Technical errors in anatomic total shoulder replacement

The anatomic total shoulder replacement is an operation that requires accuracy and technical skills. The balancing of the shoulder and correct placement of the implant are essential for a good outcome. A few of the most common technical errors are outlined below
(1) Malpositioned stems: The most common error is varus placement of the stem or high "sitting" of the stem that lead to "overstuffing" of the joint and high tension to the rotator cuff respectively.
(2) Injury to the infraspinatus during the humeral cut
(3) Over reaming or eccentric reaming of the glenoid in an attempt to correct the glenoid deformity. Correction of the glenoid deformity has the significant disadvantage of removing subchondral bone which is essential for support of the glenoid. This may lead to early loosening and failure of the glenoid component compomising the longevity of the reconstruction.
(4) Failure to adequately utilize the advantage of the eccentric heads to reproduce the anatomy of the proximal humerus
(5) Inadequate inferior capsule release during exposure that leads to difficulties in accessing the glenoid for reaming
(6) Incomplete seating of the glenoid because of poor reaming technique
(7) Over-reaming of the humerus that removes endosteal bone leading to stress points around the tip of the stem and subsequent periprothetic fractures
(8) Less than 4 sutures for repair of the subscapularis tendon that is associated with high failure of the repair.

 When the humeral cut is aimed inferiorly then there is a chance of injury to the infraspinatus

 Superior prominence and medial displacement of the implant leads to "overstuffing" and poor outcomes

 Eccentric placement of the canal was difficult to correct in the past prior to the introduction of the eccentric heads. Minor deviations from the anatomic placement can be corrected with eccentric heads. We recommend identification of the insertion of the supraspinatus and placement of the stem just a few mm medial to the insertion to avoid varus deformity and eccentric placement