Getting out of the corner.
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Biomedical subjects
Publications and source records attributed to D D Aronson.
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In scoliosis, the Cobb measure of curve severity has been recommended over the Ferguson method because it had greater magnitude and appeared more sensitive to changes during progression and after treatment. This study made comparisons between the Cobb and Ferguson measures in radiographs of patients with idiopathic scoliosis to test whether the methods were really different, and to compare their precision. In 138 observations of 77 untreated patients there was a very high correlation (R2 = 0.98) between Cobb and Ferguson angle, with Cobb angle averaging 1.35 times greater. For sequential measures (mean interval 10 months), the percent changes agreed closely (R2 = 0.5). The relationship between Cobb and Ferguson angles remained the same in measurements of 24 patients wearing a brace compared with the unbraced condition and in 18 patients measured before and after Harrington rod surgery. Repeated measurements were made by three observers with the apex and end vertebrae pre-marked and held constant. For Cobb angle, the greatest range of measurements on any film was 8 degrees (pooled SD = 1.3 degrees). For Ferguson angle the greatest range was also 8 degrees (pooled SD = 1.8 degrees). Ferguson angle was slightly more sensitive to incorrect selection of end vertebrae. It was concluded that both methods can be useful for measuring curve magnitude. Ferguson angle should be measured and then adjusted by multiplying it by 1.35 in situations where Cobb angle measurement is technically difficult or invalid. Ferguson angle is better suited to automated measurement.
To test the traditional classification system of slipped capital femoral epiphysis, we evaluated the presenting symptoms and radiographs of fifty-four patients and reclassified the slipped epiphyses as unstable or stable, rather than acute, chronic, or acute-on-chronic. Slips were considered to be unstable when the patient had such severe pain that weight-bearing was not possible even with crutches. Slips were considered to be stable when the patient could bear weight, with or without crutches. We reviewed the records on fifty-five hips in which the slip would have been classified as acute because the duration of symptoms was less than three weeks; thirty of these were unstable and twenty-five were stable. All slips were treated with internal fixation. A reduction occurred in twenty-six of the unstable hips and in two of the stable hips. Fourteen (47 per cent) of the thirty unstable hips and twenty-four (96 per cent) of the twenty-five stable hips had a satisfactory result. Avascular necrosis developed in fourteen (47 per cent) of the unstable hips and in none of the stable hips. We were not able to demonstrate an association between early reduction and the development of avascular necrosis.
The records of 224 children who had a slipped capital femoral epiphysis and who had no underlying metabolic or endocrine disorder were studied retrospectively to investigate the epidemiology of bilateral slipped capital femoral epiphysis. Eighty-two (37 per cent) of the 224 children (fifty-one boys and thirty-one girls) had a bilateral slip. Sixty-four of these children were black and eighteen were white. The age at the time of the diagnosis of the first slip was 13 +/- 1.7 years (mean and standard deviation), the duration of the symptoms was 5 +/- 5.0 months, and the angle of the slip was 26 +/- 16 degrees. Obese children were younger at the time of the diagnosis of the first slip (12 +/- 1.6 compared with 13 +/- 1.6 years for the children who were not obese, p = 0.001). The diagnosis of a slipped capital femoral epiphysis was made simultaneously in both hips in forty-one children and sequentially in forty-one children. Compared with the children in whom both hips were diagnosed simultaneously, the children in whom the hips were diagnosed sequentially had had a shorter duration of the symptoms before the diagnosis of the first slip (3 +/- 2.4 compared with 7 +/- 5.9 months, p = 0.0003), were younger at the time of the diagnosis of the first slip (12 +/- 1.9 compared with 13 +/- 1.2 years, p = 0.001), and tended to be more obese (p = 0.025). In 88 per cent of the patients who had sequential slips, the second slip was diagnosed within eighteen months after the diagnosis of the first slip.(ABSTRACT TRUNCATED AT 250 WORDS)
The adductor longus tendon was tagged with metallic markers after posterior adductor transfer in 17 children (33 hips) with cerebral palsy: 10 had spastic diplegia and seven had spastic quadriplegia. The average age at operation was 5 years 3 months, time of postoperative immobilization 5.7 weeks and average follow-up 1 year 7 months. In 19 hips the tendon remained attached to the ischium, in 11 hips it pulled away from the ischium and in three hips the result was equivocal. The incidence of detachment was higher among diplegic children than quadriplegic children.
