Somatosensory abnormalities in knee OA.

OBJECTIVE: The aim of this study was to use quantitative sensory testing (QST) to explore the range and prevalence of somatosensory abnormalities demonstrated by patients with advanced knee OA. METHODS: One hundred and seven knee OA patients and 50 age- and sex-matched healthy participants attended a 1-h QST session. Testing was performed on the medial side of the knee and the pain-free forearm. Light-touch thresholds were assessed using von Frey filaments, pressure pain thresholds using a digital pressure algometer, and thermal sensation and pain thresholds using a Thermotest MSA. Significant differences in median threshold values from knee OA patients and healthy participants were identified using Mann-Whitney U-tests. The z-score transformations were used to determine the prevalence of the different somatosensory abnormalities in knee OA patients. RESULTS: Testing identified 70% of knee OA patients as having at least one somatosensory abnormality. Comparison of median threshold values between knee OA patients and healthy participants revealed that patients had localized thermal and tactile hypoaesthesia and pressure hyperalgesia at the osteoarthritic knee. Tactile hypoaesthesia and pressure hyperalgesia were also present at the pain-free forearm. The most prevalent somatosensory abnormalities were tactile hypoaesthesia and pressure hyperalgesia, evident in between 20 and 34% of patients. CONCLUSION: This study found that OA patients demonstrate an array of somatosensory abnormalities, of which the most prevalent were tactile hypoaesthesia and pressure hyperalgesia. Further research is now needed to establish the clinical implications of these somatosensory abnormalities.

Unstated factors in orthopaedic decision-making: a qualitative study.

BACKGROUND: Total joint replacement (TJR) of the hip or knee for osteoarthritis is among the most common elective surgical procedures. There is some inequity in provision of TJR. How decisions are made about who will have surgery may contribute to disparities in provision. The model of shared decision-making between patients and clinicians is advocated as an ideal by national bodies and guidelines. However, we do not know what happens within orthopaedic practice and whether this reflects the shared model. Our study examined how decisions are made about TJR in orthopaedic consultations. METHODS: The study used a qualitative research design comprising semi-structured interviews and observations. Participants were recruited from three hospital sites and provided their time free of charge. Seven clinicians involved in decision-making about TJR were approached to take part in the study, and six agreed to do so. Seventy-seven patients due to see these clinicians about TJR were approached to take part and 26 agreed to do so. The patients' outpatient appointments ('consultations') were observed and audio-recorded. Subsequent interviews with patients and clinicians examined decisions that were made at the appointments. Data were analysed using thematic analysis. RESULTS: Clinical and lifestyle factors were central components of the decision-making process. In addition, the roles that patients assigned to clinicians were key, as were communication styles. Patients saw clinicians as occupying expert roles and they deferred to clinicians' expertise. There was evidence that patients modified their behaviour within consultations to complement that of clinicians. Clinicians acknowledged the complexity of decision-making and provided descriptions of their own decision-making and communication styles. Patients and clinicians were aware of the use of clinical and lifestyle factors in decision-making and agreed in their description of clinicians' styles. Decisions were usually reached during consultations, but patients and clinicians sometimes said that treatment decisions had been made beforehand. Some patients expressed surprise about the decisions made in their consultations, but this did not necessarily imply dissatisfaction. CONCLUSIONS: The way in which roles and communication are played out in decision-making for TJR may affect the opportunity for shared decisions. This may contribute to variation in the provision of TJR. Making the importance of these factors explicit and highlighting the existence of patients' 'surprise' about consultation outcomes could empower patients within the decision-making process and enhance communication in orthopaedic consultations.

Determination of digitised radiograph magnification factors for pre-operative templating in hip prosthesis surgery.

