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Biomedical subjects

F H Fu

Publications and source records attributed to F H Fu.

At least 145 records · Page 8Linked to original sources
PubMed1983

Long-term follow-up of the treatment of a family with nail-patella syndrome.

Patients with nail-patella syndrome have deformities of the elbows and knees which can cause bothersome symptoms requiring treatment. We have found in a small series of four patients that quadricepsplasties have been uniformly successful in treating recurrent subluxation or dislocation of the patella at 10-year follow-up. Radial head resection has been effective in relieving minor amounts of pain and eliminating the bump caused by the posteriorly dislocated head. The range of motion of the elbow and forearm has not been improved.

Adolescent↗
PubMed1981

Comparative assessment of the early mechanical integrity of repaired tendon Achillis ruptures in the rabbit.

The effectiveness of closed versus open management of Achilles tendon ruptures was studied in a series of 40 adult rabbits. Tensile test data of tendon repair specimens excised after 10 weeks of equinus cast immobilization revealed stiffness and strength deficits, relative to uninjured contralateral tendons, ranging from 70 to 88%. Although no statistically significant differences in these early tensile properties were noted among groups managed conservatively versus those treated openly, the closed management group healed with length increases more than three times those which resulted from suture repair. Apposition of a small, longitudinal polytetrafluorethylene (Gore & Assoc., Newark, DE) patch graft in order to stimulate fibroblastic proliferation at the repair site had no biomechanical advantage over simple Kleinert suturing. The tensile test data were found to be consistent with the histological appearance of the repair sites and with detailed rupture dynamics patterns recorded by high-speed cinematography.

Achilles Tendon↗
PubMed1980

Load transmission through the proximal femur of the growing child: a finite element analysis.

Growth-related variations in the distribution of mechanical stress in the normal juvenile proximal femur are explored using a computer-based finite element stress analysis technique. Input data for the model are obtained from serial patient roentgenograms and from laboratory compression tests of fresh autopsy material. The results for the limiting case of epiphyseal closure (18-year-old male) are in substantive agreement with previous experimental and mathematical studies of the adult proximal femur. The computational results for the juvenile hip show that in spite of the complex morphological alterations occurring during growth, the basic mechanisms of load transmission at first ambulation are still operational at skeletal maturity. Foremost among these are the distally-concentrated weight bearing compressive stresses in the primary trabeculation system, the abductor-induced tensile stresses in the greater trochanter, and the large longitudinal stresses within the proximal femoral cortices. As growth advances, however, the importance of transverse compressive stresses in the proximal lateral metaphysis progressively diminishes, while shearing stresses in the plane of the epiphyseal plate increase markedly. These two major growth-related changes results largely from decreases in the neck-shaft angle, and if excessive, may be implicated in development coxa vara or slipped capital femoral epiphysis.

Adolescent↗
PubMed1980

Ankle arthrodesis: a comparative clinical and biomechanical evaluation.

Arthrodesis of the ankle joint is difficult to achieve when there are associated problems with bony deformity or abnormalities of the surrounding soft tissues. In a series of 50 ankle arthrodeses, in which 68% had either damaged soft tissues or fixed ankle deformity, the pseudarthrosis rate was 30%. This high failure rate led us to devise biomechanical studies to evaluate the inherent stability of the Charnley-type compression arthrodesis, the R.A.F. fusion, and a new dynamic compression T-plate. The stability of the Charnley apparatus was directly related to the tension upon the wingnuts. However, in spite of the massive compression generated by the Charnley apparatus, it was relatively unable to resist rotatory forces. The T-plate had excellent rotatory and flexion-extension stability and developed approximately 25 pounds/inch compression across the ankle fusion. The T-plates's clinical application is demonstrated in eight successful arthrodeses. The importance of an intraoperative roentgenogram to confirm satisfactory ankle alignment cannot be overemphasized.

Adult↗
PubMed1980

Modern concepts of external skeletal fixation of the pelvis.

