Antti Eskelinen

Obesity, diabetes, and preoperative hyperglycemia as predictors of periprosthetic joint infection: a single-center analysis of 7181 primary hip and knee replacements for osteoarthritis.

BACKGROUND Diabetes and obesity are common in patients undergoing joint replacement. Studies analyzing the effects of diabetes and obesity on the occurrence of periprosthetic joint infection have yielded contradictory results, and the combined effects of these conditions are not known. METHODS The one-year incidence of periprosthetic joint infections was analyzed in a single-center series of 7181 primary hip and knee replacements (unilateral and simultaneous bilateral) performed between 2002 and 2008 to treat osteoarthritis. The data regarding periprosthetic joint infection (defined according to Centers for Disease Control and Prevention criteria) were collected from the hospital infection register and were based on prospective, active surveillance. Patients diagnosed with diabetes were identified from the registers of the Social Insurance Institution of Finland. The odds ratios (ORs) for infection and the accompanying 95% confidence intervals (CIs) were calculated with use of binary logistic regression with adjustment for age, sex, American Society of Anesthesiologists risk score, arthroplasty site, body mass index, and diabetic status. RESULTS Fifty-two periprosthetic joint infections occurred during the first postoperative year (0.72%; 95% CI, 0.55% to 0.95%). The infection rate increased from 0.37% (95% CI, 0.15% to 0.96%) in patients with a normal body mass index to 4.66% (95% CI, 2.47% to 8.62%) in the morbidly obese group (adjusted OR, 6.4; 95% CI, 1.7 to 24.6). Diabetes more than doubled the periprosthetic joint infection risk independent of obesity (adjusted OR, 2.3; 95% CI, 1.1 to 4.7). The infection rate was highest in morbidly obese patients with diabetes; this group contained fifty-one patients and periprosthetic infection developed in five (9.8%; 95% CI, 4.26% to 20.98%). In patients without a diagnosis of diabetes at the time of the surgery, there was a trend toward a higher infection rate in association with a preoperative glucose level of ≥6.9 mmol/L (124 mg/dL) compared with <6.9 mmol/L. The infection rate was 1.15% (95% CI, 0.56% to 2.35%) in the former group compared with 0.28% (95% CI, 0.15% to 0.53%) in the latter, and the adjusted OR was 3.3 (95% CI, 0.96 to 11.0). The type of diabetes medication was not associated with the infection rate. CONCLUSIONS Diabetes and morbid obesity increased the risk of periprosthetic joint infection following primary hip and knee replacement. The benefits of joint replacement should be carefully weighed against the incidence of postoperative infection, especially in morbidly obese patients. LEVEL OF EVIDENCE Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Uncemented total hip arthroplasty for primary osteoarthritis in young patients: a mid-to long-term follow-up study from the Finnish Arthroplasty Register.

Introduction The survival of total hip arthroplasties (THAs) has been considered to be poor in young patients. We evaluated the population-based survival of uncemented THA for primary osteoarthritis (OA) in patients under 55 years of age and the factors affecting survival. Methods The Finnish Arthroplasty Register was established in 1980. Between that year and 2003, 92,083 primary THAs were entered in the register, 5,607 of which were performed for primary OA in patients under 55 years of age. Using records from these 5,607 THAs, we selected uncemented femoral and acetabular components that had been used in more than 100 operations during the study period. Survival of both components (cup/stem) and their combinations were analyzed separately with the Kaplan-Meier analysis and the Cox regression model. Results All uncemented stems studied showed a survival rate of over 90% at 10 years. The Biomet Bi-Metric stem had a 95% (95% CI 93– 97) survival rate even at 15 years. Overall survival of the extendedly porous-coated Lord Madréporique stem (p = 0.003) and the proximally porous-coated Anatomic Mesh stem (p = 0.0008) were poorer than that of the Biomet Bi-Metric stem. When endpoint was defined as stem revision for any reason, results were generally similar; there was no difference, however, between the survival rates of the Lord Madréporique stem and the Bi-Metric stem. Of the acetabular components, the Biomet Universal, the ABG Il and the Harris-Galante II cups showed < 90% survival rates at 10 years with aseptic loosening as endpoint; at 13 years the corresponding survival rates were 94% (95% CI 91–97) for the Biomet Universal and 95% (95% CI 91–98) for the Harris-Galante II cups with aseptic loosening as endpoint. The PCA Pegged porous-coated uncemented cup showed a poor 13-year survival rate of 68% (95% CI 59–78) with aseptic loosening as endpoint. However, when endpoint was defined as any revision (including exchange of liner), the 10-year survival rates of all brands of cup except Harris-Galante II declined to under 80%. Interpretation Modern second-generation uncemented stems, with proximal circumferential porous- or HA-coating, seem to be a good choice for young patients with primary OA. Similarly, modern press-fit porous- and HA-coated cups appear to have good endurance against aseptic loosening in these young patients. However, liner revisions were common; thus, survival rates of uncemented cups were unsatisfactorily low. Polyethylene wear and unfavorable locking mechanisms between the metal shell and the polyethylene liner and their sequelae remain matters of concern in this young and active group of patients. ▪

