Acetabular osteolysis in total hip arthroplasty: prevention and treatment

Osteolysis can occur around loose, as well as well fixed, cemented or cementless acetabular components in total hip arthroplasty. Histologic studies of tissues biopsied from osteolytic regions suggest an adverse foreign body response to polyethylene and other particulate debris from prosthetic materials. Phagocytosis of these particles by macrophages and giant cells stimulate the production of proteolytic enzymes and inflammatory mediators, all leading to tissue destruction. The importance of polyethylene wear debris is now fully appreciated, and it is clear that this is the major contributor to particulate debris. The authors strongly recommend the avoidance of 32 mm femoral heads, thin acetabular component liners, titanium heads, and acetabular screws when absolutely necessary. We strongly advise 26 mm to 28 mm femoral heads, polyethylene thickness of at least 8 mm, precise liner shell contact, rigid fixation of the acetabular metal shell, intimate bone-acetabular shell contact, and circumferential porous coating of femoral components to decrease the amount of and migration potential of polyethylene debris (Table). Based on our current knowledge, these measures will minimize the problem of acetabular osteolysis.     

Acetabular osteolysis and migration in bipolar arthroplasty of the hip: five- to 13-year follow-up study

Two factors potentially determining the consistent overexpression of sialyl-Le(x) antigen in colon carcinoma and metastases were investigated: (i) the expression of the mucins MUC1 and MUC2, known to carry sialyl-Le(x), by Northern blotting; (ii) the extent of sialic acid O-acetylation, by Western blotting and HPLC. RNA and sialyl-Le(x)-positive mucins were purified from normal colonic mucosa (N), primary carcinomas (T) and their liver metastases (M). Northern blots showed that mRNA expression both of MUC1 and of MUC2 decreases during the progression of the disease, and is lowest in metastatic tissue. The expression of mucin-bound sialyl-Le(x) increased strongly from N to T and, to a lesser extent, to M. After alkali treatment of the mucins these differences disappeared, indicating that the total amount of mucin-bound sialyl-Le(x) is the same in the 3 types of tissues. The O-acetylation of mucin-bound sialyl-Le(x) gradually decreased from N to M. HPLC analysis showed that in N about 70%, in T 45% and in M only 20% of mucin-bound sialic acids are O-acetylated. Thus, the increase of sialyl-Le(x) detectable during colon-carcinoma progression is due to diminished O-acetylation and not to increased expression of mucin protein cores. The decrease of O-acetylation is therefore the primary chemical alteration contributing to colon carcinoma-associated overexpression of sialyl-Le(x).     

Blood utilization in hip and knee arthroplasty: a cost-minimization study

The non-utilization of crossmatched blood is an expensive waste of resources. We have audited blood utilization for all primary total hip and knee arthroplasty patients. We compared routine pre-operative crossmatching (Phase 1) with a policy of group, screen and save (G & S) only (Phase 2). The patient groups were similar in both phases. Pre- and post-operative haemoglobin results were not significantly different between Phase 1 and 2. No adverse transfusion reactions occurred. In Phase 1, 213 units were crossmatched pre-operatively, but only 127 (60%) were transfused. In Phase 2, 117 units were requested and all transfused. The G & S only policy proved to be a safe and practical option which improved the efficiency and cost-effectiveness of blood ordering. Based on a handling charge of 37.50 Pounds per unit of blood by the Regional Transfusion Centre, an estimated annual saving of over 8000 Pounds can be made in our directorate.     

Dual energy x-ray absorptiometry of implanted femora after cemented and press-fit total hip arthroplasty in a canine model

Thiols, dialkylsulfides, and dialkyldisulfides are known to be chemisorbed with high affinity on gold. We have prepared DNAs of specific length and sequence carrying thiol groups at each end. For this purpose, primers with an HS-(CH2)6-arm at the 5'-end were used to amplify segments of plasmid DNA via the polymerase chain reaction. These thiolated DNAs bind strongly to the large, ultraflat Au surfaces which we have recently described [Hegner, M. et al. (1993) Surface Sci. 291, 39-46], and can be imaged by AFM in liquids (aqueous solutions or propanol). The lengths obtained in the AFM images are consistent with the DNA being in a native B-conformation.     

