Biomedical subjects
Publications and source records attributed to M F Swiontkowski.
The surgical management of osteomyelitis includes radical debridement on nonviable bone. Laser Doppler flowmetry is a method for directly assessing the functional microcirculation in bone. The early results of the use of this technique as a surgical adjunct in the management of osteomyelitis are promising.
Laser Doppler flowmetry (LDF) has been successfully used in clinical and experimental settings to evaluate bone perfusion but unanswered questions regarding its capabilities and limitations still remain. This study was undertaken to determine absorption of He-Ne laser light (632.8 nm) and maximum depth for flow assessment (threshold thickness) under optimal conditions in bone. Light transmittance in bovine bone samples of femora and tibia was measured after each step of grinding and depth of penetration calculated. The threshold thickness was obtained by placing the same samples in a flow chamber where a solution of 2% latex circulated beneath; flow was detected by a laser Doppler probe resting on top of the sample. The results showed a significantly higher depth of penetration for trabecular than for cortical bone. A regression analysis showed a high correlation between the inorganic fraction of the bone and the depth of penetration. The maximum depth at which the laser Doppler probe can evaluate flow in bone conditions was found to be 2.9 +/- 0.2 mm in cortical bone, 3.5 +/- 0.3 mm in bone covered by 1 mm cartilage and 3.5 +/- 0.2 mm in trabecular bone. The study showed the limitations of LDF in bone and their correlations to various bone properties.
Eleven consecutive median nerves in patients with clinical carpal tunnel syndrome were examined prospectively with laser Doppler flowmetry. All procedures were done without a tourniquet with the patient under local or general anesthesia. Multiple measurements of median nerve blood flow were obtained during carpal tunnel release. Flow characteristics proximal to the transverse carpal ligament did not change after release of the ligament. Beneath the transverse carpal ligament, initial flow was random in 10 of 11 nerves. Within 1 minute after release of the transverse carpal ligament, flow became pulsatile and synchronized with the patient's pulse in nine nerves. Although preliminary, these data suggest that in carpal tunnel syndrome the segment of median nerve beneath the carpal ligament is relatively ischemic and this ischemia may be a factor in the development of symptomatic median nerve entrapment. The rapid return of a pulsatile signal within the nerve after release is positively correlated with relief or improvement of median nerve dysesthesias.
Laser Doppler flowmetry was used intraoperatively to differentiate viable from nonviable bone during the debridement of 12 cases of chronic osteomyelitis and three cases of acute bone infection following trauma. Six weeks of i.v. antibiotic therapy were directed against two cases of gram-positive and 13 cases of gram-negative bone infection. In cases of chronic infection, free muscle flaps were added for soft tissue coverage in five cases and rotational muscle flaps in four cases. At follow-up observation, of 1 to 3 years, no recurrences were seen. Laser Doppler flowmetry is an easy-to-use adjunct to the surgical debridement of bone infection.
Adequate debridement remains the most important factor in prevention of chronic sepsis in cases of massive lower limb trauma. Despite treatment with chronic antibiotics, muscle flaps, hyperbaric oxygen, and/or free-tissue transfer, failures are common due to inadequate bone debridement. All bony fragments with marginal soft-tissue attachments and exposed bone without evidence of adequate blood flow must be removed during debridement for optimal results. Laser Doppler flowmetry (LDF) may be a useful adjunct for the assessment of bone viability during both initial and subsequent debridements. Preliminary data on eight patients have demonstrated that bone blood flow as determined by LDF is highly correlated with clinical outcome. In 13 cases, LDF has proved to be helpful in the management of chronic osteomyelitis.
A randomized, prospective study comparing Ender nailing with external fixation for open fractures of sixty-three tibiae (sixty patients) was undertaken. Ender nailing proved to be at least as effective as external fixation with respect to seven parameters: time to union, tibial alignment, total number of operations, ranges of motion of the knee and ankle, pain, presence of infection, and complications. Ender nailing is a safe alternative to external fixation for grade-I and grade-II open fractures. It should not be used for comminuted fractures, which might shorten about the nails.
