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1.  The effect of posterior and lateral approach on patient-reported outcome measures and physical function in patients with osteoarthritis, undergoing total hip replacement: a randomised controlled trial protocol 
Background
Total hip replacement provides pain relief and improves physical function and quality of life in patients with end-stage hip osteoarthritis. The incidence of hip replacement operations is expected to increase due to the growing elderly population. Overall, the posterior approach and lateral approach are the two most commonly used approaches for hip replacement operations. The posterior approach is associated with an increased risk of revision due to dislocations, and some studies have shown that the lateral approach is associated with reduced patient-reported outcomes, including physical function and pain; however, this has not been investigated in a randomised controlled trial with a twelve-month follow-up. We hypothesized that the lateral approach has an inferior outcome in patient-reported outcome compared with the posterior approach after one year.
Methods/Design
The trial is a prospective, double blinded, parallel-group controlled trial with balanced randomisation [1: 1]. Patients with hip osteoarthritis scheduled for hip replacement surgery, aged 45–70 years, will be consecutively recruited and randomised into two groups. Group A will receive hip replacement using the posterior approach, and Group B will receive hip replacement using the lateral approach. The primary end-point for assessing the outcome of the two interventions will be twelve months after surgery. Follow-up will also be performed after three and six months. The primary outcome is Hip Disability and Osteoarthritis Outcome Score, subscale of "Physical function Short form" (HOOS-PS) Secondary outcome measures include two other subscales of HOOS ("Pain" and "Hip related Quality of Life"), physical activity level (UCLA activity score), limping (HHS) and general health status (EQ-5D-3L). Explorative outcomes include physical function test, 3D-gait-analysis and muscle strength.
Discussion
To our knowledge, this is the first randomised controlled trial comparing the posterior approach with the lateral approach with patient reported outcome as the primary outcome and with a twelve-month follow-up.
Trial registration
Clinicaltrial.gov: NCT01616667.
doi:10.1186/1471-2474-15-354
PMCID: PMC4216831  PMID: 25345483
Osteoarthritis; Hip replacement; Surgical approach
2.  Test-retest reliability of Common Mental Disorders Questionnaire (CMDQ) in patients with total hip replacement (THR) 
BMC Psychology  2014;2(1):32.
Background
The Common Mental Disorders Questionnaire (CMDQ) is used to assess patients’ mental health. It has previously been shown to provide a sensitive and specific instrument for general practitioner setting but has so far not been tested in hospital setting or for changes over time (test-retest). The aim of this study is, by means of a test-retest method, to investigate the reliability of the instrument over time with total hip replacement (THR) patients.
Methods
Forty-nine hip osteoarthritis patients who had undergone THR answered the questionnaire twelve months after their operation. Fourteen days later they completed it again. Covering emotional disorder, anxiety, depression, concern, somatoform disorder and alcohol abuse, the questionnaire consists of 38 items with six subscales, each of which has between 4 to 12 items. A five-point Likert scale (from 0–4) is used.
Results
For each of the 38 questions, a quadratic-weighted Kappa coefficient of 0.42 (0.68 – 0.16) to 0.98 (1.00 – 0.70) was found. A Cronbach’s alpha of 0.94 for all the questions indicated high internal consistency.
Conclusion
The results showed a moderate to almost perfect reliability of CMDQ of this specific population.
Trial registration
Current Controlled Trials: NCT01205295
doi:10.1186/s40359-014-0032-5
PMCID: PMC4317134
Test-retest; Reliability; Mental disorders; CMDQ; Kappa; Missing
3.  Countrywise results of total hip replacement 
Acta Orthopaedica  2014;85(2):107-116.
Background and purpose
An earlier Nordic Arthroplasty Register Association (NARA) report on 280,201 total hip replacements (THRs) based on data from 1995–2006, from Sweden, Norway, and Denmark, was published in 2009. The present study assessed THR survival according to country, based on the NARA database with the Finnish data included.
Material and methods
438,733 THRs performed during the period 1995–2011 in Sweden, Denmark, Norway, and Finland were included. Kaplan-Meier survival analysis was used to calculate survival probabilities with 95% confidence interval (CI). Cox multiple regression, with adjustment for age, sex, and diagnosis, was used to analyze implant survival with revision for any reason as endpoint.
Results
The 15-year survival, with any revision as an endpoint, for all THRs was 86% (CI: 85.7–86.9) in Denmark, 88% (CI: 87.6–88.3) in Sweden, 87% (CI: 86.4–87.4) in Norway, and 84% (CI: 82.9–84.1) in Finland. Revision risk for all THRs was less in Sweden than in the 3 other countries during the first 5 years. However, revision risk for uncemented THR was less in Denmark than in Sweden during the sixth (HR = 0.53, CI: 0.34–0.82), seventh (HR = 0.60, CI: 0.37–0.97), and ninth (HR = 0.59, CI: 0.36–0.98) year of follow-up.
Interpretation
The differences in THR survival rates were considerable, with inferior results in Finland. Brand-level comparison of THRs in Nordic countries will be required.
doi:10.3109/17453674.2014.893498
PMCID: PMC3967250  PMID: 24650019
4.  Local anesthetic wound infiltration for pain management after periacetabular osteotomy 
Acta Orthopaedica  2014;85(2):141-146.
Background and purpose
To our knowledge, there is no evidence to support the use of local infiltration analgesia (LIA) for postoperative pain relief after periacetabular osteotomy (PAO). We investigated the effect of wound infiltration with a long-acting local anesthetic (ropivacaine) for postoperative analgesia after PAO.
