You are here

Partial knee replacement

Why replace what isn't broken?

Knees do not wear out evenly. Sometimes one part of the knee is perfectly fine while another part is completely destroyed. Depending on where the damage is in your knee, a partial knee replacement may be an option for you.

A partial, or unicondylar, joint replacement resurfaces only the worn out portion of the joint, either the inside, outside or kneecap, leaving the rest of the joint alone. To work properly, the components must be put in extremely accurately. Even a millimeter or two of tilt or rotation dramatically affects the wear patterns and longevity of the components. Think of how a car out of alignment means rapid tire wear.

Most surgeons are unable to perform partial knee replacements because of how difficult it is to achieve the required accuracy and so in many cases, even if a patient meets the criteria for a partial knee replacement, a more invasive total knee replacement will be offered.

The Stone Clinic robotic assisted surgery

Our track record of distinction

For unparalleled accuracy in placement, Kevin R. Stone performs a MAKOplasty® partial knee resurfacing procedure using the MAKO Surgical Corp Robotic Arm Interactive Orthopaedic System. The MAKO robot is the most sophisticated joint replacement system in the world. The system robotically guides the surgeon to precisely replace the joint, resulting in better alignment and reducing the risk of early wear.

Experienced and skilled surgeon

Kevin R. Stone, MD is one of the country’s most experienced outpatient MAKOplasty® surgeons.  Dr. Stone has performed 4500 knee operations with the same surgical team and a significant number of  partial knee replacements. He was one of the first surgeons to optimize outpatient robotic partial knee replacement. Follow up studies show a very high success rate with only one infection since robotic surgery was commenced in 2012. Dr. Stone is consistently listed as one of the country’s top 25 Ambulatory Surgery Center (ASC) leaders and ranks amongst the country’s top 100 knee surgeons.

Center of surgical excellence

The San Francisco Surgery Center is a state of the art facility for outpatient procedures only. It is a far superior experience to a hospital; the care is more efficient and personalized.  Infection rates are reduced. 

World-class physical therapy

Our skilled onsite physical therapists have developed a meticulous partial knee rehab protocol and work with patients to get them back to an active lifestyle within weeks.


How a MAKOplasty® works

  • A CT scan is made of the patient’s knee
  • A computer builds a custom 3D model of the patient’s knee based on the CT scan.
  • Before surgery, Dr. Stone plans the placement of the components using the virtual model, using real-time live motion data to adjust the position of the implants.
  • During surgery, the robotic arm and computer navigation provide Dr. Stone with pinpoint precision (within 1mm and 1 degree of the plan) to enable optimal implant positioning and alignment.
  • Just a few millimeters of bone need be burred smooth to allow for the implants to be fixed to the surface.

The benefits of a MAKOplasty®

  • Extremely high accuracy of anatomical placement
  • A more natural knee motion
  • Quick recovery
  • All 4 stabilizing ligaments remain intact (ACL, PCL, MCL, LCL)
  • No muscle cut
  • Non arthritic articular cartilage left alone
  • Small incisions
  • No staples to remove
  • Less pain
  • Minimal blood loss
  • Extremely low blood clot risk

With a partial knee replacement, the procedure is so minimal that in most cases, patients walk out of the surgery center 1½ hours after surgery and begin physical therapy the next day. 

Book an office evaluation or set up a phone consultation today and find out if you meet the criteria for a partial knee replacement.

Dr. Stone says ...

I am biased towards only replacing the parts that are worn out. I prefer to delay a full replacement if I can resurface the medial, lateral or patella femoral joint alone or in combination.  My patients recover faster, the knees feel more normal, and they do more sports with them.

If you have severe knee pain or chronic knee inflammation and swelling which cannot be improved by minor surgery or physical therapy, a doctor may recommend that you have total knee replacement surgery.
Best treatments for osteoarthritis
If you’ve been diagnosed with osteoarthritis, there’s a strong chance that you were advised to rest, limit your activities and use anti-inflammatory drugs to treat the symptoms of pain and inflammation. There are some major flaws in this advice.
If you have osteoarthritis, or if you think you may develop it later, you don’t have to just “suck up” the symptoms or change your life to manage the disorder. There is something that you can do about it, especially if you catch it early.
December 1st, 2013
What can you do if you’ve been diagnosed with arthritis but told to wait for a knee replacement? Is it possible to...
April 22nd, 2014
A major triumph for a company founded by Kevin R. Stone, M.D. The Z-Lig™ is the first engineered biologic device for...
March 11th, 2014
Dr. Stone contributes to an article about how sensors and apps will soon allow accurate, real time monitoring of...

Stone, K.R., A.W. Walgenbach, A. Freyer, T.J. Turek, and D.P. Speer. 2006.

Platelet-Rich Plasma (PRP) is blood plasma that has been enriched with platelets.