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Published on Wednesday, 05 December 2012 22:25
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Written by Manny Konstantakos, MD.
Surgery Update: Quadriceps Tendon Ruptures
In a previous article, I focused on an overview of overuse injuries and tendinitis. Now it’s time to turn our attention to what happens when a tendon is completely torn. And yes, it can happen to anyone of us, unexpectedly:Branch Warren, Triple H, andRxMuscle’s President, Dave Palumbo.
Quadriceps Tendon Rupture , or simply referred to as ‘Quad rupture’, is a rather infrequent but serious injury requiring prompt diagnosis and treatment almost always requiring surgery. It usually occurs in individuals older than 40 years and can be associated with a few underlying medical conditions (especially in non-athletes). Sources include either indirect or direct trauma (i.e. car injury, trip or fall). Patients usually present to their health care provider with the classic triad of a gap right above the knee, pain, and inability to actively extend the knee (especially inability to perform a straight leg test). Most likely an x-ray will be performed to determine if there are any bone injuries. If the diagnosis is uncertain (or if the physician is questioning another co-existing injury within the knee), then an MRI may be ordered as well. Incomplete or partial ruptures(sometimes including jumper’s knee) are usually treated without an operation. Complete quad ruptures should undergo surgical repair. If quad ruptures are ignored, they can lead to further issues and difficulties down the road for the patient.
Anatomy
The quadricepsare composed of four separate muscles: the vastusmedialis, vastusintermedius, vastuslateralis, and rectus femoris muscles. These muscles merge into one tendon to attach at the superior border of the patella. The most anterior muscle of the quads, the rectus femoris, originates from the anteroinferioraspect of the iliac spine and also crosses the hip capsule. The rectus femoris is the only muscle of the quadriceps that crosses the hip joint and thus is more susceptible to injury than the other quad muscles (i.e. avulsion injuries off the iliac spine). The other remaining quad muscles (vastusmedialis, intermedius, and lateralis) all originate from the femur. The vastusmedialis originates on the anterior femur just below the level of the lesser trochanter. The vastusintermedius, originates at the anterior aspect of themidfemur and the vastuslateralisoriginates on the femur just past the greater trochanter and is anterior and lateral to the vastusintermedius. A separate muscle known as the articularis genu muscle,may also be considered to be part of the quads (but this muscle is really considered an anatomic variant and is not part of the quadriceps muscles). The quadriceps muscles are all innervated by the femoral nerve which ultimately arises from the spine.
It is important to remember that the four muscles that form the quadsall insert together on the patella. This insertion point on the patella is adjacent to the membranous layer of the knee joint and when someone sustains a quad rupture, a large hemarthrosis (blood in the knee joint) develops. In fact, this is exactly how Dave Palumbo presented to the ER in India with a very large hemarthrosis which was drained….ouch!! (see video of Dave in India).
Injury
Like all of the muscles in our body, the quads may contract concentrically (as the muscle shortens) or eccentrically (as the muscle lengthens). Very high forces can be generated during contraction of the quadriceps muscle. Most quad tendon ruptures occur during a sudden and unexpected eccentric contraction of the muscle, however. When the knee is in a semiflexed position, the quad tendon is under the greatest amount of stress. Most ruptures of the quad tendon happen when one is trying to regain their balance to avoid a fall. In this manner, the quads contract rapidly with a violent and rapid eccentric contraction.
Biology
Inflammation is what is needed to begin the healing process. This involves cells, known as fibroblasts, which migrate toward the area of injury. Granulation tissue then proliferates around the injury site and the amount of the fibroblasts increase with time which produces more collagen.
Tendons heal better when they are in close approximation to each other. Once a tendon is completely torn it frequently migrates apart from the torn area. Healing is very unlikely if the torn edge has migrated more than 2cm from its origin. The area of the tear is filled in with scar tissue which is much weaker than the native tendon tissue itself. One way to ensure an optimal healing environment is through surgery. Surgical sutureshold the tendon edges together and therefore allow the fibroblasts to produce enough collagen to re-form a strong tendon unit with a much lower risk of re-rupture than if surgery were not performed. It usually takes around 5 to 6 months for surgically repaired tendons to completely heal.
If a complete tendon tear is not repaired surgically, the area will form with scar tissue and ultimately result in a weak and elongated muscle-tendon unit. This will lead to poor muscle function which will likely never be as strong as on the opposite limb.
The quads are a very strong muscle group and are very difficult to tear. Studies have shown that up to 50% of a tendon’s fibers have to be severed for a quad rupture to occur, even when it is under extremely high forces. Up to 75% of the tendon’s fibers must be damaged or severed before a rupture occurs. This suggests that there usually is an inherent underlying weakness of the quad tendon to begin with that will lead to a quad rupture after a traumatic event (falling, jumping, etc.).
Intra-tendinous processes that lead to weak tendons include myxoid degeneration, microangioblastic dysplasia, and fatty and cystic degeneration. These changes mainly occur with age although it has been shown that quad ruptures are actually quite rare in older people and in the elderly. It is important to note that up to 30% of patients presenting with bilateral spontaneous quad ruptures and almost 20% of those with unilateral rupture have an underlying, and perhaps undiagnosed, systemic medical condition that leads to degeneration of the healthy tendon. This can easily lead to a quad rupture after a trivial event such as a simple fall in someone with these medical conditions.