OBJECTIVE: With digital radiography development, information technology (IT) companies have developed specific software for templating procedures, requiring individual magnification assessments for each patient. The aim of this study was to determine the mean magnification factor of digital radiographs and to evaluate the possibility of using the mean magnification factor or clinical information in templating. MATERIALS AND METHODS: We retrospectively evaluated 100 primary total hip arthroplasty digital radiographs using the femoral head prosthesis as a calliper to determinate the mean magnification factor. Working on the assumption that altitude of the hip during radiograph is decisive in modification of magnification factors, we also looked for a correlation between weight, body mass index (BMI), altitude and magnification factor. RESULTS: The magnification factor was 126% (121-130%). A relationship was found between magnification factor (Mf) and weight (Mf = 7.10(-4)x weight (kg) + 1.21), but not BMI. In 98% of cases, if the weight-correlated formula is used, the sizing is correct or the error is +/- 1 mm. With the mean method the sizing is correct or within 1 mm in only 78.2% of cases. CONCLUSION: Levels of accuracy for the mean magnification factor and the weight-correlated formula are not as high as individual assessments using a calliper; however, they could be used in everyday practice where individual magnification factors have not been calculated.

Variations in the pre-operative status of patients coming to primary hip replacement for osteoarthritis in European orthopaedic centres.

BACKGROUND: Total hip joint replacement (THR) is a high volume, effective intervention for hip osteoarthritis (OA). However, indications and determinants of outcome remain unclear. The 'EUROHIP consortium' has undertaken a cohort study to investigate these questions. This paper describes the variations in disease severity in this cohort and the relationships between clinical and radiographic severity, and explores some of the determinants of variation. METHODS: A minimum of 50 consecutive, consenting patients coming to primary THR for primary hip OA in each of the 20 participating orthopaedic centres entered the study. Pre-operative data included demographics, employment and educational attainment, drug utilisation, and involvement of other joints. Each subject completed the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC - Likert version 3.1). Other data collected at the time of surgery included the prosthesis used and American Society of Anaesthesiologists (ASA) status. Pre-operative radiographs were read by the same three readers for Kellgren and Lawrence (K&L) grading and Osteoarthritis Research Society International (OARSI) atlas features. Regression analyses were carried out. RESULTS: Data from 1327 subjects has been analysed. The mean age of the group was 65.7 years, and there were more women (53.4%) than men. Most (79%) were ASA status 1 or 2. Reported disease duration was 5 years or less in 69.2%. Disease in other joint sites was common.Radiographs were available in 1051 subjects and the K&L grade was 3 or 4 in 95.8%. There was much more variation in clinical severity (WOMAC score); the mean total WOMAC score was 59.2 (SD 16.1). The radiographic severity showed no correlation with WOMAC scores.Significantly higher WOMAC scores (worse disease) were seen in older people, women, those with obesity, those with worse general health, and those with lower educational attainment. CONCLUSION: 1. Clinical disease severity varies widely at the time of THR for OA. 2. In advanced hip OA clinical severity shows no correlation with radiographic severity. 3. Simple scores of pain and disability do not reflect the complexity of decision-making about who should have a THR.

Impaction bone grafting of the acetabulum at hip revision using a mix of bone chips and a biphasic porous ceramic bone graft substitute.

BACKGROUND AND PURPOSE: One of the greatest problems of revision hip arthroplasty is dealing with lost bone stock. Good results have been obtained with impaction grafting of allograft bone. However, there have been problems of infection, reproducibility, antigenicity, stability, availability of bone, and cost. Thus, alternatives to allograft have been sought. BoneSave is a biphasic porous ceramic specifically designed for use in impaction grafting. BoneSave is 80% tricalcium phosphate and 20% hydroxyapatite. Previous in vitro and in vivo studies have yielded good results using mixtures of allograft and BoneSave, when compared with allograft alone. This study is the first reported human clinical trial of BoneSave in impaction grafting. METHODS: We performed a single-institution, multi-surgeon, prospective cohort study. 43 consecutive patients underwent revision hip arthroplasty using BoneSave and allograft to restore missing bone in the acetabulum. 9 patients had cemented acetabular components implanted and 34 uncemented. 10 patients had cemented femoral components implanted and 1 had an uncemented femoral component. 32 patients did not have their femoral component revised. RESULTS: No patients were lost to follow-up. At a mean follow-up of 24 (11-48) months, there were no re-revisions and there was no implant migration. 1 acetabular component had confluent lucent lines at the implant-graft interface. Complications were rare (1 fracture, 2 dislocations). Patient satisfaction with the procedure was high. INTERPRETATION: Short-term results indicate that impaction grafting of BoneSave and allograft is an effective method of dealing with loss of bone stock at revision hip surgery.

