Improved Healing of Large Segmental Defects in the Rat Femur by Reverse Dynamization in the Presence of Bone Morphogenetic Protein-2
Background: Large segmental defects in bone do not heal well and present clinical challenges. This study investigated modulation of the mechanical environment as a means of improving bone healing in the presence of bone morphogenetic protein (BMP)-2. Although the influence of mechanical forces on th...
| Main Authors: | , , , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
Journal of Bone and Joint Surgery, Inc.
2014
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| Online Access: | http://hdl.handle.net/1721.1/88158 |
| _version_ | 1826191204987961344 |
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| author | Glatt, Vaida Miller, Micah Ivkovic, Alan Liu, Fangjun Parry, Nicola Griffin, Damian Vrahas, Mark Evans, Christopher H. |
| author2 | Massachusetts Institute of Technology. Division of Comparative Medicine |
| author_facet | Massachusetts Institute of Technology. Division of Comparative Medicine Glatt, Vaida Miller, Micah Ivkovic, Alan Liu, Fangjun Parry, Nicola Griffin, Damian Vrahas, Mark Evans, Christopher H. |
| author_sort | Glatt, Vaida |
| collection | MIT |
| description | Background: Large segmental defects in bone do not heal well and present clinical challenges. This study investigated modulation of the mechanical environment as a means of improving bone healing in the presence of bone morphogenetic protein (BMP)-2. Although the influence of mechanical forces on the healing of fractures is well established, no previous studies, to our knowledge, have described their influence on the healing of large segmental defects. We hypothesized that bone-healing would be improved by initial, low-stiffness fixation of the defect, followed by high-stiffness fixation during the healing process. We call this reverse dynamization.
Methods: A rat model of a critical-sized femoral defect was used. External fixators were constructed to provide different degrees of stiffness and, importantly, the ability to change stiffness during the healing process in vivo. Healing of the critical-sized defects was initiated by the implantation of 11 μg of recombinant human BMP (rhBMP)-2 on a collagen sponge. Groups of rats receiving BMP-2 were allowed to heal with low, medium, and high-stiffness fixators, as well as under conditions of reverse dynamization, in which the stiffness was changed from low to high at two weeks. Healing was assessed at eight weeks with use of radiographs, histological analysis, microcomputed tomography, dual x-ray absorptiometry, and mechanical testing.
Results: Under constant stiffness, the low-stiffness fixator produced the best healing after eight weeks. However, reverse dynamization provided considerable improvement, resulting in a marked acceleration of the healing process by all of the criteria of this study. The histological data suggest that this was the result of intramembranous, rather than endochondral, ossification.
Conclusions: Reverse dynamization accelerated healing in the presence of BMP-2 in the rat femur and is worthy of further investigation as a means of improving the healing of large segmental bone defects.
Clinical Relevance: These data provide the basis of a novel, simple, and inexpensive way to improve the healing of critical-sized defects in long bones. Reverse dynamization may also be applicable to other circumstances in which bone-healing is problematic. |
| first_indexed | 2024-09-23T08:52:14Z |
| format | Article |
| id | mit-1721.1/88158 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T08:52:14Z |
| publishDate | 2014 |
| publisher | Journal of Bone and Joint Surgery, Inc. |
| record_format | dspace |
