Abstract
Previous research has shown that tunnel placement is critical in ACL reconstruction. The ultimate position of both the femoral and tibial tunnel determines knee kinematics and overall function of the knee post surgery. As with all techniques there is a definite learning curve for the arthroscopic technique. However, the effect of the learning curve on tunnel placement has been studied sparsely. The purpose of this project therefore is to investigate the effect of the learning curve on tunnel placement.
Postoperative radiographs of the first 200 anterior cruciate reconstructions with bone-tendon-bone patella tendon of a single orthopaedic surgeon performed during the first four years of independent practice were analysed for tunnel placement. Radiographs were digitalised and imported into a CAD program.
Tunnel placement both femoral and tibial antero-posterior and sagittal was assessed using Sommer's criteria. A rating scale was developed to assess overall placement. A total of 100 points indicated perfect placement. A maximum of 30 points each were allocated for sagittal femoral and tibial placement and a maximum of 20 points each were allocated for coronal placement.
Tunnel placement scores improved from 66 for the first 25 procedures to 87 for the last 25 procedures. Sagittal femoral placement (zone 1–4 with zone 1 being the preferred zone of placement) improved from an average of 1.44 to 1.08. Sagittal tibial placement (45% from anterior border of tibia) did not change significantly and remained between 42.82 t0 44.76%. Coronal femoral placement (between 10:00–11:00 o'clock for the right knee and 1:00–2:00 for the left knee) ranged from 10.45–11.15 and 12:45-1:15 o'clock respectively. This finding may be related to the transtibial tibial technique used to place the femoral tunnel. Coronal tibial placement (45% from medial tibial border) ranged from 45-46.58%.
Correct placement of the femoral and tibial bone tunnels is important for a successful reconstruction of the anterior cruciate ligament (ACL). This study demonstrated a definitive learning curve and steady improvement of tunnel placement. Whilst there was no significant improvement in sagittal placement, overall placement improved significantly.
