Biomedical subjects

F H Fu

Publications and source records attributed to F H Fu.

At least 37 records · Page 2Linked to original sources

PubMed1997

The effect of anterior cruciate ligament graft fixation site at the tibia on knee stability: evaluation using a robotic testing system.

Despite its current popularity and relative success, endoscopic reconstruction of the anterior cruciate ligament (ACL) using a bone-patellar tendon-bone (BPTB) graft has not yet been perfected. Using a recently developed robotic/UFS testing system, we assessed the overall stability of porcine knees following ACL reconstruction with different sites of tibial graft fixation--proximal, central, and distal. Testing of the intact knee was performed first to determine the normal anterior-posterior (A-P) displacements and in situ forces of the ACL under 110 N of anterior tibial loading of 30 degrees, 60 degrees, and 90 degrees of knee flexion. The knee was then reconstructed with a BPTB autograft, and the distal end of the graft was fixed sequentially at three different locations in each specimen--proximal, central, distal. A-P testing was repeated for each fixation site, and the resulting knee kinematics and the in situ forces of the grafts were compared to the intact case. The site of tibial fixation was demonstrated to have a significant effect on the resulting anterior displacement and internal rotation of the tibia as well as the in situ forces of the graft. Proximal fixation produced the most stable knee (A-P displacements reduced to 120% of intact at 30 degrees and 170% at 90 degrees), becoming significantly less stable with more distal fixation. These results suggest that proximal graft fixation may provide the most acute stability of the reconstructed knee.

Animals↗

PubMed1997

The effects of cryotherapy on muscle damage in rats subjected to endurance training.

Sixty 60-day-old Sprague-Dawley male rats were subjected to exhaustive and non-exhaustive exercise treatment over a period of 3, 5 and 7 weeks. Moderate exercise consisted of running on the treadmill at 10% grade at 10 m/min for 20 min for 5 days per week, while exhaustive running consisted of running at 10% grade at 15 m/min with an increase of 5 m/min every 5 min for 5 days per week. Half of the exercised rats were subjected to immersion in 4 degrees C water for 5 min after each exercise bout. Histological analyses of the gastrocnemius showed that ultrastructural damage of myofibrils occurred after 5 weeks of exhaustive running and 7 weeks of moderate running. With post-exercise immersion in 4 degrees C water for 5 min, the occurrence of ultrastructural damage advanced by 2 weeks in both treatments. It was concluded that the application of cryotherapy to the exercise groups was deleterious. Muscle damage occurred earlier in the treatment group and the degree of damage was also more serious over the same time period. This study supports the recommendation that the use of cryotherapy to reduce pain and haematoma formation should be coupled with rest for at least 48 hours.

Actin Cytoskeleton↗

PubMed1997

Monoclonal antibody 3F3 against conformational epitope of Torpedo acetylcholinesterase.

AIM: To study the type of epitope of native Torpedo acetylcholinesterase (AChE) directed by its monoclonal antibody (McAb) 3F3. METHODS: Enzyme-linked immunosorbent assay (ELISA) was used for the assay of the reaction between antigen and antibody. RESULTS: McAb 3F3 immunoreacted well with the native AChE, but not with the reduced- and alkylated-AChE (RA-AChE) at all. Soman did not interfere the binding of 3F3 with AChE molecule. The synthesized 24-peptide containing the active serine residue of the AChE active center did not react with McAb 3F3. CONCLUSION: 3F3 is a monoclonal antibody against the conformational epitope of Torpedo AChE active center, but dose not occupy the active serine residue of the enzyme.

Acetylcholinesterase↗

PubMed1997

[Possibilities of gene therapy in traumatic and degenerative articular lesions. Current status of experimental and initial clinical applications].

Soft tissue injuries often represent the greatest clinical problem. Not only do many of the most frequently injured tissues, such as the cruciate ligaments and articular cartilage, have very limited capabilities for spontaneous repair, but they also respond poorly to surgical or non-surgical intervention. In this article we try to define the role of growth factors in these conditions and to outline concepts for future treatment based upon modulation of the native repair response. We suggest that gene transfer could improve the management of such injuries, particularly when used as vehicles for the targetted delivery of growth factors.

Animals↗

PubMed1996

Temperature changes in the knee joint during arthroscopic surgery.

Normal joint conditions are altered during arthroscopic surgery, and these changes have uncertain ultrastructural and biomechanical effects on articular cartilage. Experimental studies have shown that temperature variations affect the biomechanical properties of articular cartilage. We documented the temperature of the knee joint in 40 patients at the beginning and end of an arthroscopic procedure (anterior cruciate ligament reconstruction or meniscectomy). The intra-articular measurements were obtained using a digital thermometer connected to a sterile stainless steel probe. Correlation coefficients and linear regression techniques were used to determine which variables are independent predictors of joint temperature at the end of surgery. The mean knee joint temperature before surgery was 35.1 degrees +/- 1.0 degrees C and at the end of surgery 24.6 degrees +/- 1.5 degrees C. The joint temperature at the end of surgery was significantly affected by the temperature of the saline irrigant used and the length of arthroscopic procedure. The clinical implications of our findings must be clarified in animal models.

