Travmatologiâ i Ortopediâ Rossii (Apr 2018)

IMPACT OF VARIOUS FACTORS ON THE POLYETHYLENE WEAR RATE IN TOTAL HIP ARTHROPLASTY

  • R. M. Tikhilov,
  • M. I. Shubnyakov,
  • A. A. Boyarov,
  • A. O. Denisov,
  • I. I. Shubnyakov

DOI
https://doi.org/10.21823/2311-2905-2018-24-1-18-28
Journal volume & issue
Vol. 24, no. 1
pp. 18 – 28

Abstract

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Purpose of the study — to determine the rate of polyethylene wear in hip arthroplasty depending on various factors and to evaluate a correlation of wear rate and motor activity of the patient.Material and methods. 467 patients with coxarthrosis were included in the study with gender distribution of 322 (35.8%) women and 145 (31.0%) men. Mean age of patients was 55.0 years without statistically significant variances in women and men (р = 0,743). Daily motor activity of 167 patients (35.8%) was assessed using pedometer. The authors evaluated prosthesis head displacement in relation to the center of acetabulum and calculated the rate of polyethylene wear in MediCad. Modified Harris Hip Score and VAS parameters were evaluated for all patients. All data was analyzed and statistical processed.Results. Average level of motor activity was more than 1.9 million steps per year. The overall rate of polyethylene wear depended on the follow up period, the Pearson correlation coefficient r = 0.297 (р<0,001). Mean wear rate was 0,16 mm/year (95% CI 0.15–0.17). At the same time wear rate significantly differed in the groups of standard and cross-link polyethylene, namely 0.18 mm/year (95% CI 0.17–0.19) and 0.11 mm/year (95% CI 0.1–0.11) (р<0.001). The authors identified the following additional factors affecting wear rate in the present study: cup inclination angle, r = 0.241 (р = 0.002), and the level of motor activity, r = 0.574 (р<0.001). No evident correlation of wear rate to age, r = 0.14 (р = 0.859), and to BMI, r = -0.094 (р = 0.226), was identified, which apparently is due to a strong impact of mixing factors. Patients’ satisfaction with treatment outcomes was assessed by VAS score and in average was 91,1 points (95% CI 90.3–91.9). Harris Hip Score parameters improved in average from 36.5 (95% CI 35.1–37.9) up to 91.6 points (95% CI 91.1–92.0).Conclusion. Out of the multiple factors affecting the polyethylene wear rate only the inclination angle of acetabular component and a higher level of patient motor activity have proven to be statistically significant.

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