CHOA IRB#: 11-017
v.22July2015
Title: Intraoperative Monitoring of Epiphyseal Perfusion in Slipped Capital Femoral Epiphysis
Investigators: Tim Schrader, M.D., Principle InvestigatorStephanie Detamore-Athre,
ACNP, Sub-Investigator
Mary Beth Brock, BS, Sub-Investigator
Mackenzie Herzog, MPH, Research Coordinator
Rian Thornton, BS, CCRC, Research Coordinator
Primary Aim of Study
This prospective study is being proposed to quantify the perfusion to the femoral epiphysis during
fixation of patients with slipped capital femoral epiphysis. In addition, we hope to correlate epiphyseal
perfusion with measures of severity of epiphyseal slip. In doing so, we hope to validate the use of
intracranial pressure monitoring systems in the arena of orthopaedic fracture care. The study will be
performed in the operating room setting at Children’s Healthcare of Atlanta at Scottish Rite pediatric
hospital.
Background Information and Significance:
Slipped capital femoral epiphysis (SCFE) is among the most common hip pathologies seen by the
pediatric orthopaedic surgeon. These growth plate injuries typically develop in adolescents with an
incidence of 1/10,000 in the United States. Both biochemical (gonadotropins, thyroid hormone) and
biomechanical factors (obesity, femoral retroversion, and physeal obliquity) are thought to contribute to
a weakened physis. Regardless of the mechanism, SCFE’s represent an acute or chronic injury to the
hypertrophic zone of the physis, allowing posteroinferior displacement of the capital femoral epiphysis
on the femoral neck. As a result, a three-dimensional deformity is created wherein the proximal femur
assumes a varus, extension and external rotation position in the coronal, sagittal and axial plane
respectively [1].
SCFE usually presents as hip or knee pain and is diagnosed on plan radiographs as the femoral epiphysis
is no longer centered on the metaphysis. The severity, timing and stability of SCFE’s are included in
several well-established classification systems. The amount of displacement is usually reported as mild
0-33%, moderate 33-50% or severe >50%. Patients who can bear weight are said to have “stable”
injuries, while non-weight bearing patients have “unstable” slips. Approximately 15% of patients present
acutely (< 3 weeks of symptoms) with what is equivalent to a fracture through the growth plate. Chronic
SCFE encompass the other 85% of patients who have had > 3 weeks of pain. These classifications not
only guide the treatment of SCFE’s but also help predict the development of complications in patients
[1].
Because the severity of SCFE is directly related to the duration of symptoms, early operative treatment
is indicated. In situ fixation of SCFE’s with cannulated screws has proven an effective, minimally-invasive
technique for growth plate stabilization. This technique is associated with a high success rate, high
patient satisfaction rate and a low incidence of slip progression, chondrolysis, and osteonecrosis. To
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accomplish in situ fixation, a threaded 7.0 or 7.3 mm screw is advanced over a guide-wire from the distal
femoral neck, through the physis and into the epiphysis. Good to excellent results have been shown in
as many as 90-95% of patients undergoing in situ fixation [2]. Prophylactic pinning of the contralateral
side is also indicated in select patients [1].
Despite these measures, complications are not uncommon after SCFE and slip progression, degenerative
hip disease and chondrolysis have all been reported. Perhaps the most devastating complication
following SCFE is osteonecrosis. This vascular insufficiency is likely multifactorial as the femoral neck
blood vessels supplying the femoral head are kinked by the epiphyseal displacement and are
compressed by the evolving intracapsular hematoma [3-5]. Patients with osteonecrosis universally
develop degenerative hip disease, often requiring arthroplasty. Osteonecrosis is rarely seen in stable
injuries but develops in as many of 58% of patients with unstable SCFE [6].
Several efforts have been made to monitor the blood supply to the femoral head in the setting of SCFE.
In doing so, authors have hoped not only to predict, but prevent osteonecrosis through the reduction of
femoral epiphysis prior to fixation. For instance, pre-operative MRI has been shown to be both sensitive
and specific for the development of osteonecrosis [7]. Post-operative bone scan has also shown
excellent accuracy in the prediction of osteonecrosis [8]. However neither can provide a real-time, intraoperative measure of blood flow to the femoral head. With this information in hand, surgeons could
determine the necessity for, and adequacy of, intraoperative reduction. Lack of perfusion would clearly
alter operative treatment plan and would prompt closed reduction to regain blood flow or surgical
dislocation. This latter technique spares the retinacular vessels but permits visualization of the entire hip
joint, allowing anatomic reduction of the epiphysis and, perhaps, restoration of flow.
