Osteoarthritis of the first metatarsophalangeal joint: associated factors, clinical diagnosis, and treatment using viscosupplementation

Submission note: A thesis submitted in total fulfilment of the requirements for the degree of Doctor of Philosophy to the Musculoskeletal Research Centre, Department of Podiatry, Faculty of Health Sciences, La Trobe University, Bundoora.

This thesis comprises six related research projects investigating osteoarthritis (OA) of the first metatarsophalangeal joint (MTPJ), including (i) a systematic review of available research to determine factors associated with the presence of first MTPJ OA, (ii) a systematic review of available research to determine the optimum treatment(s) for first MTPJ OA, (iii) a study to determine the reliability of the TekScan MatScan system to accurately reproduce dynamic plantar pressures and forces, (iv) a study to determine if differences existed in dynamic plantar pressures between those with and without radiographically confirmed first MTPJ OA, (v) a study to determine the diagnostic accuracy of symptoms and clinical observations in the identification of radiographic OA in people presenting with first MTPJ pain, and (vi) a randomised controlled clinical trial evaluating the clinical efficacy of intra-articular hyaluronan (hylan G-F 20, Synvisc) against a placebo in the treatment of first MTPJ OA. Results indicate that (i) several radiographic measures of foot posture are associated with the presence of first MTPJ OA, including a dorsiflexed first metatarsal, a plantarflexed forefoot, wider first metatarsal and proximal phalanx, and a longer hallux, medial and lateral sesamoids, (ii) limited evidence exists to suggest an optimum treatment for first MTPJ OA, (iii) the TekScan MatScan system is a reliable measurement apparatus when assessing plantar pressures and forces, (iv) increased peak pressure and maximum force is evident under the hallux and lesser toes in people with radiographically confirmed first MTPJ OA, (v) several clinical symptoms and signs including first MTPJ pain during palpation, pain duration greater than 25 months, presence of a dorsal exostosis, hard end-feel, crepitus and less than 64 degrees of first MTPJ dorsiflexion display useful levels of diagnostic accuracy in identifying radiographic first MTPJ OA, (vi) up to a single 1 ml intra-articular injection of hylan G-F 20 (Synvisc) is no more effective than a placebo for the treatment of first MTPJ OA.