Osteochondral Surface Research Articles

Relative contribution of the ACL, MCL, and bony contact to the anterior stability of the knee.

Ligaments and other soft tissues, as well as bony contact, all contribute to anterior stability of the knee joint. This study was designed to measure the in situ force in the medial collateral ligament (MCL), anterior cruciate ligament (ACL), posterolateral structures (PLS), and posterior cruciate ligament (PCL) in response to 110 N anterior tibial loading. The changes in knee kinematics associated with ACL deficiency and combined MCL+ACL deficiency were also evaluated. Utilizing a robotic/universal force-moment sensor system, ten human cadaveric knee joints were tested between 0 degrees and 90 degrees of knee flexion. This unique testing system is designed to determine the in situ forces in structures of interest without making mechanical contact with the tissue. More importantly, data for individual structures can be obtained from the same knee specimen since the robotic manipulator can reproduce the motion of the intact knee. The in situ forces in the ACL under anterior tibial loading to 110 N were highest at 15 degrees flexion, 103 +/- 14 N (mean +/- SD), decreasing to 59.2 +/- 30 N at 90 degrees flexion. For the MCL, these forces were 8.0 +/- 3.5 N and 38.1 +/- 25 N, respectively. Forces due to bony contact were as high as 34.1 +/- 23 N at 30 degrees flexion, while those in the PLS were relatively small at all flexion angles. Combined MCL+ACL deficiency was found to significantly increase anterior tibial translation relative to the ACL-deficient knee only above 60 degrees of knee flexion. These findings confirm the hypothesis that there is significant load sharing between various ligaments and bony contact during anterior tibial loading of the knee. For this reason, the MCL and osteochondral surfaces may also be at significant risk during ACL injury.

Abduction-traction injury of the knee.

Disruption of the major ligaments of the knee was seen in six young men, five parachutists and a house painter, after what we have termed abduction-traction injury. This unusual complaint results from the application of a sudden block to the ankle while falling head first, leading to traction and abduction of the knee. All the patients underwent operations, generally with unsatisfactory results. At operation tears of the anterior cruciate ligament, medial collateral ligament and posterior oblique ligament were seen in each case; in four patients the posterior capsule and in three the posterior cruciate ligament also were torn. In one patient the lateral collateral ligament was torn and the lateral meniscotibial ligament was avulsed. The compression component is absent in this type of injury and consequently the menisci and the osteochondral surfaces of the tibia and femur remained intact in each case.

Osteochondritis Dissecans of the Posterior Femoral Condyle

Osteochondritis dissecans of the posterior femoral condyle is an uncommon condition. In many respects--the large size of the joint, involvement of the weight-bearing surface, natural history, method of treatment, and the population affected--it differs from the more usual condition found in the intercondylar region. In 14 cases (16 involved knees), representing the total number of cases found in the province of British Columbia during a five-year period, nearly every patient was a young male athlete. If the patient is treated before the age of 15 years, the condition may heal spontaneously or with a regimen of restricted activity. From this time, the lesion remains fairly stable and mildly symptom-producing, often for many years, until finally the osteochondral surface fragment breaks free into the joint. Once the fragment has separated, surgery becomes mandatory. To prevent degenerative joint changes and major disability is a challenge to the surgeon. Fragment removal, even with drilling of the base, has proved ineffectual. The fragment must be replaced and stable and exact anatomic realignment of the weight-bearing condylar surface restored. Multiple drilling perforations through the sclerotic base are required to stimulate revascularization. Because of the difficulty, and sometimes impossibility, of successfully meeting these exacting surgical requirements, the operation should be performed before the osteochondral fragment breaks free. The surgical technique is designed to restore vascularity to the ischemic bone and to maintain the normal contour of the condylar surface, without violating the articular cartilage surface.