A new operative procedure using a Küntcher nail for a periprosthetic supracondylar femoral fracture after revision total knee arthroplasty: A case report

1. Case report 

An 84-year-old female patient who had osteoarthritis of both knees underwent a left total knee arthroplasty (TKA) in our institution in 1982. The implants were removed because of infection in 1988. After the infection subsided, she underwent revision TKA with cement using a revision type Porous Coating Anatomic prosthesis (Howmedica, Rutherford, NJ) in 1990. In 2001, she fell down and sustained a displaced supracondylar femoral fracture of the ipsilateral side adjacent to the femoral implant (Fig. 1). Therefore, the fracture was fixed with a condylar buttress plate (Synthes, Paoli, PA) (Fig. 2). However, despite weightbearing restriction, the patient bore full weight immediately after the operation, and the fracture displaced two months postoperatively. She was conservatively treated using a knee–ankle–foot orthosis and without weight bearing, but finally the screws were broken and the fracture resulted in nonunion (Fig. 3). We treated the nonunion by our originally devised method using a 16 mm-diameter Küntcher nail in 2004. We removed the broken screws and plate used in the previous operation and debrided the nonunion site, and we found both the femoral and tibial components fixed firmly. The proximal end of 16 mm Küntcher nail was cut preoperatively to connect with the stem of the femoral component and a hole made for locking screw at the distal end. The nail was inserted retrogradely from the nonunion site, and then connected to the stem. One locking screw was used to lock the nail. The nonunion was fixed firmly at the operation. An autogenous iliac bone graft was added to promote union.

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Fig. 1. Anteroposterior (A) and lateral (B) radiographs of the supracondylar femoral fracture above the total knee arthroplasty.

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Fig. 2. Anteroposterior (A) and lateral (B) radiographs of the knee after an open reduction and internal fixation with a condylar buttress plate.

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Fig. 3. Anteroposterior (A) and lateral (B) radiographs of the supracondylar femoral nonunion before re-operation. Screw were broken and the fracture site was dislocated.

Low-intensity pulsed ultrasound therapy was additionally performed postoperatively. She began partial weight bearing at 6 weeks postoperatively and progressed to full weight bearing. At final follow up, one and one-half years after the re-operation, the nonunion had healed (Fig. 4), and the patient was able to walk without any support. The range of motion of her left knee was 0–70°, it was the same as preoperation. Her left quadriceps muscle strength was grade 4 with the manual muscle test.

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Fig. 4. Anteroposterior (A) and lateral (B) radiographs 1 year and 5 months after our originally devised treatment. A 16 mm-diameter Küntcher nail fits the stem of the femoral components firmly and the nonunion site successfully healed.

2. Discussion 

Conventional treatments available for periprosthetic femoral fractures without loosening of components include casting, external fixation, plate, flexible intramedullary nail, and retrograde intramedullary nail [1]. For those with loosening of components, the options include revision arthroplasty with a long-stemmed femoral component, a custom-made component, a tumor prosthesis, and an allograft-implant composite [1].

The retrograde intramedullary nail has several advantages compared with plate fixation including decreased operative time, better access to the fracture site without periosteal stripping, minimum disturbance of the fracture hematoma and more rigid fixation [1]. Therefore, some recent reports have recommended retrograde intramedullary nail fixation [2], [3], [4], but some implants such as those with posterior stabilized femoral components with closed housings or long-stemmed femoral components can not accommodate this method [1], [5]. At the time of the patient's first supracondylar femoral fracture, we considered using a retrograde intramedullary nail, but this could not be accommodated by her femoral component, because it had a stem and closed housing. So, the fracture was fixed with a buttress condylar plate.

Treatment options for the nonunion included external fixation, flexible intramedullary nail, revision total knee arthroplasty, and the Less Invasive Stabilization System (LISS) plate fixation. Although external fixation has recently been used successfully [6], [7], [8], we hesitated to place pins close to the femoral component, because a pin infection is common with use of this treatment [1], [5]. A flexible intramedullary nail is the least stable and typically causes shortening and rotational malunion [5], [9]. Revision of the implant with a long stem femoral component was also considered, although x-rays showed osteoporosis and no evidence of loosening of either component. Recently, the LISS plate fixation has been reported, because it secures fixation and allows for minimal fracture site dissection which may reduce intraoperative blood loss and risk of infection [5], [10]. However, it had not been introduced in Japan at this time and so we were unable to use it.

We referred the option to lengthen the femoral stem for treatment of periprosthetic femoral fracture after total hip arthroplasty [11], and found the 16 mm-diameter Küntcher nail, when cut at its proximal end, fits firmly to the stem of the same femoral component of our patient (Fig. 5). During the operation, the nonunion site was fixed firmly by the original method. We were concerned about metallosis caused by the interaction between the different metal components of the stem and the Küntcher nail, but the patient experienced no problems for one and one-half years after the re-operation, and finally bony union was obtained.

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Fig. 5. A 16 mm-diameter Küntcher nail and a stemmed femoral component (A) before and (B) after fitting.

This method may be an appropriate alternative to plate fixation for the treatment of periprosthetic supracondylar nonunion around stemmed total knee femoral components.