Unicondylar knee replacement for primary osteoarthritis: A prospective follow-up study of 1,819 patients from the Finnish Arthroplasty Register

Background The choice and use of unicondylar knee arthroplasty (UKA) has gone through a nation wide resurgence at the start of the 21st century in Finland. We evaluated the population-based survival of UKA in patients with primary osteoarthritis (OA) in Finland, and the factors affecting their survival. Method The Finnish Arthroplasty Register was established in 1980. During the years 1985–2003, 1,928 primary UKAs were recorded in the register; 1,819 of these were performed for primary OA. Of these 1,819 UKAs, we selected for further analysis implants that had been used in more than 100 operations during the study period. The survival rates of UKAs were analyzed using Kaplan-Meier analysis and the Cox regression model. Results Analysis of the whole study period showed that UKAs had a 73% (95% CI: 70–76) survival rate at 10 years, with revision for any reason as the end point. Those patients who received the Oxford menisceal bearing unicondylar (n = 1145) had a survival rate of 81% (95% CI: 72–89) at 10 years. The group that received the Miller-Galante II unicondylar (n = 330) had a 79% survival rate (95% CI: 71–87) at 10 years, whereas the Duracon (n = 196) had a survival rate of 78% (95% CI: 72–84) and the PCA (n = 146) had a survival rate of 53% (95% CI: 45–60) at 10 years. The number of UKA operations in Finland has increased markedly in recent years. At the time of operation, the mean age of the patients was 65 (38–91) years. Younger patients (≤ 65 years of age) were found to have a 1.5-fold (95% CI: 1.1–2.0; p = 0.04) increased risk of revision compared to older patients (< 65 years). Interpretation UKA is a viable option for the treatment of unicompartmental osteoarthritis of the knee. However, patients should be made aware of the lower survival of the UKAs compared with total knee arthroplasties.

Total hip arthroplasty for primary osteoarthrosis in younger patients in the Finnish arthroplasty register: 4 661 primary replacements followed for 0–22 years

Background Many studies have found a higher risk of revision after hip arthroplasty in younger patients. We evaluated the population-based survival of total hip arthroplasty (THA) in patients under 55 years of age and the factors affecting survival. Methods The Finnish Arthroplasty Register was established in 1980, and 74 492 primary THAs were entered into the register between 1980 and 2001. 4 661 of these were evaluated, all of which had been performed for primary osteoarthrosis on patients under 55 years of age. Results Proximally circumferentially porous-coated uncemented stems implanted between 1991 and 2001 had a 10-year survival rate of 99 (95% CI 98.5–99.6)% with aseptic loosening as endpoint. The risk of stem revision due to aseptic loosening was higher in cemented stems than in proximally porous-coated (RR 5.5, p<0.001) or HA-coated (RR 6.6, p=0.01) uncemented stems implanted during the same period. According to Cox regression analysis of cups implanted 1991–2001, the risk of revision for all-polyethylene cemented cups was 3.0 times as high as that for press-fit porous-coated uncemented cups with aseptic loosening as endpoint (p=0.01). However, when the endpoint was defined as any revision (including exchange of liner), there was no longer any difference between these two concepts, the 10-year survival rates being 94 (92.1–95.5)% for press-fit porous-coated uncemented cups and 93 (88.5–97.6)% for all-polyethylene cemented cups (p=0.9). Interpretation Modern uncemented stems seem to have better resistance to aseptic loosening than cemented stems in younger patients. Thus, for younger patients, uncemented proximally circumferentially porous- and HA-coated stems are the implants of choice. Press-fit porous- and HA-coated uncemented cups may have better endurance against aseptic loosening than cemented cups in younger patients. However, when all revisions (including exchange of liner) are taken into account, the survival of modern uncemented cups is no better than that of all-poly cemented cups.

