The impact of wait time on patient outcomes in knee and hip replacement surgery: a scoping review protocol.

BACKGROUND: Total hip and total knee replacement surgery are in high demand, leading to long wait times for many patients. While on the waiting list, patients may experience worsening pain, reduced mobility, and deteriorating health. Given that long wait times are common for lower joint replacement surgery, it is important to understand how patient health changes during the wait period and whether this impacts patient outcomes after surgery. The aim of this scoping review will be to identify and describe the evidence regarding the impact of wait time on patient outcomes for patients who undergo total knee and total hip replacement surgery. METHODS: This scoping review was designed with guidance from the Joanna Briggs Institute Manual for Evidence Synthesis, and results will be reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping reviews. EMBASE, Medline, PubMed, Scopus, CINAHL, and Cochrane electronic databases will be searched for English language articles published after 1999. Studies of adult patients with osteoarthritis undergoing primary knee or hip replacement surgery, which measure patient outcomes over the wait period for surgery, will be included. Two independent reviewers will screen titles and abstracts followed by full article review. Data will be extracted by two reviewers using a standardized form. Outcomes assessed during the wait period will be identified and described in tables. Factors associated with changes in health status during the wait period will be qualitatively described. DISCUSSION: This review will map the evidence regarding wait times for lower extremity joint replacement surgery. Better understanding of how the impact of wait times on patient health status is measured over the perioperative period will inform future research on wait times. SCOPING REVIEW REGISTRATION: Registered with Open Science Framework, Feb 14, 2021 DOI: https://doi.org/10.17605/OSF.IO/MV4FS.

Incremental costs of fragility fractures: a population-based matched -cohort study from Ontario, Canada.

Using a matched cohort design, the 1-year excess cost of incident fragility fractures at any site was $26,341 per patient, with 43% of total excess costs attributed to hospitalization. The high economic burden of fractures in Ontario underscores the urgency of closing the secondary fracture prevention gap. INTRODUCTION: This retrospective real-world observational study was conducted to document the incremental costs associated with fragility fractures in Ontario, Canada. METHODS: Patients aged >65 years with an index fragility fracture occurring between January 2011 and March 2015 were identified from administrative databases and matched 1:1 to a cohort of similar patients without a fracture. Healthcare resource utilization data were extracted from healthcare records and associated costs were calculated on a per-patient level and for the province of Ontario. Costs were presented as 2017 Canadian dollars. RESULTS: The eligible cohort included 115,776 patients with a fragility fracture. Of these, 101,773 patients were successfully matched 1:1 to a non-fracture cohort. Overall, hip fractures (n = 31,613) were the most common, whereas femur fractures (n = 3002) were the least common type. Hospitalization and continuing care/home care/long-term care accounted for more than 60% of 1-year direct costs, whereas 5% was attributed to medication costs. First-year costs per patient in the fracture cohort were approximately threefold higher versus the non-fracture cohort (mean $37,362 versus $11,020, respectively). The incremental first-year direct healthcare costs of fragility fractures for the province of Ontario were calculated at $724 million per year. CONCLUSIONS: Fragility fractures were associated with a threefold increase in overall mean healthcare costs per patient compared to patients without fractures. With an aging population, there is an urgent need for improved prevention strategies for patients at high-risk of fracture to decrease the economic burden of fragility fractures on the Canadian healthcare system.

Same-day and delayed hospital discharge are associated with worse outcomes following total knee arthroplasty.

AIMS: To evaluate the influence of discharge timing on 30-day complications following total knee arthroplasty (TKA). PATIENTS AND METHODS: We identified patients aged 18 years or older who underwent TKA between 2005 and 2016 from the American College of Surgeons' National Surgical Quality Improvement Program (NSQIP) database. We propensity score-matched length-of-stay (LOS) groups using all relevant covariables. We used multivariable regression to determine if the rate of complications and re-admissions differed depending on LOS. RESULTS: Our matched cohort consisted of 76 246 TKA patients (mean age 67 years (sd 9)). Patients whose LOS was zero and four days had an increased risk of major complications by an odds ratio (OR) of 1.8 (95% confidence interval (CI) 1.0 to 3.2) and 1.5 (95% CI 1.2 to 1.7), respectively, compared with patients whose LOS was two days. Patients whose LOS was zero, three, and four days had an increased risk of minor complications (OR 1.8 (95% CI 1.3 to 2.7), 1.2 (95% CI 1.0 to 1.4), and 1.6 (95% CI 1.4 to 1.9), respectively), compared with patients whose LOS was two days. In addition, a LOS of three days increased the risk of re-admission by an OR of 1.2 (95% CI 1.0 to 1.3), and a LOS of four days increased the risk of re-admission by an OR of 1.5 (95% CI 1.3 to 1.6), compared with a LOS of two days. CONCLUSION: Patients discharged on days one to two postoperatively following TKA appear to have reduced major and minor complications compared with discharge on the day of surgery, or on days three to four. Prospective clinical data are required to confirm these findings. Cite this article: Bone Joint J 2019;101-B(7 Supple C):70-76.

