Extensor mechanism disruptions of the knee are relatively uncommon but serious injuries. They are clinically diagnosed by the triad of swelling around the knee, palpable defect and inability to perform straight leg raise. The most common form of disruption is patellar fracture followed by rupture of the patellar tendon and the quadriceps tendon.3
A simultaneous rupture of a patellar tendon and the opposite quadriceps tendon is extremely rare in a previously fit individual as different mechanical, systemic and local factors are involved. The quadriceps rupture is more common in older subjects (>50 years) with associated systemic factors such as obesity, gout and local degenerative changes.4
Patellar tendon rupture is seen in young healthy people, with repeated micro trauma being the main causative factor.
Bilateral traumatic ruptures of extensor tendons are being increasingly reported and it is important to consider a bilateral pathology in cases presenting with traumatic rupture on one side. The commonest cause of bilateral simultaneous rupture appears to be sudden violent contraction of the quadriceps mechanism with the knees slightly flexed and feet firmly planted on the ground.1
It is important to feel for tenderness and defects in both the suprapatellar and infrapatellar regions, as both ruptures can occur simultaneously in spite of the two having different pathogeneses.
This is the fourth reported case in the English literature of a simultaneous rupture of the two tendons in the same individual in the absence of any inflammatory disease.5–7
This patient had urgent surgery and early rehabilitation, which is the key to good functional outcome. This case, therefore, highlights the importance of developing awareness among treating physicians and physiotherapists of the possibility of this unusual combination even in healthy individuals.
- A thorough and systematic examination is essential.
- Both knees should be examined even though the injury appears to be on one side only.
- Plain radiographs should be carefully studied for extensor mechanism injury.