Secondary osteoarthritis after tibial plateau fracture was found in 44% of 131 cases at 7.6 (3.3-13.4) years follow-up. Narrowing of the joint space was noted during the first 7 years after injury, usually in the same compartment as the fractured plateau. The incidence slightly increased with the age of patients. Removal of a meniscus during the fracture surgery resulted in secondary degeneration in 74% of the cases. When a meniscus was intact or repaired, the proportion of degenerative cases was only 37%. Normal or slight valgus alignment of the tibial plateau with intact menisci protected best against secondary degeneration. On the other hand, medial or lateral tilt of the tibial plateau with a removed meniscus was followed by osteoarthritis in most cases. The severity of articular irregularities correlated poorly with the degenerative process. Associated ligamentous injuries as well as postoperative infection increased the incidence of secondary degeneration.