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Avulsion of the Vastus Lateralis Tendon From Doing Gym Squats

From a knee specialist in Singapore, A rupture can in principle occur to all muscles in the thigh, however, ruptures most often happen in the anterior muscle (M quadriceps femoris) which has the function of stretching the knee and flexing the hip. The anterior thigh muscle consists of four muscles (M vastus lateralis, M vastus medialis, M rectus femoris and the deep lying M vastus intermedius).

vastus picture

A 24-year-old man presented with painful swelling over the front and outer aspect of his right knee after an injury when doing a squat in the gym with weights. He distinctly heard a loud “Pop” when the injury occurred.

SquatSquats in the gym


He was able to walk but with pain and a limp.

He presented to me a day after his injury.

Examination showed that he was able to fully extend his right knee and he was able to perform a straight leg raise. This implied that the extensor mechanism of his right knee was still largely intact. A complete rupture of his right knee quadriceps tendon was ruled out.

He had focal tenderness over the anterolateral region of his right patella upper pole. There was a suggestion of a divet at that area during palpation.

I performed a bed-side ultrasound scan and it suggested an area of tendon discontinuity over the vastus lateralis insertion into the upper pole of the patella.

An MRI scan of his right knee was ordered.

Ruptured vastus lateralis tendon of the right knee.

Ruptured vastus lateralis tendon of the right knee.

002 - MRI showing torn vastus lateralis tendon with bleeding. By Dr HC Chang

The ruptured vastus lateralis tendon was repaired surgically.

003 - The torn vastus lateralis tendon is identified. By Dr HC Chang004 - The torn vastus lateralis tendon is repaired to the patella bone via suture anchors. By Dr HC Chang

005 - The vastus lateralis after the surgical repair. By Dr HC Changvastus lateralis picture

His right knee was protected with a hinged knee brace for the following 6 weeks. He was allowed partial weight bearing ambulation with crutches for 3 weeks followed by full weight bearing ambulation thereafter.

The hinged brace allowed 0 – 30 degrees of knee flexion for the initial 2 weeks and it was gradually increased to full flexion over the following first 6 weeks.

006 - The surgical wound has healed after vastus lateralis tendon repair. By Dr HC Chang

This is his healed surgical scar. The contour of his muscle is restored.

007 - The patient is able to do single leg stand after successful repair. By Dr HC Chang

He was referred to the physiotherapist to strengthen his right thigh muscles. He was able to do single leg stand and lunges when the strength of his right thigh muscles improved.

Isolated vastus lateralis tendon ruptures are rare but a high degree of suspicion and low tolerance to investigate with MRI or ultraosund scans will help prevent missed diagnoses of such injuries.

Find out more about other related knee conditions and treatments from our knee specialist in Singapore.

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