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Biomedical subjects

F H Fu

Publications and source records attributed to F H Fu.

At least 163 records · Page 9Linked to original sources
PubMedDate not supplied

[Osteoblastic differentiation of human adult mesenchymal stem cells after through gene transfer of BMP-2 in the absence of dexamethasone].

AIM: Mesenchymal stem cells (MSC) of various species appear to require different cues to differentiate towards the osteoblastic lineage. For MSC of human origin, recombinant hBMP-2 is reported to be not sufficient but dexamethasone seems to be essential. The aim of this study was to analyse changes in genotype and phenotype of hMSC after adenoviral transfer of the BMP-2 gene in the absence of dexamethasone. METHODS: We employed hMSC and analysed changes in expression of the Runx2, Osterix and type I collagen gene by quantitative PCR after adenoviral transfer of the human BMP-2 gene in the absence of dexamethasone. As a phenotypic marker alkaline phosphatase activity was assessed. ANOVA and post hoc statistical analyses were used to determine differences among data (p < 0.05). RESULTS: Transfer of the hBMP-2 gene and consecutive production of transgenic BMP-2 up-regulated bone marker gene expression and increased alkaline phosphatase activity and thus promoted an enhanced lineage progression to the osteoblast phenotype without the addition of dexamethasone. CONCLUSION: These findings are noteworthy in the light of a possible superiority of endogenous transgenic proteins compared to exogenous recombinant proteins.

Adult↗
PubMedDate not supplied

[Orthopaedic surgery residency: comparison between the German and the North American system].

AIM: On the way to the unification of the European Union (EU), Germany has passed a new medical professional education system at the 106 (th) German medical board in Cologne in 2003. The medical board has established a new residency programme for the specialty of orthopaedic surgery, which was previously separated into orthopaedic and trauma surgery. An exchange of orthopaedic surgeons within the EU is therefore less complicated. For an exchange outside the EU, an international comparison especially with the USA is warranted. METHOD: We analysed and compared the German "Assistenzarzt System" with the residency programme of the USA regarding the specialty of orthopaedic surgery and further sub-specialisation programmes. RESULTS: After evaluation of both systems, a high conformity in the basic training for orthopaedic surgery was demonstrated. However, there is a difference between the two systems regarding specialisation after residency training with the German "Oberarzt" on the one side and the American fellow system on the other side. CONCLUSION: This study demonstrates that the German orthopaedic training matches well with the American residency programs. There is potential for acknowledgement of the German title "Orthopaedic surgeon" in the USA. In some states, such as Pennsylvania, European medical specialists are given institutionally restricted work permission for limited periods of time. It remains, however, questionable if there is a general political intent for the USA to acknowledge German or European residency programs.

Curriculum↗
PubMedDate not supplied

Experimental investigation of reaction forces at the glenohumeral joint during active abduction.

Reaction forces at the glenohumeral joint counterbalance the mass moment of the upper extremity during shoulder motion and are directly related to the activity of muscles across the joint. Because stability of the glenohumeral joint depends on compression of the humeral head into the glenoid, reaction forces constitute an important aspect of shoulder biomechanics. The objective of this study was to measure reaction forces at the glenohumeral joint during active scapula plane abduction. Furthermore, to clarify the relationship between the deltoid and supraspinatus muscles throughout abduction, this study investigated the effect of 4 variations of applied muscle forces on the magnitude and direction of glenohumeral reaction forces. We used a dynamic shoulder testing apparatus equipped with a force-moment sensor to directly measure reaction forces. Joint reaction forces increased throughout abduction and peaked at approximately 90 degrees for all testing conditions. The largest reaction forces occurred when the ratio of applied forces favored the supraspinatus tendon, whereas simulated paralysis of the supraspinatus resulted in a significant decrease in joint compression. There were no differences in direction of the reaction force between testing conditions. The results of this study indicate that the magnitude of glenohumeral joint reaction forces varies according to the ratio of forces between the supraspinatus and deltoid muscles. Thus, conditions characterized by either deltoid or supraspinatus dysfunction may result in abnormal loading mechanics at the glenohumeral joint. Understanding the relationship between rotator cuff function and glenohumeral reaction forces will aid in clarifying the importance of muscular activity to shoulder stability and strength as it relates to compression of the humeral head.

Biophysical Phenomena↗
PubMedDate not supplied

Shoulder proprioception in baseball pitchers.

