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Biomedical subjects

T K Liu

Publications and source records attributed to T K Liu.

At least 37 records · Page 2Linked to original sources
PubMed1996

Ultrastructural studies on myofibrillogenesis and neogenesis of skeletal muscles after prolonged traction in rabbits.

Little is known about the morphological response of muscle after long term traction. The purpose of this study was to investigate the morphological changes of skeletal muscle during limb lengthening. After application of mini-extraskeletal fixator, the hindlimb of New Zealand white rabbit was osteotomized and then slowly lengthened at the rate of 1 mm/day up to a 20 mm gain in length. The muscles of hindlimbs were perfused and dissected. Morphological studies were performed at electron microscopic level. Transmission electron microscopy revealed foci of microtrauma at the myotendinous junction. The distance between the muscle fibers and tendon parenchyma increased, with numerous primitive mesenchyme-like cells interposed within this gap. The cytoplasmic space of these cells was devoid of myofibril formation at the ends of stretched fibers. Within the satellite near the myotendinous junction myofilament production was observed in various gradations of maturation. It is concluded that myofibrillogenesis with traction neogenesis of skeletal muscle during limb lengthening does exist and occurs mainly near the myotendinous junction. The myotendinous junction in mature skeletal muscle actively participated in the process of limb lengthening.

Animals↗
PubMed1995

Periprosthetic bone mineral density of the distal femur after total knee arthroplasty.

Evaluation of the bone mineral density (BMD) was performed in the distal femur around the femoral component of a total knee prosthesis. A total of 48 females were enrolled for this study, including 14 with osteoarthritis of one knee undergoing total knee arthroplasty (TKA) with an Osteonics prosthesis, 14 with osteoarthritis of one knee undergoing TKA with a Whiteside prosthesis, and 20 age-matched normal controls. The BMDs of both knees were measured before operation, and then at 3, 6 and 12 months after operation. The preliminary results demonstrate a significant progressive decrease of BMD in the distal femur of the operated knees after TKA, whereas the BMD of the non-operated knees remains stable. The ratio of BMD between the operated femur and the non-operated femur began to decrease 6 months after operation, and was most obvious at the end of the first year (ranging from 7% to 27%). Further investigation is essential to determine the clinical significance of this loss of periprosthetic bone.

Absorptiometry, Photon↗
PubMed1995

Contact areas and pressure distributions in the subtalar joint.

We investigated how foot position and ankle arthrodesis affect the contact characteristics of the subtalar joint. Nine fresh-frozen specimens of amputated lower legs were used. Pressure-sensitive films were inserted into the anterior and posterior articulation of the subtalar joint. The contact areas and pressure for various foot positions and under axial loads of 600, 1200, and 1800 N were determined based on the gray level of the digitized film. In neutral position and under a 600 N load, the maximum contact pressure in the subtalar joint was 5.13 +/- 1.16 MPa. The contact area (1.18 +/- 0.35 cm2) was only 12.7% of the whole subtalar articulation area (9.31 +/- 0.66 cm2), and the total force (348.5 +/- 41.7 N) transmitted via this contact area was about 58% of the applied load (600 N). Dorsiflexion of the foot increased the contact area and the force transmitted, but decreased the average contact pressure in the subtalar joint, while the reverse occurred in plantar flexion. Eversion increased the subtalar contact stress, whereas inversion up to 10 degrees decreased it. Ankle joint arthrodesis shifted the contact areas in the subtalar joint posteriorly in all inversion/eversion positions. Moreover, total force transmitted through the subtalar joint as well as the contact pressure increased.

Adult↗
PubMed1995

The center of ground reaction force during lifting.

The center locations of the ground reaction force were estimated when subjects assumed upright and bending postures as well as when they lifted at low and high speeds. Ten subjects participated in this study and were instructed to assume two postures and to perform two liftings sequentially in a random order. The center locations of the ground reaction force were calculated using a Computerized Dyno Graphic system (INFOTRONIC). The center of the ground reaction force in the full bending posture had a more anterior location than it did in the upright standing posture. When measured during the lifting activity, the center of the ground reaction force shifted forward and then backward during the whole activity. The center location shifted to a more anterior location during high-speed lifting than it did during low-speed lifting.

Adult↗
PubMed1994

The acute metabolic effects of oral tricalcium phosphate and calcium carbonate.

