STATEMENT OF PROBLEM: Cortical bone plays an important role in the primary implant stability, which is essential to immediate/early loading. However, immediate load-bearing capacity and primary implant stability according to the change of the cortical bone thickness have not been reported. PURPOSE: The objectives of this study were (1) to measure the immediate load-bearing capacity of implant and primary implant stability according to the change of cortical bone thickness, and (2) to evaluate the correlation between them. MATERIAL AND METHODS: 48, screw-shaped implants (3.75 mmx7 mm) were placed into bovine rib bone blocks with different upper cortical bone thickness (0-2.5 mm) and resonance frequency (RF) values were measured subsequently. After fastening of healing abutment, implants were subjected to a compressive load until tolerated micromotion threshold known for the osseointegration and load values at threshold were recorded. Thereafter, RF measurement after loading, CT taking and image analysis were performed serially to evaluate the cortical bone quality and quantity. Immediate load-bearing capacity and RF values were analyzed statistically with ANOVA and post-hoc method at 95% confidence level (P<0.05). Regression analysis and correlation test were also performed. RESULTS: Existence and increase of cortical bone thickness increased the immediate load-bearing capacity and RF value (P<0.05). With the result of regression analysis, all parameters of cortical bone thickness to immediate load-bearing capacity and resonance frequency showed significant positive values (P<0.0001). A significant high correlation was observed between the cortical bone thickness and immediate load-bearing capacity (r=0.706, P<0.0001), between the cortical bone thickness and resonance frequency (r=0.753, P<0.0001) and between the immediate loadbearing capacity and resonance frequency (r=0.755, P<0.0001). Conclusion. In summary, cortical bone thickness change affected the immediate load-baring capacity and the RF value. Although RF analysis (RFA) is based on the measurement of implant/bone interfacial stiffness, when the implant is inserted stably, RFA is also considered to reflect implant/bone interfacial strength of immediately after placement from high correlation with the immediate loadbaring capacity. RFA and measuring the cortical bone thickness with X-ray before and during surgery could be an effective diagnosis tool for the success of immediate loading of implant.
Diagnosis ; Osseointegration ; Ribs ; Weight-Bearing*

PURPOSE: The purpose of this study was to evaluate the factors influencing the results for the treatment of the Schatzker type VI tibial plateau fractures. MATERIALS AND METHODS: Twenty-two cases of the 21 patients in Schatzker type VI tibial plateau fractures were analyzed. Treatment results were analyzed according to the type of fracture (open vs closed), method of operative treatment, angulation more than 5 degree and status of infection. The functional results was evaluated by Hohl's functional criteria. Student t-test was used for the statistical analysis. RESULTS: Functional outcome demonstrated 5 excellent, 8 good, 6 fair and 3 poor results. There was no significant difference in the treatment results between type of fracture, method of operative treatment and status of infection. Among 9 cases with angular deformity of more than 5 degree, 2 showed excellent or good result and 7 showed fair or poor result (p<0.05). There was no significant difference between rate of postoperative infection and the mean period of the clinical bone union (p=0.66). CONCLUSION: Accurate anatomical reduction and rigid fixation is essential for the treatment of Schatzker type VI tibial plateau fractures for the prevention of the angular deformity. And early weight bearing exercise should be controlled for the prevention of loss of reduction and loss of alignment leading to angular deformity.
Congenital Abnormalities ; Humans ; Weight-Bearing

OBJECTIVE: To establish the degree of modulating influence of the type of surfaces (whether stable or labile) on the dynamic balance responses during the sit-to-stand transfers in both stroke patients and healthy controls. METHOD: We evaluated sit-to-stand balance by Balance Master (NeuroCom, USA) in 30 hemiparetic patients and 10 healthy controls. All subjects were requested to perform sit-to-stand transfers three times each on the both stable and labile surfaces. Four balance indices (weight transfer time, rising index, COG sway velocity, left/right weight symmetry) were obtained. RESULTS: In hemiparetic patients, decreased rising index, increased COG sway velocity, increasing left/right weight asymmetry were noticed. During sit-to-stand transfers from sitting on labile surfaces to standing, rising index increased and left/right weight asymmetry increased in hemiparetic patients, but not in healthy controls. This implies that the maximum vertical force exerted by legs during the rise phase increased, but the differences of weight borne by each leg during the active rising phase increased in hemiparetic patients. CONCLUSION: Weight bearing exercise on the affected leg as well as strengthening exercise of legs are considered to be essential to decrease the falls during sit-to-stand transfer in stroke patients.
Humans ; Leg ; Stroke* ; Weight-Bearing

Internal fixation using a cephalomedullary nail as treatment for proximal femur fracture has recently been popular for early ambulation and rehabilitation. However metal breakage at the lag screw insertion site was reported due to non-union, delayed-union, and early weight bearing. In our orthopedic department, we experienced 2 cases of nail breakage at the lag screw insertion site, therefore we report on evaluation of the cause of metal failure and prevention of complications with literature review.
Early Ambulation ; Femur* ; Orthopedics ; Rehabilitation ; Weight-Bearing

PURPOSE: Zone I fractures of the fifth metatarsal bone can generally be treated by conservative methods while both surgical and conservative methods are used for zone II fractures. However, the clinical results of conservative treatment have been rarely reported. The purpose of this study is to report the clinical results of conservative treatment for zone I and II nondisplaced fractures. MATERIALS AND METHODS: Between July 2007 and August 2008, consecutive thirty seven patients (38 fractures) with zone I and II fractures of the fifth metatarsal bone were treated with tolerable weight bearing and minimum duration of immobilization based on pain on weight bearing. We evaluated the duration of immobilization, time to clinical and radiographic union, and time to pre-injury activity level. RESULTS: Clinical and radiological union were achieved in all patients without any complications including malunion or nonunion. The mean duration of immobilization was 28.7 days. The mean 33.1 days and 48.9 days were required for clinical union and radiographic union respectively, after the initial injury. The mean time to pre-injury activity level was 4.8 months. CONCLUSION: Our study shows that the acute nondisplaced zone I, II fracture of fifth metatarsal bone can be treated effectively using tolerable weight bearing and minimum duration of immobilization, which is based on the pain on weight bearing.
Humans ; Immobilization ; Metatarsal Bones ; Weight-Bearing

