Is 18F-fluoride PET/CT an Accurate Tool to Diagnose Loosening After Total Joint Arthroplasty?

BACKGROUND: Several studies using positron emission tomography (PET) show highly elevated periprosthetic bone uptake of fluorine-18 sodium fluoride (18F-fluoride), suggestive of implant loosening after arthroplasty. Focus so far has been on qualitative but not on quantitative assessment. There is also a lack of intraoperative confirmation of preoperative 18F-fluoride PET findings. Although the method seems to have acceptable accuracy and high sensitivity, an attempt to improve the specificity and an overall validation of the method appear warranted. QUESTIONS/PURPOSES: (1) Is there a difference in 18F-fluoride uptake around loose versus well-fixed THA and TKA components? (2) Can 18F-fluoride uptake measures provide a threshold that differentiates loose from well-fixed implants undergoing revision for a variety of septic and aseptic indications? (3) In a population restricted to THA and TKA undergoing revision for aseptic indications, can measurement of 18F-fluoride uptake still distinguish loose from well-fixed components? (4) What is the interrater reliability of measuring 18F-fluoride uptake? METHODS: This was a retrospective assessment of a diagnostic test, 18F-fluoride PET/CT, which was performed prior to revision surgery. We included 63 patients with 31 THAs and 32 TKAs. Sixty-five percent of patients were female, and the mean age at 18F-fluoride PET/CT was 66 years. The THA had different modes of fixation (cemented, cementless, and hybrid; 45%, 32%, and 23%, respectively), whereas all TKAs were cemented. Imaging was conducted using routine protocols 1 hour after tracer injection. The interobserver reproducibility was analyzed using Spearman rank correlations and Bland-Altman analyses. Two independent observers were trained separately by a nuclear physician to measure maximal periprosthetic standardized uptake values (SUVmax) for each arthroplasty component (n = 126). Findings at surgery (whether the components were well fixed or loose, as well as the presence or absence of infection) were used as a reference. Presence of periprosthetic joint infection was retrospectively determined based on the criteria suggested by the European Bone and Joint Infection Society (EBJIS): clinical features in combination with blood analysis, synovial fluid cytologic analysis, and microbiology test results. Receiver operating characteristic (ROC) curves were plotted to assess the area under the curve (AUC) for each investigated component separately, indicating suitable SUVmax thresholds that differentiate loose from well-fixed components. After excluding patients with confirmed or suspected PJI per the EBJIS criteria (n = 12), the above analysis was repeated for the remaining patients with aseptic loosening (n = 51). RESULTS: We found higher 18F-fluoride uptake around loose versus well-fixed components in all but femoral TKA components (median [range] SUVmax for well-fixed versus loose THA cups 10 [7 to 30] versus 22 [6 to 64], difference of medians 12; p = 0.003; well-fixed versus loose TKA femoral components 14 [4 to 41] versus 19 [9 to 42], difference of medians 5; p = 0.38). We identified favorable ROC curves for all investigated components except femoral TKA components (THA cups AUC 0.81 [best threshold 13.9]; THA femoral stems AUC 0.9 [best threshold 17.3]; femoral TKA components AUC 0.6 [best threshold 14.3]; tibial TKA components AUC 0.83 [best threshold 15.8]). 18F-fluoride was even more accurate at diagnosing loosening when we limited the population to those patients believed not to have prosthetic joint infection (THA cups AUC 0.87 [best threshold 14.2]; THA femoral stems AUC 0.93 [best threshold 15.0]; femoral TKA components AUC 0.65 [best threshold 15.8]; tibial TKA components AUC 0.86 [best threshold 14.7]). We found strong interrater correlation when assessing SUVmax values, with Spearman ρ values ranging from 0.96 to 0.99 and Bland-Altman plots indicating excellent agreement between the two independent observers. CONCLUSION: Measuring SUVmax after 18F-fluoride PET/CT is a useful adjunct in the diagnostic evaluation for suspected implant loosening after THA and TKA. The method appears to be both accurate and reliable in diagnosing implant loosening for all components except femoral TKA components. In a real-world mixed population with both low-grade infection and aseptic loosening, the method seems to be fairly easy to learn and helpful to subspecialized arthroplasty clinicians. When infection can be ruled out, the method probably performs even better. Further prospective studies are warranted to explore the reason why femoral TKA component loosening was more difficult to ascertain using this novel technique. LEVEL OF EVIDENCE: Level III, diagnostic study.

Continuous periprosthetic bone loss around the TOP® cup and inferior survival rate at an 8-year follow-up: a prospective cohort study.