A double-blind study was performed to test the metabolic effects of tricalcium phosphate (TP) and calcium carbonate (CC) on serum calcium (SCa), serum phosphorus (SP), and immunoreactive intact serum parathyroid hormone (SPTH) levels in two groups of 24 subjects. The mean age of young subjects was 29.5 years, and elderly subjects, 65.9 years. These subjects fasted overnight for 12 hours, but with good hydration, before the tests. Following a 2-hour baseline-urine collection, 1200 mg elemental calcium (as CC or TP in tablet form) was chewed and ingested and 2-hour postload urines were collected. Blood was drawn immediately before and at 1, 2, and 4 hours after calcium load. The results showed that SCa and SP increased, whereas SPTH decreased with both preparations. The increment of SCa was similar after oral load of either calcium salt in both groups. The increment of SP after TP load was more than after CC. The urinary calcium/creatinine ratio (UCa/Cr) increased significantly after both preparations in the young group. The urinary phosphorus/creatinine ratio (UP/Cr) did not change significantly following TP, but decreased significantly after CC load in the young subjects. However, in the elderly individuals, the UP/Cr increased after TP load but did not change following CC, with statistical significance. The difference of urinary cyclic adenosine monophosphate/creatinine ratio (UcAMP/Cr) was not significant in both groups with either preparation. In summary, there was a similar rise in SCa and an equivalent fall in SPTH between TP and CC, in both young and elderly individuals.

Administration, Oral↗
PubMed1994

Predictors for wound healing in ischemic lower limb amputation.

Determination of the level of amputation of an ischemic lower limb presents a difficult problem. This prospective study evaluated parameter capable of predicting wound healing in patients with peripheral vascular disease. Forty-four amputations performed on 38 patients for advanced ischemia of a lower extremity were analyzed. Among them, 20 patients had diabetes mellitus and 10 received vascular reconstruction prior to the amputation. All patients except one had a skin temperature measurement and 26 patients had segmental blood pressure measurements before amputation. Of the 44 amputations, 31 healed successfully and 13 failed to heal without further intervention. Patients who had an amputation above the ankle joint had a significantly better outcome than those who had amputation below the ankle joint. Among the amputations proximal to the ankle joint, all patients with segmental blood pressures > 70 mmHg at the amputation level had successful wound healing, compared with only half of those patients with segmental pressures < 70 mmHg. However, ankle segmental pressure was not associated with the outcome of wound healing in the amputations distal to the ankle joint. The absolute skin temperature and the difference between the skin and ambient temperature were found to be poor predictors for wound healing. No significant differences were detected among the successes and failures with regard to the patient's sex, age, blood chemistry and duration of diabetes mellitus.

Adult↗
PubMed1994

Posterior slope angle of the medial tibial plateau.

The overall average of the posterior slope of the medial plateau of the tibia as determined from the lateral radiography of the knee was 10 degrees +/- 4 degrees, with a range from 0 degrees to 20 degrees. This value was independent of age and gender and was unaffected by arthrosis as long as the arcuate contours of the medial socket were not eroded and could be identified by lateral radiography. While the average value of this posterior slope was similar to that of a cadaveric study, the range was much greater. The current practice of neglecting the preoperative posterior tibial slope and arbitrarily setting the tibial component at a predetermined posterior tilt angle failed to take into account the wide variation in posterior tibial slope.

Adolescent↗
PubMed1994

Analysis of neogenesis in rabbit skeletal muscles after chronic traction.

After application of a modified Orthofix mini-extraskeletal fixator, the hind limb of New Zealand White rabbits was osteotomized and then slowly lengthened at a rate of 1 mm/day. After a 20 mm gain in length, the net weight and the length of muscular and tendinous portions were measured and histological examination was carried out in triceps surae muscles. Quantitative analysis showed a significant increase in the gained length of the muscular portion (28.05% to 30.65%). Histological studies of these lengthened muscles showed a generalized increase in cellularity with scanty inflammatory cell infiltration near the myotendinous junction. The increased cellularity is due to the presence of muscle precursor cells characterized by large, oval and pale-stained vesicular nuclei and two prominent nucleoli. The nuclei of these precursor cells were larger and more numerous near the myotendinous junction, and gradually changed into a flattened and more condensed form at a distance from the junction. Occasionally, chains of centrally-located nuclei of primitive myoblasts were also visible. It is concluded that traction neogenesis of the skeletal muscle during limb lengthening does exist and occurs mainly near the myotendinous junction.

Animals↗
PubMed1994

Effect of nerve function on the failure mechanism of the triceps surae muscle by passive extension in the rabbit.

