-Case Reports-

Two Cases of Flexor Digitorum Profundus Avulsion due to Enchondroma of the Distal Phalanx

Mitsuhiko Nanno^1,2, Takuya Sawaizumi^1,3 and Shinro Takai^1,3

¹Department of Restorative Medicine of Neuro-musculoskeletal System, Orthopaedic Surgery, Graduate School of Medicine, Nippon Medical School
²Department of Orthopaedic Surgery, Nippon Medical School Musashi Kosugi Hospital
³Department of Orthopaedic Surgery, Nippon Medical School

Avulsion of the flexor digitorum profundus tendon with fracture of the distal phalanx is rare. Moreover, enchondroma is less frequent in the distal phalanx. We report two unusual cases of avulsion of the flexor digitorum profundus tendon at its insertion in combination with pathological fracture of the distal phalanx due to enchondroma. Curettage and bone grafting were performed for an enchondroma of the distal phalanx. The flexor digitorum profundus tendon and the avulsed bone fragment were reinserted through the bone graft into the distal phalanx using the pull-out technique. With Strickland's criteria, the clinical results were evaluated as excellent in both cases. At the final follow-up examinations, there were no symptoms and no recurrence of the bone tumor. In the present cases, three-dimensional computed tomography imaging was useful for diagnosing the flexor tendon avulsion, determining the preoperative identification the location of a ruptured tendon stump, and planning the operation to minimize the surgical wound. The recommended treatment for avulsion of the FDP tendon due to enchondroma is curettage, bone grafting of the resultant cavity, and reattachment of the tendon to ensure sufficient structural strength to permit secure fixation and early mobilization and, especially, to prevent flexion contracture of the finger because the stump of the flexor digitorum profundus is buried in the cavity of the distal phalanx.

J Nippon Med Sch 2012; 79: 79-84

Keywords
flexor digitorum profundus, avulsion, enchondroma, tendon rupture, three-dimensional computed tomography

Correspondence to
Mitsuhiko Nanno, Department of Orthopaedic Surgery, Nippon Medical School Musashi Kosugi Hospital, 1-396 Kosugi-cho, Nakahara-ku, Kawasaki, Kanagawa 211-8533, Japan
nanno-mi@ga2.so-net.ne.jp

Received, May 15, 2011
Accepted, August 3, 2011