Association Between Rotator Cuff Muscle Size and Glenoid Deformity in Primary Glenohumeral Osteoarthritis

Abstract

Background: Although glenoid morphology has been associated with fatty infiltration of the rotator cuff in arthritic shoulders, the association of rotator cuff muscle area with specific patterns of glenoid wear has not been studied. The purpose of our study was to assess the associations of glenoid deformity in primary glenohumeral osteoarthritis and rotator cuff muscle area. Methods: A retrospective study of 370 computed tomographic (CT) scans of osteoarthritic shoulders was performed. Glenoid deformity according to the modified Walch classification was determined, and retroversion, inclination, and humeral-head subluxation were calculated using automated 3-dimensional software. Rotator cuff muscle area was measured on sagittal CT scan reconstructions. A ratio of the area of the posterior rotator cuff muscles to the subscapularis was calculated to approximate axial plane potential force imbalance. Univariate and multivariate analyses to determine associations with glenoid bone deformity and rotator cuff measurements were performed. Results: Patient age and sex were significantly related to cuff muscle area across glenoid types. Multivariate analysis did not find significant differences in individual rotator cuff cross-sectional areas across glenoid types, with the exception of a larger supraspinatus area in Type-B2 glenoids compared with Type-A glenoids (odds ratio [OR], 1.5; p = 0.04). An increased ratio of the posterior cuff area to the subscapularis area was associated with increased odds of a Type-B2 deformity (OR, 1.3; p = 0.002). Similarly, an increase in this ratio was significantly associated with increased glenoid retroversion (beta = 0.92; p = 0.01) and humeral-head subluxation (beta = 1.48; p = 0.001). Within the Type-B glenoids, only posterior humeral subluxation was related to the ratio of the posterior cuff to the subscapularis (beta = 1.15; p = 0.001). Conclusions: Age and sex are significantly associated with cuff muscle area in arthritic shoulders. Asymmetric glenoid wear and humeral-head subluxation in osteoarthritis are associated with asymmetric atrophy within the rotator cuff transverse plane. Increased posterior rotator cuff muscle area compared with anterior rotator cuff muscle area is associated with greater posterior glenoid wear and subluxation. It is unclear if the results are causative or associative; further research is required to clarify the relationship.

The implications of the glenoid angles and rotator cuff status in patients with osteoarthritis undergoing shoulder arthroplasty

“…Posterior cuff ratio was found to be high in crosssectional areas of patients with Walch B2 types rather than in Walch A types. Posterior humeral subluxation and glenoid retroversion was as well were related to posterior cuff ratio [21]. Moreover Aleem et al [21] did not find a correlation of glenoid inclination with rotator cuff muscle area whereas, Walker et al [24] and Donohue et al [23] described the association of increased posterior muscle fatty infiltration with posterior glenoid bone loss and glenoid retroversion, which is in line with our findings.…”

“…Posterior humeral subluxation and glenoid retroversion was as well were related to posterior cuff ratio [21]. Moreover Aleem et al [21] did not find a correlation of glenoid inclination with rotator cuff muscle area whereas, Walker et al [24] and Donohue et al [23] described the association of increased posterior muscle fatty infiltration with posterior glenoid bone loss and glenoid retroversion, which is in line with our findings. Our data showed that posterior and posterosuperior glenoid wear was seen in 98% of patients with rotator cuff tears compared to only 91,5% in rotator cuff intact patients.…”

“…The effects of glenoid version and inclination on rotator cuff integrity are not clearly established. Some recent studies focused on the relationship between rotator cuff integrity, fatty infiltration and glenoid deformity [21][22][23][24]. Increased glenoid retroversion was associated with a high crosssectional area of the supraspinatus and infraspinatus, rather than the low cross-sectional area of subscapularis [22].…”

Could Subtle Obstetrical Brachial Plexus Palsy Be Related to Unilateral B Glenoid Osteoarthritis?

“…Neurogenic injury results in muscle and joint imbalance that leads to morphologic changes that progress with time, depending on the severity of the lesion. It has been shown that muscle imbalance between the subscapularis and posterior cuff is associated with posterior subluxation and retroversion of the glenohumeral joint [ 9 ].…”

“…Glenohumeral osteoarthritis (OA) with a type B retroverted glenoid with erosion is also believe to be initiated by progressive posterior subluxation of the humeral head [ 10 ]. The exact cause of such translation has not been elucidated yet, although many anatomical parameters have been identified as potential etiologic factors, including increased premorbid retroversion [ 11 ], decreased humeral retrotorsion [ 12 ], proximal humeral morphology [ 13 ], altered acromial roof morphology, position of the scapula on the thorax, as well as other factors like repetitive dynamic posterior subluxation [ 14 ], and muscular disbalance [ 9 ]. A primum movens that could explain all previously mentioned type B associations is the presence of a subclinical neurological lesion, such as a OBPP.…”