The role of the ankle plantar flexors in normal walking.
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Biomedical subjects
Publications and source records attributed to D H Sutherland.
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Electromyography is the most frequently used laboratory method of assessing gait of patients with cerebral palsy. This method has shown that slow stretch testing is non-specific and that electromyograms obtained during walking are of greater value in planning treatment. If surgical treatment is necessary, only those muscles with phase reversal should be considered for transfer; lengthening is appropriate for those with phase prolongation. The addition of movement measurements and force-plate recording increases the amount of information available for analysis. Distinctions can then be attempted between primary abnormalities and compensatory mechanisms, and gait patterns with common demominators can be identified. Only by precise pre- and post-operative studies can treatment for locomotor problems be reliably assessed. Progress in the treatment of patients with cerebral palsy cannot be achieved without such objective assessment.
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We performed double innominate osteotomy in twenty-five patients with acetabular insufficiency resulting from congenital dislocation of the hip and other lesions. Following iliac (Salter) osteotomy, the second osteotomy was carried out medial to the obturator foramen in the interval between the symphysis pubis and the pubic tubercle. In children more than six years old, adolescents, and adults, addition of the pubic osteotomy increased the amount of acetabular rotation and coverage of the femoral head that could be achieved. An additional benefit was that the femoral head could be shifted medially, decreasing the length of the femoral lever arm. The improvement in center-edge angle in the twenty-five patients averaged 27 degrees, and the acetabular index decreased an average of 19.5 degrees. The center of the head shifted medially an average of 1.5 centimeters. Hip stability was achieved in twenty-three of the patients.
A case of occult pelvic osteomyelitis is presented. The involved portions of the left pubis and left ischium presented as "cold" areas on the original bone scan with 99mTc-diphosphonate. The presumed mechanism for this unusual finding in osteomyelitis is compression of the microcirculation to bone by subperiosteal and intraosseous pus.
Two theories concerning the effects of surgical release of the proximal origins of the rectus femoris in spastic patients are (1) that release reduces hip flexion contracture and lumbar lordosis and diminishes crouch, and (2) that release primarily enhances early swing-phase knee flexion. A series of eight patients with pre-operative electromyography and pre- and post-operative dynamic knee measurements are reviewed. In these patients, back-knee thrust did not improve because it was not caused by rectus contracture. The effect upon hip was also variable: two patients had increased hip flexion and a third had diminished hip flexion after release. In six of the eight patients knee flexion was improved in early swing phase. Improvement from surgery can be expected when rectus spasticity is sufficient (1) to interfere with the initiation of swing phase, and (2) to decrease the amplitude of knee flexion. Little change occurred in the patients who did not have these functional deficits. A review of the cases supports the primary knee effect theory of Silfvenskiöld; however, insufficient information was obtained from this series to rule out hip and pelvic changes.
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One of the problems facing the clinician is the differentiation between functional and structural limb-length inequality. This study investigated 20 subjects (mean age, 9.0 +/- 3.9 years) with documented limb-length inequalities to determine the magnitude of discrepancies that result in gait abnormalities. The subjects were asked to walk on an 8-m walkway at a self-selected free pace. The contact time, first and second force peaks, and loading and unloading rates of the vertical ground-reaction force were measured for both limbs. These parameters were predictive for quantification of gait asymmetry. The asymmetry of these parameters increased as the limb-length inequality increased. In general, a limb-length inequality > 2.0 cm (3.7%) resulted in gait asymmetry that was greater than that observed in the normal population. However, the amount of asymmetry varied for each individual. A static examination can document an anatomic deformity, but this deformity may be compensated for by functional adaptations. An analysis of the patient's gait should be performed to identify asymmetries during ambulation. Dynamic gait findings, such as demonstrated in this study, are needed to support static measurements.
A cartilage-viewing technique was developed to overcome the shortcoming of not seeing the cartilaginous components, believed to play more important role than the osseous components in children's hips, with computed tomography. This technique was applied to 25 dysplastic hips in children younger than 10 years to evaluate their global and local deficiencies. The findings helped us to understand more about their individual problems. To quantify the three-dimensional (3-D) parameters of acetabular anatomy and femoral head coverage, a measuring technique was developed based on digitization of the 3-D coordinates and fitting of every component of the hip. The improved images and the quantified parameters were expected to aid the planning, formulation, and even simulation of individualized surgical treatment for children with developmental dysplasia of the hip.
