Authors (including presenting author) :
Lo HTS (1), Chan PS (2)
Affiliation :
(1) Occupational Therapy Department, Prince of Wales Hospital
Introduction :
Mallet injury means the tear or rupture of terminal slip or avulsion fracture of the base of distal phalanx. It can be classified by Dolye's Classification according to the injury nature. Conservative treatment is usually adopted for closed injury and bony mallet in Doyle I. However, it is still inconclusive which splint design is of superiority. Current global standard is usually splinting of DIPJ in extension or hyperextension for at least 6 weeks, followed by nocturnal splint.
Objectives :
According to extensor hood anatomy, flexing PIPJ would relax lateral bands and induce less stress on terminal slip. Based on it, a thermoplastic splint is made to flex PIPJ with DIPJ in extension for initial 2 weeks, aiming to reduce stress over lateral bands. Then followed by another splint to immobilize DIPJ for 4 to 6 weeks. This retrospective study aimed to evaluate the effectiveness of the mentioned splint program in treating mallet injury and factors contributing to outcomes.
Methodology :
Patients discharged between 2017 and 2019 were screened. Patients completed the mallet splint program were included. 58 patients were eligible for data analysis. DIPJ extension lag was the primary outcome. Greenhouse-Geisser test was used to analyze the treatment effect over time. Grip power and presence of swan-neck deformity were also analyzed. Correlations of DIPJ extension gain and different factors were analyzed by Pearson’s coefficient.
Result & Outcome :
There was a significant improvement over DIPJ extension lag (p< 0.05) from 31.1 degree to 13.2 degree at 3-month follow up. According to Cochrane review, DIPJ extension gain ranged from 16 degree to 20 degree after 12-week DIPJ splinting program. Our local splinting program resulted in 17.5 degree of DIPJ extension gain, which met the international standard. Patients could achieve a mean of 84.6% of grip strength when comparing with the unaffected side when program completed. Swan-neck deformity is a common secondary lesion due to tendon imbalance. In our sample, 6 (10.3%)of them developed swan-neck deformity upon discharge. General joints laxity and splint compliance issues might account for the development of such deformity. Significant correlation was found between initial extension lag and extension gain. There were no associations between age and delayed treatment with final outcomes. People used to believe that a small initial extension loss had a better outcome than those with a more severe extension loss. From our result, for those with greater initial extension lag could gain more extension. This may be the merit of our splint program as we position PIPJ in flexion at initial phase. A recent systematic review commented that increased edema and age and decreased patient adherence seem to negatively influence DIPJ extension gain. In our review, age was also found a negative relation with DIPJ extension gain, but statistical insignificant. Discrepancy of our study results might due to small sample size. To conclude, the locally developed splint program is effective in treating mallet fingers, comparable to global practice. Future randomized clinical trial, comparing our splint program with conventional DIPJ splint, could provide give more insight in mallet fingers treatment.
