Intraosseous patellar blood supply after medial parapatellar arthrotomy.

Total knee arthroplasty surgical exposure compromises blood flow to the patella. This reduction in blood flow may result in numerous patellar related complications. This study examined the intraosseous blood supply in normal patellas and those simulating total knee arthroplasty exposure. Fifteen anatomic specimen patellas were used. Ten undisturbed patellas were injected intravascularly with a colored perfusate via at least one geniculate artery, and five were subjected to a median parapatellar approach and a lateral release before injecting. Every patella was removed, embedded in epoxy, and sequentially milled. An orthogonal grid was used to position evident interosseous vessels, and each grid was normalized, allowing comparison among patellas. Perfused intrapatellar arteries formed an anastomotic network of penetrating and radiating arteries. Eighty percent of the interosseous blood supply was found in the central 50% of the undisturbed patellas. The surgically exposed patellas incurred a 75% decrease in total perfusion. There was no significant inflow from the periphery of the patella because the entire blood supply appeared to come from the anterior cortical perforating vessels. Damage to the central 50% of interosseous bone or anterior soft tissue cuff because of a central fixation post or anterior cruciate ligament graft increases the risk for segmental devascularization.