Surgical Treatment of Traumatic Quadriceps and Patellar Tendon Injuries of the Knee

Joseph Featherall, BS

Daniel Hurwit, MD

Evan James, MD

Sava Turcan, BA

Anil Ranawat, MD

Dr. Ranawat or an immediate family member has received royalties from DePuy, A Johnson & Johnson Company and Stryker Mako; is a member of a speakers’ bureau or has made paid presentations on behalf of Arthrex, Inc., Ceramtec, Medtronic, Smith & Nephew, and Stryker Mako; serves as a paid consultant to or is an employee of Arthrex, Inc., Ceramtec, Medtronic, Moximed, Smith & Nephew, and Stryker Mako; has received research or institutional support from Arthrex, Depuy Mitek-Synthes, and Stryker; has stock or stock options held in ConforMIS Inc. and Enhatch; and serves as a board member, owner, officer, or committee member of the American Orthopaedic Society for Sports Medicine and the Eastern Orthopaedic Association. None of the following authors or any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this chapter: Mr. Featherall, Dr. Hurwit, Dr. James, and Mr. Turcan.

This chapter is adapted from Schottel P, Reinhardt KR, DiFelice GS, Ranawat AS: Surgical treatment of traumatic quadriceps and patellar tendon injuries of the knee, in Flatow E, Colvin AC, eds: Atlas of Essential Orthopaedic Procedures. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2013, pp 137-145.

INTRODUCTION

Anatomy

Ruptures of the extensor mechanism of the knee are debilitating injuries that typically require surgery and prolonged physical therapy. The severity of this injury is due in part to the central role that knee extension plays in the activities of daily living. The knee extensor mechanism is composed of four principal components: the quadriceps femoris muscles (rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius), the quadriceps tendon, the patella, and the patellar tendon (Figure 1). The tendinous portions of the quadriceps muscles coalesce into the quadriceps tendon on average 3 cm proximal to the superior pole of the patella. From the patellar insertion, the tendinous portion of the rectus femoris, the most anterior component of the quadriceps tendon, continues over the anterior surface of the patella, joining the patellar tendon at the inferior patellar pole. The patellar tendon subsequently inserts into the tibial tubercle.

Epidemiology

Patellar fractures are the most common cause of extensor mechanism failure, with an incidence of approximately six times that of both quadriceps and patellar tendon ruptures. An epidemiological study in the United Kingdom demonstrated an overall incidence of 1.3% for quadriceps tendon ruptures and 0.6% for patellar tendon ruptures.¹ Indirect injury accounts for twice as many quad tendon injuries and three times as many patella tendon injuries as direct injury.² It is also important to recognize that quadriceps and patellar tendon ruptures have a characteristic demographic presentation. Most quadriceps tendon ruptures occur in patients older than 40 years, whereas most patellar tendon ruptures occurred in patients younger than 40 years. Males are much more likely to endure a patellar or quadriceps tendon rupture. Recently, Garner et al showed that 91% of quadriceps tendon and 95.5% of patellar tendon ruptures occurred in males and that the mean ages for quadriceps and patellar tendon injury were 61 and 39.5 years, respectively.³

Biomechanics and Pathology

The relative infrequency of tendinous rupture is due in part to the relative strength of the tendons. Biomechanical studies have estimated that the force required to disrupt the knee extensor mechanism is approximately 17.5 times body weight. Therefore, when nondirect traumatic tendinous rupture does occur, it is likely to occur through an area of pathologic change in the tendon. Conditions known to predispose patients to tendon rupture include end-stage renal disease, diabetes mellitus, rheumatoid arthritis, gout, obesity, hyperparathyroidism, systemic lupus erythematosus, systemic steroid use, infection, and repetitive microtrauma. Reports vary, but the incidence of concurrent systemic disease known to predispose to tendon rupture has been reported to be as high as 20% in unilateral quadriceps tendon ruptures and 70% in bilateral ruptures.⁴ Patient sex may also play a role: in Garner et al’s study, 96% of females with a tendon injury had an underlying medical comorbidity compared with 68% of males.³

FIGURE 1 Illustration shows the musculoskeletal anatomy of the knee, including the four normal components of the knee extensor mechanism: the quadriceps femoris muscles, the quadriceps tendon, the patella, and the patellar tendon.

In addition to predisposing systemic diseases, the vascular density of the tendon may also contribute to the location and reason for tendon failure. Using cadaver models, Yepes et al showed that the area of poorest tendinous blood supply was 1 to 2 cm from the patellar insertion site of the quadriceps tendon. This finding corroborates the observation that most quadriceps tendon ruptures occur within 2 cm of the superior patellar pole. The same study also reported that the highest vascular density in the tendon occurred within 1 cm of the superior patellar pole.⁵

PATIENT SELECTION

Surgical Timing

The timing of surgical repair has been shown to be clinically important. Repairs performed more than 2 weeks after injury have been associated with increased surgical complexity and unsatisfactory results, such as decreased knee range of motion (ROM) and quadriceps strength. It has also been demonstrated that chronic repairs are more likely to require graft augmentation to achieve a satisfactory outcome.⁶ Although studies have attempted to define the optimal timing of surgery, no clear consensus has yet been reached.⁴^,⁷^,⁸ Nevertheless, our recommendation and practice are to repair all extensor mechanism ruptures in an acute fashion: within 3 weeks, when possible.

