Evaluation of rotator cuff abduction moment arms for superior capsular reconstruction and reverse total shoulder arthroplasty.

PURPOSE: The rotator cuff (RC) muscles contribute to dynamic stability and rotational actions of the glenohumeral joint. Moment arm can be used to demonstrate the potential work a muscle contributes to a musculoskeletal joint rotation. This study aimed to understand the moment arm contributions of the RC muscles and explore changes following a complete supraspinatus tear treated with either superior capsular reconstruction (SCR) or reverse total shoulder arthroplasty (rTSA). METHODS: Five fresh-frozen cadaveric specimens were prepared and mounted in an apparatus where each intact RC muscle was held in tension with a line of action toward its origin on the scapula. Mean moment arms for each muscle were determined experimentally based on Optotrak data collected during cadaveric shoulder arm abduction. RESULTS: Using ANOVA testing, our analysis demonstrated significant differences (p < 0.001) in infraspinatus and teres minor moment arms after rTSA compared to the intact shoulder model. After SCR, significant differences (p < 0.001) were seen in teres minor, with these differences being statistically similar to the changes seen in teres minor after rTSA. Subscapularis showed no significant difference in moment arm values between the models (p = 0.148). CONCLUSION: Our results illustrate that mean moment arms were preserved in the RC muscles after complete supraspinatus tear. This study also shows evidence that subscapularis function may be maintained after SCR or rTSA. After SCR, infraspinatus may maintain similar abduction ability compared to the anatomical shoulder, while teres minor ability may increase. Infraspinatus may have decreased abduction ability after rTSA while teres minor may have increased ability.

Do Demographic or Anthropometric Factors Affect Lateralization of the Tibial Tubercle in a Diverse Population? A Magnetic Resonance Imaging Analysis.

INTRODUCTION: The tibial tubercle-trochlear groove (TT-TG) distance is commonly used to evaluate and guide treatment for patellar instability. There is limited data available regarding TT-TG variability based on patient demographics and anthropometric factors. MATERIALS AND METHODS: TT-TG was measured on magnetic resonance imaging (MRI) for 384 consecutive adult patients. Demographic information for the corresponding was then gathered from the medical record and analyzed. Demographic variables analyzed included age, sex, race, height, weight, and body mass index (BMI). RESULTS: Mean TT-TG among the 384 patients was 12.68mm (standard deviation [SD]: 4.13mm, 95% confidence interval [CI] 12.26-13.10mm, range, 3.2-27.0mm), and there was a significant correlation with height (p=0.009), weight (p=0.017), and race (p<0.001). However, there was no significant correlation seen with sex (p=0.854), BMI (p=0.253), or age (p=0.096). Height and African American race were identified as independent predictors of increased TT-TG (p=0.007 and p<0.001, respectively); and females were found to have an increased TT-TG relative to height (p=0.015). CONCLUSION: Tibial tubercle-trochlear groove distance was significantly correlated with race and height in the 384 patients examined. These findings may help explain clinical differences in these patients and help establish "norms" for patients of various ethnic and anthropometric variability.

Biomechanical evaluation of distal biceps tendon repair using tension slide technique and knotless fixation technique.

BACKGROUND: Acute distal biceps tendon ruptures are uncommon injuries that often affect young active males, typically resulting from an eccentric load on their dominant extremity. The purpose of this study was to compare pullout strength and tendon gapping in the tension slide technique (TST) versus a knotless fixation technique (KFT). METHODS: Two sets of experiments were performed using cadaveric elbow specimens. In the first experiment, eight elbows from different cadavers were tested to compare TST with a standard locking whipstitch with KFT, four elbows in each group, using a standard locking whipstitch. In the second experiment, 12 elbows were used to study the differences between TST with a standard locking whipstitch with KFT using suture tape reinforced whipstitch (RKFT), using the TST data from the first and second experiment. Each experiment evaluated gapping after cyclic loading and the second experiment also tested the construct to load to failure. RESULTS: Gapping for KFT with a standard locking whipstitch was 10.64 mm versus 2.69 mm for the TST after 1000 cycles (P = 0.016). A reinforced whipstitch significantly improved the failure to gap on the KFT with no significant difference in gapping when compared to TST after 3000 cycles (P = 0.36). The resultant gapping for TST and KST was 2.08 mm and 2.99 mm (P = 0.91), respectively. Load to failure for TST and KFT were 282 Nm and 328 Nm (P = 0.20), respectively. CONCLUSION: Bone-tendon gap resistance of a KFT repair of a torn distal biceps tendon is limited by suture technique. Using a tape reinforced locking whipstitch, the repair is as strong as TST repair. LEVELS OF EVIDENCE: Basic Science.

