Role of mesenchymal collagenase in the loosening of total hip prosthesis

Fibroblast-type interstitial collagenase (E.C. 3.4.24.7) was associated with loosening of total hip prostheses in eight patients: there were four cemented stems and one cementless stem with the common type of loosening and two cemented stems and one cementless acetabular component with aggressive granulomatous lesions. The authors used a specific, well-characterized, heterologous, affinity-purified, polyclonal rabbit anti-human fibroblast collagenase antiserum applied in avidin-biotin-peroxidase-complex (ABC) staining. In the aggressive granulomatous type of loosening, collagenase was found in most of the fibroblast- and macrophagelike cells, including multinuclear giant cells and epithelioid cells in periprosthetic tissue. Collagenase-positive cells also were found in the periprosthetic tissue associated with common loosening. Collagenase was also found in capillary and postcapillary venule endothelial cells in the richly vascularized aggressive granulomatous tissue. Collagenase was extracted directly from the tissue samples and incubated with soluble Type I collagen. Collagen degradation products then were analyzed by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis, and the three-fourths length degradation product quantitated by gel scanning densitometry. In both aggressive granulomatosis and the common type of loosening, extractable collagenase was found in tissue. No significant differences between the sample groups were detected in respect to total measurable collagenase, however. The extractable collagenase was present in a latent form that could be activated by the organomercurial procollagenase activator, phenylmercuric chloride (PMC). It is likely that interstitial collagenase contributes to rapid growth of reactive infiltrative tissue, loosening of the prosthesis associated with aggressive granulomatosis, and the periprosthetic lytic process associated with the common type of hip prosthesis loosening.     

Algorithm for the surgical treatment of malignant lesions of the proximal tibia

Complications are common among patients treated for malignant lesions of the proximal tibia and can be difficult to manage. This investigation was a retrospective review of 40 patients treated with total knee replacements after proximal tibial resections. Various reconstructive methods were used to fix the prosthetic stems, reestablish the extensor mechanism, and provide soft tissue coverage. Thirty-one patients had adequate followup to allow for review of prosthetic outcome (means, 78 months; range, 25-193 months). Seven patients died with less than 2 years followup, and two patients had postoperative acute infections treated by early amputation to allow chemotherapy to resume promptly. The overall 5-, 8-, and 12-year event free prostheses survival rates were 62%, 33%, and 16%, respectively. Prognostic factors for prosthetic survival were analyzed (age, gender, type of excision, type of prosthesis, type of fixation, and percent of bone resected). None were statistically significant. Patients with less than 40% of the tibia resected had better prosthetic survival at 5 years. The durability of uncemented stem fixation exceeded that of cemented stems. Expected survival of prostheses after revision was 52% at 8 years. The major cause of limb loss was infection. Failure to reconstruct soft tissues satisfactorily caused most failures. Aggressive multistage management of infection is needed. Prosthetic knee replacement is most suitable for patients with cancers that require chemotherapy and for those patients who have short potential survival.     

Activation of periprosthetic connective tissue in aseptic loosening of total hip replacements

In aseptic loosening of initially well inserted total hip prostheses, implant wear debris and cyclic mechanical loading lead to a foreign body type of chronic inflammatory reaction, then to osteolysis, and finally to loosening of the implant. In the present work the reactive and adaptive changes of the periprosthetic tissues and pseudojoint were characterized by analysis of the local cell proliferation. Immunohistochemical demonstration of proliferating cells was performed by application of affinity purified rabbit antihuman Ki-67 antibodies to periprosthetic tissues obtained from revision operations for loose total hip prostheses. The fibrous areas and, in particular, the cell rich, vascular areas of the interface tissue (between implant and bone) and the pseudocapsule around aseptically loosened implants contained higher numbers of proliferating cells than the tissues around well fixed implants. In addition, the pseudosynovial lining occasionally contained some Ki-67 positive proliferating cells. Somewhat surprisingly, proliferating vascular endothelial cells were relatively rare. These findings suggest that reactive (interface tissues) and adaptive (pseudojoint and capsule formed around the artificial joint) tissue changes in loosening total hip prostheses comprise proliferation of local fibroblastlike cells. It is concluded that periprosthetic tissues of the loosened total hip prosthesis represent activated mesenchymal tissue.     

