Outcome of Charnley total hip replacement across a single health region in England: the results at five years from a regional hip register

Global mapping of institutional and hospital-based (Level II-IV) arthroplasty registries: a scoping review

PURPOSE

Four joint arthroplasty registries (JARs) levels exist based on the recorded data type. Level I JARs are national registries that record primary data. Hospital or institutional JARs (Level II-IV) document further data (patient-reported outcomes, demographic, radiographic). A worldwide list of Level II-IV JARs must be created to effectively assess and categorize these data.

METHODS

Our study is a systematic scoping review that followed the PRISMA guidelines and included 648 studies. Based on their publications, the study aimed to map the existing Level II-IV JARs worldwide. The secondary aim was to record their lifetime, publications' number and frequency and recognise differences with national JARs.

RESULTS

One hundred five Level II-IV JARs were identified. Forty-eight hospital-based, 45 institutional, and 12 regional JARs. Fifty JARs were found in America, 39 in Europe, nine in Asia, six in Oceania and one in Africa. They have published 485 cohorts, 91 case-series, 49 case-control, nine cross-sectional studies, eight registry protocols and six randomized trials. Most cohort studies were retrospective. Twenty-three per cent of papers studied patient-reported outcomes, 21.45% surgical complications, 13.73% postoperative clinical and 5.25% radiographic outcomes, and 11.88% were survival analyses. Forty-four JARs have published only one paper. Level I JARs primarily publish implant revision risk annual reports, while Level IV JARs collect comprehensive data to conduct retrospective cohort studies.

CONCLUSIONS

This is the first study mapping all Level II-IV JARs worldwide. Most JARs are found in Europe and America, reporting on retrospective cohorts, but only a few report on studies systematically.

Adverse reaction to metal debris due to fretting corrosion between the acetabular components of modular dual-mobility constructs in total hip replacement: a systematic review and meta-analysis

Modular dual-mobility (MDM) constructs can be used to reduce dislocation rates after total hip replacement (THR). However, there are concerns about adverse reaction to metal debris (ARMD) as a result of fretting corrosion between the metal liner and shell. This systematic review reports outcomes following THR using MDM components. It was registered with PROSPERO and conducted in line with Cochrane and PRISMA recommendations.Sixteen articles were included overall, with meta-analysis performed on relevant subsets using a random intercept logistic regression model. Estimated median incidence of ARMD requiring revision surgery within study follow-up period was 0.3% (95% CI 0.1 - 1.8%, from 11 cohort studies containing 1312 cases).Serum metal ion levels were mildly raised in 7.9% of cases, and significantly raised in 1.8%, but there was no correlation with worse clinical hip function scores within studies. Dislocation rate was 0.8%. Revision rate was 3.3%.There are mixed reports of wear on the backside of the metal liner from the acetabular shell and screw heads. Both implant design and component malseating are implicated, but currently it is unclear to what extent each factor is responsible.Studies were poor quality with high risk of confounding, especially from trunnion corrosion. We have made recommendations for further work. In the meantime, surgeons should be aware of the potential risk of ARMD when considering using an MDM prosthesis, and, if selecting one, must ensure proper seating of the liner and screws intraoperatively. Cite this article: EFORT Open Rev 2021;6:343-353. DOI: 10.1302/2058-5241.6.200146.

The Prevention of Periprosthetic Joint Infection in Primary Total Hip Arthroplasty Using Pre-Operative Chlorhexidine Bathing

Periprosthetic joint infection (PJI) after total hip arthroplasty (THA) is a devastating complication. The aim of this study was to investigate whether preoperative bathing using chlorhexidine gluconate (CHG) before THA can effectively reduce the postoperative PJI rate. A total of 933 primary THA patients, with the majority being female (54.4%) were included in the study. Primary THA patients who performed preoperative chlorhexidine bathing were assigned to the CHG group (190 subjects), and those who did not have preoperative chlorhexidine bathing were in the control group (743 subjects). The effects of chlorhexidine bathing on the prevention of PJI incidence rates were investigated. Differences in age, sex, and the operated side between the two groups were not statistically significant. Postoperative PJI occurred in four subjects, indicating an infection rate of 0.43% (4/933). All four infected subjects belonged to the control group. Although the PJI cases were significantly more in the control group than in the CHG group, statistical analysis revealed no statistical significance in the risk of PJI occurrence between the two groups (p = 0.588). Preoperative skin preparation by bathing with a 2% chlorhexidine gluconate cleanser did not produce significant effects on the prevention of postoperative PJI in primary THA.

Treatment of secondary hip arthritis from shell fragment and gunshot injury in the Syrian civil war

Background

In gunshot and shell fragment injuries to the hip joint, orthopedic intervention includes wound assessment and care, osteosynthesis of fractures, and avoiding of infection and osteoarthritis. Individuals injured in the Syrian civil war were frequently transferred to the authors’ institution in neighboring city. Orthopedic trauma exposures were determined in approximately 30% of these patients. The aim of this study was to evaluate the outcomes of the patients with secondary hip arthritis due to prior gunshot and shell fragment (shrapnel) injuries who underwent primary total hip arthroplasty.

Methods

This retrospective study reviewed 26 patients (24 males, 2 females) who underwent hip arthroplasty due to prior gunshot and shell fragment injuries from November 2013 to January 2019. For all patients, the Harris Hip Score (HHS) was evaluated preoperatively and after surgery.

Results

Mean age was 31.5 (range, 19–48) years. The mean preoperative HHS was 52.95 points, and the mean postoperative HHS was 79.92 points at the final follow-up after surgery. Patients with shell fragment injuries to the hip joint had higher infection rates, but it is not statistically significant.

Conclusions

An anatomic reduction of the fracture may not be possible in these cases as a result of significant bone and/or cartilage loss. Total hip arthroplasty can be done after gunshot- and shell fragment-related posttraumatic arthritis. It is an effective treatment choice to reduce pain and improve function, but the surgeon must be very careful because of high rate of infection.

Body mass index, hip function and surgeon volume are independent predictors of dislocation: an analysis of 4334 total hip replacements

The aim of this study was to identify pre-operative and intra-operative factors that are predictive of dislocation following primary total hip replacement (THR). Data were prospectively collected for a consecutive series of 4334 THRs undertaken over a 14-year period. Ninety-eight (2.3%) of the 4334 patients had one or more dislocation post-operatively. A body mass index (BMI) of ≥ 35 (p < 0.001), a Harris Hip Score (HHS) of ≤ 41 (p < 0.001) and a low-volume surgeon (p < 0.001), which was defined as performing fewer than 43 THRs per annum, were identified as independent predictors of dislocation using logistic regression analysis. Using these three variables in differing combinations the risk of dislocation varied from 0.5 to 10.4%. Patients at high risk of dislocation, with a BMI of ≥ 35 and a pre-operative HHS of ≤ 41, undergoing surgery by a low-volume surgeon had a dislocation rate of 10.5%, but this decreased to 2.3% when operated on by a high-volume surgeon. These risk factors could be used to identify patients at high risk of dislocation, and modification of these factors, such as weight loss to achieve a BMI of ≤ 35 or referral to a high-volume surgeon, may decrease the risk of dislocation and the resulting secondary morbidity.

