The role of greater tuberosity healing in reverse shoulder arthroplasty: a finite element analysis.

BACKGROUND: The lack of greater tuberosity (GT) healing in proximal humerus fractures has been negatively correlated with outcomes for hemiarthroplasty; however, there is still debate regarding the effects of GT healing in reverse shoulder arthroplasty (RSA). Our goal was to examine the effects of GT healing using a kinematic finite element analysis (FEA) model. MATERIAL AND METHODS: Computer-aided design models of a medialized glenoid with a lateralized humerus (MGLH) RSA design were uploaded into an FEA shoulder model in 2 different configurations: healed greater tuberosity (HGT) and nonunion greater tuberosity (NGT). Deltoid muscle forces and joint reaction forces (JRFs) on the shoulder were calculated during abduction (ABD), forward flexion (FF), and external rotation (ER). RESULTS: Force magnitude of the anterior, middle, and posterior deltoid muscle as well as JRFs modeled in both GT scenarios were similar for ABD (muscle forces P = .91, P = .75, P = .71, respectively; and JRF P = .93) and for FF (muscle forces P = .89, P = .83, P = .99, respectively; and JRF P = .90). For ER, the force magnitude between 2 GT settings showed statistically significant differences (HGT: 9.51 N vs. NGT: 6.13 N) (P < .001). Likewise, during ER, JRFs were different, and the NGT group showed a steep drop in JRF after 10° of ER (HGT: 28.4 N vs. NGT: 18.38 N) (P < .001). CONCLUSION: GT healing does not seem to impact RSA biomechanics during abduction or forward flexion; however, it does affect biomechanics during external rotation. Overall orthopedic surgeons can expect good results for patients after RSA even with poor GT healing.

Unpacking the Tibial Tubercle-Trochlear Groove Distance: Evaluation of Rotational Factors, Trochlear Groove and Tibial Tubercle Position, and Role of Trochlear Dysplasia.

BACKGROUND: The tibial tubercle to trochlear groove (TT-TG) distance is often utilized for determining the surgical treatment for patients with patellar instability (PI). It is thought to directly represent the position of the TT on the tibia. Recent work has shown that the measurement of the TT-TG distance is multifactorial. PURPOSE: To investigate the relationship between relative tibial external rotation (rTER) and trochlear dysplasia (TD), as well as the location of the TG and TT in patients with and without PI, and to correlate these and other anatomic measurements with the TT-TG distance. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A total of 89 patients with PI who underwent magnetic resonance imaging were identified with 92 matched control patients. A standardized measurement protocol on axial magnetic resonance imaging determined rTER, the proximal and distal TG lateralization (pTGL and dTGL, respectively) ratios, and the TT lateralization (TTL) ratio. Other measures of interest included the lateral trochlear inclination angle, sulcus angle, and lateral patellar inclination angle. Univariate regression was used to determine the associations of TD (lateral trochlear inclination angle, sulcus angle) with rTER and the TG position, and multivariate regression was used to model associations among all the variables with the proximal and distal TT-TG distances. RESULTS: rTER was significantly higher in the study group (P < .001), and univariate regression showed a significant association between dysplasia measures and rTER (P < .001). The pTGL ratio was lower in the study group (P = .025), but there was no difference in the dTGL ratio (P = .090) or the TTL ratio (P = .098) between the groups. There were no associations between dysplasia measures and the pTGL and dTGL ratios (P > .05). Multivariate regression showed that the proximal TT-TG distance is predicted by the sulcus angle, pTGL ratio, rTER, and TTL ratio (P < .05) and that the distal TT-TG distance is predicted by the lateral patellar inclination angle, dTGL ratio, sulcus angle, rTER, and TTL ratio (P < .05). CONCLUSION: rTER had a significant association with TD. The position of the proximal TG was more medial in patients with PI. There was no significant difference in the TTL ratio between patients with and without PI. The TT-TG distance was associated with multiple anatomic measures and was not solely predicated on the position of the TT.

Posterior Labral Tear Extension Concomitant With Shoulder Bankart Injuries Is not Uncommon.

