The progression from chronic anterior cruciate instability to degeneration of the knee has been well documented in animal studies. However, the literature is unclear as to the overall consequences with respect to the development of osteoarthritis. The long-term consequences of the anterior cruciate insufficient knee with or without associated medial collateral ligament insufficiency was investigated in 127 consecutive patients. The effects of meniscal injury and/or meniscectomy in the presence of ligamentous insufficiency was correlated with roentgenographic observations. A scoring system was devised and found to show that anterior cruciate insufficiency naturally progresses toward degenerative osteoarthritis. Meniscectomy with and without an associated medial collateral ligament insufficiency hastens the degenerative process. Progressive functional deterioration was shown to correlate with roentgenographic evidence of degenerative changes. The ultimate success of surgical repairs and reconstructions of the anterior cruciate ligament will not be based only upon functional return to activity or objective stability, but will also depend on the procedure's ability to prevent later development of degenerative osteoarthritis.