Publications by authors named "Thomas R Gardner"

51 Publications

Percutaneous Fixation of Unstable Proximal Phalanx Fractures: A Biomechanical Study.

Hand (N Y) 2021 Jun 9:15589447211017224. Epub 2021 Jun 9.

Columbia University Irving Medical Center, New York, NY, USA.

Background: Unstable extra-articular proximal phalanx fractures are common injuries to the hand that are often treated by closed reduction and percutaneous pinning. Fracture-induced shortening of the proximal phalanx leads to an extensor lag at the proximal interphalangeal joint. We describe a biomechanical study in cadaver hands to compare the ability of each of three different pin configurations to resist shortening in unstable fractures.

Methods: Seventeen fresh frozen hands were disarticulated at the proximal ends of the metacarpals. The second, third, and fourth proximal phalanges were tested. A 5-mm section of bone was resected from the mid-shaft of proximal phalanx to simulate an unstable fracture. Three techniques were employed and randomized for each finger: transmetacarpophalangeal joint pinning using 1 or 2 Kirschner wires (K-wires) and periarticular cross pinning using 2 K-wires. Compressive axial loads and energy at 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm of subsidence were examined.

Results: The forces and energy required to shorten the finger for each amount of subsidence were similar for all 3 pinning techniques and for all 3 finger types. Greater amounts of shortening were found to require larger forces.

Conclusion: Closed reduction and percutaneous pinning using any of the presented techniques is an adequate method of treatment for unstable proximal phalanx fractures. All of the techniques were equivalent in their ability to resist axial loading, regardless of the complexity of technique, the number of pins used, or finger that was pinned.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/15589447211017224DOI Listing
June 2021

Tart Cherry Prevents Bone Loss through Inhibition of RANKL in TNF-Overexpressing Mice.

Nutrients 2018 Dec 29;11(1). Epub 2018 Dec 29.

Department of Orthopaedic Surgery, Columbia University, New York, NY 10032, USA.

Current drugs for the treatment of rheumatoid arthritis-associated bone loss come with concerns about their continued use. Thus, it is necessary to identify natural products with similar effects, but with fewer or no side effects. We determined whether tart cherry (TC) could be used as a supplement to prevent inflammation-mediated bone loss in tumor necrosis factor ()-overexpressing transgenic (TG) mice. TG mice were assigned to a 0%, 5%, or 10% TC diet, with a group receiving infliximab as a positive control. Age-matched wild-type (WT) littermates fed a 0% TC diet were used as a normal control. Mice were monitored by measurement of body weight. Bone health was evaluated via serum biomarkers, microcomputed tomography (µCT), molecular assessments, and mechanical testing. TC prevented TNF-mediated weight loss, while it did not suppress elevated levels of interleukin (IL)-1β and IL-6. TC also protected bone structure from inflammation-induced bone loss with a reduced ratio of receptor activator of nuclear factor kappa-B ligand (RANKL)/osteoprotegerin (OPG) to a degree comparable to infliximab. Furthermore, unlike with infliximab, TC exhibited a moderate improvement in TNF-mediated decline in bone stiffness. Thus, TC could be used as a prophylactic regimen against future fragility fractures in the context of highly chronic inflammation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/nu11010063DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6356454PMC
December 2018

Proximal Humerus Fracture 3-D Modeling.

Am J Orthop (Belle Mead NJ) 2018 Apr;47(4)

Shoulder and Elbow Surgery, Columbia University Medical Center, New York, NY.

The objective of this study is to determine the reproducibility and feasibility of using 3-dimensional (3-D) computer simulation of proximal humerus fracture computed tomography (CT) scans for fracture reduction. We hypothesized that anatomic reconstruction with 3-D models would be anatomically accurate and reproducible. Preoperative CT scans of 28 patients with 3- and 4-part (AO classification 11-B1, 11-B2, 11-C1, 11-C2) proximal humerus fractures who were treated by hemiarthroplasty were converted into 3-D computer models. The displaced fractured fragments were anatomically reduced with computer simulation by 2 fellowship-trained shoulder surgeons, and measurements were made of the reconstructed proximal humerus. The measurements of the reconstructed models had very good to excellent interobserver and intraobserver reliability. The reconstructions of these humerus fractures showed interclass correlation coefficients ranging from 0.71 to 0.93 between 1 observer and from 0.82 to 0.98 between 2 different observers. The fracture reduction was judged against normal proximal humerus geometry to determine reduction accuracy. The 3-D modeling techniques used to reconstruct 3- and 4-part proximal humerus fractures were reliable and accurate. This technique of modeling and reconstructing proximal humerus fractures could be used to enhance the preoperative planning of open reduction and internal fixation or hemiarthroplasty for 3- and 4-part proximal humerus fractures.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.12788/ajo.2018.0023DOI Listing
April 2018

Enhanced tendon-to-bone repair through adhesive films.

Acta Biomater 2018 04 8;70:165-176. Epub 2018 Feb 8.

Department of Orthopedic Surgery, Columbia University, New York, NY 10032, United States; Department of Biomedical Engineering, Columbia University, New York, NY 10027, United States. Electronic address:

Tendon-to-bone surgical repairs have unacceptably high failure rates, possibly due to their inability to recreate the load transfer mechanisms of the native enthesis. Instead of distributing load across a wide attachment footprint area, surgical repairs concentrate shear stress on a small number of suture anchor points. This motivates development of technologies that distribute shear stresses away from suture anchors and across the enthesis footprint. Here, we present predictions and proof-of-concept experiments showing that mechanically-optimized adhesive films can mimic the natural load transfer mechanisms of the healthy attachment and increase the load tolerance of a repair. Mechanical optimization, based upon a shear lag model corroborated by a finite element analysis, revealed that adhesives with relatively high strength and low stiffness can, theoretically, strengthen tendon-to-bone repairs by over 10-fold. Lap shear testing using tendon and bone planks validated the mechanical models for a range of adhesive stiffnesses and strengths. Ex vivo human supraspinatus repairs of cadaveric tissues using multipartite adhesives showed substantial increase in strength. Results suggest that adhesive-enhanced repair can improve repair strength, and motivate a search for optimal adhesives.

Statement Of Significance: Current surgical techniques for tendon-to-bone repair have unacceptably high failure rates, indicating that the initial repair strength is insufficient to prevent gapping or rupture. In the rotator cuff, repair techniques apply compression over the repair interface to achieve contact healing between tendon and bone, but transfer almost all force in shear across only a few points where sutures puncture the tendon. Therefore, we evaluated the ability of an adhesive film, implanted between tendon and bone, to enhance repair strength and minimize the likelihood of rupture. Mechanical models demonstrated that optimally designed adhesives would improve repair strength by over 10-fold. Experiments using idealized and clinically-relevant repairs validated these models. This work demonstrates an opportunity to dramatically improve tendon-to-bone repair strength using adhesive films with appropriate material properties.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.actbio.2018.01.032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5871607PMC
April 2018

Comparison of Exposure in the Kaplan Versus the Kocher Approach in the Treatment of Radial Head Fractures.

