Abstract:The purpose of this study is to analyse the gait of patients with knee joint disorder, by using the motion analysis system, in order to provide some references for clinical and therapeutic evaluation.Ten patients had been tested: six of them received anterior crucial ligament (ACL) reconstruction. and four received total knee arthroplasty. With cameras of the motion analysis system,the force plate, and the foot switch, raw experimental data were recorded simultaneously from each patient.Fourier analysis, knee angle parameters,ground reaction force parameters,and pressure distribution were then computed with the support of IBM software. The experimental results showed that(1)during the early post-operative poriod,knee joints of the patients receiving ACL reconstruction, unlike other normal subjects, did not have double locking' phenomenon in their single limb stance;(2) after rehabilitation,the ground reaction forces and the motion analysis did not show any significant difference between patients with ACL reconstruction and patients with total knee arthroplasty.

Abstract:Early motion of the affected finger is essential to healing of repaired flexor tendon,but it may result rupture if the tensile strength of the tendon is not great enough to sustain pulling force.On the other hand, over protection by inhibiting finger motion, the repaired tendon tends to adhere to the surrounding tissue.A good strong suture should be tight and secure against rupture and concomittently allow early motion of the finger. In this study we compared 4 basic suture techniques on one tendon end and eight both ends tendon suture technique as derived from basic methods.Although there are some differences between groups the most significant factor is the number of strands between the repaired tendon ends. The mean tensile strength were 1.75,3.09 and 4.54 Kgs in each group of two, four and six strands. The selection of suture technique depends on number of strands and clinical feasibily.

Abstract:The purpose of this study is to examine the gait of six postoperative patients being undergone the operation of Toe to Thumb Transplantation by the VICON motion analysis system.Three of the six patients are of Big Toe to Thumb Transplantation,and the other three are of Second Toe to Thumb Transplantation. Through the gait analysis further information can be given for clinical evaluation and therapeutic consideration.A VICON system, force plates and footswitches are implemented in collecting data simultaneoisly.These data are employed for calculating the gait periods and reaction forces from ground to feet with programing in a IBM PC.1) In the case of Big Toe Transplantation it is found the duration for the toe-off foot on the ground is longer. Furthermore, the reaction force and shear stress of in/out step of the toe-off foot are reduced.2) In the case of Second Toe Transplantation we find the duration of the big toe of the toe-off foot on the ground is 30% longer than that of a normal foot. Meanwhile, it is found the reaction force almost keeps constant no matter whether a second toe is on or not.

Abstract:In order to compare mechanical properties between various types of small bone fixators, hollow maple dowels are uniformly produced to simulate small bones in this study. Furthermore, transverse osteotonmy with 2mm gap, and 45°oblique osteotomies are created to simulate stable, unstable, and spiral fractures. Each fractue pattern is then approximated with four types fo fixators :(1)Aesculap mini extermal fixator,(2)mini A-O plate and screw,(3)cross pin, and(4) self-assembled mini external fixator. Finally,tension,torsion, and bending tests are performed with INSTRON.Dorsal plating has the strongest tensile rigidity and lateral bending rigidity in three different fracture patterns. Aesculap mini external fixator has the strongest torsional rigidity in stable and unstable fractures. Nevertheless, mini A-o plate has the strongest torsional rigidity in 45°oblique fracture. Dorsal plating, lateral plating, and mini external fixator all have good anterior bending rigidity without significant difference in stable fracture. Furthermore, only lateral plating and mini external fixator show good anterior bending rigidity in unstable and 45°oblique fractures. Except in torsional rigidity, Aesculap mini external fixator is not significantly stiffer than the self-assembled external fixator. As expected, cross pin is the weakest fixator.In this study, differences in mechanical stiffness among four types of small bone fixators are provided. Additionally. the indication should be considered when choosing a proper fixator.Complication rate can then be lowered to achieve a successful surgery in treating small bone fractures.

Abstract:Lumbar spinal flexion and extension motion was measured radiographically- "invasive" and from the back surface curvature- "non-invasive" (using motion analysis system)for evaluating lumbar spinal mobility(LSM). Twenty-four volunteers participated in this study and had their lateral view of lumbar spinal radiographs and photographs taken in three postures(upright, flexion and extension). The lumbar sacral angles(LSA) and the angles of each vertebral segment were obtained both from skin surface curvature and picture of X-ray. The results showed that the LSA and LSM remained the same either calculated based on Cobb angle or overly angle definition. To transform skin marker coordinates into corresponding vertebral body coordinates, a third order regression model was developed.The proposed transformation model demonstrated high coefficient of determination (mean=84.05%)between transformed positions and actual positions in all vertebral bodies, Based on this model, global LSA and intersegmental spinal mobility were recalculated and compared with results from X-ray measurement data. The results showed that the inter-vertebral lumbar spinal mobility could be obtained with errors ranging from 0.06 to 0.62 degrees. The results of this study indicated that in addition to the total motion in region of lumbar spine, we are able to discriminate the contribution of intersegmental spinal mobility through way of "non-invasive" measurement.

