Distal Femoral Replacement with a Metaphyseal Sleeve
A 63-year-old morbidly obese male has had 11 previous knee surgeries, including a total knee arthroplasty and multiple revisions. He now has severe, intolerable pain in his leg following a distal femoral replacement. When another revision procedure fails to relieve the pain, what options are left?
Laura Matsen Ko, MD, and Matthew S. Austin, MD
The authors have no disclosures relevant to this article.
Distal femoral replacement is a salvage operation for revision total knee arthroplasty (TKA) with severe bone loss and absence of collateral ligaments. Outcomes in the literature demonstrate varying survivorships: 67% at 5 years, 87% at 4 years, and 81% at 3 years. [1-3]
This case report illustrates a unique case of a patient presenting with a loose distal femoral replacement that had been revised but went on to subside and need further revision.
A 63-year-old male with past medical history of hypertension presented to our clinic in 2011. He had undergone 11 left knee surgeries, starting with a work-related injury in 1983. These surgeries included a primary total knee arthroplasty in the 1990s, multiple revisions of a knee replacement for infection, and, ultimately, a distal femoral replacement in 2003 at the age of 54.
At the time of presentation, the patient reported severe and intolerable pain in his left leg.
- Male patient standing 5 feet, 10 inches tall and weighing 300 pounds; BMI 43
- Well-healed incision on the left knee without signs of infection
- Range of motion in the left knee from 0° to 110° without instability
- 5° extensor lag
- 5/5 strength throughout lower extremity
- 2+ DP pulses
- Radiographic evaluation showed radiolucent lines circumferentially around his femoral component (Figure 1).
Figure 1. Preoperative images demonstrating a loose femoral component.
- Loosening of the distal femoral replacement
The patient had a negative workup for infection (normal erythrocyte sedimentation rate, normal C-reactive protein, normal synovial fluid aspirate) and underwent revision distal femoral replacement with a fully porous coated stem (Figure 2).
Figure 2. Immediate postoperative images demonstrating revised femoral and tibial components.
Four weeks after surgery, his femoral stem was noted to have subsided (Figure 3). He was then instructed to be non-weight-bearing for 6 weeks. The pain returned once the patient resumed weight-bearing.
Figure 3. One-month postoperative films demonstrating 2 cm subsidence of the femoral component.
He again had a negative workup for infection, and given the lack of osseointegration and continuing pain, he underwent a revision procedure.
The femoral component was found to be grossly loose and easily removed. Because of the early failure of the prior construct, a unique construct with a metaphyseal sleeve was used to provide initial fixation (Figure 4).
Figure 4. Radiographs after the last revision surgery, demonstrating the use of a 46-mm sleeve. The cable was applied prophylactically to reduce the risk of fracture during femoral preparation.
Three years after revision femoral replacement surgery, the patient is doing well and has satisfactory restoration his activities of daily living. In addition, he is no longer taking pain medication.
Revision total joint arthroplasty is becoming more prevalent. Primary total joints have an estimated survivorship of 94% at 5 years and 88% at 10 years based on a review of worldwide databases.  Survivorship of cemented primary TKA, based on the Norwegian Arthroplasty registry, is 89.5% to 95.3% at 10 years. 
As our patients age, they may require multiple revisions. Distal femoral replacement is an option when surgeons encounter massive bone loss and absent collateral ligaments.
We present a unique case of a morbidly obese patient in whom a metaphyseal sleeve was used to provide stable fixation for a distal femoral replacement. A study from our institution showed mean functional KSS improving from 47.9 to 61.1 and mean WOMAC from 55.3 to 25.9 when a metaphyseal sleeve was used in revision TKA procedures.  At minimum 2-year follow-up, two tibial sleeves (2.4%) required revision in a population with mostly Type IIb and III defects.  This was a unique use for the metaphyseal sleeve that differs from prior reports.
Megaprosthesis outcome studies show fair survivorship. A 5-year retrospective review of patients with compressive endoprosthetic fixation found that all mechanical failures occurred within the first 30 months.  At 5 years, implants survived in 67% of patients. 
A recent study demonstrated a 19.4% failure rate for revision distal femoral replacements at a mean of 3-year follow up, compared with an overall failure rate of 26.7% for all distal femoral replacements.  This suggests that survivorship is better in revision reconstructions than primary reconstructions. The most common complication was infection or wound dehiscence, followed by aseptic loosening. 
When tumor recurrence is eliminated, a study of megaprostheses in the lower limb showed 75.9% survival at 5 years and 66.2% survival at 10 years. 
Patients have fair function with megaprostheses. A study of oncologic patients with a mean age of 25.5 years with modular tumor endoprostheses of the knee demonstrated continued ability to participate in sporting activities.  Prior to the diagnosis of osteosarcoma, 89% of patients could participate in sports. Patients were still active 1 year (33%), 3 years (74%), and 5 years (89%) postoperatively, with cycling being the most common exercise and swimming being the second most common. 
A study of function at a mean of 13.2 years after surgery found that median oxygen consumption, walking speed, and mean strides per day among the endoprosthesis group did not differ from a healthy control group. 
Distal femoral replacement is a technically difficult surgery. Multiple standard surgical landmarks are no longer present, including femoral condyles and collateral ligament tension. Thus, careful attention must be paid to certain key portions of the reconstruction, and surgical pearls are listed below.
- Detailed informed consent, with emphasis on compliance with postoperative restrictions
- Preoperative planning with radiographs of the affected and contralateral limb to determine the proper length of bone resection and size of modular components needed
- Avoid incisions that may result in skin necrosis
- Blood loss management: tourniquet placed high on thigh (consider sterile tourniquet), tranexamic acid (if appropriate), adequate hemostasis
- Careful soft tissue management, as tissue is often already compromised by multiple prior surgeries
- Use of extensor mechanism and location of patella to restore the joint level
- Meticulous closure
Laura Matsen Ko, MD, is an adult reconstruction fellow at The Rothman Institute, Thomas Jefferson University, Philadelphia, Pennsylvania. Matthew S. Austin, MD, is Director of Joint Replacement Services at The Rothman Institute, Philadelphia, Pennsylvania.
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