Hand (N Y) 2019 03 22;14(2):253-258. Epub 2018 Jan 22.

2 Columbia University, New York City, NY, USA.

Background: The aim of this study was to compare the complete visible surface area of the radial head, neck, and coronoid in the Kaplan and Kocher approaches to the lateral elbow. The hypothesis was that the Kaplan approach would afford greater visibility due to the differential anatomy of the intermuscular planes.

Methods: Ten cadavers were dissected with the Kaplan and Kocher approaches, and the visible surface area was measured in situ using a 3-dimensional digitizer. Six measurements were taken for each approach by 2 surgeons, and the mean of these measurements were analyzed.

Results: The mean surface area visible with the lateral collateral ligament (LCL) preserved in the Kaplan approach was 616.6 mm in comparison with the surface area of 136.2 mm visible in the Kocher approach when the LCL was preserved. Using a 2-way analysis of variance, the difference between these 2 approaches was statistically significant. When the LCL complex was incised in the Kocher approach, the average visible surface area of the Kocher approach was 456.1 mm and was statistically less than the Kaplan approach. The average surface area of the coronoid visible using a proximally extended Kaplan approach was 197.8 mm.

Conclusions: The Kaplan approach affords significantly greater visible surface area of the proximal radius than the Kocher approach.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/1558944717745662DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6436133PMC
March 2019

Step-wise medial collateral ligament needle puncturing in extension leads to a safe and predictable reduction in medial compartment pressure during TKA.

Knee Surg Sports Traumatol Arthrosc 2018 Jun 22;26(6):1759-1766. Epub 2017 Nov 22.

Center for Hip and Knee Replacement, Columbia University Medical Center, 622 West 168th Street, PH 1147, New York, NY, 10032, USA.

Purpose: Medial soft tissue release in a varus deformity knee during total knee arthroplasty is essential for accurate balancing of the reconstruction. This study attempts to quantify the effect of sequential needle puncturing of the medial collateral ligament (MCL) using a pressure sensor insert (Verasense by OrthoSensor) and gap measurement under tension.

Methods: Cruciate-retaining arthroplasties were placed in 14 cadaveric knees. The MCL was elongated by step-wise perforation, in five sets of five perforations, with the use of an 18-gauge needle, followed by valgus stress. Following the fifth set of needle perforations, blade perforation was performed on the remaining tense fibers of the MCL. Following each step-wise perforation, corresponding medial compartment pressures and gap measurements under tension were recorded.

Results: Sensor measurements correlated closely with step-wise tissue release (R = 0.73, p < 0.0001), and a significant decrease in pressure was found in early needle puncturing (mean 49 N after 5, 83 N after 15, p values < 0.05), although changes diminished at later stages of needle perforation (90 N after 20). Gap measurement demonstrated small gradual changes with early puncturing, but showed significant opening in the later stages of release. There was minimal variation in pressure or gap measurements in flexion versus extension. This finding suggests that MCL needle puncture will not lead to unequal gaps between flexion and extension. There were no cases of MCL over-release after 15 punctures, one case after 20 punctures, and three after blade perforation.

Conclusion: Needle puncturing of the MCL in extension for up to 15 punctures can be a safe and predictable way to achieve medial opening when balancing a varus knee during TKA as demonstrated in this cadaveric model. Blade perforation should be used with caution to avoid over-release. The needle puncture method can be used by surgeons to achieve reliable reductions in medial compartment pressures, to help achieve a balanced TKA, with minimal risk of over-release.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00167-017-4777-2DOI Listing
June 2018

Reliability of 3-Dimensional Glenoid Component Templating and Correlation to Intraoperative Component Selection.

Am J Orthop (Belle Mead NJ) 2017 Sep/Oct;46(5):E280-E292

Center for Shoulder, Elbow, and Sports Medicine, Department of Orthopaedic Surgery, Columbia University Medical Center, New York, NY.

Although implant-specific intraoperative targeting devices for glenoid sizing exist, a validated method for preoperatively templating glenoid component size in primary total shoulder arthroplasty (TSA) based on digital imaging does not. We conducted a study to determine if 3-dimensional (3-D) digital imaging could be used for preoperative templating of glenoid component size and to compare templated glenoid sizes with implanted glenoid sizes. We created 3-D digital models from 3 glenoid component implant sizes and preoperative scapular computed tomography scans of 24 patients who underwent primary TSA. In study arm 1, surgeons templated the 3-D components using only 2 df (superior-inferior and anterior-posterior planes). In study arm 2, surgeons templated the 3-D components using 6 df (superior-inferior, anterior-posterior, and rotational planes). Overall intraobserver agreement was substantial (0.67) in study arm 1 (P < .001) and moderate (0.58) in study arm 2 (P < .001). In arm 1, overall interobserver agreement was fair (0.36) for trial 1 (P < .001) and fair (0.32) for trial 2 (P < .001). In arm 2, overall interobserver agreement was moderate (0.54) for trial 1 (P < .001) and moderate (0.43) for trial 2 (P < .001). In both arms, surgeons tended to template glenoid components smaller than those implanted intraoperatively, particularly for female patients. Our findings show that 3-D digital models can be consistently and reliably used for preoperative templating of glenoid com-ponent size.
View Article and Find Full Text PDF

Download full-text PDF

Source
June 2018

Effects of Platelet-Rich Plasma and Indomethacin on Biomechanics of Rotator Cuff Repair.

Am J Orthop (Belle Mead NJ) 2017 Sep/Oct;46(5):E336-E343

Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL.

We conducted a study to determine if platelet-rich plasma (PRP) enhances the strength of rotator cuff repair (RCR) and if concomitant use of nonsteroidal anti-inflammatory drugs (NSAIDs) affects PRP efficacy. We also wanted to determine the optimal centrifugation protocol for making PRP from rats. This study used 48 rats, 14 in a centrifugation protocol and 34 in an operative protocol. Six syngeneic rats from the operative group were used as PRP blood donors; the other 28 operative rats underwent bilateral RCRs. The Autologous Conditioned Plasma system (Arthrex) was used to prepare leukocyte-poor PRP. One shoulder was randomized to an intratendinous PRP injection, and the other received normal saline. Each rat was also randomly placed on a postoperative diet, either a regular diet or an indomethacin-enhanced diet. After rats were euthanized at 3 weeks, specimens were dissected to isolate the supraspinatus tendon at its humeral attachment, which was subjected to biomechanical testing. PRP prepared with a protocol of 5 minutes × 1300 revolutions per minute had the highest platelet index. Mean (SD) energy to failure was significantly higher (P = .03) in tendons treated with PRP, 11.7 (7.3) N-mm, than in tendons treated with saline, 8.7 (4.6) N-mm. Both groups (PRP, saline) showed no significant differences between tendons treated with NSAIDs and those not treated with NSAIDs. Intraoperative application of PRP enhances energy to failure after RCR in rats. There were no differences in biomechanical strength with NSAID use and no interactions between PRP and NSAID use.
View Article and Find Full Text PDF

Download full-text PDF

Source
June 2018

Optimal internal fixation of anatomically shaped synthetic bone grafts for massive segmental defects of long bones.

