PMC5347368_01
Scannogram of the bilateral lower limb showing varus alignment of both the knees with 10  tibiofemoral angle of the left knee.
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F1
The tibiofemoral angle was 10  varus (Figure 1), on weight bearing.
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.
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F2
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).
(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.
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F3
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).
(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.
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F4
There was lateral subluxation of the tibia with respect to the femur (Figures 4a and 4b).
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.
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F5
A primary TKA (NEXGEN; Zimmer Biomet, Warsaw, Indiana) was performed (Figure 5).
Decompression of the common peroneal nerve at the level of deep peroneal muscles after decompression of the cyst.
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F6
The cyst was then removed in toto and was sent for histopathology (Figure 6).
Removal of the cyst in toto. Examination of the inner wall of the cyst reveals smooth and glistening surface.
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F7
The nerve was freed of all the adhesions around it (Figure 7).