Trauma Rounds Case Reports from the Mass General Hospital and Brigham & Women’s Hospital A Quarterly Case Study Volume 5, Fall 2013

E Kenneth Rodriguez, MD, PhDHip fractures in geriatric patients are associated with mortality rates of 20-30% at one year. Many more patients experience significant loss of function and independence (1). The number of hip fractures worldwide was estimated at 1.7 million (1990) and is expected to rise to 6.3 mil-lion by 2050 (2).

Preventing Hip Fractures

One of the strongest predictors of hip fracture is a prior hip fracture. This is particularly true if a preventative osteoporosis intervention is not pursued after the patient’s first fracture. The risk of a second fracture in the patient’s uninjured hip remains high even if appropriate treatment for osteoporosis is initiated, due to the lag between initiation and actual fracture risk at-tenuation. The current primary standard of care for preventive intervention is medical management to reduce the rate of pro-gressive osteoporosis. Common fracture prevention modalities include the use of bisphosphonates, vitamin D, calcium sup-plementation, and fracture precautions. However, bone sparing medical protocols such as the use of bisphosphonates do not guarantee bone density restoration and have recently become associated with increased risk of atypical fracture patterns, par-ticularly 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.Prophylactic Interventions

These limitations of medical management for fracture preven-tion have promoted interest in interventional procedures to re-duce 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 interven-tional techniques to augment the mechanical properties of the proximal femur. Following the successful experience with ver-

tebroplasty, various minimally invasive femoroplasty tech-niques involving introduction of fillers such as polymethyl-methacrylate (PMMA), elastomeric polymers or calcium phos-phate products into the osteoporotic proximal femur have been described (6,7), but are not routinely performed in patients.

Currently, there is no standard of care for femoroplasty proce-dures in the United States. While in vitro biomechanical results with femoroplasty have demonstrated increased peak loads and yields to fracture, they do not correlate with fracture preven-tion, and few studies have simulated fall stresses (8). Results in general have been disappointing, and none of the methods have been recommended for patient use in the US or Europe.Anistropy Restoring Femoroplasty (ARF)

In collaboration with Dr. Ara Nazarian at the Center for Ad-vanced Orthopedic Science at the BIDMC, we are exploring the

Trauma Rounds, Volume 5, Fall 2013 1

P A R T N E R S O R T H O P A E D I C

Femoroplasty for Hip Fractures

Figure 1: Retrograde ARF in undeployed (top left) and deployed (top right). ARF implanted with Ca-Phosphate in porcine model of osteoporosis.

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 me-tallic elements embedded in an isotropic filler, restores both shear and axial energy dissipation potential to the proximal femur be-yond what is possible with isotropic filling of the proximal fe-mur. 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 inter-linked 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.

Summary

We envision ARF could be indicated for patients at high risk for hip fractures or as a procedure performed during the same surgi-cal 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.

References1. 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 frac-

tures? 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 Os-teoporos 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 femoro-plasty under simulated fall conditions. J Orthop Trauma, 2010; 24(2): 95-9.

P A R T N E R S O R T H O P A E D I C T R A U M A R O U N D S

2 Trauma Rounds, Volume 5, Fall 2013

Trauma FacultyMark Vrahas, MD — 617-726-2943Partners Chief of Orthopaedic Traumamvrahas@partners.org

Mitchel B Harris, MD — 617-732-5385Chief, BWH Orthopedic Traumambharris@partners.orgR Malcolm Smith, MD, FRCS — 617-726-2794Chief, MGH Orthopaedic Traumarmsmith1@partners.orgDavid Lhowe, MD — 617-724-2800MGH Orthopaedic Traumadlhowe@partners.org

Michael Weaver, MD — 617-525-8088BWH Orthopedic Traumamjweaver@partners.org

Jesse Jupiter, MD — 617-726-5100MGH Hand & Upper Extremity Servicejjupiter@partners.org

David Ring, MD — 617-724-3953MGH Hand & Upper Extremity Servicedring@partners.org

Brandon E Earp, MD — 617-732-8064BWH Hand & Upper Extremity Servicebearp@partners.org

George Dyer, MD — 617-732-6607BWH Hand & Upper Extremity Servicegdyer@partners.org

John Kwon, MD — 617-643-5701MGH Foot & Ankle Servicejkwon@partners.org

Please share your comments online, or by email:Mark Vrahas, MD / mvrahas@partners.orgYawkey Center for Outpatient Care, Ste 3C55 Fruit Street, Boston, MA 02114

Editor in Chief Mark Vrahas, MD

Program DirectorSuzanne Morrison, MPH(617) 525-8876smmorrison@partners.org

Editor, PublisherArun Shanbhag, PhD, MBAwww.MassGeneral.org/orthowww.BrighamAndWomens.org/orthopedics

Figure 2: Restoration of failure loads to controls levels in porcine model with ARF plus Ca-Phosphate.

AchesAndJoints.org/TraumaRead archives of all previous issues

New England Regional Fracture Summit, Stowe, VTThe annual AO Fracture Summit will be held January 17 – 20, 2014 in Stowe, VT. The highly interactive course is chaired by Drs. Mark Vra-has, 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