The purpose of this prospective study is to establish an intra-operative technique to monitor epiphyseal
blood flow in SCFE patients at Children’s Healthcare of Atlanta (Scottish Rite Campus). Our hypothesis is
that by utilizing an intracranial pressure monitor to measure perfusion levels in the femoral epiphysis,
the investigators can reliably assess the perfusion levels within the epiphysis and possibly reduce the
incidence of avascular necrosis (AVN). The implications of this study may lead to a change in post
operative treatment, changes in surgical plan at the time of surgery if little to no epiphyseal perfusion is
present and potentially new treatments for SCFE patients before any long term structural damage is
done.
The Integra Camino Intracranial neural pressure monitor will be utilized through the cannulated femoral
neck screws during the standard operative fixation of stable and unstable SCFE patients. This will allow a
real-time record of epiphyseal perfusion pressure throughout standard in situ pinning and the
manipulation of unstable fractures. Correlations will be made to patients’ blood pressure, demographic
data and injury characteristics.
The Camino , itself, is an FDA-approved device used to rapidly determine and continuously monitor
intracranial pressure and perfusion. It uses a sterile transducer-tipped pressure monitoring catheter to
produce an artifact free, high fidelity waveform tracing without the need for a “fluid-filled” system. In
the proposed application, the monitor would quantify perfusion pressure in the femoral head rather
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than cerebral tissue pressure. Following our protocol, the ICP monitor will be inserted through a
previously-placed hollow screw and then removed after the measurement has been recorded.
Although this device is FDA approved to monitor intracranial perfusion levels, the ICP monitor has not
been approved to monitor blood supply in orthopaedic surgeries, but may be utilized by orthopaedic
surgeons as an off-label device to improve surgical outcomes. Dr. Schrader now utilizes this ICP camino
as standard of care for all SCFE surgical cases after several successful attempts in which the results of
the perfusion waveforms assisted him in dictating the best surgical plan for each patient.
Study Sample description and Comparison Group along with Methods and Materials
In this prospective study, the investigators will enroll two groups of patients into this study; 1) A
validation group of approximately 10-15 patients with stable SCFE which will be pinned in situ without
manipulations and 2) A control group of approximately 20 unstable SCFE patients. Both groups will be
enrolled concurrently.
The operative protocol will proceed per standard of care surgical technique with the placement of a
single 7.3 mm cannulated Richards screw. Once the screw is confirmed to be in adequate position on
fluoroscopic imaging, we will advance an Integra Neurosciences Camino neural monitoring tube through
the screw. The monitor will be advanced no more than 2mm past the tip of the screw but will not
penetrate the joint. The ICP monitor continuous measurement is conceptualized the same as a blood
pressure waveform would be and measured in mm/Hg. A baseline systolic and diastolic blood pressure
measurement will be recorded prior to screw placement and then another measurement will be
recorded when the screw is inserted into the femoral head. Once the ICP monitor has been confirmed
to be in the correct position via fluoroscopic imaging, the investigator will record the highest and lowest
perfusion measurement over the time of the ICP placement.
We will quantify perfusion before and after reduction either through closed means or after open
reduction with a surgical dislocation. During manipulations, slip angle and slip index obtained from
fluoroscopic images will be correlated to perfusion. Ideally, we will also correlate these values to clinical
and radiographic outcomes during short-term follow-up.
Inclusion / Exclusion Criteria
Inclusion:
1) Male or female between the ages of 8-16 years with a documented SCFE diagnosis
Exclusion:
1) No clear documented presence of SCFE
Data Analysis
The clinical data will be obtained by exporting waveforms directly from the Integra monitor to Word
charts. We will record average peak pressure, average trough pressure and pulse pressure as a measure
of perfusion. This will be correlated to patient demographics (age, acuity of slip, sex), injury
characteristics (slip angle, slip index) and intraoperative values (systolic blood pressure, diastolic blood
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pressure, percent reduction). All data will be obtained from Epic, which requires password access in
order to view the data, therefore protecting patients’ confidentiality. The information will be encoded
and de-identified. Quantitative analysis of data will be performed.
Potential risks and discomforts:
This procedure will add a minimal amount of time for operative fixation of the SCFE. We are estimating
approximately 5-10 minutes of extra anesthesia time and approximately 1-2 seconds of extra
fluoroscopic images which translate to 5-10 additional mrem of radiation. The x-ray images will be
fluoroscopic quick shots of the hip(s) in question and not full pelvis x-rays which equate to 70-80mrem.
Per Health Physics Society (HPS) it is assumed that the annual background radiation a person is exposed
to is approximately 700 mrem.
