Mortality and implant revision rates of hip arthroplasty in patients with osteoarthritis: registry based cohort study

Influence of the type of stem and its fixation on revision and immediate postoperative mortality in elective total hip arthroplasty

Aims

Despite higher rates of revision after total hip arthroplasty (THA) being reported for uncemented stems in patients aged > 75 years, they are frequently used in this age group. Increased mortality after cemented fixation is often used as a justification, but recent data do not confirm this association. The aim of this study was to investigate the influence of the design of the stem and the type of fixation on the rate of revision and immediate postoperative mortality, focusing on the age and sex of the patients.

Methods

A total of 333,144 patients with primary osteoarthritis (OA) of the hip who underwent elective THA between November 2012 and September 2022, using uncemented acetabular components without reconstruction shells, from the German arthroplasty registry were included in the study. The revision rates three years postoperatively for four types of stem (uncemented, uncemented with collar, uncemented short, and cemented) were compared within four age groups: < 60 years (Young), between 61 and 70 years (Mid-I), between 71 and 80 years (Mid-II), and aged > 80 years (Old). A noninferiority analysis was performed on the most frequently used designs of stem.

Results

The design of the stem was found to have no significant influence on the rate of revision for either sex in the Young group. Uncemented collared stems had a significantly lower rate of revision compared with the other types of stem for females in the Mid-I group. There was a significantly higher rate of revision for uncemented stems in females in the Mid-II group compared with all other types of stem, while in males the rate for uncemented stems was only significantly higher than the rate for cemented stems. Cemented stems had a significantly lower revision rate compared with uncemented and short stems for both sexes in the Old cohort, as did females with collared stems. The rate of immediate postoperative mortality was similar for all types of stem in the Old age group, as were the American Society of Anesthesiologists grades.

Conclusion

In patients aged > 80 years, uncemented and short stems had significantly higher revision rates compared with cemented and collared stems, especially in females. The design of the stem and type of fixation have to be analyzed in more detail than only considering cemented and uncemented fixation, in order to further improve the success of THA.

Long-Term Outcomes of Birmingham Hip Resurfacing Arthroplasty: A Systematic Review of Independent Series with At Least 10 Years of Follow-up

Background

Hip resurfacing arthroplasty (HRA) provides an attractive alternative to total hip arthroplasty (THA) for the management of osteoarthritis in younger, more active patients; however, concerns persist over complications specific to HRA. The aims of this systematic review were to assess the documented long-term survival rates of the metal-on-metal BIRMINGHAM HIP Resurfacing System at a follow-up of at least 10 years and to analyze the functional outcomes and cause of failures.

Methods

A systematic review was undertaken of all published cohort studies available in the MEDLINE, Cochrane, Embase, and PubMed research databases up to December 2021, as recommended by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Data extraction was focused on survival rates, causes of failure, and functional outcomes. Survival estimates at 10 years were pooled in a meta-analysis, with each series weighted by its variance. Causes of failure were presented as a percentage of the pooled revisions.

Results

A total of 11 studies were identified, encompassing 3,129 cases. Across the 9 studies that had reported a mean follow-up, the mean follow-up was 11.7 years (range, 9.55 to 13.7 years). We found a pooled 10-year survival rate of 95.5% (95% confidence interval, 93.4% to 97.1%). There were 149 revisions among the studies (range, 4 to 38 revisions per study), a rate of 4.8% of the total procedures performed. The 2 main causes of revision were aseptic loosening (20.1% of revisions) and adverse reactions to metal debris (20.1%). There were no revisions for dislocation. Of the studies that reported preoperative functional scores, all reported significant improvement in mean scores postoperatively except for 1 study in which the mean Tegner activity score did not significantly improve.

Conclusions

When performed for appropriate indications, patients undergoing an HRA with use of the BIRMINGHAM HIP Resurfacing System can expect good implant survivorship at 10 years with acceptable functional results and low rates of dislocation and infection. This systematic review, however, confirms concerns regarding adverse reactions to metal debris as a leading cause of revision.

Level of Evidence

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Bilateral simultaneous hip arthroplasty shows comparable early outcome and complication rate as staged bilateral hip arthroplasty for patients scored ASA 1-3 if performed by a high-volume surgeon

PURPOSE

The aim of this study was to compare early outcomes after simultaneous and staged hip arthroplasty (THA) in patients with bilateral symptomatic pathology.

METHODS

We conducted a retrospective cohort study including all patients scheduled for primary THA for bilateral hip osteoarthritis (OA, n = 290). Patients either received simultaneous (n = 152, 52.4%) or staged (n = 138, 47.6%) bilateral THA based on individual preference. All operations (n = 428) were performed by one single, high-volume surgeon. Demographic data (e.g., age, ASA score) as well as perioperative parameters (haemoglobin drop (Hb), red blood cell transfusion, length of stay (LOS), operation time, six week complication rate and achievement of inpatient rehabilitation key points) were evaluated.

RESULTS

Patients in the simultaneous bilateral THA group were younger (62.8 ± 8.9 vs. 65 ± 9.7 years, p = 0.022) and had lower ASA scores (1.8, (34.2% ASA 1, 55.3% ASA 2, 37.2% ASA 3) vs. 2.0 (18.8% ASA 1, 61.6% ASA 2, 19.6% ASA 3)) than the staged group. While the average LOS was 7.1 ± 1.7 days for simultaneous bilateral THA, the combined LOS for the staged group was 12.9 ± 2.4 days (p < 0.001). The cumulative operation time in the simultaneous bilateral THA group was 61.1 ± 11.5 min and 57.6 ± 7.3 min in the staged group (p < 0.015). Cumulative Hb loss was significantly higher in the staged group (2.1 ± 7.2 g/dl vs. 3.7 ± 1.3 g/dl, p < 0.001). No significant differences were found concerning the complication rate or early inpatient rehabilitation.

CONCLUSION

Simultaneous bilateral hip arthroplasty in patients with symptomatic bilateral hip osteoarthritis is as safe and successful as a staged procedure if performed by a high-volume surgeon.

Cementless tapered wedge stems in patients undergoing primary total hip arthroplasty with Dorr C bone-are complication risks increased?

Background

The use of cementless femoral stems in patients undergoing primary total hip arthroplasty (THA) with Dorr C bone remains controversial for fear of fracture or subsidence. Purpose of this multicenter study was to compare clinical outcomes and complications of THA using a tapered femoral prosthesis in patients with Dorr C bone versus Dorr A/B bone.

Methods

A total of 1,030 patients underwent primary THA with a tapered wedge femoral stem at a minimum one year follow up. Forty-eight patients with Dorr C bone (mean age 68.7 years) were compared with a matched cohort of patients with Dorr A/B bone (mean age 69.9 years). Mean follow-up was approximately 4 years in both cohorts. There were no differences in sex, age, body mass index (BMI), Harris Hip Score (HHS), complications, and radiographic outcomes including subsidence and aseptic loosening were evaluated.

Results

Postoperative HHSs were a mean of 82 points in the Dorr C cohort compared to 84 points in the Door A/B cohort (P=0.2653). There was no significant difference in complication or revision rates for any reason (P=0.23). Mean subsidence for the Dorr C and Dorr A/B was 1.4 and 1.2 mm, respectively (P=0.5164), and there was no aseptic loosening of the femoral component found in either group.

Conclusions

Current generation tapered wedge cementless femoral stems provide stable fixation for patients with Dorr C bone quality without increased complications with respect to fracture or subsidence and can be considered an alternative to cemented stems in patients with compromised bone quality.

Hip resurfacing arthroplasty as an alternative to total hip arthroplasty in patients aged under 40 years

Aims

The aims of the study were to report for a cohort aged younger than 40 years: 1) indications for HRA; 2) patient-reported outcomes in terms of the modified Harris Hip Score (HHS); 3) dislocation rate; and 4) revision rate.

Methods

This retrospective analysis identified 267 hips from 224 patients who underwent an hip resurfacing arthroplasty (HRA) from a single fellowship-trained surgeon using the direct lateral approach between 2007 and 2019. Inclusion criteria was minimum two-year follow-up, and age younger than 40 years. Patients were followed using a prospectively maintained institutional database.

Results

A total of 217 hips (81%) were included for follow-up analysis at a mean of 3.8 years. Of the 23 females who underwent HRA, none were revised, and the median head size was 46 mm (compared to 50 mm for males). The most common indication for HRA was femoroacetabular impingement syndrome (n = 133), and avascular necrosis ( (n = 53). Mean postoperative HHS was 100 at two and five years. No dislocations occurred. A total of four hips (1.8%) required reoperation for resection of heterotopic ossification, removal of components for infection, and subsidence with loosening. The overall revision rate was 0.9%.

Conclusion

For younger patients with higher functional expectations and increased lifetime risk for revision, HRA is an excellent bone preserving intervention carrying low complication rates, revision rates, and excellent patient outcomes without lifetime restrictions allowing these patients to return to activity and sport. Thus, in younger male patients with end-stage hip disease and higher demands, referral to a high-volume HRA surgeon should be considered.

Comparisons of in-hospital complications between total hip arthroplasty and hip resurfacing arthroplasty

BACKGROUND

Hip resurfacing arthroplasty (HRA) is a less common but effective alternative method to total hip arthroplasty (THA) for hip reconstruction. In this study, we investigated the incidences of in-hospital complications between patients who had been subjected to THA and HRA.

