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Review Question - QID 218200

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QID 218200 (Type "218200" in App Search)
A 62-year-old healthy female presents for her annual visit after undergoing a left total knee arthroplasty seven years ago. She states she was doing well until she sustained a fall four months ago. Since that time, she has endorsed weakness in her knee and significant limitations going up and down stairs. Her primary care doctor provided a physical therapy referral, which has not provided relief after 8 weeks of sessions. She is found to have a 30-degree extension lag with radiographs shown in Figures A and B. The patient's serum labs included ESR of 10 mm/hr (normal 0-22 mm/hr) and CRP of 1.1 mg/dL (normal <0.5mg/dL). A knee aspiration is performed resulting in negative alpha defensive, negative leukocyte esterase, synovial WBC of 1,200 cells/mL, and 78% neutrophils. Which of the following is the most appropriate treatment?
  • A
  • B

Provide the patient with a drop lock brace to assist with ambulation and refer for additional physical therapy

4%

36/829

Lower the joint line via additional tibial resection and proximal patellar button placement

6%

50/829

Perform primary repair via the Krackow suture technique shuttled through bone tunnels

11%

94/829

Perform tendon reconstruction via interweaving mesh augmentation

75%

619/829

Removal of all underlying hardware and place a static spacer

2%

19/829

  • A
  • B

Select Answer to see Preferred Response

This patient presents with patella baja and a notable extension lag, consistent with a quadriceps tendon disruption. Given the high rates of failure from primary tendon repair, reconstruction should be attempted utilizing either allograft or mesh reconstruction.

Extensor mechanism disruptions after total knee arthroplasty (TKA) are rare, devastating complications that are best managed with operative intervention to achieve the highest functional outcomes. Disruption to any portion of the extensor mechanism after TKA has been attributed to trauma, unrecognized iatrogenic injury during initial TKA, mal-positioned implants, cutting the patella too thin (<12mm), and/or local vascular disruption in the multiple-revision patient. In cases of tendinous disruptions, primary repair has consistently been shown to result in high rates of failure due to re-rupture or persistent extension lag. Therefore, reconstruction serves as the current standard of care for these patients. Achilles tendon or whole extensor mechanism allografts are most often utilized and have demonstrated good results. In 2011, Browne and Hanssen described a novel technique utilizing synthetic mesh as an alternative to allograft purporting its lower cost, averted risk for disease transmission, and equivalent outcomes. Therefore, both allograft and synthetic mesh serve as acceptable surgical options for tendinous extensor mechanism disruptions after TKA. Unfortunately, even with reconstruction, there remains a considerable risk for failure or functionally limiting, persistent extensor lag (~25% of cases), and this should be discussed with patients before surgery.

Bates and Springer provided a comprehensive review article on managing extensor mechanism disruptions after TKA. They recommend nonoperative management and drop lock bracing for minimally ambulatory patients or those who have too many comorbidities to undergo surgery. They note the high rate of failure in primary repair and discuss the various grafts and techniques utilized for reconstruction. They conclude that no reconstruction method has reliably demonstrated superiority or optimal outcomes and more research is necessary in this patient population.

Brown and colleagues performed a retrospective review of 50 cases involving TKA extensor mechanism disruption in which a fresh-frozen allograft was utilized. They reported a 38% failure rate due to graft failure, deep infection, or clinically persistent extensor lag of >30 degrees. In patients with successful reconstruction, they noted significantly improved Knee Society scores and function. The authors concluded that an allograft reconstruction is a reasonable option for post-TKA extensor mechanism disruption, however, patients must be informed of high rates of failure.

Ricciardi and colleagues performed a similar retrospective review involving 25 cases of extensor mechanism reconstruction using a fresh-frozen allograft. They reported a 31% graft failure rate with an all-cause reoperation rate of 58%. They noted that patients undergoing reoperation for any cause had lower Knee Society scores and overall worse outcomes. The authors concluded that extensor mechanism allograft reconstruction shows adequate overall intermediate-term survival but comes with a high risk for reoperation.

Abdel and colleagues performed a retrospective review involving 77 cases of extensor mechanism reconstruction using Marlex mesh augmentation. At a mean follow-up of 4 years, the authors report a 20% initial mesh failure rate, of which most patients had successful mesh revision retained at the final follow-up. They also report significant improvements in functional outcomes and an average 26-degree improvement in extension lag. The authors conclude that the use of a Marlex mesh is a viable option for these patients with encouraging results.

Figures A and B demonstrate AP and lateral radiographic images of a left TKA with patella baja secondary to quadriceps tendon disruption. There does not appear to be any component loosening.

Incorrect Answers:
Answer 1: Drop lock braces are essentially hinged knee braces that allow patients to ambulate with the knee locked in extension and provide a quick release button to unlock the brace when they go to sit down. These braces should be reserved only for patients who are contraindicated to undergo reconstruction (i.e. too sick to undergo surgery).
Answer 2: This patient has patella baja secondary to a quadricep tendon rupture. Non-traumatic, longstanding patella baja is known to impart limited flexion after TKA with inferior patient-reported outcomes. Lowering the joint line via additional tibial resection and placing the patella button as proximally as possible are techniques utilized to mitigate the negative effects of patella baja in such patients.
Answer 3: Primary repair has consistently been shown to demonstrate a high rate of failure when performed after total knee arthroplasty. It is postulated that the surgical approach during the original TKA procedure, and subsequent dissection to perform patellar tendon repair, completely disrupts the major feeding vessels perfusing the extensor mechanism tendons.
Answer 5: Performing revision TKA to a static spacer would be appropriate if the patient had labs or arthrocentesis results concerning an underlying periprosthetic joint infection. In this case, the patient appears to have well-fixed hardware and unconcerned labs. Therefore, it is safe and appropriate to proceed with extensor mechanism reconstruction.

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