The triceps surae muscle-tendon units of rabbits were tested in vivo by a passive extension technique using an MTS Bionix 858 machine. The effect of nerve function on the failure mechanism was evaluated. The sites of failure were always at the muscular portion near the musculotendinous (MT) junction. It always occurred within 0.1 to 1.0 mm of the distal MT junction of the soleus muscle and within 5 to 10 mm of the distal MT junction in the lateral head of the gastrocnemius muscle. In the medial head of the gastrocnemius muscle, it always occurred within 5 to 10 mm of the proximal MT junction. The loss of nerve function significantly reduced the peak force and the absorption of energy before the point of peak force, but it produced no significant changes in the failure length and the total energy absorption. The functioning nerve might have a protective mechanism which works on the muscle-tendon unit by increasing the peak force and the energy requirement before the muscle is injured.

Animals↗
PubMed1994

Magnetic resonance imaging of rotator cuff lesions.

The purpose of this study was to evaluate the diagnostic performance of magnetic resonance imaging (MRI) in rotator cuff diseases. Forty consecutive patients studied by MRI from September 1990 to September 1992 were included in the study. MRI was performed on a 1.5 tesla MR scanner. Each MRI study was reviewed by two radiologists experienced in rotator cuff tendons. The MRI finding was compared with the surgical result. MRI sensitivity for all tears (partial and complete) was 1.0 (22/22), specificity 0.89 (16/18), accuracy rate 0.95 (38/40), and the predictive value 0.92 (22/24). Signal changes of the rotator cuff tendon (primary signs) were the most reliable criteria in diagnosis of the tear. Changes of subacromial and subdeltoid fat planes and bursa (secondary signs) were complimentary when primary signs were indeterminant. The direction of the long axis of abnormal signal intensity in the rotator cuff tendon may be a good indicator when differentiating tears from tendinitis. We conclude that MRI shows excellent performance in the determination of the presence or absence of a rotator cuff tear.

Adolescent↗
PubMed1994

Epiphyseal scar of the femoral head: a three-dimensional anatomic observation.

The purpose of this study was to inspect the three-dimensional structure of the epiphyseal scar of the femoral head. Three adult human femoral head specimens with a dense epiphyseal scar shown by radiography were used to study the morphology of the scar. One femoral head was cut in the coronal plane to show the cross-section. A trabecular pattern in the femoral head was demonstrated by radiography. The second femoral head specimen, was cut by a wafering saw in a plane parallel to the epiphyseal scar into 1.5 mm thick slices. Microradiographs of these specimen slices were taken to trace the scar from the proximal part of the femoral head to its distal end. In the third specimen, the epiphysis was chipped away to uncover the whole epiphyseal scar for a topographic examination by dissecting microscope and scanning electron microscope. The epiphyseal scar was found to consist of multiple layers of plate-like bony structure capping the metaphysis similar to an inverted cup with a defect adjacent to the fovea. Differences between the trabecular pattern in the epiphysis and metaphysis were distinctive. These morphologic characteristics of the femoral head should be taken into account when investigating stress distribution in the femoral head.

Adult↗
PubMed1994

Treatment of malunion of the lower extremities by the Ilizarov technique.

From June 1989 to February 1992, 22 patients with post-traumatic malunion of the lower limbs were surgically treated by the Ilizarov technique in our hospital. Their average age was 23.0 years (range, 10.4-38.7 years). The average follow-up time was 35.7 months (range, 18-50 months). They were divided into group A (14 cases): those with post-traumatic shortening only (average shortening: 4.0 cm for the femur, 4.0 cm for the tibia) and group B (eight cases): those with combined post-traumatic shortening and angular deformity (average shortening, 4.6 cm for the femur, 2.7 cm for the tibia; average angulation, 17.1 degrees). After treatment by the Ilizarov technique, only one case had a residual leg length discrepancy of more than 1.5 cm. The average residual angular deformity in group B was 0.4 degrees. The therapeutic indexes in group B (53 days/cm for femur, 91 days/cm for tibia) were slightly longer than that in group A (46 days/cm for femur, 45 days/cm for tibia). In total, nine obstacles or complications were encountered in our 22 patients. Three of them required further surgical management. It is concluded that the Ilizarov technique provides excellent results in the treatment of lower-limb malunions with relatively few complications.

Adolescent↗
PubMed1994

Microfailure of peroneus longus muscle during passive extension.