Medical conditions can also weaken the quads due to muscle fiber atrophy. Diabetes leads to loss of blood flow in the tendon. Obesity causes fatty degenerative changes in the tendon. Hyperparathyroidism, systemic lupus erythematosus, osteomalacia, and use of cortisone can lead to microscopic damage to the blood supply, altering the normal architecture of the tendon and thus increasing the susceptibility to complete rupture. Gout and rheumatoid arthritis can both lead to necrosis and fibrotic intra-tendinous changes.
Supplementation
It is unknown whether performance enhancing agents such as anabolic steroids lead to quad rupture. As anabolic steroids lead to greater changes and hypertrophy in muscle rather than the tendon itself, a more forceful contraction of a larger and stronger muscle may lead to a muscle/tendon imbalance. However, most tendon injuries incurred during athletics occur at the musculo-tendinous unit and not in the substance of the tendon itself (as seen with quad ruptures).
An uncontrolled or unbalanced post-cycle phase (where there is an abundance of cortisone and low levels of free testosterone) may precipitate an environment of catabolism within the body and thus contribute to tendon degeneration. Further violent stresses to the tendon may then lead to catastrophic rupture.Hence, the importance of a well-planned post-cycle phase (if needed) and emphasis on controlled eccentric lifts during this time period is essential. However, these theories have not been proven in a clinical or laboratory setting as of yet.
Physical Exam
Individuals with quad tendon tears have a finding of three classic findings: inability to actively extend the knee, a gap above the patella, and pain. Once a quad rupture occurs, the patient cannot actively extend the knee and maintain extension against gravity (i.e. cannot perform a leg lift). A hemarthrosis may develop as the knee joint capsule tears as well. The patient is usually able to flex the knee.
Comparison with the opposite leg is essential to determine whether there is a ruptured quadriceps tendon with an intact retinaculum. Although a patient with a complete rupture may be able to ambulate, the examining physician should maintain a high level of suspicion for this injury in anyone presenting with acute onset of pain and inability to actively extend the knee in the presence of a fully functional flexor mechanism. When the suprapatellar gap is not readily apparent because of local fluid accumulation, the sign may be elicited by having the patient actively flex the hip while in the supine position. This maneuver causes active shortening of the rectus femoris muscle, which draws the remaining portions of the quadriceps superiorly, thus widening the defect at the site of rupture.
Diagnostic Studies
X-rays are also important when diagnosing a quad rupture. X-rays can show a mass right above the patella (suggesting the bunched-up edges of the torn quad tendon) as well as an inferiorly displaced patella.
Ultrasound is also a useful modality in diagnosing quad tendon tears, but its reliability is operator dependent (see figure 1).
Figure 1: Ultrasound image of torn quad tendon. Note the dark area (white arrows) suggesting the torn edges of the quad
MRI is the best imaging test in diagnosing a quad rupture. However, it is an expensive test and should be used only when a clinical diagnosis of a quad tendon tear is in doubt or other intra-articular injuries are suspected (see figure 2).
Figure 2: MRI of knee with arrow pointing to wavy edges of torn quad tendon.
Medical Treatment
Incomplete tears of the quad tendon usually do not require surgery. The knee is kept in full extension and immobilization for up to 6 weeks and then protected range-of-motion and strengthening exercises are begun.
Traumatic hemarthrosis resulting in knee effusion is common after quadriceps tendon rupture and hematoma aspiration may be of use in reducing pain and promoting recovery. It has been shown that even small amounts of effusion decrease quadriceps strength and therefore early range-of-motion exercises are warranted. The famous acronym ‘RICE’ rest, ice, compression, and elevation can help symptoms of pain and swelling.
Surgical Technique
A straight incision is made over the skin to expose the extensor mechanism. The hematoma is removed the tear is identified. Full-thickness flaps are elevated medially and laterally to access the apex of retinacular tears. The edges of the quadriceps tendon are débrided of grossly degenerative tissue and freshened for repair.
Midsubstance ruptures can be treated with primary repair if sufficient tendon exists proximally and distally. Ruptures at or near the osteotendinous junction, the most common site of injury, may be repaired through drill holes in the patella. Suture anchors have been used in place of drill holes with good result (see Figure 3).
Figure 3: Surgical illustration of quad repair
Rehabilitation
The knee is usually kept in a knee immobilizer after surgery for a few days. Weight-bearing is begun almost immediately. Physical therapy and other range of motion exercises are started after 4-6 weeks from the day of surgery. Good range of motion should be achieved by 3 to 4 months after repair.
Summary
Most traumatic ruptures of the quadriceps tendon are caused by an indirect, sudden eccentric muscle contraction. Patients present with sudden onset of pain with an impaired ability to extend the knee and a palpable suprapatellar gap. Plain radiographs, ultrasound, and MRI are used for diagnosis and evaluation.
An incomplete quadriceps tendon tear is treated without surgery. Surgery is needed in most cases for complete tears to avoid possible suboptimal outcomes that could be attributed to surgical delays.
Reference: Quadriceps Tendon Rupture; Doron I. Ilan, NirmalTejwani, Mitchell Keschner, and Matthew Leibman. J Am AcadOrthopSurg May/June 2003; 11:192-200.
