Rüdiger J. Weiss

Orthopaedic surgery of the lower limbs in 49,802 rheumatoid arthritis patients : results from the Swedish National Inpatient Registry during 1987 to 2001

Objectives: To analyse changes in the rates of hospital admission and use of orthopaedic surgery to the lower limbs in Swedish patients with rheumatoid arthritis between 1987 and 2001. Methods: Data for all rheumatoid patients admitted to hospital between 1987 and 2001 were abstracted from the Swedish National Hospital Discharge Register (SNHDR). The data in the register are collected prospectively, recording all inpatient admissions throughout Sweden. The SNHDR uses the codes for diagnoses at discharge and surgical procedures according to the Swedish version of the International Classification of Diseases (ICD). Results: In all, 49 802 individual patients with rheumatoid arthritis were identified, accounting for 159 888 inpatient visits. Hospital admissions for rheumatoid arthritis decreased by 42% (p<0.001) during the period 1987 to 2001. Twelve per cent of all admissions were for a rheumatoid arthritis related surgical procedure to the lower limbs; those admissions decreased markedly (by 16%) between 1987 and 1996, and by 12% between 1997 and 2001, as did the overall number of rheumatoid arthritis related surgical procedures to the lower limbs during both time periods. Between 1997 and 2001, 47% of all rheumatoid arthritis related surgical procedures were total joint arthroplasties. There was an overall trend towards reduced length of hospital stay after orthopaedic surgery to the lower limbs during the study period. Conclusions: Rates of hospital admission and rheumatoid arthritis related surgical procedures to the lower limbs in Swedish patients with rheumatoid arthritis decreased between 1987 and 2001. This may reflect trends in disease severity, management, and health outcomes of this disease in Sweden.

The risk of revision due to dislocation after total hip arthroplasty depends on surgical approach, femoral head size, sex, and primary diagnosis: An analysis of 78,098 operations in the Swedish Hip Arthroplasty Register

Background and purpose The effects of patient-related and technical factors on the risk of revision due to dislocation after primary total hip arthroplasty (THA) are only partly understood. We hypothesized that increasing the femoral head size can reduce this risk, that the lateral surgical approach is associated with a lower risk than the posterior and minimally invasive approaches, and that gender and diagnosis influence the risk of revision due to dislocation. Patients and methods Data on 78,098 THAs in 61,743 patients performed between 2005 and 2010 were extracted from the Swedish Hip Arthroplasty Register. Inclusion criteria were a head size of 22, 28, 32, or 36 mm, or the use of a dual-mobility cup. The covariates age, sex, primary diagnosis, type of surgical approach, and head size were entered into Cox proportional hazards models in order to calculate the adjusted relative risk (RR) of revision due to dislocation, with 95% confidence intervals (CI). Results After a mean follow-up of 2.7 (0–6) years, 399 hips (0.5%) had been revised due to dislocation. The use of 22-mm femoral heads resulted in a higher risk of revision than the use of 28-mm heads (RR = 2.0, CI: 1.2–3.3). Only 1 of 287 dual-mobility cups had been revised due to dislocation. Compared with the direct lateral approach, minimally invasive approaches were associated with a higher risk of revision due to dislocation (RR = 4.2, CI: 2.3–7.7), as were posterior approaches (RR = 1.3, CI: 1.1–1.7). An increased risk of revision due to dislocation was found for the diagnoses femoral neck fracture (RR = 3.9, CI: 3.1–5.0) and osteonecrosis of the femoral head (RR = 3.7, CI: 2.5–5.5), whereas women were at lower risk than men (RR = 0.8, CI: 0.7–1.0). Restriction of the analysis to the first 6 months after the index procedure gave similar risk estimates. Interpretation Patients with femoral neck fracture or osteonecrosis of the femoral head are at higher risk of dislocation. Use of the minimally invasive and posterior approaches also increases this risk, and we raise the question of whether patients belonging to risk groups should be operated using lateral approaches. The use of femoral head diameters above 28 mm or of dual-mobility cups reduced this risk in a clinically relevant manner, but this observation was not statistically significant.