We examined proprioceptive differences between the dominant and nondominant shoulders of 21 collegiate baseball pitchers without a history of shoulder instability or surgery. A proprioceptive testing device was used to measure kinesthesia and joint position sense. Joint position sense was significantly (P =.05) more accurate in the nondominant shoulder than in the dominant shoulder when starting at 75% of maximal external rotation and moving into internal rotation. There were no significant differences for proprioception in the other measured positions or with kinesthesia testing. Six pitchers with recent shoulder pain had a significant (P =.04) kinesthetic deficit in the symptomatic dominant shoulder compared with the asymptomatic shoulder, as measured in neutral rotation moving into internal rotation. The net effect of training, exercise-induced laxity, and increased external rotation in baseball pitchers does not affect proprioception, although shoulder pain, possibly due to rotator cuff inflammation or tendinitis, is associated with reduced kinesthetic sensation.

Adolescent↗
PubMedDate not supplied

Current trends in anterior cruciate ligament reconstruction. Part II. Operative procedures and clinical correlations.

Surgical management of the anterior cruciate ligament-deficient knee has evolved from primary repair to extracapsular augmentation to anterior cruciate ligament reconstruction using biologic tissue grafts. The technique of anterior cruciate ligament reconstruction has improved over the last few decades with the aid of knowledge gained from basic science and clinical research. The biology and biomechanics of anterior cruciate ligament reconstruction were analyzed in the previously published first part of this article. In this second part, current operative concepts of anterior cruciate ligament reconstruction as well as clinical correlations are discussed. The latest information regarding anterior cruciate ligament reconstruction is presented with a goal of demonstrating the correlation between the application of basic science knowledge and the improvement of clinical outcomes.

Anterior Cruciate Ligament↗
PubMedDate not supplied

Does nitric oxide help explain the differential healing capacity of the anterior cruciate, posterior cruciate, and medial collateral ligaments?

This study compared the ability of rabbit medial collateral ligament, posterior cruciate ligament, and anterior cruciate ligament tissue to synthesize nitric oxide, and determined its effects on matrix synthesis, an important component of ligament repair. It is not known whether ligament cells can produce nitric oxide and, if so, whether it influences healing of ligament injuries. The anterior cruciate and posterior cruciate ligament tissue produced large amounts of nitric oxide in response to the inflammatory cytokine interleukin-1. Medial collateral ligament, in contrast, produced only modest amounts of nitric oxide. Furthermore, anterior cruciate ligament and, to some degree, posterior cruciate ligament synthesized nitric oxide spontaneously in culture, whereas medial collateral ligament never did so. When nitric oxide was supplied to these tissues, it strongly inhibited collagen synthesis by the two cruciate ligaments, but had little effect on collagen synthesis by the medial collateral ligament. Endogenously synthesized nitric oxide was also able to inhibit collagen synthesis as well as proteoglycan synthesis by the two cruciate ligaments, but had little effect on matrix synthesis by the medial collateral ligament. We propose a novel hypothesis, based on nitric oxide production and matrix synthesis, that may help explain why the two cruciate ligaments have such limited healing capacity compared with the medial collateral ligament.

Animals↗
PubMedDate not supplied

The biomechanical interdependence between the anterior cruciate ligament replacement graft and the medial meniscus.

To establish a quantitative biomechanical relationship between the anterior cruciate ligament graft and the medial meniscus, 10 human cadaveric knees were examined using the robotic/universal force-moment sensor testing system. In response to a combined 134-N anterior and 200-N axial compressive tibial load, the resulting kinematics of the knee and the in situ forces in the anterior cruciate ligament, the anterior cruciate ligament graft, and the medial meniscus were measured. Anterior tibial translation significantly increased after anterior cruciate ligament transection, between 6.8 +/- 2.3 mm at full extension and 12.6 +/- 3.3 mm at 30 degrees of flexion. Consequently, the resultant forces on the medial meniscus, ranging from 52 +/- 30 N to 63 +/- 51 N between full extension and 90 degrees of knee flexion in the intact knee, were doubled as a result of anterior cruciate ligament deficiency. However, after anterior cruciate ligament reconstruction, anterior tibial translations were restored to the levels of the intact knee, and thus the forces on the medial meniscus were restored as well. Likewise, the in situ forces in the anterior cruciate ligament replacement graft increased between 33% and 50% after medial meniscectomy.

Adult↗
PubMedDate not supplied

The position of the tibia during graft fixation affects knee kinematics and graft forces for anterior cruciate ligament reconstruction.

Ten cadaveric knees (donor ages, 36 to 66 years) were tested at full extension, 15 degrees, 30 degrees, and 90 degrees of flexion under a 134-N anterior tibial load. In each knee, the kinematics as well as in situ force in the graft were compared when the graft was fixed with the tibia in four different positions: full knee extension while the surgeon applied a posterior tibial load (Position 1), 30 degrees of flexion with the tibia at the neutral position of the intact knee (Position 2), 30 degrees of flexion with a 67-N posterior tibial load (Position 3), and 30 degrees of flexion with a 134-N posterior tibial load (Position 4). For Positions 1 and 2, the anterior tibial translation and the in situ forces were up to 60% greater and 36% smaller, respectively, than that of the intact knee. For Position 3, knee kinematics and in situ forces were closest to those observed in the intact knee. For Position 4, anterior tibial translation was significantly decreased by up to 2 mm and the in situ force increased up to 31 N. These results suggest that the position of the tibia during graft fixation is an important consideration for the biomechanical performance of an anterior cruciate ligament-reconstructed knee.

