Importance of the medial meniscus in the anterior cruciate ligament‐deficient knee

To establish a quantitative biomechanical relationship between the anterior cruciate ligament graft and the medial meniscus, 10 human cadaveric knees were examined using the robotic/universal force-moment sensor testing system. In response to a combined 134-N anterior and 200-N axial compressive tibial load, the resulting kinematics of the knee and the in situ forces in the anterior cruciate ligament, the anterior cruciate ligament graft, and the medial meniscus were measured. Anterior tibial translation significantly increased after anterior cruciate ligament transection, between 6.8±2.3 mm at full extension and 12.6±3.3 mm at 30° of flexion. Consequently, the resultant forces on the medial meniscus, ranging from 52±30 N to 63±51 N between full extension and 90° of knee flexion in the intact knee, were doubled as a result of anterior cruciate ligament deficiency. However, after anterior cruciate ligament reconstruction, anterior tibial translations were restored to the levels of the intact knee, and thus...

The biomechanical interdependence between the anterior cruciate ligament replacement graft and the medial meniscus.

Background:Meniscal root tears are an increasingly recognized subset of meniscal injury. The menisci are critical secondary stabilizers of the anterior cruciate ligament (ACL). The kinematic effect of lateral meniscus posterior root tear in the setting of ACL injury is not known.Purpose/Hypothesis:The purpose of this study was to determine the effect of tear of the lateral meniscal root on stability of the ACL-deficient knee. The hypothesis was that disruption of the lateral meniscal root will further destabilize the ACL-deficient knee during a simulated pivot shift.Study Design:Controlled laboratory study.Methods:Pivot-shift testing of 8 fresh-frozen cadaveric knees was performed after attachment of photoreflective flags and preparation of CT scans. Each knee was mounted in a custom activity simulator and dynamically loaded from 15° to 90° of flexion with all the permutations of the following: iliotibial band force (50, 75, 100, 125, 150, and 175 N), internal rotation moments (1, 2, and 3 N·m), and valgu...

Effect of Lateral Meniscal Root Tear on the Stability of the Anterior Cruciate Ligament–Deficient Knee:

Conservative treatment of acute anterior cruciate ligament injuries was recommended to selected patients, including those with sedentary occupations, low athletic demands, or ages greater than 30 years. Patients with generalized hyperligamentous laxity were excluded. Fifty-five of 61 patients were available at an average followup of 46 months from the time of initial injury. At followup, giving-way symptoms had not occurred in 23 patients (42%); in 22 (40%) giving way occurred occasionally. Of the 44 patients involved in high- or moderate-demand athletics, 33 (70%) were able to continue with moderate-demand sports. Presence of a medial collateral ligament sprain did not affect the longterm function. Forty-eight percent of the patients scored excellent or good (9 and 18 patients, respectively) on the Hospital for Special Surgery ligament scoring system; 8 (15%) later chose surgical reconstruction. The remaining 47 patients did not believe that their symptoms were severe enough to warrant any further intervention. In a group of individuals who are older and relatively inactive, nonoperative management of anterior cruciate ligament injuries can yield satisfactory results, provided the patients are willing to accept a modest amount of instability and a slight risk of meniscal injury.

Nonoperative Treatment of Acute Anterior Cruciate Ligament Injuries in a Selected Group of Patients

Although intrinsic and extrinsic risk factors for anterior cruciate ligament (ACL) injury have been explored extensively, the factors surrounding the inciting event and the biomechanical mechanisms underlying ACL injury remain elusive. This systematic review summarizes all the relevant data and clarifies the strengths and weaknesses of the literature regarding ACL injury mechanisms. The hypothesis is that most ACL injuries do not occur via solely sagittal, frontal or transverse plane mechanisms. Electronic database literature searches of PubMed MEDLINE (1966–2008), CINAHL (1982–2008) and SportDiscus® (1985–2008) were used for the systematic review to identify any studies in the literature that examined ACL injury mechanisms. Methodological approaches that describe and evaluate ACL injury mechanisms included athlete interviews, arthroscopic studies, clinical imaging and physical exam tests, video analysis, cadaveric studies, laboratory tests (motion analysis, electromyography) and mathematical modelling studies. One hundred and ninety-eight studies associated with ACL injury mechanisms were identified and provided evidence regarding plane of injury, with evidence supporting sagittal, frontal and/or transverse plane mechanisms of injury. Collectively, the studies indicate that it is highly probable that ACL injuries are more likely to occur during multi-planar rather than single-planar mechanisms of injury.

A 'plane' explanation of anterior cruciate ligament injury mechanisms: a systematic review.

In this study, 400 clinically anterior cruciate ligament (ACL) deficient knees were arthroscoped and studied prospectively in the period January 1986 to April 1992. An ACL tear was always confirmed, and 41 per cent of these patients did not have an associated meniscal tear. In 30.25 per cent the lateral meniscus was torn; in 21.25 per cent the ACL tear was associated with a medial meniscus tear, and in the remaining 7 per cent both menisci were torn. The most frequently associated meniscal injury was the bucket handle tear of the medial meniscus (9 per cent), followed by the posterior horn tear of the lateral meniscus, which showed the same frequency as the ragged (or degenerated) tear of the lateral meniscus (6 per cent). The horizontal tear of the posterior part of the lateral meniscus showed a prevalence of 4.3 per cent. This picture is probably dependent on a secondary referral nature of the centre surveyed, in which the average time between injury and arthroscopy was 23.3 months.

J.B. King

Papers

Patterns of meniscal tears associated with anterior cruciate ligament lesions in athletes.

Tendon problems in athletic individuals.