Decreased burden of revision hip replacements despite substantial rise in prevalence: a register-based analysis in Finland.

BACKGROUND AND PURPOSE: While the incidence of THR operations has been established, little is known about the prevalence or the ratio of the annual number of revision THRs to the total number of THRs in the general population. By combining data from nationwide registers, we calculated the annual prevalence of THRs and the revision burden caused by THR survivors in Finland. PATIENTS AND METHODS: All primary THRs performed between 1980 and 2020 were identified from the Finnish Arthroplasty Register (FAR). Patient deaths were extracted from the Finnish Digital and Population Data Services Agency and THR revisions and removals from the FAR and the Finnish Hospital Discharge Register. We analyzed annual THR prevalence by dividing the number of THRs by the population aged 40 or older and the revision burden factor (RBF) by dividing the annual number of revisions by the total number of primary and revision THRs in the population. The proportions of bilateral implants and patients with THRs performed more than 10 years earlier (older THRs) were identified. RESULTS: THR prevalence in Finland increased rapidly, reaching 3.6% in 2020. Between 2010 and 2020, the number of THRs increased by 50% and the prevalence of THRs by 38%. In 2020, the proportion of bilateral THRs had risen to 29% and the proportion of patients with older THRs to 36%. The RBF decreased between 1996 and 2020 from 3.1% to 1.3% (age- and sex-adjusted proportion ratio PR 0.42 [95% CI 0.39-0.45]). INTERPRETATION: Despite the decrease in the RBF, the rapidly increasing prevalence of THRs potentially increases the number of revisits and revisions and thus poses a challenge for healthcare in the future.

Rapid rise in prevalence of knee replacements and decrease in revision burden over past 3 decades in Finland: a register-based analysis.

BACKGROUND AND PURPOSE: The prevalence of knee joint replacements (KJR) has been less investigated in situations where the increase in incidence is known. This study investigated the annual and population-based prevalence of KJR and the relationship between the prevalence of KJRs and the incidence of revision surgery. PATIENTS AND METHODS: All KJRs performed between 1980 and 2020 were identified from the Finnish Arthroplasty Register (FAR). KJR revisions and removals were extracted from the FAR and hospital discharge registers and patient deaths from Finnish Digital and Population Data Services Agency. We analyzed the annual prevalence by dividing the number of KJR survivors by the population aged 40 or older. The revision burden factor (RBF) was determined by dividing the annual number of revisions by the number of primary and revision KJRs in the population. Proportions of bilateral implants and patients with older KJRs performed 10 or more years earlier were identified. RESULTS: KJR prevalence in Finland increased by 298% between 2000 and 2020, reaching 4.0% in 2020. The proportion of patients with bilateral KJRs and those with older KJRs had increased to 37% and 34%, respectively, by 2020. The annual RBF decreased statistically significantly from 1.9% to 0.7% between 1996 and 2020 (proportion ratio, PR 0.37 [95% CI 0.33-0.42]) and was higher among males (PR 1.23 [CI 1.20-1.26]). INTERPRETATION: Although the recent rapid increase in KJRs is abating and the RBF is diminishing, it is important to take the continuing increase in the prevalence of KJRs into account when assessing hospitals' future resources.

Mid-term outcomes of the R3™ delta ceramic acetabular system in total hip arthroplasty.

