A 20 year old male presents to the emergency department via EMS for left knee pain. He was playing basketball when he jumped and felt a “pop” in his left knee and has been unable to walk on his left leg since. He denies falling. On exam, the left lower extremity is distally neurovascularly intact with normal strength, sensation, and a palpable pulse. There is slight bogginess and swelling with tenderness to palpation to the inferior knee. He is unable to extend at the knee. A point of care ultrasound of the bilateral knees is performed and shown below. What’s the diagnosis?
Answer: Left patellar tendon rupture
- Commonly occurs from forced quadriceps contraction or falling on a flexed knee.
- Associated with a high-riding patella also known as patella alta which can be appreciated on physical exam and lateral radiographs of the knee.
- There is emerging data demonstrating point of care ultrasound as a quick and effective method to diagnose tendon injuries in the emergency department compared to physical exam, x-ray imaging, and MRI.
- Treatment:
- Incomplete tears with intact extensor mechanism can be immobilized and followed up outpatient with orthopedics.
- Complete tears or loss of extensor mechanism should prompt orthopedic consultation in the ED as expedited surgical repair is often indicated.
References:
Bengtzen R. Knee Injuries. In: Tintinalli JE, Ma O, Yealy DM, Meckler GD, Stapczynski J, Cline DM, Thomas SH. eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 9e. McGraw-Hill Education; 2020.
Berg, K., Peck, J., Boulger, C., & Bahner, D. P. (2013). Patellar tendon rupture: an ultrasound case report. BMJ case reports, 2013, bcr2012008189. https://doi.org/10.1136/bcr-2012-008189
Wu TS, Roque PJ, Green J, et al. Bedside ultrasound evaluation of tendon injuries. Am J Emerg Med. 2012;30(8):1617-1621. doi:10.1016/j.ajem.2011.11.004
