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Biomedical subjects

H M Dick

Publications and source records attributed to H M Dick.

At least 19 recordsLinked to original sources
PubMed1999

Lengthening of pediatric forearm deformities using the Ilizarov technique: functional and cosmetic results.

Eight patients (average age, 10 years) had a unilateral forearm lengthening procedure using the technique developed by Ilizarov. The procedure was performed in 4 patients with radial agenesis, in 2 with multiple hereditary exostosis, in 1 with ulnar agenesis, and in 1 with multiple enchondromatosis. Patients underwent distraction osteogenesis through either a unifocal or bifocal corticotomy. Forearm length increased on average 6.0 cm (range, 3.6-8.1 cm) or 54% (range, 21% to 94%) with a lengthening index of 1.3 months per centimeter (range, 0.6-1.9 months per centimeter). The length of follow-up averaged 4.5 years and involved office examinations with task evaluation and a questionnaire addressing function and appearance. Limb length discrepancy at follow-up measured 3.7 cm (range, 0.0-8.0 cm). Lengthening of the forearm was found to improve upper extremity function; it allowed the patient to reach distant body parts and to perform select activities requiring near-equal arm length. Forearm lengthening also improved the appearance of the arm if adequate soft tissue was preserved. Full restoration of arm length was not a requirement for a successful outcome and patient satisfaction with the results of the procedure was high.

Adolescent↗
PubMed1997

A curriculum for the ideal orthopaedic residency. Academic Orthopaedic Society.

The Academic Orthopaedic Society met in April 1994 to discuss manpower issues in orthopaedics. The members developed an approach using the Delphi system to define and obtain consensus on the characteristics of the ideal residency. Six categories of educational attributes were included: General; Clinical Management; Skills and Technical Aspects; Rehabilitation; Basic Science and Research; and Educational Environment. The following year a questionnaire was sent to more than 125 programs in an attempt to have residents and staff anonymously self score their residencies according to the standards defined by the Delphi panels. The results obtained from the 745 responders from 73 programs validate effectively the characteristics of the ideal program and also show the variation among the programs.

Clinical Competence↗
PubMed1995

Supracondylar femoral osteotomies for the correction of angular deformity about the knee in children. A follow-up study.

The results of 18 supracondylar osteotomies of the femur performed for angular deformity about the knee joint on 14 patients under the age of 18 years were reviewed. The mean follow-up was 46 months. Twelve of 18 osteotomies had a successful outcome. Six were considered failures due to recurrence of angular deformity despite bony union at the osteotomy site. Four of the six failures occurred in patients with metabolic bone disease. Special care needs to be taken when planning supracondylar osteotomies in patients with metabolic disease.

Adolescent↗
PubMed1994

Compressive stress-relaxation behavior of bovine growth plate may be described by the nonlinear biphasic theory.

The compressive behavior of the bovine distal femoral growth plate was studied in vitro. Strain-rate controlled, compression stress-relaxation experiments were performed on cylindrical bone-growth plate-bone specimens from the interior and periphery of the growth plate. The questions addressed in this study were (a) Can the nonlinear biphasic theory, one with strain-dependent permeability, be used to represent the compressive stress-relaxation behavior of bovine growth plate? (b) How do different assumptions concerning the permeabilities of the chondro-osseous interfaces influence the inferred material properties of the growth plate? and (c) Are there any differences in these properties between the periphery and the interior of the growth plate? Intrinsic biphasic material properties--aggregate modulus (HA), Poisson's ratio (v), and nonlinear strain-dependent permeability coefficients (ko and M)--were calculated from the compression stress-relaxation data with use of a finite element model and a least squares curve-fitting procedure. To verify this constitutive model for the growth plate, an independent set of finite element analyses was performed with use of the determined intrinsic biphasic properties, and comparisons were made between these finite element predictions and two additional sets of experimental data subsequently obtained for the same specimens with use of two slower rates of compression. Excellent agreement was achieved between these finite element predictions and the latter two sets of data. The aggregate modulus was found to be insensitive to the permeability of the chondro-osseous interface. The permeability coefficients were very sensitive to, and the Poisson's ratio was only slightly sensitive to the interface permeability condition. Therefore, the periphery of the growth plate is more compliant and permeable than the interior.

