Biomedical subjects

C T Vangsness

Publications and source records attributed to C T Vangsness.

45 records · Page 3Linked to original sources

PubMed1989

Tibial shaft fractures treated with functional braces. Experience with 780 fractures.

We have reviewed our recent results with functional bracing of tibial shaft fractures in adults in order to define its role in management. We also analysed several parameters of these fractures to discover those which influence healing. A total of 780 tibial fractures treated in prefabricated functional braces were followed to union; shortening of less than 10 mm and angulation of less than 5 degrees in any plane were our parameters for successful treatment. The average time before applying a brace was 3.8 weeks for closed fractures and 5.2 weeks for open ones. Closed fractures healed in an average of 17.4 weeks and open fractures in an average of 21.7 weeks, 90% of them with 10 mm of shortening or less. Varus angulation and posterior angulation were the most common deformities encountered at union. There were 20 nonunions (2.5%) and 46 braces were discontinued during treatment. We found no association between fracture healing and the patient's age, the mechanism of injury or the fracture location. The degree of soft tissue injury appeared to have most influence on the speed of fracture healing. Fracture comminution and initial displacement, the condition of the fibula and the time from injury to bracing also appeared to affect the speed of union.

Adolescent↗

PubMed1989

The carbon dioxide laser. A potential tool for orthopedic surgery.

Arthroscopic laser surgery was performed in 325 knee joints between January 1985 and August 1988 with no significant lasting complications. The CO2 laser is especially effective in the "tight knee" for high surface area, low volume lesions, and chondromalacia. Arthroscopic laser surgery is also being performed as part of a multicenter study. Although the results are satisfactory to date, the use of the laser on the spine and joints other than the knee and for PMMA removal is experimental.

Ankle Joint↗

PubMed1981

In vitro evaluation of the loosening characteristics of self-tapped and non-self-tapped cortical bone screws.

The heads of self-tapping and non-self-tapping screws in dog femurs were exposed to a cyclic shearing force of 110 N for 200 loading cycles. This cyclic shear loading created a decrease in pull-out strength for both screw types of approximately 11% (p less than 0.01). No statistically significant difference in pull-out strength was found between screw types either before or after cyclic loading. A linear relationship between pull-out force and cortical thickness was observed for both screw types. These tests corroborated past work which showed equal holding power for the self-tapping and non-self-tapping screw. The progressive loosening of the screws with cyclic shear loading was accompanied by increasing load-displacement hysteresis and screw head migration. Greater hysteresis suggested that the non-self-tapping screw might have loosened more than the self-tapping screw from this applied loading schedule. Bone microcracking around screw threads before and after cyclic loading was observed by scanning electron microscopy. Photomicrographs of one non-self-tapping screw type and two self-tapping screw types showed microcracks at the tip of the outer diameter of the screw thread. More microcracks were observed after application of cyclic shear loading.

Bone Screws↗

PubMedDate not supplied

Survey of health care coverage of high school football in southern California.

We surveyed 240 high schools about various aspects of the health care coverage of their football athletes. Approximately 70% of these schools had team physicians, and more than one third of these had more than 1 team physician. Seventy-two percent of high schools had physician coverage for scheduled games. Practices and scrimmages were not covered. Sixty-nine percent of the schools reported having an athletic trainer for home games. Basic equipment was often lacking. Recording and tracking of athletic injuries were inconsistent. An overall team approach for medical coverage was noted. Concern was raised about adequate physician or medical coverage with emphasis on greater input from the school administration, community hospitals, and physicians.

California↗

PubMedDate not supplied

Gamma irradiation: effects on biomechanical properties of human bone-patellar tendon-bone allografts.

Sixty 10-mm bone-patellar tendon-bone allografts from young human donors were placed into four test groups, a control fresh-frozen group and three fresh-frozen irradiated groups. The irradiated groups were exposed to 2.0, 3.0, or 4.0 Mrad of gamma irradiation. The specimens were tested to tensile failure. The initial biomechanical strength of fresh-frozen allografts was reduced up to 15% when compared with fresh-frozen controls after 2.0 Mrad of irradiation. Maximum force, strain energy, modulus, and maximum stress demonstrated a statistically significant reduction after 2.0 Mrad of irradiation (P < 0.01). Stiffness, elongation, and strain were reduced but not with statistical significance. A 10% to 24% and 19% to 46% reduction in all biomechanical properties were found after 3.0 (P < 0.005) and 4.0 (P < 0.0005) Mrad of irradiation, respectively. After irradiation with a 4.0 Mrad dose, the ultimate load was below that of reported values for the human anterior cruciate ligament. It is clinically important to observe and document changes in human ligaments that result from currently used doses of gamma irradiation. The results from this study provide important information regarding the initial biomechanical properties of fresh-frozen human bone-patellar tendon-bone allografts after bacterial sterilization with gamma irradiation. The current accepted dose for sterilization is between 1.5 and 2.5 Mrad. There appeared to be a dose-dependent effect of irradiation on all the biomechanical parameters studied. Four of seven parameters were found to be reduced after 2.0 Mrad of irradiation. Reductions were found in all parameters after 3.0 and 4.0 Mrad of irradiation.