The treatment of unstable pelvic ring fractures, markedly comminuted and displaced acetabular fractures and combinations of these insults to the pelvis is an unsolved problem. Of all the previously described methods, external fixation has appeared to hold the most promise for certain pelvic bone injuries of major proportions which are accompanied by instability of the pelvic ring. Many of the external fixation devices of the past have not provided adequate stability. A modification of the Hoffmann external frame provides a simple method of treatment for unstable pelvic ring fractures that immediately permits the patient to move from bed to chair. Complex pelvic and central acetabular fractures also are responsive to treatment by extensive external frames. While this external skeletal fixation is superior to previously available devices, internal fixation is under consideration for stabilization of the posterior portion of the pelvic ring. A combination of internal and external fixation may also be advantageous for severely disrupted pelvic bones.

Acetabulum↗
PubMed1979

Relief of patellofemoral contact stress by anterior displacement of the tibial tubercle.

Elevation of the patellar tendon by means of displacement of the tibial tubercle has been advocated by Maquet, Ficat and Hungerford, and Murray as an alternative to patellectomy for the treatment of patellofemoral arthralgias. Although tubercle elevation certainly reduces the over-all patellofemoral contact force, its effects on the complex local patterns of contact stress are of more direct significance. In a laboratory series using fresh amputation material, arrays of six miniature contact stress sensors were embedded in the retropatellar cartilage of knees subjected to isometric quadriceps-extension forces. The experimental data revealed that elevation of the patellar tendon generally afforded relief of local contact stress regardless of the joint configuration (zero degrees, 45 degrees, or 90 degrees of flexion), but that its effects were most pronounced at 90 degrees of flexion. Progressive increase in the tendon elevation caused progressive reduction in the contact stress. Most of the contact stress relief was achieved, however, with the first one-half inch of tendon elevation; further elevations to one and one and one-half inches were only marginally useful. In view of the increased superior patellar pole contact associated with distal pole flotation, the results indicate that under most circumstances the optimum amount of elevation of the tibial tubercle is about one-half inch.

Cartilage, Articular↗
PubMed1976

The effects of physical training on the lung growth of infant rats.

The effect of swimming exercise on the growth of the lungs was examined in 60 Charles River Outbred Albino male rats during their second and third months of life. A tw0-by-three factorial analysis of variance design was used for significant differences due to duration of exercise (swimming 5 minutes per day 5 days per week, swimming to exhaustion 5 days per week, and no exercise) and duration of training (4 weeks and 8 weeks). All rats were loaded equal to 5 percent of body weight while swimming. Measurements used to evaluate lung growth were lung blood volume, lung blood volume/body weight, alveolar density, ratio of alveolar surface area to respiratory volume, lung weight, and lung weight/body weight. It was concluded that alveolar proliferation was increased in rats exposed to swimming during the second month of postnatal growth as indicated by greater alveolar densities and surface area to respiratory volume ratios is exercised subjects. Failure to find further growth during the third month of life suggested a critical period prior to the third month for such proliferation. Nonexhaustive swimming was as effective as exhaustive swimming in promoting the proliferation. There was no interaction between duration of exercise and duration of training.

Animals↗
PubMedDate not supplied

Determination of the in situ forces and force distribution within the human anterior cruciate ligament.

The in situ forces and their distribution within the human anterior cruciate ligament (ACL) can clarify this ligament's role in the knee and help to resolve controversies regarding surgical treatment of ACL deficiency. We used a universal force-moment sensor (UFS) to determine the magnitude, direction, and point of application of the in situ forces in the ACL in intact human cadaveric knees. Unlike previous studies, this approach does not require surgical intervention, the attachment of mechanical devices to or near the ACL, or a priori assumptions about the direction of in situ force. Anterior tibial loads were applied to intact knees, which were limited to 1 degree of freedom at 30 degrees flexion. The in situ forces developed in the ACL were lower than the applied force for loads under 80 N, but larger for applied loads of more than 80 N. The direction of the force vector corresponded to that of the anteromedial (AM) portion of the ACL insertion on the tibial plateau. The point of force application was located in the posterior section of the anteromedial portion of the tibial insertion site. The anterior and posterior aspects of the anteromedial portion of the ACL supported 25% and 70% of the in situ force, respectively, with the remainder carried by the posterolateral portion. We believe that the data obtained with this new UFS methodology improves our understanding of the role of the ACL in knee function, and that this methodology can be easily extended to study the function of other ligaments.

Aged↗
PubMedDate not supplied

Shoulder muscle forces and tendon excursions during glenohumeral abduction in the scapular plane.