Clin Biomech (Bristol, Avon) 2015 Dec 2;30(10):1114-8. Epub 2015 Sep 2.

Robert E. Carroll, MD and Jane Chace Carroll Laboratories for Orthopedic Surgery, Department of Orthopedic Surgery, College of Physicians and Surgeons, Columbia University, New York, NY, USA. Electronic address:

Background: Large segmental bone defects following tumor resection, high-energy civilian trauma, and military blast injuries present significant clinical challenges. Tissue engineering strategies using scaffolds are being considered as a treatment, but there is little research into optimal fixation of such scaffolds.

Methods: Twelve fresh-frozen paired cadaveric legs were utilized to simulate a critical sized intercalary defect in the tibia. Poly-ε-caprolactone and hydroxyapatite composite scaffolds 5 cm in length with a geometry representative of the mid-diaphysis of an adult human tibia were fabricated, inserted into a tibial mid-diaphyseal intercalary defect, and fixed with a 14-hole large fragment plate. Optimal screw fixation comparing non-locking and locking screws was tested in axial compression, bending, and torsion in a non-destructive manner. A cyclic torsional test to failure under torque control was then performed.

Findings: Biomechanical testing showed no significant difference for bending or axial stiffness with non-locking vs. locking fixation. Torsional stiffness was significantly higher (P=0.002) with the scaffold present for both non-locking and locking compared to the scaffold absent. In testing to failure, angular rotation was greater for the non-locking compared to locking constructs at each torque level up to 40 N-m (P<0.05). The locking constructs survived a significantly higher number of loading cycles before reaching clinical failure at 30 degrees of angular rotation (P<0.02).

Interpretation: The presence of the scaffold increased the torsional stiffness of the construct. Locking fixation resulted in a stronger construct with increased cycles to failure compared to non-locking fixation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.clinbiomech.2015.08.016DOI Listing
December 2015

A new method for achieving compression in hindfoot arthrodesis.

Int Orthop 2015 Nov 23;39(11):2267-74. Epub 2015 Jul 23.

Department of Orthopaedic Surgery, Columbia University Medical Center, 622 West 168th St, PH 11th floor, New York, NY, 10032, USA.

Background: When performing hindfoot arthodeses, one goal of fixation is often to achieve compression across the joint. Traditional lag screws are applied eccentrically, providing compression more on the edge of the fusion. A new technique, using a post in one bone and a lag screw through the post to the other bone, may offer better compression across more of the joint.

Methods: There are three parts to this study comparing a post-and-screw construct to traditional lag screws. Synthetic bone models, representative of the talonavicular joint, were created and assessed for biomechanical measures of compression. Next, the post-and-screw construct was tested in cadavers, under conditions representing early weight bearing after arthrodesis surgery. Finally, 18 patients who had a talonavicular fusion with a post-and-screw construct with one surgeon were compared to the previous 18 patients fixed with traditional screws.

Results: In the synthetic bone model, the post-and-screw construct brought the centre of compression closer to the centre of the joint, suggesting compression was less eccentric. Neither traditional screws nor the post-and-screw construct were sufficiently strong to resist early weight bearing forces in cadaver specimens. In the clinical comparison, four patients had a painful nonunion when fixed with traditional screws, compared to none in the post-and-screw construct.

Conclusions: A post-and-screw construct spreads the forces of compression more uniformly across an arthrodesis, even when placed eccentrically. Although not all the biomechanical measures were superior, the post-and-screw construct achieved higher levels of successful fusion in patients. This technology may offer improved outcomes in some clinical scenarios and deserves further study.

Level Of Evidence: Level 3.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00264-015-2855-yDOI Listing
November 2015

Inter- and intra-observer agreement of femoroacetabular impingement (FAI) parameters comparing plain radiographs and advanced, 3D computed tomographic (CT)-generated hip models in a surgical patient cohort.

Knee Surg Sports Traumatol Arthrosc 2016 Jul 26;24(7):2324-31. Epub 2014 Sep 26.

MacSports at McMaster University, 1200 Main Street West, Room 4E17, Hamilton, ON, L8S 4L8, Canada.

Purpose: The purpose of our study was to investigate whether advanced, 3D computed tomographic (CT)-generated hip models improves inter-and intra-observer agreement when compared to plain radiographs in identifying femoroacetabular impingement (FAI) morphology.

Methods: Eight consecutive patients who underwent surgery for FAI pathology were selected for this study. Preoperative CT scan image data were used to create high resolution, 3D hip reconstruction models. Four observers (two attending hip surgeons and radiologists) performed a blinded review of preselected radiographs and 3D CT hip models. Alpha and lateral center-edge angle measurements, location of cam lesion and the presence of a "crossover sign" were assessed. Inter- and intra-observer agreement was determined by calculating the intra-class correlation coefficients (ICC) or kappa coefficients to evaluate agreement for categorical variables.

Results: The parameter that demonstrated the highest and poorest inter-observer agreement was the presence of a "crossover sign" using 3D CT-generated high resolution hip models (ICC = 0.76, p = 0.00) and anteroposterior pelvis radiography, respectively (ICC = 0.20, p = 0.02). Alpha angle values were significantly higher using plain radiographs when compared to 3D hip reconstruction models (61.1° ± 10.4° versus 55.4° ± 14.4°, p = 0.003). Furthermore, when compared to radiographs, 3D hip reconstruction models demonstrated significantly higher intra-observer agreement (ICC = 0.856 versus 0.405, p = 0.005) when determining the presence of a "crossover sign".

Conclusions: Our findings were suggestive that for most commonly used FAI morphology parameters, CT-generated hip models demonstrated little benefit over plain radiographs in improving inter-observer agreement among providers.

Level Of Evidence: III.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00167-014-3315-8DOI Listing
July 2016

Influence of Rotator Cuff Tear Size and Repair Technique on the Creation and Management of Dog Ear Deformities in a Transosseous-Equivalent Rotator Cuff Repair Model.

Orthop J Sports Med 2014 Apr 16;2(4):2325967114529257. Epub 2014 Apr 16.

Department of Orthopaedic Surgery, Columbia University Medical Center, New York, New York, USA.

