Aims

The aim of this study was to investigate the association between fracture displacement and survivorship of the native hip joint without conversion to a total hip arthroplasty (THA), and to determine predictors for conversion to THA in patients treated nonoperatively for acetabular fractures.

Aims

The aims of this study were to determine if an increasing serum cobalt (Co) and/or chromium (Cr) concentration is correlated with a decreasing Harris Hip Score (HHS) and Hip disability and Osteoarthritis Outcome Score (HOOS) in patients who received the Articular Surface Replacement (ASR) hip resurfacing arthroplasty (HRA), and to evaluate the ten-year revision rate and show if sex, inclination angle, and Co level influenced the revision rate.

Aims

Factors associated with high mortality rates in geriatric hip fracture patients are frequently unmodifiable. Time to surgery, however, might be a modifiable factor of interest to optimize clinical outcomes after hip fracture surgery. This study aims to determine the influence of postponement of surgery due to non-medical reasons on clinical outcomes in acute hip fracture surgery.

Literature surrounding artificial intelligence (AI)-related applications for hip and knee arthroplasty has proliferated. However, meaningful advances that fundamentally transform the practice and delivery of joint arthroplasty are yet to be realized, despite the broad range of applications as we continue to search for meaningful and appropriate use of AI. AI literature in hip and knee arthroplasty between 2018 and 2021 regarding image-based analyses, value-based care, remote patient monitoring, and augmented reality was reviewed. Concerns surrounding meaningful use and appropriate methodological approaches of AI in joint arthroplasty research are summarized. Of the 233 AI-related orthopaedics articles published, 178 (76%) constituted original research, while the rest consisted of editorials or reviews. A total of 52% of original AI-related research concerns hip and knee arthroplasty (n = 92), and a narrative review is described. Three studies were externally validated. Pitfalls surrounding present-day research include conflating vernacular (“AI/machine learning”), repackaging limited registry data, prematurely releasing internally validated prediction models, appraising model architecture instead of inputted data, withholding code, and evaluating studies using antiquated regression-based guidelines. While AI has been applied to a variety of hip and knee arthroplasty applications with limited clinical impact, the future remains promising if the question is meaningful, the methodology is rigorous and transparent, the data are rich, and the model is externally validated. Simple checkpoints for meaningful AI adoption include ensuring applications focus on: administrative support over clinical evaluation and management; necessity of the advanced model; and the novelty of the question being answered.

Cite this article: Bone Joint J 2022;104-B(12):1292–1303.

Aims

Two-stage exchange revision total hip arthroplasty (THA) performed in case of periprosthetic joint infection (PJI) has been considered for many years as being the gold standard for the treatment of chronic infection. However, over the past decade, there have been concerns about its safety and its effectiveness. The purposes of our study were to investigate our practice, collecting the overall spacer complications, and then to analyze their risk factors.

Introduction

Post op cup anatomical and functional orientation is a key point in THP patients regarding instability and wear. Recently literature has been focused on the consequences of the transition from standing to sitting regarding anteversion, frontal and sagittal inclination. Pelvic incidence (PI) is now considered as a key parameter for the analysis of sagittal balance and sacral slope (SS) orientation. It's influence on THP biomechanics has been suggested. Interestingly, the potential impact of this morphological angle on cup implantation during surgery and the side effects on post op functional orientation have not been studied.

Our study explores this topic from a series of standing and sitting post-op EOS images

Objectives

Preclinical data showed poly(methyl methacrylate) (PMMA) loaded with microsilver to be effective against a variety of bacteria. The purpose of this study was to assess patient safety of PMMA spacers with microsilver in prosthetic hip infections in a prospective cohort study.

