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Biomedical subjects

M D Ries

Publications and source records attributed to M D Ries.

At least 19 recordsLinked to original sources
PubMed2001

Infection after total joint arthroplasty in patients with human immunodeficiency virus or intravenous drug use.

Patients with intravenous drug use (IVDU) and patients with human immunodeficiency virus (HIV) with painful joint arthrosis present a difficult treatment decision. The purpose of this study was to determine the rate of deep periprosthetic infection in patients with HIV or IVDU after total joint arthroplasty (TJA). Twenty-nine patients with HIV or a history of IVDU or both underwent TJA. Of 28 HIV-positive patients undergoing TJA, 4 (14%) developed infections. Two of 8 joints (25%) in the IVDU group developed an infection. Two of 5 joints (40%) with both IVDU and HIV developed a deep infection. Patients with HIV or a history of IVDU are more likely to develop a deep infection compared with other patients undergoing TJA. The decision to proceed with TJA in HIV-positive and IVDU patients should be made only after weighing the ratio of risks and benefits.

Adult↗
PubMed2001

Vancomycin-resistant Enterococcus infected total knee arthroplasty.

Use of vancomycin to treat infections and hospital colonization with methicillin-resistant Staphylococcus aureus has contributed to the development of vancomycin resistance in Enterococcus. Postoperative infection with vancomycin-resistant Enterococcus developed in 2 patients after total knee arthroplasty, indicating that the infections were nosocomial. Both patients required multiple procedures. The infections were controlled with serial open débridements. One knee was fused successfully, and the other was managed with resection arthroplasty.

Adult↗
PubMed2001

Relationship between gravimetric wear and particle generation in hip simulators: conventional compared with cross-linked polyethylene.

Hip-simulator studies have shown reduced gravimetric wear rates for inert-gas gamma-irradiated ultra-high molecular weight polyethylene when compared with conventional ethylene-oxide-sterilized ultra-high molecular weight polyethylene. Analysis shows a greater number of particles generated from inert-gas gamma-irradiated ultra-high molecular weight polyethylene. This study was undertaken to examine particle-generation rates of polyethylene with different levels of cross-linking and to correlate them with gravimetric wear data. Particle-generation rates did not correlate with gravimetric wear rates. Particle analysis should be performed to predict the in vivo behavior of bearing surface materials. Cross-linked ultra-high molecular weight polyethylene subjected to 10 Mrad (100,000 Gy) of gamma irradiation generated significantly fewer particles than ethylene-oxide-sterilized ultra-high molecular weight polyethylene; it also demonstrated a 96% reduction in the volume of particles.

Hip Prosthesis↗
PubMed2000

Arthrofibrosis after total knee arthroplasty.

Six total knee arthroplasties in five patients were revised because of persistent limited motion after the primary arthroplasty. All of the revised implants were of an appropriate size and not malpositioned. No cause of stiffness was identified other than soft tissue contracture. Four of the components were posterior cruciate retaining and two were posterior cruciate substituting. Heterotopic bone formation was observed in two knees before the revision surgery and five knees after the revision surgery. Arc of motion was increased from 36 degrees (range, 20 degrees-70 degrees) before revision surgery to 86 degrees (range, 70 degrees-110 degrees) after revision surgery. What triggers the proliferation of extensive scar tissue formation in patients with arthrofibrosis is not clear. Some patients may be predisposed to this condition or may have it develop as a response to the surgical trauma and postoperative rehabilitation. However, when arthrofibrosis does develop after total knee arthroplasty, some improvement in motion and pain can be achieved with revision surgery.

Aged↗
PubMed1999

Failure of a metal-on-metal total hip arthroplasty from progressive osteolysis.

Ultra-high-molecular weight polyethylene (UHMWPE) wear, debris-induced osteolysis is a frequent cause of failure of total hip arthroplasty. Metal-on-metal total hip arthroplasty eliminates the generation of UHMWPE particulate debris. Although the volumetric wear of a metal-on-metal articulation may be lower than a metal-UHMWPE articulation, the number of particles may be higher. Osteolysis can develop in response to metallic and UHMWPE debris. The following case of massive osteolysis associated with large amounts of cobalt-chrome wear debris shows adhesive and abrasive wear mechanisms, as well as wear caused by third-body cobalt-chrome debris and impingement of the femoral component against the rim of the acetabular cup, which led to failure of a metal-on-metal total hip arthroplasty.

