Working Diagnosis:
Flexor carpi radialis rupture secondary to continuous friction from non-union trapezial ridge fracture

Treatment:
Conservative management with occupational therapy which focused on range of motion, ultrasound, and soft tissue massage was initiated. Surgery was deferred, to allow patient to return to current season.

Outcome:
Patient was able to play within two weeks with minimal pain.

Author's Comments:
Trapezium fractures as a whole represent 4-5% of all carpal fractures, with those involving trapezial ridge even less common. Trapezial ridge is the osseous palmar projection of the trapezium that serves as the radial attachment of the transverse carpal ligament. There are two types of ridge fractures: type I at the base and type II tip avulsions. Fractures may result from either direct trauma or distraction force of carpal arch resulting in avulsion of transverse carpal ligament. Fall on outstretched hand is a frequently reported mechanism of injury. Ecchymosis and point tenderness are common acute symptoms and patients can have median nerve symptoms due to close proximity of the carpal canal. The flexor carpi radialis travels from within antebrachial fascia to distal aspect of forearm forming a fibrous sheath as it enters its fibro-osseous tunnel of the trapezial ridge. At the distal trapezium the sheath is narrowest, and consequently the FCR tendon is susceptible to injury at this location.
Standard wrist x-rays frequently result in misdiagnosis due to inadequate visualization of palmar aspect of the trapezium. It is important to get carpal-tunnel views to make an adequate diagnosis; however, in chronic cases or those with negative x-rays, CT is beneficial to identify occult fractures.
This case highlights several important points in management of carpal fractures in athletes. First, these injuries can be easily dismissed as simple sprains seen in NFL linemen. Secondly, routine plain x-rays are often negative or misinterpreted as was the case with our patient. Type II trapezial ridge fractures have a propensity for nonunion despite adequate immobilization. This case also highlights that nonunion of trapezial ridge can be asymptomatic with the patient being able to participate in professional football for years without significant complaints.

Editor's Comments:
Isolated fracture of the trapezium is an uncommon injury and accounts for only a small percentage of carpal fractures. It is usually a result of a high energy trauma and can be classified into ridge and body fractures with ridge fractures being less common. Non-union is a rare complication of this often missed fracture. Most flexor tendon ruptures occur acutely with distal radius fractures, as a complication from surgical fixation or chronically due to local steroid injections.

References:
Marchessault J, Conti M, Baratz M. Carpal Fractures in Athletes Excluding the Scaphoid. Hand Clin 2009;25:371-388

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