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Biomedical subjects

P M Hendel

Publications and source records attributed to P M Hendel.

11 recordsLinked to original sources
PubMed1989

Projection geometry and stress-reduction techniques in craniofacial surgery.

Since 1981, we have been able to modify the mathematical patterns of projection geometry to reshape the skull in craniofacial surgery. Unlike burring, morcellization, rotation, and plate switching, this technique actually changes the shape of individual sections of the skull by changing their radius of curvature. The technique is an adaptation of the principles used by engineers to build complex structures such as ships' hulls, airfoils, and domes. The result is a rigid form of the desired shape that becomes permanent with healing. This has several advantages: 1. An increase in the level of safety of craniofacial procedures for remodeling the skull. This is so because there is no need to dissect normal areas as in the standard plate-switching techniques. 2. Decreased operating room time. 3. An increased range of surgical manipulations. No longer is the surgeon limited to the shape of the material present. 4. Relief of edge pressure on the frontal lobes during scalp closure. 5. Creation of a solid bony form over which the pericranial scalp flap can be draped to form new layers of bone.

Bone and Bones↗
PubMed1985

The harvesting of cranial bone grafts: a guided osteotome.

A technique for in situ harvesting of the outer table of the skull using a "guided" osteotome is presented. While guards have been placed to control the depth of the blade, additional steps are advised to ensure the highest level of safety in clinical use: Before harvesting the graft, a full set of anteroposterior and lateral x-rays should be examined to determine which areas of the skull are thin and should be avoided. All areas with cranial sutures should be avoided because here the dura is more firmly attached to the inner table making perforation more dangerous. Bone should not be harvested under the hairless forehead region because this results in a visible depression. The surgeon should use the guards as guides to visually monitor the depth of the blade. The surgeon should not attempt the procedure without having a set of three different depths (1 mm, 2 mm, and 3 mm) available. Different skulls have different thicknesses of the outer table, and the technique loses the advantage of safety if an inappropriate depth is used.

Humans↗
PubMed1984

A permanent tendon-to-bone suture technique in the distal phalanx.

This technique is used to place a permanent tendon-to-bone suture in the distal phalanx without increasing the amount of dissection beyond that needed for a Bunnell button repair. This technique has the advantage of greater strength without the problems of a percutaneous device that must be removed before full wound healing strength has developed.

Fingers↗
PubMed1983

A study of the pharmacologic control of blood flow to acute skin flaps using xenon washout. Part I.

This study was undertaken to understand the control mechanisms differentiating circulation to normal skin and acute skin flaps. The approach was to compare the effects of systemic vasoactive drugs on skin blood flow in rats in acute skin flaps and identical areas of control skin. With this model it was felt that systemic changes would affect both areas equally and any difference in response would be due to vascular control mechanisms unique to the flap. Xenon washout by percutaneous injection was chosen to measure blood flow. The results of over 8000 observations in these studies were: 1. Vasodilation enhances blood flow and flap survival. 2. Vasoconstriction decreases blood flow. 3. Depletion of sympathetic nerve terminals enhances blood flow and flap survival. 4. The acute flap is less sensitive to systemic alpha-agonists than control skin. 5. The acute flap is less sensitive to vasodilators acting at the receptor-site level than control skin. 6. Total sympathetic denervation does not occur. 7. Biologic increases in area of flap survival did occur in drug dose ranges predicted by xenon washout measurements in this model. These findings indicate that the vessels in an acutely raised skin flap have a greater vasospastic tone than is optimal for maximum nutrient blood flow. One explanation consistent with these findings is offered in which the mechanism responsible for this tone is the release of catecholamines from the sympathetic nerve terminals after the flap has been raised.

Animals↗
PubMed1983

A study of the pharmacologic control of blood flow to delayed skin flaps using xenon washout. Part II.

These experiments indicate that there are two components to the delay phenomenon. The first component is passive vasodilation owing to loss in the acute flaps originating from the sympathetic nerve terminals. The second component is active vasodilation not involving loss of a second vasoconstrictor mechanism or sensitization of the beta-receptors. Overall, the increase in blood flow associated with the delay phenomenon was seen to begin near the base of the flap and proceed distally. While the second component could not be identified, its characteristics suggest that its site of action is directly at the smooth-muscle or vascular-architecture level without involving the beta-receptors for vasodilation.

Adrenergic alpha-Agonists↗
PubMed1982

The functional vascular anatomy of rib.

The adequacy of nutrient blood supply to ribs based on the intercostal-periosteal system versus the medullary nutrient artery was investigated in six dogs containing ribs of each type. Free grafts with periosteum and without periosteum were also included. Vascularity was monitored by bone scanning and tetracycline double labeling. A preliminary study with RES scanning using sulfur colloid was also preformed. The results of this study showed (1) that no demonstrable difference in blood supply exists between rib supplied by the anterior intercostal-periosteal system versus the nutrient artery (this was seen with bone scans, tetracycline double labels, and RES scans); (2) that bone scans can differentiate between vascularized rib grafts and free rib grafts for at least the first 7 days (after 7 days, some free grafts begin to take up label); and (3) that by using bone scan, no difference in the rate of revascularization is detected between free grafts with the periosteum stripped or the periosteum intact (RES scans and tetracycline labeling were not given late enough after surgery to be incorporated in either type of nonvascularized graft).

Animals↗
PubMed1979

Avascular necrosis of bone following revascularization of the thumb.

A 35-year-old man underwent revascularization of a thumb transected through the base of the proximal phalanx after sharp division of all structures except a bridge of dorsal skin 1 cm wide. The digit survived. Avascular necrosis of the bone of the distal segment of the proximal phalanx was evident at 4 weeks and maximal at 9. Avascular necrosis did not occur in the distal phalanx. Roentgenographic changes indicated revascularization initially at the distal end of the phalanx, progressing proximally. Revascularization was first evident subperiosteally and progressed centrally; it was complete at 31 weeks. Fracture healing was delayed-evident at 17 weeks and complete at 27 weeks after injury. Avascular necrosis of bone may be the cause of delayed union or nonunion of bone cited in recent long-term reviews of successfully replanted digits. Measures should be taken to monitor, minimize, and compensate for this complication.

Adult↗
PubMedDate not supplied

Use of a tilted double clamp in microvascular anastomosis.

A tilted or angulated double microvascular clamp is described that, when applied to the vessels to be anastomosed, presents the vessel ends angulated upward facing the surgeon, so that the initial suturing of the posterior wall can be completed without rotating the vessel. Such a clamp is valuable in clinical situations where space is limited and where conventional double clamps cannot be rotated in the usual fashion.

Constriction↗