New concepts to prevent hip fractures

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Trauma Rounds
Case Reports from the Mass General Hospital and Brigham & Women’s Hospital
A Quarterly Case Study
Volume 5, Fall 2013
Femoroplasty for Hip Fractures
tebroplasty, various minimally invasive femoroplasty techniques involving introduction of fillers such as polymethylHip fractures in geriatric patients are associated methacrylate (PMMA), elastomeric polymers or calcium phoswith mortality rates of 20-30% at one year. phate products into the osteoporotic proximal femur have been
Many more patients experience significant loss described (6,7), but are not routinely performed in patients.
of function and independence (1). The number
of hip fractures worldwide was estimated at 1.7 Currently, there is no standard of care for femoroplasty procemillion (1990) and is expected to rise to 6.3 mil- dures in the United States. While in vitro biomechanical results
with femoroplasty have demonstrated increased peak loads and
lion by 2050 (2).
yields to fracture, they do not correlate with fracture prevenPreventing Hip Fractures
tion, and few studies have simulated fall stresses (8). Results in
One of the strongest predictors of hip fracture is a prior hip general have been disappointing, and none of the methods have
fracture. This is particularly true if a preventative osteoporosis been recommended for patient use in the US or Europe.
intervention is not pursued after the patient’s first fracture. The Anistropy Restoring Femoroplasty (ARF)
risk of a second fracture in the patient’s uninjured hip remains
high even if appropriate treatment for osteoporosis is initiated, In collaboration with Dr. Ara Nazarian at the Center for Addue to the lag between initiation and actual fracture risk at- vanced Orthopedic Science at the BIDMC, we are exploring the
tenuation. The current primary standard of care for preventive
Retrograde
intervention is medical management to reduce the rate of pro- Figure 1:
ARF in undeployed (top
gressive osteoporosis. Common fracture prevention modalities
left) and deployed (top
include the use of bisphosphonates, vitamin D, calcium sup- right). ARF implanted
plementation, and fracture precautions. However, bone sparing with Ca-Phosphate in
medical protocols such as the use of bisphosphonates do not porcine
model
of
guarantee bone density restoration and have recently become osteoporosis.
associated with increased risk of atypical fracture patterns, particularly around the subtrochanteric area of the femur (3).
Other options for osteoporosis management such as the use of
PTH agonists for bone restoration also carry potential risks (4).
Non-medical preventative measures include fall prevention
techniques, use of cushioning pads and reorganization of living
space.
E Kenneth Rodriguez, MD, PhD
Prophylactic Interventions
These limitations of medical management for fracture prevention have promoted interest in interventional procedures to reduce hip fracture risk. Prophylactic fixation of fractures with
traditional fracture repair instrumentation has been suggested,
but is not cost-effective and carries significant surgical risk (5).
There is recent interest in developing cost-effective interventional techniques to augment the mechanical properties of the
proximal femur. Following the successful experience with verTrauma Rounds, Volume 5, Fall 2013
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Summary
We envision ARF could be indicated for patients at high risk for
hip fractures or as a procedure performed during the same surgical session on the intact contralateral side of a patient presenting
for ORIF of a hip fracture.
Kenneth Rodriguez, MD,PhD, is Chief of Orthopaedic Trauma at Beth Israel
Deaconess Medical Center, Boston, MA.
References
Figure 2: Restoration of failure loads to controls levels in porcine
model with ARF plus Ca-Phosphate.
concept of Anisotropy Restoring Femoroplasty as a minimally
invasive interventional option for hip fracture prevention. We
have developed a technique and device that partially restores the
material anisotropy of the proximal femur with a polymeric or
Ca-phosphate filler. This composite structure, consisting of metallic elements embedded in an isotropic filler, restores both shear
and axial energy dissipation potential to the proximal femur beyond what is possible with isotropic filling of the proximal femur. The technique allows for minimally invasive insertion of an
antegrade ARF device from the greater trochanter combined with
retrograde ARF device from the lesser trochanter, both interlinked within a Ca-phosphate (Ca-P) filled proximal femur, each
inserted through separate 5 mm drill holes (Figure 1).
