Unicompartmental knee arthroplasty: Current indications, technical issues and results

Area of Science:

• Orthopedic surgery
• Biomedical engineering
• Knee joint biomechanics

Background:

• Unicompartmental knee arthroplasty (UKA) is a surgical option for knee osteoarthritis (OA).
• Patient selection and implant type influence UKA outcomes.
• Understanding contraindications and long-term efficacy is crucial for surgical decision-making.

Purpose of the Study:

• To define contraindications for UKA.
• To evaluate the medium-term and long-term results of UKA.
• To compare outcomes between different UKA bearing types and assess outpatient UKA protocols.

Main Methods:

• Review of existing literature on UKA indications, contraindications, and outcomes.
• Analysis of implant survival rates, failure mechanisms, and complication rates.
• Evaluation of clinical results and cost-effectiveness of outpatient UKA.

Main Results:

• Age <60, high BMI, heavy work, chondrocalcinosis, and patellofemoral (PF) joint bone exposure are not UKA contraindications.
• Severe lateral PF joint wear with bone loss is a contraindication.
• Medial UKA requires severe medial OA (medial/lateral ratio <20%).
• 10-year implant survival >95% for medial OA/osteonecrosis UKA.
• 10-year survival 94%, 15-year survival 91% considering all re-operations.
• Aseptic loosening is an early failure mode for mobile-bearing UKA; OA progression for fixed-bearing.
• Complication and re-operation rates are similar for mobile and fixed bearings.
• All-polyethylene implant survival is comparable to metal-backed designs.
• Outpatient UKA achieves ~50% cost savings and satisfactory clinical results.

Conclusions:

• UKA is a viable option for carefully selected patients with knee OA.
• High implant survival rates and good functional outcomes are achievable with UKA.
• Outpatient UKA is safe, effective, and cost-efficient, expanding treatment accessibility.