Tibiofemoral contact mechanics after serial medial meniscectomies in the human cadaveric knee.

BACKGROUND: There is no consensus regarding the extent of meniscectomy leading to deleterious effects on tibiofemoral contact mechanics. HYPOTHESIS: The meniscus aids in optimizing tibiofemoral contact mechanics, increasing contact area, and decreasing contact stress. STUDY DESIGN: Controlled laboratory study. METHODS: Twelve fresh-frozen human cadaveric knees each underwent 15 separate testing conditions-5 serial 20-mm posterior medial meniscectomy conditions (intact, 50% radial width, 75% radial width, segmental, and total meniscectomy) at 3 flexion angles (0 degrees , 30 degrees , and 60 degrees )-under an 1800-N axial load. Tekscan sensors were used to measure total force and medial force, contact area, mean contact stress, and peak contact stress. RESULTS: All posterior medial meniscectomy conditions resulted in significantly decreased contact areas and increased mean and peak contact stresses compared with the intact state (P < .05). The changes in contact mechanics after segmental and total posterior medial meniscectomies were not statistically different (P > .05). Incremental changes in contact area and mean contact stress increased as more peripheral portions of the medial meniscus were removed, whereas peak contact stresses exhibited similar incremental changes throughout all meniscectomy conditions. CONCLUSIONS: The meniscus is a crucial load-bearing structure, optimizing contact area and minimizing contact stress. Loss of hoop tension (ie, segmental meniscectomy) is equivalent to total meniscectomy in load-bearing terms. The peripheral portion of the medial meniscus provides a greater contribution to increasing contact areas and decreasing mean contact stresses than does the central portion, whereas peak contact stresses increase proportionally to the amount of meniscus removed. CLINICAL RELEVANCE: Because the degree of meniscectomy leading to clinically significant outcomes is unknown, a prudent strategy is to preserve the greatest amount of meniscus possible.

Primary anterior cruciate ligament reconstruction using fresh-frozen, nonirradiated patellar tendon allograft: minimum 2-year follow-up.

BACKGROUND: There are conflicting reports of allograft performance, immune response, tissue incorporation, and rerupture rates when used for anterior cruciate ligament reconstruction. PURPOSE: To evaluate the clinical outcome of a fresh-frozen, nonirradiated, patellar tendon allograft for primary anterior cruciate ligament reconstruction surgery. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Patients who underwent endoscopic primary anterior cruciate ligament reconstruction with allograft tissue a minimum of 2 years ago were evaluated with physical examinations, the KT-1000 arthrometer, functional testing, radiographic evaluation, subjective assessment, and outcomes tools. RESULTS: Fifty-nine patients (60 knees) were evaluated at an average of 51 months after surgery. Ninety-four percent of patients were mostly or completely satisfied. A negative pivot shift test result was noted in 90% of subjects. The KT-1000 arthrometer side-to-side differences were < or =3 mm in 95% of patients, and no patient exceeded 5 mm. The mean International Knee Documentation Committee score was 78 (SD = 19), and the mean Lysholm score was 82 (SD = 17). There were no clinical symptoms consistent with graft rejection or infection. Radiographic evaluation demonstrated infrequent significant tunnel widening. CONCLUSIONS: Use of a fresh-frozen, nonirradiated allograft for primary reconstruction of the anterior cruciate ligament is a successful procedure both subjectively and functionally for restoring stability in patients selected for allograft reconstruction. In the patients selected for this surgical procedure, clinical, arthrometric stability testing, and subjective satisfaction were comparable to our previously published cohort studies using patellar tendon autograft at similar postoperative follow-up.

An accessory portal for posterior cruciate ligament tibial insertion visualization.

Posterior cruciate ligament (PCL) reconstruction is infrequently performed, technically challenging, and has less predictable results compared with its anterior cruciate ligament (ACL) counterpart. Creation of a transtibial tunnel has been associated with catastrophic neurovascular complications, as well as tunnel malpositioning. This technical note reports the use of the femoral PCL tunnel to visually access the posterior slope for tibial tunnel creation. This technique modification allows concurrent placement of instruments through an inferomedial and/or posteromedial portal to facilitate PCL insertional debridement, placement of the tibial aimer, and creation of the tunnel. We feel that this technical modification provides superior visualization of this anatomic area.