A 15.5-year-old female teenager presented to the emergency room with acute right knee pain after she jumped from a scooter to brake going downhill at high speed. She reported feeling a “popping” in the knee and collapsed. Her knee became swollen, and she was unable to bear weight. The patient had a moderate knee effusion but was nevertheless able to extend the knee against gravity. No laxity during valgus stress testing was found, and the Lachmann test was negative. The foot was well perfused, and pulses were present. As the clinical vascular examination was entirely normal, we did not perform an arteriogram. Radiographs and MRI revealed a partial distal patellar tendon avulsion injury, a complete tear of the ACL, and associated bone bruises on the lateral femoral condyle, and also on the posterolateral tibial plateau (Figures –). The posterior cruciate ligament and the MCL were undamaged (Figures and ). The patient was taken to the operating room to repair the distal patellar tendon avulsion 14 days after her injury. The clinical exam under general anesthesia demonstrated a positive (grade 1) Lachman test, but no laxity during the valgus stress test. Considering the importance of the patellar tendon lesion, we avoided to perform a pivot shift test during general anesthesia. The surgical treatment focused therefore on stabilizing the patellar tendon/extensor mechanism. Surgical exploration demonstrated a partial distal patellar tendon bone avulsion injury; repair of the lesion was realized by osteosuture using suture anchors. At a 9-month follow-up (), the patient recovered a functional range of motion, with a mild 20° flexion restriction. She did not feel any anterolateral rotatory instability, and she could participate in light sports activities. Radiographs demonstrated a normal patellar height with a Caton-Deschamps index measured at 0.7; however, we noted an anterior static tibial translation of 9 mm.
A 36-year-old female jumped from a four-foot high deck landing flatly on both feet. She felt a pop in the right knee and experienced extreme pain and inability to bear weight on the limb. She sought emergency medical attention where radiographs revealed a joint effusion, and a wavy appearance to the tendon []. There was no patellar elevation, fracture or malalignment. Clinically the patient was believed to have an ACL tear. The patient was treated with a knee brace and instructed to follow-up with an orthopedic surgeon and obtain an MR examination of the knee.\nThe MR examination of the right knee was obtained 10 days later and demonstrated abnormal increased T2 signal in the midsubstance of the ACL and abnormal orientation of the ligament consistent with a complete ACL disruption []. Bone contusions in the posterior medial and lateral tibial plateaus as well as the lateral femoral condyle were present. The patellar tendon was abnormal in morphology and signal. The tendon had an abnormal wavy contour at the junction of the middle and distal thirds of the tendon and had abnormally increased signal on T2-weighted images. The axial images demonstrated near complete disruption of the patellar tendon with only a few intact fibers.\nOrthopedic follow-up visit was delayed for nearly 2 months. At the time of presentation she had persistent pain, instability, and very limited range of motion. She had a positive Lachman test of the right knee. Although the patient had tenderness over the patellar tendon, there was no palpable tendon defect and she was able to hold a straight leg raise with minimal extensor lag. The patient was diagnosed with a complete ACL tear and high-grade partial patellar tendon tear. Physical therapy was instituted to help prevent postoperative fibrosis. A delayed ACL reconstruction was schedule 8 weeks later.\nA diagnostic arthrogram at the time of surgery confirmed a complete midsubstance ACL tear. The ACL was reconstructed with an ipsilateral hamstring autograft. The patellar tendon was not directly inspected at the time of surgery and was treated clinically as a partial patellar tendon tear. The patient's postoperative course was complicated by complex regional pain syndrome requiring multiple nerve block injections. A year following the initial injury, the patient had continued stiffness, difficulty with walking and had developed quadriceps muscle atrophy.