Abstract
Introduction
The clinical impact of scapular notching is controversial. Some reports suggest it has no impact while others have demonstrated it does negatively impact clinical outcomes. The goal of this clinical study is to analyze the pre- and post-operative outcomes of 415 patients who received rTSA with one specific prosthesis (Equinoxe; Exactech, Inc).
Methods
415 patients (mean age: 72.2yrs) with 2 years minimum follow-up were treated with rTSA for CTA, RCT, and OA by 8 fellowship trained orthopaedic surgeons. 363 patients were deemed to not have a scapular notch by the implanting surgeon at latest follow-up (72.1 yrs; 221F/131M) whereas 52 patients were deemed to have a scapular notch at latest follow-up (73.3 yrs; 33F/19M). Outcomes were scored using SST, UCLA, ASES, Constant, and SPADI metrics; active abduction, forward flexion, and internal/external rotation were also measured to quantify function. Average follow-up was 38.1 months (No Notch: 37.2; Notch: 44.4). A two-tailed, unpaired t-test identified differences (p<0.05) in pre-operative, post-operative, and pre-to-post improvements.
Results
The overall scapular notching rate was 12.5%. The rTSA cohort with a scapular notch had an average notching grade of 1.3 (41 grade 1, 6 grade 2, 5 grade 3, and 0 grade 4 notches). rTSA patients with a scapular notch on average weighed significantly less (168.0 vs. 154.7 lbs; p = 0.016) and had a significantly lower BMI (27.3 vs. 26.0; p = 0.032). 8 patients without scapular notching had a radiolucent line around the humeral component (2.2%); whereas, 5 patients with scapular notching had a radiolucent line around the humeral component (10.0%). Table 1 demonstrates no difference between the cohorts in pre-operative outcomes. Table 2 demonstrates rTSA patients without scapular notching were associated with significantly larger clinical outcome scores in all 5 metrics and also had significantly improved function according to 3 of the 6 measurements as compared to rTSA patients with scapular notching. Table 3 demonstrates only one significant difference was observed in pre-to-post improvement of outcome scores between cohorts. Finally, 27 complications were reported (6.5%), 20 for patients without scapular notching (5.5%) and 7 complications for patients with scapular notching (13.5%).
Discussion and Conclusions
This large-scale clinical outcome study demonstrated that patients with scapular notching are associated with significantly poorer outcomes and a greater complication rate than patients without scapular notching at a similar average post-operative follow-up. The finding that patients with lower BMI were associated with a higher notching rate is new but also intuitive as these patients can likely adduct their arm more; it may also be that the lower average BMI and weight suggests that patients with notching were also more active. One additional new finding in this analysis is that patients with scapular notching had a 4.5X greater rate of radiolucent lines around the humeral component suggesting that the UHWMPE wear debris are related to the formation of humeral radiolucent lines. Additional and longer-term follow-up is needed to confirm these conclusions.
