An in vitro study of an intraarticular and extraarticular reconstruction in the anterior cruciate ligament deficient knee.

The biomechanical effectiveness of an extraarticular ACL reconstruction, an intraarticular ACL reconstruction, and the combination of these on both anterior stability and internal rotational stability of the ACL deficient knee was investigated in six cadaver knees. The extraarticular reconstruction consisted of the Müller anterolateral femorotibial ligament iliotibial band tenodesis, and the intraarticular reconstruction used the middle third of the patellar tendon in the manner of Clancy. The extraarticular reconstruction was found to overconstrain internal tibial rotation of the ACL excised knee between 30 degrees and 90 degrees (P less than 0.05). While the isolated extraarticular reconstruction did not return normal anterior stability to the ACL deficient knee (P less than 0.05), it did significantly reduce the anterior laxity of the ACL deficient knee between 30 degrees and 90 degrees of knee flexion (P less than 0.05). For the combined reconstruction, the intraarticular procedure was performed and then only enough tension was applied to the extraarticular reconstruction to take up slack in the tenodesis without shifting the rotatory position of the tibia from that produced by the intraarticular procedure alone. Neither the intraarticular reconstruction nor the combined procedure resulted in any significant shifts from normal (P less than 0.05) in the rotatory position of the unloaded tibia; during loading neither resulted in rotational displacements significantly different from normal; and both of these procedures reduced the increased anterior laxity of the ACL deficient knee to a level not statistically different from normal. Because the extraarticular reconstruction shared the load when performed with the intraarticular reconstruction as part of a combined procedure, we concluded that it would be useful as an adjunctive procedure in appropriate clinical situations.