5-Year Results of an Implantable Shock Absorber Demonstrate Durable Outcomes in Patients with Medial Knee Osteoarthritis.

Abstract

The implantable shock absorber (ISA) addresses patients within the knee osteoarthritis treatment gap between failure of nonsurgical care and arthroplasty. This follow-up of a prospective, open-label, comparative cohort study reports effectiveness and safety outcomes at 5 years. Eighty-one participants received the ISA. Participants had statistically significant improvement in Western Ontario and McMaster Universities Arthritis Index (WOMAC) pain (mean 43.4 point improvement, p < 0.0001) and function (mean 42.1 point improvement, p < 0.0001) versus baseline, beginning 6 weeks postsurgery, and remaining statistically significant and clinically meaningful through the 5-year follow-up. The study was designed to satisfy regulatory requirements, and survival was defined, a priori, in the study protocol with US Food and Drug Administration to be freedom from conversion to arthroplasty or high tibial osteotomy. At 5 years, 73/81 (90.1%) participants reported conversion-free survival. ISA provided benefits that were statistically significant and clinically meaningful for at least 5 years. Based on these 5-year data of durable, conversion-free survivorship, the ISA has proven to be a treatment option for medial knee osteoarthritis patients.