Quadriceps Tendon Rupture – A Resident Clinical Pearl
Ida Szarics, PGY2
Dalhousie University
Reviewed by Dr. Paul Keyes
Copyedited by Dr. Mandy Peach
A 52 year old male presents to the ED with a right knee injury. He slipped while running, landing awkwardly on his right knee, with his foot caught behind him. He felt a “pop” and immediately had severe sharp right knee pain. He was unable to weight bear and states that his knee was swollen immediately afterwards. He denies any other injuries. He is otherwise healthy and is on no medications.
On exam, his vitals are within normal limits. There is obvious swelling of the right knee and has a palpable defect 2 cm above the patella which is extremely tender to palpation. He is unable to perform a straight leg raise. The remainder of the knee exam is non-contributory and he is neurovascularly intact.
He is clinically diagnosed with a quadriceps tendon rupture.
Above: Patients with complete quadriceps tendon ruptures will often present with a palpable defect within 2 cm above the patella. Image from: https://coreem.net/core/quadriceps-tendon-rupture/
Quadriceps tendon rupture: Mechanism
Quadriceps are the knee extensors, therefore rupture is most likely when the knee is flexed with simultaneous quadriceps contraction.1
-Age <40: Less common. Often occurs in athletes, particularly those who do not stretch activity, as a result of jumping and landing with the knee flexed. Patellar tendon rupture is more common in this age group
-Age >40: More common. Weaker tendons rupture more easily, so a fall onto a knee, or trying to prevent a fall onto the knees is typical.
Risk factors,2, 3
-Age (more common in patients >40 years of age)
-Male gender
-Type 2 Diabetes
-Renal disease
-Medications associated with tendon rupture (fluoroquinolones)
ABOVE: Anatomy of the muscles of the anterior thigh. Quadriceps tendon ruptures typically happen at the tendon’s insertion at the patella. Source: https://www.physio-pedia.com/Quadriceps_Tendon_Tear
Diagnosis
-Typically a clinical diagnosis, and is one of the “cannot miss diagnosis” in acute knee injuries.
-There is often a palpable defect ~2 cm above the patella where the tendon has been torn.
-Patients with a complete tear will be unable to perform a straight leg raise.
-Patients with a partial tear are unable to extend their knee against resistance – the ability to forcibly extend the knee against resistance is a critical part of the knee exam.
Investigations
XRays:
-May show a patella that is below expected anatomic position (patella baja). Of note, patella alta (or high-riding patella) can be a sign of patellar tendon rupture.
Ultrasound
-Can be a useful modality if diagnosis is uncertain. Often primary investigation available in the ED to supplement clinical exam findings.
MRI
-Best diagnostic modality, but cannot be obtained in the ED – this is typically a modality ordered by surgeons for surgical planning
ABOVE: Normal Knee XRay (left) and low-riding patella (right). The Insall Salvatti Index is the ratio of the patellar tendon length (red line) to the patellar length (yellow line). Normal is 0.8-1.2. Source: https://radiopaedia.org/articles/insall-salvati-ratio
Management
-Early surgical repair is important to maximize recovery, especially in complete tears. The distal tendon is avascular, so it will not heal well non-operatively.1
-Non-operative treatment (RICE, splinting, non-weightbearing) may be an option in partial tears or in patients with poor baseline mobility.
-Either way, orthopedic surgery should be consulted within a timely matter, usually within a week, to guide management. As time goes on difficulty of repair increases, as does probability of failed repair. The ED physician should provide adequate analgesia as needed, immobilize the knee, and advise non-weightbearing while the patient is in the ED.
Back to our patient
Orthopedic surgery is contacted, and a plan is made to see the patient in clinic the following day to plan surgical repair. The patient’s knee is immobilized in extension, and an outpatient MRI is ordered. The patient undergoes surgical repair later that week.
References:
1Sharareh, Ben. (2021). Quadriceps Tendon Rupture. Orthobullets. https://www.orthobullets.com/knee-and-sports/3023/quadriceps-tendon-rupture
2 Von Fange, T.J., (last updated, 2021). Quadriceps Tendon and Muscle Injuries. UpToDate.
3 Nori, S., (2018) Quadriceps tendon rupture. J Family Med Prim Care. 7(1): 257–260.