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The traditional method of treating slipped capital femoral epiphysis by in situ pinning is being challenged. The complication of chondrolysis has been correlated with unrecognized pin penetration into the hip joint. Several studies have shown that black children may be more susceptible to developing chondrolysis. Fifty-five children (89% black) with 80 slipped epiphyses agreed to return for evaluation by the authors at an average of 3.3 years after in situ pinning. The results were classified according to clinical and roentgenographic parameters. The results were excellent or good in 56 (70%) of the 80 slips. Excellent or good results were found in 86% of mild slips, 55% of moderate, and 27% of severe. The complication of chondrolysis developed in three slips (4%) and avascular necrosis in two (3%). Poor pin position could be correlated with the complication in one of the three patients who developed chondrolysis and in both who developed avascular necrosis. Poor pin position was also associated with 12 (60%) of the 20 poor results. The majority of pin problems were secondary to technical problems associated with attempting in situ pinning from the lateral approach. In this study, black children were not more susceptible to chondrolysis than nonblack children.
Forty-four children (fifty-eight hips) who had a slipped capital femoral epiphysis were managed by in situ pinning with a single cannulated screw. This method of treatment was first used in our institution in 1983. Thirty-one boys and thirteen girls were followed for an average of three years (range, two to six years). There were eight acute slips and fifty chronic slips. Thirty-four patients were black and ten patients were white. The clinical criteria of Heyman and Herndon and the radiographic parameters cited by Boyer et al. were used to grade the results. Fifty-four hips were rated as either excellent or good. Avascular necrosis developed in one patient who had an acute slipped capital femoral epiphysis, but chondrolysis did not occur in any patient. The complications included a subtrochanteric fracture in one patient and an increase in the degree of slippage of the capital femoral epiphysis in two patients.
We reviewed 74 black children with 97 slipped capital femoral epiphyses (SCFEs) with an average follow-up of 3.7 years. There were 24 bilateral, 22 right, and 27 left SCFEs. The average age at operation was 12 years 6 months. The average slip severity was 28 degrees with 61 mild, 21 moderate, and 14 severe slips. Group I slips (54) were treated with multiple pins, and group II slips (43) were treated with a single central screw. Satisfactory results were achieved in 74% of the group I and 91% of the group II slips, with only three cases of chondrolysis. We conclude that single central screw fixation of SCFE in black children can lead to excellent results with a low incidence of chondrolysis.
Extra-articular subtalar arthrodesis with cancellous bone graft and internal fixation was performed on 20 feet of 12 children with myelomeningocele, whose average age at operation was 7.4 years. Indication for surgery was progressive hindfoot valgus deformity causing difficulty in fitting orthoses. At average follow-up of 4.1 years, results were satisfactory in 18 of the 20 feet. Unsatisfactory results were a result of undercorrection at time of surgery. Extra-articular subtalar arthrodesis will correct hindfoot valgus deformity in children with myelomeningocele, and the use of internal fixation and iliac crest bone grafting contributed to the improved success rate in this series.
Seventy-eight posterior transfers of the adductors of the hip in forty-two children who has spastic cerebral palsy were reviewed an average of 5.7 years after the operation (range, two to 14.6 years). The results were assessed on the basis of the patient's ability to walk, the range of motion of the affected hip or hips, and the radiographic measurements. In 88 per cent of the patients, the transfer was successful in improving or maintaining abduction, extension, functional walking, and stability of the hip. The failures were all in patients who were unable to walk and who had spastic quadriplegia. Tenotomy of the iliopsoas tendon at the time of the transfer procedure resulted in an improved range of motion of the hip.
Stability of the cervical spine was studied in two groups of children who had myelomeningocele. Group I consisted of twenty children who had an Arnold-Chiari Type-II malformation in whom a suboccipital craniectomy (partial occipital craniectomy through the suboccipital route) and cervical laminectomy was done to decompress the brain stem. The average duration of follow-up in this group (excluding one patient) was 4.7 years (range, 2.3 to 10.4 years) after the operation. Group II consisted of twenty children who had myelomeningocele but had not had an operation for decompression. Lateral radiographs of the cervical spine in flexion and extension showed no instability between the occiput and atlas or between the atlas and axis in either group. In contrast, translation between the second and third cervical vertebrae averaged four millimeters in Group I and one millimeter in Group II (p less than 0.01), and angulation between the third and fourth cervical vertebrae averaged 17 degrees in Group I and 6 degrees in Group II (p less than 0.01). Nineteen of the twenty patients in whom a suboccipital craniectomy and cervical laminectomy (Group I) had been done had instability of the cervical spine.