Rivaroxaban and early periprostethic joint infection: our experience

BACKGROUND AND AIM OF THE WORK

Periprostethic joint infection (PJI) is a severe post-operative complication after Primary Total Hip Arthroplasty (THA). According to the classification of PJI early acute PJI occurs within 4 weeks from surgery. Some authors think that Rivaroxaban is a risk factor in the incidence of early acute PJI. We analyze our experience about this item.

MATERIALS AND METHODS

We analyze our experience from 1st January 2015 to 31th December 2016. We consider all consecutive hip arthroplasty implants in this period.

RESULTS

In the 205 patients analysed we not find early acute PJI in Rivaroxaban group nor in the others assuming another kind of thromboprophylaxis.

CONCLUSIONS

In our series there is no evidence of association between Rivaroxaban and early acute PJI. This is a retrospective cohort study, so we need more studies and more robust experimental designs to confirm these results.

Current Concepts of Using Large Femoral Heads in Total Hip Arthroplasty

Instability and dislocation after total hip arthroplasty are the most common causes of revisions and major complications for failure of inserted prostheses, leading to a reduction in quality of life. Because the use of artificial femoral head sizes smaller than patient's own size is the important cause for dislocation, the use of large femoral head have increased. Femoral head sizes greater than 32 mm offer multiple advantages in physical function and activity levels of patients by improving hip stability, decreasing dislocation rate and increasing range of motion. However, various concerns are encountered including wear debris generation at the trunnion-bore interface and increases in frictional torque and stress over the component-bone interface when using larger head sizes. So, the use of femoral head sizes less than 40 mm is recommended.

Rivaroxaban Use for Thrombosis Prophylaxis Is Associated With Early Periprosthetic Joint Infection

BACKGROUND

Periprosthetic joint infection is a disastrous complication after total hip arthroplasty (THA) and total knee arthroplasty (TKA). The use of certain agents to prevent deep vein thrombosis after arthroplasty has been linked to an increased risk of adverse effects including wound drainage and infection. Adverse effects of one alternative, rivaroxaban, was studied in a single community hospital.

METHODS

International Classification of Diseases, Clinical Modification 9 codes were used to identify primary THAs and TKAs in an administrative database at one large-volume community hospital performed in 2012. Patients were divided into 2 groups: the study group received rivaroxaban, whereas the control group received another form of chemical thromboprophylaxis for at least 2 weeks postoperative. Demographics, risk factors, and illness severity scores were collected for each group. The primary measured outcome was the incidence of deep surgical site infection (SSI) within 30 days postoperative.

RESULTS

A total of 639 TKA or THA patients were included, with 159 patients who received rivaroxaban and 480 who received another form of chemical thromboprophylaxis. There were no significant differences between groups regarding demographics, risk factors, or illness severity scores. Incidence of early deep SSI in the rivaroxaban group was higher than in the control group (2.5% vs 0.2%; P < .015).

CONCLUSION

The use of rivaroxaban for thromboprophylaxis led to a significantly increased incidence of deep SSI in a continuous series of patients undergoing primary THA and TKA in a single institution.

Smoking and risk of prosthesis-related complications after total hip arthroplasty: a meta-analysis of cohort studies

Objective

Increasing evidence suggests that smoking may increase the incidence of prosthesis-related complications after total hip arthroplasty (THA). We performed a meta-analysis of cohort studies to quantitatively evaluate the association between smoking and the risk of prosthesis-related complications after THA.

Methods

Relevant articles published before August 15, 2014, were identified by searching the PubMed, EMBASE and Cochrane library databases. Pooled risk ratios (RRs) or weighted mean differences (WMDs) with 95% confidence intervals (CIs) were calculated with either a fixed- or random-effects model.

Results

Six cohort studies, involving a total of 8181 participants, were included in the meta-analysis. Compared with the patients who never smoked, smokers had a significantly increased risk of aseptic loosening of prosthesis (summary RR=3.05, 95% CI: 1.42-6.58), deep infection (summary RR=3.71, 95% CI: 1.86-7.41) and all-cause revisions (summary RR=2.58, 95% CI: 1.27-5.22). However, no significant difference in the risk of implant dislocation (summary RR= 1.27, 95% CI: 0.77-2.10) or length of hospital stay (WMD=0.03, 95% CI: -0.65-0.72) was found between smokers and nonsmokers.

Conclusions

Smoking is associated with a significantly increased risk of aseptic loosening of prosthesis, deep infection and all-cause revisions after THA, but smoking is not correlated with a risk of implant dislocation or the length of hospital stay after surgery.

Hip resurfacing versus total hip arthroplasty: a systematic review comparing standardized outcomes

BACKGROUND

Metal-on-metal hip resurfacing was developed for younger, active patients as an alternative to THA, but it remains controversial. Study heterogeneity, inconsistent outcome definitions, and unstandardized outcome measures challenge our ability to compare arthroplasty outcomes studies.

QUESTIONS/PURPOSES

We asked how early revisions or reoperations (within 5 years of surgery) and overall revisions, adverse events, and postoperative component malalignment compare among studies of metal-on-metal hip resurfacing with THA among patients with hip osteoarthritis. Secondarily, we compared the revision frequency identified in the systematic review with revisions reported in four major joint replacement registries.

METHODS

We conducted a systematic review of English language studies published after 1996. Adverse events of interest included rates of early failure, time to revision, revision, reoperation, dislocation, infection/sepsis, femoral neck fracture, mortality, and postoperative component alignment. Revision rates were compared with those from four national joint replacement registries. Results were reported as adverse event rates per 1000 person-years stratified by device market status (in use and discontinued). Comparisons between event rates of metal-on-metal hip resurfacing and THA are made using a quasilikelihood generalized linear model. We identified 7421 abstracts, screened and reviewed 384 full-text articles, and included 236. The most common study designs were prospective cohort studies (46.6%; n = 110) and retrospective studies (36%; n = 85). Few randomized controlled trials were included (7.2%; n = 17).

RESULTS

The average time to revision was 3.0 years for metal-on-metal hip resurfacing (95% CI, 2.95-3.1) versus 7.8 for THA (95% CI, 7.2-8.3). For all devices, revisions and reoperations were more frequent with metal-on-metal hip resurfacing than THA based on point estimates and CIs: 10.7 (95% CI, 10.1-11.3) versus 7.1 (95% CI, 6.7-7.6; p = 0.068), and 7.9 (95% CI, 5.4-11.3) versus 1.8 (95% CI, 1.3-2.2; p = 0.084) per 1000 person-years, respectively. This difference was consistent with three of four national joint replacement registries, but overall national joint replacement registries revision rates were lower than those reported in the literature. Dislocations were more frequent with THA than metal-on-metal hip resurfacing: 4.4 (95% CI, 4.2-4.6) versus 0.9 (95% CI, 0.6-1.2; p = 0.008) per 1000 person-years, respectively. Adverse event rates change when discontinued devices were included.