METHODS

The National Inpatient Sample data that had been recorded from 2005 to 2014 was used in this study. Based on the International Classification of Disease, Ninth Revision, Clinical Modification, patients who underwent THA or HRA were included. Data on demographics, preoperative comorbidities, length of hospital stay, total charges, and in-hospital mortality and complications were compared. Multiple logistic regression analysis was used to determine whether different surgical options are independent risk factors for postoperative complications.

RESULTS

A total of 537,506 THAs and 9,744 HRAs were obtained from the NIS database. Patients who had been subjected to HRA exhibited less preoperative comorbidity rates, shorter length of stay and extra hospital charges. Moreover, HRA was associated with more in-hospital prosthesis loosening. Notably, patients who underwent HRA were younger and presented less preoperative comorbidities but did not show lower incidences in most complications.

CONCLUSIONS

The popularity of HRA gradually reduced from the year 2005 to 2014. Patients who underwent HRA were more likely to be younger, male, have less comorbidities and spend more money on medical costs. The risk of in-hospital prosthesis loosening after HRA was higher. The HRA-associated advantages with regards to most in-hospital complications were not markedly different from those of THA. In-hospital complications of HRA deserve more attention from surgeons.

Bioelectronic multifunctional bone implants: recent trends

The concept of Instrumented Smart Implant emerged as a leading research topic that aims to revolutionize the field of orthopaedic implantology. These implants have been designed incorporating biophysical therapeutic actuation, bone-implant interface sensing, implant-clinician communication and self-powering ability. The ultimate goal is to implement revist interface, controlled by clinicians/surgeons without troubling the quotidian activities of patients. Developing such high-performance technologies is of utmost importance, as bone replacements are among the most performed surgeries worldwide and implant failure rates can still exceed 10%. In this review paper, an overview to the major breakthroughs carried out in the scope of multifunctional smart bone implants is provided. One can conclude that many challenges must be overcome to successfully develop them as revision-free implants, but their many strengths highlight a huge potential to effectively establish a new generation of high-sophisticated biodevices.

The Effect of Femoral Fixation on Revision and Mortality Following Elective Total Hip Arthroplasty in Patients Over the Age of 65 years. An Analysis of the American Joint Replacement Registry

BACKGROUND

With the overwhelming use of cementless femoral fixation for primary total hip arthroplasty in the United States, the associations of stem fixation on the risk of revision and mortality are poorly understood. We evaluated the relationship between femoral fixation and risk of revision and mortality in patients included in the American Joint Replacement Registry.

METHODS

Elective, primary, unilateral total hip arthroplasties in the American Joint Replacement Registry, in patients over the age of 65 years were considered. In total, 9,612 patients with a cemented stem were exact matched 1:1 with patients who received a cementless stem based on age, gender, and the Charlson Comorbidity Index. Outcomes compared between the groups included need and reason for revision at 90 days and 1 year; in-hospital, 90-day, and 1-year mortality; and mortality after early revision. Covariates were used in linear regression analyses.

RESULTS

Cemented fixation was associated with a 37% reduction in the risk of 90-day revision, and a reduction in the risk of revision for periprosthetic fracture of 87% at 90 days and 81% at 1 year. Cemented fixation was associated with increased 90-day and 1-year mortality (odds ratio [OR] 3.15, confidence interval [CI] 2.24-4.43 and OR 2.36, CI 1.86-3.01, respectively). Patients who underwent subsequent revision surgery within the first year exhibited the highest mortality risk (OR 3.23, CI 1.05-9.97).

CONCLUSION

In this representative sample of the United States, 90-day revision for any reason and for periprosthetic fracture was significantly reduced in patients with a cemented stem. This benefit must be weighed against the association with increased mortality and with the high risk of mortality associated with early revision, which was more prevalent with cementless fixation.

Cause-Specific Stem Revision Risk in Primary Total Hip Arthroplasty Using Cemented vs Cementless Femoral Stem Fixation in a US Cohort

BACKGROUND

We sought to evaluate the cause-specific revision risk following hybrid (cemented stem mated to a cementless acetabular implant) vs cementless total hip arthroplasty (THA) in a US cohort.

METHODS

Primary elective THA for osteoarthritis was identified using Kaiser Permanente's Total Joint Replacement Registry (2001-2018). Multivariable Cox regression was used to evaluate cause-specific revision, including aseptic loosening, infection, instability, and periprosthetic fracture (PPF), for hybrid vs cementless THA. Analysis was stratified by age (<65, 65-74, and ≥75 years) and gender.

RESULTS

The study cohort comprised 88,830 THAs, including 4539 (5.1%) hybrid THAs. In stratified analysis, hybrid THA had a higher revision risk for loosening in females in all 3 age subgroups. A lower risk of revision for PPF was observed following hybrid THA in females aged ≥75 years. For females ≥75 years, cementless THA had an excess PPF risk of 0.9% while hybrid THA had an excess loosening risk of 0.2%, translating to a theoretical prevention of 10 PPF revisions but a price of 3 loosening revisions per 1000 hybrid THAs. No difference in revision risk was observed in males.

CONCLUSION

We observed differences in cause-specific revision risks by method of stem fixation which depended upon patient age and gender. Although the trend toward all cementless fixation continue, there may be a role for hybrid fixation in females ≥75 years to mitigate risk for revision due to PPF at the potential cost of a slight increase in longer term aseptic loosening.

LEVEL OF EVIDENCE

Level III.

Cemented femoral stem fixation through the anterior approach has fewer early complications than cementless fixation

AIMS

To achieve the functional benefits of the direct anterior (DA) approach and the fixation benefits of cemented replacement, this study combined the two techniques posing the following questions: does the limited access of the DA approach adversely affect the cement technique?; and does such a cementing technique reduce the incidence of cementless complications?

METHODS

A consecutive series of 341 patients (360 hips) receiving the DA approach between 2016 and 2018 were reviewed. There were 203 cementless stems and 157 cemented stems. Mean age was 75 years (70 to 86) in the cementless group and 76 years (52 to 94) in the cemented group, with 239 (70%) females in the whole series. Femoral complications were compared between the two groups. Mean follow-up was 1.5 years (0.1 to 4.4) for patients in the cementless group and 1.3 years (0.0 to 3.9) for patients in the cemented group.

RESULTS

The cementless group had a higher rate of femoral complications (8 vs 0; p = 0.011). There were two loose stems and six fractures, all requiring revision. Fractures occurred a mean 14.5 days (2 to 31) postoperatively and loosening at 189 days and 422 days postoperatively. Femoral cementing can be done using the DA approach safely and reduces the number of complications compared with a contemporary cementless series.

CONCLUSION

A higher rate of early fractures and loosening occurred with cementless stems. This was not observed in our cemented stem cohort and cementing was safely accomplished through the DA approach. The modern femoral cementing process with the DA approach does not add to surgical complexity or time, has fewer early complications, and is a safer option for older patients compared to cementless femoral arthroplasties. Cite this article: Bone Joint J 2021;103-B(7 Supple B):33-37.

Midterm Survivorship of an Uncemented Hydroxyapatite-Coated Titanium Femoral Component and Clinically Meaningful Outcomes in Patients Older Than 75 Years

Purpose: It remains controversial whether cementless femoral components are safe in elderly patients. The aim of this study was (1) to determine the stem survival rate in patients >75 years of age who were treated with an uncemented femoral component and (2) to report clinically significant results on a mid-term follow-up. Methods: 107 total hip arthroplasties (THA) were retrospectively evaluated in 97 patients over 75 years of age (mean age 78 years, range 75–87) treated with an uncemented femoral stem. The minimum follow-up was five years (mean 6.4 years, range 5–8). Stem survival rates, clinically meaningful outcomes, and incidence of complications were evaluated. Results: Kaplan-Meier survival analysis, with the endpoint revision for any reason, showed a 6.4-year survival rate of 98% (95% CI, 95–99%; 63 hips at risk). The survival rates were comparable for male and female patients (log-rank test, p = 0.58). The modified Harris Hip Score (mHHS) improved from 42.2 (12 to 85) points to 81.1 (22 to 97) points (p < 0.0001). Mid-term minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient acceptable symptomatic state (PASS) were 25, 84, and 70, respectively. Conclusion: An uncemented stem is a viable option in patients over 75 years with good clinical outcomes and survivorship. Periprosthetic fractures were not a relevant failure mechanism with the stem used.

Femoral Stem Cementation in Hip Arthroplasty: The Know-How of a "Lost" Art

PURPOSE OF REVIEW

To describe the (1) indications, (2) preoperative precautions, and (3) stepwise technical details of modern femoral stem cemented fixation.

