Traumatic simultaneous bilateral femoral neck fracture in a child : A case report

Patrick Wendpouiré Hamed Dakouré, MD FWCS Associate Professor in Orthopaedics and Trauma at the University Hospital of Bobo-Dioulasso (Burkina Faso) Malick Diallo, MD Lecturer in Orthopaedics and Trauma Surgery at the University Hospital of Bobo-Dioulasso (Burkina Faso) Antonio Martinez Puente, MD Orthopaedic Surgeon Souleymane Ouédraogo, MD Junior Resident Massadiami Soulama, MD Orthopaedic Surgeon


Introduction
A traumatic fracture of the femoral neck in children is a rare occurrence, comprising less than 1% of all paediatric fractures. 1][4][5][6][7][8][9][10] Usually, a high energy trauma is involved, such as a fall from a height and motor vehicle accident. 1,4,6,8,11e report the case of a 9-year-old schoolgirl who presented with traumatic bilateral fractures of the femoral neck after a fall from a height.Primary skin traction and secondary closed reduction with percutaneous cannulated screws fixation (PCSF) was performed.The girl recovered completely in seven months.Anatomical characteristics, mechanism of injury and late surgical management are discussed.
On admission, the patient laid in supination with the two lower limbs externally rotated.She complained of severe pain in the groin area and could not move her hips.Distally, the neurovascular status was normal.The AP pelvic radiograph showed a displaced transcervical fracture of the right femoral neck and an intertrochanteric fracture of the left femoral neck, classified as Delbet type III and IV respectively (Figure 1).
Skin traction was first applied.On the seventeenth day, under general anaesthesia, closed reduction was performed by traction and internal rotation.Fluoroscopicguided percutaneous partially threaded cannulated screws with washers were used as internal fixation.A double plaster spica was applied immediately after surgery.The reduction was perfect on the left side with a measured cervicodiaphyseal angle (CDA) of 130 degrees.On the right side, the reduction was acceptable with a CDA of 128 degrees (Figure 2).The delay was due to our hospital's lack of materials, and the screws were the best we had available at the time of surgery.The post-operative period was uneventful.No post-operative rehabilitation was performed.The surgical wounds were healed in ten days, the spica was removed after a month and partial weight-bearing with crutches was allowed after seven weeks.Ten weeks after surgery, the hips were pain-free and she was able to walk without crutches.Follow-up pelvic radiographs showed signs of union at seven weeks, consolidation at seven months and signs of bone remodelling at 14 months.Screws were removed at seven months.There was no radiographic sign of femoral head necrosis or osteoarthritis but a shortened femoral neck and overgrowth of the greater trochanter was present on the left side (Figure 3).At 28 months, there was no lower limb shortening and the range of motion of both hip joints was: 120° for flexion, 15° for extension, 60° for abduction, 45° for adduction, 45° for external rotation and 30° for internal rotation (Figure 4).Finally the patient returned in school.

Discussion
A traumatic bilateral fracture of the femoral neck in children is an unusual injury.][4][5][6][7][8][9][10] In polytrauma cases, it is important to check the hips to avoid a delayed diagnosis. 6he average age at time of trauma was seven years (range 4-11) and the male to female ratio was 1:1.2.

Anatomical characteristics
Cervicotrochanteric and transcervical fractures are more frequently reported in the cases published in the literature 2-7,9-11 (Table I).

Mechanism of injury
A traumatic fracture occurs as a result of a particular position of the limb, and a precise point of impact to produce the injury.In reported cases of traumatic bilateral fracture of femoral neck, three main kinds of mechanisms were hypothesised: a direct 'one-injury fracture', 2 an indirect 'two-injury fracture', 4,6,9 and an indirect axial load fracture: 10 • In the one-injury fractures, the mechanism is a lateral compression (LC) on a fixed pelvis.This mechanism seems similar to the LC type of the Young-Burgess System Classification. 12• In the two-injury fractures or 'abduction-adduction fractures', the first indirect impact occurs on the medial side of the thigh with the leg forced in abduction and external rotation, and the second direct impact occurs on the hip lateral side with the leg in adduction and internal rotation.• In the axial load fractures, the force is transmitted from feet to flexed hips, through extended knees.
We are of the opinion that the mechanism in our case was that of a two-injury fracture type.

Injury management
The management of displaced femoral neck fractures is surgical by reduction and internal fixation. 1,7The closed reduction with PCSF followed by a spica plaster for seven weeks (4-16) gave best results in bilateral femoral neck fractures. 3,4,6,7According to Dhār, 3 early surgery was necessary for a good outcome.Good results, however, were also observed with delayed surgery from two to 77 days with or without skin traction mainly by open reduction 5,6,9,10 (Table I).Our 17-day delay explains the non-anatomic reduction at the right hip.We think that primary skin traction is important for pain management.
[5]7,10 It secures the internal fixation for eight weeks on average (range 4-16) without any secondary hip stiffness.The weight bearing time is linked to radiographic signs of bone union.5][6] The mean time of bone consolidation was 24 weeks in the literature described (range 12-52) (Table I).
Reported complications of surgical management are avascular necrosis of the femoral head, osteoarthritis, premature closure of the proximal femoral epiphysis, varus or valgus deformity, 7,10 shortening of the femoral neck and overgrowth of the greater trochanter. 10A non-perfect reduction of a transcervical fracture (Delbet type III) may lead to shortening of the femoral neck and overgrowth of the greater trochanter.The current case shows AVN and coxa vara on the right side with no complications on the left side.According to Togrul et al., 8 AVN is more frequent in bilateral hip fractures.The literature review found only one other case of AVN and varus deformity on a Delbet type III fracture 7 (Table I).We think that a longer follow-up time and the use of MRI would be useful to evaluate the true rate of AVN.A non-perfect anatomic reduction of a Delbet type III fracture led to an earlier physeal closure with overgrowth of the greater trochanter and varus/valgus deformity. 7,10

Conclusion
The authors reported a first case of bilateral hip fracture in a child with a Delbet III and a Delbet type IV fracture.The mechanism of injury of the current case confirms the twoinjury theory.A significant delay to surgery did not result in an adverse clinical result.However, a better outcome is observed with an earlier and perfectly closed reduction and a PCSF.
, F: Female, h: Hours, d: Days, w: Weeks, m: Months, y: Years, R: Right L: Left FFH: Fall from height, MVA: Motor vehicle accident CRIF: Closed reduction and internal fixation, ORIF: Open reduction and internal fixation, DHS: Dynamic hip screw GT: Greater trochanter Saied et al. 2 reported one case of associated transepiphyseal fracture (Delbet type I).No such case of associated intertrochanteric fracture was previously reported with another contralateral proximal femur fracture.