Migration and wear of hydroxyapatite-coated press-fit cups in revision hip arthroplasty: a radiostereometric study

Screw-fixated and hydroxyapatite-coated press-fit cups were studied using radiostereometry in 29 revision and 14 primary arthroplasties. The acetabular defects in the revision cases varied from none to type 3 (wall defects) according to Gustilo-Pasternak. Morsellized allograft was used in 25 revisions. Nine of these cups rested on less than 50% living bone. After 2 years, the mean migration in the revised group reached 0.36, 0.21, and 0.49 mm in the horizontal, longitudinal, and anteroposterior (AP) directions. The mean rotations varied between 0.5 degrees and 0.7 degrees depending on direction. The primary implants displayed smaller mediolateral migration and AP tilt. The mean proximal wear rate for the whole group was 0.11 mm/y. A central gap on the postoperative AP view implied less migration. The size of the preoperative bone defects or amount of bone-graft used had no influence on the migration. Despite extensive use of morsellized allograft, this implant displayed the smallest migration so far reported in revision hip arthroplasty.     

Histological and biomechanical analysis of bone and interface reactions around hydroxyapatite-coated intramedullary implants of different stiffness: a pilot study on the goat

We hypothesized that reduced stem stiffness of orthopaedic implants contributes to a high risk of loosening, since interface stresses and relative motions may exceed a tolerable range. To study this hypothesis, three types of load-bearing implant with different stiffnesses were inserted into the tibia of the goat. Histological analysis was performed of bone repair after insertion of the implant, bone ingrowth, interface disruption and loosening. A finite element model of the configuration provided the quantitative range of interface stresses and relative motions for the present experiment. The implants were made out of stainless steel, hollow titanium and a thin titanium core covered with a polyacetal coating. The stiffness ratios of these implants were approximately 10:4:1, respectively. All implants were coated with a layer of hydroxyapatite (HA) in order to minimize the possible biological effects of the different implant materials. Irrespective of the type of implant, there was a repair phase that lasted 6-12 weeks. The stiff implants functioned well. Large areas of bone bonding to the HA layer were found after the repair phase at 12 weeks postoperatively. After 24 weeks, some signs of loosening were observed. More loosening occurred with the hollow titanium and polyacetal implants, mainly during the repair phase. Three hollow titanium and three polyacetal coated implants survived this period, and were killed after 24 weeks. The integrity of the HA layer at the bone-implant interface of the titanium implants was good. In the polyacetal implants, the repair reaction of the cortical bone was incomplete. Bone ingrowth into HA was largely lacking. In conclusion, we found significant differences in the repair and interface reactions around implants of different stiffness. Stiff implants showed favourable initial interface conditions for bone ingrowth. Intermediate and flexible implants provoked unfavourable interface conditions for initial bone ingrowth. The finite element study showed that the flexible stems produce larger micromotions and higher interface stresses at the bone-prosthesis interface than the stiff stems, indicating an explanation for the histological findings.     

Compliance: a fundamental biomechanical property in the maintenance of an arterial reconstruction?

The Drosophila anachronism (ana) locus controls the proliferation of neuroblasts, neuronal stem cells that give rise to the central nervous system. In ana mutants, quiescent postembryonic central brain and optic lobe neuroblasts enter S phase precociously. ana encodes a novel secreted protein of 474 amino acids that is expressed not in the affected neuroblasts, but rather in a subclass of neighboring glial cells. These studies argue for an important role for glia in negatively regulating proliferation of neuronal precursor cells, thereby controlling the timing of postembryonic neurogenesis.     

Aseptic loosening of the femoral implant after cemented total hip arthroplasty in dogs: 11 cases in 10 dogs (1991-1995)

Aseptic loosening of the femoral implant (ALFI) was diagnosed in 10 dogs that had undergone cemented total hip arthroplasty (THA). One dog had bilateral ALFI. Loosening developed at the stem-cement interface a mean of 30 months after THA. The most common clinical sign was intermittent subtle or non-weight-bearing lameness. On radiographs obtained after THA, the distal stem tip was in contact with the cortical endosteum in all dogs. Radiographic changes at the time of diagnosis of ALFI included asymmetric periosteal reaction along the femoral diaphysis (n = 11), radiolucent zone at the stem-cement interface (6), altered implant position (4), and femur fracture (1). Surgical revision resulted in a good or excellent outcome in 9 dogs. In 1 dog, the implant became infected. In another, aseptic loosening recurred. Aseptic loosening of the femoral implant was significantly more common when initial positioning of the implant resulted in contact between the distal tip of the implant and cortical endosteum than when there was no contact.     