CONCLUSIONS

Revisions and reoperations are more frequent and occur earlier with metal-on-metal hip resurfacing, except when discontinued devices are removed from the analyses. Results from the literature may be misleading without consistent definitions, standardized outcome metrics, and accounting for device market status. This is important when clinicians are assessing and communicating patient risk and when selecting which device is most appropriate for individual patients.

Prevalence of periprosthetic osteolysis after total hip replacement in patients with rheumatic diseases

Periprosthetic osteolysis (PO) is a frequent complication in patients with joint implants. There are no data regarding the prevalence of PO in patients with rheumatoid arthritis (RA), juvenile chronic arthritis (JCA), ankylosing spondylitis (AS), and osteoarthritis (OA).

Monitoring the one year postoperative infection rate after primary total hip replacement

PURPOSE

Infection of a total hip replacement is potentially a devastating complication. Statistical process control methods have been generating interest as a means of improving the quality of healthcare, and we report our experience with the implementation of such a method to monitor the one year infection rate after primary total hip replacement.

METHOD

Infection was defined as the growth of the same organism in cultures of at least two aspirates or intra-operative specimens, or growth of one pathogen in a patient with local signs of infection such as erythema, abscess or draining sinus tract. The cumulative summation test (CUSUM test) was used to continuously monitor the one year postoperative infection rate. The target performance was 0.5% and the test was set to detect twice that rate.

RESULTS

Over the three year study period, 2006 primary total hip replacements were performed. Infection developed within one year after surgery in eight (0.4%) hips. The CUSUM test generated no alarms during the study period, indicating that there was no evidence that the process was out of control.

CONCLUSION

The one year infection rate after primary total hip replacement was in control. The CUSUM test is a useful method to continuously ensure that performance is maintained at an adequate level.

Elective hip and knee arthroplasty and the effect of rivaroxaban and enoxaparin thromboprophylaxis on wound healing

INTRODUCTION

Rivaroxaban is the first licensed oral direct inhibitor of factor Xa. Recent studies from the RECORD trials suggest rivaroxaban has superior efficacy compared to enoxaparin in preventing venous thromboembolism (VTE) with no significant increase in the major bleeding risk. Concerns remain regarding the incidence of minor bleeding, consequent delayed wound healing and subsequent risk of infection. The aim of this observational study was to assess the incidence of post-operative complications in patients receiving either rivaroxaban or enoxaparin thromboprophylaxis following elective hip and knee arthroplasty.

METHODS

A total of 258 patients undergoing elective total hip or knee arthroplasty within one NHS Trust were included. A total of 202 subjects (mean age, 70.7 years ± 10.0, 43 % men) received a daily dose of 10 mg of oral rivaroxaban and 56 (mean age, 70.9 years ± 9.8, 39 % men) had a daily subcutaneous injection of 40 mg of enoxaparin as thromboprophylaxis. Endpoints included VTE (deep vein thrombosis and pulmonary embolism), haemorrhagic wound complications, hospital re-admission, requirement for blood transfusion, minor and major bleeding and death.

RESULTS

There were no significant differences in the incidence of VTE, requirement for blood transfusion and readmission rate between rivaroxaban and enoxaparin-treated patients. The incidence of minor bleeding (2.0 vs. 0 %) and haemorrhagic wound complications (5.0 vs. 1.8 %) were non-significantly higher in the rivaroxaban-treated group. There were no cases of pulmonary embolism, major bleeding or death in either group.

CONCLUSION

Our experience with rivaroxaban in elective hip and knee arthroplasty showed no significant difference in the incidence of VTE or major bleeding. There was, however, a tendency to greater risk of minor bleeding and wound complications that were largely haemorrhagic in nature, which may have reached significance in a larger study.

Cyclodextrin-erythromycin complexes as a drug delivery device for orthopedic application

Background

Erythromycin, a hydrophobic antibiotic used to treat infectious diseases, is now gaining attention because of its anti-inflammatory effects and ability to inhibit osteoclasts formation. The aim of this study was to explore a cyclodextrin-erythromycin (CD-EM) complex for sustained treatment of orthopedic inflammation.

Methods and results

Erythromycin was reacted with β-cyclodextrin to form a nonhost-guest CD-EM complex using both kneading and stirring approaches. Physiochemical measurement data indicated that erythromycin and cyclodextrin formed a packing complex driven by intermolecular forces instead of a host-guest structure due to the limited space in the inner cavity of β-cyclodextrin. The CD-EM complex improved the stability of erythromycin in aqueous solution and had a longer duration of bactericidal activity than free erythromycin. Cytotoxicity and cell differentiation were evaluated in both murine MC3T3 preosteoblast cells and RAW 264.7 murine macrophage cells. The CD-EM complex was noncytotoxic and showed significant inhibition of osteoclast formation but had little effect on osteoblast viability and differentiation.

Conclusion

These attributes are especially important for the delivery of an adequate amount of erythromycin to the site of periprosthetic inflammation and reducing local inflammation in a sustained manner.

Pre-operative expectation predicts 12-month post-operative outcome among patients undergoing primary total hip replacement in European orthopaedic centres

OBJECTIVE

Patients' expectations of surgery may be related to outcomes of joint replacement. The aims of this study were to: (1). Identify patient characteristics associated with pre-operative expectations of total hip replacement (THR); (2). Explore whether pre-operative expectations predict surgical outcomes 12-months post-THR.

METHOD

The European collaborative database of cost and practice patterns of THR (EUROHIP) study consists of 1327 consenting patients coming to primary THR for osteoarthritis (OA) across 20 European orthopaedic centres. Ordered logistic regression modelling was used to look at the association between patients pre-operative expectations and baseline characteristics (age, sex, education, American Society of Anaesthesiologists (ASA) status, Kellgren & Lawrence (K&L) grade, body mass index (BMI), medication use, Western Ontario and McMaster Universities Osteoarthritis (WOMAC) score, EQ5D (EuroQol) score). The Outcome Measures in Rheumatology (OMERACT)/Osteoarthritis Research Society International (OARSI) responder criteria were used to classify patients as improved/not improved 12-months post-THR. Logistic regression modelling was used to explore whether pre-operative expectations predict response to THR.

RESULTS

Greater numbers of pre-operative expectations were associated with younger age, women, increasing BMI, and more education. The more pre-operative expectations a patient had, the more likely they were to improve after surgery. Each individual expectation a patient had, was associated with a 34% increase in improvement [95% confidential interval (CI) 1%-78%]. Analyses within dimensions of the WOMAC suggest the association is strongest for stiffness and function.

CONCLUSION

There is large variation in patients' pre-operative expectations of THR. Greater numbers of pre-operative expectations were associated with improvement following THR. This appears to be driven more by stiffness and function. These findings have implications for informed patient-clinician decision-making.

What is a good patient reported outcome after total hip replacement?

OBJECTIVES

There is an increasing movement to collect and report patient reported outcome measures (PROM's) following total hip replacement (THR). In the UK, the procedure specific PROM of choice is the Oxford Hip Score (OHS). It is currently unclear how to use this information to determine outcome following surgery. The aim of this study was to define a threshold for the OHS that is correlated with patient satisfaction.

DESIGN

Prospective cohort study.