Animals↗
PubMed1994

Infection of massive bone allografts.

A retrospective analysis of 75 consecutive cases of massive allograft implantations performed from July 1976 to October 1986 was conducted. Seventy percent of these patients had malignant bone tumors. Of the total group, 10 (13.3%) patients developed a deep infection of the allograft and are the subject of this review. Followup averaged 6.3 years from the time of infection onset. Final results were evaluated with a revised Mankin classification. Seventy percent of infections occurred within 1 month of the initial surgery. Polymicrobial infections were present in 50%. Wound and soft tissue complications were found to be the major predisposing risk factors for infection. Chemotherapy was not a statistically significant risk factor using Chi-square analysis. All allografts eventually had to be completely removed to control the infection. Limb salvage was possible in 7 patients, but 3 patients required an amputation. Two of the 3 amputations were performed for infection control, and 1 was performed for tumor recurrence with concurrent infection. Two allografts were salvaged with vascularized free fibula transfers. Two patients had implantation of a second allograft, which also became infected. Three patients required no further reconstruction. Results were: Excellent--2, Good--1, Fair--4, and Poor--3. Soft tissue coverage is of utmost importance in massive allograft procedures and should be ensured with local or free flaps, if necessary.

Adolescent↗
PubMed1993

Treatment of tibial defects and nonunions using ipsilateral vascularized fibular transposition.

Eight patients had nine ipsilateral vascularized fibular transpositions (IVFTs) in the period 1978-1987. The procedure, which involves no microvascular anastomosis, was done for difficult problems of the tibia including two long-standing posttraumatic nonunions, three allograft nonunions after tumor surgery, and four segmental tibial defects also after tumor surgery. The average duration of problems before surgery was 3.5 years, and the patients averaged 3.1 procedures before IVFT. The patients were followed for an average of 52.4 months. The average time to union was 4.2 months, and in all patients the grafts healed within six months. Late fracture of the graft developed in two patients after fixation removal; one required an additional procedure, and both eventually healed. Ipsilateral vascularized fibular grafting is a useful alternative to conventional, nonvascularized grafts for difficult tibial nonunions and segmental defects. It offers the advantages of a vascularized graft (early healing and hypertrophy), yet avoids the time-consuming microvascular anastomosis and distant donor site morbidity of free fibular grafts.

Adult↗
PubMed1992

The microstructural tensile properties and biochemical composition of the bovine distal femoral growth plate.

The tensile properties of distal femoral growth plates from 12-month-old cows were determined on uniformly prepared straight bone-growth plate-bone specimens (7 x 7 mm2 in cross-section) from predetermined anatomical sites on the physis. Each specimen was distracted to failure using a computer-controlled servo-hydraulic testing machine at a strain rate of 0.004 s-1. It was found that the exponential constitutive law, using finite deformation formulation for strain, provides an excellent description of the stress-strain behavior of all the specimens up to the point of failure. The ultimate stress and both tangent moduli (i.e., the toe region tangent modulus and the tangent modulus calculated at 75% of ultimate strain) varied with anatomical site. The anterior region was the strongest, followed by the posterior/lateral. The anterior and posterior/lateral regions were also the stiffest, whereas the posterior/medial and center regions were the weakest and most compliant. The bone-growth plate-bone specimen exhibited a low ultimate strain (13.8% +/- 6%) that did not vary significantly throughout the growth plate. This result suggests that disruption of the physis may occur in vivo even at the lower distractions currently recommended for the clinical chondrodiatasis procedure for leg lengthening. The biochemical composition of the growth plate in the anatomical regions correlated well with the tensile properties. There was a greater collagen content in the regions that were the stiffest and strongest. The gross morphology of the growth plate of the bovine distal femur is also described in this study. There is a regular pattern to the undulations of the physis at several dimensional levels. Histologic findings showed that orientation of the hypertrophic cell columns and transphyseal septa are aligned nearly parallel to the longitudinal axis of the diaphyseal shaft. This column orientation is not affected by the undulation of the primary contour of the physis, which at certain locations may be inclined as much as 60 degrees relative to the diaphyseal axis. The orientation of the hypertrophic cell columns appears to be one of the dominant microstructural features influencing the tensile behavior of the bone-growth plate-bone specimens.