Duration of surgery affects the risk of complications following total hip arthroplasty.

AIMS: The aim of this study was to assess the influence of operating time on 30-day complications following total hip arthroplasty (THA). PATIENTS AND METHODS: We identified patients aged 18 years and older who underwent THA between 2006 and 2016 from the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database. We identified 131 361 patients, with a mean age of 65 years (sd 12), who underwent THA. We used multivariable regression to determine if the rate of complications and re-admissions was related to the operating time, while adjusting for relevant covariables. RESULTS: The mean operating time decreased from 118.3 minutes (29.0 to 217.0) in 2006, to 89.6 minutes (20.0 to 240.0) in 2016. After adjustment for covariables, operating times of between 90 and 119 minutes increased the risk of minor complications by 1.2 (95% confidence interval (CI) 1.1 to 1.3), while operating times of between 120 and 179 minutes increased the risk of major complications by 1.4 (95% CI 1.3 to 1.6) and minor complications by 1.4 (95% CI 1.2 to 1.5), and operating times of 180 minutes or more increased the risk of major complications by 2.1 (95% CI 1.8 to 2.6) and minor complications by 1.9 (95% CI 1.6 to 2.3). There was no difference in the overall risk of complications for operating times of between 20 and 39, 40 and 59, or 60 and 89 minutes (p > 0.05). Operating times of between 40 and 59 minutes decreased the risk of re-admission by 0.88 (95% CI 0.79 to 0.97), while operating times of between 120 and 179 minutes, and of 180 minutes or more, increased the risk of re-admission by 1.2 (95% CI 1.1 to 1.3) and 1.6 (95% CI 1.3 to 1.8), respectively. CONCLUSION: These findings suggest that an operating time of more than 90 minutes may be an independent predictor of major and minor complications, as well as re-admission, following THA, and that an operating time of between 40 and 90 minutes may be ideal. Prospective studies are required to confirm these findings. Cite this article: Bone Joint J 2019;101-B(6 Supple B):51-56.

Factors associated with health-related quality of life, hip function, and health utility after operative management of femoral neck fractures.

Aims: The primary aim of this prognostic study was to identify baseline factors associated with physical health-related quality of life (HRQL) in patients after a femoral neck fracture. The secondary aims were to identify baseline factors associated with mental HRQL, hip function, and health utility. Patients and Methods: Patients who were enrolled in the Fixation using Alternative Implants for the Treatment of Hip Fractures (FAITH) trial completed the 12-item Short Form Health Survey (SF-12), Western Ontario and McMaster Universities Arthritis Index, and EuroQol 5-Dimension at regular intervals for 24 months. We conducted multilevel mixed models to identify factors potentially associated with HRQL. Results: The following were associated with lower physical HRQL: older age (-1.42 for every ten-year increase, 95% confidence interval (CI) -2.17 to -0.67, p < 0.001); female gender (-1.52, 95% CI -3.00 to -0.05, p = 0.04); higher body mass index (-0.69 for every five-point increase, 95% CI -1.36 to -0.02, p = 0.04); American Society of Anesthesiologists class III ( versus class I) (-3.19, 95% CI -5.73 to -0.66, p = 0.01); and sustaining a displaced fracture (-2.18, 95% CI -3.88 to -0.49, p = 0.01). Additional factors were associated with mental HRQL, hip function, and health utility. Conclusion: We identified several baseline factors associated with lower HRQL, hip function, and utility after a femoral neck fracture. These findings may be used by clinicians to inform treatment and outcomes. Cite this article: Bone Joint J 2018;100-B:361-9.

Wound irrigation does not affect health-related quality of life after open fractures: results of a randomized controlled trial.

