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Oct 26, 2023

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A healthy 36-year-old man presented to the ED with a 2-week history of draining

A healthy 36-year-old man presented to the ED with a 2-week history of draining wounds from the right thigh.

He sustained an open right femur shaft fracture 2 years prior following a motorcycle accident while living in the Dominican Republic. He was initially treated with an irrigation and debridement and right femur intramedullary nail. The following year, he underwent an additional unknown revision surgery.

Upon initial presentation to our institution, he complained of distal thigh pain, which was worse with weight-bearing along with limitations in knee range of motion as a secondary complaint. The patient had an incision to his lateral thigh that extended the length of his femur, with two sites of active drainage (Figure 1). His knee range of motion was limited to 0° to 45° and he was neurovascularly intact distally. Clinically, his right leg appeared approximately 3 cm shorter than his left. Initial inflammatory markers demonstrated an elevated erythrocyte sedimentation rate of 7 and C-reactive protein of 2.8.

The patient was suspected of having an infected nonunion of his femur. He was taken to the OR for hardware removal, irrigation and debridement, and hypertrophic bone resection with the placement of an intramedullary nail and antibiotic beads (Figure 2A).

Intraoperative biopsy and cultures were taken, which showed methicillin-sensitive Staphylococcus aureus and extended-spectrum beta-lactamase Klebsiella pneumoniae. IV meropenem and ertapenem were administered for 6 weeks. After a 2-week antibiotic holiday, his inflammatory markers had normalized. To ensure eradication of infection, an additional open biopsy was performed. The biopsy resulted in no infectious organisms on culture.

After his open biopsy and cultures confirmed eradication of the infection, a CT scanogram was performed to evaluate and quantify the right lower extremity leg length inequality. The patient was found to have a 3.5-cm limb length discrepancy as a result of his previous surgeries (Figure 2B).

See answer below.

Our goal was to address his leg length discrepancy and ultimately achieve femoral osseous union in acceptable alignment. After considering various treatment modalities, plate-assisted bone transport with use of a magnetic internal limb lengthening nail was utilized. In this case, the Precice magnetic expansile intramedullary nail (NuVasive) and plating (Synthes) were utilized.

Initially, the patient was taken to the OR where the previously placed intramedullary nail was removed and an additional 8-cm resection was performed due to residual nonviable bone (Figure 3A). To address the now 11.5-cm bone loss (3.5-cm leg length discrepancy plus 8-cm resection), an osteotomy was made in the subtrochanteric region of the femur to create a mid-transport segment to be transported with the Precice magnetic intramedullary nail (Figure 3B). Flat osteotomies were made at the distal aspect of the transport segment and the proximal portion of the distal segment to parallel the knee joint and to allow improved surface contact once docked. The nail was then placed antegrade in the proximal femur (segment 1) and locked to the middle transport segment (segment 2). A 4.5-mm plate was contoured and applied anteriorly with bicortical screws fixing the proximal segment (segment 1) to the distal femur (segment 3) to guide the transport segment and help maintain femoral alignment. Local absorbable calcium sulfate antibiotic beads were placed prophylactically, given his history of infection (Figure 3D). The magnetic lengthening was then started on postoperative day 7 at a rate of 0.75 mm per day.

Once the nail was maximally lengthened by 8 cm, the patient was returned to the OR to "reset" or reverse the nail length to allow for continued femoral lengthening.

A month after resetting the nail, the transport segment (segment 2) was now in contact with the distal segment (segment 3) and considered "docked" (filling the 8-cm resection). To address the remaining 3.5-cm limb length discrepancy, a subsequent surgery was undertaken during which the transport segment and distal segment were fixed to each other with bicortical screws through the femoral plate. The screws through the proximal segment plate (segment 1) were removed and the bone lengthened for the final 3.5-cm deficit (Figure 4A). Two months later, after completion of the lengthening process, a CT scanogram confirmed equal leg lengths (Figure 4B).

Next, as part of his planned staged procedure, screws in the plate were transitioned to unicortical in all segments to maintain length; the magnetic intramedullary nail was removed and an antegrade locked femoral nail spanning all segments was placed. The unicortical screws in the proximal segment were removed, and the proximal portion of the femoral plate was cut and removed. Medial heterotopic ossification at the docking site was also resected during this procedure (Figure 5A). During the next several months, serial imaging continued to demonstrate interval healing at all segments and appropriate alignment.

Approximately 18 months after his last procedure, the patient still had significantly limited right knee range of motion of 0° to 50°, similar to his initial presentation. At this point, he returned to the OR for a final surgery where he underwent formal Judet quadricepsplasty with removal of the remaining femoral plate. All hypertrophic scar tissue and intraarticular adhesions were excised, and a medial release was performed (Figure 5B).

