Increased anterior pelvic tilt in patients with acetabular retroversion compared to the general population: A radiographic and prevalence study.

INTRODUCTION: The prevalence of acetabular retroversion is sparsely investigated. It may be associated with increased anterior pelvic tilt. The purpose of this study was to investigate whether patients with symptomatic and radiographically verified acetabular retroversion demonstrated increased anterior pelvic tilt compared to a control group, and furthermore to evaluate the prevalence of acetabular retroversion in the general population. METHODS: Anteroposterior pelvic radiographs in standing position of 111 patients with acetabular retroversion prior to anteverting periacetabular osteotomy (PAO) and 132 matched controls from the general Danish population were assessed. Pelvic tilt was assessed by the sacrococcygeal joint-symphysis distance and pelvic-tilt-ratio. Acetabular retroversion was defined as positive cross-over sign and posterior wall sign. Prior to assessments, interrater reliability analysis was performed. Measurements were agreed by two independent assessors. A nonparametric regression model was used to test between-group differences in median pelvic tilt. The prevalence was calculated as the ratio of subjects and hips with acetabular retroversion, respectively. RESULTS: The patient group had significantly larger median anterior pelvic tilt of 14.3 mm in sacrococcygeal joint-symphysis distance and -0.08 in pelvic-tilt-ratio, compared to controls. The prevalence of subjects in the general population with either unilateral or bilateral acetabular retroversion was 24% and 18% for all hips. CONCLUSION: Our data demonstrated that patients with symptomatic acetabular retroversion have increased anterior pelvic tilt compared to the general population. Radiographic sign of acetabular retroversion was highly prevalent in the general population. IMPLICATION FOR PRACTICE: Increased anterior pelvic tilt should be considered when diagnosing and treating patients with hip pain, as symptoms may be related to the functional position of the pelvis and not necessarily solely come from the radiographic verified acetabular retroversion.

Laminar airflow versus turbulent airflow in simulated total hip arthroplasty: measurements of colony-forming units, particles, and energy consumption.

BACKGROUND: The optimal type of ventilation in operating theatres for joint arthroplasty has been debated for decades. Recently, the World Health Organization changed its recommendations based on articles that have since been criticized. The economic and environmental impact of ventilation is also currently an important research topic but has not been well investigated. AIM: To compare how large, high-volume, laminar airflow (LAF) and turbulent airflow (TAF) ventilation systems perform during standardized simulated total hip arthroplasty (THA), as they pertain to colony-forming units (cfu), particle counts, and energy consumption. METHODS: Two identical operating theatres were used to perform simulated THA. The only difference was that one was equipped with LAF and the other with TAF. Cfu and particles were collected from key points in the operating theatre, and energy was measured for each simulation. Thirty-two simulations were done in total. FINDINGS: LAF had significantly reduced cfu and particle count when compared with TAF, at both 100% and 50% air influx. Furthermore, it was shown that lowering the air influx by 50% in LAF did not significantly affect cfu or particles, although reducing the fresh air influx from 100% to 50% significantly lowered the energy consumption. Most simulations in TAF did not meet the cleanroom requirements. CONCLUSION: Cfu were significantly lower in LAF at both 100% and 50% air influx. It is possible to reduce fresh air influx in LAF operating theatres by 50%, significantly reducing energy consumption, while still maintaining cfu and particle counts below the ISO classification threshold required for THA surgery.

Laminar airflow decreases microbial air contamination compared with turbulent ventilated operating theatres during live total joint arthroplasty: a nationwide survey.

BACKGROUND: Preventing surgical site infections and prosthetic joint infections is crucial for patient safety after total joint arthroplasty. Microbial air contamination has been suggested as a risk factor. Therefore, the ventilation system that will reduce air contamination most effectively in operating theatres (OTs) has been discussed. AIM: To determine whether laminar airflow (LAF) ventilation is superior to turbulent airflow (TAF) ventilation by looking at the colony forming units (cfu) count during live total hip and knee arthroplasties. Furthermore, to explore whether the number of OT personnel, door and cabinet lock openings and technical parameters of the ventilation systems have an impact on the number of cfu. METHODS: Active air sampling and passive sedimented bacterial load were performed in 17 OTs, equipped with either LAF or TAF ventilation, during 51 live surgeries while observations were noted. FINDINGS: LAF OTs reduced cfu counts compared with TAF OTs during live surgery (P<0.001). All LAF OTs provided ultraclean air whereas TAF had nine procedures exceeding the threshold of 10 cfu/m3. Door and cabinet lock openings and number of personnel did not influence the cfu count, while it decreased with increasing volume and total air change per hour (P<0.05). CONCLUSION: All LAF OTs had cfu counts within recommendations and provided lower cfu counts compared with TAF OTs. The number of OT personnel and total openings did not have an influence on cfu counts. Increased volume of the OT and total air change per hour showed a decrease in active cfu counts.

