The effect of cyclic pressure on human monocyte-derived macrophages in vitro. (17/642)

Aseptic loosening and osteolysis around prosthetic joints are the principal causes of failure and consequent revision. During this process activated macrophages produce cytokines which are thought to promote osteolysis by osteoclasts. Changes in pressure within the space around implants have been proposed as a cause of loosening and osteolysis. We therefore studied the effect of two different regimes of cyclic pressure on the production of interleukin-1beta (IL-1beta), IL-6 and tumour necrosis factor-alpha (TNF-alpha) by cultured human monocyte-derived (M-D) macrophages. There was a wide variation in the expression of cytokines in non-stimulated M-D macrophages from different donors and therefore cells from the same donor were compared under control and pressurised conditions. Both regimes of cyclic pressure were found to increase expression of IL-6 and TNF-alpha. Expression of IL-1beta was increased by a higher-frequency regime only. Our findings suggest that M-D macrophages are activated by cyclic pressure. Further work will be required to understand the relative roles of frequency, amplitude and duration of applied pressure in the cellular effects of cyclic pressure in this system.  (+info)

Cementless hemispheric acetabular component in total hip replacement. (18/642)

A series of 198 total hip arthroplasties was performed using a porous-coated, hemispheric press-fit cup. One hundred and twenty-seven cups were available for clinical and radiological examination at mean follow-up of 10.6 years. The mean age at the index procedure was 61.2 years. The mean Harris hip score at final follow-up was 89.8. Three cups were revised for aseptic loosening and two liners were changed for eccentric wear and pelvic osteolysis. Nine additional patients showed mild or suspected osteolysis. Two cups were rated "fibrous" stable. There was no correlation between additional screw fixation of the press-fit cup and osteolysis or revision.  (+info)

A modular femoral implant for uncemented stem revision in THR. (19/642)

We present the early results of 142 uncemented femoral stem revisions using the modular MRP-Titan system. There were 70 cases with marked preoperative femoral bone defects (Paprosky type 2C and type 3); and bone grafts were used in 31 cases. At a mean follow-up of 2.3 years five cases were re-revised due to dislocation and two due to aseptic loosening. The mean Harris hip score improved from 37.4 preoperatively to 92.4. In 122 cases progressive bone regeneration on X-ray was seen; and no further osteolysis was observed.  (+info)

A conservative femoral replacement for total hip arthroplasty. A prospective study. (20/642)

Between 1985 and 1993, 146 patients (162 hips) had total hip replacement (THR) using a conservative uncemented femoral component. The mean age of the patients was 50.8 years and the mean follow-up was 6.2 years (2 to 13). One patient was lost to follow-up, one died within two years of surgery and one had a revision procedure after a fracture sustained in a road-traffic accident. For the remaining 159, Kaplan-Meier survival analysis was calculated for the incidence of revision because of mechanical loosening or osteolysis. Survival without mechanical loosening at both five and ten years was 98.2%. Survival without osteolysis was 99% at five and 91% at ten years. The Harris hip score improved from a mean of 66.3 before to 90.4 at follow-up. Of particular note is the lack of thigh pain in this group. Radiological analysis showed that 139 stems (88%) had no measurable subsidence, 8 (5%) had less than 2 mm and 12 (7%) had more than 2 mm. Two of the eight and one of the 12 were revised for mechanical loosening. Nine hips were revised for late loosening associated with osteolysis. No reaming of the femoral canal was associated with statistically significant less blood loss compared with a comparable control group of uncemented implants (p < 0.0001). Our study suggests that using a conservative femoral implant does not protect against wear debris but the reliable mechanical stability (98.2%) makes this an attractive design of implant particularly for young patients.  (+info)

Anti-TNF-alpha therapy as a clinical intervention for periprosthetic osteolysis. (21/642)

Aseptic loosening of total joint arthroplastics due to periprosthetic osteolysis is a frequent cause of implant failure. The absence of clinical interventions to arrest or prevent this complication limits the use of total joint replacement especially in younger patients. Here we review recent studies implicating tumor necrosis factor (TNF)-alpha in periprosthetic osteolysis and the rationale for clinical studies of anti-TNF therapy and other interventions for periprosthetic loosening.  (+info)

pH dependence of bone resorption: mouse calvarial osteoclasts are activated by acidosis. (22/642)

