STUDY DESIGN: This biomechanical study was designed to perform flexibility tests in multiple loading directions to compare the stabilizing effects of supplemental hook or pedicle screw fixation on short segment pedicle instrumentation system. OBJECTIVE: To compare biomechanical flexibilities of short segment pedicle instrumentation constructs added by hook or pedicle screw fixation in an unstable calf spine model. SUMMARY OF BACKGROUND DATA: Short segment pedicle instrumentation is using recently for the surgical treatment of the unstable burst fractures of the thoracolumbar spine, but a high incidence of early screw tai lure in short segment pedicle instrumentation has reported. MATERIALS AND METHODS: Ten fresh frozen calf spines (T10-L3) were loaded with pure uncosstrained moments in flexion, extension, axial rotation, and lateral bending directions. A maximum moment of 6.4 Nm was achieved in 5 steps using dead weights. After removal of L1 vertebral body, testing was performed on intact specimens first and then each specimen after laminar hook or pedicle screw insertion on the short segment pedicle instrumentation of ISOLA implant. Any kinds of graft material or transfixation device were not used to make the worst possible case of instability of an injured spine. Three different fixation methods were instrumented. These included: (1) one level aboye and one level below with pedicle screw, (2) 2 levels above with pedicle screw and hook and one level below with pedicle screw, and (3) 2 levels abode and one level below with pedicle screws. RESULTS: At the level of corpectomy, all fixation methods significantly reduced motions in flexion, extension, and lateral bending as compared to the intact motion (P<0.001). The differences between all constructs were not statistically significant. The addition of a hook or screw on the short segment pedicle screw construct was not significantly reduced the flexibi lite as compared to the short segment pedicle screw construct. Axial rotational motions in groups I, II, and III were similar with each other and with intact motion as well and there were no significant statistical difference. The addition of the hook or screw on the short segment pedicle construct showed more stability as compared to the pedicle screw construct, but statistical difference was not. The addition of hook or screw on the short segment pedicle screw construct showed similar stability in all motions with each other. At the level above corpectomyl all tested fixation methods did not improve the axial rotational stability beyond the intact case, but reduced flexion, extension, and lateral bending motions significantly (p<0.001). The addition of hook or screw on the short segment pedicle screw construct showed significant stability in all motions (p<0.001) as compared to the short segment pedicle screw construct and their stabilities were similar with each other. CONCLUSIONS: All fixation methods showed more stabilities in all motions than normal specimen. The addition of pedicle screw on the short segment pedicle screw constructs are more stable than the addition of hook, but there was no statistical difference. Adding one level of fixation cranial to the fracture using pedicle screws or hooks may be necessary to decrease the rate of clinical failure and to enhance the stability of the construct with short segment pedicle instrumentation
Incidence ; Pliability ; Spine ; Transplants ; Weights and Measures

The vertical and sagittal diameter of the vertebral body from the 12th thoracic to the 4th lumbar spine was measured by the true lateral roentgenogram. The material consisted of 110 normal Koreans ranging from the age of newborns up to adolescents, in which the vertebral body index (Ivb = v/s) and the intervertebral disk index (id = d/v) of each spine were measured and its interrelationship with normal growth rate was evaluated. The authors obtained the following results. 1. The vertebral body index showed gradual decrease with the advance of the age. It was significantly high in the group Ⅰ compared with other groups. 2. The difference between the boy and the girl was more significant at the 12th thoracic and 1st lumbar vertebral body than the othervertebrae in the group V. 3. Among children of more than 120 cm in height and older than 12 years of age, girls had a higher index of vertebral body than boys, the latter show a less pronounced vertical growth of the body. 4. The intervertebral disk index began to decrease after the 1st month of life possibly because of the accelerated vertical growth of the body from that period. 5. Of all the age groups, the intervertebral disk index showed a higher value in boys than in girls.
Adolescent ; Child ; Female ; Humans ; Infant, Newborn ; Intervertebral Disc ; Male ; Spine

12 cases of Thompson's quadricepsplasty for extra-articular ankylosis of the knee joints which we experienced, were evaluated and analyzed. We obtained the following results. 1. Most of our cases had fracture in the middle one third of the femur. 2. Average 62.5 degrees of flexion range was gained by the operation. 3. Among the 2 cases in which extension lag existed before the operation, it has disappeared in one and still remained in the other case after the operation. 4 cases of new extension lags appeared after the operation. Average extension lag after the operation was 13 degrees. 4. Immediate postoperative exercises and adequate physiotherapy are considered to be very important.
Ankylosis ; Exercise ; Femur ; Knee Joint ; Knee

The bone is the dynamic living tissue which is always maintained bone mineral content by bone resorption and formation. It has been well known that the bone mineral content is decreased very slowly with aging. It is very difficult to diagnose the osteopenia because it is almost subclinical. Another important problem in the osteopenia is the fracture occurring spontaneously. The quantitative method of bone mineral mass provide an information to diagnose the osteopenia and predict the risk of spontaneous fracture. Various methods have been used to access the degree of bone atrophy but have not been routinely available for clinical application in the hospital. The microdensitometric method is a noninvasive, easy, accurate, and objective one to monitor the degree of changes in the skeletal mass quantitatively. So, we measured the 7 indices at the middle site of the 2nd metacarpal bone with a microdensitometer and computer on an X-ray film of the hands and studied the correlations between the age and indices of those under 30 and over 30 yrs old in healthy and fracture groups. The results were obtained as follows : 1. There was a significant high correlation between age and indices in healthy and fracture groups. 2. The measurement of age by microdensitometric method was highly correlated with the chronological age. 3. Comparing both groups, There was a significant correlation of D (P<0.001), MCI(P<0.01), and d (P<0.01) over 30 yrs in male and GSmin (P<0.001) and ΣGS/D (P<0.01) over 30 yrs in female. 4. In fracture group, 1) The index of bone width(D) was slightly larger than in the healthy group. 2) The metacarpal index(MCI) was lower than in the healthy group. 3) The index of medulla width(d) was wider than in the healthy group. 4) The density index of cortex(GSmax) was smaller than in the healthy group. 5) The density index of cortex and medulla(GSmin) was smaller than in the healthy group. 6) There was no considerable difference in ΣGS/D between healthy and fracture groups. 7) The densitometric pattern was more aggrevated than in the healthy group.
Aging ; Atrophy ; Bone Density ; Bone Diseases, Metabolic ; Bone Resorption ; Female ; Fractures, Spontaneous ; Hand ; Humans ; Male ; Methods ; Miners ; Radiography ; X-Ray Film

No abstract available.
Animals ; Cyclophosphamide* ; Food Deprivation* ; Mice*

No abstract available.
Animals ; Cyclophosphamide* ; Food Deprivation* ; Mice*

No abstract available.

No abstract available.
Forearm* ; Humerus*

No abstract available.
Fracture Fixation, Intramedullary*

No abstract available.
Spine*