Incidence Of Aseptic Loosening Research Articles

Modular fluted tapered stems in two-stage reimplantation of previously infected total hip arthroplasties.

Uncemented implants are now commonly used at reimplantation of a two-stage revision total hip arthoplasty (THA) following periprosthetic joint infection (PJI). However, there is a paucity of data on the performance of the most commonly used uncemented femoral implants - modular fluted tapered (MFT) femoral components - in this setting. This study evaluated implant survival, radiological results, and clinical outcomes in a large cohort of reimplantation THAs using MFT components. We identified 236 reimplantation THAs from a single tertiary care academic institution from September 2000 to September 2020. Two designs of MFT femoral components were used as part of an established two-stage exchange protocol for the treatment of PJI. Mean age at reimplantation was 65 years (SD 11), mean BMI was 32 kg/m2 (SD 7), and 46% (n = 109) were female. Mean follow-up was seven years (SD 4). A competing risk model accounting for death was used. The 15-year cumulative incidence of any revision was 24%. There were 48 revisions, with the most common reasons being dislocation (n = 25) and infection (n = 16). The 15-year cumulative incidence of any reoperation was 28%. Only 13 revisions involved the fluted tapered component (FTC), for a 15-year cumulative incidence of any FTC revision of 8%. Only two FTCs were revised for aseptic loosening, resulting in a 15-year cumulative incidence of FTC revision for aseptic loosening of 1%. Stem subsidence ≥ 5 mm occurred in 2% of unrevised cases. All stems were radiologically stable at most recent follow-up. Mean Harris Hip Score was 69 (SD 20) at most recent follow-up. This series demonstrated that MFT components were durable and reliable in the setting of two-stage reimplantation THA for infection. While the incidence of aseptic loosening was very low, the incidence of any revision was 24% at 15 years, primarily due to dislocation and recurrent PJI.

Cemented versus Cementless Stem Fixation in Revision Total Knee Arthroplasty: A Systematic Review and Meta-Analysis.

The number of revision knee arthroplasties (rTKA) is growing significantly as is the use of intramedullary stems for optimized stability. The choice of the most appropriate stem fixation method is still controversial. The purpose of this meta-analysis is to compare cemented versus cementless stem fixation in rTKA. Publications with patients undergoing rTKA with a follow-up > 24 months were systemically reviewed. Extracted parameters included total revision and failure rates for any reason, incidence of aseptic loosening, periprosthetic infection, and radiolucent lines, as well as the clinical outcome. A statistical regression analysis was then performed on all extracted clinical and radiological outcome data. A total of 35 publications met the inclusion criteria and were included and analyzed. Overall, 14/35 publications compared cementless versus cemented stem fixation, whereas 21/35 publications investigated only one stem fixation method. There were no significant differences in revision (p = 0.2613) or failure rates (p = 0.3559) and no differences in the incidence of aseptic loosening (p = 0.3999) or periprosthetic infection (p = 0.1010). The incidence of radiolucent lines was significantly higher in patients with cemented stems (26.2% versus 18.6%, p < 0.0001). However, no differences in clinical outcomes were observed. No superiority of a specific stem fixation method in rTKA was found. Rates of revision or failure for any reason as well as incidence of aseptic loosening and periprosthetic infection in cemented versus cementless stem fixation showed no significant difference. A higher incidence of radiolucent lines was observed in cemented stem fixation; however, no effect was observed on the clinical outcome.

