Articular responses to purified cartilage proteoglycans.

To examine whether proteoglycans (PGs) liberated from cartilage might contribute to articular changes in arthritis, cartilage PGs were injected intraarticularly into rabbit knee joints. Twice-weekly injections of PG (2.5 mg) provoked synovial hypertrophy, synovitis, erosion of the articulating surfaces, and loss of metachromasia of the articular cartilage. These changes were accompanied by a marked elevation in the production of neutral collagenase and gelatinase by both synoviocytes and chondrocytes. The synoviocytes of experimental knee joints also produced factor(s), possibly related to interleukin-1, which provoked the activation of chondrocytes. Our data are consistent with the idea that free PG fragments mediate some of the pathophysiologic changes that occur in arthritic joints. This property may be particularly important in osteoarthritis.

Isolated contracture of the abductor digiti minimi.

A case of isolated contracture of an intrinsic hand muscle, the abductor digiti minimi, after the use of an upper extremity tourniquet is reported. Six cadaver specimens were studied after latex arterial injection. We present an anatomic study and pathomechanical analysis, along with a review of the literature on tourniquet-associated injuries.

Objective anterior cruciate ligament testing.

We examined subjects with the Stryker knee laxity tester as part of the clinical examination to determine its usefulness in evaluating the anterior cruciate ligament. We measured 123 athletes with no history of knee injury, as well as 30 patients with ACL injury proven by arthroscopy, and 11 injured patients with intact ACL at arthroscopy. We recorded anterior and posterior tibial displacement at 20 degrees of knee flexion and 20 lbs force in each direction. Anterior laxity and side to side difference correlated with ACL injury; posterior and total AP laxity did not. In normal subjects, mean anterior laxity was 2.5 mm. Only 8% of normal knees had anterior laxity of 5 mm or more. Ten percent of normal subjects had a side to side difference of 2 mm or more. In ACL tears, mean laxity was 8.1 mm, with 94% measuring 5 mm or more. Of the subjects, 89% with unilateral ACL injury had an increase of 2 mm or more on the injured side. Ten of ten acute ACL tears were detected by these criteria, with no false positives. In injured knees with intact ACL, measurements did not differ significantly from normal. We found the objective knee laxity measurement to be a useful complement to clinical knee examination.