BACKGROUND: The trabeculae-oriented pattern (TOP®) cup was designed to minimize acetabular periprosthetic bone loss. In our previous prospective study comprising 30 patients with a two-year follow-up we found a substantial decrease in periprosthetic bone mineral density (pBMD) in the proximal and medial regions of the TOP cup. The present study aims to investigate pBMD changes in the mid-term and how this affects implant survival. METHODS: We followed the previous cohort and estimated implant survival by Kaplan-Meier analysis, evaluated pBMD with dual-energy X-ray absorptiometry (DXA) and clinical outcome using the Harris Hip Score (HHS). RESULTS: Mean follow-up was 8.6 (range 7.8-9.1) years. The eight-year implant survival rate for cup revision for all reasons was 83% (95% confidence interval {CI}: 70-97) and 86% (CI: 74-99) when cup revision due to aseptic loosening was the endpoint. Mean HHS at eight years was 95 (range 77-100). A further 12% (CI: 5-17) loss in pBMD was detected in the proximal Digas zone 1 and 12% (CI: 7-17) loss in Digas zone 2 also between two and eight years after surgery. pBMD continued to decrease up to 30% (CI: 24-36) in Digas zones 1, 2 and 3 compared to pBMD immediately postoperatively. CONCLUSIONS: The TOP cup shows inferior mid-term survival rates compared to other uncemented cups, as well as a continuous decrease in pBMD. Periprosthetic bone loss cannot be prevented by this uncemented cup. CLINICAL TRIAL NUMBER: Not applicable.

Risk of conversion to total knee arthroplasty after surgically treated tibial plateau fractures: an observational cohort study of 439 patients.

BACKGROUND AND PURPOSE: We aimed to assess joint failure rate, i.e., subsequent conversion to TKA after surgical treatment of a tibial plateau fracture (TPF). Secondary aims were to explore the association between joint failure and fracture type, and to determine the risk of failure associated with inadequate joint surface reduction. METHODS: We included all patients ≥ 18 years of age with a surgically treated TPF, treated at Uppsala University Hospital between 2002 and 2015. All fractures were classified according to the Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Traumatology Association (AO/OTA) classification. Postoperative radiographs were evaluated to determine the quality of joint surface inadequate reduction, defined as an articular step-off ≥ 2 mm. The study cohort was linked with the Swedish Arthroplasty Register (SAR) for information on subsequent total knee arthroplasty (TKA). RESULTS: 439 patients (57% women) with a mean age of 55 years (SD 17) were included. According to the AO/OTA classification, the fracture distribution was B1: 4.8%, B2: 10%, B3: 47%, C1: 12%, C2: 6.4%, and C3: 19%. 23 patients (5.2%) were converted to a TKA within 2 years of initial surgery, and 34 patients (7.7%) had been converted by the end of follow-up (16 years). AO/OTA type B3 and C3 had a 6.8 (95% confidence interval [CI] 1.6-29) times greater risk of joint failure compared with B1-2 and C1-C2 at 2 years' follow-up. Inadequate joint surface reduction led to an 8.4 (CI 3.6-20) times greater risk of conversion to TKA at 2 years' follow-up. CONCLUSION: Overall, 5.2% were converted to a TKA within 2 years. Fracture types AO/OTA B3 and C3 with a comminuted articular surface and inadequate joint surface reduction were strongly associated with joint failure.

Demographics and risk for containment surgery in patients with unilateral Legg-Calvé-Perthes disease: a national population-based cohort study of 309 patients from the Swedish Pediatric Orthopedic Quality Register.

BACKGROUND AND PURPOSE: It is controversial as to which patients affected by Legg-Calvé-Perthes disease (LCPD) benefit from containment surgery. This population-based study based on data from a national quality registry aims to assess the incidence of LCPD and to explore which factors affect the decision for surgical intervention. METHODS: This observational study involved 309 patients with unilateral LCPD reported between 2015 and 2023 to the Swedish Pediatric Orthopedic Quality Register (SPOQ). Descriptive statistics and logistic regression models were used for analysis. RESULTS: In 2019, the assessed incidence of LCPD in the Swedish population of 2-12-year-olds was 4.2 per 105. 238 (77%) were boys with a mean age of 6 years. At diagnosis, 55 (30%) were overweight or obese, rising to 17 patients (39%) and 16 patients (40%) at 2-year follow-up for surgically and non-surgically treated groups, respectively. At diagnosis, affected hips had reduced abduction compared with healthy hips, and their abduction remained restricted at the 2-year follow-up. Surgically treated patients had inferior abduction compared with non-surgically treated ones at diagnosis. The adjusted risk for containment surgery increased with age and in the presence of a positive Trendelenburg sign but decreased with greater hip abduction. CONCLUSION: We found a lower national yearly incidence (4.2 per 105) than previously reported in Swedish studies. A higher proportion of overweight or obese patients compared with the general Swedish population of 4-9-year-olds was identified. Increasing age, positive Trendelenburg sign, and limited hip abduction at diagnosis correlated with increased surgical intervention likelihood.