Purpose: To identify the rate and risk factors of posterior labral involvement in operatively managed Bankart lesions and assess the effectiveness of MRI arthrogram for preoperative identification of such injury patterns. Methods: A consecutive cohort of patients undergoing arthroscopic Bankart repair were retrospectively reviewed. All subjects underwent a prearthroscopy MRI arthrogram. Operative findings were used as the gold standard for posterior labral tear extension. Patient demographic and surgical data were then analyzed to identify independent factors associated with the presence of concomitant posterior labral injury. Results: Of 124 patients undergoing arthroscopic Bankart stabilization, 23 (19%) were noted to demonstrate posterior labral injury on arthroscopic evaluation. Factors associated with injury to the posterior labrum included those sustaining two or fewer dislocations events (P =.001), an earlier average presentation (P = .001), and a reported "contact" mechanism of dislocation (P = .02). Posterior labral involvement did not correlate with surgical positioning (beach-chair versus lateral) or the need for revision surgery. On the basis of review of preoperative imaging, MRI arthrogram demonstrated a sensitivity of 83% and a specificity of 95% for detection of posterior labral injury. Conclusions: Posterior propagation of Bankart lesions is relatively common following shoulder dislocations, with a rate of 18.5%. Risk factors for posterior labral extension include two or fewer dislocations, early presentation from the time of injury, and contact sports. On the basis of these findings, careful assessment of the posterior labrum on MRI arthrogram may reveal the majority, but not all, of these lesions. Level of Evidence: Level III, retrospective case-controlled study.

On-Track Lesions with a Small Distance to Dislocation Are Associated with Failure After Arthroscopic Anterior Shoulder Stabilization.

BACKGROUND: Off-track lesions are strongly associated with failure after arthroscopic Bankart repair. However, on-track lesions with a small distance-to-dislocation (DTD) value, or "near-track lesions," also may be at risk for failure. The purpose of the present study was to determine the association of DTD with failure after arthroscopic Bankart repair. METHODS: We performed a retrospective analysis of 173 individuals who underwent primary arthroscopic Bankart repair between 2007 and 2015. Glenoid bone loss and Hill-Sachs lesion size were measured with use of previously reported methods. Patients with failure were defined as those who sustained a dislocation after the index procedure, whereas controls were defined as individuals who did not. DTD was defined as the distance from the medial edge of the Hill-Sachs lesion to the medial edge of the glenoid track. Receiver operating characteristic (ROC) curves were constructed for DTD to determine the critical threshold that would best predict failure. The study population was subdivided into individuals ≥20 years old and <20 years old. RESULTS: Twenty-eight patients (16%) sustained a recurrent dislocation following Bankart repair. Increased glenoid bone loss (p < 0.001), longer Hill-Sachs lesion length (p < 0.001), and decreased DTD (p < 0.001) were independent predictors of failure. ROC curve analysis of DTD alone demonstrated that a threshold value of 8 mm could best predict failure (area under the curve [AUC] = 0.73). DTD had strong predictive power (AUC = 0.84) among individuals ≥20 years old and moderate predictive power (AUC = 0.69) among individuals <20 years old. Decreasing values of DTD were associated with a stepwise increase in the failure rate. CONCLUSIONS: A "near-track" lesion with a DTD of <8 mm, particularly in individuals ≥20 years old, may be predictive of failure following arthroscopic Bankart repair. When using the glenoid track concept as the basis for surgical decision-making, clinicians may need to consider the DTD value as a continuous variable to estimate failure instead of using a binary on-track/off-track designation. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of Levels of Evidence.

Failure rates and clinical outcomes after treatment for long-head biceps brachii tendon pathology: a comparison of three treatment types.

HYPOTHESIS/BACKGROUND: Treatment options for the biceps brachii tendon include tenotomy, arthroscopic tenodesis, and open tenodesis. Few studies to date have compared all treatment options in the context of a rotator cuff repair. METHODS: A retrospective review of 100 patients who underwent arthroscopic supraspinatus repair between 2013 and 2018 with a minimum of one-year follow-up was performed. Patients were separated into the following 4 groups: (1) 57 had isolated supraspinatus repair with no biceps tendon surgery (SSP); (2) 16 had supraspinatus repair and biceps tenotomy; (3) 18 had supraspinatus repair and arthroscopic biceps tenodesis; (4) 9 had supraspinatus repair and an open biceps tenodesis (SSP + OT). The primary outcome was operative time. The secondary outcomes were cost analysis, complications, patient-reported outcome measures, range of motion, and strength testing. RESULTS: The operative time for the SSP + OT group was significantly longer than that of the SSP group (P < .05) but was not significantly longer than that of the other groups. The cost for the SSP group was significantly less than the cost for the SSP + OT and supraspinatus repair and arthroscopic biceps tenodesis groups (P < .05 for both), whereas the cost for the supraspinatus repair and biceps tenotomy group was significantly less than the cost for the SSP + OT group (P < .05). There were no significant differences between groups for complications, all patient-reported outcome measues, all range of motion, and all strength parameters. DISCUSSION/CONCLUSION: Operative time is the longest in open biceps tenodesis and is significantly longer than that of isolated supraspinatus repair. No significant differences in operative times or costs were identified in patients undergoing arthroscopic vs. open biceps tenodesis. All patients, irrespective of the type of biceps tendon procedure, had excellent clinical and functional outcomes at least one year after surgery. There was no difference in clinical or functional outcomes, or complications, among the 4 groups.