His knee range of motion significantly improved from 0° to 115° of flexion 4 months following his final procedure, and he was walking pain free without any assistive devices. Radiographs at this visit demonstrated continued union, no hardware complications and acceptable limb alignment with excellent patient-reported outcomes (Figure 6).

Infectious nonunion of the femur is a rare yet devastating complication that can cause significant morbidity and functional impairment. It is typically caused by bacterial contamination of the fracture site, leading to impaired healing. The incidence of infectious nonunion is reported to be between 0.7% and 15% in patients with femur fractures. Open fractures have a higher risk of infectious nonunion, with rates reported to be three to 10 times higher than those of closed fractures. The treatment goals for infectious nonunion include eradication of infection, addressing bone loss or restoration of anatomy and achieving osseous union, which often requires a multidisciplinary approach.

In this case, the patient had a complicated history. The first step involved eradicating the infection, as outlined above. The Infectious Disease Society of America recommends that antibiotics be chosen based on culture and sensitivity results and that treatment should continue until clinical and laboratory parameters have normalized, as was done in this case.

Modern treatment options for femoral bone loss include structural autograft/allografts, vascularized bone grafts, induced membrane technique (Masquelet), bone transport with Ilizarov tension wire frame and bone transport with magnetic rods. Selecting the optimal treatment modality to address femoral bone loss requires an in-depth understanding of the options and critically analyzing the host.

Structural autografts/allografts are primarily used for smaller bone defects. Certain structural autografts, such as vascularized free fibula grafts, have shown promise in larger deficits. However, vascularized bone grafts are typically considered when metabolic, mechanical, environmental and host factors jeopardize union.

Alternatively, bone transport with Ilizarov tension fine wire frame has a proven track record in correcting limb length discrepancies, angular deformities and segmental defects of long bones since the 1960s. Unfortunately, Ilizarov fine wire frames are associated with a technical learning curve and are associated with high complication rates. A retrospective series of 50 patients treated with radical debridement and distraction osteogenesis of infected femoral nonunions found a 100% complication rate. All 50 patients studied had pin-tract infections, and statistically significant decreases in knee range of motion were noted in this cohort. One patient required hip disarticulation secondary to sepsis. Other complications included loosening of wires or pins, deep infection, external thigh compression from an excessively tight-fitting ring, equinus deformity, deep veinous thrombosis and bleeding. Patient compliance with treatment protocol and limitations in speed of lengthening can make this technique suboptimal for large defects, especially in a patient with preexisting knee stiffness.

In the past few decades, the use of the induced membranous technique (Masquelet) for osseous defects has gained traction. The induced membrane technique is a two-stage surgical procedure used to treat bone loss. The first stage involves the implantation of a bone cement spacer, which induces the formation of a membrane around it, followed by the removal of the spacer and replacement with a bone graft in the second stage.

A meta-analysis of 13 studies involving a total of 711 cases compared the clinical outcomes of the Masquelet technique (342 patients) and the Ilizarov bone transport method (369 patients) for the treatment of infected bone defects in the lower extremities. Results showed a statistically significant difference in favor of the Masquelet technique in terms of hospitalization costs, final union time, time to full weight bearing, quality of life and the risk of complications. However, the Masquelet technique has some limitations, such as the bone cement spacer used in the first stage that can cause discomfort, and there are reports of an increased risk of infection. Additionally, the bone graft may not integrate correctly, leading to failure of the lengthening process.

More recently, the use of magnetic rods, with or without external frames, has been deployed to address femoral bone loss. The procedure involves implanting a magnetic rod into the femur, which is then lengthened using an external magnetic device. The magnetic force stimulates bone growth, resulting in lengthening of the bone over time. The intramedullary rod can be guided to correct angular deformity/maintain alignment with external spatial frames. However, these frames are associated with pin tract infections, similar to the Ilizarov frames cohorts. The use of plate fixation with magnetic rods eliminates the risk of pin site infections while still providing limb alignment benefits.

A level 2 study involving a systematic review and meta-analysis compared the effectiveness of motorized internal limb lengthening with alternative techniques. The study included 143 limbs lengthened through the motorized internal limb lengthening technique and 98 limbs lengthened through other techniques described above. The analysis found the motorized internal limb lengthening cohort had significantly fewer complications compared with the alternative technique cohort. Across all studies, both deep and superficial infectious complications were less common with motorized internal limb lengthening procedures. Based on their findings, the authors concluded that motorized internal limb lengthening techniques are likely to be the preferred method for limb lengthening in the future due to superior outcomes and fewer complications.

Overall, the management of infected nonunion of the femur requires a multidisciplinary approach that incorporates surgical debridement, antibiotic therapy and bone grafting or transport. It is a complex and challenging condition that can result in significant morbidity and functional impairment. However, with appropriate planning and management, successful outcomes can be achieved, as highlighted in this case.