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Biomedical subjects

R S Siffert

Publications and source records attributed to R S Siffert.

At least 19 recordsLinked to original sources
PubMed1990

Non-invasive low-intensity pulsed ultrasound accelerates bone healing in the rabbit.

The effect of ultrasound (US) on the rate of fibula osteotomy healing in 139 mature New Zealand white rabbits was assessed in this study. Bilateral midshaft fibular osteotomies were made using a 1-mm Gigli saw. US was noninvasively applied to one limb for 20 minutes daily, while the contralateral limb served as a control. A 2.5-cm PZT transducer was applied to both limbs, with the treated limb receiving a 200-microseconds burst of 1.5-MHz sine waves repeated at 1.0 kHz. The incident intensity was approximately 30 mW/cm2. Animals were killed at intervals between 14 and 28 days. Maximum strength increases (significant to p less than or equal to 0.01) ranged from 40 to 85% from postoperative day 14 to 23. On day 28, no significant difference in ultimate strength was noted. From day 17 through day 28, all US-treated fractures were as strong as intact bones (p less than or equal to 0.005). On the other hand, the ultimate strength of the control osteotomies attained intact values only by day 28. These results indicate that biomechanical healing is accelerated by a factor of nearly 1.7. This occurs with an overall acceleration of the healing curve in this fresh fracture model. If noninvasive low-intensity pulsed sine wave ultrasound can significantly accelerate bone repair in clinical application with an in-home treatment of 20 minutes daily, then US may be a useful adjunct for fracture care with a concomitant impact on patient morbidity.

Animals↗
PubMed1990

Deterioration of trapeziometacarpal arthritis due to trigger thumb: a biomechanical evaluation.

Patients with trigger thumb and trapeziometacarpal joint arthritis accompanied by swan-neck deformity of their first rays find that their arthritic pain becomes worse whenever their thumbs "catch." Six hands with adduction contracture and arthritis of the trapeziometacarpal joint are studied biomechanically and demonstrate significantly excessive shear forces (p less than 0.01) around their trapeziometacarpal joint relative to six normal hands. Increased pain with deformity suggests aggressive treatment of trigger thumb in cases such as these.

Aged↗
PubMed1983

Growth recovery zones.

Growth arrest lines and zones have been reinvestigated. Sequential studies after dietary deprivation reveal transformations of the physis with diminution in formation of the zone of cell columns, resorption of previously formed bone, and cessation of new bone formation. At 6 weeks post diet restriction, the physis is prominently narrowed with transversely oriented, thin bone plaque sealing it from the subjacent marrow. Initially, restoration of stock diet thickens the bony plaque, creating a growth arrest line. Later the zone of osteogenesis adds new bone as a dense metaphyseal band.

Animals↗
PubMed1983

"Beak" triple arthrodesis for severe cavus deformity.

Attention is called to the principles of a technique described more than 20 years ago that has proved clinically useful in the correction of severe cavus and cavovarus deformities when foot stabilization by triple arthrodesis is indicated. The method obtains correction of the cavus deformity by depressing the anterior aspect of the foot beneath a beak or ledge created in the talus, thereby preserving the vascularity to the talus and the integrity of the anterior ankle joint without shortening the foot.

Arthrodesis↗
PubMed1983

Complications of Ender-pin fixation in basicervical, intertrochanteric, and subtrochanteric fractures of the hip.

Two hundred patients with a basicervical, intertrochanteric, or subtrochanteric fracture were treated by Ender-pin fixation during a three-year period. Their median age was 73.5 years and there was a 10 per cent mortality rate. Early partial weight-bearing with some external support was allowed for most patients. Minimum shortening and one non-union occurred. However, there was a substantial incidence of complications. The fixation failed in all basicervical fractures. Distal pin migration of more than two centimeters occurred in 50 per cent of the unstable intertrochanteric fractures. Seventy-six per cent of the forty-two patients who were personally examined at follow-up had pain in the knee and 36 per cent had external malrotation. The incidence of pin migration increased in the more unstable fractures.

Adult↗
PubMed1982

Intraepiphyseal osteotomy for progressive tibia vara: case report and rationale of management.