Porous-coated total hip replacement

Fifteen years of clinical experience with porous-coated prostheses demonstrated the durability of this type of fixation. This experience was documented by clinical follow-up study of the 393 cases treated by the senior author before 1985. Only six of these femoral components have been revised: three for loosening, two for stem breakage, and one for infection. Thus, the revision rate for the porous-coated stems was 1.5%. Porous-coated acetabular components were used in 227 of the arthroplasties. Five of these porous-coated cups have been revised: four for malposition leading to dislocation and one for late loosening secondary to osteolysis. Thus, the revision rate for these porous-coated acetabular components was 2.2%. Twenty bipolar and 146 cemented acetabular components were used in the remaining 166 cases treated before 1985. Eleven (7.5%) of the cemented acetabular components were revised. Revisions of the porous-coated components were rare in the first ten postoperative years. The clinical data were supplemented with analysis of postmortem specimens from 15 patients. Mechanical testing of the femoral specimens showed the relative micromotion at the porous surface to be exceptionally small (less than 40 microns). Seven of these postmortem retrievals involved cases with unilateral arthroplasties. In these cases, the contralateral normal femur also was removed, and a prosthesis identical to that in the in vivo implanted side was inserted to simulate the immediate postoperative condition. Dual-energy X-ray absorptiometry (DEXA) of the seven paired femora demonstrated that bone remodeling can be expected to produce a 5%-52% loss of periprosthetic bone mineral content, with the greatest loss occurring in the more osteoporotic patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ceramic endoprosthesis in total hip arthroplasty

Aluminia-on-aluminia hip prosthesis with titanium alloy stem was used in 255 cases, for 143 patients with cemented acetabular cup and 112 with an uncemented screw cup. The average age of the patients was 62 years. Of the patients, 35 were treated bilaterally. The indication for surgery was osteoarthritis in 186 cases, fractures and nonunions of the hip joint in 34 cases, and congenital dislocations of the hip joint in 16 cases. Previous surgery of the hip joint was recorded for 43 cases. All procedures were primary arthroplasties. Only personal clinical examinations together with radiographic studies were accepted as clinical data. Three patients failed to show up for routine follow-up evaluation and these were excluded from the series. Revision operation was classified as failure. The indications for revision were aseptic loosening, late infection, and fracture of the acrylic cement resulting in loosening of the acetabular or femoral component. The acetabular component was cemented in 143 patients and the mean follow-up period for these patients was 6.7 years (range, 1-12 years). In this series, a revision operation was undertaken for 16 patients (11%). In 12 cases, broken acrylic cement resulted in acetabular aseptic loosening. In the series of 112 patients with uncemented titanium screw cup, the mean follow-up period was 3.6 years (range, 1-7 years) and a revision operation was undertaken in seven cases (7%). In two, the indication was late infection; in one, technical failure; and in two, progression of Pigmented villonodular synovitis. Acetabular aseptic loosening resulted in revision in only two cases. With cementless acetabular component bone transplantation is indicated.(ABSTRACT TRUNCATED AT 250 WORDS)     

Low dose flunarizine protects the fetal brain from ischemic injury in sheep

This retrospective long-term study analyzes the clinical function, failures, and radiographic status of 131 Richards Series 2 prostheses in total hip arthroplasties (THAs) performed during 1981 and 1982. After a minimum follow-up period of 11 years, the results were evaluated. Sixty two (54%) patients with 71 THAs were available for follow-up; 44 (38%) patients with 49 THAs had died. Three patients with three THAs were lost to follow-up, and seven patients with eight THAs were unable to participate in the examination due to causes not related to their present hip status. Ten patients underwent revision THA during the observation period. The median hip functional index (HFI) was 8.6 preoperatively and 15.8 at follow-up. Hip functional index correlated to radiographic signs of loosening. With revision as endpoint, the Kaplan-Meier survivorship for all 131 hips was 93% after 10 years and 91% after 12 years. The radiographic examination at follow-up revealed 5 (8%) definite loose cups and 12 (19%) definite loose stems. Including the number of aseptic loosened cups and stems confirmed at revision, aseptic loosening was found in 6% of all cups and 13% of all stems. This radiographic evaluation confirmed that lack of containment of the cup and varus position of the stem were factors influencing the long-term stability of the prostheses, whereas etiology, type of arthritis, and ectopic ossification did not. A fixation and stability score that was modified for cemented prostheses was developed and was of value in detecting the prostheses at risk. The long-term results of the Richards Series 2 THA are acceptable and comparable with other long-term studies on conventional prosthetic designs. Ten percent to 20% revision THAs due to aseptic loosening can be expected. In addition, patients younger than age 60 at surgery and especially men were found to belong to a high-risk group with regard to revision THA. These patients must be evaluated carefully so that revision THA can be performed before the bone bed is destroyed.     

