RESUMEN
This article discusses recent innovations in the management of distal radius fractures. Clinical and biomechanical studies have shown that stable fixation can be achieved with small implants aligned in an orthogonal fashion. This technique greatly diminishes the necessary soft tissue dissection needed at surgery and allows for early mobilization of the wrist, which may lead to improved outcomes and fewer soft tissue complications.
Asunto(s)
Fijación Interna de Fracturas/métodos , Fracturas del Radio/cirugía , Adulto , Fenómenos Biomecánicos , Femenino , Humanos , Fijadores Internos , Masculino , Persona de Mediana Edad , Rango del Movimiento ArticularRESUMEN
To compare stability of wrist external fixation, simulated unstable extra-articular distal radius fractures were created in 7 fresh-frozen cadaveric upper extremities and stabilized using 4 different external fixators. Physiologic muscle tension across the wrist was simulated by application of 40-N load distributed among the wrist tendons. Alternating loads of up to 100 N in flexion and extension of the wrist were applied during stability testing and 3-dimensional kinematics of the proximal and distal fracture fragments were determined using attached infrared light-emitting diodes and a 3-dimensional motion tracking system. Fracture stability was reassessed for each of the constructs after augmentation of the fracture fragments with a single dorsal transfixion K-wire. K-wire augmentation demonstrated a significant reduction in motion of the distal radial fragment of at least 40% in all 3 rotational planes. For flexion/extension, the reduction in motion was from 4.5 degrees to 2.6 degrees. For radial/ulnar deviation, the range of motion decreased from 3.0 degrees to 1.5 degrees. Rotational motion declined from an average of 3.2 degrees to 1.2 degrees. The addition of the single dorsal transfixion K-wire significantly improved stability of each of the 4 fixators in at least 1 of the 3 planes in which motion was measured. While we compared the most rigid with some of the least rigid external fixators, the data do not support an important difference in fracture fragment stability among the 4 fixators. The data much more strongly support the concept of K-wire augmentation for increasing stability of an unstable extra-articular distal radius fracture regardless of the type of external fixator that is used.
Asunto(s)
Fijadores Externos , Fracturas del Radio/cirugía , Fenómenos Biomecánicos , Cadáver , Estudios de Evaluación como Asunto , Humanos , Fracturas del Radio/fisiopatología , Rango del Movimiento ArticularRESUMEN
Although much has been written about surgical treatment of arthritis of the first carpometacarpal joint, no literature exists on splinting as a conservative treatment. One hundred fourteen patients (130 thumbs) were retrospectively reviewed to determine the efficacy of splinting. Patients were grouped according to their stage of disease and whether they had carpometacarpal joint surgery. Seventy-six percent of patients with stage I and II disease and 54% of patients with stage III and IV disease had improvement in their symptoms with splinting. There was no significant difference in the degree of improvement between the 2 groups. All patients who had initial improvement in their symptoms with splinting had between 54% and 61% average improvement in symptom severity 6 months after splinting. All groups were found to be equally tolerant of the splinting protocol and no group had a significantly higher rate of activity modification. Overall, splinting was found to be a well-tolerated and effective conservative treatment to diminish, but not completely eliminate, the symptoms of carpometacarpal joint arthritis and inflammation.
Asunto(s)
Artritis/terapia , Férulas (Fijadores) , Pulgar , Actividades Cotidianas , Adulto , Anciano , Anciano de 80 o más Años , Artritis/cirugía , Femenino , Humanos , Masculino , Persona de Mediana Edad , Dolor/etiología , Manejo del Dolor , Estudios Retrospectivos , Encuestas y Cuestionarios , Resultado del Tratamiento , Articulación de la MuñecaRESUMEN
External fixation of fractures of the distal end of the radius neutralizes external forces and maintains axial alignment during healing. As far as we know, there have been no biomechanical studies of the effects of early removal of the fixator in a partially healed fracture model. The purpose of the present study was to observe the load-displacement behavior of a distal radial fracture model in which we had simulated partial healing by injection of butyl-rubber caulk and augmented this simulated healing with Kirschner-wire fixation. Sixteen fresh-frozen hand-wrist-forearm specimens from cadavera were mounted in mid-rotation in resin pots, and a load was applied. An osteotomy was used to simulate the fracture. Relative motion at the site of the osteotomy was compared, with use of a three-dimensional Optotrak kinematic device, during physiological loading of six constructs with Kirschner-wire transfixion or outrigger fixation. In the experimental group, partial healing was simulated by injection of butyl-rubber caulk into the site of the osteotomy and testing with simulated muscle-loading was performed through a full range of motion of the wrist. No difference could be detected between the relative motion at the osteotomy sites that had been treated with standard fully augmented external fixation and that in the experimental group (p > 0.05). T test analysis revealed that motion was equivalent regardless of whether Kirschner-wire transfixion or outrigger fixation had been used (p = 0.62) and that all of the augmented constructs had significantly less relative motion than all of the nonaugmented constructs (p < 0.001).
