Biomedical subjects

Cheng-Kung Cheng

Publications and source records attributed to Cheng-Kung Cheng.

33 records · Page 2Linked to original sources

PubMed2003

The influence of surgical malalignment on the contact pressures of fixed and mobile bearing knee prostheses--a biomechanical study.

OBJECTIVE: To investigate the effect of surgical malalignment on contact pressures of fixed and mobile bearing knee prostheses. DESIGN: An experimental set-up was used to measure contact pressure on the tibial component of fixed and mobile bearing knee prostheses subjected to a compression load and surgical malalignment situations were simulated. BACKGROUND: Mobile bearing knee prostheses were designed to decrease tibiofemoral contact pressure by providing both high congruity and mobility. It was also assumed to accommodate surgical malalignment. However, few studies have reported the effect of malalignment of the tibiofemoral joint on contact pressure of fixed and mobile bearing knee prostheses. METHODS: Surgical malalignment situations were simulated to evaluate contact characteristics of tibial component of fixed and mobile bearing knee prostheses. The simulated malalignment conditions include the medial-lateral translation (0.5 and 1 mm), anterior-posterior translation (2 and 4 mm) and internal-external rotation (1 degrees, 3 degrees, 5 degrees and 10 degrees ) of the femoral component relative to the tibial component. Fuji pressure sensitive film was used to measure the contact pressure. RESULTS: The greatest increase of maximum contact pressure in the anterior-posterior maltranslation was 7.63% and 7.62% relative to the neutral contact situation in the fixed and mobile bearing designs respectively. In the medial-lateral maltranslation, there was 23.3% in the fixed bearing design and was 22.0% in the mobile bearing design. In the internal/external malrotation, the greatest increase of maximum contact pressure in the fixed bearing design was 27.1%, which was much higher than the mobile bearing design (22.4%). CONCLUSIONS: The mobile bearing design can reduce maximum contact pressure more significantly than the fixed bearing design when malalignment conditions of the tibiofemoral joint occurs, especially in the internal/external malrotation. The mobile bearing design offers the advantage of self-adjusting over the fixed bearing design to accommodate surgical malalignment. RELEVANCE: This study revealed that the mobile bearing design has smaller maximum contact pressures than the fixed bearing design in knee prosthesis under malalignment biomechanical tests. This result indicates that there is an advantage for a mobile bearing design over a fixed bearing design to accommodate malalignment conditions caused by surgical technique or soft tissues imbalance in total knee arthroplasty.

Arthroplasty, Replacement, Knee↗

PubMed2003

Evaluation of shoulder proprioception following muscle fatigue.

OBJECTIVE: To investigate the effect of shoulder muscle fatigue on glenohumeral proprioception. DESIGN: A repeated proprioception test was performed. BACKGROUND: The role of conditioning and fatigue in sport injuries remains controversial. It has been hypothesized that proprioceptive information plays an important role in joint stabilization and that muscle fatigue may alter proprioceptive ability. However, the effect of shoulder muscle fatigue on glenohumeral proprioception is still controversial. METHODS: Eleven normal subjects (mean age 27.3 years) participated in this study. Proprioception tests (on the dominant shoulder) were performed in which proprioception of the active reproduced and passive reproduced shoulder position was measured using an isokinetic dynamometer and a proprioception testing apparatus, respectively. The speed of active repositioning was at 2 deg/s and passive repositioning was at 0.5 deg/s. The mean value of maximum voluntary contraction and the number of repetitions for muscle fatigue were recorded. Post-fatigue proprioception test was started within 3 min after muscle fatigue. RESULTS: There was no significant difference of shoulder proprioception between pre- and post-fatigue determinations of passive repositioning in shoulder internal rotation, passive repositioning in external rotation and active repositioning in internal rotation. There was a significant difference between pre- and post-fatigue determination of active repositioning in external shoulder rotation (mean degrees: 2.57 (SD 1.02) vs. 4.96 (SD 1.73), P<0.05). CONCLUSION: Shoulder proprioception in active repositioning in external rotation was major affected by muscle mechanoreceptors in the presence of muscle fatigue. RELEVANCE: This study revealed that the shoulder proprioception after muscle fatigue in active repositioning in shoulder external rotation was affected more sensitively by the muscle mechanoreceptors than the joint mechanoreceptors. Increasing resistance of muscle fatigue would increase the shoulder proprioceptive ability.

