Background
The deltopectoral approach for total shoulder arthroplasty can result in subscapularis dysfunction. In addition, glenoid wear is more prevalent posteriorly, a region difficult to access with this approach. We propose a posterior approach for access in total shoulder arthroplasty that uses the internervous interval between the infraspinatus and teres minor. This study compares this internervous posterior approach with other rotator cuff–sparing techniques, namely, the subscapularis-splitting and rotator interval approaches.

Methods
The 3 approaches were performed on 12 fresh frozen cadavers. The degree of circumferential access to the glenohumeral joint, the force exerted on the rotator cuff, the proximity of neurovascular structures, and the depth of the incisions were measured, and digital photographs of the approaches in different arm positions were analyzed.

Results
The posterior approach permits direct linear access to 60% of the humeral and 59% of the glenoid joint circumference compared with 39% and 42% for the subscapularis-splitting approach and 37% and 28% for the rotator interval approach. The mean force of retraction on the rotator cuff was 2.76 (standard deviation [SD], 1.10) N with the posterior approach, 2.72 (SD, 1.22) N with the rotator interval, and 4.75 (SD, 2.56) N with the subscapularis-splitting approach. From the digital photographs and depth measurements, the estimated volumetric access available for instrumentation during surgery was comparable for the 3 approaches.

Conclusion
The internervous posterior approach provides greater access to the shoulder joint while minimizing damage to the rotator cuff.