Effects of progressive resistance training prior to total HIP arthroplasty - a secondary analysis of a randomized controlled trial.

OBJECTIVE: To investigate 1-year postoperative effect of preoperative resistance training (RT) in patients undergoing total hip arthroplasty (THA) on patient-reported outcomes on activity and function and objective outcomes on muscle strength and physical performance. DESIGN: A 3-12 months follow-up of a randomized controlled trial. Patients scheduled for THA were randomized into: RT-group, twice a week for 10 weeks prior to THA, or 'care-as-usual' (CG). Primary endpoint of this sequel analysis is HOOS-ADL at 12 months follow-up. Secondary outcome measures are; other HOOS subscales, knee- and hip muscle strength plus function (gait, ascending/descending stairs, and sit-to-stand) at three and/or 12 months. CLINICALTRIALS.GOV: NCT01164111. RESULTS: Eighty patients (70% women, 70.4 ± 7.6 years, BMI of 27.8 ± 4.6) were randomized to RT (n = 40) or CG (n = 40); data from 85% were available at 12 months. No superior effects were observed at 12 months for HOOS ADL (between-group change score [95%CI]) (2.6 [-4.2; 9.8], P = 0.44) or remaining subscales. However, ascending (1.3 s [0.3; 2.3], P = 0.01)) and descending stairs (1.6 s [0.3; 2.9], P = 0.01) demonstrated additional effects. At 3 months clinically relevant change-scores in favour of RT was observed on HOOS-Sport/Rec (10.5 points [1.4; 19.6], P = 0.023), together with higher knee strength of the affected side (14.6 Nm [6.3; 22.9], P < 0.001), and selected outcomes of physical function. CONCLUSIONS: At 12 months after surgery, there was no additional effect of preoperative RT compared with THA alone, but rehabilitation was accelerated at 3 months.

Mismatch 'never events' in hip and knee arthroplasty: a cohort and intervention study.

AIMS: The aim of this study was to give estimates of the incidence of component incompatibility in hip and knee arthroplasty and to test the effect of an online, real-time compatibility check. MATERIALS AND METHODS: Intraoperative barcode registration of arthroplasty implants was introduced in Denmark in 2013. We developed a compatibility database and, from May 2017, real-time compatibility checking was implemented and became part of the registration. We defined four classes of component incompatibility: A-I, A-II, B-I, and B-II, depending on an assessment of the level of risk to the patient (A/B), and on whether incompatibility was knowingly accepted (I/II). RESULTS: A total of 26 524 arthroplasties were analyzed. From 12 307 procedures that were undertaken before implementation of the compatibility check, 21 class A incompatibilities were identified (real- or high-risk combinations; 0.17%; 95% confidence interval (CI) 0.11 to 0.26). From 5692 hip and 6615 knee procedures prior to implementation of the compatibility check, we found rates of class A-I incompatibility (real- or high-risk combinations unknowingly inserted) of 0.14% (95% CI 0.06 to 0.28) and 0.17% (95% CI 0.08 to 0.30), respectively. From 14 217 procedures after the introduction of compatibility checking (7187 hips and 7030 knees), eight class A incompatibilities (0.06%; 95% CI 0.02 to 0.11) were identified. This difference was statistically significant (p = 0.008). CONCLUSION: Our data presents validated estimates of the baseline incidence of incompatibility events for hip and knee arthroplasty procedures and shows that a significant reduction in class A incompatibility events is possible using a web-based recording system. Cite this article: Bone Joint J 2019;101-B:960-969.

Radiographic signs of acetabular retroversion using a low-dose slot-scanning radiographic system (EOS®).

