Is a routine radiological consultation cost-effective for pediatric orthopedic radiographs?

This investigation was undertaken to determine the value of a routine radiological consultation on all examinations taken during the course of evaluation and treatment of children with elective orthopedic problems. Shriners Hospital in Los Angeles treats children with chronic orthopedic problems. All radiographs are ordered by an orthopedic surgeon. Currently all plain examinations are also read and reported by a pediatric radiologist. The study was a retrospective chart review. Three hundred nineteen radiographic examinations (6.7% of the total performed in calendar year 1995) were reviewed. The orthopedic surgeons documented the results of their readings in 69% of the cases, while the radiology staff documented 92% of the studies. The data do not show evidence of significant misinterpretations in the readings by the orthopedic surgeons. Therefore routine radiological consultation for all examinations is unnecessary in that specific setting. If a policy change were instituted, it would represent a major saving in health-care costs.

Limb xenotransplantation using FK506 and RS61443 immunosuppression.

A new model of limb xenotransplantation has been developed to determine whether the newer immunosuppressive agents, FK-506 and RS-61443, either alone or in combination, can delay the rejection of a composite limb xenograft from donor Golden Syrian hamsters to recipient Lewis rats. Using a short-term course of immunosuppression for 14 days post-transplant, both FK-506 2 mg/kg/day and RS-61443 30 mg/kg/day were able to delay rejection. FK-506-treated animals had a mean rejection time of 10.2 days and RS-61443-treated animals had a mean rejection time of 10 days, compared with a mean rejection time of 6.4 days in non-immunosuppressed controls. Combination and sequential immunosuppression with both FK-506 and RS-61443 did not produce any improvement, compared with single-agent immunosuppression, and were quite toxic. Histologically, FK-506 seemed to prevent signs of rejection in the skin and muscle components of the limb xenograft better than RS-61443.

Stride analysis after proximal tibial replacement.

Ten patients who had undergone primary intraarticular proximal tibial replacement between April 1985 and December 1994, and had a minimum of 2 years of followup, were available for stride analysis. Mean age, time since intraarticular proximal tibial replacement, height, and weight were 23.8 years, 6.5 years, 167 cm, and 63 kg, respectively. A volunteer control group of five male patients who had undergone above knee amputation was obtained from the local community. The mean age, time since above knee amputation, height, and weight were 43.6 years, 24.1 years, 165 cm, and 70 kg, respectively. Stride analysis was performed over the central 6-m portion of a 10-m walkway at a self selected, comfortable pace. Gait velocity, stride length, cadence, and stance time symmetry were measured. Velocity after intraarticular proximal tibial replacement versus above knee amputation was 79.2 +/- 7.6 m per minute versus 71.4 +/- 5.4 m per minute. Cadence after intraarticular proximal tibial replacement versus above knee amputation was 112.4 +/- 10.6 steps per minute versus 110.1 +/- 2.4 steps per minute. There were no significant differences between stride length (1.41 +/- 0.13 m versus 1.43 +/- 0.12 m) and stance time symmetry (0.90 +/- 0.07 versus 0.87 +/- 0.11) for intraarticular proximal tibial replacement versus above knee amputation. The results suggest that endoprosthetic reconstruction resulted in a gait comparable with that after above knee amputation with an external prosthesis.

Nerve xenograft transplantation. Immunosuppression with FK-506 and RS-61443.

An experimental model has been developed to study the potential transplantation of nerve xenografts using the newer immunosuppressive agents RS-61443 and FK-506. Sciatic nerve grafts of 2 cm were transplanted from donor Golden Syrian hamsters into a 0.5 cm gap in the sciatic nerve of recipient Lewis rats. Walking track analysis, somatosensory evoked potentials and histology demonstrated improved regeneration across the nerve xenografts that had been immunosuppressed with RS-61443 and FK-506 compared with non-immunosuppressed controls, but the function never approached that seen in control isografts. Regeneration across nerve xenografts immunosuppressed with FK-506 was better than xenografts immunosuppressed with RS-61443.

Perioperative aspects of hip fracture. Guidelines for intervention that will impact prevalence and outcome.