RECENT FINDINGS

Femoral stem cementation provides excellent implant longevity with a low periprosthetic fracture rate among patients with compromised bone quality or aberrant anatomy. Unfamiliarity with the details of modern cementation techniques among trainees who may lack frequent exposure to cementing femoral stems may preclude them from offering this viable option to suitable patients in later stages of their careers. As such, maximizing benefit from cemented femoral stem fixation among suitable candidates is contingent upon the meticulous use of modern cementation techniques. In addition to proper patient selection, modern cementation techniques emphasize the use of (1) pulsatile lavage of the femoral canal, (2) utilization of epinephrine-soaked swabs, (3) vacuum cement mixing, (4) retrograde cement introduction, (5) cement pressurization, and (6) the use of stem centralizers. Furthermore, identifying and optimizing the preoperative status of at-risk patients with pre-existing cardiopulmonary compromise, in addition to intraoperative vigilance, are essential for mitigating the risk of developing bone cement implantation syndrome. Further research is required to assess the utility of cemented femoral stem fixation among younger patients.

Similar early mortality risk after cemented compared with cementless total hip arthroplasty for primary osteoarthritis: data from 188,606 surgeries in the Nordic Arthroplasty Register Association database

Background and purpose - Current literature indicates no difference in 90-day mortality after cemented compared with cementless total hip arthroplasty (THA). However, previous studies are hampered by potential selection bias and suboptimal adjustment for comorbidity confounding. Therefore, we examined the comorbidity-adjusted mortality up to 90 days after cemented compared with cementless THA performed due to osteoarthritis.Patients and methods - Using the Nordic Arthroplasty Register Association database, 2005-2013, we included 108,572 cemented and 80,034 cementless THA due to osteoarthritis. We calculated the Charlson comorbidity index of each patient based on data from national patient registers. The Kaplan-Meier method was used to estimate unadjusted all-cause mortality. Cox regression was used to estimate hazard ratios (HR) with 95% confidence intervals (CI) for 14, 30-, and 90-day mortality comparing cemented with cementless THA, adjusting for age, sex, comorbidity, nation, and year of surgery.Results - Cumulative all-cause mortality within 90 days was 0.41% (CI 0.37-0.46) after cemented and 0.26% (CI 0.22-0.30) after cementless THA. The adjusted HR for cemented vs. cementless fixation was 0.97 (CI 0.79-1.2), and similar risk estimates were obtained for mortality within 14 (adjusted HR 0.91 [CI 0.64-1.3]) and 30 days (adjusted HR 0.94 [CI 0.71-1.3]). We found no clinically relevant differences in mortality between cemented and cementless THA in analyses stratified by age, sex, Charlson comorbidity index, or year of surgery.Interpretation - After adjustment for comorbidity as an important confounder, we observed similar early mortality between the 2 fixation techniques.

Introduction of a New Treatment Algorithm Reduces the Number of Periprosthetic Femoral Fractures After Primary Total Hip Arthroplasty in Elderly Females

BACKGROUND

Increasing global usage of cementless prostheses in total hip arthroplasty (THA) presents a challenge, especially for elderly patients. To reduce the risk of early periprosthetic femoral fractures (PFFs), a new treatment algorithm for females older than 60 years undergoing primary THA was introduced. The aim of this study was to determine the impact of the new treatment algorithm on the early risk of perioperative and postoperative PFFs and guideline compliance.

METHODS

A total of 2405 consecutive THAs that underwent primary unilateral THA at our institution were retrospectively identified in the period January 1, 2013-December 31, 2018. A new treatment algorithm was introduced on April 1, 2017 with female patients aged older than 60 years intended to receive cemented femoral components. Before this, all patients were scheduled to receive cementless femoral components. Demographic data, number of perioperative and postoperative PFFs, and surgical compliance were recorded, analyzed, and intergroup differences compared.

RESULTS

The utilization of cemented components in female patients older than 60 years increased from 12.3% (n = 102) to 82.5% (n = 264). In females older than 60 years, a significant reduction in the risk in early postoperative and intraoperative PFF after introduction of the new treatment algorithm was seen (4.57% vs 1.25%; P = .007 and 2.29% vs 0.31%; P = .02, respectively). Overall risk for postoperative and intraoperative fractures combined was also reduced in the entire cohort (4.1% vs 2.0%; P = .01).

CONCLUSION

Use of cemented fixation of the femoral component in female patients older than 60 years significantly reduces the number of PFFs. Our findings support use of cemented femoral fixation in elderly female patients.

Comparison of suprapatellar versus infrapatellar approaches of intramedullary nailing for distal tibia fractures

Background

This study aimed to analyze and compare the clinical and functional outcomes of distal tibia fractures treated with intramedullary nailing (IMN) using the suprapatellar (SP) and infrapatellar (IP) surgical approaches.

Methods

A retrospective analysis was performed in 63 patients with distal fractures that were treated with IMN between August 2014 and August 2018. A total of 27 and 36 patients underwent IMN using the SP and IP techniques, respectively. The surgical time, blood loss, closed reduction rate, rate of adjuvant reduction technique, fracture healing time, and complications were reviewed in this study. Anterior knee pain was assessed using the visual analog scale. The Lysholm Knee Scoring Scale and American Orthopaedic Foot and Ankle Society (AOFAS) scale were used as clinical measurements.

Results

A total of 63 patients, with a minimum follow-up of 12 months, were evaluated. The average surgical time, blood loss, rate of adjuvant reduction technique, closed reduction rate, fracture healing time, and Lysholm Knee Scoring Scale score were insignificantly different (P > 0.05) between the two groups. However, the SP approach was superior to the IP approach in terms of pain score, AOFAS score, and fracture deformity rate (P < 0.05).

Conclusions

In the treatment of distal tibia fractures, the SP IMN technique is associated with a significantly higher functional outcome, lower knee pain, and lower rate of fracture deformity than the IP IMN technique.

Impaction technique influences implant stability in low-density bone model

Aims

Cementless acetabular components rely on press-fit fixation for initial stability. In certain cases, initial stability is more difficult to obtain (such as during revision). No current study evaluates how a surgeon’s impaction technique (mallet mass, mallet velocity, and number of strikes) may affect component fixation. This study seeks to answer the following research questions: 1) how does impaction technique affect a) bone strain generation and deterioration (and hence implant stability) and b) seating in different density bones?; and 2) can an impaction technique be recommended to minimize risk of implant loosening while ensuring seating of the acetabular component?

Methods

A custom drop tower was used to simulate surgical strikes seating acetabular components into synthetic bone. Strike velocity and drop mass were varied. Synthetic bone strain was measured using strain gauges and stability was assessed via push-out tests. Polar gap was measured using optical trackers.

Results

A phenomenon of strain deterioration was identified if an excessive number of strikes was used to seat a component. This effect was most pronounced in low-density bone at high strike velocities. Polar gap was reduced with increasing strike mass and velocity.

Conclusion

A high mallet mass with low strike velocity resulted in satisfactory implant stability and polar gap, while minimizing the risk of losing stability due to over-striking. Extreme caution not to over-strike must be exercised when using high velocity strikes in low-density bone for any mallet mass.

Cite this article: Bone Joint Res 2020;9(7):386–393.

Patient and surgical variability in the primary stability of cementless acetabular cups: A finite element study

Aseptic loosening is the most common indication for revision of cementless acetabular cups and often depends on the primary stability achieved following surgery. Cup designs must be capable of achieving primary stability for a wide variety of individuals and surgical conditions to be successful. Typically, preclinical finite element (FE) testing of cups involves assessing the performance in a single patient and under a limited set of idealized conditions. The aim of this study was to assess the effect of patient and surgical parameters on the primary stability of an acetabular cup design in a set of subject-specific FE models. Interference fit was varied in a representative set of 12 patient-specific models of the implanted hemipelvis. Linear mixed models showed a significant association with micromotion for interference fit (P < .0001), acetabular bone elastic modulus (P < .001), native acetabular diameter (P  = .03), and the interference fit-elastic modulus interaction (P = .01). There were no significant associations between the polar gap and any of the parameters considered. The significant interference fit-elastic modulus interaction suggests that increasing the interference fit in patients with low bone quality leads to a greater reduction in micromotion than in patients with higher bone quality. However, the significant association between percentage bone yielding and interference fit (P < .0001) suggests a higher periacetabular fracture risk at higher interference fits. This work supports the development of preclinical testing of cup designs for the broad range patients and surgical conditions a cup may face following surgery.

Concentration-Dependent Regulation of TiAl6V4 Particles on the Osteogenesis Potential of Human Bone Marrow Mesenchymal Stem Cells

Total joint replacement is one of the most effective treatments for osteoarthritis, while the aseptic loosening of artificial joint is a major complication leading to the joint replacement failure. There are very limited studies about the effects of titanium-alloy particles on the osteogenic differentiation of mesenchymal stem cells. In this study, human bone marrow-derived mesenchymal stem cells (BM-hMSCs) were treated with different concentrations of TiAl₆V₄ particles. The cell viability was detected by MTT assay, and the cell proliferation was assessed by CKK-8 assay. The early and late stages of osteogenic differentiation were determined by alkaline phosphatase (ALP) and Alizarin Red S (ARS) staining assays. The expression of osteogenic genes and proteins was analyzed by RT-PCR and Western blot. TiAl₆V₄ particles at high concentration 100 μg/ml inhibited the cell viability of BM-hMSCs. However, TiAl₆V₄ in the range of 5-50 μg/ml did not show effects neither on the cell viability nor on the cell proliferation of BM-hMSCs. TiAl₆V₄ particles showed concentration-dependent bidirectional regulations on BM-hMSC osteogenesis. Specifically, TiAl₆V₄ at 5 μg/ml promoted the osteogenesis of BM-hMSCs, which was suppressed by TiAl₆V₄ at 50 μg/ml. Further, mechanism study revealed that the regulation of TiAl₆V₄ on BM-hMSCs was related to Wnt signaling pathway. Given the potential of mesenchymal cells, our study suggested that the minimization of metal use would be an attractive strategy to reduce the joint replacement failure.

