In which cases would CA heads be preferred over reverse systems?

The preference for using compensatory anatomy (CA) heads over reverse shoulder systems arises in specific scenarios, particularly in the context of muscle function and joint mechanics. When evaluating the strength and function of the deltoid muscle, a healthy deltoid is crucial for optimal shoulder mechanics. The CA design is tailored to preserve and utilize the native anatomy of the shoulder, which is particularly effective when the deltoid is fully functional.

In cases of deltoid insufficiency, the CA heads are more favorable because they do not require the deltoid to compensate for the loss of motion or stability to the same extent that a reverse system would. A reverse shoulder arthroplasty modifies the mechanics of the shoulder joint and heavily relies on the deltoid's ability to function properly, sometimes leading to complications if the deltoid is insufficient. Therefore, the CA design can provide a more effective solution for patients who lack deltoid strength, as it relies more on the patient's existing musculature around the shoulder.

When considering other scenarios, such as patients with humeral neck fractures or severe rotator cuff tears, the reverse systems are typically preferred due to their ability to compensate for significant rotator cuff deficiency. In these cases, the anatomical considerations shift,