RESUMEN
OBJECTIVE: To determine the influence of the number of cortices of fixation on the stiffness of plate fixation of diaphyseal fractures. DESIGN: Canine experimental study. SETTING: Tertiary referral and teaching hospital in Toronto, Canada. PARTICIPANTS: Paired radii from fourteen skeletally mature, cross-bred dogs. MAIN OUTCOME MEASURE: One member of each pair of radii was tested intact as a control, and the other had a transverse osteotomy plated sequentially with five to ten cortices of fixation on either side of the simulated fracture. Dynamic compression plates and limited contact dynamic compression plates were used in two groups with seven paired radii each. Normalized torsional stiffness and four-point bending stiffness were determined in the elastic range for the control and each of the plated constructs in both groups, using a materials testing machine. RESULTS: The authors found no significant difference between the stiffness of the dynamic compression plates and limited contact dynamic compression plates. With either plate of a given length, significantly increased torsional stiffness is achieved with end bicortical screws. For bending stability with the plate at right angles to the bending plane, even short plated constructs have a stiffness exceeding that of intact bone. CONCLUSIONS: For a transverse osteotomy with no fracture interdigitation, the bending rigidity with the plate at right angles to the bending plane is greater than the original stiffness of the bone for all constructs tested, with the exception of the limited contact dynamic compression plate with five cortices of fixation. The torsional rigidity of fixation only approaches the original rigidity of the bone for ten cortices of fixation with the dynamic compression plate and the limited contact dynamic compression plate.
Asunto(s)
Fenómenos Biomecánicos , Placas Óseas , Fijación Interna de Fracturas/instrumentación , Ensayo de Materiales , Fracturas del Radio/cirugía , Animales , Modelos Animales de Enfermedad , Perros , Elasticidad , Diseño de Equipo , Seguridad de Equipos , Femenino , Fijación Interna de Fracturas/métodos , Masculino , Fracturas del Radio/patología , Valores de Referencia , Sensibilidad y EspecificidadRESUMEN
OBJECTIVE: To determine the immediate effect of reaming and insertion of the acetabular component with and without cement on peri-acetabular blood flow during primary total hip arthroplasty (THA). DESIGN: A clinical experimental study. SETTING: A tertiary referral and teaching hospital in Toronto. PATIENTS: Sixteen patients (9 men, 7 women) ranging in age from 30 to 78 years and suffering from arthritis. INTERVENTION: Elective primary THA with a cemented (8 patients) and non-cemented (8 patients) acetabular component. All procedures were done by a single surgeon who used a posterior approach. MAIN OUTCOME MEASURE: Acetabular bone blood-flow measurements made with a laser Doppler flowmeter before reaming, after reaming and after insertion of the acetabular prosthesis. RESULTS: Acetabular blood flow after prosthesis insertion was decreased by 52% in the non-cemented group (p < 0.001) and 59% in the cemented group (p < 0.001) compared with baseline (pre-reaming) values. CONCLUSION: The significance of these changes in peri-acetabular bone blood flow during THA may relate to the extent of bony ingrowth, peri-prosthetic remodelling and ultimately the incidence of implant failure because of aseptic loosening.
Asunto(s)
Acetábulo/irrigación sanguínea , Artroplastia de Reemplazo de Cadera/efectos adversos , Artroplastia de Reemplazo de Cadera/métodos , Cementos para Huesos/efectos adversos , Complicaciones Intraoperatorias/etiología , Isquemia/etiología , Adulto , Anciano , Análisis de Varianza , Presión Sanguínea , Resorción Ósea/etiología , Femenino , Humanos , Incidencia , Complicaciones Intraoperatorias/diagnóstico , Complicaciones Intraoperatorias/fisiopatología , Isquemia/diagnóstico , Isquemia/fisiopatología , Flujometría por Láser-Doppler/métodos , Masculino , Persona de Mediana Edad , Monitoreo Intraoperatorio/métodos , Osteoartritis de la Cadera/cirugía , Falla de PrótesisRESUMEN
BACKGROUND: The objective of this study was to determine the individual and combined effects of pulmonary contusion and fat embolism on the hemodynamics and pulmonary pathophysiology in a canine model of acute traumatic pulmonary injury. METHODS: After a thoracotomy, twenty-one skeletally mature dogs were randomly assigned to one of three groups. Unilateral pulmonary contusion alone was produced in Group 1 (seven dogs); pulmonary contusion and fat embolism, in Group 2 (seven dogs); and fat embolism alone, in Group 3 (seven dogs). Pulmonary contusion was produced by standardized compression of the left lung with a piezoelectric force transducer. Fat embolism was produced by femoral and tibial reaming followed by pressurization of the