Survey study suggests that reverse total shoulder arthroplasty is becoming the treatment of choice for four-part fractures of the humeral head in the elderly.

PURPOSE: The role of reverse total shoulder arthroplasty (RTSA) for three and four-part proximal humerus fractures is evolving. However, there does not appear to be a clear consensus amongst surgeons. The purpose of this study is to further define the standard of care, assessing surgeon preference and treatment considerations for management of such fractures. METHODS: Orthopaedic surgeons were surveyed on their training, practice setting, and experience regarding management of four-part proximal humerus fractures. The survey also presented five representative cases to assess treatment preferences. RESULTS: Two hundred five surgeons responded to the survey with fellowship training in shoulder and elbow surgery (114), orthopaedic trauma (35) or sports medicine/other training (56). There was no difference between respondents with years in practice and confidence with performing RTSA, however, surgeons in the academic setting were more confident in performing the surgery. Surgeons preferred RTSA for management of four-part fractures in patients over age 65. However, they also trended to favour hemiarthroplasty with higher co-morbidities. Physicians with more than 11 years of experience were more likely to choose hemiarthroplasty for older and high comorbidity patients. RTSA was not the preferred treatment method for younger, active patients. Patient age and fracture pattern had a greater influence on the surgeon's decision. CONCLUSIONS: There is a consensus in our study population that RTSA is the preferred treatment for four-part proximal humerus fractures for elderly patients with patient age and fracture pattern being the most important factors in making management decisions. LEVEL OF EVIDENCE: Level III - Case controlled study.

National trends and perioperative outcomes in primary and revision total shoulder arthroplasty: Trends in total shoulder arthroplasty.

INTRODUCTION: Total shoulder arthroplasty (TSA) is a highly successful procedure for management of glenohumeral arthritis, fractures and rotator cuff tears. The purpose of this study was to evaluate patient demographics, perioperative outcomes and assess recent national trends in both primary and revision TSA. METHODS: The National Hospital Discharge Survey database was searched for patients admitted to US hospitals for primary and revision TSA from 2001 to 2010. RESULTS: A total of 1,297 patients who underwent primary TSA and 184 patients who underwent revision TSA were identified. The rates of primary TSA (r = 0.88) and revision TSA (r = 0.85) both demonstrated a strong positive correlation with time. The mean patient age of the primary group was significantly higher than the revision group. Gender was not significantly different between the groups. There was no significant difference in the racial make-up between the revision and primary groups. African Americans accounted for 3.3 % of primaries versus 4.3 % of revisions (p = 0.615). Revision TSA patients had a significantly longer average LOS (3.06 days vs 2.46 days, p < 0.01), more medical comorbidities (6.0 vs 5.1 comorbidities, p < 0.01) and a higher rate of developing a myocardial infarction (2.2 % versus 0 %, p < 0.01) than the primary TSA group. CONCLUSIONS: This study demonstrates that the rate of TSA is rapidly increasing in the US, with over a four-fold increase in revisions and five-fold increase in primaries over the ten years studied.

Infraspinatus Muscle Fiber Moment Arms During Abduction: A Biomechanical Comparison of Values for Intact Rotator Cuff, Supraspinatus Tear, Superior Capsular Reconstruction, and Reverse Total Shoulder Arthroplasty.

