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Biomedical subjects

D R Wenger

Publications and source records attributed to D R Wenger.

At least 55 records · Page 3Linked to original sources
PubMed1976

Results of proximal tibial osteotomy. The effects of tibiofemoral angle, stance-phase flexion-extension, and medial-plateau force.

Forty-eight knees were evaluated after proximal tibial osteotomy, performed for varus deformity to determine the desired amount of correction of the deformity, the effect of osteotomy on knee motion during gait and one medial-plateau force during standing, and the relationships between these factors and the result. Correction of the tibiofemoral angle to 5 degrees of genu valgum or more produced the best and most lasting results. Stance-phase flexion-extension increased the rotation decreased in knees with good results while the other gait parameters were not significantly changed. Medial-plateau force was decreased by successful tibial osteotomy. The knees with the best and most lasting results had 7 degrees of stance-phase flexion-extension or more during walking and either a valgus tibiofemoral angle of 5 degrees or more or a medial-plateau force of 50 per cent of body weight or less.

Adult↗
PubMedDate not supplied

Location of acetabular deficiency and associated hip dislocation in neuromuscular hip dysplasia: three-dimensional computed tomographic analysis.

Forty-one hips in 24 patients with neuromuscular disease (NMD) were studied using three-dimensional computed tomography (3DCT). The location of the acetabular deficiency was posterior (37%), anterior (29%), midsuperior (15%), and mixed (19%) (anterosuperior, posterosuperior, and global). Although subtle morphologic changes occurred in the entire acetabulum, the major acetabular deficiency coincided with the direction of the subluxation or dislocation. The location of the acetabular deficiency that develops in cerebral palsy is not always posterosuperior, as suggested by other authors. The pattern of spasticity that results in muscle imbalance around the hip joint and changes in proximal femur architecture causes hip subluxation or dislocation, which may be either, posterior, anterior, or midsuperior. 3DCT studies are required to analyze accurately and understand acetabular deficiency in childhood NMD. These image data also allow more accurate planning for surgery in neuromuscular hip dysplasia.

Acetabulum↗
PubMedDate not supplied

Three-dimensional characteristics of cartilaginous and bony components of dysplastic hips in children: three-dimensional computed tomography quantitative analysis.

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.

Acetabulum↗
PubMedDate not supplied

Genu valgum in children with coxa vara resulting from hip disease.

Three patients with chronic hip disease and progressive coxa vera deformity also had an unrecognized compensatory ipsilateral genu valgum until the primary hip deformity had been corrected operatively. This unrecognized genu valgum may become subtly worse in a growing child because of lateralization of the mechanical axis of the lower extremity with respect to the knee joint. Operative correction of coxa vara acutely moves the mechanical axis farther laterally, causing the occult genu valgum to become clinically apparent. The genu valgum may subtly worsen over time in a growing child because of lateralization of the lower extremity mechanical axis with respect to the knee joint, with the resulting abnormal Hueter-Volkmann forces across the physis causing progressive genu valgum. Recognition of occult genu valgum before correcting coxa vara in children allows the surgeon the better to advise the family about the need for possible subsequent operations on the knee.

Adolescent↗
PubMedDate not supplied

"Functional retroversion" of the femoral head in Legg-Calvé-Perthes disease and epiphyseal dysplasia: analysis of head-neck deformity and its effect on limb position using three-dimensional computed tomography.

We studied femoral head and neck deformity in Legg-Calvé-Perthes disease (LCPD) and epiphyseal dysplasia using three-dimensional computed tomography (3DCT) in 17 patients (22 hips). The deformed femoral head can be divided into two portions: (i) the portion that protrudes anterolaterally and inferiorly (false head), often blocking internal rotation (lower margin is radiographic "sagging rope" sign) and (ii) the posteromedial superior portion (true head), representing the original articulating femoral head. This remodeled segment is retroverted in relation to the anterolateral segment resulting in "functional retroversion," which causes an externally rotated gait. This position also produces "functional coxa vara" measured by the relationship with the greater trochanter. These studies contradict previous reports of increased anteversion in LCPD and explain the paradox of supposed increased anteversion on radiograph in a child who walks with the limb externally rotated.

Adolescent↗
PubMedDate not supplied

Surgical correction of "functional retroversion" and "functional coxa vara" in late Legg-Calvé-Perthes disease and epiphyseal dysplasia: correction of deformity defined by new imaging modalities.

We studied six patients with severe femoral head deformity treated surgically by valgus-flexion-internal-rotation femoral osteotomy plus simultaneous acetabuloplasty based on the concept of "functional retroversion" and "functional coxa vara" of the deformed femoral head in late severe Legg-Calvé-Perthes disease and epiphyseal dysplasia. The combined procedure achieves the following: (i) corrects the "functional coxa vara" and hinge abduction (valgus osteotomy); (ii) establishes a more normal articulation between the posteromedial portion of the true femoral head and the acetabulum, while moving the anterolateral protruding portion of the femoral head away from the anterolateral acetabular margin (valgus-flexion osteotomy); (iii) corrects external-rotation deformity of the distal limb (internal-rotation osteotomy); (iv) improves joint congruity and anterolateral femoral-head coverage in hips with associated acetabular dysplasia (acetabuloplasty).

