The Rugby Shoulder – Shoulder injury in rugby players
Rugby is a high contact sport with high incidence of injury. Shoulder injuries comprise 20% of all rugby injuries, and the shoulder is the second most commonly injured joint following the knee. Acromioclavicular joint dislocation and shoulder dislocation is the most common shoulder injuries. The study of English Professional Rugby Union1 showed that the incidence of shoulder injuries was significantly higher during matches compared with training (8.9 vs 0.10 per 1000 player-training hours). The most common match injuries was the acromioclavicular joint dislocation, also known as shoulder separation. The most severe injury was shoulder dislocation (glenohumeral joint dislocation) and labrum tear, and about two-third of them (62%) had recurrence. The majority of match shoulder injuries were sustained in the tackle (65%), and a mean of 241 player-days per club per season were lost to shoulder injuries.
The shoulder is the most mobile joint in the body, making it mechanically unstable. A comparison can be made of the humeral head on the glenoid joint as a golf ball is on the tee. The dynamic stabilizer of the shoulder joint is the muscles around the shoulder joint which include the rotator cuff muscles, which are normally well developed in muscular rugby players. Another important stabilizing effect comes from the clunk block effect of the labrum, which is the weakest point in the shoulder.
There are two major mechanisms of injuries. First is forced abduction and external rotation which occurred either in a tackle, or landing with the ball outstretched when scoring a try. Second is direct impact with the arm at the side, this occurred when player holding the ball are forced to the ground, or on direct impact tackling
Concerning the types of shoulder injuries, acromioclavicular joint injury or dislocation, and labral injury are the two most common. Labral tear is more common than a true shoulder dislocation, which causes subclinical instability and subluxation. Rotator cuff tear is only seen in 5% of cases. The pattern of labral tear is more complex and severe in rugby player injuries in comparison to other sports. In rugby injuries, there are more prominent cases of bony Bankart lesion, SLAP tear and posterior labral tear.
The acromioclavicular (AC) joint is located at the tip of the shoulder where the acromion (part of shoulder blade) joins with the collarbone (clavicle). Problems can be acute such as AC joint dislocation or chronic AC joint pain. AC joint dislocation usually occurred with a direct fall on the shoulder. The degree of injury is classified by the degree of joint separation and injury to the ligaments supporting the joint. More severe types of AC joint dislocation require early surgical reduction and fixation. Less severe types can usually be treated conservatively with physiotherapy and analgesia. Most people with less severe types of AC joint dislocation will recover fully without problems, but overhead athletes or manual worker may have persistent pain and require surgical treatment, namely arthroscopic distal clavicle resection. Chronic AC joint pain is usually caused by repetitive minor AC joint injury. Pain is commonly found in overhead activities, along with local tenderness over the AC joint and a cross arm pain test positive. The problem presides in the cartilage injury inside the AC joint and arthroscopic distal clavicle resection may be required where indicated.
As mentioned before, labral tear is more common than the true shoulder dislocation. It is most likely due to large muscle bulk that prevents the frank dislocation in rugby players. Dislocation usually occurs in forced abduction and external rotation positions, causing an anterior labral tear (Bankart lesion). There is higher incidence of bony Bankart lesion (Labral tear with glenoid bone fracture) and rotator cuff tear in this group. Direct impact injury usually results in a superior labral tear (SLAP, Superior Labral Anterior Posterior lesion) and posterior labral tears. At the time of injury, there may often be a pop or dead arm feeling. Eventually they are able to return to play, but not to the same level. The symptom include pain, catching, clicking, or locking feeling. The players often lose confidence in the injured shoulder and avoid tackles on that side. They may also have posterior shoulder pain in bench pressing exercise. Investigation for this problem includes x-rays to look for bony Bankart lesion, MRI scan for rotator cuff tear and labral tear. Sometimes MRI arthrogram (MRI with contrast injected into the shoulder joint) may be needed to give a better diagnosis, but it may still not be 100% accurate. Finally, shoulder arthroscopy is the golden standard for these diagnosis. Players who are not able to return to pre-injury level of play, may require surgical treatment. Surgical treatment of choice is an arthroscopic repair of the labrum, except in large glenoid bone deficiency which requires an open bone block procedure (Latarjet procedure). After surgery, there is a comprehensive rehabilitation protocol with physiotherapist so that these players can return to play as early and as safe as possible.
References:
- Julia Headey, John H. M. Brooks, Simon P. T. Kemp. The Epidemiology of Shoulder Injuries in English Professional Rugby Union. Am J Sports Med September 2007;35:1537.
Written by Dr. Benjamin Chow
