Abstract
BackgroundHallux valgus (HV) is a common condition involving the progressive subluxation of the first metatarsophalangeal joint due to lateral deviation of the hallux and medial deviation of the first metatarsal. The objective of this study was to evaluate the re-test reliability and validity of self-assessment of HV using a simple clinical screening tool involving four standardised photographs (the Manchester scale), in order to determine whether this tool could be used for postal surveys of the condition.MethodsHV was assessed with the Manchester scale in 138 people aged 65 to 93 years of age (102 women and 36 men) as part of a larger randomised controlled trial. At the six month follow-up assessment, HV was reassessed to determine re-test reliability, and participants were asked to self-assess their degree of HV independent of the examiners. Associations between (i) baseline and follow-up assessments of the examiners and (ii) participant and examiner assessments were performed using weighted kappa statistics. Analyses were then repeated after HV was dichotomised as present or absent using unweighted kappa, and sensitivity and specificity of self-assessment of HV was determined.ResultsRe-test reliability of the examiners was substantial to almost perfect (weighted kappa = 0.78 to 0.90), and there was a substantial level of agreement between observations of the participants and the examiners (weighted kappa = 0.71 to 0.80). Overall, there was a slight tendency for participants to rate their HV as less severe than the examiners. When the Manchester scale scores were dichotomised, agreement was substantial to almost perfect for both re-test comparisons (kappa = 0.80 to 0.89) and substantial for comparisons between participants and examiners (kappa = 0.64 to 0.76). The sensitivity and specificity of self-assessment of HV using the dichotomous scale were 85 and 88%, respectively.ConclusionsThe Manchester scale demonstrates high re-test reliability, and self-assessment scores obtained by participants are strongly associated with scores obtained by examiners. These findings indicate that the tool can be used with confidence in postal surveys to document the presence and severity of HV.Trial registrationACTRN12608000065392
Highlights
Hallux valgus (HV) is a common condition involving the progressive subluxation of the first metatarsophalangeal joint due to lateral deviation of the hallux and medial deviation of the first metatarsal
Hallux valgus (HV) is a common condition affecting the forefoot in which the first metatarsophalangeal joint is progressively subluxed due to the lateral deviation of the hallux and medial deviation of the first metatarsal [1]
HV was dichotomised using the Manchester scale by merging the first two categories to indicate that HV was absent, and merging the second two categories to indicate that HV was present. This cut-off was based on our previous study where we found that the mean hallux abductus angle obtained from radiographs for participants with a Manchester scale score of 2 was approximately 15 degrees [28], which is the commonly accepted minimum value for the diagnosis of HV [21,22]
Summary
Hallux valgus (HV) is a common condition involving the progressive subluxation of the first metatarsophalangeal joint due to lateral deviation of the hallux and medial deviation of the first metatarsal. HV is generally considered to be present when the angle formed by the bisections of the first metatarsal and the proximal phalanx obtained from foot radiographs is greater than 15 degrees [21,22] Because it is not always feasible or necessary to obtain radiographs to assess HV, several other approaches have been suggested, including goniometric assessment, measurement of forefoot girth, and the use of standardised photographs or line drawings [23,24,25,26]. Roddy et al [26] developed an instrument consisting of five line drawings, each drawing illustrating a sequential increase in the HV angle of approximately 15 degrees This tool has been shown to have excellent re-test reliability (kappa = 0.82)
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