome for the treatment of idiopathic clubfoot is believed to require adequate adherence to brace use. Previous studies have relied on parental reporting of brace application. We used temperature sensors to determine the adherence to the bracing protocol, the accuracy of parent-reported use, and differences in adherence between patients who experienced relapse of deformity and those who did not.

Methods: Using wireless sensors attached to brace sandals, we monitored brace wear over a 3-month period in this cross-sectional study involving 48 patients in 4 age-based groups: 6 to 12 months (Group 1), >1 to 2 years (Group 2), >2 to 3 years (Group 3), and >3 to 4 years (Group 4). Parents were blinded to the purpose of the sensors. The mean number of hours of daily brace use as measured by the sensors was compared with the physician-recommended hours and parent-reported hours of brace use.

Results: Sensors were retrieved from 44 of 48 patients. Overall, the median brace use recorded by the sensors was 62% (range, 5% to 125%) of that recommended by the physician, and 77% (range, 6% to 213%) of that reported by the parents. For Groups 1 to 3, the difference between the physician-recommended and measured number of hours of daily brace use was significant (p ≤ 0.002), and the difference between the parent-reported and measured number of hours of daily brace use was also significant (p ≤ 0.013). Eight (18%) of the 44 patients who completed the study experienced relapse during the period of monitoring; most importantly, the mean number of hours of brace wear for these patients, 5 hours per day (median, 4; and standard deviation [SD], 3 hours per day) was significantly lower than the 8 hours per day for those who did not experience relapse (median, 9; and SD, 5 hours per day) (p = 0.045).

Conclusions: The present study objectively quantified the number of daily hours of post-corrective brace wear for patients with clubfoot in varying age groups and provides an estimate of the number of hours required to avoid relapse.

Level Of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.
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http://dx.doi.org/10.2106/JBJS.16.00170DOI Listing
October 2016

Challenging the Conventional Standard for Thoracic Spine Range of Motion: A Systematic Review.

JBJS Rev 2016 04;4(4):e51-e511

The J. Vernon Luck, Sr., M.D. Orthopaedic Research Center, Orthopaedic Institute for Children, University of California, Los Angeles, Los Angeles, California.

Background: Segmental motion is a fundamental characteristic of the thoracic spine; however, studies of segmental ranges of motion have not been summarized or analyzed. The purpose of the present study was to present a summary of the literature on intact cadaveric thoracic spine segmental range of motion in each anatomical plane.

Methods: A systematic MEDLINE search was performed with use of the terms "thoracic spine," "motion," and "cadaver." Reports that included data on the range of motion of intact thoracic human cadaveric spines were included. Independent variables included experimental details (e.g., specimen age), type of loading (e.g., pure moments), and applied moment. Dependent variables included the ranges of motion in flexion-extension, lateral bending, and axial rotation.

Results: Thirty-three unique articles were identified and included. Twenty-three applied pure moments to thoracic spine specimens, with applied moments ranging from 1.5 to 8 Nm. Estimated segmental range of motion pooled means ranged from 1.9° to 3.8° in flexion-extension, from 2.1° to 4.4° in lateral bending, and from 2.4° to 5.2° in axial rotation. The sums of the range of motion pooled means (T1 to T12) were 28° in flexion-extension, 36° in lateral bending, and 45° in axial rotation.

Conclusions: The pooled ranges of motion were similar to reported in vivo motions but were considerably smaller in magnitude than the frequently referenced values reported prior to the widespread use of biomechanical testing standards. Improved reporting of biomechanical testing methods, as well as specimen health, may be beneficial for improving on these estimations of segmental cadaveric thoracic spine range of motion.
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http://dx.doi.org/10.2106/JBJS.RVW.O.00048DOI Listing
April 2016

How Many Patients Who Have a Clubfoot Treated Using the Ponseti Method are Likely to Undergo a Tendon Transfer?

J Pediatr Orthop 2018 Aug;38(7):382-387

Department of Orthopaedics, David Geffen School of Medicine at UCLA, Orthopaedic Institute for Children, Los Angeles, CA.

Background: The Ponseti method has become the standard of care for the treatment of idiopathic clubfoot. A commonly reported problem encountered with this technique is a relapsed deformity that is sometimes treated in patients older than 2.5 years by an anterior tibial tendon transfer (ATTT) to the third cuneiform. Presently, there is insufficient information to properly counsel families whose infants are beginning Ponseti treatment on the probability of needing later tendon transfer surgery.

