Is there an association between a low acromion index and osteoarthritis of the shoulder?

Abstract

The aim of this study was to evaluate the relationship between a low acromion index and osteoarthritis of the shoulder. Three patient groups were used: (I) instability, n=53; (II) calcifying tendonitis, n=109; and (III) osteoarthritis, n=120. Standardised digital X-rays were evaluated from the true anteroposterior and axillary views. Joint space width at three levels in each plane and the size of humeral osteophytes were measured and osteoarthritis was graded according to Samilson. The acromion index was calculated according to Nyffeler et al. (J Bone Joint Surg Am 88:800-805, 2006) in the true anteroposterior view. There were two independent investigators. Interobserver reliability was excellent for all measurements in the anteroposterior (AP) projection but inferior in the axillary projections, especially in group III. The mean acromion index was 0.64±0.07 in group I, 0.64±0.08 in group II and 0.73±0.12 in group III. The acromion index was not correlated with the joint space width nor with the size of the osteophytes or the Samilson grading in group III. The data of the study did not show a significant association between a low acromion index and typical signs of osteoarthritis at the shoulder. The theoretical concept of a small acromion index associated with the development of osteoarthritis of the shoulder is not supported.

Critical Shoulder Angle and Acromial Index Do Not Influence 24-Month Functional Outcome After Arthroscopic Rotator Cuff Repair

“…Biomechanical experiments have suggested that each increase in CSA is accompanied by a significant increase in cranially directed shear forces and therefore superior glenohumeral joint stability. 10,20,29 The implication is that with continued compensatory activity of the (15) .039 6 mo 60 (18) 54 (17) .080 1 y 69 (15) 67 (14) .374 2 y 71 (12) 71 (13) .953 Oxford Shoulder Score 3 mo 27 (11) 29 (11) .400 6 mo 19 (8) 22 (10) .130 1 y…”

“…Recently, this theory has been challenged by several authors, with conflicting reports suggesting the need for more sophisticated biomechanical research before the theory can be validated. 2,14,18…”

“…Recently, this theory has been challenged by several authors, with conflicting reports suggesting the need for more sophisticated biomechanical research before the theory can be validated. 2,14,18 The CSA, a radiographic parameter described by Moor et al, 19 has been shown to be a powerful predictor of the occurrence of RCTs. The CSA combines the measurements of the inclination of the glenoid and the lateral extension of the acromion; a CSA greater than 35°is associated with RCTs, and a CSA less than 30°is associated with glenohumeral osteoarthritis and absence of RCT.…”

Acromion and glenoid shape: Why are they important predictive factors for the future of our shoulders?

“… 31 , 32 The CSA, however, is in addition also significantly different between primary osteoarthritis and normal shoulders. This is not the case for the AI, 33 probably due to the joint space narrowing and the flattening of the humeral head in osteoarthritic shoulders.…”

Assesment of Key Parameters on the Performance of the Deltoid Muscle in Reverse Shoulder Arthroplasty — A Modeling and Simulation-Based Study

“…These models were shown to be capable of creating a realistic representation of the X-Ray and MRI images obtained from previous studies 12,13,14,15,19,20 . The dimensions, coordinates, relative positions, perceived displacements, centre of rotations, trajectories, acceleration velocities and displacements can all be specified discretely and accurately allowing for future parametric optimisation.…”