Higher Age is Associated with Lower Likelihood of Conversion to Surgery after Primary Nonoperative Treatment for Osteochondral Lesions of the Talus

IntroductionThe first line of treatment for osteochondral lesions of the talus (OLT) is nonoperative. To date, there is limited evidence on risk factors that may influence conversion to surgery after primary nonoperative treatment for symptomatic OLTs. The aim of this study was therefore to identify risk factors for conversion to surgery after initial nonoperative treatment of OLTs.Methods For this cohort study, patients with a primary OLT who were nonoperatively treated for at least 6 months between 1990 and 2020 were included. Univariable Cox regression analysis, resulting in hazard ratios (HRs), on the primary outcome (i.e. conversion to surgery after initial nonoperative treatment) was performed for potential risk factors. The following risk factors were analyzed: gender, age, body mass index (BMI), numeric rating scale (NRS), lesion size (depth, sagittal length, coronal length, volume, surface), lesion morphology (presence of fragments and presence of cysts), lesion location (medial/central/lateral), congruency of the ankle joint and trauma in history. Data imputation was conducted according to the multiple data principle with pooling.Results Forty-two patients with primary OLTs were included in this study: 23 (55%) males and 19 (45%) females with a mean age of 39.1 (SD: 14.2). The median overall follow-up time was 66 months (range: 7-188). Around 23% of the patients had a conversion to surgery at the median observation time. The Kaplan-Meier analysis revealed a survival rate of 93% (95% confidence interval [CI]:84-100), 90% (95% CI: 81-99), and 77% (95% CI: 63-91) at 1, 2, and 5 years after the initiation of treatment, respectively. After performing the COX regression analysis, age was the sole risk factor significantly associated with conversion to surgery with an HR of 0.93 (95% CI: 0.87-0.99). The different HRs for all other risk factors were as follows: gender: 0.33 (95% CI: 0.08-1.34), BMI: 0.87 (95% CI 0.76-1.01), depth: 0.97 (95% CI: 0.79-1.18), coronal length: 1.19 (95% CI: 0.97-1.44), sagittal length: 0.98 (95% CI: 0.87-1.12), surface area: 1.17 (95% CI: 0.41-3.31), volume: 0.96 (95% CI: 0.24-3.91), presence of fragments: 4.17 (95% CI: 0.84-20.61).Conclusion For primary OLTs, 77% of the patients were successfully treated nonoperatively at a median follow-up of 66 months without the need for a surgical intervention. Survival rates of 93%, 90%, and 77% were found at 1, 2, and 5 years after the initiation of treatment, respectively. We found that a higher age at the moment of diagnosis was significantly associated with a lower likelihood of conversion to surgery with a 7% decrease of likelihood each year the patient is older at the moment of diagnosis. The findings of this study are clinically relevant as it ameliorates the quality of the shared decision-making process between the patient and the treating team as we can advise OLT patients at a higher age with tolerable symptomatology that there is a relatively lower risk of conversion to surgery.