Urist tested whether implants of dead, decalcified bone matrix could induce new bone to form in host tissue.
About 70 implant experiments in roughly 300 animals, most of them rabbits, plus bone defects in 21 patients.
Urist presented the experiments in support of a hypothesis that bone forms after fetal life by autoinduction.
Methods
Model
Muscle pouches in rabbits, rats, mice and guinea pigs
Bone beds in rabbits, dogs and humans
Intervention
HCl‑decalcified diaphyseal matrix
Chemically or physically altered preparations
Assays
Radiographs
Histology
Share of implants forming bone
Time points
3 to 16 weeks after implantation
Key Findings
At best, decalcified matrix formed new bone in over 90% of experiments, in an amount proportional to the implant volume.
Matrix decalcified with EDTA or mixed formic and citric acids induced bone like HCl‑treated matrix, while nitric or nitrous acid abolished induction.
From 8 to 16 weeks, more bone formed by endochondral ossification of cartilage nests in old vascular channels.
When induction succeeded in muscle, the implant was replaced by a living ossicle with a marrow cavity, about 75% of the original implant volume.
In an illustrated rabbit ulnar defect, the decalcified segment was completely replaced by new bone at 12 weeks, while the undecalcified segment was largely unresorbed.
Decalcified matrix gave no internal fixation and failed to fuse the dog lumbar spine.
Board pearl
Bone forming in decalcified matrix implanted in muscle is evidence of induction, because no host bone is nearby to supply bone‑forming cells by osteoconduction.
Authors' conclusion
The process is followed immediately by new-bone formation by autoinduction in which both the inductor cells and the induced cells are derived from ingrowing cells of the host bed.
Urist tested whether implants of dead, decalcified bone matrix could induce new bone to form in host tissue.
About 70 implant experiments in roughly 300 animals, most of them rabbits, plus bone defects in 21 patients.
Urist presented the experiments in support of a hypothesis that bone forms after fetal life by autoinduction.
Methods
Model
Muscle pouches in rabbits, rats, mice and guinea pigs
Bone beds in rabbits, dogs and humans
Intervention
HCl‑decalcified diaphyseal matrix
Chemically or physically altered preparations
Assays
Radiographs
Histology
Share of implants forming bone
Time points
3 to 16 weeks after implantation
Key Findings
At best, decalcified matrix formed new bone in over 90% of experiments, in an amount proportional to the implant volume.
Matrix decalcified with EDTA or mixed formic and citric acids induced bone like HCl‑treated matrix, while nitric or nitrous acid abolished induction.
From 8 to 16 weeks, more bone formed by endochondral ossification of cartilage nests in old vascular channels.
When induction succeeded in muscle, the implant was replaced by a living ossicle with a marrow cavity, about 75% of the original implant volume.
In an illustrated rabbit ulnar defect, the decalcified segment was completely replaced by new bone at 12 weeks, while the undecalcified segment was largely unresorbed.
Decalcified matrix gave no internal fixation and failed to fuse the dog lumbar spine.
Board pearl
Bone forming in decalcified matrix implanted in muscle is evidence of induction, because no host bone is nearby to supply bone‑forming cells by osteoconduction.
Authors' conclusion
The process is followed immediately by new-bone formation by autoinduction in which both the inductor cells and the induced cells are derived from ingrowing cells of the host bed.