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 pa tients and unstable in 236. Forty-five unstable patients had an ACL reconstruction within 90 days of injury. Sur gical procedures performed >90 days after injury in cluded 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 mea surements, 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 recon struction;​ and IV, late reconstruction. No patient changed occupation because of the knee injury. Hours per year of sports participation and levels of sports par ticipation decreased in all groups. Joint arthrosis was documented by radiograph and bone scan. Joint sur face injury abnormalities observed at surgery and me niscal surgery showed greater abnormalities by radio graph and bone scan scores (P < 0.05). Reconstructed patients had a higher level of arthrosis by radiograph and bone scan.