Preoperative rotator cuff fatty infiltration and muscle atrophy do not negatively influence outcomes following anatomic total shoulder arthroplasty

Abstract

Background

Anatomic total shoulder arthroplasty (TSA) is an effective surgical option for the treatment of primary glenohumeral osteoarthritis (GHOA) with an intact rotator cuff. While an intact rotator cuff is essential to the success of TSA, little is known about how preoperative rotator cuff muscle quality may impact clinical outcomes. In this study, we sought to determine the effects of rotator cuff fatty infiltration (FI) and muscle atrophy (MA) on clinical outcomes following TSA.

Methods

A retrospective review of a prospectively maintained, single-surgeon registry was used to identify patients undergoing TSA for GHOA between April 2015 and March 2020. Patients were included if they had preoperative magnetic resonance imaging available, an intact rotator cuff, and complete preoperative and minimum 2-year postoperative patient-reported outcome measures (PROMs) and active range of motion (ROM) measurements. Preoperative MA and FI of the rotator cuff were assessed on magnetic resonance imaging by measuring muscle cross-sectional area and using the Goutallier classification system, respectively. Pearson’s correlation was used to determine any relationship between MA and clinical outcomes. Univariate analysis was used to compare clinical outcomes of patients with moderate-to-severe FI to those with minimal-to-mild FI.

Results

There were 163 shoulders from 154 patients with a mean age of 62.5 (standard deviation = 7.4) and a mean follow-up of 2.9 years (standard deviation 1.2) that met inclusion criteria. Rotator cuff muscle area was not correlated with any preoperative or postoperative ROM or PROMs (P > .05). However, the ratio of infraspinatus and teres minor (posterior cuff) to subscapularis muscle area was minimally negatively correlated with change in Single Assessment Numerical Evaluation (r = −0.171, P = .029) and change in internal rotation (r = −0.207, P = .008), although the clinical relevance is unclear. No significant differences in preoperative ROM or PROMs were found between patients with minimal-to-mild and moderate-to-severe FI (P > .05).

Conclusion

Preoperative rotator cuff muscle volume and FI do not impact clinical outcomes following TSA in patients with GHOA and intact rotator cuffs. TSA remains a viable surgical treatment for individuals with GHOA and an intact rotator cuff, provided the MA and FI are not so severe that a patient may be indicated for another type of treatment.