Tunnel positioning in anterior cruciate ligament reconstruction: how long is the learning curve?

The purpose of this study is to investigate the effect of the learning curve on radiographic tunnel position. A consecutive series of the first 200 procedures of an orthopaedic surgeon over his initial 4 years of independent practice were analysed for tunnel placement, based on radiographic appearance. An arthroscopic-assisted technique using patella tendon as graft material was performed in all cases. To establish femoral tunnels, a transtibial guide pin was used. The graft was secured with bioabsorbable screws. A Frik tunnel view and a strictly lateral radiograph were used to assess tunnel placements. Tunnel positioning was assessed using a computer-aided design, 2D software (Auto CAD2000^®). To minimize measurement bias, radiographs were assessed three times or until deviations in all three measurements were less than 10%, and the three measurements were then averaged. Sagittal femoral tunnel placement improved significantly (P = 0.01) after the first 100 cases. Significant improvement (P = 0.05) in coronal femoral tunnel placement was observed after the first 75 cases. Significant improvement (P = 0.01) in sagittal tibial tunnel position was observed after the first 100 cases. Mean coronal tibial tunnel did not improve. Critical analysis in this consecutive series suggests that a caseload of approximately 100 procedures were necessary for this surgeon to refine his surgical technique beyond that acquired during formal training.