SETTING

A district general hospital (St. Helier Hospital, Carshalton, UK).

PARTICIPANTS

799 patients receiving THR from 1995 to 2004.

MAIN OUTCOME MEASURES

At 12 and 24 months after surgery patients were asked if they were satisfied with surgery and completed the OHS. Receiver operating characteristic (ROC) analyses were used to identify thresholds of follow-up OHS, which best discriminated patient satisfaction. Analyses were stratified by age, sex, body mass index (BMI), baseline OHS and patient expectations.

RESULTS

91.9% of patients were satisfied with THR at 12 months (92.8% at 24 months). Using the ROC technique, the OHS at 12 months associated with patient satisfaction was 38 and at 24 months 33. The OHS at 24 months associated with satisfaction was higher in those with highest tertile of baseline OHS (30, 33, 43 respectively), and lowest tertile of BMI.

CONCLUSIONS

We have identified a value of the OHS that predicts patient satisfaction 12-24 months following THR within a standard clinical setting. However, this threshold is markedly influenced by pre-operative OHS and should be stratified accordingly.

Large-diameter metal-on-metal cementless total hip arthroplasty in the elderly

To evaluate the clinical effectiveness and complications of large-diameter metal-on-metal prostheses, particularly in the elderly, we performed cementless total hip arthroplasty (THA) using metal-on-metal prostheses with large-diameter femoral heads (mean, 45 mm) in 59 patients (average age, 75.1 years) between January 2004 and December 2005. All procedures were performed using a posterolateral approach and spinal anesthesia. Average follow-up was 65 months. Pre- and postoperative Harris Hip Scores and SF-36 questionnaire results were recorded for all patients to evaluate the level of pain relief, improvement in physical function, and changes in quality of life. Postoperative radiographic images were used to document areas of osteolysis and probable aseptic loosening. Average preoperative Harris Hip Score was 36.1±5.7, compared to 69.4±8.3 at last follow-up (P<.01). Average preoperative SF-36 score was 33.6±7.4, compared to 71.8±6.4 at last follow-up (P<.01). There were no dislocations, aseptic loosening, or revisions. Our findings suggest that metal-on-metal cementless prostheses with large-diameter femoral heads in THA can produce satisfactory results with good durability, a low rate of dislocation and aseptic loosening, and a low incidence of revisions in the short term. The benefits of this technique for elderly patients, especially those with weak muscle power and reduced cognitive function, include avoidance of severe cement-injection complications and early functional recovery.

Efficacy of periprosthetic erythromycin delivery for wear debris-induced inflammation and osteolysis

OBJECTIVES

We have reported that oral erythromycin (EM) inhibits periprosthetic tissue inflammation in a group of patients with aseptic loosening. The purpose of this study was to assess the efficacy of local, periprosthetic EM delivery in a rat model.

METHODS

Uncoated Ti pins were press-fit into the right tibia of fourteen Sprague-Dawley rats following an intramedullar injection of UHMWPE (ultra high molecular weight polyethylene) particles. Revision surgeries were performed 2 months after the primary surgery. EM was applied to the Peri-Apatite™ (PA) layer of the titanium (Ti) pins. The previously implanted Ti pins were withdrawn and replaced with Ti pins coated either with (n = 7) or without (n = 7) EM. The rats were killed 1 month after "revision surgery". The EM efficacy was evaluated by (MicroCT) μCT and histology.

RESULTS

μCT analysis showed that bone volume percentage (BV/TV) was significantly higher in the EM-treated group compared to the untreated group (p < 0.05). Histological analysis showed that EM treatment inhibits UHMWPE particle-induced periprosthetic tissue inflammation compared to the untreated group.

CONCLUSION

This study demonstrated that periprosthetic EM delivery reduced periprosthetic inflammation and improved the quality of surrounding bone.

Early complications of total hip and knee replacement: a comparison of outcomes in a regional orthopaedic hospital and two independent treatment centres

INTRODUCTION

There is anecdotal evidence of poorer outcomes from prosthetic joint replacement performed in independent treatment centres but very few comparative studies.

PATIENTS AND METHODS

We compared the early re-operation, dislocation, re-admission, major wound infection and audit rates of 880 total hip (THA) and 874 total knee (TKA) arthroplasties carried out at a regional orthopaedic hospital (Avon Orthopaedic Centre; AOC) with 368 THAs and 365 TKAs from an NHS (WGH) and 67 THAs and 86 TKAs from a private hospital (CNH) independent treatment centre.

RESULTS

Early re-operation rates were 9% at CNH, 1.4% at WGH and 0.6% at AOC after THA and 8% at CNH, 1.9% at WGH and 1% at AOC after TKA. After THA, dislocation rates after THA were 6% at CNH and 1.8% at both WGH and AOC. Re-admission rates were 13% at CNH, 0.6% at WGH and 1.2% at AOC. Major wound problems were 20% at CNH, 3.8% at WGH and 0.4% at AOC after THA and 19% at CNH, 1.9% at WGH and AOC (1.1%) after TKA. After TKA, re-admission rates from CNH were 13%, 1% at WGH and 1.1% at AOC. AOC and WGH audited their outcomes. None were available from CNH.

CONCLUSIONS

Results and audit from independent treatment centres are variable and patients should be warned of this before undergoing treatment at them.

Dislocation after total hip arthroplasty with 28 and 32-mm femoral head

Background

Dislocation after primary total hip arthroplasty (THA) is a significant complication that occurs in 2–5% of patients. It has been postulated that increasing the femoral head diameter may reduce the risk of dislocation. The purpose of this paper is to report our experiences with a change from a 28 to a 32-mm femoral head.

Materials and methods

The retrospective cohort study includes 2572 primary THA performed with a 28 or 32 mm diameter femoral head in the period February 2002 to July 2009. All patients were operated with a posterolateral approach, and all except 18 were operated because of osteoarthritis. Cemented stems were used in 1991 cases and uncemented stems in 581 cases. Cemented cups were used in 2,230 cases and uncemented cups in 342 cases. The patients have been routinely followed for 1–8 years in the 28-mm femoral head group and from 0.5–7.5 years in the 32 femoral head group. We defined a dislocation as an event in which the hip required reduction by a physician.

Results

Dislocation occurred in 49 hips with a 28-mm femoral head and in 4 hips with a 32-mm femoral head with an odds ratio of 6.06 (95% CI = 2.05–17.8) (P < 0.001). Otherwise, there were no significant associations between sex, age, diagnosis and type of prosthesis.

Conclusions

Multivariate analyses of patients operated at our hospital indicate a significant association between femoral head diameter and dislocation after THA. There were no significant associations between dislocation and sex, age, diagnosis, or type of prosthesis.

Birmingham hip arthroplasty: five to eight years of prospective multicenter results

Pioneering centers report excellent results of Birmingham resurfacing arthroplasty. Results from pioneering surgeons are not usually reproduced when implants are used at other centers. We therefore studied patients' satisfaction, postoperative hip function, and survival of Birmingham hip resurfacing in a group, operated by nonpioneering surgeons. The median first year postoperative Harris hip score was 95, and this score was sustained for a period of 8 years. The cumulative survival at 8 years was 95.7%. Most of the failures were in the first year; commonest cause of the first year failures was fracture of femoral neck. This complication is not seen as a substantial problem in the pioneering surgeons' studies. We therefore conclude that this complication is not related to the prosthesis and that its occurrence can be reduced.

