|Year : 2020 | Volume
| Issue : 1 | Page : 61-66
Insufficiency fracture of the distal femur during ilizarov treatment for congenital pseudarthrosis of the tibia
Mahmoud A El-Rosasy, Abdullah Ahmed Nada
Department of Orthopedics, Unit of Limb Reconstruction and Pediatric Orthopedics, Tanta School of Medicine, Tanta University, Tanta, Egypt
|Date of Submission||12-Jan-2020|
|Date of Decision||19-Feb-2020|
|Date of Acceptance||16-Mar-2020|
|Date of Web Publication||30-Jun-2020|
Dr. Abdullah Ahmed Nada
Department of Orthopedics, Unit of Limb Reconstruction and Pediatric Orthopedics, Tanta School of Medicine, Tanta University, Tanta
Source of Support: None, Conflict of Interest: None
Background: Patients with congenital pseudarthrosis of the tibia (CPT) usually have significant limb length discrepancy that requires lengthening. In the presence of generalized osteopenia in CPT patients, insufficiency fractures of distal femur can occur during lengthening. No reports in the literature have described this complication and its management. Patients and Methods: We report three cases of CPT with distal femur insufficiency fracture during the treatment by Ilizarov frame. The fracture was minimally displaced. Under general anesthesia, traction and manipulation for fracture reduction were done. A cast was wrapped around the thigh, then three rods were added to the proximal ring to surround the thigh, and then another cast was used to connect the rods and the first cast. Results: In these three cases, healing of the fracture was achieved within 7 weeks without any complications, and the management of CPT continued as planned. Conclusion: The new technique provides a stable construct based on the already mounted frame; thus, healing of the fracture is achieved in a simple, easy, and cheap way with no documented complications.
Keywords: Congenital pseudarthrosis of the tibia, distal femur fracture, Ilizarov lengthening, insufficiency fracture, neurofibromatosis, osteopenia
|How to cite this article:|
El-Rosasy MA, Nada AA. Insufficiency fracture of the distal femur during ilizarov treatment for congenital pseudarthrosis of the tibia. J Limb Lengthen Reconstr 2020;6:61-6
|How to cite this URL:|
El-Rosasy MA, Nada AA. Insufficiency fracture of the distal femur during ilizarov treatment for congenital pseudarthrosis of the tibia. J Limb Lengthen Reconstr [serial online] 2020 [cited 2020 Sep 21];6:61-6. Available from: http://www.jlimblengthrecon.org/text.asp?2020/6/1/61/288559
| Introduction|| |
Congenital pseudarthrosis of the tibia (CPT) is a rare disorder with an incidence of 1 per 140,000 live births. Patients who have CPT are widely reported to have neurofibromatosis-1 (NF-1). In NF-1, there is neurofibromin deficiency which leads to generalized osteopenia. In addition, neurofibromin is required for normal bone development as well as bone regeneration, and thus, delayed healing of fractures in such patients is expected. Moreover, decreased bone mineral density has been observed in as much as 50% of individuals with NF-1.,
Older children with CPT usually have significant limb length discrepancy (LLD) which necessitates leg lengthening after union; for this reason, an Ilizarov frame is usually applied.
The application of Ilizarov frame for distraction osteogenesis can result in an insufficiency fracture of the distal femur. This fracture is both a biological and a mechanical problem. Biological due to disease-related osteopenia is accentuated by the disuse during treatment, while mechanical due to partial stiffness of the knee, weight of the leg with the device on and muscle contracture develops during long segment tibial lengthening.
In this study, we describe the cases of three patients with CPT who developed insufficiency fracture of the distal femur during the treatment by Ilizarov frame. The risk factors for the development of this fracture are presented and analyzed. In addition, a simplified technique is described for the management of such fractures. To the best of our knowledge, no reports in the literature have dealt with this complication and its management plan.
| Patients and Methods|| |
Of 25 cases of CPT treated in our department, five of them needed lengthening due to the presence of significant LLD. We report three cases with distal femur insufficiency fracture during the treatment by Ilizarov frame.