Adult↗
PubMedDate not supplied

Meniscal tears: the effect of meniscectomy and of repair on intraarticular contact areas and stress in the human knee. A preliminary report.

The role of the meniscus in load transmission across the knee has long been a subject of debate. In this study, we examined the biomechanical consequences of the operative treatments for bucket-handle and peripheral meniscal tears. Contact areas and instantaneous intraarticular pressure distributions were measured in two groups of human cadaver knees. In Group I, consisting of four knees, we created a bucket-handle tear involving the inner one-third of the meniscus, followed by partial, and then total meniscectomy. Knees were tested in an Instron testing machine after each procedure, using a 400 pound load at 0 degrees or 30 degrees flexion. Contact areas and local stresses were measured using Prescale, a pressure-sensitive film. After partial meniscectomy, contact areas decreased approximately 10%, and peak local contact stresses (PLCS) increased approximately 65%. After total meniscectomy, contact areas decreased approximately 75%, and PLCS increased approximately 235%. In Group II, consisting of three additional knees, we created a 2 cm peripheral tear of the posterior meniscal horn, followed by open repair, arthroscopic repair, segmental, and then total meniscectomy. Repair of the tear was accomplished with either vertically placed sutures by an open technique or horizontally placed sutures by an arthroscopic technique. Knees were tested in the neutral position in the Instron machine and contact areas and local stresses measured using Prescale. PLCSs and contact areas were found to be the same using either repair technique. There was, however, a 110% increase in PLCS after segmental meniscectomy of that portion of the meniscus involved in the peripheral tear.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗
PubMedDate not supplied

Anterior stability of the glenohumeral joint. A dynamic model.

This study defines the interaction of the rotator cuff musculature and the glenohumeral ligaments in providing anterior stability to the glenohumeral joint. Eight cadaveric shoulders were studied using a testing frame that individually simulated the forces of the subscapularis, the supraspinatus, and the infraspinatus/teres minor musculature. The application of these forces abducted the humerus to approximately 90 degrees. The cocking phase of throwing was then simulated through the use of an Instron. With random variation of the rotator cuff forces, we investigated the effects that each force had on the rotation of the humerus and the strain of the inferior glenohumeral ligament. Our results demonstrate that the infraspinatus/teres minor muscle group was the most effective in controlling external rotation of the humerus and in reducing ligamentous strain. These observations are pertinent in the treatment of anterior instability syndromes of the shoulder.

Humans↗
PubMedDate not supplied

Peripheral tears of the meniscus. The effect of open versus arthroscopic repair on intraarticular contact stresses in the human knee.

The mechanical properties of the repaired meniscus may affect its ability to heal and to protect the articular surface against degenerative changes. We compared the immediate biomechanical consequences of open versus arthroscopic repair in the human cadaver knee. Additionally, having measured postoperative stresses at various degrees of knee flexion, we have addressed the effect of tethering of the meniscus, a question relevant to both meniscus repair and replacement. Peak stresses were measured by the Pressensor system. Fresh human cadaver knees were subjected to loading in an Instron unit, on an unconstrained base. Instantaneous loads were applied with the knee in 0 degree, 30 degrees, or 60 degrees of flexion, and stress distributions were measured after repair of a 2 cm peripheral tear, by an open or arthroscopic approach. The results of loading experiments on five knees revealed no statistically significant differences between stresses after the two repairs. Similarly, there was no statistically significant difference between the normal and repaired menisci. In our model, this suggests that the immediate biomechanical consequences of open and arthroscopic repair are equivalent and that the "tethered" meniscus distributes loads as well as the normal meniscus.

Arthroscopy↗
PubMedDate not supplied

The biochemical and histological effects of artificial ligament wear particles: in vitro and in vivo studies.

Growing evidence suggests that biochemical mechanisms play a role in the pathogenesis of arthritis. Cartilaginous wear particles have been shown to induce destructive enzymes and cytokines. To assess the biocompatibility of artificial ACL replacements, the effects of wear particles from the following ligaments were analyzed biochemically and histologically: GORETEX, Stryker Dacron Ligament Prosthesis, Versigraft carbon, Kennedy LAD, Xenograft, Leeds-Keio, and human patellar tendon allograft. Ligaments were frozen and ground to produce wear particles similar to those seen clinically and were added to lapine synovial cell cultures. The resulting conditioned medium was analyzed for collagenase, gelatinase, and chondrocyte activating factor (CAF) production. All of the ligaments induced significantly elevated enzyme and CAF production by the synoviocytes, with Xenograft and carbon inducing significantly higher enzyme levels than those of the other five ligaments. Five milligrams of wear particles were injected into the knees of 4 kg to 5 kg rabbits that were analyzed histologically after 14 weeks. Wear particles accumulated in the periarticular synovial folds and induced modest to severe macrophage infiltration in the synovium. A hypothetical model explaining the role of artificial ligament wear particles in the pathogenesis of arthritis is presented.