Sarcopenia prevalence and incidence in older men - a MrOs Sweden study.

INTRODUCTION: The European Working Group on Sarcopenia in Older People (EWGSOP) published a revised definition of sarcopenia in 2018. There are few incidence studies of sarcopenia following the latest definition. OBJECTIVE: To study prevalence, incidence proportion and incidence rate of sarcopenia in a simple random sample of older Swedish men using the EWGSOP2 definition. METHODS: Men aged 69-81 were invited to participate in the Osteoporotic Fractures in Men (MrOs) Sweden study. Of 2,004 included participants, 1,266 participants (mean age 75.1, SD 3.1 years) completed baseline and 5-year follow-up measurements. We assessed muscle strength by measuring grip strength and chair stands test, lean mass by dual energy X-ray absorptiometry and physical performance by gait speed at baseline and follow-up. Sarcopenia prevalence and incidence were calculated according to the EWGSOP2 definition. RESULTS: Sarcopenia prevalence increased from 5.6% at baseline to 12.0% at follow-up. During the mean 5.2-year follow-up period, 9.1% developed sarcopenia (incidence proportion), corresponding to an incidence rate of 1.8 per 100 person-years at risk while 39.4% of the participants with sarcopenia at baseline participating in follow-up reversed to no longer having confirmed sarcopenia at 5-year follow-up. CONCLUSION: The prevalence of sarcopenia defined along EWGSOP2 criteria doubled within 5 years in older men, and more than a third of the study participants with sarcopenia at baseline did not have sarcopenia at follow-up. We conclude that sarcopenia is not a static condition.

Increasing risk of revision due to infection after primary total hip arthroplasty: results from the Nordic Arthroplasty Register Association.

BACKGROUND AND PURPOSE: The incidence of periprosthetic joint infection after total hip arthroplasty (THA) may be increasing. We performed time-trend analyses of risk, rates, and timing of revision due to infection after primary THAs in the Nordic countries from the period 2004-2018. PATIENTS AND METHODS: 569,463 primary THAs reported to the Nordic Arthroplasty Register Association from 2004 to 2018 were studied. Absolute risk estimates were calculated by Kaplan-Meier and cumulative incidence function methods, whereas adjusted hazard ratios (aHR) were assessed by Cox regression with the first revision due to infection after primary THA as primary endpoint. In addition, we explored changes in the time span from primary THA to revision due to infection. RESULTS: 5,653 (1.0%) primary THAs were revised due to infection during a median follow-up time of 5.4 (IQR 2.5-8.9) years after surgery. Compared with the period 2004-2008, the aHRs for revision were 1.4 (95% confidence interval [CI] 1.3-1.5) for 2009-2013, and 1.9 (CI 1.7-2.0) for 2014-2018. The absolute 5-year rates of revision due to infection were 0.7% (CI 0.7-0.7), 1.0% (CI 0.9-1.0), and 1.2% (CI 1.2-1.3) for the 3 time periods respectively. We found changes in the time span from primary THA to revision due to infection. Compared with 2004-2008, the aHR for revision within 30 days after THA was 2.5 (CI 2.1-2.9) for 2009-2013, and 3.4 (CI 3.0-3.9) for 2013-2018. The aHR for revision within 31-90 days after THA was 1.5 (CI 1.3-1.9) for 2009-2013, and 2.5 (CI 2.1-3.0) for 2013-2018, compared with 2004-2008. CONCLUSION: The risk of revision due to infection after primary THA almost doubled, both in absolute cumulative incidence and in relative risk, throughout the period 2004-2018. This increase was mainly due to an increased risk of revision within 90 days of THA. This may reflect a "true" increase (i.e., frailer patients or more use of uncemented implants) and/or an "apparent" increase (i.e., improved diagnostics, changed revision strategy, or completeness of reporting) in incidence of periprosthetic joint infection. It is not possible to disclose such changes in the present study, and this warrants further research.