The operation of the century: total hip replacement.

In the 1960s, total hip replacement revolutionised management of elderly patients crippled with arthritis, with very good long-term results. Today, young patients present for hip-replacement surgery hoping to restore their quality of life, which typically includes physically demanding activities. Advances in bioengineering technology have driven development of hip prostheses. Both cemented and uncemented hips can provide durable fixation. Better materials and design have allowed use of large-bore bearings, which provide an increased range of motion with enhanced stability and very low wear. Minimally invasive surgery limits soft-tissue damage and facilitates accelerated discharge and rehabilitation. Short-term objectives must not compromise long-term performance. Computer-assisted surgery will contribute to reproducible and accurate placement of implants. Universal economic constraints in healthcare services dictate that further developments in total hip replacement will be governed by their cost-effectiveness.

A systematic comparison of the actual, potential, and theoretical health effects of cobalt and chromium exposures from industry and surgical implants.

Humans are exposed to cobalt (Co) and chromium (Cr) from industry and surgical devices, most notably orthopedic joint replacements. This review compares the potential health effects of exposure to Co and Cr contaminants from these two different sources, both in the locally exposed tissues and at sites distant to the primary exposure. Surgical implantation results largely in exposures to ions, corrosion products, and particles of Co and Cr. Industrial exposures are predominantly to metal compounds and particles. Although there are large literatures on industrial and surgical exposures to these metals, there has yet to be a systematic comparison of the two to test whether more general lessons might be learned about the human toxicology of Co and Cr. Both industrial and surgical exposures cause inflammatory and other immune reactions in the directly exposed tissues. In the lung there is a well-established risk of cancer following long-term exposures to hexavalent Cr; however, the development of sarcoma in the connective tissues adjacent to implants in response to metal particles is rare. Both types of exposure are associated with changes in the peripheral blood, including evidence of oxidative stress, and altered numbers of circulating immune cells. There is dissemination of Co and Cr to sites distant to the orthopedic implant, but less is known about systemic dissemination of these metals away from the lung. The effects of industrial exposures in the reproductive, renal, and cardiac systems have been investigated, but this has yet to be explored after surgical exposures. The form of the metal (and associated elements) in both instances is key to the toxicological effects arising in the body and further characterization of debris released from devices is certainly recommended, as is the impact of nanotoxicology on the health and safety of workers and patients. Biomonitoring schemes currently used in industry could be translated, if required, into suitable programs for orthopedic out-patients. Cross-communication between experts in industrial and occupational medicine and regulatory agencies may be useful.

A new short uncemented, proximally fixed anatomic femoral implant with a prominent lateral flare: design rationals and study design of an international clinical trial.

BACKGROUND: Anatomic short femoral prostheses with a prominent lateral flare have the potential to reduce stress-shielding in the femur through a more physiological stress distribution to the proximal femur. We present the design rationale of a new short uncemented, proximally fixed anatomic femoral implant and the study design of a prospective multi-centre trial to collect long-term patient outcome and radiographic follow up data. METHODS: A prospective surveillance study (trial registry NCT00208555) in four European centres (UK, Italy, Spain and Germany) with a follow up period of 15 years will be executed. The recruitment target is 200 subjects, patients between the ages of 18 and 70 admitted for primary cementless unilateral THA will be included. The primary objective is to evaluate the five-year survivorship of the new cementless short stem. The secondary objectives of this investigation are to evaluate the long term survivorship and the clinical performance of the implant, the impact on the subjects health related Quality of Life and the affect of the prosthesis on bone mineral density. Peri- and postoperative complications will be registered. Clinical and radiographic evaluation of prosthesis positioning will be done post-operatively and at 3, 6, 12, 24, 60, 120 and 180 months follow up. DISCUSSION: Shortening of the distal stem can maximise bone and soft tissue conservation. New stem types have been designed to improve the limitations of traditional implants in primary THA. A new, uncemented femoral short stem is introduced in this paper. A long-term follow up study has been designed to verify stable fixation and to research into the clinical outcome. The results of this trial will be presented as soon as they become available.

