Harold I. Salmons, MD; Charles P. Hannon, MD, MBA , 2025-05-16 14:40:00
An 82-year-old woman with a medical history of diabetes mellitus type 2 (most recent hemoglobin A1c of 10.3%), atrial fibrillation (on apixaban) and hypothyroidism presented to our ED with left thigh pain.
Her surgical history was notable for a prior left primary total knee arthroplasty at our institution 4 years prior. Her knee was previously functioning well. However, 4 months prior to her current presentation, she fell and sustained a left distal periprosthetic femur fracture (Figure 1). This was managed at an outside hospital with open reduction and internal fixation (ORIF) using a lateral locking plate at the time of her original injury. Her fracture healing was followed radiographically thereafter, and it was noted that she had evidence of delayed healing of her fracture at 3 months after her ORIF (Figure 2).
Image: Charles P. Hannon, MD, MBA, and Harold I. Salmons, MD
Source: Mayo Clinic
The patient presented to our ED after suffering a sudden onset of pain while walking at home. She could no longer bear weight. She denied antecedent pain or trauma. Radiographs were obtained, and these revealed a new periprosthetic femur fracture through the prior area of her delayed union with an associated fracture and failure of her lateral locking plate (Figure 3).
Source: Mayo Clinic
On exam, she was alert and comfortable with the left lower extremity in a shortened and externally rotated position. There were no skin tears or open fractures. There was an obvious deformity about the left thigh. She was able to fire her quadriceps, tibialis anterior, extensor hallucis longus, posterior tibialis, peroneals and gastronemius/soleus muscles. She was sensate to light touch throughout the lower extremity. She had a warm and well-perfused foot and a palpable dorsalis pedis pulse that was symmetric to her uninvolved contralateral lower extremity.
Source: Mayo Clinic
What are the best next steps in management of this patient?
See answer below.
Revision ORIF with plate and nail construct
A serum C-reactive protein was collected along with baseline preoperative labs. This was normal, suggesting her fracture and associated delayed union were due to a mechanical rather than infectious cause. As such, a preoperative aspiration was deferred. She was placed into a well-padded knee immobilizer and consented for revision ORIF using an intramedullary nail and lateral plate combination, with debridement of her nonunion site.
Revision ORIF
The patient was placed supine. A lateral subvastus approach incorporating her prior lateral locking plate incision was utilized along the distal femur. Care was taken to identify and ligate perforating vessels. Abundant fracture hematoma was encountered. The broken lateral plate was identified and removed. At this point, the nonunion site was visualized and debrided of all fibrinous material thoroughly. Three cultures were sent, which later returned as negative for bacterial growth. The nonunion site was debrided until visible osseous bleeding was observed, and care was taken to avoid stripping periosteum. The fracture was noted to be mobile and, using a towel bump under the distal segment along with a slight valgus force, the fracture was reduced manually to an appropriate position.
At this point, attention was turned to the intramedullary nail. A 3-cm incision from the inferior pole of the patella to the proximal tibia was created incorporating her prior midline total knee incision. The scarred paratenon and accompanying patellar tendon were identified and split longitudinally in line with its fibers. Heavy scissors were used to bluntly dissect to the anticipated femoral start point for a retrograde femoral nail. A guide pin was inserted, followed by an opening 12-mm reamer. The ball tip guide wire was then inserted to the proximal femur, just distal to the lesser trochanter. Care was taken to maintain fracture reduction during the passing of the guide pin and subsequent reaming and nail insertion. A 340-mm nail length was selected, and reamers were sequentially administered through the reduced fracture site to a maximum diameter of 12.5 mm to accept an 11-mm retrograde femoral nail.
Visible oozing and bleeding were noted across the nonunion site, with the hopes that this would deliver appropriate biology to the area and assist with healing. Under biplanar fluoroscopy the retrograde femoral nail was inserted, taking care to maintain reduction of the fracture throughout this portion of the case. The nail was locked in static mode distally and then impacted into the proximal segment in a retrograde manner to facilitate further healing via compression across the fracture site. Paying careful attention to rotation, the proximal interlock was then implemented.
A new lateral locking plate was then fashioned to bone. A 241-mm plate was selected and locked distally after first being secured to bone with nonlocking screws. The plate spanned the area of fracture and nonlocking screws were implemented proximally. The goal of this revision dual-plate construct was to provide appropriate stability for immediate weight-bearing while concomitantly permitting enough strain across the fracture site to promote osseous union (Figure 4).