AIMS: The Fluid Lavage in Open Fracture Wounds (FLOW) trial was a multicentre, blinded, randomized controlled trial that used a 2 × 3 factorial design to evaluate the effect of irrigation solution (soap versus normal saline) and irrigation pressure (very low versus low versus high) on health-related quality of life (HRQL) in patients with open fractures. In this study, we used this dataset to ascertain whether these factors affect whether HRQL returns to pre-injury levels at 12-months post-injury. PATIENTS AND METHODS: Participants completed the Short Form-12 (SF-12) and the EuroQol-5 Dimensions (EQ-5D) at baseline (pre-injury recall), at two and six weeks, and at three, six, nine and 12-months post-fracture. We calculated the Physical Component Score (PCS) and the Mental Component Score (MCS) of the SF-12 and the EQ-5D utility score, conducted an analysis using a multi-level generalized linear model, and compared differences between the baseline and 12-month scores. RESULTS: We found no clinically important differences between irrigating solutions or pressures for the SF-12 PCS, SF-12 MCS and EQ-5D. Irrespective of treatment, participants had not returned to their pre-injury function at 12-months for any of the three outcomes (p < 0.001). CONCLUSION: Neither the composition of the irrigation solution nor irrigation pressure applied had an effect on HRQL. Irrespective of treatment, patients had not returned to their pre-injury HRQL at 12 months post-fracture. Cite this article: Bone Joint J 2018;100-B:88-94.

Evaluating the critical strain energy release rate of bioactive glass coatings on Ti6Al4V substrates after degradation.

It has been reported that the adhesion of bioactive glass coatings to Ti6Al4V reduces after degradation, however, this effect has not been quantified. This paper uses bilayer double cantilever (DCB) specimens to determine GIC and GIIC, the critical mode I and mode II strain energy release rates, respectively, of bioactive coating/Ti6Al4V substrate systems degraded to different extents. Three borate-based bioactive glass coatings with increasing amounts of incorporated SrO (0, 15 and 25mol%) were enamelled onto Ti6Al4V substrates and then immersed in de-ionized water for 2, 6 and 24h. The weight loss of each glass composition was measured and it was found that the dissolution rate significantly decreased with increasing SrO content. The extent of dissolution was consistent with the hypothesis that the compressive residual stress tends to reduce the dissolution rate of bioactive glasses. After drying, the bilayer DCB specimens were created and subjected to nearly mode I and mode II fracture tests. The toughest coating/substrate system (one composed of the glass containing 25mol% SrO) lost 80% and 85% of its GIC and GIIC, respectively, in less than 24h of degradation. The drop in GIC and GIIC occurred even more rapidly for other coating/substrate systems. Therefore, degradation of borate bioactive glass coatings is inversely related to their fracture toughness when coated onto Ti6A4V substrates. Finally, roughening the substrate was found to be inconsequential in increasing the toughness of the system as the fracture toughness was limited by the cohesive toughness of the glass itself.

Ten-year follow-up study of three alternative bearing surfaces used in total hip arthroplasty in young patients: a prospective randomised controlled trial.

AIMS: We present the ten-year data of a cohort of patients, aged between 18 and 65 years (mean age 52.7 years; 19 to 64), who underwent total hip arthroplasty. Patients were randomised to be treated with a cobalt-chrome (CoCr) femoral head with an ultra-high molecular weight polyethylene (UHMWPE), highly cross-linked polyethylene (XLPE) or ceramic-on-ceramic (CoC) bearing surface. PATIENTS AND METHODS: A total of 102 hips (91 patients) were randomised into the three groups. At ten years, 97 hips were available for radiological and functional follow-up. Two hips (two patients) had been revised (one with deep infection and one for periprosthetic fracture) and three were lost to follow-up. Radiological analysis was performed using a validated digital assessment programme to give linear, directional and volumetric wear of the two polyethylene groups. RESULTS: There was a significantly reduced rate of steady-state linear wear with XLPE (0.07 mm/yr) compared with UHMWPE (0.37 mm/yr) (p = 0.001). Volumetric wear was also significantly reduced in the XLPE group (29.29 mm3/yr) compared with the UHMWPE group (100.75mm3/yr) (p = 0.0001). There were six patients with UHMWPE who had non-progressive osteolysis and none in the XLPE group. All three bearing groups had significant improvements in 12-item short form health survey scores, Western Ontario and McMaster Universities Osteoarthritis Index score and Harris Hip Score. However, the improvement in HSS was significantly less in the UHMWPE group (p = 0.0188) than in the other two groups. At ten years, the rates of volumetric and linear wear in the XLPE group remain low and predominantly below the estimated threshold for osteolysis (1 mm/yr). The rate of linear wear in the XLPE group was three times less than in the UHMWPE group at five-year follow-up and five times less at ten years. The rate of volumetric wear was also three times less in the XLPE group at ten years. CONCLUSION: While CoC also performs well, XLPE at ten years remains a safe and excellent bearing option in young patients, with low rates of wear and no evidence of osteolysis. Cite this article: Bone Joint J 2017;99-B:1590-5.