Background: Redundancies in the rotator cuff tissue, commonly referred to as "dog ear" deformities, are frequently encountered during rotator cuff repair. Knowledge of how these deformities are created and their impact on rotator cuff footprint restoration is limited.

Purpose: The goals of this study were to assess the impact of tear size and repair method on the creation and management of dog ear deformities in a human cadaveric model.

Study Design: Controlled laboratory study.

Methods: Crescent-shaped tears were systematically created in the supraspinatus tendon of 7 cadaveric shoulders with increasing medial to lateral widths (0.5, 1.0, and 1.5 cm). Repair of the 1.5-cm tear was performed on each shoulder with 3 methods in a randomized order: suture bridge, double-row repair with 2-mm fiber tape, and fiber tape with peripheral No. 2 nonabsorbable looped sutures. Resulting dog ear deformities were injected with an acrylic resin mixture, digitized 3-dimensionally (3D), and photographed perpendicular to the footprint with calibration. The volume, height, and width of the rotator cuff tissue not in contact with the greater tuberosity footprint were calculated using the volume injected, 3D reconstructions, and calibrated photographs. Comparisons were made between tear size, dog ear measurement technique, and repair method utilizing 2-way analysis of variance and Student-Newman-Keuls multiple-comparison tests.

Results: Utilizing 3D digitized and injection-derived volumes and dimensions, anterior dog ear volume, height, and width were significantly smaller for rotator cuff repair with peripheral looped sutures compared with a suture bridge (P < .05) or double-row repair with 2-mm fiber tape alone (P < .05). Similarly, posterior height and width were significantly smaller for repair with looped peripheral sutures compared with a suture bridge (P < .05). Dog ear volumes and heights trended larger for the 1.5-cm tear, but this was not statistically significant.

Conclusion: When combined with a standard transosseous-equivalent repair technique, peripheral No. 2 nonabsorbable looped sutures significantly decreased the volume, height, and width of dog ear deformities, better restoring the anatomic footprint of the rotator cuff.

Clinical Relevance: Dog ear deformities are commonly encountered during rotator cuff repair. Knowledge of a repair technique that reliably decreases their size, and thus increases contact at the anatomic footprint of the rotator cuff, will aid sports medicine surgeons in the management of these deformities.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/2325967114529257DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4555599PMC
April 2014

Comparison of radiographic stress tests for syndesmotic instability of supination-external rotation ankle fractures: a cadaveric study.

J Orthop Trauma 2014 Jun;28(6):e123-7

Columbia Orthopaedic Surgery, New York Presbyterian Hospital, New York, NY.

Objective: According to the classification of Lauge-Hansen, supination-external rotation IV (OTA 44-B) injuries should not have syndesmotic instability; yet, several studies have suggested disruption is present in up to 40% of these injuries based on stress tests. In this study, we examine various stress radiographic parameters in a cadaver model of supination-external rotation IV equivalent injury. We hypothesize that external rotation stress testing and widening of the medial clear space do not always represent syndesmotic instability. Rather, the better predictor of syndesmotic instability will be an increased tibia-fibula clear space with the lateral stress test.

Methods: Eleven fresh frozen human lower limbs were each secured into a custom frame. External rotation stress test was performed by applying an external moment of 7.5 Nm, and lateral stress test was performed by applying 100 N lateral pull at the distal fibula. True mortise radiographs were taken of intact ankles and while performing external rotation and lateral stress tests at each stage of sequentially sectioning the ankle ligaments. The deltoid ligament was sectioned first, then anterior-inferior tibiofibular ligament, posterior-inferior tibiofibular ligament, and interosseous membrane. Tibiofibular clear space and medial clear space were measured on each radiograph.

Results: External rotation stress test produced significant medial clear space widening when the deltoid ligaments were sectioned (P < 0.05). Lateral stress test produced no significant widening of the tibiofibular clear space until interosseous membranes were sectioned (P < 0.05).

Conclusions: Lateral stress test with widening of the tibiofibular clear space is the preferred indicator of syndesmotic instability. The external rotation stress is a poor indicator of syndesmotic injury in the setting of deltoid ligament injury.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/BOT.0000000000000010DOI Listing
June 2014

Characterizing bone tunnel placement in medial ulnar collateral ligament reconstruction using patient-specific 3-dimensional computed tomography modeling.

Am J Sports Med 2013 Apr 25;41(4):894-902. Epub 2013 Feb 25.

Department of Orthopaedic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA.

Background: Medial ulnar collateral ligament (MUCL) reconstruction is successful in restoring valgus elbow stability, but variability in bone tunnel characteristics exists among surgical techniques.

Hypothesis: Tunnel parameters such as diameter, drill angle, and starting location in MUCL reconstruction affect tunnel length and bone bridge size between tunnels.

Study Design: Descriptive laboratory study.

Methods: Three-dimensional models were created from elbow computed tomography scans of 10 throwing athletes and analyzed using Mimics (Materialise) software. The MUCL reconstructions were simulated on each elbow with 3 techniques: Jobe, humeral docking, and DANE TJ. Humeral central tunnels were modified by diameter, medial-lateral epicondylar starting point, and angle with respect to the humeral axis. Ulnar tunnels were varied by diameter and angle with respect to the ulnar axis. Humeral tunnel length, humeral and ulnar bone bridge sizes, and ulnar tunnel aperture and distance from the articular surface of the olecranon were measured. Comparisons were made using 1- and 2-way analysis of variance and Student-Newman-Keuls multiple comparison tests.

Results: Mean central humeral tunnel length varied significantly by starting point and angulation of the tunnel both in sagittal and coronal planes, ranging from 14.2 ± 2.3 mm to 25.5 ± 4.3 mm (P < .05). Mean bone bridge size between humeral exit tunnels ranged from 9.0 ± 2.5 mm to 15.1 ± 3.1 mm, varying by central humeral tunnel orientation and exit tunnel diameter (P < .05). Bone bridge size between ulnar tunnels with the Jobe and docking techniques averaged 6.7 ± 0.9 mm (3.2-mm tunnels) and 6.4 ± 0.8 mm (3.5-mm tunnels), respectively. Angle of ulnar tunnels affected distance from the articular surface with the Jobe and docking techniques (P < .0001) and affected tunnel aperture size with the interference screw technique (P < .0001).

Conclusion: Humeral and ulnar tunnel angles, starting points, and diameters affect tunnel length, distance from the articular surface, and bone bridge size in MUCL reconstructions. Maximal humeral tunnel length is achieved by starting central or lateral to the midpoint of the epicondyle, angulated 30° to the humeral axis in the sagittal plane and 15° in the coronal plane. A reasonable goal tunnel depth should range from 15 to 20 mm. Ulnar tunnels should be placed on the anterior and posterior aspects of the sublime tubercle, directed away from the joint to minimize the likelihood of breaching the articular cartilage. A bone bridge of 6 to 8 mm between these tunnels can be reasonably achieved. Tunnels with the ulnar interference screw fixation technique should also be directed away from the joint but at an angle more perpendicular than 45° to minimize tunnel aperture size. Regardless of angle of the tunnel drilled for the ulnar interference screw employed in the DANE TJ technique, the tunnel length is sufficient to fully contain a 15-mm screw.