Patients and methods
We performed a randomized, double-blind, placebo-controlled trial (ClinicalTrials.gov: NCT00815503) in 53 patients undergoing PAO to evaluate the effect of local anesthetic infiltration on postoperative pain and on postoperative opioid consumption. All subjects received intraoperative infiltration followed by 5 postoperative injections in 10-hour intervals through a multi-holed catheter placed at the surgical site. 26 patients received ropivacaine and 27 received saline. The intervention period was 2 days and the observational period was 4 days. All subjects received patient-controlled opioid analgesia without any restrictions on the total daily dose. Pain was assessed at specific postoperative time points and the daily opioid usage was registered.
Results
Infiltration with 75 mL (150 mg) of ropivacaine did not reduce postoperative pain or opioid requirements during the first 4 days.
Interpretation
The clinical importance of ropivacaine as single component in postoperative treatment of pain is questionable, and we are planning further studies to explore the potential of LIA in larger volume—and also a multimodal regimen—to treat pain in this category of patients.
doi:10.3109/17453674.2014.899840
PMCID: PMC3967255  PMID: 24650022
5.  The efficacy of tourniquet assisted total knee arthroplasty on patient-reported and performance-based physical function: a randomized controlled trial protocol 
Background
Surgical treatment of osteoarthritis with total knee arthroplasty (TKA) usually takes place in a complete bloodless field using a tourniquet. However, doing the surgery without a tourniquet may reduce muscle damage, post-surgery pain and led to improved functional rehabilitation and mobilization.
Methods/Design
A prospective, blinded, parallel-group, controlled superiority trial, with balanced randomization [1:1]. Patients aged 50 or older eligible for primary TKA for osteoarthritis will be consecutively recruited from Department of Orthopedic Surgery and Traumatology, Odense University Hospital, Denmark. A total of 80 patients will be randomly allocated to TKA with or without tourniquet application providing 40 patients for each of the two treatment arms. The tourniquet assisted TKA group will have an automatic, micro-processor-based pneumatic tourniquet inflated around the thigh during surgery. The non-tourniquet assisted TKA group will have surgery performed without application of a tourniquet. The primary aim is to compare tourniquet assisted to non-tourniquet assisted TKA on patient-reported physical function (KOOS-ADL). The secondary aim is to compare post-surgery pain, function in sports and recreation, quality of life, and performance-based physical function. The explorative outcomes include; use of pain medication, single-fiber muscle damage, and changes in mechanical muscle function. The primary endpoint will be at 3-months following surgical treatment, and the time-point for analysis of the primary outcome. However, follow-up will continue up to 1 year, and provide medium-term results. The treatment effect (difference in KOOS-ADL) will be analyzed using a random effects regression model, crude and adjusted results will be reported, if needed. Analyses will be based on the intention-to-treat (ITT). Subsequent per-protocol analysis may be necessary in the event of a substantial number of patients (> 15%) being lost during follow-up. The number needed to treat (NNT) for a positive effect of treatment (>10 points on KOOS-ADL) will be reported.
Discussion
This is the first randomized clinical trial comparing the efficacy of tourniquet assisted TKA on patient-reported physical function supported by a range of performance-based secondary outcome measures. As such it will provide high quality evidence that may help determine whether tourniquet should be used in future TKA procedures in patients with osteoarthritis of the knee.
Trial registration
ClinicalTrials NCT01891266.
doi:10.1186/1471-2474-15-110
PMCID: PMC3978123  PMID: 24678741
Tourniquet; Total knee arthroplasty; Patient-reported; Performance-based; Physical function
6.  Low validity of the Sensewear Pro3 activity monitor compared to indirect calorimetry during simulated free living in patients with osteoarthritis of the hip 
Background
To validate physical activity estimates by the Sensewear Pro3 activity monitor compared with indirect calorimetry during simulated free living in patients diagnosed with osteoarthritis of the hip pre or post total hip arthroplasty.
Methods
Twenty patients diagnosed with hip osteoarthritis (10 pre- and 10 post total hip arthroplasty; 40% female; age: 63.3 ± 9.0; BMI: 23.7 ± 3.7). All patients completed a 2 hour protocol of simulated free living with 8 different typical physical activity types. Energy consumption (kcal/min) was estimated by the Sense Wear pro3 Armband activity monitor and validated against indirect calorimetry (criterion method) by means of a portable unit (Cosmed K4b2). Bias and variance was analyzed using functional ANOVA.
Results
Mean bias during all activities was 1.5 Kcal/min 95%CI [1.3; 1.8] corresponding to 72% (overestimation). Normal gait speed showed an overestimation of 2.8 Kcal/min, 95%CI [2.3; 3.3] (93%) while an underestimation of -1.1 Kcal/min, 95%CI [-1.8; -0.3] (-25%) was recorded during stair climb. Activities dominated by upper body movements showed large overestimation with 4.37 Kcal/min, 95%CI [3.8; 5.1] (170%) being recorded during gardening. Both bias and variance appeared to be dependent on activity type.
Conclusion
The activity monitor generally overestimated the energy consumption during common activities of low to medium intensity in the patient group. The size and direction of the bias was highly dependent on the activity type which indicates the activity monitor is of limited value in patients with hip osteoarthritis and that the results do not express the real energy expenditure.
doi:10.1186/1471-2474-15-43
PMCID: PMC3938645  PMID: 24552503
7.  Heritability of clubfoot: a twin study 
Introduction
The aetiology of congenital clubfoot is unclear. Although studies on populations, families, and twins suggest a genetic component to the aetiology, other studies have identified environmental factors. The purpose of this study was to calculate heritability in order to determine to what extent genetic and/or environmental factors contribute to the aetiology of congenital clubfoot and to asses whether there was a change in the prevalence over time.
