What Is an Unicompartmental Knee Arthroplasty?

A unicompartmental knee arthroplasty (UKA) is a surgical procedure in which only the damaged parts of the knee are replaced in one of the knee compartments.

A unicompartmental knee arthroplasty (UKA)is a surgical procedure used to relieve disease in one of the knee compartments. In UKA, only the damaged parts of the knee are replaced. The UKA surgery may reduce postoperativepainand have a shorter recovery period than atotal knee replacementprocedure, especially in the elderly population.

Knee arthroplastyis also called aknee replacement手术。手术包括移除damaged parts of theknee jointand replacing them with parts constructed with metal, ceramic, and very hardplastic.

This artificial joint is also called a prosthesis or an implant. It reducespainand improves the function of the knee joint. Knee arthroplasty is indicated when the knee joint is damaged.Arthritisis the most common cause of knee joint damage and, hence, one of the most common indications for knee arthroplasty.

The three compartments of the knee joint

The ends of the bones, where the bones in the knee joint move against each other the most, are most likely to suffer damage. These areas are known as compartments, and they are as follows:

• The medial or inside compartment
• The lateral or outside compartment
• The patellofemoral or behind-the-kneecap compartment

There are various surgical approaches to the surgery, including minimally invasive techniques. The choice of technique depends on the surgeon’s decision.

To undergo a unicompartmental knee arthroplasty (UKA), the damage to the joint should be confined to only one compartment. UKA may be indicated in the following conditions if it is limited to a single compartment:

• Osteoarthritis
• Osteonecrosis(tissue death)
• Malalignment
• Mild deformities

Contraindications for a unicompartmental knee arthroplasty (UKA) include the following:

• Inflammation of the joint
• Previous surgery with overcorrection
• Septic arthritis(joint infection) andsepsis(systemic infection)
• Ligament tears leading to joint instabilities
• Tibial (shin bone) or femoral (thigh bone) shaft deformity
• Major joint deformities
• Damage in more than one compartment

Prior to the surgery, the surgeon performs a complete physical assessment, X-ray andmagnetic resonance imaging(MRI) of the joint.

The surgery is performed using general anesthesia. The concept behind a unicompartmental knee arthroplasty (UKA) is the replacement of only the damaged part of the knee and the preservation of as much normal tissue and bone as possible to allow the restoration of normal kinematics.

A conventional incision is usually around 12 inches in length, whereas the incision in UKA is around 7 cm. The damaged part of the joint is replaced with a prosthetic. The surgery can also be performed arthroscopically (minimally invasive). A small incision of around 3-4 inches in length is made over the area of the knee joint through which an arthroscope (a camera with a light source) and surgical instruments are inserted. The surgicalwoundis closed with缝合线(stitches) and dressed.

After the surgery, painkillers and antibiotics are administered. Patients are usually discharged between one and three days after the surgery. Patients are encouraged to walk with support the same or next day to prevent the formation ofblood clots.

物理治疗会在医院,和the patient would be advised to continue the exercises at home. Pain, swelling, andbruisingdue to the surgery are reduced in two weeks. Most patients can resume their routine activities in less than 6-12 weeks.

Recovery and joint strength continue to improve. Complete recovery after the surgery may take around six months, after which patients can resume high impact exercises and sports.

Some complications encountered are as follows:

• Osteolysis (inflammation destroying the bone and causing the prosthesis to loosen)
• Infection
• Bleeding
• Formation of blood clots
• Bone necrosis (bone death)
• Different leg lengths leading to altered gait/limp
• Migration or failure of the prosthesis
• Dislocation orfractureof the joint
• 骨折around the joint
• Residual disease in the other compartments
• Reaction to anesthesia