Clinical Relevance: Computer models can guide MUCL reconstruction technique by indicating tunnel placement for maximizing the bone bridge and tunnel length.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/0363546513477377DOI Listing
April 2013

Rotator cuff repair augmentation with local autogenous bone marrow via humeral cannulation in a rat model.

J Shoulder Elbow Surg 2013 Sep 1;22(9):1256-64. Epub 2013 Feb 1.

Department of Orthopaedic Surgery, Columbia University Medical Center, 622 W. 168th St., New York, NY 10032, USA.

Background: Growth factors have been shown to improve healing after rotator cuff repair. Bone marrow is a potential vehicle for growth factor augmentation, yet methods of delivering marrow to cuff repair sites are still under-researched. We hypothesized that a cannulated humeral implant would deliver local bone marrow and thereby improve healing in a rat model.

Methods: Twenty-eight rats underwent bilateral rotator cuff injury and repair. Each rat acted as its own control, randomized to a cannulated humeral implant in one shoulder and a solid implant in the other. Rats were euthanized at 4 and 8 weeks to create 4 time-treatment cohorts. Tendon healing was evaluated by dimensional measurements, biomechanical testing, and histology.

Results: Tendon thickness, all biomechanical measures, and semi-quantitative histologic scores improved over time (P < .05) but not with treatment. The most common site of biomechanical tendon failure was midsubstance in the 8-week cannulated cohort and at the tendon footprint in the other 3 cohorts. Intraluminal bone growth was evident in all cannulated implants.

Conclusions: Humeral cannulation did not quantifiably improve tendon-to-bone healing in a rat model. The diminutive size of implants in rats, however, may have prevented sufficient delivery of local autogenous bone marrow; hence, further study in a larger animal is recommended.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jse.2012.11.014DOI Listing
September 2013

Glenoid implant orientation and cement failure in total shoulder arthroplasty: a finite element analysis.

J Shoulder Elbow Surg 2013 Jul 10;22(7):940-7. Epub 2013 Jan 10.

Centers for Orthopaedic Research and Shoulder, Elbow and Sports Medicine, Department of Orthopaedic Surgery, Columbia University, New York, NY 10032, USA.

Background: To minimize glenoid implant loosening in total shoulder arthroplasty (TSA), the ideal surgical procedure achieves correction to neutral version, complete implant-bone contact, and bone stock preservation. These goals, however, are not always achievable, and guidelines to prioritize their impact are not well established. The purpose of this study was to investigate how the degree of glenoid correction affects potential cement failure.

Methods: Eight patient-specific computer models were created for 4 TSA scenarios with different permutations of retroversion correction and implant-bone contact. Two bone models were used: a homogeneous cortical bone model and a heterogeneous cortical-trabecular bone model. A 750-N load was simulated, and cement stress was calculated. The risk of cement mantle fracture was reported as the percentage of cement stress exceeding the material endurance limit.

Results: Orienting the glenoid implant in retroversion resulted in the highest risk of cement fracture in a homogeneous bone model (P < .05). In the heterogeneous bone model, complete correction resulted in the highest risk of failure (P = .0028). A positive correlation (ρ = 0.901) was found between the risk of cement failure and amount of exposed trabecular bone.

Conclusions: Incorporating trabecular bone into the model changed the effect of implant orientation on cement failure. As exposed trabecular bone increased, the risk of cement fracture increased. This may be due to shifting the load-bearing support underneath the cement from cortical bone to trabecular bone.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jse.2012.09.007DOI Listing
July 2013

Glenoid articular conformity affects stress distributions in total shoulder arthroplasty.

J Shoulder Elbow Surg 2013 Mar 11;22(3):350-6. Epub 2012 Dec 11.

Department of Orthopaedic Surgery, Columbia University Centers for Orthopaedic Research and Shoulder, Elbow and Sports Medicine, New York, NY 10032, USA.

Background: The stress applied to the glenoid component in total shoulder arthroplasty (TSA) remains an important concern because of the risk of wear and loosening. The purpose of this study was to determine the stress pattern in the glenoid component with 3 different surface designs.

Methods: Computer models of 9 scapulae of patients scheduled for TSA were created from computerized tomography images. Each glenoid was virtually reamed, and 3 different glenoid component designs (conforming, nonconforming, and hybrid) were placed. Using finite element analysis, superior translation of the humeral head was modeled. Maximum stress and shear stress were measured at 3 different locations in the glenoid component: center, transition, and superior regions.

Results: All 3 designs showed a similar level of maximum stress at the center and transition regions, while the maximum stress at the superior periphery was significantly higher in the conforming design than in the other 2 designs (P = .0017). The conforming design showed significantly higher shear stress at the superior periphery (P < .0001).

Discussion: Stress from periphery loading is higher than from the center and transition region regardless of component design and is highest in the conforming design. The stress at the transition region of the hybrid design was not higher than the other 2 designs. The hybrid design has favorable characteristics based on its low stress at the periphery and greater contact area with the humeral head at the center.

Level Of Evidence: Basic Science Study, Biomechanical Computer Simulation Study.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jse.2012.08.025DOI Listing
March 2013

Transillumination of hand tumors: a cadaver study to evaluate accuracy and intraobserver reliability.

Hand (N Y) 2011 Dec 7;6(4):390-3. Epub 2011 Sep 7.

Department of Orthopaedic Surgery New York Presbyterian Hospital, Columbia-Presbyterian Medical Center, 622 West 168th Street PH-11-1119, New York, NY 10032 USA.

Background: The aim of this study was to assess the accuracy and intraobserver reliability of the technique of penlight transillumination of simulated hand tumors as well as the rationale for the technique.

Methods: Eight observers examined small (9.5 mm) plastic spheres in a fresh frozen cadaveric human hand 3 weeks apart in a blinded manner. The observers were divided into two overall groups based on their level of training. Four spheres simulating hand tumors (two dorsal and two palmar) were placed subcutaneously. The spheres were known to either transilluminate or to be opaque. The observers noted their impression as to whether the spheres either did or did not transilluminate. Accuracy and multi-rater-kappa-statistical analysis were performed.

Results: The overall accuracy was 87.5%: 95% for senior group, 81% for junior group (P = .388, not significant). The average kappa of the intraobserver reliability overall was 0.46. The senior group had a kappa value of 0.67 (substantial agreement), the "junior" group: 0.25 (fair agreement).