We examined the effects of HCO(3)(-) and CO(2) acidosis on osteoclast-mediated Ca(2+) release from 3-day cultures of neonatal mouse calvaria. Ca(2+) release was minimal above pH 7.2 in control cultures but was stimulated strongly by the addition of small amounts of H(+) to culture medium (HCO(3)(-) acidosis). For example, addition of 4 meq/l H(+) reduced pH from 7.12 to 7.03 and increased Ca(2+) release 3.8-fold. The largest stimulatory effects (8- to 11-fold), observed with 15-16 meq/l added H(+), were comparable to the maximal Ca(2+) release elicited by 1,25-dihydroxyvitamin D(3) [1, 25(OH)(2)D(3); 10 nM], parathyroid hormone (10 nM), or prostaglandin E(2) (1 microM); the action of these osteolytic agents was attenuated strongly when ambient pH was increased from approximately 7.1 to approximately 7.3. CO(2) acidosis was a less effective stimulator of Ca(2+) release than HCO(3)(-) acidosis over a similar pH range. Ca(2+) release stimulated by HCO(3)(-) acidosis was almost completely blocked by salmon calcitonin (20 ng/ml), implying osteoclast involvement. In whole mount preparations of control half-calvaria, approximately 400 inactive osteoclast-like multinucleate cells were present; in calvaria exposed to HCO(3)(-) acidosis and to the other osteolytic agents studied, extensive osteoclastic resorption, with perforation of bones, was visible. HCO(3)(-) acidosis, however, reduced numbers of osteoclast-like cells by approximately 50%, whereas 1,25(OH)(2)D(3) treatment caused increases of approximately 75%. The results suggest that HCO(3)(-) acidosis stimulates resorption by activating mature osteoclasts already present in calvarial bones, rather than by inducing formation of new osteoclasts, and provide further support for the critical role of acid-base balance in controlling osteoclast function.  (+info)

Bone defect associated with middle meningeal arteriovenous fistula treated by embolization--case report. (23/642)

A 57-year-old male presented with a frontal bone defect associated with a middle meningeal arteriovenous fistula (AVF) manifesting as headache. The patient had a history of head injury 19 years previously. Skull radiography and computed tomography demonstrated a left frontal bone defect. Left external carotid angiography demonstrated a middle meningeal AVF at the frontal region, at the same location as the bone defect. The AVF was fed by the bilateral middle meningeal and left deep temporal arteries, and drained by the superior sagittal and ipsilateral cavernous sinuses. The minor feeding artery, the left deep temporal artery, was embolized with polyvinyl alcohol particles, then 0.4 ml of a 1:3 mixture of n-butyl cyanoacrylate and lipiodol was injected from the left middle meningeal artery. Follow-up angiography 3 months after the embolization revealed complete obliteration of the fistula. The bone defect may have been caused by erosion of the frontal bone by the pulsating effect of the feeding and draining vessels of the fistula, or by inadequate nutrition to the bone tissue because of the arteriovenous shunt.  (+info)

Horizontal platform supported total hip replacement. (24/642)

OBJECTIVE: To investigate the effect of horizontal platform supported (HPS) prosthesis on cementless total hip replacement for surgical treatment of arthritis in a long-term follow-up study. METHODS: Clinical and radiographic follow-up of 65 consecutive primary cementless porous coated HPS total hip replacements, which were implanted in 60 patients between 1982 and 1989, was carried out. RESULTS: The 53 hips in 50 patients were evaluated both clinically and radiographically. The average follow-up was 6.8 years (range: 5 to 12 years). According to the Harris hip score, 52 (98%) of the hips had sustained an excellent or good result with an average score of 92. At the time of final assessment, no patient experienced anterior thigh pain. There were two revisions performed early in the series due to technical failures. Radiographically, osteolysis and bone remodelling were assessed. CONCLUSION: The findings suggest that the clinical and radiographic results after cementless total hip replacement for primary hip arthroplasty may be favourably influenced by the use of the proximal stress loaded HPS femoral component.  (+info)