Paper 167: Vitamin D Level in the Serum Correlates with Fatty Degeneration of Cuff Muscles in Patients with Rotator Cuff Tear

Abstract

To analyze the relationship between vitamin D (25(OH)D3) level in the serum and the fatty degeneration of the rotator cuff muscles in patients with rotator cuff disorders. Consecutive 366 patients with shoulder disorders underwent magnetic resonance arthrography, and the serum concentrations of vitamin D (25(OH)D3) and intact parathyroid hormone (iPTH) were simultaneously measured. Two hundred twenty eight patients were found to have full-thickness cuff tear (group I) and the remaining 138 were diagnosed as other than full-thickness tear (group II). Data on various factors [full-thickness cuff tear, gender, age, symptom duration, FD of cuff muscles, size and retraction of tear, and abduction and external rotation (ER) torque of the affected and unaffected shoulders as measured by isokinetic muscle performance test] were collected, and finally, stepwise linear regression analysis was performed to identify the factors which account for the FD of cuff muscles. In group I, a lower serum level of 25(OH)D3 was related with female, a higher FD of the supraspinatus (SSP) and infraspinatus (ISP), a higher serum iPTH, lower abduction torque in unaffected shoulder, and lower ER torque of both affected and unaffected shoulder. The Spearman correlation coefficients were −0.22 (p = 0.001), −0.22 (p = 0.001) and −0.10 (p = 0.146) between the serum 25(OH)D3 level and the FD of the SSP, ISP and subscapularis, respectively. Stepwise linear regression analysis revealed that retraction (p < 0.001), the ER torque of the unaffected shoulder (p = 0.001), and serum level of 25(OH)D3 (p = 0.031) were independent variables for the FD of the SSP. In group II, the lower level of serum 25(OH)D3 was related with female, a higher FD of the SSP and ISP, lower abduction and ER torque in the affected and unaffected shoulders. The current study demonstrated the serum vitamin D level has a significant negative correlation with the FD of the torn cuff muscles and a positive correlation with the isokinetic muscle torque. Future study may be needed to confirm the local concentration of vitamin D in the cuff muscles, and whether supplementation with vitamin D affects the functional and anatomical outcomes, and also the improvement of FD after rotator cuff repair.