PURPOSE: To determine maximal outcome improvement (MOI) thresholds for patient-reported outcome measures and identify predictors of achieving them after autologous osteoperiosteal transplantation (AOPT) for cystic osteochondral lesions of the talus.
METHODS: Patients with Hepple V cystic osteochondral lesions of the talus who underwent AOPT from January 2010 to January 2023 and had a minimum follow-up of 24 months were retrospectively included. An anchor question was queried regarding satisfaction with current ankle status. The American Orthopaedic Foot and Ankle Society (AOFAS) score, visual analog scale (VAS), Ankle Activity Score (AAS), and Foot and Ankle Outcome Score (FAOS) were evaluated pre- and postoperatively. The minimal clinically important difference and patient acceptable symptom state were calculated using a distribution- and anchor-based method, respectively. MOI was defined as a patient-specific percentage of improvement normalized by the maximal possible improvement. MOI threshold for predicting patient satisfaction was determined by the optimal cutoff using receiver operating characteristic curve analysis. Predictors of achieving these thresholds were identified through multivariable logistic regression analysis.
RESULTS: In total, 124 patients were included, with a mean follow-up of 71.3 ± 36.9 months (range, 24.4-173.5 months). Among them, 101 (81.5%) were satisfied with current ankle status. Significant differences were observed in postoperative patient-reported outcome measures and improvements (P < .01) between the satisfied and dissatisfied groups, except for AOFAS improvement (P = .237). The proportions of patients exceeding the minimal clinically important difference were 97.6%, 100%, 90.3%, and 96.0% for AOFAS, VAS, AAS, and FAOS, whereas the proportions exceeding the patient acceptable symptom state were 70.2%, 49.2%, 56.5%, and 94.0%, respectively. MOI thresholds were 81.4%, 73.2%, 11.8%, and 64.0% for the AOFAS, VAS, AAS, and FAOS scores, respectively. MOIs for FAOS showed the highest predictive capacity for satisfaction with an area under the curve of 0.858. Increased body mass index (odds ratio = 0.884, P = .031) and double plugs (odds ratio = 3.512, P = .017) were associated with lower odds of achieving the MOI threshold for FAOS. Sex showed an insignificant correlation (odds ratio = 0.982, P = .306).
CONCLUSIONS: After primary AOPT for cystic osteochondral lesions of the talus, the MOI thresholds were 81.4%, 73.2%, 11.8%, and 64.0% for the AOFAS, VAS, AAS, and FAOS scores, respectively, with MOIs for FAOS showing the highest predictive capacity of predicting satisfaction. Increased body mass index and double plugs in AOPT were associated with reduced odds of achieving the MOI threshold for FAOS.
LEVEL OF EVIDENCE: Level IV, retrospective case series.
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