A 12-year-old female child presented with CPT associated with NF-1. She had spontaneous fracture at the age of 2 and was treated by hinged knee brace till the age of 12, when she received the first treatment. Her CPT is categorized as type 1 (according to the El-Rosasy-Paley-classification of CPT [atrophic, mobile, and without previous surgery]). Tibial pseudarthrosis was managed by open excision of the periosteal fibrous hamartoma, wedging of the distal into the proximal bone segment, intramedullary (IM) rod, onlay autogenous iliac crest bone graft, and an Ilizarov frame. Proximal tibial lengthening osteotomy was created to compensate LLD of 12 cm. She sustained a nondisplaced ipsilateral distal femur greenstick after minor trauma during the consolidation phase of the frame, 12 months after treatment initiation. The fracture was flexed (apex anterior angulation) [Figure 1]. At the time of the fracture, she had 9 cm of lengthening at the level of the proximal tibia with good regenerate. The patient has suffered from diabetes mellitus (DM) type 1 during her management. Cessation of lengthening was due to intractable pin-tract infection and DM.
|Figure 1: Fluoroscopic photograph showing the fracture's apex anterior angulation|
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Under general anesthesia, traction and manipulation for fracture reduction were done and were confirmed by intraoperative fluoroscopy. A well-padded cast tube was wrapped around the thigh as high as possible, then 3–4 rods were connected to the proximal ring to surround the thigh medially, laterally, and anteriorly, and then another layer of cast was used to incorporate the rods and connect the rods and the first cast [Figure 2] and [Figure 3].
|Figure 2: Application of the cast tube to the thigh and the rods to the tibial fixator|
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|Figure 3: A layer of cast was used to incorporate the rods and connect the rods to the first cast|
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Anti-edematous (alpha-amylase) and analgesic medications (ibuprofen) were prescribed. Follow-up X-rays were performed at 3 and 6 weeks. No ambulation was allowed until radiographic signs of union were evident (at least three cortices out of four showed bony continuity or a bridging callus).
Healing of the fracture was achieved within 6 weeks without any complications, and the management of CPT continued as planned. After consolidation, physiotherapy was done until a full knee range of motion (ROM) was regained. Nonweight-bearing protocol was followed till radiological union 5 weeks after fixation. Gradual weight-bearing started and was continued for 6 more weeks. After that, the frame was removed, and walking cast application for 4 weeks was done. Finally, a knee-ankle-foot-orthosis (KAFO) was applied [Figure 4], [Figure 5], [Figure 6].
|Figure 4: Preoperative anteroposterior and lateral X-ray views of the fracture in Case 1|
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|Figure 5: Postoperative anteroposterior and lateral X-ray views of the fracture after reduction and fixation by our construct|
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|Figure 6: Anteroposterior and lateral X-ray views of the fracture after removal of the device, showing a proper union with callus formation in an acceptable alignment|
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A 12-year-old boy presented with CPT associated with NF-1. He started his treatment when he was 2 years old. He had six surgeries before presentation to us. His CPT was categorized as type 2 according to the El-Rosasy-Paley classification (atrophic, mobile, and with a history of previous surgery). Tibial pseudarthrosis was managed in the same way as the previous case. He had 6 cm of lengthening at the level of the proximal tibia with good regenerate. Lengthening was stopped when he developed contracture of the knee. He sustained a nondisplaced ipsilateral distal femur greenstick fracture (no history of trauma) during ambulation during the consolidation phase of the frame, 8 months after starting treatment. The fracture was flexed (apex anterior angulation). Management of the fracture was done in the same method as described in Case 1, except that there was a 30°-flexion-deformity of the knee. Under anesthesia, extension of the deformity occurred at the level of the fracture. Thus, the reduction was regained in flexion and the rods were applied to the frame while the knee is flexion to avoid hyperextension and malalignment of the fracture [Figure 7], [Figure 8], [Figure 9].
|Figure 7: Lateral X-ray view of the fracture in Case 2 (with flexion deformity)|
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|Figure 8: Intraoperative clinical photo after application of the construct, in the presence of knee flexion deformity in Case 2|
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|Figure 9: Postoperative lateral X-ray view showing proper alignment and fixation of the fracture in Case 2|
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Healing of the fracture was achieved after 6 weeks without any complications; then, gradual extension of the knee in the frame until full extension was achieved [Figure 10]. Physiotherapy was done until a functional ROM (0°–110° flexion) was regained. During physiotherapy, weight-bearing was allowed. After achieving full extension, the construct was removed and a walking cast was applied for 4 weeks. Finally a KAFO was applied.