Adolescent↗
PubMedDate not supplied

The morphology of residual acetabular deficiency in childhood hip dysplasia: three-dimensional computed tomographic analysis.

Seventy hips (in 48 patients) in children with residual dysplasia resulting from developmental dysplasia of the hip (DDH) were evaluated by using three-dimensional computed tomographic (3DCT) imaging to clarify the nature and degree of acetabular and femoral head deformity. We noted four types of dysplastic acetabulae: type I, subtle deficiency of the acetabulum with a mild break in Shenton's line (24%); type II, anterosuperior deficiency (29%); type III, midsuperior deficiency (38%); and type IV, global deficiency (9%). In untreated DDH with complete dislocation, the deficiency was predictably midsuperior (type III). Isolated posterosuperior deficiency, which is common in neuromuscular conditions, was not seen in these normal children with DDH. The 3DCT method used produced a topographic "contact map" that replicates the contact relation between the acetabulum and the femoral head. Analyzing the femoral head-acetabular contact relation and the type of acetabular deficiency allows the surgeon to plan better surgical correction of hip dysplasia in children.

Acetabulum↗
PubMedDate not supplied

Congenital dislocation of the knee.

Between February 1988 and June 1995, 24 congenital dislocations of the knee joints (17 patients) were reduced with closed methods including immediate reduction, serial casting, or traction in patients from 10 min to 26 days old. At an average follow-up of 4 years and 10 months, an excellent or good result was achieved if there were no associated anomalies. Fair or poor results were the result of delayed treatment or associated musculoskeletal anomalies including arthrogryposis multiplex congenita or Larsen's syndrome. Routine check of the hip dislocation is suggested. Diagnosis with manual testing was difficult, and other methods such as radiography or sonography were suggested in combination to detect hip dysplasia. The dislocated knee should be reduced before treating the hip dislocation. Concomitant treatment of the congenital dislocation of the knee and the hip with Pavlik harness provided satisfactory results. When late, progressive, genu valgus deformity occurred because of global instability of the knee and asymmetric physeal growth, reconstruction of the medial structures of the knee and prolonged bracing provided good results.

Casts, Surgical↗
PubMedDate not supplied

Anteversion of the acetabulum in developmental dysplasia of the hip: analysis with computed tomography.

Acetabular anteversion was measured by using two-dimensional (2-D) computed tomography (CT) scans in 39 dysplastic and 27 normal hips (patient age range, 3-33 years), and averaged 19.7 degrees in the dysplastic hips and 18.1 degrees in the normal hips. There was no statistically significant difference between the two groups, with a wide range of acetabular anteversion values noted in both groups (8-32 degrees ). Although acetabular anteversion may be increased in some patients with developmental dysplasia of the hip (DDH), it is not a universal finding. We believe that assessment and understanding of acetabular anteversion is needed before performing corrective osteotomies for hip dysplasia to optimize results and avoid the complications of acetabular retroversion.

Acetabulum↗
PubMedDate not supplied

Congenital coxa vara: computed tomographic analysis of femoral retroversion and the triangular metaphyseal fragment.

Three patients with congenital coxa vara studied with two- and three-dimensional computed tomographic (2DCT and 3DCT) methods are reported. In all cases, the femoral retroversion was documented and subsequently corrected by proximal femoral osteotomy. In two patients with isolated coxa vara, the physeal-femoral neck angle was decreased as seen in slipped capital femoral epiphysis in adolescents. Our studies suggest that the triangular metaphyseal fragment reflects a Salter-Harris type II separation pattern through the defective femoral neck. The epiphysis and attached triangular fragment slip from the normal superoanterior portion of the neck in an inferior-posterior direction. The treating surgeon should be aware of the often marked femoral retroversion component present in severe congenital coxa vara. This knowledge allows surgical planning for corrective osteotomies that will better normalize hip mechanics. A combination of marked valgus and flexion with internal rotation of the distal fragment are required to fully correct the deformity.

Acetabulum↗
PubMedDate not supplied

Biomechanics of scoliosis correction by segmental spinal instrumentation.

The mechanical effectiveness of applying transverse forces by segmental spinal instrumentation to correct scoliosis is examined in this paper. Comparisons with traditional Harrington instrumentation are made on the basis of each method's potential to produce corrective bending moments and their ability to transfer this correction to the spine. Recognizing the scoliosis is a three-dimensional deformity, biomechanical evaluations are performed in each of the three anatomic planes, with special attention paid to maintaining normal sagittal plane contour and transverse plane derotation. Such an analysis indicates that segmental spinal instrumentation has a clear mechanical advantage over traditional Harrington instrumentation in providing and maintaining correction. Proposed improvements include the development of instrumentation which can be segmentally attached to the vertebra without invading the spinal canal.

Biomechanical Phenomena↗