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. Complete recovery takes at least 4 months, but most repairs are almost completely healed within 6 months. It may take even longer to completely achieve strength training and range of motion goals.
Other Names
- Quad Rupture
- Patellar Tendon Rupture
- Extensor Mechanism Rupture
- Knee Extensor Mechanism Rupture
Epidemiology
- Overall scant literature published on the subject due to relatively rare injury
- Greater occurrence with increased age (more common after age 40) and multiple medical comorbidities
- More prevalent in males
- Missed diagnosis rate is reported to range from 10-50%
- British study
- Incidence of quad tendons and patellar tendon ruptures are 1.37 and 0.6 per 100,000 person-years
- In this study, the mean age for males was 50.5, females 51.7
- Quad ruptures
- More common in patients older than 40 years
- Associated with degenerative tendon changes
- Quad tendon ruptures occur approximately 6 times more frequently than patellar ruptures
- Patellar tendon
- Typically observed in patients younger than 40 years
- Associated with direct traumatic mechanisms or end-stage patellar tendinopathy
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, 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
Pathoanatomy
- Quadriceps Femoris is 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
- 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
Risk Factors
- Demographic Risk
- Increasing age
- Obesity
- Orthopedic History of
- Patellar Tendonitis
- Previous ACL Repair
- History of Total Knee Arthroplasty
- Systemic Illnesses
- End-Stage Renal Disease
- 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
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-Johnansson Disease)
- Patellar Pole Avulsion Fracture
- Tibial Tubercle Avulsion Fracture
- Tibial Tuberosity Apophysitis (Osgood Schalatters Disease)
Clinical Features
- History
- Acute injury
- Commonly hear a pop or tearing sensation
- Preceding tendinopathy symptoms are common
- Suprapatellar (quad tendon) or infrapatellar (patellar tendon) pain
- Inability to bear weight
- Exam: Physical Exam Knee
- Tenderness at the 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
Evaluation
Patella Alta and inferior patella pole avulsion fracture suspicious for patellar tendon rupture
- Standard Radiographs Knee
- AP and lateral knee
- Quad Tendon: Patella pulled inferiorly by the Patellar Tendon, termed patella Baja
- Patellar Tendon: Patella is pulled proximally by the 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 the 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: hypoechoic area with some intact tendon fibers
- Assess the degree of tendon gap with knee flexion
- Normal
- The 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
- Surgical
- Boudicca et al found good functional outcomes in 50 patients followed for 6 years for pain, function, range of motion
- Most studies report good or excellent results ranging from 80 to 92% following surgical repair
- Return to sport
- Nguyen et al found NBA players returned to the sport at a similar competition level
- Boublik et al also found NFL players were able to return to a high level of competition
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 the extensor mechanism
Operative
- Indications
- Complete tear
- Partial or incomplete tear with a functional deficit
- Poor response to conservative measures
- Technique
- Primary repair of acute rupture
- Primary repair of a chronic rupture
Rehab and Return to Play
Rehabilitation
- In Hinged Knee Brace postoperatively
- Historically, the knee was immobilized in full extension for 6 weeks postoperatively to allow complete tendon healing before stressing the extensor mechanism
- The trend toward early post-operative joint mobilization to reduce joint stiffness and quadriceps atrophy
- Range of motion
- Surgeon dependent but can begin as early as week 1 limiting to 45° active flexion and passive extension only
- On weeks 2-3 can begin progressive range of motion past 45°, moving only 15° per week
- Strength
- Isometric quadriceps and hamstring exercises begin on post-op day 1
- Active knee extension starts at 6 weeks
- Ambulation
- Full weight-bearing in a locked brace, with crutches at 6 weeks
- Brace and crutches are discontinued when adequate quadriceps strength is achieved, usually around 12 weeks[15]
Return to Play
- Needs to be updated
Complications
- Pain and stiffness
- Extensor mechanism weakness
- Functional impairment
- Strength deficit
- Re-rupture
- Extensor lag, inability to fully extend the knee
- Loss of full knee flexion
- Quadriceps Atrophy
