Two-year clinical outcomes and complication rates in anatomic and reverse shoulder arthroplasty implanted with Exactech GPS intraoperative navigation.

INTRODUCTION: We compared the 2-year clinical outcomes of both anatomic and reverse total shoulder arthroplasty (ATSA and RTSA) using intraoperative navigation compared to traditional positioning techniques. We also examined the effect of glenoid implant retroversion on clinical outcomes. HYPOTHESIS: In both ATSA and RTSA, computer navigation would be associated with equal or better outcomes with fewer complications. Final glenoid version and degree of correction would not show outcome differences. MATERIAL AND METHODS: A total of 216 ATSAs and 533 RTSAs were performed using preoperative planning and intraoperative navigation with a minimum of 2-year follow-up. Matched cohorts (2:1) for age, gender, and follow-up for cases without intraoperative navigation were compared using all standard shoulder arthroplasty clinical outcome metrics. Two subanalyses were performed on navigated cases comparing glenoids positioned greater or less than 10° of retroversion and glenoids corrected more or less than 15°. RESULTS: For ASTA, no statistical differences were found between the navigated and non-navigated cohorts for postoperative complications, glenoid implant loosening, or revision rate. No significant differences were seen in any of the ATSA outcome metrics besides higher internal and external rotation in the navigated cohort. For RTSA, the navigated cohort showed an ARR of 1.7% (95% CI 0%, 3.4%) for postoperative complications and 0.7% (95% CI 0.1%, 1.2%) for dislocations. No difference was found in the revision rate, glenoid implant loosening, acromial stress fracture rates, or scapular notching. Navigated RTSA patients demonstrated significant improvements over non-navigated patients in internal rotation, external rotation, maximum lifting weight, the Simple Shoulder Test (SST), Constant, and Shoulder Arthroplasty Smart (SAS) scores. For the navigated subcohorts, ATSA cases with a higher degree of final retroversion showed significant improvement in pain, Constant, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), SST, University of California-Los Angeles shoulder score (UCLA), and Shoulder Pain and Disability Index (SPADI) scores. No significant differences were found in the RTSA subcohort. Higher degrees of version correction showed improvement in external rotation, SST, and Constant scores for ATSA and forward elevation, internal rotation, pain, SST, Constant, ASES, UCLA, SPADI, and SAS scores for RTSA. CONCLUSION: The use of intraoperative navigation shoulder arthroplasty is safe, produces at least equally good outcomes at 2 years as standard instrumentation does without any increased risk of complications. The effect of final implant position above or below 10° of glenoid retroversion and correction more or less than 15° does not negatively impact outcomes.

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.

Humeral head sizing using extra-articular landmarks on conventional radiographs.

PURPOSE: Proper humeral head (HH) sizing is critical to success in anatomic shoulder replacement for management of glenohumeral arthritis. In this study, we evaluate the accuracy and reliability of using non-articular landmarks on conventional radiographs for HH templating. METHODS: Anatomic HH replacement was performed on five non-arthritic shoulders, from fresh adult cadavers. Pre-operative and post-operative radiographs and 3-D CT scans were obtained. Humeral head size was determined using the articular surface and three extra-articular landmarks (inner aspect of the lateral cortex, the medial footprint of the rotator cuff, and the medial calcar). Two independent observers performed each measurement twice to evaluate reliability. The accuracy was assessed by subtracting the mean values from both the 3D-CT and the implanted HH size measurements. RESULTS: Intraclass correlation coefficient for Observer 1 and 2 for the three-point method showed excellent test-retest reliability 0.996 (95% CI 0.994-0.998) and 0.997 (95% CI 0.995-0.998), respectively. Inter-observer ICC for the three-point method was 0.996 (95% CI 0.994-0.997) showing high level of precision. The three-point method was overestimating the size of the HH (to 3D-CT) with 0.46 ± 0.61 mm on average. The three-point method predicted the size of the HH within 1 mm of the implanted head size showing very high accuracy. The center of rotation (COR) for the three-point method was within 1.34 mm of the (COR) of the articular surface. CONCLUSION: The three-point measuring technique using conventional radiographs may be useful to predict the HH size using extra-articular landmarks within a small margin of error. This method is simple, cost effective and has high level of precision. LEVEL OF EVIDENCE: Basic Science Study; Anatomic and Imaging Study.

