To The Editor:
We read with interest the article "Comparison of Early and Delayed
Fixation of Subcapital Hip Fractures in Patients Sixty Years of Age or
Less" (2002;84:1605-12), by Jain et al. We are concerned by their
decision to use twelve hours postinjury as the cutoff between early and
delayed treatment. Scientific and clinical work points to a cutoff of six
hours postinjury for fixation of intracapsular fractures of the femoral neck
in younger patients.
In a study of the effects of occlusion of the blood supply to the femoral
head in a group of dogs, Woodhouse1 found that, with six hours of
anoxia of the femoral head, avascular necrosis subsequently developed in 50%
of the femoral heads. However, with twelve hours of anoxia, avascular necrosis
developed in 100% of the femoral heads. In a similar study, Rösingh and
James2 assessed the survival of bone cells following ischemia in
the femoral heads of rabbits. They demonstrated that, at six hours
post-ischemia, the DNA of osteocytes and osteoblasts reached the point of no
return with subsequent DNA disintegration. Osteoclasts disintegrated at three
days.
In a clinical study of 494 patients treated with internal fixation of a
femoral neck fracture, Manninger et al.3 found that when the
fracture had been fixed within six hours after injury, the avascular necrosis
rate at two years was 10.5%. However, when the operation had been delayed
beyond this point, there was radiographic evidence of avascular necrosis in
40% of cases at two years.
Although Jain et al. found no radiographic evidence of avascular necrosis
in the group of patients treated with early fixation, I wish to note that
eight of the fifteen patients had less than two years of radiographic
follow-up and four had less than one year. Despite positive results, only a
small number of patients (seven) in the early fixation group were followed for
the full two years. Therefore, the study does not have enough power to allow
us to make any clinical inferences from the results.
In general orthopaedic practice in the United Kingdom, we generally strive
to use six hours postinjury as a cutoff for early fixation in young patients
with a displaced intracapsular fracture of the neck of the femur. We therefore
urge orthopaedic practitioners involved in the care of these patients to use
this length of time as a goalpost.
The literature has not been clear about the exact timing of fracture
fixation. As indicated in our article, the twelve-hour mark was used as the
cutoff in the belief that this would allow sufficient time for a patient to be
processed through the emergency department, undergo appropriate preoperative
investigations, and be taken to the operating room on an urgent basis within
the same day. The patients in our study were treated at major teaching
hospitals and two trauma centers. A high volume of life and limb-threatening
injuries is seen at these hospitals. Appropriate triage of all patients occurs
in the emergency department and the operating room such that life-threatening
injuries take precedence. Thus, even when hip fracture surgery is deemed
urgent by the surgeon, it may be delayed for a few hours.
Mr. Webb and Mr. Borrill point out that several investigations of animals
suggest that irreversible DNA changes occur with femoral head ischemia, but a
similar effect on humans was not noted in those studies. Therefore, the
applicability of the results of those investigations to human physiology does
not necessarily follow.
Manninger et al.3
examined a series of 592 patients with femoral neck fracture. Ninety-eight of
those patients were excluded (sixty-four were treated conservatively,
seventeen were deemed too medically ill for surgery, and seventeen underwent
arthroplasty). Of the remaining 494 patients, only sixty-four were less than
fifty years old. The investigators did not make adjustments for age. The
patients were divided into three groups based on the time from injury to
surgery: less than six hours, six to twenty-four hours, and more than
twenty-four hours. Furthermore, functional outcomes were not assessed. Only
surgical outcomes, including union, time to union, and femoral head collapse,
were evaluated. The patients studied by Manninger et al. had different
characteristics from our study group, and therefore their results are not
necessarily comparable with those in our patient group.
We did discuss the issue of incomplete radiographic follow-up in our
report. However, we provided functional outcomes, since these are an important
aspect of patient-centered care. Ultimately, as orthopaedic surgeons, we treat
patients' complaints, and not their radiographs in isolation.
Woodhouse CF. Dynamic influences
of vascular occlusion affecting the development of avascular necrosis of the
femoral head. Clin Orthop.1964;
32: 119-29.32119
1964
[PubMed]
Rösingh GE, James J. Early
phases of avascular necrosis of the femoral head in rabbits. J Bone
Joint Surg Br.1969;51:
165-74.51165
1969
Manninger J, Kazar G, Fekete G,
Fekete K, Frenyo S, Gyarfas F, Salacz T, Varga A. Significance of urgent
(within 6h) internal fixation in the management of fractures of the neck of
the femur. Injury.1989;20:
101-5.20101
1989
[PubMed][CrossRef]