Browse the corpus

Unicompartmental knee arthroplasty (UKA) is a surgical technique used for the treatment of osteoarthritis in one compartment of the knee, most commonly in the medial compartment. In contrast, a total knee arthroplasty (TKA) is used for the treatment of osteoarthritis in all three compartments of the knee. UKA was first introduced in the 1970s. This activity reviews the indications for UKA and highlights the role of the interprofessional team in the management of patients with osteoarthritis. Objectives: Describe the indications for unicompartmental knee arthroplasty. Review the contraindications for unicompartmental knee arthroplasty. Summarize the clinical relevance of unicompartmental knee arthroplasty. Outline the importance of improving care coordination among interprofessional team members to improve outcomes for patients undergoing unicompartmental knee arthroplasty. Access free multiple choice questions on this topic.

Unicompartmental knee arthroplasty (UKA) is a surgical technique used for the treatment of osteoarthritis in one compartment of the knee, most commonly in the medial compartment.[1][2] In contrast, a total knee arthroplasty (TKA) is used for the treatment of osteoarthritis in all three compartments of the knee. UKA was first introduced in the 1970s.[2] Proponents for UKA argued that the procedure more closely mimics normal knee kinematics, leads to lower perioperative morbidity and intraoperative blood loss, and allows for earlier mobilization and rehabilitation compared to conventional bicondylar knee arthroplasty.[3] Early results, however, demonstrated high rates of failures, with a 28% rate of conversion to TKA at an average follow-up of six years.[4] Over time, modifications in the implant design, surgical technique, and the expansion of surgical indications have led to renewed interest in UKA. Furthermore, the increased demand for minimally invasive approaches has also increased the popularity of UKA, which requires a smaller incision compared to traditional TKA. The development of robotic-assisted techniques has improved surgical precision and component alignment in an effort to increase survivorship.[5]

Since the introduction of UKA several decades ago, the primary mechanism of failure has remained consistent in the literature, most commonly stemming from aseptic loosening, followed by progressive osteoarthritis.[1] A systematic review of UKA demonstrated that aseptic loosening (25%) and osteoarthritis progression (20%) accounted for more than half of all revisions in the first five years, while infection (5%) and polyethylene wear (4%) were less frequent.[11] Approximately 40% of mid- and late-term revisions were attributed to osteoarthritis progression.[29] Despite technological advances in UKA implants, the revision-free survival rate has remained constant, unlike improvements seen in TKA survival rate trends.[30] Some authors attribute this to the lower threshold by the surgeon to convert a UKA to a TKA, whereas a TKA revision is viewed as more technically demanding, with higher morbidity. Recent literature has refuted these claims by demonstrating similar complication and revision rates after UKA conversion and after primary TKA.[31]

Despite the excellent long-term survival rates after UKA in recent literature, there are substantial differences in outcomes demonstrated by cohort and registry data.[11] At 15 years, the average survival rate was 87% in cohort studies, as opposed to 67% in registry studies.[11] This discrepancy may be explained by variability in outcomes reporting and the inclusion of multiple surgeons with varying degrees of clinical volume. Registry studies offer the benefits of demonstrating trends in UKA over time and capturing a higher number of cases compared to cohort studies. For example, online data provided by the National Joint Registry for England, Wales, and Northern Ireland demonstrated better outcomes in UKA performed by surgeons who perform them 40 to 60% of the time compared to surgeons who perform them less than 5% of their total practice.[1] This data highlights that in addition to careful patient selection, surgeon experience plays a substantial role in optimizing outcomes after UKA. High-volume centers that employ dedicated orthopedic operating room staff, as well as nursing and therapy staff familiar with the procedure, will ensure both operational efficiency and postoperative care to optimize the patients’ outcomes. Preoperatively, a thorough assessment of the patient’s comorbid medical conditions helps minimize postoperative complications and length of stay. [Level 5]