Adolescent↗

PubMed1996

Mechanical properties of the long head of the biceps tendon.

In this study, the geometric and mechanical properties of the long head of the biceps tendon were determined in order to elucidate its role in shoulder stability. We used a laser-micrometer system to measure the cross-sectional area and shape of seven fresh-frozen tendons at three levels: proximal, middle, and distal levels. The cross-sectional areas were found to be 22.7 +/- 9.3 mm2, 22.7 +/- 3.5 mm2, and 10.8 +/- 2.7 mm2, respectively. While statistically significant differences could not be demonstrated between the magnitudes of the areas, a consistent difference in shape was noted between the proximal and middle levels, the tendon being flatter as it progressed over the humeral head and more triangular as it passed through the bicipital groove. We then performed cyclic relaxation tests and uniaxial tensile testing of the tendons which revealed a cyclic stress relaxation of 18 +/- 4% over ten cycles. All tensile failures occurred within the mid-portion of the tendon substance. Additionally, the modulus was calculated between 3% and 6% strain and found to be 421 +/- 212 MPa, while the ultimate tensile strength, ultimate strain, and strain energy density were 32.5 +/- 5.3 MPa, 10.1 +/- 2.7 %, and 1.9 +/- 0.4 MPa, respectively. These mechanical properties of the long head of the biceps tendon are of the same order of magnitude as tendons from other joints. The high stiffness of this tendon indicates that it has an ability to support the large load transferred to it by the muscle and to act as a humeral head depressor.

Adult↗

PubMed1996

Knee joint proprioception: a comparison between female intercollegiate gymnasts and controls.

The role of proprioception as a protective mechanism has gained interest in recent years. From the clinical standpoint, several studies have dealt with ways to enhance proprioception following surgery and during rehabilitation. If kinesthesia (ability to detect passive motion) can be enhanced as a consequence of long-term athletic training, such training must be included as a part of the rehabilitation process to protect the patient from reinjury. Consequently, the purpose of this study was to compare the kinesthetic knee pattern between trained gymnasts and healthy nongymnasts. The proprioception testing device (PTD) was used to evaluate knee kinesthesia. From 45 degrees of flexion, the knee was passively extended with the PTD. The device was stopped by the subject when this passive motion was detected. Fifteen healthy college-age female gymnasts (mean age 19.3 years) and 30 normal volunteers (mean age 20.7 years) comprised our study sample. A one-way analysis of variance (ANOVA) was used to compare the mean values of the dominant gymnastic knee to the dominant knee in the control group. Results revealed statistically significant mean differences between the trained gymnastic group and the untrained control group (F1.34(.95) = 7.17, P = 0.011). The results of this study suggest that extensive training has a positive influence on knee kinesthesia in addition to increasing muscle tone. According to the findings of this and other studies, highly trained athletes possess enhanced neurosensory pathways which are speculated to develop as a result of long-term athletic training. Although definite conclusions cannot be made from our investigation, prospective studies can determine the true role of athletic training in proprioceptive patterns.

Adolescent↗

PubMed1996

Prospects for gene therapy in sports medicine.

For the orthopedic sports medicine physician soft tissue injuries often present the greatest clinical problems. Not only do many of the most frequently injured tissues, such as the cruciate ligaments and articular cartilage, have very limited capabilities for spontaneous repair, but they also respond poorly to surgical or nonsurgical intervention. In this article we try to define the role of growth factors in these conditions and to outline concepts for future treatment based upon modulation of the native repair response. We suggest that gene transfer could improve the management of such injuries, particularly when used as vehicles for the targeted delivery of growth factors. The concept of gene therapy in orthopedic sports medicine can be extended to include disorders that present as laxity or mechanical weakness of ligaments. We speculate that subtle genetic differences between individuals may account for those who appear to be injury prone. In these cases it is likely that genes encoding the structural macromolecules of the matrix are defective. Local gene supplementation in such cases could be useful in the future.

Athletic Injuries↗

PubMed1996

A combined robotic/universal force sensor approach to determine in situ forces of knee ligaments.

We developed a system that uses a 6-degree-of-freedom (6-DOF) robotic manipulator combined with a 6-DOF force-moment sensor and a control system. The system is used to find and record the passive knee flexion path for controlling the knee flexion positions. It is also used to strain a knee structure by finding a multiple-DOF path in response to specific joint loading, e.g. anterior-posterior tibial force application. It is additionally used to measure in-situ forces in ligaments by recording differences in forces and moments when repeating a prerecorded path, both before and after removal of the ligament of interest. Example applications are included in the study.