Aged↗
PubMed1999

An inexpensive molding method for antibiotic-impregnated cement spacers in infected total hip arthroplasty.

Placement of an antibiotic-impregnated cement endoprosthesis facilitates patient mobilization and treatment of infection complicating total hip arthroplasty. Molds, particularly to form the spherical head of the cement endoprosthesis, are not readily available, however. We have found that the rubber bulb portion of an irrigation syringe can be conveniently used as a mold to shape the proximal end of a cement endoprosthesis during surgery.

Anti-Bacterial Agents↗
PubMed1999

Photoelastic analysis of stresses produced by different acetabular cups.

Porous-coated acetabular components can provide long-term biologic fixation to bone. However, the periacetabular stress patterns and mechanisms by which different types of cementless acetabular cups obtain initial stability is not clear. In the current study, periacetabular stresses produced by different cementless acetabular cup geometries were quantitated using a three-dimensional photoelastic model. The cup geometries consisted of trispiked, finned, hemispherical, and nonhemispherical (wider than a hemisphere at the periphery) geometries. The cup models were loaded incrementally in the photoelastic material to simulate periacetabular stress distributions at the time of implantation during surgery rather than under physiologic weightbearing loads. The peripheral stress distributions and their magnitudes induced by the trispiked and oversized hemispherical cups were similar, but the trispiked cup induced localized high stress regions where the spikes penetrate the bone model. The fins separated the periacetabular material into quadrants, which was associated with decreased peripheral stresses. A nonhemispherical geometry with a wider diameter at the rim than a hemisphere increased peripheral stresses more than an oversized hemispherical geometry and required less force to seat the implant. Although various cementless acetabular cups can perform well clinically, they produce different periacetabular stresses and appear to obtain initial fixation by different mechanisms.

Acetabulum↗
PubMed1999

Simultaneous primary and contralateral revision total knee arthroplasty.

Seven patients underwent primary and contralateral revision total knee arthroplasty (TKA) under one anesthetic in a sequential fashion. The average patient age was 67.6+/-6.9 years. Average blood loss was 764+/-568 cc, average operative time was 269+/-107 minutes, and average length of hospital stay was 9.6+/-3.4 days. One patient with a history of hypertension, diabetes, and coronary heart disease died from pulmonary embolism 7 days after surgery. Deep infection with enterococcus developed in the revised knee of another patient 3 months after surgery. For the six surviving patients, knee pain and function were improved by surgery. However, in this small series of patients, two major complications occurred. These results indicate that if this procedure is considered at all, it should be reserved for only healthy patients with relatively uncomplicated knee reconstructions.

Aged↗
PubMed1998

Prophylactic intramedullary femoral rodding during total knee arthroplasty with simultaneous femoral plate removal.

Removal of a plate from the distal femur creates a risk of fracture through the screw holes. This is a particular concern when a total knee arthroplasty is present because supracondylar fracture may occur with minimal trauma. A patient who presents after prior plating of a distal femur fracture with osteoporosis, retained hardware associated with pain, and gonarthrosis severe enough to warrant total knee arthroplasty is often difficult to manage. Prophylactic intramedullary rodding is a well-accepted method of treating pathologic stress risers in the femur. An intramedullary rod can be inserted into the femur at the time of total knee arthroplasty. This method permits simultaneous plate removal and total knee arthroplasty while protecting the femur from postoperative fracture.

Bone Plates↗
PubMed1998

Endosteal referencing in revision total knee arthroplasty.

A method of orienting the femoral and tibial bone cuts relative to the endosteal cortex of the femur and tibia was used in 32 patients who underwent revision total knee arthroplasty. The mean orientation of the femoral component was 96.74 degrees +/- 1.03 degrees, mean orientation of the tibial baseplate was 90.71 degrees +/- 1.10 degrees, mean anatomic tibiofemoral alignment was 7.42 degrees +/- 1.69 degrees of valgus, and mean mechanical tibiofemoral alignment was 1.09 degrees +/- 1.83 degrees of valgus. Mean tibial bowing was 1.63 degrees +/- 1.57 degrees of valgus, and mean femoral bowing was 0.58 degrees +/- 1.53 degrees of varus. Valgus tibial bowing was correlated with valgus orientation of the tibial component (r = .86, P < .000001), and varus femoral bowing was correlated with orientation of the femoral component (r = .54, P = .0054). Referencing the implant position from the endosteal cortex of the intramedullary canals provides a reliable method of achieving satisfactory alignment in most revision total knee arthroplasties; however, bowing of the femur or tibia can affect alignment.