Effect of nitric oxide, prostacyclin, and thromboxane on the vasospastic action of hydrogen peroxide on human umbilical artery

During the years 1991-1994, the Norwegian Arthroplasty Register recorded 1,324 primary hip arthroplasties implanted with the Boneloc cement. We have compared the survival until revision due to aseptic loosening for charnley (n 955) and Exeter (n 172) prostheses. The Boneloc cemented hips were also compared with high viscosity cemented hips implanted during the same period. In the Boneloc cemented group, the estimated probability of survival at 4.5 years of a Charnley femoral component was 74% and for an Exeter femoral component 97% (p < 0.0001). Using a Cox regression model with adjustment for age, gender, type of cement, systemic antibiotic and stratified for diagnosis, an 8 times higher risk of revision was found in Boneloc cemented Charnley femoral components than in Exeter femoral components (p < 0.0001). For the acetabular components, the difference between the Charnley and Exeter components with Boneloc cement was not statistically significant. In both the Charnley and the Exeter prostheses, the high viscosity cemented components had significantly better survival than the Boneloc cemented components. The Cox regression model showed that a Boneloc cemented Charnley femoral component had a 14 times higher risk of revision than a high viscosity cemented component (p < 0.0001), and for Exeter femoral components a 7 times higher revision risk was found in the Boneloc cemented components (p = 0.003). Our results confirm the previously reported inferior results of Charnley prostheses implanted with Boneloc cement and inferior results of Boneloc cemented Exeter prostheses as well, but less pronounced than for Charnley prostheses.     

From the RSNA refresher courses. Total hip arthroplasty: radiographic evaluation

Expected appearances of total hip arthroplasty vary according to type of implant, its method of fixation (cemented, porous coating for bone ingrowth, press fit), and whether it is a revision. Cemented arthroplastic components normally may show 1-2-mm-wide radiolucent zones at cement interfaces. Definite loosening is diagnosed when progressive widening of the radiolucent zone, migration of a cemented component, or change in alignment is seen. In cementless arthroplasty, normal findings include calcar resorption, radiolucent zones up to 2 mm in width, cortical thickening, periosteal reaction, endosteal sclerosis, and even subsidence of the femoral component that stabilizes at less than 1 cm. The most reliable radiographic signs of loosening in cementless arthroplasty are progressive subsidence, migration, or tilt of the component. Because subsidence or change in alignment may be very subtle, serial radiography and measurement are often required for diagnosis. Other signs that indicate loosening include bead shedding (in porous-coated prostheses), extensive cortical hypertrophy, endosteal bone bridging at the stem tip, endosteal scalloping, and a radiolucent zone wider than 2 mm. In revision arthroplasty, wide radiolucent zones and subsidence are common. The diagnosis of revision failure is based on progressive widening of the radiolucent zones and change in component position after 12 months.     

Survivorship analysis of cemented total hip arthroplasty acetabular components implanted with second-generation techniques

The clinical and radiographic results of primary cemented total hip arthroplasty performed by a single surgeon, with particular emphasis on the performance of acetabular components implanted with so-called second-generation cement techniques, were studied. Seventy hips with 48 metal-backed and 22 polyethylene acetabular components were followed for a mean of 9 years (range, 5-11.5 years). The clinical results were evaluated using a recognized hip score. The fixation status of the cemented acetabular component was evaluated using two methods of measuring radiolucent lines at 5 years and at the last evaluation. Acetabular component loosening was defined as a circumferential radiolucent line, component migration, or revision for loosening. This study was unable to confirm the findings of others that demonstrated higher failure rates with cemented metal-backed components when compared with all-polyethylene components. The survival of cemented acetabular components with 28-mm head femoral prostheses was worse than the survival of cemented acetabular components with 22-mm femoral heads in other published reports, despite advances in cement techniques. Because of the high rate of loosening of cemented 28-mm-inner-diameter acetabular components at 5 and 10 years, the authors no longer use these cemented components for acetabular reconstruction.     

