CORRELATION OF A CLINICAL OUTCOME MEASUREMENT TO BIO-MECHANICAL ASSESSMENT IN SURGICALLY TREATED CLUBFEET

Abstract

The aim of this study was to correlate two outcome measurements of clubfoot surgery. A modified, partially subjective, clinical scoring system was compared with an objective biomechanical assessment, using the optical Dynamic Pedobarograph foot pressure system. The outcomes of the latter method were developed into a classification system for future prospective studies and to complement clinical evaluation of patients, especially those with relapse.

Many different functional outcome measures have been designed. Differing number of points are allocated to various subjective and objective items of relevance. The weighting given to each item in the overall score depends entirely on the importance the surgeon believes that particular item has on what he believes constitutes a good corrected clubfoot. This makes the scoring systems arbitrary and therefore results of clubfoot surgery between various centres impossible to compare. Sixteen patients [21 feet] were randomly selected from a poll of patients that had undergone clubfoot surgery. The operations were carried out by a single surgeon and consisted of a lateral-posteromedial peritalar release utilising the Cincinnati incision. Post-operatively, all feet were independently classified using a modified scoring system, based on the ones designed by Laaveg and Ponseti and the one by McKay, which scores both objective and subjective findings. This system has a good interobserver reproducibility. After finalisation of treatment, patients were referred to the Foot Pressure Analysis Clinic in Dundee where a novel method has been developed for the evaluation of clubfeet, using a static and dynamic foot pressure analysis system which provides both a graphical and analytical model for comparison. A pedobarographic classification system was developed. An excellent result entails that the patient does not require further treatment. A good result has been achieved if a near normal posture and pressure distribution is recorded. However, this means that there are still functional problems, which, as the foot matures, may lead to future relapse. These feet may therefore require long-term treatment with an orthotic support to let the foot develop its normal shape. A fair result requires major orthotic support of shoe adaptation, or further surgical releases. The correlation between clinical and biomechanical outcomes in the 21 feet was calculated using Kendall’s tau rank test for non-parametric data. The r value was 0.3524, which was significant [p< 0.05]

There is a significant correlation between the above mentioned outcome measurements. Biomechanical assessment cannot replace clinical evaluation, but can complement it and perhaps give a more subtle and earlier prediction of the need for further additional treatment. This technique has not only proven to be objective but also clinically valuable and cost effective. A prospective study to refine this biomechanical classification system into a reliable predictor of relapse in surgically corrected clubfeet is currently being considered.