Muscle force values and tendon excursions across the glenohumeral joint during unconstrained glenohumeral abduction in the scapular plane were evaluated with a dynamic shoulder testing apparatus. This evaluation was achieved by simulated rotator cuff and middle deltoid activity applied in four plausible muscle force ratios: (1) equal force to each tendon, (2) 2:3 ratio of force applied to the middle deltoid/supraspinatus tendons, (3) 3:2 ratio of force applied to the middle deltoid/supraspinatus tendons, and (4) zero force applied to the supraspinatus tendon to simulate supraspinatus paralysis. The glenohumeral joint was then moved to 5 degrees, 15 degrees, 30 degrees, 45 degrees, 60 degrees, and maximum glenohumeral abduction while muscle forces, tendon excursions, and glenohumeral joint kinematics were monitored. Full glenohumeral abduction was achieved in all four test conditions. When the muscle force combination favored the middle deltoid, the smallest supraspinatus force was required from 30 degrees to maximum glenohumeral abduction; however, when the supraspinatus was favored, the largest supraspinatus force was necessary to achieve maximum glenohumeral abduction. With simulated supraspinatus paralysis the middle deltoid required the greatest increase in force from 15 degrees through 45 degrees of glenohumeral abduction. These results indicate that muscle efficiency during glenohumeral abduction is highly dependent on the ratio of applied force between the middle deltoid and supraspinatus. A larger contribution of force from the supraspinatus was required near the beginning of motion, whereas the middle deltoid was more important near the end of glenohumeral abduction in the scapular plane. Tendon excursion for the middle deltoid (6.4 +/- 0.2 cm) and supraspinatus (3.8 +/- 0.2 cm) were proportionately larger than those for the subscapularis and infraspinatus. Humeral head translations on the glenoid were less than 2 mm in all four conditions evaluated; therefore the glenohumeral joint behaves kinematically as a "ball-and-socket" articulation during glenohumeral abduction. Simulated supraspinatus paralysis does not change normal joint kinematics and does not prevent full glenohumeral abduction.

Aged↗
PubMedDate not supplied

Tensile properties of the superior glenohumeral and coracohumeral ligaments.

Recent evidence has shown that the superior glenohumeral ligament (SGHL) and coracohumeral ligament (CHL) are important static stabilizers. To clarify the function of these two ligaments, we studied their tensile properties with bone-ligament-bone complexes from fresh-frozen shoulders, 10 SGHLs and 10 CHLs. Each ligament's cross-sectional area was measured, and uniaxial tensile testing of each complex was performed. The stiffness, ultimate load, percent elongation, and energy absorbed to failure of each bone-ligament-bone complex were derived from its load-elongation curve. The cross-sectional area of the coracohumeral ligament was significantly greater than that of the superior glenohumeral ligament of their midportions (CHL, 53.7 +/- 3.2 mm2 vs. SGHL, 11.3 +/- 1.6 mm2, p < 0.05). Results also reveal significant differences between the tensile properties for the two ligaments, with the coracohumeral ligament possessing greater stiffness (CHL, 36.7 +/- 5.9 N/mm vs. SGHL, 17.4 +/- 1.5 N/mm, p < 0.05) and ultimate load (CHL, 359.8 +/- 40.3 N vs. SGHL, 101.9 +/- 11.5 N, p < 0.05) than the superior glenohumeral ligament. Our findings confirm that the coracohumeral ligament is an important capsuloligamentous structure of the glenohumeral joint.

Adult↗
PubMedDate not supplied

The spinoglenoid ligament and its relationship to the suprascapular nerve.