Increased Fracture Risk in Patients with Rheumatic Disorders and Other Inflammatory Diseases — A Case-Control Study with 53,108 Patients with Fracture

Objective. To identify the risk of hip and vertebral fractures in patients with rheumatic disorders (RD) and inflammatory bowel diseases (IBD). Methods. This population-based case-control study assessed the fracture risk of patients with rheumatoid arthritis, juvenile idiopathic arthritis (JIA), ankylosing spondylitis (AS), systemic lupus erythematosus, polymyositis/dermatomyositis (PM/DM), systemic sclerosis (SSc), Crohn’s disease, and ulcerative colitis (UC). The study cohort comprised 53,108 patients with fracture (66% women) and 370,602 age-matched and sex-matched controls. Conditional logistic regression analysis was performed and results were expressed as OR with corresponding 95% CI. Results. There was a statistically significant increased fracture risk for all RD and for IBD compared with controls. The magnitude of fracture risk was higher for patients with RD (OR 3, 95% CI 2.9–3.2) than for those with IBD (OR 1.6, 1.4–1.8). The OR in RD ranged from 2.6 (1.3–4.9) for SSc to 4 (3.4–4.6) for AS. The largest increased fracture risk for vertebral fractures was seen in AS (OR 7.1, 6–8.4) and for hip fractures in JIA (OR 4.1, 2.4–6.9). Conclusion. Our results highlight the existence of an increased fracture risk from a variety of underlying causes in patients with RD and IBD. In many inflammatory diseases, implementation of fracture prevention strategies may be beneficial.

Decrease of RA-related orthopaedic surgery of the upper limbs between 1998 and 2004: data from 54 579 Swedish RA inpatients

OBJECTIVES To describe the overall use and temporal trends in orthopaedic upper limb surgery associated with RA on a nation wide basis in Sweden between 1998 and 2004. METHODS Data for all inpatient visits during 1998-2004 for patients older than 18 yrs with RA-related diagnoses were extracted from the Swedish National Hospital Discharge Registry (SNHDR). The SNHDR prospectively collects data on all hospital admissions in Sweden according to the International Classification of Diseases (ICD). Data were analysed with respect to orthopaedic surgery of the hand, elbow and shoulder. RESULTS During the study period, 54,579 individual RA patients were admitted to a Swedish hospital and 9% of these underwent RA-related surgery of the upper limbs. The RA patient cohort underwent a total of 8251 RA-related upper limb surgical procedures. The hand (77%) was most frequently operated on, followed by the shoulder (13%) and the elbow (10%). There was a statistically significant decrease of 31% for all admissions associated with RA-related upper limb surgery during 1998-2004 (P = 0.001). Some 10% of all RA-related upper limb surgery was due to total joint arthroplasties (TJAs), mostly for the elbow (59%). During 1998-2004, all TJAs, elbow-TJAs and shoulder-TJAs had a stable occurrence. In contrast, the overall numbers of hand-TJAs significantly increased (P = 0.009). CONCLUSIONS Rates of RA-related upper limb surgery decreased and TJAs had a stable occurrence in Sweden during 1998-2004. The findings of this study may reflect trends in disease management and health outcomes of RA patients in Sweden.

Dual-mobility cups for revision due to instability are associated with a low rate of re-revisions due to dislocation 228 patients from the Swedish Hip Arthroplasty Register