MODULAR FLUTED TAPERED STEMS IN TWO-STAGE REIMPLANTATION OF PREVIOUSLY INFECTED TOTAL HIP ARTHROPLASTIES: RESULTS AT 15 YEARS

There is a paucity of long-term data on modular fluted tapered (MFT) stems for two-stage reimplantation following periprosthetic joint infection (PJI). The purpose of this study was to evaluate implant survivorship, radiographic results, and clinical outcomes in a large cohort of reimplantation THAs using MFT stems.We identified 236 reimplantation THAs from a single tertiary care academic institution from 2000 to 2020. Two designs of MFT stems were used as part of an established two-stage exchange protocol for the treatment of PJI. Mean age at reimplantation was 65 years, mean BMI was 32 kg/m2, and 46% were female. Median stem diameter was 19 mm, and median stem length was 195 mm. Mean follow-up was 7 years. A competing risk model accounting for death was utilized.The 15-year cumulative incidence of any revision was 24%. There were 48 revisions, with the most common reasons being dislocation (n=25) and PJI (n=16). The 15-year cumulative incidence of any reoperation was 28%. Only 13 revisions involved the fluted tapered portion of the component (FTC), for a 15-year cumulative incidence of any FTC revision of 8%. Only 2 FTCs were revised for aseptic loosening, resulting in a 15-year cumulative incidence of FTC revision for aseptic loosening of 1%. Stem subsidence &gt;5 mm occurred in 2% of unrevised cases, and all stems were radiographically stable at most recent follow-up. Mean HHS was 77 at most recent follow-up.This series demonstrated that MFT stems were durable and reliable even in the setting of two-stage reimplantation for infection. While the incidence of aseptic loosening was very low, the incidence of any revision was 24% at 15 years, primarily caused by dislocation and recurrent PJI.Level of Evidence: IV

Comparison of Contemporary Surgical Indications for Revision Total Knee Arthroplasty between 2005-2011 and 2012-2017 in a Referral Center.

Different causative factors for revision total knee arthroplasty (TKA) surgeries are elucidated in the arthroplasty registry data of different countries and the patient records at tertiary care centers. We aimed to determine the changes in the causes for revision TKAs before and after 2011 (The year that the Musculoskeletal Infection Society proposed a new definition for periprosthetic joint infection) and the changes in the demographics of patients who underwent revision TKAs during the same time intervals. Patients who underwent revision TKAs between 2004 and 2017 were evaluated. A total of 291 patients operated before (period 1, n = 139) and after (period 2, n = 152) 2011 were included, while 53 patients with inconclusive diagnoses were excluded. The demographic data of patients and the causes for revision TKAs were collected and compared between the two periods. Infection was the most common cause of revision TKAs during periods 1 (58%) and 2 (48%). Aseptic loosening (46%) and infection (37%) were the 2 most common causes for late revisions during period 2. Aseptic loosening almost doubled during period 2 compared with that in period 1. Age, sex, and body mass index distribution in patients were similar across both the periods. Although the incidence of aseptic loosening has significantly increased since 2011, infection is still the most common cause for revision knee arthroplasty surgery.

Is three-dimensional\u2013printed custom-made ultra-short stem with a porous structure an acceptable reconstructive alternative in peri-knee metaphysis for the tumorous bone defect?

BackgroundLong-lasting reconstruction after extensive resection involving peri-knee metaphysis is a challenging problem in orthopedic oncology. Various reconstruction methods have been proposed, but they are characterized by a high complication rate. The purposes of this study were to (1) assess osseointegration at the bone implant interface and correlated incidence of aseptic loosening; (2) identify complications including infection, endoprosthesis fracture, periprosthetic fracture, leg length discrepancy, and wound healing problem in this case series; and (3) evaluate the short-term function of the patient who received this personalized reconstruction system.MethodsBetween September 2016 and June 2018, our center treated 15 patients with malignancies arising in the femur or tibia shaft using endoprosthesis with a 3D-printed custom-made stem. Osseointegration and aseptic loosening were assessed with digital tomosynthesis. Complications were recorded by reviewing the patients’ records. The function was evaluated with the 1993 version of the Musculoskeletal Tumor Society (MSTS-93) score at a median of 42 (range, 34 to 54) months after reconstruction.ResultsOne patient who experienced early aseptic loosening was managed with immobilization and bisphosphonates infusion. All implants were well osseointegrated at the final follow-up examination. There are two periprosthetic fractures intraoperatively. The wire was applied to assist fixation, and the fracture healed at the latest follow-up. Two patients experienced significant leg length discrepancies. The median MSTS-93 score was 26 (range, 23 to 30).ConclusionsA 3D-printed custom-made ultra-short stem with a porous structure provides acceptable early outcomes in patients who received peri-knee metaphyseal reconstruction. With detailed preoperative design and precise intraoperative techniques, the reasonable initial stability benefits osseointegration to osteoconductive porous titanium, and therefore ensures short- and possibly long-term durability. Personalized adaptive endoprosthesis, careful intraoperative operation, and strict follow-up management enable effective prevention and treatment of complications. The functional results in our series were acceptable thanks to reliable fixation in the bone-endoprosthesis interface and an individualized rehabilitation program. These positive results indicate this device series can be a feasible alternative for critical bone defect reconstruction. Nevertheless, longer follow-up is required to determine whether this technique is superior to other forms of fixation.

