RESEARCH REPORT PLATFORM PRESENTATION

IS LEG LENGTH INEQUALITY IMPORTANT AFTER TOTAL HIP REPLACEMENT? Beard D¹, Gill R¹, Andrew G², Nolan J³, Barker K⁴, Murray D¹; ¹Nuffield Dept Orthopaedic Surgery, University of Oxford, UK. ²Bangor Hospital, North Wales, UK. ³Norfolk & Norwich Hospitals Trust, Norwich, UK. ⁴Nuffield Orthopaedic Centre NHS Trust, Oxford, UK

PURPOSE: To document the incidence and influence on outcome of length leg discrepancy (LLD) after cemented total hip replacement (THR). In addition, contributory factors to the aetiology of this common post operative complication were investigated. RELEVANCE: Leg length discrepancy is a well known complication following THR. The true magnitude, and the cause, of LLD remains unknown as there are few studies documenting the incidence and potential mechanisms of undesirable limb shortening after THR. To what extent this problem influences functional outcome is also unknown. Physiotherapists are often required to treat the sequelae of this condition because of the effect on gait and functional activity. Increased understanding of the problem will help therapists in the management of this common complication. PARTICIPANTS: 1583 patients undergoing elective cemented THR were recruited to the Exeter Primary Outcomes Study (EPOS). All patients had all undergone cemented primary THR using the Exeter stem in seven different UK centres. Either an anterolateral (n=1143) or posterior (n=426) was used. METHODS: Data were collected prospectively by a research assistant in each centre. Various demographic data were assimilated including age, gender, BMI, grade of surgeon, type of anaesthetic. Standard validated outcome instruments were used including the Oxford Hip Questionnaire and Activity scores at one and two years. True leg length discrepancy was measured using the standard linear tape method from anterior superior iliac spine (ASIS) to medial malleolus. ANALYSIS: Descriptive methods were used for the frequency data. Outcome data were examined in two ways; 1) by comparing those with and without LLD (Mann Whitney) and 2) assessing the influence of LLD on specific activities (ANOVA with post hoc Tukey). A Chi square was used to examine the influence of anaesthetic type. RESULTS: 318 patients (20%) had a LLD ≥ 1cm whilst 74 of these (5%) had LLD of ≥ 2cm. There was a significant difference in Oxford Hip Score between patients with and without LLD. In terms of specific activities, patients with LLD found it more difficult to put on socks, ascend stairs and had more pain than those without. It was found that patients who underwent an epidural anaesthetic were more likely to have resultant and significant LLD after the operation than those who had a general anaesthetic. CONCLUSIONS: The incidence of LLD after cemented THR is higher than expected. This complication has a major influence on outcome and specific function of THR patients. Excessive muscle relaxation during an epidural anaesthetic may contribute to the generation of LLD. IMPLICATIONS: These results, from a large multi-centre cohort, indicate the need for increased vigilance by the rehabilitation team regarding leg length discrepancy after THR. Physiotherapy management after THR should include careful screening and the initiation of appropriate treatment for LLD. Intervention should include prosthetic referral and gait assessment/education as necessary. KEYWORDS: Hip, Leg, Length. FUNDING ACKNOWLEDGEMENTS: Stryker Howmedica Osteonics have provided funding for the EPOS study. The Oxford database group are thanked for their assistance. CONTACT: david.beard@ndos.ox.ac.uk

ETHICS COMMITTEE: COREC (Oxford) UK