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PubMed1977

8. Self-compressing implants in the management of fractures.

Internal fixation of fractures has become increasingly important since the introduction of self-compressing implants. Rigidity of fixation thus ensured permits primary bone healing. Two types of self-compressing implants are available--screws and plates. The former produces compression between fracture fragments, the latter, along the long axis of the bone. Two common types of plates are the dynamic compression plate and the Osteo self-compressing plate. Use of self-compressing implants requires familiarity with the technique, a definite plan of operation, and strict asepsis and lack of infection in the patient. Indications for the technique include failure or unsuitability of closed reduction of fractures, care of associated serious soft-tissue injuries, and displaced intra-articular fractures. Use of self-compressing plates hastens rehabilitation, lessens joint stiffness and reduces the duration of hospitalization. The incidence of nonunion with self-compression techniques is lower than with traditional methods of fracture management.

Bone Plates↗

PubMed1978

Metastatic abdominal implants of endometrial carcinoma demonstrated on 99mtc-methylene diphosphonate bone scan.

Metastatic serosal and omental implants from a primary papillary endometrial carcinoma were well demonstrated by radionuclide uptake on a bone scan utilizing 99mTc-methylene diphosphonate. Imaging of an endometrial malignancy by a 99mTc-labeled phosphate compound has not previously been reported. While the exact mechanism of accumulation in such soft-tissue neoplastic foci is not known, several possibilities have been suggested. In this particular case, the mechanism appears related in some way to the presence of dystrophic calcifications within the metastatic deposits.

Abdominal Neoplasms↗

PubMed1979

Interface radiation dosimetry in mandibular reconstruction.

When a beam of radiation crosses the interface between two substances, secondary electrons are generated. This results in enhancement of the absorbed dose of radiation roughly proportional to the difference in atomic numbers. Interfaces are created in reconstruction of the mandible with implantable trays containing hematopoietic bone marrow and cancellous bone chips. Radiation was measured in tissue-equivalent material surrounding mandibular tray implants of titanium, vitallium, stainless steel, and Dacron/polyetherurethane. The absorbed dose was enhanced by 29% to 36% adjacent to the metallic trays; 1% dose enhancement was noted adjacent to the Dacron/polyetherurethane tray. We conclude that, when radiation therapy is necessary following mandibular reconstruction, homogeneity of dose is maintained and local soft-tissue reactions to excessive irradiation may be avoided by using a nonmetallic tray.

Biocompatible Materials↗

PubMed1991

Experimental transplantation of the Swarm rat chondrosarcoma into bone: radiological and pathological studies.

The Swarm rat chondrosarcoma has been the subject of extensive biochemical studies. However, to our knowledge, there are no previous reports in the literature on transplantation of this tumor into bone. This article describes the natural history of the tumor when implanted into the bone of the rat, and correlates its histological growth pattern with its radiological appearance. Our results showed that the tumor grows slowly in the bone. The rate of intramedullary growth, however, was variable and was not the same in all the animals. Its growth pattern resembles human chondrosarcoma, with extensive invasion of the marrow and cortex. In the first few weeks after implantation, the only radiological changes noted were mild medullary radiopacities. At a later stage, 12-14 weeks postimplantation, as the tumor infiltrated the bone, significant radiological abnormalities were observed in the medullary cavity and cortex. Periosteal reaction was seen after the tumor invaded the cortex with the production of a soft-tissue mass. Distant dissemination was rare; only 1 of 24 rats developed pulmonary metastases. The Swarm rat chondrosarcoma is a well-differentiated malignant tumor that histologically resembles well-differentiated human chondrosarcoma. Transplanted into bone, it may be useful as an experimental model for comparative studies with human chondrosarcoma.

Animals↗

PubMed1992

Oral administration of D-penicillamine causes neonatal mortality without morphological defects in CD-1 mice.

