H Mike Kim

Columbia University, New York, New York, United States

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Publications (31)94.9 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: After carpal tunnel syndrome, cubital tunnel syndrome is the second most common compression neuropathy in the upper extremity. Various sites of ulnar nerve compression at the elbow exist, with the most common being between the 2 heads of the flexor carpi ulnaris. Other potential sites include the arcade of Struthers, the space between Osborne's ligament and the medial ulnar collateral ligament, the medial epicondyle, the medial head of the triceps, and the medial intermuscular septum. The anconeus epitrochlearis, an anomalous muscle that runs between the medial aspect of the olecranon and the medial epicondyle, is found in up to 28% of cadavers. Although it is far less common, it must be considered when evaluating a patient with cubital tunnel syndrome. The authors report a 19-year-old man with a 2-month history of atraumatic left elbow pain accompanied by distal motor and sensory symptoms that significantly affected his activities of daily living and quality of life. After a short course of conservative management, surgical excision of the anomalous muscle, along with decompression of the ulnar nerve, was performed because of progression of symptoms. The patient had immediate improvement in subjective symptoms and strength on removal of the anconeus epitrochlearis. As shown in this case report, recovery of both motor and sensory nerve function can be achieved if the source of compression is an anomalous muscle and is treated with early surgical removal.
    Orthopedics 08/2014; 37(8):e743-e745. DOI:10.3928/01477447-20140728-92 · 0.98 Impact Factor
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    ABSTRACT: Muscle forces are necessary for the development and maintenance of a mineralized skeleton. Removal of loads leads to malformed bones and impaired musculoskeletal function due to changes in bone (re)modeling. In the current study, the development of a mineralized junction at the interface between muscle and bone was examined under normal and impaired loading conditions. Unilateral mouse rotator cuff muscles were paralyzed using botulinum toxin A at birth. Control groups consisted of contralateral shoulders injected with saline and a separate group of normal mice. It was hypothesized that muscle unloading would suppress bone formation and enhance bone resorption at the enthesis, and that the unloading-induced bony defects could be rescued by suppressing osteoclast activity. In order to modulate osteoclast activity, mice were injected with the bisphosphonate alendronate. Bone formation was measured at the tendon enthesis using alizarin and calcein fluorescent labeling of bone surfaces followed by quantitative histomorphometry of histologic sections. Bone volume and architecture was measured using micro computed tomography. Osteoclast surface was determined via quantitative histomorphometry of tartrate resistant acid phosphatase stained histologic sections. Muscle unloading resulted in delayed initiation of endochondral ossification at the enthesis, but did not impair bone formation rate. Unloading led to severe defects in bone volume and trabecular bone architecture. These defects were partially rescued by suppression of osteoclast activity through alendronate treatment, and the effect of alendronate was dose dependent. Similarly, bone formation rate was increased with increasing alendronate dose across loading groups. The bony defects caused by unloading were therefore likely due to maintained high osteoclast activity, which normally decreases from neonatal through mature timepoints. These results have important implications for the treatment of muscle unloading conditions such as neonatal brachial plexus palsy, which results in shoulder paralysis at birth and subsequent defects in the rotator cuff enthesis and humeral head.
