A 13-year-old male athlete presented to the emergency department with an injured left tibia. The patient reported a left knee forced hyperflexion during a football match, which caused the injury. The described mechanism of injury was violent contraction of the quadriceps muscle against a fixed tibia.
The left knee was held in 100  of flexion with complete inability to extend the knee or bear weight. On examination, there was obvious swelling over the proximal tibia and on palpation there was tenderness on the anterolateral part of the proximal end of the tibia. No neurovascular impairment was identified. The patient was able to actively move his ankle, as well as his toes, and both posterior tibialis artery and dorsalis pedis artery were palpable.
From the plain radiographs, a displaced flexion type Salter-Harris type II fracture of the proximal tibia epiphysis was identified (Figure 1).
Few hours after admission, the patient was led to the theatre and, under general anesthesia, a closed reduction of the fracture was performed by extending the knee and putting strong pressure over the tibial tubercle. Reduction was confirmed using image intensifier (Figure 2) and stability of the fracture was verified, as there was no displacement at 80  of knee flexion. After reduction, the dorsalis pedis artery and the posterior tibial artery were palpable. Since there was no displacement with that degree of flexion, percutaneous pinning of the fracture was not performed and only a circumferential cast with the knee in full extension was applied.
Patient was hospitalized in the Orthopaedic Department under close observation of limb neurovascular status. On the same night after reduction, the patient developed severe pain, which subsided after splitting the cast. The next few days, the patient developed severe swelling over the anterior tibia compartment, but there were no clinical signs of compartment syndrome. Posterior tibialis remained easily palpable, whereas the dorsalis pedis became weak but easily identifiable with the Doppler ultrasound scan. Fracture remained in a satisfactory position one week after reduction (Figure 3) and a full femur-tibia-ankle cast in 5  of knee flexion was applied. 2 weeks after injury, radiographs of the fracture were still satisfactory. 6 weeks after injury, fracture position was satisfactory with radiographic evidence of healing (Figure 4) and the cast was removed, encouraging active range of motion of the knee. At the same time, the anterior tibialis artery was easily palpable and a triplex ultrasound scan of the lower limb was normal. 8 weeks after injury, the patient achieved full range of motion, and full weight bearing was allowed. MRI scan was performed at this point; as occasionally, these fractures are associated with ligamentous injuries around the knee. MRI scan was normal regarding the cruciate and the collateral ligaments as well as the menisci. Patient's follow-up will continue with serial radiographs at 4 months, 8 months, and 12 months in order to detect early signs of growth arrest or angular deformity and genu recurvatum.