Factors affecting stress shielding and osteolysis after reverse shoulder arthroplasty: A multicenter study in a Japanese population.

BACKGROUND: Stress shielding and osteolysis around the humeral stem after reverse shoulder arthroplasty causes loosening and periprosthetic fractures and reduces bone stock during revision surgery. In Japanese patients, who have relatively small bodies, different characteristics may exist regarding the occurrence of these changes compared with the characteristics of Westerners, who have relatively larger frames. The purpose of this multicenter study was to investigate the incidence and clarify the predictors of stress shielding and osteolysis in Japanese individuals who underwent reverse shoulder arthroplasty. METHODS: The occurrence of stress shielding and osteolysis was investigated in 135 shoulders that had undergone reverse shoulder arthroplasty at least 2 years prior in five Japanese hospitals. During post-surgical follow-up, which was conducted every 3 months, the locations of the stress shielding occurrences, such as cortical thinning and osteopenia (which primarily occurred in zones 1, 2, and 7, where 1 is the greater tuberosity and 7 is the calcar part), spot weld, and condensation lines, were recorded. Cases without any abnormal findings on radiographs obtained up to ≥2 years after surgery were regarded as having no abnormalities. Finally, the predictors of cortical thinning and proximal humeral osteolysis were assessed using univariate and multivariate regression analyses. RESULTS: Cortical thinning and osteopenia occurred in 68 shoulders, a condensation line occurred in 37 shoulders, and spot weld occurred in 23 shoulders. In particular, greater tuberosity and calcar osteolysis occurred in 40 and 47 shoulders, respectively. Long stem, cementless stem, and a larger proximal filling ratio were independent predictors of cortical thinning and osteopenia, whereas a cementless stem, larger metaphysis diameter, and a larger proximal filling ratio were associated with proximal humeral osteolysis. CONCLUSIONS: The predictors of stress shielding and osteolysis included the use of long stems, cementless stems, larger proximal filling ratios, and larger metaphysis diameters. LEVEL OF EVIDENCE: retrospective comparative study (Level III).

Monitoring of progression of nonsurgically treated rotator cuff tears by magnetic resonance imaging.

BACKGROUND: Nonsurgically treated rotator cuff tears sometimes become irreparable in the lead up to surgical repair. The purposes of our study were to identify predictive factors in the progression of tear size, and determine the changes in tear location. METHODS: Eighty shoulders from 71 patients (mean age 69.4 years) diagnosed with rotator cuff tears by MRI were treated nonsurgically. MRI was repeated after more than 1 year of initial diagnosis. Tear size was measured from the edge of the tear to the lateral aspect of the greater tuberosity. Tears were classified into 5 groups based on tear size and 4 groups based on tear location. Changes in tear size and location were examined. RESULTS: The mean follow-up period was 22.3 months. The average progression of tear size was 5 mm during follow-up, averaging 3 mm per year. Tears that were initially <1 or ≥4 cm were unlikely to progress in tear size. On the other hand, 1- to 2-cm tears on the initial MRI exhibited the greatest progression in tear size, followed by 2- to 3-cm tears. Furthermore, 62.5 % of localized tears in the posterior of the superior facet spread anteriorly, whereas 88.9 % of localized tears in the anterior of the superior facet did not change. CONCLUSIONS: Medium-sized tears are at high risk of tear progression. In contrast, there is little risk of early development of irreparable damage in partial tear or small full-thickness tears. In addition, typical tears may start in the posterior of the superior facet, and subsequently spread anteriorly. Our present findings may serve as a useful reference in determining the treatment course for rotator cuff tears. LEVEL OF EVIDENCE: Level IV, Case Series, Prognosis Study.

Arthroscopic Hip Capsular Repair Improves Patient-Reported Outcome Measures and Is Associated With a Decreased Risk of Revision Surgery and Conversion to Total Hip Arthroplasty.

Purpose: To perform a systematic review to assess the effect of capsular repair compared with nonrepair on patient-reported outcome measures (PROMs) and conversion to total hip arthroplasty (THA) after hip arthroscopy in patients with femoroacetabular impingement syndrome. Methods: We initially searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, and PubMed databases, as well as ongoing clinical trials (https://clinicaltrials.gov), on December 15, 2022. The eligibility criteria were randomized controlled trials (Level Ⅰ) and prospective comparative studies (Level II) of patients who underwent capsular repair and nonrepair via hip arthroscopy with a minimum follow-up period of 2 years. We registered this protocol a priori on PROSPERO (identification No. CRD42021239306). We assessed the risk of bias using the Methodological Index for Non-randomized Studies (MINORS) appraisal tool. Results: This review included 5 studies with a total of 639 patients (270 with capsular repair [average age, 35.4 years; 41% female patients] and 369 with nonrepair [average age, 37.3 years; 38% female patients]). In the included studies, surgical procedures consisting of labral repair and pincer or cam osteoplasty were performed via hip arthroscopy. The modified Harris Hip Score was measured in all the included studies, and the standardized mean difference in PROMs for capsular repair versus nonrepair in the included studies was 0.42 (95% confidence interval [CI], 0.20 to 0.63). A sensitivity analysis of randomized controlled trials achieved consistent results (standardized mean difference in PROMs, 0.31; 95% CI, 0.02 to 0.60). Capsular repair was not associated with a reduction in revision surgery (risk difference, -0.02; 95% CI, -0.06 to 0.03; 26 of 270 patients with capsular repair vs 42 of 369 with nonrepair) but was associated with a reduction in conversion to THA (risk difference, -0.05; 95% CI -0.09 to -0.01; 12 of 270 patients with capsular repair vs 38 of 369 with nonrepair). The average Methodological Index for Non-randomized Studies (MINORS) score in the included studies was 20. Conclusions: Patients who undergo capsular repair in conjunction with other arthroscopic hip preservation techniques have better PROMs and a lower incidence of THA conversion. Level of Evidence: Level II, systematic review of Level I and II investigations.