Acute vascular compromise after avulsion of the distal phalanx with the flexor digitorum profundus tendon

Acute vascular compromise after avulsion of the distal phalanx with the flexor digitorum profundus tendon An unusual case of avulsion fracture of the insertion of the flexor digitorum profundus tendon is presented. In most such avulsion fractures a small amount of fractured bone may remain with the tendon . In this case almost the entire distal phalanx was avulsed, and vascular compromise of the digit then occurred. Prompt redu ction restored vascularity. (J HAND SURG 1987;12A: 259-61.)

Leonard Gordon, M.D ., and Enrique H. Monsanto , M.D., San Francisco, Calif.

From the Department of Orthopaedic Surgery, University of California at San Francisco , San Francisco, Calif. Received for publication March 6, 1986; accepted in revised form May 5, 1986. This article was accepted for publication before July I, 1986. No conflict-of-interest statement was requested from the authors. Reprint requests: Leonard Gordon, M.D ., Department of Orthopaedic Surgery/U47I , University of California at San Francisco , San Francisco, CA 94143.

, Avulsion fracture of the insertion of the flexor digitorum tendon is not unusual. Loss of flexion of the distal interphalangeal (DIP) jo int in the affected finger can usually be managed by reduct ion and fixation of the avulsed bone fragment. We had a case of flexor digitorum profundus avulsion, in which almost the entire distal phalanx accompanied the attached tendon as it retracted just distal to the proxim al interphalangeal (PIP) joint. This avulsion resulted in compres sion of the neurovascular bundle s.

Fig. 1. Small finger shows evidence of vascular compromi se , with a mass over the middle phalanx. Note the extended position of the DIP joint.

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Fig. 2. A, Lateral x-ray film of the small finger shows the fractured distal phalanx overlying the middle phalan x. B, Posteroanterior x-ray film shows the fractur e of the distal phal anx .

Case report A 43-year-old man was walking his dog when it suddenly yanked on the leash. This sharp tug occurred when the patient 's fingers were flexed around the leash and resulted in an injury to the small finger. There was immediate pain and swelling. The diagnosis of the orthopedic surgeon was that

the injured digit had acute vascul ar compromise. The patient was then transferred to the University of California Medical Center at San Francis co for possible revascularization . The finger was markedly swollen and pale , with areas of blue discoloration ( Fig. 1). It was also cool to the touch , having no capillary return . There was decreased sensibility

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Fig. 3. Intraoperat ive photograph of the tendon avulsion. with the attached distal phalan x; note the appearance of the palm ar aspect of the distal phalanx.

over the entire palm ar surface of the d istal phalanx , and a palpable mass was pre sent on the palmar surface just distal to the PIP joint. Flexi on of the DIP joint was absent. A diagn osis of acute neur ovascular compromise was made . X-ray films of the small finger showed that only a small wafer of the proximal and distal end of the distal phalanx rema ined in position . The rest of the distal phalan x was displaced into the reg ion of the PIP joint ( Fig. 2). Through a Bruner incision, the avulsed flexor digitorum profundus and the distal phalanx were located just distal to the PIP joi nt ( Fig. 3). Both vascular bundles were intact but ecchymotic. After redu ction of the fracture. circulation returned and further revaseularization was unnecessary. The reducti on was maint ained with a Kirschner wire . Early range of motion of the PIP joint was initiat ed . The Kirschner wire was removed at 4 weeks, and motion was begun at the distal join t.

Discussion Four types of avulsion of the flexor digitorum profundus tendon have been described . I. 2 In type I , the tendon is pulled from its insertion with retraction into the palm, causing severe scarring of the flexor sheath . In type 2, avulsion of the tendon causes it to retract into the finger, but retraction is limited by the vinculum longum . Type 3 is an avulsion of the tendon accompanied by a fragment of bone where it inserts, result ing in entrapment in the digit al tendon sheath after retrac-

tion. I The fourth type is an intra-articular fragment of the DIP joint avulsed and trapped at the base of the proxim al phalanx. " This case is characteriz ed by the avulsion of a large bone fragment that constituted the majority of the distal phalanx , with acute vascular compromise as the result. The mechanism of injury in this particular instanceforced extension of the finger from the flexed positionhas been respon sible for other types of digital tendon avulsion injuries ." It is not clear whether in this patient the unusually large size of the bone fragment caused direct compression of the neurovas cular bundles, with consequent ischemia and neuropraxia, or whether hematom a and swelling caused the vascular problem s. Operat ive reduction within 4 hours of the injury resulted in restoration of neurovascular function , and irreversible ischem ic inj ury was avoided.

REFERENCES I . Ledd y JP. Packer JW : Avulsion of the profundus tend on insert ion in athletes. J HAND SURG 2:66-9 , 1977 2. Sm ith JH : Avulsion of a profundus tend on with simult aneous intraarticular fracture of the distal phalanx-Case report . J HAND SURG 6:600- 1, 1981 3. Carroll RE , March RM : Avulsio n of the flexor profundu s tendon inserti on . J Trauma 10:1109-1 8