Neuropathic joint disease — a particularly severe form of rapidly progressive osteoarthritis of the foot and ankle — is characterized by multiple ligament abnormalities and diffuse bone edema even early in the disease process, a small retrospective British study found.
Patients with neuropathic joint disease had a median of three partial or complete ligament tears, a finding that was not seen in any patients in a comparator group who had the more common, degenerative form of osteoarthritis (P=0.005), according to Jill Halstead, MSc, of the University of Leeds, and colleagues.
Those with the neuropathic condition also had higher scores for diffuse bone marrow edema, which was detected in a median of 6.5 tarsal bones compared with only two adjacent bones in the osteoarthritis group (P=0.005), the researchers reported in the August Arthritis & Rheumatism.
Whereas foot and ankle degenerative osteoarthritis typically progresses slowly and is not associated with joint deformity, the neuropathic condition, which is most often associated with diabetes, is characterized in late phases by bone debris, joint destruction, and new bone formation.
But limited data are available on anatomic factors that could be predictive of disease progression, and conventional radiography is not sufficiently sensitive to detect early changes.
To more fully characterize the early phase of neuropathic arthritis, when timely intervention could help limit the damage, Halstead and colleagues performed an exploratory study comparing MRI findings in 15 patients with osteoarthritis of the ankle and foot and seven patients with neuropathic joint disease.
Six of these seven had diabetes, and the median duration of their sensory neuropathy was seven years.
Linear bone disruption consistent with the presence of fractures was seen in two or more bones in almost all patients with neuropathic disease and in only one bone in a single osteoarthritis patient.
The neuropathic condition also was characterized by ligament and capsular disruption, joint subluxation of the hindfoot, and abnormalities of the major supporting ligaments of the midfoot.
Some signal abnormalities were common to both groups, such as focal bone marrow edema with cysts, osteochondral and cartilage defects, and joint effusions. Articular cartilage damage also was seen in both groups.
The authors stated that these observations confirm that extensive bone edema and fracture formation are early features of neuropathic joint disease near the time of clinical presentation, helping explain the presence of bone debris in the synovium, which has long been recognized as an early histologic feature.
“Importantly, the results of this study link the outcome of degenerative arthritis of the foot and ankle to ligament- and bone-based, rather than articular cartilage-based, pathologic abnormalities,” the researchers noted.
The findings also support a theory of neurotraumatic origin for neurogenic joint arthritis, with sensory and proprioception loss leading to damage of the joint.
The investigators noted that it was not clear whether changes in bone or ligaments occur first, but they considered ligaments more likely because of the prominent role these structures have in proprioception.
According to the authors, the diffuse bone involvement seen in these patients also may have implications for treatment, because prompt administration of bisphosphonates might slow the joint remodeling.
They acknowledged that the study had limitations, including small sample sizes, unmatched group sizes, and unequal timing of MRI scans in the two cohorts.
“The interesting finding of ligament damage and bone debris in early [neuropathic joint disease] requires further investigation in a larger cohort,” they concluded.
Source : MedPage Today