Time to entry point and distal locking of intramedullary nails: a methodological phantom study comparing biplanar and uniplanar surgical imaging.

BACKGROUND: Intramedullary nailing is the method of choice for diaphyseal fractures of the femur and tibia and is also commonly used to treat trochanteric hip fractures. Perioperative imaging is essential for visualising adequate reduction, achieving an optimal entry point (EP) and performing distal locking (DL) of intramedullary nails. This methodological study aims to compare biplanar and uniplanar imaging in some steps of intramedullary nailing. METHODS: We used a biplanar preassembled imaging device (Biplanar™ 600s, Swemac Imaging) and a uniplanar imaging device (Ziehm Solo FD, Ziehm Imaging) to measure procedural and radiation times for antegrade and retrograde femoral and antegrade tibial nailing in fully soft flexible tissue encased legs with radiopaque sawbones (SKU:1515-7-11, Sawbones Europe, Malmö, Sweden). Four orthopaedic surgeons with different levels of experience performed all procedures in all three phantoms with both image techniques in random order, producing in total 12 EPs and nailings with DL with each imaging device. Time to EP, radiation times, time to DL for both devices and the number of swings of the uniplanar device for the two procedures were measured. Comparisons between the biplanar and uniplanar systems with a paired-samples t-test were conducted. RESULTS: Using the biplanar device, time to optimal EP was shorter for retrograde femoral (26 s (SD15) vs 35 s (SD13), p = 0.01) and for antegrade tibial nailing (23 s (SD13) vs 49 s (SD24), p = 0.001). No statistically significant differences in time to EP, radiation time or time to DL were found for antegrade femoral nailing. A median of two swings of the uniplanar device was needed to obtain optimal EP for all procedures. CONCLUSIONS: Biplanar imaging slightly but statistically significantly reduced time to EP for retrograde femoral and antegrade tibial nailing in this methodological study comparing biplanar and uniplanar imaging techniques. Biplanar imaging can reduce time and radiation exposure when defining the EP around the knee in intramedullary nailing procedures, but the clinical relevance of these time savings remain to be defined. For antegrade femoral nailing we found no clear benefit with biplanar imaging in the investigated steps of nailing.

The Swedish Fracture Register - ten years of experience and 600,000 fractures collected in a National Quality Register.

BACKGROUND: Before the creation of the Swedish Fracture Register (SFR), there was no national quality register that prospectively collects data regarding all types of fractures regardless of treatment in an emergency setting. Observational data on fractures registered in a sustainable way may provide invaluable tools for quality improvements in health care and research. DESCRIPTION: Ten years after its implementation, the Swedish Fracture Register has 100% coverage among orthopaedic and trauma departments in Sweden. The completeness of registrations reached in 2020 69-96% for hip fractures at the different departments, with the majority reporting a completeness above 85%. The Swedish Fracture Register is a fully web-based national quality register created and run by orthopaedic professionals, with financial support from public healthcare providers and the government. All users have full access to both the registration platform and all aggregated statistics in real time. The web-based platform was created for use in health quality registers and it has easily gained acceptance among users. The register has gradually developed by the addition of more fracture types and skeletal parts. Research activity is high and 31 scientific publications have been published since 2016. The strategy from the start was to publish validation data and basic epidemiological data. However, over the past few years, publications on outcomes, such as re-operations and mortality, have been published and four register-based, randomised, controlled trials are ongoing. CONCLUSION: It is possible to create a fracture register, to gain professional acceptance and to collect fracture data in a sustainable way on a national level if the platform is easy to use. Such a platform can also be used as a randomisation platform for prospective studies.

Similar risk of cancer in patients younger than 55 years with or without a total hip arthroplasty (THA): a population- based cohort study on 18,771 exposed to THA and 87,683 controls.

BACKGROUND AND PURPOSE: Concerns related to a potentially increased risk of cancer after total hip arthroplasty (THA) have frequently surfaced, especially since the novel EU medical device regulation classified cobalt as carcinogenic. We assessed the risk of cancer after THA in a nationwide cohort of patients younger than 55 years at surgery. PATIENTS AND METHODS: In this population-based longitudinal cohort study, 18,771 individuals exposed to THA were identified in the Swedish Hip Arthroplasty Registry (SHAR) and compared with 87,683 unexposed individuals who were matched by age, sex, and residence. Diagnoses, socioeconomic background, and dates of death were obtained from the Swedish Cancer Register, the National Patient Register, and Statistics Sweden. Primary outcome was the adjusted risk of any cancer after the first THA; secondary outcomes were specific cancer forms. RESULTS: We found no enhanced adjusted risk of developing any cancer, either in exposed females compared with unexposed females (hazard ratio [HR] 1.1, 95% confidence interval [CI] 0.95-1.2), or in exposed males (HR 1.1, CI 0.99-1.2). When analysing specific cancers, increased adjusted risks were found for thyroid and pancreas cancer in exposed females, and for cancer of the stomach, skin melanoma, and prostate cancer in exposed males. INTERPRETATION: This study indicates that there is no statistically significant increased overall risk of cancer in young THA-exposed patients. The potentially slightly enhanced risk for specific cancers may be due to residual confounding resulting from risk factors not accounted for and merits further investigation.

