Clinical orthopaedics and related research
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Clin. Orthop. Relat. Res. · Oct 1998
Comparative StudyStrain rate and timing of stimulation in mechanical modulation of fracture healing.
Fracture of the long bones results in a repair process that has the potential to restore the anatomic morphology and mechanical integrity of the bone without scar tissue. The repair process can occur in two patterns. In the first, under conditions of rigid stabilization, direct osteonal remodeling of the fracture line can occur with little or no external callus, a process known as direct bone repair. ⋯ The beneficial effect of this particular biophysic stimulus early in the healing period may be related to the viscoelastic nature of the differentiating connective tissues in the early endochondral callus. In the early endochondral callus, high rates of movement induce a greater deformation of the fracture fragments because of the stiffening of the callus. Alternatively, the transduction pathway may involve streaming potentials as a result of the high movement rate.
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Laboratory and clinical scientists and practicing clinicians need definitions of union, delayed union, and nonunion. Fracture union is a gradual process, so quantitative measures are the most meaningful. However, end point definitions also are useful, but they need empirical validation. ⋯ These observations suggest a more rational approach to the definition of union, delayed union, and nonunion than that provided by the selection of arbitrary times. For conservatively treated fractures at least, delayed union can be defined as the cessation of the periosteal response before the fracture successfully has been bridged. Nonunion is the cessation of both the periosteal and endosteal healing responses without bridging.
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Clin. Orthop. Relat. Res. · Sep 1998
Computer assisted orthopaedic surgery. Image guided and robotic assistive technologies.
Technologies are emerging that will influence the way in which orthopaedic surgery is planned, simulated, and performed. Recent advances in the fields of medical imaging, computer vision, and robotics have provided the enabling technologies to permit computer aided surgery to become an established area which can address clinical needs. ⋯ The goals of these new clinically focused technologies are to develop interactive, patient specific preoperative planners to optimize the performance of surgery and the postoperative biologic response, and develop more precise and less invasive interactive smart tools and sensors to assist in the accurate and precise performance of surgery. The medical community is beginning to see the benefit of these enabling technologies which can be realized only through the collaboration and combined expertise of engineers, roboticists, computer scientists, and surgeons.
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Elbow arthroplasty most commonly is performed through a posterior approach by detaching or reflecting the triceps off the olecranon. Surgical approaches to the elbow joint that dissociate the triceps from the olecranon have distinct disadvantages. ⋯ To avoid these complications a modified posterior approach to the elbow joint that preserves the triceps muscle insertion on the olecranon was used in 10 consecutive elbow arthroplasties. This method provides adequate exposure, allows early rehabilitation, and avoids triceps weakness.