ch 45 delayed union, non-union, and malunion Flashcards
(49 cards)
what are the 4 tenants of bone healing and regeneration
mechanics
scaffold
growth factors
cells
what is geometric configuration as it relates to bone healing
geometric configuration centers on limb alignment or fracture reduction
what is the maximum gap that a bone can have and still heal
definitive number is unknown but ill advised to have a gap wider than the diameter of the bone
what is the most favorable mechanical environment for bone formation
Low to moderate magnitudes of tensile strain and hydrostatic tensile stress
during weight bearing, most forces across the diaphysis are ______ → healing tissues are compressed and hydrostatic forces are placed _______ → tension is created on the _______ of the fracture callus
During weight bearing, most forces across the diaphysis are AXIAL
Healing tissues are compressed and hydrostatic forces are placed ABAXIALLY
Tension is created on the OUTSIDE of the fracture callus
Bone is formed _____ along tension stresses
Bone is formed abaxially along tension stresses
Closer to the center of the callus, stem cells are subjected to _______ forces → favors _____
Closer to the center of the callus, stem cells are subjected to COMPRESSIVE forces → favors CHONDROGENESIS
how is axial strain
calculated
decrease in gap width divided by total gap width
The amount of strain shown to enhance new bone formation in axial load is as high as _______
36%
strains of _____ demonstrate far less bone healing
7%
For small gaps, _____ interfragmentary movements result in _____ periosteal areas of callus
For small gaps, LARGER interfragmentary movements result in LARGER periosteal areas of callus
For large gaps, interfragmentary movement _______ stimulation of callus and _______ consolidation of the fracture
For large gaps, interfragmentary movement INHIBITS stimulation of callus and DELAYS consolidation of the fracture
Stress protection
refers to the inhibited healing of fractures if too little strain is imparted to the healing fracture callus
what is the strain needed for simple axial loading and fx with a few to several mm of gap or comminution
5-10%
Tensile forces promote stem cell differentiation and proliferation along ______ lineages
Tensile forces promote stem cell differentiation and proliferation along OSTEOBLASTIC lineages
Compressive forces promote stem cell proliferation along _______ lineages
Compressive forces promote stem cell proliferation along CHONDROBLASTIC lineages
_______ forces promote stem cell proliferation along chondroblastic lineages
COMPRESSIVE forces promote stem cell proliferation along chondroblastic lineages
__________ forces promote stem cell differentiation and proliferation along osteoblastic lineages
TENSILE forces promote stem cell differentiation and proliferation along osteoblastic lineages
bending forces have compression on ______ side of bend, tension on _______ side
bending forces have compression on CONCAVE side of bend, tension on CONVEX side
Bending is a combination of ______ and _____. Maximal ______ and _____ occur at the surface of the bone and decrease toward the neutral axis.
Bending is a combination of COMPRESSION and TENSION. Maximal COMPRESSION and TENSION occur at the surface of the bone and decrease toward the neutral axis.
Cellular activity (migration, adhesion, proliferation, differentiation) occurs in concert with ________ signaling
humoral signaling
what are negative intrinsic factors for growth factor activity
Diaphyseal cortical bone,
decreased/compromised vascularity of the periosteum,
sparse soft tissue attachments
aged patient
what is plate luting
technique used in fx repair where PMMA is placed between the bone and the plate as well as the screw heads in the plate
Cambrium
layer of periosteum
Inner layer cells are osteongenic precursors important for skeletal growth, remodeling, and regional fx repair
