Quadriceps tendon rupture is an injury that occurs when the tendon attaches the quadriceps muscle (a group of 4 muscles in the front part of the femur) to the patella or kneecap tears. The quadriceps tendon may be partially or completely torn. Quadriceps tendon rupture is a rare but serious injury. If this injury is not promptly recognized and early operated on, it may lead to disability the quadriceps tendon works with the quadriceps muscle to extend the leg. All four parts of the quadriceps muscle attach to the shin via the patella (knee cap), where the quadriceps tendon becomes the patellar ligament. It attaches the quadriceps to the top of the patella, which in turn is connected to the shin from its bottom by the patellar ligament. A tendon connects muscle to bone, while a ligament connects bone to bone. Small tears of this tendon cause pain or make it difficult to walk and participate in other daily activities. A complete tear of the quadriceps tendon is a disabling injury. It almost always requires surgery, followed by physical therapy to regain full knee motion and function. Quadriceps tendon tears are not common. A quadriceps tendon rupture can be treated by both non-surgical and surgical methods. Most cases of small or partial ruptures are treated with a non-surgical approach. Non-surgical treatment involves the use of a knee brace or immobilizer to keep the injured knee straight and help it heal.
Other Names
- Quad Rupture
- Patellar Tendon Rupture
- Extensor Mechanism Rupture
- Knee Extensor Mechanism Rupture
Pathophysiology
- Mechanism
- Can be spontaneous
- Minor direct trauma following progressive tendon degeneration
- Violent eccentric contraction of the extensor mechanism.
- Result of a tensile overload on the extensor mechanism and long-standing chronic tendon degeneration
- Quadriceps muscle suddenly contracts with the knee in a flexed position (flexed more than 60 degrees)
- Due to sudden, eccentric contraction of the quadriceps from
- Jump and land mechanism
- Sudden change in direction
- Less commonly, direct trauma
- Typically involving an eccentric load of the quads
- Tendon ruptures rarely occur mid substance, and more commonly manifest as
- Avulsion fracture
- disruptions at the musculotendinous junction
- disruptions at the osseotendinous junctions
- Quadriceps Tendon
- Associated with degenerative changes
- Patellar Tendon Rupture
- Involves complete tear of the patellar tendon (connects from the patella’s inferior pole to the tibial tubercle)
- Zernicke et al: a force of 17.5 times body weight is required to cause patellar tendon rupture in healthy patients[6]
Pathoanatomy
- Quadriceps Femoris are formed by the confluence of 4 muscles into the quadriceps tendon:
- Rectus Femoris, Vastus Lateralis, Vastus Intermedius, Vastus Medialis
- Extensor Mechanism
- Quadriceps tendon inserts into Patella, Patella Tendon, in turn, attaches to Tibial Tubercle
- Quad Tendon Injury Location
- A relatively hypovascular zone exists about 1–2 cm superior to the patella, making it more susceptible to injury[7]
- In younger folks, the most common sites of the tear are between 1 cm and 2 cm of the superior pole of the Patella
- In older folks, more distally at the osseotendinous junction
- Patellar Tendon Injury Location
- Most occur at the inferior patellar pole
- Proximal avulsion of the tendon, with or without bone from the inferior pole of the patella
- Midsubstance of the tendon
- Avulsion of the patellar tendon from the tibial tubercle
- Demographic Risk
- Increasing age
- Obesity
- Orthopedic History of
- Patellar Tendonitis
- Previous ACL Repair
- History of Total Knee Arthroplasty[8]
- Systemic Illnesses
- End-Stage Renal Disease[9]
- Diabetes Mellitus
- Rheumatoid Arthritis
- Hyperparathyroidism
- Gout
- Pseudogout (CPPD)
- Connective tissue disorders
- Iatrogenic risk factors
- Medication use such as fluoroquinolones, Statins
- History of Oral Corticosteroid use
- History of IA Corticosteroid Injections
Differential Diagnosis Thigh Pain
- Fractures
- Femoral Shaft Fracture
- Femoral Shaft Stress Fracture
- Distal Femur Fracture
- Muscle and Tendon
- Quadriceps Tendonitis
- Quadriceps Contusion
- Quadriceps Tendon Rupture
- Hamstring Strain
- Hamstring Tendonitis
- Adductor Strain
- Adductor Tendinopathy
- Neurological
- Meralgia Paresthetica
- Other
- Myositis Ossificans
- Acute Compartment Syndrome
- Osteitis Pubis
Differential Diagnosis Knee Pain
- Fractures
- Distal Femur Fracture
- Patellar Fracture
- Tibial Plateau Fracture
- Dislocations & Subluxations
- Patellar Dislocation (and subluxation)
- Knee Dislocation
