Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

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Knee extension mechanism injuries

The knee extension mechanism includes the quadriceps muscle-tendon, the patellar bone, the patellar
tendon, and its insertion into the tibia. Injuries can occur in all these structures.

Quadriceps tendon injuries
The distal quadriceps tendon attaches to the patella and its adjacent soft tissue structures (the retinaculum).
It is important for the extensor mechanism. This tendon is extremely strong and only ruptures in rare situations, mostly in older athletes, such as golf players falling on slippery grass slopes, or weightlifters lifting excessive loads. It can also be an overuse injury in weightlifters doing repeated knee bending work.

Rupture
The typical history of a rupture of the quadriceps tendon includes a sudden pop when increased stress is applied to the extensor mechanism. When there is a complete rupture, the disability will be immediate and the athlete cannot support the body weight on the injured side. There is often a gross displacement of the patella
distally. These injuries are often complete, and therefore pain is not prominent.

Symptoms and diagnosis
– Tenderness and swelling occur where the muscle merges into the tendon above the patella or where the tendon inserts into the patella.
– A gap can be felt where the rupture has occurred.
– operate in cases of major ruptures in athletes or active persons when the tendon is avulsed from the patella;
– operate on old injuries of this type.
Early mobilization is important, but return to sports is not possible before 4–6 months.

Overuse injuries
Chronic overuse injuries to the distal quadriceps tendon area are not very common; they are most likely to occur in weightlifters. Problems can also be seen in basketball or team handball players who jump frequently. They complain of pain when they push off for the jump, or on rising from squatting or kneeling positions . There is localized tenderness over the proximal area of the patella where the quadriceps tendon inserts. Sometimes there is discomfort when contracting the quadriceps, especially against resistance or when the extended knee is lifted against resistance. The treatment of these overuse injuries are according to the principles.The prognosis is often reasonably good and gradual return to sports may follow a rehabilitation period including stretching and strengthening exercises.

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