Entrapment of the suprascapular nerve by the inferior transverse scapular ligament or spinoglenoid ligament (SGL) has been discussed frequently in the literature, but it has not been well documented anatomically. Therefore the mechanism of entrapment is not well understood. When isolated atrophy and denervation of the infraspinatus muscle have been noted, compression of the muscle's motor branch at the spinoglenoid notch has been implicated. This anatomic and morphologic study investigates the role of the SGL in entrapment neuropathy of the infraspinatus. We used 23 shoulders from 19 cadavers, 5 women (8 shoulders) and 14 men (15 shoulders), with a mean age of 67.9 (54 to 78) years. The presence or absence of the SGL was noted. The length, width, and orientation of the SGL; size and shape of the tunnel to the infraspinatus fossa; and distance of the notch to the posterior glenoid rim were determined. The SGL was present in 14 (60.8%) shoulders, 5 (36%) women and 9 (64%) men. The SGL was wider at the superior entrance of the tunnel and fanned and twisted toward the inferior aspect. In all specimens the SGL fibers inserted into the posterior shoulder capsule. The mean length for the upper part of the SGL was 17.5 +/- 2.6 mm in men and 15.8 +/- 1.8 mm in women, and the lower part was 14.1 +/- 2.4 mm and 12.9 +/- 1.8 mm, respectively. The widths of the SGL at the origin of the scapular spine were 12.2 +/- 3.9 mm for men and 10.4 +/- 2.7 mm for women, whereas the insertion site widths were 15.8 +/- 2.2 mm for men, and 16.1 +/- 3.8 mm for women. The midportion width of the SGL was 6.8 +/- 1.9 mm in men and 5.8 +/- 2.1 mm in women. During cross-body adduction and internal rotation of the glenohumeral joint, the interaction of the SGL and the posterior capsule resulted in a tightening of the SGL. The suprascapular nerve moved laterally and stretched underneath the SGL in this position.

Aged↗
PubMedDate not supplied

Contribution of the passive properties of the rotator cuff to glenohumeral stability during anterior-posterior loading.

The passive properties of the rotator cuff have been shown to provide some stability during anterior-posterior (AP) translation. However, the relative importance of the rotator cuff to joint stability remains unclear. The purpose of this study was to quantify the force contributions of the rotator cuff and of capsuloligamentous structures at the glenohumeral joint during AP loading. We hypothesized that the rotator cuff acts as a significant passive stabilizer of the glenohumeral joint and that its contribution to joint stability is comparable to the contribution made by the components of the glenohumeral capsule. A robotic/universal force-moment sensor testing system was used to determine both the multiple "degrees of freedom" joint motion and the in situ force carried by each soft tissue structure during application of an 89N AP load at 4 abduction angles. The percent contribution of the rotator cuff to the resisting force of the intact joint during AP loading was significantly greater during posterior loading (35% +/- 26%) than during anterior loading at 60 degrees of abduction (P < .05). The contribution of the rotator cuff (i.e., 29% +/- 16% at 30 degrees of abduction) was found to be significantly greater than the contributions of the capsule components during posterior loading at 30 degrees, 60 degrees, and 90 degrees of abduction (P < .05). However, no differences could be found between the respective contributions of the rotator cuff and the capsule components during anterior loading. The results support our hypothesis and suggest that passive tension in the rotator cuff plays a more significant role than other soft tissue structures in resisting posterior loads at the glenohumeral joint. The important role of the rotator cuff during posterior loading may be a result of the thin posterior joint capsule compared with the anterior capsule, which has several thickenings. This information increases our understanding of posterior stability at the glenohumeral joint during clinical laxity tests.

Biomechanical Phenomena↗
PubMedDate not supplied

[Gene therapy for cartilage repair].

AIM: Articular cartilage has very limited intrinsic healing capacity. Although numerous attempts to repair full-thickness articular cartilage defects have been conducted, no methods have successfully regenerated long-lasting hyaline cartilage. One of the most promising procedures for cartilage repair is tissue engineering accompanied by gene therapy. METHOD: With gene therapy, genes encoding for therapeutic growth factors can be expressed at a high level in the injured site for an extended period of time. Chondrocytes have been intensively studied for cell transplantation in articular cartilage defects. RESULTS: However, recent studies have shown that chondrocytes are not the only candidate for cartilage repair. Muscle-derived cells have been found capable of delivering genes and represent a good vehicle to deliver therapeutic genes to improve cartilage repair. More importantly, recent studies have suggested the presence of pluripotent stem cells in muscle-derived cells. CONCLUSION: New techniques of cell therapy and molecular medicine for the treatment of cartilage lesions are currently undergoing clinical trials. This paper will summarize the current status of gene therapy for cartilage repair and its future application.