Postoperative 30-day complications after cemented/hybrid versus cementless total hip arthroplasty in osteoarthritis patients > 70 years

Background and purpose - The use of cementless total hip arthroplasty (THA) in elderly patients is debated because of increased risk of early periprosthetic femoral fractures. However, cemented femoral components carry a risk of bone cement implantation syndrome. Hence, we compared in-hospital complications, complications leading to readmission and mortality ≤ 30 days postoperatively between hybrid/cemented (cemented femoral component) vs. cementless THA in osteoarthritis patients > 70 years.Patients and methods - This is a prospective observational cohort study in 9 centers from January 2010 to August 2017. We used 30-day follow-up from the Danish National Patient Registry, patient records, and data from the Danish Hip Arthroplasty Register. Only THAs performed as a result of osteoarthritis were included.Results - 3,368 (42%) of the THAs were cemented/hybrid and 4,728 (58%) cementless. The in-hospital complication risk was 7.7% after cemented/hybrid vs. 5.3% after cementless THA (< 0.001), statistically not significant when adjusting for comorbidities (p = 0.1). There were similar risks of complications causing readmission (5.7% vs. 6.2%) and mortality ≤ 30 days (0.2% vs. 0.3%). 15 cases (0.4%) of pulmonary embolism (PE) were found after cemented/hybrid vs. 4 (0.1%) after cementless THA (p = 0.001); none occurred within 24 hours postoperatively. 2 of the PEs after cementless THA led to mortality. Cemented/hybrid THA remained significantly associated with risk of PE (RR 3.9, p = 0.02), when adjusting for comorbidities. BMI > 35 was associated with highest risk of PE (RR 5.7, p = 0.003). The risk of periprosthetic femoral fracture was 0.2% after cemented/hybrid vs. 1.5% after cementless THA (p < 0.001) and the risk of dislocations was 1.2% after cemented/hybrid THA vs. 1.8% after cementless THA (p = 0.04).Interpretation - The higher risk of PE after cemented/hybrid THA and higher risk of periprosthetic femoral fractures and dislocations after cementless THA highlights that both medically and surgically complications are related to fixation technique and have to be considered.

Has the Use of Fixation Techniques in THA Changed in This Decade? The Uncemented Paradox Revisited

BACKGROUND

Despite existing studies favoring cemented fixation for patients older than 75 years, a trend toward increased use of uncemented fixation has been described in a 2013 study that used arthroplasty registry data from 2006 to 2010. Updated summarized data are needed beyond 2010 to investigate contemporary trends in the usage of uncemented fixation, especially in patients older than 75 years, and to draw attention to a potential continuing conflict between trends in fixation choice and reported revision risk. Thus, healthcare policy and practice can change and surgeons can make better implant fixation choices.

QUESTIONS/PURPOSES

(1) Has the percentage of primary THAs performed with uncemented fixation changed since 2010? (2) Has the percentage of primary THAs performed in patients older than 75 years performed with uncemented fixation changed since 2010? (3) After stratifying by age, which fixation strategy (cemented versus uncemented and hybrid versus uncemented) is associated with the lowest risk of revision?

METHODS

National annual reports from hip arthroplasty registers were identified, and data were extracted from registers published in English or a Scandinavian language, with at least 3 years of reported data in the period from 2010 to 2017. These included Australia, Denmark, England-Wales, Finland, the Netherlands, New Zealand, Romania, Norway, Sweden, and Switzerland, which are all countries with high completeness rates. Data regarding rates of revisions (all causes) related to fixation methods and secondary to different age groups, were taken directly from the registers and no re-analysis was done. The risk estimates were presented as either hazard ratios, rate per 100 component years or as Kaplan-Meier estimates of revision. The age groups compared for Denmark were younger than 50, 50-59, 60-69,70-79, and older than 80 years, and for Australia, New Zealand, England-Wales, and Finland, they were younger than 55, 55-64, 65-74, and older than 75 years. No data were pooled across the registers.

RESULTS

The current use of uncemented fixation in primary THAs varies between 24% (Sweden) and 71% (Denmark). Increasing use of uncemented fixation has been reported in Norway, Denmark, and Sweden, whereas decreasing use of uncemented fixation has been reported in England-Wales, Australia, New Zealand, and Finland. Examining the group of patients older than 75 years, we found that the use of uncemented fixation has been stable in Netherlands, Sweden, New Zealand, and England-Wales. The use of uncemented fixation is still increasing in Denmark and Australia. In Finland, the use of uncemented fixation has decreased (from 43 % to 24 %) from 2010 to 2017. When compared with uncemented fixation, the risk of revision for hips using cemented fixation was lower in patients older than 75 years for all registers surveyed, except for the oldest males in the Finnish register. In this group, no difference was found between cemented and uncemented fixation.

CONCLUSION

Our findings should be used in healthcare policy as feedback on current THAs being performed so as to direct surgeons to choose the right implant fixation, especially in patients older than 75 years, thereby reducing revision risk and increasing the long-term survival of primary THAs. It appears that femoral stem fixation may be the most important revision risk factor in older patients, and future studies should examine this perspective.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Venous thromboembolism in patients hospitalized for hip joint replacement surgery

BACKGROUND

Venous thromboembolism (VTE) is a potentially life-threatening disease. Major transient risk factors include trauma, surgery, and immobilization. Patients undergoing hip joint replacement (HJR) are characterized by a high risk of postoperative VTE, but data on the time trends of VTE rates in this population are sparse.

METHODS

In an analysis of the German nationwide inpatient sample, we included all hospitalizations for elective primary HJR in Germany from 2005 to 2016. Time trends of the surgical procedure, overall death rates, and VTE rates were analysed, and predictors of VTE identified.

RESULTS

Overall, 1,885,839 inpatients with elective primary HJR (59.1% women, 51.4% ≥70 years) were included in the analysis. During hospitalization, VTE was documented in 11,554 (0.6%) patients. While total numbers of primary HJR increased from 145,223 in 2005 to 171,421 in 2016 (β-(slope)-estimate 1818 [95%CI 1083 to 2553], P < 0.001), in-hospital VTE decreased from 1288 (0.9%) to 843 (0.5%) cases (β-estimate -0.71 [95%CI -0.77 to -0.65], P < 0.001), and in-hospital death rate from 0.33% (476 deaths) to 0.29% (498 deaths) (β-estimate -0.11 [95%CI -0.20 to -0.02], P = 0.018). Infections during hospitalization were associated with higher VTE risk than cancer and cardiovascular events. VTE events were independently associated with an increased death risk (OR 15.19 [95%CI 14.19-16.86], P < 0.001).

CONCLUSIONS

While total numbers of HJR increased significantly in Germany between 2005 and 2016, in-hospital rates of VTE decreased from 0.9% to 0.5%. Patients with perioperative VTE had a 15-fold increase of in-hospital death. Cancer, cardiovascular disease and perioperative infections were associated with higher risk for VTE.

Suprapatellar nailing of fractures of the tibia

OBJECTIVE

Intramedullary nailing of tibia fractures via a suprapatellar, transarticular approach with the knee joint in 20-30° of flexion and the use of specific protection tubes to preserve intra-articular structures.

INDICATIONS

Extra-articular fractures of the proximal tibia; simple and comminuted fractures of the tibia diaphysis; segmental diaphyseal fractures of the tibia; extra-articular fractures of the distal tibia and fractures with simple intra-articular distal extension; floating knee injuries.

CONTRAINDICATIONS

Gustilo grade 3C open fractures of the tibia; severe soft tissue laceration, contamination or infection in the suprapatellar area; ipsilateral knee joint prosthesis; knee arthrodesis; implants blocking the nail entry point.

SURGICAL TECHNIQUE

Via a suprapatellar, transarticular approach an intramedullary tibia nail is inserted after anatomical reposition of the tibial fracture with the knee joint in 20-30° of flexion. Use of specific protection tubes to preserve intra-articular structures. The proximal and distal locking configuration depends upon the specific fracture characteristics.

RESULTS

In all, 61 patients underwent suprapatellar tibia nailing and were under follow-up at least until fracture union. Twelve patients suffered from an open fracture. A total of 17 patients had a distal third fracture, 8 sustained a proximal third fracture and 36 had a shaft fracture. Follow-up focused on patients with distal fractures; 6/17 patients sustained open fractures. Average time to union was 9 weeks. One fracture did not heal and required exchange nailing. Two patients complained about anterior knee pain. Functionally, full range of motion was regained in all patients.