Conclusions: Accuracy at correctly determining whether or not a small hand tumor transilluminated was high. The senior group was more accurate overall in correctly determining transillumination, though not with statistical significance. Intraobserver reliability was high for the senior group and less robust for the junior group.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11552-011-9358-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3213256PMC
December 2011

Scaphoid excision and 4-bone arthrodesis versus proximal row carpectomy: a comparison of contact biomechanics.

J Hand Surg Am 2012 Sep;37(9):1861-7

Trauma Training Center, Department of Orthopaedic Surgery, Columbia University Medical Center, New York, NY 10032, USA.

Purpose: We compare scaphoid excision and 4-bone arthrodesis (FBA) with proximal row carpectomy (PRC) in terms of contact pressure, area, and location.

Methods: Six cadaveric forearms underwent simulated FBA with K-wires. We measured pressures in the radiocarpal joint with Fuji contact film after we applied a 200-N load via the wrist tendons with the wrist in neutral, flexion, and extension. We repeated the experiment after excising the lunate and triquetrum, to create a PRC in the same specimens.

Results: Contact pressure in the PRC wrist was significantly greater, by 25%, compared with the FBA wrist for all wrist positions. The PRC wrist had a significantly smaller contact area, by 43%, compared with the FBA wrist. In the FBA wrist, lunate contact was more dorsal in flexion but more volar in extension. In the PRC wrist, capitate contact was more dorsal and radial in flexion, whereas the contact was more volar and ulnar in extension. Comparing contact location, FBA contact was significantly more ulnar than PRC contact in wrist flexion. We found no significant difference in contact translation (the distance between the contact locations in the positions of wrist flexion and extension) for the lunate in FBA or the capitate in PRC.

Conclusions: The FBA wrist has significantly lower contact pressure (P < .001), greater contact area (P < .001), and equal contact translation compared with the PRC wrist. These qualities may make FBA less susceptible to degeneration over time. By advancing our understanding of the biomechanics of both wrist procedures, we may better tailor them to the individual patient.

Clinical Relevance: Current biomechanical evidence is lacking for common motion-preserving procedures for wrist arthritis. Comparing contact pressure, area, and location provides a biomechanical basis of our clinical understanding of these surgeries.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jhsa.2012.05.040DOI Listing
September 2012

A rat model of chondrocyte death after closed intra-articular fracture.

J Orthop Trauma 2013 Mar;27(3):e50-6

Department of Orthopaedic Surgery, New York Orthopaedic Hospital, Columbia University Medical Center, New York, NY, USA.

Objective: The development of osteoarthritis after intra-articular fractures has been described for decades, although the exact mechanical and cellular changes that occur remain poorly understood. There are several animal models to study this phenomenon, but they are mechanistically different from physiologic fractures in several important ways. This article describes a novel model that recreates the kinematics present in high-energy trauma and intra-articular fractures.

Methods: We designed a "drop tower" for the creation of intercondylar femoral fractures in rats and tested it on cadaveric rats to determine the optimal kinetic parameters. Intra-articular fractures were then created in live rats and the animals were killed at 0, 24, and 72 hours after the fracture. Cartilage samples were obtained for live/dead staining, and the relationships among fracture time, cartilage depth, and cell viability were evaluated.

Results: The model reproduced intra-articular fractures very similar to those seen in high-energy trauma, although we required significantly higher energies (3600 mJ) than those reported in other fracture models (40-200 mJ). Cartilage viability decreased with time (68% immediately after the fracture and 46% at 72 hours, P = 0.02) and increased with depth from the articular surface (47% at the surface vs. 66% in the deepest layer, P = 0.001).

Conclusions: This model is a physiologically relevant reliable method for creating intra-articular fractures in rats and can produce meaningful data about the biologic changes occurring in cartilage after injury. Cell viability decreases with time postfracture and with proximity to the articular surface.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/BOT.0b013e318251e66dDOI Listing
March 2013

Glenoid morphology after reaming in computer-simulated total shoulder arthroplasty.

J Shoulder Elbow Surg 2013 Jan 21;22(1):122-8. Epub 2012 Apr 21.

Center for Orthopaedic Research and Center for Shoulder, Elbow and Sports Medicine, Department of Orthopaedic Surgery, Columbia University, 622 W 168th St, New York, NY 10032, USA.

Background: The relationships between reaming parameters for glenoid-implant surface area and bone loss in total shoulder arthroplasty have not been well established. The hypotheses of this study are: (1) for large version corrections, a large reaming depth of 5 mm is not sufficient to obtain complete glenoid implant contact; (2) glenoid bone is removed in a linear proportion with reaming depth; and (3) initial reamer placement has no effect on glenoid bone removal.

Methods: Ten computer models from computed tomography scans of patients with advanced osteoarthritis were created for computer-simulated reaming as performed during total shoulder arthroplasty. Reaming variables studied included reaming depth, reamer placement, and version correction. The resulting reamed glenoid surface area available for implantation and bone volume removed were calculated for each permutation.

Results: Reamed surface area significantly increased with larger depths of reaming (P < .0001) and smaller version corrections (P < .0001). Bone volume removed and reaming depth had a strong quadratic relationship (r(2) = 0.999). With off-center reamer placement, volume removed when deviating in the posterior direction was significantly greater than when deviating in the anterior, superior, or inferior direction (P < .05).

Conclusion: Performing smaller version corrections allows for greater attainable implant-bone surface contact because increasing reaming depth results in small increases in conforming surface area but large losses in glenoid bone stock. Bone volume removed was most sensitive to off-center position errors in the posterior direction.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jse.2011.12.010DOI Listing
January 2013

Perioperative polyphenon E, a green tea extract, does not affect the wound complication rate in mice after sham laparotomy yet has an inhibitory effect on wound healing.

Surg Innov 2012 Dec 18;19(4):399-406. Epub 2012 Mar 18.

Columbia University, New York, NY, USA.

Introduction: Major surgery is associated with physiologic alterations that may promote tumor growth, and catechins in green tea may inhibit tumor growth. This study's aim was to assess the impact of a green tea extract on laparotomy wound healing in mice.

Methods: Mice were randomized to daily oral catechins solution (n = 25) or placebo (n = 20), underwent sham laparotomy after 10 days, and were sacrificed on postoperative day 7 or 21. The peak force and total energy required to rupture the abdominal wall wound, wound collagen content, and histology were assessed.

Results: There were no wound complications in either group, and mean peak wound rupture forces and collagen concentration were similar. Mean energy was lower and more fibroblast proliferation was found in the treatment group on postoperative day 21.

Conclusions: These results suggest that catechins has only mild clinically significant adverse effect on wound healing, and its perioperative use warrants further study.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/1553350612436565DOI Listing
December 2012

Perioperative polyphenon E- and siliphos-inhibited colorectal tumor growth and metastases without impairment of gastric or abdominal wound healing in mouse models.