Materials and Methods
The Odense based Danish Twin Registry is unique as it contains data on all the approximately 85,000 twin pairs born in Denmark over the last 140 years. All 46,418 twin individuals born from 1931 through 1982, who had earlier consented to contact, received a 17-page Omnibus questionnaire in the spring of 2002. Data were analysed with structural equation models to identify the best fitting aetiological model based on a balance of goodness-of-fit and parsimony and to estimate heritability.
Results
We found an overall self-reported prevalence of congenital clubfoot of 0.0027 (95 % confidence interval 0.0022–0.0034). Fifty-five complete (both twins answered the question) twin pairs were identified representing 12 monozygotic, 22 same-sex dizygotic, 18 opposite-sex dizygotic, and 3 with unclassified zygosity. The model with only environmental factors (CE) was best fitting based on AIC, and the model with an additive genetic factor (ACE) came in second. Due to the small statistical power, we hypothesise that the model with both genetic and environmental effects (ACE) was the better model. Choosing the ACE-model we found a heritability of clubfoot of 30 %. Regression coefficient for age was −0.002 (−0.011 to 0.005), indicating that there has been no change in prevalence of clubfoot over the 50-year age span we examined.
Discussion
We conclude that non-genetic factors must play a role, and a genetic factor might contribute, in the aetiology of congenital clubfoot.
doi:10.1007/s11832-014-0562-7
PMCID: PMC3935025  PMID: 24504418
Clubfoot; Twins; Heritability; Genetics; Aetiology
8.  Increased risk of revision in patients with non-traumatic femoral head necrosis 
Acta Orthopaedica  2014;85(1):11-17.
Background and purpose
Previous studies of patients who have undergone total hip arthroplasty (THA) due to femoral head necrosis (FHN) have shown an increased risk of revision compared to cases with primary osteoarthritis (POA), but recent studies have suggested that this procedure is not associated with poor outcome. We compared the risk of revision after operation with THA due to FHN or POA in the Nordic Arthroplasty Register Association (NARA) database including Denmark, Finland, Norway, and Sweden.
Patients and methods
427,806 THAs performed between 1995 and 2011 were included. The relative risk of revision for any reason, for aseptic loosening, dislocation, deep infection, and periprosthetic fracture was studied before and after adjustment for covariates using Cox regression models.
Results
416,217 hips with POA (mean age 69 (SD 10), 59% females) and 11,589 with FHN (mean age 65 (SD 16), 58% females) were registered. The mean follow-up was 6.3 (SD 4.3) years. After 2 years of observation, 1.7% in the POA group and 3.0% in the FHN group had been revised. The corresponding proportions after 16 years of observation were 4.2% and 6.1%, respectively. The 16-year survival in the 2 groups was 86% (95% CI: 86–86) and 77% (CI: 74–80). After adjusting for covariates, the relative risk (RR) of revision for any reason was higher in patients with FHN for both periods studied (up to 2 years: RR = 1.44, 95% CI: 1.34–1.54; p < 0.001; and 2–16 years: RR = 1.25, 1.14–1.38; p < 0.001).
Interpretation
Patients with FHN had an overall increased risk of revision. This increased risk persisted over the entire period of observation and covered more or less all of the 4 most common reasons for revision.
doi:10.3109/17453674.2013.874927
PMCID: PMC3940986  PMID: 24359026
9.  Minimal clinically important improvement (MCII) and patient-acceptable symptom state (PASS) in total hip arthroplasty (THA) patients 1 year postoperatively 
Acta Orthopaedica  2014;85(1):39-48.
Background and purpose
The increased use of patient-reported outcomes (PROs) in orthopedics requires data on estimated minimal clinically important improvements (MCIIs) and patient-acceptable symptom states (PASSs). We wanted to find cut-points corresponding to minimal clinically important PRO change score and the acceptable postoperative PRO score, by estimating MCII and PASS 1 year after total hip arthroplasty (THA) for the Hip Dysfunction and Osteoarthritis Outcome Score (HOOS) and the EQ-5D.
Patients and methods
THA patients from 16 different departments received 2 PROs and additional questions preoperatively and 1 year postoperatively. The PROs included were the HOOS subscales pain (HOOS Pain), physical function short form (HOOS-PS), and hip-related quality of life (HOOS QoL), and the EQ-5D. MCII and PASS were estimated using multiple anchor-based approaches.
Results
Of 1,837 patients available, 1,335 answered the preoperative PROs, and 1,288 of them answered the 1-year follow-up. The MCIIs and PASSs were estimated to be: 24 and 91 (HOOS Pain), 23 and 88 (HOOS-PS), 17 and 83 (HOOS QoL), 0.31 and 0.92 (EQ-5D Index), and 23 and 85 (EQ-VAS), respectively. MCIIs corresponded to a 38–55% improvement from mean baseline PRO score and PASSs corresponded to absolute follow-up scores of 57–91% of the maximum score in THA patients 1 year after surgery.
Interpretation
This study improves the interpretability of PRO scores. The different estimation approaches presented may serve as a guide for future MCII and PASS estimations in other contexts. The cutoff points may serve as reference values in registry settings.
doi:10.3109/17453674.2013.867782
PMCID: PMC3940990  PMID: 24286564
10.  Low bone mineral density is not related to failure in femoral neck fracture patients treated with internal fixation 
Acta Orthopaedica  2014;85(1):60-65.
Background and purpose
Internal fixation (IF) in femoral neck fractures has high reoperation rates and some predictors of failure are known, such as age, quality of reduction, and implant positioning. Finding new predictors of failure is an ongoing process, and in this study we evaluated the importance of low bone mineral density (BMD).
Patients and methods
140 consecutive patients (105 females, median age 80) treated with IF had a dual-energy X-ray absorptiometry (DXA) scan of the hip performed median 80 days after treatment. The patients’ radiographs were evaluated for fracture displacement, implant positioning, and quality of reduction. From a questionnaire completed during admission, 2 variables for comorbidity and walking disability were chosen.
