Summary

In a consecutive series of rotator cuff repairs, there was a significant effect of time on tear size progression from preoperative MRI dimensions to actual tear dimensions at time of repair.

Abstract

Background

Magnetic resonance imaging (MRI) is the advanced imaging modality of choice for the evaluation and diagnosis of full thickness rotator cuff tears (RCT). Tear size progression has been correlated with increasing pain. The purpose of the study was to evaluate the effect of time (from date of MRI measured tear dimensions to date of RCR measured intraoperative tear dimensions) on tear size progression.

Methods

In the course of a study on physical examination manual muscle tests in patients with known full thickness RCT requiring repair, MRI was obtained for each patient. Tears were measured intraoperatively in the Anterior-Posterior (A-P) and Medial-Lateral (M-L) dimensions with a graduated probe. Location (anterior, central, posterior in the supraspinatus tendon), area of the tear, and anterior band of supraspinatus status (intact/ not intact) were recorded. The preoperative MRI was evaluated by the same examiner blinded to the operative results at least 4 weeks after the RCR and the same parameters measured. There were 64 consecutive shoulders with 40 male, 24 female at an average age of 58 yrs (40-76) that had MRI and underwent RCR. The mean MRI dimensions were: A-P tear: 16.53mm (SD 9.70); M-L tear: 17.3mm (SD 9.75); Tear area: 366.7 square mm. The average time from preoperative MRI to RCR was 107.3 days (range 12-399 days). Operative mean RCT dimensions were: A-P tear: 18.38mm (SD 10.0); M-L tear: 14.06mm (SD 8.15); Tear area: 307.7 square mm. Descriptive statistical analysis with two-sample T-test was performed to determine the temporal effect on tear size from date of MRI to the date of surgery, and whether there was a change. Patients were grouped in the following time cohorts based on the length of time elapsed between the preoperative MRI and date of RCR: less than 1 month, 1-2 months, 2-3 months, 3-9 months, and greater than 9 months. The delta, or difference between intraoperative measurements and preoperative MRI measurements, was calculated for each cohort.

Results

There was a significant time effect on tear size between the MRI and intraoperative measured tears requiring repair [A-P (p<0.001), M-L (p<0.001), total area (p=0.009)]. In an attempt to determine a “watershed” or critical time interval where MRI and RCT size correlated, an additional analysis was performed. The change in A-P tear dimension between MRI and RCR findings showed increasing delta with increasing time. Positive mean delta in A-P dimension was seen in the 2-3 month group (2.64), with larger differences seen in the 3-9 month (5.89) and greater than 9 month (7.3) groups. A similar trend was seen for mean delta values in the M-L dimension among the cohorts.

Conclusions

In a consecutive series of RCTs undergoing repair, the measured MRI dimensions and the intraoperative dimensions were recorded and analyzed. A surgeon can have a level of confidence that the RCT size will correlate with MRI tear size within a certain time frame. There is a significant effect of time on tear size progression from MRI dimensions to actual RCT dimensions at time of repair.