INTRODUCTION: Acetabular retroversion is assessed using pelvic X-ray. Cross-over-sign (COS), posterior-wall-sign (PWS) and ischial-spine-sign (ISS) are important radiographic signs of the condition. The pelvic area is sensitive to radiation and thus, possibilities to reduce dose should be considered. The purpose was to compare radiographic signs of acetabular retroversion on conventional pelvic anteroposterior (AP) X-rays with a low-dose slot-scanning system (EOS) in a sample of patients with retroversion of the acetabulum and to compare the radiation doses. METHODS: 34 participants with radiographic signs of acetabular retroversion in one or both hips on conventional pelvic X-ray were consecutively recruited. Pelvic EOS-images were acquired in each patient and COS, PWS, ISS, COS-ratio and PWS-ratio was assessed. Radiation dose comparison of X-ray vs. EOS was performed using Dose-Area Products. RESULTS: Retroversion was present in 57 out of 68 hips. The absolute agreement was 91%, 84% and 76% for COS, PWS and ISS, respectively. No statistically significant differences were present between COS-ratio and PWS-ratio in either modality and Bland-Altman limits of agreement were narrow. The mean radiation dose was 1053 mGy*cm2 in X-ray and 593 mGy*cm2 in EOS (p = 0.003). CONCLUSION: The results indicate that pelvic EOS provides diagnostic qualities similar to conventional X-ray using 44% less radiation when radiographic signs of acetabular retroversion are assessed.

Changes in clavicle length in acute fractures within 3 weeks: a prospective ultrasonographic study of 59 patients.

BACKGROUND: Within traumatology a common indication for acute surgery of fractured clavicles is bone shortening over 2 cm. This indication is among but a few indications; which are recommended to be treated operatively within the very first weeks after a fracture. Theoretically clavicle fractures could become less shortened over time due to decreasing muscle pull. If this reduced shortening does indeed happen, some patients with initial bone shortening over 2 cm could perhaps be treated conservatively? However, it is unknown what happens to the length of the clavicle within the first weeks after a fracture. The aim of this study was to investigate if the length of the fresh fractured clavicles changes within the first three weeks. METHODS: Rested length measurements using navigation ultrasound were done on 59 patients with a fractured clavicle. Measurements were performed within the first three weeks after a lateral or mid-clavicular fracture. The inclusion period was from March 2014 to February 2016. Median age was 40 years and age range was 18-81 years. The data was analyzed using mixed linear models. RESULTS: The clavicle length showed no change within the first three weeks after fracture (p = 0.24). CONCLUSION: Fractured clavicles retain their length for the first three weeks.

Does hydroxyapatite coating of uncemented cups improve long-term survival? An analysis of 28,605 primary total hip arthroplasty procedures from the Nordic Arthroplasty Register Association (NARA).

OBJECTIVE: It is unclear whether hydroxyapatite (HA) coating of uncemented cups used in primary total hip arthroplasty (THA) improves bone ingrowth and reduces the risk of aseptic loosening. We therefore investigated survival of different uncemented cups that were available with or without HA coating. METHOD: We investigated three different cup types used with or without HA coating registered in the Nordic Arthroplasty Register Association (NARA) database that were inserted due to osteoarthritis (n = 28,605). Cumulative survival rates and adjusted hazard ratios (HRs) for the risk of revision were calculated. RESULTS: Unadjusted 13-year survival for cup revision due to aseptic loosening was 97.9% (CI: 96.5-99.4) for uncoated and 97.8% (CI: 96.3-99.4) for HA-coated cups. Adjusted HRs were 0.66 (CI 0.42-1.04) for the presence of HA coating during the first 10 years and 0.87 (CI 0.14-5.38) from year 10-13, compared with uncoated cups. When considering the endpoint cup revision for any reason, unadjusted 13-year survival was similar for uncoated (92.5% [CI: 90.1-94.9]) and HA-coated (94.7% [CI: 93.2-96.3]) cups. The risk of revision of any component due to infection was higher in THA with HA-coated cups than in THA with uncoated cups (adjusted HR 1.4 [CI 1.1-1.9]). CONCLUSIONS: HA-coated cups have a similar risk of aseptic loosening as uncoated cups, thus the use of HA coating seems to not confer any added value in terms of implant stability. The risk of infection seemed higher in THA with use of HA-coated cups, an observation that must be investigated further.

