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Biomedical subjects

J M Cuckler

Publications and source records attributed to J M Cuckler.

At least 19 recordsLinked to original sources
PubMed2001

Short-term results of the M2a-taper metal-on-metal articulation.

A polyethylene-free, metal-on-metal acetabular system (M2a-taper [Biomet, Inc., Warsaw, IN]) was designed in an effort to improve total hip arthroplasty (THA) longevity. Minimum 2-year follow-up results involving 72 polyethylene liner THAs and 78 metal liner THAs from a multicenter, randomized, controlled, investigational device exemption study are reported. Mean Harris hip scores of 95.54 (polyethylene liner group) and 95.23 (metal liner group) were reported at mean follow-up intervals of 3.29 and 3.23 years. Radiographic evaluation revealed no evidence of early failure. No acetabular components have been revised or are pending revision. No statistically significant differences in the data were calculated between liner types except for the immediate postoperative (P=.0415) and minimum 2-year follow-up (P=.0341) angles of inclination. The M2a-taper metal-on-metal articulation may represent a viable alternative for THA in younger, higher demand patients.

Adolescent↗
PubMed2001

Dealing with post-traumatic arthrosis of the hip.

The conversion of the arthritic post-traumatic hip may be more similar to revision surgery than routine primary hip replacement. Careful preoperative planning and templating is essential. Soft-tissue balance to produce stability is challenging, and patients may need bracing with a THR orthosis postoperatively to assure soft-tissue healing and stability. Acetabular bone stock may be significantly compromised, and the preoperative identification of bone stock deficiencies may not always be possible. The surgeon should be prepared with adequate allograft, acetabular reconstruction rings, and alternative procedures such as fusion or resection arthroplasty in these challenging cases.

Hip Dislocation↗
PubMed1998

Flow intrusion characteristics and fracture properties of titanium-fibre-reinforced bone cement.

Two clinically relevant considerations for a new bone cement are its fracture properties and flow intrusion characteristics. We present data for a titanium-fibre-reinforced poly(methyl methacrylate) (Ti-PMMA). The fracture properties presented are a concise review of previously published material, while the flow intrusion observations are new. We performed fracture toughness and fatigue fracture experiments. Two types of fatigue specimens were designed and tested. A 'smooth' specimen represented the extreme case of minimum surface flaws. The lifetime of a 'smooth' specimen incorporates fatigue crack initiation (FCI) and fatigue crack propagation (FCP). 'Notched' specimens were created by machining a sharp notch into cylindrical specimens. The sharp notch effectively eliminated FCI from a random surface flaw and thus we made the assumption that the lifetime of the notched specimen was a function of FCP only. Fatigue testing was performed on rotating-bending fatigue machines until failure. Fibre addition resulted in a significant increase in fracture toughness over the control bone cement. Fibre addition and the combination of fibre addition and centrifugation increased the fatigue crack initiation and propagation resistance of the bone cement. For the intrusion studies, eight femurs were obtained from four dogs. The femurs were prepared following a procedure similar to that in human hip replacement surgery. One of the pair of femurs from each dog was filled with non-reinforced bone cement and the other was filled with Ti-PMMA. A stainless-steel rod was inserted into the cement to simulate the insertion of a prosthesis stem. The cemented bones were sectioned and then stained with Alizarin Red S to distinguish the bone from the PMMA or Ti-PMMA. Because of the irregular bone morphology, it was not practical to quantify intrusion depth, but instead to make general observations on the intrusion characteristics. The Ti fibres did not generally flow into the small openings; however, fibre addition did not hinder the bone cement's ability to penetrate into bone interstices.

Animals↗
PubMed1997

Calcium phosphate ceramic coatings as carriers of vancomycin.

