Introduction: To reduce the risk of oxidation without sacrificing the strength or wear properties of the polymer, vitamin E-diffused highly cross-linked polyethylene (HXLPE) was introduced. For the countersurface of the articulation couple, zirconia toughened alumina (ZTA) was invented to overcome the brittleness of alumina ceramic. The aim of this study was to compare the wear properties and the clinical outcomes of ZTA ceramic femoral head (Delta) on vitamin E diffused HXLPE liner with those of cobalt-chrome (CoCr) head for the Japanese female patients with a diagnosis of unilateral dysplastic coxarthritis.
Patients and methods: A total of 144 patients consented to participate in this blinded randomized controlled study in four Japanese hospitals. Finally, 65 patients in the CoCr group and 63 patients in the Delta group were included in the analysis. The center of the femoral head in the acetabular shell was measured within six weeks after the operation, at 1, 2 and 3 years using the Martell Hip Analysis Suite. Clinical outcomes were evaluated using Harris Hip Score (HHS), Western Ontario and McMaster University Osteoarthritis Index (WOMAC), UCLA Activity Score.
Results: The total femoral head penetration at three years was −0.02mm (IQR: −0.32, 0.29) in CoCr group, and 0.12mm (IQR: −0.32, 0.64) in Delta group. There was no difference between the two groups in terms of HHS, WOMAC, UCLA Activity Score.
Conclusions: The short-term wear of vitamin E diffused HXLPE with ZTA ceramic ball was similar to that with CoCr ball. Following the results of clinical outcomes, an advantage of ZTA ceramic ball on vitamin E diffused HXLPE was not recognized at three years postoperatively.
Introduction: A superior approach (SA) for the hip joint differs from other approaches on not taking over the range leg position. We investigated the rate of preservation of the short rotator muscles, intraoperative fractures (IOFs), and postoperative dislocations among patients who underwent hip arthroplasty using the SA. Additionally, we investigated factors associated with muscle-preserving total hip arthroplasty (THA).
Methods: The study included patients who underwent hip hemi-arthroplasty and THA using the SA between January 2016 and December 2019. We analyzed patient records to confirm IOFs and preservation vs. resection of the short rotator muscles. We recorded the postoperative dislocation rates until February 2020. We evaluated preoperative plain radiographs to measure the distance between the lesser trochanter and the ischium. Logistic regression analysis was used to analyze the factors associated with short rotator muscle preservation.
Results: Hip hemi-arthroplasty for femoral neck fractures was performed in 138 patients. The mean operation time was 64min. The mean intraoperative blood loss was 143g. IOFs occurred in 2 (1.4%) patients, and no dislocation occurred during follow-up. Primary THA was performed in 70 patients. The mean operation time was 108min. The mean intraoperative blood loss was 406g. The rate of short rotator muscle preservation was 65.7%. No IOFs were observed, and 2 (2.9%) patients developed dislocation during follow-up. Both patients with dislocations reported a history of rheumatoid arthritis, and dislocations were attributed to falls. Female sex (odds ratio [OR] 5.73, 95% confidence interval [CI] 1.26-26.0, p<0.05) and greater distance between the lesser trochanter and the ischium (OR 1.14, 95%CI 1.04-1.25, p<0.01) were associated with short rotator muscle preservation.
Conclusion: In all of the HAs and forty-six (65.7%) THAs, the piriformis and conjoint tendons were preserved. SA-HA would lead to lower rate of IOFs and postoperative dislocations.