Arthritis, Rheumatoid↗
PubMedDate not supplied

[The effect of growth/differentiation factor-5 (GDF-5) on genotype and phenotype in human adult mesenchymal stem cells].

AIM: To evaluate the effects of GDF-5 on genotype and phenotype of human mesenchymal stem cells (hMSC). HYPOTHESIS: GDF-5 leads to up-regulation of the Type I-collagen (Col) gene without altering bone marker genes or alkaline phosphatase activity. METHODS: To test our hypothesis hMSC were treated with rmGDF-5. Using quantitative real-time PCR we analyzed mRNA for Col, Runx2 and Osterix (Osx). Furthermore, we analyzed alkaline phosphatase activity (ALP) as a phenotypical bone marker. ANOVA and post hoc statistical analyses were used to determine differences among treatments (p < 0.05). RESULTS: HMSC showed a biphasic response in both Col and Runx2 after rmGDF-5. Initial up-regulation was followed by a significant down-regulation below controls. Interestingly, the controls presented with changes for Col and Runx2 over time. There was no Osx expression in either treated hMSC or controls. No significant differences could be detected in ALP. CONCLUSION: Increased expression of Col and Runx2 might indicate differentiation towards both osteoblast and fibroblast lineage. However, no Osx expression and no change in ALP support the assumption that rmGDF-5 does not lead to an osteoblast phenotype in hMSC. Our in vitro studies confirm a possible therapeutic benefit of GDF-5 in the treatment of tendon and ligament injuries and tissue engineering approaches. Further research is necessary to prove its clinical value.

Alkaline Phosphatase↗
PubMedDate not supplied

[Sensorimotor potential of the intact and injured anterior and posterior cruciate ligaments--a neurophysiological study in an animal model].

AIM: This neurophysiological study is intended to investigate the sensomotor potential of the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL) which may provide joint stabilization via a ligamentomuscular reflex arch. In addition, the role of ligamentous injury on the sensomotor potential has been investigated. METHOD: The sensomotor potential was investigated using 24 knee joints in a sheep model under in-vivo conditions. The cruciate ligaments were mechanically loaded and the muscular activities of the hamstrings and the quadriceps were recorded simultaneously via electromyography. Injury to the ligaments was simulated by defined mechanical elongation of the ACL and PCL to failure. RESULTS: The results confirm the hypothesis of the existence of a ligamentomuscular reflex loop between ligamentary mechanoreceptors and the joint-stabilizing muscles. Mechanical loading of the ACL triggered mainly the activity of the hamstrings, whereas loading of the PCL led to the activation of the quadriceps. The rate of elongation which caused disturbances to the sensomotor potential was significantly smaller as compared to the elongation to failure. CONCLUSION: The cruciate ligaments provide dynamic joint stabilization via a ligamentomuscular reflex arch. It was demonstrated that the sensomotor potential of both structures is significantly more susceptible to ligament injury than the biomechanical potential.

Animals↗
PubMedDate not supplied

[Refined adenoviral transduction for controlled gene transfer into human adult mesenchymal stem cells].

AIM: Adenoviral gene transfer remains a powerful tool for basic research purposes. We hypothesize that adenoviral transduction of human mesenchymal stem cells (hMSC) in vitro can be improved by refined use of experimental parameters. METHODS: hMSCs were transduced by adenoviral vectors encoding Luciferase or BMP-2 at a selection of multiplicities of infection (MOI) and exposure times. Transgene production and total protein content were measured. To determine practical relevance, expression of the bone marker genes Runx2 and Type I collagen was analyzed by quantitative PCR. As a phenotypic marker alkaline phosphatase was assessed. ANOVA and post hoc statistical analyses were used to determine differences among data (p < 0.05). RESULTS: Prolonged exposure led to a decrease in transgene production and total protein content. Increasing MOI at exposure of up to 4 hours resulted in a higher production of the transgene. Transfer of the hBMP-2 gene promoted an enhanced lineage progression to the osteoblast phenotype indicating biological activity. CONCLUSION: Time of exposure is of major importance for toxicity in vitro and should not exceed 4 hours for hMSC. While increase in exposure time leads to cell death, surviving cells, up to a certain limit, seem to compensate by increasing production of the transgene indicating that transduction efficiency cannot be positively measured in a binary yes-or-no scheme.

Adenoviridae↗