Popliteal Pseudoaneurysm after Medial Open Wedge High Tibial Osteotomy: Osteotomy

Objectives: Medial open wedge high tibial osteotomy is an effective procedure to treat isolated medial unicompartmental knee osteoarthritis and varus knee alignment. Respecting individual variance of surrounding anatomical structures is one of the keys to achieve satisfactory results after this procedure. This case report highlights the importance of understanding and respecting surrounding anatomical structures which are at a potential risk during medial open wedge high tibial osteotomy describing a rare case of postoperative popliteal pseudoaneurysm. Methods: A 54-year-old male patient (176 cm, 84 kg, BMI: 27,1 kg/m 2 ) presented in our clinic with a chronic medial knee pain in his left knee. His left knee was operated twice in an external clinic arthroscopically with medial meniscus resection. The clinical examination showed a left knee with varus deformity and pain in the medial compartment. Range of motion (ROM) was 5° to 130° degrees. Anteroposterior long leg standing, lateral and valgus/varus stress radiographs were obtained. Magnetic resonance imaging (MRI) was performed. In the long leg standing radiograph, 7,6° varus angle, 82,2° medial proximal tibia angle (MPTA) and 88,4° lateral distal femur angle (LDFA) were measured. Furthermore, MRI showed a tear in the posterior horn of the medial meniscus and a chondromalacia grade II-III in medial femoral condyle and medial tibia plateau. Hence, a decision for a knee arthroscopy and an open wedge high tibial osteotomy was made. In knee arthroscopy, medial meniscus tear was resected. Then, open wedge proximal tibial osteotomy was performed. Results: Six days after the procedure, the patient presented in our clinic with swelling, effusion and pain in his left lower limb. C-reactive protein (CRP) value was 17 mg/dL. In the doppler sonography, A. tibialis posterior and A. dorsalis pedis were detectable. Due to a suspected acute postoperative infection, DAIR-procedure was performed. Since symptoms persisted postoperatively, vascular sonography was carried out and pseudoaneurysm of A. poplitea was suspected. Pseudoaneurysm of popliteal artery was confirmed after a computed tomography angiography (CTA) with contrast material. After the confirmed diagnosis and clinical symptomatic of compartment syndrome, stent graft implantation of popliteal artery, truncal-A. tibialis anterior vein bypass and fasciotomy were carried out. Postoperative recovery of the patient was uneventful. Conclusion: In this case, there was an increased risk of vascular complication due to the atypical high origin of the anterior tibial artery branching from the popliteal artery. The vessel was located directly in the dorsal region of the proximal tibia and therefore posed a particular risk despite using a retractor, possibly due to the vibration of the oscillating saw on the retractor. Respecting the location and course of popliteal artery in relation to tibia in the preoperative MRI examination could help to avoid this rare complication.