BACKGROUND: Whilst bony fixation of hip replacement has stable solutions, there remains controversy over which bearing best optimizes longevity and function. Ceramic-on-ceramic (CoC) bearing combinations are associated with lower risk of revision due to aseptic loosening and dislocation. Evidence for long-term functional outcomes of modern, 4th generation CoC bearings is limited. The aim of this study was to analyze outcomes and complications of the R3™ Acetabular System (Smith & Nephew, Inc., Cordova, TN, USA) in combination with BIOLOX® Delta ceramic femoral head in patients undergoing primary total hip arthroplasty (THA). METHODS: Between June 2009 and May 2011, 175 patients (178 hips) were enrolled into a prospective, study at 6 sites in Europe and prospectively followed-up at 3 months and 1, 3, 5, and 7 years postoperative. RESULTS: Total WOMAC score improved from 63 (range, 22-91) preoperative to 8 (range, 0-8) at 1-year follow-up and remained unchanged at 7-year follow-up. Modified Harris hip score improved from 45 (range, 10-87) preoperative to 83 (range, 25-100) at 3 months, 91 (range, 42-100) at 1 year, and 92 (range, 46, 100) at 7 years. UCLA Activity Rating Scale score improved from 3.3 (range, 1-8) preoperative to 6.2 (range, 2-8) at 1 year; it marginally declined to 5.8 (range, 3-8) at 7-year follow-up. There were 4 trochanteric fractures and 5 patients died of unrelated reasons. Three hips were revised (2 periprosthetic fractures and 1 subluxation). The 7-year cumulative survival rate was 98.3%. CONCLUSION: Clinical and functional improvements of THA with CoC bearing are maintained at 7 years postoperative. TRIAL REGISTRATION: ClinicalTrials.Gov, NCT03566082 , Registered 10 January 2018-retrospectively registered.

Large head ceramic-on-ceramic bearing in primary total hip arthroplasty: average 3-year follow-up of a multicentre study.

BACKGROUND: Surgeons are increasingly using larger femoral head sizes in total hip arthroplasty (THA) to improve stability and reduce the rate of dislocation, 1 of the leading causes of revision surgery. Large ceramic head sizes up to 48 mm can now be used with monoblock acetabular components. National registries have shown promising results at short-term with large diameter ceramic-on-ceramic THA, with very low revision rates.This study reports on the average 3-year follow up of a press-fit monoblock large diameter acetabular shell with a pre-assembled ceramic liner, with emphasis on the radiographic outcome, complications related to the implantation of the cup, and the patient's clinical outcome. METHODS: 170 hips in 169 patients were reviewed at an average 38 ± 5.8 months following surgery. RESULTS: The radiographic review revealed no acetabular cup loosening, no osteolysis and no cup migration. 1 acetabular cup was revised for malposition. The patient clinical outcome and the satisfaction rate were excellent. At 3 years, 7.1% of patients complained of groin pain and 3.5% spontaneously reported hip joint generated noise. 1 patient sustained a non-recurrent traumatic hip dislocation 2 years post surgery. CONCLUSIONS: New technology should be introduced cautiously on the market. This is especially true for the large diameter ceramic monoblock acetabular component used in this study since it involves a new acetabular component design. At short term, we have not identified new modes of failure with this implant. Longer follow-up is still needed to assess the safety of large ceramic bearing in THA.

Dislocation of large-diameter head metal-on-metal total hip arthroplasty and hip resurfacing arthroplasty.

INTRODUCTION: Dislocation of large-diameter head (LDH) metal-on-metal (MoM) total hip arthroplasty (THA) or hip resurfacing arthroplasty (HRA) is a rare complication. This study aimed to determine the incidence and risk factors for dislocation of LDH MoM THAs and HRAs. METHODS: This retrospective analysis considered 4038 cementless LDH MoM THAs and HRAs, 3207 THAs in 2912 patients and 831 HRAs in 757 patients. The end of follow-up was revision due to dislocation. Incidence of dislocation was evaluated from this study population of 4038, and study groups were formed. The study was designed as a case-control study, and a threefold stratified randomised control group was formed. Demographic data were collected and radiological analyses were performed in the study groups. RESULTS: There were 26/3207 (0.8%) early dislocations in the THA group, and 6/831 (0.7%) in the HRA group ( p = 0.9). Most LDH THA dislocations occurred in a group with head size ⩽ 38 mm (18/26) ( p < 0.001). In dislocated hips, there were more dysplastic acetabula and post-traumatic hips than in the control group ( p = 0.036). In the dislocation group, the mean acetabulum component anteversion angle was 19.6° (standard deviation [SD] 13.4°) and in the control group it was 23.2° (SD 10.4°) ( p = 0.006); 7/32 (21.8%) of dislocated THAs needed revision surgery, and mean time to revision from the index surgery was 1.2 (SD 2.6) years. DISCUSSION: Dislocations occurred more often in THAs of head size ⩽ 38 mm and with a smaller anteversion angle of the acetabulum component. Hip dysplasia and post-traumatic osteoarthritis were more common in patients with dislocation.

