Case Study - Subscapularis Avulsion in an Adolescent Rugby Union Player

Written By Gaby Halloran

Rugby Union is a contact sport, characterised by high impact collisions between opposing players in the tackle. Due to the unpredictable nature of tackling and multiple moving parts, there is a high risk of shoulder injury. The main structures injured are: labrum, rotator cuff and acromioclavicular joint. The glenohumeral joint gains stability from passive (labrum and ligaments) and active (rotator cuff and surrounding muscles) structures, therefore if any one of these structures is damaged a player may experience instability or pain.. Shoulder dislocations entered the top 3 most common time loss injuries in Rugby Union (>84 days severity) for the first time in the 2017-2018 season. Shoulder instability (symptomatic abnormal motion of the glenohumeral joint - GHJ) has been classified by Stanmore to help us diagnose and manage injuries around the GHJ.

These structures can be damaged in isolation or together, by trauma or overuse. Some people are also born with slight differences (e.g. shallow socket) than can mean both atraumatic and traumatic instability are more likely.

Traumatic instability can arise through a number of injury mechanisms:

1.     Forced abduction and external rotation of the GHJ

2.     Direct impact (SLAP lesions)

3.     “Try scoring” injuries - landing on an outstretched arm in hyeprflexion

4.     “Tackler” injuries - extension of an abducted arm behind the player whilst tackling

Why is this relevant to our case study? An injury to any one of the structures both passive and active that provide shoulder stability, can result in instability. This is especially important in a contact sport such as rugby. In our case, we describe a traumatic avulsion of subscapularis at the lesser tuberosity, how it presented and how it would be managed, as well as the potential consequences of returning to sport.

A subscapularis avulsion injury is where the subscapularis tendon is avulsed from its insertion on the lesser tuberosity usually as a result of traction/rapid contraction. They are very rare injuries, with few cases reported in the literature. They appear to be more common in adolescents aged 12-14. It is speculated that these injuries result in avulsion due to the forces applied to the relatively weaker physis, rather than the musculotendinous unit.

The mechanism of injury (MOI) is very similar to that of shoulder instability or dislocation, with forced abduction and external rotation or forced forward flexion of the GHJ. Suspicion should be raised in skeletally immature patients that fits the MOI, who present with ongoing weakness in internal rotation and prolonged dysfunction/pain. Early imaging can help diagnose these injuries and referral to a specialist surgeon is essential for a positive outcome.

It is worth noting that these injuries were historically managed non-operatively, but the small body of evidence now suggests that outcome can be improved with operative treatment due to potential bony overgrowth at the site of healing which can block range of movement.

The case we present is that of a 14yo rugby union full back, who injured his shoulder in a tackle. He had a concurrent ankle injury, for which he was removed from play. His initial recovery was quick, and due to it being the end of the season, did not seek further assessment of his shoulder. He returned to play a few months later with minimal issues. Approximately 1 year on from his injury, he present to the academy Physiotherapists with pain in his shoulder, reduced range of movement (see images) and marked weakness on resisted internal rotation (belly press test).

The player was referred for further imaging to rule out labral or rotator cuff injury. The MRI showed an avulsion at the lesser tuberosity with some signs it had healed just distal to the original insertion. Two surgical opinions were sought, the first advising that surgery would be necessary for optimal function, the second advised a trial period of physiotherapy to improve function.

The player completed approximately 6 weeks of rehabilitation, focusing on isolated strength and function. He regained full range of movement and his internal rotation strength began to improve. It was decided in conjunction with the second surgeon, to continue with conservative management. As mentioned, bony overgrowth can block range of movement, but in this case it was neuromuscular dysfunction preventing the player achieving full flexion/abduction.

The player made a full recovery, hit his key strength and endurance markers and has successfully returned to full contact rugby without issue for several years.

So what?

This case highlights the importance of an individualised approach to management. A thorough and accurate clinical assessment +/- imaging are the keystones to managing shoulder injures in adolescent rugby players. It allows accurate diagnosis, and then appropriate consultation with orthopaedic surgeons. It is important in these cases of delayed diagnosis to exhaust conservative management before considering surgical intervention.

References

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Gaby Halloran