Genotoxic effects of particles of surgical cobalt chrome alloy on human cells of different age in vitro.

Humans are exposed to metals from industry, the environment and from wear debris from worn orthopaedic joint replacements. Patients exposed to worn cobalt chrome hip replacements show an increase of chromosome aberrations in the bone marrow adjacent to the implant and an increase of chromosome translocations and aneuploidy in the peripheral blood. This study has tested whether particles of surgical cobalt chrome alloy are able to induce similar DNA damage and chromosome aberrations in human cells in vitro. Because increasingly young patients are receiving hip replacements it has also tested whether the response is altered at different cellular age in vitro. Primary human fibroblasts, were tested at different pre senescent population doublings (PD10 (young) and PD35 (older)) to particles of cobalt chrome alloy for up to 15 days. As in patients there was an increase of aneuploidy, chromosome translocations and DNA damage after exposure to the cobalt chrome particles in vitro. The overall level of DNA damage and numerical and structural aberrations was approximately the same in young and older cells. However, the cellular reaction to the DNA damage was different. Older cells showed a greater loss of viability and induction of senescence and a lesser rate of mitosis and cell growth than young cells. They showed less change in transcription, particularly of p38 and caspase 10 mRNA levels, than young cells. They showed more complex aneuploidy in association with unseparated or prematurely separated chromatids. This study suggests that at least part of the chromosome changes in patients with worn implants may be due to direct effects of the metal wear particles from the implant. It would be of interest to test whether the altered reaction of the human cells at different in vitro age might correspond with a different incidence of chromosome aberrations in patients at different ages.

Patient expectations regarding total knee arthroplasty: differences among the United States, United Kingdom, and Australia.

BACKGROUND: Total knee arthroplasty is an effective treatment for severe osteoarthritis of the knee. Our aim was to determine whether patients from the United Kingdom, United States, and Australia have different preoperative expectations regarding total knee arthroplasty and whether these expectations have an impact on outcomes and patient satisfaction. METHODS: Patients from the United Kingdom, the United States, and Australia were recruited into a prospective observational study of primary total knee arthroplasty for the treatment of osteoarthritis. Preoperative expectations, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Short Form-36 (SF-36) scores, and demographic, socioeconomic, and follow-up data, including satisfaction with outcome, were obtained from self-administered patient questionnaires. RESULTS: A total of 598 patients with a mean age of sixty-nine years at the time of the index arthroplasty were recruited; 58% were women. The majority of patients expected to have no pain at twelve months after the surgery, and with the numbers available there was no significant difference among the countries with regard to pain expectations. Australian patients were more likely than patients in the United Kingdom or the United States to expect better function at twelve months after the surgery. With the numbers available, satisfaction scores at twelve months did not differ significantly among the countries and were not influenced by preoperative expectations. Australian patients were more likely than patients in the United Kingdom or the United States to be unwilling to undergo total knee arthroplasty again at twelve months under similar circumstances. CONCLUSIONS: Patients from different countries have different expectations regarding total knee arthroplasty, which are not fully explained by differences in sociodemographic factors, clinical characteristics, and pain and functional status. Australian patients had the highest expectations but, despite reporting similar outcomes and satisfaction following total knee arthroplasty, they were more likely not to want to have the surgery again under similar circumstances.

Quantifying the quasi-static angle and base of gait: a preliminary investigation comparing footprints and a clinical method.