Tibia vara (Blount's disease) is characterized by two components, the epiphyseal, which is concerned with articular relationships, and physeal/metaphyseal, which may produce angulation of a long bone. Although the initial etiology is not known, it appears that asymmetrical pressure applied to the angulated proximal tibia results in progressive deformity. In the initial stages, medial and posteromedial pressure causes growth retardation of the epiphysis (articular instability) and the physis (tibia vara). Nonsurgical or surgical treatment that relieves the pressure generally permits reconstitution of normal growth. Continued abnormal pressure and shear forces applied to the physis may result in disorderly enchondral ossification and produce a true osteochondrosis, which may lead to permanent physeal arrest. Osteotomy alone to relieve medial pressure may allow the tibia to grow straight, but residual medial epiphyseal compression and joint instability may persist. A case is reported of a 13 1/2 year follow-up of a patient in whom intraepiphyseal osteotomy restored articular congruity without interfering with longitudinal growth. The risks and experimental nature of this procedure are emphasized.

Child↗
PubMed1982

Tissue antibiotic levels with tourniquet use in orthopedic surgery.

Ten adult mongrel dogs were given 500 mg of cefazolin intravenously, before and after tourniquet cuff inflation. Muscle tissue antibiotic levels were comparable to the control side when the antibiotic was administered prior to tourniquet inflation. Muscle tissue antibiotic levels were markedly diminished compared to the control limb when the antibiotic was given after the tourniquet was inflated. The low level of antibiotic appeared slowly and peaked at 60 minutes as a reflection of minimal limb blood flow. It was questionable whether the small antibiotic concentration in the latter situation served adequate protective cover.

Animals↗
PubMed1982

Surgical management of metastatic disease of bone at the hip.

Concordant advances in cancer chemotherapy, radiotherapy, and surgical technique have been of apparent benefit to many cancer patients suffering from skeletal involvement at the hip. Consideration of the effects of underlying disease and prior treatment must be evaluated prior to developing a surgical plan. Acetabular involvement can be treated by either conventional or augmented total hip arthroplasty using protrusio rings and acetabular meshes, depending upon minor or major degrees of tumor destruction. Girdlestone resection arthroplasty for massive degrees of acetabular involvement yields only modest results. Femoral neck fractures can be treated by endoprosthetic replacement. However, the association of acetabular disease should be considered, and if present, total hip arthroplasty should be performed. Intertrochanteric fractures can be stabilized with the use of a stout tubeplate nail device plus cement. Subtrochanteric fractures can be stabilized with a Zickel nail device plus cement. The goals of treatment are to relieve pain and restore function by using a device with an anticipated fatigue life which should exceed the patient's life expectancy.

Acetabulum↗
PubMed1981

Patterns of deformity of the developing hip.

The hip joint presents a coaptive relationship between the head of the femur and the acetabulum. Developmental changes in either component affect the responsive growth of its companion. Normal pressure of the head of the femur in the acetabulum maintains a balance in the proliferation of triradiate and acetabular growth cartilage. Secondary deformities occur as a result of failure of head-acetabular relationships as in congenital dislocation of the hip and primary epiphyseodesis of the triradiate cartilage (TRC). Anatomically the proximal femur adapts to the growth of the primary epiphyses and associated biomechanical forces. The femoral head and greater trochanter enlarge by appositional growth, and their subjacent growth plates, nourished by epiphyseal vascularity that penetrates the bony end plate, contribute to length and width of the neck, respectively. During infancy and early childhood the longitudinal growth plate (LGP) of the neck is horizontal. The shape of the proximal femur depends primarily upon lateral contributions of the trochanteric growth plate (TGP) and the femoral neck isthmus (FNI) balanced against the longitudinal and slightly medial contributions of the LGP. The resultant longitudinal vector of axial and medial (LGP) and lateral (TGP and FNI) directions of growth maintains biomechanical forces about the hip while at the same time insuring the trajectory of growth in line with the axis of the femur. An understanding of the interrelationships of the growth zones of the proximal femur and their alterations as a result of genetic, environmental, and developmental influences permits early diagnosis of growth deformities and the opportunity to plan early corrective procedures.

Acetabulum↗