Sunday, January 29, 2017

Shoulder hemiarthroplasty

Risk factors for glenoid erosion in patients with shoulder hemiarthroplasty: an analysis of 118 cases

These authors reviewed radiographs of 118 hemiarthroplasties in 113 patients with a mean follow-up of 31 months (range, 5-86 months).

Attempts in quantifying glenoid erosion by determining several parameters and their change over the postoperative period were made (beta angle, critical shoulder angle, medialization of prosthetic head).

However, the authors concluded that none of them was consistent in quantifying erosion. While the authors obtained preoperative CT scans on almost all shoulders, they did not attempt to use CT scans to evaluate erosion at followup.

Therefore, they graded glenoid erosion on plain films using a system described in 2007 (see this link) as (grade 1) none; (grade 2) mild (erosion into the subchondral bone); (grade 3) moderate (medialization of the glenoid subchondral bone with hemispheric conforming deformation of the glenoid); or (grade 4) severe (complete hemispheric deformation of the glenoid with superior bone loss to the base of the coracoid base).

In this series, erosion after hemiarthroplasty was associated with glenoid cysts, loss of glenoid cartilage, rotator cuff degeneration, female sex, rheumatoid arthritis, and implantation of the prosthetic head in a valgus position. The relationship of radiographic estimates of erosion to the clinical outcomes in these patients is not reported.

Comment: These factors are very similar to those affecting clinical outcomes of shoulder hemiarthroplasty as reported thirteen years ago in the article "Preoperative Factors Associated with Improvements in Shoulder Function After Humeral Hemiarthroplasty", the abstract of which is reproduced below;

Background: The relationship between the characteristics of the shoulder that can be determined before humeral hemiarthroplasty and the functional improvement after surgery is not known. The goal of this study was to test the hypothesis that the functional outcome of this procedure correlated significantly with factors that are identifiable preoperatively.

Methods: The study group included seventy-one shoulders in sixty-eight patients undergoing hemiarthroplasty, performed by the same surgeon, for diagnoses other than acute fracture. The mean age of the patients was sixty-one years (range, thirty to eighty-three years). The results were characterized in terms of the change in self-assessed shoulder function and general health status at an average of forty-nine months (range, twenty-four to 142 months) after surgery.

Results: The preoperative absence of erosion of the glenoid was associated with greater improvement in shoulder function and level of comfort after hemiarthroplasty (p < 0.001). Shoulders that had not had previous surgery had greater functional improvement than did those that had previous surgery (p = 0.012). Shoulders with an intact rotator cuff showed significantly (p < 0.5) greater improvement in the ability to lift weight above shoulder level after hemiarthroplasty (p <0.5). With regard to diagnoses, shoulders with rheumatoid arthritis, capsulorrhaphy arthropathy, and cuff tear arthropathy had the least functional improvement, whereas those with osteonecrosis (p = 0.0004) and with primary (p = 0.02) and secondary degenerative joint disease (p = 0.03) had the greatest improvement. Patient age and gender did not significantly affect the outcome.

Conclusions: These results suggest that the functional improvement following humeral hemiarthroplasty is related to factors that are identifiable before surgery. These data may be of benefit in preoperative discussions with patients who have a shoulder disorder and are considering treatment with hemiarthroplasty.


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