Adaptation, Psychological↗

PubMed2003

A stereomorphologic study of bone matrix apposition in HA-implanted cavities observed with SEM, being prepared by a microvascular cast and freeze-fracture method.

In order to obtain further understanding of the relationship between hydroxyapatite (HA) with regard to its properties as an implantation bed, dense HA particles were implanted into the tibiae of dogs. Following the healing periods of 2 weeks, 1 month, 2 months, 3 months and 6 months, the specimens were prepared with a combination of a microvascular cast method and a freeze-fracture technique, allowing observations to be made with a scanning electron microscope (SEM). Under SEM, osteogenesis among the HA particles developed in a programmed sequence. The unfolding sequence revealed that the sinusoidal capillaries provided the initial evidence of vascularization preceding new bone formation, with microvessels creeping along the interparticular space among the HA particles. Having established an intimate contact existing between the microvessels, collagen fibres and the HA surface, the HA particles served as a supporting scaffold for the vessels to creep over and to connect with each other to form a vascular network. The way that the collagen fibres attached to the HA particles was either through globular depositions or via directly abutting themselves on to the HA surface. On closer inspection the osteoblasts with extracellular collagen fibrils were observed over the HA surface. By appositional growth, osteoblasts laid down a bone matrix in successive layers, forming a woven bone around the HA particles. As the implantation time increased, bony tissues gradually transformed into mature bone occupying all of the interparticular space. This study successfully revealed the spatial relationship between bone cells, collagen fibres and blood vessels in an osteogenetic sequence among HA particles, as revealed by a microvascular cast and the freeze-fracture method.

Animals↗

PubMed2002

Particle size and morphology of UHMWPE wear debris in failed total knee arthroplasties--a comparison between mobile bearing and fixed bearing knees.

Osteolysis induced by ultrahigh molecular weight polyethylene wear debris has been recognized as the major cause of long-term failure in total joint arthroplasties. In a previous study, the prevalence of intraoperatively identified osteolysis during primary revision surgery was much higher in mobile bearing knee replacements (47%) than in fixed bearing knee replacements (13%). We postulated that mobile bearing knee implants tend to produce smaller sized particles. In our current study, we compared the particle size and morphology of polyethylene wear debris between failed mobile bearing and fixed bearing knees. Tissue specimens from interfacial and lytic regions were extracted during revision surgery of 10 mobile bearing knees (all of the low contact stress (LCS) design) and 17 fixed bearing knees (10 of the porous-coated anatomic (PCA) and 7 of the Miller/Galante design). Polyethylene particles were isolated from the tissue specimens and examined using both scanning electron microscopy and light-scattering analyses. The LCS mobile bearing knees produced smaller particulate debris (mean equivalent spherical diameter: 0.58 microm in LCS, 1.17 microm in PCA and 5.23 microm in M/G) and more granular debris (mean value: 93% in LCS, 77% in PCA and 15% in M/G).

Aged↗

PubMed2002

The incidence of revision of the metal component of total knee arthroplasties in different tibial-insert designs.

Seventy-one revisions of knee arthroplasty due to wear of modular tibial polyethylene inserts undertaken from May 1990 to May 1999 were reviewed. In 38 cases (53.5%), severe damage was noted that necessitated replacement of the metal components. This proportion was less than in a previous study (88.7%). All the cases were further divided into two groups based on the design of the tibial component, one group having mobile bearings and the other fixed. In only 17.7% of the mobile group was there a need to replace metal parts at revision, whereas 83.8% of the fixed group required such replacement, which is much more comparable to the previous study. Therefore, the incidence of revision of the metallic component of a total knee arthroplasty depends greatly on the design of the tibial components.

Aged↗

PubMed2002

Late dislocation of rotating platform in New Jersey Low-Contact Stress knee prosthesis.