|Figure 10: Anteroposterior and lateral X-ray views of the fracture after correction of the knee flexion deformity using the applied frame, while keeping the fracture in a proper alignment and fixation|
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An 11-year-old boy presented with CPT associated with NF-1. He had a history of previous unsuccessful surgery. He started his treatment at our institution when he was 9 years old. His CPT was categorized as type 2 according to El-Rosasy-Paley classification (atrophic, mobile, and with a history of previous surgery). Tibial pseudarthrosis was managed in the same way as the previous cases. Proximal tibial lengthening osteotomy was created to compensate for LLD of 11 cm. He had minor trauma while ambulatory during the consolidation phase of the frame, 11 months after Ilizarov frame application. He sustained a nondisplaced ipsilateral distal femur greenstick fracture. The fracture was flexed (apex anterior angulation) [Table 1].
Healing of the fracture was achieved within 6 weeks without any complication; the same postoperative protocol, as in Case 1, was followed.
| Discussion|| |
CPT is considered as one of the most challenging orthopedic problems. This is due to difficulty in achieving and maintaining the union. The condition is usually associated with NF-1. In patients with NF, generalized osteopenia is usually present because of neurofibromin deficiency, which can increase the risk of fractures.
Several treatment protocols have been described for the management of CPT with variable success rates.,, However, the two basic principles are usually the same: One of them is optimizing the biological environment by excision of the diseased periosteum and addition of bone graft, either osteoperiosteal graft, massive onlay graft, autogenous iliac crest bone graft, or vascularized bone graft. The other basic principle is the mechanical stability, which can be achieved by IM rods, an Ilizarov frame, or a combination of both.,,
Our preferred method of fixation is to use an Ilizarov external fixator augmented by an IM rod. The Ilizarov external fixator facilitates fixation of small bone fragments and simultaneous compression of pseudarthrosis, gradual correction of deformities, and LLD correction by distraction osteogenesis. LLD is a nearly consistent finding particularly in older children.,,
Of 25 cases treated in out institution, only five cases needed concomitant lengthening during treatment, and three of them had distal femur fracture, which was mainly due to their older age and the presence of significant LLD. In younger children, we accept up to 3 cm LLD, compensated by ipsilateral femoral overgrowth, which is stimulated by walking on a short leg.
The application of Ilizarov frame for distraction–compression results in gastrocnemius muscle tightness and knee flexion contracture, particularly when tibial lengthening exceeds 13%–25% of the original tibial length., The prolonged application of Ilizarov external fixator along with the lack of weight-bearing would accentuate regional osteopenia of the affected limb. In addition, knee stiffness may complicate the lengthening process. Thus, the combination of these factors will put much stress on the nearby osteopenic distal femur at the metaphyseo-diaphyseal junction, resulting in insufficiency fracture.
Problems with the management of these fractures are: The level of the fracture does not allow any safe and stable method of fixation. Moreover, the soft femoral bone would not hold extension of the external fixator on the femur. Furthermore, extension of the frame on the femur will leave pin site holes as stress risers with the risk of femoral fracture after fixator removal.
In the first case in this study, the percentage of lengthening was 42%, which is much higher than the recommended percentage for safe lengthening which is less than 25%., Despite achievable, it came at a high cost in the form of risk of insufficiency fracture and prolonged fixator time. This cost has to be weighed against the benefits of a single treatment event and should be discussed in details with the child's parents or caregivers. In the view of the above, it is important that the treating surgeon should resist the temptation to push the limits by going further in bone lengthening taking the risk of prolonged treatment time and has to dampen the enthusiasm of the patient's family to do so. Staged lengthening can be considered as a safe solution.
There are several points to consider in CPT patient with NF-1. First, those patients have higher bone healing index than normal subjects and are expected to have prolonged fixator time. Second, healing of CPT is of prime importance, and one should consider safe limb lengthening in the range of 5 cm, based on our experience in the treatment of CPT cases. Thus, it could be wise to advice the patient to use his limb with shoe lift to correct the residual LLD. Then, when the bone quality improves, a second limb lengthening only procedure could be performed while the healed CPT is protected by the previously retained IM rod.
| Conclusion|| |
The proposed technique provides a stable construct based on the already mounted frame; thus, healing of the fracture is achieved in a simple and cost-effective way with no documented complications.
Written, informed consent was obtained from all the patients authorizing the treatment, radiological and photographic documentation. They were informed and consented that the data would be submitted for publication.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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