Efficacy of Surgical Joint Denervation in Painful Digital Osteoarthritis

Osteoarthritis is the most common joint pathology of the musculoskeletal system. It affects 6 million French people and constitutes a public health problem. Osteoarthritis of the hands or digitalis is the second localization of symptomatic osteoarthritis, after the knee. Its main risk factors are female sex, age, genetic factors, and obesity. Osteoarthritis combines articular cartilage degradation, synovial inflammation, subchondral bone remodeling and osteophyte development. Its cardinal symptoms are pain and functional impairment (at a level sometimes close to inflammatory rheumatism such as rheumatoid arthritis), particularly intense in the case of the erosive form. There is also local joint inflammation associated with pain. Pain in osteoarthritis is a complex phenomenon involving joint tissues other than cartilage, a tissue that is not innervated (subchondral bone, joint capsule, synovial membrane). There is currently no etiological treatment for osteoarthritis. Symptomatic treatments have a modest efficacy, which justifies the search for new treatments. The surgical options are arthrodesis or prosthesis, invasive techniques potentially sources of complications, and finally proposed infrequently given the prevalence of digital osteoarthritis. The only current conservative surgical solution that can be proposed for intractable painful proximal interphalangeal joint (PIPJ) osteoarthritis is denervation. This technique consists of cutting the nerve branches intended for the PIPJ in order to directly interrupt the pain pathways. It reduces pain by 80% after 5 years, without loss of mobility. There are only 4 published series reporting the results of this technique (2-3). These were retrospective case series with a low level of evidence. The patient satisfaction rate reached 90%, with transient paresthesias as the only reported complication. The mechanism of action for the effectiveness of this intervention has never been studied. Our hypothesis is that denervation of the PIP has clinical efficacy in painful digital osteoarthritis refractory to usual treatments, and that it would have a structural effect that can be objectified on MRI. The results of this pilot study will make it possible to construct a prospective randomized study.