STATEMENT OF PROBLEM: Alteration of tooth function is assumed to be changed by stress/strain on the adjacent alveolar bone, producing changes in morphology similar to those described for other load-bearing bones. When teeth are removed, opposing teeth will not be functioned. When edentulous area is restored by implant prostheses, opposing teeth will be received physiologic mechanical stimuli. PURPOSE: The aim of this study was to evaluate the bone changes around the teeth opposing implant restoration installed mandibular posterior area. MATERIAL AND METHOD: Eight patients who had mandibular posterior edentulous area were treated with implants. Radiographs of the opposing teeth were taken at implant prostheses delivery(baseline), 3 months, and 6 months later. Customized film holding device was fabricated to standardize the projection geometry for serial radiographs of opposing teeth. Direct digital image was obtained. Gray values of region of interest at each digital image were measured and compared according to time lapse. Repeated measured analysis of variance and post-hoc Scheffe's test were performed at the 95% significance level. RESULTS: Alveolar bone changes around the natural teeth opposing the posterior implant in mandible showed statistically significant difference compared to control group(P<0.05). And gray values of alveolar bone around the teeth opposing implants were increased. There were no statistically significant differences of alveolar bone changes between crestal group and middle group and between mesial group and distal group according to time lapse(P>0.05). There were no statistically significant differences of alveolar bone changes among mesial-crestal group, mesial-middle group, distal-crestal group, distal-middle group, and control group(P>0.05). CONCLUSION: Alveolar bone around the natural teeth opposing the implant prosthesis showed gradual bony apposition.
Humans ; Mandible* ; Prostheses and Implants ; Tooth* ; Weight-Bearing

PURPOSE: The purpose of this study was to analyze the relative micromotions between the straight and the curved stems during the immediate postoperative stage of noncemented total hip replacement which load simulating the single leg stance and stair climbing. MATERIALS AND METHODS: The authors developed 3-dimensional numerical finite element models implanted with the straight stem, which was composed of a total of 1,170 elements of 8 nodes, and which had a curved stem composed of a total of 885 elements of 8 nodes, and then analyzed the relative micromotions of the straight and curved stems. RESULTS: In the single leg stance, the curved stem was more stable especially in terms of its rotational stability. Rotational displacement accounted for over 90% of the total micromotion in both types of stem and this was highest for the proximal medial portion of the stem, but markedly less distally. Stair climbing produced more micromotion than the single leg stance regardless of the stem configuration. CONCLUSION: It is recommended that surgeons do not allow patient weight bearing until bony ingrowth has been achieved. In the future more attention should be placed upon increasing the initial rotational stability of the two types of femoral stem to prevent loosening by excessive micromotion.
Arthroplasty, Replacement, Hip ; Humans ; Leg ; Weight-Bearing

Mechanically the symphysis pubis serves to anchor the ends of the two weight bearing arches of the pubis-the femorosacral and ischiosacral arches. Under normal conditions it has been found to exceedingly resistant to separation. Sacroiliac strain is also uncommon because the sacroiliac ligaments are very strong and the movement which produce a torsion strain upon the joint is more likely to cause a strain of thinner capsular ligaments surrounding the small lumbosacral joints. We experienced a case of separation of the symphysis pubis and 2 cases of sacroiliac strain during and after spontaneous labor.
Joints ; Ligaments ; Pubic Bone ; Weight-Bearing

The results of 17 fractures of tibial shaft treated with Rush nails under the image intensifier and early weight bearing are reported. Thirteen of these fractures were closed. All fractures were united between 12 and 21 weeks clinically, 17 and 26 weeks radiologically after operation. All cases were healed without significant complications, such as fracture disease. The advantages of this method were as follows; 1) normal knee motion and early weight bearingare possible during healing. 2) There is a relatively rapid restoration of bone continuity. This method of treatment for tibial shaft fractures were indicated as follows; 1. Mid-shaft fracture. 2. Segmental fracture of shaft. 3. Expectation of compression force at fracture surface by weight bearing. 4. Open fracture of shaft.
Fractures, Open ; Knee ; Methods ; Tibia ; Weight-Bearing

In order to compare mechanical stability of the Ilizarov external fixation methods for treatment of pilon fracture of the tibia, six human amputed tibiae were utilized to simulate Ruedi type I, II, and III fractures anatomically and non-anatomically reduced. Six fracture models which were either anatomically(3) or non-anatomically(3) reduced were first stailized by the Ilizarov construct composed of two tibial rings and foot assembly with connecting rods and ankle hinges and underwent axial load compression test using Instron. And then same tests were repeated on the models in which ankle hinges between the tibial rings and foot assembly were removed to examine biomechanical effect of the ankle hinges on the fracture stability. When the fracture model was fixed by the construct without ankle hinges, 720 N-780 N were required to disrupt fracture stability. When the fracture was non-anatomically reduced and was fixed by the construct without ankle hinges, 420 N-520 N were required to disrupt the fracture stability. The current study suggests that Ilizarov fixation system should have the construct composed of two tibial rings and foot assembly with connection rods and ankle hinges to prevent fracture destabilization during early ankle motion and weight-bearing in the tibial pilon fracture.
Ankle ; Foot ; Humans ; Methods ; Tibia ; Weight-Bearing