FIRST METATARSOPHALANGEAL JOINT ARTHRODESIS – A NEW TECHNIQUE USING MEMORY COMPRESSION STAPLES.

Abstract

Arthrodesis of the first metatarsophalangeal joint (MTPJ) has been recommended for various big toe deformities. We present a new technique of internal fixation for achieving dynamic compression at the first metatarso-phalangeal joint arthrodesis using memory compression staples. The memory compression staple is fabricated from equiatomic Nickel-Titanium (Ni-Ti) alloy. This alloy has a property by virtue of which it becomes easily malleable at a low temperature and reverts back to its original shape at a higher temperature. This property is known as the Shape Memory Effect. This principle is employed to provide compression at the arthrodesis site. Thirty feet were operated in 27 patients. There were 24 females and 3 males with a mean age of 61.2 years. Two memory compression staples were used at right angles to each other to achieve compression at the fusion site. The post-operative regime allowed full weight-bearing in a rigid sole shoe. A standard questionnaire was used for the subjective assessment, which included questions regarding level of pain, ambulation and patient satisfaction. Objective assessment was performed by a clinical and a radiological examination. Post-operatively there was a reduction in the pain score from 4.6 to 1.6 (p< 0.0001). Ambulation ability improved from 4 to 2.5 (p< 0.0001). There was 96.7% of radiological fusion with an average fusion time of 8.2 weeks. Patients reported 86.6% excellent to good results. The only significant post-operative complication was a single non-union.

We advocate memory compression staples for the internal fixation of the first metatarsophalangeal joint arthrodesis, which is a low profile implant, does not require post-operative cast immobilisation and has a predictable success rate comparable to previously reported methods.