CT-based volumetric assessment of rotator cuff muscle in shoulder arthroplasty preoperative planning

Abstract

Aims The aim of this study was to describe a quantitative 3D CT method to measure rotator cuff muscle volume, atrophy, and balance in healthy controls and in three pathological shoulder cohorts. Methods In all, 102 CT scans were included in the analysis: 46 healthy, 21 cuff tear arthropathy (CTA), 18 irreparable rotator cuff tear (IRCT), and 17 primary osteoarthritis (OA). The four rotator cuff muscles were manually segmented and their volume, including intramuscular fat, was calculated. The normalized volume (NV) of each muscle was calculated by dividing muscle volume to the patient’s scapular bone volume. Muscle volume and percentage of muscle atrophy were compared between muscles and between cohorts. Results Rotator cuff muscle volume was significantly decreased in patients with OA, CTA, and IRCT compared to healthy patients (p < 0.0001). Atrophy was comparable for all muscles between CTA, IRCT, and OA patients, except for the supraspinatus, which was significantly more atrophied in CTA and IRCT (p = 0.002). In healthy shoulders, the anterior cuff represented 45% of the entire cuff, while the posterior cuff represented 40%. A similar partition between anterior and posterior cuff was also found in both CTA and IRCT patients. However, in OA patients, the relative volume of the anterior (42%) and posterior cuff (45%) were similar. Conclusion This study shows that rotator cuff muscle volume is significantly decreased in patients with OA, CTA, or IRCT compared to healthy patients, but that only minimal differences can be observed between the different pathological groups. This suggests that the influence of rotator cuff muscle volume and atrophy (including intramuscular fat) as an independent factor of outcome may be overestimated. Cite this article: Bone Jt Open 2021;2(7):552–561.

Pectoralis major tendon transfer in reverse total shoulder arthroplasty with irreparable subscapularis: surgical technique and preliminary clinical and radiological results

“…In the last clinical and radiological follow-up via CT-Scan, good trophicity, no fatty infiltration and the good integrity and function of the tendon transfer was reported in all patients. 31 No atraumatic dislocations were reported during this study.…”

“…Follow-up CT-Scans were performed to assess the integrity and fatty infiltration of the PM tendon transfer in all patients. 31 …”

Objective analysis of partial three-dimensional rotator cuff muscle volume and fat infiltration across ages and sex from clinical MRI scans

“…Intramuscular fat was included in this calculation to measure the muscle volume and conform to methodology in previous literature 13 . Dividing muscle volume by scapula volume is commonly used to normalize by patient size when interpreting and comparing muscle volume across patients 13 , 16 .…”

“…Intramuscular fat was included in this calculation to measure the muscle volume and conform to methodology in previous literature 13 . Dividing muscle volume by scapula volume is commonly used to normalize by patient size when interpreting and comparing muscle volume across patients 13 , 16 . To validate this technique for partial volume measures, we correlated scapular volume and each of the four RC muscles’ volume as a function of location along scapula from 30 and 40% for the healthy adult scans.…”

“…However, all these methods have multiple limitations: (1) subjectivity and lack of precision, (2) limited applicability of 2D measurements to the entire muscle structure 10 , (3) bias towards the supraspinatus at the expense of the other RC muscles; and (4) lack of concrete normative comparisons to account for natural atrophy with age 11 . Current innovations have trended toward complete 3D preoperative planning 12 and objective 3D fat quantification 13 ; however, clinical MRI scans often only capture the lateral portion of the RC muscle structure. To systematically determine 3D muscle volume, a method to account for variation in capture range that is typical of clinical MRI scans must be developed and validated.…”