Infection in the setting of total joint arthroplasty remains a challenging problem. Attention has turned to developing methods of local delivery of antibiotics for prophylaxis. Vancomycin loaded into calcium phosphate ceramic coatings on titanium alloy substrates is a clinically relevant concept in the setting of total joint arthroplasty. Drug loading was accomplished by immersion of ceramic-coated discs in vancomycin-containing simulated physiological solution; in some experiments drug loading by immersion was followed by lipid coating in egg phosphatidylcholine solutions. The kinetics of vancomycin release and the efficacy of drug inhibition of Staphylococcus aureus were determined in vitro in comparison to the release from currently used antibiotic-laden poly(methyl methacrylate) (PMMA). The loading by immersion provided effective release and inhibition at early time points (up to 24 h); however, the lipid-coated samples demonstrated significant release and effective bacterial inhibition up to 72 h. The two-step procedure, i.e. drug loading followed by lipid coating in order to slow antibiotic elution, is more effective than the conventional one-step loading. The study indicated that the osteoconductive calcium phosphate coatings have the potential to serve as drug carriers to prevent infection in the setting of total joint arthroplasty.

Alloys↗
PubMed1997

Systemic titanium levels in rabbits with a titanium implant in the absence of wear.

All non-noble metals and alloys will release metallic species into the body. This raises the issue of amount and fate, i.e. transport and storage, of these metal dissolution products. For titanium, the nature and extent of these systemic effects remain mostly unknown. In this study we investigated titanium levels in alleged target tissues in rabbits, both with and without a titanium implant functioning in the absence of wear, and compare these results to the limited body of literature concerning systemic levels of titanium. Titanium fibre felts were implanted into the tibia of rabbits. At various time points, lung, spleen, and muscle samples were collected from these rabbits as well as two groups of control rabbits. The samples were analysed for titanium concentration using electrothermal atomic absorption spectrophotometry. The data for the implant groups show that titanium levels in these tissues do not increase in comparison with controls up to 1 y after implantation.

Journal Article↗
PubMed1997

Orderly oriented wire mesh: a novel porous coating.

As an alternative to commercially available porous beads and fiber metal mesh, a new porous coating, orderly oriented wire mesh (OOWM), was developed. Rectangular plugs, 10 x 5 x 5 mm with porous-coated beads, and four different OOWM configurations were inserted into bilateral femoral condyles of adult beagles. Dogs were sacrificed immediately after implantation, and at 4 weeks, 8 weeks, and 12 weeks postimplantation. Mechanical pullout strength of plugs revealed that porous beads are equivalent to the simplest OOWM at 12 weeks postimplantation. Of the four OOWMs tested, the 25 x 25 single layer was significantly more stable than others at 4 weeks postimplantation. These results indicate that in an in vivo unloaded model, OOWM is just as effective as the porous beads in achieving early bone ingrowth and stability.

Animals↗
PubMed1996

Local accumulation of titanium released from a titanium implant in the absence of wear.

Titanium and its alloys, like the majority of metallic implant materials, release passive metal dissolution products. This raises the issues of amount and fate, i.e. transport, storage, and/or excretion of these metal dissolution products. In this paper we document titanium levels in tissues local to a commercially pure titanium implant in the absence of wear; compare these values to control tissues; and determine the relative contribution of the local accumulation to total release. Titanium fiber felts were implanted into the tibia of rabbits for periods up to 1 year. Bone and muscle tissue samples near the implant were collected. Using electrothermal atomic absorption spectrophotometry the samples were analyzed for titanium content. Compared to controls, titanium levels in the bone near the implant were elevated at 1-, 4-, and 12-month postoperative time points. The 12-month time point had higher periprosthetic bone titanium levels than both the 1- and the 4-month implant groups. Titanium levels in muscle tissue near the felt also indicated release was occurring. The data support the hypothesis that metal species released from titanium implants in the absence of wear have a limited solubility. As a result, they tend to remain in an area local to the implant.

Analysis of Variance↗
PubMed1996

Titanium serum and urine levels in rabbits with a titanium implant in the absence of wear.

Although devices made of titanium and its alloy with 6% aluminium and 4% vanadium have been remarkably successful primarily in orthopaedic and dental applications, clinical reports have implicated the biological response to released metal from this class of metals as a cause of failure. It is our hypothesis that in the absence of wear, the amount of titanium released is small and will preferentially accumulate in local tissues. One important implication of this is that measurable quantities of titanium in serum and urine that have been observed in clinical studies result from mechanically induced or assisted release phenomena. In order to test this hypothesis, titanium levels in various tissues and fluids of animals both with and without titanium implants need to be determined. In this paper, we report the titanium concentration in serum and urine of rabbits in the absence of wear. Titanium fibre felts were implanted into the tibia of rabbits. At various time points, serum and urine samples were collected from these rabbits as well as from two groups of control rabbits. The samples were analysed for titanium concentration using electrothermal atomic absorption spectrophotometry. The data for the implant group show that titanium levels in serum and urine do not increase in comparison to controls up to one year after implantation. Some clinical studies have documented elevated titanium serum and urine levels in the presence of titanium-based prostheses. The different results from these studies can be resolved by considering titanium release mechanisms other than passive dissolution.