Quantifying the mode II critical strain energy release rate of borate bioactive glass coatings on Ti6Al4V substrates.

Bioactive glasses have been used as coatings for biomedical implants because they can be formulated to promote osseointegration, antibacterial behavior, bone formation, and tissue healing through the incorporation and subsequent release of certain ions. However, shear loading on coated implants has been reported to cause the delamination and loosening of such coatings. This work uses a recently developed fracture mechanics testing methodology to quantify the critical strain energy release rate under nearly pure mode II conditions, GIIC, of a series of borate-based glass coating/Ti6Al4V alloy substrate systems. Incorporating increasing amounts of SrCO3 in the glass composition was found to increase the GIIC almost twofold, from 25.3 to 46.9J/m2. The magnitude and distribution of residual stresses in the coating were quantified, and it was found that the residual stresses in all cases distributed uniformly over the cross section of the coating. The crack was driven towards, but not into, the glass/Ti6Al4V substrate interface due to the shear loading. This implied that the interface had a higher fracture toughness than the coating itself.

Total hip arthroplasty following failure of core decompression and tantalum rod implantation.

AIMS: One method of femoral head preservation following avascular necrosis (AVN) is core decompression and insertion of a tantalum rod. However, there may be a high failure rate associated with this procedure. The purpose of this study was to document the clinical and radiological outcomes following total hip arthroplasty (THA) subsequent to failed tantalum rod insertion. PATIENTS AND METHODS: A total of 37 failed tantalum rods requiring total hip arthroplasty were identified from a prospective database. There were 21 hips in 21 patients (12 men and nine women, mean age 37 years, 18 to 53) meeting minimum two year clinical and radiographic follow-up whose THAs were carried out between November 2002 and April 2013 (mean time between tantalum rod implantation and conversion to a THA was 26 months, 6 to 72). These were matched by age and gender to individuals (12 men, nine women, mean age 40 years, 18 to 58) receiving THA for AVN without prior tantalum rod insertion. RESULTS: There were no functional outcome differences between the two groups. Tantalum residue was identified on all post-operative radiographs in the tantalum group. Linear wear rates were comparable between groups with no evidence of catastrophic wear in either group. CONCLUSION: In the short term, tantalum rod implantation does not demonstrate an adverse effect on subsequent total joint replacement surgery. There is however, a high rate of retained tantalum debris on post-operative radiographs and thus there is an unknown risk of accelerated articular wear necessitating longer term study. Cite this article: Bone Joint J 2016;98-B:1175-9.

Understanding why people do or do not engage in activities following total joint replacement: a longitudinal qualitative study.

OBJECTIVE: Numerous studies report large and significant improvements in basic mobility and activities of daily living following total hip or knee replacement (TJR). Nevertheless, quantitative research has shown minimal increase in participation in activities that benefit overall health. This study explored why people do or do not engage in activities following hip or knee TJR. METHOD: This was a longitudinal qualitative study. Sampling was guided by constructivist grounded theory and data collected using open-ended, semi-structured interviews. Participants were recruited using maximum variation sampling based on age, sex and joint replaced (hip or knee). Data were analysed using a constant comparative approach and coded for thematic patterns and relationships from which overarching themes were constructed. RESULTS: Twenty-nine patients participated in interviews prior to, and 8 and 18 months post following TJR. A high degree of variability with regard to participants' return to activities was found and five emergent themes were identified that accounted for this variability. These themes highlight the importance of issues beyond medical factors alone, such as socio-cultural factors that partially determine participants' participation in activity following TJR. CONCLUSION: Findings suggest that multi-faceted experiences impact participation in activity following TJR. These experiences include changes in identity and lifestyle that preclude a 'return to normal'. There is an urgent need for supports to increase people's activity post-TJR in order to facilitate enhancement of post-surgery levels of engagement. Approaches that take into consideration more personalized interventions may be critical to promoting healthy aging in people with TJR.

