Periosteal Sleeve Avulsion Fracture of the Quadriceps Tendon

A 15-year-old girl presented with a primary lateral patella dislocationof her left knee after she slippedoff a starting block and struck the medial aspect of her knee. No reduction was required, the patellar dislocation spontaneously reducedwith gentle knee extension prior to evaluation. Patellofemoral anatomy measurements demonstrated an Insall–Salvati ratio of 1.5, a Caton–Deschamps index of 1.6, and a tibial tubercle– trochlear groove distance of 16 mm. Initial radiographs were negative for fracture or loose bodies. A magnetic resonance imaging (MRI) demonstrated medial patellofemoral ligament rupture from its patellar origin, but neither chondral injuries nordamage to the superior patellar pole orquadriceps tendon. Conservative management consisted of weight bearing as tolerated, utilization of a patellar stabilization brace, and a graduated physical therapy (PT) program. Patient progressed satisfactorily with conservative management. The patient’s range of motion (ROM) profile had normalized, gait was nonantalgic, strengthening had returned, and a return to sports-specific activities was initiated. Twenty-seven days after index injury, she landed awkwardly on a trampoline with her left knee in flexion and presented with severe pain of the knee. The patient returned to jumping on a trampoline without clearance, no bracing was utilized for this activity. Examination revealed effusion, tendernesswithpalpation along the lateral and medial border and profound apprehensionwith lateral translation of the patella, passive ROM from 0 to 45 to 100 degrees of flexion, and inability to perform a straight leg raise. Standard radiographs (►Figs. 1a, b, and 2) demonstrated an osteochondral fragment along the medial patellar border on sunrise view, and superior to the patella on lateral viewwithout anterior patellar tilt. This was interpreted as an osteochondral fragment from a second patellar dislocation. Repeat MRI demonstrated complete disruption of the quadriceps tendon insertion at the superior patellar pole with an associated avulsion of the periosteal sleeve, without evidence of fracture or other intra-articular pathology. Surgical repair was offered.