Five patients with late rotational dislocation of the rotating platform bearing in the New Jersey Low-Contact Stress total knee arthroplasty are reported. The prostheses had functioned well for 8 to 12 years before failure. Preoperative radiographs showed asymmetric femorotibial joint spaces. Entrapment of the dislocated bearing in three patients and spontaneous reduction of the dislocated bearing in another two patients were seen at revision. Femorotibial ligamentous instability was found after reduction. The retrieved polyethylene bearings showed advanced wear and cold flow deformities and the thickness was reduced. The revision arthroplasty was accomplished by replacement with a thicker bearing element. Progressive femorotibial ligament laxity and reduction of the thickness of polyethylene with wearing break down the originally well-balanced soft tissue tension of the knee. The rotational degree of the rotating platform bearing is unrestricted, which may result in late dislocation. Polyethylene wear is unavoidable in knee prostheses using metal contact with polyethylene even with a mobile-bearing design. Efforts to reduce polyethylene wear are mandatory.

Aged↗

PubMed2002

A biomechanical comparison of posterolateral fusion and posterior fusion in the lumbar spine.

Late postoperative complications occurred after posterior fusion and posterolateral fusion as a result of biomechanical alterations. The stress change between the two fusion procedures has not been well reported. To differentiate the biomechanical alteration that occurs with posterior fusion and posterolateral fusion of the lumbar spine, the load sharing of the vertebrae, disc, facet joint, bone graft, and the range of motion were computed in a finite element model. Five finite element models, including the intact lumber spine, posterior fusion, posterior fusion with implant, posterolateral fusion, and posterolateral fusion with implant, were created for stress analysis. The finite element model estimated that the differences between these two fusion procedures were within 7% in stress of the adjacent disc, 3% in force of the facet joint above the fusion mass, and 5% in the range of motion. However, the stress of the pedicle in posterolateral fusion without an implant was at most two times greater than that in the intact lumbar spine under lateral bending. The stress of pars interarticularis in posterior fusion without an implant was also at most two times greater than that in the intact lumbar spine under lateral bending. After the implant was added, the discrepancy between the two fusion procedures decreased but still remained a relatively large difference. Therefore, the largest changes of posterior fusion and posterolateral fusion were in the pars interarticularis and pedicle, respectively.

Adult↗

PubMed2002

Osteolysis in failed total knee arthroplasty: a comparison of mobile-bearing and fixed-bearing knees.

BACKGROUND: Osteolysis is an important complication associated with total knee arthroplasty. The purpose of this study was to compare the prevalence of osteolysis after failed total knee arthroplasty with a mobile-bearing prosthesis and after failed arthroplasty with a fixed-bearing prosthesis. METHODS: Eighty revision total knee arthroplasties performed between 1995 and 1998 were included in this study. All had radiographic evidence of advanced polyethylene wear. The mobile-bearing group consisted of thirty-four knees with a Low Contact Stress implant, and the fixed-bearing group included forty-six knees. The average time (and standard deviation) from the primary operation to the revision was 102.8 +/- 26.5 months in the mobile-bearing group and 96.0 +/- 30.1 months in the fixed-bearing group. The prerevision radiographs and operative findings were reviewed. RESULTS: The prevalence of osteolysis was significantly higher in the mobile-bearing group (47%; sixteen of thirty-four knees) than in the fixed-bearing group (13%; six of forty-six knees) (p = 0.003). The distal part of the femur was involved in thirteen knees in the mobile-bearing group and in four knees in the fixed-bearing group. Seventeen knees had osteolysis in the posterior aspect of the femoral condyle, which was the most common site of osteolysis; however, twelve of them had no evidence of osteolysis on prerevision radiographs. CONCLUSIONS: The prevalence of osteolysis was higher in the knees with a mobile-bearing prosthesis than in those with a fixed-bearing prosthesis. The osteolysis was predominantly on the femoral side, adjacent to the posterior aspect of the condyle. Radiographic evaluation of osteolysis in the distal part of the femur may not be reliable and usually leads to an underestimation of the degree of osteolysis.

Aged↗

PubMed2002

Biomechanical analysis of the lumbar spine with anterior interbody fusion on the different locations of the bone grafts.