    PLoS ONE 05/2014; 9(5):e97375. DOI:10.1371/journal.pone.0097375 · 3.23 Impact Factor
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    ABSTRACT: It is widely accepted that most patients treated with rotator cuff repair do well regardless of the integrity of the repair. The purpose of this cross-sectional study was to reexamine this concept and identify the factors affecting the outcomes of patients with a recurrent tear. A cohort of patients who had been treated with rotator cuff repair completed a survey regarding satisfaction with the operatively treated shoulder, physical activity, and shoulder function. Ultrasonography was performed to determine rotator cuff integrity. Patients were divided into three age categories: younger than fifty-five years, fifty-five to sixty-five years, and sixty-six years or older. The relationships of the outcomes to patient age, repair integrity, and other demographic factors were analyzed. Forty-seven (26%) of the 180 enrolled patients had a retear, defined as a full-thickness defect. In each age category, the satisfaction, ASES (American Shoulder and Elbow Surgeons), and SST (Simple Shoulder Test) scores in the retear group were significantly poorer than those in the no-retear group (p < 0.05). Within the retear group, all three scores were significantly better in the oldest age category (p < 0.05); there were no significant differences among the age categories within the no-retear group (p > 0.05). Simple regression analysis showed that younger age, a Workers' Compensation claim, and lower education level were significant predictors of poorer scores in patients with a retear (p < 0.05). Multiple regression analysis of the retear group showed that (1) lower education level and a Workers' Compensation claim were independent predictors of a poorer satisfaction score; (2) lower education level, younger age, and a Workers' Compensation claim were independent predictors of a poorer ASES score; and (3) lower education level was the only independent predictor of a poorer SST score (p < 0.01 for all). The presence of a retear negatively affected the clinical outcomes following rotator cuff repair. This finding refutes the widely held concept that patients typically do well regardless of the repair integrity following rotator cuff repair. In patients with a retear, nonanatomic factors including younger age, lower education level, and a Workers' Compensation claim were associated with poorer outcomes. Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence. PEER REVIEW This article was reviewed by the Editor-in-Chief and one Deputy Editor, and it underwent blinded review by two or more outside experts. It was also reviewed by an expert in methodology and statistics. The Deputy Editor reviewed each revision of the article, and it underwent a final review by the Editor-in-Chief prior to publication. Final corrections and clarifications occurred during one or more exchanges between the author(s) and copyeditors.
    The Journal of Bone and Joint Surgery 01/2014; 96(2):106-12. DOI:10.2106/JBJS.L.01649 · 4.31 Impact Factor
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    ABSTRACT: Elbow arthroscopic surgery can now effectively treat a variety of conditions that affect athletes. Advances in instrumentation, increased surgeon familiarity, and expanded indications have led to significant growth in elbow arthroscopic surgery in the past few decades. While positioning, portal placement, and specific instruments may vary among surgeons, anatomic considerations guide surgical approaches to minimize neurovascular compromise. Arthroscopic procedures vary in difficulty, and surgeons should follow stepwise advancement with experience. Removal of loose bodies, debridement of synovial plicae, and debridement of the extensor carpi radialis brevis for lateral epicondylitis are considered simple procedures for novice elbow arthroscopic surgeons. More advanced procedures include management of osteochondritis dissecans, valgus extension overload in the throwing athlete, and capsular release. With proper technique, a variety of athletic elbow conditions can be treated arthroscopically with predictable results and minimal morbidity.
    The American Journal of Sports Medicine 04/2013; 41(9). DOI:10.1177/0363546513482106 · 4.70 Impact Factor
  • Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.] 01/2013; 22(3). DOI:10.1016/j.jse.2012.11.012 · 2.37 Impact Factor
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    ABSTRACT: 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.
    Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.] 01/2013; 22(7). DOI:10.1016/j.jse.2012.09.007 · 2.37 Impact Factor
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    ABSTRACT: 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.
    Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.] 12/2012; 22(3). DOI:10.1016/j.jse.2012.08.025 · 2.37 Impact Factor
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    ABSTRACT: Tendon-to-bone healing is typically poor, with a high rate of repair-site rupture. Bone loss after tendon-to-bone repair may contribute to poor outcomes. Therefore, we hypothesized that the local application of the osteogenic growth factor bone morphogenetic protein 2 (BMP-2) would promote bone formation, leading to improved repair-site mechanical properties. Intrasynovial canine flexor tendons were injured in Zone 1 and repaired into bone tunnels in the distal phalanx. BMP-2 was delivered to the repair site using either a calcium phosphate matrix (CPM) or a collagen sponge (COL) carrier. Each animal also received carrier alone in an adjacent repair to serve as an internal control. Repairs were evaluated at 21 days using biomechanical, radiographic, and histologic assays. Although an increase in osteoid formation was noted histologically, no significant increases in bone mineral density occurred. When excluding functional failures (i.e., ruptured and gapped repairs), mechanical properties were not different when comparing BMP-2/CPM groups with carrier controls. A significantly higher percentage of BMP-2 treated specimens had a maximum force <20 N compared to carrier controls. While tendon-to-bone healing can be enhanced by addressing the bone loss that typically occurs after surgical repair, the delivery of BMP-2 using the concentrations and methods of the current study did not improve mechanical properties over carrier alone. The anticipated anabolic effect of BMP-2 was insufficient in the short time frame of this study to counter the post-repair loss of bone. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1702-1709, 2012.
