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Acute and Chronic Patellar Tendon Ruptures After Total Knee Arthroplasty
CASE STUDY
A 48-year-old woman underwent a left total knee arthroplasty. A tibial tubercle osteotomy was performed for patellar maltracking 10 years before her arthroplasty. The postoperative course was uncomplicated. Approximately 18 months after surgery, the patient was playing golf and felt a pop in her left knee while bending down. She had pain and was unable to straighten the knee. Radiographs revealed a displaced patella fracture ( Fig. 27.1 ), which was treated with open reduction and internal fixation ( Fig. 27.2 ). She did well initially but sustained another twisting injury approximately 12 months after her surgery and had evidence of avascular necrosis of the patella, failed fixation, and disruption of the patellar tendon ( Fig. 27.3 ). She had a 40-degree extensor lag and complained of instability when walking. Initial attempts at conservative treatment failed, and the patient underwent extensor mechanism reconstruction with an allograft. Radiographs obtained 6 months after surgery showed a well-incorporated graft ( Fig. 27.4 ), and the patient has an intact extensor mechanism with a range of motion from 5 to 120 degrees.
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Chapter Synopsis
Disruption of the patellar tendon after total knee arthroplasty is an infrequent but devastating complication that should be avoided by use of careful intraoperative techniques. When it occurs, the treatment depends on several factors. Allograft tissue has historically provided the best means for reconstruction, and synthetic graft material has shown promising early results. With proper surgical technique that includes full tensioning of the allograft, an acceptable functional outcome can be achieved.
Important Points
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Identifying at-risk patients and use of meticulous surgical technique (including extensile exposures) are key to preventing patellar tendon disruptions.
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Primary repair of patellar tendon disruption has had poor results.
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Chronic disruptions require the use of allograft tissue or synthetic mesh for reconstruction.
Clinical/Surgical Pearls
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Inspection of the allograft tissue before surgery ensures adequate tissue for repair.
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Component position and rotation must be assessed and revised before allograft reconstruction.
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Meticulous surgical reconstruction and appropriate tensioning of the allograft are essential for a successful outcome.
Clinical/Surgical Pitfalls
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Patients must be willing and able to comply with postoperative instructions.
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Success of patellar tendon reconstruction depends on strict adherence to the postoperative rehabilitation protocol.
Introduction
Rupture of the patellar tendon after total knee arthroplasty (TKA) is an infrequent but devastating complication. The reported prevalence of this debilitating complication is 0.17% to 2.5%. Patients are left with dramatic functional impairment from extensor lag and instability of the joint. Nonoperative management often relegates patients to the use of a brace or cast and limits their ambulatory ability, which often necessitates surgical intervention.
The cause of patellar tendon rupture is complex and often multifactorial. It is important, therefore, to identify patients who are at risk preoperatively. Risk factors include obesity, previous history of corticosteroid use, stiffness, previous extensor mechanism complications, osteolysis, previous osteotomy, and patella baja. The arthroplasty surgeon must avoid problems during primary TKA that can lead to extensor mechanism failure. For example, appropriate extensile exposures must be used when necessary to avoid damage.
Ruptures can be categorized as acute or chronic. Acute ruptures of the patellar tendon occur during surgery, in the early postoperative period, or as the result of a traumatic injury that causes immediate extensor mechanism dysfunction. Chronic ruptures often result from an injury that is neglected, and patients develop extensor mechanism dysfunction over a longer period of time.
The success of surgical intervention for rupture of the patellar tendon after TKA depends on several factors, including the type of rupture (acute or chronic), quality of the remaining host tissue, and functional demands of the patient. Meticulous surgical technique and adherence to a strict postoperative protocol are imperative for a successful outcome after repair.
Disruption of the patellar tendon after TKA can be treated by primary repair with additional augmentation or by extensor mechanism reconstruction with the use of an allograft or synthetic graft. Primary repair alone for acute or chronic ruptures typically has produced poor results. It is not recommended as the sole treatment option and should be accompanied by augmentation of the repair.
Primary repair with augmentation of the host tissue is used for treatment of acute ruptures when there is good remaining host tissue. Numerous surgical augmentation procedures using sutures, staples, wires, and autogenous tissue have been described, and surgeons should be familiar with the various techniques.
Extensor mechanism reconstruction with allograft tissue is used for the treatment of chronic patellar tendon disruption or in the acute setting when there is poor remaining host tissue to allow for an adequate primary repair with augmentation. The use of whole extensor mechanism allografts or Achilles tendon allografts has become the mainstay of extensor mechanism reconstruction. Newer techniques using synthetic graft reconstruction have become popular and have had short-term success rates comparable to those obtained with the use of allograft tissue. This chapter focuses on the surgical techniques used for allograft extensor mechanism reconstruction after rupture of the patellar tendon.
Indications and Contraindications
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