The anterior lumbar interbody fusion is the common procedure in the management of the degenerated disc in the lumbar spine, but the biomechanical behavior of the fused segment would be changed because of the implantation of bone graft at the different locations. To investigate the biomechanical alteration, the study applied the finite element model to undergo the stress analysis.A three-dimensional finite element model of the lumbar spine was established, and modified to the three fusion models consisted of the bone graft at the anterior site, the middle site and the posterior site, respectively. The 12 N m flexion and the 10 N m torsion with pre-load 150 N were imposed on the L1 vertebral body. The results of the finite element model indicated that placing bone graft at anterior site could effectively resist flexion moment, and decreased the tensile force of the posterior ligaments about 15% above. Placing bone graft at posterior site could resist torsional moment, and also led to none of contact force of the facet joint in the fused segment. However, wherever the bone grafts were placed, stress slightly increased on the disc adjacent to interbody fusion about 5% below.

Bone Transplantation↗

PubMed1998

Biomechanical evaluation of a new anterior spinal implant.

OBJECTIVE: To biomechanically evaluate the construct of a new anterior spinal implant for osteoporotic patients. DESIGN: Mechanical tests and finite element analysis were designed to evaluate the spinal implant. BACKGROUND: Many osteoporotic thoracolumbar spine fractures often need surgical intervention to relieve pains, stabilize progressive kyphosis or improve neurologic impairment. Progressive kyphosis, instrumentation failure and pseudoarthrosis are often seen post-operatively. These results may be due to insufficient bonding between the screw and the vertebral body. As the end-plate is the most rigid part of the vertebral body, the spinal implant was designed so that the end-block would fix onto the end-plates of the vertebral bodies. METHODS: Two biomechanical evaluations of the new anterior spinal implant were conducted to evaluate the construct stiffness and the bonding strength between the spinal implant and the vertebral body. In the evaluation of the construct stiffness, the biomechanical tests between the new spinal implant and the Kaneda device were performed on six fresh intact porcine spines at the thoracolumbar region. In the prediction of the loading transfer between the spinal implant and the vertebral body, a three-dimensional finite element model (FEM) was built to simulate the osteoporotic vertebral body and the new anterior spinal implant. RESULTS: The results of the mechanical tests showed that the compressive stiffnesses of the Kaneda device and the new implant were 357 +/- 37 N mm(-1) and 297 +/- 98 N mm(-1). Their flexional stiffnesses were 0.339 +/- 0.126 N-m mm(-1) and 0.364 +/- 0.107 N-m mm(-1), respectively. Their torsional stiffnesses were 6.37 +/- 0.28 N-m deg(-1) and 5.30 +/- 0.71 N-m deg(-1), respectively. There were no significant differences (p > 0.01). The results of FEM showed that the new implant had high stress concentration on the junction of the screw and plate, screw and end-blocks, and between the end-plate and the end-blocks. CONCLUSIONS: The stabilization effect of the new implant was similar to that of the Kaneda device. With less rigid mechanical properties, the new implant can be more beneficial to the remodeling process of the spinal structure after instrumentation. The new anterior spinal implant showed a high potential for application to osteoporotic patients.

Journal Article↗

PubMed1998

A three-dimensional mathematical model for predicting spinal joint force distribution during manual liftings.

OBJECTIVE: A three-dimensional dynamic mathematical model was developed to discover what loads are imposed on the lumbar structures by performance of asymmetric manual liftings. DESIGN: An external model was used to estimate the intersegmental resultant forces and moments at the L(5)/S(1) joint in this dynamic biomechanical model. Using an optimization algorithm, an internal model then distributed the intersegmental resultants to forces of muscle, disc, facet joints, and ligaments. BACKGROUND: To study the relation between large loads and low-back disorders, many biomechanical models have been developed. Most of the models were two-dimensional models discussed with symmetric activities. Some three-dimensional biomechanical models were static models or only included limited elements of the disc and muscles in the model. METHODS: A healthy young male subject was asked to perform asymmetric lift with bent knees. Dynamic data of body motion and ground reaction forces were monitored, and the EMG of six muscles were recorded simultaneously. A Newtonian equation was used to calculate the joint intersegmental resultant forces and moments. In the internal model, three components of the disc force, eight muscle forces, two ligament forces and two facet joint forces were computed. RESULTS: The correlation between the reaction moments from the upper and lower models of the external part were generally above 0.94, and the root mean square differences were below 19 Nm. In this internal model, the maximal disc compression was close to the data showed on the literature, and the estimation of muscle forces corresponded to the EMG activities. CONCLUSIONS: A three-dimensional biomechanical model has been developed and evaluated to estimate the spinal joint force distribution during asymmetric manual lifting activities.