Surg Endosc 2012 Jul 19;26(7):1856-64. Epub 2012 Jan 19.

Colon & Rectum Surgery, St. Luke's Roosevelt Hospital Center, 432 West, 58th Street, Room 517, New York, NY 10019, USA.

Introduction: Perioperative anticancer therapy that does not impair wound healing is needed to counter the persistent proangiogenic plasma compositional changes that occur after colorectal resection. Polyphenon E (PolyE), a green tea derivative (main component EGCG), and Siliphos (main component silibinin), from the milk thistle plant, both have antitumor effects. This study assessed the impact of PolyE/Siliphos (PES) on wound healing and the growth of CT-26 colon cancer in several murine models.

Methods: One wound healing and three tumor studies were performed. Tumor Study (TS)1 assessed the impact of PES on subcutaneous tumor growth, whereas TS2 assessed PES's impact on subcutaneous growth when given pre- and post-CO(2) pneumoperitoneum (pneumo), sham laparotomy, or anesthesia alone. TS3 determined the ability of PES to limit hepatic metastases (mets) after portal venous injection of tumor cells. In the final study, laparotomy and gastrotomy wound healing were assessed several ways. BALB/c mice were used for all studies. The drugs were given via drinking water (PolyE) and gavage (Siliphos), daily, for 7-9 days preprocedure and for 7-21 days postoperatively. Tumor mass, number/size of hepatic mets, and proliferation and apoptosis rates were assessed. The abdominal breaking strength and energy to failure were measured postmortem as was gastric bursting pressures.

Results: PES significantly inhibited subcutaneous growth in the nonoperative setting. PES also significantly decreased the number/size of liver mets when given perioperatively. Abdominal wound breaking strength, energy to wound failure, and collagen content were not altered by PES; gastrotomy bursting strength also was not affected by PES. Neither drug alone had a significant impact on tumor growth.

Conclusions: The PES combination inhibited subcutaneous and hepatic tumor growth yet did not impair wound healing. PES holds promise as a perioperative anticancer therapy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00464-011-2114-2DOI Listing
July 2012

An anatomic and biomechanical study of the oblique retinacular ligament and its role in finger extension.

J Hand Surg Am 2011 Dec;36(12):1959-64

Department of Orthopaedic Surgery, Columbia University Medical Center, New York, NY 10032, USA.

Purpose: To analyze the anatomy and contribution of the oblique retinacular ligament (ORL) to distal interphalangeal (DIP) joint extension force with varying angles of proximal interphalangeal (PIP) and metacarpophalangeal (MCP) joint flexion.

Methods: Forty fresh-frozen fingers were dissected. The fingers were mounted in a custom jig, and the force required to flex the DIP joint was assessed with the PIP joint flexed 0°, 30°, 60°, and 90° and with the MCP joint flexed 0°, 45°, and 90°. The force was measured in the intact specimen, and then all measurements were repeated following sectioning of the ORL and then the central slip.

Results: The ORL was present on the radial and ulnar aspects of all but 2 fingers. The ORL tended to be the most robust in the ring finger. In the intact specimen, DIP flexion resistance force was maximum at 30° of PIP joint flexion and minimum at 90° of PIP joint flexion. There was a significant difference between the 90° position and all other positions of the PIP joint with respect to flexion force in the intact specimen. This meant that less force was required to flex the DIP joint at 90° of PIP joint flexion. Sectioning of the ORL revealed that it contributed 25% to the total force required to flex the DIP joint with the PIP joint at 0°, 31% at 30°, 18% at 60°, and 3% at 90° of flexion. The MCP joint position had no effect. Sectioning the central slip produced a significant increase in force required to flex the DIP joint at 90° of PIP joint flexion.

Conclusions: In this study, the ORL was usually present, and it contributed up to 30% of the passive resistance to DIP joint flexion. The intact central slip accounted for the decrease in DIP joint extensor tone at 90° of PIP joint flexion.

Clinical Relevance: The ORL plays a small role in passively resisting DIP flexion.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jhsa.2011.09.033DOI Listing
December 2011

Reverse total shoulder arthroplasty for cuff tear arthropathy: the clinical effect of deltoid lengthening and center of rotation medialization.

J Shoulder Elbow Surg 2012 Oct 6;21(10):1269-77. Epub 2011 Nov 6.

Department of Orthopaedic Surgery, Columbia University Medical Center, New York, NY 10032, USA.

Background: Reverse total shoulder arthroplasty (RSA) for cuff tear arthropathy improves shoulder function and reduces pain. Implant position and soft tissue balancing are important factors to optimize outcome. Tensioning the deltoid and increasing the deltoid moment arm by medializing the center of rotation are biomechanically advantageous. The purpose of this study was to correlate RSA functional outcomes with deltoid lengthening and center of rotation medialization.

Materials And Methods: This prospective cohort study enrolled 49 consecutive patients who underwent RSA for cuff tear arthropathy. Preoperative and serial postoperative physical examinations, radiographs, and American Shoulder and Elbow Surgeons and Simple Shoulder Test scores were evaluated. Deltoid lengthening and medialization of the center of rotation were measured radiographically and correlated with functional outcome scores, range of motion, and complications.

Results: At final follow-up (average, 16 ± 10 months), 37 of 49 patients (76%) were available for analysis. Deltoid lengthening (average, 21 ± 10 mm) correlated significantly (P = .002) with superior active forward elevation (average, 144° ± 19°). Medialization of the center of rotation (average, 18 ± 8 mm) did not correlate with active forward elevation or subjective outcomes. Deltoid lengthening that achieved an acromion-greater tuberosity distance exceeding 38 mm had a 90% positive predictive value of obtaining 135° of active forward elevation. Two patients (4%) required revision surgery, and 68% of patients developed scapular notching (average grade, 1.3 ± 1.2) at final follow-up.

Conclusion: Deltoid lengthening improves active forward elevation after RSA for cuff tear arthropathy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jse.2011.08.049DOI Listing
October 2012

The effect of fixation technique on the stiffness of comminuted Vancouver B1 periprosthetic femur fractures.

J Arthroplasty 2010 Sep 16;25(6 Suppl):124-8. Epub 2010 Jun 16.

Center for Hip and Knee Replacement, New York-Presbyterian Hospital at Columbia University, New York, New York, USA.

The purpose of this study was to evaluate the stiffness of 3 different constructs for the fixation of comminuted Vancouver B1 periprosthetic femoral shaft fractures: a single lateral locking plate, a single lateral locking plate plus an anterior strut allograft, and a lateral locking plate plus an anterior locking plate. The axial stiffness, lateral bending stiffness, and torsional stiffness of 10 synthetic periprosthetic femur fracture models were tested. Differences in stiffness between constructs were determined with a 1-way repeated-measures analysis of variance. Fixation technique was found to have a significant effect for all loading modalities (P < .0001). A lateral locked plate plus an anterior locked plate was significantly stiffer than the allograft that in turn was significantly stiffer than the single plate (P < .0001).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.arth.2010.04.009DOI Listing
September 2010

Effect of hormone replacement and selective estrogen receptor modulators (SERMs) on the biomechanics and biochemistry of pelvic support ligaments in the cynomolgus monkey (Macaca fascicularis).