Methods: All idiopathic clubfoot patients seen at the authors' institution during the study period who met the inclusion criteria and who were followed for >2.5 years were included (N=137 patients). Kaplan-Meier Survival analysis was used to determine the probability of survival without the need for ATTT surgery. In addition, the influence of patient characteristics, socioeconomic variables, and treatment variables on need for surgery was calculated.

Results: On the basis of the survivorship analysis, the probability of undergoing an ATTT remained below 5% for all patients at 3 years of age, but exceeded 15% by 4 years of age, increasing steadily afterwards such that by 6 years of age, the probability of undergoing an ATTT reached 29% of all patients. Overall, controlling for all other variables in the analysis, parent-reported adherence with bracing reduced the odds of undergoing surgery by 6.88 times, compared with parent-reported nonadherence (P<0.01).

Conclusions: This is the first study to report the probability of undergoing ATTT surgery as a function of age using survivorship analysis following Ponseti clubfoot treatment. Although the overall probability reached 29% at 6 years, this was significantly reduced by compliance with bracing. This information may be useful to the clinician when counseling families at the start of treatment.

Level Of Evidence: Level III-theraputic.
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http://dx.doi.org/10.1097/BPO.0000000000000828DOI Listing
August 2018

Strength of Thoracic Spine Under Simulated Direct Vertebral Rotation: A Biomechanical Study.

Spine Deform 2016 Mar 30;4(2):85-93. Epub 2016 Dec 30.

The J. Vernon Luck, Sr., M.D. Orthopaedic Research Center, Orthopaedic Institute for Children/UCLA Department of Orthopaedic Surgery, 403 West Adams Blvd, Los Angeles, CA, 90007, USA.

Background: Direct vertebral rotation (DVR) has gained increasing popularity for deformity correction surgery. Despite large moments applied intraoperatively during deformity correction and failure reports including screw plow, aortic abutment, and pedicle fracture, to our knowledge, the strength of thoracic spines has been unknown. Moreover, the rotational response of thoracic spines under such large torques has been unknown.

Purpose: Simulate DVR surgical conditions to measure torsion to failure on thoracic spines and assess surgical forces.

Study Design: Biomechanical simulation using cadaver spines.

Methods: Fresh-frozen thoracic spines (n = 11) were evaluated using radiographs, magnetic resonance imaging (MRI) and dual-energy x-ray absorptiometry. An apparatus simulating DVR was attached to pedicle screws at T7-T10 and transmitted torsion to the spine. T11-T12 were potted and rigidly attached to the frame. Strain gages measured the simulated surgical forces to rotate spines. Torsional load was increased incrementally till failure at T10-T11. Torsion to failure at T10-T11 and corresponding forces were obtained.

Results: The T10-T11 moment at failure was 33.3 ± 12.1 Nm (range = 13.7-54.7 Nm). The mean applied force to produce failure was 151.7 ± 33.1 N (range = 109.6-202.7 N), at a distance of approximately 22 cm where surgeons would typically apply direct vertebral rotation forces. Mean right rotation at T10-T11 was 11.6°±5.6°. The failure moment was significantly correlated with bone mineral density (Pearson coefficient 0.61, p =.047). Failure moment also positively correlated with radiographic degeneration grade (Spearman rho > 0.662, p <.04) and MRI degeneration grade (Spearman rho = 0.742, p =.01).

Conclusion: The present study indicated that with the advantage of lever arms provided with DVR techniques, relatively small surgical forces, <200 N, can produce large moments that cause irreversible injury. Although further studies are required to establish the safety of surgical deformity correction surgeries, the present study provides a first step in the quantification of thoracic spine strength.
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http://dx.doi.org/10.1016/j.jspd.2015.09.044DOI Listing
March 2016

The Influence of Sex and Laterality on Clubfoot Severity.

J Pediatr Orthop 2017 Mar;37(2):e129-e133

Orthopaedic Institute for Children, David Geffen School of Medicine at UCLA, Los Angeles, CA.

Background: Idiopathic clubfoot is bilateral in approximately 50% of cases and has been widely reported to affect males more frequently than females. Despite these observations, the correlation between sex and severity of the deformity has not been established. As well, the difference in severity between unilateral and bilateral clubfeet has not been extensively investigated. Therefore, the goals of the present study were to: (1) examine the relationship between sex and severity of deformity and (2) determine the relationship between laterality and severity of deformity.

