Does glenohumeral offset affect clinical outcomes in a lateralized reverse total shoulder arthroplasty?

BACKGROUND: Reverse total shoulder arthroplasty (rTSA) exhibits high rates of success and low complication rates. rTSA has undergone numerous design adaptations over recent years, and lateralization of implant components provides theoretical and biomechanical benefits in stability and range of motion (ROM) as well as decreased rates of notching. However, the magnitude of implant lateralization and its effect on these outcomes is less well understood. The purpose of this study was to evaluate how increasing glenohumeral offset affects outcomes after rTSA, specifically in a lateralized humerus + medialized glenoid implant model. METHODS: Primary rTSA using a lateralized humeral + medialized glenoid implant model performed at a single academic institution between 2012 and 2018 were retrospectively reviewed. Patient-reported outcome (PRO) parameters and clinical outcomes including ROM were evaluated both pre- and postoperatively. Pre- and postoperative radiographs were analyzed for measurement of glenohumeral offset, defined as the acromial-tuberosity offset (ATO) distance on the anteroposterior radiograph. RESULTS: A total of 130 rTSAs were included in the analysis, with a mean follow-up of 35 mo. The mean postoperative absolute ATO was 16 mm, and the mean delta ATO (difference from pre- to postoperatively) was 4.6 mm further lateralized. Among all study patients, improvements in all ROM parameters and all PROs were observed from pre- to postoperative assessments. When assessing for the effects of lateralization on these outcomes, multivariate analysis failed to reveal a significant effect from the absolute postoperative ATO or the delta ATO on any outcome parameter. CONCLUSIONS: rTSA using a lateralized humeral + medialized glenoid implant model exhibits excellent clinical outcomes in ROM and PROs. However, the magnitude of lateralization as measured radiographically by the ATO did not significantly affect these outcomes; patients exhibited universally good outcomes irrespective of the degree of offset restoration.

The Effect of Screw Design and Cortical Augmentation on Insertional Torque and Compression in Coracoid-Glenoid Fixation in a Sawbones Model.

PURPOSE: To compare screw insertional torque and coracoid-glenoid compression from 4 fixation techniques with different screw design parameters and cortical augmentation for the Latarjet procedure. METHODS: Simulated Latarjet procedures were performed with 4 fixation techniques using laminated polyurethane blocks with dimensions similar to the coracoid-glenoid construct. The groups included DePuy Synthes Mitek 3.5-mm partially threaded screws with top hats, Arthrex 3.75-mm fully threaded screws with a 2-hole plate, Arthrex 3.75-mm fully threaded screws, and Smith & Nephew 4.0-mm partially threaded screws. Screws were inserted using a digital torque-measuring screwdriver to determine maximum insertional torque. Pressure-sensitive film was used to measure the maximum contact pressure and the effective pressure distribution (EPD) between the coracoid and glenoid; the EPD represents the percentage of the film's surface area that experienced pressure greater than 10 MPa. One-way analysis of variance and post hoc tests were used for statistical analysis. RESULTS: Significant differences were found between the 4 fixation groups for each variable measured. The 2 cortically augmented systems produced significantly higher maximum insertional torque than the non-cortically augmented systems (P < .001 for both). The 3.75-mm screws with a 2-hole plate yielded significantly higher contact pressures than the 4.0-mm screws (P = .028). This group also had a high EPD, with a mean value more than double the values of the non-cortically augmented systems (P = .037 and P < .001). CONCLUSIONS: Cortically augmented fixation methods showed higher maximum insertional torque, maximum contact pressure, and EPD between the surfaces of the coracoid and glenoid in this Sawbones model. CLINICAL RELEVANCE: Various implants are available for the Latarjet procedure, but their biomechanical characteristics have not yet been fully elucidated. Graft fracture and nonunion represent 2 modes of failure that may be related to insertional torque and coracoid-glenoid compression. This study compared screw insertional torque and compression achieved using 4 fixation techniques with different screw design parameters and cortical augmentation in a Sawbones model.