Asunto(s)
Fractura de Colles/fisiopatología , Fijación de Fractura/métodos , Curación de Fractura/fisiología , Rango del Movimiento Articular/fisiología , Articulación de la Muñeca/fisiopatología , Hilos Ortopédicos , Cadáver , Fractura de Colles/cirugía , Fijadores Externos , Humanos , Modelos Biológicos , Osteotomía , Soporte de Peso/fisiologíaRESUMEN
An in vitro model of an unstable extra-articular distal radius fracture was created in 8 fresh-frozen cadaveric specimens and stabilized with an external fixator. Rotation and translation kinematics of the distal radial fracture fragment were measured in relation to the proximal radius during physiologic loading, using infrared light-emitting diodes and a 3-dimensional motion-sensing device. The effect of supplemental single and combination Kirschner wire (K-wire) fixation on fracture fragment stability was assessed. Fixation of supplemental K-wires to the fixator frame via a custom-developed outrigger assembly was also analyzed. Significant reductions in sagittal plane (flexion/extension) rotation and neutral zone were recorded when the fracture fragment was stabilized with a single styloid or dorsal transfixion K-wire. Equivalent stability was afforded by attachment of a nontransfixion K-wire to the fixator frame via the outrigger assembly. The dorsal constructs compared favorably to the styloid constructs in reduction of the sagittal plane neutral zone and coronal (radioulnar) rotation. These data lend biomechanical support to the concept of augmentation of distal radius external fixation and provide a physiologic model to test fixation methods for other fracture patterns.
Asunto(s)
Hilos Ortopédicos , Fractura de Colles/cirugía , Fijadores Externos , Fijación de Fractura/métodos , Traumatismos de la Muñeca/cirugía , Cadáver , Fractura de Colles/fisiopatología , Humanos , Rango del Movimiento Articular/fisiología , Estrés Mecánico , Traumatismos de la Muñeca/fisiopatología , Articulación de la Muñeca/fisiopatologíaRESUMEN
To clarify mechanisms underlying an enhanced susceptibility to cardiac rhythm disturbances in hypertension and myocardial hypertrophy, we evaluated the vulnerability to histamine-induced arrhythmias of isolated left ventricles from spontaneously hypertensive rats (SHR) and age-matched controls (Wistar-Kyoto rats, WKY). Before drug administration, left ventricle-to-body weight ratios, spontaneous firing rates, and the incidence of arrhythmias (including delayed afterdepolarizations) were significantly increased in SHR ventricles versus WKY. In addition, action potential duration (APD) was prolonged in SHR at all levels of repolarization. In WKY but not SHR hearts, histamine (10(-7)-10(-4) M) increased spontaneous firing rates; the incidence of arrhythmias was increased in all hearts, but the response to histamine was most pronounced and occurred at lower threshold drug levels in SHR. After potentials and triggered activity were observed only in SHR. The H2-receptor blocker cimetidine (10(-5) M) and the Ca2(+)-channel antagonist verapamil (10(-6) M) each attenuated the arrhythmogenic influence of histamine in SHR and WKY preparations. Neither chlorpheniramine nor propranolol had any effect. The enhanced vulnerability to arrhythmogenesis observed in SHR myocardium may reflect elevated intracellular calcium levels, which may in turn be potentiated by local ischemia and/or intracardiac histamine release.
Asunto(s)
Arritmias Cardíacas/inducido químicamente , Histamina/farmacología , Potenciales de Acción/efectos de los fármacos , Animales , Cimetidina/farmacología , Susceptibilidad a Enfermedades , Interacciones Farmacológicas , Técnicas In Vitro , Masculino , Ratas , Ratas Endogámicas SHR , Ratas Endogámicas , Especificidad de la Especie , Verapamilo/farmacologíaRESUMEN
A potential physiological role for cardiac histamine and its interaction with norepinephrine were investigated in isolated left ventricles from spontaneously hypertensive rats (SHR). Prior to drug administration, left ventricle-to-body weight ratios and spontaneous firing rates (beats per min) were significantly increased in SHR ventricles vs. age- and sex-matched controls (WKY). Also, action potential duration was significantly prolonged in SHR at all levels of repolarization. In all hearts, norepinephrine (10(-7)-10(-4) M) increased spontaneous rate and the percent incidence of arrhythmias. The H2-receptor antagonist cimetidine (10(-5) M) potentiated the rate and arrhythmogenic effects of norepinephrine in SHR and, to a lesser extent, in WKY preparations; propranolol (10(-6) M) reduced them. Histamine (10(-7) M) also inhibited the norepinephrine-induced increase in arrhythmias in SHR, but not in WKY. The attenuation of adrenergically induced rhythm disturbances by histamine and their potentiation by cimetidine in hypertensive hearts support the hypothesis that histamine plays a role as a postjunctional modulator of adrenoceptor function in a setting of hypertension and myocardial hypertrophy.