The development of laser Doppler flowmetry (LDF) has provided a real-time, reliable method for monitoring capillary perfusion in multiple tissues. LDF has potential for the experimental and clinical assessment of bone blood flow. To compare the accuracy and ease of use of two commercially available laser Doppler flowmeters with different mechanisms for processing the Doppler-shifted component of light, estimates of bone blood flow were obtained in a sheep model using the two systems, and the values derived then compared with estimates of bone blood flow also obtained in a sheep using the technique of injection of labeled microspheres. The single-channel laser Doppler flowmeter, the LD 5000, processes the reference and Doppler-shifted beams on the surface of a single photodetector using optical heterodyning for measurement. The dual-channel flowmeter, the Periflux 2, uses two optical fibers to transmit reference and Doppler-shifted light to two separate photodetectors. The differential amplification and detection system improves the signal-to-noise ratio. Measurement of both metaphyseal (cancellous) and diaphyseal (cortical) blood flow using both LDF systems was compared with values obtained with an injection of 85Sr-labeled microspheres in three sheep. The LDF measurements were repeated after occlusion of the left femoral artery, and a 46Sc microsphere injection was performed prior to animal sacrifice. Two of the animals developed vasomotor instability, resulting in poor correlation between the measurements obtained with the Periflux 2, which is motion sensitive, and the values obtained with the microsphere method. High correlation was apparent in two of the three animals for the LD 5000 and the microsphere values.(ABSTRACT TRUNCATED AT 250 WORDS)
The purpose of this study was to quantitate the blood flow of the anterior cruciate ligament in vivo. Functional flow was evaluated using laser Doppler flowmetry (LDF), for which the output signal, blood cell flux (BCF), is expressed in terms of volts. Ten patients undergoing routine arthroscopic surgery with clinically intact anterior cruciate ligaments were selected at random for participation in the study. Under arthroscopic visualization, a 2.2-mm probe was placed through a trocar sleeve into the anterior cruciate ligament after the arthroscopic procedure. Pulsatile flow within the ligament was observed in all patients. The mean maximum BCF value ranged from 101 to 274 mV; SD range was +/- 3-9 mV. The mean minimum BCF ranged from 75 to 197 mV; SD range was +/- 0 to 9 mV. Laser Doppler flowmetry offers significant promise as a method for measurement of in vivo anterior cruciate and cruciate substitution blood flow.
To evaluate pin/screw/plate fixation for management of femoral neck fractures, 39 proximal femora were tested in both torsion and flexion under physiological loading conditions. Three, four, or five implants of six commonly used multiple-fixation devices, and a sliding hip screw with and without an additional 6.5-mm cancellous screw were examined in paired femora. The intact and postfixation femora were initially subjected to a single applied moment, and the torsion and bending stiffness were determined from the load-deformation data. Postfixation femora were also subjected to cyclic loading in flexion at three load ranges, and fixation was judged successful if no failure occurred on or before 1,500 cycles of 667 to 2,000 N of a combined compressive force and moment. Anterior-posterior and lateral radiographs of each specimen were taken after fixation in order to evaluate Singh's index of bone density, fracture reduction, implant placement, and cross-sectional diameter of the femoral neck. Bone density was also evaluated by computed tomography (CT) and physical measurement of core samples obtained from the femoral head. The results indicate that there appears to be no justification for the use of more than three pin/screw implants for management of femoral neck fractures. Bone density was found to correlate with fracture stability and may be a useful predictor of fixation success.
Most theories concerning osteonecrosis of the femoral head have as their central focus ischemia of bone. This has been difficult to prove because of lack of a method for direct measurement of bone blood flow. The authors evaluated femoral head blood flow in five patients with established femoral head osteonecrosis using laser Doppler flowmetry. Blood flow within the "avascular" segment was lower than that of the normal cancellous bone of the intertrochanteric region. A surrounding zone of hyperemia was noted in four of the five patients. Laser Doppler flowmetry was easy to use and is a reproducible method for direct estimation of bone-blood flow.
This paper presents Laser Doppler Flowmetry (LDF) as a method for measuring cortical bone blood flow. The goal of this study was to evaluate the efficacy of LDF as a means to determine cortical bone perfusion as an indicator of persistent patency of microvascular anastomoses. Cortical bone blood flow was measured in an experiment using free vascularized immunosuppressed bone allografts. Disulfine blue demonstrated patency in all grafts at 20 weeks sacrifice date, with 15 percent localized areas of nonperfusion, corresponding to areas of microscopic evidence of devitalization. LDF suggested four out of six anastomoses to be nonpatent at four weeks, and irregular evidence of patency at 20 weeks, depending the site of measurement. The small volume of tissue sampled by the probe limits LDF's ability to assess patency of a vessel supplying a whole graft. Comparing LDF with disulfine blue technique, we conclude that the LDF-results in our experiment did not allow general statements regarding the patency of microvascular anastomoses to large segments of cortical bone.
A midshaft femoral fracture in a high-energy trauma victim should prompt the orthopedist to search carefully for an ipsilateral fracture of the femoral neck. This fracture will be present in 5 per cent of patients, and the incidence may be increasing. Management of the femoral neck fracture should include emergent capsulotomy, anatomic reduction, and rigid fixation with compression. Management of the femoral shaft should not interfere with these goals because of the risk of post-traumatic necrosis of the femoral head. Successful methods of management of the femoral shaft fracture have included compression plating, retrograde Kuntscher nailing, and interlocking nails. Approaches to the treatment of concomitant intertrochanteric and femoral shaft fractures should be selected according to the skill and experience of the surgeon and the availability of equipment.