Quantitative measurement of joint space narrowing progression in hip osteoarthritis: a longitudinal retrospective study of patients treated by total hip arthroplasty

OBJECTIVES: To evaluate the rate of progression of radiological joint space narrowing (JSN) in patients operated on for hip osteoarthritis (OA) and to determine its predictive factors. METHODS: Study design: retrospective longitudinal trial of 61 patients who underwent total hip arthroplasty (THA) for hip OA (69 operated hips). Mean follow-up 81.2 +/- 9.9 months. Collected data: (1) standing frontal radiographs of the pelvis from diagnosis to surgery (246 films) for morphological evaluation and quantitative measurement of joint space width (JSW) (computerized reading of digitized X-rays); (2) demographic data (sex, age, body mass index, smoking status, professional and sporting activities, family history of OA); (3) clinical data (age at onset-diagnosis and THA, drug consumption, time from diagnosis to permanent disability, OA at other joints, previous THA of the contralateral hip). Statistics: multivariate analysis. RESULTS: The yearly mean narrowing (YMN) of MeanJSW was 0.43 +/- 0.43 mm/yr (median 0.29, range 0.03-2.55). YMN correlated inversely with joint space width at operation and follow-up duration, and was increased in atrophic OA (r = 0.71). The time between diagnosis and THA correlated with JSW at diagnosis, and was inversely correlated with age at onset and YMN. It was longer in patients with hypertrophic OA (r = 0.69). CONCLUSION: Rapid progression of JSN, older age and absence of osteophytes appear to be the main factors leading to THA.     

Impact of a clinical pathway and implant standardization on total hip arthroplasty: a clinical and economic study of short-term patient outcome

This study evaluates the impact of a clinical pathway (CP) and a hip implant standardization program (HISP) on the quality and cost of total hip arthroplasty (THA). Two hundred six unilateral THA operations for osteoarthritis were evaluated: 89 operations were performed in 1991 without a CP or HISP (4-year follow-up period); 117 operations were performed in 1993 with a CP and HISP (2-year follow-up period). All patients had good clinical results and excellent outcomes with short-term follow-up evaluation. No differences were seen between groups in terms of patient ratings of outcome and satisfaction or in terms of complication rates in the hospital. Implementation of a CP and HISP did not adversely affect the short-term outcome of THA but did reduce hospital length of stay and hospital cost for THA.     

Hydroxyapatite coating versus cemented fixation of the tibial component in total knee arthroplasty: prospective randomized comparison of hydroxyapatite-coated and cemented tibial components with 5-year follow-up using radiostereometry

A mathematical model that characterizes the response of venous oxygenation to changes in cerebral blood flow (rCBF) and oxygen consumption has been previously presented. We use this model to examine the dampening phenomenon in functional MRI (fMRI) signals with rapidly alternating periodic stimulation bursts. Using a mass balance approach, the equations for an input-output model are derived and solved using Matlab (the Math Works Inc.). Changes in venous oxygenation are related to the results of fMRI experiments using progressively shorter periods of stimulation. An impulse-response function for the model is derived in an attempt to explore the source of the lag in cerebral hemodynamics. Increasing the frequency of stimulation bursts eventually produces a dampening in the fMRI signal. The dampening phenomenon in fMRI signals occurs with stimulation of high frequency on-off alternation. The dynamics of signal dampening, as well as the impulse-response function of a blood oxygen level-dependent model, lend strong indirect support to the hypothesis that blood oxygen level-dependent contrast at the level of the venous blood pool, rather than R1 inflow effects or changes in oxygenation at the level of the capillary bed, underlies the observed signal changes in fMRI.     

Polyethylene wear after total hip arthroplasty: the effect of a modular femoral head with an extended flange-reinforced neck

The use of modular components in total hip arthroplasty has been thought to contribute to accelerated polyethylene wear. Specifically, a modular femoral head with a flange extension and a longer neck may cause increased wear. The purpose of the current study was to evaluate the effect of a flange extension on polyethylene wear. Ninety-one patients who had had a total of 100 primary total hip arthroplasties were evaluated after an intermediate duration of follow-up. All of the acetabular components consisted of a hemispherical titanium-alloy fiber-mesh porous-coated shell with a nonelevated modular polyethylene liner; they were inserted without cement and with use of supplemental screws through the dome after so-called line-to-line reaming. All of the femoral components consisted of a modular head with a diameter of twenty-eight millimeters and either a long neck (with a flange extension) or a short or medium neck (without a flange extension). The study group comprised sixty-two patients (sixty-six hips) who had had radiographic evaluation that was adequate to allow the valid measurement of polyethylene wear. Thirty-two hips were in men, and thirty-four were in women. The mean age of the patients was fifty-six years, the mean weight was seventy-three kilograms, and the mean duration of follow-up was 6.1 years (range, four to eight years). The rate of polyethylene wear in the eleven hips in which the femoral component had a flange extension was significantly greater than that in the fifty-five in which the femoral component did not have a flange extension (mean, 0.17 compared with 0.11 millimeter per year; p = 0.009). Multivariate analysis showed that the presence of a flange extension was associated with increased polyethylene wear to a greater degree (F = 2.86) than were all other variables that were measured, including a younger age (F = 1.72), a more vertical angle of the acetabular component (F = 0.49), a heavier weight (F = 0.14), male gender (F = 0.11), and a smaller initial thickness of the polyethylene (F = 0.02). These data support an association between the presence of a modular femoral head with a flange extension and an accelerated rate of polyethylene wear. The presumed mechanism is an increase in peripheral, or so-called rim, impingement of the flange-reinforced neck on the acetabulum due to a decrease in the ratio between the diameters of the femoral head and neck.     