Total hip arthroplasty using highly cross-linked polyethylene in patients aged 50 years and younger : minimum 15-year follow-up.

Highly cross-linked polyethylene (HXLPE) has greatly improved the durability of total hip arthroplasty (THA) in young patients because of its improved wear characteristics. Few studies have followed this population into the second decade, and therefore the purpose of this investigation was to evaluate the clinical outcome for THA patients 50 years of age and younger at a minimum of 15 years postoperatively. The second purpose was to evaluate the radiological findings secondary to wear or mechanical failure of the implant. Between October 1999 and December 2005, 105 THAs were performed in 95 patients (53 female, 42 male) aged 50 years and younger (mean 42 years (20 to 50)). There were 87 patients (96 hips) that were followed for a minimum of 15 years (mean 17.3 years (15 to 21)) for analysis. Posterior approach was used with cementless fixation with a median head size of 28 mm. HXLPE was the acetabular bearing for all hips. Radiographs were evaluated for polyethylene wear, radiolucent lines, and osteolysis. Clinical outcomes showed significant improvement of mean Harris Hip Scores from 52.8 (SD 13.5) preoperatively to 94.8 (SD 7.6) postoperatively. One hip was revised for recurrent instability, and there were no infections. No hips were revised for mechanical loosening or osteolysis. Mean polyethylene linear wear was 0.04 mm/year and volumetric wear was 6.22 mm3/year, with no significant differences between head size or material. Osteolysis was not present in any of the hips. The use of HXLPE in THA for patients aged 50 years and younger has performed exceptionally well without evidence of significant wear causing mechanical loosening or necessitating revision. The radiolucent lines of the acetabular component must be followed to determine the prognostic significance. This investigation represents the longest clinical follow-up of a large, consecutive cohort of patients aged 50 years or younger with THA using HXLPE. This long-term analysis found negligible polyethylene wear, no incidence of aseptic loosening, and excellent clinical outcomes at and beyond 15 years of follow-up. Cite this article: Bone Joint J2021;103-B(7 Supple B):78-83.

The High Flex Total Knee Arthroplasty\u2014Higher Incidence of Aseptic Loosening and No Benefit in Comparison to Conventional Total Knee Arthroplasty: Minimum 16-Years Follow-Up Results

PurposeThis prospective randomized study compares the clinical and radiographic long-term results at least 16 years after total knee arthroplasty (TKA) between a mobile-bearing high flex and a fixed-bearing posterior-stabilized knee.MethodsIn 2000, we included 60 patients who underwent a TKA. Patients were divided into two groups. At the time of the follow-up after a minimum of 16 years (16.5 years ± 0.6), 16 patients had died for causes unrelated to the operation, 15 were lost to the follow-up. Five patients of the high flex group had a revision. The final evaluation included the hospital for special surgery score (HSS) and radiographs. Using the X-rays and the Knee Society Roentgenographic Evaluation and Scoring System, radiolucent lines and the maximal knee flexion were determined.ResultsNo significant differences between the two groups were found. The mean HSS score of LPS group patients was 87.9 (± 10.6) points and that of the high flex group was 93.1 (± 7.4) points. Five patients of the high flex group had undergone a reoperation. One knee was revised for painful mid-flexion instability and the others for symptomatic aseptic loosening of the components.ConclusionThe long-term follow-up does not show any clear benefits and even a higher incidence of implant loosening using the mobile-bearing high-flex knee.

