Late fracture of the hip after reamed intramedullary nailing of the femur

Surgical strategy of the treatment of atypical femoral fractures

The atypical femoral fracture (AFF) has been attracting significant attention because of its increasing incidence; additionally, its treatment is challenging from biological and mechanical aspects. Although surgery is often required to manage complete AFFs, clear guidelines for the surgical treatment of AFFs are currently sparse. We reviewed and described the surgical treatment of AFFs and the surveillance of the contralateral femur. For complete AFFs, cephalomedullary intramedullary nailing spanning the entire length of the femur can be used. Various surgical techniques to overcome the femoral bowing common in AFFs include a lateral entry point, external rotation of the nail, and the use of a nail with a small radius of curvature, or a contralateral nail. In the case of a narrow medullary canal, severe femoral bowing, or pre-existing implants, plate fixation may be considered as an alternative. For incomplete AFFs, prophylactic fixation depends on several risk factors, such as a subtrochanteric location, presence of a radiolucent line, functional pain, and condition of the contralateral femur; the same surgical principles as those in complete AFFs can be applied. Finally, once AFF is diagnosed, clinicians should recognize the increased risk of contralateral AFFs, and close surveillance of the contralateral femur is recommended.

Are piriformis reconstruction implants ideal for prophylactic femoral neck fixation?

OBJECTIVES

Prophylactic femoral neck fixation may be performed in the setting of geriatric diaphyseal femur fracture, pathologic or impending atypical femur fractures. Fixation constructs often utilize cephalomedullary implants with one or two proximal interlocking screws into the femoral head/neck. Variations in proximal femoral anatomy and implant design can interfere with the placement of two screws in the femoral head and neck. Our objective was to assess the strength of piriformis entry reconstruction implants with one versus two proximal interlock screws for prophylactic femoral neck fixation.

METHODS

Thirty fourth generation synthetic femur models were separated into 5 groups. The control group was an intact femur, and the second group was an intact femur with an entry hole in the piriformis fossa. The remaining groups had an intramedullary nail placed with either 0, 1, or 2 screws placed into the femoral head and neck. Each femur was mechanically loaded along the mechanical axis through the femoral head. Load to failure and failure displacement were recorded.

RESULTS

Mean load to failure was 5583 ± 543 N in the intact femur. Constructs with 2 screws had a significantly higher mean load to failure (3223 ± 474 N) compared to one screw constructs (2368 ± 280 N). All of the experimental groups remained significantly lower than the intact femur model (p < 0.05).

CONCLUSION

Our results demonstrate that piriformis entry reconstruction implants have a significantly lower load to failure compared to an intact femur irrespective of screw construct. Further studies are needed to investigate this potential iatrogenic weakening.

Management pitfalls of fractured neck of femur in osteogenesis imperfecta

INTRODUCTION

Fractured neck of femur in osteogenesis imperfecta is rarely reported. Its management is always difficult because of bone fragility and the outcome is not well known. We, therefore, aimed to study the management pitfalls in this group of patients.

METHODS

We retrospectively reviewed five cases of fractured neck of femur in four patients treated in our hospital between 2006 and 2009. The demographic data, mode of injury, fracture configuration, treatment, complications, clinical and radiological outcome were reviewed.

RESULTS

According to the Sillence classification, one patient was type I, two were type III and one was type IV. There were two children (aged 8 and 15 years) and two adults (aged 21 and 22 years), with the 8 year-old girl suffering from hip fracture on different sides in two accidents. All five hip fractures were the result of low-energy injury and were associated with other fractures. Two undisplaced fractures required intra-operative fluoroscopic confirmation to demonstrate movement at the fracture site. The interval between the injury and fixation ranged from 6 h to 3 days. One hip required secondary surgery to openly reduce the fracture due to inadequate primary fixation and reduction. Two hips were fixed with paediatric dynamic hip screws and three hips were fixed with cannulated screws. All patients were immobilised in hip spica for 6 weeks. The average follow-up was 4 years (3-5 years). All patients had satisfactory union and none of them developed radiological evidence of avascular necrosis at the latest follow-up. All patients returned to their pre-injury functional level.

CONCLUSION

Fractured neck of femur is rare given the high prevalence of long bone fractures in osteogenesis imperfecta. They all have characteristic associated fractures of the extremity at the time of injury and neck of femur fractures could be easily missed. Fracture fixation is a great challenge to the orthopaedic surgeons because of the small size of the patients, poor bone quality with suboptimal imaging intra-operatively and compromised purchase of fixation devices. The choice of implants should be determined by the size of the patients and the presence of prior instrumentation close to the hip joint.