Medial Implantable Shock Absorber (MISHA) to Treat Medial Knee Arthritis in an Active Patient

Osteoarthritis is a leading cause of disability worldwide and most commonly affects the knee. Conservative management has limited long-term efficacy, and traditional surgical options present inherent challenges for the high-demand patient population, creating a treatment gap. Medial implantable shock absorber (MISHA) technology has been recently approved by the US Food and Drug Administration (FDA) for active patients with symptomatic medial compartment arthritis who are either unable or unwilling to undergo high tibial osteotomy (HTO) or arthroplasty. Select advantages include early return to full weightbearing without bracing, reversibility without "burning bridges," and favorable patient-reported outcomes.

We present a 58-year-old female, active military officer with a 9-month history of symptomatic medial knee osteoarthritis who had conservative measures that failed. Following informed consent regarding surgical options, the patient underwent left knee arthroscopy followed by open implantation of the MISHA Knee Implant.

Medial internal shock absorbers can serve to shield the medial compartment from abnormal loads, reduce pain, and improve function without altering the native knee joint or lower extremity anatomy. In a prospective nonrandomized cohort study supervised by the FDA, a comparison between MISHA and HTO demonstrated the favorable outcomes of the MISHA group in terms of pain, function, adverse events, implant integrity, and conversion surgery at the primary end point of 24 months.

In this surgical technique, we outline the key steps for implantation of the medial internal shock absorber to treat symptomatic medial compartment osteoarthritis in an active patient. We also review technical pearls and pitfalls and postoperative care, including rehabilitation and return to activity timelines and expectations.

The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.