Correction of a fixed flexion deformity of the PIP joint requires:
- excision of enough bone to reduce the deformity
- stabilisation to allow healing
Either a simple excision arthroplasty, removing the condyles of the proximal phalanx, or a fusion with bone removed from bothe sides of the joint, can achieve this.
A technique of shaping the end of the proximal phalanx into a peg, which fits a hole in the middle phalanx, has been described (Alvine 1980, Lehman 1995). Although 95% of Lehman’s, and 97% of Alvine’s attempted arthrodesis fused, 13-15% of patients were still dissatisfied, due to malalignment, continued pain and shoewear restrictions. Lamm (2001) found no difference between the failure rate of end-to-end and peg-in-hole techniques; most failures occurred in the second toe. Caterini (2004) stabilised the fusion with a cannulated intramedullary screw in 51 toes in 24 patients. The union rate was 96%; seven screws were removed for tip pain and one toe had a malalignment. Two patients found the toe “too straight”.
Konkel (2007 described the use of an absorbable PDS pin to stabilise the toe. This avoided metal allergies and there was no protruding wire to be removed. Konkel reported satisfactory results in 91% of 48 toes, with 10 malaligned toes, 9 floating toes and 9 fibrous unions. There were no reactions to the PDS pin.
Coughlin (2000) reported the largest series of resection arthroplasties: 118 toes in 63 patients. 81% if resection arthroplasties, in fact, fused. 84% of patients were satisfied with symptom relief; the main causes of dissatisfaction were malalignment and numbness. There was no difference in satisfaction between fused and non-fused toes. 23% of toes did not touch the ground in stance. O’Kane and Kilmartin (2005) reported 100 second toe PIP arthroplasties in 75 patients. O’Kane stabilised the toe simply with an extensor tenodesis (Coughlin used a metal pin). The mean AOFAS score was 93/100 and mean patient satisfaction score 9.1/10. There were seven slightly symptomatic floating toes.
Overall, the clinical results of fusion and excision arthroplasty are similar. While higher fusion rates can be obtained with very precise prepapration and more stable fixation, it is not clear this makes a difference to patient outcomes. Surprisingly for such a common procedure, no randomised controlled trials have compared techniques and this would be useful.