Animals↗

PubMed1996

Allograft versus autograft anterior cruciate ligament reconstruction: 3- to 5-year outcome.

Sixty-four patients whose knees underwent anterior cruciate ligament reconstruction with nonirradiated allograft tissue were compared with 26 patients whose anterior cruciate ligaments were reconstructed using autograft tissue 3 to 5 years after their operation. Detailed symptoms, activity-level, and functional outcomes, physical examination, and instrumented knee testing were recorded. No statistically significant differences were found except a higher incidence of loss of terminal extension in the autograft group. These differences were small and not considered clinically significant. Laxity and knee scores were similar in both groups. According to International Knee Documentation Committee ratings, overall outcome was normal or nearly normal in 48% of the allograft patients and in 38% of the autograft patients. Overall subjective rating with the Cincinnati Knee Score was 85.8 for the allograft patients and 84.5 for the autograft patients. Allograft tissue provides an acceptable alternative to autograft tissue for reconstruction of the anterior cruciate ligament.

Adult↗

PubMed1996

Anterior cruciate ligament surgery 1996. State of the art?

During the past 20 years, numerous basic science and clinical studies have improved the treatment of the anterior cruciate ligament deficient knee. As our understanding of the short term and long term morbidity caused by the torn anterior cruciate ligament has improved, and the morbidity of surgical reconstruction has decreased, the indications for anterior cruciate ligament reconstruction have widened. Anatomic placement of the anterior cruciate ligament graft has improved the outcome of surgery, although various techniques are used to achieve that goal. The patellar tendon autograft has been established as the gold standard graft choice, but several graft choices are available, and have given similar results in early followup. One of the major advances in anterior cruciate ligament reconstruction has been the acceptance of early range of motion and controlled endurance and strength training during the postoperative period.

Anterior Cruciate Ligament↗

PubMed1996

Revision anterior cruciate ligament surgery: experience from Pittsburgh.

Twenty-five patients who underwent revision anterior cruciate ligament reconstruction after failure of a previous intraarticular reconstruction were retrospectively reviewed. Before revision, all patients reported functional instability with sports or activities of daily living and exhibited increased anterior patholaxity on physical examination. Fresh frozen irradiated allograft tissue was used for all revisions. A comprehensive knee analysis using a subjective and objective system was done for all patients preoperatively and at the time of final followup. The mean age at revision surgery was 25 years and average time from primary to revision surgery was 30 months. Average length of followup was 28 months. The anteroposterior displacement was improved in all patients. Sixty-four percent of patients had less than 5 mm side to side difference on arthrometric testing. Eighty percent had either a Grade 0 or Grade 1 pivot shift. The average modified Cincinnati Knee Score was 68 with the results of 88% of patients rated abnormal by International Knee Documentation Committee guidelines. Seventy-six percent of patients were satisfied with their results and would elect to have revision surgery again. These results show that patients having revision anterior cruciate ligament reconstruction for a failed intraarticular reconstruction had improvement in their functional status compared with prerevision; however, they did not achieve the same level of satisfactory results as primary anterior cruciate ligament reconstruction.

Activities of Daily Living↗

PubMed1996

Role of proprioception in pathoetiology of shoulder instability.

Proprioception is a specialized sensory modality that gives information about extremity position and direction of movement. This kind of afferent sensory feedback is probably important in mediating muscular control of the shoulder joint. As this articulation is minimally constrained, such a coordinated dynamic control of muscles about the joint is necessary for stability during arm motion. The authors evaluated proprioception in individuals with normal shoulders, unstable shoulders, and after surgical stabilization, by assessing threshold to detection of passive motion and the ability to passively reposition the arm in space. In normal shoulders there is no difference between the dominant and nondominant shoulder, though in unstable shoulders there is a significantly decreased proprioceptive ability. Surgical stabilization normalizes proprioception of the shoulder.

Adult↗

PubMed1996

Athletic knee injuries. Similarities and differences between Asian and Western experience.

The pattern and prevalence of knee injuries among athletes are different in Asia, Europe, and North America because of factors such as the different sporting cultures of the regions and the type of favorite sports. Sampling and data bias and the variable levels of diffusion of sports in the different parts of the world also are responsible for the variation. In this review, the knee emerges as the most commonly injured part of the body; such injuries present significant problems of mechanical block or instability that may compromise athletic performance. Sports specific injuries are delineated, and specific groups, such as children and adolescents, female, and master athletes, are reviewed in light of the characteristic patterns of knee injuries. Differences in the patients' attitude, health care systems, and consultations of traditional medical practitioners produce major differences in management styles. However, it is encouraging to find a concerted effort on all continents in the search for a better understanding of knee injuries and a more satisfactory coordination between clinical and basic science research in this field.

