Does the Upward Migration Index Predict Function and Quality of Life in Arthroscopic Rotator Cuff Repair?

Abstract

Although upward humeral head migration is a well-recognized phenomenon in patients with tears of the cuff, it is unclear whether it relates to patient function after cuff repair. The upward migration index (UMI) assesses proximal migration of the humeral head while controlling for patients' bony morphologic features. We asked whether functional and quality-of-life (QOL) improvement occurs longitudinally in patients with low, moderate, or high degrees of proximal humeral migration after arthroscopic cuff repair and whether differences occur between groups. We retrospectively reviewed 118 patients with full-thickness tears treated by arthroscopic cuff repair. Patients were divided into three groups depending on the severity of preoperative proximal humeral migration seen on MRI. We determined function using two functional scores and the Western Ontario Rotator Cuff Index (a QOL index). Evaluations were performed preoperatively and 6 and 12 months postoperatively. A general linear model analysis controlled for patient characteristics, including the UMI, to determine their effects on functional and QOL scores. Function and QOL improved after surgery in all three groups. The UMI did not correlate with final functional or QOL scores. Six-month functional and QOL scores correlated with final scores. The best predictor of final strength was initial strength. Preoperative UMI did not correlate with functional or QOL improvements after surgery. The data suggest substantial proximal migration of the humeral head, as measured by the UMI, should not be considered a contraindication to arthroscopic rotator cuff repair.