Documentation of hip prostheses used in NorwayA critical review of the literature from 1996–2000

We have conducted a systematic review of the scientific literature concerning outcome and clinical effectiveness of prostheses used for primary total hip replacement (THR) in Norway. The study is based on two Health Technology Assessment reports from the UK (Faulkner et al. 1998, Fitzpatrick et al. 1998), reviewing the literature from 1980 to 1995. Using a similar search strategy, we have evaluated the literature from 1996 through 2000. We included 129 scientific and medical publications which were assessed according to a specific appraisal protocol. The majority (72%) were observational studies, whereas only 9% were randomized studies. We could not retrieve any peer-reviewed documentation for one third of the implants. The Charnley prosthesis had by far the best and most comprehensive evidence base with better than 90% implant survival after about 10 years. Survival of the Charnley prosthesis declines by about 10% during each of the two following decades. Except for the Charnley and Lubinus IP, no other prosthesis on the market in Norway has given long-term results (> 15 years). 5 other cemented implants have given comparable results at about 10 years of follow-up. Some uncemented stems have shown promising medium-term outcome, but no combination of uncemented cup and stem fulfilled the benchmark criterion of > or = 90% implant survival at 10 years, which we propose as a minimum requirement for unrestricted clinical use for prostheses used in primary THR. New or undocumented implants should be introduced through a four-step model including preclinical testing, small series evaluated by radiosterometry, randomized clinical trial involving comparison with a well-documented prosthesis, and finally, surveillance of clinical use through registers.

Surgical site infection: incidence and impact on hospital utilization and treatment costs

BACKGROUND

Surgical site infections (SSIs) are serious operative complications that occur in approximately 2% of surgical procedures and account for some 20% of health care-associated infections.

METHODS

SSI was identified based on the presence of ICD-9-CM diagnosis code 998.59 in hospital discharge records for 7 categories of surgical procedures: neurological; cardiovascular; colorectal; skin, subcutaneous tissue, and breast; gastrointestinal; orthopedic; and obstetric and gynecologic. Source of data was the 2005 Healthcare Cost and Utilization Project National Inpatient Sample (HCUP NIS). Primary study outcomes were rate of SSI by surgical category and impact of SSI on length of stay and cost. Results were projected to the national level.

RESULTS

Among 723,490 surgical hospitalizations in the sample, 6891 cases of SSI were identified (1%). On average, SSI extended length of stay by 9.7 days while increasing cost by $20,842 per admission. From the national perspective, these cases of SSI were associated with an additional 406,730 hospital-days and hospital costs exceeding $900 million. An additional 91,613 readmissions for treatment of SSI accounted for a further 521,933 days of care at a cost of nearly $700 million.

CONCLUSION

SSI is associated with a significant economic burden in terms of extended length of stay and increased costs of treatment. Our analysis documented nearly 1 million additional inpatient-days and $1.6 billion in excess costs.

Effect of oral erythromycin therapy in patients with aseptic loosening of joint prostheses

There is currently no cure for aseptic loosening (AL) of total joint replacement (TJR) except surgical revision. The purpose of this study was to determine whether oral EM could improve the periprosthetic tissue profiles and reduce serum cytokine production in AL patients who are candidates for surgical revision. We recruited 32 AL patients. AL patients were treated with either EM (600 mg/day, n=18) or placebo (n=14) daily, started one month before surgery and ending on the day of surgery. Blood samples were obtained before EM treatment and during surgery. Periprosthetic tissues and joint fluids were collected during surgery. Our results demonstrate that oral EM reduces the inflammation of periprosthetic tissues, as manifested by the reduction of the numbers of infiltrating cells, CD68+ macrophages, RANKL+ cells, and TRAP+ cells. Remarkable decreases of TNFalpha (9.6-fold), IL-1beta (21.2-fold), and RANKL (76-fold) gene transcripts were observed in periprosthetic tissues of patients treated with oral EM. Serum levels of both TNFalpha and (to a lesser extent) IL-1beta were significantly reduced following EM treatment (p<0.05). Our results suggest that EM represents a biological cure or prevention for those patients who might need repeated revision surgeries and/or show the early signs of progressive osteolysis after TJR.

Risk factors for revision after shoulder arthroplasty: 1,825 shoulder arthroplasties from the Norwegian Arthroplasty Register

BACKGROUND AND PURPOSE

Previous studies on shoulder arthroplasty have usually described small patient populations, and few articles have addressed the survival of shoulder implants. We describe the results of shoulder replacement in the Norwegian population (of 4.7 million) during a 12-year period. Trends in the use of shoulder arthroplasty during the study period were also investigated.

PATIENTS AND METHODS

1,531 hemiprostheses (HPs), 69 total shoulder replacements (Neer type TSR), and 225 reversed total shoulder replacement (reversed TSR) operations were reported to the Norwegian Arthroplasty Register between 1994 and 2005. Kaplan-Meier failure curves were drawn up for particular subgroups of patients, and revision rates were calculated using Cox regression analysis.

RESULTS

The 5- and 10-year failure rates of hemiprostheses were 6% (95% CI: 5-7) and 8% (95% CI: 6-10), and for reversed total shoulder replacements they were 10% (95% CI: 5-15) and 22% (95% CI: 10-33), respectively. For hemiprostheses, the risk of revision for patients who were 70 years or older was half that of those who were younger (RR = 0.47, CI: 0.28-0.77), while the risk of revision was highest for patients with sequelae after fracture compared to those with acute fractures (RR = 3.3, CI: 1.5-7.2). No differences in prosthesis survival were found between the different hemiprosthesis brands. The main reasons for revision of hemiprostheses were pain and luxation. For reversed total prostheses, the risk of revision was less for women than for men (RR = 0.26, CI: 0.11-0.63), and the main cause of revision was aseptic loosening of the glenoid component. During the study period, the incidence of shoulder arthroplasty increased for all diagnostic groups except inflammatory arthritis, for which a decrease was seen.

INTERPRETATION

We found good results in terms of 5-year prosthesis failure rate, with the use of hemiarthroplasty for patients with inflammatory arthritis, osteoarthritis, and acute fractures. Reversed total shoulder replacement was associated with a rather poor prognosis.

Potential for infection in orthopaedic practice due to individually packaged screws

The use of implants is widespread in orthopaedic practice. In recent times screws and plates have increasingly been supplied individually pre-packaged. We hypothesised that there is a potential for an increased risk of infection associated with the practice of using individually packaged screws. In this study an attempt was made to recreate as closely as possible the standard practice of opening screw packets in the operating theatre. The exterior of 50 screw packets was cultured. The outer screw packets were then opened over a draped instrument table above a petri dish. As a control, petri dishes were left open to the air in the same theatre environment. The packet exteriors grew cultures of organisms in 24/50 cases. The act of opening the packets yielded a growth in 7/50 cases. There was no growth on the control petri dishes. The significance of the result and potential solutions are discussed.

