Posterior instability near extension is related to clinical disability in isolated posterior cruciate ligament deficient patients

Biomechanical analysis of posterior cruciate ligament reconstruction with aperture femoral fixation

The goal of this study was to determine whether single-tunnel-double-bundle-equivalent posterior cruciate ligament (PCL) reconstruction using an aperture femoral fixation device better replicated normal knee kinematics than single-bundle reconstruction. Eight fresh-frozen human cadaver knees underwent arthroscopically assisted PCL reconstruction and were examined with a robotic testing system to assess knee joint kinematics under combinations of applied internal, neutral, and external rotational tibial torque and anteroposterior translational forces at 0°, 30°, 60°, 90°, and 120° flexion. Three conditions were tested: (1) intact PCL; (2) single-tunnel PCL reconstruction with anterolateral and posteromedial bundle fixation at 90°/90° (single bundle); and (3) 90°/0° (double-bundle equivalent), respectively. Posterior tibial translation was the primary outcome measure. Compared with the intact knee, double-bundle-equivalent reconstruction under external tibial torque allowed greater posterior translation across the flexion arc as a whole (P=.025) and at 30° flexion (P=.027) when results were stratified by flexion angle. No other kinematic differences were found with single-bundle or double-bundle-equivalent fixation, including mediolateral translation and both coupled and isolated tibial rotation (P>.05). Single-bundle PCL reconstruction closely approximated native knee rotational and translational kinematics, whereas double-bundle-equivalent reconstruction permitted increased posterior translation with applied external tibial torque, particularly at lower flexion angles. Single-bundle PCL reconstruction provides knee stability similar to the intact condition, making it a practical alternative to conventional double-bundle PCL reconstruction. The authors found that double-bundle-equivalent reconstruction provided no advantage to justify its clinical use.

Biomechanical evaluation of an anatomic double-bundle posterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to evaluate the effect of the anatomic double-bundle reconstruction (ADBR) of the posterior cruciate ligament (PCL) with 2 femoral tunnels and 2 tibial tunnels.

METHODS

Eight fresh-frozen human knees were used. Bone tunnels were created based on the PCL anatomic footprints. A 9-mm looped semitendinosus and gracilis tendon for anterolateral bundle reconstruction (ALR), a 7-mm looped semitendinosus tendon for posteromedial bundle reconstruction (PMR), and the same grafts for the ADBR were used. Under a 100-N posterior tibial load and under a 100-N posterior tibial load and 5 Nm of external tibial torque, the posterior tibial translation (PTT) was measured.

RESULTS

Under posterior tibial load, at 0°, the PTT of the ALR was larger than that of the intact knee (P = .04) and the ADBR (P = .03); however, there were no significant differences between the PTT of the PMR and that of the ADBR (P = .28) and intact knee (P = .99). At 30°, the PTT of the ADBR was smaller than that of the ALR (P = .02) and PMR (P = .02). At 60°, the PTT of the PMR was larger than that of the ADBR (P = .02). At 90°, the PTT of the PMR was larger than that of the ADBR (P = .02). Under posterior tibial load and external tibial torque, at 0°, the PTT of the ALR was larger than that of the ADBR (P = .04).

CONCLUSIONS

Although the graft size of the ADBR was larger than other reconstructions, the ADBR was better than the ALR at 0° and 30° of knee flexion under the posterior tibial load and at 0° under the combination of posterior tibial load and external tibial torque, as well as better than the PMR at 30°, 60°, and 90° of knee flexion under the posterior tibial load.

CLINICAL RELEVANCE

The clinical outcome of PCL reconstruction might improve by reducing posterior knee laxity in knee extension with the ADBR.

The effect of intra-articular autogenous bone marrow injection on healing of an acute posterior cruciate ligament injury in rabbits

PURPOSE

The purpose was to identify the effect of intra-articular autogenous bone marrow injection on the healing of an acute posterior cruciate ligament (PCL) rupture in a rabbit model. The effect of autogenous bone marrow on the healing process was assessed serially by gross inspection, histologic examination, and immunohistochemical study of growth factors.