Anterior cruciate ligament reconstruction with the patellar tendon augmented by absorbable artificial materials. A histological and molecular biological study in rabbits

An experimental study was performed to investigate the histological and molecular biological properties of reconstructed anterior cruciate ligaments (ACL) using the patellar tendon augmented by absorbable artificial material in rabbits. Thirty rabbits underwent ACL reconstruction with the patellar tendon (non-augmented group), and 30 with the patellar tendon augmented by a polyglactin 910 mesh (augmented group). They were respectively sacrificed at at 1, 2, 3, 4, 6, 8 and 12 weeks after surgery for histological and molecular biological examination. Histologically, the fibrocytes were disappeared in deep portion of transplanted graft at 2 weeks after surgery in both groups. The graft was replaced with granulated tissues at 6 weeks in the augmented group, but it took 8 weeks in the non-augmented group. At 12 weeks, the graft showed hypocellularity with regularly oriented fibers in the augmented group, while it still showed hypercellularity with disoriented fibers in the non-augmented group. Molecular biologically, after the reconstruction at one week, the relative radioactivity in the graft was 1.05 in the non-augmented group, and 2.10 in the augmented group. Additionally the level of the alpha 2 (I) collagen mRNA was also significantly higher in the augmented group than that in the non-augmented group. These results suggested that a polyglactin 910 mesh had an effect on the process of reorganization and remodeling in the transplanted patellar tendon during the post-operative period in rabbit.     

Clear cell adenocarcinoma of the uterine cervix: a histological and histochemical study

A case of Mullerian clear cell adenocarcinoma of the uterine cervix occurring in a young women is presented. A detailed histological and histochemical study of this type of tumour is important so as to separate it from the clear cell tumour of mesoenphric origin. The association of Mullerian clear cell adenocarcinoma and other abnormalities of the vagina and cervix with the administration of maternal nonsteroidal oestrogens has been recently stressed in the literature. However, our patient is illustrative of the 30-50% of cases reported to date which have few if any of the associated abnormalities of the genital tract and have no known exposure to non-steroidal oestrogens.     

Effect of microamperage stimulation on the rate of wound healing in rats: a histological study

BACKGROUND AND PURPOSE: This study examined cutaneous wound healing after microamperage stimulation (MS). SUBJECTS: Twelve female Sprague-Dawley rats were studied. METHODS: The treatment (wound reduction) group (n = 6) received 100 microA of current at 0.3 Hz on a 50% duty cycle for 2 hours a day for 14 days. The control group (n = 6) received the same handling and electrode placement, but no current was applied. Wound size was measured daily following each treatment. Histological analysis included measurement of epithelial thickness, vascularity, and fibroblast density from tissue sections taken at the end of the experiment. RESULTS: An analysis of variance showed no significant difference between the two groups with respect to the change in wound size over the 14 treatment days. A series of t tests showed no significant differences between the groups for any of the histological measurements. CONCLUSION AND DISCUSSION: The results of this study do not support the hypothesis that MS accelerates acute cutaneous wound healing.     