Modular unipolar versus bipolar prosthesis: a prospective evaluation of functional outcome after femoral neck fracture

Between January 1, 1987, and December 31, 1992, 140 community-dwelling geriatric patients > or = 65 years of age with a displaced femoral neck fracture (Garden III-IV) underwent primary prosthetic replacement and were followed prospectively for a minimum of 1 year. Overall, 92 patients received a cemented bipolar prosthesis and 48 patients received a cemented modular unipolar prosthesis. There were no statistically significant differences between the two groups with respect to preinjury characteristics (age, sex, and number and severity of medical comorbidities) and functional ability. There were no statistically significant differences between the two groups with regard to the number of postoperative complications, length of stay, and 1 year mortality rate. An in-depth functional evaluation was obtained as follows: level of ambulation, independence in basic activities of daily living (feeding, bathing, dressing, toileting), and independence in instrumental activities of daily living (food shopping, food preparation, banking, laundry, housework, and use of public transportation). At 1 year follow-up, no statistically significant differences in functional ability were identified between the unipolar and bipolar groups. Furthermore, at a minimum of 1 year follow-up, there were no statistically significant differences between the two groups with regard to the need for revision surgery or the incidence hip pain. Based on the results of this study, there does not appear to be any advantage to the use of bipolar endoprosthesis for the treatment of femoral neck fractures in the elderly patient. The lower cost of modular unipolar prostheses compared with bipolar prostheses provides additional support for their use.     

Biphasic spiral computed tomography versus digital subtraction angiography for evaluation of arterial thrombosis after orthotopic liver transplantation

Aseptic loosening of implant components is a common and important complication of both cemented and uncemented prosthetic joint replacements. Wear particles derived from organic polymer and metal implant biomaterials are commonly found within macrophages and macrophage polykaryons in the fibrous membrane between loose implant components and the host bone undergoing resorption. In order to determine whether biomaterial particle-containing, foreign-body macrophages may contribute to periprosthetic bone resorption, we cultured murine monocytes that had phagocytosed particles of biomaterials commonly employed in bone implant surgery [polymethylmethacrylate (PMMA), ultra-high molecular weight polyethylene (PE), titanium and chromium-cobalt] on bone slices and glass coverslips with UMR 106 osteoblast-like stromal cells in the presence of 1,25-dihydroxy-vitamin D3. Under these conditions, all biomaterial particle-containing, foreign-body macrophages differentiated into osteoclastic cells, i.e. tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells capable of extensive lacunar bone resorption. This study shows that particle phagocytosis by macrophages does not abrogate the ability of these cells to undergo osteoclast differentiation. These findings emphasise the importance of the foreign-body macrophage response to biomaterial wear particles in the pathogenesis of aseptic loosening.     

Complications from the hinged GUEPAR prosthesis after resection of knee tumor. 102 cases

PURPOSE: The purpose of this study was to present the complications which occurred in knee replacement with the GUEPAR prosthesis, after bone tumor resection. We tried to point out complications in relation to prosthetic design and surgical technique. MATERIAL AND METHOD: Between 1972 and 1993, 90 patients had a knee resection, for 80 malignant and 10 benign tumors. There were 51 males and 49 females, aged 12 to 75 years (mean age 35). Fifty-six distal femur resections and 34 proximal tibial resections were performed. Length of resection averaged 16 cm (9 to 30). The reconstruction was always achieved with a cemented, custom-made GUEPAR prosthesis. Including revisions, there was a total of 102 prostheses in 90 patients. A patellar resurfacing was performed in 64 cases. An allograft reconstruction was associated in 39 knees. In all tibial resections and in two extra-articular femoral resections, the extensor mechanism had to be reconstructed. Several reconstruction techniques were associated, in which 19 medial gastrocnemius transfers. The prosthesis design was slightly modified with time. Ten patients received radiotherapy, and 55 had chemotherapy. RESULTS: Results and complications were retrospectively assessed, with an average follow-up of 4.3 years (1 to 22). Six patients were lost for follow-up, 62 patients were alive, with no evolutive disease, 13 had an evolutive disease and 10 were deceased from disease. Nineteen patients had distant metastasis and 17 had local recurrences. Apart from intraoperative complications, late mechanical complications included: 13 aseptic loosening, 2 femoral shaft fractures, 18 knee contractures, 5 femoral stem fractures and, 18 intra-articular instabilities related to wear of the hinge-axis. In the 39 allograft-composite prostheses, only 15 had a favorable evolution. There were 15 extensor mechanism failures and 13 knees had persistent infection. There was a total of 94 reoperations in the 90 patients. In 28 cases, the initially implanted prosthesis was removed. There were also 18 revisions, 7 amputations and 3 arthrodeses. Survivorship analysis showed a 60 per cent probability for the initial prosthesis not to be revised at 10 year-follow-up, apart from oncologic complications. DISCUSSION: Results with allograft-composite reconstruction were not better than with massive prosthesis. When needed, soft tissue coverage and patellar tendon augmentation would better be performed with gastrocnemius plasty. Polyethylene and steel bushes were not solution for hinge axis wear.     