There is also always a risk of public health information that could be leaked to those not IRB approved to
participate in this study. Therefore, data will be maintained in a database on a secure hard drive that will
be kept at the Children’s Orthopaedics of Atlanta office under a password-protected login. Only
authorized staff will have access to the research database associated with the study. Furthermore, no
data will be identifiable to study subjects, as each subject will be assigned a unique study number when
entered into the database. When published or presented, no identifying features will be provided.
Potential Benefits:
In regards to the potential benefits of this study, the investigators believe that both groups may benefit
from this technique as it will offer the real-time monitoring of blood flow and provide the surgeon with
additional surgical information that may confirm his surgical plan or alter it to achieve the very best
outcome.
Informed Consent Process
Potential patients fitting inclusion and exclusion study criteria will be identified by the PI. Once
identified, these patients and their families will be approached by investigators and/or study staff to
determine their interest in participating in the study, and to obtain informed consent, assent, and HIPAA
authorization prior to any study-related procedures. The study will be explained in detail to the patient
and/or family, including the purpose, procedures, and risks involved in the study. A Children’s
Healthcare of Atlanta IRB-approved informed consent package will be presented to the patient and/or
family for review, which will go into further detail about the study. The patient and/or family will be
given ample time to review and discuss the consent. All questions will be answered by the investigator
and/or study staff prior to completion of the informed consent process. After the informed consent
process has been completed and documented, a copy of the consent will be given to the patient and/or
family. During the informed consent process, the investigator and/or study staff will clearly
communicate to the patient and/or family that their decision to participate or not participate in this
study is entirely voluntary and will not affect their current or future care at the hospital.
Intended Sample Size
Up to 15 patients in the validation group of stable SCFE’s and up to 20 patients in the unstable group
which may or may not require reduction. The results of this study will dictate future larger population
studies and whether use of the ICP camino monitor is feasible in patients who will have surgical
intervention for their SCFE.
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Funding Sources
Funding for the ICP monitor devices, staff effort and statistical review has been awarded from a
Children’s Healthcare of Atlanta intramural “Friends” seed grant. The budgeted amount secured will
cover up to 35 enrolled patients in the study.
Additional charges for time in the operating room, radiographic images and anesthesia time are
considered negligible and will be billed to each enrolled patient’s insurance per standard of care.
Study Time Line
Up to 36 months or until full enrollment is achieved.
Intended Results Dissemination Plan
Preliminary and final results of this study will be submitted to orthopaedic arenas such as Journal of
Pediatric Orthopedics or the Journal of Bone and Joint Surgery. Findings will also be submitted for
presentation at major pediatric, trauma and general orthopaedic conferences.
Data Safety and Monitoring Plan
In order to ensure patient safety, data accuracy and overall research compliance the investigators will
continue to submit all preliminary study data and documentation to an independent reviewer quarterly.
After review of data, the independent reviewer and investigators will provide an updated data and
safety monitoring plan to identify how the data will be utilized and if the study should continue. The
principle investigator will review all adverse events, protocol deviations and noncompliance immediately
if they should occur and will be promptly reported per Children’s institutional policies. This voluntary
internal audit will ensure that the study is in accordance to ICH/GCP, HIPAA, and CHOA institutional
policies and guidelines. In addition to the initial study audit, subsequent audits will be conducted
annually thereafter until the completion of the study.
References:
1) Aronsson DD, et al. Slipped Capital Femoral Epiphysis: Current Concept. JAAOS
2006;14:666.
2) Aronsson DD, Carlson WE, Slipped Capital Femoral Epiphysis: A prospective study of
fixation with a single screw. JBJS 1992;74:810.
3) Maeda S, et al. Vascular supply to spilled capital femoral epiphysis. JPO 2001;21:664.
4) Svalastoga E, et al. The effect of intracapsular pressure and extension of the hip on
oxygenation of the juvenile femoral epiphysis: A study in the goat. JBJS 1989;71:222.
5) Beck M, et al. Increased Intraarticular pressure reduces blood flow to the femoral head.
CORR 2004;424:149.
6) Krahn TH, et al. Long-term follow-up of pateints with avascular necrosis after treatment
of slipped capital femoral epiphysis. JPO 1993;13:154.
7) Tins B, et al. The role of pre-treatment MRI in established cases of slipped capital
femoral epiphysis. Eur J Rad 2009;70:570.
8) Rhoad RC, et al. Pretreatment Bone Scan in SCFE: A Predictor of Ischemia and Avascular
Necrosis. JPO 1999;19:164.
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