The effectiveness of allograft bone for posterior spinal fusion in neuromuscular scoliosis is controversial. Thirty patients with cerebral palsy, treated with posterior spinal fusion, were divided into two groups. Group 1 consisted of 18 patients treated by posterior spinal fusion using autogenous bone graft. Group 2 consisted of 12 patients treated by posterior spinal fusion using freeze-dried allograft bone. The average preoperative curve of 70 degrees in Group 1 was corrected to 35 degrees (50% correction). At 3.2 years average follow-up, the curves averaged 51 degrees (46% loss of correction). The average preoperative curve of 80 degrees in Group 2 was corrected to 39 degrees (51% correction). At 3.5 years average follow-up, the curves averaged 54 degrees (38% loss of correction). Anesthesia time decreased from 344 to 281 minutes (p less than 0.05), and intraoperative blood loss decreased from 2730 to 1740 ml (p less than 0.025) when allograft bone was used as a substitute for autograft bone. Freeze-dried allograft bone is a readily available, safe, and effective substitute for autogenous bone graft in patients with cerebral palsy undergoing posterior spinal fusion.
To correlate the season of the year with the prevalence of slipped capital femoral epiphysis, we reviewed the cases of 177 patients who had 243 slips during an eleven-year period. We assessed the month when the patient was seen and the implied time of onset of the slip and found a statistically significant variation for both. The average time of onset was mid-June, with a standard deviation of 2.5 months, and was not significantly different for race, sex, or laterality. We attributed the increased incidence of slipped capital femoral epiphysis during the summer to increased physical activity in that season.
Posterior transfer of the tendon of the anterior tibial muscle through the interosseous membrane to the calcaneus to prevent or correct a calcaneus deformity was performed in twenty patients (thirty-nine feet) who had a myelomeningocele. The average age of the patients at the time of the operation was 4.6 years, and they were followed for an average of six years. Satisfactory clinical and radiographic results were obtained in thirty-seven (95 per cent) of the thirty-nine feet. Two patients, one who was unable to walk and one who walked at home only, had a mild equinus deformity of the left foot. No patient had a clinical calcaneus deformity, but there was radiographic evidence of talipes calcaneus in one patient (two feet). The anterior tibial muscle functioned more consistently when the operation was performed after the patient was four years old and in patients who had a fifth lumbar or first sacral motor level.
The etiology of valgus deformity after a seemingly innocuous fracture of the proximal tibial metaphysis in children is unknown. The purpose of this work was to identify the etiology of this deformity using a rabbit model. Twenty-two eight-week-old rabbits were divided into two groups. In Group I, the medial periosteum was excised from the left proximal tibial metaphysis. A partial osteotomy was created 5 mm distal to the epiphyseal plate, involving the medial one-half of the tibial metaphysis. Two 0.7-mm Kirschner wires were placed as markers on each side of the osteotomy. In Group II, the identical procedure was performed from the lateral side. Standard roentgenograms were obtained postoperatively and weekly until death by sodium pentobarbital overdose at six weeks. The angular deformity, medial growth, and lateral growth were calculated from the markers on the roentgenograms. All tibias were decalcified and analyzed under light microscopy. In Group I, all 11 rabbits developed valgus deformity averaging 12.2 degrees; asymmetric growth was statistically significant. In Group II, ten of 11 rabbits developed varus deformity averaging 9.8 degrees; asymmetric growth was not statistically significant. Despite obvious asymmetric growth in both groups, light microscopy failed to reveal any asymmetry of the physis. Valgus and varus deformities are secondary to asymmetric growth, which is not demonstrable by light microscopy.
Thirty-seven (20 per cent) of 186 children who had myelomeningocele whose records were reviewed had sustained a total of seventy-six fractures. The frequency with which the fractures occurred was related directly to the level of neurological involvement. Thirteen (41 per cent) of the patients who had involvement at the thoracic level, fifteen (36 per cent) who had involvement at the upper lumbar level, eight (10 per cent) who had involvement at the lower lumbar level, and one (3 per cent) who had involvement at the sacral level sustained fractures. Sixty-five (86 per cent) of the fractures occurred before the child was nine years old, fifty-eight (76 per cent) were judged to be secondary to the limb being in a cast, and seventy-four (97 per cent) involved the lower extremity. Eleven patients, all of whom had thoracic or upper lumbar involvement, sustained fractures of multiple extremities. All fractures of the lower extremity were distal to the level of neurological involvement; they occurred predominantly in the femur in patients who had thoracic involvement and in the tibia in patients who had lumbar involvement. All of the metaphyseal and diaphyseal fractures healed satisfactorily, whether they were treated by immobilization in a plaster cast or in a bulky Webril dressing, although there were fewer complications in the latter group. The seven fractures that involved the physeal plate were a major problem, as three (43 per cent) had delayed union and two (29 per cent) developed premature growth arrest.