Investigation of the differences in foot and ankle characteristics of patients with lower limb osteoarthritis : implications for clinical practice
To date, the foot posture of patients with lower limb osteoarthritis (OA) has not been explored from an orthopaedic perspective. In other medical fields such as neurology and sports medicine, a relationship between foot posture, gait and pathology has been acknowledged. In view of the current high incidence of lower limb OA, investigation of any differences in foot posture in patients with lower limb OA that may lead to improved assessment and conservative management is worthy of consideration. The first component of the thesis investigated a clinically observed difference in the foot posture of 60 patients with hip OA, 60 patients with medial compartment osteoarthritis of the knee (MCOA) and 60 healthy volunteers using an observational study. A significant difference in foot characteristics was demonstrated. Patients with hip OA demonstrated a lack of dorsiflexion and a greater degree of calcaneal inversion, presenting with a supinated foot. Patients with MCOA demonstrated ample dorsiflexion and a greater degree of calcaneal eversion, presenting with a pronated foot. In general, the healthy volunteers demonstrated average dorsiflexion and average calcaneal eversion and this gave the appearance of a normal foot. This did not, however, provide evidence of any causal relationship. A pre and post operative observational study of 55 patients with MCOA who underwent the Oxford unicompartmental knee arthroplasty was then undertaken. As a result of this surgery there is a major correction of varus to valgus knee orientation which is significant clinically and statistically. Although there is a major change in knee orientation, this study showed that the foot posture was not altered. This study also does not provide evidence that foot posture is causal in the development of MCOA. It does, however, give an indication of the robustness of the foot postures of these patients. The second component of the thesis was concerned with clinical outcome measures for the assessment of foot posture in patients with lower limb OA. Currently there is no standard practice for physiotherapists. Routine examination of the foot is rare. Two systems of measurement: (a) The Foot Posture Index and (b) the F-Scan in-shoe pressure measurement system were examined in detail with a cohort of patients with lower limb osteoarthritis. The two measurement systems were found to be useful in a clinical setting and sensitive enough to support the findings in Component 1 of the thesis. In addition, the use of the Foot Posture Index score allowed investigation of the relationship between foot posture and talocrural dorsiflexion. A high degree of talocrural dorsiflexion corresponds with a positive FPI score indicating a pronated foot. A low degree of dorsiflexion corresponds with a negative FPI score indicating a supinated foot. This is the first time that talocrural dorsiflexion has been shown to be associated with foot posture, although previously it has been accepted anecdotally in clinical podiatry. The third component was a systematic review which explored the current clinical practice of using lateral wedges in the conservative management of MCOA by orthopaedic surgeons. This contrasts with the use of medial wedges in the world of sports medicine, physiotherapy and podiatry to correct over-pronation problems. As the foot posture of patients with MCOA had been shown to be pronated, it was felt necessary to examine the evidence for the use of lateral wedges. The systematic review found no strong evidence to support the use of lateral wedges in the conservative management of MCOA. Finally, the main findings of the thesis are discussed, the findings summarised and suggestions made for clinical practice and further research.
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