Preoperative Magnetic Resonance Assessment of Patellar Tendon Dimensions for Graft Selection in Anterior Cruciate Ligament Reconstruction

Background: A bone patellar tendon bone autograft is one of the standard graft choices for anterior cruciate ligament reconstruction. However, its use can be limited when the patellar tendon is too narrow or too long. Hypothesis: A preoperative assessment of patellar tendon dimensions using magnetic resonance imaging would be accurate and reliable. Patients undergoing anterior cruciate ligament reconstruction would have wide ranges of patellar tendon dimensions, and a significant proportion of patients would have a too narrow and/or too long patellar tendon as the graft choice. There would be a demographic predictor to identify the patients with inappropriate patellar tendon dimensions. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: The accuracy and reliability of magnetic resonance assessments of patellar tendon dimensions were assessed by comparing the intraoperative measurements using a ruler in 55 knees and 10 knees, respectively. Data from the magnetic resonance assessments in 147 knees undergoing anterior cruciate ligament reconstruction were used for the normative documentation of the patellar tendon dimensions (width, thickness, and length) and identification of demographic predictors for the dimensions. Results: Preoperative magnetic resonance assessments of the patellar tendon dimensions were accurate and reliable. Korean patients undergoing anterior cruciate ligament reconstruction had wide variations in patellar dimensions, and a significant portion of the patients had an inappropriate patellar tendon (longer than 5 cm in 4.1% and narrower than 27 mm at middle portion in 15.6%) for the graft source. Patient height was the predictor used for patellar tendon width. The mathematical equation used to estimate the width based on patient height was: tendon width at middle portion (mm) = 0.202 x patient height (cm) - 5.07. Conclusion: Preoperative magnetic resonance assessment of patellar tendon dimensions can be a valuable tool with satisfactory accuracy and reliability when the autologous patellar tendon is considered as the graft source for anterior cruciate ligament reconstruction.