A PROSPECTIVE STUDY OF A NOVEL TWO PIN TECHNIQUE OF PROXIMAL INTERPHALANGEAL JOINT FUSION OF LESSER TOES

Abstract

Introduction: Traditionally flexion deformities in Proximal Interphalangeal joints of lesser toes like hammer toes and curly toes are treated with fusing the PIP joint with a single Large Kwire. We describe a new technique of fusing PIP joints using two 1.1mm K wires.

The advantages of this technique over single K wire are:

1. Less post operative complications like pain and pin tract infection.

2. Achieving normal biomechanics of the foot by fixing the PIP joint at 15–20 degrees of flexion.

3. Using two K wires gives more rotational stability of the toes and reduces the complications of over riding, under riding and hyperextension of the toes.

4. 15–20 degrees flexion at PIP joint will give good digital purchase and push off in stance phase.

5. As the K wire engages the cortex of proximal phalanx, there is almost negligible chance of loosening of K wires which is a common problem in large single K wire which usually is driven in to the medullary cavity of proximal phalanx.

Aim: To compare the clinical and radiological outcomes in two pin fusions with standard single pin fusions described by Coughlin. To prove that this is a technically and biomechanical better procedure.

Materials and Methods: Two pin technique was used for 36 PIP joint fusions in 25 patients with a mean age of 58 years (range–42 to 87 years) and female preponderance. Results were analysed using foot function scale, AOFAS (American Orthopaedic Foot and Ankle Society) lesser metatarsophalageal-Interphalageal scale. Post operative complications were documented.

Technique: Dorsal skin incision was used to approach the PIP joint. Articular surfaces were prepared and two 1.1mm K wires were inserted from the tip of the toe and joint fixed in 15 – 20 degrees of flexion which is optimal functional position of PIP joint. Patients were mobilised non weight bearing for 6 weeks when K wires were removed and weight bearing started.

Results: The results were analysed at 3–6 months post operatively. The foot function scores and objective parameters of AOFAS scores are slightly better in two pin fusions compared with single pin fusions.

Objective parameters of AOFAS scale like adduction/ abduction, flexion, rotational deformities are significantly less with two wire fusions compared with single wire procedures (Coughlin et al). Radiological analysis of the foot showed that 97% had bony union compared 81% with single pin, and only 3% had fibrous union compared to 19% with single wire. Both the procedures didn’t have any non-unions. Only one patient had superficial wound infection, and surprisingly none had pin tract infection.

Conclusion: Two pin PIP Joint fusion is relatively easy procedure with many technical advantages over single pin technique. The clinical and radiological outcomes are good. Results of the biomechanical studies should be available soon.