Symptomatic transient patellar ischemia following total knee replacement as detected by scintigraphy. A prospective, randomized, double-blind study comparing the mid-vastus to the medial para-patellar approach.

The most advantageous surgical approach for total knee arthroplasty is not defined. The mid-vastus approach has been suggested to improve patient rehabilitation and prevent patellar devascularization. The following study assessed the changes in patellar vascularity as determined by bone scanning following total knee arthroplasty without lateral release or patellar replacement. A total of 30 patients were randomly allocated to either undergo a medial para-patellar approach or a midvastus approach. All patients underwent a pre-operative bone scan and another scan was performed 5-7 days later. The bone scans were compared to assess the intensity of patellar uptake. In 4/30 (13.5%) of subjects, evenly distributed among the two study groups, patellar ischemia was demonstrated by decreased radioisotope uptake. These subjects underwent a third bone scan 1 month later. The latter scan demonstrated similar uptake to the pre-operative scan. These patients continue to suffer from anterior knee pain and show a positive patellar grinding test, which were not found in other patients. The current study appears to indicate that transient patellar ischemia is relatively common following total knee arthroplasty, even when no lateral release is performed. The surgical approach does not seem to affect the frequency of patellar ischemia. This phenomenon might be related to clinical symptoms of anterior knee pain.