gms | German Medical Science

Objectives/Interrogation: We introduced the relative motion splint concept at the 1995 IFSSH meeting in Finland, permitting active motion and functional use following long extensor tendon repair using relative motion extensor (RME) orthoses. Its use is now well established. We now present rationale and results using relative motion flexion (RMF) orthoses for acute boutonniere deformity, allowing use during healing, and the nonsurgical management of chronic deformity.

Methods: Cadaver and anatomic study show that placing the injured digit MP joint in 15-20 degrees' greater flexion than adjacent digits can transition a supple boutonniere deformity to full PIP extension by the quadriga effect, transmitting the increased EDC tension to full IP extension by the EDC lateral slips to the lateral bands, with simultaneous relaxation of the lumbrical volar pull by relaxed tension of the attached flexor profundus tendon. Acute injuries were splinted 6 weeks encouraging hand use and avoiding later therapy. Chronic boutonniere cases had serial casting of fixed PIP deformity to maximum extension (none worse than -20 degrees) maintained by 3 months of RMF orthosis use, with full flexion recovered.

Results and Conclusions: Since 2003, 8 acute (3 open) and 15 chronic cases are reviewed. Acute cases had supple PIP deformity and maintained full range of motion (minus 15 to 20 degrees MP extension) throughout 6 weeks of splinting without additional therapy. Chronic boutonniere patients treated an average of 40 months after injury had serial PIP casting to extension of 0 to -20 degrees, averaging -3 degrees. This required an average 2.5 weeks of casting. Thereafter therapy recovered full flexion, maintaining PIP extension in the splint for 3 months. Therapy visits averaged 7.5, with the most frequent complication broken orthoses from functional use. Initial joint contracture averaged -29 degrees, and the average improved PIP range of motion was 35.9 degrees, because several chronic boutonniere patients improved PIP flexion as well as extension. RMF splinting safely permits early active motion and hand use after boutonniere injury during 6 weeks of healing, obviating need for additional therapy. Serial PIP casting and use of RMF orthoses for 3 months obviated need for surgery in chronic boutonniere deformity, allowing functional use and minimal hand therapy once full flexion was recovered, other than to replace broken orthoses. These patients achieved an "excellent" Strickland classification for boutonniere deformity.