Longitudinal changes in patient-reported outcome measures following total hip arthroplasty and predictors of deterioration during follow-up: a seven-year prospective international multicentre study.

AIMS: The primary aim of this study was to quantify the improvement in patient-reported outcome measures (PROMs) following total hip arthroplasty (THA), as well as the extent of any deterioration through the seven-year follow-up. The secondary aim was to identify predictors of PROM improvement and deterioration. PATIENTS AND METHODS: A total of 976 patients were enrolled into a prospective, international, multicentre study. Patients completed a battery of PROMs prior to THA, at three months post-THA, and at one, three, five, and seven-years post-THA. The Harris Hip Score (HHS), the 36-Item Short-Form Health Survey (SF-36) Physical Component Summary (PCS), the SF-36 Mental Component Summary (MCS), and the EuroQol five-dimension three-level (EQ-5D) index were the primary outcomes. Longitudinal changes in each PROM were investigated by piece-wise linear mixed effects models. Clinically significant deterioration was defined for each patient as a decrease of one half of a standard deviation (group baseline). RESULTS: Improvements were noted in each PROM between the preoperative and one-year visits, with one-year values exceeding age-matched population norms. Patients with difficulty in self-care experienced less improvement in HHS (odds ratio (OR) 2.2; p = 0.003). Those with anxiety/depression experienced less improvement in PCS (OR -3.3; p = 0.002) and EQ-5D (OR -0.07; p = 0.005). Between one and seven years, obesity was associated with deterioration in HHS (1.5 points/year; p = 0.006), PCS (0.8 points/year; p < 0.001), and EQ-5D (0.02 points/year; p < 0.001). Preoperative difficulty in self-care was associated with deterioration in HHS (2.2 points/year; p < 0.001). Preoperative pain from other joints was associated with deterioration in MCS (0.8 points/year; p < 0.001). All aforementioned factors were associated with clinically significant deterioration in PROMs (p < 0.035), except anxiety/depression with regard to PCS (p = 0.060). CONCLUSION: The present study finds that patient factors affect the improvement and deterioration in PROMs over the medium term following THA. Special attention should be given to patients with risk factors for decreased PROMs, both preoperatively and during follow-up. Cite this article: Bone Joint J 2019;101-B:768-778.

Evaluation of vitamin E-diffused highly crosslinked polyethylene wear and porous titanium-coated shell stability: a seven-year randomized control trial using radiostereometric analysis.

AIMS: Vitamin E-diffused, highly crosslinked polyethylene (VEPE) and porous titanium-coated (PTC) shells were introduced in total hip arthroplasty (THA) to reduce the risk of aseptic loosening. The purpose of this study was: 1) to compare the wear properties of VEPE to moderately crosslinked polyethylene; 2) to assess the stability of PTC shells; and 3) to report their clinical outcomes at seven years. PATIENTS AND METHODS: A total of 89 patients were enrolled into a prospective study. All patients received a PTC shell and were randomized to receive a VEPE liner (n = 44) or a moderately crosslinked polyethylene (ModXLPE) liner (n = 45). Radiostereometric analysis (RSA) was used to measure polyethylene wear and component migration. Differences in wear were assessed while adjusting for body mass index, activity level, acetabular inclination, anteversion, and head size. Plain radiographs were assessed for radiolucency and patient-reported outcome measures (PROMs) were administered at each follow-up. RESULTS: In total, 73 patients (82%) completed the seven-year visit. Mean seven-year linear proximal penetration was -0.07 mm (sd 0.16) and 0.00 mm (sd 0.22) for the VEPE and ModXLPE cohorts, respectively (p = 0.116). PROMs (p = 0.310 to 0.807) and radiolucency incidence (p = 0.330) were not different between the polyethylene cohorts. The mean proximal shell migration rate was 0.04 mm per year (sd 0.09). At seven years, patients with radiolucency (34%) demonstrated greater migration (mean difference: 0.6 mm (sd 0.2); p < 0.001). PROMs were lower for patients with radiolucency and greater proximal migration (p = 0.009 to p = 0.045). No implants were revised for aseptic loosening. CONCLUSION: This is the first randomized controlled trial to report seven-year RSA results for VEPE. All wear rates were below the previously reported osteolysis threshold (0.1 mm per year). PTC shells demonstrated acceptable primary stability through seven years, as indicated by low migration and lack of aseptic loosening. However, patients with acetabular radiolucency were associated with higher shell migration and lower PROM scores. Cite this article: Bone Joint J 2019;101-B:760-767.

