Incomplete Bicruciate Injuries: Fix only the ACL
Incomplete Bicruciate Injuries: Fix only the ACL
Abstract & Commentary
Synopsis: A retrospective, nonrandomized study of 18 patients with an interesting injury pattern of a complete ACL tear and a partial PCL tear (previously described as an incomplete bicruciate injury) were treated with BTB ACL reconstruction and observation of the PCL injury. Long-term follow-up revealed excellent stability (11/18 with a negative lachman, 4/18 patients with a 1+ lachman, average lysholm score 93). Substantial evidence is given for managing this injury with ACL reconstruction alone.
Source: Wolf RS, Lemak LJ. The Journal of Arthroscopic and Related Surgery. 2002;18:264-271.
This study documents the functional outcome associated with arthroscopically assisted anterior cruciate ligament (ACL) reconstruction in the specific injury pattern of an incomplete bicruciate knee. Wolf and Lemak report on 18 patients followed for an average of 60 months (range, 10-92 months) treated by Dr. Lemak in Birmingham, Ala, from 1990 to 1998. They confirm the previously described injury pattern of complete ACL tear and partial posterior cruciate ligament ([PCL] incomplete bicruciate injury) with PCL injury ranging from 0 to 2+ (9 grade 0 partial PCLs, 4 grade 1 PCLs, and 2 grade 2 PCLs). No patient sustained a documented knee dislocation nor were there any grade 3 PCL injuries. Three patients were lost to follow-up with 13 of 15 seen postoperatively after undergoing an isolated ACL reconstruction. Two patients underwent a combined ACL reconstruction and posteromedial corner repair. PCL surgery included only arthroscopic evaluation, occasional debridement, and no radiofrequency treatment. At long-term follow-up, patients fared remarkably well with an isolated ACL reconstruction with an average Lysholm score of 93 with only 1 patient with a score less than 80, and in that patient completion of the PCL tear occurred with a second injury. Wolf and Lemak performed extensive postoperative testing including IKDC, KT-2000, stress radiographs, and isokinetic strength testing.
Wolf and Lemak note overall good results with isolated treatment of the ACL tear in the incomplete bicruciate knee injury and observation of the PCL injury. Symptomatic chronic posterior instability was low and only occurred in 1 patient (6%). No failures of ACL reconstruction were noted at long-term follow-up. Wolf and Lemak hypothesize one reason for the long-term durability of the nonoperative PCL treatment. They suspect the mechanism of injury to be hyperextension, which in theory completely tears the ACL and the posteromedial bundle of the PCL; hence, sparing the anterolateral bundle of the PCL which is more important at 90° of knee flexion (ie, posterior drawer testing).
Comment by Robert C. Schenck, Jr., MD
Controversy exists over clinical decisionmaking and timing of surgery in multiple ligamentous injuries of the knee. Wolf and Lemak present a long-term follow-up of one subset of multiple ligamentous injuries, namely the incomplete bicruciate knee injury.1 This injury pattern involves a complete tear of the ACL, partial PCL, and variable involvement of the collateral ligaments. Although Wolf and Lemak noted no patient with a documented knee dislocation, Cooper and colleagues described the PCL intact knee dislocation occurring with a normally or partially torn PCL.2 In those case reports, isolated ACL reconstruction gave satisfactory long-term knee stability. The reader should be cautioned, however, and should proceed carefully with the treatment of a bicruciate injury, be it incomplete or complete. The need for a careful knee exam under anesthesia in combination with a preoperative MRI is crucial to determine the degree of injury to the PCL. As described in the paper by Wolf and Lemak, the majority of patients had a normally functioning PCL and only MR or arthroscopic evidence of PCL injury. The presence of a complete bicruciate injury (for all intents and purposes, a knee dislocation) must be treated with initial management of the PCL followed by ACL reconstruction (delayed or simultaneous). The clinician reconstructing the complete bicruciate injury with an ACL reconstruction alone has a significant risk of tibiofemoral subluxation on tensioning of the ACL graft. In contrast, the incomplete bicruciate injury has a functioning PCL providing the foundation for a successful ACL reconstruction which was shown nicely by Wolf and Lemak.
References
1. Nonweiler D, Schenck RC, DeLee JC. Orthop Rev. 1993;22:1249-1252.
2. Cooper D, et al. Clin Orthop. 1992;284:228-233.
Dr. Schenck, Deputy Chairman, Department of Orthopaedics, University of Texas Health Science Center, San Antonio, TX, is Associate Editor of Sports Medicine Reports.
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