Reverse shoulder arthroplasty with os acromiale

Abstract

Function and strength of the deltoid muscle are important in reverse shoulder arthroplasty (RSA). Moreover, location and shape of the acromion, clavicle, and scapular spine, which are origins of the deltoid muscle, are also important. The frequency of os acromiale is 5% to 15%; however, it is rare in the Asian population, affecting approximately 0.7% of Koreans. RSA has rarely been reported in patients with os acromiale. We present a case series of two patients with cuff tear and arthropathy combined with os acromiale who underwent RSA. From 2016 to 2018, two patients with os acromiale who presented with pain and limited range of motion (ROM) underwent RSA with cuff tear arthropathy using the subscapularis-sparing deltopectoral approach. Their ROM, visual analog scale (VAS), and satisfaction were evaluated before and after surgery. In both patients, VAS decreased, ROM increased, and postoperative satisfaction increased. There were no specific complications due to os acromiale. The VAS, ROM, and satisfaction of patients improved after surgery compared with values before surgery. However, careful attention must be given during surgery to ensure optimal repair and recovery.

Keywords: Cuff tear arthropathy; Os acromiale; Reverse shoulder arthroplasty.

Fig. 1.

Os acromion subtypes: pre-acromial (PA), meso-acromial (MSA), meta-acromial (MTA), basi-acromial (BSA). Depending on location of the osseous union at the ossification center of the acromion, the condition is classified as type A, type B, and type C.

Fig. 2.

A 71-year-old man with a left shoulder, full thickness rotator cuff tear underwent reverse shoulder arthroplasty, revealing os acromiale of meso-acromion type. (A) Preoperative axillary view X-ray showed meso-acromion findings. (B) T1-weighted coronal plane image showed a meso-acromion finding. (C) Anteroposterior postoperative X-ray showed no significant difference in the acromion before and after surgery. (D) One year later, the acromiale showed no morphological changes on the anteroposterior postoperative X-ray. (E) One year later, the acromiale showed no morphological changes on the postoperative computed tomography. Undefined (arrows, meso-acromion).

Fig. 3.

A 73-year-old man with a right shoulder, full thickness rotator cuff tear underwent reverse shoulder arthroplasty that showed os acromiale type B. (A) Preoperative axillary view X-ray showed a type B os acromion finding. (B) T2-weighted coronal plane image showed a type B os acromion finding. (C) Anteroposterior postoperative X-ray showed no significant difference in the acromion before and after surgery. (D) One year later, the acromiale showed no morphological changes on anteroposterior postoperative X-ray. (E) One year later, the acromiale showed no morphological changes on postoperative computed tomography. Undefined (arrows, meso-acromion).