A comparison of the effects of prosthetic and commercially pure metals on retrieved human fibroblasts: the role of surface elemental composition.

The most common clinical cause of long-term failure in total joint replacement surgery is inflammatory aseptic osteolysis; a condition in which bone surrounding the prosthetic implant, and to which the implant is attached, is resorbed, rendering the artificial device loose and painful. Historically, the severity of this bone resorptive process has been thought to be predominately attributed to the size and shape of wear-debris particles, particularly the metallic particulates that interact biologically/immunologically with cells in the joint. Because the cytotoxic reactions are the result of interactions between the cells and the surfaces of the particulates, it is not clear in the realm of orthopedics to what extent different surface stoichiometric ratios contribute to instigating bioreactive or cytotoxic cellular responses that can lead to aseptic osteolysis. Using energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), this study presents data and analyses concerning the respective bulk and surface stoichiometric ratios of two commercially pure metal micro-particulates (tantalum and titanium), two prosthetic F75 cobalt-chromium-molybdenum alloy micro-particulates, and prosthetic F136 titanium-aluminum-vanadium alloy micro-particulates, each containing elements common to total joint replacement surgery. Cell culture viability data from four volunteer donors are also presented, which suggest that micro-particulates containing large percentages of surface titanium and aluminum can cause moderate cellular toxicity, and micro-particulates containing large percentages of surface cobalt can result in extremely severe cellular toxicity. This work further suggests that surface analysis techniques, such as XPS, are essential to determine surface elemental characterization of metallic materials prior to interpreting cellular response results.

Differences in the surface composition of seemingly similar F75 cobalt-chromium micron-sized particulates can affect synovial fibroblast viability.

We present data and analyses concerning the cytotoxicity and bioreactivity associated with the surface composition of fine metal particulates that are similar to those commonly released in the body by prostheses used in total joint replacement surgery. Here we study the bulk and surface compositions of three separately procured cobalt-chromium-molybdenum (CoCrMo) micron-sized particulate powders, each identified by their corresponding vendor as being ASTM F75 grade material. We use energy dispersive spectroscopy (EDS) to verify the bulk metallic composition and X-ray photoelectron spectroscopy (XPS) to examine the surface metallic composition of each CoCrMo powder. Cultured synovial fibroblasts were then exposed to the particulate powders to see how the metallic surfaces might affect cellular viability. Results indicate that while the bulk metallic composition of each CoCrMo powder was similar, the surface metallic compositions were found to be dramatically different and yielded equally dramatic differences in terms of cytotoxicity and bioreactivity of synovial fibroblast in culture.

An introduction of various spectroscopic methods to identify in vivo metal wear in total knee arthroplasty.

While the industrial community already employs multiple surface analytical techniques to study compositional wearing of various metallic and nonmetallic materials, as yet, these methods have not been widely introduced into the biological community. We report on a novel approach, using the industrial spectroscopic techniques of X-ray photoelectron spectroscopy, micro-Raman spectroscopy, and scanning electron microscopy equipped with energy dispersive spectroscopy, to identify the fine wear particulates and other impurities deposited within the knee-joint following total knee arthroplasty. In this study, synovial fluid was extracted from knee-joints scheduled for revision of total knee arthroplasty. The small debris flake formed by centrifugation of the fluid was analyzed using the spectroscopic techniques mentioned above. These nondestructive techniques were successful in identifying numerous micron and submicron sized metallic particulates that appear to emanate from both the prosthetic bearing (articulating) surfaces and from backside (nonarticulating) surfaces, even when gross wearing of the prosthetic device was not detectable by direct visual inspection intraoperatively. Most interesting is that the ratio of the in vivo metallic debris is approximately the same ratio as that of the manufactured alloy, indicating prosthetic wearing as opposed to chemical dissolution. More importantly, using these spectroscopic techniques to probe both the surface and below the surface of the synovial deposits, we identify an inhomogeneous distribution of the wear debris. This indicates the need to use multiple techniques in order to adequately identify the elemental composition of the prosthetic wear material.

