A 40-year-old male patient presented to the emergency ward with pain and swelling on the lateral aspect of the right knee due to lateral trauma to the fibula during external rotation of the leg with his foot on the ground while playing football. Physical examination revealed minimal effusion in the knee joint, a prominent fibular head, and pain in the proximal tibiofibular joint. The patient had difficulty bearing weight on the affected extremity. Knee range of motion was measured as 0 -135 . The dorsalis pedis and posterior tibial artery pulses were evaluated as palpable. No peroneal nerve damage was detected. Ankle dorsiflexion and plantar flexion were painless, and full range of motion was confirmed. A written informed consent was obtained from the patient.
Anterolateral dislocation of the fibular head from the tibiofibular joint was detected on the anteroposterior and lateral radiographs (Figure 1). Computed tomography confirmed the diagnosis. No osseous pathology was detected.
After the physical examination, radiography, and CT, axial traction and internal rotation were applied under sedation, and the fibular head was manipulated to provide closed reduction. Deformity disappeared after reduction (Figure 2). The fibular head was more mobile compared to the contralateral knee, which was considered as instability. After reduction, the distal neurovascular examination was normal, and there was no pain; then, long-leg plaster splint was applied. The magnetic resonance imaging (MRI) scans showed that the proximal tibiofibular joint was reduced. Besides, the presence of soft tissue edema around the knee joint, hematoma, joint capsule, and tibiofibular ligament tears were detected. A bucket-handle lateral meniscal tear was also detected as an intraarticular pathology (Figure 3). Surgery was planned, and the patient was operated due to instability and the bucket-handle meniscal tear.
The arthroscopy of the knee revealed that the medial meniscus was intact. However, a big bucket- handle tear was detected in the lateral meniscus. The popliteus tendon was also intact. The lateral meniscus was repaired all-inside with five vertical mattress sutures, and then the meniscus was found to be reduced. Then, a curved incision was performed for the proximal fibula. The lateral collateral ligament was intact but slightly elongated. The fibular head, which was unstable in the proximal tibiofibular joint, was reduced, and fixation was performed under fluoroscopy using one cannulated screw (Figure 4). Subsequently, a long-leg plaster splint was applied. We did not detect peroneal nerve damage after surgery.
The sutures and the plaster splint were removed in the postoperative second week. The patient had full range of motion of the knee, with mild pain at the surgery site.
At the end of the eighth postoperative week, the patient had no pain in the tibiofibular joint. The knee flexion and extension movements were found to be between 0 -135  and equal to the contralateral knee. The patient was allowed full weight-bearing.