Partial knee replacement, also known as unicompartmental knee replacement, is a surgical procedure designed to relieve arthritis in one specific part of the knee. Unlike total knee replacement which replaces the entire knee joint, this surgery targets only the damaged area, preserving as much of the natural knee structure as possible. This procedure is suitable for patients with arthritis confined to a single knee compartment.

Differences Between Partial Knee Replacement and Total Knee Replacement

The primary distinction between partial and total knee replacement surgeries lies in the extent to which the knee joint is replaced. Here are the key differences:

Scope of Surgery

  • Partial Knee Replacement: Only the damaged compartment of the knee—either the medial (inside), lateral (outside), or patellofemoral (front) compartment—is replaced.
  • Total Knee Replacement: The entire knee joint is replaced, including all compartments, regardless of where the damage is localised.

Recovery and Rehabilitation

  • Partial Knee Replacement typically involves a shorter hospital stay, quicker recovery, and less postoperative pain, allowing patients to often return to daily activities sooner.
  • Total Knee Replacement may require a longer rehabilitation period and more time before the patient experiences full benefits, due to the more extensive nature of the surgery.

Surgical Outcome and Knee Function

  • Partial Knee Replacement aims to preserve as much of the knee’s natural structure and function as possible, potentially resulting in a more natural feeling in the knee post-surgery.
  • Total Knee Replacement replaces the entire knee joint with a prosthetic, which may feel less natural than a partial replacement but is necessary for those with advanced arthritis throughout the knee.

Benefits of Partial Knee Replacement

Partial knee replacement surgery offers several advantages, particularly for patients with arthritis that is confined to a single part of the knee. These benefits include:

  • Less Invasive Procedure: The surgery requires smaller incisions and less bone removal compared to total knee replacement, thereby preserving more of the knee’s natural anatomy.
  • Faster Recovery: Patients typically experience a quicker recovery time, shorter hospital stays and a faster return to daily activities and work.
  • Reduced Pain and Blood Loss: With less tissue trauma and a smaller operative area, patients often report less post-operative pain and minimal blood loss during surgery.
  • Better Knee Function: Because the unaffected parts of the knee are left intact, patients may achieve a more natural range of motion and function.
  • Lower Risk of Complications: The reduced complexity and invasiveness of the procedure may lead to a lower risk of surgical complications, such as infections or blood clots.

Who is Suitable for Partial Knee Replacement?

Candidates typically experience pain and limited mobility and have not responded to non-surgical treatments such as medications, physical therapy, or lifestyle changes. Suitability for partial knee replacement also depends on the specific condition and structural integrity of the knee, as assessed by the doctor. Candidates are usually older adults with a moderate activity level, maintaining a healthy weight, and having stable knee ligaments. It’s recommended to consult a doctor if you’re experiencing persistent knee pain or mobility issues, as they can accurately assess whether you need a knee replacement. Candidates typically share the following characteristics:

Localised Knee Arthritis

People with osteoarthritis who are confined to a single compartment of the knee, whether it be the medial, lateral, or patellofemoral compartment, are prime candidates.

Intact Ligaments

The presence of intact ligaments, such as the anterior cruciate ligament (ACL), is important for the stability and success of a partial knee replacement.

Range of Motion

Candidates should have a relatively good range of motion in the knee joint pre-surgery. Stiffness or significant limitation in movement may affect the outcomes of a partial replacement.

Absence of Inflammatory Arthritis

Candidates without widespread inflammatory arthritis, such as rheumatoid arthritis, tend to respond better to partial knee replacement, as the procedure targets localised degenerative changes rather than systemic joint inflammation.

Age and Activity Level

While there’s no strict age limit, partial knee replacement is often recommended for older people with moderate activity levels.

Risks and Complications Associated with Partial Knee Replacement

As with any surgical procedure, partial knee replacement carries potential risks and complications.

Surgical Risks

  • Infection: Though rare, infections can occur at the incision site or within the joint, requiring antibiotics or further surgery to address.
  • Blood Clots: The risk of developing blood clots in the leg veins is present, necessitating preventive measures such as blood-thinning medication or mechanical compression devices.

Prosthetic Issues

  • Wear and Loosening: Over time, the prosthetic components may wear down or loosen, potentially leading to pain and the need for revision surgery.
  • Implant Failure: While modern implants are designed for durability, there is a small risk of failure, necessitating replacement.

Postoperative Complications

  • Stiffness and Limited Mobility: Some patients may experience stiffness or limited range of motion in the knee, often addressed through physical therapy.
  • Pain: Persistent or new pain post-surgery can occur, requiring further evaluation and management.

Long-term Considerations

  • Progression of Arthritis: Arthritis may progress in the parts of the knee that were not replaced, potentially leading to further interventions.
  • Revision Surgery: Although partial knee replacements can last many years, a revision to a total knee replacement may become necessary if the joint deteriorates or complications arise.

Conclusion

Partial knee replacement offers a less invasive option for those with localised knee arthritis, providing benefits such as faster recovery and more natural knee function. Patients need to consider the potential risks and long-term implications, including the possibility of revision surgery.