The management and treatment of peri-prosthetic fractures around both total hip and hemiarthroplasty

Peri-prosthetic fractures are an increasingly common phenomenon. They are associated with a high mortality, morbidity and economic burden. We reviewed the literature and look at historical aspects, risk factors, clinical assessment, classification and management of peri-prosthetic fractures around the hip. This article is intended to provide an overview to enable safe initial management of peri-prosthetic fractures and insight into definitive treatment.

Dislocation following total hip replacement: the Avon Orthopaedic Centre experience

INTRODUCTION

The aim of this study was to determine the incidence and outcome of dislocation after total hip arthroplasty at our unit.

PATIENTS AND METHODS

In total, 1727 primary total joint arthroplasties and 305 revision total hip arthroplasties were performed between 1993 and 1996 at our unit. We followed up 1567 (91%) of the primary hip arthroplasties and 284 (93%) of the revision hip arthroplasties at 8-11 years after surgery. Patients were traced by postal questionnaire, telephone interview or examination of case notes of the deceased.

RESULTS

The dislocation rates by approach were 23 out of 555 (4.1%) for the posterior approach, 0 out of 120 (0%) for the Omega approach and 30 out of 892 (3.4%) for the modified Hardinge approach. Of dislocations after primary total hip arthroplasty, 58.5% were recurrent. The mean number of dislocations per patient was 2.81. Overall, 8.1% of revision total hip arthroplasties dislocated. 70% of these became recurrent. The mean number of dislocations per patient was 2.87. The vast majority of dislocations occurred within 2 months of surgery.

DISCUSSION

To our knowledge, this is the largest multisurgeon audit of dislocation after total hip arthroplasty published in the UK. The follow-up of 8-11 years is longer than most comparable studies. The results of this study can be used to inform patients as to the risk and outcome of dislocation, as well as to the risk of further dislocation.

Charnley low-friction arthroplasty of the hip. Five to 25 years survivorship in a general hospital

Background

Some studies have raised the question about whether the good results obtained with the Charnley prosthesis could be replicated at general hospitals when it comes to the frequency of early complications and failure rates, both of which would be higher than those published by centres devoted to hip arthroplasties.

Methods

We reviewed the results of 404 Low Friction Arthroplasties of the hip implanted between 1976 and 1993 in a general hospital by general orthopaedic surgeons. For the survival analysis, the end-point chosen would be the chirurgical revision of any of the prosthetic components for whatever reason.

Results

The complications were 16 dislocations (4%), 14 deep infections (3.5%), 2 neurological injuries (0,5%) and 5 clinical deep venous thromboses (1.2%) (2 pulmonary embolisms). The survival rate at 25 years, both for stem and cup, was 83%. Survival was higher in those arthroplasties implanted in patients older than 60 years, with statistical significance.

Conclusion

Low Friction Arthroplasty undertaken at general hospitals by general orthopaedic surgeons feature similar outcomes to those found in centres devoted to hip surgery.

Late dislocation after total hip arthroplasty

OBJECTIVES

Instability after total hip arthroplasty is a troublesome complication. It commonly occurs in the first 3 postoperative months, but the risk continues over time. There are numerous treatment options, but they have relatively unpredictable outcomes. Numerous factors have been associated with dislocation, but research has mainly focused on the surgical ones. Epidemiological factors remain the subject of much debate. We aimed to establish the incidence of dislocation over time.

METHODS

The Scottish National arthroplasty non-voluntary registry is based on SMR01 records (Scottish Morbidity Record) data. We analyzed the Scottish National Arthroplasty Project to find patients' dislocation rates.

RESULTS

There were 62,175 total hip arthroplasties performed from April 1989 to March 2004 with an annual incidence of dislocation of 0.9%. We found no increase in the rate of dislocation after 2 years.

CONCLUSIONS

It appears there is no late increase in dislocation rate.

LEVEL OF EVIDENCE

Prognostic study, level II-1 (prospective study).

The unstable total hip replacement

BACKGROUND

Dislocation is one of the most common complications of total hip arthroplasty with a reported dislocation rate of 3.2%. Despite increased experience with hip replacement, the overall rate has not yet changed. The aim of this paper is to review the most recent literature published on this topic and indexed in Medline, in order to clarify the main risk factors, and to standardize a treatment protocol of such an important complication of prosthetic surgery.

MATERIALS AND METHODS

Medline database was searched using key words: "hip dislocation", "hip instability" from 1980-2007. Studies were eligible for review and included if they met the following criteria: (1) publication in English, (2) clinical trials (3) review papers.

RESULTS

The risk of first-time dislocation as a function of time after the surgery is not well understood. Most, but not all, series have demonstrated that the risk of dislocation is highest during the first few months after hip arthroplasty; however, first-time late dislocation can also occur many years after the procedure. Several risk factors were described, including the surgical approach, the diameter of the head, impingement, component malposition, insufficient abductor musculature. In addition, there are also many treatment options, such as long-term bracing after closed reduction, component reorientation, capsulorraphy, trochanteric advancement, increasing offset, exchange of the modular head and the polyethylene liner, insertion of constrained liner.

CONCLUSION

Preventing hip dislocation is obviously the best strategy. Surgeons must take into account patient and surgical risk factors. For patients at high risk for dislocation the surgeon should accurately restore leg length and femoral offset; the use of larger femoral heads, posterior transosseous repair of the capsulotendinous envelope if posterior approach is chosen or the use of a lateral approach should be considered. Proper patient education and postoperative care are very important.

Implant infection caused by dermatitis: a report of two cases

We report 2 cases of implant infection with Staphylococcus aureus associated with dermatitis. In both cases, the skin at the surgical site was normal and full antiseptic measures were taken. One patient had a history of chronic asteatotic eczema complicated by cellulitis; the other had generalised exfoliative dermatitis with an atopic aetiology. Dermatitis at sites remote from the operative site may be a contributing factor in implant infection.

The operation of the century: total hip replacement

In the 1960s, total hip replacement revolutionised management of elderly patients crippled with arthritis, with very good long-term results. Today, young patients present for hip-replacement surgery hoping to restore their quality of life, which typically includes physically demanding activities. Advances in bioengineering technology have driven development of hip prostheses. Both cemented and uncemented hips can provide durable fixation. Better materials and design have allowed use of large-bore bearings, which provide an increased range of motion with enhanced stability and very low wear. Minimally invasive surgery limits soft-tissue damage and facilitates accelerated discharge and rehabilitation. Short-term objectives must not compromise long-term performance. Computer-assisted surgery will contribute to reproducible and accurate placement of implants. Universal economic constraints in healthcare services dictate that further developments in total hip replacement will be governed by their cost-effectiveness.

Omnifit acetabular component: a solution to preventing and treating dislocation

PURPOSE

To assess short- to medium-term outcome of the Omnifit constrained acetabular component in preventing dislocation in at-risk patients after total hip arthroplasty (THA).

METHODS

81 patients (mean age, 77 years) underwent either primary or revision THA with an Omnifit constrained acetabular component and were followed up clinically and radiologically for a mean period of 24 months.