D-Penicillamine (DPA) causes axial skeletal defects in rats and fetal lethality when given as 0.83% and 1.6% of the diet, but its mechanism of action on the axial skeleton is unknown. We have been using submerged fetal CD-1 mouse limb-bud organ cultures to evaluate the mechanisms of teratogenesis in the developing murine limb. Before attempting to evaluate the in vitro effects of DPA, a dose response morphological teratology study was undertaken using CD-1 mice to determine the effects of DPA on the mouse and determine the potential of using the mouse limb-bud assay to investigate the terata produced by DPA. Groups (n = 8) of nulliparous pregnant mice (vaginal plug = day 0 of gestation) were dosed, via oral gavage, with 0, 250, 500, 1000 and 2000 mg kg-1 DPA for the first 12 days of gestation. Body weights and food consumption were measured daily. On day 18, fetuses were removed by Caesarian section. Two-thirds of the fetal skeletons were stained with alcian blue and alizarin red and then cleared and examined for defects. Soft-tissue defects were examined in the remaining one-third using a modification of the Wilson freehand technique. Maternal body weight gains were not different before day 12 of the experiment, but differed in the interval of day 13-18 (P = 0.004). No group differences were noted in male/female ratios, site of implantation, implantation numbers and number of fetuses. Decreased survivability was seen in the 2000 mg kg-1 group. No treatment-related defects were seen.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormalities, Drug-Induced↗

PubMed1991

Remodelling of bone around intramedullary stems in growing patients.

The remodelling of bone around intramedullary cemented stems, used for the fixation of massive distal femoral replacements in young patients, has been studied. Several types of remodelling have been identified, and this is common to all of the retrieved specimens that have been in situ for periods of 6 to 18 months. Transection of cortical bone and the insertion of a massive prosthesis leads to (a) the formation of a pedicle of bone or bony bridge that grows from the transection site over the shaft of the prosthesis, (b) bone resorption at the transection site, (c) the development of an inner porotic cortex surrounding the intramedullary stem and subperiosteal bone formation, and (d) a shell of bone around the acrylic cement. The tibial component that allows continued growth of the proximal tibial physis consists of a press fit metallic plateau with a stem that slides into an ultra-high-molecular-weight polyethylene sleeve inserted below the growth plate. A sclerotic layer of bone forms adjacent to a soft-tissue interface around both the sleeve and the metallic component. Remodelling of bone around intramedullary stems is attributed either to a redeveloping blood supply or to load adaptive changes.

Adolescent↗

PubMed1991

Endoprosthetic reconstruction after bone tumor resections of the proximal tibia.

The advent of successful adjuvant chemotherapy and radiation therapy protocols for primary malignant tumors and the development of custom-designed metallic endoprostheses has now made possible a successful limb salvage procedure for malignancies of the proximal tibia. Use of the transposed medial gastrocnemius flap, as proposed by Dr. Jean Duboussett of Paris, has been critical to the soft-tissue reconstruction that routinely permits an excellent active and passive range of motion for these patients. This article describes the operative techniques and technical considerations necessary for a successful proximal tibial endoprosthesis reconstruction.

Bone Neoplasms↗

PubMed1991

Orthopedic fixation devices.

Orthopedic fixation devices are used in the treatment of fractures, soft-tissue injuries, and reconstructive surgery. After fracture reduction, internal, external, or intramedullary fixation devices may be used to provide stability and maintain the alignment of bone fragments during the healing process. They must be strong and secure enough to allow early mobilization of the injured part, as well as the entire patient. Compression is used whenever possible to increase the contact area and the stability between fragments and to decrease the stress on the implant. Screws are used primarily to provide interfragmental compression or to attach plates, which can then provide compression, prevent displacement, and support the fragments during healing. Pins and wires can be used for fixation of small fragments or fractures in small bones and for attachment of external fixation devices and traction. A basic understanding of the devices and principles of use is needed to interpret radiographs obtained after the treatment of musculoskeletal injuries.

Fracture Fixation↗

PubMed1992

Biocompatibility of surgical-grade dense polycrystalline alumina.

This article reviews the knowledge about biocompatibility of alumina since its introduction as a material for use in joint replacements. Alumina is a hydrophilic material with high wettability allowing very low friction with negligible wear. Macrophages loaded with alumina particles show no morphologic alteration and do not lose their chemotactic ability. The host response has been studied for bulk and particulate alumina in soft tissues, as well as in human and animal bone under loaded and nonloaded conditions. The soft-tissue response to bulk alumina exhibits minimal fibrosis, and direct bone contact is achieved at compression-loaded interfaces. Examination of human biopsies from failed total hip prostheses reveals a foreign-body reaction containing predominantly macrophages loaded with alumina particles. No lymphocyte or plasma-cell infiltration is observed because of the absence of soluble component release. The amount of necrosis and fibrosis was lower than that associated with metal or polyethylene debris. In summary, alumina exhibits greater bioinertness than all other implant materials currently available for joint replacement.

