The MISHA Knee System is a prescription implant placed outside the knee capsule along the inner side of the knee. It shares load with the medial compartment without removing joint surfaces or cutting the tibia to change alignment.
It fills a narrow space between nonsurgical unloading and reconstructive surgery. It is not a miniature knee replacement, and it is not intended for every patient with knee arthritis.
Find surgeons whose official pages discuss MISHA Compare MISHA with HTO and other unloading options
Who falls within the FDA indication?
FDA authorized MISHA through the De Novo pathway in April 2023. The labeled indication is for patients with medial-compartment knee osteoarthritis who have not found relief with surgical and/or nonsurgical treatments, continue to have pain that interferes with daily activities, and are unwilling to undergo or ineligible for total knee replacement because of age or the absence of advanced osteoarthritis.
That wording is narrower than “anyone who wants to avoid a knee replacement.” Candidacy still depends on the arthritis pattern, alignment, ligament function, bone quality, symptoms, prior treatment, health, and device-specific contraindications.
How is it different from other unloading options?
| Option | How it unloads the knee | Bone cut? | Implant? |
|---|---|---|---|
| --- | --- | ---: | ---: |
| Unloader brace | External force shifts load away from one compartment | No | No |
| MISHA | Extracapsular shock absorber shares medial-compartment load | No | Yes |
| High tibial osteotomy | Realigns the tibia and weight-bearing axis | Yes | Fixation plate/screws are commonly used |
| Partial knee replacement | Replaces one damaged joint compartment | Bone preparation | Yes |
MISHA may preserve future options, but “joint preserving” does not mean risk-free or guaranteed to delay replacement.
What does the evidence show?
FDA reviewed a prospective multicenter study of 81 MISHA patients compared with 81 propensity-matched patients from a historical high tibial osteotomy study. At 24 months, the study met its prespecified noninferiority endpoint and showed clinically meaningful improvements in pain and function.
The comparison was not a randomized concurrent trial. FDA also noted uncertainty related to missing comparator data and the MISHA removal rate. In the reviewed cohort, 11 of 81 implants were removed and four patients had deep incisional surgical-site infections. FDA required five-year postmarket surveillance, and a randomized comparison with nonsurgical treatment is underway.
A fair summary is:
> MISHA has meaningful FDA-reviewed short- to mid-term evidence for a selected population, but long-term durability and comparative effectiveness are still being defined.
Current safety update: specified lots are under recall
Checked August 12, 2026: FDA lists an open Class II recall involving specified lots of the small left and small right MISHA implants. The recalled components may have nonconforming geometry that can contribute to fracture and new or worsening discomfort, swelling, pain, or stiffness.
The recall does not state that every MISHA implant is affected. FDA’s record identifies the specific reference numbers and lots. People with a MISHA implant should not use this page to determine whether their device is included; the implanting surgeon or facility can identify the device and lot.
Potential advantages
- Does not remove the joint surfaces.
- Does not require the bone realignment of an HTO.
- Designed specifically to unload the medial compartment.
- May allow faster weight bearing than an osteotomy in selected patients.
- Leaves knee replacement available if it is needed later.
Important tradeoffs
- It is an implanted device with risks of infection, pain, nerve or ligament injury, loosening, device failure, and later surgery or removal.
- Evidence is less mature than for established knee-replacement procedures.
- It applies to a narrow arthritis pattern.
- Insurance coverage, trained-surgeon access, and device availability may vary.
- The active lot-specific recall requires a prominent, maintained safety notice.
Questions to ask a surgeon
- Does my imaging show isolated medial-compartment disease that fits the labeled indication?
- Why would MISHA fit better than an unloader brace, HTO, partial knee replacement, or continued nonsurgical care?
- Which MISHA size and lot would be used, and how is the recall being handled?
- What are your rates of wound problems, infection, device removal, and later knee replacement?
- What restrictions and rehabilitation should I expect?
- What happens if the device does not relieve pain?
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