2002 Papers - Berkowitz


Radiographic Analysis of Femoral Tunnel and Interference Screw Placement During Arthroscopic ACL Reconstruction
Mark Berkowitz, Bertram Providence, David H. Kim, Craig R. Bottoni
Tripler Army Medical Center

Background: Tunnel placement has been identified as one of the most critical factors in ACL reconstruction. Several techniques exist for creation of an optimal femoral tunnel. The transtibial technique involves drilling of the femoral tunnel through a previously created tibial tunnel. The femoral interference screw is subsequently inserted through a separate arthroscopic portal. The femoral-side-first technique creates the femoral tunnel through an anteromedial arthroscopic portal, independent of and prior to creation of the tibial tunnel. The femoral interference screw is then inserted through this same anteromedial tunnel.
The purpose of this study is to evaluate and compare the radiographic position of the femoral tunnel and femoral interference screw during reconstruction of the anterior crucuiate ligament using these two different arthroscopic techniques: transtibial (TT) and "femoral-side-first" (FSF).

Materials and Methods: Forty consecutive patients who underwent anterior cruciate ligament reconstruction using the transtibial technique were placed into Group I. Similarly, forty consecutive patients who underwent ACL reconstruction using the FSF technique were placed in Group II. Patients enrolled in the study included primary ACL reconstruction procedures using bone-patellar-tendon-bone autografts stabilized with metal interference screws in whom adequate postoperative anterior-posterior (AP) and lateral radiographs were obtained. Exclusion criteria included revision ACL reconstruction, procedures involving hamstring autografts, multiple ligament reconstructions, bioabsorbable interference screws, non-interference screw fixation, procedures complicated by posterior wall violation and those with inadequate postoperative radiographs.
All patients in both Group I and Group II were evaluated using standard AP and lateral radiographs. Four separate parameters were measured. These included: 1) interference screw-bone plug divergence, 2) posterior wall thickness, 3) coronal and sagittal tunnel angles, and 4) coronal tunnel placement ratio. Statistical analysis of the results was performed using a two-tailed Students t-test, and interobserver reliability was determined.

Results: The average divergence in Group I was 13.1 degrees compared to 2.2 degrees in Group II. All patients in Group II had divergence angles < 10 degrees, whereas only 47% of Group I patients achieved this parameter. Nearly half of the Group I patients demonstrated rotation of the bone plug anterior to the screw. Only 5 of 30 Group II patients demonstrated this finding. Group I patients consistently demonstrated a more anterior and more vertical femoral tunnel compared to the FSF group, with greater posterior wall widths and larger coronal tunnel angles. Sagittal angles and coronal ratios did not differ significantly between the groups.

Conclusions: This study demonstrates radiographic differences in femoral tunnel and interference screw placement for the ACL reconstruction when using either the transtibial or femoral-side-first technique. The position of the femoral tunnel using the FSF technique was on average more posterior than when the transtibial technique was employed. Moreover, divergence of interference screw and graft was minimized using the FSF technique. The nature of these radiographic differences suggests that the femoral-side-first technique may more reliably produce optimal position of the femoral tunnel and interference screw. We recommend the FSF technique for creation of the femoral tunnel and insertion of the femoral interference screw during ACL reconstruction.