Abstract:Pullout test has been widely utilized in evaluating design parameters of screws. This is due to its simplicity in the experimental procedure.However, simple test creates some difficult problems. For example, no discussion has been made in the following topics:(1) effect of insertion position and direction,(2) effect of pullout direction, (3) effect of variation of cancellous bone structures. Insertion position and direction are relative to the geometric orientation of cancellous structures. Pullout direction can also contribute to pullout strength. Thinking differently, in this study, we use two kinds of trabecular structures: isotropic rod-type from bovine femoral condyle and plate-rod type structure from bovine spine vertebral body C_2～C_6, to check how this structural variation affecting the maximum pullout force in the pullout test. Finally, finite element modeling for pullout test is important based on several points: (1) how accurate can be obtained. (2) local deformation pattern around threads, (3) convergence characteristics. In the finite element analysis the strain energy density criterion will be used to define failure condition in the pullout simulation.

Abstract:In order to understand the effects of body weight-bearing on knee joint biomechanics, a video-fluoroscopic digitizing system was applied and in vivo human knee joint motions of 12 healthy adults under body weight-bearing and no weight-bearing conditions were recorded, digitized and analyzed. The changes of following parameters, including the knee flexion angle versus time, the length of the moment arm of the quadriceps muscle, the ratio between patellar tendon force and quadriceps muscle force, the ratio between patellofemoral joint reaction force and patellar tendon force in the sagittal plane during knee flexion-extension exercises under weight-bearing and no weight-bearing conditions were measured and compared. The results revealed that biomechanics of the knee joint motion under weight-bearing and no weight-bearing conditions were quite differnet. The knee under body weight-bearing condition extended rapidly and decelerated at near6-extension but the knee without body weight-bearing extended and flexed at almost equal speeds. The moment arm of the quadriceps muscle was shorter in knee exercise with body weight-bearing than that with no body weight-bearing but two groups showed similar patterns of change. The ratio between the tension of the patellar tendon and the quadriceps muscle force changed less obviously in the group performing knee exercise under body weight-bearing than the group performing knee exercise without body weight-bearing. The ratio between the patellofemoral joint reaction force and the quadriceps muscle force changed more obviously in the group with body weight-bearing than the group without body weight-bearing. Therefore,we concluded that body weight-bearing has strong influence on knee joint biomechanics. Besides, we should be more judicious in conducting in vitro studies of knee biomechanics because body weight-bearing is definitely a determining factor.

Abstract:An in-vivo test with New Zealand rabbit was done to analyse the influence of various post-operative rehabilitative exercises on the tensile strength of the interfascial healing tissue between bone and tendon. Three different post-operative exercises were included in this study and they are cast immobilization, cage activity, and continuous passive movement. The result revealed that the maximal tensile strength of the interfascial healing tissue at the 15th post-operative day was 0. 875kg in cage activity group, 2.014kg in cast immobilization group, and 2. 63kg in continuous passive motion group. The continuous passive motion group had the best maximal tensile strength. The cast immobilization group also had high maximal tensile strength, bu massive intracapsular adhesive tissue also observed in this group.

Abstract:Periosteal grafts have been used to repair large osteochondral defects in rabbit articular cartilage but early degeneration of the new cartilage has hindered extensive clinical application of this procedure. The effect of TGF-βintroduced either by pre-incubation of the periosteum in vitro or by intraarticular injection in vivo was compared to determine the relative effects of these two methods on the generation of new cartilage.Sixty-four rabbits were divided into five groups: 1. non-grafted group; 2. grafted group; 3. 100ng/ml rhTGF-β1 pre-incubation group; 4. grafted and 100ng/100μl rhTGF-β1 injected group; 5. grafted and 200ng/100μl rhTGF-β1 injected group. The rabbits were sacificed at 2 to 12 weeks, and specimens taken for histological examination sections were stained with Safranin O and were scored basing on a new subjective scoring system. Results showed that the grafted group healed with hyaline cartilage-like material formed to its utmost at 4 weeks, but soon followed with progressive thinning; the rhTGF-β1 incubated group did accelerated chondrogenesis but also accelerated degeneration. The rhTGF-β1 injected groups did not enhance chondrogenesis but generated osteophytes instead. While the non-grafted group healed without any cartilaginous material. The rhTGF-β1 pre-incubation in vitro is preferred over intra-articular injection as the route of administering this polypeptide growth factor and is effective in accelerating chondrogenesis, but the problem of early degeneration of new cartilage necessitates further study.