| spelling | mit-1721.1/881582022-09-26T08:50:52Z Improved Healing of Large Segmental Defects in the Rat Femur by Reverse Dynamization in the Presence of Bone Morphogenetic Protein-2 Glatt, Vaida Miller, Micah Ivkovic, Alan Liu, Fangjun Parry, Nicola Griffin, Damian Vrahas, Mark Evans, Christopher H. Massachusetts Institute of Technology. Division of Comparative Medicine Parry, Nicola Background: Large segmental defects in bone do not heal well and present clinical challenges. This study investigated modulation of the mechanical environment as a means of improving bone healing in the presence of bone morphogenetic protein (BMP)-2. Although the influence of mechanical forces on the healing of fractures is well established, no previous studies, to our knowledge, have described their influence on the healing of large segmental defects. We hypothesized that bone-healing would be improved by initial, low-stiffness fixation of the defect, followed by high-stiffness fixation during the healing process. We call this reverse dynamization. Methods: A rat model of a critical-sized femoral defect was used. External fixators were constructed to provide different degrees of stiffness and, importantly, the ability to change stiffness during the healing process in vivo. Healing of the critical-sized defects was initiated by the implantation of 11 μg of recombinant human BMP (rhBMP)-2 on a collagen sponge. Groups of rats receiving BMP-2 were allowed to heal with low, medium, and high-stiffness fixators, as well as under conditions of reverse dynamization, in which the stiffness was changed from low to high at two weeks. Healing was assessed at eight weeks with use of radiographs, histological analysis, microcomputed tomography, dual x-ray absorptiometry, and mechanical testing. Results: Under constant stiffness, the low-stiffness fixator produced the best healing after eight weeks. However, reverse dynamization provided considerable improvement, resulting in a marked acceleration of the healing process by all of the criteria of this study. The histological data suggest that this was the result of intramembranous, rather than endochondral, ossification. Conclusions: Reverse dynamization accelerated healing in the presence of BMP-2 in the rat femur and is worthy of further investigation as a means of improving the healing of large segmental bone defects. Clinical Relevance: These data provide the basis of a novel, simple, and inexpensive way to improve the healing of critical-sized defects in long bones. Reverse dynamization may also be applicable to other circumstances in which bone-healing is problematic. United States. Dept. of Defense (Grant W81XWH-10-1-0888) National Institute of Arthritis and Musculoskeletal and Skin Diseases (U.S.) (Grant R01AR50243) 2014-07-01T13:36:01Z 2014-07-01T13:36:01Z 2012-11 Article http://purl.org/eprint/type/JournalArticle 0021-9355 1535-1386 http://hdl.handle.net/1721.1/88158 Glatt, Vaida, Micah Miller, Alan Ivkovic, Fangjun Liu, Nicola Parry, Damian Griffin, Mark Vrahas, and Christopher Evans. “Improved Healing of Large Segmental Defects in the Rat Femur by Reverse Dynamization in the Presence of Bone Morphogenetic Protein-2.” J Bone Joint Surg Am 94, no. 22 (November 21, 2012): 2063. © 2012 by The Journal of Bone and Joint Surgery, Incorporated en_US http://dx.doi.org/10.2106/jbjs.k.01604 The Journal of Bone and Joint Surgery (American) Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf Journal of Bone and Joint Surgery, Inc. Journal of Bone and Joint Surgery, Inc. |
| spellingShingle | Glatt, Vaida Miller, Micah Ivkovic, Alan Liu, Fangjun Parry, Nicola Griffin, Damian Vrahas, Mark Evans, Christopher H. Improved Healing of Large Segmental Defects in the Rat Femur by Reverse Dynamization in the Presence of Bone Morphogenetic Protein-2 |
| title | Improved Healing of Large Segmental Defects in the Rat Femur by Reverse Dynamization in the Presence of Bone Morphogenetic Protein-2 |
| title_full | Improved Healing of Large Segmental Defects in the Rat Femur by Reverse Dynamization in the Presence of Bone Morphogenetic Protein-2 |
| title_fullStr | Improved Healing of Large Segmental Defects in the Rat Femur by Reverse Dynamization in the Presence of Bone Morphogenetic Protein-2 |
| title_full_unstemmed | Improved Healing of Large Segmental Defects in the Rat Femur by Reverse Dynamization in the Presence of Bone Morphogenetic Protein-2 |
| title_short | Improved Healing of Large Segmental Defects in the Rat Femur by Reverse Dynamization in the Presence of Bone Morphogenetic Protein-2 |
| title_sort | improved healing of large segmental defects in the rat femur by reverse dynamization in the presence of bone morphogenetic protein 2 |
| url | http://hdl.handle.net/1721.1/88158 |
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