Objective: The aim of this study was to identify the anatomical obstacles on the humeral surface which can complicate subcutaneous plate advancement during surgical treatment of humeral fractures.
Methods: We dissected twelve upper extremities of six male cadavers, and measured the humeral length, which was defined as the distance between the greater tubercle and the lateral epicondyle. We performed a retrograde advancement of a 4.5 mm plate through the subbrachial tunnel and noted the mechanical obstacles during the procedure. In addition, we recorded the distances between the anatomic obstacles and lateral epicondyle.
Results: The average humeral length was 271.8 mm. We identified anterior insertion of the deltoid muscle and the proximal part of the brachialis muscle as the main anatomic obstacles on the anterior surface of the humerus. The average distances between the lateral epicondyle and the most proximal and distal insertion of anterior deltoid were 188.9 mm and 138.7 mm, respectively. The average distance between the lateral epicondyle and the brachialis origin was 147.4 mm. Proportions of the distances between the lateral epicondyle and proximal of anterior deltoid insertion, the lateral epicondyle and distal of anterior deltoid insertion and the lateral epicondyle and proximal of brachialis origin to humeral length were 69.4%, 51%, and 54.2%, respectively. There was a high interobserver reliability (p<0.001).
Conclusion: The deltoid insertion and proximal attachment of the brachialis muscles were identified as mechanical obstacles when performing the percutaneous plating. These sites caused difficulties with the procedure during the retrograde plate advancement through submuscular tunnel on the anterior surface of humerus. It was also noted that for successful plate advancement, it was necessary to release the anterior part of the deltoid insertion.