Evaluation of in vivo wear of vitamin E-diffused highly crosslinked polyethylene at five years: a multicentre radiostereometric analysis study.

AIMS: The primary aim of this study was to compare the wear properties of vitamin E-diffused, highly crosslinked polyethylene (VEPE) and one formulation of moderately crosslinked and mechanically annealed ultra-high molecular weight polyethylene (ModXLPE) in patients five years after primary total hip arthroplasty (THA). The secondary aim was to assess the clinical results of patients treated with VEPE by evaluating patient-reported outcome measures (PROMs), radiological evidence of fixation, and the incidence of mechanical failure. PATIENTS AND METHODS: A total of 208 patients (221 THAs) from four international centres were recruited into a prospective study involving radiostereometric analysis (RSA) and the assessment of clinical outcomes. A total of 193 hips (87%) were reviewed at the five-year follow-up. Of these, 136 (70%) received VEPE (vs ModXLPE) liners and 68 (35%) received ceramic (vs metal) femoral heads. PROMs and radiographs were collected preoperatively and at one, two, and five years postoperatively. In addition, RSA images were collected to measure PE wear postoperatively and at one, two, and five years after surgery. RESULTS: We observed similar bedding in one year postoperatively and wear two years postoperatively between the two types of liner. However, there was significantly more penetration of the femoral head in the ModXLPE cohort compared with the VEPE cohort five years postoperatively (p < 0.001). The only variables independently predictive of increased wear were ModXLPE (vs VEPE) liner type (ß = 0.22, p = 0.010) and metal (vs ceramic) femoral head (ß = 0.21, p = 0.013). There was no association between increased wear and the development of radiolucency (p = 0.866) or PROMs. No patient had evidence of osteolysis. CONCLUSION: Five years postoperatively, patients with VEPE (vs ModXLPE) and ceramic (vs metal) femoral heads had decreased wear. The rates of wear for both liners were very low and have not led to any osteolysis or implant failure due to aseptic loosening.

Vitamin E diffused highly cross-linked polyethylene in total hip arthroplasty at five years: a randomised controlled trial using radiostereometric analysis.

AIMS: The objective of this five-year prospective, blinded, randomised controlled trial (RCT) was to compare femoral head penetration into a vitamin E diffused highly cross-linked polyethylene (HXLPE) liner with penetration into a medium cross-linked polyethylene control liner using radiostereometric analysis. PATIENTS AND METHODS: Patients scheduled for total hip arthroplasty (THA) were randomised to receive either the study E1 (32 patients) or the control ArComXL polyethylene (35 patients). The median age (range) of the overall cohort was 66 years (40 to 76). RESULTS: The five-year median (interquartile range) proximal femoral head penetration into the E1 was -0.05 mm (-0.13 to -0.02) and 0.07 mm (-0.03 to 0.16) for ArComXL. At three and five years, the penetration was significantly greater in the ArComXL group compared with the E1 group (p = 0.029 and p = 0.019, respectively). All patient-reported outcomes (PROs) improved significantly from the pre-operative interval compared with those at one year, and remained favourable at five years. There were no differences between the two groups at any interval. CONCLUSION: The five-year results showed that E1 polyethylene does not wear more than the control, ArComXL. This is the longest-term RCT comparing the wear performance and clinical outcome of vitamin E diffused HXLPE with a previous generation of medium cross-linked polyethylene. Cite this article: Bone Joint J 2017;99-B:577-84.

Mid-term changes in blood metal ion levels after Articular Surface Replacement arthroplasty of the hip.