One-year incidence of prosthetic joint infection in total hip arthroplasty: a cohort study with linkage of the Danish Hip Arthroplasty Register and Danish Microbiology Databases.

OBJECTIVE: To examine the trend of Prosthetic Joint Infections (PJI) following primary total hip arthroplasty (THA) and the antimicrobial resistance of the bacteria causing these infections. MATERIALS AND METHODS: We identified a population-based cohort of patients in the Danish Hip Arthroplasty Register (DHR) who had primary THA and received their surgery in Jutland or Funen between 2005 and 2014. We followed the patients until revision, emigration, death, or up to 1-year of follow-up. Data from the DHR were combined with those from microbiology databases, the National Register of Patients, and the Civil Registration System. We estimated the cumulative 1-year incidence of PJI for two 5-year periods; 2005-2009 and 2010-2014. The hazard ratio of PJI as a measure of relative risk after adjusting for multiple risk factors was calculated. RESULTS: Of 48,867 primary THAs identified, 1120 underwent revision within 1 year. Of these, 271 were due to PJI. The incidence of PJI was 0.53% (95% confidence interval (CI): 0.44; 0.63) during 2005-2009 and 0.57% (95% CI: 0.49; 0.67) during 2010-2014. The adjusted relative risk was 1.05 (95% CI: 0.82; 1.34) for the 2010-2014 period vs the 2005-2009 period. The most common micro-organisms identified in the 271 PJI were Staphylococcus aureus (36%) and coagulase-negative staphylococci (CoNS) (33%); others commonly identified included Enterobacteriaceae, enterococci, and streptococci. Antimicrobial resistance to beta-lactams and gentamicin did not change during the study period. CONCLUSION: The risk of PJI within 1-year after primary THA and the antimicrobial resistance of the most prevalent bacteria remained unchanged during the 2005-2014 study period.

Validation of the diagnosis 'prosthetic joint infection' in the Danish Hip Arthroplasty Register.

AIMS: The purpose of this study was to validate the diagnosis of periprosthetic joint infection (PJI) in the Danish Hip Arthroplasty Register (DHR). PATIENTS AND METHODS: We identified a cohort of patients from the DHR who had undergone primary total hip arthroplasty (THA) since 1 January 2005 and followed them until first-time revision, death, emigration or until 31 December 2012. Revision for PJI, as registered in the DHR, was validated against a benchmark which included information from microbiology databases, prescription registers, clinical biochemistry registers and clinical records. We estimated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for PJI in the DHR alone and in the DHR when combined with microbiology databases. RESULTS: In total, 1382 of the 37 826 primary THAs in the DHR were registered as having been revised for any cause once 26 patients with errors in registration had been excluded: 232 of these were for PJI. For this group, the sensitivity was 67%, specificity 95%, PPV 77%, and NPV 92%. Combining the data from the DHR with those from microbiology databases increased the sensitivity to 90% and also improved specificity (100%), PPV (98%) and NPV (98%). CONCLUSION: Only two thirds of revisions for PJI were captured in the DHR and only 77% of the PJI reported to the DHR could be confirmed to be infected. TAKE HOME MESSAGE: combining the data from the DHR with those from microbiology databases substantially improved the validity of the diagnosis of PJI and should enable future register-based studies.

Preoperative progressive explosive-type resistance training is feasible and effective in patients with hip osteoarthritis scheduled for total hip arthroplasty--a randomized controlled trial.

OBJECTIVE: To investigate the efficacy and feasibility of progressive explosive-type resistance training (RT) in patients with osteoarthritis (OA) of the hip scheduled for total hip arthroplasty (THA). METHOD: Randomized controlled trial (1:1) in patients diagnosed with hip OA and scheduled for THA. The intervention group (IG) performed supervised preoperative progressive explosive-type RT twice a week for 10 weeks; four exercises (hip/thigh) performed in three series each (8-12 repetition maximum). The control group (CG) received 'care as usual'. Efficacy was reported as the between-group difference in the Hip Osteoarthritis Outcome Score (HOOS) (primary endpoint; ADL function), and leg muscle power at post intervention follow-up immediate before surgery. Intention-to-treat analyses were performed in a multilevel regression model adjusting for baseline, sex, age and weight. Feasibility was reported as adherence, exercise related pain and adverse effects. Post-surgical follow up will be reported separately. ClinicalTrials.gov registration: NCT01164111. RESULTS: Eighty patients (age 70.4 ± 7.6 years, BMI 27.8 ± 4.6, 52 females (65%) were included. Adherence was high (93%) with acceptable exercise related pain (VAS score ≤ 5) reported in 83% of sessions and no adverse events. Changes in HOOS 'function' was 10.0 points 95%CI [4.7; 15.3] higher in IG compared to CG (P < 0.001). For all the remaining HOOS subscales IG scored significantly better (P < 0.03) and had higher leg extension muscle power (P < 0.0001) compared to CG. CONCLUSION: Progressive explosive-type RT was feasible in the included group of hip OA patients scheduled for THA and resulted in significant improvement in self-reported outcomes and increased leg muscle power.