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.

Radiographic assessment of prosthetic humeral head size after anatomic shoulder arthroplasty.

BACKGROUND: Restoring the premorbid proximal humeral anatomy during shoulder arthroplasty is critical yet can be difficult because of the deformity of the arthritic head. The purpose of this study was to measure the variation between surgeons and between types of prosthetics in reproducing the anatomic center of rotation (COR) of the humeral head after anatomic shoulder arthroplasty. METHODS: The anteroposterior radiographs of 125 stemmed and 43 resurfacing shoulder arthroplasties, performed by 5 experienced surgeons, were analyzed. All patients had primary replacement for treatment of end-stage glenohumeral arthritis. A best-fit circle to preserved nonarticular humeral landmarks was used to define the difference between the anatomic COR and the prosthetic COR. A difference in COR of >3.0 mm was considered clinically significant and analyzed for the cause of this deviation. RESULTS: The average deviation of the postoperative COR from the anatomic COR was 2.5 ± 1.6 mm for stemmed cases and 3.8 ± 2.1 mm for resurfacings. Thirty-nine stemmed cases (31.2%) and 28 resurfacings (65.1%) were beyond 3.0 mm of deviation and regarded as outliers. The majority of the stemmed outliers and all resurfacing outliers were overstuffed. An improper humeral head size selection and inadequate reaming were the main reasons for the deviation in stemmed and resurfacing outliers, respectively. CONCLUSION: A large percentage of shoulder replacements demonstrated significant deviations from an anatomic reconstruction. Resurfacing arthroplasty exhibited significantly greater deviations compared with stemmed arthroplasty (P < .001), indicating that surgeons have more difficulty in restoring the anatomy with resurfacings. Further studies are needed to assess the clinical impact of these deviations.

Determination of humeral head size in anatomic shoulder replacement for glenohumeral osteoarthritis.

BACKGROUND: We hypothesized that a sphere mapped to specific preserved nonarticular landmarks of the proximal humerus can accurately predict native humeral head radius of curvature (ROC) and head height (HH) in the osteoarthritic, deformed humeral head. METHODS: Three consistent nonarticular landmarks were defined with a 3-dimensional sphere (and 2-dimensional circle in midcoronal plane) placed along the articular surface in 31 normal cadaveric humeri. Side-to-side differences in ROC and HH were determined in 22 pairs of normal shoulders. Using the nonarticular landmarks and sphere method, 3 independent blinded observers performed 2 sets of measurements in 22 pairs of shoulders with unilateral glenohumeral osteoarthritis. The predicted native ROC and HH in the pathologic shoulder were compared with the normal side control. RESULTS: The mean side-to-side difference in normal shoulders was 0.2 mm (ROC) and 0.6 mm (HH). In the unilateral osteoarthritis cases, the intraobserver mean differences for the normal side were 0.3 mm (ROC) and 0.9 mm (HH). The pathologic side ROC and HH, defined by the sphere, exhibited intraobserver differences of 0.5 mm (ROC) and 1.0 mm (HH). The mean side-to-side differences between the normal and pathologic sides were 0.5 mm (ROC) with concordance correlation coefficient of 0.95 and 1.3 mm (HH) with concordance correlation coefficient of 0.66. CONCLUSION: A sphere mapped to preserved nonarticular bone landmarks can be used for accurate preoperative measurement of premorbid humeral head size and therefore the selection of an anatomically sized prosthetic head. This is applicable postoperatively, as is a circle method for 2-dimensional assessment of anatomic humeral reconstruction in the coronal plane.