Partial Knee Replacement

Precision Surgery for Targeted Relief

While a total knee replacement addresses degeneration of the entire joint, a Partial Knee Replacement (also known as Unicompartmental Knee Arthroplasty) is a highly specialised procedure designed for patients whose arthritis is confined to just one "compartment" of the knee.

Dr Adam Farrier is a consultant knee surgeon offering partial (unicompartmental) knee replacement for patients in Carlisle and across Cumbria, including West Cumberland (Whitehaven), and in Newcastle upon Tyne and the North East.

Is a Partial Knee Replacement Right for You?

The knee is divided into three main compartments: the medial (inner), lateral (outer), and patellofemoral (front/kneecap). If your cartilage damage is limited to only one of these areas—and your ligaments are healthy—you may be a candidate for this bone-preserving surgery. All three compartments can be individually replaced. With partial knee surgery, considerably more bone is preserved (an improved description for the procedure should be a partial knee resurfacing rather than ‘replacement’).

Preserving Options for the Future

One of the most significant advantages of a Partial Knee Replacement is the flexibility it offers, particularly for our younger, more active patients.

Crucially, choosing a partial replacement provides greater reassurance should further surgery be required in the future. Because the procedure is bone-preserving, it can be seamlessly transitioned to a total knee replacement if the original implant eventually wears out or loosens over time.

In contrast, a total knee replacement can only be followed by a ‘Revision Knee Replacement.’ This is a more complex undertaking that involves the removal of substantially more bone and is often associated with higher risks and less predictable outcomes.

The Evidence on Longevity in clinical experience, the likelihood of a partial knee replacement requiring further surgery is not significantly higher than that of a total knee replacement. By opting for a targeted approach now, your anatomy can be preserved while ensuring you remain a candidate for the full range of surgical solutions in the decades to come.

The Benefits of "Thinking Small"

Because this procedure is less invasive than a total knee replacement, patients often experience:

• A More "Natural" Feel: Because we preserve your healthy bone and ligaments (like the ACL), the knee often retains its natural proprioception (balance and feel).

• Faster Recovery: Most patients return to daily activities and low-impact sports significantly sooner.

• Less Pain & Swelling: Smaller incisions and less bone removal typically mean a smoother post-operative period.

• Better Range of Motion: Patients often achieve a greater degree of flexion (bending) compared to total replacements.

• Lower risk of all complications: Patients undergoing partial knee replacement experience lower rates of common complications including surgical wound problems, blood clots, stiffness and instability.

• Forgotten knee: Patients experience the highest chance of "forgetting" they have had a knee replacement.

Important Considerations & Risks

As with any surgical procedure, it is important to understand the potential risks. These include standard surgical risks (infection, numb patch of skin, nerve and vessel injury, or blood clots) and specific considerations such as:

• Arthritis Progression: Arthritis may eventually develop in the untreated parts of the knee.

• Revision Rates: Partial replacements (~30%) have a slightly higher long-term revision rate compared to total knee replacements (~18%) at 25 years. 

• Technical Precision: This surgery is technically demanding and requires a surgeon with specific expertise in knee kinematics.

Dr. Farrier’s Note: "My goal is always to keep you active using the most conservative surgical option possible. For the right patient, a partial knee replacement isn't just a surgery; it's a way to get back to the sports and activities you love with a knee that feels like your own."

Frequently Asked Questions: Understanding Revision Surgery

It is natural to have questions about the longevity of your implant and what happens if a "re-do" is needed. Here are the most common concerns addressed:

What exactly is "Revision" surgery?

Revision surgery occurs when a previous implant needs to be replaced. If you have a Partial Knee, a revision usually involves moving to a Total Knee Replacement. Because we preserved your healthy bone and ligaments during the first surgery, this transition is very similar to a standard primary knee replacement.

If you already have a Total Knee, a revision is more complex, as it requires specialised implants to compensate for the additional bone loss. This makes outcomes (pain and function) less predictable.

Why might a partial knee need to be revised?

The two most common reasons are:

• Arthritis Progression: Arthritis may eventually develop in the other compartments of your knee that were originally healthy.

• Loosening: Over many years, the bond between the implant and the bone can weaken.

Other reasons include:

• Infection: A rare complication where bacteria colonises the implant leading to implant failure. Superficial wound infection occurs in 2-3% of surgeries while deep infection requiring washout and potential further surgery occurs in 1%.

• Peri-prosthetic Fracture: Where the bone around the implant breaks.

Does a partial knee wear out faster than a total knee?

While historical data suggested partials had a higher revision rate, modern techniques and better patient selection (like the criteria I use in my clinic) have closed that gap significantly. For many active patients, the "natural feel" and improved function of a partial knee far outweigh the statistical difference in longevity.

Will my recovery be harder if I need a revision later?

Transitioning from a Partial to a Total knee typically has a recovery profile similar to an initial knee replacement. However, revising a Total to a Revision Total is a more significant recovery process, which is why I aim to be as conservative as possible with your first procedure.