Increased mortality after intramedullary nailing of trochanteric fractures: a comparison of sliding hip screws with nails in 19,935 patients.

Background and purpose - Intramedullary nails (IMN) have become increasingly common as treatment for trochanteric hip fractures (THF) although they are costlier, and without proven superiority compared with sliding hip screws (SHS). We investigated whether the 2 methods differ in terms of short-term mortality when used in fractures where both methods are suitable. Patients and methods - We extracted data from the Swedish Fracture Register (SFR) on 19,935 patients ≥ 60 years with trochanteric fractures AO type 31-A1 or -A2 who had been treated with either SHS or IMN. We assessed absolute mortality rates and the relative risks (RR) of death after 7, 30, 90, and 365 days using generalized linear models, adjusting for age, sex, and fracture type. We performed a sensitivity analysis on a subgroup of 3,673 patients with information on comorbidity to address this potential confounder. Results - 69% of the patients were women and mean age was 84 years (60-107). IMN was used in 35% of A1 and in 71% of A2 fractures. The use of IMN was associated with a slightly increased adjusted risk of death within 30 days compared with SHS (RR = 1.1, 95% CI 1.0-1.2) with no difference at any other time point. Interpretation - The slightly increased risk of death up to 30 days postoperatively does not support the use of IMN instead of SHS in stable THF.

Study protocol: The DAICY trial-dual versus single-antibiotic impregnated cement in primary hemiarthroplasty for femoral neck fracture-a register-based cluster-randomized crossover-controlled trial.

BACKGROUND AND PURPOSE: Older patients with a displaced femoral neck fracture (FNF) are often treated with a cemented primary hemiarthroplasty (HA). The DAICY trial investigates whether high-dose dual-impregnated antibioticloaded cement (DIAC) including gentamicin and clindamycin can reduce the risk of periprosthetic joint infection (PJI) in comparison with low-dose single-impregnated gentamicin antibiotic-loaded cement (SIAC), in patients ≥ 60 years treated with a cemented HA for a displaced FNF. STUDY DESIGN: The trial is a national, multicenter, register-based, cluster-randomized, crossover trial. Patients ≥ 60 years with a non-pathological, displaced FNF (Type Garden 3-4/AO 31-B2 or B3) suitable for HA according to local guidelines are eligible for inclusion. Participating orthopedic departments will be randomized to start with either SIAC (control group) or DIAC treatment (intervention group) for 2 years. After 2 years, the study departments will then change to the other treatment arm for the remaining 2 years of the study. Approximately 7,000 patients will be included. The study is pragmatic in that the choice of implant brands, surgical approach and peri- and postoperative protocols follow the local routines of each participating department. All outcome variables will be retrieved after linkage of the study cohort to the following Swedish registers: the Fracture Register, the Arthroplasty Register, the National Patient Register and the Prescribed Drug Registry Outcome: The primary outcome will be periprosthetic joint infection of the index joint within 1 year after surgery. Secondary outcomes will be any reoperation on the index joint, mortality within 90 days and 1 year, resistance patterns of causative bacteria in cases of PJI, and health economics. Potential added value: This trial is designed to support or refute the efficacy of DIAC used in patients with a displaced FNF, potentially reducing PJI and resource allocation. Start of the trial and estimated duration - The DAICY trial started recruiting patients in January 2022 and will continue recruiting for approximately 4 years. Complete follow-up expected in 5 years.

Denosumab prevents acetabular bone loss around an uncemented cup: analysis of secondary outcomes in a randomized controlled trial.

