A Prospective, Quantitative Evaluation of Fatty Infiltration Before and After Rotator Cuff Repair

Abstract

Background:Current evaluation of muscle fatty infiltration has been limited by subjective classifications. Quantitative fat evaluation through magnetic resonance imaging (MRI) may allow for an improved longitudinal evaluation of the effect of surgical repair on the progression of fatty infiltration.Hypotheses:We hypothesized that (1) patients with isolated full-thickness supraspinatus tendon tears would have less progression in fatty infiltration compared with patients with full-thickness tears of multiple tendons and (2) patients with eventual failed repair would have higher baseline levels of fatty infiltration.Study Design:Cohort study; Level of evidence, 2.Methods:Thirty-five patients with full-thickness rotator cuff tears were followed longitudinally. All patients received a shoulder MRI, including the iterative decomposition of echoes of asymmetric length (IDEAL) sequence for fat measurement, prior to surgical treatment and at 6 months after surgical repair. Fat fractions were recorded for all 4 rotator cuff muscles from measurements on 4 sagittal slices centered at the scapular-Y. Demographics and tear characteristics were recorded. Baseline and follow-up fat fractions were compared for patients with isolated supraspinatus tears versus multitendon tears and for patients with intact repairs versus failed repairs. Statistical significance was set at P < .05.Results:The mean fat fractions were significantly higher at follow-up than at baseline for the supraspinatus (9.8% ± 7.0% vs 8.3% ± 5.7%; P = .025) and infraspinatus (7.4% ± 6.1% vs 5.7% ± 4.4%; P = .027) muscles. Patients with multitendon tears showed no significant change for any rotator cuff muscle after repair. Patients with isolated supraspinatus tears showed a significant progression in the supraspinatus fat fraction from baseline to follow-up (from 6.8% ± 4.9% to 8.6% ± 6.8%; P = .0083). Baseline supraspinatus fat fractions were significantly higher in patients with eventual failed repairs compared with those with intact repairs (11.7% ± 6.8% vs 7.1% ± 4.8%; P = .037).Conclusion:Contrary to our initial hypothesis, patients with isolated supraspinatus tears showed a significant progression of fatty infiltration. Patients with eventual repair failure had higher baseline fat fractions in the supraspinatus.

Rotator Cuff Fibro‐Adipogenic Progenitors Demonstrate Highest Concentration, Proliferative Capacity, and Adipogenic Potential Across Muscle Groups

“…Gladstone et al showed that the degree of FI remained constant or progressed after patients underwent repair and found a positive correlation between the degree of FI and RC retear rates. Multiple other studies have described similar findings regarding FI and its detrimental role in RC tears and functional outcomes …”

Beige FAPs Transplantation Improves Muscle Quality and Shoulder Function After Massive Rotator Cuff Tears

“…FI of RC muscles has major clinical implications as it correlates with shoulder function and is often irreversible in the setting of repair . As such, methods to reduce or diminish adipogenesis following RC tears are critical.…”

“…Although tears of all sizes can result in muscle degeneration, patients with anterior cable ruptures or large or massive tears are particularly susceptible . Baseline muscle degeneration is associated with poor repair success and functional outcomes . For patients in which repair is contraindicated, muscle atrophy and FI often continue to progress during nonoperative treatment, further impairing function …”

Adipocyte hyperplasia: the primary mechanism of supraspinatus intramuscular fat accumulation after a complete rotator cuff tendon tear: a study in the rabbit

“…Uhthoff et al [19] showed that animals with reattachment immediately after tear could recover muscle volume but did not reverse fat accumulation. Delayed repair also failed to reverse fat accumulation [18][19][20][21]. These four studies used precise, invasive as well as radiologic measures and followed up SSP muscles for 3 months after repair.…”

“…In a different study, delayed tendon reattachment did not reverse SSP fat accumulation [20]. The rabbit experimental model of rotator cuff tear and repair reproduced accurately the human pathology and represents a valuable avenue to decipher the pathophysiology of IMF accumulation associated with rotator cuff tear [12,21].…”