Effect of Surgical Technique on Resection Symmetry of the Patella in Total Knee Arthroplasty

Resection of the patella to prepare it for placement of a patellar prosthesis is a procedure that is performed routinely in the vast majority of total knee arthroplasties (TKA) in the United States and at the Mayo Clinic. This procedure is performed by a number of different techniques that have been proved to be safe and effective. Despite this, patellar instability, tilt, obliquity, and maltracking are all possible complications of improperly resected patellae during TKA. The goals of resection are to create a patella that is symmetrical, absent of obliquity (slanting), and thick enough to receive a patellar prosthesis. Although outcomes are generally good for most described methods, to date, little had been published regarding direct comparison of these methods. Patients undergoing TKA with planned patellar resection were randomized to have their patella resected by one of three methods during primary TKA: 1) use of a cutting guide, 2) haptic feedback, or 3) free-hand resection guided by four quadrant measurements. There were three experienced fellowship-trained arthroplasty surgeons (hip and knee) performing the procedures who were all familiar and experienced with each of the three techniques being investigated. Each surgeon, within a group of 30 of their patients, performed a total 10 resections using each of the three methods listed above (30 resections per surgeon for a total of 90 resections). Before and after resection measurements of knee-cap thickness were taken and used to determine patellar symmetry. The resulting symmetry of each of the three techniques was then be compared between and within each of the three techniques and surgeons. Each procedure was also be timed from first measurement by the staff surgeon to the final measurement by that surgeon.