BACKGROUND AND PURPOSE: Uncemented total hip arthroplasty (THA) is associated with periprosthetic bone loss. In a secondary outcome analysis from a randomized controlled trial, we studied whether denosumab can prevent loss of acetabular periprosthetic bone mineral density (pBMD) in patients who received a trabecular metal cup during uncemented THA. PATIENTS AND METHODS: 64 patients (aged 35-65 years) with unilateral osteoarthritis of the hip were randomized to 2 subcutaneous injections with denosumab or placebo, given 1-3 days post-surgery and 6 months post-surgery. Acetabular pBMD was measured in 5 regions of interest (ROIs) by dual-energy X-ray absorptiometry. Serum markers for bone metabolism were analyzed. Periprosthetic osteoblastic activity, measured as standardized uptake values (SUVs) by [18F] positron emission tomography/computed tomography, was evaluated in 32 of the 64 study patients. RESULTS: After 12 months, patients treated with denosumab had higher pBMD compared with the placebo-treated patients in 4 of 5 ROIs and in sum of ROIs 1-5. After 24 months, the effect on pBMD for patients treated with denosumab declined. Serum markers declined pronouncedly up to 12 months in patients treated with denosumab, but rebounded above baseline levels after 24 months. Patients treated with denosumab had statistically significantly lower SUVs in all ROIs, except ROI 5, after 6 months. INTERPRETATION: Based on this exploratory analysis of secondary endpoints the application of denosumab seems associated with preserved acetabular pBMD, reduced bone metabolism and attenuated periprosthetic osteoblastic activity. However, given the known rebound affects after discontinuation of denosumab treatment, these effects cannot be expected to persist. If prolonged treatment or shift to other regimes would be beneficial to reduce the risk of cup loosening is yet to be investigated.

How deadly is a fracture distal to the hip in the elderly? An observational cohort study of 11,799 femoral fractures in the Swedish Fracture Register.

Background and purpose - Unlike hip fractures, diaphyseal and distal femoral fractures in elderly patients have not been widely studied. We investigated the demographics, comorbidities and mortality of patients with femoral fractures at any anatomical level with a focus on early mortality.Patients and methods - We analyzed 11,799 patients ≥ 65 years with a femoral fracture registered in the Swedish Fracture Register from 2011 to 2014. The cohort was matched with the National Patient Register to obtain data on comorbidities classified according to the Charlson Comorbidity Index (CCI). Generalized linear models were fitted to estimate the adjusted relative risk of mortality.Results - Mean age of the cohort was 83 years and 69% were women. Patients with distal femoral fractures had the lowest degree of comorbidity, with 9% having a CCI of ≥ 3 compared with 14% among those with proximal and 16% among those with diaphyseal fractures. Unadjusted 90-day mortalities were 13% (95% CI 9.4-16) after fractures in the distal, 13% (CI 10-16) in the diaphyseal, and 15% (CI 14-15) in the proximal segment. The adjusted relative risk for 90-day mortality was 1.1 (CI 0.86-1.4) for patients with distal and 0.97 (CI 0.76-1.2) for patients with diaphyseal femoral fractures when compared with patients with hip fractures.Interpretation - Elderly patients with femoral fractures distal to the hip may have similar adjusted early mortality risks to those with hip fractures. There is a need for larger, preferably prospective, studies investigating the effect of rapid pathways and geriatric co-management for patients with diaphyseal and distal femoral fractures.

No increased mortality after total hip arthroplasty in patients with a history of pediatric hip disease: a matched, population-based cohort study on 4,043 patients.

Background and purpose - Patients with pediatric hip diseases are more comorbid than the general population and at risk of premature, secondary osteoarthritis, often leading to total hip arthroplasty (THA). We investigated whether THA confers an increased mortality in this cohort.Patients and methods - We identified 4,043 patients with a history of Legg-Calvé-Perthes disease (LCPD), slipped capital femoral epiphysis (SCFE), or developmental dysplasia of the hip (DDH) in the Swedish Hip Arthroplasty Register (SHAR) between 1992 and 2012. For each patient, we matched 5 controls from the general population for age, sex, and place of residence, and acquired information on all participants' socioeconomic background and comorbidities. Mortality after THA was estimated according to Kaplan-Meier, and Cox proportional hazard models were fitted to estimate adjusted hazard ratios (HRs) for the risk of death.Results - Compared with unexposed individuals, patients exposed to a THA due to pediatric hip disease had lower incomes, lower educational levels, and a higher degree of comorbidity but a statistically non-significant attenuation of 90-day mortality (HR 0.9; 95% CI 0.4-2.0) and a lower risk of overall mortality (HR 0.8; CI 0.7-0.9).Interpretation - Patients exposed to THA due to a history of pediatric hip disease have a slightly lower mortality than unexposed individuals. THA seems not to confer increased mortality risks, even in these specific patients with numerous risk factors.