AIMS: Our first aim was to determine whether there are significant changes in the level of metal ions in the blood at mid-term follow-up, in patients with an Articular Surface Replacement (ASR) arthroplasty. Secondly, we sought to identify risk factors for any increases. PATIENTS AND METHODS: The study involved 435 patients who underwent unilateral, metal-on-metal (MoM) hip resurfacing (HRA) or total hip arthroplasty (THA). These patients all had one measurement of the level of metal ions in the blood before seven years had passed post-operatively (early evaluation) and one after seven years had passed post-operatively (mid-term evaluation). Changes in ion levels were tested using a Wilcoxon signed-rank test. We identified subgroups at the highest risk of increase using a multivariable linear logistic regression model. RESULTS: There were significant increases in the levels of metal ions for patients who underwent both MoM HRA (Chromium (Cr): 0.5 parts per billion (ppb); Cobalt (Co): 1.1 ppb) and MoM THA (Cr: 0.5 ppb; Co: 0.7 ppb). In a multivariable model considering MoM HRAs, the change in the levels of metal ions was influenced by female gender (Co: Odds Ratio (OR) 1.42; p = 0.002 and Cr: OR 1.08; p = 0.006). The change was found to be irrespective of the initial level for the MoM HRAs, whereas there was a negative relationship between the initial level and the change in the level for those with a MoM THA (Co: OR -0.43; p < 0.001 and Cr: OR -0.14; p = 0.033). CONCLUSION: The levels of metal ions in the blood increase significantly over the period until mid-term follow-up in patients with both a MoM HRA and those with a MoM THA. We recommend that the levels of metal ions be measured most frequently for women with a MoM HRA. While those with a MoM THA appear to stabilise at a certain level, the accuracy of this trend is not yet clear. Vigilant follow-up is still recommended. Cite this article: Bone Joint J 2017;99-B(4 Supple B):33-40.

A Fully Functional Drug-Eluting Joint Implant.

Despite advances in orthopedic materials, the development of drug-eluting bone and joint implants that can sustain the delivery of the drug and maintain the necessary mechanical strength in order to withstand loading has remained elusive. Here, we demonstrate that modifying the eccentricity of drug clusters and the percolation threshold in ultrahigh molecular weight polyethylene (UHMWPE) results in maximized drug elution and in the retention of mechanical strength. The optimized UHMWPE eluted antibiotic at a higher concentration for longer than the clinical gold standard antibiotic-eluting bone cement while retaining the mechanical and wear properties of clinically used UHMWPE joint prostheses. Treatment of lapine knees infected with Staphylococcus aureus with the antibiotic-eluting UHMWPE led to complete bacterial eradication and to the absence of detectable systemic effects. We argue that the antibiotic-eluting UHMWPE joint implant is a promising candidate for clinical trials.

The use of patient-reported outcomes after routine arthroplasty: beyond the whys and ifs.

The limitations and benefits of patient-reported outcome measures, in defining the merits of arthroplasty surgery, are discussed.

Variables determining outcome in total hip replacement surgery.

In this study we hypothesised that anxiety/depression, one of five dimensions in the health-related quality of life (HRQoL) measurement tool EQ-5D, could predict outcome after total hip replacement surgery. Pre-operative and one-year post-operative data from the Swedish Hip Arthroplasty Register, including 6158 patients with primary osteoarthritis of the hip, were analysed. In order to examine the association between anxiety and outcome with respect to pain and satisfaction an analysis of covariance was used. The pre-operative EQ-5D anxiety/depression dimension was a strong predictor for pain relief and patient satisfaction (p < 0.001). Orthopaedic surgeons involved in the care of patients eligible for total hip replacement surgery should be aware that mental health may influence post-operative pain and HRQoL. An appropriate assessment of mental health may enable a modification in the way these patients are managed in order to optimise the outcome after joint replacement surgery.

Incidence of surgically treated osteoarthritis in the hip and knee in male construction workers.

