case_images: PMC5347368_01
case_images: Scannogram of the bilateral lower limb showing varus alignment of both the knees with 10  tibiofemoral angle of the left knee.
case_images: sicotj-3-22-fig1_small.jpg
case_images: PMC5347368_01_sicotj-3-22-fig1_small.jpg
case_images: F1
case_images: The tibiofemoral angle was 10  varus (Figure 1), on weight bearing.
case_images: Patient standing with a stick in his hand. From the lateral aspect two swellings can be appreciated. The first swelling was located 1 cm above the lateral joint line and 4 cm lateral from the lateral patellar border and measured 4 cm x 6 cm. The other swelling was located 1 cm below the lateral joint line and 2.5 cm lateral from the lateral patellar tendon measuring 2 cm x 4 cm.
case_images: sicotj-3-22-fig2_small.jpg
case_images: PMC5347368_01_sicotj-3-22-fig2_small.jpg
case_images: F2
case_images: The other swelling was located 1 cm below the lateral joint line and 2.5 cm lateral to the lateral patellar tendon measuring 2 cm x 4 cm (Figure 2).
case_images: (a) Examination of the ligaments in maximal extension revealed 10 mm of opening of the lateral joint line on varus stress test with a soft end. (b) Examination of the ligaments in maximal extension revealed improvement of the alignment to normal with valgus stress.
case_images: sicotj-3-22-fig3_small.jpg
case_images: PMC5347368_01_sicotj-3-22-fig3_small.jpg
case_images: F3
case_images: Examination of the ligaments in maximal extension revealed 10 mm of opening of the lateral joint line on varus stress test with a soft end point and with valgus stress the alignment of the knee improved to normal with a bony end point (Figures 3a and 3b).
case_images: (a) Anteroposterior (AP) X-ray of the bilateral knee showing decrease in the joint space (left > right) with lateral tibial subluxation of the left knee. (b) Lateral radiograph of both the knee showing multiple osteophytes and degenerative changes in the patellofemoral joint.
case_images: sicotj-3-22-fig4_small.jpg
case_images: PMC5347368_01_sicotj-3-22-fig4_small.jpg
case_images: F4
case_images: There was lateral subluxation of the tibia with respect to the femur (Figures 4a and 4b).
case_images: A standing anteroposterior radiograph of the left knee shows a well-fixed, well-aligned, total knee prosthesis with cemented tibial stem and a malleolar screw in the medial aspect.
case_images: sicotj-3-22-fig5_small.jpg
case_images: PMC5347368_01_sicotj-3-22-fig5_small.jpg
case_images: F5
case_images: A primary TKA (NEXGEN; Zimmer Biomet, Warsaw, Indiana) was performed (Figure 5).
case_images: Decompression of the common peroneal nerve at the level of deep peroneal muscles after decompression of the cyst.
case_images: sicotj-3-22-fig6_small.jpg
case_images: PMC5347368_01_sicotj-3-22-fig6_small.jpg
case_images: F6
case_images: The cyst was then removed in toto and was sent for histopathology (Figure 6).
case_images: Removal of the cyst in toto. Examination of the inner wall of the cyst reveals smooth and glistening surface.
case_images: sicotj-3-22-fig7_small.jpg
case_images: PMC5347368_01_sicotj-3-22-fig7_small.jpg
case_images: F7
case_images: The nerve was freed of all the adhesions around it (Figure 7).