A Comparison of Long-Term Outcomes of Computer-Navigated and Conventional Total Knee Arthroplasty: A Meta-Analysis of Randomized Controlled Trials.

It is not clear whether long-term outcomes differ between computer-navigated and conventional total knee arthroplasty. The purpose of this study was to perform a meta-analysis comparing the radiographic outcomes, the long-term functional outcomes, and survivorship between computer-navigated total knee arthroplasty and conventional total knee arthroplasty. We searched MEDLINE, Embase, and the Cochrane Library to identify studies comparing long-term outcomes between computer-navigated total knee arthroplasty and conventional total knee arthroplasty. Randomized controlled trials with mean follow-up durations of >8 years were included. The meta-analysis compared radiographic outcomes (postoperative alignment), functional outcomes (range of motion and patient-reported outcomes), and survivorship of the 2 techniques. Nine studies were included. A meta-analysis of accuracy revealed better outcomes in computer-navigated total knee arthroplasty when compared with conventional total knee arthroplasty in terms of the sagittal alignment of the femoral component (risk ratio [RR], 0.69; [95% confidence interval (CI), 0.51 to 0.93]; p = 0.02) and the coronal alignment of the tibial component (RR, 0.75 [95% CI, 0.60 to 0.95]; p = 0.02). The mechanical axis of the lower extremity, the coronal alignment of the femoral component, and the sagittal alignment of the tibial component did not differ significantly between the 2 groups. The functional outcomes did not differ significantly between the 2 techniques. Both in terms of the revision rate and the incidence of aseptic loosening, there were no differences between the 2 techniques. Although computer-navigated total knee arthroplasty resulted in better outcomes in postoperative component alignment than conventional total knee arthroplasty, there were no significant differences in long-term functional outcomes and survivorship between the 2 techniques. To fully evaluate the utility of computer navigation in total knee arthroplasty, additional randomized controlled studies including diverse ethnic groups and countries, as well as studies evaluating the correlation between postoperative alignment and long-term survivorship, are necessary. Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Uncemented, curved, short endoprosthesis stem for distal femoral reconstruction: early follow-up outcomes

BackgroundUncemented endoprosthetic knee replacement has become a mainstream treatment for malignant tumours of the distal femur. Most femoral stems, however, are straight and therefore poorly fit the anteriorly bowed curvature of the femur. To address this issue, we used a short, curved, uncemented press-fit femoral stem and evaluated its short-term outcomes after reconstruction of the distal femur.MethodsForty-two patients underwent distal femur replacement using curved press-fit stem. To assess the interface, we measured the axial length of the press-fit area and the perpendicular distance of the radiolucent area between the stem and bone on digital images obtained using tomosynthesis with Shimadzu Metal Artefact Reduction Technology (T-SMART). Postoperative complications and oncological outcomes were monitored at each follow-up visit.ResultsOf the 42 patients enrolled in the study, two had cancer-related deaths and one had local tumour recurrence. The minimum follow-up time of the surviving patients was 24 months, with no incidence of aseptic loosening or mechanical failure of the prosthesis. The average effective contact length between the press-fit stem and bone was 74.0 mm, with nearly undetectable radiolucent gaps between the implant and the bone on medial-lateral and anteroposterior views.ConclusionsOver the short term, uncemented, curved, short stem provides a stable bone-prosthesis interface without any aseptic loosening.

