Biomedical subjects

G T Lin

Publications and source records attributed to G T Lin.

30 records · Page 2Linked to original sources

PubMed1996

Mechanical property analysis of small bone fixators.

The purpose of this study is to establish a database and to compare mechanical properties between various types of small bone fixators. Hollow maple dowels are uniformly produced to simulate small bones in this study. Furthermore, transverse osteotomy, transverse osteotomy with 2 mm gap, and 45 degrees oblique osteotomies are created to simulate stable, unstable, and spiral fractures. Each fracture pattern is then approximated with four types of fixators: (1) Aesculap mini external fixator, (2) mini A-O plate and screw, (3) cross pin, and (4) self-assembled mini external fixator. Finally, tension, torsion, and bending tests are performed with INSTRON. In three different fracture patterns, dorsal plating has the strongest tensile rigidity and lateral bending rigidity. In stable and unstable fractures, Aesculap mini external fixator has the strongest torsional rigidity. However, mini A-O plate has the strongest torsional rigidity in 45 degrees oblique fractures. In stable fractures, dorsal plating, lateral plating, and mini external fixator all have good anterior bending rigidity without significant differences. Nevertheless, only lateral plating and mini external fixator show good anterior bending rigidity in unstable and 45 degrees oblique fractures. Except in torsional rigidity, Aesculap mini external fixator is not significantly stiffer than the self-assembled external fixator. As expected, cross pin is the weakest fixator. Differences in mechanical stiffiness between the four types of small bone fixators are provided in this study. Additionally, one should also consider the indication when choosing a proper fixator. Complication rate can then be lowered to achieve successful surgery in treating small bone fractures.

Bone Substitutes↗

PubMed1992

Comparative flexor tendon excursion after passive mobilization: an in vitro study.

Two experimental studies were conducted to investigate flexor tendon excursions. In the first study, tendon excursions due to passive joint motion in various loading condition were evaluated. In the second study, the efficacy of a new technique that used synergistic wrist motion (S-splint) was compared with the traditional dorsal splinting methods: the Kleinert splint (K-splint) and the Brooke Army Hospital/Walter Reed modified Kleinert splint with a palmar bar (P-splint). The results of these studies question the anticipated tendon excursion associated with postoperative splinting. They demonstrated that the measured tendon excursion under a condition of low tendon tension was almost half that of theoretically predicted values. In zone II, the magnitude of excursion introduced by the three mobilization methods were in descending order: S-splint, P-splint, K-splint (p less than 0.05). Differential tendon excursion between the flexor digitorum profundus and the flexor digitorum superficialis had a mean value of 3 mm and was not significantly different among the three methods. Passive proximal interphalangeal joint motion was the most effective means of providing increased amplitude of tendon gliding in zone II. Passive distal interphalangeal joint motion did not increase excursion in zone II as much as had been predicted.

Cadaver↗

PubMed1992

Microsurgical replantation of avulsed scalp--two cases report.

Two female patients with scalp avulsion were treated successfully by microsurgical replantation. The first patient suffered an avulsion of the right half of scalp and which survived fully after replantation. The second patient suffered avulsion of the entire scalp as well as the forehead skin and nape of the neck. Almost all of the avulsed part survived except partial skin loss in the posterior neck and left occipital area. Only one temporal artery and one vein was anastomosed in each case. Near normal hair growth recurred in both cases.

Adult↗

PubMed1991

Digital skin bloodflow of patient rested on different positions--a laser Doppler study.

Brachial plexus injuries resulting from malposition of the patient during general anesthesia have been described in the medical literature for nearly a century. However, concerning the brachial vessels which were accompanying the nervous plexus, few papers can be found discussing the changes that also occur when malpositing. In this study, an attempt was made to measure changes of digital skin bloodflow among patients resting in different postures simulating the operating postures in orthopaedic surgery. Laser doppler was found to be a sensitive indicator of skin bloodflow and peripheral vascular diseases. The results show that axillary pad used with patients resting in decubital positions does not change digital skin bloodflow or elbow flexion which could serve to reduce nervous tension among those patients whose digital skin bloodflow remains unchanged by hyperabductive shoulder positions. These findings do not support the preferred shoulder positions which are suggested in most papers discussing brachial plexus. From this it may be concluded that digital bloodflow is not occluded in healthy persons either by body postures or by the positions of the shoulders and elbows.

Adult↗

PubMed1991

Healing potential of experimental meniscal tears in the rabbit. Preliminary results.

This study assessed the healing potential of longitudinal or transverse incisions in the peripheral, central, and inner rim regions of rabbit medial menisci. Longitudinal and transverse incisions were made in 48 male New Zealand white rabbits. The incisions were either repaired with sutures or left open. The effect of joint motion on repair was also evaluated. In one group, longitudinal incisions were made in the peripheral, central, and inner rim regions of the meniscus. Some of these incisions were sutured, whereas others were not repaired. In another group, transverse incisions were made in the meniscus, extending from the inner rim to the middle of the meniscus or to the peripheral attachment (radial tear). Again, the lesions were left open or repaired. The effect of joint motion on healing was assessed by immobilizing several knees from each group with Kirschner wires temporarily for ten weeks. Suture of the meniscus incision did not substantially affect the rate of healing. When the healing rates of menisci at the periphery, body, and rim were compared, incisions at the periphery healed significantly better than incisions at the meniscal body and central rim regions. K-wire immobilization did not substantially affect the rate of healing. The difference in healing with regard to the type of incision, either longitudinal or transverse, was not statistically significant.