Aluminum Oxide↗

PubMed1992

Experimental applications of porous (coralline) hydroxylapatite in middle ear and mastoid reconstruction.

Hydroxylapatite is a ceramic implant material which has been extensively investigated in the orthopedic and oral surgical literature. A set of animal experiments was carried out to determine the feasibility of the use of porous (coralline) hydroxylapatite for middle ear and mastoid reconstruction. Coralline hydroxylapatite was placed in the mastoid bulla of dogs and was carved into struts which were placed into the middle ear and against the tympanic membrane. Coralline hydroxylapatite is a highly biocompatible material which showed abundant ingrowth when in contact with host bone. There was also good soft-tissue ingrowth and fibrous tissue fixation within the middle ear and against the tympanic membrane. Hydroxylapatite is generally accepted to be osteoconductive, but not osteogenic. However, one of the specimens described with chronic inflammatory mucosal changes, shows de novo new bone formation within the pores of the graft. While normally the bone formed in coralline hydroxylapatite is secondary (lamellar), in this specimen primary (woven) bone was found. Porous (coralline) hydroxylapatite appears to be an excellent otologic graft material. It biointegrates with the host, is osteoconductive, and under certain circumstances may be osteogenic.

Animals↗

PubMed1991

Osteopromotion for cranioplasty. An experimental study in rats using a membrane technique.

Various techniques for treatment of large cranial defects have been reported, but the use of alloplastic materials still seems to predominate. The authors have applied and explored a new approach for bone repair which appears promising, even for use in less osteogenic environments such as the adult calvaria. Seventy-two adult Sprague-Dawley rats each received bilateral 8-mm trephine defects in the temporoparietal area; this defect size precludes spontaneous osseous healing during the lifetime of the animal. Five surgical procedures, employing various alternatives of biologically inert expanded polytetrafluoroethylene membrane positioning and intramembranous bone-chip implantation, were performed and compared to control defects. Slight improvement of bone regeneration was demonstrated with subperiosteal ectocranial and endocranial membranes, alone or in combination, and with bone chips alone or in combination with an outer or inner membrane. Virtually complete bone healing was observed in animals receiving both an outer and an inner membrane with interpositioned bone chips. The latter appeared to function primarily as space-holders by keeping the membranes separated throughout the defect. Consequently, this technique seems to significantly promote bone repair by excluding soft-tissue components from the bone-healing site.

Animals↗

PubMed1992

The use of Gore-Tex implants in aesthetic surgery of the face.

Deep wrinkles and folds usually are not completely or permanently corrected with face lifting, fat or collagen injections, chemical peels, and other known procedures. It is suggested that a permanent implant, well tolerated by human tissues, could be helpful as an isolated or associated procedure. An expanded synthetic polymer known as Gore-Tex expanded polytetrafluoroethylene soft-tissue patch is available and is easy to use to approximate and correct defects; it also can be used as a filling material or to replace other kinds of prostheses to get better projection of frontal, orbital, malar, and chin areas. I have used this material in my clinic for 5 years. Indications and results of the first cosmetic cases are reported herein.

Adolescent↗

PubMed1992

[Epitheses of the face].

Despite progress in maxillofacial cancer surgery, most patients present disfiguration of their faces. External prostheses are a pleasing alternative to camouflaging maxillofacial mutilations after tumor ablation. Established indications for external prosthesis are: 1. the patient refusing soft-tissue reconstruction, 2. patient's multimorbidity, and, 3. the impossibility of fully reconstructing a specific maxillofacial defect. Consequently, the benefits of applying external prosthesis include the simple camouflage of an unsightly tumor defect, the ease in supervising any possible local tumor growth beneath the external prosthesis as well as helping to prevent patient's isolation. Thus, external prostheses are a good option in the rehabilitation of maxillofacial surgery patients.

Adult↗

PubMed1992

[Favorable results of the surgical treatment of intra-articular crush fractures of the distal femur].