Reduced length of uninterrupted institutional stay after implementing a fast-track protocol for primary total hip replacement.

Background and purpose - Fast-track protocols have been successfully implemented in many hospitals as they have been shown to result in shorter length of stay (LOS) without compromising results. We evaluated the effect of fast-track implementation on the use of institutional care and results after total hip replacement (THR). Patients and methods - 3,193 THRs performed in 4 hospitals between 2009-2010 and 2012-2013 were identified from the Finnish Hospital Discharge Register and the Finnish Arthroplasty Register. Hospitals were classified as fast-track (Hospital A) and non-fast-track (Hospitals B, C, and D). We analyzed LOS, length of uninterrupted institutional care (LUIC, including LOS), discharge destination, readmission, revision rate, and mortality in each hospital. We compared these outcomes for THRs performed in Hospital A before and after fast-track implementation and we also compared outcomes, excluding readmission rates, with the corresponding outcomes for the other hospitals. Results - After fast-track implementation, median LOS in Hospital A diminished from 5 to 2 days (p < 0.001) and (median) LUIC from 6 to 3 (p = 0.001) days. No statistically significant changes occurred in discharge destination. However, the reduction in LOS was combined with an increase in the 42-day readmission rate (3.1% to 8.3%) (p < 0.001). A higher proportion of patients were at home 1 week after THR (p < 0.001) in Hospital A after fast-tracking than before. Interpretation - The fast-track protocol reduces LUIC but needs careful implementation to maintain good quality of care throughout the treatment process.

Fast-tracking for total knee replacement reduces use of institutional care without compromising quality.

Background and purpose - Fast-tracking shortens the length of the primary treatment period (length of stay, LOS) after total knee replacement (TKR). We evaluated the influence of the fast-track concept on the length of uninterrupted institutional care (LUIC) and other outcomes after TKR. Patients and methods - 4,256 TKRs performed in 4 hospitals between 2009-2010 and 2012-2013 were identified from the Finnish Hospital Discharge Register and the Finnish Arthroplasty Register. Hospitals were classified as fast track (Hospital A) and non-fast track (Hospitals B, C and D). We analyzed length of uninterrupted institutional care (LUIC), LOS, discharge destination, readmission, revision, manipulation under anesthesia (MUA) and mortality rate in each hospital. We compared these outcomes for TKRs performed in Hospital A before and after fast-track implementation and we also compared Hospital A outcomes with the corresponding outcomes for the other 3 hospitals. Results - After fast-track implementation, median LOS in Hospital A fell from 5 to 3 days (p < 0.001) and (median) LUIC from 7 to 3 (p < 0.001) days. These reductions in LOS and LUIC were accompanied by an increase in the discharge rate to home (p = 0.01). Fast-tracking in Hospital A led to no increase in 14- and 42-day readmissions, MUA, revision or mortality compared with the rates before fast-tracking, or with those in the other hospitals. Of the 4 hospitals, LOS and LUIC were most reduced in Hospital A. Interpretation - A fast-track protocol reduces LUIC and LOS after TKR without increasing readmission, complication or revision rates.

Translation and validation of the 12-item Oxford knee score for use in Finland.