Primary outcome was low hip BMD (amount of mineral matter per square centimeter of hip bone) compared to hip failure (resection, arthroplasty, or new hip fracture). A stratified Cox regression model on fracture displacement was applied and adjusted for age, sex, quality of reduction, implant positioning, comorbidity, and walking disability.
Results
49 patients had a T-score below –2.5 (standard deviation from the young normal reference mean) and 70 patients had a failure. The failure rate after 2 years was 22% (95% CI: 12–39) for the undisplaced fractures and 66% (CI: 56–76) for the displaced fractures. Cox regression showed no association between low hip BMD and failure. For the covariates, only implant positioning showed an association with failure.
Interpretation
We found no statistically significant association between low hip BMD and fixation failure in femoral neck fracture patients treated with IF.
doi:10.3109/17453674.2013.875360
PMCID: PMC3940993  PMID: 24359030
11.  Factors influencing health-related quality of life after total hip replacement - a comparison of data from the Swedish and Danish hip arthroplasty registers 
Background
There is an increasing focus on measuring patient-reported outcomes (PROs) as part of routine medical practice, particularly in fields such as joint replacement surgery where pain relief and improvement in health-related quality of life (HRQoL) are primary outcomes. Between-country comparisons of PROs may present difficulties due to cultural differences and differences in the provision of health care. However, in order to understand how these differences affect PROs, common predictors for poor and good outcomes need to be investigated. This cross-sectional study investigates factors influencing health-related quality of life (HRQoL) one year after total hip replacement (THR) surgery in Sweden and in Denmark.
Methods
Data was retrieved from the Swedish (n = 14 560 patients) and Danish (n = 632 patients) Hip Arthroplasty Registers according to preset selection criteria. Using linear regression models, we examined how sex, age, comorbidity and country of surgery were associated with different aspects of HRQoL as measured by the EQ-5D index and EQ VAS.
Results
Danish patients had an overall higher EQ-5D index and EQ VAS than Swedish patients (p < 0.001). After regression analysis, the estimated coefficients for sex, age, or the Charlson score did not differ between countries for either the EQ-5D index (p = 0.83) or EQ VAS (p = 0.41) one year after THR.
Conclusions
We conclude that there are clear similarities in how basic predictors influence patient-reported outcomes (PROs) in patients with THR in Sweden and Denmark and these known predictors of good or poor HRQoL outcomes are not specific for each country.
doi:10.1186/1471-2474-14-316
PMCID: PMC4228371  PMID: 24192304
Total hip replacement; EQ-5D; Predictors; Comorbidity; Patient-reported outcome; Patient-reported outcome measures; Register study
12.  Effects of a perfusion bioreactor activated novel bone substitute in spine fusion in sheep 
European Spine Journal  2012;21(9):1740-1747.
Purpose
To evaluate the effect of a large perfusion-bioreactor cell-activated bone substitute, on a two-level large posterolateral spine fusion sheep model.
Methods
A 50 mm long porous biphasic-calcium–phosphate bone substitute reinforced with poly(d,l-lactide) and, activated with bone marrow derived mononuclear-cells (BMNC) was used. Eighteen sheep were divided into two groups and one group (n = 9) had BMNC-activated bone substitutes and cell-free substitutes implanted. The second group (n = 9) had autograft supplemented with BMNC and regular autograft implanted. The implant material was alternated between spine level L2–L3 and L4–L5 in both groups. MicroCT was used to compare the spine fusion efficacy and bone structure of the two groups as well as the implanted bone substitutes and non-implanted substitutes.
Results
After 4½ months six sheep survived in both groups and we found five spine levels were fused when using activated bone substitute compared to three levels with cell-free bone substitute (p = 0.25). Five sheep fused at both levels in the autograft group. A significant increased bone density (p < 0.05) and anisotropy (p < 0.05) was found in the group of activated bone substitutes compared to cell-free bone substitute and no difference existed on the other parameters. The implanted bone substitutes had a significant higher bone density and trabecular thickness than non-implanted bone substitutes, thus indicating that the PLA reinforced BCP had osteoconductive properties (p < 0.05). No effect of the supplemented BMNC to autograft was observed. The autograft group had a significant higher bone density, trabecular thickness and degree of anisotropy than the implanted bone substitutes (p < 0.05), but a lower connectivity density existed (p < 0.05). This indicates that though the activated substitute might have a similar fusion efficacy to autograft, the fusion bridge is not of equal substance.
Conclusion
We found that bioreactor-generated cell-based bone substitutes seemed superior in fusion ability when compared to cell-free bone substitute and comparable to autograft in fusion ability, but not in bone structure. This combined with the favorable biocompatible abilities and strength comparable to human cancellous bone indicates that it might be a suitable bone substitute in spine fusion procedures.
doi:10.1007/s00586-012-2421-x
PMCID: PMC3459119  PMID: 22777077
Bone graft substitute; Poly(d,l-lactide) enhanced hydroxyappatite/β-tricalciumphosphate; Perfusion bioreactor; Posterolateral spine fusion; Microarchitecture
13.  Similar range of motion and function after resurfacing large–head or standard total hip arthroplasty 
Acta Orthopaedica  2013;84(3):246-253.
Background and purpose
Large–size hip articulations may improve range of motion (ROM) and function compared to a 28–mm THA, and the low risk of dislocation allows the patients more activity postoperatively. On the other hand, the greater extent of surgery for resurfacing hip arthroplasty (RHA) could impair rehabilitation. We investigated the effect of head size and surgical procedure on postoperative rehabilitation in a randomized clinical trial (RCT).
