ABSTRACT
This study was performed to evaluate the fatigue strength of commonly used small diameter tibial nails. Five types of small diameter tibial nails (7 mm aap Biorigid Nail, 8 mm aap Biorigid Nail, 8 mm Ace UTN, 8 mm RT Tibial Nail, 8 mm Synthes UTN) with a sample size of 30 implants (six samples of each nail type) were tested with a new modular testing system. One module of the testing system was removed, simulating a 55-mm distal tibial defect, to induce maximum loading on the distal portion of the implant and locking bolts. The average yield strengths were obtained from static, single cycle tests and revealed an average static ultimate load of 1072 N (aap7), 1820 N (aap8), 1812 N (Ace), 1942 N (R&T), and 1543 N (Syn). The fatigue limits were evaluated by cyclic, sinusoidal loading and revealed a fatigue strength of 750 N (aap7), 1092 N (aap8), 906 N (Ace), 971 N (R&T), and 771 N (Syn) to endure 500000 cycles. Our results showed that the solid tibial nails fractured in the testing device in the same manner and location as they do in the clinical series. This study showed that all the small diameter tibial nails tested are obviously able to transmit loads of more than average body weight. The fatigue strength of the implants is relatively high, which means that patients without bone defects could be mobilised with full weight bearing as tolerated by pain. However, according to the results of this study, early mobilisation with full weight bearing in a normal gait cycle can not be suggested in patients with segmental tibial fractures or fractures with defect zones.
Subject(s)
Bone Nails , Fracture Fixation, Internal , Tibial Fractures/surgery , Weight-Bearing , Biomechanical Phenomena , Contraindications , Early Ambulation , Humans , Materials Testing , Prosthesis Failure , Sample SizeABSTRACT
Unreamed nailing with solid tibial nails is an accepted method of treatment for open tibial shaft fractures up to grade III and of closed tibial fractures with severe soft tissue damage. However, fatigue failure of the distal locking bolts is a frequent complication. We report a mechanical study investigating the fatigue limit of six different types of locking bolts used in solid tibila nails (Biorigid Tibial nail/aap, UTN/ace, STN/Howmedica, TLN/Howmedica, delta R & T Tibial nail/Smith & Nephew, AO/ASIF UTN/Synthes). Our results prove a direct correlation between the bolt's diameter and mechanical properties. Further more we found that bolts with a continuing thread were weaker than bolts of the same diameter with only a short thread and an increased diameter at the nail's aperture. Our results suggest that mobilization with half of the average body weight (350N) allows osseous consolidation without fatique failure of any of the tested locking bolts. Some of the tested locking bolts may even withstand full wieght-bearing in a physiological walking cycle, but will not withstand the stress of a running cycle.
Subject(s)
Equipment Failure Analysis , Fracture Fixation, Intramedullary/instrumentation , Tibial Fractures/surgery , Weight-Bearing/physiology , Biomechanical Phenomena , Equipment Design , Humans , Microscopy, Electron, Scanning , Tibial Fractures/physiopathologyABSTRACT
It is proved, that the physiological interpretation of the peaks in the quadriceps femoris muscle twitch mechanogramme is possible. The measuring chain (sensor-amplifier-magnetic data recorder-plotter) has a resonance frequency of 170 Hz and is suitable for the true representation of the tension-time-course. In order to compare the tensions with one another, it is necessary to standardize the tensions on the lower leg or body mass. Considering the fact that the twitch mechanogramme is a summation of the contractions of the fast twitch fiber (FTF) and slow twitch fiber population (STF), it has been assumed that both FTF and STF show contraction peaks. Essential methodological influences on the tension-time-course result from the relationship between tension sensor and biological system (lower leg mass). The measuring chain and lower leg mass represent a feather-mass system. The provoked oscillations of the lower leg mass may produce methodological peaks in the twitch mechanogramme. In general, the mechanogramme shows contractions superimposed by mechanical processes. The tonogramme shows that the tension-time-course of the twitch is characterized by several peaks too. In the tonogramme characteristic changes depending on the portion of the quadriceps femoris muscle (rectus femoris, vastus lateralis) can be seen. Following the muscle action potential (MAP) there are frequently reflex-MAP's variable in form and amplitude in the time range between 120-180 ms after the stimulus impulse. They allow to explain the peaks in the mechanogramme with contraction times (CT) of 140-160 ms, or they provoke an extension of the relaxation times. Some reflex-MAP may have a latency of only 80 ms. The analysis of the methodological components influencing the mechanogramme of the muscle twitch shows that the interpretation as FT- or ST-peaks has to be done from the point of view of physiology. The following results indirectly speak for the interpretation as FT- or ST-peaks (CT: 30-50 ms and 75 to 95 ms, respectively). There are the corresponding average CT for groups with clearly different lower leg mass, the relatively higher increase of the peaks with CT between 60-70 ms after a maximal voluntary contraction (MVC) of 10 seconds, the higher average tensions for the ST-peaks by long distance runners and the results for the CT when the lower leg mass is artificially elevated. Furthermore the mechanogrammes of the long distance runners show that the maximum may come to a CT of 100-130 ms.