Partial Knee Arthroplasties

Partial knee arthroplasty, specifically involving the medial side of the knee joint, has gained popularity as a proven technique for treating anteromedial osteoarthritis (AMOA) with quicker patient recovery and lower risk of major medical complications compared to total knee arthroplasty (TKA). In addition, more recent data has shown comparable survival profiles out to 10 years in line with those of TKA. Functionally intact knee ligaments, specifically the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), and medial collateral ligament (MCL) were historically thought to be necessary for long-term success of medial unicompartmental arthroplasty (UKA) as early studies showed a high rate of aseptic loosening of the tibial baseplate in ACL-deficient knees at early term follow-up in mobile bearing designs. More recent evidence however has suggested that a functionally intact ACL may not be required for medial UKA depending on the age of the patient, functional status, and primary complaint, whether of pain or instability symptoms, especially when using a fixed bearing design. Similarly, an intact PCL may not be required for medial UKA when using a fixed bearing design if the slope of the tibial implant can be minimized and the functional demands of the patient are minimized; however, definitive data is still lacking on optimal patient selection. For younger patients with end-stage AMOA and ACL deficiency who maintain an active lifestyle but complain of pain and/or instability, combined medial UKA and ACL reconstruction can be the treatment of choice, either done concurrently during the same operation or as staged procedures with the ACL reconstruction occurring first and only proceeding to medial UKA if persistent pain remains postoperatively.