Analysis of Variance↗
PubMed1996

Initial stability of a modular uncemented, porous-coated femoral stem: a mechanical study.

A versatile modular hip system was used to evaluate the initial stability of a cementless femoral stem in anatomically consistent composite bones. Four implant bone configurations of varying proximal and distal fit/fill were tested. The implanted femurs were tested on an Instron 1331 materials testing machine in neutral loading and flexion loading; both translational micromotions and rotations of the implant relative to the bone were recorded on all three axes of motion, accounting for all 6 degrees of freedom of joint motion. Implants were then sectioned, and both endosteal canal fit and intramedullary canal fill were measured. Results indicate that (1) loading the implant in flexion by out-of-plane forces significantly increases both relative translation and rotation at the interface, (2) increasing the proximal fit reduces implant rotation about its longitudinal axis in flexion loading and (3) increasing the distal canal fit and fill increases prosthesis rotation about its longitudinal axis in flexion loading. These results indicate that the femoral stem is more unstable in out-of-plane loading, such as during stair climbing, and that increasing the proximal fit may enhance the initial rotational stability of an uncemented femoral stem.

Biomechanical Phenomena↗
PubMed1995

The effects of centrifugation and titanium fiber reinforcement on fatigue failure mechanisms in poly(methyl methacrylate) bone cement.

The contributions to fatigue resistance in poly(methyl methacrylate) bone cement (PMMA) by centrifugation and titanium fiber addition were studied. Three modified bone cements were tested: porosity reduced cement (C-PMMA); titanium (Ti) fiber-reinforced cement (R-PMMA), using a novel method to incorporate fibers; and porosity reduced and Ti fiber-reinforced cement (C-R-PMMA). Specimens of untreated bone cement (PMMA) were included as controls. Non-notched and notched specimens were cyclically loaded in fully reversed bending. For the non-notched specimens, at all stress levels, C-R-PMMA had significantly greater fatigue life than either C-PMMA or R-PMMA (except C-PMMA at 30 MPa). R-PMMA had lower fatigue life than the control at 30 MPa (nominal maximum stress), but higher fatigue life at 20 and 15 MPa. At both 20 and 15 MPa, there was no statistical difference between the fatigue lives of C-PMMA and R-PMMA. Fractography revealed that, at 30 MPa, characteristics of rapid fracture predominated. At 20 and 15 MPa, in contrast, almost the entire fracture surface showed the characteristic fatigue morphology, indicating that subcritical crack growth was predominant. For the notched specimens, C-PMMA showed greater life than PMMA at the highest stress intensity, but the lifetimes converged with decreasing stress intensity. In contrast, the life-times for PMMA and R-PMMA diverged with decreasing stress intensity. The effect of centrifugation appeared to be strongest at higher stress intensities, and diminished with decreasing stress intensity. The reinforcing effect of Ti fiber addition increased the notched fatigue life at high initial stress intensities, and the reinforcing effect increased with decreased stress intensity.(ABSTRACT TRUNCATED AT 250 WORDS)

Biocompatible Materials↗
PubMed1995

Revision total knee arthroplasty: how much constraint is necessary?

The majority of revision total knee arthroplasties will achieve sufficient stability with a posterior stabilized design. However, when partial compromise of the medical collateral ligament is encountered, enhanced stability should be achieved with the use of a CCK device. Rarely, hinged designs will be necessary as salvage procedures for low demand patients. The principles of total knee arthroplasty stability, as in primary surgery, require an anatomic alignment of the extremity, proper alignment of the prosthetic components, and physiologic symmetry of the collateral ligaments in both flexion and extension to assure a successful result.

Follow-Up Studies↗