The cost of treating osteoporosis-related diagnoses, over one half of which are hip fractures, is $5.2 billion per year. The incidence of hip fractures is rising, and it is the orthopedic surgeon who provides the definitive medical care to these patients. Factors associated with poor outcome in hip fractures include poor nutrition, impaired mental ability and mobility, age, male sex, and inadequate fluid resuscitation and medical stabilization prior to surgery. The energy requirements for fracturing the hip are low. Potential prophylactic interventions include fall prevention, hip protector devices, estrogen replacement therapy, and calcium and vitamin D supplementation.

Computer graphic analysis of endosteal expansion after total hip arthroplasty.

Femoral endosteal expansion is known to occur naturally with aging and may contribute to femoral component loosening after cemented total hip arthroplasty (THA). Previous roentgenographic models used to quantify femoral expansion have used a limited number of measurements at arbitrary axial sites in one roentgenographic view. A computer graphic model is introduced, which uses standard anteroposterior (AP) and lateral roentgenograms to reconstruct a three-dimensional model of the femur between the lesser trochanter and the distal end of a cemented prosthesis. The model was used retrospectively to calculate endosteal and periosteal surface area and volume at the time of surgery and at follow-up examination for 22 patients who had been treated with hip arthroplasty (average, 9.3-year follow-up observation). Endosteal surface area and volume were found to increase an average of 3.1 cm2 and 1.7 cm3, respectively. Periosteal dimensions did not change significantly. Overall endosteal expansion occurs in the vicinity of the implanted prosthesis. The extremely low interobserver variability indicates that this model provides a reliable method of following surface area and volume changes around a cemented hip prosthesis.

Biomechanical comparisons of unidirectional and bidirectional Kirschner-wire insertion.

Peak axial loads on entry and peak pull-out loads were measured for Kirschner-wires (K-wire) inserted into canine metacarpals. The wires were placed using a standard, unidirectional drill and using an oscillating, bidirectional drill that reversed spin direction every 120 degrees. Seven trocar-tip wires were compared with seven diamond-tip wires using each drilling method. The trocar-tip wires demonstrated equal peak axial loads on entry when drilled at comparable speeds unidirectionally and bidirectionally. Pull-out load of the trocar tip after bidirectional insertion was less than that for unidirectional insertion but was still in the clinically useful range. The diamond-tip wire exhibited higher peak axial load on entry and lower peak pull-out load when drilled bidirectionally. Bidirectional insertion of a trocar-tip K-wire offers fixation characteristics comparable with those with unidirectional insertion and will potentially reduce the risk of soft-tissue damage associated with winding-up and avulsion of vital structures on the spinning shaft of a unidirectional driver.

Repriming and reversal of the isometric unexplained enthalpy in frog skeletal muscle.

1. heat production and high-energy phosphate hydrolysis by frog sartorius muscles in 6 s isometric tetani were measured to test the hypothesis that the isometric unexplained enthalpy (u.e.) and labile maintenance heat (l.m.h.) were of similar origin. Muscles were first given a conditioning tetanus to deplete the u.e. and l.m.h. A second (test) 6 s tetanus was given 6-300 s later to ascertain the extent to which l.m.h. and u.e. had recovered (reprimed). 2. The labile maintenance heat repriming was biphasic: 42% of the conditioning l.m.h. reprimed with a time constant of 10 s, the remainder with a time constant of 500 s. 3. The u.e. produced in the test tetanus 6 s after the conditioning tetanus was reduced to 18% of its conditioning value. By 30 s, u.e. had returned to conditioning values even though the amount of high-energy phosphate splitting was 17% less than that in the conditioning tetanus. 4. This observation is supported by measurements revealing that during the 30 s following a 6 s tetanus an amount of enthalpy was absorbed (less heat produced than expected from the measured metabolic changes) whose absolute value (after correction for oxygen consumption) was not different from the amount of unexplained enthalpy liberated during the tetanus. 5. The difference in repriming time course shows that l.m.h. and u.e. are not produced by the same reactions. The data are consistent with the hypothesis that calcium binding to troponin and parvalbumin produce u.e. while calcium binding to troponin and a non-linear time course of ATP hydrolysis produce l.m.h.