Arthroplasty, Replacement, Knee↗
PubMed1998

Intramedullary pressure and pulmonary function during total knee arthroplasty.

Twenty-eight patients who underwent unilateral total knee arthroplasty and 20 patients who underwent simultaneous bilateral total knee arthroplasties participated in this study and were randomized to have either a fluted or round 10-mm diameter femoral intramedullary alignment rod used during surgery. The intramedullary rods were cannulated and connected with pressure tubing to a monitor which provided measurements of pressure at the tip of each rod. Arterial blood gas measurements on room air were obtained before and on the morning after surgery. An arterial line was placed and an arterial blood gas measurement was obtained at the time of skin incision and again after tourniquet release. Pulmonary shunt was calculated from the arterial blood gas measurements. Intramedullary pressure during rod insertion was significantly higher for the groups of patients having the round compared with the fluted rod. The change in pulmonary shunt during surgery was lowest for the patients in the unilateral group having the fluted rod and highest for the patients in the bilateral group having the round rod. A fluted rather than a round intramedullary alignment rod should be used to minimize intramedullary pressure and pulmonary shunting during unilateral and bilateral total knee arthroplasties.

Analysis of Variance↗
PubMed1998

Factors affecting stability of press fit acetubular cups.

Press fitting cementless porous coated acetabular components without screw fixation is desirable to minimize debris-related problems. Compression between the bone and periphery of an acetabular component which is slightly larger than the reamed acetabulum provides implant fixation while oversizing at the dome may adversely affect stability. In most primary total hip arthroplasties, the acetabulum can be reamed to a hemispherical cavity and assessed using acetabular sizing trials prior to implanting the cup. Use of an implant with a hemispherical dome and gradual transition to a wider peripheral dimension maximizes peripheral bone strains and implant stability with less impaction force and overall deformation than a larger oversized hemispherical cup.

Journal Article↗
PubMed1997

Effect of total hip arthroplasty on cardiovascular fitness.

Thirty patients who underwent total hip arthroplasty and 18 patients with medically treated arthritis participated in this study. Both groups of patients underwent a cardiovascular fitness exercise test on entering the study and 6 months, 1 year, and 2 years later. Fitness was assessed by patient performance on a graded maximal exercise test using a bicycle ergometer and metabolic cart. In the group of total hip arthroplasty patients, significant improvements in exercise duration (P = .011), maximum workload (P = .0013), peak oxygen consumption (P = .0036), and percentage of predicted maximum oxygen uptake achieved (P = .0002) were observed during the follow-up evaluation. In the group of control patients, decreases in exercise duration (P = .0001), maximum workload (P = .0001), and workload at anaerobic threshold (P = .0108) occurred without a significant change in the other measures of cardiovascular fitness. The results indicate that resumption of routine physical activities after total hip arthroplasty is associated with a corresponding improvement in cardiovascular fitness.

Activities of Daily Living↗
PubMed1997

Effect of cementless acetabular cup geometry on strain distribution and press-fit stability.

Use of cementless acetabular cups, which are slightly larger than the reamed acetabulum, can provide press-fit stability without screws; however, the ideal cup geometry to maximize stability is not clear. Acetabular strain distribution, deformation, and implant stability were studied using an axisymmetric finite-element model, and mechanical stability was assessed by testing lever-out and extraction forces required to displace different cup geometries from foam bones. The implants tested included four nonhemispheric cup geometries and 1- and 2-mm oversized hemispheric geometries. A nonhemispheric cup that provides a gradual transition from a hemisphere at the dome to a larger peripheral dimension appears to maximize peripheral strains and implant stability without increasing overall acetabular deformation as much as a larger oversized hemispheric cup.

Acetabulum↗