Predicting the mechanical outcome of femoral neck fractures fixed with cancellous screws: an in vivo study

OBJECTIVE: The goal of this project was to determine, by using a retrospective cohort analysis, the relative importance of fracture geometry, bone density, and quality of fracture reduction in predicting redisplacement of femoral neck fractures fixed with multiple cancellous screws in a patient population. DESIGN: A retrospective analysis of quantitative geometric and bone density data from forty-seven patients with femoral neck fractures fixed with cancellous screws was performed. SETTING: Radiographs retrieved after analysis of a statewide hospital database were digitized and analyzed quantitatively. INTERVENTION: Quantitative data from radiographs included estimates of femoral neck bone density, fracture surface orientation and location, degree of comminution, prefixation displacement, initial reduction position of the fractured component, and final displacement of the fracture after fixation. MAIN OUTCOME MEASUREMENTS: Angular rotation and inferior displacement of the fracture component after fixation. RESULTS: Femoral neck bone density can be correlated to femoral cortical thickness and can be used as a measure of bone density from plain x-rays. Significant relative risk of redisplacement of a femoral neck fracture is correlated with initial inferior offset of the fracture component and varus angulation. Relative risks of other variables, including valgus reduction, Garden Stage 3 and 4 position of the femoral head, low bone density, presence of inferior comminution, a more vertical fracture surface angle, and fracture position, were not significant. CONCLUSIONS: When compared with other geometric and mechanical variables, nonanatomic reduction of a femoral neck fracture, with either inferior offset or varus angulation, is the strongest predictor of postfixation redisplacement of the fracture.     

Cytotoxicity of Kuwait weathered lake crude oil on rat hepatocytes: a histological and ultrastructural study

BACKGROUND: We sought to determine whether there was empirical support for the diagnostic thresholds of DSM-IV bulimia nervosa (BN) and whether an empirically derived typology resembled the diagnostic categories of DSM-IV. METHODS: Detailed information about bulimic behaviours were assessed via personal interview in a population-based sample of 1897 Caucasian female twins. We assessed the lifetime prevalence of the component bulimic behaviours and DSM-IV and DSM-III-R BN. Latent class analysis of nine separate bulimic symptoms was used to develop an empirical typology of bulimic behaviour. RESULTS: Although the lifetime prevalences of bingeing (23.6%) and vomiting (4.8%) were relatively common, DSM-IV BN was distinctly uncommon (0.5%). The criterion that specified the frequency and duration of bingeing and vomiting was an important limiting condition. Analysis of alternative thresholds found little support for the DSM-IV thresholds requiring an average of twice per week for 3 months. Latent class analysis yielded an interpretable four class solution that had little overlap with the DSM-IV typology. CONCLUSIONS: As in other studies of unselected samples of women, the lifetime presence of bulimic behaviours are relatively high. Our results suggest that the DSM-IV approach to categorizing bulimic behaviour inadequately captures the spectrum of lifetime bulimic behaviours in the general population.     

Clinical and histological evaluation of thermal injury thresholds in human teeth: a preliminary study

The effect on healthy dental pulp of thermal increases ranging from 8.9 to 14.7 degrees C was evaluated. These temperature increases correspond approximately to those caused by certain restorative procedures, such as tooth preparation with high-speed instruments and the fabrication of direct provisional crowns. Two criteria of evaluation have been used in conjunction, a clinical (symptomatic) and a histological one, to assert with greater precision potential damage to the pulp. The results suggest a low susceptibility of cells to heat, which does not appear to be a major factor of injury, at least in the short term. The main cause of postoperative inflammation or necrosis of the pulp is probably the injury of the dentine, a tissue in direct functional and physiological connection with the pulp.     

Effects of short-term treatment with the bisphosphonates zoledronate and pamidronate on rat bone: a comparative histomorphometric study on the cancellous bone formed before, during, and after treatment

To study the anti-resorptive effects of zoledronate and pamidronate on growing long bones we have performed a histomorphometric analysis of the three regions of the proximal tibial cancellous bone of bone formed before, during, and after drug treatment. Male rats (190-220 g) were treated subcutaneously for 10 days with zoledronate (0.028-2.8 microg/kg) or pamidronate (3.7-370 microg/kg) and sacrificed 5 days later. To delineate the three regions of cancellous bone, and for dynamic bone histomorphometry, calcein and demeclocycline were injected at various times. Both bisphosphonates caused a dose-dependent suppression of cancellous bone turnover and resorption to produce an increase in cancellous bone, but zoledronate was 100 times more potent than pamidronate. The increase in the bone amount and connectivity was more pronounced in the bone formed during treatment where transient bone resorption and normal bone formation led to a positive bone balance. In the bone formed before treatment, inhibition of bone resorption associated with reduced bone formation produced a net gain in amount of bone. Although both bone regions showed a positive bone balance, more bone accumulated in the bone formed during treatment probably because its trabecular bone surface was three times greater. In the primary spongiosa formed after treatment, a moderate increase in the bone amount and connectivity was observed only at the highest dose of both bisphosphonates. The bone formed before, during, and after treatment with bisphosphonates responds differently due to differences in bone architecture, rates of modeling and remodeling, and period of drug exposure.