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Partial Knee Replacement: Is It For You?

By James D. Holtzclaw, M.D.

As the exuberant baby-boom generation ages into its 50’s, younger patients are seeking treatment for chronic knee pain in order to maintain active lifestyles. When conservative measures (NSAID’s [Nonsteroidal anti-inflammatory drugs], cortisone or gel injections) no longer provide symptomatic relief, arthroscopic procedures to clean out or debride small areas of degenerated cartilage can prolong the life on one’s knee. When arthritis advances to the point where the cartilage is completely worn out (bone on bone), artificial joint replacement becomes a possible solution.

The knee joint is comprised of three anatomic compartments. The medial compartment is the inner aspect of the knee joint and is most commonly afflicted with arthritis. The lateral compartment is on the outer aspect of the knee and is least commonly involved. The patellofemoral compartment is between the kneecap and the front of the distal thigh bone. For patients with extensive arthritis involving more than one compartment, total knee replacement is an option which provides excellent pain relief and is a procedure with a reliable, proven track record. For patients in whom the arthritis is limited to a single compartment, partial knee replacement is an option with some attractive benefits.

Unicompartmental knee replacement (UKR) procedures have been performed around the world for over 40 years. The incidence of UKR procedures is highest in Australia and Scandinavia. More than twice as many UKR’s are performed in Australia than in the USA. In the USA, 90 percent of knee joint replacements are total joint replacements (TKR) and 10 percent are unicompartmental (UKR). The low proportion of UKR procedures can be partially explained by the strict criteria for patient selection.

There are some clear benefits to those patients who are candidates for UKR. Studies have shown UKR is a less invasive procedure with a smaller incision, reduced blood loss, less post-op pain and faster recovery time. (1) Patients who have had both TKR and UKR implants report that a UKR implant feels more “normal” and was preferred. (2) Some additional benefits include a greater range of motion and better joint function than TKR. (3) Length of hospital stay is less with UKR than TKR .(1)

So why aren’t more UKR’s done in the USA? The answer is that most patients do not meet the selection criteria for UKR. The patient’s arthritis and pain symptoms should be limited to a single compartment. Most patients have significant involvement of more than one compartment by the time they are referred to an orthopaedic surgeon. The patient should also be near their ideal body weight. UKR is contradicated in obese patients as they are susceptible to early loosening of the components. The knee joint must also be free of any fixed ligament contractures and have intact cruciate ligaments (ACL/PCL). As younger patients are seeking surgical treatment for their arthritic knees, the number of candidates for UKR is growing. Many patients have returned to active lifestyles that include exercise walking, hiking, cycling, tennis, golf and skiing.

Partial knee replacement (UKR) is an excellent surgical option in the right patient. It should be part of the discussion with your orthopaedic surgeon if you are considering knee replacement surgery.

For more information about knee replacement surgery or other orthopædic issues, Dr. Holtzclaw can be contacted at Chatham Orthopædic Associates, P.A., 4425 Paulsen Street, Savannah, Georgia 31405 or call him at (912) 355-6615 or visit