What's the Diagnosis? By Dr. Abby Renko
Wed, 06/02/2021 - 1:45pm
A 45 y/o M with PMhx of HTN and ESRD on dialysis presents to the ED w/ knee pain after slipping at work. On exam, he is unable to extend his leg. An X-ray is done and shown below. What's the diagnosis? (scroll down for answer)
Answer: Quadriceps tendon rupture
- At first glance, lateral XR does not show obvious deformity....however: you may notice calcifications just superior to the patella (representing retracted tendon)
- Quadriceps tendon ruptures tend to occur in individuals > 40, while patellar tendon ruptures occur more frequently in individuals < 40
- Overall quadricep tendon ruptures are more common (risk factors- rheumatologic disease, renal failure, DM, chronic steroid use)
- High riding patella ("patella alta") on lateral films is more frequently seen in patellar tendon ruptures
- Low riding patella ("patella baja") may be seen on lateral film with complete quadricep tendon tear (intact patellar tendon displaces patella inferiorly)
- Xrays may be normal!
- In both injuries, classic exam finding is inability to extend the knee
- You can often palpate a defect just above the patella in quadriceps tendon ruptures
- Orthopedic consultation is always warranted for these cases
- Remember-- always consider knee dislocation in any patient that has a severely injured knee that is unstable!
- Dislocations typically occur traumatically, but can also occur spontaneously, especially in obese individuals
- They are a surgical emergency due to possible injury of the popliteal artery (ischemia risk) and peroneal nerve
- Timely reduction is essential, with documentation of a neurovascular exam before and after reduction
- Extemity should then be splinted with knee at 20 degrees of flexion to prevent re-dislocation
Bengtzen RR, Glaspy JN, Steele MT. Knee Injuries. In: Tintinalli JE, Stapczynski JS, et al., eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 8th ed. New York, NY: McGraw-Hill; 2016: (Ch) 274.