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Biomedical subjects

F H Fu

Publications and source records attributed to F H Fu.

At least 19 recordsLinked to original sources
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

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

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↗
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↗
PubMed1995

A new dynamic testing apparatus to study glenohumeral joint motion.

A dynamic shoulder testing apparatus has been developed to examine unconstrained glenohumeral joint motion in human cadaveric full upper extremities. Six computer-controlled hydraulic cylinders are used to simulate muscle action, while the corresponding tendon excursions and six-degree of freedom joint motion are measured. Trials showed that the testing apparatus creates highly reproducible glenohumeral joint motion in the scapular plane. The apparatus can be used to examine the function of the shoulder musculature and capsuloligamentous structures during normal and pathologic motion at the glenohumeral joint.

Computers↗
PubMed1995

Arthroscopic Bankart repair with the Suretac device. Part I: Clinical observations.

Although arthroscopic Bankart repair has become an accepted surgical stabilization technique for anterior shoulder instability, the failure rate remains unacceptably high. Little information is available concerning healing of the Bankart repair. The purpose of this article is to clarify this issue by analyzing a cohort of 15 patients who underwent a "second-look" arthroscopy to evaluate and treat pain or recurrent instability following arthroscopic Bankart repair with the Suretac device (Acufex Microsurgical, Mansfield, MA). "Second-look" arthroscopy was performed at an average of 9 months following the index surgical procedure. The reasons for this second surgery were recurrent instability in 7, pain in 6, and pain and stiffness in 2. In the 7 patients with recurrent instability, the Bankart repair was found to be completely healed in 3 (43%), partially healed in 1 (14%), and had recurred in 3 (43%); however, 6 of 7 were observed to have lax capsular tissue. In 4 of these cases, retrospective review of the index surgical procedure showed that a technical error had been made during the repair. Two cases had biopsy of the repair site on "second-look" at 6 to 8 months, and this showed residual polyglyconate polymer debris surrounded by a histiocytic infiltrate. In the remaining 8 cases with stable shoulders, the Bankart repair had completely healed in 5 cases (62.5%) and partially healed in 3 cases (37.5%). The higher failure rate with this approach compared with open approaches appears to result from improper patient selection and errors in surgical technique. There is some question concerning healing strength of the Bankart repair, although complete healing of the Bankart does not seem to be a prerequesite for shoulder stability. Success of the procedure might be expected to improve by selecting only patients with unidirectional, posttraumatic, anterior instability who are found to have a discrete Bankart lesion and well-developed ligamentous tissue.

Adult↗
PubMed1995

Insertion-site anatomy of the human menisci: gross, arthroscopic, and topographical anatomy as a basis for meniscal transplantation.

A cadaveric study was performed to determine the insertion-site anatomy of the human menisci, their topographical relationships to adjacent intra-articular structures, and which arthroscopic portal provides for optimal visualization of each insertion site. Fifteen fresh-frozen cadaver knees were studied (ages 48 to 63 years). Ten knees underwent arthroscopy using four standard arthroscopic portals. Visualization and placement of an arthroscopic guide over each meniscal horn insertion site was attempted through the four arthroscopic portals. Guide wires were drilled to mark horn insertions followed by a gross dissection to evaluate accuracy of the guide wire gross dissection to evaluate accuracy of the guide wire placement and to isolate meniscal horn insertion sites. Insertion sites were outlined and evaluated for size and topographical relationships to other intra-articular structures. Five additional knees were dissected free of all soft tissues except the tibial insertions of the meniscal roots and anterior cruciate ligament/posterior cruciate ligament. Each tibia was mounted in a jig and a digitizing system was used to record coordinates of points along the outline of each bony meniscal horn insertion site, the ACL tibial insertion, and the articular surface of each tibial plateau. The x, y, z coordinates for each point were calculated and loaded into a computer program allowing for surface area determination and computer-generated topographical maps to assess relative position of each specific insertion site. Placement of the arthroscope in the anterolateral portal allows optimal visualization and guide wire placement for both lateral meniscal horn insertion sites. Medial meniscal anterior and posterior horn insertion sites are best visualized with the arthroscope in the anteromedial and posteromedial portals respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Arthroscopy↗
PubMed1995

Instability and impingement in the athlete's shoulder.

The competitive athlete who participates in a sport requiring overhead motion depends on a shoulder with optimal function. An acute episode of injury or a gradual onset of symptoms in the shoulder can affect the athlete's ability to perform. An understanding of shoulder anatomy and function is essential, and an accurate diagnosis of the underlying pathology is critical for planning treatment options. The correct diagnosis may be less clear when the athlete presents with an insidious onset of shoulder pain. A detailed history and physical examination, as well as an evaluation of the overhead motion and onset of pain, is important when the diagnosis of instability or impingement is considered. Rehabilitation of the rotator cuff often succeeds in alleviating symptoms and restoring function. Surgery is considered when symptoms and diminished function persist despite appropriate nonoperative treatment. Operative repair or reconstruction must be anatomical in nature. Postoperative rehabilitation is equally important in this setting, and a motivated athlete helps to ensure success.

Athletic Injuries↗
PubMed1995

Shoulder kinesthesia in healthy unilateral athletes participating in upper extremity sports.