Background: Lines of action of the superior, middle, and inferior infraspinatus muscle fibers work together to produce moment arms that change throughout abduction in an intact shoulder, after a supraspinatus tear, and after superior capsular reconstruction (SCR) and reverse total shoulder arthroplasty (rTSA). Purpose: To use moment arm values to indicate the efficacy of SCR and rTSA to restore infraspinatus function during shoulder abduction. Study Design: Descriptive laboratory study. Methods: A total of 5 human cadaveric shoulders placed in a testing apparatus were each actively abducted (0°-90°) under the following 4 conditions: intact, complete supraspinatus tear, SCR, and rTSA. The 3-dimensional coordinates of points were tracked along the origin and insertion of the superior, middle, and inferior infraspinatus fibers during abduction. Moment arm values were calculated using the origin-insertion method to determine abduction contribution of infraspinatus fiber sections. Analysis of variance and post hoc Tukey testing were used to compare differences in moment arms between the 4 conditions and between fiber sections. Results: In the intact condition, the superior infraspinatus fibers had an abduction moment that decreased with elevation until shifting to adduction. Conversely, the middle and inferior fibers had an adduction moment that turned to abduction (mean moment arm values from 0° to 90°: inferior, from -5.9 to 19.4 mm; middle, from -4.7 to 15.9 mm; superior, from 5.6 to -5.1 mm; P < .05). After a supraspinatus tear, superior fibers lacked any torque, and inferior and middle fibers lost adduction potential (inferior, from 4.8 to 14.0 mm; middle, from -0.2 to 9.6 mm; superior, from 1.0 to 0.7 mm; P < .05). SCR restored the initial superior fiber abduction moment (5.6 mm at 0°; P < .05); middle and inferior fibers had some restoration but were weaker than intact fibers. Loss of abduction moment in all fibers was seen with rTSA (inferior, from -9.6 to -1.6 mm; middle, from -10.5 to -3.6 mm; superior, from -1.7 to -4.6 mm; P < .05). Conclusion: Infraspinatus fiber groups had different and inverse moment arms during scapular plane elevation. SCR most closely resembled the intact shoulder, whereas rTSA transformed the infraspinatus into an adductor. Clinical Relevance: These results support the efficacy of SCR at restoring biomechanical muscle function and suggest that the changes in moment arms for each fiber group be considered when choosing treatment modalities and rehabilitation protocols after rotator cuff tear.

Scapular winging: an update.

Scapular winging is a rare disorder often caused by neuromuscular imbalance in the scapulothoracic stabilizer muscles. Lesions of the long thoracic nerve and spinal accessory nerves are the most common cause. Numerous underlying etiologies have been described. Patients report diffuse neck, shoulder girdle, and upper back pain, which may be debilitating, associated with abduction and overhead activities. Accurate diagnosis and detection depend on appreciation of the scapulothoracic anatomy and a comprehensive physical examination. Although most cases resolve nonsurgically, surgical treatment of scapular winging has been met with success.

Abnormal translation in SLAP lesions on magnetic resonance imaging abducted externally rotated view.

PURPOSE: The purpose of this study was to measure in vivo axial-plane translation of the glenohumeral joint by use of magnetic resonance imaging in patients with and without SLAP lesions between the conventional adducted neutral rotation (AD) view and an abducted externally rotated (ABER) view. METHODS: Seven patients with an intraoperative SLAP lesion that was unstable and required repair were selected into the SLAP group. Although they did not have normal shoulders, 15 patients were selected into the control or comparison group, most of whom had rotator cuff pathology. The glenohumeral contact point (CP) and humeral head center (HHC) were calculated and compared with the glenoid surface as a relative anterior or posterior translation. The relative posterior translation between the ABER and AD views for each patient was calculated as Delta CP and Delta HHC. These values were compared between the SLAP and control groups. RESULTS: There was a significant difference in Delta CP between the SLAP and control groups (3.62 v 0.79 mm of relative posterior translation, P = .005). There was not a similar significant difference found in Delta HHC between the SLAP and control groups (3.19 mm v 1.48 mm of relative posterior translation, P = .14). There was a significant difference between the mean translations of the SLAP-ABER group and the SLAP-AD group for both CP (-3.65 mm v -0.04 mm, P = .008) and HHC (-2.22 mm v +0.97 mm, P = .03). The difference between the control-ABER group and the control-AD group was not as pronounced. CONCLUSIONS: The magnetic resonance imaging ABER view in patients with unstable SLAP lesions requiring repair showed in vivo glenohumeral posterior translation relative to the adducted neutral rotation view of greater than 3 mm. CLINICAL RELEVANCE: This finding furthers the understanding of the pathokinematics in SLAP lesions.