We are presently testing a prototype device in a pig femur model
(Figure 1) that has optimistic early results when compared with
isotropic femoroplasty alone. Insertion of our ARF prototype
device with calcium phosphate in a de-trabeculated pig femur
model simulating osteopenic bone restores load to failure (Figure
2) and bone stiffness to control levels.
Trauma Faculty
Mark Vrahas, MD — 617-726-2943
1. Brauer CA, Incidence and mortality of hip fractures in the United States.
JAMA, 2009; 302(14): 1573-9.
2. Gullberg B, Johnell O and Kanis JA, World-wide projections for hip fracture.
Osteoporos Int, 1997; 7(5): 407-13.
3. Seraphim A, et al., Do bisphosphonates cause femoral insufficiency fractures? J Orthop Traumatol, 2012; 13(4): 171-7.
4. Augustine M and Horwitz MJ, Parathyroid Hormone and Parathyroid
Hormone-Related Protein Analogs as Therapies for Osteoporosis. Curr Osteoporos Rep, 2013; Sep 28.
5. Faucett SC et al, Is prophylactic fixation a cost-effective method to prevent a
future contralateral fragility hip fracture? J Orthop Trauma, 2010; 24(2): 65-74.
6. van der Steenhoven TJ, et al, Elastomer femoroplasty prevents hip fracture
displacement In vitro biomechanical study comparing two minimal invasive
femoroplasty techniques. Clin Biomech, 2011; 26(5): 464-9.
7. Strauss EJ, et al, Calcium phosphate cement augmentation of the femoral
neck defect created after dynamic hip screw removal. J Orthop Trauma, 2007;
21(5): 295-300.
8. Sutter EG, Mears SC and Belkoff SM, A biomechanical evaluation of femoroplasty under simulated fall conditions. J Orthop Trauma, 2010; 24(2): 95-9.
New England Regional Fracture Summit, Stowe, VT
The annual AO Fracture Summit will be held January 17 – 20, 2014 in
Stowe, VT. The highly interactive course is chaired by Drs. Mark Vrahas, Jesse Jupiter and Raymond White, and features several members of
the Harvard Orthopaedic Trauma faculty. This year’s invited sage is Dr.
David Helfet of the Hospital for Special Surgery, NY.
The course is designed to educate community orthopedic surgeons
who are actively involved in the treatment of patients with fractures.
Participants are encouraged to bring their own cases for discussion.
Registration is still open.
For more information: www.aona.org
AchesAndJoints.org/Trauma
Read archives of all previous issues
Jesse Jupiter, MD — 617-726-5100
Please share your comments online, or by email:
MGH Hand & Upper Extremity Service
Mark Vrahas, MD / mvrahas@partners.org
Yawkey Center for Outpatient Care, Ste 3C
55 Fruit Street, Boston, MA 02114
Partners Chief of Orthopaedic Trauma
mvrahas@partners.org
jjupiter@partners.org
Mitchel B Harris, MD — 617-732-5385
MGH Hand & Upper Extremity Service
dring@partners.org
Chief, BWH Orthopedic Trauma
mbharris@partners.org
R Malcolm Smith, MD, FRCS — 617-726-2794
Chief, MGH Orthopaedic Trauma
rmsmith1@partners.org
David Lhowe, MD — 617-724-2800
MGH Orthopaedic Trauma
dlhowe@partners.org
Michael Weaver, MD — 617-525-8088
BWH Orthopedic Trauma
mjweaver@partners.org
2
David Ring, MD — 617-724-3953
Brandon E Earp, MD — 617-732-8064
BWH Hand & Upper Extremity Service
bearp@partners.org
George Dyer, MD — 617-732-6607
BWH Hand & Upper Extremity Service
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Editor in Chief
Mark Vrahas, MD
Program Director
Suzanne Morrison, MPH
(617) 525-8876
smmorrison@partners.org
Editor, Publisher
John Kwon, MD — 617-643-5701
Arun Shanbhag, PhD, MBA
MGH Foot & Ankle Service
www.MassGeneral.org/ortho
www.BrighamAndWomens.org/orthopedics
jkwon@partners.org
Trauma Rounds, Volume 5, Fall 2013