Diagnosis

Early diagnosis of the condition is important as delay in treatment (>2 weeks) is associated with less satisfactory clinical outcomes (1).

A patient usually presents with a history of tripping or giving away of the knees (1)

• it is associated with a ‘Pop’ sound at time of injury together with acute onset of pain
• the amount of force required for rupture may vary from strenuous weight lifting to descending stairs
• in cases of complete rupture, inability to extend the knee of the affected extremity can be observed (1)

Physical examination finding include:

• swelling of the knee
• tenderness at the inferior pole of the patella or along the patella tendon
• palpable defect in the tendon (may not be felt in cases with swelling or increased soft-tissue mass)
• asymmetric patella alta (proximal migration of the patella) - characteristic picture for patellar tendon rupture, more visible with knee flexion
• active knee extension may be completely absent

Additional diagnostic studies include:

• plain radiographs -
  • “tooth sign” caused by degenerative changes close to patellar tendon origin
  • patella alta may also be visible
• ultrasound and magnetic resonance imaging - maybe useful in patients with unclear or delayed diagnosis (1)

Reference

1. Brinkman JC, Reeson E, Chhabra A. Acute Patellar Tendon Ruptures: An Update on Management. J Am Acad Orthop Surg Glob Res Rev. 2024 Apr 01;8(4)