Purpose. The purpose of this study was to compare the accuracy of the conventional method for determining the percentage of partial thickness rotator cuff tears to a method using an intra-articular depth guide. The clinical utility of the intra-articular depth guide was also examined. Methods. Partial rotator cuff tears were created in cadaveric shoulders. Exposed footprint, total tendon thickness, and percentage of tendon thickness torn were determined using both techniques. The results from the conventional and intra-articular depth guide methods were correlated with the true anatomic measurements. Thirty-two patients were evaluated in the clinical study. Results. Estimates of total tendon thickness (r = 0.41, P = 0.31) or percentage of thickness tears (r = 0.67, P = 0.07) using the conventional method did not correlate well with true tendon thickness. Using the intra-articular depth guide, estimates of exposed footprint (r = 0.92, P = 0.001), total tendon thickness (r = 0.96, P = 0.0001), and percentage of tendon thickness torn (r = 0.88, P = 0.004) correlated with true anatomic measurements. Seven of 32 patients had their treatment plan altered based on the measurements made by the intra-articular depth guide. Conclusions. The intra-articular depth guide appeared to better correlate with true anatomic measurements. It may be useful during the evaluation and development of treatment plans for partial thickness articular surface rotator cuff tears. 1. Introduction Rotator cuff tears are a common cause of pain and disability in the adult shoulder , and surgery for the rotator cuff is one of the most common procedures performed in the shoulder. Rotator cuff tears may be divided into partial thickness tears and full thickness tears. Full-thickness tears involve complete disruption of the tendon thickness and are commonly treated with open or arthroscopic rotator cuff repair . In clinical and cadaveric studies, partial thickness tears are approximately twice as common (6–39% incidence) as full-thickness tears [2–5]. These tears involve only partial disruption of the tendon thickness, and a portion of the tendon insertion remains intact on its footprint. Codman  first described partial thickness tears over seventy-five years ago. However, it was not until the development of arthroscopy that partial thickness tears became a commonly diagnosed and treated condition [2, 4, 5]. It is generally believed that the extent of partial thickness tearing correlates with the severity of symptoms [3, 5]. Articular surface tears are commonly agerelated and may
O. R. McConville and J. P. Iannotti, “Partial-thickness tears of the rotator cuff: evaluation and management.,” The Journal of the American Academy of Orthopaedic Surgeons, vol. 7, no. 1, pp. 32–43, 1999.
S. C. Weber, “Arthroscopic debridement and acromioplasty versus mini-open repair in the management of significant partial-thickness tears of the rotator cuff,” Orthopedic Clinics of North America, vol. 28, no. 1, pp. 79–82, 1997.