Robotic-Arm Assisted Partial Knee Replacement

Robotic knee replacement is performed very accurately with robotic technology which results in execution of a surgical plan to implant the prosthetic partial replacement within a single millimeter of precision.  Prior to surgery, a CT scan permits generation of a digital model of the affected limb and the size and position is selected for reproduction at surgery using a robotic arm which prepares the bone for accepting the implant.  Prior to final bone preparation, intraoperative fine-tuning of implant position based on soft tissue balance is performed so that isometry of the ligaments is achieved (the ligaments have the same tension throughout a range of motion).  Cartilage mapping positions the front portion of the implant for a smooth interface with native cartilage surfaces.  The use of robotic technology and the resultant improved accuracy of prosthesis positioning may improve outcomes and rates of survivorship of the implant.

Partial knee replacement is performed as an outpatient where the patient leaves the surgical facility the same day.  The procedure is done through a small incision under deep sedation with spinal anesthesia with numbing placed around the knee so that immediate walking and even stairs can be performed the same day.  Discharge is recommended within hours of the procedure in most cases which permits recovery at home.  Physical therapy is required for a few weeks to optimize range of motion and strength.  Most patients can return to independent activities within 2-3 weeks when any assistive device such as a cane is discontinued.  By 2-3 months, the recovery is nearly fully complete with return to leisure activities such as tennis or golf around that time.  Patients undergoing the procedure will report subtle improvements for up to one year.

Because of improvements in surgical precision with sizing and positioning of the implant with robotic technology, improvements in the wear characteristics of the bearing (moving part of the prosthesis), wear rates and long-term survivorship are excellent in the appropriately selected patient undergoing partial knee replacement.  Evidence suggests survivorship of >90% at 10 years with conversion to total knee replacement as the definitive endpoint on survival(1).  It remains within a reasonable degree of certainty that with modern technique and implants, the partial replacements will have improved durability compared with prior models with conventional instruments.  The biggest long-term risk of a partial replacement is the other compartments of the knee become arthritic and wear out, requiring a conversion to total knee replacement.

Total knee replacement provides a powerful ability to address more severe forms of arthritis, particularly where other compartments (sections) of the knee are involved.  The most common form of knee arthritis is that affecting the inner (medial) compartment.  As arthritis progresses, the limb can undergo a deformity where motion becomes significantly impaired, contracture sets in and the bones shift in their relationship to one another.  These forms of arthritic deformity are more reliably corrected with total knee replacement.  Partial knee replacement cannot correct contractures and very severe forms of arthritis and is sometimes suited for younger individuals with less severe structural forms of arthritis (albeit no less debilitating).

A thorough assessment of your symptoms will be performed by expert knee and robotic surgeon Dr. Obermeyer to ensure your pain is sourced all or in large part from the affected medial (inner) compartment of the knee.  This is based on the nature of pain symptoms being located at the arthritic section of the knee, physical examination to determine how sore the different areas of the knee are, and often MRI.  MRI is utilized to confirm the integrity of the ligaments and to evaluate milder arthritic progression in the lateral or front (patellofemoral) compartments of the knee.  If your symptoms, physical examination, and MRI confirm you are a candidate, and have failed nonsurgical management, partial knee replacement may be a very satisfying solution to correct pain and functional impairments from knee arthritis.