Methods
We followed randomized groups of RHAs, large–head THAs and standard THAs at 2 months, 6 months, 1 and 2 years postoperatively, recording clinical rehabilitation parameters.
Results
Large articulations increased the mean total range of motion by 13° during the first 6 postoperative months. The increase was not statistically significant and was transient. The 2–year total ROM (SD) for RHA, standard THA, and large–head THA was 221° (35), 232° (36), and 225° (30) respectively, but the differences were not statistically significant. The 3 groups were similar regarding Harris hip score, UCLA activity score, step rate, and sick leave.
Interpretation
Head size had no influence on range of motion. The lack of restriction allowed for large articulations did not improve the clinical and patient–perceived outcomes. The more extensive surgical procedure of RHA did not impair the rehabilitation.
This project is registered at ClinicalTrials.gov under # NCT01113762.
doi:10.3109/17453674.2013.788435
PMCID: PMC3715815  PMID: 23530872
14.  Lower reoperation rate for cemented hemiarthroplasty than for uncemented hemiarthroplasty and internal fixation following femoral neck fracture 
Acta Orthopaedica  2013;84(3):254-259.
Background and purpose
Elderly patients with displaced femoral neck fractures are commonly treated with a hemiarthroplasty (HA), but little is known about the long-term failure of this treatment. We compared reoperation rates for patients aged at least 75 years with displaced femoral neck fractures treated with either internal fixation (IF), cemented HA, or uncemented HA (with or without hydroxyapatite coating), after 12–19 years of follow-up.
Methods
4 hospitals with clearly defined guidelines for the treatment of 75+ year-old patients with a displaced femoral neck fracture were included. Cohort 1 (1991–1993) with 180 patients had undergone IF; cohort 2 (1991–1995) with 203 patients had received an uncemented bipolar Ultima HA stem (Austin-Moore); cohort 3 (1991–1995) with 209 patients had received a cemented Charnley-Hastings HA; and cohort 4 (1991–1998) with 158 patients had received an uncemented hydroxyapatite-coated Furlong HA. Data were retrieved from patient files, from the region-based patient administrative system, and from the National Registry of Patients at the end of 2010. We performed survival analysis with adjustment for comorbidity, age, and sex.
Results
Cemented HA had a reoperation rate (RR) of 5% and was used as reference in the Cox regression analysis, which showed significantly higher hazard ratios (HRs) for IF (HR = 3.8, 95% CI: 1.9–7.5; RR = 18%), uncemented HA (HR = 2.2, CI: 1.1–4.5; RR = 11%) and uncemented hydroxyapatite-coated HA (HR = 3.6, CI: 1.8–7.4; RR = 16%).
Interpretation
Cemented HA has a superior long-term hip survival rate compared to IF and uncemented HA (with and without hydroxyapatite coating) in patients aged 75 years or more with displaced femoral neck fractures.
doi:10.3109/17453674.2013.792033
PMCID: PMC3715822  PMID: 23594248
15.  The effect of education and supervised exercise vs. education alone on the time to total hip replacement in patients with severe hip osteoarthritis. A randomized clinical trial protocol 
Background
The age- and gender-specific incidence of total hip replacement surgery has increased over the last two decades in all age groups. Recent studies indicate that non-surgical interventions are effective in reducing pain and disability, even at later stages of the disease when joint replacement is considered. We hypothesize that the time to hip replacement can be postponed in patients with severe hip osteoarthritis following participation in a patient education and supervised exercise program when compared to patients receiving patient education alone.
Methods/design
A prospective, blinded, parallel-group multi-center trial (2 sites), with balanced randomization [1:1]. Patients with hip osteoarthritis and an indication for hip replacement surgery, aged 40 years and above, will be consecutively recruited and randomized into two treatment groups. The active treatment group will receive 3 months of supervised exercise consisting of 12 sessions of individualized, goal-based neuromuscular training, and 12 sessions of intensive resistance training plus patient education (3 sessions). The control group will receive only patient education (3 sessions). The primary end-point for assessing the effectiveness of the intervention is 12 months after baseline. However, follow-ups will also be performed once a year for at least 5 years. The primary outcome measure is the time to hip replacement surgery measured on a Kaplain-Meier survival curve from time of inclusion. Secondary outcome measures are the five subscales of the Hip disability and Osteoarthritis Outcome Score, physical activity level (UCLA activity score), and patient’s global perceived effect. Other measures include pain after exercise, joint-specific adverse events, exercise adherence, general health status (EQ-5D-5L), mechanical muscle strength and performance in physical tests. A cost-effectiveness analysis will also be performed.
Discussion
To our knowledge, this is the first randomized clinical trial comparing a patient education plus supervised exercise program to patient education alone in hip osteoarthritis patients with an indication for surgery on the time to total hip replacement.
Trial registration
NCT01697241
doi:10.1186/1471-2474-14-21
PMCID: PMC3561107  PMID: 23311889
Exercise therapy; Education; Osteoarthritis; Hip; Hip replacement
16.  Reproducibility of range of motion and muscle strength measurements in patients with hip osteoarthritis – an inter-rater study 
Background
Assessment of range of motion (ROM) and muscle strength is fundamental in the clinical diagnosis of hip osteoarthritis (OA) but reproducibility of these measurements has mostly involved clinicians from secondary care and has rarely reported agreement parameters. Therefore, the primary objective of the study was to determine the inter-rater reproducibility of ROM and muscle strength measurements. Furthermore, the reliability of the overall assessment of clinical hip OA was evaluated. Reporting is in accordance with proposed guidelines for the reporting of reliability and agreement studies (GRRAS).
