First MTPJ arthrodesis is it fused and how do we know?

A. Isaacson, A. Cattell, A. Bing

Introduction: First MTPJ arthrodesis is a treatment of arthritis, hallux valgus and hallux rigidus. However, nonunion is a common complication (3.2-12%). Post-operative management of patients requires assessment of healing to guide post-operative rehabilitation and recovery. This demands radiographical assessment of union be both reliable and reproducible.

Aim: To determine the complication and non-union rate in patients undergoing first MTPJ arthrodesis at the Robert Jones and Agnes Hunt Hospital and to determine most reliable method of assessing union on plain radiographs.

Method: 124 patients undergoing isolated primary first MTPJ arthrodesis between 2008 and 2013 were identified. Clinical data of all follow up and outcomes were collected until the patient was discharged. The union rate was compare to the standard reported in the literature (3.2-12%). Post operative radiographs were reviewed independently by two orthopaedic registrars and scored according to the criteria proposed by Hammer et al (1984). An unweighted Cohens Kappa for 2 raters was used to assess interobserver reliability.

Results: 80% of patients achieved MTPJ arthrodesis with no significant complications and the average patient is discharge at 5 months. The non-union rate was 9.7 % (7% required revision surgery) and a further 8.9% required further surgery to remove metalwork. Radiographic assessment of union at 6 weeks shows only moderate inter-observer agreement. At 12 weeks the clinician´s general impression or the number of cortices with a fracture line evident show substantial inter- observer agreement.

Conclusion: First MTPJ arthrodesis is a reliable treatment option however, it is important to counsel patients about the possible complications and the recovery period (approx. 5 months). Clinicians should not use the 6 weeks radiographical assessment alone to determine ongoing rehabilitation. 12 weeks radiographical assessment provide a more reliable assessment of union. This study would, therefore, strongly support all patients receiving a 12 week radiographical assessment prior to discharge.