Anterior Cruciate Ligament Intact Knees Research Articles

Single-Tunnel Double-Bundle Anterior Cruciate Ligament Reconstruction with Anatomical Placement of Hamstring Tendon Graft

Background Anatomical reconstruction techniques that can restore normal joint kinematics without increasing surgical complications could potentially improve clinical outcomes and help manage anterior cruciate ligament injuries more efficiently. Hypothesis Single-tunnel double-bundle anterior cruciate ligament reconstruction with anatomical placement of hamstring tendon graft can more closely restore normal knee anterior-posterior, medial-lateral, and internal-external kinematics than can conventional single-bundle anterior cruciate ligament reconstruction. Study Design Controlled laboratory study. Methods Kinematic responses after single-bundle anterior cruciate ligament reconstruction and single-tunnel double-bundle anterior cruciate ligament reconstruction with anatomical placement of hamstring tendon graft were compared with the intact knee in 9 fresh-frozen human cadaveric knee specimens using a robotic testing system. Kinematics of each knee were determined under an anterior tibial load (134 N), a simulated quadriceps load (400 N), and combined torques (10 N·m valgus and 5 N·m internal tibial torques) at 0°, 15°, 30°, 60°, and 90° of flexion. Results Anterior tibial translations were more closely restored to the intact knee level after single-tunnel double-bundle reconstruction with anatomical placement of hamstring tendon graft than with a single-bundle reconstruction under the 3 external loading conditions. Under simulated quadriceps load, the mean internal tibial rotations after both reconstructions were lower than that of the anterior cruciate ligament—intact knee with no significant differences between these 3 knee conditions at 0° and 30° of flexion (P > .05). The increased medial tibial shifts of the anterior cruciate ligament—deficient knees were restored to the intact level by both reconstruction techniques under the 3 external loading conditions. Conclusion Single-tunnel double-bundle anterior cruciate ligament reconstruction with anatomical placement of hamstring tendon graft can better restore the anterior knee stability compared with a conventional single-bundle reconstruction. Both reconstruction techniques are efficient in restoring the normal medial-lateral stability but overcorrect the internal tibial rotations. Clinical Relevance Single-tunnel double-bundle anterior cruciate ligament reconstruction with anatomical placement of hamstring tendon graft could provide improved clinical outcomes over a conventional single-bundle reconstruction.

Joint Space Narrowing After Partial Medial Meniscectomy in the Anterior Cruciate Ligament-Intact Knee

Osteoarthritis of the knee is common after total medial meniscectomy. In anterior cruciate ligament-intact knees, the reported outcomes of partial medial meniscectomy are variable. Radiographic assessment using a posteroanterior weight-bearing view is a reliable tool for detecting minor medial joint space narrowing, which may be an early sign of osteoarthritis. Studies that assessed the effect of partial medial meniscectomy found a low percentage of patients with >50% joint narrowing at 10 to 15 years after surgery. Digital radiography, using a posteroanterior weight-bearing view, is a highly sensitive method for observing minor joint space narrowing in the involved knee. A recent study showed that 88% of patients who underwent partial medial meniscectomy had joint space narrowing of <2 mm, and none had narrowing >or=2 mm, at a mean follow-up of 12 years. Subjective results after partial medial meniscectomy are favorable, with 88% to 95% of patients reporting good to excellent results.

Effects of Initial Graft Tension on the Tibiofemoral Compressive Forces and Joint Position after Anterior Cruciate Ligament Reconstruction

Background The initial tension applied to an anterior cruciate ligament graft at the time of fixation modulates knee motion and the tibiofemoral compressive loads. Purpose To establish the relationships between initial graft tension, tibiofemoral compressive force, and the neutral tibiofemoral position in the cadaveric knee. Study Design Controlled laboratory study. Methods The tibiofemoral compressive forces and joint positions were determined in the anterior cruciate ligament-intact knee at 0°, 20°, and 90° of knee flexion. The anterior cruciate ligament was excised and reconstructed with a patellar tendon graft using graft tensions of 1, 15, 30, 60, and 90 N applied at 0°, 20°, and 90° of knee flexion. The compressive forces and neutral positions were compared between initial tension conditions and the anterior cruciate ligament-intact knee. Results Increasing initial graft tension increased the tibiofemoral compressive forces. The forces in the medial compartment were 1.8 times those in the lateral compartment. The compressive forces were dependent on the knee angle at which the tension was applied. The greatest compressive forces occurred when the graft was tensioned with the knee in extension. An increase in initial graft tension caused the tibia to rotate externally compared with the anterior cruciate ligament-intact knee (1.5° and 7.7° of external rotation when tensioned to 90 N at 0° and 90° of knee flexion, respectively). Increases in initial graft tension also caused a significant posterior translation of the tibia relative to the femur (0.9 and 5.3 mm of posterior translation when tensioned to 90 N at 0° and 90° of knee flexion, respectively). Conclusion Different initial graft tension protocols produced predictable changes in the tibiofemoral compressive forces and joint positions. Clinical Relevance The tibiofemoral compressive force and neutral joint position were best replicated with a low graft tension (1-15 N) when using a patellar tendon graft.

