Proximal fibular osteotomy to treat medial compartment knee osteoarthritis: Preoperational factors for short-term prognosis

Objective The purpose of this study was to determine the association between preoperational factors and patients' short-term outcome after proximal fibular osteotomy (PFO) and to provide a basis for detailed surgical indication and patient selection. Methods This was a retrospective study of patients undergoing PFO between January 2015 and December 2015. Preoperational clinical data including gender, age, duration of disease, visual analogue score (VAS) and American Knee Society (KSS) score were collected. The radiological factors including hip-knee-ankle angle (HKA angle), condyle-plateau angle (CP angle), Kellgren and Lawrence grade (KL grade), joint space width of both compartments and settlement value were also considered. Patients were followed for at 12 months postoperatively. Both clinical and functional KSS scores were obtained. The outcome of interest was divided into clinical outcome and functional outcome. For each, two criteria were defined: satisfaction and significant improvement. Satisfaction is characterized by a KSS clinical or functional score over 70 points (excellent and good results); significant improvement refers to an increase in KSS scores of more than 15 points. Bivariate logistic regression for the association between preoperational factors and outcomes of interest was performed. Multivariable logistic regression analyses were used to detect the independent factors affecting the outcomes. Results A total of 84 patients and 111 knees were followed-up. Of these, 17 knees were from males and 94 were from females. The average age was 59.45 +/- 8.82 years. The average preoperational VAS score, KSS clinical and functional score were 7.08 +/- 1.41 points, 49.14 +/- 10.95 points and 44.97 +/- 17.71 points, respectively. According to KL grading, there were 17 knees of grade 2, 47 knees of grade 3, and 47 knees of grade 4. In clinical outcomes, there were 51 knees in the satisfaction group and 77 knees in the significant improvement group. In functional outcomes, 43 knees were in the satisfaction group and 76 knees in the significant improvement group. KSS clinical score (OR = 1.134, 95%CI= 1.067-1.205, P = 0.000) was the independent factor associated with clinical satisfaction. Age (OR = 1.072, 95%CI= 1.000-1.150, P = 0.048), VAS score (OR = 1.679, 95%CI= 1.041-2.706, P = 0.033), KSS clinical (OR = 1.072, 95%CI = 1.005-1.144, P = 0.034) and functional (OR = 1.100, 95%CI = 1.044-1.159, P = 0.000) score, HKA angle (OR = 1.345, 95%CI = 1.119-1.617, P = 0.002) and settlement value (OR = 7.540, 95%CI = 1.307-43.484, P = 0.024) were the independent factors associated with functional satisfaction. KSS clinical (OR = 0.905, 95%CI = 0.8500.963, P = 0.002) score, CP angle (OR = 0.760, 95%CI = 0.593-0.973, P = 0.030) and medial joint space width (OR = 0.001, 95%CI = 0.000-0.107, P = 0.003) were the independent factors associated with significant clinical improvement; VAS score (OR = 1.582, 95%CI = 1.042-2.402, P = 0.031), KSS functional (OR = 0.888, 95%CI = 0.838-0.942, P = 0.000) score, HKA angle (OR = 1.292, 95%CI = 1.101-1.518, P = 0.002) and settlement value (OR = 9.990, 95%CI = 1.485-67.197, P = 0.018) were the independent factors associated with significant functional improvement. Conclusions The independent factors affecting postoperative clinical outcome after PFO were KSS clinical score, CP angle and medial joint space width. In addition, the independent factors that influenced functional outcome included age, VAS score, KSS score, HKA angle and settlement value. As objective radiological evidence, HKA angle and settlement value could be used as an important basis for patient selection for PFO.