Osteolytic indicators found in total knee arthroplasty synovial fluid aspirates.

Interleukin-1beta and tartrate resistant acid phosphatase concentrations in synovial fluid aspirates were examined to determine if they could be used as indicators of increased synovial inflammation and an osteolytic reaction in patients having total knee arthroplasty. Synovial aspirates were obtained from seven patients with severely osteoarthritic knees that were scheduled for primary total knee arthroplasty and from 20 patients with knees scheduled for total knee arthroplasty revision. Eleven of the revision cases involved titanium alloy prostheses and nine involved cobalt chrome alloy prostheses. The interleukin-1beta and tartrate resistant acid phosphatase concentrations were obtained and compared between the group having primary total knee arthroplasty and the group having revision total knee arthroplasty. The knees having revision surgery had higher concentrations of interleukin-1beta and tartrate resistant acid phosphatase than did the knees having primary total knee arthroplasty. These results indicate a greater inflammatory and osteolytic response in knees having revision surgery. Although the osteoarthritic knees and the knees needing revision surgery in this study are considered to have an inflammatory state, it was only after total knee arthroplasty when particulate wear debris would be present that appreciable concentrations of interleukin-1beta and tartrate resistant acid phosphatase were produced.

In vitro response of human fibroblasts to commercially pure titanium.

The generation of metal particles through surface wear of prosthetic joints has been associated with biological reactions that may lead to prosthetic component loosening. The role of the macrophage in these reactions has been studied extensively, but that of the fibroblast has not. The few fibroblast studies that there have been have shown that particles of several metals, with sizes over a wide range, can promote cytokine release and may cause cell necrosis. The intent of this study was to determine if there are metal particle exposure threshold levels that result in morphological changes and cell necrosis of fibroblasts in peri-articular tissues. Retrieved human fibroblasts (superior medial plica) were cultured in standard fashion and then were exposed to various particle dosages of commercially pure Titanium (cpTi). Cell morphological changes and necrosis were observed to occur when the total mass of the particle dosage exceeded a threshold level. These data imply that these cell responses occur at threshold levels of wear particle exposure.

Medical and financial aspects of same-day bilateral total knee arthroplasties.

In this retrospective study, we compared forty-five patients who had undergone same-day bilateral total knee arthroplasties with 144 patients who had undergone unilateral total knee arthroplasty procedures. All procedures were performed by a single surgeon using a single prosthetic design between June 1994 to May 1996. The issues studied were the length of hospital stay, hospital charges, units of blood transfused, units of homologous blood transfused, and the rate and type of complications. This study also examined the usage and financial charges of extended care facilities and/or home health care following discharge from the hospital. Results show that, for patients suffering from symptomatic bilateral knee disease, the same-day bilateral total knee procedure is significantly less costly than staged bilateral procedures. The rate and type of complications seen in the same-day bilateral cases were not significantly different from complications seen in unilateral cases.

Quadriceps femoris function during knee extension following total knee arthroplasty.

Electromyographic signals (EMG) from surface electrodes over the vastus medialis, rectus femoris and vastus lateralis were monitored during isometric knee extension for 10 TKA patients and 6 control subjects. No significant side-to-side differences in normalized EMG signals from any of the monitored muscles were found when the left and right legs of the control group were compared or when the operative and the non-operative legs of the patient group were compared. However, both the operative and the non-operative legs in the patient group differed significantly (p < 0.01) in normalized EMG from the control group. This study has shown that a muscle imbalance, possibly leading to patellar tracking problems, does not routinely exist following TKA through a medial parapatellar incision.

Response of human fibroblasts to tantalum and titanium in cell culture.