Methods: The families of infants with idiopathic clubfoot deformity treated at our institution were prospectively invited to participate in this institutional review board-approved study. Severity of the deformity was assessed by a single surgeon for each patient using the Dimeglio criteria at the first clinic visit. After evaluating the distributions, the correlations were quantified by nonparametric analyses.

Results: Over 8 years, 240 infants met the inclusion criteria. There was no significant difference in the severity of deformity due to sex (P=0.61): the median Dimeglio score for males was 13 (variance 4.8) and for females, the median was 13.0 (variance of 5.1). In contrast, severity was distributed differently among unilateral versus bilateral patients. Although both unilateral and bilateral patients had a median Dimeglio score of 13, the ratio of bilateral patients was higher among those with moderate or very severe deformities compared with those with severe deformities (P<0.01).

Conclusions: Although idiopathic clubfoot is commonly considered to affect male patients disproportionately, this is the first study to document no difference in severity due to sex. Further, this study demonstrated that on average, bilateral patients did not have increased severity, but presented with a larger range of severity than those patients with unilateral deformity.

Level Of Evidence: Level III-prognostic.
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http://dx.doi.org/10.1097/BPO.0000000000000603DOI Listing
March 2017

Static and dynamic fatigue behavior of topology designed and conventional 3D printed bioresorbable PCL cervical interbody fusion devices.

J Mech Behav Biomed Mater 2015 Sep 27;49:332-42. Epub 2015 May 27.

J. Vernon Luck, Sr., M.D. Orthopaedic Research Center at Orthopaedic Institute for Children, 403 W. Adams Blvd., Los Angeles, CA 90007, USA; Department of Orthopedic Surgery, University of California, Orthopaedic Center, 100 UCLA Medical Plaza Suite 755, Los Angeles, CA 90095, USA.

Recently, as an alternative to metal spinal fusion cages, 3D printed bioresorbable materials have been explored; however, the static and fatigue properties of these novel cages are not well known. Unfortunately, current ASTM testing standards used to determine these properties were designed prior to the advent of bioresorbable materials for cages. Therefore, the applicability of these standards for bioresorbable materials is unknown. In this study, an image-based topology and a conventional 3D printed bioresorbable poly(ε)-caprolactone (PCL) cervical cage design were tested in compression, compression-shear, and torsion, to establish their static and fatigue properties. Difficulties were in fact identified in establishing failure criteria and in particular determining compressive failure load. Given these limitations, under static loads, both designs withstood loads of over 650 N in compression, 395 N in compression-shear, and 0.25 Nm in torsion, prior to yielding. Under dynamic testing, both designs withstood 5 million (5M) cycles of compression at 125% of their respective yield forces. Geometry significantly affected both the static and fatigue properties of the cages. The measured compressive yield loads fall within the reported physiological ranges; consequently, these PCL bioresorbable cages would likely require supplemental fixation. Most importantly, supplemental testing methods may be necessary beyond the current ASTM standards, to provide more accurate and reliable results, ultimately improving preclinical evaluation of these devices.
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http://dx.doi.org/10.1016/j.jmbbm.2015.05.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4490041PMC
September 2015

Does Clubfoot Treatment Need to Begin As Soon As Possible?

J Pediatr Orthop 2016 Sep;36(6):558-64

Orthopaedic Institute for Children, David Geffen School of Medicine at UCLA, Los Angeles, CA.

Introduction: Parents of an infant with an idiopathic clubfoot deformity are often urged by their primary care physician to seek treatment as soon as possible. This advice frequently appears in many general pediatric and pediatric orthopaedic textbooks and monographs on the subject. This recommendation has not changed since the wide acceptance of the minimally invasive Ponseti method to treat clubfoot. We determined the correlations among patient-related variables, early treatment variables, and the age at which the patient was first seen to begin treatment.

Methods: Infants with moderate to very severe idiopathic clubfoot deformity were invited to participate. Age at which the patient presented to begin treatment was correlated against early treatment-related variables, including number of casts required, cast slippage, cast-related skin problems, brace-related skin problems, early noncompliance with brace wearing, and relapse before 1 year. Patient-related variables were also correlated against age at first visit.

Results: Over 7 years, 176 infants met the inclusion criteria. There were no significant differences in the aspects of the early management as a function of age at first visit, with the exception of cast slippage (P=0.05).

Conclusions: The age at first visit influenced the incidence of cast slippage, but otherwise did not affect the early treatment of clubfoot.

