ABSTRACT
PURPOSE: To analyze the effects of various amount of peripheral defect of the acetabulum in terms of the stability of the acetabular cup with screw fixation. MATERIALS AND METHODS: The porous coated acetabular cup of Trilogy was press-fitted with 3 screw fixations after 2 mm undersized reaming into the distal part of 100 bovine femurs, but with insufficient peripheral coverage of 0%, 5%, 10%, 15% and 20% respectively. The micromotions of the acetabular cups were measured under the axial loads of 50, 100, 150, 200, 250, and 300 Kp, and torques were measured at 1degrees to 5degrees of cup rotation under applied rotational force in 10 specimens in each of five groups. RESULTS: The micromotion between the cup and bone interface increased proportionally with peripheral coverage insufficiency and the torque values in the five groups increased in proportion to the rotation degree and were inversely proportinal peripheral coverage insufficiency. CONCLUSION: 15% or less coverage insufficiency of the acetabular cup may be acceptable as the average micromotion is less than 150micrometa and compatible with biologic fixations.
Subject(s)
Acetabulum , Femur , TorqueABSTRACT
Peritrochanteric fractures are common in the elderly, and the mortaliy and morbidity rates after conservative treatment of the fractures are usually high. In these fractures the internal fixation now allows the patient more rapid functional gain. It has been known that for stabilization of fracture the sliding hip screw is superior to other fixation devices. To investigate the biomechanical difference between two different materials of dynamic hip screw, eight intertrochateric and eight subtrochanteric femur fractures were artificially induced in human cadavers. Two femurs were used as the control. In eight cadaver intertrochanteric fractures (Group I), four of them were treated with stainless steel compression hip screw and four were treated with titanium compression hip screw. Eight cadaver subtrochanteric fractures (Group II) were divided by two groups as equal number. One group was treated with stainless steel compression hip screw and the other was treated with titanium compression hip screw with plate. Each femur was secured in a fixation device of the Instron and loaded in a vertical compression. Collapse or fixation failure during vertical compression were observed and recorded continuously in slow speed with deformation rate of 3mm/min. Biomechanical analysis of maximal loading force in the control and experimental two groups were performed. The results were as follows; 1. The mean maximal loading force was 625 kp in control group. 2. The mean maximal loading force in each 4 intertrochanteric fractures fixed with stainless steel DHS (dynamic hip screw) and plate was 92.59 kp, and with titanium DHS and plate was 71.57 kp. There was no statistical significance between stainless steel DHS and plate fixation and titanium DHS and plate fixation. (p>0.05) 3. The mean maximal loading force in each 4 subtrochanteric fractures fixed with stainless DHS and plate was 140.12 kp, and with titanium DHS with plate was 169.4 kp. There was no statistical significance between stainless steel DHS and plate fixation and titanium DHS and plate fixation. (p>0.05) 4. The breakage of metal implant was not occurred at the maximal loading force 600 kp in both group. There was no difference of fixability and stability according to the metal quality, as the results of the experiment of compression loading force to the stainless steel DHS and titanium DHS fixation on intertrochanteric and subtrochanteric fractures in cadaverous femurs.
Subject(s)
Aged , Humans , Cadaver , Femur , Hip Fractures , Hip , Internal Fixators , Stainless Steel , TitaniumABSTRACT
Successful repair of lacerated tendons must restore continuity of the tendon and should yield a strong tenorrhaphy. Mechanical strength of repair should be adequate to early postoperative motion and mobility, The optimal repair technique must be able to withstand the rigors of early motion and also must not interfere with tendon healing. The relative strength of three suture methods of lacerated tendon were measured by mechanical disruption in effort to determine the strength of suture technique. Fifty-four Calcaneal tendons of 27 the New Zealand white rabbit were transected at mid portion and repaired with the three suture technique: group 1, Kessler suture, group 2, Pennington’s modified-Kessler suture and group 3, augmented- Becker suture technique. Each group was composed of 18 calcaneal tendons. Nine rabbits were sacrified immediately after suture, nine in postoperative 2 weeks and nine in postoperative 4 weeks Six calcaneal tendons in each three experimental group were obtained immediately after suture, at postoperative 2 and 4 weeks respectively. Tensile strength, maximum strength and modulus of elasticity of all experimental specimens were measured with Instron-UTM-4-100(Toyo-Baldiwin, Japan). The results were evaluated statistically to compare the strength of the three suture technique at three different periods. The tensile strength was predominantly strongest in augmented-Becker method among three suture technique at immediate suture, postoperative 2 weeks and 4 weeks respectively. The augmented Becker repair was strongest in maximum stress among Kessler and modified Kessler repair at immediate operation, postoperative 2 weeks and 4 weeks respectively. The augmented Becker repair was highest in modulus of elasticity than Kessler method and modified-Kessler method at immediate operation, postoperative 2 weeks and postoperative 4 weeks respectively. Tensile strength, maximum stress and modulus of elasticity were gradually increased from immediate operation to postoperative 4 weeks, but there were not statistically significance between experimental three suture methods at postoperative 4 weeks.