OBJECTIVE: Occupational workload has been associated with an increased risk of osteoarthritis. The objective was to further examine the association between workload and occurrence of osteoarthritis and in particular to study whether heavy workload has similar importance as a causative factor for osteoarthritis of the hip and knee. METHODS: In a cohort study, the authors investigated the incidence of surgically treated osteoarthritis in the hip and knee among men employed in the Swedish construction industry (n = 204 741). Incident cases were found by linkage with the Swedish hospital discharge register between 1987 and 1998. Incidence rates adjusted for age and BMI were compared between different occupational groups. RESULTS: The incidence rates for osteoarthritis in hip and knee were positively correlated (r = 0.62; p = 0.01). There was a significantly increased risk of surgically treated osteoarthritis in the knee among floor layers, asphalt workers, sheet-metal workers, rock workers, plumbers, brick layers, wood workers and concrete workers. Even if there was a trend towards increased relative risks for osteoarthritis in the hip in floor layers, asphalt workers, wood workers and concrete workers they were not statistically significant. The relative risk for surgically treated osteoarthritis of the knee was 4.7 (95% CI 1.8 to 12.3) among floor layers, indicating an attributable fraction for work factors of 79%. CONCLUSIONS: This study shows that some work-related factors seem to be risk factors for osteoarthritis both in the knee and hip. However, the risk factors seem to be of greater importance for osteoarthritis in the knee compared with the hip. This study indicates that at least 50% of the cases of severe osteoarthritis of the knee can be prevented through decreasing occupational risk factors in some occupational groups.

The excess mortality due to periprosthetic femur fracture. A study from the Swedish national hip arthroplasty register.

A rare but serious adverse event of total hip replacement (THR) is periprosthetic femoral fracture. The aim of the present study was to assess whether there was an excess mortality due to such a fracture and to estimate the probability of death caused by the fracture. We studied primary total hip replacement in 27,652 men and 35,930 women with osteoarthritis from The Swedish National Hip Arthroplasty Register operated from 1979 to 2000. From the same register we also studied 392 men and 344 women with periprosthetic fracture from 1979 to 2000, all with osteoarthritis as the primary diagnosis. By the special method applied, it was possible to perform the estimation of death due to the fracture event though we could not determine in the individual case whether the fracture caused the death. Compared to the total population of patients operated with a primary THR there was a higher mortality rate immediately after the surgery for patients with periprosthetic fracture and in the longer run for patients below the age of 70 years. At the age of 70 years the estimated probability of death due to the fracture was 2.1% for men and 1.2% for women. At the age of 80 years at fracture the corresponding probabilities were 3.9% and 2.2% for men and women, respectively.

Risk factors for failure after treatment of a periprosthetic fracture of the femur.

Periprosthetic fracture of the femur is an uncommon complication after total hip replacement, but appears to be increasing. We undertook a nationwide observational study to determine the risk factors for failure after treatment of these fractures, examining patient- and implant-related factors, the classification of the fractures and the outcome. Between 1979 and 2000, 1049 periprosthetic fractures of the femur were reported to the Swedish National Hip Arthroplasty Register. Of these, 245 had a further operation after failure of their initial management. Data were collected from the Register and hospital records. The material was analysed by the use of Poisson regression models. It was found that the risk of failure of treatment was reduced for Vancouver type B2 injuries (p = 0.0053) if revision of the implant was undertaken (p = 0.0033) or revision and open reduction and internal fixation (p = 0.0039) were performed. Fractures classified as Vancouver type B1 had a significantly higher risk of failure (p = 0.0001). The strongest negative factor was the use of a single plate for fixation (p = 0.001). The most common reasons for failure in this group were loosening of the femoral prosthesis, nonunion and re-fracture. It is probable that many fractures classified as Vancouver type B1 (n = 304), were in reality type B2 fractures with a loose stem which were not recognised. Plate fixation was inadequate in these cases. The difficulty in separating type B1 from type B2 fractures suggests that the prosthesis should be considered as loose until proven otherwise.

An electronic database for outcome studies that includes digital radiographs.

We report on acquisition of key data from the clinical medical record, surgical data, radiologic studies, and patient surveys for a novel digital total hip arthroplasty (THA) registry that includes electronic capture of digital radiographic images into a database on an internet platform for query. We now have the ability to collect demographic and operative data, including the operative note, discharge summary, surgery data, and Digital Imaging Communications in Medicine (DICOM) radiology images. Steps are being completed to assemble office encounters, hospital procedural codes, and implant bar codes. Two examples include a THA surgery record and a THA outcome study with plain radiograph set. Analysis of such data could suggest ways to improve clinical practice.

Outcome of total hip replacement: a comparison of different measurement methods.