Severely comminuted intra-articular femoral fractures are usually associated with major soft-tissue damage as a part of serious multiple injuries. Surgical treatment should aim at exact anatomical restoration of the articular surface. Internal fixation should be stable so that functional after-treatment is possible, a condition of achieving an optimal result. In a period of over 7 years, 24 patients with 26 intra-articular comminuted fractures were operated on. Twenty patients had multiple injuries (ISS > 18), 11 fractures were complicated. Postoperatively, impaired wound healing occurred in three elderly patients; in two of these amputation was necessary. Considering the severity of the injury, the long-term results were good: ten of the 16 patients examined with 18 fractures recovered completely, in the other cases the functional result wa adequate to good. Surgical treatment of comminuted intra-articular fractures of the distal femur is to be adapted to the individual case; depending on the fracture type and the associated damage a selection is to be made from various implants and techniques. With consistent, individually adapted application of the current AO techniques good results can be obtained.

Adult↗

PubMed1992

Quantitative analysis of lidocaine hydrochloride delivery by diffusion across tissue expander membranes.

Permeability of Silastic tissue expander shells to lidocaine was studied to investigate the feasibility of intraluminal lidocaine injection for pain relief during soft-tissue expansion. Both intact expanders and an apparatus using isolated Silastic membrane segments were used to partition solutions of various lidocaine concentrations, and the rate of diffusion was quantitatively measured using a fluorescence polarization immunoassay. Lidocaine flux was found to follow Fick's law of passive diffusion with respect to time, surface area, and concentration gradient for the first 9 hours, with a permeability coefficient of 10.3 +/- 2.6 micrograms (h.cm2.percent)-1 (mean +/- SD) and diffusion coefficient of 7.5 x 10(-7) cm2/min for an average membrane thickness of 473 +/- 23 microns. After 9 hours, the lidocaine flux decreased exponentially, although the concentration gradient across the membrane remained essentially the same order of magnitude. Plasma proteins in the outer bathing solution and methylparaben used as a preservative in the standard lidocaine formulation had no influence on the change in transport flux with time. At the end of the linear portion of the diffusion curve, less than 2 percent of the total intraluminal lidocaine had crossed the membrane. Potential toxicity in the event of implant rupture limits the maximum total lidocaine dose to approximately 500 mg within an expander at any one time. Within these limits, the capacity for lidocaine delivery of 500 mg lidocaine by a 640-cc tissue expander would be only 6 mg during the first 9 hours after administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Diffusion↗

PubMed1990

A clinical evaluation of resorbable hydroxylapatite for the repair of human intra-osseous defects.

One of the goals of periodontal therapy is actual hard- and soft-tissue regeneration or at least the functional repair of periodontal defects. Alloplastic materials used in the past included dense hydroxylapatite grafts which were non-resorbable and often exfoliated. A new resorbable hydroxylapatite biomaterial [OsteoGen (HA RESORB)] was used during flap surgery. After the usual initial therapy, full-thickness flaps were elevated. A through debridement of the roots and osseous defects was accomplished. The defects were measured and then filled with OsteoGen. The mean initial bone defect depth was 4.47 mm. These defects were re-evaluated by the probing of bone levels after a 4-6-month healing period. A mean of 2.26 mm of new bone fill was obtained. This represents an average fill of 51%. Seventeen of the 22 defects had 42% or more actual new bone fill. No foreign body reaction or exfoliation occurred.

Alveolar Bone Loss↗

PubMed1991

Analysis of silicon in human breast and capsular tissue surrounding prostheses and expanders.

Diffusion of polydimethylsiloxane from silicone breast prostheses and soft-tissue expanders has been associated with capsular contraction. We used electron dispersive x-ray analysis and scanning electron microscopy to assess the presence of silicon in capsular tissue surrounding three categories of breast prostheses and expanders. Breast and subcutaneous tissues external to the capsules were used as control specimens. Semiquantitative results allowed capsules to be ranked according to implant type. Silicon was localized within the inner 2.0 mm of capsular tissue. The analyses of tissues from 2 patients exhibiting unilateral, Baker grade IV contraction after bilateral placement of prostheses showed less silicon present in the severely contracted capsule than in the less-contracted capsule. Results from this study diminish the importance of silicon as the initiator of capsular contraction.

Breast Diseases↗

PubMed1992

Use of a calf prosthesis and tissue expansion in aesthetic reconstruction of the leg.

We present a technique for reconstruction of the legs in patients with soft-tissue loss and formation of large scars with retraction of this tissue in the pretibial region. In such patients, a subcutaneous tissue expander is placed in the region adjacent to the scar tissue. With expansion, we obtained sufficient skin for use in the reconstruction, and the resulting asymmetry in leg diameter was compensated for by means of one or two calf prostheses, depending on the patient.

Adult↗