PATELLAR TENDON LENGTH CHANGE AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION USING THE MIDTHIRD PATELLAR TENDON

The purpose of this study was to determine if use of the midthird pate llar tendon autograft contributes to or causes patellar tendon shorten ing or patella baja in anterior cruciate ligament reconstruction. Thir ty-six patients undergoing arthroscopically assisted midthird patellar tendon autograft anterior cruciate ligament reconstruction were studi ed prospectively. Intraoperative patellar tendon length changes were m easured. Half of the patients had the tendon defect closed and half ha d it left open (closing peritenon only). Radiographic tendon length ch anges and patella baja were assessed using Insall-Salvati and Blackbur ne-Peel ratios measured on 450 lateral knee radiographs using an adjus table polypropylene jig. Bilateral films were obtained preoperatively and at 2 weeks, 3 months, and 6 months postoperatively. No patients de monstrated evidence of patellar tendon shortening greater than the 5.5 % measurement error. Tendon defect closure resulted in negligible tend on shortening intraoperatively, averaging 2.28% (1.11 mm). Of the 18 p atients whose defects were closed, 5 showed no shortening. The remaini ng 13 patients had measurable tendon shortening less than 4% (2 mm). N o patients developed patella baja.