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Biomedical subjects

S A Stuchin

Publications and source records attributed to S A Stuchin.

At least 37 records · Page 2Linked to original sources
PubMed1995

The effectiveness of cut-proof glove liners: cut and puncture resistance, dexterity, and sensibility.

Five types of commercial glove liners (within double latex gloves) were compared to single and double latex gloves for cut and puncture resistance and for relative manual dexterity and degree of sensibility. An apparatus was constructed to test glove-pseudofinger constructs in either a cutting or puncture mode. Cutting forces, cutting speed, and type of blade (serrated or scalpel blade) were varied and the time to cut-through measured by an electrical conductivity circuit. Penetration forces were similarly determined with a scalpel blade and a suture needle using a spring scale loading apparatus. Dexterity was measured with an object placement task among a group of orthopedic surgeons. Sensibility was assessed with Semmes-Weinstein monofilaments, two-point discrimination, and vibrametry using standard techniques and rating scales. A subjective evaluation was performed at the end of testing. Time to cut-through for the liners ranged from 2 to 30 seconds for a rapid oscillating scalpel and 4 to 40 seconds for a rapid oscillating serrated knife under minimal loads. When a 1 kg load was added, times to cut-through ranged from 0.4 to 1.0 second. In most cases, the liners were superior to double latex. On average, 100% more force was required to penetrate the liners with a scalpel and 50% more force was required to penetrate the liners with a suture needle compared to double latex. Object placement task times were not significantly liners compared to double latex gloves. Semmes-Weinstein monofilaments, two-point discrimination, and vibrametry showed no difference in sensibility among the various liners and double latex gloves. Subjects felt that the liners were minimally to moderately impairing. An acclimation period may be required for their effective use.

Equipment Design↗
PubMed1993

Allografting in total knee replacement arthroplasty.

Revision, and complicated primary total knee arthroplasty (TKA), may present with significant structural bony defects. Allograft offers blocks of material that can be shaped to the defect. The opportunity to gain a biological bond may theoretically enhance loading conditions and enhance any subsequent surgery. However, the biomechanical and biological issues of immune response, infection, graft incorporation, resorption, and load transfer render allografting a powerful but problematic technology.

Adult↗
PubMed1992

Stability of press-fit acetabular cups.

Mechanical tests were performed to characterize the initial stability of press-fit cups as a function of cup design, surface structure, and surgical preparation. Eight cups from six manufacturers were press-fit into acetabular cavities prepared in two densities of Sawbones polyethylene foam and in bovine knee trabecular bone. Cavity sizes and cup loading forces were varied. Acetabular defects were simulated in the Sawbones model. Preparations were tested to determine axial-rotatory and tangential ("levering-out") stability. Results suggested that cup geometry and proper surgical technique--in particular, proper sizing and depth of the acetabular cavity--are important in determining initial cup stability independent of adjuvant screw or spike fixation. Stability is a function of the area of interface contact between the cup rim and the substrate. If the cavity is too small or too shallow, and the substrate too dense, the cup will not seat to the rim and stability will be compromised. If there are defects in the rim, the area of interface contact will be diminished and stability compromised. Cups with a true hemispherical design have a greater area of rim interface contact than "low-profile" cups and are therefore more stable. 1 mm undersizing of the cavity (or 2 mm undersizing in less dense substrate) appears to provide optimal stability.

Acetabulum↗
PubMed1992

Wrist anatomy.

The multiple joints within the wrist form a complex structure capable of transmitting significant loads to the upper extremity while providing a mobile base for the precision movements of the hand. This duality is accomplished through a fine interplay between the carpal bones and an arrangement of highly specific ligamentous structures, a system loaded by balanced muscle forces.

Biomechanical Phenomena↗
PubMed1991

Cementless total knee arthroplasty in patients with inflammatory arthritis and compromised bone.

