MRI detection of partial rupture of the patellar tendon in association with multiple ligament injuries of the knee: its surgical importance

Multiple ligament injury of the knee frequently results from high-energy trauma, and may be associated with knee dislocation. Commonly, the anterior cruciate ligament (ACL) is torn, in association with one of the collateral ligaments and the associated postero-medial or lateral-capsular structures. Posterior cruciate ligament (PCL) damage may occur and complete rupture of the patellar tendon is a rare association. The detection of the full spectrum of injuries using MRI has an important bearing on the initial surgical management. We report two cases of knee injury, including ACL disruption, both of which had a partial patellar tendon rupture, which could not be diagnosed clinically, and in one case the patellar tendon injury was not initially recognised on MRI. We wish to emphasise the importance of careful scrutiny and reporting of this latter finding for pre-operative planning since partial patellar tendon rupture prevents the use of patellar tendon graft for early ACL reconstruction.