Preliminary report of clinical experience with metal-on-highly-crosslinked-polyethylene hip resurfacing

Objectives

Modern metal-on-metal (MoM) hip resurfacing arthroplasty (HRA), while achieving good results with well-orientated, well-designed components in ideal patients, is contraindicated in women, men with head size under 50 mm, or metal hypersensitivity. These patients currently have no access to the benefits of HRA. Highly crosslinked polyethylene (XLPE) has demonstrated clinical success in total hip arthroplasty (THA) and, when used in HRA, potentially reduces metal ion-related sequelae. We report the early performance of HRA using a direct-to-bone cementless mono-bloc XLPE component coupled with a cobalt-chrome femoral head, in the patient group for whom HRA is currently contraindicated.

Methods

This is a cross-sectional, observational assessment of 88 consecutive metal-on-XLPE HRAs performed in 84 patients between 2015 and 2018 in three centres (three surgeons, including the designer surgeon). Mean follow-up is 1.6 years (0.7 to 3.9). Mean age at operation was 56 years (sd 11; 21 to 82), and 73% of implantations were in female patients. All patients were individually counselled, and a detailed informed consent was obtained prior to operation. Primary resurfacing was carried out in 85 hips, and three cases involved revision of previous MoM HRA. Clinical, radiological, and Oxford Hip Score (OHS) assessments were studied, along with implant survival.

Results

There was no loss to follow-up and no actual or impending revision or reoperation. Median OHS increased from 24 (interquartile range (IQR) 20 to 28) preoperatively to 48 (IQR 46 to 48) at the latest follow-up (48 being the best possible score). Radiographs showed one patient had a head-neck junction lucency. No other radiolucency, osteolysis, component migration, or femoral neck thinning was noted.

Conclusion

The results in this small consecutive cohort suggest that metal-on-monobloc-XLPE HRA is successful in the short term and merits further investigation as a conservative alternative to the current accepted standard of stemmed THA. However, we would stress that survival data with longer-term follow-up are needed prior to widespread adoption.

Cite this article: R. B. C. Treacy, J. P. Holland, J. Daniel, H. Ziaee, D. J. W. McMinn. Preliminary report of clinical experience with metal-on-highly-crosslinked-polyethylene hip resurfacing. Bone Joint Res 2019;8:443–450. DOI: 10.1302/2046-3758.810.BJR-2019-0060.R1

Cementing of the hip arthroplasty stem increases load-to-failure force: a cadaveric study

Background and purpose - To date, there is not a single clinical or mechanical study directly comparing a cemented and a cementless version of the same stem. We investigated the load-to-failure force of a cementless and a cemented version of a double tapered stem. Material and methods - 10 femurs from 5 human cadaveric specimens, mean age 74 years (68-79) were extracted. Bone mineral density (BMD) was measured using peripheral quantitative computed tomography. None of the specimens had a compromised quality (average T value 0.0, -1.0 to 1.4). Each specimen from a pair randomly received a cemented or a cementless version of the same stem. A material testing machine was used for lateral load-to-failure test of up to a maximal load of 5.0 kN. Results - Average load-to-failure of the cemented stem was 2.8 kN (2.3-3.2) and 2.2 kN (1.8-2.8) for the cementless stem (p = 0.002). The cemented version of the stem sustained a higher load than its cementless counterpart in all cases. Failure force was not statistically significantly correlated to BMD (p = 0.07). Interpretation - Implanting a cemented version of the stem increases the load-to-failure force by 25%.

Cementless short-stem total hip arthroplasty in the elderly patient - is it a safe option?: a prospective multicentre observational study

Background

Due to its bone preserving philosophy, short-stem total hip arthroplasty (THA) has primarily been recommended for young and active patients. However, there may be benefits for elderly patients given a less invasive operative technique due to the short curved implant design. The purpose of this study was to compare the clinical and radiological outcomes as well as perioperative complications of a calcar-guided short stem between a young (< 60 years) and a geriatric (> 75 years) population.

Methods

Data were collected in a total of 5 centers, and 400 short-stems were included as part of a prospective multicentre observational study between 2010 and 2014 with a mean follow-up of 49.2 months. Preoperative femur morphology was analysed using the Dorr classification. Clinical and radiological outcomes were assessed in both groups as well as perioperative complications, rates and reasons for stem revision.

Results

No differences were found for the mean visual analogue scale (VAS) values of rest pain, load pain, and satisfaction, whereas Harris Hip Score (HHS) was slightly better in the young group. Comparing both groups, none of the radiological parameters that were assessed (stress-shielding, cortical hypertrophy, radiolucency, osteolysis) reached differences of statistical significance. While in young patients aseptic loosening is the main cause of implant failure, in the elderly group particularly postoperative periprosthetic fractures due to accidental fall have to be considered to be of high risk. The incidence of periprosthetic fractures was found to be 0% in Dorr type A femurs, whereas in Dorr types B and C fractures occurred in 2.1 and 22.2% respectively.

Conclusions

Advanced age alone is not necessarily to be considered as contra-indications for calcar-guided short-stem THA, although further follow-up is needed. However, markedly reduced bone quality with femur morphology of Dorr type C seems to be associated with increased risk for postoperative periprosthetic fractures, thus indication should be limited to Dorr types A and B.

Trial registration

German Clinical Trials Register; DRKS00012634, 07.07.2017 (retrospectively registered).

Early postoperative mortality similar between cemented and uncemented hip arthroplasty: a register study based on Finnish national data

Background and purpose - Implant survival of cemented total hip arthroplasty (THA) in elderly patients is higher than that of uncemented THA. However, a higher mortality rate in patients undergoing cemented THA compared with uncemented or hybrid THA has been reported. We assessed whether cemented fixation increases peri- or early postoperative mortality compared with uncemented and hybrid THA. Patients and methods - Patients with osteoarthritis who received a primary THA in Finland between 1998 and 2013 were identified from the PERFECT database of the National Institute for Health and Welfare in Finland. Definitive data on fixation method and comorbidities were available for 62,221 THAs. Mortality adjusted for fixation method, sex, age group, and comorbidities among the cemented, uncemented, and hybrid THA was examined using logistic regression analysis. Reasons for cardiovascular death within 90 days since the index procedure were extracted from the national Causes of Death Statistics and assessed separately. Results - 1- to 2-day adjusted mortality after cemented THA was comparable to that of the uncemented THA group (OR 1.2; 95% CI 0.24-6.5). 3- to 10-day mortality in the cemented THA group was comparable to that in the uncemented THA group (OR 0.54; CI 0.26-1.1), and in the hybrid THA group (OR 0.64, CI 0.25-1.6). Pulmonary embolism or cardiovascular reasons as a cause of death were not over-represented in the cemented THA group. Interpretation - Early peri- and postoperative mortality in the cemented THA group was similar compared with that of the hybrid and uncemented groups.

Mortality after hip resurfacing versus total hip arthroplasty in young patients: a single surgeon experience

Background

The aims of this study were to investigate the following questions: (I) what are the mortality rates in patients age 55 years and younger who underwent a hip resurfacing arthroplasty (HRA) versus a standard total hip arthroplasty (THA)? (II) is the type of operation independently associated with mortality?

Methods

The database of a single high-volume surgeon was reviewed for patient's age 55 years and younger who underwent a hip arthroplasty between 2002 and 2010. This yielded 505 HRA patients and 124 THA patients. Chi-square analysis was performed to identify a 5-year mortality rate difference between the two cohorts. Multivariable Cox-Regression analyses were used to determine whether the type of operation was independently associated with mortality.

Results

There were 8 mortalities (1.6%) in the HRA cohort and 11 (8.9%) in the THA cohort, a statistically significant difference (P<0.001) on univariate analysis. Low mortality rates produced underpowered multivariate models.

Conclusions

We have demonstrated that patients age 55 and younger who undergo HRA have a significantly lower mortality rate than those undergoing THA. This is consistent with multiple previously published large database studies.

The outcome and survival of metal-on-metal hip resurfacing in patients aged less than 50 years

Aims

The aim of this study was to report the implant survival and patient-reported outcome measures (PROMs) in a consecutive series of patients aged less than 50 years at the time of arthroplasty using the Birmingham Hip Resurfacing system (BHR), with a minimum follow-up of ten years.

Patients and Methods

A total of 226 patients with osteoarthritis of the hip, who underwent BHR and presented to a single surgeon, were included in the study. Survival of the implant was confirmed by cross-checking with the Australian Orthopaedic Association National Joint Replacement Registry. Kaplan–Meier survival curves with 95% confidence intervals (CIs) were constructed. Pre- and postoperative PROMs were compared with t-tests, and postoperative scores were compared using anchor analysis with age and gender matched normative data.

Results

At median follow-up of 12 years (interquartile range (IQR) 10 to 13), six BHRs were revised, with a cumulative rate of survival of 96.8% (95% confidence interval (CI) 94.2 to 99.4) at 15 years, and with a significantly lower (p = 0.019) cumulative rate of revision than the national average for the same device at ten years. Most revisions (n = 4) were undertaken early, less than three years postoperatively, and occurred in women. Patient-reported general health (Veteran’s Rand-36), disease state (Western Ontario and McMaster Universities Osteoarthritis Index), function (modified Harris Hip Score) and level of activity (Tegner activity score) maintained significant (p < 0.01 for each) improvements beyond ten years postoperatively and were equal to, or exceeded, age- and gender-matched normative data in more than 80% of the patients.