Methods
In a university hospital, four blinded raters independently examined patients with unilateral hip OA; two hospital orthopaedists independently examined 48 (24 men) patients and two primary care chiropractors examined 61 patients (29 men). ROM was measured in degrees (deg.) with a standard two-arm goniometer and muscle strength in Newton (N) using a hand-held dynamometer. Reproducibility is reported as agreement and reliability between paired raters of the same profession. Agreement is reported as limits of agreement (LoA) and reliability is reported with intraclass correlation coefficients (ICC). Reliability of the overall assessment of clinical OA is reported as weighted kappa.
Results
Between orthopaedists, agreement for ROM ranged from LoA [-28–12 deg.] for internal rotation to [-8–13 deg.] for extension. ICC ranged between 0.53 and 0.73, highest for flexion. For muscle strength between orthopaedists, LoA ranged from [-65–47N] for external rotation to [-10 –59N] for flexion. ICC ranged between 0.52 and 0.85, highest for abduction. Between chiropractors, agreement for ROM ranged from LoA [-25–30 deg.] for internal rotation to [-13–21 deg.] for flexion. ICC ranged between 0.14 and 0.79, highest for flexion. For muscle strength between chiropractors, LoA ranged between [-80–20N] for external rotation to [-146–55N] for abduction. ICC ranged between 0.38 and 0.81, highest for flexion. Weighted kappa for the overall assessment of clinical hip OA was 0.52 between orthopaedists and 0.65 between chiropractors.
Conclusions
Reproducibility of goniometric and dynamometric measurements of ROM and muscle strength in patients with hip OA is poor between experienced orthopaedists and between experienced chiropractors. Orthopaedists and chiropractors can to a moderate degree differentiate between hips with or without osteoarthritis.
doi:10.1186/1471-2474-13-242
PMCID: PMC3565957  PMID: 23217149
Hip; Examination; Inter-observer; Reliability; Osteoarthritis; Hip
17.  Low revision rate after total hip arthroplasty in patients with pediatric hip diseases 
Acta Orthopaedica  2012;83(5):436-441.
Background
The results of primary total hip arthroplasties (THAs) after pediatric hip diseases such as developmental dysplasia of the hip (DDH), slipped capital femoral epiphysis (SCFE), or Perthes’ disease have been reported to be inferior to the results after primary osteoarthritis of the hip (OA).
Materials and methods
We compared the survival of primary THAs performed during the period 1995–2009 due to previous DDH, SCFE, Perthes’ disease, or primary OA, using merged individual-based data from the Danish, Norwegian, and Swedish arthroplasty registers, called the Nordic Arthroplasty Register Association (NARA). Cox multiple regression, with adjustment for age, sex, and type of fixation of the prosthesis was used to calculate the survival of the prostheses and the relative revision risks.
Results
370,630 primary THAs were reported to these national registers for 1995–2009. Of these, 14,403 THAs (3.9%) were operated due to pediatric hip diseases (3.1% for Denmark, 8.8% for Norway, and 1.9% for Sweden) and 288,435 THAs (77.8%) were operated due to OA. Unadjusted 10-year Kaplan-Meier survival of THAs after pediatric hip diseases (94.7% survival) was inferior to that after OA (96.6% survival). Consequently, an increased risk of revision for hips with a previous pediatric hip disease was seen (risk ratio (RR) 1.4, 95% CI: 1.3–1.5). However, after adjustment for differences in sex and age of the patients, and in fixation of the prostheses, no difference in survival was found (93.6% after pediatric hip diseases and 93.8% after OA) (RR 1.0, CI: 1.0–1.1). Nevertheless, during the first 6 postoperative months more revisions were reported for THAs secondary to pediatric hip diseases (RR 1.2, CI: 1.0–1.5), mainly due to there being more revisions for dislocations (RR 1.8, CI: 1.4–2.3). Comparison between the different diagnosis groups showed that the overall risk of revision after DDH was higher than after OA (RR 1.1, CI: 1.0–1.2), whereas the combined group Perthes’ disease/SCFE did not have a significantly different risk of revision to that of OA (RR 0.9, CI: 0.7–1.0), but had a lower risk than after DDH (RR 0.8, CI: 0.7–1.0).
Interpretation
After adjustment for differences in age, sex, and type of fixation of the prosthesis, no difference in risk of revision was found for primary THAs performed due to pediatric hip diseases and those performed due to primary OA.
doi:10.3109/17453674.2012.736171
PMCID: PMC3488168  PMID: 23043269
18.  Increasing risk of prosthetic joint infection after total hip arthroplasty 
Acta Orthopaedica  2012;83(5):449-458.
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.
doi:10.3109/17453674.2012.733918
PMCID: PMC3488170  PMID: 23083433
19.  Patient anxiety and concern as predictors for the perceived quality of treatment and patient reported outcome (PRO) in orthopaedic surgery 
Background
Previous studies have shown that patients’ anxiety and dissatisfaction are predictors for increased postoperative pain and reduced efficacy of pain treatment. However, it remains to be shown whether patient anxiety and concern are predictors for the perceived quality of treatment and patient reported outcome (PRO).
The aim of this study is to investigate whether there is a correlation between preoperative anxiety and concern, and the perceived quality of postoperative treatment and outcome. The hypothesis is that anxious and concerned patients are less satisfied with treatment and have a poorer outcome.
Methods/design
This study is designed as a prospective follow-up study and has the aim of investigating the correlation between patient anxiety and concern, patients´ perceived quality of treatment and outcome. This correlation will be detected using five questionnaires: CMD-SQ (Common Mental Disorders Screening Questionnaire), EuroQol 5 Dimensions (EQ-5D), Short form 12 (SF-12), “What is your evaluation of the patient progress in the Department of Orthopaedic Surgery?” (HVOK), Questionnaire for patients who have had hip surgery (RCS) and Oxford Hip Score (OHS) or Oxford Shoulder Score (OSS). The patients will complete the above mentioned questionnaires preoperatively in the outpatient department, and postoperatively just before discharge from the inpatient department, and 12 and 52 weeks after the operation. The study includes a reliability test of CMD-SQ regarding this specific population and tested by means of a Kappa. A total of 500 hip- and shoulder-patients will be included from October 2010 till October 2011.