(ABSTRACT TRUNCATED AT 400 WORDS)
Subject(s)
Muscle Contraction , Muscles/physiology , Adolescent , Adult , Body Weight , Child , Electrophysiology/instrumentation , Electrophysiology/methods , Female , Humans , Leg , Male , Organ Size , ReflexABSTRACT
The left and right quadriceps femoris muscle (QFM) of 11 to 13-years old children and of 10 adult sportmen was stimulated supramaximally by a single shock. Simultaneously the muscle action potential (MAP) and the mechanogramm (MG) was recorded. In the MG of both groups several maxima appeared with averaged contraction times (CT) between 43-47 ms, 80-86 ms and 115-126 ms in the left as well as right position. In some cases maxima of approximately 65 ms and between 140-160 ms were found. The CT from test to retest varied about 1-7% and the amplitude about 7, 5% and 4%. The maxima of the left QFM having a CT of about 47 ms and 84 ms were significantly higher than on the right one. At the left muscle an aerobic load of 1 W/kg body mass elicited a significant reduction of the maximum by 84 ms. The remaining difference to the right muscle is 10-15%. It was concluded, that the maxima of the mean CT of 43-47 ms and 80-86 ms are those of the FTF- and STF-populations. The maxima of 65 ms should be due to the FTO-fibres and the maxima higher than 100 ms must be explained by evoked responses of the motoneurones. The reaction of the ST-amplitudes is due to extensibility changes and the remained difference shows the higher potential strength of the STF at the left muscle. Within the potentiation of the formerly recruited FTF.
Subject(s)
Muscles/physiology , Muscular Diseases/diagnosis , Adolescent , Adult , Child , Electric Stimulation , Electromyography/methods , Evoked Potentials , Humans , Leg , Motor Neurons/physiology , Muscle ContractionABSTRACT
A clinical study of the cases of acute abdomen in 1970 and in 1980 has been conducted in two surgical departments (Zoug and Olten, Switzerland). In 660 cases the question was investigated whether progress has been made with the introduction of technical aids during the last ten years. In 1980 more specialized methods such as sonography, laparoscopy etc. were employed. Preoperative diagnosis was significantly improved and the agreement between pre- and postoperative diagnosis was markedly ameliorated.
Subject(s)
Abdomen, Acute/etiology , Intestinal Diseases/diagnosis , Abdominal Injuries/diagnosis , Adult , Appendicitis/diagnosis , Cholecystitis/diagnosis , Diagnosis, Differential , Humans , Intestinal Obstruction/diagnosis , Pancreatitis/diagnosisABSTRACT
A multicentric, double-blind, randomized, parallel-group study was performed in patients with fever of diverse origin to test the tolerance and the antipyretic activity of single oral doses of 4-(p-fluorophenyl)-1-isopropyl-7-methyl-2(1H)-quinazolinone (fluproquazone) (200 mg, n = 18), acetylsalicylic acid (ASA) (1000 mg, n = 22) and placebo (n = 19). Whereas with placebo mean rectal temperature remained constant, a continuous fall was recorded with both active medications over the whole 3-h study period. With fluproquazone normalization of body temperature was nearly reached. Fluproquazone was more effective than placebo (p less than 0.001) and ASA (p less than 0.1), which in turn was more active than placebo (p less than 0.0001). No specific side-effects occurred.
Subject(s)
Anti-Inflammatory Agents, Non-Steroidal , Fever/drug therapy , Quinazolines/therapeutic use , Adult , Aspirin/therapeutic use , Body Temperature , Female , Fever/physiopathology , Humans , Male , Middle Aged , QuinazolinonesABSTRACT
In 4 double-blind, randomized, stratified, parallel group studies, single oral doses of fluproquazone (75 to 200 mg), a new nonsteroidal anti-inflammatory analgesic, were compared with aspirin (1,000 mg) and placebo in a total of 672 hospitalized patients with moderate or severe pain following episiotomy or other surgical interventions. A dose-dependent effect of fluproquazone which was highly significantly superior to placebo and which resembled the effect of aspirin with respect to onset, degree, and duration was noted in all studies. Fluproquazone, 100 to 150 mg, was found to be approximately equiactive to 1,000 mg of aspirin and better tolerated.
