Unicompartmental knee arthroplasty replaces only the arthritic compartment of the knee, preserving the healthy compartments and the native ligaments. Dr. Chudik performs robot-assisted unicompartmental replacement (MAKOplasty), which provides the precision required for the smaller, more technically demanding procedure. For appropriately selected patients, partial replacement preserves more native function than total knee replacement.
What Is Unicompartmental Knee Arthroplasty?
The knee has three compartments: medial (inside), lateral (outside), and patellofemoral (behind the kneecap). Arthritis often affects only one compartment, particularly the medial compartment in older adults. In these patients, replacing all three compartments (total knee replacement) is more invasive than necessary.
Unicompartmental knee arthroplasty replaces only the arthritic compartment, typically the medial femoral condyle and tibial plateau. The other two compartments and the native cruciate ligaments are preserved. The result is a smaller surgery, faster recovery, and a knee that feels more natural in motion than after total replacement.
Robot-assisted unicompartmental replacement (MAKOplasty) uses pre-operative CT scan data to plan the implant position and bone cuts on a 3D model of the patient’s knee. The robotic system guides bone preparation with sub-millimeter precision, which matters more in unicompartmental replacement than in total replacement because of the smaller surgical exposure and tighter tolerances.
Who Is a Candidate?
Candidates for unicompartmental knee arthroplasty typically have:
- Isolated single-compartment arthritis on imaging
- Intact and functional cruciate ligaments
- Adequate alignment that can be restored with partial replacement
- Acceptable range of motion and minimal flexion contracture
- Pain limited to the affected compartment
Patients with tricompartmental disease, significant ligament insufficiency, or substantial deformity are typically better served by total knee arthroplasty.
How the Procedure Is Performed
The procedure is performed through a smaller incision than total knee replacement. The arthritic compartment is exposed and the bone surfaces are prepared per the robotic-guided plan. The robot tracks the surgical instruments in real time and constrains bone preparation to the planned position, preventing cuts that would deviate from the optimal plan.
The femoral and tibial components for the affected compartment are implanted. A polyethylene bearing surface sits between them. The opposite compartment, the patellofemoral joint, and both cruciate ligaments are preserved.
Recovery and Rehabilitation
Recovery is faster than total knee arthroplasty:
- Same-day mobilization with physical therapy
- Walking with cane for one to two weeks
- Progressive range of motion and strengthening over four to six weeks
- Return to most daily activities by three to four weeks
- Return to low-impact sport at six to eight weeks
Risks and Outcomes
Risks include infection, component loosening, polyethylene wear, and progression of arthritis in the unreplaced compartments. Long-term survivorship is excellent in appropriately selected patients, with most modern unicompartmental implants surviving 15 to 20 years.
The main advantages over total replacement are faster recovery, more natural-feeling knee mechanics, and preservation of native ligaments and bone. The main disadvantages are the possibility that arthritis may progress in the unreplaced compartments, requiring conversion to total replacement years later.
Why Dr. Chudik for Unicompartmental Knee Arthroplasty
Dr. Chudik performs robot-assisted unicompartmental knee replacement using computer navigation that allows precise virtual planning and intraoperative guidance. The technology is particularly suited to partial replacement, where small variations in implant position have larger effects on long-term outcomes than they do in total replacement. His high case volume includes the full spectrum of knee replacement complexity, from straightforward unicompartmental cases to revision conversion to total replacement.