Conclusion

Longer term PROMs after BHR, from a single surgeon, for patients aged less than 50 years remain under-reported. We found that the outcome after a BHR, at a minimum of ten years postoperatively, remained satisfactory, particularly for self-reported hip function.

Polyethylene Hip Resurfacing to Treat Arthritis and Severe Acetabular Insufficiency

BACKGROUND

Hip dysplasia is the leading cause of hip arthritis in young adults. These patients often participate in active lifestyles that require a full and stable range of motion.

METHODS

Between 2001 and 2011, 232 consecutive polyethylene resurfacing arthroplasties were performed in 201 patients with advanced arthritis from severe acetabular insufficiency due to dysplasia. All patients had Crowe II or III disease. Their mean age at surgery was 43 years. A 2-piece cementless acetabular resurfacing shell with dome screws and a highly cross-linked polyethylene liner were implanted to provide secure fixation, early weight bearing, and a stable hip. Additional structural bone grafts and/or fixation were not used. A cemented or cementless resurfacing prosthesis was used on the femur.

RESULTS

During a mean follow-up of 10 years, 8 hips (3.5%) were converted to a total hip arthroplasty due to acetabular loosening (1), femoral neck fracture (2), femoral osteonecrosis (2), infection (2), or persistent pain (1), resulting in a mean survival of the resurfacing prostheses of 96% (95% confidence interval 89-98). There were no pending revisions and no dislocations. At 2 years postoperative, Harris Hip Scores improved from a preoperative mean of 55 to 97 and University of California Los Angeles activity scores improved from 5 to 8.

CONCLUSION

Hip resurfacing using a 2-piece polyethylene acetabular component for advanced dysplasia has resulted in excellent function and implant survivorship with a low rate of complications at mid-term follow-up.

Using long term mortality to determine which perioperative risk factors of mortality following hip and knee replacement may be causal

Observational studies have identified surgical factors that are associated with a reduced risk of mortality after joint replacement. It is not clear whether these are causal or reflect patient selection. Data on the first primary hip (n = 424,156) and knee replacements (n = 469,989) performed for osteoarthritis in the National Joint Registry were analysed. Flexible parametric survival modelling was used to determine if risk factors for mortality in the perioperative period persisted. To explore selection bias, standardised mortality ratios were calculated for all-cause, respiratory and smoking related cancer mortality using population rates. Selection was apparent for hip resurfacing, combined spinal and general anaesthetic and unicondylar knee implants; reduced mortality was observed for many years for both all and other causes of mortality with a waning effect. Mechanical thromboprophylaxis was also suggestive of selection although patients receiving aspirin had sustained reduced mortality, possibly due to to a cardioprotective effect. Posterior approach for hips was ambiguous with a possible causal component. Spinal anaesthesia was suggestive of a causal effect. We are reliant on observational data when it is not feasible to undertake randomised trials. Our approach of looking at long term mortality risks for perioperative interventions provides further insights to differentiate causal interventions from selection. We recommend the use of aspirin chemothromboprophylaxis, the posterior approach and spinal anaesthetic in total hip replacement due to the apparent causal effect on reduced mortality.

Discrepancy and contradiction regarding fixation of hip stems with or without cement: survey among 765 hip arthroplasty specialists

INTRODUCTION

The growing use of cementless stems is associated with an increase in implant-related complications. This global survey study investigates which parameters orthopaedic surgeons currently consider for either cemented or cementless stem fixation in primary total hip arthroplasty (THA).

METHODS

A survey regarding current practice patterns was distributed among hip arthroplasty specialists. Key questions concerned: (i) frequency of using cemented/cementless stems; (ii) frequency of using parameters which influence a choice between both; (iii) usage of specific cut-off values for parameters.

RESULTS

507 (out of 765) respondents, having at least 5 years' experience and performing at least 50 cases a year, were selected for analysis. Respondents using both fixation techniques ( n = 413; 81%) use a cementless stem in 69% and a cemented stem in 31%. The choice is most frequently based on: (i) patient age; (ii) cortical thickness; (iii) femoral canal shape; (iv) bone mineral density; and (v) stem fit on preoperative templating. 57% using both fixation techniques do not use a specific cut-off value for age. 92% of the respondents that do use a cut-off value for age use exclusively cemented stems in patients being ⩾72.7 years (median 75; range 50-90 years). Considerable discrepancy and even contradictory responses were present regarding the other parameters and the use of specific cut-off values.

CONCLUSIONS

Current practice patterns regarding stem fixation in primary THA vary substantially among orthopaedic surgeons. Evidence-based guidelines are needed to define which parameters and threshold values support the best individual choice for hip stem fixation.

Antibacterial surface modification of titanium implants in orthopaedics

The use of biomaterials in orthopaedics for joint replacement, fracture healing and bone regeneration is a rapidly expanding field. Infection of these biomaterials is a major healthcare burden, leading to significant morbidity and mortality. Furthermore, the cost to healthcare systems is increasing dramatically. With advances in implant design and production, research has predominately focussed on osseointegration; however, modification of implant material, surface topography and chemistry can also provide antibacterial activity. With the increasing burden of infection, it is vitally important that we consider the bacterial interaction with the biomaterial and the host when designing and manufacturing future implants. During this review, we will elucidate the interaction between patient, biomaterial surface and bacteria. We aim to review current and developing surface modifications with a view towards antibacterial orthopaedic implants for clinical applications.

Is Cemented or Cementless Femoral Stem Fixation More Durable in Patients Older Than 75 Years of Age? A Comparison of the Best-performing Stems

BACKGROUND

There is ongoing debate concerning the best method of femoral fixation in older patients receiving primary THA. Clinical studies have shown high survivorship for cemented and cementless femoral stems. Arthroplasty registry studies, however, have universally shown that cementless stems are associated with a higher rate of revision in this patient population. It is unclear if the difference in revision rate is a reflection of the range of implants being used for these procedures rather than the mode of fixation.

QUESTIONS/PURPOSES

(1) Is the risk of revision higher in patients older than 75 years of age who receive one of the three cementless stems with the highest overall survivorship in the registry than in those of that age who received one of the three best-performing cemented stems? If so, is there a difference in risk of early revision versus late revision, defined as revision within 1 month after index surgery? (2) Are there any diagnoses (such as osteoarthritis [OA] or femoral neck hip fracture) in which the three best-performing cementless stems had better survivorship than one of the three best-performing cementless stems? (3) Do these findings change when evaluated by patient sex?

METHODS

The Australian Orthopaedic Association National Joint Replacement Registry data were used to identify the best three cemented and the best three cementless femoral stems. The criteria for selection were the lowest 10-year revision rate and use in > 1000 procedures in this age group of patients regardless of primary diagnosis. The outcome measure was time to first revision using Kaplan-Meier estimates of survivorship. Comparisons were made for THAs done for any reason and then specifically for OA and femoral neck fracture separately.

RESULTS

Overall, the cumulative percent revision in the first 3 months postoperatively was lower among those treated with one of the three best-performing cemented stems than those treated with one of the three best-performing cementless stems (hazard ratio [HR] for best three cementless versus best three cemented = 3.47 [95% confidence interval {CI}, 1.60-7.53], p = 0.001). Early revision was 9.14 times more common in the best three cementless stems than in the best three cemented stems (95% CI, 5.54-15.06, p = 0.001). Likewise, among patients with OA and femoral neck fracture, the cumulative percent revision was consistently higher at 1 month postoperatively among those treated with one of the three best-performing cementless stems than those treated with one of the three best-performing cementless stems (OA: HR for best three cementless versus best three cemented = 8.82 [95% CI, 5.08-15.31], p < 0.001; hip fracture: HR for best 3 cementless versus best three cemented = 27.78 [95% CI, 1.39-143.3], p < 0.001). Overall, the cumulative percent revision was lower in the three best cemented stem group than the three best cementless stem group for both males and females at 1 month postoperatively (male: HR = 0.42 [95% CI, 0.20-0.92], p = 0.030; female: HR = 0.06 [95% CI, 0.03-0.10], p < 0.001) and for females at 3 months postoperatively (HR = 0.15 [95% CI, 0.06-0.33], p < 0.001), after which there was no difference.

CONCLUSIONS

Cementless femoral stem fixation in patients 75 years or older is associated with a higher early rate of revision, even when only the best-performing prostheses used in patients in this age group were compared. Based on this review of registry data, it would seem important to ensure the proper training of contemporary cementing techniques for the next generation of arthroplasty surgeons so they are able to use this option when required. However, the absence of a difference in the two groups undergoing THA after 3 months suggests that there can be a role for cementless implants in selected cases, depending on the surgeon's expertise and the quality and shape of the proximal femoral bone.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Do Patients Live Longer After THA and Is the Relative Survival Diagnosis-specific?

BACKGROUND

Hip replacements are successful in restoring mobility, reducing pain, and improving quality of life. However, the association between THA and the potential for increased life expectancy (as expressed by mortality rate) is less clear, and any such association could well be influenced by diagnosis and patient-related, socioeconomic, and surgical factors, which have not been well studied.

QUESTIONS/PURPOSES

(1) After controlling for birth year and sex, are Swedish patients who underwent THA likely to survive longer than individuals in the general population? (2) After controlling for relevant patient-related, socioeconomic/demographic factors and surgical factors, does relative survival differ across the various diagnoses for which THAs were performed in Sweden?

