The development of osteoarthrosis in unstable knee joints of dogs after transection of the anterior cruciate ligament is greatly accelerated when the afferent nerve fibers from the ipsilateral hindlimb have been interrupted by dorsal root ganglionectomy before transection. The purpose of the current study was to determine whether partial loss of the afferent fibers from the knee joints of dogs, accomplished by neurectomy of the primary articular nerves before transection of the ligament, also accelerates the development of osteoarthrosis. Osteoarthrosis did not develop in dogs that had had transection of the medial, posterior, and lateral articular nerves to the left knee joint but had an intact anterior cruciate ligament. Osteoarthrosis developed in all dogs that had had transection of the anterior cruciate ligament. However, the osteoarthrotic lesions, as gauged by histological and macroscopic criteria, were more frequent and severe in dogs that had had neurectomy before transection than in those that had intact sensory nerves and an unstable joint (p less than or equal to 0.05). A subchondral fracture occurred in three dogs that had had neurectomy and had an unstable joint but in none of the dogs that had intact sensory nerves and an unstable joint.