Biomedical subjects
Publications and source records attributed to J K Mayfield.
The key wrist ligaments are volar and intracapsular. The pathogenesis of carpal instability is dependent on the loading mechanism, hand position, and ligament and bone biomechanics. Ligament elongation with associated intercarpal and carpal instability can be present.
The spines of forty patients with myelomeningocele and paralytic scoliosis were surgically stabilized at the Twin Cities Scoliosis Center between 1960 and 1979. Treatment with posterior spine fusion and Harrington instrumentation extending to the sacrum, combined with anterior fusion using either Dwyer or Zielke instrumentation, gave the best results, correcting scoliosis by an average of 45 degrees (comparing preoperative values with those at the last visit), lordosis by an average of 20 degrees, torso decompensation by an average of 5.7 centimeters, and pelvic obliquity by an average of 7 degrees. This combined fusion method reduced the rate of pseudarthrosis to 23 per cent (compared with 46 per cent when only posterior fusion and instrumentation were used). Prophylactic antibodies (selected on the basis of preoperative cultures of urine) reduced the infection rate to 8 per cent. Posterior fusion or anterior fusion alone was inadequate, even with instrumentation. Early mobilization wearing a bivalved polypropylene body jacket minimized osteoporosis, pressure sores, and social isolation. Unsolved technical problems remain, however, especially in relation to obtaining fusion across the lumbosacral joint.
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The cases of forty children who had incurred a spinal cord injury between birth and the age of eighteen years were reviewed at two to 26.8 years (mean, ten years) after injury. In all of the twenty-five patients who were injured prior to the adolescent growth spurt paralytic spinal deformity developed; in twenty-four (96 per cent) of them it was progressive. Scoliosis developed in twenty-three (92 per cent); kyphosis, in sixteen (64 per cent); and excessive lumbar lordosis, in five (20 per cent). Management of the spinal deformities by bracing was difficult, and seventeen patients (68 per cent) required spine fusion, usually to the sacrum. Complications were frequent. All of the fifteen patients who were injured after the onset of the adolescent growth spurt had sustained a spinal fracture or fracture-dislocation. Nine (60 per cent) had an acute angular thoracic or thoracolumbar fracture kyphosis and seven (47 per cent) had progressive fracture kyphosis. A history of a thoracic and thoracolumbar laminectomy always was associated with increased kyphosis progression. Six (40 per cent) of these patients required spinal stabilization, usually for unstable injuries and progressive post-laminectomy deformity. Progressive paralytic spinal deformity was uncommon in the postadolescent patient.
Of seventy-four children who were treated at a mean age of seventeen months for neuroblastoma and survived more than five years, fifty-six (76 per cent) had spinal deformity due either to the disease or to the treatment after a mean follow-up of 12.9 years. Of these fifty-six, 50 per cent had post-radiation scoliosis (mean, 18 degrees; range, 5 to 79 degrees), and 16 per cent had post-radiation kyphosis, most frequently at the thoracolumbar junction (mean, 39 degrees; range, 13 to 61 degrees), at the time of follow-up. Two kyphotic thoracolumbar curve patterns were identified: (1) an angular kyphosis with a short radius of curvature and its apex at the twelfth thoracic and first lumbar vertebrae, and (2) a thoracic kyphosis with a long radius of curvature that extended into the lumbar spine. The post-radiation deformity--both the scoliosis and the kyphosis--progressed with growth, the scoliosis at a rate of 1 degree per year and the kyphosis at a rate of 3 degrees per year. Epidural spread of the neuroblastoma was associated with most of the cases of severe scoliosis and kyphosis. The deformity was due either to the laminectomy or to the paraplegia acting in conjunction with the radiation. Eighteen per cent of 419 children with this malignant disease survived more than five years, and of the survivors, 20 per cent had spinal deformity severe enough to warrant treatment. The factors associated with the development of spinal deformity in patient treated for neuroblastoma were: (1) orthovoltage radiation exceeding 3000 rads, (2) asymmetrical radiation of the spine, (3) thoracolumbar kyphosis, and (4) epidural spread of the tumor.
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The pathomechanics, ligamentous damage, and degree of carpal instability in perilunate and lunate dislocations were analyzed by experimentally loading 32 cadaver wrists to failure. Thirteen perilunate and two lunate dislocations were produced. The mechanism of injury was extension, ulnar deviation, and intercarpal supination. These dislocations occurred in a sequential fashion due to progressive and specific ligamentous disruptions and were classified according to the degree of perilunar instability (PLI). Stage I perilunar instability (scapholunate diastasis) had the least degree of carpal instability. Lunate dislocations (stage IV PLI) had the highest degree of carpal instability. Radial styloid fractures were produced in seven as a result of avulsion. Scaphoid rotation was created in eight and was due to rupture of the radioscaphoid and scapholunate ligaments. Reduction was accomplished by reversing the mechanism of injury--that is, intercarpal pronation, radial deviation, and palmar flexion. Stress roentgenograms employing longitudinal carpal compression in radial and ulnar deviation were helpful in determining the degree of associated carpal instability.
