Multiple options available for managing 3% rate of periprosthetic knee fractures

Locked plates, casts, revision surgery among operative, nonoperative treatments to consider.

Issue: October 2008

SAN FRANCISCO — Periprosthetic fractures can occur in various locations around total knee arthroplasty components, with outcomes depending greatly on the type of fracture aid treatment used, an orthopedist from the Mayo Clinic said.

Robert T. Trousdale, MD, said when treating periprosthetic supracondylar femur, patellar or tibial fractures, total joint surgeons should consider the fracture location, implant stability, patient’s gender and bone quality, among other factors.

“In our first 19,000 primary and revision total knees, the prevalence of fractures around the tibia, femur or patella was just under 3%,” he said. “The most common fracture we see is periprosthetic fractures that occur in the supracondylar region above a total knee replacement,” Trousdale said at the 2008 Knee Society Specialty Day Meeting held during the annual meeting of the American Academy of Orthopaedic Surgeons.

$Tibial periprosthetic fractures are least common$
Tibial periprosthetic fractures are least common, occurring at a rate of 0.7% in patients seen at the Mayo Clinic, Rochester, Minn.

Images: Trousdale RT

Supracondylar area

Risk factors for supracondylar femur fractures include female gender, conditions that cause osteopenia, neurologic conditions that lead to falls and potentially anterior notching of the knee during surgery. Notching in high-risk patients can be especially problematic, Trousdale, who is a member of the Orthopedics Today Editorial Board, noted.

“Treatment options for these fractures are really threefold,” including nonoperative care, operative fracture fixation or total knee arthroplasty (TKA) revision, he said.

Indications for nonoperative treatment are rare. Patients treated in that manner run the risk of knee stiffness, fracture malunion or nonunion. Therefore, Trousdale only recommends it for nonambulatory elderly patients and those with selected nondisplaced fractures.

$Supracondylar femur fractures are amenable to operative treatment$
Supracondylar femur fractures are amenable to operative treatment and fixation with lateral plating and retrograde nailing, according to Trousdale. He reserves use of external fixators in these cases for patients with skin problems or severely comminuted fractures that might otherwise heal in poor alignment.

Fixation options

“Operative treatment is for the majority of patients with a displaced fracture. It decreases the risk of knee stiffness,” Trousdale said. One fixation strategy is lateral plating, such as fixed angle blade or locking plates, implanted through a lateral incision using fluoroscopy for optimal positioning.

A retrograde nail usually produces reasonable alignment in displaced supracondylar fractures, but is not compatible with all TKA designs, Trousdale added.

“We reserve external fixators for patients who have extremely comminuted bone where you are not going to get good fixation or in patients who have major skin problems around the knee,” he said. TKA revision is indicated for loosened or markedly malpositioned implants.

Lateral incisions make placing lateral plates easier when fixing supracondylar femoral fractures. Trousdale recommended using fluoroscopy to improve the accuracy of their placement.

Patellar fracture subgroups

Periprosthetic fracture can occur in the patella and is associated with resurfaced patellae osteolysis and revision TKAs. “In our clinic, males have higher risk of patella fractures than females,” Trousdale explained.

He classifies these fractures into three subgroups to select the best treatment, as follows:

For patients with an intact extensor mechanism and stable implant, use nonoperative management;
A disrupted extensor mechanism with distal fracture calls for fragment excision and tendon advancement; and
Treat loose patellar components surgically with revision or resection arthroplasty, patellectomy or bone grafting.

The 0.7% rate of periprosthetic tibial fractures is a relatively rare fracture. “This is the least common fracture around a knee arthroplasty,” Trousdale said. When it occurs with loose implants and osteolysis, he recommended long-stemmed revision components.

Casting is also an option for tibial fractures located well below the primary implant.

For more information:

Robert T. Trousdale, MD, can be reached at Mayo Clinic, 200 First Street SW E14B, Rochester, MN 55905; 507-284-3663; e-mail: trousdale.robert@mayo.edu. He has no direct financial interest in any products or companies mentioned in this article.

Reference:

Trousdale RT, Haidukewych GJ. Management of periprosthetic fractures. Symposium VII: Complications do happen: How to avoid them and what to do. Presented at the Knee Society/AAHKS Specialty Day Meeting. March 8, 2008. San Francisco.