[Short-term effectiveness of Kirschner wire elastic fixation in treatment of Doyle type Ⅰ and Ⅱ mallet finger].

OBJECTIVE: To evaluate the short-term effectiveness of Kirschner wire (K-wire) elastic fixation in the treatment of Doyle type Ⅰ and Ⅱ mallet finger.

METHODS: Between July 2016 and March 2017, 18 patients with Doyle type Ⅰ and Ⅱ mallet finger were treated. There were 12 males and 6 males, with an average age of 45 years (range, 16-61 years). The index finger was involved in 2 cases, the middle finger in 3 cases, the ring finger in 10 cases, and the little finger in 3 cases. The interval from injury to operation ranged from 2 hours to 45 days (median, 5.5 hours). There were 8 patients of closed wound and 10 patients of open wound. Fourteen patients were simply extensor tendon rupture and 4 were extensor tendon rupture complicated with avulsion fracture. The distal interphalangeal joints (DIPJ) of injured fingers were elastically fixed with the K-wire at mild dorsal extend position. The K-wire was removed after 6 weeks, and the functional training started.

RESULTS: The operation time was 34-53 minutes (mean, 38.9 minutes). Patients were followed up 3-8 months (mean, 5 months). All incisions healed primarily and no K-wire loosening or infection happened during the period of fixation. All mallet fingers were corrected. The range of motion (ROM) in terms of active flexion of injured DIPJ was (75.83±11.15)° at 6 weeks after operation, showing significant difference when compared with the normal DIPJ of contralateral finger [(85.28±6.06)°] ( t =3.158, P =0.003). The ROM in terms of active flexion was (82.67±6.78)° in 15 patients who were followed up at 8 months after operation, showing no significant difference when compared with the normal DIPJ of contralateral finger [(86.00±5.73)°] ( t =1.454, P =0.157). After the removal of K-wire at 6 weeks, visual analogue scale (VAS) score of active flexion and of passive flexion to maximum angle were 1.78±0.88 and 3.06±1.06, respectively. According to the total active motion criteria, the effectiveness was rated as excellent in 10 cases, good in 5 cases, moderate in 2 cases, and poor in 1 case, and the excellent and good rate was 83.33%. The patients' satisfaction were accessed by Likert scale, which were 3-5 (mean, 4.2).

CONCLUSION: K-wire elastic fixation in the treatment of Doyle typeⅠand Ⅱ mallet finger can repair the extensor effectively, correct the mallet finger deformity, and also be benefit for the flexion-extension function restoration of DIPJ.