During the past 40 years, improvements have been made in the technique, implant, and surgical environment for total hip replacement, which today is one of the most cost-effective operations done. The aim of this study was to compare different outcome measurement methods and to develop recommendations for optimal followup of total hip replacement. The study involved the outcome of 2604 randomly selected patients in Sweden treated surgically with a modern technique. General questionnaires (the Medical Outcomes Study 36-Item Short-Form Health Survey and the Nottingham Health Profile) were compared with disease-specific questionnaires (the Western Ontario and McMaster University Osteoarthritis Index and the Harris hip score). The study showed a good correlation between the studied questionnaires, and all questionnaires used could be suitable for followup study after hip replacement surgery. In clinical practice and for research, a general and disease-specific self-administered score should be used. Some patients (older and low cerebral capacity) have difficulties answering questions on these questionnaires. A new short self-administered general and disease-specific questionnaire was designed: the Total Hip Replacement score. The Total Hip Replacement score provides information about the result of the hip arthroplasty, and the results can be compared with results of other surgical interventions.

Correlation of wear debris-induced osteolysis and revision with volumetric wear-rates of polyethylene: a survey of 8 reports in the literature.

This survey focused on clinical reports of polyethylene wear and osteolysis in total hip replacements. With regard to documentation of clinical wear-rates, 57 publications were reduced to an analysis of 8 reports of THR series, including the incidence of osteolysis. A direct correlation was found among volumetric wear-rates, incidence of osteolysis and revision rates in THR concepts of the 1983-1987 era. As volumetric wear rate increased, the incidence of osteolysis and revision rates increased. With regard to our grading system for volumetric wear, with follow-up in the 4-15 year range, osteolysis was rare in group A (wear = 0-80 mm3/year), ranging from 6% to 31% in group B (wear 40-80 mm3/year) and from 21% to 100% in group C (wear > 140 mm3/year). With regard to cup design, the optimal low-wear group had mainly cemented polyethylene cups with 22 and 28 mm head sizes. The mid-wear group B had metal-backed cemented and uncemented cups, with 28 mm head size, and the high-risk group C had only uncemented, metal-backed cups, with the highest wear in the 32 mm head size. Less than 10 years of follow-up did not distinguish adequately between different designs of THR, except in a few cases which had early failures due to material or design deficiencies. Overall, the cemented all-polyethylene cup combined with the smaller ball head proved to be better.

Outcome after total hip arthroplasty: Part II. Disease-specific follow-up and the Swedish National Total Hip Arthroplasty Register.

The Swedish National Total Hip Arthroplasty Register records primary hip replacements, revisions and surgical technique/environmental factors. The end-point for failure is revision. A prosthesis still in place, however, does not mean success. Clinical and radiographic outcomes should describe in more detail the efficacy of hip replacement surgery instead of the relatively blunt outcome measure that the register can provide. We performed a clinical outcome analysis on patients with primary total hip replacement thus testing the adequacy of the end-point for failure in the Swedish register. 1,113 randomly selected patients who had had total hip replacement surgery between 1986 and 1995 answered a disease-specific self-administered questionnaire (WOMAC). A cohort of 344 patients was studied, using the Harris Hip Score and a conventional radiographic examination as outcome measures. We found clinical failure rates of 13% and 20% for all implants after 10 years, using 60 points or revision as the definition of failure in the Harris Hip Score and WOMAC, respectively. The result, according to the register during the same period, was a 7% revision rate. The clinical failure rate depended on the type of evaluation tool, definition of failure and demographics, which made it difficult to decide whether there was a need for revision. With the exception of pain measured by the Harris Hip Score, the results showed no significant correlation between clinical failure and radiographic failure. Hence, with the knowledge that there is a difference between the revision rate according to the register and clinical outcome, the strict definition of failure in the register is useful as an end-point for primary hip replacement surgery.

Is the Harris hip score system useful to study the outcome of total hip replacement?