Anatomical Double-Bundle Anterior Cruciate Ligament Reconstruction after Valgus High Tibial Osteotomy

Background Although anatomical double-bundle anterior cruciate ligament reconstruction can successfully restore normal knee biomechanics for knees with typical varus-valgus alignment, the efficacy of the same reconstruction method for knees after a valgus high tibial osteotomy is unclear. Hypothesis Anatomical double-bundle anterior cruciate ligament reconstruction for valgus knees after a high tibial osteotomy cannot restore normal knee kinematics and can result in abnormally high in situ forces in the ligament graft. Study Design Controlled laboratory study. Methods Ten cadaveric knees were subjected to valgus high tibial osteotomy followed by an anatomical double-bundle anterior cruciate ligament reconstruction. The valgus knees were tested using a robotic/universal force-moment sensor system before and after the ligament reconstruction. The knee kinematics in response to anterior tibial load and combined rotatory loads, as well as the corresponding in situ forces of the anterior cruciate ligament bundles and grafts, were compared between the ligament-intact and ligament-reconstructed valgus knees. Results After reconstruction, the anterior tibial translation and internal tibial rotation for the valgus knee decreased approximately 2 mm and 2°, respectively, at low flexion angles compared with those of the anterior cruciate ligament–intact knee (P < .05). The in situ forces in the posterolateral graft became 56% to 200% higher than those in the posterolateral bundle of the intact anterior cruciate ligament (P < .05). Conclusion Performing an anatomical double-bundle anterior cruciate ligament reconstruction on knees after valgus high tibial osteotomy may overconstrain the knee and result in high forces in the posterolateral graft, which could predispose it to failure. Clinical Relevance Modifications of anterior cruciate ligament reconstruction procedures to reduce posterolateral graft force may be needed for valgus knees after a high tibial osteotomy.

Histology of the Torn Meniscus: A Comparison of Histologic Differences in Meniscal Tissue between Tears in Anterior Cruciate LigamentIntact and Anterior Cruciate LigamentDeficient Knees

Purpose The purpose of this case control study was to evaluate possible preexisting structural differences between torn menisci in anterior cruciate ligament–intact and anterior cruciate ligament–deficient knees. Materials and Methods Subjects were prospectively enrolled into the study from new patient referrals to the orthopaedic clinic. Forty-four meniscal specimens were retrieved during routine arthroscopy. The anterior cruciate ligament–deficient group included 24 patients (15 men and 9 women, average age of 26.5 years, SD = 9.5) with 24 acute, displaced, longitudinal, bucket-handle tears of the medial meniscus in unstable, anterior cruciate ligament–deficient knees. The anterior cruciate ligament–intact group included 20 patients (14 men and 6 women, average age of 30.4 years, SD = 13.4) with similar tears in anterior cruciate ligament–intact knees. Longitudinal and transverse section specimens were stained with hematoxylin and eosin and safranin O, divided into zones based on proximity to the tear, and graded on safranin O uptake or tissue composition. Results Descriptive statistics and χ2 analyses were used to assess differences between groups within each zone. Significant differences (P < .05) were observed between anterior cruciate ligament–deficient and anterior cruciate ligament–intact specimens stained with hematoxylin and eosin in zone 3 for both transverse and longitudinal cuts. Significant differences were not found between anterior cruciate ligament–deficient and anterior cruciate ligament–intact specimens stained with safranin O. Conclusion Longitudinal meniscal tears occurring in anterior cruciate ligament–intact knees may result from early degenerative disease processes. Attempted repair of this diseased tissue may fail to have a positive effect on long-term preservation of the meniscus.

A comparison of joint stability between anterior cruciate intact and deficient knees: a new canine model of anterior cruciate ligament disruption

Transection of the canine anterior cruciate ligament (ACL) is a well-established osteoarthritis (OA) model. This study evaluated a new method of canine ACL disruption as well as canine knee joint laxity and joint capsule (JC) contribution to joint stability at two time points (16 and 26 weeks) after ACL disruption ( n=5/time interval). Ten crossbreed hounds were evaluated with force plate gait analysis and radiographs at intervals up to 34 weeks after monopolar radiofrequency energy (MRFE) treatment of one randomly selected ACL. Each contralateral ACL was sham treated. The MRFE treated ACLs ruptured approximately eight weeks (mean 52.5 days, SEM ± 1.0, range 48–56 days) after treatment. Gait analysis and radiographic changes were consistent with established canine ACL transection models of OA. Anterior–posterior (AP) translation and medial–lateral (ML) rotation were measured in each knee at 30°, 60°, and 90° of flexion with and then without JC with loads of 40 N in AP translation and 4 N m in ML rotation. A statistically significant interaction in AP translation included JC by cruciate ( P=0.02), and there was a trend for a cruciate by time ( P=0.07) interaction. Significant interactions in ML rotational testing included the presence of joint capsule ( P=0.0001) and angle by cruciate ( P=0.0012). This study describes a model in which canine ACLs predictably rupture approximately eight weeks after arthroscopic surgery and details the contribution of JC to canine knee stability in both ACL intact and deficient knees. The model presented here avoids the introduction of potential surgical variables at the time of ACL rupture and may contribute to studies of OA pathogenesis and inhibition. This model may also be useful for insight into the pathologic changes that occur in the knee as the ACL undergoes degeneration prior to rupture.

