A 65 year old RHD male was packing for travel when he impacted his finger in a suitcase. He thought his finger was dislocated and presented for evaluation. Xrays showed a dorsal avulsion fracture of the distal phalanx with underlying DJD of the DIPJ. The decision was made to treat this with a dorsal extension splint and follow up-no surgery as the fracture is small and involves < than 50% of the articular surface. More importantly he has underlying DJD of the DIPJ which is already associated with stiffness and decreased motion. At 6 week follow up, he was able to fully extend the dorsal phalanx and extension strength was 4+/5. He was instructed to wear the splint for an additional 3 weeks and then begin ROM and strength exercises. Follow up xray is seen below. Note the persistent avulsion defect, however, there is no lag.
Discussion: Mallet finger injuries are commonly seen in orthopedic urgent cares and hand clinics. There are essentially two types-one involving a disruption of the attachment of the terminal extensor tendon distal to the DIPJ, and the other an avulsion of the dorsal bony attachment of the tendon. The recommended treatment for isolated tendon ruptures is a dorsal extension splint for 6 weeks and recheck. The splint can be made by OT with a molded thermoplast material and velcro straps, or with an alumafoam splint and coban/tape. Stax splints are not preferred. The patient is instructed to not allow the DIPJ to flex for 6 weeks. If the finger flexes, the clock resets. The same treatment is true for the majority of bony avulsion fractures. The general criteria for CRPP of a bony mallet include volar subluxation of the distal phalanx, > 50% of articular surface involvement and > 2mm displacement of the fragment.
Sam Dyer, PA-C, MHS