Postoperative dislocation following total hip arthroplasty (THA) remains a significant concern with a reported incidence of 1% to 10%. The risk of dislocation is multifactorial and includes both surgeon-related (i.e. implant position, component size, surgical approach) and patient-related factors (i.e. gender, age, preoperative diagnosis, neurologic disorders). While the majority of prior investigations have focused on the importance of acetabular component positioning, recent studies have shown that approximately 60% of “dislocators” following primary THA have an acceptably aligned acetabular component. Therefore, the importance of the relationship between the spine and pelvis, and its impact on functional component position has gained increased attention. Kanawade and Dorr et al. have shown patients can be categorised into having a stiff, normal, or hypermobile pelvis based on their change in pelvic tilt when moving from the standing to seated position. The degree of change in functional position of both the acetabular and femoral components is impacted by the degree of pelvic motion each patient possesses. In the “normal” pelvis, as a patient moves from the standing to seated position the pelvis typically tilts posteriorly, thus increasing the functional anteversion of the acetabular component. However, patients with lumbar degeneration or spine pathology often have a decrease in posterior pelvic tilt in the seated position, thus potentially increasing their risk of dislocation. Bedard et al. noted an 8.3% dislocation risk in patients with a spinopelvic fusion after THA vs. 2.9% in those without. There is the potential that preoperative, dynamic imaging can be used to predict the ideal component position for each individual patient undergoing THA. However, this assumes that a patient's preoperative pelvic motion will be the same following implantation of a total hip prosthesis, and that a patient's pelvic motion will remain consistent over time postoperatively. A recent study has shown that the impact of THA on pelvic motion can be highly variable, thus potentially limiting the utility of preoperative dynamic imaging in predicting a patient's ideal component position. Future investigations must focus on preoperative factors that can be used to predict postoperative pelvic motion and how pelvic motion changes over time following implantation of a total hip arthroplasty

Orthopaedic implants, such as femoral heads, sockets and stems, are manufactured with a high degree of smoothness and very low form error in order to function as low wear bearings. The surfaces are subject to both wear and damage during in vivo use. Articulating surfaces naturally wear during normal use. Aseptic loosening associated with osteolysis and release of wear particles is the main reason for revision of total hip arthroplasty (THA). Damage of femoral heads is well known to increase the wear rate at the articulating surface and is vulnerable to scratching during the maneuver of positioning the femoral component into the acetabulum component either in primary as in revision total hip arthroplasties. The findings emphasize the importance of achieving and maintaining good surface finish of the femoral head component. The author presents a very simple and “zero cost” method of preventing scratching of the femoral head of any kind of total hip prosthesis (ceramic on ceramic, ceramic on poly, metal on metal, metal on poly and even metal on ceramic) when the reduction of the femoral head prosthesis is done inside the new acetabular component with metal, ceramic liner or poly liner with metal back (where the scratching can also occur) as one of the final stages of the surgical procedure which can be crucial to the long survival of the hip prosthesis. A short one minute video on an e-poster will show how this can be done being an easy, reproducible, safe and reliable technique to prevent femoral head scratching

SL-PLUS MIA stem (Smith & Nephew Orthopaedics AG) is a modified implant of Zweymuller type SL-PLUS standard stem (Smith & Nephew Orthopaedics AG). We constructed finite element (FE) models and analysed equivalent stresses in the femur. In addition, we measured bone mineral density (BMD) in the femur by dual-energy X-ray absorptiometry (DEXA) after THA. The purpose of this study was to investigate the equivalent stress and to compare the results of the FE analyses with changes in BMD after THA. Twenty-one patients (18 women and 3 men) who underwent primary cementless THA with SL-PLUS MIA or SL-PLUS formed the basis of this study. Eleven patients received SL-PLUS MIA and ten patients received SL-PLUS. Zones were defined according to Gruen's system (zones 1∼7). Computed-tomography (CT) images of the femur were taken before and at 1 week after THA. FE models of the femur and prosthesis were obtained from CT data by Mechanical Finder (Research Center of Computational Mechanics Inc., Tokyo, Japan), software that creates FE models showing individual bone shape and density distribution. Equivalent stresses were analysed in zones 1 to 7 and compared to the DEXA data. FE studies revealed that there was no significant difference in equivalent stress between SL-PLUS MIA and SL-PLUS. BMD was maintained after THA in zones 3, 4, and 5, whereas BMD decreased in zones 2, 6, and 7. In zone 1, BMD decreased in SL-PLUS MIA stem group by 14%, while BMD was maintained in SL-PLUS standard stem.

Objectives

Prosthetic joint infection (PJI) is a devastating complication following total joint arthroplasty. Non-contact induction heating of metal implants is a new and emerging treatment for PJI. However, there may be concerns for potential tissue necrosis. It is thought that segmental induction heating can be used to control the thermal dose and to limit collateral thermal injury to the bone and surrounding tissues. The purpose of this study was to determine the thermal dose, for commonly used metal implants in orthopaedic surgery, at various distances from the heating centre (HC).

Aims

The aim of this study was to assess the current trends in the estimation of survival and the preferred forms of treatment of pathological fractures among national and international general and oncological orthopaedic surgeons, and to explore whether improvements in the management of these patients could be identified in this way.

Total Hip Arthroplasty (THA) is a well-established, cost-effective treatment for improving function and alleviating pain in patients who have disabling hip disease with excellent long-term results. Based on the excellent results, there is an ongoing trend for THA to be performed in younger and more active patients, having higher physical demands on their new total joints.