BACKGROUND: The focus in the reporting of results after total knee replacement (TKR) has changed from surgeon/radiologist-based scores to patient-reported outcome measures (PROMs). The questionnaires used in subjective outcome are often originally published in English and need to be validated in different languages. The aim of our study was to investigate the feasibility, validity, reliability, and responsiveness of the Finnish language version of the Oxford Knee Score (OKS-S) questionnaire. METHODS: The original OKS questionnaire was translated using a forward/backward protocol. The OKS-S questionnaire was sent to 225 patients who were scheduled to undergo TKR surgery. The assessment was repeated 1 year after the index operation. Half of the patients also received the RAND-36 questionnaire with the OKS-S questionnaire and the other half the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire. 30 patients twice received the OKS-S questionnaire preoperatively for the test-retest assessment. RESULTS: Feasibility was acceptable with a response rate of 96% in both pre- and postoperative assessments. Correlation between OKS-S questionnaire and all domains of the KOOS questionnaire and the physical domains in the RAND-36 questionnaire was high, and confirmed both good criterion and convergent validity. Content validity was good since no ceiling or floor effect was observed. In the test-retest assessment, all but 2 patients were within the 95% limits of agreement. Responsiveness was large according to effect sizes. CONCLUSIONS: Our data suggests that the OKS-S questionnaire is suitable for the assessment of both the preoperative status and the outcome of TKR in Finnish speaking patients.

Survival of uncemented cups from a single manufacturer implanted from 1985 to 2013: Finnish Arthroplasty Register data.

INTRODUCTION: Total hip arthroplasty (THA) with uncemented implants has been a relatively common procedure in Finland during the recent decades. The most common brand of uncemented implants was chosen for further analysis to study the survivorship of this uncemented cup design in comparison to cemented references. PATIENTS, MATERIALS AND METHODS: Since 1980, The Finnish Arthroplasty Register has collected information on THAs on a national level. This study was based on information of THAs recorded in the Finnish Arthroplasty Register from 1985 to 2013. If patient had undergone bilateral THA, only the first one was included. Altogether, 49,289 THAs were included. RESULTS: The overall 10-year implant survivorship of uncemented implants was 84.3% (95% CI 83.5-85.0%) and of cemented implants 90.6% (90.2-90.0%). The 10-year survival of the contemporary uncemented implants was 90.8% (94.0-95.5%) and 88.5% (84.2-91.7%). The most recently introduced uncemented cup designs had good survivorship rates at 5 years; 10-year survival data are not yet available. CONCLUSIONS: We found that modern uncemented cup designs may provide good long-term survivorship rates comparable with the gold standard of cemented cups. However, polyethylene wear, liner problems and periosthetic osteolysis may still occur, also with modern uncemented acetabular components.

Early aseptic loosening of cementless monoblock acetabular components.

PURPOSE: Early aseptic loosening of cementless monoblock acetabular components is a rare complication of total hip arthroplasty (THA) and hip resurfacing arthroplasty (HRA). The purpose of this study was to evaluate the incidence and risk factors for early aseptic loosening of the cementless monoblock acetabular components. METHODS: This retrospective analysis consisted of 4,043 cementless hip devices (3,209 THAs and 834 HRAs). We identified 41 patients with early aseptic loosening of the acetabular component. A control group of 123 patients without acetabular component loosening was randomly selected. The demographic data and risk factors for loosening of the acetabular component were evaluated. The mean follow-up time was 4.6 years (range, 1.7-7.8). The end-point was acetabular revision. RESULTS: The incidence of early acetabular component loosening was 1.0 %. Mean time to revision was 1.2 years (SD 1.6, range 0.0-5.4). There was significantly more Dorr type A and C acetabular morphology in patients with early loosening (P = 0.014). The loosened components were implanted to more vertical (P < 0.001) and less anteverted (P = 0.001) position than those of the control group. Presence of acetabular dysplasia or acetabular component type did not associate to early loosening. CONCLUSIONS: Acetabular morphology (Dorr type A and C) and component positioning vertically and less anteverted were more common in patients with early aseptic loosening of cementless acetabular components. Suboptimal cup position most likely reflects challenges to obtain sufficient stability during surgery. We hypothesize that errors in surgical technique are the main reason for early loosening of monoblock acetabular components.

Poor 10-year survivorship of hip resurfacing arthroplasty.