Discussion
If a correlation between patient anxiety and concern, patients´ perceived quality of treatment and patient reported outcome is found, it will be recommended to screen all hip- and shoulder-patients for anxiety and concern preoperatively. Besides, it would be relevant to carry out investigations of possible interventions towards anxious and concerned patients.
Trial registration
Current Controlled Trials: NCT01205295
doi:10.1186/1472-6963-12-244
PMCID: PMC3496589  PMID: 22873940
20.  Feasibility of 4 patient-reported outcome measures in a registry setting 
Acta Orthopaedica  2012;83(4):321-327.
Background and purpose
Feasibility is an important parameter when choosing which patient-reported outcomes (PRO) to use in a study. We assessed the feasibility of PROs in a hip registry setting.
Methods
Primary total hip arthroplasty (THA) patients (n = 5,747) who had been operated on 1–2, 5–6, or 10–11 years previously were randomly selected from the Danish Hip Arthroplasty Register and sent 2 PRO questionnaires: 1 generic (EuroQoL-5D or SF-12 health survey) and 1 disease-specific (hip dysfunction and osteoarthritis outcome score (HOOS) or Oxford 12-item hip score). We compared response rates, floor and ceiling effects, missing items, and the need for manual validation of forms.
Results
4,784 patients (mean age 71 years, 57% females) were included (83%). The response rates ranged from 82–84%. Statistically significantly different floor and ceiling effects ranged from 0% to 0.5% and from 6.1% to 46%, respectively. Missing items ranged from 1.2% to 3.4%, and 0.8–4.3% required manual validation (p < 0.009). A hypothetical repeat study found that group sizes from 51 to 1,566 are needed for subgroup analysis, depending on descriptive factor and choice of PRO.
Interpretation
All 4 PROs fulfilled a priori set criteria, with the exception of ceiling effects. The high ceiling effects were attributed to postoperative administration and good outcome for THA. We conclude that all 4 PROs are appropriate for administration in a hip registry.
doi:10.3109/17453674.2012.702390
PMCID: PMC3427620  PMID: 22900909
21.  Quality of Data Entry Using Single Entry, Double Entry and Automated Forms Processing–An Example Based on a Study of Patient-Reported Outcomes 
PLoS ONE  2012;7(4):e35087.
Background
The clinical and scientific usage of patient-reported outcome measures is increasing in the health services. Often paper forms are used. Manual double entry of data is defined as the definitive gold standard for transferring data to an electronic format, but the process is laborious. Automated forms processing may be an alternative, but further validation is warranted.
Methods
200 patients were randomly selected from a cohort of 5777 patients who had previously answered two different questionnaires. The questionnaires were scanned using an automated forms processing technique, as well as processed by single and double manual data entry, using the EpiData Entry data entry program. The main outcome measure was the proportion of correctly entered numbers at question, form and study level.
Results
Manual double-key data entry (error proportion per 1000 fields = 0.046 (95% CI: 0.001–0.258)) performed better than single-key data entry (error proportion per 1000 fields = 0.370 (95% CI: 0.160–0.729), (p = 0.020)). There was no statistical difference between Optical Mark Recognition (error proportion per 1000 fields = 0.046 (95% CI: 0.001–0.258)) and double-key data entry (p = 1.000). With the Intelligent Character Recognition method, there was no statistical difference compared to single-key data entry (error proportion per 1000 fields = 6.734 (95% CI: 0.817–24.113), (p = 0.656)), as well as double-key data entry (error proportion per 1000 fields = 3.367 (95% CI: 0.085–18.616)), (p = 0.319)).
Conclusions
Automated forms processing is a valid alternative to double manual data entry for highly structured forms containing only check boxes, numerical codes and no dates. Automated forms processing can be superior to single manual data entry through a data entry program, depending on the method chosen.
doi:10.1371/journal.pone.0035087
PMCID: PMC3320865  PMID: 22493733
22.  The Need for Total Hip Arthroplasty in Perthes Disease: A Long-term Study 
Background
Legg-Calvé-Perthes disease (LCPD) was described a century ago. In previous long-term reports of patients with LCPD, nonoperative treatment varied considerably. The likelihood of hip osteoarthritis (OA) developing in patients with LCPD and possible need for THA are not well defined.
Questions/purposes
The purpose of the study was to determine whether nonoperatively treated patients with LCPD (1) had an increased prevalence of THA compared with gender- and age-matched control subjects, (2) if patients with Stulberg Classes III/IV/V femoral heads had an increased risk of THA compared with those with Classes I/II femoral heads. Given the limitation in the study, we (3) evaluated whether patients with LCPD were at risk for having radiographic hip OA more commonly than control subjects and (4) whether hips with Classes III/IV/V femoral heads had an increased prevalence of OA compared with hips with Classes I/II femoral heads.
Patients and Methods
The study population consisted of 167 patients with LCPD treated with a Thomas splint. The control population consisted of gender- and age-matched control subjects who were participants in the Copenhagen City Heart Study: the Osteoarthritis Substudy. Radiographs at skeletal maturity were classified according to the classification system of Stulberg et al. Data from the Danish Hip Arthroplasty Register and the Registries of the National Board of Health were collected to obtain the number of patients with LCPD having THA. At a mean followup of 47 years later (range, 37–58 years), weightbearing pelvic radiographs were obtained. Radiographic OA was defined as a joint space width of 2.0 mm or less.