Patients with bone compromised by inflammatory arthritis and medications are often excluded from cementless total knee arthroplasty (TKA) because of concerns regarding implant fixation and ingrowth. However, many such patients are young and at long-term risk for implant failure no matter what the fixation technique. Improved implant designs and technique may improve results. Cementless arthroplasty was performed in 45 patients with inflammatory arthritis. There were 38 patients with 53 implants available for follow-up evaluation during a 2- to 6.4-year period (average, 3.3 years). Medications included steroids (16 patients), nonsteroidal antiinflammatory drugs (36 patients), and cytotoxic agents (12 patients). Twenty-nine patients were using at least two types of medication. Prostheses included the Tricon P, Tricon M, Miller-Galante, and Anatomic Modular Knee (AMK) prosthesis. The procedures were performed using standard ligament-balancing techniques. Tibial resections were within 1 cm of the tibial plateau, thereby necessitating extensive bone grafts in ten patients. Tibial components were chosen for maximal cortical rim contact. Roentgenograms were reviewed for alignment, tibial rim contact, radiolucencies, gaps, sclerosis, and subsidence. Patients with no evidence of gap or lucency had spot films under image control. Hospital for Special Surgery knee scores averaged 47 preoperatively and 88 at follow-up examination. Alignment was from 3 degrees valgus to 9 degrees valgus (average, 6 degrees valgus), with a tibial axis of 0 degrees +/- 2 degrees. Plateau coverage was within 2.4 mm (average) of the cortical rim in all planes in the anteroposterior (AP) and lateral views. Tibial sclerosis occurred with equal frequency in all AP zones and was present equally in anterior and posterolateral zones. Gaps and lucencies were more common laterally. Fifteen femoral components showed a disturbing, localized osteopenia. Sclerosis, gap, and lucency were most common anteriorly. Cementless TKA with appropriate technique can produce results comparable to cemented surgery in patients with bone quality compromised by inflammatory arthritis, steroids, and nonsteroidal and cytotoxic agents. The femoral bone response suggests an intimate bone implant relationship. The tibia shows little direct coupling of prosthesis to bone. These responses are similar to reports from other studies. Fixation is sufficient to allow for continued analysis over time and results are encouraging.

Adult↗
PubMed1990

Treatment of trigger finger by steroid injection.

A retrospective study of 235 patients with 338 primary trigger fingers determined the efficacy and safety of steroid injection. Initial treatment consisted of one to three injections of corticosteroid mixed with local anesthetic. Those fingers that failed injection therapy had conventional release of the first annular pulley. Seventy-seven percent of all fingers showed resolution or improvement; 49% after a single injection, 23% after two injections, and 5% after three injections.

Adolescent↗
PubMed1990

Analysis of removed autophor ceramic-on-ceramic components.

Six Autophor alumina ceramic total hip arthroplasty components (5 removed for stem loosening and 1 for cup loosening) were evaluated to determine the nature and extent of wear by direct measurement, scanning electron microscopy of wear debris, and histology. Component implantation averaged 29 months (range, 8-54 months). All components had evidence of marked wear, including gross loss of material, which increased with the duration of implantation.

Adult↗
PubMed1990

Femoral shaft fracture in porous and press-fit total hip arthroplasty.

Press-fit and porous femoral components for total hip replacements are currently designed for aggressive canal filling. The bulk of the implants and their manner of insertion have created new femoral fracture problems in hip arthroplasty. Sixteen femoral fractures occurred in a series of 79 press-fit or porous arthroplasties in 72 patients. All cases in this report were reviewed through the period of fracture healing. The fractures were classified as follows: type I, at the neck medially, or proximal to the isthmus laterally; type II, running in a spiral oblique pattern from the stem tip; type III, originating in stress risers in the femoral shaft; and type IV, miscellaneous unclassifiable fractures. All fractures healed, leaving painless hips (Harris hip score average, 84). Collared implants are recommended in proximal fractures to protect against acute subsidence due to a wedging mechanism.

Adolescent↗
PubMed1990

The management of vascular injuries associated with total hip arthroplasty.

Approximately 100,000 total hip reconstructions are done annually in the United States. The nature of the surgical technique in a field close to the iliac and femoral vessels makes the occurrence of vascular injury an occasional but serious complications. We have reviewed retrospectively our experience of five cases of vascular injuries with total hip replacement and an additional 63 cases in the literature to identify those patients at risk and to define the management of these injuries. For the entire group of 68 patients, most injuries were sustained on the left side (66%), and 39% were seen in revisions. Complications were related to cement incorporation of the iliac vessels (44%), aggressive medial retraction (17%), excessive traction on atherosclerotic vessels (10%), and improper technique in preparation of the acetabulum. The most commonly injured vessels were the external iliac artery (36), common femoral artery (17), and external iliac vein (6). Twenty-seven of these injuries required emergent surgery, most for hemorrhage (66%). Injuries consisted of thromboembolic complications leading to distal ischemia (46%), vessel lacerations (26%), pseudoaneurysms (25%), and arteriovenous fistulas (3%). Vascular repair was individualized and included suture repair, thrombectomy and patch angioplasty, embolectomy, and arterial and venous bypass procedures. There was an overall 7% mortality and a 15% incidence of limb loss. Risk factors include (1) revision procedures, (2) left-sided procedures, and (3) intrapelvic migration of the acetabular component of the hip prosthesis. Elective vascular workup and preliminary retroperitoneal exposure of the iliac vessels at time of hip arthroplasty is recommended for patients at risk.

