Unicompartmental mobile-bearing knee arthroplasty

Area of Science:

• Orthopedic surgery
• Biomedical engineering

Background:

• Two mobile-bearing unicompartmental knee replacement designs exist since the late 1970s.
• Designs differ in bearing constraint: one is tracked, the other freely moving.
• Both are indicated for medial unicompartmental osteoarthritis in the US.

Purpose of the Study:

• To compare the outcomes of two mobile-bearing unicompartmental knee replacement designs.
• To highlight the benefits of mobile-bearing designs in restoring knee kinematics and protecting polyethylene.
• To emphasize critical factors for successful implantation.

Main Methods:

• Review of available literature and clinical experience with mobile-bearing unicompartmental knee implants.
• Analysis of patient selection criteria and surgical technique requirements.
• Examination of survivorship data for freely mobile-bearing implants.

Main Results:

• Mobile-bearing designs restore normal knee joint kinematics and reduce polyethylene stress.
• Successful outcomes are critically dependent on meticulous patient selection and surgical technique.
• Key patient criteria include anteromedial osteoarthritis, correctable varus deformity, and intact anterior cruciate ligament.
• Ten-year survivorship rates for freely mobile-bearing implants range from 85% to 98%.

Conclusions:

• Mobile-bearing unicompartmental knee replacement is a viable option for specific osteoarthritis patients.
• Careful patient selection and precise surgical technique are paramount for optimal results.
• Survivorship rates are comparable to those of total knee replacement, indicating long-term efficacy.