This paper compares the frontal plane hip function of subject’s known to have had hip arthroplasty via either the lateral (LA) or posterior (PA) surgical approaches and a group of subjects associated with no pathology (NP). This is investigated through the Trendelenburg test using 3D motion analysis and classification. Here, a recent development on the Classification and Ranking Belief Simplex (CaRBS) technique, able to undertake n-state classification, so termed NCaRBS is employed. The relationship between post-operative hip function measured during a Trendelenburg Test using three patient characteristics (pelvic obliquity, frontal plane hip moment and frontal plane hip power) of LA, PA and NP subjects are modelled together. Using these characteristics, the classification accuracy was 93.75% for NP, 57.14% for LA, 38.46% for PA. There was a clear distinction between NP and post-surgical function. 3/6 LA subjects and 6/8 PA subjects were misclassified as having NP function, implying that greater function is restored following the PA to surgery. NCaRBS achieved a higher accuracy (65.116%) than through a linear discriminant analysis (48.837%). A Neural Network with two-nodes achieved the same accuracy (65.116%) and as expected was further improved with three-nodes (69.767%). A valuable benefit to the employment of the NCaRBS technique is the graphical exposition of the contribution of patient characteristics to the classification analysis.
C. Benjamin Ma, MD, Weiyuan Xiao, MD, Madeleine Salesky, AB, Edward Cheung, MD, Alan L. Zhang, MD, Brian T. Feeley, MD, and Drew A. Lansdown, MD∗Shoulder
Background
Glenoid retroversion and humeral head subluxation have been suggested to lead to inferior outcomes after total shoulder arthroplasty (TSA). There are limited data to support this suggestion. We investigated whether preoperative glenoid retroversion and humeral head subluxation are associated with inferior outcomes after TSA and whether change of retroversion influences outcomes after TSA.
Methods
Patients undergoing TSA with minimum 2-year follow-up were included from a prospectively collected institutional shoulder arthroplasty database. Retroversion and humeral head subluxation before and after surgery were measured on axillary radiographs. Postoperative radiographs were -evaluated for glenoid component loosening and compared between groups. Spearman correlations were determined between retroversion measurements and American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) scores. Patients were analyzed in groups based on retroversion and humeral head subluxation.
Results
There were 113 patients (50% follow-up rate) evaluated at 4.2 years postoperatively. The mean preoperative retroversion (15.3° ± 7.7°) was significantly higher than postoperative retroversion (10.0° ± 6.8°; P < .0001). There was no correlation between postoperative glenoid version or humeral head subluxation and ASES scores. For patients with preoperative retroversion of >15°, there was no difference in outcome scores based on postoperative retroversion. There were no differences in preoperative or postoperative version for patients with or without glenoid lucencies.
Discussion
We observed no significant relationship between postoperative glenoid retroversion or humeral head subluxation and clinical outcomes in patients following TSA. For patients with preoperative retroversion >15°, change of retroversion during TSA had no impact on their clinical outcomes at short-term follow-up.
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