Clinical Relevance: The treatment of idiopathic clubfoot deformity should not be considered an orthopaedic emergency, and parents whose infants are born with this deformity should be counseled accordingly.
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http://dx.doi.org/10.1097/BPO.0000000000000514DOI Listing
September 2016

Design control for clinical translation of 3D printed modular scaffolds.

Ann Biomed Eng 2015 Mar 10;43(3):774-86. Epub 2015 Feb 10.

Department of Biomedical Engineering, The University of Michigan, Rm 2214 Lurie Biomedical Engineering Bldg, 1101 Beal Ave, Ann Arbor, MI, USA,

The primary thrust of tissue engineering is the clinical translation of scaffolds and/or biologics to reconstruct tissue defects. Despite this thrust, clinical translation of tissue engineering therapies from academic research has been minimal in the 27 year history of tissue engineering. Academic research by its nature focuses on, and rewards, initial discovery of new phenomena and technologies in the basic research model, with a view towards generality. Translation, however, by its nature must be directed at specific clinical targets, also denoted as indications, with associated regulatory requirements. These regulatory requirements, especially design control, require that the clinical indication be precisely defined a priori, unlike most academic basic tissue engineering research where the research target is typically open-ended, and furthermore requires that the tissue engineering therapy be constructed according to design inputs that ensure it treats or mitigates the clinical indication. Finally, regulatory approval dictates that the constructed system be verified, i.e., proven that it meets the design inputs, and validated, i.e., that by meeting the design inputs the therapy will address the clinical indication. Satisfying design control requires (1) a system of integrated technologies (scaffolds, materials, biologics), ideally based on a fundamental platform, as compared to focus on a single technology, (2) testing of design hypotheses to validate system performance as opposed to mechanistic hypotheses of natural phenomena, and (3) sequential testing using in vitro, in vivo, large preclinical and eventually clinical tests against competing therapies, as compared to single experiments to test new technologies or test mechanistic hypotheses. Our goal in this paper is to illustrate how design control may be implemented in academic translation of scaffold based tissue engineering therapies. Specifically, we propose to (1) demonstrate a modular platform approach founded on 3D printing for developing tissue engineering therapies and (2) illustrate the design control process for modular implementation of two scaffold based tissue engineering therapies: airway reconstruction and bone tissue engineering based spine fusion.
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http://dx.doi.org/10.1007/s10439-015-1270-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4407657PMC
March 2015

Imaging Criteria for the Quantification of Disc Degeneration: A Systematic Review.

JBJS Rev 2015 Feb;3(2)

The J. Vernon Luck, Sr., MD Orthopaedic Research Center, Orthopaedic Institute for Children, in Alliance with UCLA, 403 West Adams Boulevard, Los Angeles, CA 90007.

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http://dx.doi.org/10.2106/JBJS.RVW.N.00056DOI Listing
February 2015

An alternative measurement tool for the identification of hysteretic responses in biological joints.

J Mech Behav Biomed Mater 2014 Nov 8;39:270-8. Epub 2014 Aug 8.

Sonny Astani Dept. of Civil and Environmental Eng., Viterbi School of Engineering, University of Southern California, 3620 S. Vermont Ave, KAP 210, MC 2531, Los Angeles, CA 90089, United States. Electronic address:

In structural engineering, sophisticated multi-dimensional analysis techniques, such as the Restoring Force Method (RFM), have been established for complex, nonlinear hysteretic systems. The purpose of the present study was to apply the RFM to quantify nonlinear spine hysteresis responses under applied moments. First, synthetic hysteretic spine responses (n=50) were generated based on representative results from pure moment flexion-extension loading of a human cadaveric lumbar spine segment. Then, the RFM was applied to each hysteresis response to describe the flexion-extension rotation as a function of applied moment and simulated axial displacement using a set of 16 unique coefficients. Range of motion, neutral zone, elastic zone, and stiffness were also measured. The RFM coefficient corresponding to the 1st-order linear dependence of rotation on applied moment was dominant, and paralleled changes in elastic zone. The remaining RFM coefficients were not captured from the traditional biomechanical analysis. Therefore, the RFM may potentially supplement the traditional analysis to develop a more comprehensive, quantitative description of spine hysteresis. The results suggest the potential for more thorough and specific characterization of spine kinematics, and may lead to future applications of such techniques in characterizing biological structures.
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http://dx.doi.org/10.1016/j.jmbbm.2014.07.033DOI Listing
November 2014
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