Dale M. Daniel

We followed 292 patients who had sustained an acute traumatic hemarthrosis for a mean of 64 months. The KT-1000 arthrometer measurements within 90 days of injury revealed the injured knee was stable in 56 patients and unstable in 236. Forty-five unstable patients had an ACL reconstruction within 90 days of injury. Surgical procedures performed > 90 days after injury included ligament reconstruction in 46 patients. Factors that correlated with patients who had late surgery for a meniscal tear or an ACL reconstruction (P < 0.05) were preinjury hours of sports participation, arthrometer measurements, and patient age. Follow-up data are presented for the patients divided into four groups: I, early stable, no reconstruction; II, early unstable, no reconstruction; III, early reconstruction; and IV, late reconstruction. No patient changed occupation because of the knee injury. Hours per year of sports participation and levels of sports participation decreased in all groups. Joint arthrosis was documented by radiograph and bone scan. Joint surface injury abnormalities observed at surgery and meniscal surgery showed greater abnormalities by radiograph and bone scan scores (P < 0.05). Reconstructed patients had a higher level of arthrosis by radiograph and bone scan.

We performed instrumented measurement of anterior-posterior laxity of the knee in thirty-three cadaver specimens, 338 normal subjects, and eighty-nine patients with unilateral disruption of the anterior cruciate ligament. The test instrument was the Medmetric knee arthrometer, model KT-2000. We measured total anterior-posterior laxity, produced by anterior and posterior loads of eighty-nine newtons (twenty pounds), and the anterior compliance index. The total anterior-posterior laxity is composed of an anterior displacement and a posterior displacement; these are measured from a testing reference position, defined as the resting position of the knee after applying and then releasing a posterior load of eighty-nine newtons. The anterior compliance index is defined as the anterior displacement between an anterior load of sixty-seven newtons and one of eighty-nine newtons. All tests were performed with the knee held on a thigh support that placed the knee in 20 +/- 5 degrees of flexion. The mean anterior displacement at eighty-nine newtons was 5.7 millimeters in a group of normal subjects and 13.0 millimeters in a group of patients with a disrupted anterior cruciate ligament. Ninety-two per cent of the normal subjects had a left knee-right knee difference in anterior displacement of no more than two millimeters, while 96 per cent of the patients with a unilateral disruption of the anterior cruciate ligament had an injured knee-normal knee difference in anterior displacement of more than two millimeters. Ninety-three per cent of the normal subjects had a difference in the left-right compliance index of no more than 0.5 millimeter, and 85 per cent of the patients with unilateral disruption of the anterior cruciate ligament had a difference in the compliance index of the injured and normal sides of more than 0.5 millimeter.

UNLABELLED: Between 1982 and 1986, 126 patients who had undergone ACL reconstruction were followed in a prospective manner. One year follow-up statistics were reviewed for the presence of 13 different complications. The most prevalent complications were quadriceps weakness, flexion contracture, and patellofemoral pain. Quadriceps weakness (strength less than 80% of the normal side) was present in 65% of patients and correlated positively with flexion contracture, patellar irritabibilty, and ACL reconstructions using patellar tendon grafts. Flexion contracture of 5 degrees or more was present in 24% of patients and correlated positively with increased age and patellar irritability. Patellofemoral pain was present in 19% of patients and correlated positively with flexion contracture. CLINICAL RELEVANCE: The three most common complications of knee ligament surgery are shown to be strongly interrelated. It is likely that a causal relationship is present in which flexion contracture causes patellofemoral irritability, and that both of these factors, alone or in combination, result in quadriceps weakness. If this theory is correct, then it is crucial that postoperative rehabilitation programs place a major emphasis on the avoidance of flexion contracture.

Instrumented anterior/posterior laxity measurements were performed on 138 patients evaluated within 2 weeks of injury with their first traumatic knee hemarthrosis. All patients were tested with the MEDmetric Arthrometer model KT-1000 in a knee injury clinic. Seventy-five of the patients had knee arthroscopy. Thirty-three had arthrometer laxity tests under anesthesia. Eighty-seven percent of patients arthroscoped had anterior cruciate ligament (ACL) tears and 41% had meniscus tears. One hundred twenty normal subjects were tested to establish normal anterior laxity values. Three tests were used to evaluate anterior laxity: anterior displacement between a 15 and 20 pound force (compliance index), anterior displacement with a 20 pound force, and anterior displacement with a high manually applied force. Displacement measurements in normal subjects revealed a wide range of normal laxity with a small right knee-left knee difference. For example, the 20 pound anterior displacement range was 3 to 13.5 mm with a right knee-left knee difference (mean +/- SD, 0.8 +/- 0.7 mm). Eighty-eight percent of the normals had a right-left difference of less than 2 mm. In the 53 patients arthroscoped who had complete ACL tears, the anterior laxity measurements performed in the clinic were suggestive or diagnostic of pathologic anterior laxity in 50 patients.

This study was undertaken to evaluate the medial ligamentous stabilizers of the patella in restraining lateral displacement and to assess their relative contribution after individual repair. Seventeen fresh frozen human anatomic specimen knee joints were studied. The specimens were loaded onto a testing instrument that was designed to measure the compliance of the medial and lateral patellar restraints in the coronal plane. Two different cutting and repair sequences were used to test the individual contributions of the patellar ligaments. The medial patellofemoral ligament was found to be the major medial ligamentous stabilizer of the patella. Isolated release resulted in a 50% increase in lateral displacement, and isolated repair restored balance to the patella. In addition, the patellotibial and patellomeniscal ligament complex played an important secondary role in restraining lateral patellar displacement. Isolated repair of these ligaments restored balance to near normal levels. The medial patellofemoral retinaculum played only a minor role in patellofemoral instability. Proximal realignment or medial ligament repair for patellofemoral instability specifically should address repair of the deep layers that contain the restraints to lateral patellar displacement. Failure to include these structures in repair, especially of the medial patellofemoral ligament, may lead to persistent or recurrent instability.