Laser Doppler flowmetry (LDF) was used to measure bone blood flow in the rabbit femoral head and femoral condyles. To correlate the LDF output signal blood cell flux to in vivo blood flow, simultaneous measurements using LDF and 85Sr-labeled microspheres were made in an adult rabbit model. There was no correlation between the two methods for blood flow in the femoral condyles and the correlation between the two methods for blood flow in the femoral head does not achieve statistical significance. An LDF signal of 0.4 V was approximately equal to a microsphere measured flow rate of 0.4 ml blood/g bone/min. The strength of the correlation in the latter case may have been affected by (a) large arteriovenous shunts, (b) inadequate mixing of the microspheres with a left ventricular injection, and (c) insufficient numbers of microspheres present in the bone samples with which to satisfy the mathematical requirements of the microsphere method. When LDF was used to evaluate the effect of elevated intracapsular pressure on femoral head blood flow in skeletally mature rabbits, femoral head subchondral bone blood flow declined with increasing intracapsular pressure from a baseline value of 0.343 +/- 0.036 to a value of 0.127 +/- 0.27 at 120 cm of water pressure. The decline in femoral head blood flow was statistically significant at pressures of 40 cm of water or higher (p less than 0.001), and evaluation of sections of the proximal femora made from preterminal disulphine blue injections confirmed these findings. Intracapsular tamponade has an adverse effect on femoral head blood flow beginning well below central venous pressure and should be considered in the pathophysiology of posttraumatic and nontraumatic necrosis of the femoral head. Laser Doppler flowmetry was easy to use and appears to be a reproducible technique for evaluating femoral head blood flow, offering distinct advantages over the microsphere technique for measuring bone blood flow. Further studies of the in vivo calibration of the LDF method for bone blood flow are necessary for the method to have potential for clinical application.
The results of ten acute, displaced proximal femoral fractures in patients 14 years and under are reported. These high-risk fractures were managed with urgent open reduction and pin or screw fixation with supplemental spica casting. The exception to this protocol was in two Delbet's type IV (intertrochanteric) fractures which were managed by closed reduction and spica casting. There was a case of partial avascular necrosis of the femoral head in a type I transepiphyseal fracture. At a minimum followup of 2 years the patients were asymptomatic with no significant limitation of hip motion.
Percutaneous Neufeld pinning was performed for 32 femoral neck fractures in elderly medically debilitated patients (mean age, 75 years). The technical complications were minimal in the 25 impacted or nondisplaced fractures and in the seven displaced fractures. Although 23 of the 25 patients with impacted or nondisplaced fractures were ambulatory at a mean follow-up period of two years, none of the patients with displaced fractures achieved functional ambulation. Percutaneous Neufeld pinning may be considered for elderly, medically unstable patients with impacted or nondisplaced fractures, using no more than three pins. Some other internal fixation device, endoprosthetic arthroplasty, or another implant should be considered for displaced fractures.
One hundred twenty-five consecutive femoral neck fractures were treated with Deyerle fixation in the ten-year period from 1970 to 1980. The 123 patients in the series of 125 fractures had a mean age of 62.2 years. Sixty-nine percent of the fractures were displaced. Fewer than nine pins were used in only eight cases. In 102 cases, impaction was recorded and quantitated. Pin penetration was noted in 44 cases (35%), and infection in 14 cases (11%). Sixty-four percent of the patients were followed for at least two years; 31 (39%) developed aseptic necrosis and five (6.3%) had nonunited fractures. Owing to the risks of increased operating time, blood loss, and technical difficulties encountered in the authors' teaching hospital, the method was discontinued.
Slippage of the capital femoral epiphysis typically presents as hip pain in a child. Radiographic examination demonstrates translocation of the upper femoral epiphysis away from its normal anatomic position on the neck of the femur. Slipped capital femoral epiphysis can result in permanent deformity if it is not promptly corrected. Closed pinning is the treatment for acute slips, but treatment options are complex when the condition is chronic.
Femoral neck fractures in young adults have a poor prognosis because the incidence of non-union and aseptic necrosis is high. We reviewed the results in twenty-seven consecutive patients with a femoral neck fracture who were younger than fifty years and who were treated with a standard protocol at Harborview Medical Center from 1975 to 1981. There were twenty-two male and five female patients, and they ranged in age from twelve to forty-nine years (mean, 32.4 years). Twenty patients were involved in high-velocity trauma and twelve of them had significant injuries to other organ systems. One of the remaining seven patients had sustained the fracture while running, and in the other six the fracture was associated with a metabolic disorder. Eight patients had a Garden Stage-II fracture; twelve, Stage-III; and seven, Stage-IV. The fractures were fixed with multiple 6.5-millimeter cancellous screws after adequate closed reduction, which was usually performed within eight hours after injury. All of the fractures united and there were no wound infections. Aseptic necrosis of the femoral head developed in five patients (20 per cent), three of whom had symptoms at the time of writing and will require surgical revision of the hip.