Sensitivity and specificity of CT- and MRI-scanning in evaluation of occult fracture of the proximal femur.

OBJECTIVE: To estimate sensitivity and specificity of CT and MRI examinations in patients with fractures of the proximal femur. To determine the interobserver agreement of the modalities among a senior consulting radiologist, a resident in radiology and a resident in orthopaedics surgery. MATERIALS AND METHODS: 67 patients (27 males, 40 females, mean age 80.5) seen in the emergency room with hip pain after fall, inability to stand and a primary X-ray without fracture were evaluated with both CT and MRI. The images were analysed by a senior consulting musculoskeletal radiologist, a resident in radiology and a resident in orthopaedic surgery. Sensitivity and specificity were estimated with MRI as the golden standard. Kappa value was used to assess level of agreement in both MRI and CT finding. RESULTS: 15 fractures of the proximal femur were found (7 intertrochanteric-, 3 femoral neck and 5 fractures of the greater trochanter). Two fractures were not identified by CT and four changed fracture location. Among those, three patients underwent surgery. Sensitivity of CT was 0.87; 95% CI [0.60; 0.98]. Kappa for interobserver agreement for CT were 0.46; 95% CI [0.23; 0.76] and 0.67; 95% CI [0.42; 0.90]. For MRI 0.67; 95% CI [0.43; 0.91] and 0.69; 95% CI [0.45; 0.92]. CONCLUSION: MRI was observed to have a higher diagnostic accuracy than CT in detecting occult fractures of the hip. Interobserver analysis showed high kappa values corresponding substantial agreement in both CT and MRI.

Uptake and depuration of gold nanoparticles in Daphnia magna.

This study presents a series of short-term studies (total duration 48 h) of uptake and depuration of engineered nanoparticles (ENP) in neonate Daphnia magna. Gold nanoparticles (Au NP) were used to study the influence of size, stabilizing agent and feeding on uptake and depuration kinetics and animal body burdens. 10 and 30 nm Au NP with different stabilizing agents [citrate (CIT) and mercaptoundecanoic acid (MUDA)] were tested in concentrations around 0.5 mg Au/L. Fast initial uptake was observed for all studied Au NP, with CIT stabilized Au NP showing similar rates independent of size and MUDA showing increased uptake for the smaller Au NP (MUDA 10 nm > CIT 10 nm, 30 nm > MUDA 30 nm). However, upon transfer to clean media no clear trend on depuration rates was found in terms of stabilizing agent or size. Independent of stabilizing agent, 10 nm Au NP resulted in higher residual whole-animal body burdens after 24 h depuration than 30 nm Au NP with residual body burdens about one order of magnitude higher of animals exposed to 10 nm Au NP. The presence of food (P. subcapitata) did not significantly affect the body burden after 24 h of exposure, but depuration was increased. While food addition is not necessary to ensure D. magna survival in the presented short-term test design, the influence of food on uptake and depuration kinetics is essential to consider in long term studies of ENP where food addition is necessary. This study demonstrates the feasibility of a short-term test design to assess the uptake and depuration of ENP in D. magna. The findings underlines that the assumptions behind the traditional way of quantifying bioconcentration are not fulfilled when ENPs are studied.

The risk of venous thromboembolism, myocardial infarction, stroke, major bleeding and death in patients undergoing total hip and knee replacement: a 15-year retrospective cohort study of routine clinical practice.

