Percutaneous Chevron Akin (PECA) Correction of Hallux Valgus Deformity: Analysis of the Learning Curve

CATEGORY: Bunion INTRODUCTION/PURPOSE: Percutaneous hallux valgus correction is increasing in popularity, with good correction of deformity and improvement in outcomes. The learning curve is reported as steep, based on arbitrary analysis. METHODS: We performed a prospective study of a single surgeon series on the 1st 58 feet in 53 patients undergoing PECA hallux valgus correction, following cadaveric training and surgical observation. Pre- & post-operative (6 month) hallux valgus angles (HVA) & 1-2 intermetatarsal angles (IMA) were measured on weight bearing radiographs. Tourniquet time & number of fluoroscopy images were recorded. Complications were analysed. Parametric data was described with mean+-SD & non- parametric data with median+-interquartile range. Unpaired 2-tailed t tests were used to compare continuous data. The learning curve was calculated by plotting the tourniquet time against case number using a smoothed cubic spline with straight lines fitted to the slope. This was used to define a learning phase & a plateau phase. RESULTS: Median age was 62 (IQR 56-66). The mean HVA improved from 32°+-4.7 to 9°--+-5.9 (p<0.0001). Mean IMA improved from 16°+-3.1 to 8°+-2.3 (p<0.0001). There were 6 re-operations (ostectomy & screw removal). The learning curve inflection point was between case 38 & 39. 38 were analysed in the learning phase & the remaining 20 in the plateau phase. No significant difference between the learning and plateau phases were seen for age, pre- & post-operative HMA or IMA, difference from normal angles or return to theatre. Pearson correlation revealed that only tourniquet time (p=0.001) & number of fluoroscopy shots (p=0.019) were significantly correlated with the learning or plateau phase. CONCLUSION: The learning curve for the PECA hallux valgus technique is around 40 cases, reflected by tourniquet time and number of fluoroscopy shots. It does not affect radiological correction or complications, showing that if taught properly this technique is reproducible and reliable.