Biomechanics of the ACL: Measurements of in situ force in the ACL and knee kinematics

Injury of the anterior cruciate ligament (ACL) can lead to knee instability associated with damage to other knee structures and the increased risk of degenerative joint disease. This has led to the frequent use of intra-articular tissue grafts for ACL reconstruction in an attempt to restore normal knee function. Despite moderate success, the continued failure of ACL reconstruction to restore normal knee kinematics has led many investigators to study the role played by the ACL in normal knee motion. At our research center, we have focused on the development of a new and innovative approach to measure multiple degree of freedom (DOF) knee kinematics and to determine the in situ forces within the ACL. A unique testing system utilizing a 6-DOF robotic manipulator and universal force–moment sensor (UFS) has been developed such that these measurements can be made in a non-contact fashion while allowing a series of experiments to be performed on the same knee. In this manuscript, we will describe the functional and mathematical development of the robotic/UFS system and its use in a series of studies designed to give insight into the function of the ACL and ACL grafts. Our first study investigated the effect of constrained vs. unconstrained knee motion on anterior tibial translation and on the in situ force in the ACL. We found that unconstrained multiple-DOF knee motion significantly increased anterior tibial translation. While the magnitude of the in situ force remained similar to the more constrained condition, its direction, point of application and distribution between the anteromedial (AM) and posterolateral (PL) bundles were found to significantly change. These findings led us to investigate the effect of knee flexion angle and magnitude of anterior applied tibial load on the in situ force in the ACL and its bundles during unconstrained knee motion. We found the PL bundle of the human ACL to carry a greater proportion of the in situ force than the AM bundle near knee extension. Also, the change in magnitude of the in situ force in the PL bundle with changing knee flexion angle was similar to that of the entire ACL. This led us to conclude that the PL bundle must play a significant role in ACL function and in resisting anterior tibial load and that it should receive more serious consideration during ACL reconstruction. Lastly, we used our new testing system to examine two popular ACL reconstruction techniques: bone–patellar tendon–bone (BPTB) and quadruple semitendinosus/gracilis hamstring (QST/G) grafts. We compared them in terms of restoration of anterior tibial translation and reproduction of the in situ force in the intact ACL. Each reconstruction was performed on the same knee, allowing us to minimize interspecimen variability and take advantage of paired statistical analysis. We found that while both reconstructions effectively reduced anterior tibial translation secondary to anterior tibial loading to a level not significantly different from the ACL intact knee, use of a QST/G graft may be advantageous, as it reproduced the in situ forces of the intact ACL more closely. This series of three studies has garnered quantitative data to further our understanding of how the ACL functions and has yielded new concepts to help improve ACL reconstruction. Through the use of a robotic manipulator, our testing system has the capability to reproduce complex physiologic loading conditions that allow us to evaluate the efficacy of various ACL reconstruction techniques and rehabilitation protocols in the same knee. In the future, we intend to acquire in vivo kinematic data of the knee secondary to various functional and sporting activities and reproduce them using our robotic/UFS system such that in vivo in situ forces can be indirectly determined. We believe that such studies will provide a basis for the advancement of ACL reconstruction and rehabilitation.

Femoral intercondylar notch stenosis and correlation to anterior cruciate ligament injuries. A prospective study.

To evaluate the possible relationship between femoral intercondylar notch stenosis and anterior cruciate ligament injuries in pivoting and cutting sports, a 2-year prospective study was performed on intercollegiate athletes at a Division I university. Daily practice times and athlete participation in practices and games were recorded for each sport during the 2-year period. Bilateral intercondylar notch view radiographs were taken of all athletes enrolled in the study. The notch width index, a ratio that measures the width of the anterior outlet of the intercondylar notch divided by the total condylar width at the level of the popliteal groove, was measured for each knee. A total of 213 athletes, representing 415 anterior cruciate ligament-intact knees, were enrolled in the study. There were 7 anterior cruciate ligament tears. Statistical analysis demonstrated a correlation between femoral intercondylar notch stenosis and anterior cruciate ligament injuries. No statistical difference was found between the sex of the athlete and notch width indices or rate of anterior cruciate ligament tears. Athletes with intercondylar notch stenosis appear to be at increased risk for noncontact anterior cruciate ligament injuries.

Long-Term Results After Nonconstrained Total Knee Arthroplasty

In 1975, in Montreal, a nonconstrained total anatomic resurfacing prosthesis was designed. After a follow-up period of ten to 13 years, 79% of knees had an excellent or good result (Hospital for Special Surgery score) and 21% had a fair or poor result. Seven knees had been revised. The flexion range, stability, and capacity to climb stairs normally were significantly better in the knees where both posterior and anterior cruciate ligaments were preserved. Only one knee was revised in the anterior cruciate ligament intact knees. The incidence of aseptic component loosening was 1.2%.