Background and purpose Revision total hip arthroplasty (THA) due to recurrent dislocations is associated with a high risk of persistent instability. We hypothesized that the use of dual-mobility cups would reduce the risk of re-revision due to dislocation after revision THA. Patients and methods 228 THA cup revisions (in 228 patients) performed due to recurrent dislocations and employing a specific dual-mobility cup (Avantage) were identified in the Swedish Hip Arthroplasty Register. Kaplan-Meier survival analysis was performed with re-revision due to dislocation as the primary endpoint and re-revision for any reason as the secondary endpoint. Cox regression models were fitted in order to calculate the influence of various covariates on the risk of re-revision. Results 58 patients (25%) had been revised at least once prior to the index cup revision. The surgical approach at the index cup revision was lateral in 99 cases (44%) and posterior in 124 cases (56%). Median follow-up was 2 (0–6) years after the index cup revision, and by then 18 patients (8%) had been re-revised for any reason. Of these, 4 patients (2%) had been re-revised due to dislocation. Survival after 2 years with the endpoint revision of any component due to dislocation was 99% (95% CI: 97–100), and it was 93% (CI: 90–97) with the endpoint revision of any component for any reason. Risk factors for subsequent re-revision for any reason were age between 50–59 years at the time of the index cup revision (risk ratio (RR) = 5 when compared with age > 75, CI: 1–23) and previous revision surgery to the relevant joint (RR = 1.7 per previous revision, CI: 1–3). Interpretation The risk of re-revision due to dislocation after insertion of dual-mobility cups during revision THA performed for recurrent dislocations appears to be low in the short term. Since most dislocations occur early after revision THA, we believe that this device adequately addresses the problem of recurrent instability. Younger age and prior hip revision surgery are risk factors for further revision surgery. However, problems such as potentially increased liner wear and subsequent aseptic loosening may be associated with the use of such devices in the long term.

Minimum 5-Year Follow-Up of a Cementless, Modular, Tapered Stem in Hip Revision Arthroplasty

Hip revision surgery with a cementless tapered femoral component can provide axial and rotational stability in patients with compromised proximal bone stock. This study includes 90 cases revised with the Link MP (Waldemar Link, Hamburg, Germany) prosthesis. The median age at surgery was 72 (38-89) years. Aseptic loosening (70%) and periprosthetic fracture (22%) were common indications for surgery. Sixty-three patients (70%) were followed clinically with a median of 6 (5-11) years of follow-up. All other patients were followed through the Swedish Hip Register. The 5-year survival rate was 98% with stem removal and 90% with any reoperation as the end point. Complications included hip dislocation in 17 (19%) patients. The median Harris hip score was 78 (16-100) points, and the median radiographic stem migration was 2.7 mm at follow-up.

National data of 6409 Swedish inpatients with femoral shaft fractures: Stable incidence between 1998 and 2004

INTRODUCTION Femoral shaft fractures are commonly thought to be primarily associated with high-energy trauma in young persons. Only limited attention has been given to low-energy violence as a cause of these fractures among the elderly. National epidemiological data on characteristics of patients with femoral shaft fractures are lacking, so the purpose of this study was to analyse the incidence, admissions, causes of fracture and operations for these fractures on a nationwide basis in Sweden during 1998-2004. PATIENTS AND METHODS Data on all femoral shaft fractures were extracted from the Swedish National Hospital Discharge Registry. Sex- and age-specific fracture incidence, hospital admissions, mechanisms of injury and surgical procedures were analysed using descriptive analysis, linear-regression analysis and other methods as appropriate. RESULTS Over a period of 7 years, 6409 patients with femoral shaft fractures were identified, corresponding to an annual incidence of 10 per 100,000 person-years. Men had a younger median age (27 years, IQR 12-68) than women (79 years, IQR 62-86) (p<0.001). Females (54%) generated more admissions than males (46%). The incident rate ratio between men and women was 0.9 (p<0.001). Most hospital admissions were generated among females by the 80-89 years age-group and among males <10 years of age. 2% of the fractures were open fractures. The total number of hospital admissions was stable during 1998-2004. The two major mechanisms of injury were falls on the same level (50%) and transport accidents (17%). A significant number of fractures occurred among elderly patients after low-energy trauma. Osteosynthesis with femoral nail (54%) was the preferred operation, followed by osteosynthesis with plate and screws (16%), skeletal traction (14%) and external fixation (6%). DISCUSSION This nationwide study on femoral shaft fractures provides an update on incidence, admissions, external causes and surgical procedures. This information assists health-care providers in planning hospital beds, surgical interventions and risk preventions. Moreover, these data can be used for power calculations for further clinical studies.

