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| CASE REPORT |
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| Year : 2021 | Volume
: 7
| Issue : 2 | Page : 142-144 |
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Limb lengthening of a rare case of congenital femoral deficiency with an unstable knee
Ricardo Marta1, Armando Campos2, António Oliveira3, João Carvalho4
1 Department of Orthopaedic, Hospital da Senhora da Oliveira, Guimarães, Portugal
2 Department of Orthopaedic, Centro Hospitalar Universitário do Porto, Porto, Portugal
3 Department of Orthopaedic, Centro Hospitalar Universitário do Porto; Instituto de Ciências Biomédicas Abel Salazar, Porto, Portugal
4 Department of Orthopaedic, Centro Hospitalar Tâmega e Sousa, Penafiel, Portugal
| Date of Submission | 01-Aug-2021 |
| Date of Decision | 11-Sep-2021 |
| Date of Acceptance | 18-Nov-2021 |
| Date of Web Publication | 30-Dec-2021 |
Correspondence Address:
Dr. Ricardo Marta
Hospital da Senhora da Oliveira, Guimarães
Portugal
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/jllr.jllr_23_21
Congenital femoral deficiency (CFD) is a rare birth defect that is characterized by a short femur, associated with hip and knee deformity, deficiency, or instability. Children with severe CFD may need multiple deformity correction or lengthening procedures to reduce axial malalignment and limb length discrepancy (LLD). During limb lengthening, it can occur knee subluxation or dislocation, a severe treatment-related complication. We report a 15-year-old girl with a CFD with a previous episode of posterior subluxation of the knee during a femoral lengthening using a monolateral external fixator. She had a 13 cm LLD and coxa vara; therefore, it was applied a knee spanning Ilizarov fixator with a double osteotomy of the femur for gradual correction. At 11 months following Ilizarov application, a complete correction was achieved, and the circular fixator was removed. Knee joints of patients with CFD show highly variable grades of instability. Adequate surgical techniques, preventive measures, and early detection of signs of subluxation can lead to good functional results. Femur lengthening with a preventive bridging of the knee with an Ilizarov frame is a safe and effective way of treating patients with CFD.
Keywords: Circular external fixation, congenital femoral deficiency, Ilizarov, knee instability, knee subluxation, limb lengthening
How to cite this article:
Marta R, Campos A, Oliveira A, Carvalho J. Limb lengthening of a rare case of congenital femoral deficiency with an unstable knee. J Limb Lengthen Reconstr 2021;7:142-4 |
| Introduction | |  |
Congenital femoral deficiency (CFD) is a rare and complex condition that is frequently associated with other congenital anomalies. CFD may be associated with bowing of the shaft, pseudoarthrosis of the femoral neck, coxa vara, acetabular dysplasia, hypoplasia at the femoral condyle, genu valgum, hypoplastic patella, and absence of the cruciate ligaments.[1] There are variable degrees of severity of dysplasia of the femur.[2],[3] Limb lengthening is an appropriate option when there are mobile hip and knee joints.[4],[5],[6] Children with severe CFD may need multiple deformity correction or lengthening procedures during growth to reduce axial malalignment and leg length discrepancy. Various methods such as monolateral fixators, circular hexapod/Ilizarov fixators, and intramedullary lengthening nails have been developed. During limb lengthening, knee instability due to articular and soft-tissue deficiencies can result in knee subluxation and dislocation, a severe treatment-related complication.[1],[4],[7],[8]
| Case Report | | |
A 15-year-old girl presented in 2019 with a shortening of the left limb. On examination, the left femur was short with a full range of movement of ipsilateral hip and knee. There was no history of hip dislocation, and grade 1 laxity was present on Lachman and Drawer tests. On teleroentgenogram of lower limbs, the left femur was shortened by 13 cm as compared to the right without any discrepancy of length in the leg compartment [Figure 1]. There was no other obvious congenital abnormality found in the radiograph. Diagnosis of Congenital Femoral Deficiency was established.