Although the angle and base of gait are useful parameters commonly measured in podiatric medical practice, a standardized procedure has yet to be defined. Static footprints and clinical tracings of the perimeters of both feet were investigated in 25 asymptomatic subjects (17 women and 8 men). The intrarater reliability of each measurement condition was assessed using intraclass correlation coefficients and ranged from 0.965 to 0.981 for the angle of gait and from 0.979 to 0.986 for the base of gait. Both sets of data were compared using paired t-tests and demonstrated no significant differences (P > .001) for the angle and base of gait. The results suggest that footprint data and a simple clinical tracing of the foot are similar, providing a useful clinical tool for static assessment of the angle and base of gait.

The Oxford hip score: the patient's perspective.

BACKGROUND: In the last 25 years, assessment of orthopaedic intervention has become patient focused, with the development of self-completion patient-centred outcome measures. The Oxford hip score (OHS) is a joint specific outcome measure tool designed to assess disability in patients undergoing total hip replacement (THR). Although the psychometric properties of the OHS have been rigorously examined, there is little research on the patient's perspective of the OHS. Therefore, the aim of this study is to assess whether the OHS is an adequate disability measure from the patient's perspective using qualitative analysis of annotations written on the OHS by patients. METHODS: In total, 276 orthopaedic patients completed an OHS between April 2004 and May 2005. One hundred and fifty six pre-operative patients listed for a THR completed the OHS during a pre-admission assessment clinic, and 120 post-operative patients completed the OHS postally in the home setting. Patient's unprompted annotations in response to the questions on the OHS were recorded and grouped into thematic categories. RESULTS: In total, 46 (17%) patients made 52 annotations when completing the OHS. These annotations identified five main areas of difficulty that patients experienced: lack of question clarity (particularly concerning the use of aids), difficulty in reporting measurements of pain, restrictive and irrelevant questions, the influence of co-morbidities on responses, and double-barrelled questions. CONCLUSION: Although the OHS is a useful short tool for the assessment of disability in patients undergoing THR, this study identified several problem areas that are applicable to patient-centred outcome tools in general. To overcome these current limitations, further work is underway to develop a more individualised patient-centred outcome measure of disability for use in patients with osteoarthritis.

Orthopaedic surgery. Joint effort.

Hip replacement surgery is becoming increasingly specialised and evidence shows that, particularly in revision, surgery is best done by specialists. An audit of GPs suggests great variation in referral practice, with one-third prepared to refer to a 'generalist' orthopaedic surgeon. GPs need better communication with hospitals and knowledge of where specialists are available.

The usage of image trigonometry in bone measurements.

The entire musculo-skeletal system responds dynamically to stresses and strains applied to it. Restoring normal biomechanics contributes to the normal function that ensures that physiological stresses and strains are preserved. Appropriate preoperative planning is mandatory to restore normal biomechanics at reconstructive surgery. Effective preoperative planning depends on the ability to reproducibly make accurate measurements of lengths and angles from plain radiographs. Measurement has become an integral part of orthopaedics to define morphological abnormality, to plan for reconstruction and for comparative research. The most prevalent method of measurement is usually based on lines drawn on radiographs with no accurate reference to the actual geometry of the structures. This two-dimensional projection of an asymmetrical three-dimensional structure leads to inaccuracy and consequently to a compromise in the overall precision of many procedures. In addition it is also difficult to monitor the progression of disease as the exact relationship of the bones and joints to each other, and to prosthetics, cannot be accurately recorded. This paper presents a method of digitally measuring relevant bone parameters in a geometric manner in order to achieve accurate, repeatable measurements.

Primary and revision THA using a stemless metaphyseal-loading implant above distorted proximal femoral anatomy.