Adolescent↗

PubMed1996

Meniscal repair using the inside-to-outside technique.

The frequent occurrence of degenerative joint disease following complete or partial meniscectomy is well recognized. Meniscal repair has been shown to lead to a lower prevalence of degenerative changes in the knee. Arthroscopically assisted inside-to-outside meniscal repair is a safe, reproducible technique for for salvaging the torn meniscus.

Arthroscopy↗

PubMed1996

Gene transfer to the rabbit patellar tendon: potential for genetic enhancement of tendon and ligament healing.

Injuries to ligaments and tendons occur very commonly, but often heal very poorly. A number of growth factors show promise as biological agents with which to augment the reparative responses of these tissues, but they are extremely difficult to deliver clinically. We have suggested the use of gene transfer as a possible way to obviate this limitation. Here we have used the lacZ marker gene to evaluate methods for gene delivery to ligaments and tendons. Cell cultures were established from the following tissues of the New Zealand white rabbit: anterior and posterior cruciate ligaments, medial collateral ligament, patellar tendon and semitendionsus. In vitro experiments confirmed that these cells were very efficiently transduced by an E1- E3- adenoviral vector carrying the lacZ gene. Cells derived from ligaments and tendons also proved readily susceptible to retroviral transduction and, following transfer of the ned gene, selection in G418. To determine whether these cells could be genetically altered in situ, gene transfer to the patellar tendons of rabbits' knee joints was attempted using an adenovirus for in vivo delivery and a retrovirus for ex vivo delivery. Direct, percutaneous injection of the adenovirus resulted in high levels of lacZ expression, but this was limited to the area of tendon immediately adjacent to the injection site, and preferentially labeled cells in the epitenon sheath. An unexpected finding of these studies was the in vivo adenoviral transduction of bone cells in areas where the tendon insertion site had been accidentally injected. Allotransplantation of tendon fibroblasts into which the lacZ gene had been retrovirally introduced led to lacZ expression throughout the body of the tendon itself. The genetically altered cells appeared able to migrate from the site of injection and to integrate themselves into the crimp pattern of the tissue. Both in vivo and ex vivo methods led to gene expression for at least 6 weeks, which may be long enough for clinical purposes.

Adenoviridae↗

PubMed1995

The Bankart lesion of the shoulder: a biomechanical analysis following repair.

The Bankart lesion of the shoulder has long been associated with anterior instability. Our laboratory has developed a biomechanical model of the human shoulder which was used to determine the effects of creating a Bankart lesion on cadaveric specimens and then to compare the effects of two repair techniques. The model simulates the abducted, externally rotated position of the glenohumeral joint and uses pneumatic cylinders to simulate the rotator cuff forces. Specimens were tested intact following a partial Bankart lesion, following a complete Bankart lesion, and after performing a Bankart repair using three Mitek suture anchors. Finally, both the traditional and Mitek repairs were tested until failure. Strain in the inferior glenohumeral ligament (IGHL) and torque resistance was measured as an indication of instability of the joint. Strain was noted to decrease with increasing depth of lesion of the IGHL. Torsional rigidity of the shoulder decreased with increasing depth of lesion as well. Repairing the shoulder restores the strain and rigidity to control conditions. The mean load until failure was greater with the traditional repair than with the suture anchor technique. This study quantitates the effects of a Bankart lesion of the shoulder, and demonstrates that repairing the lesion with a suture anchor technique restores the biomechanics of the shoulder.

Biomechanical Phenomena↗

PubMed1995

Effect of knee flexion on the in situ force distribution in the human anterior cruciate ligament.

This study was conducted to evaluate the effect of applied load on the magnitude, direction, and point of tibial intersection of the in situ forces of the anteromedial (AM) and posterolateral (PL) bands of the human anterior cruciate ligament (ACL) at 30 degrees and 90 degrees of knee flexion. An Instron was used to apply a 100 N anterior shear force to 11 human cadaver knees, 6 at 30 degrees of knee flexion and 5 at 90 degrees of knee flexion. A Universal Force Sensor (UFS) recorded the resultant 6 degree-of freedom (DOF) forces/moments. Each specimen then underwent serial removal of the AM and PL bands. With the knee limited to 1 DOF (anteroposterior), tests were performed before and after each structure was removed. Because the path was identical in each test, the principle of superposition was applied. Thus, the difference between the resultant forces could be attributed to the force carried by the structure just removed. The magnitudes of force in the ACL at 30 degrees and 90 degrees of knee flexion were 114.1 +/- 7.4 N and 90.8 +/- 8.3 N, respectively (P < 0.05). At 30 degrees, the AM and PL bundles carried 95% and 4% of the total ACL force, respectively. At 90 degrees, the AM and PL bands carried 85% and 13%, respectively (P < 0.05). The direction of the in situ force in the whole ACL as well as its two bands correlated with the anatomic orientation of the ligament.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