Animals↗
PubMed1992

Heterogeneous in vivo MR images of soft tissue tumors: guide to gross specimen sampling.

Twelve soft tissue tumors preoperatively studied with magnetic resonance (MR) imaging contained areas of inhomogeneous intralesional signal intensity. The pathologist's selection of biopsy sites from gross specimens was based on specific MR images selected by a radiologist and depended on close cooperation between the radiologist and pathologist. The histopathology so sampled, further depended on the lesion's size, careful gross specimen orientation, discrete sampling, and a specially developed Grid Analysis technique. Our initial experience indicates that (1) histology may vary within different and often neighboring sites of a single soft tissue lesion; (2) that such variability is common in soft tissue tumors; (3) that histological variability within different sites of a single lesion influences signal heterogeneity; and (4) that although differing MR signal intensities per se are not tissue specific, MR may enhance the histopathological accuracy of pathologists who can be directed to particular gross specimen sites by magnetic resonance images. To our knowledge such a specific, detailed effort has not been made.

Adult↗
PubMed1991

Magnetic resonance grid analysis of soft tissue lesions.

Soft tissue tumors of seven patients were imaged with magnetic resonance imaging (MRI) prior to operative resection. In four cases, gross surgical specimen biopsy sites were broadly selected from areas of diverse signal intensity. A subsequently developed "grid analysis" technique, used in three additional patients, better localized differing zonal intensities within individual gross specimens. Further investigation of this technique is warranted, since MR images, when analyzed by means of a detailed grid technique, appear to enhance histologic diagnostic accuracy. Examination of larger segments of inhomogeneous soft tissue tumors is facilitated, while pathologists' sampling time is diminished.

Adult↗
PubMed1991

Articular fractures of the hand. Part I: Guidelines for assessment.

Articular fractures of the hand represent a particularly challenging group of injuries owing to the frequent comminution of the fractured bone, disruption of a finely balanced soft-tissue sleeve, and a propensity for scarring and contractures. Assessment of these fractures must include accurate delineation of the injury, using roentgenographic and computed tomographic imaging to define articular congruency, and a precise examination to determine stability.

Finger Injuries↗
PubMed1991

Articular fractures of the hand. Part II: Guidelines for management.

Articular fractures of the hand represent a particularly challenging group of injuries owing to the frequent comminution of the fractured bone, disruption of a finely balanced soft-tissue sleeve, and a propensity for scarring and contractures. Treatment must restore anatomic joint alignment and stability and should incorporate a carefully guided early rehabilitation program. Part I of this article, which appeared in the January issue, covered techniques for the evaluation of these complex injuries.

Finger Injuries↗
PubMed1990

Limited open surgical approach for external fixation of distal radius fractures.

In an effort to reduce treatment-related complications, a surgical procedure has been developed for the insertion and application of an external fixation device in the management of unstable fractures of the distal radius. Clinical experience with this device has demonstrated its effectiveness in reducing complications associated with pin insertion. The surgical technique is presented together with a case example. Results of laboratory tests corroborate our clinical experience and demonstrate the effectiveness of this technique in minimizing complications. Clinical results in 66 cases document the efficacy and safety of this technique.

Adult↗