Microalbuminuria and cardiovascular risk

As a part of long-term follow up (I) of 544 cemented Müller-curved stem total hip replacements (THR), implanted 1977 to 1983, 207 THR in 163 patients with rheumatoid arthritis (RA) were evaluated 9 to 15 years (11 on an average) postoperatively. The feed back rate was 96.9% so the results are very reliable. 18 cups were loosened (13 already changed), but no stem had to be changed for aseptic loosening. 2 THR (1.0%) had to be revised because of deep infection. Survival rate of Kaplan and Meier for aseptic loosening was 94.6% after 10 years, 83.5% after 15 years. The ARO multi-center-study 1995 (II) includes 3113 THR implanted 1987 and 1988. Within a follow-up period of 7 to 9 years the over all rate of aseptic changing for cemented cups (1.4%) was significantly lower than for uncemented cups (2.9%)--in RA even 1% versus 5.7%. The corresponding rates for stems was 1.0% (cemented) versus 1.8% (uncemented). We contributed 110 THR in 94 patients with RA with feed back of 100%. Because of deep infection one THR had to be changed and two were explanted. But no change of cup or stem because of aseptic loosening was observed. Also in the literature survival rates up to 97% after 10 years or 77% after 25 years even in younger patients with RA can be stated. CONCLUSIONS: Cemented THR shows good long-term-results in RA which with uncemented designs have also to be proved. As a consequence of analysing the (few) failures the cemented THR of Wessinghage with optimized bone-cement-implant-compound was introduced. We demand a high feed back rate in long-term follow-ups also with respect to quality management and comparing data.     

100 cemented versus 100 noncemented stems with comparison of 25 matched pairs

Two series of 100 consecutive primary total hip arthroplasties, each using a single design of noncemented or cemented femoral component (all 28 mm heads), were compared. One cemented and two noncemented stems underwent revision for aseptic loosening. Of unrevised hips, outcome data statistically favored cemented, rather than noncemented, stems. The data for cemented and noncemented stems, respectively, were: An excellent to good result in 97% versus 88%; thigh pain in 3% versus 40%; subsidence in 0% versus 22%; and endosteal cavitation in 6% versus 12%. For patients with 25 unrevised matched pairs, selected by gender, age, diagnosis, and weight, outcome data also statistically favored cemented over noncemented stems, respectively: an excellent or good result in 25 versus 20 hips; thigh pain in two versus eight hips; and subsidence in none versus six hips. Midterm followup data for these concurrent total hip arthroplasty series of a mid 1980s design revealed prevalence of mechanical failure of 1% for cemented stems and 4% for noncemented stems. Corroborating matched pair comparison neutralized selection bias as a causative factor for these differences. These data indicate contemporary cemented femoral stem fixation is superior to second generation noncemented femoral stem fixation. Controlled comparative studies at midterm to long term followup, such as in this report, are needed to define outcome and indications for current third generation noncemented stem fixation.     