Is Arthroscopic Transosseous Rotator Cuff Repair Strength Dependent on the Tunnel Angle?

BACKGROUND: Previous studies have aimed to biomechanically improve the transosseous tunnel technique of rotator cuff repair. However, no previous work has addressed tunnel inclination at the time of surgery as an influence on the strength of the repair construct. HYPOTHESIS: We hypothesized that the tunnel angle and entry point would influence the biomechanical strength of the transosseous tunnel in rotator cuff repair. Additionally, we investigated how tunnel length and bone quality affect the strength of the repair construct. STUDY DESIGN: Controlled laboratory study. METHODS: Mechanical testing was performed on 10 cadaveric humeri. Variations in the bone tunnel angle were imposed in the supraspinatus footprint to create lateral tunnels with inclinations of 30°, 45°, and 90° relative to the longitudinal axis of the humeral shaft. A closed loop of suture was passed through the bone tunnel, and cyclic loading was applied until failure of the construct. Load to failure and distance between entry points were the dependent variables. Analysis of variance, post hoc paired t tests, and the Bonferroni correction were used to analyze the relationship between the tunnel angle and failure load. The Pearson correlation coefficient was then used to evaluate the correlation of the distance between entry points to the ultimate failure load, and t tests were used to compare failure loads between healthy and osteoporotic bone. RESULTS: Tunnels drilled perpendicularly to the longitudinal axis (90°) achieved the highest mean failure load (167.51 ± 48.35 N). However, there were no significant differences in the failure load among the 3 tested inclinations. Tunnels drilled perpendicularly to the longitudinal axis (90°) measured 13.86 ± 1.35 mm between entry points and were significantly longer (P = .03) than the tunnels drilled at 30° and 45°. We found no correlation of the distance between entry points and the ultimate failure load. Within the scope of this study, we could not identify a significant effect of bone quality on failure load. CONCLUSION: The tunnel angle does not influence the strength of the bone-suture interface in the transosseous rotator cuff repair construct. CLINICAL RELEVANCE: The transosseous technique has gained popularity in recent years, given its arthroscopic use. These findings suggest that surgeons should not focus on the tunnel angle as they seek to maximize repair strength.

Single-Incision Anatomic Repair Technique for Distal Biceps Tendon Rupture Using Tunneling Device.

Distal biceps tendon ruptures are uncommon and generally occur in men aged 30 to 50 years in their dominant arm as a result of a strong eccentric load. Numerous surgical exposures and methods of fixation exist for repair of a ruptured distal biceps tendon. The goal of surgical management is to restore the anatomic footprint of the biceps tendon on the radial tuberosity to maximize flexion strength, supination strength, and muscle endurance. When compared with 2-incision repair techniques, single-incision repairs historically may not have restored the anatomic footprint of the distal biceps. Single-incision repair with the ArthroTunneler is a safe and effective technique that provides the anatomic restoration of a 2-incision approach with the decreased complication profile of a single-incision approach and does not require suture anchors, buttons, screws, or other implants.

Total Knee Arthroplasty in the Younger Patient.