[3] When she was 6 years old, it was carried a femoral lengthening with a mid-diaphyseal monofocal osteotomy using a monolateral external fixator. After 2 months of lengthening, a posterior subluxation of the knee was noted, so she removed the monolateral fixator [Figure 2]. Over the next few years, she presented several complications, namely fracture at the osteotomy site, failure of plate osteosynthesis and infection [Figure 3]. Eleven years later, she arrived at our hospital, and it was decided to make another attempt to correct the limb-length discrepancy and the femur deformity. We applied a knee spanning Ilizarov's ring for gradual correction. After 7 days of latent period, lengthening was started at the rate of 1 mm per day with 13 cm of length gained at 3 months [Figure 4]. The patient was allowed partial weight-bearing and walking with crutches during this period. The patient was also advised to do a range of motion (ROM) exercise of the hip. Femoral lengthening requires close follow-up and intensive rehabilitation in order to identify problems and maintain a functional extremity, respectively. Follow-up was every 2 weeks for radiographic and clinical assessment. Clinically, the patient was assessed for hip ROM, knee subluxation, nerve function, and pin sites. Radiographically, the distraction gap length, regenerate bone quality, limb alignment, and joint location were assessed. | Figure 1: Preoperative radiograph showing a 15-year-old girl with congenital femoral deficiency
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 | Figure 2: Posterior subluxation of the knee during a femoral lengthening using a monolateral external fixator when she was 6-years-old
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 | Figure 3: Complications following the removal of monolateral external fixator
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 | Figure 4: Anteroposterior radiograph at 3 months following Ilizarov application
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| Results | | |
At 11 months following Ilizarov application, a complete correction was achieved, with both limbs of the same size and an improvement of the axial alignment of the left limb [Figure 5]. At this time, the circular fixator was removed. She is very satisfied with the surgery results, presenting a visual analog scale score 1 and a stable and pain-free lower limb, walking without external support. She has no clinical or analytical inflammatory signs.
| Discussion | | |
Almost all CFD can be assumed to have hypoplastic or absent cruciate ligaments with mild to moderate anteroposterior instability. Some also have mediolateral and torsional instability. Despite this, in most cases, the knee tracks normally preoperatively, and there is no need to perform a ligamentous reconstruction. Knee subluxation with lengthening is usually posterior and occurs due to conflict of force vectors at the hip and knee during lengthening. The dislocating forces are exerted by the tight periarticular tissues, mainly the iliotibial tract, which works against the anatomical bony deficiencies and, with its biarticular attachment, can cause knee dislocation.[9] Grill and Dungl reported on 37 patients with CFD, who were treated with femoral lengthening with the Ilizarov frame or monolateral lengthening device.[10] Complications and knee subluxation occurred in 21%. In order to prevent subluxation during lengthening, the knee joint should be bridged by the external fixator. The safest way of lengthening is, therefore, the preventive bridging of the knee with a circular frame. An accurately placed hinge at the center of rotation of the knee between the femoral and tibial frame allows safe lengthening and enables controlled mobilization of the knee joint. Monolateral fixators might give less stability, but with an adequate technique, the knee can be bridged as well. As mild knee subluxation can easily go unrecognized on X-rays, clinical examination and accurate radiographic analysis during bone lengthening are important to detect signs of subluxation of adjacent joints as early as possible. Consequences of subluxation and residual knee flexion deformity can be severe with functional leg length discrepancy, anterior knee pain, and inability to weight bear due to knee instability. Hence, before performing femoral lengthening in CFD, a complete assessment of the risk factors is necessary to avoid knee dislocation. The surgeon should maintain a high index of suspicion and be alert to recognize the symptoms and signs which indicate subluxation during lengthening.
| Conclusion | | |
Knee joints of patients with CFD show highly variable grades of instability. Adequate surgical techniques, preventive measures, and early detection of signs of the subluxation can lead to good functional results in patients with CFD. Femur lengthening with a preventive bridging of the knee with an Ilizarov frame is safe and effective.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient (s) has/have given his/her/their consent for his/her/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
Nil.
Conflicts of interest
There are no conflicts of interest.
| References | | |
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| 9. | Fairclough J, Hayashi K, Toumi H, Lyons K, Bydder G, Phillips N, et al. The functional anatomy of the iliotibial band during flexion and extension of the knee: Implications for understanding iliotibial band syndrome. J Anat 2006;208:309-16. |
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
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