Uncemented or cemented stems in first-time revision total hip replacement? An observational study of 867 patients including assessment of femoral bone defect size.

Background and purpose - Uncemented stems are gradually replacing cemented stems in hip revision surgery. We compared the risk of re-revision between uncemented and cemented revision stems and assessed whether the different fixation methods are used in similar femoral bone defects.Patients and methods - 867 patients operated on with uncemented or cemented stems in first-time hip revision surgery due to aseptic loosening performed 2006-2016 were identified in the Swedish Hip Arthroplasty Register. Preoperative femoral bone defect size was assessed on radiographs of all patients. Cox regression models were fitted to estimate the adjusted risk of re-revision during different postoperative time periods. Re-revision of any component for any reason, and stem re-revision, as well as risk of cause-specific re-revision was estimated.Results - Most patients in both fixation groups had Paprosky class IIIA femoral bone defects prior to surgery, but there were more severe bone defects in the cemented group. The adjusted risk of re-revision of any component for any reason was higher in patients with uncemented compared with those with cemented revision stems during the first 3 years after index surgery (hazard ratio [HR] 4, 95% confidence interval [CI] 2-9). From the 4th year onward, the risk of re-revision of any component for any reason was similar (HR 0.5, CI 0.2-1.4). Uncemented revision stems conferred a higher risk of dislocation compared with cemented stems (HR 5, CI 1.2-23) during the first 3 years.Interpretation - Although not predominantly used in more complex femoral defects, uncemented revision stem fixation confers a slightly higher risk of re-revision during the first years, but this risk is attenuated after longer follow-up.

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.

No generally increased risk of cancer after total hip arthroplasty performed due to osteoarthritis.

Previous studies on the risk of cancer after total hip arthroplasty (THA) contradict each other, and many are hampered by small cohort sizes, residual confounding, short observation times or a mix of indications underlying the THA procedure. We evaluated the risk of cancer after total hip arthroplasty due to osteoarthritis in a nationwide cohort by comparing cancer incidences in individuals exposed to total hip arthroplasty due to osteoarthritis and in unexposed, sex-, age- and residence matched individuals. To address some previous studies' shortcomings, information on comorbidity and socioeconomic background were obtained and adjusted for. We included 126,276 patients exposed to a cemented THA between 1992 and 2012, and 555,757 unexposed individuals. Follow-up started on the day of surgery for exposed individuals and respective date for matched, unexposed individuals, and ended on the day of death, emigration, censuring or December 31st, 2012, whichever came first. The Swedish Hip Arthroplasty Registry (SHAR), the Swedish Cancer Registry, the Swedish National Patient Registry and Statistics Sweden were accessed to obtain information on procedural details of the THA, cancer diagnoses, comorbidities, and socioeconomic background. The primary outcome measure was the occurrence of any cancer after the index date. Exposed individuals had a slightly lower adjusted risk of developing any cancer than unexposed individuals (hazard ratio [HR] 0.97; CI 0.95-0.99). The only cancer with a statistically significant risk increase in exposed individuals was skin melanoma (HR 1.15; CI 1.05-1.24). We attained similar risk estimates in analyses stratified by sex, in individuals with minimum 5 years of follow-up, in an analysis including individuals with a history of previous cancer, and in patients with cementless THA. In this study on a large and well-defined population with long follow-up, we found no increased overall risk of cancer after THA. These reassuring findings could be included in the guidelines on preoperative information given to THA patients.

Study protocol: HipSTHeR - a register-based randomised controlled trial - hip screws or (total) hip replacement for undisplaced femoral neck fractures in older patients.