Polyethylene (PE) wear and its biological consequences are one of the main causes of implant failure in THA. Macrophages phagocytise PE wear particles and this will result in osteolysis and loss of periprosthetic bone. The risk of these complications can be estimated in relation to the amount of volumetric wear based on two assumptions: that the number of PE particles dispersed in the peri-prosthetic tissues is controlled by the amount of PE wear; and that the development of osteolysis and the resulting aseptic loosening is triggered by these PE particles. Based on these assumptions, a model was developed to estimate the osteolysis-free life of a THA, depending on the Linear Wear Rate (LWR) and femoral head size of the PE bearing.

A review of the literature was conducted to provide an estimate of the radiologic osteolysis threshold based on the volumetric wear of the PE bearing. This review demonstrates that this radiologic osteolysis threshold is approximated 670 mm3 for conventional PE. The osteolysis-free life of the THA was estimated by simply dividing this threshold volume by the annual Volumetric Wear Rate (VWR) of the bearing. The annual VWR is basically controlled by two parameters: (1) annual LWR and (2) head size, and was calculated by using published formulae.

For 28 mm heads, following osteolysis-free life was determined in function of the annual LWR. LWR: 10 µm/y => 116.6 years / LWR: 25 µm/y => 46.6 years / LWR: 50 µm/y => 23.3 years / LWR: 100 µm/y => 11.6 years. For 40 mm heads, following osteolysis-free life was determined in function of the annual LWR. LWR: 10 µm/y => 57.1 years / LWR: 25 µm/y => 22.9 years / LWR: 50 µm/y => 11.4 years / LWR: 100 µm/y => 5.7 years.

The osteolysis-free life determined by this model is in good agreement with the clinical results of PE bearings having a 28 mm head size and demonstrates that extreme low LWRs are mandatory to assure a descent osteolysis-free life for THA (PE bearings) using large heads, such as 40 mm. For such head sizes, small variations of the LWR may have large impacts on the osteolysis-free life of the THA.

Increasing innovation in rapid prototyping (RP) and additive manufacturing (AM), also known as 3D printing, is bringing about major changes in translational surgical research.

This review describes the current position in the use of additive manufacturing in orthopaedic surgery.

Cite this article: Bone Joint J 2018;100-B:455-60.

Introduction. Computer navigation is a highly sophisticated tool in orthopedic surgery for component placement in total hip arthroplasty (THA). In order to apply it adequately it is of upmost importance that the targets the surgeon is trying to hit are well-defined. This concept considers all four component orientations: cup inclination (cIncl) and anteversion (cAV), stem antetorsion and neck-to-shaft angle. The optimising goal in this concept is maximising the size of the cSafe-Zone. Methods. A computerised 3D- model of a total hip prosthesis was used to systematically analyse all combinations of component orientations in automatised batch runs. Component orientations were varied for cup inclination, cup anteversion, neck antetorsion and neck inclination. Results. The combined Safe-Zone outlines spaces in a 3D-diagram that show the relationship between cup inclination, cup anteversion and neck anteversion, while the neck inclination is used as a curves parameter. These spaces include all component orientation that allow the predefined iROM without prosthetic impingement. In order to compare these results to Lewinnek's recommendation cross-sections were taken at distinct neck antetorsions in 5° intervals. Conclusion. The new combined Safe-Zone (cSafe-Zone) includes all orientation parameters of both total hip components and such gives well-defined recommendations for combined positioning of both components. Ideally it can be introduced into a smart computer navigation system in order to compute in real-time the best combined orientation of both components

