Femoral Neck Fracture in Adult and Avascular Necrosis and Nonunion
Condition: Femoral Neck Fractures; Avascular Necrosis
MeSH terms: Osteonecrosis; Necrosis; Fractures, Bone; Femoral Neck Fractures
Study type: Observational

Summary: 
      One of the most serious sequelae of femoral neck fractures (FNFs) is avascular necrosis (AVN)
      and nonunion, and this translates to a significant morbidity and mortality. This study was
      conducted to determine the relationship between the etiologies and management of FNFs in our
      institution and its relationship to the development of AVN or nonunion.
    

Detailed description: 
      Femoral neck fractures (FNFs) are fractures of the flattened pyramidal bone connecting the
      femoral head and the femoral shaft. It is not so common in healthy individuals but common
      among athletes, military recruits, and young adults because of high energy cases such as
      sports and road traffic accidents, in adults due to falls, in women with estrogen imbalances,
      and in patients with bone mineralization and deficiencies.

      In the USA in 2013, there were a reported 146 cases per 100,000 population. Mortality can be
      high as much as 30% at one year particularly if there is delaying management over 24 hours.

      FNFs are classified using the Garden Classification based on anteroposterior radiographs into
      Types I to IV wherein Type I is incomplete fracture, Type II is complete but non-displaced
      fracture, Type III is complete and partially displaced fracture and Type IV is complete and
      fully displaced femur. Another classification is the Pauwel's classification which is a
      biomechanical classification based on the vertical orientation of the fracture line, and is
      commonly used to determine the appropriate treatment for FNFs particularly among younger
      adults.

      The radiographic union score for hip (RUSH) is a scoring used to describe healing of femoral
      neck fractures, particularly among patients who might require additional surgery, in which
      patients with a 6-month RUSH score <18 have a greater probability of undergoing reoperation.

      Surgical management of FNFs include open reduction and internal fixation (ORIF) which has
      some fixation failures, primary total hip arthroplasty (TA) which is cost-effective for
      displaced FNFs in patients 45-65 years old, cannulated screw (CS) fixation for the young and
      middle-aged patients, dynamic hip screw fixation (DHS), and hemiarthroplasty. The decision to
      use either of the surgical management depends on several factors including displacement of
      the femoral neck, presence of hip joint arthritis, age, and other factors. Around 24% of
      patients who had THA underwent revision within 5 years because of aseptic loosening,
      infection and many other causes. Some surgeons however prefer ORIF and some prefer THA for
      displaced FNFs particularly among active older patients with Garden III fracture.

      One of the most serious sequelae of FNFs is avascular necrosis (AVN) which occurs in 10-45%
      of patients with FNFs, particularly those who have displaced and nonunion FNFs. Nonunion
      occurs in almost 20% of FNFs, more common in men than women, and common with increasing age.
      Around 33% of displaced FNFs are associated with complications. One study showed that age and
      the type of fixation are not significantly correlated to the incidence of AVN, but the amount
      of vascular damage at the time of the fracture determines the development of vascular
      necrosis. On the other hand, a separate study showed that the fracture type and age are the
      most significant predictors of the development of AVN.

      It has been mentioned that time is essential in the management of FNFs particularly in the
      development of AVN. One study showed that the rates of AVN increases over time when patients
      underwent surgery before 12 hours had elapsed and after 12 hours from 12.5% to 14.0%, while
      another study showed that a delay of more than 48 hours before surgery did not influence the
      rate of union or the development of AVN when compared with operation within 48 hours of
      injury. Some studies reported that bleeding from the holes of cannulated screws predict the
      development of AVN, some due to damage to the blood supply of the femoral head brought about
      by the initial high energy trauma, and some due to the extent of fracture displacement. Other
      studies have suggested that FNFs treated using cannulated screws particularly among
      middle-aged and elderly patients have less incidence of AVN. Because of these, we undertook
      this study to determine the relationship between the etiologies and management of FNFs in our
      institution and its relationship to the development of AVN or nonunion.
    

Intervention name(s): dynamic hip screw (DHS) and cannulated screw (CS)
Intervention type(s): Procedure
Intervention description(s): A preformed case report form was used to collect the data which included the demographic profile of the patients (age, gender), comorbidities, smoking history, mode of injury (high or low energy), presence of multiple trauma, garden classification, side of injury, time to fixation (in hours), type of reduction, type of implant used, RUSH score (healing), start of weight bearing, development of AVN, and final outcome (whether varus, valgus, displaced or healed).
Other intervention name(s): Time to fixation
Observational model: Cohort
Time perspective: Retrospective
Sampling method: Non-Probability Sample
Study population: 
        -  All adult patients aged 18 years old to 70 years old admitted and managed for Femur
             Neck Fracture during the last 10 years (2007 - 2017) at Security Forces Hospital,
             Riyadh, Saudi Arabia.

          -  Fresh trauma case including all patients admitted within 24 hours of the injury.

          -  Referred cases including patients referred from other hospitals and patients came from
             the war zone without time limitation.
      
Keywords: Adult; avascular necrosis; Complications; Delayed fixation; nonunion; Surgical timing; Pauwels