TY - JOUR
T1 - Bone strength estimates relative to vertical ground reaction force discriminates women runners with stress fracture history
AU - Popp, Kristin L.
AU - McDermott, William
AU - Hughes, Julie M.
AU - Baxter, Stephanie A.
AU - Stovitz, Steven D
AU - Petit, Moira A.
N1 - Publisher Copyright:
© 2016
PY - 2017/1/1
Y1 - 2017/1/1
N2 - 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.
AB - 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.
KW - Cortical area
KW - Female
KW - Peripheral quantitative computed tomography (pQCT)
KW - Running mechanics
KW - Volumetric bone mineral density (vBMD)
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U2 - 10.1016/j.bone.2016.10.006
DO - 10.1016/j.bone.2016.10.006
M3 - Article
C2 - 27729292
AN - SCOPUS:84991706677
SN - 8756-3282
VL - 94
SP - 22
EP - 28
JO - Bone
JF - Bone
ER -