intramedullary canals. Cardiac output, systolic blood pressure, peak airway pressure, pulmonary arterial pressure, pulmonary capillary wedge pressure, partial pressure of arterial oxygen, and partial pressure of carbon dioxide were monitored for all groups. From these data, several outcome parameters were calculated: total thoracic compliance, alveolar-arterial oxygen gradient, and ratio of partial pressure of arterial oxygen to fractional inspired oxygen concentration. All of the dogs were killed after eight hours, and tissue samples were obtained from the brain, kidneys, and lungs for histological analysis. Lung samples were assigned scores for pulmonary edema (the presence of fluid in the alveoli) and inflammation (the presence of neutrophils or hyaline membranes, or both). The percentage of the total area occupied by fat was determined. RESULTS: Pulmonary contusion alone caused a significant increase in the alveolar-arterial oxygen gradient but only after seven hours (p = 0.034). Fat embolism alone caused a significant transient decrease in systolic blood pressure (p = 0.001) and a significant transient increase in pulmonary arterial pressure (p = 0.01) and pulmonary capillary wedge pressure (p = 0.015). Fat embolism alone also caused a significant sustained decrease in the ratio of partial pressure of arterial oxygen to fractional inspired oxygen concentration (p = 0.0001) and a significant increase in the alveolar-arterial oxygen gradient (p = 0.0001). The combination of pulmonary contusion and fat embolism caused a significant transient increase in pulmonary capillary wedge pressure (p = 0.0013) as well as a significant sustained decrease in partial pressure of arterial oxygen (p = 0.0001) and a significant decrease in systolic blood pressure (p = 0.001) that lasted for an hour. Pulmonary contusion followed by fat embolism caused a significant increase in peak airway pressure (p = 0.015), alveolar-arterial oxygen gradient (p = 0.0001), and pulmonary arterial pressure (p = 0.01), and these effects persisted for five hours. Total thoracic compliance was decreased 6.4 percent by pulmonary contusion alone, 4.6 percent by fat embolism alone, and 23.5 percent by pulmonary contusion followed by fat embolism. The ratio of partial pressure of arterial oxygen to fractional inspired oxygen concentration was decreased 23.7 percent by pulmonary contusion alone, 52.3 percent by fat embolism alone, and 65.8 percent by pulmonary contusion followed by fat embolism. The mean pulmonary edema score was significantly higher with the combined injury than with either injury alone (p = 0.0001). None of the samples from the lungs demonstrated inflammation. Fat embolism combined with pulmonary contusion resulted in a significantly greater mean percentage of the area occupied by fat in the noncontused right lung than in the contused left lung (p = 0.001); however, no significant difference between the right and left lungs could be detected with fat embolism alone. The mean percentage of the glomerular and cerebral areas occupied by fat was greater with fat embolism combined with pulmonary contusion than with fat embolism alone (p = 0.0001 and p = 0.01, respectively). (ABSTRACT TRUNCATED)
Asunto(s)
Contusiones/complicaciones , Embolia Grasa/fisiopatología , Lesión Pulmonar , Embolia Pulmonar/fisiopatología , Resistencia de las Vías Respiratorias , Animales , Presión Sanguínea , Gasto Cardíaco , Perros , Embolia Grasa/etiología , Embolia Grasa/patología , Femenino , Pulmón/patología , Rendimiento Pulmonar , Masculino , Oxígeno/sangre , Circulación Pulmonar , Embolia Pulmonar/etiología , Embolia Pulmonar/patología , Intercambio Gaseoso Pulmonar , Presión Esfenoidal PulmonarRESUMEN
The authors investigated the effect of a posterior surgical approach on the local femoral blood supply during primary total hip arthroplasty. Greater trochanteric blood flow measurements were made with a laser Doppler flowmeter at intervals during the performance of eight uncemented and nine cemented total hip arthroplasties. Complete detachment of the quadratus femoris was associated with a significant decrease in trochanteric blood flow in the uncemented and cemented groups. The lowest perfusion levels during the procedure were seen transiently with posterior dislocation of the femoral head, after which trochanteric perfusion was decreased by 66% in the uncemented group, and 61% in the cemented group compared with baseline values. Blood flow remained approximately half of baseline values after insertion of the femoral prosthesis in the uncemented and cemented groups. These changes in greater trochanteric blood flow may serve as a marker for reduction in proximal femoral blood flow during total hip arthroplasty, and subsequently relate to the extent of bony ingrowth, periprosthetic bone loss, and ultimately the incidence of implant failure caused by aseptic loosening.
