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Abstract Presented at the 26th Annual Meeting of the Arthroscopy Association of North America| Volume 23, ISSUE 6, SUPPLEMENT , e6-e7, June 2007

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Double Bundle ACL Reconstruction Better Restores the Tibiofemoral Pressure and Contact (SS-11)

      Summary

      In order to evaluate the tibiofemoral pressure and contact area after ACL reconstruction, ten knees from cadavers were tested under 1000 N axial load. The tibiofemoral pressure and contact area were marked in a pressure measuring film placed between tibia and femur. Double-Bundle (DB) ACL reconstruction demonstrated better restoration of the average and maximum tibiofemoral pressure as well as tibiofemoral contact area when compared to the Single-Bundle (SB) ACL reconstruction. These in vitro findings may suggest that DB ACL reconstruction better preserve the cartilage after an ACL reconstruction compared to the SB ACL reconstruction.

      Purpose

      The long-term clinical outcomes of ACL surgery show a large amount of patients with cartilage degenerative changes. Biomechanical studies have shown that Double-Bundle (DB) ACL reconstruction better restores the knee biomechanics when compared to the conventional Single-Bundle (SB) ACL reconstruction. However, it is unknown whether the tibiofemoral cartilage pressure and contact area is better restored after DB reconstruction when compared to SB reconstruction. The purpose of this study is to evaluate the tibiofemoral pressure and contact area after SB or DB ACL reconstruction.

      Methods

      10 knees from cadavers were used for this study. Five knees were tested for DB and five for SB ACL reconstruction. Pressure measuring film was inserted between tibia and femur, and subject to 1000N axial load using an uniaxial testing machine. The super-low film was used to assess the average and maximum tibiofemoral pressure, and the contact area at 0, 15, 30 and 45degrees. Three conditions were evaluated: 1) intact ACL(Int), 2)DB ACL reconstruction, and 3)SB ACL reconstruction. The pressure measuring films were scanned after the experiment and the images evaluated by specific software. Statistical analysis was performed using the Repeated Measures Anova. The level of significance was set a prior at p<.05.

      Results

      The average pressure in the lateral compartment of DB and SB groups at all flexion angles tested was not different from the intact ACL group. However, at 15 degrees SB had higher pressure than DB. The average pressure in the medial compartment at 15, 30, and 45 degrees showed no difference between groups. But, at 0 degrees DB had significant less pressure than SB. The maximum pressure in the lateral compartment at all flexion angles showed no difference between groups. The maximum pressure in the medial compartment showed no difference at 0, 30, and 45 degrees, but at 15 degrees DB restored close to normal the maximum pressure values while SB did not. Though no statistical differences were found in several circumstances regarding to average and maximum pressure, there was a trend to better restoration in the DB group compared to SB.
      DB restored the contact area in the lateral compartment at 0, 15 degrees of flexion to values close to normal while SB did not. At 30 and 45 degrees neither DB nor SB restored the normal contact area in the lateral compartment. In the medial compartment at 0, 15, 30 degrees DB is significant better to SB and restore the contact area close to normal. At 45 degrees there was no difference between DB and SB compared to the normal.

      Conclusions

      We found that DB has superior restoration of the tibiofemoral pressure and contact area than SB reconstruction. It suggests in our experimental model that DB reconstruction may preserve better the cartilage after ACL reconstruction when compared to SB reconstruction. However, further clinical studies are needed to elucidate clinically this issue.