Background and purpose - In a previous registry report, short-term implant survival of hip resurfacing arthroplasty (HRA) in Finland was found to be comparable to that of total hip arthroplasty (THA). Since then, it has become evident that adverse reactions to metal debris (ARMDs) may also be associated with HRA, not only with large-diameter head metal-on-metal THA. The aim of the study was to assess medium- to long-term survivorship of HRA based on the Finnish Arthroplasty Register (FAR). Patients and methods - 5,068 HRAs performed during the period 2001-2013 in Finland were included. Kaplan-Meier survival analysis was used to calculate survival probabilities and their 95% confidence intervals (CIs). Cox multiple regression, with adjustment for age, sex, diagnosis, femoral head size, and hospital volume was used to analyze implant survival of HRA devices with revision for any reason as endpoint. The reference group consisted of 6,485 uncemented Vision/Bimetric and ABG II THAs performed in Finland over the same time period. Results - The 8-year survival, with any revision as an endpoint, was 93% (CI: 92-94) for Birmingham Hip Resurfacing (BHR), 86% (CI: 78-94) for Corin, 91% (CI: 89-94) for ReCap, 92% (CI: 89-96) for Durom, and was 72% (CI: 69-76) for the Articular Surface Replacement (ASR). The 10-year survival, with any revision as an endpoint, for reference THAs was 92% (CI: 91-92) and for all HRAs it was 86% (CI: 84-87%). Female HRA patients had about twice the revision risk of male patients. ASR had an inferior outcome: the revision risk was 4-fold higher than for BHR, the reference implant. Interpretation - The 10-year implant survival of HRAs is 86% in Finland. According to new recommendations from NICE (The National Institute for Health and Care Excellence), an HRA/THA should have a revision rate of 5% or less at 10 years. None of the HRAs studied achieved this goal.

Patient injuries in primary total hip replacement.

Background and purpose - Although the results of primary total hip replacements (THRs) are generally excellent, sometimes serious complications arise. Some of these severe complications are considered to be patient injuries. We analyzed primary THR-related patient injuries in a nationwide setting. Patients and methods - We evaluated all the primary THR-related patient injury claims in Finland between 2008 and 2010. We used the original medical records and 2 nationwide registries, the Care Register for Social Welfare and Health Care and the Patient Injury Claim Register. Results - We identified 563 claims, 44% of which were compensated (n = 250). Of these 250 compensated claims, 79% were considered to be avoidable (treatment injuries) and 21% were severe unexpected infections (with a preoperative infection risk of less than 2%). The most common type of technical error was cup malposition (31%). High-volume hospitals (with an annual primary THR volume ≥ 400) had a lower patient injury rate. In lower-volume hospitals (with an annual primary THR volume of < 400), the relative risks (RRs) of patient injury for any reason, due to technical errors, or because of cup malposition were 2-fold (95% CI: 1.6-3.1), 4-fold (95% CI: 2.3-6.2), and 9-fold (95% CI: 3-28), respectively, compared to high-volume hospitals. Interpretation - Our study provides the first comprehensive nationwide data on THR-related patient injury types. Hospital volume was associated with the quality and quantity of errors detected. An annual hospital volume of ≥ 400 primary THRs was established as a protective factor against patient injuries.

Risk factors for intraoperative calcar fracture in cementless total hip arthroplasty.

BACKGROUND AND PURPOSE: Intraoperative periprosthetic femoral fracture is a known complication of cementless total hip arthroplasty (THA). We determined the incidence of--and risk factors for--intraoperative calcar fracture, and assessed its influence on the risk of revision. PATIENTS AND METHODS: This retrospective analysis included 3,207 cementless THAs (in 2,913 patients). 118 intraoperative calcar fractures were observed in these hips (3.7%). A control group of 118 patients/hips without calcar fractures was randomly selected. The mean follow-up was 4.2 (1.8-8.0) years. Demographic data, surgical data, type of implant, and proximal femur morphology were evaluated to determine risk factors for intraoperative calcar fracture. RESULTS: The revision rates in the calcar fracture group and the control group were 10% (95% CI: 5.9-17) and 3.4% (CI: 1.3-8.4), respectively. The revision rate directly related to intraoperative calcar fracture was 7.6%. The Hardinge approach and lower age were risk factors for calcar fracture. In the fracture group, 55 of 118 patients (47%) had at least one risk factor, while only 23 of118 patients in the control group (20%) had a risk factor (p = 0.001). Radiological analysis showed that in the calcar fracture group, there were more deviated femoral anatomies and proximal femur bone cortices were thinner. INTERPRETATION: Intraoperative calcar fracture increased the risk of revision. The Hardinge approach and lower age were risk factors for intraoperative calcar fracture. To avoid intraoperative fractures, special attention should be paid when cementless stems are used with deviant-shaped proximal femurs and with thin cortices.

