Jason E. Hsu

Current review of adhesive capsulitis

Adhesive capsulitis, also known as frozen shoulder, is a common condition involving scapulohumeral pain and loss of motion. This condition was termed ‘‘peri-arthritis scapulohumerale’’ by Duplay in 1896. Codman, in 1934, characterized the diagnosis of ‘‘frozen shoulder’’ as a condition characterized by pain and reduced range of motion in the affected shoulder. Neviaser, in the prearthroscopic era, subsequently used the term ‘‘adhesive capsulitis’’ to describe the findings of chronic inflammation and fibrosis of the joint capsule, although arthroscopic examination would support the term ‘‘fibrotic capsulitis’’ with the absence of adhesions. The current consensus definition of the American Shoulder and Elbow Surgeons is ‘‘a condition of uncertain etiology characterized by significant restriction of both active and passive shoulder motion that occurs in the absence of a known intrinsic shoulder disorder.’’ Despite the large number of patients affected by this condition, our understanding of the condition is limited. In the past, the term ‘‘frozen shoulder’’ has often been used to describe other shoulder conditions such as subacromial bursitis and calcific tendonitis. Neviaser and Neviaser described the term ‘‘frozen shoulder’’ as a ‘‘waste-can diagnosis,’’ because it was often overused and misapplied to patients with a stiff and painful shoulder. Conditions such as calcific tendonitis, bicipital tenosynovitis, glenohumeral and acromioclavicular arthritis, and tears of the rotator cuff can lead to a stiff and painful shoulder, causing apparent limitation of active range of motion, but they lack true

Restoration of Anterior-Posterior Rotator Cuff Force Balance Improves Shoulder Function in a Rat Model of Chronic Massive Tears

The rotator cuff musculature imparts dynamic stability to the glenohumeral joint. In particular, the balance between the subscapularis anteriorly and the infraspinatus posteriorly, often referred to as the rotator cuff “force couple,” is critical for concavity compression and concentric rotation of the humeral head. Restoration of this anterior–posterior force balance after chronic, massive rotator cuff tears may allow for deltoid compensation, but no in vivo studies have quantitatively demonstrated an improvement in shoulder function. Our goal was to determine if restoring this balance of forces improves shoulder function after two‐tendon rotator cuff tears in a rat model. Forty‐eight rats underwent detachment of the supraspinatus and infraspinatus. After four weeks, rats were randomly assigned to three groups: no repair, infraspinatus repair, and two‐tendon repair. Quantitative ambulatory measures including medial/lateral forces, braking, propulsion, and step width were significantly different between the infraspinatus and no repair group and similar between the infraspinatus and two‐tendon repair groups at almost all time points. These results suggest that repairing the infraspinatus back to its insertion site without repair of the supraspinatus can improve shoulder function to a level similar to repairing both the infraspinatus and supraspinatus tendons. Clinically, a partial repair of the posterior cuff after a two‐tendon tear may be sufficient to restore adequate function. An in vivo model system for two‐tendon repair of massive rotator cuff tears is presented.

The Disabilities of the Arm, Shoulder, and Hand questionnaire in intercollegiate athletes: validity limited by ceiling effect.

HYPOTHESIS The Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire has been validated as an effective upper extremity specific outcome measure. Normative scores have not been established for young athletes. This study was conducted to establish normative DASH scores for intercollegiate athletes. We hypothesized that DASH scores in intercollegiate athletes differ from published values obtained from the general population. MATERIALS AND METHODS The DASH questionnaire was administered to 321 athletes cleared for full participation in intercollegiate sports. Their scores were compared with normative values in the general population and 2 other age-matched cohorts. RESULTS Intercollegiate athletes had significantly better upper extremity function compared with the general population (1.37 +/- 2.96 vs 10.10 +/- 14.68, P < .001) and an age-matched cohort of employed adults (1.37 +/- 2.96 vs 5.40 +/- 7.57, P < .0001). The DASH was 0 for 65.1%. Within this cohort, men reported better upper extremity function than women (0.98 vs 1.82, P = .010). Athletes participating in overhead sports reported worse upper extremity function than nonoverhead athletes (1.81 vs 0.98, P = .042). DISCUSSION We report normative DASH values for a group of intercollegiate athletes and show a significant difference between the scores of these athletes and the general population. Within our cohort of competitive athletes, overhead sports and female gender are associated with significantly lower DASH scores and sports module scores. The utility of using these results are limited by a substantial ceiling effect in this population of competitive athletes. Differences within our cohort and differences between our cohort and other populations are minimized by this ceiling effect. Various upper extremity outcome measures may be similarly limited by a ceiling effect and should be examined for appropriateness before use. CONCLUSION Intercollegiate athletes report significantly greater upper extremity function than the general population; however, validity of the DASH in these athletes is limited and population differences may be minimized by a substantial ceiling effect.

