Purpose: In the modern political climate our practice is increasingly being compared with that of our peers. Outcome measures will form the basis of this. Good outcome measures have two essential requirements; they should be valid and reliable. Outcome measures are not easy to construct. Traditionally subjective walking distances have formed a portion of the assessment. This has never been validated.

Method: Null hypothesis - patients can accurately estimate their actual walking distance.

After gaining COREC approval we compared the objective to subjective walking distance of patients who had sustained a fractured Os Calcis over the past two years and were allowed to full weight bear. Patients were assessed by a senior physiotherapist and Doctor. Both the American Orthopaedic Foot and Ankle Score and Maryland Score were performed. Patients were asked to estimate their maximum walking distance prior to objective treadmill assessment.

Results: 20 patients, 6 female and 14 male were assessed. Average age was 67yrs (range 46–83yrs). One patient was excluded as they were breathless at rest. Good correlation was found between the subjective walking assessments of the two scores. All patients’ uniformly over estimated their walking ability. This was a highly significant difference, p-value 0.002. Therefore the null hypothesis has been disproved; patients’ subjective walking distance is inaccurate.

Significance: Walking distance assessment is used is as a measure in many fields of orthopaedics namely foot and ankle outcome measures and lower limb arthroplasty. This study has shown it to be an inaccurate method. It also highlights the need to validate all outcome measures.