To study the material properties of the skeletal muscle-tendion unit, the peroneus longus muscle of a rabbit, rubber and plastic materials were tested with on MTS machine. After anesthesia, the peroneus longus muscle of a rabbit was dissected out and then stretched to failure by an MTS Bionix 858 machine. The load-deformation curves of the muscle and non-biological materials were analyzed and compared. The results showed that the load-deformation curve of a muscle-tendon unit can be separated into 4 different portions: first, the viscoelastic portion, which corresponds to the physiological range of motion; second, the portion of microfailure; third, the portion of macrofailure; and fourth, the portion of rupture and separation of a muscle-tendon unit. The cause of these behaviors are explained by the presence of actinmyosin cross bridges. Elucidation of the existence of microfailure of skeletal muscle gives a good reference point to determine the functional capabilities and limitation of muscular tissue. This will be useful in determining the beneficial effect of stretch programs in sports and rehabilitation and preventing the potential impact of tissue injury.

Animals↗
PubMed1994

The excursion length of posterior cruciate ligament during range of motion in prosthetic knee.

Restriction of knee motion after total knee replacement was noted to be associated with lengthening of the posterior cruciate ligament during flexion of the knee which was replaced with a cruciate retaining knee prosthesis. The purpose of this study was to measure the excursion length of the PCL in the normal knee in four different cruciate-retaining knee prostheses, and in five cadaveric knees which were replaced with the Tricon prosthesis. For every knee, the tibial part was fixed on a stand and the femoral part was allowed to do flexion-extension motion upon the tibial plateau. The angle of the motion was monitored by the self-readout goniometer. A thin wire cord was attached to the proposed origin site of the PCL on the femur. The wire cord was passed through a tiny hook which was attached to the proposed insertion site of the PCL on the tibia and connected to a dial gauge. The excursion length of the PCL during 90 degrees flexion was measured. The same measurement was repeated five times in each cadaver knee and prosthetic knee studied, and in five knee specimens which were replaced with the Tricon prosthesis. The excursion length of the PCL during 0 degrees to 90 degrees of flexion in five cadaver knees averaged 0.08cm of lengthening. Three different origin sites of the ligament were designated to represent the anterior, middle and posterior part of the ligament.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗
PubMed1993

Staurosporine-induced morphological changes in the rat osteoblasts.

Treatment of cultured rat osteoblasts with staurosporine caused a rapid outgrowth of long slender cellular processes and the formation of stellate cells. The number of stellate cells increased with higher concentrations of and longer incubation with staurosporine. Scanning electron microscopy (SEM) revealed that the smooth surface of control polygonal cells became ruffled with many long slender cellular processes, thus increasing the cell surface area. Transmission electron microscopy (TEM) of the stellate cells showed a rich accumulation of large lipid droplets in the cytoplasm. Some lipid droplets had coalesced under the cytoplasmic membrane. We suggest that staurosporine has an effect on the differentiation of cultured rat osteoblasts.

Alkaloids↗
PubMed1993

Increased bone growth by local prostaglandin E2 in rats.

The effects of prostaglandin E2 (PGE2) on bone growth were investigated in rats. Daily injection of PGE2 (1, 10, and 100 pmol) was given via local intraosseous route into the metaphysis of the left tibia for 14 days. The contralateral right tibia injected with vehicle and saline was for the control. The rats receiving no injection provided as normal control. The results obtained indicated that PGE2 slightly but significantly decreased the body weight increment without effect on tibial length. The most prominent effect of PGE2 was the increase of metaphyseal bone trabeculae by 45-81% in a dose-dependent manner. The microscopic examination revealed that PGE2 unequivocally increased the new woven bone formation. The bone cell population study showed no difference between the number of osteoblasts and osteoclasts in primary spongiosa of the PGE2-injected limbs and those of contralateral limbs. However, the numbers of osteoblasts and osteoclasts were markedly increased in secondary spongiosa in the PGE2-injected limbs. This finding confirmed a stimulatory role of PGE2 in the bone formation. The local intraosseous injection of PGE2 was proven to be a good model for the study of local growth factors on bone metabolism with a lower effective dose which eliminates the systemic side effects.

Analysis of Variance↗
PubMed1993

Vascularized tendon graft using lateral arm flap. 5 microsurgery cases.

We treated 5 patients with soft tissue defects involving the skin and tendon with microsurgical transfer of vascularized tendon grafts from the upper lateral arm. All the flaps survived and recovery of motor function has been satisfactory. The advantages of a composite upper lateral arm flap are its versatility, constant anatomy, and skin sensibility.

Adult↗