We examined the risk of thrombotic and major bleeding events in patients undergoing total hip and knee replacement (THR and TKR) treated with thromboprophylaxis, using nationwide population-based databases. We identified 83 756 primary procedures performed between 1997 and 2011. The outcomes were symptomatic venous thromboembolism (VTE), myocardial infarction (MI), stroke, death and major bleeding requiring hospitalisation within 90 days of surgery. A total of 1114 (1.3%) and 483 (0.6%) patients experienced VTE and bleeding, respectively. The annual risk of VTE varied between 0.9% and 1.6%, and of bleeding between 0.4% and 0.8%. The risk of VTE and bleeding was unchanged over a 15-year period. A total of 0.7% of patients died within 90 days, with a decrease from 1% in 1997 to 0.6% in 2011 (p < 0.001). A high level of comorbidity and general anaesthesia were strong risk factors for both VTE and bleeding, with no difference between THR and TKR patients. The risk of both MI and stroke was 0.5%, which remained unchanged during the study period. In this cohort study of patients undergoing THR and TKR patients in routine clinical practice, approximately 3% experienced VTE, MI, stroke or bleeding. These risks did not decline during the 15-year study period, but the risk of dying fell substantially.

Association between fixation technique and revision risk in total hip arthroplasty patients younger than 55 years of age. Results from the Nordic Arthroplasty Register Association.

OBJECTIVES: To evaluate implant survival following primary total hip replacement (THR) in younger patients. To describe the diversity in use of cup-stem implant combinations. DESIGN: 29,558 primary THRs osteoarthritis (OA) patients younger than 55 years of age performed from 1995 through 2011 were identified using the Nordic Arthroplasty Registry Association database. We estimated adjusted relative risk (aRR) of revision with 95% confidence interval (CI) using Cox regression. RESULTS: In general, no difference was observed between uncemented and cemented implants in terms of risk of any revision. Hybrid implants were associated with higher risk of any revision (aRR = 1.3, CI: 1.1-1.5). Uncemented implants led to a reduced risk of revision due to aseptic loosening (aRR = 0.5, CI: 0.5-0.6), whereas the risk was similar for hybrid and cemented implants. Compared with cemented implants, both uncemented and hybrid implants led to elevated risk of revision due to other causes, as well as elevated risk of revision due to any reason within 2 years. 183 different uncemented cup-stem implant combinations were registered in Denmark, of these, 172 were used in less than 100 operations which is similar to Norway, Sweden and Finland. CONCLUSIONS: Uncemented implants perform better in relation to long-term risk of aseptic loosening, whereas both uncemented and hybrid rather than cemented implants in patients younger than 55 years had more short-term revisions because problems due to dislocation, periprosthetic fracture and infection has not yet been completely solved. The vast majority of cup-stem combinations were used in very few operations.

Patient education with or without manual therapy compared to a control group in patients with osteoarthritis of the hip. A proof-of-principle three-arm parallel group randomized clinical trial.

OBJECTIVE: To investigate the effectiveness of a patient education (PE) program with or without the added effect of manual therapy (MT) compared to a minimal control intervention (MCI). METHODS: In a single-center university hospital setting, a total of 118 patients with clinical and radiographic unilateral hip osteoarthritis (OA) from primary care were randomized into one of three groups: PE, PE plus MT or MCI. The PE was taught by a physiotherapist involving five sessions. The MT was delivered by a chiropractor involving 12 sessions and the MCI included a home stretching program. Primary outcome was self-reported pain severity on an 11-box numeric rating scale (NRS) immediately following a 6-week intervention period. Patients were followed for 1 year. RESULTS: Primary analysis included 111 patients (94%). In the combined group (PE + MT), a clinically relevant reduction in pain severity compared to the MCI of 1.90 points (95% confidence interval (CI) 0.9-2.9) was achieved. Effect size (Cohen's d) for the PE + MT minus the MCI was 0.92 (95% CI 0.41-1.42). Number needed to treat for PE + MT was 3 (95% CI 2-7). No difference was found between the PE and MCI groups, with mean difference 0.0 (95% CI -1.0 to 1.0). At 12 months, not including patients receiving hip surgery the statistically significant difference favoring PE + MT was maintained. CONCLUSIONS: For primary care patients with OA of the hip, a combined intervention of MT and PE was more effective than a MCI. PE alone was not superior to the MCI. TRIAL REGISTRATION: clinicaltrials.govNCT01039337.