Cementless vs Cemented Tibial Fixation in Primary Total Knee Arthroplasty.

BACKGROUND: The ideal fixation for modern tibial components in total knee arthroplasty (TKA) remains controversial with uncertainty on whether cementless implants can yield equivalent outcomes to cemented fixation in early follow-up. METHODS: A series of 70 consecutive cases with reverse hybrid cementless fixation were matched to 70 cemented cases from 2008 to 2015 based on implant design and patient demographics. RESULTS: Cementless TKA demonstrated greater aseptic loosening (7 vs 0, P = .013) and revision surgery (10 vs 0, P = .001) than cemented fixation within 5 years of follow-up, but with no clinically significant differences in outcome scores. CONCLUSION: It remains unclear whether early aseptic loosening in cementless TKA can be reduced with enhanced adjunct fixation and what proportion of early failure justifies the potential lifelong fixation through biologic ingrowth of cementless tibial components.

Comparison of press-fit versus peripherally cemented hybrid glenoid components in anatomic total shoulder arthroplasty: minimum 5-year follow-up.

BACKGROUND: A common complication of anatomic total shoulder arthroplasty (aTSA) is aseptic glenoid loosening. Monoblock polyethylene glenoid components with backside ingrowth or on-growth utilize hybrid fixation, with cementation of the peripheral pegs and central ingrowth or on-growth of bone have been designed to decrease glenoid loosening. However, there is a paucity of midterm data comparing cementation of the peripheral peg holes versus all press-fit implantation for hybrid glenoid constructs. The purpose of this study is to compare the minimum five-year clinical and radiographic outcomes of a press-fit hybrid glenoid component with a peripherally cemented hybrid glenoid component in aTSA. METHODS: Between years 2013-2015, we reviewed a total of 169 patients who underwent primary aTSA, with follow-up data spanning a minimum of five years, from an international multi-institutional database. There were 61 press-fit and 108 peripherally cemented glenoids. Shoulders were evaluated for outcome measures, which included clinical outcome scores, radiographic outcomes, and complication rates. RESULTS: Postoperatively, there were no statistically significant differences in patient satisfaction, shoulder function, pain scoring, the Simple Shoulder Test, the Constant score, the American Shoulder and Elbow Surgeons score, the University of California-Los Angeles score, nor the Shoulder Pain and Disability Index, between the two cohorts. There were no significant differences in adverse events (P = .791) or revision rates (P = .592). At the final radiographic follow-up, there were no significant differences between the two groups with regard to the incidence of radiolucent lines on the glenoid (P = .210) or humeral side (P = .282). CONCLUSION: At a minimum of 5-year follow-up, aTSA with a press-fit glenoid implant demonstrates no difference in clinical or radiographic outcomes when compared with a glenoid cohort where the peripheral pegs are cemented. In addition, there is no increased rate of aseptic glenoid loosening or need for revision surgery between the two groups with a lower rate of radiolucency detected than prior midterm data studies. Uncemented press-fit glenoid fixation with a cage component appears to be a safe and effective treatment option for patients undergoing primary aTSA at a minimum of 5-year follow-up.

Management of Glenoid Bone Loss with Anterior Shoulder Instability: Indications and Outcomes.

PURPOSE OF REVIEW: Glenoid Bone Loss is a commonly encountered problem in anterior shoulder instability. In this article, we review current techniques for diagnosis, indications and management of glenoid bone loss. RECENT FINDINGS: Multiple bone grafting techniques are available depending on the glenoid defect size including the coracoid, distal clavicle, iliac crest, and allograft distal tibia. Advancement in imaging methods allows for more accurate quantification of bone loss. Indications and techniques are continuing to evolve, and emerging evidence suggests that smaller degrees of bone loss "subcritical" may be best treated with bone grafting. Future directions for innovation and investigation include improved arthroscopic techniques and a refinement of indications for the type of bone grafts and when to indicate a patient of arthroscopic repair versus glenoid bone grafting for smaller degrees of bone loss to ensure successful outcome.