Animals↗
PubMedDate not supplied

Cidex-induced synovitis.

Microscopic evidence of inflammation was observed in the synovium of rabbit knees that had been injected with 10 ppm of Cidex (2% glutaraldehyde). Initial changes were synovial hypertrophy, subsynovial edema, and vascular congestion. At concentrations of 100 ppm or greater, focal synovial necrosis, hemorrhage, and gross diffuse synovitis were observed. The degree of synovial inflammation was proportional to the concentration of Cidex. Observation of synovial response versus time demonstrated this reaction to be a chemical synovitis without histologic evidence of a delayed hypersensitivity allergic component. Significant intraoperative levels of Cidex were noted in the rise solutions at several hospitals. When a single rinse is used, the concentration of Cidex present in the rinse basin is 100 to 300 ppm. If the same rinse is used for subsequent cases, the Cidex concentration is on the order of 1,000 ppm by the fifth arthroscopic procedure. If a double rinse is used and the rinse changed with each operative case, the Cidex concentration in the second rinse is less than 10 ppm. After irrigation of the knee joint with 1 liter of saline, the intraarticular concentration of Cidex is less than 10 ppm regardless of the rinse technique.

Aldehydes↗
PubMedDate not supplied

Tibial meniscal dynamics using three-dimensional reconstruction of magnetic resonance images.

The human knee joint represents a complex biomechanical system of which the menisci are an integral component. At present, little data exists describing the meniscal kinematics of the intact knee. Accordingly, a three-dimensional reconstruction magnetic resonance image model was used to explore this issue. Five fresh cadaveric knees were examined by magnetic resonance imaging throughout a full range of motion at 10 degrees intervals. Computer three-dimensional images of the menisci were generated and evaluated for anteroposterior excursion and deformation. During flexion, the posterior excursion of the medial meniscus was 5.1 mm, while that of the lateral meniscus was 11.2 mm. The anterior horn segments were shown to be more mobile than the posterior horn segments bilaterally. Prior limitations of meniscal kinematic assessment may be overcome with advanced imaging techniques such as magnetic resonance imaging and three-dimensional reconstruction. The menisci are highly mobile and easily deformed structures within the intact, cadaveric knee. This imaging technique may prove useful in the elucidation of meniscal dynamics. In the future, similar techniques may be applied clinically to aid in the diagnosis of joint dysfunction.

Biomechanical Phenomena↗
PubMedDate not supplied

Loss of motion after anterior cruciate ligament reconstruction.

We did a retrospective review and follow-up examination to investigate the incidence, risk factors, and outcome of patients who developed loss of motion after arthroscopic anterior cruciate ligament reconstruction. Two hundred forty-four patients with a minimum followup of 1 year were reviewed. Loss of motion (defined as a loss of extension of more than 10 degrees or flexion of less than 125 degrees) was identified in 27 patients for an overall incidence of 11.1%. Factors associated with loss of motion included acute reconstruction (less than 1 month from initial injury), male sex, and concomitant medial collateral ligament repair or posterior oblique ligament reefing or both. Twenty-one patients required surgery to regain their motion; three patients required a second procedure. Twenty-one of 27 patients with loss of motion underwent a detailed followup and were compared with 24 randomly chosen controls who had a normal range of motion after anterior cruciate ligament reconstruction. At followup, patients who experienced loss of motion had a significant decrease in noninvolved to involved knee extension and flexion compared to the control patients. There was no difference between our patients and the controls regarding patellofemoral problems, anterior knee laxity, and functional strength. Sixty-seven percent of patients with loss of motion had a good or excellent result in comparison to 80% of the controls.

Adolescent↗
PubMedDate not supplied

Thoracic spine fracture in a football player. A case report.

Compression fractures of the thoracic spine are less common than injuries to the cervical, thoracolumbar, or lumbar regions because of the inherent stability and geometry of the thoracic spinal region. This injury may be difficult to detect acutely because of the lack of localizing symptoms. An appropriate index of suspicion should be present when examining a player experiencing acute back pain associated with localized spinal tenderness. Early recognition and appropriate treatment are needed to maximize the patient's chances of return to normal function while avoiding further injury from lack of recognition of the injury or too early return to play.

Adult↗