Am J Obstet Gynecol 2010 May;202(5):485.e1-9

Division of Female Pelvic Medicine and Reconstructive Surgery, Department of Obstetrics and Gynecology, Keck School of Medicine at USC, Los Angeles, CA, USA.

Objective: To evaluate the effect of selective estrogen receptor modulators and ethinyl estradiol on the biomechanical and biochemical properties of the uterosacral and round ligaments in the monkey model of menopause.

Study Design: A randomized, double-blind, placebo-controlled study on 11 female macaque monkeys. Ovariectomized monkeys received 12 weeks of placebo, raloxifene, tamoxifen, or ethinyl estradiol. Biomechanical step-strain testing and real-time polymerase chain reaction was performed on the uterosacral and round ligaments.

Results: Tamoxifen and raloxifene uterosacrals expressed differing collagen I/III receptor density ratios, but both selective estrogen receptor modulators showed decreased tensile stiffness compared to ethinyl estradiol and controls.

Conclusion: These findings support a possible effect of selective estrogen receptor modulators on biomechanical and biochemical properties of uterosacrals. This may play a role in pelvic organ prolapse.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ajog.2010.01.074DOI Listing
May 2010

Interobserver and intraobserver reliability of the Walch classification in primary glenohumeral arthritis.

J Shoulder Elbow Surg 2010 Mar 5;19(2):180-3. Epub 2009 Dec 5.

Center for Shoulder, Elbow and Sports Medicine, Columbia University, New York, NY 10032, USA.

Introduction: In 1999, Walch et al introduced a novel classification scheme for glenoid morphology in patients with primary glenohumeral arthritis and reported substantial intraobserver and interobserver reliability. This classification system has been widely used by shoulder surgeons but a recent independent evaluation revealed considerable lower agreement. The goal of this study was to evaluate the reproducibility of the Walch classification.

Material And Methods: Twenty-three consecutive patients (26 shoulders) undergoing total shoulder arthroplasty (TSA) or evaluated for TSA between March 2007 and November 2007 had shoulder CT scans performed and were included in this study. Three attending shoulder surgeons and 5 shoulder/sports medicine trained fellows independently and blindly evaluated CT scans of 26 consecutive patients with primary glenohumeral arthritis, and classified each patient according to the Walch classification to determine the interobserver reliability. The intraobserver reliability was assessed by comparison of the classification of each patient by the observers on 2 occasions separated by at least 6 weeks.

Results: The overall interobserver agreement for all 8 observers was moderate (k=.508) for all Walch classes. The overall intraobserver reproducibility was substantial (k=.611).

Discussion: We have shown that the interobserver reliability of the Walch classification is moderate while the intraobserver reliability is substantial. This is similar to or superior to the reliability of many commonly used orthopaedic classification systems. While the Walch classification system is not as reliable as initially suggested and improvement of this classification system would be of utility for future clinical studies, we have shown that this is an acceptable classification system and has good clinical and research applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jse.2009.08.003DOI Listing
March 2010

Nuclear factor of activated T cells mediates fluid shear stress- and tensile strain-induced Cox2 in human and murine bone cells.

Bone 2010 Jan 11;46(1):167-75. Epub 2009 Sep 11.

Department of Orthopaedic Surgery, Columbia University Medical Center, 630 W 168th Street, Black Building 14-1412, New York, NY 10032, USA.

Mechanical loading such as interstitial fluid shear stress and tensile strain stimulates bone cells, which respond by changing bone mass and structure to maintain optimal skeletal architecture. Bone cells also adapt to bone implants and altered mechanical loading. Osseous integration between host bone and implants is a prerequisite for the stability of implants. Fluctuating fluid pressure and interfacial strains occur between bone cells and implants due to mechanical loading during walking and other daily activities. In this study, we examined the signaling mechanism by which mechanical stimulation activates a novel transcription factor in human and mouse bone cells. Nuclear factor of activated T cells (NFAT) is one of the transcription factors that act downstream of the Ca(++)/calcineurin (Ca(++)/Cn) network: a well-known pathway of inflammation. In this study, we hypothesized that NFAT2 is activated in response to mechanical stimulation and mediates Cox2 expression. Fluid shear stress and tensile strain results in nuclear translocation of NFAT in cells of the osteoblastic lineage. A peptide inhibitor of the Cn/NFAT axis was found to block the mechanical stimulation-mediated Cox2 induction. Further, chromatin immunoprecipitation assay shows direct interaction between NFAT2 and the human Cox2 promoter region. Additionally, CnAbeta knockout calvarial bone cells were found to be less sensitive than control bone cells to mechanical stimulation. Our study provides new evidence for a novel role for NFAT in bone mechanotransduction in the context of cytokine gene induction in bone cells.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bone.2009.08.061DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2818272PMC
January 2010

Improving bone density at the rotator cuff footprint increases supraspinatus tendon failure stress in a rat model.

J Orthop Res 2010 Mar;28(3):308-14

Center of Shoulder, Elbow, and Sports Medicine, Department of Orthopaedic Surgery, Columbia University Medical Center, 622 West 168th Street, PH 11th Floor, New York, New York 10032, USA.

The purpose of this study was to investigate whether supraspinatus tendon failure stress at the footprint can increase by improving the bone density at the rotator cuff footprint in a rat model. Bilateral ovariectomies were performed in twenty-four 4-month-old Sprague-Dawley rats. Half received bisphosphonate (zoledronic acid) and the other half received no treatment (OVX + ZOM and OVX, respectively). Twelve additional rats did not undergo ovariectomy or receive bisphosphonate treatment (CON). All rats were sacrificed at 7 months of age. Quantitative micro-computed tomography was used to assess bone density in the proximal humerus. A series of stress-relaxation tests were performed to assess stiffness and failure stress of the supraspinatus tendon. Bone density in OVX + ZOM was significantly higher at the rotator cuff footprint when compared to CON and OVX rats (p < 0.0001). The supraspinatus tendons in the OVX group were significantly stiffer when compared to the CON and OVX + ZOM groups (p < 0.05). The failure stress of the OVX + ZOM group was significantly greater than the CON and OVX groups (22.89 +/- 4.43 MPa vs. 18.36 +/- 3.16 and 17.70 +/- 4.92, respectively). In conclusion, improving the bone density at the rotator cuff footprint enhances failure stress of the suprapinatus tendon.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jor.20972DOI Listing
March 2010
-->