Complications Of Reverse Shoulder Arthroplasty Research Articles

Predictive factors of scapular notching in patients with reverse shoulder arthroplasty

IntroductionThe main complication of reverse shoulder arthroplasty is the development of notches in the scapular pillar, which occurs in 44% to 100% of cases. Furthermore the functional score has been shown to be poorer in patients with high-grade notches. Many options have been proposed to reduce this risk. The purpose of this study was to evaluate the predictive factors of the development of scapular notches. Materials and methodsWe retrospectively evaluated 133 shoulders in 121 patients with reverse shoulder arthroplasty. We performed a radiographic assessment of the effect of positioning the glenoid component with inferior overhang of the glenosphere and the glenometaphyseal angle. All patients were reviewed after 2years follow-up, including a clinical assessment based on the Constant score and X-rays to assess the presence of notches. ResultsNineteen complications were reported, and 14 required revision surgery. We excluded patients in whom prosthetic components were changed. The quality of the X-rays was not satisfactory enough to be analyzed in over 15 patients so they were excluded. One hundred five patients were reviewed. At 2years follow-up, 50.4% of shoulders presented with notches. The Constant score was 69.3 points (54–83) in shoulders without notches, and 66.4 points (38–82) in shoulders with notches. The average glenosphere overhang was 3.5mm (−1 – 8mm). Notches were present in 65.5% if it was less than 3mm and 39.6% if it was more than 2mm (P<0. 05). The average glenometaphyseal angle was 27.3° (4–59°), and notches developed in 72.2% if it was more than 28° and 26.5% if it was less than 28° (P<0.05). ConclusionThe position of the metaglene influences the development of notches. The risk decreases if the glenosphere overhangs the glenoid. The degree of adduction of the arm influences the development of notches and can be correlated with the patient's BMI. Level of evidenceLevel IV retrospective study.

The impact of scapular notching on reverse shoulder glenoid fixation

Scapular notching is a well-documented complication of reverse shoulder arthroplasty. The effect of scapular notching on glenoid fixation is unknown. This study dynamically evaluated reverse shoulder glenoid baseplate fixation and assessed the effect of scapular notching on fixation in composite scapulae. A cyclic test was conducted to simulate 55° of humeral abduction in the scapular plane as a 750-N axial load was continuously applied to induce a variable shear and compressive load. Before and after cyclic loading, a displacement test was conducted to measure glenoid baseplate displacement in the directions of the applied static shear and compressive loads. For the scapulae without a scapular notch, glenoid baseplate displacement did not exceed the generally accepted 150-μm threshold for osseous integration before or after cyclic loading in any component tested. For the scapulae with a scapular notch, glenoid baseplate displacement exceeded 150 μm in 2 of the 7 samples before cyclic loading and in 3 of the 7 samples after cyclic loading. The average pre-cyclic glenoid baseplate displacement in the direction of the shear load was significantly greater in scapulae with a scapular notch than those without a scapular notch both before (P = .003) and after (P = .023) cyclic loading. Adequate glenoid baseplate fixation was achievable in most cases in scapulae with a severe scapular notch; however, the fact that this micromotion threshold was not met in all scapulae with a notch is concerning and implies that severe notching may play a role in initial glenoid baseplate stability.

The relationship between scapular notching and reverse shoulder arthroplasty prosthesis design

Inferior scapular notching is a common radiographic complication of reverse shoulder arthroplasty. The purpose of this study is to determine the impact of prosthesis design on the incidence and severity of notching. Eighty-eight patients (mean age, 72 years) who underwent reverse shoulder arthroplasty with a minimum of 12 months' follow-up (mean, 31 months) were retrospectively reviewed. Patients were grouped based on prosthesis design: Tornier (Stafford, TX, USA) (45%), Zimmer (Warsaw, IN, USA) with a nonretentive liner (35%), and Zimmer with a retentive liner (19%). Notching on final radiographs was graded by use of the Sirveaux classification system and a novel classification system. The incidence of notching was significantly higher with the Tornier prosthesis (92%) compared with the Zimmer prosthesis with nonretentive liners (58%) and retentive liners (71%) (P < .05). The incidence of high-grade notching and the median grade were significantly higher with the Tornier prosthesis compared with the Zimmer prosthesis (P < .05). By use of the novel grading system, there was a higher incidence of notching involving the baseplate with the Tornier prosthesis (68%) compared with the Zimmer prosthesis (33%) (P < .05). The addition of a retentive liner was not associated with greater notching than a nonretentive liner for the Zimmer implant. Diagnosis had no significant influence on notching. A higher incidence and severity of notching were observed with the Tornier reverse arthroplasty compared with the Zimmer reverse arthroplasty at short-term follow-up. These findings may be because of the different morphology of the polyethylene component and/or differences in glenosphere offset between the prosthetic systems. In addition to surgical technique, consideration should be given to prosthesis design in mitigating the risk of scapular notching.

Scapular Spine Stress Fracture as a Complication of Reverse Shoulder Arthroplasty

Scapular Spine Stress Fracture as a Complication of Reverse Shoulder Arthroplasty