The rate of total knee arthroplasty (TKA) utilization in younger patients (< 65 years old) is increasing. Little is known regarding demographics and in-hospital outcomes in this population. The National Hospital Discharge Survey (NHDS) database was searched using International Classification of Diseases, Ninth Revision (ICD-9) procedure codes for patients admitted to U.S. hospitals for unilateral primary TKA between 2001 and 2010. Patients were separated into young (< 65 years of age) and senior cohorts (≥ 65 years of age). ICD-9 diagnosis and procedure codes were used to identify demographics, hospital length of stay, in-hospital adverse events, mortality, and discharge disposition. Trends were evaluated by linear regression with Pearson correlation coefficient (r) and statistical comparisons were made using Student t-test and chi-square analysis. The young cohort accounted for 38.4% of TKAs performed from 2001 to 2005, increasing to 42.7% of TKAs from 2006 to 2010. They had a higher percentage of males (36.4 vs. 34.2%, p < 0.001). Rates of obesity (11.1 vs. 6.0%, p < 0.001) and morbid obesity (5.8 vs. 1.9%, p < 0.001) were significantly higher, yet they had less comorbidities (4.7 vs. 5.2, p < 0.001), and lower rates of transfusion (12.2 vs. 19.8%, p < 0.001), pulmonary embolism (PE) (0.31 vs. 0.49%, p < 0.020), and mortality (0.03 vs. 0.18%, p < 0.001). Patients < 65 years old undergoing TKA have almost double the rate of obesity of patients ≥ 65 years old. This could explain the higher rates of periprosthetic infection and aseptic mechanical failure seen in younger patients. However, the young cohort had a more favorable discharge disposition and lower mortality and risk of PE than elderly patients.

Total Hip Arthroplasty and Hemiarthroplasty: US National Trends in the Treatment of Femoral Neck Fractures.

There is controversy regarding whether total hip arthroplasty (THA) or hemiarthroplasty (HA) is the treatment preferred for displaced intracapsular femoral neck fractures (FNFs). Using the US National Hospital Discharge Survey, we found that, of 12,757 patients admitted for FNF between 2001 and 2010, 4.6% underwent THA and 52.5% underwent HA. More of both procedures were performed over time. Mean age was higher for HA patients. Hospitalization duration and blood transfusion rates were higher for THA. There were region-based differences in frequency of THA and significant hospital-size-based differences in frequency of HA, possibly because of differences in regional training and subspecialist availability. In addition, a larger proportion of THA patients was covered by private insurance.

Posterior capsular contracture of the shoulder.

Posterior capsular contracture is a common cause of shoulder pain in which the patient presents with restricted internal rotation and reproduction of pain. Increased anterosuperior translation of the humeral head occurs with forward flexion and can mimic the pain reported with impingement syndrome; however, the patient with impingement syndrome presents with normal range of motion. Initial management of posterior capsular contracture should be nonsurgical, emphasizing range-of-motion stretching with the goal of restoring normal motion. For patients who fail nonsurgical management, arthroscopic posterior capsule release can result in improved motion and pain relief. In the throwing athlete, repetitive forces on the posteroinferior capsule may cause posteroinferior capsular hypertrophy and limited internal rotation. This may be the initial pathologic event in the so-called dead arm syndrome, leading to a superior labrum anteroposterior lesion and, possibly, rotator cuff tear. Management involves regaining internal rotation such that the loss of internal rotation is not greater than the increase in external rotation. In the athlete who fails nonsurgical management, a selective posteroinferior capsulotomy can improve motion, reduce pain, and prevent further shoulder injury.

Effects of a cyclooxygenase-2 inhibitor (rofecoxib) on bone healing.

