What is Lateral Approach Total Knee Replacement?
Lateral approach total knee replacement is a surgical procedure employed for the treatment of valgus deformity of the osteoarthritic knee. The procedure involves approaching the knee joint from the lateral side of the patella (kneecap) or on the outer aspect of the knee to remove and replace the worn-out or damaged surfaces of the knee joint with a prosthesis to treat valgus deformity of the knee. This approach is also known as the Keblish approach or lateral parapatellar approach and is deemed to promote better soft tissue balance and patellar tracking for a total knee replacement on a valgus knee. The lateral approach is recommended as the “approach of choice” for fixed valgus deformity in total knee replacement due to its good/excellent result.
Anatomy of the Knee
The knee is made up of the femur (thighbone), the tibia (shinbone), and the patella (kneecap). The lower end of the thighbone meets the upper end of the shinbone at the knee joint. A small disk of bone called the patella (kneecap) rests on a groove on the front side of the femoral end. A bone of the lower leg (fibula) forms a joint with the shinbone. The bones are held together by protective tissues, ligaments, tendons, and muscles. Synovial fluid within the joint aids in the smooth movement of the bones over one another. The meniscus, a soft crescent-shaped area of cartilage between the femur and tibia, serves as a cushion and helps absorb shock during motion.
Indications for Lateral Approach Total Knee Replacement
Some of the indications for using a lateral approach in a total knee replacement include :
- Lateral unicompartmental replacement
- Fixed valgus knee deformity with patellar subluxation
- Grossly unstable knee with enlarged suprapatellar pouch
- Partly correctable valgus with patellar subluxation and/or lateral orientation
- Previous lateral incisions with multiple knee operations and risk of skin undermining
- Varus knee with acute tibial rotation, tight retinaculum, increased Q-angle, and iliotibial band (ITB) with patellar subluxation or tilt
Preparation for Lateral Approach Total Knee Replacement
Preoperative preparation for lateral approach total knee replacement will involve the following steps :
- A thorough examination by your doctor is performed to check for any medical issues that need to be addressed prior to surgery.
- Depending on your medical history, social history, and age, you may need to undergo tests such as blood work and imaging to help detect any abnormalities that could threaten the safety of the procedure.
- You will be asked if you have allergies to medications, anesthesia, or latex.
- You should inform your doctor of any medications, vitamins, or supplements that you are taking.
- You should refrain from medications or supplements such as blood thinners, aspirin, or anti-inflammatory medicines for 1 to 2 weeks prior to surgery.
- You should refrain from alcohol or tobacco at least 24 hours prior to surgery.
- You should not consume any solids or liquids at least 8 hours prior to surgery.
- Arrange for someone to drive you home as you will not be able to drive yourself post surgery.
- A written consent will be obtained from you after the surgical procedure has been explained in detail.
Procedure for Lateral Approach Total Knee Replacement
The surgery is performed under spinal or general anesthesia. Your surgeon will make a longitudinal incision lateral to the patella to expose the knee joint.
Then, the damaged portions of the femur bone are cut at appropriate angles using specialized jigs. The femoral component is attached to the end of the femur with or without bone cement. Your surgeon then cuts or shaves the damaged area of the tibia (shinbone) and cartilage. This removes the deformed part of the bone and any bony growths, as well as creates a smooth surface on which the implants can be attached.
Next, the tibial component is secured to the end of the bone with bone cement or screws. Your surgeon will place a plastic piece called an articular surface between the implants to provide a smooth gliding surface for movement. This plastic insert will support the body’s weight and allow the femur to move over the tibia, like the original meniscus cartilage.
The femur and tibia with the new components are then put together to form the new knee joint. To make sure the patella (kneecap) glides smoothly over the new artificial knee, its rear surface is also prepared to receive a plastic component.
With all the new components in place, the knee joint is tested through its range of motion. The entire joint is then irrigated and cleaned with a sterile solution. The incision is carefully closed, drains may be inserted and a sterile dressing is placed over the incision.
Postoperative Care and Recovery
In general, postoperative care instructions and recovery after lateral approach total knee replacement will involve the following steps :
- You will be transferred to the recovery area to be monitored until you are awake from the anesthesia.
- Your nurse will monitor your blood oxygen level and other vital signs as you recover.
- You may notice some pain, swelling, and discomfort in the knee area. Pain and anti-inflammatory medications are provided as needed.
- Medications will also be prescribed as needed for symptoms associated with anesthesia, such as vomiting and nausea.
- Antibiotics are prescribed to address the risk of surgery-related infection.
- Keep the surgical site clean and dry. Instructions on surgical site care and bathing will be provided.
- You will be placed on crutches for the first few weeks with instructions on restricted weight-bearing. You are encouraged to walk with assistance as frequently as possible to prevent blood clots.
- Use of a continuous passive motion machine (CPM) at home may be advised during the first few weeks to aid in constant movement of the knee joint under a controlled range of motion.
- You are advised to keep your leg elevated while resting to prevent swelling and pain.
- Refrain from smoking as it can negatively affect the healing process.
- Eating a healthy diet rich in vitamin D is strongly advised to promote healing and a faster recovery.
- Refrain from strenuous activities and lifting heavy weights for the first couple of months. Gradual increase in activities over a period of time is recommended.
- An individualized physical therapy protocol is designed to help strengthen your knee muscles and optimize knee function.
- You will be able to resume your normal activities in a couple of months; however, return to sports may take 4 to 6 months.
- A periodic follow-up appointment will be scheduled to monitor your progress.
Benefits of Lateral Approach Total Knee Replacement
Some of the important benefits of lateral approach total knee replacement include :
- Minimizes soft tissue damage
- Preserves quadriceps muscle function
- Maintains blood supply to the patella
- Averts lateral patellar subluxation
- Grants direct access to lateral section in a valgus knee
- Helpful for a fixed valgus deformity
Risks and Complications
Lateral approach total knee replacement is a relatively safe procedure; however, as with any joint replacement surgery, possible risks and complications may occur, such as :
- Knee stiffness
- Blood clots (deep vein thrombosis)
- Nerve and blood vessel damage
- Ligament injuries
- Patella (kneecap) dislocation
- Wearing out of the plastic liner
- Loosening of the implant
- Allergic/anesthetic reaction