Impaired contractile function of the supraspinatus in the acute period following a rotator cuff tear

Background: Rotator cuff (RTC) tears are a common clinical problem resulting in adverse changes to the muscle, but there is limited information comparing histopathology to contractile function. This study assessed supraspinatus force and susceptibility to injury in the rat model of RTC tear, and compared these functional changes to histopathology of the muscle. Methods: Unilateral RTC tears were induced in male rats via tenotomy of the supraspinatus and infraspinatus. Maximal tetanic force and susceptibility to injury of the supraspinatus muscle were measured in vivo at day 2 and day 15 after tenotomy. Supraspinatus muscles were weighed and harvested for histologic analysis of the neuromuscular junction (NMJ), intramuscular lipid, and collagen. Results: Tenotomy resulted in eventual atrophy and weakness. Despite no loss in muscle mass at day 2 there was a 30% reduction in contractile force, and a decrease in NMJ continuity and size. Reduced force persisted at day 15, a time point when muscle atrophy was evident but NMJ morphology was restored. At day 15, torn muscles had decreased collagen-packing density and were also more susceptible to contraction-induced injury. Conclusion: Muscle size and histopathology are not direct indicators of overall RTC contractile health. Changes in NMJ morphology and collagen organization were associated with changes in contractile function and thus may play a role in response to injury. Although our findings are limited to the acute phase after a RTC tear, the most salient finding is that RTC tenotomy results in increased susceptibility to injury of the supraspinatus

Reliability, validity, and responsiveness of a novel subscapularis outcome score: the Baltimore Orthopedic Subscapularis Score

BACKGROUND: Available surveys that evaluate shoulder strength and pain often combine rotator cuff muscles making the test unable to differentiate subscapularis tears from other pathology including concomitant supraspinatus, infraspinatus tears. The purpose of this study was to validate a subscapularis-specific shoulder survey (Baltimore Orthopedic Subscapularis Score) as a viable clinical outcome assessment through analysis of psychometric properties. METHODS: A 5-question survey was given to a study population of 390 patients, 136 of whom had full thickness rotator cuff tears with a minimum score of 5 (better) and a maximum score of 25 (worse). Surveys were given during the initial consultation, preoperative visit, and postoperative visit. Content validity, construct validity, test-retest reliability, responsiveness to change, internal consistency, and minimal clinically important difference using distribution and anchor-based methods were determined for our subscapularis function survey. RESULTS: A high correlation was reported on test-retest reliability (intraclass correlation coefficient = 0.89). An acceptable internal consistency was reported for all patients surveyed (Cronbach alpha = 0.91). Floor and ceiling effects for patients with rotator cuff pathology were minimized (1% for both). Patients with an isolated subscapularis tear scored worse than supraspinatus/infraspinatus tears and exhibited similar dysfunction as patients with a supraspinatus/infraspinatus/subscapularis tear. An acceptable construct validity was reported with subscapularis-involved tears demonstrating higher scores with significance ( \u3c .05). There was excellent responsiveness to change with a standardized response mean of 1.51 and effect size of 1.27 (large \u3e 0.8). The minimal clinically important difference using a distribution and anchor-based method was 4.1 and 4.6, respectively. Among patients with rotator cuff tears in this population, a score of 22 or higher predicts a subscapularis tear 75% of the time, in spite of its low overall prevalence. CONCLUSION: The subscapularis shoulder score demonstrated acceptable psychometric performance for outcomes assessment in patients with rotator cuff disease. This survey can be used as an effective clinical tool to assess subscapularis function

An accurate method of measuring shoulder sling compliance: a validation study

Abstract Background The effect of postoperative shoulder sling compliance on surgical outcomes is unknown. The goal was to determine an accurate method to measure sling compliance. We compared volunteer recorded sling wear time with temperature-based sensors to monitor sling compliance. Methods Data loggers sutured at three locations measured heat generated in 15-minute intervals. Slings wearers logged sling wear to accurately cross-reference with temperature sensors. Secondary experiments analyzed whether surrounding ambient temperature can be discerned from actual sling wear. We created an algorithm to describe actual sling wear time as a function of heat recorded and calculated percent wear accuracy. Results The modified sling was worn for 172 h. The algorithm modeled sling on/off times by analyzing cutoff temperatures. Diagnostic accuracy was >99 % for the three locations, with no statistically significant differences among them. Compared with sling wear, ambient temperature took longer to reach critical temperature values determined by the algorithm, helping distinguish compliance from false positives. Conclusions The described algorithm can effectively quantify shoulder sling wear time based on heat-generated sensor readings. False positives from ambient temperature are minimal. This measurement method could be used to study the relationship between postoperative sling use and functional outcomes after shoulder surgery

Difference in Resident Versus Attending Perspective of Competency and Autonomy During Arthroscopic Rotator Cuff Repairs

Background:. A noted deficiency in orthopaedic resident education is a lack of intraoperative autonomy; however, no studies exist evaluating this issue. The purpose of this study was to determine whether there is a difference between resident and attending perception of resident competency and autonomy during arthroscopic rotator cuff repairs and whether increased perceived competency leads to more autonomy. Methods:. This study included 21 orthopaedic residents and 7 attendings from a single residency program. A survey was developed that included the previously validated Ottawa Surgical Competency Operating Room Evaluation (O-SCORE) and implemented novel arthroscopic rotator cuff repair questions concerning 5 key procedural steps determined by attendings. The survey assessed resident and attending perception of percent opportunity given and percent completed of each step and whether the resident could complete the surgery independently. Paired comparisons were conducted using the Wilcoxon signed-rank test. Agreement between residents and attendings was calculated using a linear-weighted Gwet's AC2. A secondary analysis investigated resident perception of autonomy stratified by attending perception of competency using Kruskal-Wallis tests. Results:. One hundred forty-two surveys were completed over one academic year. Residents reported a 4-point higher median O-SCORE (34) than attendings (30; p < 0.01; agreement = 0.63). Residents perceived less opportunity compared with attendings, with a median opportunity to complete each step of 54% vs. 70% (p < 0.01; agreement = 0.39). Residents also perceived lower percent completed of the key steps compared with attendings, with medians of 52% vs. 61% (p < 0.01; agreement = 0.37). Resident perceived opportunity increased with higher attending reported O-SCOREs (p < 0.01) and percent completion of the key steps (p < 0.01). No statistically significant increase in perceived opportunity was observed the with post-graduate year (PGY) level (p = 0.35). Discussion:. This study demonstrated a significant difference in perception between residents and attendings regarding resident competency and autonomy during arthroscopic rotator cuff repairs. It also demonstrated that with increasing attending perception of competency, there was an increasing resident perception of autonomy, but there was no statistically significant difference of perceived autonomy based on the PGY-level

DS_10.1177_0363546518769267 – Supplemental material for Fatty Infiltration Is a Prognostic Marker of Muscle Function After Rotator Cuff Tear

<p>Supplemental material, DS_10.1177_0363546518769267 for Fatty Infiltration Is a Prognostic Marker of Muscle Function After Rotator Cuff Tear by Ana P. Valencia, Jim K. Lai, Shama R. Iyer, Katherine L. Mistretta, Espen E. Spangenburg, Derik L. Davis, Richard M. Lovering and Mohit N. Gilotra in The American Journal of Sports Medicine</p