Review Question - QID 217902

When performing an arthroscopic distal clavicle excision (DCE), it is important to avoid damaging the posterior/superior acromioclavicular (AC) ligaments in order to avoid post-operative anterior-posterior AC joint instability.

AC joint arthritis is a common cause of shoulder pain and often occurs concomitantly with other shoulder pathologies. If present radiographically and symptomatic, patients are often indicated for an arthroscopic DCE, or Mumford procedure. This involves removing the lateral 0.5-1.0 cm of distal clavicle arthroscopically with a burr. Complications are primarily related to under- or over- resection, as visualization can be difficult during this portion of the procedure. Under-resection can lead to continued pain at the AC joint, while over-resection can lead to instability secondary to damage to the AC or coracoclavicular ligaments. Even in cases where an appropriate amount of distal clavicle is resected, damage to the posterior/superior AC ligaments and joint capsule can lead to anterior-posterior instability at the AC joint post-operatively that can be bothersome to patients.

Strauss et al. discuss the evaluation and management of failed distal clavicle resections, noting that most are successful whether performed open or arthroscopically. They note common causes of failure include under-resection, instability, stiffness, heterotopic bone formation, and post-operative infection. They discuss management of these conditions which can be conservative or potentially involve revision surgery based on the pathology at hand.

Nuber et al. reviewed the arthroscopic diagnosis and treatment of AC joint injuries. They note most can be treated conservatively, but some may ultimately require DCE, whether open or arthroscopic. Advantages to arthroscopic DCE include the ability to directly visualize the end of the clavicle, less violation of the surrounding muscles/tendons, shorter rehabilitation, and a quicker return to activity. The authors suggest that only 4-8mm of bony resection may be necessary in order to see good results, however complications can be seen in cases of under- or over-resection.

Figure A is an intraoperative arthroscopy picture demonstrating distal clavicle excision being performed.

Incorrect Answers:
Answer 1: The coracohumeral ligament passes through the rotator interval and is not at risk of being damaged during a DCE. Additionally, damage to the coracohumeral ligament would not lead to AC joint instability.
Answer 2: The coracoacromial ligament inserts on the anterior aspect of the anterior acromion and is often removed from its insertion during a subacromial decompression if impingement is suspected. However, it does not play a role in AC joint instability.
Answer 3: The posterior and superior AC ligaments play the most important roles in providing AC joint stability. Resection or damage to the anterior/superior AC ligaments does not contribute to instability.
Answer 5: The deltotrapezial fascia is typically elevated and repaired in cases of open distal clavicle excision, but not typically affected in arthroscopic DCE.