New Insights Into Rotator Cuff Repair Efficacy

A research team at Rush University School of Medicine collected data from 12 cadaveric shoulders at 0°, 45°, and 90° abduction under five conditions:

1. intact rotator cuff/superior capsule,
2. rotator cuff section first,
3. superior capsule sectioned first,
4. both structures sectioned and
5. rotator cuff repair.

Why did they do this and what did they learn? They organized this study because, as they wrote in their paper, “Individual contributions of the rotator cuff and superior capsule to prevent superior translation of the humerus are not well understood.”

The answers they obtained are detailed in their paper, “Biomechanical Role of the Superior Capsule in a Rotator Cuff Sectioned and Repaired State: A Sequential Sectioning Study,” was published online on March 24, 2022, in The American Journal of Sports Medicine.

The Rush team collected data on the relative contributions of the superior capsule and rotator cuff repair to normal and pathologic shoulder biomechanics and looked at their independent effects on superior humeral translation.

The team randomly assigned matched pairs of cadaveric shoulders to their rotator cuff sectioned first or superior capsule sectioned first. All shoulders were tested under 2 static conditions, either 40-N deltoid load or 80-N deltoid load and 1 dynamic condition during active abduction.

The researchers found that during balanced deltoid loading at 0° and 45°, there was greater humeral translation when both structures were sectioned compared with the intact state and with both isolated sectioned states (p < .05 for all). There were no significant differences observed between or within groups at 90° of abduction. All these effects remained with superiorly directed loading.

In addition, dynamic testing of both groups showed a significant increase in superior translation for shoulders in which the rotator cuff was deficient versus the intact state (p = .027), with no difference when the superior capsule was sectioned.

The rotator cuff repair state returned translation to values similar to the intact state at all abduction angles and loading conditions (p > .05).

“In this cadaveric study, the superior capsule and rotator cuff played an important role in preventing superior humeral translation; however, dynamic testing suggested preferential contribution of the rotator cuff. Rotator cuff repair was effective in preventing superior humeral translation, even with a sectioned superior capsule at the level of the glenohumeral joint,” the researchers wrote.

“Rotator cuff repair was effective in preventing superior humeral translation, even in the presence of a sectioned superior capsule at the level of the glenohumeral joint in this cadaveric model. Our data lay the groundwork for future studies investigating the clinical effect of rotator cuff repair in a superior capsule sectioned state.”

The study authors include Steven F. DeFroda, M.D., MEng, Allison K. Perry, BS, Nabil Mehta, M.D., Johnathon R. McCormick, M.D., Ian M. Clapp, M.D., M.S., Grant E. Garrigues, M.D., and Nikhil N. Verma, M.D., all at Midwest Orthopaedics at Rush University. Muturi G. Muriuki, Ph.D., and Robert M. Havey, MS, of Edwards Hines Jr. VA Hospital in Hines, Illinois also contributed to the study.