Addressing glenoid bone deficiency and asymmetric posterior erosion in shoulder arthroplasty

Glenoid bone deficiency and eccentric posterior wear are difficult problems faced by shoulder arthroplasty surgeons. Numerous options and techniques exist for addressing these issues. Hemiarthroplasty with concentric glenoid reaming may be a viable alternative in motivated patients in whom glenoid component failure is a concern. Total shoulder arthroplasty has been shown to provide durable pain relief and excellent function in patients, and numerous methods and techniques can assist in addressing bone loss and eccentric wear. However, the ideal amount of version correction in cases of severe retroversion has not yet been established. Asymmetric reaming is a commonly used technique to address glenoid version, but correction of severe retroversion may compromise bone stock and component fixation. Bone grafting is a technically demanding alternative for uncontained defects and has mixed clinical results. Specialized glenoid implants with posterior augmentation have been created to assist the surgeon in correcting glenoid version without compromising bone stock, but clinical data on these implants are still pending. Custom implants or instruments based on each patients unique glenoid anatomy may hold promise. In elderly, sedentary patients in whom bone stock and soft-tissue balance are concerns, reverse total shoulder arthroplasty may be less technically demanding while still providing satisfactory pain relief and functional improvements.

Hypercholesterolemia increases supraspinatus tendon stiffness and elastic modulus across multiple species.

BACKGROUND More than one-quarter of Americans have hypercholesterolemia and/or are being treated with cholesterol-lowering medications. Given the systemic nature of hypercholesterolemia and remaining questions regarding its effect on tendons at a local level, we sought to assess the utility of small versus large animal model systems for translational studies by exploring the effect of hypercholesterolemia on supraspinatus tendon elastic mechanical properties in mice, rats, and monkeys. We hypothesized that stiffness and elastic modulus would be increased in tendons across species due to hypercholesterolemia. MATERIALS AND METHODS Supraspinatus tendons from normal (control) and high-cholesterol (HC) mice, rats, and monkeys were used in this study. After dissection, tendons were geometrically measured and tensile tested with tissue strain measured optically. RESULTS Overall, HC animals had significantly altered plasma lipid profiles. Biomechanical testing showed a significant increase in stiffness compared with control in HC mice and rats, as well as a nonsignificant trend for HC monkeys. Elastic modulus was also significantly increased in HC mice and monkeys, with HC rats showing a trend. CONCLUSIONS The consistency of our findings across species and between small and large animals, combined with the fact that the aged mice were exposed to lifelong hypercholesterolemia (compared with rats and nonhuman primates, which were fed HC diets), suggests that these increased properties may be inherent to the effect of hypercholesterolemia on supraspinatus tendon rather than due to an effect of cumulative exposure time to the effects of HC. Further investigation is needed to confirm this concept.

Development and evaluation of multiple tendon injury models in the mouse

The mouse has proven to be an advantageous animal model system in basic science research focused on aiding in development and evaluation of potential treatments; however, the small size of mouse tendons makes consistent and reproducible injury models and subsequent biomechanical evaluation challenging for studying tendon healing. In this study, we investigated the feasibility and reproducibility of multiple mouse tendon injury models. Our hypothesis was that incisional (using a blade) and excisional (using a biopsy punch) injuries would result in consistent differences in tendon material properties. At 16 weeks of age, 17 C57BL/6 mice underwent surgery to create defects in the flexor digitorum longus, Achilles, or patellar tendon. Each animal received 1-2 full-thickness, central-width incisional or excisional injuries per limb; at least one tendon per limb remained uninjured. The injuries were distributed such that each tendon type had comparable numbers of uninjured, incisionally injured, and excisionally injured specimens. Three weeks after injury, all animals were euthanized and tendons were harvested for mechanical testing. As hypothesized, differences were detected for all three different tendon types at three weeks post-injury. While all models created injuries that produced predictable outcomes, the patellar tendon model was the most consistent in terms of number and size of significant differences in injured tendons compared to native properties, as well as in the overall variance in the data. This finding provides support for its use in fundamental tendon healing studies; however, future work may use any of these models, based on their appropriateness for the specific question under study.

