Objectives Opening-wedge high tibia osteotomies (HTO) can be technically challenging. The HTO iBalance system was designed to reduce vascular complications and to avoid secondary plate removal. The purpose of the study was to evaluate the performance of the HTO iBalance system in patients with symptomatic medial osteoarthritis and varus malalignment.
Methods The study was performed as a retrospective cohort study investigating a consecutive series of patients who underwent HTO with the iBalance system performed by a single surgeon from August 2013 to March 2016 at Zealand University Hospital, Koege, and Aleris-Hamlet Hospital. The primary outcome was the degree of realignment. The secondary outcome was Knee injury and Osteoarthritis Outcome Score (KOOS). Follow-up was performed at mean (SD) 25 (9.7) months. Weight-bearing long-leg standing radiographs were taken before surgery and at follow-up. Failure was defined as collapse of the HTO defined as a correction <50% of the intended correction at time of follow-up. Logistic regression was used to identify risk factors for failure.
Results 44 patients and a total of 47 knees were included in this study. Preoperatively the mechanical axis was a mean (SD) 5.8° (2.9) varus and postoperatively 2.3° (3.7) varus . The HTO failed in 13 of 47 knees (28%). Patients with failure showed no statistically significant differences to non-failure in any KOOS subscore (p>0.05). American Society of Anesthesiologists (ASA) score (p=0.01) and body mass index (BMI) (p=0.05) were correlated with failure, whereas bone transplantation and smoking were not.
Conclusion In this study, the failure rate of HTO was 28%. High BMI and ASA-score were the only risk factors associated with failure while bone grafting and smoking were not.
Level of evidence Retrospective cohort study, level III.
- lower extremity
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Contributors MIH, LB and KWB conceived idea for the study. MIH, JS and NK acquired the data for the work. All authors contributed to the analysis and the interpretation of data. MIH wrote the manuscript in close cooperation with KWB. All authors have critically revised the manuscript and have agreed to the final version.
Funding All X-rays were financially supported by Arthrex. The company had no influence on study design, data collection and result interpretation.
Competing interests MIH, NK, JS and KWB declare to have no conflict of interest. LB is a paid consultant for Arthrex.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information. The study, REG-33-2016: 'High tibial osteotomy performed with PEEK implant demonstrated a failure rate of 28%—a retrospective cohort study' has been approved by Region Zealand 'Health Scientific Research' in accordance to the Danish Data Protection Agency. The Data Availability Statement number is 2008-58-0020.The main author has the responsibility for the project's information. Electronic data are stored on team site in Sharepoint, under Region Zealand and in EasyTrial.
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