Total Hip Arthroplasty for Primary Osteoarthritis in Patients Fifty-five Years of Age or Older: An Analysis of the Finnish Arthroplasty Registry

BACKGROUND According to the long-term results obtained from the Scandinavian arthroplasty registries, cemented total hip replacement has been the treatment of choice for osteoarthritis of the hip in elderly patients. The aim of the present study was to analyze population-based survival rates of the cemented and cementless total hip replacements performed for primary osteoarthritis in patients fifty-five years of age or older in Finland. METHODS From 1980 to 2004, a total of 50,968 primary total hip replacements that met our criteria were entered in the Finnish Arthroplasty Registry. The success rate of different implant groups was analyzed. The implants included were classified in one of the following four groups: implants with a cementless, straight, proximally circumferentially porous-coated stem and a modular, porous-coated press-fit cup (cementless group 1); implants with a cementless, anatomic, proximally circumferentially porous-coated and/or hydroxyapatite-coated stem with a modular, porous-coated and/or hydroxyapatite-coated press-fit cup (cementless group 2); a hybrid total hip replacement consisting of a cemented stem combined with a modular, press-fit cup (the hybrid group); and a cemented loaded-taper or composite-beam stem combined with an all-polyethylene cup (the cemented group). RESULTS Cementless total hip replacements, as well as cementless stems and cups analyzed separately, had a significantly reduced risk of revision for aseptic loosening compared with cemented hip replacements (p < 0.001). When revision for any reason was the end point in survival analyses, however, there were no significant differences among the groups. In patients between the ages of fifty-five and sixty-four years, the fifteen-year survival rates of the two cementless groups (78% and 80%) were higher than that of the cemented group (71%) with revision for aseptic loosening as the end point. In patients who were sixty-five to seventy-four years old, the fifteen-year survival rate of the implants in cementless group 1 was 94%, while cemented total hip replacements had an 85% survival rate. In patients who were seventy-five years old or more, no significant differences were detected among the total hip replacement groups; all of them had survivorship of >90% at ten years. CONCLUSIONS In patients who were fifty-five years of age or older, the long-term survival of cementless total hip replacements was comparable with that of cemented replacements. In patients who were fifty-five to seventy-four years old, straight porous-coated cementless stems had better long-term survival than the cemented stems. In patients who were seventy-five years of age and older, there were no significant differences in the results. Multiple wear-related revisions of the cementless cups in the present study indicate that excessive polyethylene wear was a major clinical problem with modular cementless cups in all age groups. LEVEL OF EVIDENCE Therapeutic Level III. See Instructions to Authors for a complete description of levels of evidence.

Comparison of survival and cost-effectiveness between unicondylar arthroplasty and total knee arthroplasty in patients with primary osteoarthritis: a follow-up study of 50,493 knee replacements from the Finnish Arthroplasty Register.

