Arthritis management with partial knee replacement

Knee arthritis is a common condition that can cause pain, stiffness and reduced mobility, particularly in older adults. While total knee replacement is often considered for advanced cases, some patients may benefit from a partial knee replacement, also known as unicompartmental knee replacement. This approach is less invasive and preserves more of the knee’s natural structure.

What is partial knee replacement?

Partial knee replacement is a surgical procedure that replaces only the damaged part of the knee joint, rather than the entire joint. The knee has three compartments: medial (inner), lateral (outer) and patellofemoral (front of the knee). If arthritis is confined to just one of these compartments, a partial replacement may be appropriate.

The procedure involves removing the damaged bone and cartilage and replacing it with metal and plastic components that mimic the function of the natural joint. This allows smoother movement and helps reduce pain.

When to consider surgery

Surgery should be considered when conservative measures such as weight loss, physiotherapy, pain relief and injections no longer control symptoms. If knee pain affects quality of life or limits daily activities, a consultation with an orthopaedic surgeon can help determine the most appropriate treatment, whether that’s a partial or total knee replacement is required.

NICE (National Institute for Health and Care Excellence) guidance in the UK recommends considering unicompartmental knee replacement for suitable candidates.

Who is a suitable candidate?

Not all patients with knee arthritis are suitable for partial knee replacement. The procedure is most effective for individuals who:

Have arthritis limited to one compartment of the knee
Maintain good range of motion and ligament stability
Have a correctable deformity
Do not have significant inflammatory arthritis (e.g., rheumatoid arthritis), as thedisease can spread to other compartments of the knee.

Age is not a limiting factor; suitability is based on joint condition and overall health rather than chronological age

A thorough clinical assessment, supported by imaging such as X-rays with specific views and occasionally an MRI scan, is essential to confirm suitability for partial knee replacement.

Benefits of partial knee replacement

Compared with total knee replacement, partial knee replacement offers several potential advantages:

Quicker recovery: Smaller incisions and less disruption to surrounding tissues can lead to faster healing.
Less pain after surgery: Reduced surgical trauma often results in lower post-operative discomfort.
Preservation of natural movement: As much of the original knee structure is retained, patients often experience a more natural feel.
Shorter hospital stay: Many patients return home the same day or after one night.
Lower risk of complications: Reduced likelihood of blood loss, infection and medical complications.

What does the recovery involve?

Most patients can begin walking with assistance soon after surgery and will be guided by a physiotherapist through a structured rehabilitation programme. Light activity often resumes within a few weeks, while more strenuous exercise should be avoided until the knee has fully healed, usually around six weeks to three months post-surgery.

Long-term outlook

Partial knee replacement generally provides very good pain relief and improvement in mobility for carefully selected patients. Modern implants have excellent long-term results, with studies showing that most last well over 10 to 15 years, and many longer, especially when implanted in suitable candidates. Recovery is often quicker compared with a total knee replacement, with many patients reporting a more “natural-feeling” knee. However, it is important to note that there is a small risk that arthritis can progress in the other compartments of the knee over time, which may lead to pain returning and, in some cases, the need for further surgery such as a total knee replacement in the future.