Shoulder kinesthesia has not been extensively studied in upper extremity athletes. The purpose of this study was to determine if there were differences in threshold to detection of passive motion between dominant and nondominant shoulders of healthy overhead athletes in two positions, 0 degrees and 75 degrees of external rotation. In addition, the study attempted to determine if there was a relationship between the range of external rotation (ER) and internal rotation (IR) and the threshold to detection of passive motion values. Shoulder kinesthesia was assessed in the dominant and nondominant shoulders of 20 collegiate athletes participating in unilateral upper extremity sports. A proprioceptive testing device passively moved the shoulder into internal and external rotation. The dominant shoulder had a significantly greater difficulty detecting motion compared with the nondominant arm at both 0 degrees and 75 degrees of external rotation. Both shoulders exhibited enhanced kinesthesia (lower threshold to detection of passive motion scores) at 75 degrees of external rotation compared with 0 degrees, where the glenohumeral joint capsule is relatively taut. The results of this study suggest that healthy upper extremity athletes may have kinesthetic deficits in their throwing shoulder compared with their nondominant shoulder.

Adolescent↗
PubMed1995

Uncommon causes of knee pain in the athlete.

There are many causes of knee pain in the athlete. Clearly, common things, such as meniscal tears, ligament sprains, contusions, and patellofemoral dysfunction, are common. The infrequency of other entities, however, should not make the physician complacent. A thorough history and physical examination will, in most cases, elicit inconsistencies in the occasional athlete presenting with one of these uncommon causes of knee pain (Table 1). Diagnosing these uncommon causes, when they do present to the health care provider, allows for early and correct treatment with a more rapid return to sports.

Adolescent↗
PubMed1995

Distribution of subcutaneous fat and equations for predicting percent body fat from skinfold measurements: a comparison between Chinese females from two age cohorts.

The need to apply different regression equations in predicting percent body fat was investigated with 40 Chinese females between 20-30 years and 40-50 years in Beijing in 1993-94. Skinfolds from 10 sites at subscapular, midaxillary, pectoral, abdominal, suprailiac, thigh, triceps, medial calf, suprapatellar, and forearm were measured with a Lange caliper. The criterion test was performed with hydrostatic weighing and the Siri equation was used to calculate percent body fat. It was found that there were significant differences in the distribution of subcutaneous fat between younger and older Chinese females, with the major differences in the abdominal and subscapular skinfolds. It also appeared that the 20-30 years cohort had a more evenly distributed subcutaneous fat that the 40-50 years cohort. A general prediction equation for percent body fat with skinfolds of the forearm, pectora, subscapular, and triceps was formulated with an R of 0.95 and SEE of 2.14. Separate equations were developed for the two age cohorts. These were found to be more accurate than the general equation. The present study indicated that subcutaneous fat distribution varied with age in the female and further study in this area would be needed to better understand the relationship between fat distribution patterns, metabolic risks, and cardiovascular disease.

Adipose Tissue↗
PubMed1994

Particle-induced synthesis of collagenase by synovial fibroblasts: an immunocytochemical study.

The response of synoviocytes to wear particles has been implicated in several orthopaedic pathologies, including the synovitis associated with the failure of synthetic anterior cruciate ligament (ACL) replacements. To study the interactions of particles with synovial fibroblasts at the level of the individual cell, we employed immunocytochemistry, with use of antiserum, to lapine interstitial collagenase. Cultures of the HIG-82 lapine synovial cell line showed only weak immunofluorescence under resting conditions. Incubation with phorbol myristate acetate or autocrine factors known as cell-activating factors (CAFs) induced marked changes in morphology and intense immunofluorescence. This technique then was used to study the effects of standard particles of latex and of particles generated from two prosthetic ACL materials, Dacron and carbon. Internalized particles of latex, Dacron, and carbon all induced collagenase. Particles of latex that were too large for endocytosis failed to induce collagenase, whereas particles of carbon and, in particular, Dacron that remained extracellular, still provoked considerable synthesis of collagenase. Thus, both the size and the physical properties of these materials influence their ability to activate synoviocytes. Certain cells that appeared by visual inspection to contain no particles nevertheless produced collagenase when in co-culture with cells that did contain particles. This is consistent with earlier biochemical data showing that phagocytosis, in addition to inducing collagenase, also provokes the release of CAFs, which then activate additional cells in the culture. More rarely, cells were identified which, although containing particles, did not stain positively for collagenase.(ABSTRACT TRUNCATED AT 250 WORDS)

Anterior Cruciate Ligament↗
PubMed1994

Synovial fluid cytokine concentrations as possible prognostic indicators in the ACL-deficient knee.

Approximately 44% of patients develop osteoarthritis (OA) following rupture of the anterior cruciate ligament (ACL) if the injury is left unrepaired. Restoring knee stability through reconstruction, while providing symptomatic relief, has not been shown to reduce the incidence of degenerative changes. In fact, recent studies have shown that 50%-60% of ACL-reconstructed patients go on to develop degenerative changes or frank osteoarthritis. In light of these data, our group suggests that the cause of post-traumatic osteoarthritis is not biomechanical but biochemical. To test this hypothesis, we measured levels of nine cytokines which are important in modulating physiological and pathophysiological metabolism of cartilage in knee joint synovial fluid following ACL rupture. Our patient population contained both acute and chronic ACL ruptures. A total of 84 samples were collected and analyzed by enzyme-linked immunosorbent assay. On the basis of the data collected, we were able to identify subgroups of patients who, on the basis of their synovial fluid cytokine profile, may be at greater or lesser risk of developing post-traumatic OA. In general, patients displayed concentrations of interleukin-1 alpha (IL-1 alpha), basic fibroblastic growth factor (bFGF), transforming growth factor-beta (TGF-beta), granulocyte/macrophage-colony stimulating factor (GM-CSF), IL-6, and IL-8 that we interpreted as being consistent with an inflammatory reaction. Of great interest is the fact that the levels of these cytokines were very similar in patients 4 weeks after injury and in chronic patients, leading us to hypothesize that a chronic smoldering inflammatory reaction persists after resolution of the acute effusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Anterior Cruciate Ligament Injuries↗