Introduction. Lewinnek's Safe-Zone gives recommendations only for cup placement in total hip arthroplasty while the orientation of the neck isn't considered. Furthermore the criteria for cup placement are not clearly defined and the ranges for cup orientation are considerably large. This study introduces new recommandations for the combined placement of both total hip components, when both, cup and stem, are considered. This defines the new dynamic combined safe-zone (cSafe-Zone) which gives clear directions for the optimal combined orientation of both components in order to maximize the intended range of movement (iROM) while reducing the risk for prosthetic impingement and dislocation. Material and Methods. The combined safe-zone outlines the area that encloses all component orientations that achieve the predefined iROM without prosthetic impingement. A computerized 3D-model of a total hip prosthesis was established that does systematically test all design parameters semi-automatically in order to identify those component positions that fulfill the predefined conditions. The analysis was carried out for straight stems, anatomic stems and short stems. The iROM is composed of basic movements like flexion/extension, internal/external rotation, ab/adduction and combination of these movements that the patient should reach and that are commonly accepted as physiologic hip movements. The orientation of the cup was varied between 20° and 70° of inclination and −10° of retro- to 40° anteversion. Stem antetorsion was tested from −10° retro- to 40°-antetorsion and CCD-angle from 110° to 150°. Head-size and head/neck ratio were additional parameters. Results. The new combined safe-zone has a dynamic location and has a polygonal outer boundary. It is smaller than Lewinnek's safe-zone. Its size and location within the cup inclination/anteversion diagram depends on the antetorsion and the CCD-angle of the stem. It can be demonstrated that a low-anteverted stem should be combined with a high-anteverted cup and vice versa, i.e. cup anteversion and stem antetorsion are linearly but inversely correlated. This is true for a straight stem as well as for anatomic and for short stems. The size of the cSafe-Zone is largest when the socket is radiographically anteverted between 20° and 25°. The neck/shaft-angle (CCD-angle) and the anatomic design do have a high impact on the preferred antetorsion of the stem. A straight 130°-CCD-stem is best implanted in about 15°+/−4degree of antetorsion while an anatomic 127°-CCD-stem can be implanted in a lower degree of antetorsion. Increasing the head/neck ratio increases the cSafe-Zone too and gives room for a lower cup inclination which increases the jumping distance. The optimal CCD-angle of a straight stem is 127°+/−3 degree. Conclusion. The new combined safe-zone (cSafe-zone) gives well-defined recommendations for cup and stem placement taking into account the dynamic interrelationship between cup and stem. In extending Lewinnek's recommendations it defines how both the cup and the stem should be oriented relative to each other and how the component's orientations are optimized in order to achieve the highest safety against prosthetic impingement while reaching the highest range of movement which is especially important for high-performance materials and in young and active patients

Objectives

The high revision rates of the DePuy Articular Surface Replacement (ASR) and the DePuy ASR XL (the total hip arthroplasty (THA) version) have led to questions over the viability of metal-on-metal (MoM) hip joints. Some designs of MoM hip joint do, however, have reasonable mid-term performance when implanted in appropriate patients. Investigations into the reasons for implant failure are important to offer help with the choice of implants and direction for future implant designs. One way to assess the performance of explanted hip prostheses is to measure the wear (in terms of material loss) on the joint surfaces.

Objectives. The cytotoxicity induced by cobalt ions (Co. 2+. ) and cobalt nanoparticles (Co-NPs) which released following the insertion of a total hip prosthesis, has been reported. However, little is known about the underlying mechanisms. In this study, we investigate the toxic effect of Co. 2+. and Co-NPs on liver cells, and explain further the potential mechanisms. Methods. Co-NPs were characterised for size, shape, elemental analysis, and hydrodynamic diameter, and were assessed by Transmission Electron Microscope, Scanning Electron Microscope, Energy Dispersive X-ray Spectroscopy and Dynamic Light Scattering. BRL-3A cells were used in this study. Cytotoxicity was evaluated by MTT and lactate dehydrogenase release assay. In order to clarify the potential mechanisms, reactive oxygen species, Bax/Bcl-2 mRNA expression, IL-8 mRNA expression and DNA damage were assessed on BRL-3A cells after Co. 2+. or Co-NPs treatment. Results. Results showed cytotoxic effects of Co. 2+. and Co-NPs were dependent upon time and dosage, and the cytotoxicity of Co-NPs was greater than that of Co. 2+. In addition, Co-NPs elicited a significant (p < 0.05) reduction in cell viability with a concomitant increase in lactic dehydrogenase release, reactive oxygen species generation, IL-8 mRNA expression, Bax/Bcl-2 mRNA expression and DNA damage after 24 hours of exposure. Conclusion. Co-NPs induced greater cytotoxicity and genotoxicity in BRL-3A cells than Co. 2+. Cell membrane damage, oxidative stress, immune inflammation and DNA damage may play an important role in the effects of Co-NPs on liver cells. Cite this article: Y. K. Liu, X. X. Deng, H.L. Yang. Cytotoxicity and genotoxicity in liver cells induced by cobalt nanoparticles and ions. Bone Joint Res 2016;5:461–469. DOI: 10.1302/2046-3758.510.BJR-2016-0016.R1

Objectives

High failure rates of metal-on-metal hip arthroplasty implants have highlighted the need for more careful introduction and monitoring of new implants and for the evaluation of the safety of medical devices. The National Joint Registry and other regulatory services are unable to detect failing implants at an early enough stage. We aimed to identify validated surrogate markers of long-term outcome in patients undergoing primary total hip arthroplasty (THA).