In the study reported here, we determined the effects on bone healing of rofecoxib, one of the selective cyclooxygenase-2 (Cox-2) inhibitors that has been used for postsurgical analgesia, and compared these effects with those of nonselective ibuprofen and placebo. Each of 66 male rats received a closed, nondisplaced femoral fracture and was fed rofecoxib, ibuprofen, or placebo for 4 weeks. Results of postsacrifice evaluation showed gross nonunions in 64.7% of rofecoxib rats (P < .0001), 17.6% of ibuprofen rats (P = .007), and 0% of placebo rats. Compared with ibuprofen, rofecoxib was significantly more likely to produce nonunions (P = .007). Mean callus width was 8.9 mm (SD, 1.3 mm) for rofecoxib (P = .03), 8.9 mm (SD, 1.2 mm) for ibuprofen (P = .03), and 8.0 mm (SD, 1.3 mm) for placebo. Mean healing maturity (Goldberg classification) was 1.6 (SD, 0.7) for rofecoxib (P < .0001), 1.7 (SD, 0.8) for ibuprofen (P = .0001), and 2.7 (SD, 0.6) for placebo. Mean fracture angulation was 30.8 degrees (SD, 16.7 degrees) for rofecoxib (P = .003), 14.3 degrees (SD, 14.4 degrees) for ibuprofen (NS), and 13.4 degrees (SD, 10.3 degrees) for placebo. Mean histologic healing was 5.75 for rofecoxib (P = .02), 6.35 for ibuprofen (P = .05), and 8.25 for placebo. Cox-2 inhibitors should be used with caution when bone healing is necessary. Further study is warranted to determine whether the adverse effects occur in humans.

Methicillin-resistant Staphylococcus aureus infected gluteal compartment syndrome with rhabdomyolysis in a bodybuilder.

Gluteal compartment syndrome (GCS) is a rare condition. We present a case of gluteal muscle strain with hematoma formation, methicillin-resistant Staphylococcus aureus (MRSA) superinfection, leading to acute GCS, rhabdomyolysis and acute kidney injury. This combination of diagnoses has not been reported in the literature. A 36-year-old Caucasian male presented with buttock pain, swelling and fever after lifting weights. Gluteal compartment pressure was markedly elevated compared with the contralateral side. Investigations revealed elevated white blood cell, erythrocyte sedimentation rate, C-reactive protein, creatine kinase, creatinine and lactic acid. Urinalysis was consistent with myoglobinuria. Magnetic resonance imaging showed increased T2 signal in the gluteus maximus and a central hematoma. Cultures taken from the emergency debridement and fasciotomy revealed MRSA. He had repeat, debridement 2 d later, and delayed primary closure 3 d after. GCS is rare and must be suspected when patients present with pain and swelling after an inciting event. They are easily diagnosed with compartment pressure monitoring. The treatment of gluteal abscess and compartment syndrome is the same and involves rapid surgical debridement.

Technical Errors May Affect Accuracy of Torque Limiter in Locking Plate Osteosynthesis.

In locking plate osteosynthesis, proper surgical technique is crucial in reducing potential pitfalls, and use of a torque limiter makes it possible to control insertion torque. We conducted a study of the ways in which different techniques can alter the accuracy of torque limiters. We tested 22 torque limiters (1.5 Nm) for accuracy using hand and power tools under different rotational scenarios: hand power at low and high velocity and drill power at low and high velocity. We recorded the maximum torque reached after each torque-limiting event. Use of torque limiters under hand power at low velocity and high velocity resulted in significantly (P < .0001) different mean (SD) measurements: 1.49 (0.15) Nm and 3.73 (0.79) Nm. Use under drill power at controlled low velocity and at high velocity also resulted in significantly (P < .0001) different mean (SD) measurements: 1.47 (0.14) Nm and 5.37 (0.90) Nm. Maximum single measurement obtained was 9.0 Nm using drill power at high velocity. Locking screw insertion with improper technique may result in higher than expected torque and subsequent complications. For torque limiters, the most reliable technique involves hand power at slow velocity or drill power with careful control of insertion speed until 1 torque-limiting event occurs.

Percutaneous antegrade intramedullary nailing of the femur in obese patients.

Antegrade intramedullary nailing using the piriformis fossa as an entry point for insertion has become the treatment of choice for most diaphyseal fractures of the femur. In obese or well-muscled patients, however, creating an entry point can be difficult. This difficulty has led some authors to switch to retrograde intramedullary nailing. Unfortunately, retrograde nailing is associated with higher nonunion rates and increased incidence of knee pain and stiffness. We describe an antegrade nailing technique that is useful and easy to perform even in obese patients.