Unicompartmental and Bicompartmental Partial Knee Replacement

What is a partial knee replacement, and what are the benefits? Learn more about Conformis unicompartmental and bicompartmental partial knee replacement options for osteoarthritis.

What is a Partial Knee Replacement?

Partial knee replacement (PKR) is a less invasive alternative to total knee replacement. During a partial knee replacement,  only the damaged compartments of the knee are replaced in either a unicompartmental or bicompartmental procedure, as opposed to replacing the entire knee join in a total knee replacement (TKR) procedure. It is estimated that approximately one third of patients treated for knee osteoarthritis have disease involving just two of the three compartments of the knee.

Benefits of Partial Knee Replacement vs Total Knee Replacement

Traditionally, a total knee replacement (TKR) would be used to remove bone from all three compartments, at the cost of one or both of the anterior cruciate ligaments (ACL) and posterior cruciate ligaments (PCL). However, osteoarthritis (OA) disease pattern studies have shown that bicompartmental disease is the most common disease pattern found amongst knee OA patients. For example, Rolston L., et al., tracked 100 patients older than 40 years of age, and identified through radiographic interpretation that 73% had involvement of both medial and patellofemoral compartments, but no lateral involvement1.

Bicompartmental partial knee replacements using the iDuo G2 provide a less invasive alternative to total knee replacement for patients suffering from disease in the medial (inner) or lateral (outer) compartment of the knee, along with the patellofemoral joint (the area behind the kneecap). By targeting just the diseased portions of the joint, partial knee replacements utilizing the iDuo G2 enable appropriately selected patients to preserve all of their ligaments and far more bone than a traditional total knee replacement options.

Conformis Options for Unicompartmental or Bicompartmental Knee Replacement

The iUni is a personalized unicompartmental knee replacement product for the treatment of the medial or lateral compartment of the knee.

The iDuo is the only personalized bicompartmental knee replacement system on the market. With the iDuo G2, a surgeon can treat just the affected compartments with a precise, patient specific implant that delivers unparalleled fit, preserves all ligaments and conserves far more bone than traditional TKA. Not only does this provide patients with a more natural knee motion, it also preserves future treatment options — a benefit to both patients and surgeons alike.

Patient satisfaction is a result of multiple factors: setting realistic expectations, proper implant design, intuitive and reproducible surgical technique, and post-op patient compliance. A true patient specific implant and instrument system ensures the implants will provide optimal fit for the patient while delivering a simplified surgical technique that makes the OR experience smooth and reproducible.

Learn more about partial knee replacement options from Conformis below.


1Rolston L, et al.; Bicompartmental knee arthroplasty: a bone-sparing, ligamentsparing and minimally invasive alternative for active patients; Orthopedics;
Aug 2007; Vol. 30(8):pp. 70-73; PMID: 17824339

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