Implantation of a shock or load absorber for mild to moderate symptomatic medial knee osteoarthritis

Device fracture 7 months after implantation was reported in a case report of 1 patient. A 2‑stage revision procedure was performed and the device was completely removed without any further complications.

Infection of the tibial wound attributed to prolonged physical activity was reported 6 weeks after the procedure in a case report of 1 patient. The patient was initially treated with antibiotics but the infection did not resolve. The patient subsequently had a 2‑stage revision procedure involving removal of the load absorber with antibiotics for 6 weeks followed by insertion of a new absorber 3 months after the infection was resolved.

Persistent pain led to the removal of the device in 4% (4 out of 99) of patients in the case series between 2 and 10 months after implantation.

Surgery was done for failure to improve symptoms in 6% (6 out of 99) of patients in the case series of 99 patients: 4 patients had total knee arthroplasty and 2 patients had high tibial osteotomy.

Recurring pain within 6 months of implantation was reported in 2 patients in the case series of 99 patients. Further details were not reported.

In addition to safety outcomes reported in the literature, specialist advisers are asked about anecdotal adverse events (events which they have heard about) and about theoretical adverse events (events which they think might possibly occur, even if they have never done so). For this procedure, specialist advisers listed the following anecdotal adverse events: soft tissue irritation, impingement, dislocation, or uncoupling of the device needing removal. They considered that the following were theoretical adverse events: thrombotic events (deep vein thrombosis leading to pulmonary embolism); stiffness of the knee; and bone loss adjacent to anchoring sites that could compromise future salvage surgery including joint replacement.