A 66-year-old woman presented with a painful, unstable left total knee arthroplasty. She had undergone many prior procedures, including two revision arthroplasties, and during the past 2 years, she had had several falls. During that period, she had difficulty extending her knee, which felt unstable, but she sought no medical care.
She walked into our office with a left unstable gait while using a walker. The left knee had a healed midline incision with a trace effusion. There was a palpable gap in the quadriceps tendon at the superior pole of the patella with no active extension and a 90-degree extensor lag. The passive range of motion was 0 to 120 degrees. The lateral radiograph revealed a patella baja ( Fig. 28.1 ). She was diagnosed with a chronic rupture of the quadriceps tendon.
During surgery, it was found that the quadriceps tendon had retracted proximally and could not be advanced distally to the superior pole of the patella. The chronic rupture of the quadriceps tendon was reconstructed with an extensor mechanism allograft. A postoperative radiograph verified the position of the extensor mechanism allograft ( Fig. 28.2 ).
Chapter Preview
Disruption of the quadriceps tendon is a devastating complication after total knee arthroplasty (TKA), especially because of the functional disability associated with complete rupture. This chapter focuses on the management of acute and chronic quadriceps tendon rupture after TKA, including surgical techniques and postoperative rehabilitation programs.
Introduction
Extensor mechanism disruption is a devastating complication after total knee arthroplasty (TKA), and obtaining favorable outcomes from reconstruction can be extremely difficult. Among the different types of extensor mechanism failure, quadriceps tendon rupture is the least common, and there is a paucity of data in the literature regarding treatment and functional outcome. In a historical study by Lynch and colleagues, a 1.1% incidence of quadriceps tendon rupture was cited, but that rate is high compared with current standards. Dobbs and colleagues reported an incidence of 0.1% from the Mayo Clinic in 2005.
Quadriceps tendon rupture after TKA can have mechanical, systemic, and local causes. Most cases are traumatic and are the result of a fall on a flexed knee. The quadriceps tendon is subject to significant loads that approach 3000 N. The force in the quadriceps tendon is greater than in the patellar tendon at 90 and 120 degrees of flexion. Along with predisposing factors, a sudden force on the flexed knee at these loads can result in a rupture of the quadriceps tendon within its substance or at the bone attachment to the superior pole of the patella. Rheumatoid arthritis, diabetes, chronic renal failure, obesity, and hyperthyroidism can predispose an individual to quadriceps tendon rupture. Local factors such as overresection of patellar bone at the time of resurfacing, a lateral retinacular release that extends proximally and across the tendinous insertion of the vastus lateralis in a medial direction, patellectomy, and multiple injections may result in rupture.
Diagnosis of a quadriceps tendon rupture is fairly easy when there are findings of an extensor lag and palpable defect. A lateral radiograph may show a change in the patellar height compared with prior radiographs and may identify a patella baja ( Fig. 28.3 ). Ultrasound or metal-suppression magnetic resonance imaging (MRI) may be useful if the diagnosis is uncertain. If the rotation of the components is questionable, computed tomography (CT) may be used to rule out malrotation, which can cause extensor mechanism failure.
To avoid complications associated with chronic tears of the quadriceps tendon, such as retraction or proximal migration of the musculotendinous structure or knee instability, the lesions should be treated as soon as possible. Partial tears with a minimal extensor lag of less than 15 degrees can be treated nonoperatively with cast immobilization in extension for 6 weeks. Gradual resumption of motion in a flexion-controlled hinged knee brace for an additional 6 weeks is necessary. Nonoperative management has produced uniformly positive results for partial quadriceps tendon tears without extensor lag.
Acute complete tears with an extensor lag greater than 15 degrees require operative repair. Ruptures that are the result of tendon avulsion from the superior pole of the patella may be repaired by suture through drill holes in the residual patellar bone. Acute rupture within the substance of the quadriceps tendon can be repaired in an end-to-end fashion with augmentation if the tendon is of poor substance. Treatment should be reserved for acute tears without compromise of the structural integrity of the tendon. Despite use of the best technique, the results of primary repair can be disappointing, and Crossett and colleagues have reported mixed outcomes.