Outcomes of dual mobility components in total hip arthroplasty: a systematic review of the literature.

Instability remains a challenging problem in both primary and revision total hip arthroplasty (THA). Dual mobility components confer increased stability, but there are concerns about the unique complications associated with these designs, as well as the long-term survivorship. We performed a systematic review of all English language articles dealing with dual mobility THAs published between 2007 and 2016 in the MEDLINE and Embase electronic databases. A total of 54 articles met inclusion criteria for the final analysis of primary and revision dual mobility THAs and dual mobility THAs used in the treatment of fractures of the femoral neck. We analysed the survivorship and rates of aseptic loosening and of intraprosthetic and extra-articular dislocation. For the 10 783 primary dual mobility THAs, the incidence of aseptic loosening was 1.3% (142 hips); the rate of intraprosthetic dislocation was 1.1% (122 hips) and the incidence of extra-articular dislocation was 0.46% (41 hips). The overall survivorship of the acetabular component and the dual mobility components was 98.0%, with all-cause revision as the endpoint at a mean follow-up of 8.5 years (2 to 16.5). For the 3008 revision dual mobility THAs, the rate of aseptic acetabular loosening was 1.4% (29 hips); the rate of intraprosthetic dislocation was 0.3% (eight hips) and the rate of extra-articular dislocation was 2.2% (67 hips). The survivorship of the acatabular and dual mobility components was 96.6% at a mean of 5.4 years (2 to 8). For the 554 dual mobility THAs which were undertaken in patients with a fracture of the femoral neck, the rate of intraprosthetic dislocation was 0.18% (one hip), the rate of extra-articular dislocation was 2.3% (13 hips) and there was one aseptic loosening. The survivorship was 97.8% at a mean of 1.3 years (0.75 to 2). Dual mobility articulations are a viable alternative to traditional bearing surfaces, with low rates of instability and good overall survivorship in primary and revision THAs, and in those undertaken in patients with a fracture of the femoral neck. The incidence of intraprosthetic dislocation is low and limited mainly to earlier designs. High-quality, prospective, comparative studies are needed to evaluate further the use of dual mobility components in THA. Cite this article: Bone Joint J 2018;100-B:11-19.

Fixation of stem in revision of total knee arthroplasty: cemented versus cementless—a meta-analysis

Revision of total knee arthroplasty (TKA) is growing rapidly all over the world. The introduction of intramedullary stems for additional stability in revision is well accepted by most of the surgeons, while the philosophy of stem fixation is still under controversy. A meta-analysis was performed to compare the survivorship of revised implants with regard to a cemented or cementless stem fixation. Publications with patients who underwent revision TKA with minimum 24-month follow-up were systematically reviewed. Type of intramedullary stem fixation, failure rate for any reason, incidence of aseptic loosening and infection were extracted with follow-up interval specified. Random-effects meta-analysis was used to aggregate incidence data, which was compared between different fixation groups by fitting of logistic regression model. Seventeen observational studies were included in this meta-analysis. There was a similar likelihood of failure for any reason (risk ratio, RR 0.97), general reoperation (RR 1.02), aseptic loosening (RR 1.0) and infection (RR 1.0) in cemented stem fixation group compared to cementless stem fixation group with follow-up <60months. When follow-up period extend to more than 60months, the same likelihood was observed as 0.98, 0.96, 0.97 and 0.98, respectively. There was no significant difference in any of these comparisons of survival-related indices. There was no significant difference in failure for any reason, reoperation, aseptic loosening and infection between revision TKA with cemented or cementless stem fixation. Based on the available literature, no superiority of any type of stem fixation was found. If follow-up period was neglected, aseptic loosening would be the leading reason for pain and dysfunction of patient undertaken revision TKA. Systematic review of Level IV, Therapeutic studies, Level IV.