Journal Article↗

PubMed1998

Morphological changes of the triceps surae muscle-tendon unit during passive extension: an in vivo rabbit model.

OBJECTIVE: To elucidate the morphological and biomechanical manifestation of the triceps surae muscle-tendon unit during passive extension. DESIGN: The instantaneous changes within the load-deformation curve of muscle-tendon unit were analyzed by an in vivo rabbit model. BACKGROUND: Although muscle strains occur more frequently than complete failures, the failure mechanism of these sub-failure injuries is rarely investigated. Monitoring of the instantaneous changes in the load-deformation curve allows correlation with the morphological changes that occur during passive extension. METHODS: After anesthesia, the triceps surae muscle of rabbit was dissected and then stretched to failure by a MTS Bionix 858 machine. The morphological changes in failure patterns were recorded by photographs. RESULTS: The morphological and biomechanical manifestations of the triceps surae muscle-tendon unit was divided into five different portions: first, the viscoelastic portion with minimal morphologic change; second, the portion of micro-failure with local ecchymosis; third and fourth, the portions of macrofailure with sequential rupture of the muscle fibers; and fifth, the portion of rupture and separation of muscle parenchyma. CONCLUSIONS: A threshold for stretch-induced injury does exist. The threshold of the initiation of micro-failure in this model was 16.5% of the strain, which corresponded to 16.6% of the maximal sustainable force. RELEVANCE: Elucidation of the existence of micro-failure in skeletal muscle gives a good reference point to determine the functional capabilities and limitation of muscular tissue. With this, the deleterious effect of muscle stretching can be avoided by limiting muscle stretching to below this limit.

Journal Article↗

PubMed1998

Isokinetic evaluation of the ankle before and after surgical treatment of the lumbar disc herniation.

OBJECTIVE: To quantitatively evaluate the ankle strength before and after surgical treatment for herniated lumbar intervertebral disc. DESIGN: Isokinetic test of ankle joint and statistical analysis were designed to evaluate the results before and after surgery. BACKGROUND: Assessments of the results before and after treatment of lumbar herniation of intervertebral discs (HIVD) in previous papers were all based on patients' symptoms, activity, working condition, the angle of straight leg raising test, and requirement of pain medication. We designed a prospective study of isokinetic measurement of the ankle joints in those patients with HIVD to try to find a quantitative method of evaluation. METHODS: The criteria of selecting patients were single level disc herniation of lumber spine, without associated major neuromuscular or musculoskeletal disorder, normal mental status and cooperative, clinically evident radiculopathy, failure of conservative treatment, and age under 45. The isokinetic strengths of the ankle joints, of both involved and uninvolved limbs, were evaluated with plantarflexion or dorsiflexion, in the velocities of 30, 60, 120, and 180 degrees s(-1), according to their affected levels. Standard laminotomy with removal of intervertebral disc was undertaken for all patients under general anesthesia. The isokinetic strength of the ankle joints were evaluated with Kin-Com dynamometer before surgery, and post-operatively at 1 week, 2 weeks, 4 weeks, 2 months, and 3 months. All data were collected and analyzed with linear mixed model for analysis of variance with repeated measures. RESULTS: From January, 1996, 5 patients entered this study, 2 patients were L4-L5 herniation, and 3 for L5-S1. The estimated mean strength ratio and standard error was 55.04 +/- 2.21% preoperatively, 46.42 +/- 2.22% postoperatively at 1 week, 64.35 +/- 2.23% postoperatively at 2 weeks, 73.93 +/- 2.23% postoperatively at 4 weeks, 100.40 +/- 2.22% postoperatively at 2 months, and 104.55 +/- 2.21% postoperatively at 3 months. CONCLUSIONS: In this preliminary prospective study, there seems no correlation between duration of the symptoms and isokinetic strength of the ankle joint. There is, however, marked improvement of isokinetic strength of ankle joint postoperatively at 2 months, which was statistically significant.

Journal Article↗

PubMed1995

Surgery simulation analysis of anterior advancement of the tibial tuberosity.