Seventeen patients with cerebral palsy (29 hips) underwent psoas recession at the pelvic brim. The operative technique was a direct anterior approach, lateral to the femoral sheath. There were no infections or nerve or arterial injuries. After surgery, clinical examination revealed that fixed hip-flexion contractures decreased significantly in all patients. All of the subjects retained the ability to flex the hip against gravity and against manual resistance. All of the subjects underwent pre- and postoperative gait analysis. Stance-phase dynamic minimum hip flexion decreased significantly. Dynamic pelvic tilt improved to a statistically significant level for the younger children but did not for the group as a whole. There was less improvement with increasing age. Step length was significantly increased and cadence significantly decreased in all patients. We conclude that psoas recession at the pelvic brim, by using the anterior approach, lateral to the femoral sheath, is a safe, reliable, and effective procedure for children with cerebral palsy who have excessive anterior pelvic tilt and excessive dynamic hip flexion or hip-flexion contracture.
Kinematic gait analysis was carried out on 42 hips, including normal joints and joints affected with Legg-Calvé-Perthes disease. Data were analyzed by a computer algorithm that calculated three-dimensional femoral head contact with the acetabulum (containment). Patients were studied in and out of various abduction orthoses. The three-dimensional containment of the hip is reproducibly altered by various devices; specifically, the Atlanta brace increases posterior coverage and slightly increases lateral coverage, and Petrie casts improve lateral and anterior coverage at the expense of posterior containment. This analysis allows modeling of osteotomies and enhances clinical assessment of actual changes in containment with bracing.
A technique of intraarticular hip arthrodesis using a cancellous screw to provide compression across the joint is introduced. We present four patients in whom this method was successful, resulting in solid fusion and pain relief at follow-up.
In this study, 21 patients who had undergone double innominate osteotomy for congenital hip dysplasia (CDH) were studied to determine if significant improvements in clinical and radiographic indexes were present at follow-up. Quantitative data reflecting functional status, pain level, and range of motion were obtained and analyzed statistically, as were standardized measurements from preoperative and postoperative radiographs. Statistically significant improvements at follow-up were observed in pain level, functional status, acetabular index, center-edge angle, and relative lateral displacement. Significant correlations were found between the postoperative functional score and several clinical indexes, but none were found between radiographic indexes and the final functional score.
We retrospectively studied 62 nonambulatory children with spastic quadriplegic cerebral palsy who underwent proximal hamstring lengthening to improve hip and spine positioning. Preoperatively, all had hamstring contracture, with difficulty sitting due to hip extensor thrust and increased kyphosis. Thirty-five patients with follow-up greater than or equal to 2 years were studied using a modified Reimer scale to assess sitting ability. Sitting ability improved significantly (p less than 0.01) postoperatively, along with popliteal angle (p less than 0.001) and straight leg raising (p less than 0.001). Proximal hamstring lengthening is effective in treating severe hamstring contractures in the wheelchair-bound child with cerebral palsy.
The confusion test examines ankle dorsiflexion in patients with cerebral palsy. Orthopedists have related this test to swing-phase activity of the tibialis anterior, and have used it as a prerequisite for tendon transfer. To determine the validity of this assumption, ankle dorsiflexion was tested in 47 normal children. Forty-seven percent had a positive, unresisted confusion test, and 97% had a positive, resisted confusion test. Twenty-three patients with cerebral palsy who had a positive confusion test underwent gait analysis. Tibialis anterior electromyographs showed wide variability. Sagittal-plane ankle-movement curves revealed five patterns. Thirty-three percent of the patients showed abnormal swing-phase dorsiflexion, and 61% had abnormal swing-phase plantar-flexion. We conclude that the confusion test evaluates a normal, patterned response, and is positive in most children with cerebral palsy. Although a positive confusion test shows that active ankle dorsiflexion is possible, it is not predictive of swing-phase ankle kinematics.
Hip measurements using three-dimensional (3-D) images and computed tomography (CT) scans were evaluated. The 3-D measurements proved more accurate than CT measurements of femoral and acetabular anteversion. Additionally, accurate 3-D measurements (> 99%) of the femoral neck-shaft angle were provided. Acetabular anteversion determinations by CT scans were systematically decreased as pelvic flexion increased, whereas accuracy was > 96% with 3-D images. The 3-D software allows image rotation in all three reference planes, which minimizes positional errors. A case study is provided to exemplify the shortcomings of conventional imaging techniques and the utility of the quantitative 3-D protocol.