Advantages of a Cementless Unicompartmental Knee Arthroplasty Approach

Medial unicompartmental knee arthroplasty (UKA) is a procedure designed for resurfacing the medial compartment in isolated medial compartment degenerative joint disease. Many long-term studies have reported the success of UKA. Despite recent interest and isolated reports of success, significant issues still exist today with early failure in UKA. Medial UKA is a promising alternative to total knee arthroplasty for isolated medial compartment degenerative joint disease. Potential advantages of this treatment option compared with total knee arthroplasty include improved patient satisfaction, more consistent return to sporting activities, quicker recovery, decreased complication risk, and greater range of motion. With the introduction of robotic arm tools to help improve accuracy and reliability of implant position, we may be able to decrease failure rates in UKAs. In addition, cementless technologies are promising approaches to improve the durability of UKA fixation. Robotic arm techniques coupled with cementless fixation strategies may dramatically reduce the incidence of aseptic loosening in UKA.

The dog as a preclinical model to evaluate interface morphology and micro-motion in cemented total knee replacement

This study investigated cemented fixation of the tibial component from a canine total knee replacement preclinical model. The objective was to determine the local morphology at the material interfaces (implant, cement, bone) and the local relative micro- motion due to functional loading following in vivo service. Five skeletally mature research dogs underwent unilateral total knee replacement using a cemented implant system with a polyethylene (PE) monobloc tibial component. Use of the implanted limb was assessed by pressure-sensitive walkway analysis. At 60 weeks post-surgery, the animals were euthanatized and the tibia sectioned en bloc in the sagittal plane to create medial and lateral specimens. High resolution imaging was used to quantify the morphology under the tray and along the keel. Specimens were loaded to 50% body weight and micro- motions at the PE-cement and cement-bone interfaces were quantified. There was significantly (p = 0.002) more cement-bone apposition and interdigitation along the central keel compared to the regions under the tray. Cavitary defects were associated with the perimeters of the implant (60 ± 25%). Interdigitation fraction was negatively correlated with cavitary defect fraction, cement crack fraction, and total micro-motion. Achieving good interdigitation of cement into subchondral bone beneath the tibial tray is associated with improved interface morphology and reduced micro-motion; features that could result in a reduced incidence of aseptic loosening. Multiple drill holes distributed over the cut tibial surface and adequate pressurization of the cement into the subchondral bone should improve fixation and reduce interface micromotion and cavitary defects.

Gender is a Significant Factor for Failure of Metal-on-Metal Total Hip Arthroplasty

Metal-on-metal (MoM) articulations offers low wear, larger head size, and increased stability. Reports of early failure are troubling and include failure of ingrowth and metal articulation problems such as metallosis, hypersensitivity, pseudotumor, and unexplained pain. This study investigates the survivorship of modern MoM articulations by gender. We reviewed 1589 primary MoM THA in 1363 patients, with minimum 2-year follow-up for 1212 hips. Follow-up averaged 60 months. There were 643 female patients and 719 male patients. The incidence of cup revision was significantly higher in women than in men (8.2% vs 2.7%; P = .0000), as was incidence of aseptic loosening (4.3% vs 1.1%; P = .0006), and failure for metal-bearing complications (2.2% vs 0.6%; P = .0126). There appear to be gender factors influencing the success of MoM THA, which may include hormonal, anatomic, or functional differences.

Short‐Term Aseptic Loosening of the Femoral Component in Canine Total Hip Replacement: Effects of Cementing Technique on Cement Mantle Grade