Asunto(s)
Fémur/irrigación sanguínea , Adulto , Artroplastia de Reemplazo de Cadera , Cementación , Femenino , Necrosis de la Cabeza Femoral/cirugía , Hemodinámica , Luxación de la Cadera/cirugía , Humanos , Flujometría por Láser-Doppler , Masculino , Persona de Mediana Edad , Osteoartritis de la Cadera/cirugía , Flujo Sanguíneo RegionalRESUMEN
OBJECTIVE: To alert surgeons who perform arthroplasty to the possibility of acute colonic pseudo-obstruction (Ogilvie's syndrome) after elective orthopedic procedures. To identify possible risk factors and emphasize the need for prompt recognition, careful monitoring and appropriate management so as to reduce morbidity and mortality. DESIGN: A case series. SETTING: A university-affiliated hospital that is a major referral centre for orthopedic surgery. PATIENTS: Four patients who had Ogilvie's syndrome after lower extremity arthroplasty. Of this group, 2 had primary hip arthroplasty, 1 had primary knee arthroplasty and 1 had revision hip arthroplasty. MAIN OUTCOME MEASURES: Morbidity and mortality. RESULTS: In all 4 patients Ogilvie's syndrome was recognized late and required surgical intervention. Two patients died as a result of postoperative complications. CONCLUSIONS: Our case series identified increasing age, immobility and patient-controlled narcotic analgesia as potential risk factors for Ogilvie's syndrome in the postoperative orthopedic patient. Prompt recognition and early consultation with frequent clinical and radiographic monitoring are necessary to avoid colonic perforation and its significant associated death rate.
Asunto(s)
Artroplastia de Reemplazo de Cadera , Artroplastia de Reemplazo de Rodilla , Seudoobstrucción Colónica/etiología , Complicaciones Posoperatorias , Anciano , Seudoobstrucción Colónica/diagnóstico por imagen , Diagnóstico Diferencial , Resultado Fatal , Humanos , Masculino , Persona de Mediana Edad , RadiografíaRESUMEN
This study was conducted to determine the effect of intramedullary reaming and canal preparation on bone blood flow in the proximal femur. Thirty-five adult dogs were randomly assigned to have their intramedullary canals prepared after reaming in the following manner: group 1, ream only; group 2, lavage; group 3, methylmethacrylate cement introduction; group 4, cement pressurization after placing a cement restrictor; group 5, lavage then cement introduction; and group 6, lavage then cement pressurization. Bone blood flow was measured at both metaphyseal and diaphyseal sites by using laser Doppler flowmetry before reaming, after reaming, after lavage, after cementing, and at 6 weeks after the procedure just before euthanasia. Reaming significantly decreased bone blood flow in the diaphysis (P = .046) but not in the metaphysis. Cement introduction and cement pressurization both significantly decreased bone blood flow in the metaphysis (P = .035, P = .004) and diaphysis (P = .007, P = .029). Pressurization of cement had a significantly greater relative effect than cement introduction alone in the diaphysis (P = .006) but not in the metaphysis. Lavage had no effect on bone perfusion. Bone blood flow was significantly increased at 6 weeks after the initial procedure in both the metaphysis (P = .049) and the diaphysis (P = .004). The results suggest that reaming decreases diaphyseal cortical but not metaphyseal bone blood flow significantly, whereas lavage has no effect. Cement introduction with or without pressurization has a significant detrimental effect on metaphyseal and diaphyseal blood flow. These findings have implications for intramedullary nailing and for canal preparation when performing arthroplasty.
Asunto(s)
Artroplastia de Reemplazo de Cadera , Fémur/irrigación sanguínea , Fémur/cirugía , Flujometría por Láser-Doppler , Animales , Artroplastia de Reemplazo de Cadera/métodos , Cementación , Perros , Femenino , Masculino , Flujo Sanguíneo Regional , Irrigación TerapéuticaRESUMEN
The management of unstable phalangeal fractures has been associated with significant morbidity. Percutaneous transmetacarpal intramedullary Kirschner wire fixation of proximal phalangeal fractures has been described as a useful technique. We present a retrospective review of 35 digits in 24 patients with unstable fractures of the proximal phalanx treated using this technique between 1985 and 1995. Outcome measures, including radiological adequacy of reduction, total active range of motion, development of joint contracture, grip strength, and digital grip strength, were assessed. Good or excellent results were obtained in 76% of fractures (19 of 25) that were treated and followed. Thirty-two percent of digits (8 of 25) treated developed a proximal interphalangeal joint flexion contracture. Flexion contracture averaged 18.1 deg at the involved joints. Seven secondary procedures were required in 6 patients. Major complications noted during the study included loss of reduction with rotational deformity in four digits, and one nonunion. The use of skeletal traction devices was associated with three of the major complications observed. These devices should not be used concurrently on or adjacent to any digit treated by intramedullary pinning. We conclude that transmetacarpal axial Kirschner wire fixation is a technically simple method of treating unstable proximal phalangeal fractures, and good or excellent results can be obtained in the majority of appropriately selected patients.