Hospital volume affects outcome after total knee arthroplasty.

BACKGROUND AND PURPOSE: The influence of hospital volume on the outcome of total knee joint replacement surgery is controversial. We evaluated nationwide data on the effect of hospital volume on length of stay, re-admission, revision, manipulation under anesthesia (MUA), and discharge disposition for total knee replacement (TKR) in Finland. PATIENTS AND METHODS: 59,696 TKRs for primary osteoarthritis performed between 1998 and 2010 were identified from the Finnish Hospital Discharge Register and the Finnish Arthroplasty Register. Hospitals were classified into 4 groups according to the number of primary and revision knee arthroplasties performed on an annual basis throughout the study period: 1-99 (group 1), 100-249 (group 2), 250-449 (group 3), and ≥ 450 (group 4). The association between hospital procedure volume and length of stay (LOS), length of uninterrupted institutional care (LUIC), re-admissions, revisions, MUA, and discharge disposition were analyzed. RESULTS: The greater the volume of the hospital, the shorter was the average LOS and LUIC. Smaller hospital volume was not unambiguously associated with increased revision, re-admission, or MUA rates. The smaller the annual hospital volume, the more often patients were discharged home. INTERPRETATION: LOS and LUIC ought to be shortened in lower-volume hospitals. There is potential for a reduction in length of stay in extended institutional care facilities.

Surgical treatment of chronic acromioclavicular joint dislocation with autogenous tendon grafts.

BACKGROUND: Conservative treatment of acromioclavicular (AC) joint dislocation is not always successful. A consequence of persistent AC joint dislocation may be chronic pain and discomfort in the shoulder region as well a sensation of constant AC joint instability and impaired shoulder function. Stabilization of the AC joint may reduce these sequels. MATERIALS AND METHODS: Due to chronic AC joint dislocation, 39 patients in our hospital underwent coracoclavicular (CC) ligament reconstruction with autogenous semitendinosus and gracilis tendons between May 2005 and April 2011. We examined 25 patients after a mean of 4.2 years. The outcomes were Constant shoulder Score (CS), Disabilities of the Arm, Shoulder and Hand (DASH), pain (Visual Analog Scale, VAS), cross-arm test, stability of the AC joint, and complications. The follow-up visits included anteroposterior and axillary radiographs. RESULTS: Mean CS was 83 in the injured shoulder and 91 in the uninjured shoulder (p = 0.002). Mean DASH was 14. In 14 patients, the AC joint was clinically stable; pain was minor. In radiographs, osteolysis of the lateral clavicle and tunnel widening were markedly common. Fracture of the coracoid process occurred in 5 patients, and 3 suffered a fracture of the clavicle; 2 had a postoperative infection. CONCLUSIONS: Anatomic reconstruction of CC ligaments showed a moderate subjective outcome at the 4-year follow-up. After surgery, almost half the AC joints failed to stabilize. Lateral clavicle osteolysis and tunnel widening were notably common complications.

Efficacy of a novel PCR- and microarray-based method in diagnosis of a prosthetic joint infection.