To evaluate the effects of different cementing techniques on radiographic cement mantle grade and short-term aseptic loosening of the femoral component in canine total hip replacement (THR). Retrospective study. Radiographs of 284 dogs that had THR. Immediate postoperative radiographs of 284 dogs that had cemented THR were reviewed by 4 surgeons and 1 radiologist and assigned a cement mantle grade using a 4-grade classification system. Dog age and weight at surgery, cementing technique (1st, 2nd, 3rd generation), complications (type and timing), and follow-up time were retrieved and analyzed. Mean cement mantle score for 2nd generation technique was significantly higher than 3rd generation technique and both were significantly higher than 1st generation technique (P<.001). Aseptic loosening was the 2nd most common complication observed with an incidence of 2.1%. Mean time from surgery to last follow-up examination was 122 days. No statistically significant difference in incidence of aseptic loosening was identified among different cement mantle grades or cementing techniques. Advanced cementing techniques resulted in better cement mantles based on grading of immediate postoperative radiographs, however grading did not predict short-term aseptic loosening. Cementing technique seemingly did not affect the incidence of short-term aseptic loosening of the femoral component for dogs in this study. Our study suggests that advances in cementing technique may result in improvements in the radiographic grade of cement mantles. With respect to aseptic loosening of the femoral component, our data only suggest that short-term (3 months-3 years) loosening cannot be predicted by immediate postoperative radiographic evaluation of cement mantle.

Assessing the dog as a model for human total hip replacement

Post-mortem retrieval of canine, cemented femoral components was analysed to assess the performance of these implants in the dog as a model for human total hip replacement (THR). Mechanical testing and radiological analysis were performed to determine the stability of the implant and the quality of the cement. Thirty-eight implants from 29 dogs were retrieved after time intervals ranging from 0.67 to 11.67 years. The incidence of aseptic loosening was 63.2%, much higher than in human patients (6% in post-mortem studies). Failure of the femoral implants began with debonding at the cement-metal interface, similar to that in implants in man. The incidence of aseptic loosening was much lower in bilateral than in unilateral implants. Significant differences were observed for three different designs of implant. While the dog remains the animal model of choice for THR, results from this study provide insight into interspecies differences in the performance of implants. For example, the performance of THR in dogs should be compared with that in young rather than in elderly human patients.

Prosthetic Survival and Functional Evaluation in Prosthetic Reconstruction of Malignant Bone Tumors of the Proximal Tibia

Purpose: This study retrospectively analyzed the prosthetic survival and functional results after a prosthetic reconstruction for malignant bone tumors of the proximal tibia. Materials and Methods: Thirty-five patients (32 osteosarcomas and 3 chondrosarcomas) were followedup for an average 72 months (24-167 months). A gastrocnemius flap was transferred in 12 patients and cement fixation of the stem was performed in 10. More than 40% of the bone length was resected in 12 patients. Results: Three patients had died of the disease at the time of the final follow-up. There were one local recurrence and five distant metastases. The major complications were infection (5), aseptic loosening (5) and periprosthetic fractures (1). Gastrocnemius flap affected the incidence of a deep infection in the proximal tibia (17.4% vs. 8.3%) but there were no statistical correlation. A resection of >40% of the involved tibia increased the incidence of aseptic loosening (p=0.002). The rate of prosthetic survival was 72% at 5 years and 58% at 10 years. The functional score at the final follow-up was 81% (43-93%). Conclusion: A prosthetic reconstruction in the proximal tibia showed acceptable oncologic and functional outcomes in patients at an intermediate term follow-up. Infection and loosening were the main factors threatening the survival of the prosthesis.