Total hip arthroplasty is well established as a successful treatment for end stage arthritis, with a wide variety of components currently available. Using traditional stemmed implants in patients with a distorted proximal femur can be technically challenging with an increased risk of complications. We present seven patients with distorted proximal femoral anatomy or failed hip arthroplasty in whom a short, metaphyseal loading implant was utilised. At minimum two-year follow-up there have been no complications with all stems stable and well fixed radiologically. Average improvement in Oxford Hip Score is 32. We suggest that a short, metaphyseal loading prosthesis can be considered in cases where a conventional stemmed implant may not be suitable due to challenging proximal femoral anatomy.

Blood levels of cobalt and chromium are inversely correlated to head size after metal-on-metal resurfacing arthroplasty.

Resurfacing arthroplasty has fallen out of favour in recent years due to unfavourable survivorship in joint registries and alarming reports of soft tissue reactions around metal on metal prostheses. Our aim was to assess the effect of head size, implant design and component positioning on metal production by resurfacing arthroplasties. We measured whole blood cobalt and chromium and component position in matched populations implanted with two designs of resurfacing arthroplasty over a two-year period. Both implants resulted in a significant increase in blood metal levels (p<0.001) though the ASR design generated significantly higher metal levels (p = 0.041). A significant inverse correlation was seen between component size and blood cobalt levels (p = 0.032) and blood chromium levels (p<0.001). No correlation was identified between component position and blood metal levels. Small diameter metal resurfacing components result in increased metal generation compared with larger components. As increased metal generation has been correlated to wear and therefore failure, caution must be used on implantation of smaller components and indeed, in those who require smaller components, alternative bearing materials should be considered. These results contrast with recent findings which have demonstrated early failure for larger diameter stemmed metal-on-metal prostheses.

Medium-term outcome in patients treated with total hip arthroplasty using a modular femoral stem.

The clinical, radiographic and quality of life results of total hip arthroplasty using the MODULUS cementless modular femoral stem were reviewed. 48 patients who had a total hip arthroplasty using the MODULUS femoral stem were identified. Six had bilateral procedures, resulting in 60 hips with complete clinical and radiographic data. Mean age at implantation was 50 years (range 33 to 82). Mean follow-up was 59 months (range 50 months to 73). There were two early post-operative dislocations (within 2 days). One patient required further surgery to remove heterotopic bone. Mean Harris Hip Score increased from 37 points preoperatively (range, 7 to 66) to 89 points at final review (range, 65 to 100 points). Radiographic evaluation revealed that all implants were stable without evidence of osteolysis but three patients (5%) exhibited heterotopic ossification. Quality of life was evaluated with the SF36. The physical component increased from 29.2 points (range, 18.5 to 46.0) to 51.7 points (range 42.9 to 60.6) and the mental component from 375 points (range, 19.5 to 50.0) to 50 points (range 32,8 to 62.0).

Does improved instrumentation result in better component alignment in total knee arthroplasty?

Accurate component alignment and joint line reproduction in total knee replacement (TKR) is crucial for successful clinical outcome. Advances in instrumentation and better understanding of the biomechanics can help to achieve better three dimensional alignments of TKR components and joint line restoration. We compared the accuracy of component alignment and joint line restoration with the use of 2 different TKR instrumentation kits (an older Gobot and a newer Xcelerate). Retrospective study of 150 consecutive patients undergoing primary TKR had their pre and post-operative x-rays reviewed. Seventy-five patients (group A) had their TKR using the older instrumentation kit (Gobot) and 75 (group B) had the newer version (Xcelerate). The positioning of the prosthesis components were assessed using the American Knee society radiographic evaluation method and the joint line position using the Figgie's method. The results from the two groups were statistically compared. There was a significantly greater elevation of the joint line position in TKRs done with the Gobot instrumentation (mean 4.49 mm vs. 2.71 mm in group B, P=0.03), and significant differences in the mean tibial component angle cTCA (group A 88.6°, group B 90.1°, P=0.04) and the mean Q angle (group A 6.28° valgus, group B 8.45° valgus, P=0.04). Use of the newer Xcelerate instrumentation was associated with better restoration of joint line position, however the femoral component flexion and posterior slope of the tibial component ere found to be above the desired level. Hence the overall differences between the two groups were found to be small.