    Journal of Orthopaedic Research 11/2012; 30(11):1702-9. DOI:10.1002/jor.22151 · 2.97 Impact Factor
  • The American Journal of Sports Medicine 08/2012; 40(9):2149-53. DOI:10.1177/0363546512454659 · 4.70 Impact Factor
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    ABSTRACT: Diagnostic evaluation of rotator cuff muscle quality is important to determine indications for potential operative repair. Ultrasonography has developed into an accepted and useful tool for evaluating rotator cuff tendon tears; however, its use for evaluating rotator muscle quality has not been well established. The purpose of this study was to investigate the diagnostic performance and observer reliability of ultrasonography in grading fatty degeneration of the posterior and superior rotator cuff muscles. The supraspinatus, infraspinatus, and teres minor muscles were prospectively evaluated with magnetic resonance imaging (MRI) and ultrasonography in eighty patients with shoulder pain. The degree of fatty degeneration on MRI was graded by four independent raters on the basis of the modified Goutallier grading system. Ultrasonographic evaluation of fatty degeneration was performed by one of three radiologists with use of a three-point scale. The two scoring systems were compared to determine the diagnostic performance of ultrasonography. The interobserver and intraobserver reliability of MRI grading by the four raters were determined. The interobserver reliability of ultrasonography among the three radiologists was determined in a separate group of thirty study subjects. The weighted Cohen kappa, percentage agreement, sensitivity, and specificity were calculated. The accuracy of ultrasonography for the detection of fatty degeneration, as assessed on the basis of the percentage agreement with MRI, was 92.5% for the supraspinatus and infraspinatus muscles and 87.5% for the teres minor. The sensitivity was 84.6% for the supraspinatus, 95.6% for the infraspinatus, and 87.5% for the teres minor. The specificity was 96.3% for the supraspinatus, 91.2% for the infraspinatus, and 87.5% for the teres minor. The agreement between MRI and ultrasonography was substantial for the supraspinatus and infraspinatus (kappa = 0.78 and 0.71, respectively) and moderate for the teres minor (kappa = 0.47). The interobserver reliability for MRI was substantial for the supraspinatus and infraspinatus (kappa = 0.76 and 0.77, respectively) and moderate for the teres minor (kappa = 0.59). For ultrasonography, the interobserver reliability was substantial for all three muscles (kappa = 0.71 for the supraspinatus, 0.65 for the infraspinatus, and 0.72 for the teres minor). The diagnostic performance of ultrasonography in identifying and grading fatty degeneration of the rotator cuff muscles was comparable with that of MRI. Ultrasonography can be used as the primary diagnostic imaging modality for fatty changes in rotator cuff muscles.