RESULTS

There was one dislocation and one revision for avulsion of the acetabulum. The remaining prostheses remained well fixed.

CONCLUSIONS

In the short- to medium-term, the Omnifit constrained acetabular component is effective in preventing primary and recurrent dislocation in at-risk patients. Long-term follow-up is needed to assess whether good fixation is maintained. The Omnifit acetabular cup is recommended for elderly patients with limited life expectancy and functional demands.

Outcome following deep wound contamination in cemented arthroplasty

Infection remains a devastating complication of joint replacement surgery causing a significant burden to both patient and surgeon. However, despite exhaustive prophylactic measures, intraoperative contamination still occurs during cemented arthroplasty with current infection rates of 1-2%. A study was undertaken to determine the incidence of perioperative contamination in cemented arthroplasty patients, to identify contaminating organisms, to identify contaminated regions within the operative wound, to identify factors associated with increased contamination, and finally to assess the medium-term clinical outcome in patients with confirmed intraoperative wound contamination. Eighty consecutive patients undergoing hip and knee cemented arthroplasty were prospectively enrolled over a 6-month period. All scrubbed personnel wore total body exhaust isolation suits and procedures were carried out in ultra-clean air theatres. Of 441 samples, contamination was identified at 21 sites (4.8%) representing a cohort of 18 patients (22.5%). Longer duration of surgery predisposed to higher contamination rates while lower contamination rates were significantly related to fewer gowned personnel within the ultra-clean system, and fewer total personnel in theatre during the procedure. None of the patients developed clinical evidence of deep prosthetic infection at follow-up. We noted a high incidence of intraoperative contamination despite standard prophylaxis. However, this was not reflected by a similar rate of postoperative infection. This may be due to a small bacterial inoculum in each case or may be due to the therapeutic effect of perioperative intravenous antibiotic prophylaxis.

Continuous monitoring of long-term outcomes with application to hip prostheses

The CUSUM continuous monitoring method could be a valuable tool in evaluating the performance (revision experience) of prostheses used in hip replacement surgery. The dilemma when applying the CUSUM in this context is the choice of statistical model for the outcome (revision). The Bernoulli model is perhaps the most straightforward approach but the Poisson model is a plausible, and could be argued, preferable alternative for long-term outcomes such as this, provided the rate of revision with time from surgery can be assumed to be constant. However, a rate (or hazard) varying according to the Weibull distribution appears to be a better representation of a prosthesis lifetime. We show how to adapt the Poisson approach to allow for the hazard to vary according to the Weibull model as well as other parametric survival models. Application to data on a known poorly performing prosthesis shows both the Poisson and Weibull CUSUMs could have given early warning of the poor performance, with the Weibull chart alerting before the Poisson. Simulation work to investigate the robustness of the Poisson and Weibull CUSUM to departures from the underlying survival model highlights the need for correct specification of the model for the outcome.

Bacteriology swab in primary total hip arthroplasty-- does it have a role?

Infection in joint replacement is a devastating complication, and in spite of the advances in surgery, it remains a challenge. The rate of deep infection following primary hip/knee arthroplasty is between 1% and 2%. The aim of this study was to determine whether obtaining bacteriology swabs at the time of surgery could help in further reducing the rate of infection following joint arthroplasty. A bacteriology swab of the synovial fluid was taken after opening the capsule of the hip joint and was sent for culture and sensitivity. Out of 142 swabs sent, four (2.1%) were found to be positive. Three of these patients were treated with antibiotics after obtaining sensitivities. None of the patients developed deep infection. Bacteriology swab in primary joint arthroplasty may have a role and may help in further reducing the incidence of deep infection in joint replacement surgery.

Development and problems of metal-on-metal hip arthroplasty

For over 40 years, the metal-on-polyethylene bearing has dominated the field of total hip replacement. Problems of wear, osteolysis (dissolution of bone), and ultimately failure of prostheses have led to the development of alternative bearing surfaces. Metal-on-metal hip resurfacing has taken current orthopaedic surgery almost by storm. However, metal ion release following metal-on-metal hip resurfacing remains a major cause for concern. This article looks into the development and examines problems and issues surrounding metal-on-metal resurfacing arthroplasty.

Performances en activité de différents types d'installation de traitement de l'air au bloc opératoire

AIM

To compare the performance of various types of airflow system in operating theatre.

METHODS

Besançon Hospital has three types of airflow system in operating theatre: laminar (unidirectional) flow, stabilized flow and turbulent flow. We have compared performances of these airflow systems during operations by evaluating several indicators: number of airborne particles, microbial contamination, kinetics of decontamination, rate of mixing and an index of functionality.

RESULTS

At rest, performances of stabilized flow are close to these of laminar flow. On the other hand, during operations, the laminar flow is the single airflow system to reach the class B10.

CONCLUSION

Our study suggest that laminar flow should be used for prosthetic orthopaedic surgery. However, clinical studies are needed to confirm the superiority of laminar airflow systems in operating theatre.

Evaluation of measures to decrease intra-operative bacterial contamination in orthopaedic implant surgery

The aim of this study was to evaluate whether behavioural and systemic measures will decrease intra-operative contamination during total hip or knee replacements. The influence of these measures on subsequent prolonged wound discharge, superficial surgical site infection and deep periprosthetic infection was also investigated during an 18-month follow-up period. Four swabs were taken from instruments at the beginning and end of the procedure for 207 procedures. Removed bone material (acetabulum and femur in case of the hip joint; femur and tibia in case of the knee joint) was also tested for contamination. Initially, 70 operations performed under original control conditions were included, after which the first behavioural measure was introduced (i.e. better use of the plenum). Cultures were taken during 67 operations using better use of the plenum (Group 1), followed by disciplinary measures and the installation of a new laminar flow system. Seventy operations were monitored after this second intervention (Group 2). The control group showed intra-operative contamination in 32.9% (23/70) of cases, Group 1 showed contamination in 34.3% (23/67) of cases and Group 2 showed contamination in 8.6% (6/70) of cases. Prolonged wound discharge and superficial surgical site infection decreased significantly in Group 2, as did the incidence of deep periprosthetic infection; however, the latter did not reach statistical significance. This study shows that the combination of systemic and behavioural changes in an operating room significantly decreases the incidence of intra-operative bacterial contamination, subsequent prolonged wound discharge and superficial surgical site infection. After 18 months of follow-up, there was also a decrease in deep periprosthetic infection.