Salvage of failed femoral megaprostheses with allograft prosthesis composites

The records of 11 consecutive adult patients who underwent revision of a failed femoral megaprosthesis (aseptic loosening, nine; periprosthetic fracture, one; and prosthesis fracture, one) to an allograft prosthesis composite were reviewed retrospectively. Complications included radiographic component subsidence in two patients (18%), hip instability in three patients (27%), deep infection in two patients (18%), and allograft fractures in two patients (18%). Five patients (45%) required subsequent reoperations; four patients underwent removal of the allograft prosthesis composite at a mean of 16 months (range, 5-41 months) and one patient (9%) with hip instability underwent revision of the failed megaprosthesis to a constrained acetabulum. Reconstruction of a failed femoral megaprosthesis is a complex problem caused by extensive bone loss and violation of soft tissue attachments. Despite a high complication rate, six patients (55%) remained ambulatory and had mild or no pain at a mean followup exceeding 5.5 years.     

Intracellular distribution of phospholipase C gamma 1 in cell lines with different levels of transformation

PURPOSE OF THE STUDY: To assess after 83 months of follow-up, the results of 19 femoral revisions carried out according to an original method combining a cemented stem and bone reconstruction by means of impacted-morcelized bone allograft protected by a titanium mesh. MATERIALS: Twenty hips (18 patients mean aged 58 at surgery) were included between 1986 and 1991. Five hips had a least one previous prosthetic revision, one hip was revised because of septic loosening. No patient was lost for follow-up, but two had died during the follow-up period: one patient died one month after surgery was excluded, one other died 7 years after the index procedure and was included with his last hip rating. Loss of femoral bone stock was severe according to the SOFCOT four stage rating system: 2 femurs were grade II, 14 grade III, and 3 grade IV. Femoral stem migration was assessed with landmarks recommended by Walker. All the measurements were performed with a digitizer (OrthoGraphics). METHODS: All the procedures were carried out through a posterolateral approach, augmented by 4 trochanteric osteotomies and 5 distal femoral windows. After prosthesis and cement removal, a bone plug was placed into the medullary canal. Then, cancelous bone morcelized allografts were impacted in the femoral defects through the medullary canal. A titanium mesh cylinder was placed into the femur to separate the graft from the cement introduced later to obtain fixation of the revision stem. The stem was extended about 5 centimeters over the distal edge of the grafts in order to bridge the femoral defects. The mesh was extended only in front of the grafts and was used to protect them from excessive cement penetration. RESULTS: Functional improvement was noticeable since the Merle d'Aubigné Hip score improved from 9.8 to 16.3 at follow-up. The pain score improved from 2.1 to 5.5 and walking score from 2.3 to 5. Adverse effects occurred during the first cases and were related to cement removal: 3 greater trochanter fractures, 5 distal femoral perforations and 2 non displaced femoral shaft fractures. The septic revision had recurrence of infection associated with radiolucent lines > 2 millimeters and the only one graft resorption. One trochanteric non-union was observed but no prosthetic dislocation. Only one femoral stem migration (4.4 millimeters) was detected without any other radiographic features of loosening after 9 years of follow-up. This stem was considered as loosed, but was not revised because of few clinical symptoms. Only 2 radiolucent lines less than 2 millimeters at the bone cement interface in Gruen's zones 3 to 5. Likewise, no radiographic feature of stress-shielding was observed. On follow-up X-rays, 3 hips had corticalisation of the grafts, and 12 hips demonstrated normal cancelous trabeculations in the grafts. CONCLUSION: Satisfactory functional and radiographic results were obtained with this method after 5 to 10 years of follow-up instead of severe preoperative femoral bone stock impairement. Likewise, we observed only one recurrence of loosening diagnosed with the help of digitized X-ray examination. Only one significant (> 3.5 mm) femoral stem migration was detected. Radiographic features of femoral reconstruction were observed but without histologic proof of graft integration. This method uses a longer stem than the "Exeter", but avoids a high rate of femoral stem migration and appears compatible with femoral bone reconstruction.     

Effects of design changes on cemented tapered femoral stem fixation

The effects of matte finish and modularity on loosening of tapered stems using the same cementing technique were studied prospectively. In 80 patients, 82 cemented Exeter primary stems were implanted at total hip revision by one surgeon using the same surgical and cementing technique throughout the series. The polished stems behaved differently than the matte surfaced stems behaved. Polished stems subsided in the cement mantle an average of 1 mm at 2 years after implantation, but without subsequent loosening of stems at as long as 12 years after implantation. Matte surfaced stems with metal centralizers had a higher loosening rate, and loss of fixation at the prosthesis to cement interface was identified as an early sign of loosening of these stems. At a mean 6-year followup, there were no revisions nor was there radiographic evidence of loosening of the polished modular stems. It is concluded that matte finish results in increased loosening of tapered stems but the introduction of modularity did not.     