Contraindications

Numerous relative contraindications exist for the tendinous repair of the extensor mechanism. Although each particular clinical scenario needs to be assessed carefully by the surgeon, we believe that nonsurgical management should be strongly considered for nonambulatory
patients and for patients with significant medical comorbidities, compromised soft tissues around the knee as a result of infection, trauma, or radiation, a known history of noncompliance with rehabilitation, or chronic irreparable tears.

Surgical repair is almost always advocated for complete tears. Nonsurgical treatment may be acceptable in cases of incomplete extensor mechanism tendon tears. Incomplete tears are diagnosed when patients retain active knee extension against gravity while supine but demonstrate compromised extension against resistance while in a seated position. Although these patients typically present with an effusion, they lack the large palpable tendinous defect and the common radiographic findings of patella baja or patella alta that are seen in patients with complete tears. A common treatment regimen for a partial tear includes elevation, ice, compression, anti-inflammatory medications, and knee immobilization in a brace locked in extension followed by progressive ROM and strengthening exercises.

PREOPERATIVE IMAGING

In addition to the clinical examination and patient history, imaging studies are important not only to confirm the presence and severity of an extensor mechanism tendon rupture but also to evaluate for concomitant injuries. Common imaging modalities include plain radiography, ultrasonography, and MRI.

Radiographs should be obtained for patients presenting with knee pain when a quadriceps or patellar tendon tear is suspected. At a minimum, anterior-posterior and lateral views should be obtained, with additional projections such as Merchant and oblique views, depending on the clinical scenario. Characteristic findings on plain radiographs in patients with quadriceps tendon tears include patella baja, interruption of the quadriceps tendon soft-tissue shadow, and a suprapatellar soft-tissue mass (Figure 2). In cases of patellar tendon rupture, patella alta is the most characteristic radiographic finding. Patella alta can be identified by the patella being located superior to Blumensaat line on the lateral image or by an increased Insall-Salvati ratio (Figure 3).

Ultrasonography is another means of diagnosing a quadriceps or patellar tendon tear. Although this modality is operator dependent, it is an expeditious and relatively inexpensive way to determine the location and completeness of the tear, as judged by the presence and extent of an anechoic shadow (Figure 4). MRI is typically used to evaluate the extent of tendon disruption and to identify concomitant injuries. It may also help characterize tendinopathy at the site of injury. A study examining extensor mechanism ruptures and concomitant knee injuries using MRI found that patients with a patellar tendon rupture had a 30% incidence of a concomitant injury and those with a quadriceps tendon rupture had a 10% incidence, with anterior cruciate ligament and medial meniscus tears being the most common findings.⁹ Although MRI is expensive and may potentially delay treatment, its ability to confirm a clinical diagnosis and provide additional
anatomic information, facilitating the formulation of a more accurate surgical plan and the identification of concomitant injury, can be invaluable (Figure 5).

FIGURE 2 Lateral radiograph of the right knee of a patient with a rupture of the quadriceps tendon. The patella is below the Blumensaat line, indicating patella baja.

FIGURE 3 Lateral radiograph of the left knee of a patient with an acute rupture of the patellar tendon. The image clearly demonstrates patella alta, with the entire patella above the Blumensaat line.

FIGURE 4 Sagittal ultrasonographic image of a ruptured quadriceps tendon. The anechoic shadow within the substance of the tendon (arrow) represents the rupture.

VIDEO 23.1 Repair of Injuries to the Extensor Mechanism: Quadriceps and Patellar Tendons. Spero G. Karas, MD; Richard J. Hawkins, MD, FRCSC; J. Richard Steadman, MD (10 min)

View Quicktime Video

Video 23.1

PROCEDURE

Positioning and Preparation

Under regional anesthesia, the patient is positioned supine with a bump under the hip of the surgical extremity. A tourniquet is placed as proximal as possible on the surgical extremity, and the patient is prepared and draped in the usual sterile fashion. An examination under anesthesia is conducted to evaluate for soft-tissue injuries or confirm the presence and extent of such injuries identified in preoperative imaging. Antibiotic administration is confirmed, and the tourniquet is inflated after exsanguination of the extremity.

FIGURE 5 Extensor mechanism injuries of the knee. A, Sagittal T1-weighted MRI demonstrates an acute patellar tendon rupture. B, Sagittal fluid-sensitive, fat-suppressed MRI demonstrates an acute quadriceps tendon tear.

Quadriceps Tendon Repair

Numerous methods have been described for the repair of quadriceps tendon tears. Although the location, extent, and chronicity of the tear may dictate the use of one method over another, the most commonly used technique is a transosseous tunnel technique. This technique involves placing interlocking sutures through the proximal tendon, passing them through longitudinal transosseous patellar drill holes, and subsequently tying them over a patellar bone bridge (Figure 6). In a case series examining this technique with 6 years of follow-up, 100% of patients were able to achieve full extension postoperatively and 97% were able to return to work at their previous level of function.¹⁰ This method is best used for tears that occur at or near the osteotendinous junction. An end-to-end primary repair with interrupted nonabsorbable sutures may be used for midsubstance tears with sufficient proximal and distal tendon remaining. Variations of these two techniques, including the use of suture anchors, suture tapes, or reinforcement of the repair with a partial-thickness turndown of the quadriceps tendon, known as the Scuderi technique, have been described in the literature. As suture anchors have become more popular in recent years, a number of biomechanical studies have demonstrated that suture anchors are equally as strong or superior to transosseous tunnels.¹¹ This section describes our preferred surgical technique for repair using transosseous tunnels.

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