Asunto(s)
Hilos Ortopédicos , Traumatismos de los Dedos/cirugía , Fijación Intramedular de Fracturas , Fracturas Óseas/cirugía , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Femenino , Humanos , Masculino , Persona de Mediana Edad , Complicaciones Posoperatorias , Estudios Retrospectivos , Resultado del TratamientoRESUMEN
OBJECTIVE: To determine the effect of retrograde femoral reaming on the blood flow of the distal femur and the cruciate ligaments. DESIGN: Canine experimental study. SETTING: Tertiary referral and teaching hospital in Toronto, Canada. PARTICIPANTS: Thirteen skeletally mature, cross-bred dogs. MAIN OUTCOME MEASURE: Red cell flux (RCF) was measured by using a laser Doppler flowmetry probe at three bone sites in the distal femur (trochlear groove, medial condyle, and lateral condyle) and at the midportion of both the anterior and posterior cruciate ligaments before and after retrograde femoral reaming. RESULTS: There was a significant increase in the mean postreaming RCF at all the bone sites of the distal femur compared with prereaming values: trochlear groove (p = 0.0247), medial condyle (p = 0.0440), and lateral condyle (p = 0.0042). We also found a significant decrease in the mean postreaming RCF at both cruciate ligament sites compared with prereaming values (anterior cruciate, p = 0.0004; posterior cruciate, p = 0.0006). CONCLUSIONS: Retrograde femoral reaming and intramedullary nailing has become a popular option for the treatment of distal femoral and some femoral shaft fractures, but concerns regarding the effect of reaming through an intraarticular entry portal have been raised. Our experimental study found that after reaming perfusion of the anterior cruciate ligament decreased by 52 percent and perfusion of the posterior cruciate ligament decreased by 49 percent. Diminished perfusion after reaming may delay healing or exacerbate existing injury to the cruciate ligaments and adversely affect rehabilitation of the knee after femoral fracture.
Asunto(s)
Ligamento Cruzado Anterior/irrigación sanguínea , Arteria Femoral/fisiología , Fracturas del Fémur/cirugía , Fijación Intramedular de Fracturas/efectos adversos , Ligamento Cruzado Posterior/irrigación sanguínea , Animales , Velocidad del Flujo Sanguíneo , Modelos Animales de Enfermedad , Perros , Eritrocitos/fisiología , Femenino , Fijación Intramedular de Fracturas/métodos , Flujometría por Láser-Doppler , MasculinoRESUMEN
We examined the roles of methylmethacrylate (MMA) monomer and cementing technique in the formation, and haemodynamic outcome, of pulmonary fat emboli. The preparation of the femoral canal and the cementing technique were studied in four groups of adult dogs as follows: control (no preparation); lavage; cement pressurisation; and cement pressurisation after lavage. We measured the intramedullary pressure, pulmonary artery pressure (PAP), pulmonary capillary wedge pressure and bilateral femoral vein levels of triglyceride, cholesterol and MMA monomer at rest and after reaming, lavage, and cementing. Femoral vein triglyceride and cholesterol levels did not vary significantly from resting levels despite significant elevations in intramedullary pressure with reaming, lavage and cementing (p = 0.001). PAP was seen to rise significantly with reaming (p = 0.0038), lavage (p = 0.0031), cementing (p = 0.0024) and cementing after lavage (p = 0.0028) while the pulmonary capillary wedge pressure remained unchanged. MMA monomer was detected in femoral vein samples when cement pressurisation was used. Intramedullary lavage before cementing had no significant effect on the MMA level. Haemodynamic evidence of pulmonary embolism was noted with reaming and intramedullary canal preparation, irrespective of the presence of MMA monomer. We found no relationship between MMA monomer level and intramedullary pressure, PAP or pulmonary capillary wedge pressure. Our findings suggest that the presence of MMA monomer in femoral venous blood has no effect on the formation of fat emboli or their pulmonary haemodynamic outcome during cemented hip arthroplasty.