Kristin L Popp1, William McDermott2, Julie M Hughes3, Stephanie A Baxter2, Steven D Stovitz4, Moira A Petit5. 1. School of Kinesiology, Laboratory of Musculoskeletal Health, University of Minnesota, 1900 University Ave SE, Minneapolis, MN 55455, USA. Electronic address: kpopp@mgh.harvard.edu. 2. The Orthopedic Specialty Hospital, 5848 S Fashion Blvd, Murray, UT 84107, USA. 3. United States Army Research Institute of Environmental Medicine, 10 General Greene Ave, Natick, MA 01760, USA. 4. Department of Family Medicine and Community Health, University of Minnesota, 420 Delaware St. SE. MMC381, Minneapolis, MN 55455, USA. 5. School of Kinesiology, Laboratory of Musculoskeletal Health, University of Minnesota, 1900 University Ave SE, Minneapolis, MN 55455, USA.
Abstract
PURPOSE: To determine differences in bone geometry, estimates of bone strength, muscle size and bone strength relative to load, in women runners with and without a history of stress fracture. METHODS: We recruited 32 competitive distance runners aged 18-35, with (SFX, n=16) or without (NSFX, n=16) a history of stress fracture for this case-control study. Peripheral quantitative computed tomography (pQCT) was used to assess volumetric bone mineral density (vBMD, mg/mm3), total (ToA) and cortical (CtA) bone areas (mm2), and estimated compressive bone strength (bone strength index; BSI, mg/mm4) at the distal tibia. ToA, CtA, cortical vBMD, and estimated strength (section modulus; Zp, mm3 and strength strain index; SSIp, mm3) were measured at six cortical sites along the tibia. Mean active peak vertical (pkZ) ground reaction forces (GRFs), assessed from a fatigue run on an instrumented treadmill, were used in conjunction with pQCT measurements to estimate bone strength relative to load (mm2/N∗kg-1) at all cortical sites. RESULTS: SSIp and Zp were 9-11% lower in the SFX group at mid-shaft of the tibia, while ToA and vBMD did not differ between groups at any measurement site. The SFX group had 11-17% lower bone strength relative to mean pkZ GRFs (p<0.05). CONCLUSION: These findings indicate that estimated bone strength at the mid-tibia and mean pkZ GRFs are lower in runners with a history of stress fracture. Bone strength relative to load is also lower in this same region suggesting that strength deficits in the middle 1/3 of the tibia and altered gait biomechanics may predispose an individual to stress fracture. Copyright Â
PURPOSE: To determine differences in bone geometry, estimates of bone strength, muscle size and bone strength relative to load, in women runners with and without a history of stress fracture. METHODS: We recruited 32 competitive distance runners aged 18-35, with (SFX, n=16) or without (NSFX, n=16) a history of stress fracture for this case-control study. Peripheral quantitative computed tomography (pQCT) was used to assess volumetric bone mineral density (vBMD, mg/mm3), total (ToA) and cortical (CtA) bone areas (mm2), and estimated compressive bone strength (bone strength index; BSI, mg/mm4) at the distal tibia. ToA, CtA, cortical vBMD, and estimated strength (section modulus; Zp, mm3 and strength strain index; SSIp, mm3) were measured at six cortical sites along the tibia. Mean active peak vertical (pkZ) ground reaction forces (GRFs), assessed from a fatigue run on an instrumented treadmill, were used in conjunction with pQCT measurements to estimate bone strength relative to load (mm2/N∗kg-1) at all cortical sites. RESULTS: SSIp and Zp were 9-11% lower in the SFX group at mid-shaft of the tibia, while ToA and vBMD did not differ between groups at any measurement site. The SFX group had 11-17% lower bone strength relative to mean pkZ GRFs (p<0.05). CONCLUSION: These findings indicate that estimated bone strength at the mid-tibia and mean pkZ GRFs are lower in runners with a history of stress fracture. Bone strength relative to load is also lower in this same region suggesting that strength deficits in the middle 1/3 of the tibia and altered gait biomechanics may predispose an individual to stress fracture. Copyright Â
Authors: Therese E Johnston; Colleen Dempsey; Frances Gilman; Ryan Tomlinson; Ann-Katrin Jacketti; Jeremy Close Journal: Sports Health Date: 2020-06-11 Impact factor: 3.843
Authors: Sara E Rudolph; Signe Caksa; Sarah Gehman; Margaret Garrahan; Julie M Hughes; Adam S Tenforde; Kathryn E Ackerman; Mary L Bouxsein; Kristin L Popp Journal: Med Sci Sports Exerc Date: 2021-10-01
Authors: Therese E Johnston; Allison E Jakavick; Caroline A Mancuso; Kathleen C McGee; Lily Wei; Morgan L Wright; Jeremy Close; Ayako Shimada; Benjamin E Leiby Journal: Int J Sports Phys Ther Date: 2021-02-02