Sphingomyelinase mediates macrophage activation by titanium particles independent of phagocytosis: a role for free radicals, NFkappaB, and TNFalpha

The manner in which wear debris initiates intracellular signaling and macrophage activation remains poorly understood. While particle phagocytosis has been implicated in this process, recent studies have shown that phagocytosis is not required for macrophage activation. We examined the hypothesis that titanium particles stimulate macrophages through membrane associated signaling events involving free radicals, sphingomyelinase, NFkappaB, and TNFalpha. Titanium particles stimulated peroxidation of linoleic acid, producing malondialdehyde, while neither lipopolysaccharide nor PBS pre-incubated with particles did, suggesting that the increased peroxidation is related to the presence of the particles themselves. Furthermore, particles stimulated sphingomyelin metabolism in a neutral sphingomyelinase (NSmase) containing cell free system; this effect was inhibited by glutathione, indicating that NSmase activation was due to titanium induced free radicals. Titanium particles also stimulated NSmase activity in cultures of ANA-1 murine macrophages. Addition of purified NSmase to ANA-1 cell cultures stimulated NFkappaB binding, increased transcriptional activity in cells transfected with NFkappaB responsive promoters, and induced TNFalpha expression. These effects were also inhibited by addition of glutathione. Similarly, glutathione inhibited the ability of titanium particles to induce NFkappaB signaling and TNFalpha expression in ANA-1 cells. The findings demonstrate that titanium particles generate free radicals and induce plasma membrane peroxidation and NSmase activation. NSmase, in turn, hydrolyzes sphingomyelin, with activation of the NFkappaB signaling pathway and induction of responsive genes, including TNFalpha. This study demonstrates a mechanism for phagocytosis-independent macrophage activation and defines the sphingomyelin cycle as a potential therapeutic target for the prevention of wear debris induced osteolysis.

Fibroblasts express RANKL and support osteoclastogenesis in a COX-2-dependent manner after stimulation with titanium particles

Synovial fibroblasts are possible mediators of osteolysis. Fibroblasts respond directly to titanium particles and increase RANKL expression through a COX-2/PGE2/EP4/PKA signaling pathway. Fibroblasts pretreated with titanium or PGE2 stimulated osteoclast formation, showing the functional importance of RANKL induction. Synovial fibroblasts and their activation pathways are potential targets to prevent osteolysis.

INTRODUCTION

Bone loss adjacent to the implant is a major cause of joint arthroplasty failure. Although the cellular and molecular response to microscopic wear debris particles is recognized as causative, little is known concerning role of synovial fibroblasts in these events.

MATERIALS AND METHODS

Murine embryonic fibroblasts and knee synovial fibroblasts in culture stimulated with titanium particles were examined by FACS, real time RT-PCR, Northern blot, and Western blot for expressions of vascular cell adhesion molecule (VCAM)1, RANKL, cyclooxygenase (COX)-1, and COX-2, and the four prostaglandin E2 (PGE2) receptor isoforms. Experiments were performed in the presence and absence of COX inhibitors, protein kinase A (PKA) and protein kinase C (PKC) inhibitors, and various EP receptor agonists. Osteoclast formation was examined in co-cultures of pretreated glutaraldehyde-fixed fibroblasts and primary murine spleen cells treated with macrophage-colony stimulating factor (M-CSF) for 7-days.

RESULTS

TNF-alpha stimulated VCAM1 expression, consistent with a synovial fibroblast phenotype. Titanium particles stimulated RANKL gene and protein expressions in fibroblasts in a dose-dependent manner. Gene expression was increased 5-fold by 4 h, and protein levels reached a maximum after 48 h. Within 1 h, titanium particles also induced COX-2 mRNA and protein levels, whereas both indomethacin and celecoxib blocked the stimulation of RANKL, suggesting a COX-2-mediated event. Furthermore, PGE2 induced RANKL gene and protein expression and rescued RANKL expression in titanium-treated cultures containing COX-2 inhibitors. Fibroblast cultures pretreated with either PGE2 or titanium particles enhanced osteoclast formation, indicating the functional importance of RANKL induction. EP4 was the most abundant PGE2 receptor isoform, EP1 and EP2 were expressed at low levels, and EP3 was absent. The EP1 selective agonist iloprost and the EP2 selective agonist butaprost minimally stimulated RANKL. In contrast, the EP2 and EP4 agonist misoprostol induced RANKL to a magnitude similar to PGE2. Finally, PKA antagonism strongly repressed RANKL stimulation by PGE2.

CONCLUSION

Fibroblasts respond directly to titanium particles and increase RANKL expression through a COX-2/PGE2/EP4/PKA signaling pathway. Thus, the synovial fibroblast is important mediator of osteolysis and target for therapeutic strategies.

Cemented or uncemented femoral component in primary total hip replacement? A review from a clinical and radiological perspective

Controversy exists regarding the optimal method of fixation for primary total hip replacement, particularly the femoral component. We performed a systematic literature review to explore whether cemented total hip replacement can achieve better clinical and radiological outcomes. A total of 29 publications were selected using computer-aided and manual searches. A qualitative comparison of results in clinical and radiological changes was then conducted. Most of the literature showed that better short-term clinical and functional outcomes could be obtained from cemented femoral fixation than from uncemented femoral fixation. Results were less clear for the mid-term clinical outcome, though in general, cemented fixation still appeared to show a superior clinical outcome. Radiographic differences are variable and do not seem to correlate with clinical findings. For the short- and mid-term, cemented femoral component is recommended. However, a long-term randomised trial combined with a large cohort study or registry is needed.

Factors regulating osteoclast formation in human tissues adjacent to peri-implant bone loss: expression of receptor activator NFkappaB, RANK ligand and osteoprotegerin

Aseptic bone loss adjacent to orthopedic joint implants is a common cause of joint implant failure in humans. This study investigates the expression of key regulators of osteoclast formation, receptor activator NFkappaB (RANK), Receptor activator of NFkappaB ligand (RANKL) and osteoprotegerin (OPG), in the peri-implant tissues of patients with osteolysis compared with levels in synovial tissues from osteoarthritic and healthy subjects. Immunohistochemical studies demonstrated that significantly higher levels of RANKL protein (p<0.05) were found in the peri-implant tissues of patients with implant failure than in similar tissues from osteoarthritic and healthy subjects. In contrast, OPG protein levels were similar in all tissues. RANKL, expressed as mRNA and protein, was predominantly associated with cells containing wear particles. Dual labeling studies showed that the cells expressing RANKL protein were macrophages. In situ hybridization studies confirmed that mRNA encoding for these proteins is also expressed by cells in the peri-implant tissues. In addition, RANK mRNA was expressed in cells that contained wear particles. These findings show that abnormally high levels of RANKL are expressed in peri-implant tissues of patients with prosthetic loosening and that these abnormal levels of RANKL may significantly contribute to aseptic implant loosening.

Routine recovery room radiographs after total hip arthroplasty: ineffective for screening and unsuitable as baseline for longitudinal follow-up evaluation

To assess the usefulness of traditional recovery room check radiographs after total hip arthroplasty, we retrospectively analysed 2,065 consecutive hip arthroplasty patients. We found a 0.1% rate of radiologic diagnosis of dislocation in the population screened. In 100 patients randomly selected for comparison, the image quality in the recovery room radiographs was significantly inferior to standardized departmental radiographs (P<.001), with further significant differences between cup version (P<.001), and stem alignment assessments (P=.002). We found good agreement between the authors in the assessments of these radiographs with a weighted kappa statistic of 0.8653 (P<.0001). Seven recovery room radiographs needed repetition for poor quality versus none of the departmental films (P=.007). With such poor information and diagnostic yield for follow-up and screening, these investigations should only be performed when clinically indicated.