The objective of this study is to evaluate the surgical outcome of anterior displacement of the tibial tuberosity (Maquet procedure) for reducing patellofemoral joint contact force. Thein-vivo experimental knee joint geometric data with a biomechanical model was used to do the simulation of the Maquet procedure. Six healthy young adults performed weight-bearing knee flexion-extension by ascending a one-step stair. Dynamic X-ray images of the knee were continuously recorded by a video-fluoroscopic system. These X-ray images were analysed on a computerized digitizing system to get the knee joint geometric data. Based on the continuous in-vivo geometric data, computer surgery simulation was studied on six right knees with advancement of 3, 5, 10, 15, and 20 degrees of the patellar tendon insertion. Evaluation of the simulation consequences from a biomechanical view point showed that the Maquet procedure reduced the patellofemoral joint reaction force only up to 20% at 90 degrees of knee flexion angle. The patellofemoral joint reaction force had 50% reduction only when the knee flexion angle less than 20 degrees, and only when the patellar tendon was moved out by 15 or 20 degrees. This represented nearly 1 in. of the anterior displacement of the tibial tuberosity. The results also showed that the Maquet procedure would decrease up to 20% of the force transmission efficiency of the patellofemoral mechanism, which would cause the mechanical consequences of the operation to be only minor at larger knee flexion angles more than 20 degrees. These findings suggest that the Maquet procedure is only favourable to less active or older patients having small knee flexion angle activities. RELEVANCE: Surgical procedure of anterior displacement of the tibial tuberosity has been used to reduce the patellofemoral joint contact force for treatment of symptomatic osteoarthrosis of the patellofemoral joint. In this study the patellofemoral joint reaction force had 50% reduction only when the knee flexion angle was less than 20 degrees, and only when patellar tendon was moved out nearly 1 in. Based on this result, the Maquet procedure is suggested only favourable to less active or older patients having small knee flexion angle activities.

Journal Article↗

PubMedDate not supplied

Effect of Fuji pressure sensitive film on actual contact characteristics of artificial tibiofemoral joint.

OBJECTIVE: To investigate the effect of inserting a Fuji pressure sensitive film into an artificial tibiofemoral joint on the actual contact mechanics. DESIGN: The experimental measurement and finite element analysis were used.Background. Although Fuji pressure sensitive film was widespread used for measuring the contact characteristics of artificial joint, how this measurement approaches actual contact characteristics has not yet been studied extensively. METHOD: Two three-dimensional finite element models of an artificial tibiofemoral joint were constructed. The with-film-model was used to mimic the experimental setup and was verified by comparing the contact area and pressure on the simulated film calculated from finite element analysis to the measured one from the Fuji film (ultra-super low and medium grades) in the experimental test. Then the with-film-model was modified to the without-film-model in which the simulated film was removed. The contact characteristics on the film calculated from the with-film-model were represented to the measured one and the contact characteristics on the tibial component calculated from the without-film-model were represented to the actual one. The measured and actual contact characteristics were studied to investigate the effects of Fuji film on the actual contact characteristics in the tibiofemoral joint of knee prosthesis. RESULTS: The contact characteristics calculated from with-film-model was reasonable agreement with measured one by Fuji film in the experimental test. The maximum difference is 13% in maximum contact pressure under a load of 3000 N. The maximum difference of contact area and pressure between the model simulating actual contact circumstance and the model with inserting a Fuji film between contacting surface are 2.4% and 14% respectively. CONCLUSION: This study revealed that contact area and pressure of the tibiofemoral joint of knee prosthesis measured by Fuji pressure sensitive film could be simulated by finite element analysis. The measurement of contact area in the artificial joint by using ultra-super low grade Fuji film is overestimated its actual contact area by 1.2-2.4%, but the measurement of contact pressure by using medium grade Fuji film is underestimated its actual contact pressure by 8-14%. RELEVANCE: This study revealed that the ultra-super low grade Fuji film is a reliable sensor to measure the contact area and the medium grade film would underestimate its actual contact pressure in the artificial tibiofemoral joint. This finding can provide a better understanding of the reliability of Fuji film to measure the contact characteristics of artificial joint in the experimental test.

Computer-Aided Design↗