A Model for the Conservative Management of Mallet Finger

INTRODUCTION

Mallet finger deformity, a common condition, can lead to impaired function and cosmetic defect. Non-operative treatment is by splintage and there are many varieties of splint in use, some of which are complicated and others expensive. The Stack (Stack, 1969) and Abouna (Abouna, 1965) splints have been reported to give good results (Warren et al., 1988). The Stack splint is in common usage, but does not provide a good fit in all cases, due to variance in finger shape and sometimes due to swelling of the finger. This leads to sub-optimal compliance, poor finger hygiene and treatment failure (Maitra and Dorani, 1993). Use of both types of splint can produce substantial skin complications (Maitra and Dorani, 1993; Warren et al., 1988). This paper reports on the results of a custom-made thermoplastic splint.

PATIENTS AND METHODS

All mallet fingers presenting to the Accident and Emergency Department of our hospital between April 1999 and April 2000 were referred directly to the hand therapy unit. Table 1 shows the demographic and clinical data of the patients treated. Patients with mallet injuries to the thumb, open fractures and fractures involving more than one-third of the articular surface of the distal phalanx were excluded, though mallet fingers with simple abrasions were included, as the splint could be moulded to accommodate small dressings.

The same senior hand therapist (SB) saw all patients within 1 week of presentation to the Accident and Emergency department and made a custom-made mallet finger splint from 1.6 mm thick thermoplastic (Orfit Thermoplastics, Promedics, Blackburn, England). This ensured extension at the distal interphalangeal joint and allowed flexion of proximal interphalangeal joint of the finger. Elastic adhesive tape was used to secure the splint in place (Figs 1 and 2). The patients were given information on the nature of the injury and the time span of management. They were also taught to remove the splint and clean the skin as and when required. The patients were also provided with written advice (Appendix A).

Patients were reviewed at 1 week when adjustments to the splint were made, depending on the reduction in swelling and/or removal of dressing. They were reviewed again at 6 weeks when the splint was removed and the distal interphalangeal joint range of movement was assessed using a Rolyon finger goniometer (Smith and Nephew, London, UK). The strength of active distal interphalangeal joint extension was also assessed. If strong, the patient was instructed to use a band of elastic adhesive tape around the distal interphalangeal joint during the day and continue with the splint at night for 2 weeks. If there was an extension lag of more than 10° or poor active extension, the splint was continued for a further 2 weeks followed by night splinting for a further 2 weeks. At 12 weeks after the injury, outcome was assessed by measurement of range of movement using the same Rolyon finger goniometer. The best of three readings was recorded. The results were graded by the Abouna and Brown criteria (Abouna and Brown, 1968: Table 2).

RESULTS

Forty-two patients were enrolled during the study period. Of these, eight patients failed to complete follow-up and were excluded. Eight of the 34 patients had bony injuries with a mean articular surface area involvement of 10% (range, 6% to 21%) as measured on the lateral plain radiograph.

Thirty of 34 patients achieving a successful outcome and were improved according to Abouna’s system. There was no difference in the success rate between bony and tendinous injuries or between dominant and non-dominant hands. No complications were present at the completion of treatment. There were four failures: one had had a cerebrovascular accident affecting the injured side during treatment and three patients had abandoned the use of the splint within 6 weeks.

DISCUSSION

The results of this study are favourable in comparison to previous studies, with 30 of 34 patients achieving satisfactory results in comparison with 55% (Maitra and Dorani, 1993) and 50% (Warren et al., 1988) satisfactory results that have previously been reported according to the Abouna and Brown criteria. This suggests that a purpose-made splint applied and monitored by specialist hand therapists may be preferable to a standard splint.

A comparative study between a Stack splint and a custom-made perforated splint showed that there were significantly less complications with the custom-made splint group, which did not require regular removal for finger hygiene (Kinninmonth and Holburn, 1986). Our splint can be remoulded as required during follow-up, to make it more comfortable for the patient, and we feel that this led to good compliance. Also, the custom-made splint is cheap costing £0.22 compared with £1.58 for the popular Stack splint (Promedics, Blackburn, England).

The poor fit of the Stack splint may cause skin maceration and damage as a result of persistent moisture due to sweating in the splint and wetting of the hand during daily activities over a 6 to 8 week period (Maitra and Dorani, 1993; Stack, 1986). All patients in this series were taught to remove the custom-made thermoplastic splint whilst maintaining the distal interphalangeal joint in extension for a few minutes everyday. This allowed for washing and drying of the skin. There were no cases of skin maceration and patient compliance was high. At every follow-up, the splint was re-checked and remoulded if required, to allow for changes in size of the finger caused by the reduction of swelling. Strong emphasis was placed on the patient’s responsibility for their own finger, which produced good compliance and patient satisfaction.

Although there was open access to orthopaedic clinic, no patient required referral, thus reducing orthopaedic workload.

The management of these uncomplicated mallet fingers by the hand therapy team achieved satisfactory results. This evidence indicates that specialist hand therapists could treat mallet finger by themselves, providing that the patients fit the inclusion criteria for non-operative treatment.