The Journal of Bone and Joint Surgery (American). 2009;91:2903-2914.
doi:10.2106/JBJS.H.01464
© 2009 The Journal of Bone and Joint Surgery, Inc.
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow CME: Take the activities for this article:
 Pediatrics Test 22: Winter 2010 (publ...
CME 4: October, November, December 20...
Right arrow [Supplementary Material]
Right arrow Letters to the Editor: Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when Letters to the Editor are posted
Right arrow Alert me if a correction is posted
Services
Right arrow E-mail this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My File Cabinet
Right arrow Download to citation manager
Right arrow Rights and Permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Right arrow Sign up for keyword alerts
Google Scholar
Right arrow Articles by Shapiro, F.
Right arrow Articles by Jaramillo, D.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Shapiro, F.
Right arrow Articles by Jaramillo, D.
Related Collections
Right arrow Basic Science
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us   Add to Facebook   Add to Technorati   Add to Twitter  
What's this?

Femoral Head Deformation and Repair Following Induction of Ischemic Necrosis

A Histologic and Magnetic Resonance Imaging Study in the Piglet

Frederic Shapiro, MD1, Susan Connolly, MD1, David Zurakowski, PhD1, Nina Menezes, PhD2, Elizabeth Olear, MA2, Mauricio Jimenez, MD3, Evelyn Flynn, MA1 and Diego Jaramillo, MD, MPH3

1 Department of Orthopaedic Surgery (F.S., D.Z., and E.F.) and Radiology (S.C.), Children's Hospital Boston, 300 Longwood Avenue, Boston, MA 02115. E-mail address for F. Shapiro: frederic.shapiro{at}childrens.harvard.edu
2 Department of Radiology, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114
3 Department of Radiology, Children's Hospital of Philadelphia, 34th and Civic Center Boulevard, Philadelphia, PA 19104

Investigation performed at Orthopaedic Research Laboratory and Department of Radiology, Children's Hospital Boston, and Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts

Disclosure: In support of their research for or preparation of this work, one or more of the authors received, in any one year, outside funding or grants in excess of $10,000 from the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity.

Background: Ischemic necrosis of the femoral head can be induced surgically in the piglet. We used this model to assess femoral head deformation and repair in vivo by sequential magnetic resonance imaging and by correlating end-stage findings with histologic assessments.

Methods: Ischemic necrosis of the femoral head was induced in ten three-week-old piglets by tying a silk ligature around the base of the femoral neck (intracapsular) and cutting the ligamentum teres. We used magnetic resonance imaging with the piglets under general anesthesia to study the hips at forty-eight hours and at one, two, four, and eight weeks. Measurements on magnetic resonance images in the midcoronal plane of the involved and control sides at each time documented the femoral head height, femoral head width, superior surface cartilage height, and femoral neck-shaft angle. Histologic assessments were done at the time of killing.

Results: Complete ischemia of the femoral head was identified in all involved femora by magnetic resonance imaging at forty-eight hours. Revascularization began at the periphery of the femoral head as early as one week and was underway in all by two weeks. At eight weeks, magnetic resonance imaging and histologic analysis showed deformation of the femoral head and variable tissue deposition. Tissue responses included (1) vascularized fibroblastic ingrowth with tissue resorption and cartilage, intramembranous bone, and mixed fibro-osseous or fibro-cartilaginous tissue synthesis and (2) resumption of endochondral bone growth. At eight weeks, the mean femoral head measurements (and standard error of the mean) for the control compared with the ligated femora were 10.4 ± 0.4 and 4.8 ± 0.4 mm, respectively, for height; 26.7 ± 0.8 and 31.2 ± 0.8 mm for diameter; 1.1 ± 0.1 and 2.3 ± 0.1 mm for cartilage thickness; and 151° ± 2° and 135° ± 2° for the femoral neck-shaft angle. Repeated-measures mixed-model analysis of variance revealed highly significant effects of ligation in each parameter (p < 0.0001).

Conclusions: Magnetic resonance imaging allows for the assessment of individual hips at sequential time periods to follow deformation and repair. There was a variable tissue response, and histologic assessment at the time of killing was shown to correlate with the evolving and varying magnetic resonance imaging signal intensities. Femoral head height on the ischemic side from one week onward was always less than the initial control value and continually decreased with time, indicating collapse as well as slowed growth. Increased femoral head width occurred relatively late (four to eight weeks), indicating cartilage model overgrowth concentrated at the periphery.

Clinical Relevance: Femoral head deformation and internal tissue deposition patterns can be followed accurately in vivo by magnetic resonance imaging.


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Facebook Facebook   Add to Technorati Technorati   Add to Twitter Twitter    What's this?