The mechanism responsible for carpal injuries has been elusive. Direct results of the inability to identify the mechanism include a confusing system of classification and a lack of a rational plan of treatment for the many fractures and fracture-dislocations that occur about the carpus. The mechanism of injury determined experimentally was 3-dimensional, including extension, ulnar deviation, and intercarpal supination. The resultant spatial vector in conjunction with the magnitude and duration of loading determined the combination of injuries produced. Carpal dislocations resulted from a force vector that emphasized ulnar deviation and intercarpal supination. Scaphoid fractures were produced by a vector that emphasized extension and were fractured by the dorsal rim of the radius. The degrees of carpal instability produced experimentally were divided into four stages, depending upon the amount of ligamentous damage and joint instability. Stage I (scapholunate instability) was the most stable and Stage IV (lunate dislocation) was least stable. Scaphoid fractures started on the palmar surface and propagated dorsally. Type I fractures had an intact dorsal soft-tissue hinge and fracture stability could be created by flexion. Types II and III scaphoid fractures were associated with significant perilunar instability (PLI) and were classified as fracture-dislocations.
Twenty-seven patients with Type-II congenital kyphosis (failure of anterior vertebral segmentation) all had progression of the kyphosis which varied in magnitude. The average rate of progression was 5 degrees per year. Pain due to compensatory lumbar hyperlordosis (eight patients) and objectionable deformity (fifteen patients) were the most frequent complaints. Unlike patients with Type-I kyphosis (failure of vertebral formation), paraplegia did not occur and associated congenital anomalies were infrequent (three of the twenty-seven patients). Spontaneous ossification of the anterior part of seemingly normal intervertebral discs leading to bar formation and progression of deformity occurred in five patients. A Milwaukee brace had little effect on this fixed kyphotic deformity in the six patients in whom the brace was used. Early recognition and spine fusion are the recommended treatment. Posterior fusion is sufficient in young children with progressive deformity, whereas combined two-stage anterior and posterior fusion with osteotomy of the anterior bar is recommended in children with severe deformity.
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The ligamentous anatomy of the wrist was analyzed by studying (1) 28 dissected human wrists, (2) and by examination of 19 wrist injuries created mechanically. Six volar intracapsular ligaments are described, two stabilizing the distal carpal row, three stabilizing the proximal carpal row and one stabilizing the proximal scaphoid pole. More specific terminology for these ligaments is proposed. An explanation of how these ligaments participate in the mechanical functioning of the carpus is advanced. Mechanically created wrist injuries had ruptures of specific ligaments as described augmenting a need for a more specific terminology. Suspected mechanisms of injury in perilunate and lunate dislocations are mentioned based upon the functional understanding of the intracapsular ligaments.
The results of a prospective study of the surgical treatment of paralytic scoliosis and congenital lumbar kyphosis in 19 children with myelodysplasia and one child with sacral agenesis indicate that improved results can be achieved with the use of staged anterior and posterior fusions, more rigid spinal instrumentation, and bank and autogenous bone graft. No wound infections occurred as a result of preoperative treatment of urinary infection and with the use of prophylactic antibiotics. Improved posterior spinal fixation was accomplished with a double square end sacral hook in paralytic scoliosis and pelvic obliquity and with a cable-hook compression system in congenital lumbar kyphosis. Posterior lumbopelvic fusion with cable-hook compression instrumentation gave acceptable results in lumbopelvic kyphosis from complete sacral agenesis.
The concept of a spectrum of progressive ligamentous injury of the wrist, supported by anatomical and biomechanical data, indicates that a pattern of ligamentous injury begins on the radial side of the wrist. The mechanism of carpal injury associated with this ligamentous damage is a three-dimensional or spatial mechanism including extension, ulnar deviation, and intercarpal supination. Perilunar instability (PLI) begins at the scapholunate joint (Stage I PLI) and may be associated with partial interosseous ligament tears, interosseous ligament elongation, or complete disruption. Radiocapitate ligament failure leads to Stage II (PLI) with opening of the space of Poirier. This proceeds to Stage III (PLI) with radiotriquetral ligament failure. Stage IV (PLI) exhibits dorsal radiocarpal ligament disruption.