Lessons Learned from a Case with Valgus Deformity of the Knee Following Partial Removal of Lateral Discoid Meniscus

Few studies have focused on the possible change in the axial alignment of the lower limb after lateral meniscectomy. Here, we present a patient with valgus deformity of the knee following the partial removal of lateral discoid meniscus. With the distal femur osteotomy and fixation, this complication was treated successfully. This case suggested that we should pay more attention to the axial alignment of the lower limb in patients with torn discoid lateral meniscus before meniscectomy, as a severe valgus inclination may develop in some of these patients. A 43‑year‑old woman was referred to our hospital because she complained that she had limped for snapping during daily activities for the past 2 months, resulting in lateral pain of her right knee. She had experienced minor trauma. She was noted clinically to have audible and palpable snapping during the movement of the right knee. The valgus deformity was noted on both the knees when she was in a standard standing position. However, we did not pay more attention on this. Tenderness of lateral side and positive McMurray sign of the right knee were checked out. To rule out intra‑articular pathology, magnetic resonance imaging (MRI) of the right knee was performed. Coronal and sagittal MRI of the right knee showed Grade III discoid meniscus tear. The patient underwent right knee arthroscopy with spinal anesthesia. A small pneumatic tourniquet was applied. The meniscus was probed to identify the posterior attachment. The complete type discoid lateral meniscus was noted. Probing of the meniscal synovial edge showed complete longitudinal tear from anterior to posterior. Rough wear and scarring were presented at tear edges. Grade II cartilage degeneration was also noted in the lateral compartment. Hence, we decided to do a partial meniscectomy. However, her knee was becoming more symptomatic with increasing pain and swelling only 1 month after the surgery. The standing X‑ray showed that the right knee was in fact much more valgus than the left. We used the tibiofemoral angle to evaluate the axial alignment of the lower limb. However, we did not give the order of a full‑length weight‑bearing X‑rays before arthroscopy surgery. Hence, we judge the right knee according to the deformity of the left knee [Figure 1]. The anti‑inflammatory drugs, quadriceps exercise, and knee brace chuck were consequently given to this patient for more than 6 months, but there was no significant relief of symptoms. There had been no indication …