Supine Knee Positioning Does Not Interfere with Mobile-Bearing Unicompartmental Knee Arthroplasty Performance.

The Food and Drug Administration has only approved mobile-bearing unicompartmental knee arthroplasty (MB-UKA) to be performed with a hanging leg holder. The purpose of this study is to evaluate the impact of a supine knee position on MB-UKA performance.In total, 16 cadavers were randomized so that either the right or left knee was placed in the flexed or supine positions. One board-certified orthopaedic surgeon and three adult reconstruction fellows that attended the required Oxford partial knee instructional course performed four operations in each position. The primary outcome was final knee balance. Secondary outcomes included procedure duration, timing of individual surgical steps, implant sizes, range of motion, implant alignment, and fracture. A Students t-test was used to examine differences between positions with significance set at p < 0.05. Secondary analyses using two one-sided tests were conducted to explore equivalence between the two positions.There was no significant difference in mean final balance between supine (1.7 mm ± standard deviation [SD] = 1.5 mm) and flexed (1.3 ± 1.3 mm) positions (p = 0.390). There were also no significant differences between positions for procedure time (p = 0.497), tibia coronal alignment (p = 0.614), tibial slope (p = 0.194), femoral component sagittal alignment (p = 0.091), and fractures (n = 0). Exploratory equivalence analyses indicated that the positions were equivalent for final balance (p = 0.002).MB-UKA performed in the supine position is not significantly different from the flexed position in terms of ligament balance, overall procedure time, and radiographic appearance. These initial safety data warrant further clinical investigations and support the expansion of the surgical technique to include performing MB-UKAs in the supine position.

Malunions and Nonunions of the Acromion and Coracoid Proceses: A Comparison of Functional Outcomes Before and After Reconstruction.

OBJECTIVES: To assess surgical and functional outcomes in a cohort of patients having operatively reconstructed scapula process malunions and/or nonunions. DESIGN: Retrospective case series. SETTING: Level I trauma center. PATIENTS/PARTICIPANTS: Between 2003 and 2018, we identified 16 patients who presented to our institution with symptoms associated with a nonunion or malunion of closed, displaced fractures of the scapula processes after acute injury mechanisms. INTERVENTION: Surgical osteotomy of the malunion or debridement of the nonunion and subsequent reconstruction. MAIN OUTCOME MEASUREMENTS: The primary outcome measured included range of motion, strength, and DASH. Return to work was a secondary outcome. RESULTS: Among 13 of the 16 (81%) patients with ≥12 months follow-up, the mean follow-up was 34 months (range, 12-112 months). Three patients were lost to follow-up. The mean DASH score improved from 56.4 ± 22.4 preoperatively to 23.4 ± 22.2 postoperatively (P < 0.001). Among the patients with ≥1-year follow-up, range of motion improved from preoperative to final follow-up in abduction (P = 0.020). Among the 15 of 16 patients for whom occupation data are available, 73% either returned to their original occupation (n = 7) or did not due to reasons other than their reconstructive surgery (n = 4). Two postoperative complications occurred including failure of acromion nonunion fixation at 4 months and went on to heal after revision surgery. All reconstructions united without malunion. CONCLUSIONS: Reconstruction of the scapula process malunion and nonunion is possible, providing restoration of function and symptom relief, with a low complication rate. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Invagination of elevated lip liner preventing reduction of dislocated total hip.

Instability is the most common indication for revision total hip arthroplasty in the United States. Elevated-rim acetabular liners were introduced to minimize the risk of posterior instability. We describe a patient with multiple total hip arthroplasty dislocations secondary to component subsidence leading to instability. As the patient initially refused revision of his femoral component, he was treated with an elevated-rim acetabular liner. When this too dislocated, the hip could not be reduced concentrically. During operative exposure for a stem revision, the lipped aspect of the liner was found to have folded into the acetabulum thus preventing concentric reduction of the head. We conclude that invagination of the elevated lip of a polyethylene liner should be considered when concentric reduction of a dislocated hip proves difficult.