The effect of pre-operative tibio-talar alignment on patient reported outcomes in the mid-term following total ankle joint replacement for osteoarthritis

T. Karim, R. Jugdey, C. Purcell, S. Buttress, J. Barrie

Background: There is debate whether pre-operative tibio-talar (TT) mal-alignment in the coronal plane should be a contra-indication to total ankle joint replacement (TAR). This study aims to determine if, in the mid-term, there is a statistically significant difference between perceived levels of pain and function following TAR for osteoarthritis (OA) dependant on pre-operative TT alignment.

Methods: This retrospective cohort study identified 65 eligible individuals who underwent primary TAR for OA, without adjunct realignment procedure, in 2008 and 2009 at a specialist orthopaedic centre. Ethical procedures were followed, informed consent gained and participants grouped according to pre-operative alignment using a novel approach to measuring the radio-graphic TT angle (neutral group = < 5°, valgus group= >5° & varus group >5°). The EQ 5D-5L, Manchester-Oxford Foot Questionnaire (MOXFQ) and a visual analogue scale (VAS) of pain were used as patient reported outcome measures (PROMs) collected via postal questionnaire.

Results: Response rate was 67%. Mean TT angles within the groups were 2° neutral, 9° valgus and 9° varus. Median scores for the neutral, varus and valgus groups were as follows: EQ5D-5L index score = 0.71, 0.74 and 0.86, EQ5D-5L health score = 80, 75 and 70, MOXFQ = 16, 8 and 6.5 with VAS = 2.6, 1.2 and 1.3 respectively. PROM data was analysed using a non-parametric Kruskal-Wallis one-way analysis of variance test with a p value of < 0.08, in which the EQ5D-5L index score = 0.301, EQ5D-5L NRS = 0.874, MOXFQ = 0.294 and VAS = 0.452. No statistically significant difference was observed between the 3 groups. Inter-rater reliability of measuring TT angle was excellent with a correlation coefficient of 97%.

Conclusion: Moderate coronal plane pre-operative TT mal-alignment does not have a significant impact on patient reported outcomes in the mid-term following TAR should not be considered a contra-indication to surgery.