METHODS

Data from the Swedish Hip Arthroplasty Register, linked to administrative health databases, were used for this study. We identified 131,808 patients who underwent THA between January 1, 1999, and December 31, 2012. Of these, 21,755 had died by the end of followup. Patient- and surgery-specific data in combination with socioeconomic data were available for analysis. We compared patient survival (relative survival) with age- and sex-matched survival data in the entire Swedish population according to Statistics Sweden. We used multivariable modeling proceeded with a Cox proportional hazards model in transformed time.

RESULTS

Patients undergoing elective THA had a slightly improved survival rate compared with the general population for approximately 10 years after surgery. At 1 year after surgery, the survival in patients undergoing THA was 1% better than the expected survival (r = 1.01; 95% confidence interval [CI], 1.01-1.02; p < 0.001); at 5 years, this increased to 3% (r = 1.03; 95% CI, 1.03-1.03; p < 0.001); at 10 years, the difference was 2% (r = 1.02; 95% CI, 1.02-1.03; p < 0.001); and by 12 years, there was no difference between patients undergoing THA and the general population (r = 1.01; 95% CI, 0.99-1.02; p = 0.13). Using the diagnosis of primary osteoarthritis as a reference, hip arthroplasties performed for sequelae of childhood hip diseases had a similar survival rate (hazard ratio [HR], 1.02; 95% CI, 0.88-1.18; p = 0.77). Patients undergoing surgery for osteonecrosis of the femoral head (HR, 1.69; 95% CI, 1.60-1.79; p < 0.001), inflammatory arthritis (HR, 1.49; 95% CI, 1.38-1.61; p < 0.001), and secondary osteoarthritis (HR, 2.46; 95% CI, 2.03-2.99; p < 0.001) all had poorer relative survival. Comorbidities and the Elixhauser comorbidity index had a negative association with relative survival. Level of achieved education (middle level of education: HR, 0.90, 95% CI, 0.87-0.93, p < 0.001; high level: 0.76, 95% CI, 0.73-0.80, p < 0.001) and marital status (single status: HR, 1.33; 95% CI, 1.28-1.38; p < 0.001) were also negatively associated with survival.

CONCLUSIONS

Whereas it has been known that in most patients, THA improves quality of life, this study demonstrates that it also is associated with a slightly increased life expectancy that lasts for approximately 10 years after surgery, especially among patients whose diagnosis was primary osteoarthritis. This adds further proof of a health-economic value for this surgical intervention. The reasons for the increase in relative survival are unknown but are probably multifactorial.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Revision surgery of metal-on-metal hip arthroplasties for adverse reactions to metal debris

Background and purpose - The initial outcomes following metal-on-metal hip arthroplasty (MoMHA) revision surgery performed for adverse reactions to metal debris (ARMD) were poor. Furthermore, robust thresholds for performing ARMD revision are lacking. This article is the second of 2. The first article considered the various investigative modalities used during MoMHA patient surveillance (Matharu et al. 2018a ). The present article aims to provide a clinical update regarding ARMD revision surgery in MoMHA patients (hip resurfacing and large-diameter MoM total hip arthroplasty), with specific focus on the threshold for performing ARMD revision, the surgical strategy, and the outcomes following revision. Results and interpretation - The outcomes following ARMD revision surgery appear to have improved with time for several reasons, among them the introduction of regular patient surveillance and lowering of the threshold for performing revision. Furthermore, registry data suggest that outcomes following ARMD revision are influenced by modifiable factors (type of revision procedure and bearing surface implanted), meaning surgeons could potentially reduce failure rates. However, additional large multi-center studies are needed to develop robust thresholds for performing ARMD revision surgery, which will guide surgeons' treatment of MoMHA patients. The long-term systemic effects of metal ion exposure in patients with these implants must also be investigated, which will help establish whether there are any systemic reasons to recommend revision of MoMHAs.

Hip resurfacing in patients with severe osteoarthritis and blocked medullary canal

INTRODUCTION

This study evaluated the effectiveness of hip resurfacing in patients with femoral deformities or retained femoral implants. Implant removal and conversion total hip replacement (CTHR) have been associated with increased operative time, blood loss, and cost. Removing intramedullary nails in particular can be difficult and can result in a more difficult recovery and/or complications. Hip resurfacing can be performed with a blocked femoral canal and has the possible additional benefits of a less-complex procedure, improved functional outcomes, better patient survivorship, and a possibly less-complicated revision should a failure occur.

MATERIALS AND METHODS

The author performed hip resurfacing in 61 patients (65 hips) with a blocked femur who had been advised elsewhere that they could not undergo THR without also undergoing additional surgical procedures. The perioperative complexity of resurfacing was evaluated by recording operative time, blood loss and functional outcomes using the Harris Hip Score (HHS) and Short-Form 12 (SF-12) questionnaire. Implant survivorship was evaluated by the need for revision surgery.

RESULTS

At 9 years' mean follow-up (range 5-19 years), 59 of the 61 patients presented for postoperative evaluation. The mean operative time was 104 minutes and the mean blood loss was 300 cc. The mean HHS improved from 41 to 92 ( p < 0.001) and the mean SF-12 physical and mental scores improved from 26 to 49 and from 44 to 54, respectively ( p < 0.001). None of the procedures failed or required revision.

CONCLUSION

Canal-sparing hip resurfacing is a successful and less complicated option than CTHR when there is deformity or retained implant blocking the femoral canal.

Hip resurfacing before 50years of age: A prospective study of 979 hips with a mean follow-up of 5.1years

BACKGROUND

Hip resurfacing arthroplasty (HRA) is an alternative to total hip arthroplasty (THA) for the treatment of hip osteoarthritis in patients younger than 50 years. Data on revision rates after HRA are conflicting. The National Institute for Health and Care Excellence (NICE) recommends performing only those hip arthroplasty procedures associated with 10-year revision rates no greater than 5% (0.5% per year). Follow-up studies can rapidly determine whether this criterion is met. The uncertainties surrounding revision rates after HRA prompted us to design a study of prospectively enrolled patients aiming (1) to determine the revision rate after HRA performed before 50years of age and (2) to assess the functional, radiological, and biological outcomes of HRA.

HYPOTHESIS

The revision rate after HRA performed before 50years of age meets the NICE criterion.

MATERIAL AND METHODS

Consecutive patients undergoing HRA before 50years of age were enrolled prospectively. The same implant was used in all patients. Functional outcomes were assessed based on the Harris Hip Score (HHS), Postel-Merle d'Aubigné (PMA) score, 12-item Oxford Hip Score (OHS), and UCLA activity score. Radiographic outcomes were assessed, and blood levels of chromium and cobalt were assayed.

RESULTS

The study included 936 patients (979 HRAs) with a mean age of 42.7years (16.4-50.0years) at surgery and a mean follow-up of 5.1years (range: 3.1-9.0 years). All four mean functional scores were significantly improved at last follow-up vs. baseline: HHS, 95.9 (39.0-100) vs. 44.3 (18.0-83.0); PMA score, 17.6 (6.0-18.0) vs. 11.7 (3.0-16.0); OHS, 14.3 (12.0-37.0) vs. 40.6 (25.0-60.0); and UCLA activity score, 7.8 (2.0-10.0) vs. 5.6 (1.0-10.0) (p<0.0001). Mean cup inclination in the coronal plane was 42.1° (25.0°-68.0°). Mean blood cobalt level was significantly higher at last follow-up than at baseline (1.36μg/L [0.05-8.2μg/L] vs. 0.61μg/L [0.01-3.6]) (p<0.001). No patient experienced dislocation. Revision was required for 17 hips and involved changing the implant in 12 (1.2%). The 10-year survival rate with implant change, as the endpoint was 98.7% (95%CI, 97.6%-99.3%), indicating that the NICE criterion was easily met.

DISCUSSION

The NICE criterion allows the rapid identification of prostheses with insufficient survival. HRA is theoretically associated with a high risk of aseptic mechanical loosening, as it is performed in young patients who have a high level of physical activity. Nevertheless, our study showed that implant survival after HRA was better than required by the NICE criterion. Thus, HRA is a valid alterative to THA in patients younger than 50years.

LEVEL OF EVIDENCE

IV, prospective study with no control group.

Time course and reasons for 90-day mortality in fast-track hip and knee arthroplasty

BACKGROUND

Post-operative mortality is an important adverse outcome, including in total hip (THA) and knee arthroplasty (TKA). However, whether mortality is due to anaesthetic/surgical complications, surgically induced organ dysfunction or unrelated to surgery is rarely considered.

METHODS

Prospective observational study in 13,775 consecutive THA/TKAs with similar fast-track protocols and a median length of stay of 2 days. Complete 90-days follow-up through national registries, followed by review of medical records and death certificates. Relation between mortality and surgically induced organ dysfunction were classified as certain, probable, possible or unlikely.

RESULTS

Of a total of 44 deaths (0.3%), 28 (0.2%) were found to have certain or probably relation with surgery and were considered as surgery-related. Surgery-related deaths were more common after THA than TKA (0.3% vs. 0.1% P = 0.044), occurred after median 14 days and 19 of 28 were between day 0-30. Of the remaining 16 deaths (0.1%), nine were found to be possible and seven to be unlikely related to surgery, and occurred a median of 42 and 61 days after surgery. The most common initial organ dysfunction for surgery-related deaths was pulmonary (6/28) and gastrointestinal (6/28), while the most common reported cause of death were pulmonary (9/28) and cardiac events (6/28). In five of the seven unlikely related deaths mortality was attributed to underlying cancer.

