Due to increased life expectancy, as well as the technological advancements that have been made in total knee arthroplasties (TKA), the number of TKA performed in the United States is expected to continuously increase. As a result, the total number of periprosthetic distal femur fractures is also expected to grow.1

After a TKA, surgical management of periprosthetic distal femur fracture is considered standard of care. The 3 most accepted options for the surgical treatment of such fractures are as follows: (1) plates and screws,2 (2) intramedullary nailing,3 and (3) a revision knee arthroplasty.4 While choosing the most appropriate surgery depends on multiple factors, early mobilization and ambulation are vital to decrease patient morbidity and mortality.

The most invasive among traditional methods are considered to be revision arthroplasty, which is often a salvage procedure with distal femoral replacement. This method is used in the instance of unrepairable fracture patterns or the loosening of mal-aligned implants with or without associated bone loss. Retrograde intramedullary nailing is another option, which is minimally invasive. It is not as technically demanding, often allows for early weight-bearing, and its limitations are generally related to one of 2 things: the complex anatomy of the fracture, especially those within close proximity to the femoral component, or implant compatibility, as the nails cannot be used with a closed-box femoral component already implanted.

In the invasive scale, a locked compression plate fits in the middle of the 3 main surgical methods mentioned. Its traditional use is indicated in cases of significant radiologic fracture comminution with reasonable preservation of bone stock around a well-fixed femoral component. Although this technique offers an early range of motion, patients often require a prolonged period of non–weight-bearing as the plate is a load-sharing device. Furthermore, current distal femur locking plates are oftentimes bulky and not suitable for patients of a more slender build.

Although a few comparative outcome studies already exist, recent literature has shown that when using this technique there are lower reoperation rates, a decreased risk of malalignment, and similar time to weight-bearing when compared with stabilization of periprosthetic distal femur fractures.5 However, the appropriate operative treatment is dependent upon numerous patient-specific factors including medical comorbidities, quality of bone stock, fracture anatomy, and stability/type of TKA implants. Through the use of a low-profile short plate and intramedullary fibular strut allograft, we present a modification to existing surgical techniques to meet our patient-specific challenges that would allow for early weight-bearing in a patient with a periprosthetic distal femur fracture in the setting of severe peri-implant osteoporosis.

Presented is a 72-year-old slender-stature woman with a past medical history of mild intermittent asthma and a right total knee arthroplasty performed many years ago at an outside hospital. The patient denied taking any medications at home and she was ambulating without an assistive device at baseline. She presented to the emergency department with a 3-week history of acute onset atraumatic right knee pain as well as a 4-day history of inability to bear weight on her right leg. She reported no recent direct trauma or falls, and besides the right knee pain, her physical examination revealed only mild swelling of the distal thigh. Her skin was intact with an unusually large primary TKA postsurgical scar. Plain emergency radiographs showed a right periprosthetic distal femur lateral unicondylar fracture above a cruciate-retaining total knee arthroplasty with radiologic evidence of osteoporosis (Fig. 1). In consideration of early weight-bearing all surgical options were discussed including the possibility of distal femur replacement. Initial planning also included plates and screws combined with an inlay medial strut allograft. Given the patient’s history, generalized osteoporosis, and the anatomy of her fracture, the other choice for fracture stabilization that would ensure postoperative early weight-bearing was a combination of load-bearing and load-sharing devices.

FIGURE 1:

Right knee periprosthetic fracture X-rays.

TECHNIQUE

The sight of the surgical scar from the previous TKA was used for a lateral parapatellar approach to the right knee joint and it was then confirmed that the periprosthetic fracture involved only the lateral cortex of the distal femur. Arthroplasty components were well fixed but the process of distal femur fracture hardware selection was complicated and it was concluded that available commercial distal femur plates even without onlay medial ½ fibular strut allograft were too bulky due to the slenderness of the patient. In search of alternative hardware and fracture fixation method, the femoral canal was accessed through the open-box site of the cruciate-retaining femoral component. This was followed by the insertion of an 8×110 mm ½ fibular strut allograft (Figs. 2A–D) and while trying distal femur hardware, a 1.2 mm stainless steel 6-hole T-plate (Stryker) became an optimal choice as a buttress (Fig. 2E) with 7 nonlocking screws inserted 3-cortically through the lateral femoral cortex inline with the ½ fibular allograft through the medial femoral cortex (Fig. 2F). The graft was initially held parallel to the plate by a large surgical clamp, later released after placement of the very first screw. The bone void in the femoral notch was bone grafted and sealed with bone wax (Figs. 2G and H), and the knee was brought through a full range of motion with axial loading. The hardware, strut allograft, and fracture were moving as one unit and there were no issues with TKA stability.

FIGURE 2:

Intraoperative photos.

Postoperatively, the patient was made weight-bearing as tolerated with no restrictions. She had no surgical complications and was routinely bearing weight after her surgery, with no changes in hardware alignment throughout the recovery process (Fig. 3).

FIGURE 3:

Right knee healed periprosthetic fracture X-rays.

Expected Outcome

At ~1-year follow-up, the patient presented in this technique guide has experienced a positive outcome, thus far. Recent radiographs and clinical examinations in the office are consistent with complete fracture healing. She has remained weight-bearing as tolerated since the date of the procedure without loss of fixation. While additional studies including a larger and more diverse sample size are necessary to further support this technique’s widespread use, this technique offers surgeons an option for unicondylar lateral femoral condyle distal femur fracture in patients with slender body habitus. Further, the use of a plate and an intramedullary fibular strut allograft may provide additional load-bearing properties, offering the benefit of early weight-bearing and mobilization for different distal femur periprosthetic fracture patterns in younger and older patients even in the setting of severe osteoporosis.

Complications

There were no complications seen during the use of this novel technique. However, theoretical complications of this technique are similar to that of other surgical techniques used to manage distal femur periprosthetic fractures including: malunion and loss of fixation, nonunion, hardware irritation, and infection.

ACKNOWLEDGMENT

The author wishes to acknowledge Katharine Cintron, BS, for her assistance in the writing and finalizing of this article.

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