Relooking at double-bundle versus single-bundle anterior cruciate ligament reconstruction: A biomechanical model to evaluate which can confer better rotatory stability.

BACKGROUND: To treat anterior cruciate ligament (ACL) injuries, double-bundle ACL reconstruction has been proposed as a more anatomical approach relative to single-bundle reconstruction. However, controversy remains over which technique is superior in addressing knee instability, particularly rotational laxity. We hypothesize that double-bundle reconstruction better restores rotational knee laxity, while both methods are similar in restoring anterior knee laxity, to intact knee levels. METHODS: A controlled laboratory study. Eight cadaveric knees were tested accordingly: (1) static anterior laxity testing under 150 N-anterior tibial loading at 20°, 60° and 90° knee flexion using a material testing machine, followed by (2) dynamic simulated pivot-shift with knee-specific loading involving iliotibial band forces, valgus and internal rotation torques, while the knee was brought from extension to 90° flexion on a 6°-of-freedom custom-designed rig. Tibiofemoral kinematics were recorded using an electromagnetic tracking system for the ACL-intact, ACL-deficient, single-bundle and double-bundle ACL-reconstructed knee conditions. FINDINGS: Double-bundle reconstruction reduced internal rotation under pivot-shift to levels not significantly different from ACL-intact conditions (P > .173), unlike single-bundle that remained significantly higher at 10-40° flexion (P < .05). For anterior laxity, there was no significant difference between double-bundle, single-bundle, and ACL-intact conditions under static testing (P > .175) or pivot-shift (P = .219). The maximum extent of knee envelope laxity was significantly reduced for double-bundle relative to single-bundle, particularly for the rotatory component (P = .012). INTERPRETATION: Double-bundle was biomechanically superior to single-bundle in addressing envelope of rotation, while both techniques restored anterior knee laxity to ACL-intact levels.

Subchondroplasty for Bone Marrow Lesions in the Arthritic Knee Results in Pain Relief and Improvement in Function.

Subchondroplasty is a relatively new joint preserving procedure, which involves the localized injection of calcium pyrophosphate bone substitute into the bone marrow lesion. The advent of magnetic resonance imaging (MRI) has greatly facilitated the identification of these bone marrow lesions. We investigated the clinical efficacy of subchondroplasty in the treatment of symptomatic bone marrow lesions in the knee, including knees with preexisting osteoarthritis. This study comprised of 12 patients whose knees were evaluated with standard radiographs and MRI to identify and localize the bone marrow lesions. They then underwent subchondroplasty under intraoperative radiographic guidance. Preoperative and postoperative visual analog scale (VAS) pain scores, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, and Knee Injury and Arthritis Outcome Scores (KOOS) were obtained. VAS scores improved significantly from 7.5 ± 1.8 before surgery to 5.2 ± 2.7 after surgery. This further improved to 2.1 ± 2.4 at the one-year follow-up. KOOS scores improved significantly from 38.5 ± 17.0 before surgery to 73.2 ± 19.0 at the one-year follow-up. WOMAC scores improved significantly from 47.8 ± 20.5 before surgery to 14.3 ± 13.2 at the one-year follow-up. Subchondroplasty offers an effective way to treat subchondral bone marrow lesions in the arthritic knee, resulting in improvement in symptoms and early return to activity. Long-term studies are required to evaluate if these benefits can last. This is a Level II study.