Preoperative serum vitamin D deficiency is associated with increased rotator cuff fatty degeneration but is unlikely to influence post repair outcomes: a systematic review and meta-analysis of correlation coefficients.

Background: Vitamin D deficiency is prevalent among the older generation who are also prone to developing degenerative rotator cuff tears. Vitamin D is found to be critical in tendon-to-bone healing and is potentially a modifiable risk factor for arthroscopic rotator cuff repair (RCR) outcomes. However, there are few studies evaluating the effects of vitamin D levels on the latter. This study thus aims to evaluate the relationship between preoperative serum vitamin D levels and rotator cuff tears as well as arthroscopic RCR outcomes. Methods: A systematic search of four databases (PubMed, EMBASE, Scopus, and Cochrane Library) was performed. The inclusion criteria were studies with (a) preoperative serum vitamin D levels, (b) patients who underwent arthroscopic RCR, and (c) preoperative characteristics and postoperative outcomes. Meta-analysis of correlation coefficients was performed to compare the relationship between vitamin D levels and preoperative factors, including (a) fatty degeneration (FD) of supraspinatus and (b) tear size and retraction size, as well as postoperative outcomes, including (a) patient-reported outcome measures and (b) retear rates or failure requiring revision surgery. Results: Five articles were included with a sample size of 1436. The pooled mean serum vitamin D level was 23.66 ng/ml. Higher vitamin D levels were significantly associated with lower FD (R = -0.24, Conclusion: While higher vitamin D levels are associated with lower rates of rotator cuff FD and possible lower retear rates, it does not necessarily lead to better clinical outcomes post-repair. This study's findings do not justify routine testing and supplementation of vitamin D in patients undergoing RCR.