Belly Fat Forces on the Spine: Finite Element Analysis of Belly Fat Forces by Waist Circumference.

OBJECT: It has been well-established that obesity, or the fat content of the belly, is associated with diabetes, heart conditions, metabolic syndrome and back pain. With regard to back pain, this study aimed to assess the forces that incremental amounts of belly fat exert on the spine. METHODS: A finite element analysis (FEA) was performed with a 3D CAD model of the spine using data for various populations from the Dallas Heart Study. RESULTS: There were significant differences in the forces exerted on the spine by belly fat among ethnic groups. CONCLUSIONS: These findings should help clarify the stress forces experienced by the spine in relation to waist circumference and could help to explain the association between obesity and back pain.

Backpack Forces on the Spine.

OBJECT: Backpacks are standard load carriers for people of all ages, especially school children and the military. Previous studies have described the impact of the forces exerted by backpacks on load distribution, back pain, and gait. The objective of this study was to use finite element analysis (FEA) to assess the effects of incremental weights in a backpack on the spine. METHODS: To assess the forces experienced by the spine under the incremental addition of weight to a backpack, we performed a finite element simulation using commercially available 'BodyParts3D/Anatomography' data, which were imported into FEA software. We studied two different scenarios: 1) a regular backpack with incrementally placed weights using both shoulder straps with the spine in a neutral position, and 2) a regular backpack with incrementally placed weights using both shoulder straps with the spine tilted forward 20 degrees. The spine model was physiologically accurate. RESULTS: For all of the added weights examined (1-100 pounds; 0.45-45.36 kg), the force experienced by the neutral spine was 7.2-fold the added weight. For the 20 degrees-forward posture, this value rose to 11.6-fold. CONCLUSIONS: These findings should help to clarify the forces experienced by the spine due to objects in a backpack. For example, this should help spinal surgeons to better understand the tremendous importance of sagittal plane alignment in planning their surgical reconstructions.

Stem Cells in Spine Surgery.

INTRODUCTION: Spine surgeons are embracing advanced biologic technologies in an attempt to help millions of people achieve a better outcome in spine surgery. These new technologies may be complicated to understand, partly because the contribution of different types of cells has not been definitively identified. This paper describes the characteristics of the stem cells used in spine surgery, including their actions and possible complications. The description necessitates an overview of all studies to date on the use of stem cells in spine surgery, as well as other cells used in cellular therapy. MATERIALS AND METHODS: The paper summarizes the results of major studies to date on the use of stem cells in spine surgery. Cells were harvested from the posterior superior iliac spine, vertebral bodies in surgery, fat tissue, or from the posterior spine of cadavers. RESULTS: This paper reports on three studies involving 37 patients treated with stem cells for regenerative spine surgery, 14 studies involving 533 patients treated with stem cells in spinal fusion surgery, and one study in which stem cells were used for the treatment of anterior cervical discectomy and fusion. DISCUSSION: Indications, techniques, and calibration of results were different in each study. Results are available for cellular augmentation of demineralized bone sponges, OsteoSponge® (Bacterin, Belgrade, Montana) and concentrated bone marrow (Terumo BCT®, Lakewood, CO); cancellous allograft bone and BMA; mineralized collagen and BMA; Osteocel® Plus (OC+) (Nuvasive®, San Diego, California); b-Tricalcium phosphate (b-TCP) (SYNTHES® Dento, West Chester, Pennsylvania; a silicate-substituted calcium phosphate (Si-CaP) with bone marrow aspirate (BMA), and HEALOS® graft carrier (DePuy Synthes, West Chester, Pennsylvania) with bone marrow aspirate. CONCLUSION: Stem cell augmentation of spinal fusion surgery is equivalent to the gold standard for iliac crest bone graft in posterolateral fusion models. There is evidence of safety and feasibility in the injectable treatment of DDD with autologous BMC that indicates a favorable outcome of mesenchymal cell concentration on discogenic pain reduction. The use of adult stem cells is an innovation that promises fewer complications and improved function in patients who are demographically suitable for stem cell therapy.

Breast Forces on the Spine.

OBJECTIVE: It is a well-established fact that women who have large, heavy breasts suffer from spine pain. The objective of this study is to assess the forces that the breast exerts on the spine. It is important that such women understand the stresses that the spine is forced to sustain because of heavy breasts. MATERIALS AND METHODS: The study was conducted using finite element analyses (FEA) of a human spine under different loads, loads being defined as incremental weights being sustained by the spine. The goal was to assess the influence of female breast size and weight on the forces and stresses sustained by the spine. RESULTS: The magnitude of forces generated by the breast to the thoracic spine ranged between 8.5 pounds of force for underwire size 30 to 110 pounds of force for underwire size 60. All increments in between were assessed in Newton of force and pounds of force. CONCLUSION: The magnification factor of forces generated by breast weight is 10X. Using the American bra sizing system a woman with a breast size of 36H would expect 52 pounds of force on the spine (for both breasts) while with weight loss she might reduce her breast size to 36D, with a corresponding reduction of force to 28 pounds of both breasts; that is, a total stress reduction of 24 pounds to the spine. On the other hand, surgical enlargement of size 34B breasts (18.4 pounds) to 34F (32.1 pounds) leads to an increase of ~14 pounds of force on the spine.

Assessment of stresses in the cervical spine caused by posture and position of the head.

Preamble. Billions of people are using cell phone devices on the planet, essentially in poor posture. The purpose of this study is to assess the forces incrementally seen by the cervical spine as the head is tilted forward, into worsening posture. This data is also necessary for cervical spine surgeons to understand in the reconstruction of the neck.