Neuropathic (Charcot) arthropathy is a slowly progressive, chronic, destructive form of joint degeneration seen in patients with a neurosensory deficit. Attempts to produce neuropathic joint disease experimentally with a variety of deafferentation procedures have generally been unsuccessful. However, if the knee is rendered unstable by anterior cruciate ligament transection (ACLT), breakdown of the joint occurs rapidly in dogs that have previously undergone dorsal root ganglionectomy (DRG) for deafferentation of the ipsilateral limb. In contrast, ACLT in neurologically intact dogs produces only nonprogressive changes that are characteristic of mild osteoarthritis. This report describes 3 patients with longstanding insulin‐dependent diabetes mellitus in whom neuropathic arthropathy developed within weeks after minor trauma to the foot or ankle. In these patients, diabetic neuropathy served as the functional equivalent of dorsal root ganglionectomy, and the minor trauma served as the functional equivalent of ACLT. Together, they illustrate the phenomenon of neurogenic acceleration of joint degeneration in humans.

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Salicylates suppress net glycosaminoglycan synthesis in articular cartilage. The inhibitory effect is greater in osteoarthritic (OA) cartilage than in normal cartilage. Whether the isolated OA chondrocyte is inherently more susceptible to the effects of salicylate on glycosaminoglycan metabolism has not been determined. The results of this study show that, after isolation from the extracellular matrix, normal and OA chondrocytes in suspension culture are similarly susceptible to the metabolic effects of salicylate. However, chondrocytes from the contralateral knees of dogs with unilateral OA were notably resistant to the effects of salicylate.Salicylates produce reversible, concentrationdependent suppression of proteoglycan (PG) synthesis by normal articular cartilage in vitro. The effect is much greater in osteoarthritic (OA) cartilage than in normal cartilage (1). Since uptake of ''C-acetylsalicylic acid by slices of OA cartilage has been shown to be significantly greater than that by normal cartilage (I), the depletion of negatively charged PGs in the matrix of OA cartilage presumably facilitated diffusion of the weakly acidic salicylate into the matrix. This possibility was supported by data demonstrating increased suppression of PG synthesis in normal cartilage after enzymatic depletion of its PGs (2).The above data do not exclude the additional possibility that in OA, the chondrocyte, which is intrinsically hypermetabolic (3,4), may be more susceptible than normal to the effects of salicylate. In the present study, we used isolated chondrocytes in suspension cultures, rather than cartilage organ cultures, to examine the susceptibility of the OA chondrocyte to salicylate. MATERIALS AND METHODSSurgical procedures. OA was induced in a standard manner in 9 normal adult mongrel dogs (25-30 kg) by transection of the anterior cruciate ligament of the right knee (1). Postoperatively, all dogs bore weight on the operated limb by the third day and ambulated freely in caged runs (4 feet x 8 feet) until they were killed 10-13 weeks later. Nine additional adult mongrel dogs that underwent no surgical procedure were used as normal controls.Tissues. At the time the dogs were killed, fullthickness samples of the articular cartilage and underlying subchondral bone were obtained from the central regions of the habitually loaded area of the medial femoral condyle of both knees of each animal for histologic study. Slices of articular cartilage (10-15 mg wet weight) were taken from the same sites for determination of dry weight and uronic acid concentration. The remainder of the cartilage from the articular surfaces of the medial and lateral femoral condyles and tibia1 plateaus was used for isolation of chondrocytes.