CONCLUSION

Ninety-days mortality was 0.3% in THA and TKA, but only 28 of 44 deaths (64%) were found to be surgery-related. Reporting total mortality rate or cause of death without considerations on surgery induced organ dysfunction, may be insufficient for future aims to reduce post-operative mortality.

Risk of early mortality after cemented compared with cementless total hip arthroplasty

Aims

It has been suggested that cemented fixation of total hip arthroplasty (THA) is associated with an increased peri-operative mortality compared with cementless THA. Our aim was to investigate this through a nationwide matched cohort study adjusting for age, comorbidity, and socioeconomic background.

Patients and Methods

A total of 178 784 patients with osteoarthritis who underwent either cemented or cementless THA from the Swedish Hip Arthroplasty Register were matched with 862 294 controls from the general population. Information about the causes of death, comorbidities, and socioeconomic background was obtained. Mortality within the first 90 days after the operation was the primary outcome measure.

Results

Patients who underwent cemented THA had an increased risk of death during the first 14 days compared with the controls (hazard ratio (HR) 1.3, confidence interval (CI) 1.11 to 1.44), corresponding to an absolute increase in risk of five deaths per 10 000 observations. No such early increase of risk was seen in those who underwent cementless THA. Between days 15 and 29 the risk of mortality was decreased for those with cemented THA (HR 0.7, CI 0.62 to 0.87). Between days 30 and 90 all patients undergoing THA, irrespective of the mode of fixation, had a lower risk of death than controls. Patients selected for cementless fixation were younger, healthier and had a higher level of education and income than those selected for cemented THA. A supplementary analysis of 16 556 hybrid THAs indicated that cementation of the femoral component was associated with a slight increase in mortality up to 15 days, whereas no such increase in mortality was seen in those with a cemented acetabular component combined with a cementless femoral component.

Conclusion

This nationwide matched cohort study indicates that patients receiving cemented THA have a minimally increased relative risk of early mortality that is reversed from day 15 and thereafter. The absolute increase in risk is very small. Our findings lend support to the idea that cementation of the femoral component is more dangerous than cementation of the acetabular component. Cite this article: Bone Joint J 2017;99-B:37–43.

Clinical and Functional Outcomes of the Birmingham Hip Resurfacing System

This study reported the outcomes of patients treated with the Birmingham Hip Resurfacing System (Smith & Nephew, Memphis, Tennessee) to identify the prevalence of complications and failures. A retrospective review of 202 patients (206 hips) was performed. Outcomes were assessed clinically with Harris Hip Score at 6 and 12 months and then yearly. Subanalysis was performed, with the hips divided according to patient sex and size of the femoral component. Mean patient age was 51±8 years, and mean follow-up was 4±1.6 years. Of the patients, 163 were men (83%) and 35 were women (17%). Postoperative improvement was significant, with preoperative Harris Hip Score of 62.9±10.6 and postoperative Harris Hip Score of 98.6±6.7 (P<.001). There were 9 patients (4%) who had complications. A total of 5 hips (2.4%) underwent revision. At 3 years, mean survival was better for men than for women (99% vs 92%, respectively). Survival was lowest in patients with femoral component diameter of less than 46 mm. According to the authors' results, the Birmingham Hip Resurfacing System resulted in good clinical outcomes at 4 years. Survival and outcomes in women, particularly those with modest bone size, are inferior.

An Assessment of Gender-Specific Risk of Implant Revision After Primary Total Hip Arthroplasty: A Systematic Review and Meta-analysis

BACKGROUND

Total hip arthroplasty (THA) has been a successful reconstructive procedure to mitigate pain associated with diseases of the hip joint. However, some THA procedures require revision due to mechanical or biological failure. The purpose of this study was to synthesize and examine the evidence on the relative risk of revision in men and women after primary THA procedures.

METHODS

We conducted a systematic literature review of cohort studies reporting THA revision risk estimate by gender. Study quality scoring and a random effects meta-analysis were performed to estimate the meta-relative risk (meta-RR) and corresponding 95% confidence interval (95% CI) of revision, comparing men to women.

RESULTS

Males had a statistically significant increased risk of revision after primary THA (meta-RR = 1.33 [95% CI: 1.13-1.57]), when compared to females. When stratified by cause of revision, males had a statistically significant increased risk of revision due to any cause (meta-RR = 1.16 [95% CI: 1.01-1.33]), aseptic loosening (meta-RR = 1.54 [95% CI: 1.05-2.25]), and infection (meta-RR = 1.55 [95% CI: 1.11-2.15]). For primary THA operations performed during the 2000s, males in Europe had a statistically significant increased risk of revision (meta-RR 1.42 [95% CI: 1.25-1.61]) while males in the United States had a statistically significant decreased risk of revision (meta-RR 0.80 [95% CI: 0.72-0.89]).

CONCLUSION

These results provide evidence for an increased risk of revision after THA among males, which may be impacted by geographic location and time period of operation. Findings suggest that a better understanding of the underlying drivers of gender-specific risks would help reduce postsurgery complications.

Has Metal-On-Metal Resurfacing Been a Cost-Effective Intervention for Health Care Providers?-A Registry Based Study

Background

Total hip replacement for end stage arthritis of the hip is currently the most common elective surgical procedure. In 2007 about 7.5% of UK implants were metal-on-metal joint resurfacing (MoM RS) procedures. Due to poor revision performance and concerns about metal debris, the use of RS had declined by 2012 to about a 1% share of UK hip procedures. This study estimated the lifetime cost-effectiveness of metal-on-metal resurfacing (RS) procedures versus commonly employed total hip replacement (THR) methods.

Methodology/Principal Findings

We performed a cost-utility analysis using a well-established multi-state semi-Markov model from an NHS and personal and social services perspective. We used individual patient data (IPD) from the National Joint Registry (NJR) for England and Wales on RS and THR surgery for osteoarthritis recorded from April 2003 to December 2012. We used flexible parametric modelling of NJR RS data to guide identification of patient subgroups and RS devices which delivered revision rates within the NICE 5% revision rate benchmark at 10 years. RS procedures overall have an estimated revision rate of 13% at 10 years, compared to <4% for most THR devices. New NICE guidance now recommends a revision rate benchmark of <5% at 10 years. 60% of RS implants in men and 2% in women were predicted to be within the revision benchmark. RS devices satisfying the 5% benchmark were unlikely to be cost-effective compared to THR at a standard UK willingness to pay of £20,000 per quality-adjusted life-year. However, the probability of cost effectiveness was sensitive to small changes in the costs of devices or in quality of life or revision rate estimates.

Conclusion/Significance

Our results imply that in most cases RS has not been a cost-effective resource and should probably not be adopted by decision makers concerned with the cost effectiveness of hip replacement, or by patients concerned about the likelihood of revision, regardless of patient age or gender.

Recent Nanotechnology Approaches for Prevention and Treatment of Biofilm-Associated Infections on Medical Devices

Bacterial colonization in the form of biofilms on surfaces causes persistent infections and is an issue of considerable concern to healthcare providers. There is an urgent need for novel antimicrobial or antibiofilm surfaces and biomedical devices that provide protection against biofilm formation and planktonic pathogens, including antibiotic resistant strains. In this context, recent developments in the material science and engineering fields and steady progress in the nanotechnology field have created opportunities to design new biomaterials and surfaces with anti-infective, antifouling, bactericidal, and antibiofilm properties. Here we review a number of the recently developed nanotechnology-based biomaterials and explain underlying strategies used to make antibiofilm surfaces.

Aseptic loosening of cobalt chromium monoblock sockets after hip resurfacing

INTRODUCTION

Acetabular component loosening is a leading cause for revision after metal-on-metal hip resurfacing arthroplasty (MMHRA). We aimed to identify potential risk factors and determine radiographic signs associated with this mode of failure.

METHODS

From a series of 1375 hips treated with MMHRA, 21 (20 patients) underwent revision surgery secondary to aseptic loosening of the acetabular component and 6 patients had a radiographically loose acetabular component. A control group of 27 hips (26 patients) was selected among the patients that did not have a revision, and was matched for age, gender, component size and diagnosis.

RESULTS

Mean time to revision in the loosening group was 103.0 months and the mean time of follow-up in the control group was 161.4 months. We found greater activity levels, range of motion scores, and cup abduction angles in the loosening group. The centre-edge (CE) angle of Wiberg was 10° lower in the loosening group compared with the control group. In addition, 11 of the hips from the study group presented a sclerotic halo superior to the cup on the last radiograph vs. none in the control group. There was no difference in the prevalence of postoperative reaming gaps or radiographic signs of neck-cup impingement between the 2 groups.

DISCUSSION

Risk factors for acetabular loosening included hip dysplasia with low CE angle, and a large cup abduction angle. The patient's level of activity influences the appearance of symptoms and the time to revision. We recommend selecting patients with a sufficient CE angle and properly orienting the cup.