Abstract

MOONDA, Z; NORTJE, MB  and  DEY, R. Does the intra-operatively measured leg length correction compare to the post-operative radiograph in total hip replacement surgery?. SA orthop. j. [online]. 2020, vol.19, n.4, pp.206-211. ISSN 2309-8309.  http://dx.doi.org/10.17159/2309-8309/2020/v19n4a2.

BACKGROUND: This study aims to analyse the accuracy of the Vertical Measurement System™ (VMS) in assessing the leg length correction (LLC) during total hip arthroplasty (THA) by comparing the intra-operative measurements to the radiographic measurements obtained six weeks post-operatively Patients and methods: A prospective cohort study was conducted in which patients undergoing primary THA were enrolled at two centres in Cape Town, over a period of 19 weeks. THAs were performed by four surgeons. Pre-operative leg length discrepancy (LLD) measurements were obtained in 92 patients. The VMS was used to predict intra-operative LLC, and this measurement was compared to the post-operative LLC measured on the six-week follow-up X-ray. These measurements were statistically compared using the Mann-Whitney U test. RESULTS: The difference between the intra-operative VMS calculation and the six-week radiological measurement was not significant (p>0.05), with the difference in their mean values being 0.1±3.3 mm. In the cohort, 82% of the patients (n=75) were within 5 mm of the target LLC, and 96% of patients (n=88) were within 10 mm of the target LLC. The mean absolute residual LLD at six weeks was 3.2±3.1 mm. CONCLUSION: The intra-operative LLC measurement obtained using the VMS accurately predicts the six-week post-operative radiographic LLC measurement Level of evidence: Level 4

Keywords : total hip replacement; leg length discrepancy; leg length correction; vertical measurement system; comparative study; longitudinal study.

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