Abstract
PurposeThe purpose of this prospective study was to analyze the impact of obesity on the clinical and radiological outcomes 6 years after open-wedge high tibial osteotomy (HTO).MethodsA total of 120 prospectively recorded patients with medial compartment osteoarthritis underwent open-wedge HTO between 2008 and 2011. The study cohort was frequently examined over a minimum of a 6-year follow-up. The cohort was divided into three groups according to body mass index (BMI): normal weight patients (BMI < 25 kg/m2), pre-obese patients (BMI 25–30 kg/m2) and obese patients (BMI > 30 kg/m2). Clinical and functional outcomes (Oxford Knee Score, Hospital for Special Surgery Score, Lequesne Score, Tegner Activity Scale), subjective health-related quality of life (SF-36), change in mechanical limb alignment (mTFA) as well as conversion to unicompartmental or total knee arthroplasty (TKA) were evaluated. To compare clinical scoring between the groups, univariate variance analysis was applied. Changes in outcome variables over time were analyzed with dependent t tests.ResultsFrom 120 patients, 85 were followed-up over a 6.7-year period on average (6–11.8 years) after HTO. The mean BMI was 28.6 ± 4.6 kg/m2. Each group showed a significant pre- to postoperative increase in all recorded scores (p < 0.05). In absolute terms, both mental and clinical scores of overweight patients did not reach the peak values of the normal weighted population during the period of observation. There was a conversion to TKA in 10.5% after an average of 50.1 ± 25.0 months following surgery. A total of five complications occurred without significant differences (BMI < 25: n = 1, BMI 25–30: n = 2, BMI > 30: n = 2; n.s.). There was a mean pre- to postoperative (six weeks after surgery) correction difference of 6.9° ± 3.2° (mTFA) with higher loss of correction over time in overweight patients.ConclusionIn terms of clinical outcome and health-related quality of life, overweight patients may receive a benefit from open-wedge HTO to the same extent as patients with normal weights and show similar complication rates. However, they have inferior preoperative clinical and functional results and mid-term results after open-wedge HTO compared to patients with normal weights.Level of evidenceLevel III.
Highlights
Medial open-wedge high tibial osteotomy (HTO) using an angular locking plate system as described by Staubli et al [35] as well as Lobenhoffer and Agneskirchner [23] has been reported to achieve good to excellent mid- to long-term results with low complication rates [4, 35].Several studies have investigated the potential risk factors that lead to inferior subjective and functional outcomes after HTO surgery
No significant differences were observed between the body mass index (BMI) groups for the recorded characteristics
Considering the inferior preoperative clinical scores and health-related quality of life (HRQL) of obese patients, the present study revealed an improvement after open-wedge HTO to the same extent as the patients
Summary
Several studies have investigated the potential risk factors that lead to inferior subjective and functional outcomes after HTO surgery. Female sex [12, 37], mental illness, impaired psychological situation, and previous surgeries were found to be risk factors for poorer surgical outcome [20, 27, 31, 37]. Obesity is known as a major risk factor for complications and impaired clinical outcome following different types of knee surgery [1, 15]. Studies on unicompartmental knee arthroplasty have found a fivefold increase in failure rate in morbidly obese patients due to disease progression in other compartments or mobile bearing instability [26]
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