Polyethylene Wear and Osteolysis in Uncemented Acetabular Component

Purpose: To investigate the influence of the linear wear rate of polyethylene, the osteolysis threshold of the linear wear rate, and the related factors on polyethylene wear in an uncemented metal-backed-cup of a primary total hip arthroplasty. Materials and Methods: This study examined 87 hips from 75 patients (57 men and 18 women) who had undergone a primary total hip arthroplasty with a minimum follow-up of five years. The mean age was 47.3 years (range, 25-68 years). The mean follow up period was 90 months (range, 60-148 months). The most frequent diagnosis was avascular necrosis of the femoral head. 18 Harris-Galante I and 69 Harris-Galante II cups, were used on the acetabular side, and 66 Anatomic and 21 Harris-Galantestems were used on the femoral side. Radiographic polyethylene wear was estimated using the method reported by Livermore, and the above mentioned factors that influence polyethylene wear were investigated and analyzed statistically. Results: The overall mean linear wear rate of polyethylene was 0.21 mm/year. The linear wear rate of 22 hips with osteolysis and 65 hips without osteolysis was 0.29 mm/year and 0.12 mm/year respectively, showing a significant difference (p=0.001). The patients with high activity had a significantly higher mean linear wear rate (0.28 mm/year) than that those patients with low activity (0.16 mm/year) (p=0.048). Patients younger than 40 year-old had a significantly higher mean linear wear rate (0.23 mm/year) than the patients older than 40 year-old (0.19 mm/year) (p=0.049). However, there were no correlations between the mean linear wear rate and gender, weight, diagnosis, the type of cup and the thickness of the polyethylene. Conclusion: The polyethylene wear rate in an uncemented metal-backed-cup was significantly affected by age and the activity of the patients, which strongly influenced the development of osteolysis. Therefore, in order to reduce the incidence of aseptic loosening due to osteolysis in young patients with high activity, a bearing surface with mean linear wear rate of 0.12 mm/year or less is recommended.

The management of severe acetabular bone loss using structural allograft and acetabular reinforcement devices

The cases of 37 acetabular reconstructions in 35 patients with major structural pelvic bone loss were reviewed. At an average follow-up of 7.1 years, patients rated their results as excellent in 12 cases (32.4%), good in 22 (59.5%), fair in 2 (5.4%), and poor in 1 (2.7%). Thirty-four cases (91.9%) were classified as a clinical success. Thirty-six allografts (97.3%) had radiographic evidence of full incorporation. Of the unrevised hips, 1 (2.7%) was classified as definitely loose, 2 (5.4%) as probably loose, and 4 (10.8%) as possibly loose. One revision of an acetabular component was required because of late sepsis. This is the first reported series on the use of acetabular reinforcement devices with solid bulk allograft covering more than 50% of the socket. The allograft is protected in the early postoperative period, superior migration of the cup is virtually eliminated as a complication, and the incidence of aseptic loosening is greatly diminished.

Pharmacologic inhibition of particulate-induced bone resorption.

In this study, a rat calvaria/macrophage co-culture model was used to study the effects of various agents upon bone resorption induced by macrophage exposure to bone cement particles. The experimental group consisted of calvaria bone disks set in tissue culture medium on stainless-steel platforms into wells with macrophages adherent to the bottom which are exposed to the particles. Tumor necrosis factor alpha (TNF-alpha), prostaglandin E2 (PGE2), and calcium 45 (Ca45 were released in significant amounts in this system. Interleukin 1 alpha (IL-1 alpha) was not detected. Indomethacin inhibited the production of PGE2, but did not affect TNF release or inhibit the release of Ca45. Anti-TNF antibody neutralized the presence of TNF to undetectable levels, but did not affect PGE2 release or inhibit Ca45 release. The addition of calcitonin did not inhibit Ca45 release by calvaria. In contrast, the addition of disodium pamidronate, a member of the bisphosphonate family, was effective in inhibiting the release of Ca45 even after 96 h of incubation. In prior studies, incubation of calvaria in conditioned medium from macrophages exposed to cement particles led to resorption through a mechanism which is dependent upon TNF production by macrophages, and PGE2 production by cells in bone. In this two-way system, in which macrophages and cells in bone are allowed to interact, this dependency was no longer evident. Pamidronate was the only agent tested which suppressed the increase in bone resorption associated with macrophage exposure to bone cement particles to levels which were not significantly different from unexposed calvaria. By delaying or preventing bone resorption associated with macrophage exposure to bone cement particles, bisphosphonates may have a clinical role in cemented joint arthroplasty by decreasing the rate or incidence of aseptic loosening and prolonging implant longevity.