A histologic and biochemical comparison of the interface tissues in cementless and cemented hip prostheses

Thirty-four membranes from 20 cementless and 14 cemented prostheses from 33 patients excised during revision arthroplasty were analyzed for foreign-body reactive processes. As a control, identical analyses were performed using adjacent pseudocapsular tissue taken from 12 patients during revision arthroplasty. Histologically, cementless membranes tended to contain more metal debris, and cemented membranes contained more foreign-body giant cells. Collagenase, gelatinase, prostaglandin E2, and interleukin-1 were measured in conditioned media taken from organ cultures of each interface membrane. Both cementless and cemented membranes released significant levels of gelatinase and collagenase, prostaglandin E2, and interleukin-1 into the conditioned media when compared with control tissues. However, the tissue concentrations were not significantly different between cementless and cemented membranes. Although histologic differences between cementless and cemented interface membranes exist, both share a similar capacity to release bioactive products that can induce bone resorption and cause aseptic loosening of the hip prostheses.     

Expression of gelatinase A and its activator MT1-MMP in the inflammatory periprosthetic response to polyethylene

Wear debris of polyethylene prosthetic components is known to induce a host granulomatous reaction which recruits numerous macrophages and multinucleated giant cells. By releasing cellular mediators of a nonspecific inflammatory reaction, activated phagocytic cells are thought to play a key role in osteolysis leading to aseptic loosening of the prosthesis. Matrix metalloproteinases (MMPs) have been implicated in this destructive process by their ability to degrade extracellular matrix components of bone and adjacent connective tissue. To investigate the roles of gelatinase A, its activator MT1-MMP, and the MMP inhibitors TIMP-1 and TIMP-2 in aseptic loosening of polyethylene prostheses, immunohistochemistry (IHC) and in situ hybridization (ISH) were performed on periprosthetic pseudosynovial interface tissues. Gelatinase A and MT1-MMP were strongly detected immunohistochemically in macrophages and multinucleated giant cells in contact with polyethylene wear debris. In contrast to MT1-MMP, gelatinase A mRNAs were not found in phagocytic cells but in surrounding fibroblasts, thereby suggesting cooperation between macrophages and fibroblasts in this process. While TIMP-1 was expressed essentially in hyperplastic pseudosynoviocytes as assessed by IHC and ISH, TIMP-2, MT1-MMP, and gelatinase A were colocalized in phagocytic cells. These data support the concept of progelatinase A activation involving a trimolecular complex (MT1-MMP-TIMP-2-gelatinase A) mechanism. Thus, this study demonstrated that gelatinase A and its activator might contribute to the aseptic loosening of polyethylene prostheses.     

Bone scan, gallium scan, and hip aspiration in the diagnosis of infected total hip arthroplasty

The difficulty in differentiating aseptic loosening from infection in painful total hip arthroplasty is well recognized. This prompted a review of the efficacy of the preoperative investigations used at the authors' institution. One hundred forty-four patients who underwent revision hip arthroplasty were reviewed. Seventy-two had sequential bone-gallium scan, and/or hip aspiration, and intraoperative Gram stain. These were compared to intraoperative culture as the gold standard. Twenty infected hips were detected on culture. For prediction of infection, the bone-gallium scan had a sensitivity of 38% and a specificity of 100%. Hip aspiration had a sensitivity of 57% and a specificity of 97%. The investigations combined gave a sensitivity of 64% and a specificity of 95%. Intraoperative Gram stain compared with subsequent culture yielded a sensitivity of 23% and a specificity of 100%. Uncemented hips were infected more frequently (47%) than cemented hips (9%), significant at P < .0001. It was concluded that bone-gallium imaging is not an effective method for investigating painful hip prostheses for sepsis and offers no additional advantage over hip aspiration. Intraoperative Gram stain also missed a large number of infections. Other modalities, such as indium-labeled-leukocyte imaging and capsular histologic examination, may be more efficacious. A significant difference in the number of infections found in cemented versus uncemented hips was shown, hence greater vigilance for infection is required when patients present with painful uncemented hip arthroplasties.