METHODS

In both knee joints, the PCL was completely transected surgically near the femoral attachment site in 24 rabbits. Autogenous bone marrow was obtained from both tibias and delivered only to the right knee joint by direct intra-articular injection. Gross inspection, histologic examination, and immunohistochemical study of growth factors were performed at 8, 12, and 16 weeks after severing of the posterior cruciate ligament (PCL) among 8 randomly chosen specimens. The degree of healing in both marrow-stimulated and untreated control ligaments was evaluated by gross inspection using an ordinal scale consisting of 5 grades. The degree of fibroblast and vessel proliferation and alignment of collagen fibers were evaluated by histologic examination. The degree of expression of transforming growth factor β1, epidermal growth factor receptor, and vascular endothelial growth factor was evaluated by immunohistochemical study. Statistical analysis was performed with the Mann-Whitney U test.

RESULTS

In the group with marrow-stimulated ligaments, the degree of healing was higher at 8 and 12 weeks by gross examination, whereas there was no significant difference at 16 weeks between the 2 groups. According to histologic examination, the healing process was faster in the bone marrow injection group than in the control group at 8 and 12 weeks because the degree of fibroblast and vessel proliferation significantly declined and collagen fibers were arranged more regularly compared with the control group. Similar to the results of histologic examination, the results of immunohistochemical studies showed that the healing process was faster in the bone marrow injection group. However, the recovery of the PCL was completed at 16 weeks after PCL resection in both the bone marrow injection group and the control group.

CONCLUSIONS

Intra-articular autogenous bone marrow injection appeared to promote the initiation of healing response in acutely injured PCLs in rabbits.

CLINICAL RELEVANCE

Intra-articular autogenous bone marrow injection can be a viable option for treating acutely injured PCLs.

Management of medial-sided knee injuries, part 2: posteromedial corner

Injury to the posteromedial corner (PMC) of the knee differs anatomically and biomechanically from isolated injury to the medial collateral ligament. Newer anatomic and biomechanical studies are refining the field's understanding of the medial side of the knee, as well as its role in multiple ligament injuries. Valgus instability places additional strain on a reconstructed anterior or posterior cruciate ligament, which can contribute to late graft failure. Injuries to the PMC may not heal without surgical repair or reconstruction, particularly when part of a multiple-ligament injury. Identification of PMC injury before cruciate reconstruction is important so that appropriate repair or reconstruction of the PMC and medial collateral ligament can be undertaken at the same time. This article reviews the relevant literature on the PMC, discusses reasons for selective operative management, and illustrates reconstructive strategies for PMC injuries occurring as part of a medial-sided or multiligament injury to the knee.

Remnant posterior cruciate ligament-augmenting stent procedure for injuries in the acute or subacute stage

PURPOSE

To evaluate the results of a remnant posterior cruciate ligament (PCL)-augmenting stent procedure for acute- or subacute-stage PCL injuries in terms of stability and clinical results.

METHODS

Between September 2003 and March 2006, 32 patients with a PCL tear underwent a reconstructive stent procedure with an autogenous hamstring tendon graft to augment the remains of the injured PCL. Of these patients, 20 who satisfied our inclusion criteria and could be followed up for a minimum duration of 24 months were enrolled in our study. The remnant PCL and synovium were preserved, and augmentation was performed by use of the transtibial technique. A femoral tunnel was created near the footprint of the anterolateral bundle. Stability was measured on posterior stress radiographs and by use of a maximum manual displacement test performed with a KT-1000 arthrometer (MEDmetric, San Diego, CA). The International Knee Documentation Committee (IKDC) and Orthopädische Arbeitsgruppe Knie scoring systems were used for clinical evaluation.

RESULTS

Stress radiographs showed that the mean side-to-side differences in displacement were reduced from 9.9 +/- 4.0 mm preoperatively to 3.0 +/- 2.6 mm at the last follow-up, whereas KT-1000 tests showed that these differences were reduced from 6.9 +/- 2.1 mm preoperatively to 2.7 +/- 1.5 mm. The final IKDC score was A in 7 patients (35%), B in 10 (50%), C in 2 (10%), and D in 1 (5%). The mean Orthopädische Arbeitsgruppe Knie score improved from 61.6 +/- 13.1 to 88.2 +/- 9.5.

CONCLUSIONS

Of the patients, 90% showed satisfactory posterior stability and 85% had a normal or nearly normal rating based on the IKDC score at a mean of 3 years after the remnant PCL-augmenting stent procedure in the acute or subacute stage of PCL injuries.