The loosening of total joint arthroplasties (TKA) with associated osteolysis has been a persistent problem in orthopaedics. Wear debris from prosthetic devices including Titanium (Ti) is involved in this process. Mechanisms for this osteolytic process are unclear. The purpose of this study was to compare the biological response of Ti and Tantalum (Ta) on retrieved human fibroblasts. Fibroblasts were retrieved from human volunteers and cultured using standard techniques. Twenty-five (25) ml culture flasks were seeded with cells and when reaching confluency four concentrations of Ti and Ta were added. Their mean size was less than 3 microns for both metals and gram weights were 0.0048. 0.0096, 0.048, and 0.096 gms. After ten (10) days the cells were fixed, stained and photographed. For both Ti and Ta, the lowest concentration had little effect on the cells, while at the two higher concentrations, nearly all of the cell were killed. Since both of the metals tested are considered to be inert with respect to toxicity, these results would suggest that the observed cell death, seen equally for both metals, was due to the size and concentration of the particles and not to the metals tested. Mechanisms are currently being investigated which include mechanical as well as chemical factors.

A comparison of interleukin-1 beta in human synovial fluid of osteoarthritic and revision total knee arthroplasty.

Interleukin-1 beta levels from synovial aspirates were examined to determine if they can be used as indicators of increased synovial activity and an inflammatory reaction within total knee arthroplasty. Synovial aspirates were obtained from twelve osteoarthritic knees scheduled for total knee arthroplasty and twenty-one knees scheduled for total knee revision. Eleven of the revision cases involved titanium alloy prostheses and ten involved cobalt-chrome prostheses. Using a high sensitivity ELISA test kit, the interleukin-1 beta concentrations were compared. A significant difference in the interleukin-1 beta concentration was found between all three knee groups. The knees scheduled for revision surgery showed higher concentrations of interleukin-1 beta than osteoarthritic knees. While the knees implanted with a titanium prosthesis showed the greatest concentration of interleukin-1 beta, the osteoarthritic knees showed the lowest interleukin-1 beta concentration. Furthermore, significantly greater synovial aspirate volumes were obtained from the revision cases than from the osteoarthritic cases. This increased synovial activity is most likely attributed to the high concentration of the particulate wear debris produced from the prosthesis.

The use of postoperative suction drainage in total hip arthroplasty.

Two hundred eight primary total hip arthroplasties were reviewed to evaluate the effect of closed suction drainage. This review included 45 hips in which closed drains were used and 163 hips in which drains were not used. These two groups were compared for possible differences in wound problems, temperature elevations, changes in Hgb/Hct, and the need for transfusions. There was no statistically significant difference in postoperative temperatures or decrease in Hgb. However, there were four superficial wound infections in the drained group and three superficial wound infections in the non-drained group (P < .025). There were no deep infections in either group. These findings suggest closed suction drainage provides no apparent advantage in uncomplicated primary total hip arthroplasty.

Isokinetic lifting strength and occupational injury. A prospective study.

One hundred seventy-one nurses had their back strength evaluated on an isokinetic lifting device and filled out an epidemiologic questionnaire. They were then followed prospectively for 2 years to determine the incidence of job-related low-back injuries. The data were analyzed to determine if the injury incidence correlated with any of the strength or epidemiologic variables collected during the original evaluation. Average peak force measured during the isokinetic lift was 63.8 kg + 13.6 kg at a lift speed of 30.5 cm/sec and 59.1 kg + 14.9 kg at a lift speed of 45.7 cm/sec. Sixteen nurses reported an occurrence of job-related low-back pain or injury during the 2-year prospective period. Discriminate statistical techniques showed that none of the strength or epidemiologic variables correlated with the incidence of pain or injury or explained significant amounts of variance when the variables were regressed on strength or work calculated from the lift force/lift height data. It was concluded that in this high risk population, in which loads are heavy and lifting postures are variable, the use of low-back strength or prior history of pain or injury are poor predictors as to subsequent low-back pain or injury.