Aged↗
PubMed1988

Unusual fragment displacement in a distal radius fracture.

A 25-year-old man sustained a closed comminuted intra-articular fracture of the distal radius. Tomography showed 180 degree rotation of a palmar medial articular fragment. This rare injury is mentioned only once in the literature. When recognized, open reduction and internal fixation are necessary.

Adult↗
PubMed1988

Technical note: a modified Harris trochanteric reattachment technique.

A trochanteric reattachment technique which does not penetrate the femoral canal with wire has been developed for use in revision surgery or with press-fit implants. This technique was shown by in vitro mechanical testing to be comparable in stability to the standard Harris trochanteric reattachment method. It has been used successfully in 15 clinical cases.

Bone Wires↗
PubMed1986

Interscalene brachial plexus block anesthesia for upper extremity surgery.

Use of the interscalene brachial plexus block for upper extremity anesthesia in a primarily rheumatoid population is reviewed in 88 cases. The interscalene approach described by Winnie was used. Anesthesia was effective in 93% of the cases. Failure to achieve anesthesia was more likely to occur in surgical procedures on the distal upper extremities. The technique allowed effective and reliable anesthesia throughout the upper extremity, including the shoulder. Problems associated with other forms of upper extremity regional anesthesia, such as tourniquet pain, pneumothorax, systemic anesthetic toxicity, and inadequate duration of anesthesia, were not encountered. Difficulties with more distally based block administration due to decreased shoulder motion were obviated.

Anesthetics, Local↗
PubMed1986

Difficult acetabular revision. A preliminary report.

Thirteen patients (14 hips) underwent revision from conventional cemented total hip arthroplasty to uncemented acetabular threaded screw-in components and cementless femoral press-fit stems by means of the Autophor, Biofit, and Ti-Thread designs. The patients suffered from all forms of primary hip disease except rheumatoid arthritis; their average age was 34 years. The average preoperative Harris hip score was 39.4; the average postoperative score was 71.2 at six months, 90.6 at one year, and 91.6 at two years. Complications included two femoral shaft fractures, one femoral nerve palsy, and one dislocation. No signs have been observed of loosening or migration as of an early (6-24 months) follow-up.

Acetabulum↗
PubMed1985

Results of total knee replacement using an uncemented tibial component.

Fourteen patients (16 knees) underwent total knee arthroplasty with a noncemented tibial component. Clinical evaluation at one year and two years showed a level of function and pain relief comparable to that reported in studies of cemented prostheses. Radiographic studies demonstrated evidence of active bone implant consolidation.

Aged↗
PubMed1984

Stiffness of small-bone external fixation methods: an experimental study.

A variety of small-bone external fixation methods were evaluated to determine bending and torsional stiffness. Several methods of external pin stabilization with bone cement and with a commercial device were used. Among experimental variables examined were: the number of pins, pin diameter, pin length, pin spacing, and pin threading. The most rigid fixation was achieved with four pins held with a wire-reinforced bone cement fixator. Pin diameter was the most significant variable in the determination of stiffness with this configuration.

Animals↗
PubMed1983

Chemical, microscopic, and ultrastructural characterization of the mineral deposits in tumoral calcinosis.

The presence of hydroxyapatite has been determined based on ultrastructure, X-ray diffraction, electron diffraction, and chemical analysis, and confirmed by microprobe analysis in multiple deposits surgically excised from four unrelated patients with tumoral calcinosis. The chemical composition of each of the mineralized deposits resembled bone, rather than dermis, in mineral, uronic acid, total lipid, and complexed acidic phospholipid composition. No collagen abnormalities were detected. However, all of these deposits differed from normal bone mineral, being heavily mineralized and containing larger, more perfect hydroxyapatite crystals. Ultrastructurally, the crystals were both extracellular and within mononuclear cells in close proximity to dilated rough endoplasmic reticulum.

Adolescent↗
PubMedDate not supplied

Early experience with the Autophor prosthesis using a posterior approach.

Twenty-eight Autophor hip prostheses have been implanted in 25 patients, using primarily a posterior approach. Complications have included two dislocations and two femoral shaft fractures. One dislocation required reoperation. The shaft fractures healed in three months with bone grafting and cerclage wiring. There were no infections and no cases of loosening or component failure. Radiological follow-up including bone scan suggests implant boney stabilization at six months. Our early experience suggests that this implant is quite successful, especially in the young patient and the patient with significant loss of bone stock from protrusio or revision surgery.

Adult↗