    The Journal of Bone and Joint Surgery 06/2012; 94(12):e83. DOI:10.2106/JBJS.J.01899 · 4.31 Impact Factor
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    ABSTRACT: BACKGROUND: The purpose of this study was to describe the complex anatomy surrounding the teres minor muscle. METHODS: Thirty-one cadaveric human shoulders were dissected. Qualitative fascial and neurovascular anatomy were described. Location of motor nerves to teres minor were measured in reference to local anatomy. RESULTS: Fascial anatomy of the posterior shoulder had 2 distinct and equally common variants, 1 of which demonstrated a stout, inflexible fascial compartment enveloping the teres minor muscle. The other had a continuous fascia enveloping both the infraspinatus and teres minor muscles. In both variants, the primary nerve to teres minor traveled around a fascial sling, becoming sub-fascial at an average of 44 mm (range, 25-68) medial to the teres minor's insertion. The nerve took its most angulated course as it entered the fascial sling. Smaller accessory innervation of teres minor began, on average, 30 mm (range, 15-48) medial to the muscle's lateral insertion. None of the accessory motor nerves coursed deep to the fascial sling nor to the distinct teres minor fascial compartment. CONCLUSION: A stout fascial sling may be the potential site of greatest compression and tethering of the primary motor nerve to teres minor. Additional lateral accessory motor nerves to teres minor remained extra-fascial and took a less angulated path. Half of the shoulders demonstrated a separate teres minor fascial compartment. An improved understanding of the fascial anatomy and innervation pattern of the teres minor muscle may help clinicians who treat patients with symptomatic isolated teres minor muscle atrophy.
    Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.] 04/2012; 22(1). DOI:10.1016/j.jse.2011.12.005 · 2.37 Impact Factor
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    ABSTRACT: Shoulder pain is the third most frequent musculoskeletal complaint presented to physicians. Often considered a benign entity by patients and even their physicians, shoulder disorders can have a devastating effect on a patient's ability to function, as well as serve as an indicator of poor general health. For these reasons, it is important for the physician to be able to identify the etiology of a patient's shoulder problem(s). However, making a correct diagnosis is often difficult because there can be many causes for a patient's shoulder pain, weakness, or loss of function. Moreover, the shoulder girdle is an intricate group of structures that work together to allow for the largest range of motion in the body. This complexity makes it difficult to diagnose a patient's condition(s) based on history alone. A thorough and well-performed physical examination is the key to making a correct diagnosis and helping to distinguish different etiologies of shoulder dysfunction. In this article, we review relevant shoulder anatomy and biomechanics, and general shoulder examinations with special tests for various shoulder pathologies. We provide an effective and methodical approach to the physical examination of the shoulder.
    The Physician and sportsmedicine 02/2012; 40(1):91-101. DOI:10.3810/psm.2012.02.1955 · 1.49 Impact Factor
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    ABSTRACT: Irreversible muscle changes after rotator cuff tears is a well-known negative prognostic factor after shoulder surgery. Currently, little is known about the pathomechanism of fatty degeneration of the rotator cuff muscles after chronic cuff tears. The purposes of this study were to (1) develop a rodent animal model of chronic rotator cuff tears that can reproduce fatty degeneration of the cuff muscles seen clinically, (2) describe the effects of tear size and concomitant nerve injury on muscle degeneration, and (3) evaluate the changes in gene expression of relevant myogenic and adipogenic factors after rotator cuff tears using the animal model. Rotator cuff tears were created in rodents with and without transection of the suprascapular nerve. The supraspinatus and infraspinatus muscles were examined at 2, 8, and 16 weeks after injury for histologic evidence of fatty degeneration and expression of myogenic and adipogenic genes. Histologic analysis revealed adipocytes, intramuscular fat globules, and intramyocellular fat droplets in the tenotomized and neurotomized supraspinatus and infraspinatus muscles. Changes increased with time and were most severe in the muscles with combined tenotomy and neurotomy. Adipogenic and myogenic transcription factors and markers were upregulated in muscles treated with tenotomy or tenotomy combined with neurotomy compared with normal muscles. The rodent animal model described in this study produces fatty degeneration of the rotator cuff muscles similar to human muscles after chronic cuff tears. The severity of changes was associated with tear size and concomitant nerve injury.
    Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.] 08/2011; 21(7):847-58. DOI:10.1016/j.jse.2011.05.004 · 2.37 Impact Factor
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    ABSTRACT: Despite advances in surgical technique, rotator cuff repairs are plagued by a high rate of failure. This failure rate is in part due to poor tendon-to-bone healing; rather than regeneration of a fibrocartilaginous attachment, the repair is filled with disorganized fibrovascular (scar) tissue. Transforming growth factor beta 3 (TGF-β3) has been implicated in fetal development and scarless fetal healing and, thus, exogenous addition of TGF-β3 may enhance tendon-to-bone healing. We hypothesized that: TGF-β3 could be released in a controlled manner using a heparin/fibrin-based delivery system (HBDS); and delivery of TGF-β3 at the healing tendon-to-bone insertion would lead to improvements in biomechanical properties compared to untreated controls. After demonstrating that the release kinetics of TGF-β3 could be controlled using a HBDS in vitro, matrices were incorporated at the repaired supraspinatus tendon-to-bone insertions of rats. Animals were sacrificed at 14-56 days. Repaired insertions were assessed using histology (for inflammation, vascularity, and cell proliferation) and biomechanics (for structural and mechanical properties). TGF-β3 treatment in vivo accelerated the healing process, with increases in inflammation, cellularity, vascularity, and cell proliferation at the early timepoints. Moreover, sustained delivery of TGF-β3 to the healing tendon-to-bone insertion led to significant improvements in structural properties at 28 days and in material properties at 56 days compared to controls. We concluded that TGF-β3 delivered at a sustained rate using a HBDS enhanced tendon-to-bone healing in a rat model.
    Journal of Orthopaedic Research 07/2011; 29(7):1099-105. DOI:10.1002/jor.21301 · 2.97 Impact Factor
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    ABSTRACT: The purpose of this study was to examine the role of two of the three transforming growth factor beta (TGF-β) isoforms at the healing tendon-to-bone insertion. The supraspinatus tendons of 64 rats were transected at their bony insertions and repaired to the humeral head. One shoulder of each rat received an osmotic pump for sustained delivery of the following factors at the repair site: (1) TGF-β1 and neutralizing antibodies to TGF-β2 and 3 (TGF-β1 group), (2) TGF-β3 and neutralizing antibodies to TGF-β1 and 2 (TGF-β3 group), (3) neutralizing antibodies to TGF-β1, 2, and 3 (anti-TGF-β group), and (4) saline (saline group). The contralateral shoulders received saline to serve as paired controls. The repairs were evaluated at multiple time points postmortem using histology-based assays and biomechanical testing. Treated shoulders in the TGF-β1 group showed increased type III collagen production compared to the paired control shoulders, indicative of a scar-mediated response. There was a trend toward reduced mechanical properties in the TGF-β1 group, but these changes did not reach statistical significance. The anti-TGF-β group showed no difference in tissue volume, but significantly inferior mechanical properties, compared to the paired control shoulders. The TGF-β3 group did not show any differences compared to the paired control shoulders. Although TGF-β isoforms play important roles in tendon-to-bone development and healing, application of exogenous TGF-β isoforms and neutralizing antibodies to the subacromial space using osmotic pumps did not improve supraspinatus tendon-to-bone healing.
    Connective tissue research 04/2011; 52(2):87-98. DOI:10.3109/03008207.2010.483026 · 1.98 Impact Factor
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    ABSTRACT: The mechanical environment plays an important role in musculoskeletal tissue development. The present study characterized changes in supraspinatus muscle due to removal of mechanical cues during postnatal development. An intramuscular injection of botulinum toxin type A (BTX) was used to induce and maintain paralysis in the left shoulders of mice since birth while the right shoulders received saline and served as contralateral controls. A separate group of animals was allowed to develop normally without any injections. Muscles were examined postnatally at various time points. The maximum isometric tetanic force generated by the muscle was significantly reduced in the BTX group compared to saline and normal groups. The paralyzed muscles were smaller and showed significant muscle atrophy and fat accumulation on histologic evaluation. Myogenic genes myogenin, myoD1, myf5, myf6, and fast type II myosin heavy chain (MHC) isoform were significantly upregulated while slow type I MHC isoform was significantly downregulated in the BTX group. Adipogenic genes C/EBPα, PPARγ2, leptin, and lipoprotein lipase were significantly upregulated in the BTX group. Results indicate that reduced muscle loading secondary to BTX-induced paralysis leads to fat accumulation and muscle degeneration in the developing muscle. Understanding the molecular and compositional changes in developing supraspinatus muscles may be useful for identifying and addressing the pathological changes that occur in shoulder injuries such as neonatal brachial plexus palsy.