Source: Mayo Clinic
Postoperative rehabilitation
The patient was permitted to weight-bear as tolerated. Daily supplementation with calcium and vitamin D were encouraged. Deep venous thrombosis chemoprophylaxis was maintained for 30 days, and periprocedural antibiotics in the form of cefazolin were administered for 24 hours. The patient progressed with physical therapy in the hospital and was discharged on postoperative day 4.
At her 6-week follow-up, she had no pain and was ambulating with use of assistive devices as needed. Her radiographs demonstrated evidence of early fracture healing and maintained alignment (Figure 5). Her wound had healed well.
Source: Mayo Clinic
Discussion
Distal femur periprosthetic fractures above well-fixed TKAs are relatively rare but pose a significant challenge in orthopedic surgery. These fractures typically result from low-energy trauma in an elderly population, such as a fall, and require careful consideration of several factors during management. Treatment involves not only addressing the fracture itself but also considering the underlying knee prosthesis, the specific fracture characteristics, the patient’s general health and bone quality. The increasing longevity of patients following TKA suggests that the incidence of periprosthetic femur fractures will likely rise in parallel, with a corresponding need for improved management strategies. Current studies estimate the incidence of periprosthetic fractures to be between 1% to 2% of all TKA complications, although other reports suggest the rate may be as high as 3% to 5%. These fractures predominantly occur in the elderly population, which necessitates careful preoperative medical optimization and consideration of fixation strategies, especially given the often-compromised bone stock in this group.
Surgery is generally recommended for displaced fractures, as early mobilization postoperatively is crucial to minimize mortality risks in elderly patients. Various fixation options have been described in the literature, including lateral locking plates, dual-plating systems and plate-nail combinations. The choice of fixation method depends on careful evaluation of the fracture pattern, bone quality and the extent of involvement of the knee prosthesis. In the authors’ experience, intramedullary implants are often favored due to their load-sharing nature, which facilitates immediate weight-bearing. In cases involving comminution, additional plate fixation may be necessary to provide sufficient stability. A key consideration during preoperative planning is the compatibility of the TKA design with retrograde femoral nails, as the ability to pass a nail through the open box of the prosthesis can significantly impact the choice of fixation. Reference to recent studies, such as the work by Daniel E. Gerow, DO, and colleagues, which summarized the compatibility of various TKA implants with retrograde femoral nail systems, is crucial in guiding the surgical decision-making process.
For fractures extending distally close to the joint line, preoperative imaging, particularly CT scans, are essential in assessing the feasibility of intramedullary fixation. Surgeons must carefully evaluate the interlocking options for the retrograde femoral nail to ensure that sufficient fixation can be achieved distally. If interlocking distally is not feasible, lateral plate fixation can be an acceptable alternative, particularly in cases of simple fractures without significant instability. However, in more complex fractures or those involving substantial medial cortical comminution, dual-plate constructs may be necessary to provide adequate stabilization. Although dedicated distal medial femoral plates are available, the authors find that a flipped proximal humerus plate can serve as an effective and readily accessible solution for medial locking plate fixation in these situations.
In conclusion, the management of periprosthetic distal femur fractures above a well-fixed TKA requires a comprehensive, individualized approach that considers the patient’s overall health, bone quality and the specific characteristics of the fracture. Early weight-bearing should be a goal in the treatment of elderly patients, as it has significant benefits in terms of recovery and mortality reduction. Surgeons must balance the stiffness of the construct with the appropriate strain required for optimal fracture healing, taking care to ensure compatibility with the existing knee prosthesis and addressing any additional challenges posed by complex fracture patterns.
Key points:
Distal femur periprosthetic femur fractures offer a challenge to the surgeon and portend significant morbidity and mortality risk to the elderly patient.
A careful consideration of patient factors along with fracture location, morphology and a review of TKA compatibility for retrograde femoral nailing are paramount.
While multiple options for surgical fixation have been described, selection of the construct that best supports immediate weight-bearing is favored.
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For more information:
Charles P. Hannon, MD, MBA, and Harold I. Salmons, MD, can be reached at the department of orthopedic surgery at the Mayo Clinic in Rochester, Minnesota. Salmons’s email: salmons.harold@mayo.edu.
