Patellar Tendon Thickness and Failure After Anterior Cruciate Ligament Reconstructions with Bone-Patella Tendon-Bone Autograft

OBJECTIVES: The purpose of this study was to determine if patellar tendon (PT) thickness measured on pre-operative magnetic resonance imaging (MRI) is a risk factor for failure after anterior cruciate ligament reconstruction (ACLR) using bone-patella tendon-bone (BTB) autograft. METHODS: 18 patients [age (mean 96 Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:”Table Normal”; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow: yes; mso-style-priority:99; mso-style-parent:”“; mso-padding-alt:0in 5.4 pt 0in 5.4 pt; mso-para-margin:0in; mso-para-margin-bottom:.0001 pt; mso-pagination: widow-orphan; font-size:11.0 pt; mso-bidi-font-size:12.0 pt; font-family: Helvetica;} ± standard deviation) 21.5 ± 4.99years] that underwent an ACLR with BTB autograft and returned for revision ACLR between July 2005-January 2017 at our institution were included in the study. Failures were age-, sex-, height-, and weight-matched to 36 control (age 21.5 ± 4.99years) BTB-ACLR patients that have not required revision at a minimum of 2-years follow-up. Demographic data and mechanism of injury were recorded from patients’ medical records. PT thickness was measured at 3 points (5 mm lateral to the center, center, and 5 mm medial to the center) each at the level of the inferior pole of the patella (IPP), midpoint (MP), and insertion to tibial tubercle (ITT) on pre-operative axial-cut MRI. RESULTS: All ACLR failures occurred after a non-contact pivot-shift type injury. Mean time between primary ACLR and revision was 2.4 ± 2.4 years and mean follow-up time was 3.1 ± 0.9 years in the control group. Patients with a failed ACLR had significantly thicker PTs at the IPP (lateral: 4.66 ± 1.47 vs 3.96 ± 0.66 mm; central: 5.39 ± 1.49 vs 4.51 ± 1.04 mm; medial: 5.51 ± 1.52 vs 4.59 ± 1.05 mm) and MP (lateral: 4.50 ± 0.83 vs 4.12 ± 0.54 mm; central: 4.83 ± 0.80 vs 4.43 ± 0.59 mm; medial: 4.57 ± 0.88 vs 4.13 ± 0.59 mm). There were no significant differences in PT thickness at the ITT. PT width tended to be larger in the failure cohort but this was not statistically significant (IPP: 32.2 ± 4.6 vs 29.8 ± 4.3 mm; MP: 31.3 ± 4.9 vs 29.5 ± 3.8 mm; ITT: 27.7 ± 3.7 vs 26.2 ± 2.9 mm). CONCLUSION: Contrary to conventional wisdom, we found that BTB autograft ACLR failures had significantly thicker patellar tendons at the inferior pole of the patella and midpoint. Further studies are need to investigate possible causes for this inverse correlation, such as poor histological tendon quality or mechanical impingement due to increased tendon size.