Partial Knee Replacements

Minimally invasive surgery (MIS) is changing the way joint replacement surgery is done.  MIS causes less trauma during surgery and speeds rehabilitation.  Some Total Knee Replacements  can be done with MIS.  All Partial Knee Replacements can be done with MIS. MIS means an incision of 4-6 inches with minimal to no incision of the quadriceps tendon.  A Total Knee Replacement traditional incision is 10-12 inches with a large incision of the quadriceps tendon.  The rehab of Partial Knee Replacement patients is remarkably more rapid than Total Knee Replacement patients.  Typically, a Partial Knee Replacement patient is walking without support at 2 weeks, driving also at about 2 weeks, and requires minimal physical therapy to achieve full function and full knee range of motion.  Most Total Knee Replacement patients require 6-8 weeks of intensive physical therapy and never achieve full function or range of motion.

Although Partial Knee Replacements can provide a knee that functions with normal range of motion, it obviously is not "normal."  Impact activities such as running and racquet sports are discouraged with Partial Knee Replacement.  The life span of a Partial Knee Replacements is commonly placed at about 10 years.  In this time frame the plastic spacer may wear out requiring simply an exchange of this part, or the entire metal component may loosen from the bone requiring a repeat Partial Knee Replacement or conversion to a Total Knee Replacements.  Also, arthritis of the knee may progress on the other side of the knee after Partial Knee Replacement, necessitating conversion to a Total Knee Replacement.  Across the board however, Partial Knee Replacement satisfactory results are about 85% at 10 years.  This means that 16 people out of 20 have a very functional knee with minimal to no pain.  Total Knee Replacements results are somewhat higher in terms of satisfactory results (90%) but again, function results are lower than Partial Knee Replacement.

In summary, Partial Knee Replacements provides excellent pain relief and functional status superior to a Total Knee Replacement.  Partial Knee Replacement is only available to a limited number of patients with bone-on-bone arthritis of the knee who meet specific criteria.  MIS for Partial Knee Replacements is common and speeds recovery allowing patients to return to most regular activities much quicker.

Mark F. Mills, MD

Panorama Orthopedics & Spine Center

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