BACKGROUND AND PURPOSE: Polymerase chain reaction (PCR) methods enable detection and species identification of many pathogens. We assessed the efficacy of a new PCR and microarray-based platform for detection of bacteria in prosthetic joint infections (PJIs). METHODS: This prospective study involved 61 suspected PJIs in hip and knee prostheses and 20 negative controls. 142 samples were analyzed by Prove-it Bone and Joint assay. The laboratory staff conducting the Prove-it analysis were not aware of the results of microbiological culture and clinical findings. The results of the analysis were compared with diagnosis of PJIs defined according to the Musculoskeletal Infection Society (MSIS) criteria and with the results of microbiological culture. RESULTS: 38 of 61 suspected PJIs met the definition of PJI according to the MSIS criteria. Of the 38 patients, the PCR detected bacteria in 31 whereas bacterial culture was positive in 28 patients. 15 of the PJI patients were undergoing antimicrobial treatment as the samples for analysis were obtained. When antimicrobial treatment had lasted 4 days or more, PCR detected bacteria in 6 of the 9 patients, but positive cultures were noted in only 2 of the 9 patients. All PCR results for the controls were negative. Of the 61 suspected PJIs, there were false-positive PCR results in 6 cases. INTERPRETATION: The Prove-it assay was helpful in PJI diagnostics during ongoing antimicrobial treatment. Without preceding treatment with antimicrobials, PCR and microarray-based assay did not appear to give any additional information over culture.

Cancer incidence and cause-specific mortality in patients with metal-on-metal hip replacements in Finland.

BACKGROUND AND PURPOSE: Metal-on-metal hip implants have been widely used, especially in the USA, Australia, England and Wales, and Finland. We assessed risk of death and updated data on the risk of cancer related to metal-on-metal hip replacements. PATIENTS AND METHODS: A cohort of 10,728 metal-on-metal hip replacement patients and a reference cohort of 18,235 conventional total hip replacement patients were extracted from the Finnish Arthroplasty Register for the years 2001-2010. Data on incident cancer cases and causes of death until 2011 were obtained from the Finnish Cancer Registry and Statistics Finland. The relative risk of cancer and death were expressed as standardized incidence ratio (SIR) and standardized mortality ratio (SMR). SIR/SIR ratios and SMR/SMR ratios, and Poisson regression were used to compare the cancer risk and the risk of death between cohorts. RESULTS: The overall risk of cancer in the metal-on-metal cohort was not higher than that in the non-metal-on-metal cohort (RR = 0.91, 95% CI: 0.82-1.02). The risk of soft-tissue sarcoma and basalioma in the metal-on-metal cohort was higher than in the non-metal-on-metal cohort (SIR/SIR ratio = 2.6, CI: 1.02-6.4 for soft-tissue sarcoma; SIR/SIR ratio = 1.3, CI: 1.1-1.5 for basalioma). The overall risk of death in the metal-on-metal cohort was less than that in the non-metal-on-metal cohort (RR = 0.78, CI: 0.69-0.88). INTERPRETATION: The overall risk of cancer or risk of death because of cancer is not increased after metal-on-metal hip replacement. The well-patient effect and selection bias contribute substantially to the findings concerning mortality. Arthrocobaltism does not increase mortality in patients with metal-on-metal hip implants in the short term. However, metal-on-metal hip implants should not be considered safe until data with longer follow-up time are available.

Total knee arthroplasty with an uncemented trabecular metal tibial component: a registry-based analysis.

Previous poor results have kept the appeal of uncemented total knee arthroplasties (TKAs) minimal. We analyzed the mid-term survivorship and reasons for failures of a contemporary uncemented porous tantalum monoblock tibial component nation-wide. During the study period (2003-2010), such tibial components were used in 1143 primary TKAs recorded in the Finnish Arthroplasty Registry. Seven-year survivorship of these TKAs was 100% (95% CI 99-100) with revision for aseptic loosening of the tibial component, and 97% (95% CI 96-98) with revision for any reason as the respective end points. The most common reasons for revisions were instability and prosthetic joint infections. In conclusion, TKAs using an uncemented porous tantalum monoblock tibial component showed excellent mid-term survivorship in a population-based setting.