Langerʼs Lines: To Use or Not to Use
ABSTRACT Thirty-six differently named guidelines have developed as surgeons have searched for an ideal guide for elective incisions. Many surgeons prefer Langer's lines. These lines were developed by Karl Langer, an anatomy professor, from cadavers in rigor mortis. However, Kraissl preferred lines oriented perpendicular to the action of the underlying muscles. Later, Borges described relaxed skin tension lines, which follow furrows formed when the skin is relaxed and are produced by pinching the skin. However, these are only guidelines; there are many contributors to the camouflaging of scars, including wrinkle and contour lines. Borges's and Kraissl's lines (not Langer's) may be the best guides for elective incisions of the face and body, respectively.
- SourceAvailable from: Stephen Boppart
[Show abstract] [Hide abstract]
- "Langer's lines describe the patterns of biomechanical anisotropy in human skin. Directions within skin and along (parallel to) Langer's lines have the least flexibility (highest Young's modulus ) . We chose the volar forearm for these measurements because the Langer's lines are easily defined at this site to be parallel to the long axis of the arm . "
ABSTRACT: Dynamic optical coherence elastography is used to determine in vivo skin biomechanical properties based on mechanical surface wave propagation. Quantitative Young's moduli are measured on human skin from different sites, orientations, and frequencies. Skin thicknesses, including measurements from different layers, are also measured simultaneously. Experimental results show significant differences among measurements from different skin sites, between directions parallel and orthogonal to Langer's lines, and under different skin hydration states. Results also suggest surface waves with different driving frequencies represent skin biomechanical properties from different layers in depth. With features such as micrometer-scale resolution, noninvasive imaging, and real-time processing from the optical coherence tomography technology, this optical measurement technique has great potential for measuring skin biomechanical properties in dermatology.IEEE transactions on bio-medical engineering 10/2009; 57(4):953-9. DOI:10.1109/TBME.2009.2033464 · 2.23 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Biomechanical properties are important for living tissues and cells. They are indicators of functional changes and pathological variations in the micro-structure, such as during tumor development. The topic of this thesis falls at the intersection of biomechanics and optical imaging, and focuses on optical elastography, an optical sensing and imaging technique used to measure biomechanical properties at the tissue and cell levels. Optical coherence elastography, multiphoton elastography, and magnetomotive microscopy are developed, demonstrated, optimized, and applied at the tissue level to ex vivo breast cancer and in vivo skin, and at the cellular level to mouse macrophages in culture. Driven by scientific needs to engineer new quantitative methods that utilize the high micro-scale resolution achievable with optics, results of biomechanical properties were obtained from the biological samples. The results suggest potential diagnostic and therapeutic clinical applications. Results from these studies also help our understanding of the relationship between biomechanical variations and tissue/cell functional changes in biological systems. Therefore, the engineering of imaging techniques is employed to investigate biomechanics, as well as the feasibility for using these techniques to solve more scientific and clinical questions.
Conference Paper: Strictly Observable Linear Systems[Show abstract] [Hide abstract]
ABSTRACT: The rudimants of the module theoretic approach to linear system theory are briefly reviewed. Two types of integer invariants of systems are mentioned: the reduced reachability indices, and the latency indices. The reduced reachability indices are related to the problem of reducing a system through the application of causal precompensation. The latency indices are related to the problem of causal factorization of one system over another.Decision and Control, 1982 21st IEEE Conference on; 01/1983