Biomechanical Phenomena↗

PubMedDate not supplied

Soft tissue for allograft reconstruction of the human knee: a survey of the American Association of Tissue Banks.

With increasing use and availability of musculoskeletal soft tissue allografts, orthopaedic surgeons need current knowledge about allograft processing, costs, and availability. In conjunction with the American Association of Tissue Banks, a comprehensive survey consisting of specific questions on several topics in tissue banking was sent to 42 member banks or banks undergoing accreditation review that distribute musculoskeletal tissues. Donors came from organ procurement organizations, coroners' offices, hospital morgues, and donations; the average age of the donors was 35. Most of the 36 tissue banks responding to the questionnaire harvest patellar and Achilles tendons. Patellar tendon demand exceeded supply. Tissue processing was done by outside organizations approximately 50% of the time. Of the four types of tissue sterilization processes performed, gamma irradiation was the most common. Doses of sterilizing gamma irradiation varied from 1 to 3.5 mrad. The average approximate costs of fresh-frozen tissue were $800 for patellar tendon allograft, $615 for Achilles tendon, and $640 for menisci. There was no consensus of opinion of how to size or sterilize meniscal allografts. As demand increases for soft tissue allografts, it is essential that the orthopaedic surgeon is knowledgeable about the clinical impact of tissue banking.

Adolescent↗

PubMedDate not supplied

Upper extremity blood flow in collegiate and high school baseball pitchers A preliminary report.

The arterial and venous volume blood flow in the dominant and nondominant upper extremities of five male pitchers, ages 16 to 21, was measured using color flow duplex ultrasound. Blood-flow measurements were obtained at baseline, after warm-up, and after each sequence of 20 pitches until 100 pitches were thrown. Blood flow was additionally determined 1 hour after the last pitch. The velocity of each pitch was recorded with a speed gun. Anthropomorphic measurements of the upper extremity were obtained at baseline and immediately after Pitch 100 using a standard measuring tape. The highest average arterial volume flow in the pitching arm occurred after 40 pitches, reaching a peak of 549 ml/min (56% increase from baseline). Thereafter, the average arterial blood flow steadily declined, reaching an average of 402 ml/min after the 100th pitch (14% increase from baseline). In contrast, the arterial blood flow in the nonpitching arm increased only slightly from baseline, reaching a maximal volume flow of 448 ml/min immediately after the warm-up period (10% increase from baseline). The volume flow then persistently fell to a level 30% below baseline after the 100th pitch. Although this small pilot study does not demonstrate causation between a decline in pitching performance and arterial blood flow, it suggests arterial flow in the dominant extremity falls as the pitch count increases.

Adolescent↗

PubMedDate not supplied

Isometry of the posterior cruciate ligament. Effects of functional load and muscle force application.

The effects of functional load and muscle force application on isometry of the posterior cruciate ligament were determined. Eight fresh-frozen cadaver knees were mounted in a custom-designed rig. A full range of motion and muscle forces were applied through the quadriceps, hamstring, and gastrocnemius tendons during a simulated static squat maneuver. The low-load isometric posterior cruciate ligament point was located 5.63 mm proximal and 0.18 mm anterior to the anatomic center of the posterior cruciate ligament origin on the femur. The high-load state, with no gastrocnemius and hamstring muscle forces applied, shifted the isometric point 6.32 mm proximal and 6.72 mm anterior (P < 0.05). Loading the hamstring and gastrocnemius muscles also shifted the isometric point (P < 0.05). This study indicated that the most isometric region of the posterior cruciate ligament femoral attachment changed significantly when functional loads and muscle forces were applied to the knee. This finding may have implications for both surgical reconstruction and rehabilitation of the posterior cruciate ligament-injured knee.

Cadaver↗

PubMedDate not supplied

The effects of laser-induced collagen shortening on the biomechanical properties of the inferior glenohumeral ligament complex.

The purpose of this study was to determine the effects of laser-induced collagen shortening on the biomechanical properties of the inferior glenohumeral ligament complex. Fifty-seven bone-ligament-bone specimens underwent uniaxial tensioning to 10% strain. Approximately half of the specimens then underwent 10% shortening by lasing using a holmium:yttrium-aluminum-garnet laser. Both groups were again tensioned to 10% strain, and then loaded to failure. Ultimate strain and yield strain were significantly higher in the lased specimens than in the nonlased specimens. No significant difference was found for ultimate stress, yield stress, or elastic modulus between the two groups. Failure of the ligament did not appear to occur in the lased areas. The load-to-failure results suggested that the strength of the ligament complex was not significantly compromised by this lasing protocol.

Aged↗