BACKGROUND: Femoral neck fractures (FNFs), which are common in the older population, are associated with high mortality and morbidity. Some 20% of FNFs are undisplaced (uFNFs). The routine surgical procedure for uFNFs is internal fixation (IF) with 2-3 screws/pins with a reported reoperation rate in older patients (age ≥ 75 years) of up to 21%. The reoperation rate for hemiarthroplasties for displaced fractures is lower than for undisplaced fractures operated with IF. This study will aim to determine whether the outcome for older patients with an uFNF can be improved by replacing the hip instead of preserving it. METHODS: A national multicentre, register-based, randomised controlled trial (rRCT) will be conducted. For this trial, 1440 patients, ≥75 years with an acute uFNF, will be allocated. Eligible patients will be identified by the Swedish Fracture Register (SFR) platform, which will notify the admitting orthopaedic surgeon of eligibility. After informed consent has been given and documented, patients will be randomised to either IF (control group) or arthroplasty (intervention group) within the SFR platform. Injury mechanism, fracture classification, date of injury, and type of treatment are registered in the SFR. Type and brand of arthroplasty, surgical approach, and fixation are obtained from the Swedish Hip Arthroplasty Register (SHAR). The study cohort from the SFR will be cross-checked with the National Patient Register and the SHAR for outcome variables at 2, 5, and 10 years. The primary outcome will be a composite variable comprising reoperation rate and mortality at 2 years postoperatively. Secondary endpoints will include reoperation rate and mortality as stand-alone variables. In addition, secondary endpoints will be patient-reported outcomes as measured by the Short Musculoskeletal Functional Assessment questionnaire at 1 year postoperatively as routinely collected within the SFR. Further secondary endpoints will include the occurrence of adverse events such as pneumonia, stroke or myocardial infarction and evaluation of the external validity of the study. DISCUSSION: This large, multicentre, register-based randomised controlled trial could potentially shift the treatment of uFNFs in older patients towards primary hip arthroplasty in order to improve the outcome. TRIAL REGISTRATION: The trial is registered at www.clinicaltrials.gov (NCT03966716); May 29, 2019.

Two-component surface replacement implants compared with perichondrium transplantation for restoration of Metacarpophalangeal and proximal Interphalangeal joints: a retrospective cohort study with a mean follow-up time of 6 respectively 26 years.

BACKGROUND: The aim of our study was to compare the long-term outcome after perichondrium transplantation and two-component surface replacement (SR) implants to the metacarpophalangeal (MCP) and the proximal interphalangeal (PIP) joints. METHODS: We evaluated 163 joints in 124 patients, divided into 138 SR implants in 102 patients and 25 perichondrium transplantations in 22 patients. Our primary outcome was any revision surgery of the index joint. RESULTS: The median follow-up time was 6 years (0-21) for the SR implants and 26 years (1-37) for the perichondrium transplants. Median age at index surgery was 64 years (24-82) for SR implants and 45 years (18-61) for perichondium transplants. MCP joint survival was slightly better in the perichondrium group (86.7%; 95% confidence interval [CI]: 69.4-100.0) than in the SR implant group (75%; CI 53.8-96.1), but not statistically significantly so (p = 0.4). PIP joint survival was also slightly better in the perichondrium group (80%; CI 55-100) than in the SR implant group (74.7%; CI 66.6-82.7), but below the threshold of statistical significance (p = 0.8). CONCLUSION: In conclusion, resurfacing of finger joints using transplanted perichondrium is a technique worth considering since the method has low revision rates in the medium term and compares favorable to SR implants. LEVEL OF EVIDENCE: III (Therapeutic).

Study protocol: The DUALITY trial-a register-based, randomized controlled trial to investigate dual mobility cups in hip fracture patients.

Background and purpose - Physically and mentally fit patients with a displaced femoral neck fracture (FNF) are mostly treated with total hip arthroplasty (THA). Dislocation is a severe and frequent complication in this group, and dual mobility cups (DMC) were developed to reduce the risk of dislocation after THA. The DUALITY trial investigates whether the use of DMC in FNF patients treated with a THA reduces the risk of dislocation.Patients and methods - The trial is a national, multicenter, register-based, randomized controlled trial (rRCT). Patients ≥ 65 years with a non-pathological, displaced FNF (Type Garden 3-4/AO 31-B2 or B3) who are suitable for a THA according to local guidelines are assessed for eligibility using the web-based registration platform of the Swedish Fracture Register (SFR). 1,600 patients will be randomized 1:1 to either insertion of a DMC (intervention group) or a standard cup (control group). The study is pragmatic in that the choice of implant brands, surgical approach, and peri- and postoperative protocols follow the local routines of each participating unit. All outcome variables will be retrieved after linkage of the study cohort obtained from the SFR with the Swedish Hip Arthroplasty Register and the National Patient Register.Outcomes - The primary outcome is the occurrence of any dislocation of the index joint treated with closed or open reduction within 1 year after surgery, expressed as a relative risk when comparing groups, and a risk reduction of at least 45% is considered clinically relevant. Secondary outcomes are the relative risk of any reoperation of the index joint, periprosthetic joint infection, and mortality within 90 days and 1 year. Patient-reported outcomes and health economics are evaluated.Start of trial and estimated duration - The DUALITY trial started recruiting patients in January 2020 and will continue for approximately 5 years.Trial registration - The trial is registered at clinicaltrials.gov (NCT03909815; December 12, 2019).