Animals↗

PubMed1990

Mechanical properties of human pulleys.

In order to determine the mechanical properties of the fibro-osseous pulleys in the hand, the diaphyseal annular pulleys, the volar plate annular pulleys and the cruciate or condensable portions were tested. A custom-made loading device provided proper fit of the soft tissues for a uniform distribution of the pulley load during testing. The A2 pulley was found to be the strongest of the pulleys; the A1 and A4 were the next strongest. The A3 pulley was nearly equal in mean breaking strength to the other annular pulleys, but in absolute breaking load was considerably weaker because of its shortness. The A4 was the least compliant of the pulleys. We concluded that the fibro-osseous A2 and A4 were mechanically stronger and stiffer pulleys than the A1, A3, A5 (volar plate) pulleys. In testing one type of pulley reconstruction, we found that the "belt loop" technique of Karev nearly matched the annular pulleys in strength and energy absorption.

Biomechanical Phenomena↗

PubMed1989

Biomechanical analysis of finger flexor pulley reconstruction.

Fifty cadaver digits were used to study the mechanical properties of five different methods of pulley reconstruction and the effectiveness of three different pulley reconstructive arrangements in restoring a normal relationship between tendon excursion and joint motion. All reconstructed pulleys showed less stiffness and more displacement before failure than normal intact pulleys. Although reconstruction using a length of another tendon woven through the remaining fibrous rim of the pulley and both double and triple tendon graft loops around bone absorbed more energy to failure than a normal pulley, only the triple loop around bone could withstand as much load before failure as a normal pulley. No reconstruction restored a normal tendon excursion/joint motion relationship, but reconstruction of the A2 and A4 pulleys restored a more normal relationship than either the "belt loop" reconstruction or a combination belt loop, A2 and A4 reconstruction.

Biomechanical Phenomena↗

PubMed1989

Functional anatomy of the human digital flexor pulley system.

The anatomy of 55 cadaver digits was studied, both statistically and with simulated active motion using weights attached to the flexor tendons. The modified description of Doyle and Blythe accurately described the anatomy observed. Serial pulley sectioning showed two types of bowstringing, both of which affected the relationship of tendon excursion to joint motion. The most constant, resulting in 15% loss of motion for a fixed tendon excursion, occurred over the concave surfaces of the proximal and middle phalanges. Bowstringing at the proximal interphalangeal joint was present only after 30 degrees of flexion had occurred, because of the convexity of the phalangeal condyles.

Anthropometry↗

PubMed1988

Biomechanical studies of running suture for flexor tendon repair in dogs.

A new running-locking loop suture technique has been developed to increase tendon repair strength and to provide better tendon edge inversion. Biomechanical analysis documented the failure mechanism and the failure strength of various circumferential repair techniques. When compared with two well-known techniques, the simple circumferential running suture and Lembert running suture, the locking suture technique was shown to have 3.77 and 1.68 times greater tensile failure strength and 1.73 and 1.26 times greater stiffness than these traditional suture methods. A running peripheral locking suture may help augment the strength of tendon repair.

Animals↗

PubMed1988

The holding technique for flexor tendon repair.

This paper introduces a technique for tendon holding during tendon repair. A segment of rubber glove is used to wrap severed tendon ends, is clamped at one side by a curved mosquito hemostat, and then is transfixed with a needle. All the items are readily available in any operating room or emergency room. The elasticity of the rubber loop provides steady holding power without doing damage to the outer surface of the tendon.

Finger Injuries↗

PubMed1984

Nasal alar reconstruction with free "accessory auricle".

A case of basal cell epithelioma of the nasal ala is presented that was managed by local excision of the tumor. The alar defect was reconstructed by a microvascular accessory auricle with excellent outcome.

Basal Cell Carcinoma↗

PubMedDate not supplied

Ultrasonographic study of the coexistence of muscular torticollis and dysplasia of the hip.

The consistent relationship between congenital muscular torticollis and dysplasia of the hip is now widely accepted. However, the coexistence rate of these two disorders has been reported with variations from 0 to 20%. To obtain a more accurate coexistence rate, ultrasound scanner was used as the diagnostic tool for both of these disorders.Sixty-three children (30 boys and 33 girls) younger than 6 months who had undergone ultrasound scanning of both bilateral sternocleidomastoid muscle and bilateral hips were included in this study. Forty-seven children were confirmed to have muscular torticollis, and the remaining 16 cases were diagnosed as postural torticollis. Only these 47 cases were included for analysis of the coexistence rate. Eight children were found with dysplasia of the hips associated with muscular torticollis, which included Graf's type IIa for four hips, type IIb for two hips, type IIIa for one hip, and type IIIb for one hip. From the results of the present ultrasonographic study, the coexistence rate of congenital muscular torticollis and dysplasia of the hip was concluded to be 17%. If only those dysplastic hips (type IIb, IIIa, IIIb) that required treatment were included, the coexistence rate would be lowered to 8.5%.

Female↗