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Background: Ring avulsion injuries are somewhat common due to the propensity of a ring to catch on objects and pull the tissues of the finger.  These injuries can range from skin lacerations to complete digit amputation.  They present a specific concern due to difficulty of repair to structures in this area.  The most accepted classification for ring avulsion injuries was developed by Urbaniak and has three classes based on worsening severity.  Other authors have commented on the need to modify the classification due to their experience treating a variety of injuries.

Methods: Retrospective chart review was conducted on thirty-three patients with ring injuries were treated by the senior author and colleagues.  At the time of injury, all patients were wearing rings that were integral to the mechanisms of injury. Eight cases were classified as Urbaniak Class I, thirteen class II, and Twelve class III. 

Results: Uniformly good finger motion occurred with salvage of fingers in which no damage occurred to the skeleton, profundus or sublimus flexor tendons.  All patients with flexor tendon injury or proximal phalangeal fracture or both had significant loss of motion and limited hand function.  This includes decreases in PIP joint motion of approximately 40 degrees and 70 degrees of total active motion compared to class II injuries without tendon and bone involvement.  Four class III injuries had a successful replantation and DIP joint fusion, but one complained of swelling and dysestheia and was eventually lost to follow-up; another had revision amputation at the MP joint level due to infection and ischemia.  The other two were injuries distal to the FDS insertion (Zone I) had good outcomes. 

Conclusion: As a guideline to salvage, the authors propose expanding the Urbaniak Class II injury to include classes IIA through IIE to account for all potentially injured structures from superficial to deep.  As more structures are injured, final range of motion and function are decreased.  While current guidelines advise revascularization of class II ring avulsion injuries, our series would suggest caution in anticipating good results with sublimus or profundus tendon laceration and proximal phalanx fracture.  Replantation in class III injuries, while possible, is warranted only in exceptional situations or those in flexor zone I.