Unicompartmental knee arthroplasty

Unicompartmental Knee Arthroplasty (UKA), also known as a partial knee replacement, is a surgical procedure used to relieve arthritis in one of the knee compartments. Where the knee is divided into three major compartments, the UKA replaces only the damaged compartment, leaving the healthy parts of the knee intact. This contrasts with Total Knee Arthroplasty (TKA), where all the knee compartments are replaced.

Indications

UKA is indicated for patients with osteoarthritis that is limited to a single compartment of the knee, typically the medial compartment, which is the most commonly affected area. Ideal candidates are those with:

• Isolated unicompartmental osteoarthritis
• Intact anterior cruciate ligament (ACL)
• Limited inflammation
• Minimal deformity of the knee
• Adequate range of motion

Procedure

The procedure involves the surgical removal of the damaged cartilage and bone from the affected knee compartment and replacing them with metal and plastic components. The metal components replace the damaged surfaces of the thigh bone (femur) and the shin bone (tibia), while a plastic insert is placed between them to ensure smooth movement.

Advantages

UKA offers several advantages over TKA, including:

• Quicker recovery time
• Less blood loss during surgery
• Preservation of knee anatomy and kinematics
• Better post-operative knee function

Risks and Complications

As with any surgical procedure, UKA carries risks and potential complications, including:

• Infection
• Blood clots
• Implant wear and loosening
• Persistent pain
• Need for revision surgery

Recovery

Recovery from UKA generally involves less time than recovery from TKA. Patients can often begin walking with assistance the day after surgery and may return to normal activities within six weeks. However, a full recovery can take up to three months and involves physical therapy to restore strength and mobility.

Comparison with Total Knee Arthroplasty

While UKA is less invasive and has a quicker recovery time than TKA, it is not suitable for all patients. The decision between UKA and TKA depends on the extent of the knee damage, patient activity level, and overall health.

Future Directions

Advancements in surgical techniques and implant design continue to improve the outcomes of UKA. Robotic-assisted UKA is an emerging field that offers the potential for even more precise implant placement and alignment, potentially improving the longevity and function of the implant.