- Proximal Tibiofibular Joint Dislocation
- Muscle and Tendon Injuries
- Quadriceps Contusion
- Iliotibial Band Syndrome
- Quadriceps Tendonitis
- Patellar Tendonitis
- Popliteus Tendinopathy
- Extensor Mechanism Injury
- Patellar Tendon Rupture
- Quadriceps Tendon Rupture
- Patellar Fracture
- Ligament Pathology
- ACL Injury
- PCL Injury
- MCL Injury
- LCL Injury
- Meniscal Pathology
- Posterolateral Corner Injury
- Multiligament Injury
- Arthropathies
- Knee Osteoarthritis
- Septic Arthritis
- Gout
- Bursopathies
- Prepatellar Bursitis
- Pes Anserine Bursitis
- MCL Bursitis
- Infrapatellar Bursitis
- Patellofemoral Pain Syndrome (PFPS)/ Anterior Knee Pain)
- Chondromalacia Patellae
- Patellofemoral Osteoarthritis
- Osteochondral Defect Knee
- Plica Syndrome
- Infrapatellar Fat Pad Impingement
- Patellar Instability
- Neuropathies
- Saphenous Nerve Entrapment
- Other
- Bakers Cyst
- Patellar Contusion
- Pediatric Considerations
- Patellar Apophysitis (Sinding-Larsen-Johansson Disease)
- Patellar Pole Avulsion Fracture
- Tibial Tubercle Avulsion Fracture
- Tibial Tuberosity Apophysitis (Osgood Schalatters Disease)
Symptoms
- Popping or tearing sensation in the quadriceps.
- Cramping, bruising or tenderness.
- Inability to walk without the leg giving way.
- A depression where the tendon tore.
Diagnosis
- History
- Acute injury
- Commonly hear a pop or tearing sensation
- Preceding tendinopathy symptoms is common
- Suprapatellar (quad tendon) or infrapatellar (patellar tendon) pain
- Inability to bear weight
- Exam: Physical Exam Knee
- Tenderness at site of rupture
- Quad: Palpable defect usually within 2 cm of the superior pole of the patella
- Patellar: Palpable defect between inferior pole and tibial tubercle
- Unable to extend the knee against resistance or gravity
- Patella: low riding (quad tendon), high riding (patellar tendon)
- Joint effusion is often present
- Weak knee extension or extension lag suggests incomplete disruption
- Decreased ROM
- Special Tests
- Straight Leg Raise: unable to perform due to loss of extensor mechanism
Patella alta and inferior patella pole avulsion fracture suspicious for patellar tendon rupture
- Standard Radiographs Knee
- AP and lateral of knee
- Quad Tendon: Patella pulled inferiorly by the Patellar Tendon, termed patella baja
- Patellar Tendon: Patella is pulled proximally by quad tendon, termed patella alta
- Avulsion injuries present as patellar or tibial tubercle avulsion fractures
- Insall-Salvati Ratio is used to evaluate patellar height on the lateral view
US of the knee in quad tendon, long axis. There is a complete tear of the tendon approximately 4 cm proximal to its insertion with a 2.3 cm defect and hematoma[10]
Ultrasound
- Pathologic Findings
- Complete tear: Hypoechoic area between the two tendon fragments
- Partial tear: hypopoechoic area with some intact tendon fibers
- Assess the degree of tendon gap with knee flexion
- Normal
- Quad tendon is 6–11 mm thick
- Linearly oriented homogeneous echoes extending through the length of the tendon
MRI
- May show
- Differentiates between partial and complete tears
- Obtain if uncertainty regarding diagnosis
- Can evaluate for other intra-articular injuries
Treatment
Prognosis
- Surgical
- Boudicca et al found good functional outcomes in 50 patients followed for 6 years for pain, function, and range of motion [11]
- Most studies report good or excellent results ranging from 80 to 92% following surgical repair[12]
- Return to sport
- Nguyen et al found NBA players returned to the sport at a similar competition level[13]
- Boublik et al also found NFL players were able to return to a high level of competition[14]
Nonoperative
- General
- Partial quadriceps tendon ruptures may be managed non-operatively if the extensor mechanism is intact
- Partial patellar tendon ruptures may be managed non-operatively if the extensor mechanism is intact
- Consider in patients who are poor surgical candidates due to comorbidities
- Acute Management
- Rest
- Ice Therapy
- Compression
- Immobilization in Knee Immobilizer
- Quad Tendon
- Immobilized in full extension for 6 weeks
- Patellar Tendon
- Fully immobilized in extension for 2 weeks
- Begin active/ passive flexion/extension at 4 weeks, strengthening at 6 weeks
- Effusion should be aggressively managed to minimize tension on extensor mechanism
Operative
- Indications
- Complete tear
- Partial or incomplete tear with functional deficit
- Poor response to conservative measures
- Technique
- Primary repair of acute rupture
- Primary repair of chronic rupture
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