Although the Harris hip score frequently is used to assess the outcome of total hip replacement, only a few minor validity tests have been presented. The aim of this study was to perform a validity test of the Harris hip score and to test its reliability. Two cohorts were studied. First, 58 patients who had undergone total hip replacement 2 to 10 years earlier were evaluated by an orthopaedic surgeon and an experienced physiotherapist using the Harris hip score. The patients also answered the Western Ontario and McMaster University Osteoarthritis Index and the Medical Outcomes Study 36-Item Short-Form Health Survey. Second, 1,056 patients answered the Western Ontario and McMaster University Osteoarthritis Index and the Medical Outcomes Study 36-Item Short-Form Health Survey questionnaires. The results were compared with those of a subcohort of 344 patients who were evaluated using the Harris hip score. The following items were tested: content validity, convergent and divergent construct validity, criterion validity, test and retest reliability, internal consistency reliability, and interobserver reliability. The Medical Outcomes Study 36-Item Short-Form Health Survey, Western Ontario and McMaster University Osteoarthritis Index, and the Harris hip score showed high validity and reliability. The Harris hip score can be used by a physician or a physiotherapist to study the clinical outcome of hip replacement.

Impaction technique and graft treatment in revisions of the femoral component: laboratory studies and clinical validation.

The micromotions of femoral stems cemented into impacted bone-graft were studied in 23 femora from adult sows. The model was validated against 2 patient groups. Conventional impaction technique and a new impaction technique using polished and rotating impactors were studied in the preclinical model and in 14 and 10 patients with type II defects. The specimens were loaded in an MTS (Minneapolis Testing System) machine for 72,000 cycles at 250N to 3,250N. The bone-graft was rinsed in tepid water, and most of the bone marrow and fat were removed. Radiostereometric measurements revealed small subsidence of the stems cemented into the specimens and the patients 6 weeks after the operation without any difference (median values, -0.06 to -0.16 mm). Further studies of specimens operated with nontreated bone-graft showed that extraction of fat increased the stability. Our findings suggest that the early postoperative implant stability after impaction grafting of the femur mainly is an effect of surgical technique and graft treatment. The new impaction technique, with which we hoped to obtain a more reproducible procedure and less risk for perioperative fracture, resulted in stability equal to that obtained with the conventional technique.

Are the findings in the Swedish National Total Hip Arthroplasty Register valid? A comparison between the Swedish National Total Hip Arthroplasty Register, the National Discharge Register, and the National Death Register.

The Swedish National Total Hip Arthroplasty (THA) Register was initiated in 1979, and it is one of the oldest quality registers in the world. The register covers all hospitals in Sweden, and today it contains > 205,000 hip arthroplasties. The failure endpoint definition in the register is revision. There is no information about quality of life and mortality. The aim of this study was to validate the results presented by the Swedish THA register by comparison with the Discharge register (the Swedish National Board of Health and Welfare) and to study mortality after hip arthroplasties. All hip arthroplasties from the Discharge register, performed in 1986 and thereafter, were compared with the Swedish THA register. Epidemiologic parameters, including mortality, were documented from the Swedish Death register. The mortality for primary THAs for men was 1% higher and for women 6% higher when compared with an age-matched and sex-matched cohort. For revision, the numbers were 7% and 9% higher. The risk for death compared with an age-matched and sex-matched population was lower for patients with osteoarthrosis treated with hip arthroplasty. The results with revision as failure endpoint showed that the Swedish THA register is reliable. The register includes >95% of the primary and revision THAs performed in Sweden between 1986 and 1995.

Outcome after total hip arthroplasty: Part I. General health evaluation in relation to definition of failure in the Swedish National Total Hip Arthoplasty register.

The Swedish National Total Hip Arthroplasty register, which was started in 1979, is one of the oldest national quality registers in the world and consists of over 160,000 primary operations and 12,500 revisions. The register identifies risk factors for poor outcomes related to the patient, implant and surgical techniques. The end-point for failure, i.e., revision, does not provide information about the patient's general health after the primary procedure. The aim of this study was twofold. First, to validate the end-point for failure in the Swedish National Total Hip Arthroplasty register and secondly, to study general health after total hip arthroplasty. We validated the outcome of 1,056 primary THRs randomly selected from the Discharge register in Sweden by comparing the data to the Swedish THA register. These patients had answered the SF-36 and Nottingham Health Profile questionnaires. By comparing the clinical outcome, measured as general health, with the results obtained from the register, we evaluated the importance of the end-point for failure. We found that the end-point was useful, but further evaluations are desirable. Patients operated on with hip replacement do very well up to 10 years postoperatively and those who are not revised have good general health. The findings in this study can be used as a reference for others as it shows results from a national register, with a random selection of the study cohort.