Surgical Repair of Acute Rupture of the Quadriceps Tendon
Equipment
Repair of an acute rupture of the quadriceps tendon requires the following equipment:
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Tourniquet
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Beath pin
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Suture passer
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Power drill
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No. 2 FiberWire or no. 5 nonabsorbable sutures
Surgical Technique
The prior anterior midline surgical incision is used and the dissection is extended through the subcutaneous layer. The entire extensor mechanism is exposed, and medial and lateral flaps are developed to visualize the medial and lateral retinacula. The hematoma is evacuated, and the joint is inspected through the rupture of the quadriceps tendon. The torn quadriceps tendon is identified and débrided to healthy tissue. If the rupture occurred as an avulsion from the superior pole of the patella, the residual tendon at the bone interface is débrided. The patellar bone and patellar component should be inspected to confirm that the component is well fixed. The thickness of the residual patellar bone is then determined; it is important to have at least 13 to 15 mm of residual bone in order to create the transosseous tunnels for suture passage. The drill holes are placed midway between the patellar component and the anterior patellar cortex.
Using no. 2 FiberWire or no. 5 nonabsorbable suture, two interlocking Krackow stitches are placed in the distal quadriceps tendon: one along the medial tendon and the other along the lateral tendon. The free ends of the sutures exit at the distal tip of the quadriceps tendon. Three longitudinal, intraosseous drill holes are placed 1 to 1.5 cm apart in a superior to inferior direction in the patella. The residual patellar bone should be at least 13 to 15 mm thick. The free ends of the sutures are then passed through the drill holes in a superior to inferior direction. The lateral and medial suture ends are passed through their respective drill holes, and the two center suture ends are passed together through the central drill hole ( Fig. 28.4 , A ).
An alternative method of passing the sutures is to drill the holes with a Beath pin. After the pin passes through the inferior pole of the patella, the sutures are placed in the eyelet and pulled through the inferior pole of the patella as the pin is manually removed from the bone. All the sutures are pulled through the patella, and the knee is brought to full extension. Tension is placed on all of the suture ends, and the proximal quadriceps tendon is brought into contact with the superior pole of the patella. The suture ends are then tied distally under maximum tension (see Fig. 28.4 , B ). The position of the patella should be checked to confirm that there is no tilt or subluxation.
To complete the repair, the residual tendon is sutured on the superior pole of the patella to the distal tendon, and the medial and lateral retinacula are repaired with no. 1 nonabsorbable sutures. The wound is then closed in layers, and the knee is immobilized in full extension.
Surgical Tips
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Interference with the fixation of the patellar component can be avoided by drilling in a proximal to distal direction while looking directly at the superior pole of the patella and holding it between the thumb and index finger.
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The drill holes should be placed equidistant between the anterior patellar cortex and the patellar component.
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The three drill holes should be equidistant from each other and not too close to the medial or lateral cortex.
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The distal tendon should make contact with the bone surface at the superior pole of the patella. Failure to do so produces a gap, in which case augmentation or a distal turndown should be considered.
Postoperative Care
After surgery, the knee is immobilized in full extension for 6 weeks. Full weight bearing is allowed with the knee in full extension in the brace or cast. At 6 weeks, a flexion-controlled hinged knee brace is placed, and active motion between 0 and 30 degrees is begun. Passive flexion by the physiotherapist is prohibited at this time. The hinged knee brace is adjusted to allow an additional 30 degrees of flexion every 2 weeks, and physiotherapy is usually initiated between week 8 and 10, when the patient can actively flex to 60 degrees. Twelve weeks after surgery, the brace is discontinued, and there are no restrictions to active flexion. Unrestricted activity is allowed when the patient has regained full motion and strength, which usually takes about 6 months.
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