Background and purpose Both unicondylar arthroplasty (UKA) and total knee arthroplasty (TKA) are commonly used for the treatment of unicompartmental osteoarthritis (OA) of the knee. The long‐term survivorship and cost‐effectiveness of these two treatments have seldom been compared on a nationwide level, however. We therefore compared the survival of UKA with that of TKA and conducted a cost‐benefit analysis comparing UKA with TKA in patients with primary OA. Patients and methods We analyzed 1,886 primary UKAs (3 designs) and 48,607 primary TKAs that had been performed for primary OA and entered in the Finnish Arthroplasty Register between 1980 and 2003 inclusive. Results UKAs had a 60% (95% CI: 54–66) survival rate and TKAs an 80% (95% CI: 79–81) survival rate at 15 years with any revision taken as the endpoint. Overall survival of UKAs was worse than that of TKAs (p < 0.001). All 3 UKA designs had poorer overall survival than the corresponding TKA designs. In the theoretical cost‐benefit analysis, the cost saved by lower implant prices and shorter hospital stay with UKA did not cover the costs of the extra revisions. Interpretation At a nationwide level, UKA had significantly poorer long‐term survival than TKA. What is more, UKA did not even have a theoretical cost benefit over TKA in our study. Based on these results, we cannot recommend widespread use of UKA in treatment of unicompartmental OA of the knee.

Increasing risk of prosthetic joint infection after total hip arthroplasty

Background and purpose The risk of revision due to infection after primary total hip arthroplasty (THA) has been reported to be increasing in Norway. We investigated whether this increase is a common feature in the Nordic countries (Denmark, Finland, Norway, and Sweden). Materials and methods The study was based on the Nordic Arthroplasty Register Association (NARA) dataset. 432,168 primary THAs from 1995 to 2009 were included (Denmark: 83,853, Finland 78,106, Norway 88,455, and Sweden 181,754). Adjusted survival analyses were performed using Cox regression models with revision due to infection as the endpoint. The effect of risk factors such as the year of surgery, age, sex, diagnosis, type of prosthesis, and fixation were assessed. Results 2,778 (0.6%) of the primary THAs were revised due to infection. Compared to the period 1995–1999, the relative risk (with 95% CI) of revision due to infection was 1.1 (1.0–1.2) in 2000–2004 and 1.6 (1.4–1.7) in 2005–2009. Adjusted cumulative 5–year revision rates due to infection were 0.46% (0.42–0.50) in 1995–1999, 0.54% (0.50–0.58) in 2000–2004, and 0.71% (0.66–0.76) in 2005–2009. The entire increase in risk of revision due to infection was within 1 year of primary surgery, and most notably in the first 3 months. The risk of revision due to infection increased in all 4 countries. Risk factors for revision due to infection were male sex, hybrid fixation, cement without antibiotics, and THA performed due to inflammatory disease, hip fracture, or femoral head necrosis. None of these risk factors increased in incidence during the study period. Interpretation We found increased relative risk of revision and increased cumulative 5–year revision rates due to infection after primary THA during the period 1995–2009. No change in risk factors in the NARA dataset could explain this increase. We believe that there has been an actual increase in the incidence of prosthetic joint infections after THA.

Cementless Total Hip Arthroplasty in Patients with High Congenital Hip Dislocation

BACKGROUND The optimal surgical treatment for patients with high congenital dislocation of the hip remains controversial. The purpose of our study was to evaluate the mid-term to long-term results of cementless total hip arthroplasty in such patients. METHODS The study included sixty-eight total hip replacements performed between 1989 and 1994 in fifty-six consecutive patients with high congenital hip dislocation at our hospital. The cup was placed at the level of the true acetabulum, and a shortening osteotomy of the proximal part of the femur and distal advancement of the greater trochanter were performed in 90% of the hips. At the time of final follow-up, at a mean of 12.3 years postoperatively, fifty-two patients (sixty-four hips) were evaluated by us with a physical examination, determination of Harris hip scores, and radiographs. RESULTS The mean Harris hip score increased from 54 points preoperatively to 84 points at the time of final follow-up (p < 0.001). There was a negative Trendelenburg sign in fifty-nine (92%) of the sixty-four hips. There were thirteen perioperative complications (19%): three peroneal nerve palsies, one femoral nerve palsy, one superior gluteal nerve palsy, four nondisplaced fractures of the proximal part of the femur, one malpositioned stem perforating the posteromedial cortex of the femur, one superficial wound infection, and two early dislocations. With revision because of aseptic loosening as the end point, the ten-year survival rate for press-fit, porous-coated acetabular components was 94.9% (95% confidence interval, 89.3% to 100%). Eight of nine threaded acetabular components were revised, and the ninth was radiographically loose at the time of the last follow-up examination. The rate of survival for the CDH femoral components, with revision because of aseptic loosening as the end point, was 98.4% (95% confidence interval, 96.8% to 100%) at ten years. CONCLUSIONS Total hip arthroplasty, with placement of the cup at the level of the true acetabulum, distal advancement of the greater trochanter, and femoral shortening osteotomy, can be recommended for patients with high congenital hip dislocation. Complications such as wear, osteolysis, and cup revision were secondary to the suboptimal design of the acetabular components used in this series.