Results
Thirteen percent of patients with LCPD had THAs compared with none in the control group. Seven percent of the patients with LCPD had OA compared with 1% in the control group. The prevalence of THA and OA was increased in hips with Classes III/IV/V femoral heads compared with hips with Classes I/II femoral heads.
Conclusions
Patients with LCPD have an increased risk of having THA compared with a gender- and age-matched control group. Our data suggest that patients with LCPD have a greater risk of having radiographic OA develop than a gender- and age-matched control group. It seems that patients with Classes III/IV/V femoral heads have an increased risk of THA and OA compared with patients with Classes I/II femoral heads.
Level of Evidence
Level III, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-010-1566-3
PMCID: PMC3048259  PMID: 20838945
23.  Non-surgical treatment of hip osteoarthritis. Hip school, with or without the addition of manual therapy, in comparison to a minimal control intervention: Protocol for a three-armed randomized clinical trial 
Background
Hip osteoarthritis is a common and chronic condition resulting in pain, functional disability and reduced quality of life. In the early stages of the disease, a combination of non-pharmacological and pharmacological treatment is recommended. There is evidence from several trials that exercise therapy is effective. In addition, single trials suggest that patient education in the form of a hip school is a promising intervention and that manual therapy is superior to exercise.
Methods/Design
This is a randomized clinical trial. Patients with clinical and radiological hip osteoarthritis, 40-80 years of age, and without indication for hip surgery were randomized into 3 groups. The active intervention groups A and B received six weeks of hip school, taught by a physiotherapist, for a total of 5 sessions. In addition, group B received manual therapy consisting of joint manipulation and soft-tissue therapy twice a week for six weeks. Group C received a self-care information leaflet containing advice on "live as usual" and stretching exercises from the hip school. The primary time point for assessing relative effectiveness is at the end of the six weeks intervention period with follow-ups after three and 12 months.
Primary outcome measure is pain measured on an eleven-point numeric rating scale. Secondary outcome measures are the hip dysfunction and osteoarthritis outcome score, patient's global perceived effect, patient specific functional scale, general quality of life and hip range of motion.
Discussion
To our knowledge this is the first randomized clinical trial comparing a patient education program with or without the addition of manual therapy to a minimal intervention for patients with hip osteoarthritis.
Trial registration
ClinicalTrials NCT01039337
doi:10.1186/1471-2474-12-88
PMCID: PMC3112433  PMID: 21542914
24.  Microdialysis in the femoral head of the minipig and in a blood cloth of human blood 
Acta Orthopaedica  2011;82(2):241-245.
Introduction
Microdialysis can detect ischemia in soft tissue. In a previous study, we have shown the development of ischemia in the femoral head removed from patients undergoing total hip replacement. That study also raised some methodological questions that this study tries to answer: what is happening in the dead space around the catheter in the drill canal, and is there an equilibrium period after the insertion of the catheter?
Material and methods
In an ex-vivo study using 5 syringes with 5 mL human blood, a microdialysis catheter was inserted and microdialysis was performed over 3 h. In an in-vivo study, a drill hole was made in the proximal part of the femur in 6 mature Göttingen minipigs and microdialysis was performed over 3 h. The pigs were kept normoventilated during the experiment.
Results
The ex-vivo microdialysis results showed that lactate kept a steady level and glucose and glycerol both fell; pyruvate fell but leveled out. The mean lactate/pyruvate ratio increased from 13 (SD 4) to 32 (SD 6) (p < 0.001). In vivo, relative recovery was 57% (SD 11). Lactate increased, pyruvate stayed constant, and glucose and glycerol levels fell. The lactate/pyruvate ratio increased from 30 (8) initially to 37 (8) after 1 h (p = 0.007) but no statistically significant change from 1 to 2 h was observed.
Interpretation
The ex-vivo study showed a clear washout pattern, and was different from what we see in bone. The in-vivo study indicated that an equilibrium period is necessary or that a reference measurement in healthy bone must be used when performing short measurements in bone.
doi:10.3109/17453674.2011.566132
PMCID: PMC3235298  PMID: 21428845
25.  Risk factors for revision due to infection after primary total hip arthroplasty 
Acta Orthopaedica  2010;81(5):542-547.
Background and purpose
There has been a limited amount of research on risk factors for revision due to infection following total hip arthroplasty (THA), probably due to low absolute numbers of revisions. We therefore studied patient- and surgery-related risk factors for revision due to infection after primary THA in a population-based setting.
Materials and methods
Using the Danish Hip Arthroplasty Registry, we identified 80,756 primary THAs performed in Denmark between Jan 1, 1995 and Dec 31, 2008. We used Cox regression analysis to compute crude and adjusted relative risk (RR) of revision due to infection. Revision was defined as extraction or exchange of any component due to infection. The median follow-up time was 5 (0–14) years.
Results
597 primary THAs (0.7%) were revised due to infection. Males, patients with any co-morbidity, patients operated due to non-traumatic avascular femoral head necrosis, and patients with long duration of surgery had an increased RR of revision due to infection within the total follow-up time. A tendency of increased RR of revision was found for patients who had received cemented THA without antibiotic and hybrid THA relative to patients with cementless implants. Hip diagnosis and fixation technique were not associated with risk of revision due to infection within 1 year of surgery (short-term risk).
Interpretation
We identified several categories of THA patients who had a higher risk of revision due to infection. Further research is required to explain the mechanism underlying this increased risk. More attention should be paid by clinicians to infection prevention strategies in patients with THA, particularly those with increased risk.
doi:10.3109/17453674.2010.519908
PMCID: PMC3214741  PMID: 20860453

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