    Journal of Orthopaedic Research 02/2011; 29(2):281-8. DOI:10.1002/jor.21234 · 2.97 Impact Factor
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    ABSTRACT: The purposes of this study were to identify changes in tear dimensions, shoulder function, and glenohumeral kinematics when an asymptomatic rotator cuff tear becomes painful and to identify characteristics of individuals who develop pain compared with those who remain asymptomatic. A cohort of 195 subjects with an asymptomatic rotator cuff tear was prospectively monitored for pain development and examined annually for changes in various parameters such as tear size, fatty degeneration of the rotator cuff muscle, glenohumeral kinematics, and shoulder function. Forty-four subjects were found to have developed new pain, and the parameters before and after pain development were compared. The forty-four subjects were then compared with a group of fifty-five subjects who remained asymptomatic over a two-year period. With pain development, the size of a full-thickness rotator cuff tear increased significantly, with 18% of the full-thickness tears showing an increase of >5 mm, and 40% of the partial-thickness tears had progressed to a full-thickness tear. In comparison with the assessments made before the onset of pain, the American Shoulder and Elbow Surgeons scores for shoulder function were significantly decreased and all measures of shoulder range of motion were decreased except for external rotation at 90° of abduction. There was an increase in compensatory scapulothoracic motion in relation to the glenohumeral motion during early shoulder abduction with pain development. No significant changes were found in external rotation strength or muscular fatty degeneration. Compared with the subjects who remained asymptomatic, the subjects who developed pain were found to have significantly larger tears at the time of initial enrollment. Pain development in shoulders with an asymptomatic rotator cuff tear is associated with an increase in tear size. Larger tears are more likely to develop pain in the short term than are smaller tears. Further research is warranted to investigate the role of prophylactic treatment of asymptomatic shoulders to avoid the development of pain and loss of shoulder function.
    The Journal of Bone and Joint Surgery 11/2010; 92(16):2623-33. DOI:10.2106/JBJS.I.00506 · 4.31 Impact Factor
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    ABSTRACT: The developmental course of musculoskeletal deformities in neonatal brachial plexus palsy (NBPP) has not been studied extensively. The goals of this study were to: (1) evaluate a new animal model of NBPP, (2) characterize the development of musculoskeletal abnormalities in paralyzed shoulders, and (3) investigate the expression of myogenic and adipogenic genes in paralyzed rotator cuff muscles. Neonatal mice were divided into neurotomy and sham groups. The neurotomy group underwent surgical transection of the superior trunk of the brachial plexus within 24 h of birth. The sham group underwent the same surgical exposure, but the brachial plexus was left intact. Musculoskeletal deformities were evaluated with radiological and histological assays at 2, 4, 8, 12, and 30 weeks after birth. The supraspinatus muscles of a separate group of mice were used to examine expression of myogenic and adipogenic genes at 8 weeks. The neurotomized forelimbs developed deformities similar to those seen in human NBPP. The deformities progressed with age. The denervated supraspinatus muscles showed intramuscular fat accumulation and upregulation of both myogenic and adipogenic genes compared to the normal. The current study presents a useful animal model for future research examining musculoskeletal changes secondary to neonatal nerve injury.