Total ankle replacement: a population-based study of 515 cases from the Finnish Arthroplasty Register.

Background and purpose Although total ankle replacement (TAR) is a recognized procedure for treatment of the painful arthritic ankle, the best choice of implant and the long-term results are still unknown. We evaluated the survival of two TAR designs and factors associated with survival using data from the nationwide arthroplasty registry in Finland. Methods 573 primary TARs were performed during the period 1982–2006 because of rheumatic, arthritic, or posttraumatic ankle degeneration. We selected contemporary TAR designs that were each used in more than 40 operations, including the S.T.A.R. (n = 217) and AES (n = 298), to assess their respective survival rates. The mean age of the patients was 55 (17–86) years and 63% of operations were performed in women. Kaplan-Meier analysis and the Cox regression model were used for survival analysis. The effects of age, sex, diagnosis, and hospital volume were also studied. Results The annual incidence of TAR was 1.5 per 105 inhabitants. The 5-year overall survivorship for the whole TAR cohort was 83% (95% CI: 81–86), which agrees with earlier reports. The most frequent reasons for revision were aseptic loosening of one or both of the prosthesis components (39%) and instability (39%). We found no difference in survival rate between the S.T.A.R. and AES designs. Furthermore, age, sex, diagnosis, and hospital volume (< 10 and > 100 replacements in each of 17 hospitals) did not affect the TAR survival. Interpretation Based on our findings, we cannot conclude that any prosthesis was superior to any other. A high number of technical errors in primary TARs suggests that this low-volume field of implant arthroplasty should be centralized to fewer units.

Failure rate of cemented and uncemented total hip replacements: register study of combined Nordic database of four nations

Objective To assess the failure rate of cemented, uncemented, hybrid, and reverse hybrid total hip replacements in patients aged 55 years or older. Design Register study. Setting Nordic Arthroplasty Register Association database (combined data from Sweden, Norway, Denmark, and Finland). Participants 347 899 total hip replacements performed during 1995-2011. Main outcome measures Probability of implant survival (Kaplan-Meier analysis) along with implant survival with revision for any reason as endpoint (Cox multiple regression) adjusted for age, sex, and diagnosis in age groups 55-64, 65-74, and 75 years or older. Results The proportion of total hip replacements using uncemented implants increased rapidly towards the end of the study period. The 10 year survival of cemented implants in patients aged 65 to 74 and 75 or older (93.8%, 95% confidence interval 93.6% to 94.0% and 95.9%, 95.8% to 96.1%, respectively) was higher than that of uncemented (92.9%, 92.3% to 93.4% and 93.0%, 91.8% to 94.0%), hybrid (91.6%, 90.9% to 92.2% and 93.9%, 93.1% to 94.5%), and reverse hybrid (90.7%, 87.3% to 93.2% and 93.2%, 90.7% to 95.1%) implants. The survival of cemented (92.2%, 91.8% to 92.5%) and uncemented (91.8%, 91.3% to 92.2%) implants in patients aged 55 to 64 was similar. During the first six months the risk of revision with cemented implants was lower than with all other types of fixation in all age groups. Conclusion The survival of cemented implants for total hip replacement was higher than that of uncemented implants in patients aged 65 years or older. The increased use of uncemented implants in this age group is not supported by these data. However, because our dataset includes only basic information common to all national registers there is potential for residual confounding.