Subject(s)
Rabbits , Elastic Modulus , Methods , New Zealand , Suture Techniques , Sutures , Tendons , Tensile StrengthABSTRACT
The authors analyzed clinical and radiographic results of the 87 cases which had done THRA with porous coated femoral stem followed up more than 2 years to study the difference of clinical and radiologic findings between the absence (group 1 ; 53 cases) and presence(group 2 ; 34 cases) of the porous coating in superolateral portion of the femoral stem. The following results were obtained : 1. Harris hip scores were improved 34.4 points from 56.5 points preoperatively to 90.9 points postoperatively in group Ι, and 32.7 points from 61 points preoperatively to 93.7 points postoperatively in group 2. The clinical results of the group 1 were Excellent in 45 cases, Good in 5 cases and Fair in 3 cases, and clinical result of the group 2 were Excellent in 33 cases and Good in 1 case. 2. The changes of femoral stem angle were below 2 degrees in 7 cases, above 2 degrees in 2 cases in group 1, and below 2 degrees in 5 cases, but not found more than 2 degrees of change of the femoral stem angle in group 2. 3. The osteolysis around femoral stem were 15 cases(28%) in Group 1, and 5 cases(15%) in Group 2. Diffuse osteolysis were 3 cases in Group 1, but was not observed in Group 2. 4. The vertical subsidence more than 2 mm was 3 cases in group 1, but was not observed in group 2. 5. The stable femoral stem were 51 cases in group 1, and 34 cases in group 2. The unstable femoral stem were 3 cases in group 1, but was not observed in group 2. Above results suggest that the porous coating in the superolateral portion of the femoral stem showed better results in radiologic and clinical findings in short term follow up.
Subject(s)
Clinical Study , Follow-Up Studies , Hip , OsteolysisABSTRACT
Reliable and valid evaluation of hand strength is of paramount importance in determining the effectiveness of various normative data area needed to interpret evaluation data, to set realistic treatment goals and to assess a patient's ability to return to employment. The primary purpose of this study was to establish normal value of grip and pinch strength for men women in normal Korean adult. A Jamar dynamometer(Hydraulic Hand Dynamometer. PC 5030, USA) was used to measure grip strength and Jamar pinch gauge(Hydraulic Pinch Gauge, PC 5030HPG, USA)was used to measure tip, key and palmar pinch. Two hundreds forty eight male and two hundreds thiry one female adults, aged 20 to 74 years were tested for using standardized positioning with their shoulder adducted and neutrally rotated, elbow flexed at 90。 and the forearm and wrist in neutral position. Right and left hand data were stratified into age groups for both sexes. This stratification provides a means of comparing the scores of individuals to that of normal subjects of the same aged and sex. The following results were obtained; 1. The average grip strength of the dominant hand was highest(43.9±7.3kg)in 3rd decade male group. 2. The average tip pinch strength of the dominant hand was highest in 4th decade(7.3±3.5kg)and 5th decade (7.3±2.4kg) male group. 3. The average key pinch strength of the dominant hand was highest in 5th decade(8.3±2.3 kg)male group. 4. The average palmar pinch strength of the dominant hand was highest in 4th decade(9.6±3.3 kg)male group. 5. A high correlation was seen between grip strength and age, but a low correlation between pinch strength and age. 6. The average grip strength of dominant hand was 5.6% higher than that of nondominant hand in men, and 6.5% higher in women. 7. In pinch strength, palmer pinch strength was highest among the three groups of pinch strength, then key pinch and tip pinch strength in order. 8. The mean scores of the dominant hand were larger than that of the nondominant hand on all hand strength.