Early micromovement of the Articular Surface Replacement (ASR) femoral component: two-year radiostereometry results.

Radiostereometric analysis (RSA) can detect early micromovement in unstable implant designs which are likely subsequently to have a high failure rate. In 2010, the Articular Surface Replacement (ASR) was withdrawn because of a high failure rate. In 19 ASR femoral components, the mean micromovement over the first two years after implantation was 0.107 mm (SD 0.513) laterally, 0.055 mm (SD 0.204) distally and 0.150 mm (SD 0.413) anteriorly. The mean backward tilt around the x-axis was -0.08° (SD 1.088), mean internal rotation was 0.165° (SD 0.924) and mean varus tilt 0.238° (SD 0.420). The baseline to two-year varus tilt was statistically significant from zero movement, but there was no significant movement from one year onwards. We conclude that the ASR femoral component achieves initial stability and that early migration is not the mode of failure for this resurfacing arthroplasty.

Changes in bone mineral density of the acetabulum, femoral neck and femoral shaft, after hip resurfacing and total hip replacement: two-year results from a randomised study.

It is accepted that resurfacing hip replacement preserves the bone mineral density (BMD) of the femur better than total hip replacement (THR). However, no studies have investigated any possible difference on the acetabular side. Between April 2007 and March 2009, 39 patients were randomised into two groups to receive either a resurfacing or a THR and were followed for two years. One patient's resurfacing subsequently failed, leaving 19 patients in each group. Resurfaced replacements maintained proximal femoral BMD and, compared with THR, had an increased bone mineral density in Gruen zones 2, 3, 6, and particularly zone 7, with a gain of 7.5% (95% confidence interval (CI) 2.6 to 12.5) compared with a loss of 14.6% (95% CI 7.6 to 21.6). Resurfacing replacements maintained the BMD of the medial femoral neck and increased that in the lateral zones between 12.8% (95% CI 4.3 to 21.4) and 25.9% (95% CI 7.1 to 44.6). On the acetabular side, BMD was similar in every zone at each point in time. The mean BMD of all acetabular regions in the resurfaced group was reduced to 96.2% (95% CI 93.7 to 98.6) and for the total hip replacement group to 97.6% (95% CI 93.7 to 101.5) (p = 0.4863). A mean total loss of 3.7% (95% CI 1.0 to 6.5) and 4.9% (95% CI 0.8 to 9.0) of BMD was found above the acetabular component in W1 and 10.2% (95% CI 0.9 to 19.4) and 9.1% (95% CI 3.8 to 14.4) medial to the implant in W2 for resurfaced replacements and THRs respectively. Resurfacing resulted in a mean loss of BMD of 6.7% (95% CI 0.7 to 12.7) in W3 but the BMD inferior to the acetabular component was maintained in both groups. These results suggest that the ability of a resurfacing hip replacement to preserve BMD only applies to the femoral side.

Translation, cross-cultural adaptation and validation of the Danish version of the Oxford hip score: Assessed against generic and disease-specific questionnaires.

OBJECTIVES: The Oxford hip score (OHS) is a 12-item questionnaire designed and developed to assess function and pain from the perspective of patients who are undergoing total hip replacement (THR). The OHS has been shown to be consistent, reliable, valid and sensitive to clinical change following THR. It has been translated into different languages, but no adequately translated, adapted and validated Danish language version exists. METHODS: The OHS was translated and cross-culturally adapted into Danish from the original English version, using methods based on best-practice guidelines. The translation was tested for psychometric quality in patients drawn from a cohort from the Danish Hip Arthroplasty Register (DHR). RESULTS: The Danish OHS had a response rate of 87.4%, no floor effect and a 19.9% ceiling effect (as expected in post-operative patients). Only 1.2% of patients had too many items missing to calculate a sum score. Construct validity was adequate and 80% of our predefined hypotheses regarding the correlation between scores on the Danish OHS and the other questionnaires were confirmed. The intraclass correlation (ICC) of the different items ranged from 0.80 to 0.95 and the average limits of agreement (LOA) ranged from -0.05 to 0.06. The Danish OHS had a high internal consistency with a Cronbach's alpha of 0.99 and an average inter-item correlation of 0.88. CONCLUSIONS: This Danish version of the OHS is a valid and reliable patient-reported outcome measurement instrument (PROM) with similar qualities to the original English language version.