    Journal of Orthopaedic Research 10/2010; 28(10):1391-8. DOI:10.1002/jor.21128 · 2.97 Impact Factor
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    ABSTRACT: Studies have demonstrated that flexor tendon repair strength fails to increase in the first three weeks following suturing of the tendon, a finding that correlates closely with the timing of many clinical failures. The application of growth factors holds promise for improving the tendon-repair response and obviating failure in the initial three weeks. The effects of basic fibroblast growth factor on flexor tendon healing were evaluated with use of a canine model. Operative repair followed by the sustained delivery of basic fibroblast growth factor, at two different doses, was compared with operative repair alone. Histological, biochemical, and biomechanical methods were used to evaluate the tendons twenty-one days after repair. Vascularity, cellularity, and adhesion formation were increased in the tendons that received basic fibroblast growth factor as compared with the tendons that received operative repair alone. DNA concentration was increased in the tendons that received 1000 ng of basic fibroblast growth factor (mean and standard deviation, 5.7 ± 0.7 μg/mg) as compared with the tendons that received 500 ng of basic fibroblast growth factor (3.8 ± 0.7 μg/mg) and the matched control tendons that received operative repair alone (4.5 ± 0.9 μg/mg). Tendons that were treated with basic fibroblast growth factor had a lower ratio of type-I collagen to type-III collagen, indicating increased scar formation compared with that seen in tendons that received operative repair alone (3.0 ± 1.6 in the group that received 500-ng basic fibroblast growth factor compared with 4.3 ± 1.0 in the paired control group that received operative repair alone, and 3.4 ± 0.6 in the group that received 1000-ng basic fibroblast growth factor compared with 4.5 ± 1.9 in the paired control group that received operative repair alone). Consistent with the increases in adhesion formation that were seen in tendons treated with basic fibroblast growth factor, the range of motion was reduced in the group that received the higher dose of basic fibroblast growth factor than it was in the paired control group that received operative repair alone (16.6° ± 9.4° in the group that received 500 ng basic fibroblast growth factor, 13.4° ± 6.1° in the paired control group that received operative repair alone, and 29.2° ± 5.8° in the normal group [i.e., the group of corresponding, uninjured tendons from the contralateral forelimb]; and 15.0° ± 3.8° in the group that received 1000 ng basic fibroblast growth factor, 19.3° ± 5.5° in the paired control group that received operative repair alone, and 29.0° ± 8.8° in the normal group). There were no significant differences in tendon excursion or tensile mechanical properties between the groups that were treated with basic fibroblast growth factor and the groups that received operative repair alone. Although basic fibroblast growth factor accelerated the cell-proliferation phase of tendon healing, it also promoted neovascularization and inflammation in the earliest stages following the suturing of the tendon. Despite a substantial biologic response, the administration of basic fibroblast growth factor failed to produce improvements in either the mechanical or functional properties of the repair. Rather, increased cellular activity resulted in peritendinous scar formation and diminished range of motion.
    The Journal of Bone and Joint Surgery 10/2010; 92(13):2285-93. DOI:10.2106/JBJS.I.01601 · 4.31 Impact Factor
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    ABSTRACT: Clinical outcomes after intrasynovial flexor tendon repair have been substantially improved over the past 2 decades through advances in tendon suture techniques and postoperative rehabilitation methods. Nevertheless, complications such as repair site elongation (i.e., gap formation) and rupture continue to occur frequently. Experimental studies have shown that repair site strength fails to increase in the first 3 weeks after tendon suture. After 3 weeks, the strength and rigidity of the repair site improve significantly, a process that continues for several months. Formation of a repair site gap during the early rehabilitation period has been shown to considerably delay the accrual of repair site strength over time. Thus, it is of prime importance that the method of tendon suture achieves and maintains a stiff and strong repair site during the early healing interval by maintaining close approximation of the tendon stumps and by stimulating, where possible, the intrinsic repair response. In this review, we describe recent efforts to enhance the integrity of the immature repair site. We focus on 2 major areas of advancement: surgical technique modifications and manipulation of the biologic and biochemical environment.
    The Journal of hand surgery 06/2010; 35(6):1031-7; quiz 1038. DOI:10.1016/j.jhsa.2009.12.044 · 1.66 Impact Factor

Publication Stats

587 Citations
94.90 Total Impact Points

Institutions

  • 2012–2014
    • Columbia University
      • Department of Orthopaedic Surgery
      New York, New York, United States
  • 2009–2014
    • Washington University in St. Louis
      • Department of Orthopaedic Surgery
      San Luis, Missouri, United States
  • 2009–2012
    • Barnes Jewish Hospital
      San Luis, Missouri, United States