A 57 year old male with no significant PMH presents to the ED after tripping and falling in the bathroom just prior to arrival. He has severe right knee pain and deformity. He states that he had stumbled while walking in the bathroom and landed hard on his right foot with severe knee pain before falling. There was no direct trauma to the knee. He denies paresthesias. He has been unable to ambulate since the event due to pain.
On exam of his right knee, the patella is displaced superiorly with tenderness and palpable defect inferiorly. There is no valgus or varus instability. The extensor mechanism is not intact. Sensation is intact to light touch. Dorsiflexion and plantarflexion are full strength. There is no warmth, erythema, crepitus, or ecchymosis. Pulses are intact distally. The remainder of his exam is unremarkable including the right hip and ankle.
Differentials:
Patellar fracture
Patellar tendon rupture
Quadriceps tendon rupture
Tibial tuberosity fracture
Knee dislocation
Two view x-rays of the knee (and ankle and hip) were obtained. The x-rays show no patellar fracture and no tibial tubercle fracture. It did demonstrate patella alta. Orthopedics was consulted, who admitted the patient and took him for operative repair the next day.
Take Away #1
Quad and patellar tendon ruptures occur more commonly in males than females, and quad tendon ruptures are more common than patellar tendon ruptures. Risk factors include people with rheumatologic disease, renal failure, or diabetes. Suspect these when there is an injury involving sudden quadriceps contraction while the knee is flexed (jumping, missing a step on the stairs) and pain with extension or inability to extend the knee
Take Away #2
Your exam will guide your management. Palpate for high riding or low riding patella with inferior or superior defect to determine if it is patellar or quadriceps tendon injury. Palpate at the tibial tubercle for tenderness. Test the extensor mechanism. Test for distal neurovascular status as these can sometimes have large effusion. MRI the knee if there is uncertainty regarding a partial versus complete tear.
Take Away #3
You MUST test the extensor mechanism (knee extension and active straight leg raise). If it is intact, secure the knee with an immobilizer and ensure close orthopedics follow-up for serial x-rays and an MRI is recommended. If it is not intact, orthopedics consult in the ED is indicated as poor functional outcomes are associated with delayed repair
Tim Khowong, MD is a current second year resident at Stony Brook Emergency Medicine.
References:
Patella Tendon Rupture. (n.d.). Retrieved from https://www.orthobullets.com/knee-and-sports/3024/patella-tendon-rupture
Quadriceps Tendon Rupture. (n.d.). Retrieved from https://www.orthobullets.com/knee-and-sports/3023/quadriceps-tendon-rupture
Tintinalli, J. E., Stapczunski, J. S., Ma, O. J., Yealy, D. M., Meckler, G. D., & Cline, D. M. (2016). Tintinallis emergency medicine a comprehensive study guide. New York, NY: McGraw-Hill Education.
Edited by Bassam Zahid, MD