Acromioclavicular Joint Resection: Arthroscopic vs. Open Approach
Abstract & Commentary
Synopsis: Conservative management of acromioclavicular joint arthrosis involves activity modification, anti-inflammatory medications, and occasional steroid injections into the AC joint. When these measures fail, excision of the terminal 1-1.5 cm of the clavicle has been shown to be effective for pain relief, allowing the athlete to return to activities.
Source: Matthews LS, et al. Arthroscopic versus open distal clavicle resection: A biomechanical analysis on a cadaveric model. Arthroscopy 1999;15(3):237-240.
Both arthroscopic and open methods for distal clavicle excision have been used, with few comparative studies. Matthews and colleagues compared arthroscopic to open resection methods in a cadaver model to determine if one approach was biomechanically superior to the other. Specifically, they asked the following questions: Does the smaller amount of bone (0.5-1 cm) generally removed arthroscopically adequately decompress the joint, and does the more extensive dissection of open resection destabilize the clavicle?
Twelve fresh cadaver shoulders were prepared in a manner that allowed compressive loading of the AC joint with measurement of relative motion between joint surfaces with an extensometer. Following preconditioning of the joint with a cycled load, a 100N load was applied, and load and displacement data were obtained. An inferior arthroscopic approach was used to resect the terminal 0.5 cm of clavicle using a burr, and the displacement was then measured with compressive loads. The same shoulder then had an additional 0.5 cm of bone removed through a superior, open approach, and the displacements were remeasured.
There was no significant difference noted in the displacement following the arthroscopic (1.13 mm) vs. the open (1.37 mm) resections. However, when the coracoclavicular ligaments were sectioned, the joint space converged for either method.
Comment by David R. Diduch, MS, MD
Pain and arthrosis in the acromioclavicular joint of the shoulder may occur following a traumatic AC joint injury or with repetitive loading. Partial traumatic disruptions result in late pain more often than do complete disruptions because the clavicle still makes contact with the acromion in partial disruptions (Grade I or II). In these cases, rubbing together of the bony ends with overhead or cross-arm adducted activities may result in painful degenerative changes. Likewise, weightlifters can excessively load the AC joint with bench or overhead press motions, resulting in bony erosion or osteolysis of the distal clavicle.
This study by Matthews et al effectively demonstrates that either arthroscopic or open resection methods can be effective at decompressing the AC joint. In fact, removal of only 0.5 cm of bone with a burr appears to be sufficient. Loading of the bone ends can be prevented provided the coracoclavicular ligaments are preserved. This is an important point. Grade III or complete AC joint separations with disruption of the coracoclavicular ligaments destabilize the clavicle such that bony impingement may persist after simple excision. In these cases, reconstruction of AC joint stability, such as with transfer of the coracoacromial ligament to the cut end of the clavicle, is necessary.
The vast majority of AC joint injuries can be managed successfully without surgery. Those that develop late pain or osteolysis with compressive loads can be decompressed either arthroscopically or by open methods equally well. While arthroscopic resection may involve less perioperative morbidity, it tends to take more surgical time and be more technically demanding. Assessment of adequate bone removal, especially posterior-superior, can be difficult and is critical to avoiding continued pain from residual impingement. This paper supports a decision on operative approach based upon surgeon’s and patients’ preference.
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