Partial Knee Replacement

Description

A partial knee replacement (PKR) is a surgical procedure that replaces only part of the damaged knee joint. It can replace the inner part of the knee, the outer part, or the kneecap.

• Partial knee replacement has several advantages over total knee replacement, including shorter recovery time and greater range of motion preserved after surgery. However, partial knee arthroplasty is only suitable for people whose knee joint is only damaged on the outer medial side or one part of the patella [1].
• Surgery to replace the entire knee joint is called a total knee replacement.

Indication

The most common reason for partial knee replacement is unicompartmental knee injury from advanced osteoarthritis [1]

Partial knee replacement is also used in patients with joint disease and moderate knee deformity due to rheumatoid arthritis or traumatic arthritis.

Partial knee replacement surgery improves pain and function, similar to total knee replacement, for people with osteoarthritis that affects only a single compartment of the knee. Partial knee replacement surgery is also less expensive. [2]

Diagnostic Tests

1. X-rays. These images help determine the extent of damage and deformity in the knee. Multiple x-rays of the knee are done to look for signs of arthritis.
2. Magnetic resonance imaging (MRI) scan. Some surgeons may also order an MRI scan to better evaluate the cartilage [3].

Surgical Procedures and Types of Partial Knee Replacement

Types

A unicompartmental knee replacement is a surgery that replaces only the affected single compartment (medial or lateral) of the knee.

Patellofemoral arthroplasty is a surgery to replace the worn patella (kneecap) and trochlea (groove at the end of the thighbone).

A bicompartmental knee replacement is a surgery that replaces the two compartments of the knee joint, the medial compartment and the patellofemoral compartment.

Pre-operative Preparation

Preoperative preparation begins immediately after the surgical consultation and lasts for approximately one month.

Patient performs range of motion exercises and hip knee and ankle joint strengthening (isometric view) as directed by therapist.

Before surgery, preoperative tests are done: usually a complete blood count, electrolytes, APTT, and PT to measure blood clotting, a chest x-ray, an electrocardiogram, and blood crossmatching for possible transfusions.

• About a month before surgery, patients may be given iron supplements to raise hemoglobin in the blood system.
• An accurate x-ray of the affected knee is required to measure the dimensions of the required components. Medications such as warfarin and aspirin are stopped a few days before surgery to reduce the amount of bleeding.
• If the preoperative workup is done in the preanesthesia clinic, the patient may be admitted the day of surgery, or may be admitted one or more days before surgery. Some hospitals offer preoperative seminars for this procedure [4].
• Preoperative education is an important part of patient care today. There is some evidence that it may slightly reduce anxiety before knee replacement surgery, with a low risk of harmful effects. [5] There is currently insufficient quality evidence to support the use of preoperative Physical therapy for older adults undergoing total knee replacement [6]
• Bariatric surgery before knee replacement does not appear to change outcomes. [7]

Physiotherapy Rehabilitation

Rehabilitation Exercises: Help maintain range of motion and restore strength. The exercises are the same as for a total knee replacement, see here.

Hospital discharge.

Patients who have had partial knee replacements generally experience less postoperative pain and swelling, and recovery is easier than those who have had total knee replacements. In most cases, patients will go home 1 to 3 days after surgery. Some patients go home the day of surgery [3] (depending on patient’s health status and the amount of support available outside the hospital). [8] Due to quadriceps weakness [10], use of crutches or a walker to protect weight bearing until prescribed by the surgeon [9]

To increase the likelihood of a good outcome after surgery, several weeks of physical therapy are required. During these weeks, the therapist will help the patient return to normal activities and prevent blood clots, improve circulation, increase range of motion, and ultimately strengthen Work the muscles around you with specific exercises.

Protocol Physiotherapy Rehabilitation

Week 1: Goals

• Decrease pain/swelling.
• Passive range of motion <90 degrees (secondary to sutures) x 2 weeks.
• Full weight bearing.

Week 2 – 4: Goals

• Decrease pain/swelling.
• Tolerate bilateral stationary cycling.
• Active range of motion 0-90 degrees.

Week 4 – 6: Goals

• Normal gait pattern.

Week 6 – 8: Goals

• Active range of motion 0 to 110 degrees.
• Passive range of motion 120 degrees.

Week 8 – 12: Goals

• Walk downstairs with reciprocal gait.
• Full range of motion.[11]

Treatment includes encouraging patients to move as soon as possible after surgery. [12] Usually range of motion (to the limits of the prosthesis) is restored within the first two weeks (the sooner the better). Over time, the patient is able to increase the weight bearing on the operated leg, and Under the guidance of a physical therapist, eventually be able to bear full weight bearing.

• After about ten months, patients should be able to return to normal daily activities, although the operated leg may be significantly weaker than the non-operated leg. [13]

For uncomplicated knee replacements, continuous passive motion (CPM) can improve recovery. [14] In addition, CPM is inexpensive and convenient, which helps patients adhere to treatment. However, CPM should be used in conjunction with traditional physical therapy. in unusual circumstances CPM may be useful if the person has problems that prevent standard mobilization treatment.

Key evidence for contraindications and common side effects

• Some physicians and patients may consider ultrasonography of lower extremity veins to screen for deep vein thrombosis after knee replacement surgery. However, such screening should be done only when indicated. If there is a medical condition that could lead to deep vein thrombosis, doctors can choose Treat patients with cryotherapy and intermittent pneumatic compression as a preventive measure. [15]
• Partial knee replacement surgery is not suitable for patients with certain types of infection Any psychiatric or neuromuscular disease that creates an unacceptable risk of prosthetic instability Failure of prosthetic fixation or complications of postoperative care Skeletal immaturity Severe Unstable knees or excess body weight.
• Common side effects: As with any surgery, PKR has its risks, which may be implant-related risks that may lead to revision, including dislocation, loosening, fractures, nerve damage, heterogeneous ossification, implant wear, metal sensitivity, soft tissue imbalance, Osteolysis (localized progressive bone dissolution) loss) and response to particle debris.
• Knee implants may not provide the same feel or performance characteristics as a normal healthy joint.