Gait pattern in rheumatoid arthritis

The purpose of this study was to analyse kinematic and kinetic gait changes in rheumatoid arthritis (RA) patients in comparison to healthy controls and to examine whether levels of functional disability (Health Assessment Questionnaire (HAQ)-scores) were associated with gait parameters. Using a three-dimensional motion analysis system, kinematic and kinetic gait parameters were measured in 50 RA patients and 37 healthy controls. There was a significant reduction in joint motions, joint moments and work in the RA cohort compared with healthy controls. The following joint motions were decreased: hip flexion-extension range (Delta6 degrees ), hip abduction (Delta4 degrees ), knee flexion-extension range (Delta8 degrees ) and ankle plantarflexion (Delta10 degrees ). The following joint moments were reduced: hip extensor (Delta0.30Nm/kg) and flexor (Delta0.20Nm/kg), knee extensor (Delta0.11Nm/kg) and flexor (Delta0.13Nm/kg), and ankle plantarflexor (Delta0.44Nm/kg). Work was lower in hip positive work (Delta0.07J/kg), knee negative work (Delta0.08J/kg) and ankle positive work (Delta0.15J/kg). Correlations were fair although significant between HAQ and hip flexion-extension range, hip abduction, knee flexion-extension range, hip abductor moment, stride length, step length and single support (r=-0.30 to -0.38, p<0.05). Our findings suggest that RA patients have overall less joint movement and specifically restricted joint moments and work across the large joints of the lower limbs during walking than healthy controls. There were only fair associations between levels of functional disability and gait parameters. The findings of this study help to improve the understanding how RA affects gait changes in the lower limbs.

Maternal smoking during pregnancy, other prenatal and perinatal factors, and the risk of Legg-Calvé-Perthes disease

OBJECTIVE. The causes of Legg-Calvé-Perthes disease are largely unknown, but this pediatric disease seems to result from interruption of the blood supply to the proximal femur and is considered a vascular disease. Because maternal smoking during pregnancy influences fetal development and is associated with cardiovascular diseases in offspring, we hypothesized that this exposure is a risk for Legg-Calvé-Perthes disease and also investigated other markers of impaired fetal development and early-life exposures. MATERIALS AND METHODS. The Swedish Inpatient Register identified 852 individuals with a diagnosis of Legg-Calvé-Perthes disease from 1983 to 2005, individually matched by year of birth, age, sex, and region of residence with 4432 randomly selected control subjects. Linkage with the Swedish Medical Birth Register provided information on prenatal factors, including maternal smoking. Conditional logistic regression examined associations of maternal smoking during pregnancy and the other measures with the risk of Legg-Calvé-Perthes disease in offspring, adjusted for socioeconomic index and other potential confounding factors. RESULTS. Maternal smoking during pregnancy was associated with an increased Legg-Calvé-Perthes disease risk, and heavy smoking was associated with a risk increase of almost 100%. Very low birth weight and cesarean section were independently associated with ∼240% and 36% increases in the risk of Legg-Calvé-Perthes disease, respectively. CONCLUSION. Maternal smoking during pregnancy and other factors indicated by impaired fetal development may be associated with an increased risk of Legg-Calvé-Perthes disease.

Decreasing incidence of tibial shaft fractures between 1998 and 2004 : information based on 10,627 Swedish inpatients

Background and purpose There is a lack of national epidemiological data on the characteristics of patients with tibial shaft fractures. We therefore analyzed data on Swedish patients with tibial shaft fractures in this nationwide population study based on data from 1998 through 2004. Methods Data on all patients with tibial shaft fractures were extracted from the Swedish National Hospital Discharge Register. Results We identified 10,627 hospital admissions for tibial shaft fractures, corresponding to an annual incidence rate of 17 per 100,000 person‐years (pyr). The number of hospital admissions decreased by 12% during the period 1998–2004, mostly from a reduction in male incidence. The median (SD) age at admission was 28 (22) years for men and 51 (26) years for women. The two major mechanisms of injury were falls on the same level (48%) and transport accidents (21%). Surgical procedures were dominated by osteosynthesis with nail (48%), followed by closed reduction and plaster cast (27%), and external fixation (12%). 12% of all tibial shaft fractures were classified as open, corresponding to an incidence rate of 2.3 per 100,000 pyr, which declined during 1998–2004. Interpretation This nationwide study of tibial shaft fractures shows a falling off of fracture incidence, a finding that can be used to advantage by healthcare providers.