Abstract
Introduction
Posterior glenoid wear is common with glenohumeral osteoarthritis. To correct posterior wear, surgeons may eccentrically ream the anterior glenoid to restore version. However, eccentric reaming undermines prosthesis support by removing unworn anterior glenoid bone, compromises cement fixation by increasing the likelihood of peg perforation, and medializes the joint line which has implications on joint stability. To conserve bone and preserve the joint line when correcting glenoid version, manufacturers have developed posterior augment glenoids for aTSA and rTSA applications. This clinical study quantifies outcomes achieved using posteriorly augmented aTSA/rTSA glenoid implants in patients with severe posterior glenoid wear at 2 years minimum follow-up.
Methods
47 patients (mean age: 68.7yrs) with 2 years minimum follow-up were treated by 5 fellowship trained orthopaedic surgeons using either 8° posteriorly augmented aTSA/rTSA glenoid components in patients with severe posterior glenoid wear. 24 aTSA patients received posteriorly augmented glenoids (65.8 yrs; 7F/17M) for OA and 23 rTSA patients received posteriorly augmented glenoids (71.8 yrs; 9F/14M) for treatment of CTA and OA. Outcomes were scored using SST, UCLA, ASES, Constant, and SPADI metrics; active abduction, forward flexion, and external rotation were also measured to quantify function. Average follow-up was 27.5 months (aTSA 29.4; rTSA 25.5). A two-tailed, unpaired t-test identified differences (p<0.05) in pre-operative, post-operative, and pre-to-post improvements.
Results
A comparison of pre-operative, post-operative, and pre-to-post improvement in outcomes are presented in Tables 1–3, respectively. As described in Table 1, pre-operative outcomes were similar for patients receiving posterior augment aTSA and posterior augment rTSA implants, with only active abduction being significantly less in rTSA patients. Additionally, rTSA patients were noted to be significantly older (p=0.0434) and have significantly longer follow-up (p=0.0358) though no difference was noted in mean patient height, weight, or BMI between cohorts. As described in Table 2, at 2 years minimum follow-up posterior augment aTSA patients were associated with significantly greater SST scores and also had significantly more active abduction and active external rotation than posterior augment rTSA patients. However, as described in Table 3, no significant difference was observed in pre-to-post improvement of outcome scoring metrics and only improvement in active external rotation was observed to be significantly different between the two cohorts. No complications were reported for either posterior augment implant cohort.
Conclusions
These results demonstrate positive outcomes can be achieved at 2 years minimum follow-up in patients with severe posterior wear using either posteriorly augmented aTSA/rTSA glenoid implants. While relative differences in outcomes were noted, these mean differences are expected due to differing indications and associated differences in rotator cuff status. Due to the aforementioned concerns of aseptic glenoid loosening in patients with severe posterior glenoid wear, some have recommend treating patients with posterior glenoid wear using only rTSA regardless of the status of the patient's rotator cuff. The results of this study demonstrate that patients with posterior glenoid wear and a functioning rotator cuff can be successfully treated with posterior augmented aTSA as well. Additional and longer-term follow-up is needed to confirm these positive outcomes.