Propionibacterium acnes infection in shoulder arthroscopy patients with postoperative pain

BACKGROUND Recent studies have identified Propionibacterium acnes as the causal organism in an increasing number of postoperative shoulder infections. Most reports have found a high rate of P acnes infection after open surgery, particularly shoulder arthroplasty. However, there are limited data regarding P acnes infections after shoulder arthroscopy. MATERIALS AND METHODS We prospectively collected data on all shoulder arthroscopies performed by the senior author from January 1, 2009, until April 1, 2013. Cultures were taken in all revision shoulder arthroscopy cases performed for pain, stiffness, or weakness. In addition, 2 cultures were taken from each of a cohort of 32 primary shoulder arthroscopy cases without concern for infection to determine the false-positive rate. RESULTS A total of 1,591 shoulder arthroscopies were performed during this period, 68 (4.3%) of which were revision procedures performed for pain, stiffness, or weakness. A total of 20 revision arthroscopies (29.4%) had positive culture findings, and 16 (23.5%) were positive for P acnes. In the control group, 1 patient (3.2%) had P acnes growth. CONCLUSIONS The rate of P acnes infection in patients undergoing revision shoulder arthroscopy is higher than previously published and should be considered in cases characterized by refractory postoperative pain and stiffness.

Treatment of femur fractures in school-aged children using elastic stable intramedullary nailing: a systematic review.

Femur fractures are common long-bone injuries in school-aged children (6–12 years). Among the various acceptable treatment options, elastic stable intramedullary nailing (ESIN) has gained popularity over recent years although the level of evidence for ESIN is low. This study was a systematic review of the literature to examine the outcomes and complications of ESIN in school-aged children and to critically evaluate the quality of the available literature. Although most complications were minor, some series report complication rates of more than 50%. Union rates are high. Malunion or mechanical axis malalignment, on the other hand, is common, and leg length discrepancy and overgrowth are also not unusual. Symptomatic implants are common, particularly if the distal ends of the nail are left long and prominent. Refracture was noted to be uncommon in this population. ESIN is a well-accepted and reliable option for treatment of femur fractures in school-aged children. Advantages are decreased length of hospital stay, early return to function, and high union rates. Care must be taken to obtain and maintain reduction, and caution is advised in older and heavier children.

Propionibacterium acnes infections in shoulder surgery.

Perioperative shoulder infections involving Propionibacterium acnes can be difficult to identify in a patient who presents with little more than pain and stiffness in the postoperative period. Although indolent in its growth and presentation, infection of the shoulder with P acnes can have devastating effects, including failure of the surgical intervention. This article reviews the importance of a comprehensive physical, radiologic, and laboratory evaluation, and discusses appropriate preventive and treatment strategies for P acnes infections of the shoulder.

Patterns of tear progression for asymptomatic degenerative rotator cuff tears

BACKGROUND The purpose of this study was to examine patterns of rotator cuff tear size progression in degenerative rotator cuff tears and to compare tear progression risks for tears with and without anterior supraspinatus tendon disruption. METHODS Asymptomatic full-thickness rotator cuff tears with minimum 2-year follow-up were examined with annual shoulder ultrasound examinations. Integrity of the anterior 3 mm of the supraspinatus tendon determined classification of cable-intact vs. cable-disrupted tears. Tear enlargement was defined as an increase of 5 mm or more in width. Tear propagation direction was calculated from measured changes in tear width in reference to the biceps tendon on serial ultrasound examinations. RESULTS The cohort included 139 full-thickness tears with a mean subject age of 63.3 years and follow-up duration of 6.0 years. Ninety-six (69.1%) of the tears were considered cable intact. Cable-disrupted tears were larger at baseline (median, 19.0 mm vs. 10.0 mm; P < .0001) than cable-intact tears. There was no difference in the risk of enlargement (52.1% vs. 67.4%; P = .09) or time to enlargement (3.2 vs. 2.2 years; P = .37) for cable-intact compared with cable-disrupted tears. There was no difference in the magnitude of enlargement for cable-intact and cable-disrupted tears (median, 7.0 mm vs.9.0 mm; P = .18). Cable-intact tears propagated a median of 5 mm anteriorly and 4 mm posteriorly, whereas cable-disrupted tears propagated posteriorly. CONCLUSIONS The majority of degenerative rotator cuff tears spare the anterior supraspinatus tendon. Although tears classified as cable disrupted are larger at baseline than cable-intact tears, tear enlargement risks are similar for each tear type.