Avulsion of the profundus tendon insertion usually occurs when something strongly grasped is suddenly pulled away ("Rugby jersey finger"), either tearing the tendon from the bone, producing a volar avulsion fracture, or both. The injury is compounded to a variable degree by devascularization of the tendon from disruption the attachments of the vincula. For example, in the soft tissue variety of injury, the tendon usually retracts into the palm, tearing away the attachments of both the long and short vincula. If treatment is delayed (which often is the case), at the time of exploration, the distal tendon segment found in the palm is either necrotic or firm and contracted to such a degree that it is unsuitable for reattachment. If the injury is associated with an avulsion fracture, the end of the tendon is usually trapped at either the base of the distal phalanx, the A4 pulley (mid-middle phalanx) or the A2 pulley (mid-proximal phalanx) (Fig. 19) with avulsion fracture fragments of diminishing size, respectively. Obviously, the greater distance the tendon retracts, the more brief the window of opportunity for primary repair. If the end of the tendon is trapped at or distal to the proximal interphalangeal joint, only the short vinculum is disrupted. More proximal retraction results in disruption of both the long and short vincula, with unavoidable tendon devascularization. Minimally displaced avulsion fractures may be repaired many weeks after injury, but in this instance, the examiner should have the patient demonstrate some active flexion of the distal interphalangeal joint to confirm that this is not the combined injury of avulsion fracture and complete soft tissue tendon avulsion. If primary reinsertion is not possible, either distal interphalangeal joint capsulodesis or arthrodesis is less complicated than staged flexor tendon reconstruction with a temporary silastic rod.

Profundus Avulsion
 

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