Co-morbidities in elderly patients with hip fracture: recommendations of the ISFR-IOF hip fracture outcomes working group.

INTRODUCTION: Hip fractures are the second leading cause of hospitalization in the aged and by 2041, epidemiologists forecast an increase in economic cost to $2.4 billion. The hip patient population often presents with comorbidities causing these patients to receive less aggressive medical treatment and have a low quality of life. We believe that physical function is a patient-important outcome for many medical and surgical interventions. The functional co-morbidity index (FCI), unlike prior co-morbidity indices, was developed with physical function as an outcome instead of being designed for administrative purposes or to predict mortality. Our objective was to evaluate the perceptions of practitioners in hip fracture care about the impact of comorbidities on physical function as primary outcome. METHODS: We piloted and then distributed a self-administered survey to members of the International Society for Fracture Repair hip fracture outcomes working group. For each of the 18 diagnoses included in the FCI index, we asked in our survey whether the presence of the co-morbidity and whether the severity of the co-morbidity was perceived to impact physical function in patients following a hip fracture. RESULTS: Seventeen out of 20 respondents completed the questionnaire. The presence and severity of arthritis was 'strongly' believed to predict physical function in those with hip fracture (69 and 85.7 %, respectively). Respondents 'agreed' (range 53-73 %) that 10/18 diagnoses would predict changes in physical function following hip fracture treatment. Whereas, 63 % of the practitioners'strongly disagreed' that diabetes types I and II would change physical function scores. Furthermore, dementia was listed as an additional diagnosis that would affect physical function. CONCLUSION: The FCI may provide a useful instrument to predict functional outcome after hip fracture; however, the index may need to be modified for this specific population.

Understanding osteoporosis and fractures: an introduction to the use of qualitative research.

BACKGROUND: Qualitative research has been recognized in recent years as a field of inquiry used to understand people's beliefs, attitudes, behaviors, culture or lifestyle. While quantitative results are challenging to apply in everyday practice, the qualitative paradigm can be useful to fill in a research context that is poorly understood or ill-defined. It can provide an in-depth study of interactions, a way to incorporate context, and a means to hear the voices of participants. Understanding experiences, motivation, and beliefs can have a profound effect on the interpretation of quantitative research and generating hypotheses. In this paper, we will review different qualitative approaches that healthcare providers and researchers may find useful to implement in future study designs, specifically in the context of osteoporosis and fracture. METHODS: We will provide insight into the qualitative paradigm gained from the osteoporosis literature on fractures using examples from the database Scopus. Five prominent qualitative techniques (narratives, phenomenology, grounded theory, ethnography, and case study) can be used to generate meanings of the social and clinical world. DISCUSSION AND CONCLUSION: We have highlighted how these strategies are implemented in qualitative research on osteoporosis and fractures and are anchored to specific methodological practices. We focus on studies that explore patient psychosocial experiences of diagnosis and treatment, cultural boundaries, and interprofessional communication. After reviewing the research, we believe that action research, that is not frequently used, could also effectively be used by many professions to improve programs and policies affecting those dealing with osteoporosis issues.

The importance of perceived helplessness and emotional health in understanding the relationship among pain, function, and satisfaction following revision knee replacement surgery.

OBJECTIVE: Little is known about the relationships among pain, function, psychological variables like perceived helplessness and emotional health, and patient satisfaction in people with revision knee replacement surgery. We hypothesized that pain and function would have a direct association with satisfaction as well as an indirect association through patient perceptions of helplessness and emotional health. DESIGN: This longitudinal study included 145 participants undergoing revision knee replacement surgery. Demographic data and expectation of benefit from surgery were recorded prior to surgery. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the Arthritis Helplessness Scale (AHS) and the Mental Component Scale (MCS) of the SF-36 (emotional health) were collected prior to and 2 years post-surgery. Satisfaction was recorded 2 years post-surgery. Regression analyses were conducted to test for mediation effects of helplessness and MCS. RESULTS: Participants were on average 69 years old and 54% were women. Participants were satisfied with the results of the surgery (mean ± standard deviation (SD) = 70.42 ± 31.46). Less pain and functional disability were associated with increased patient satisfaction and, the effect of pain or function was also mediated through helplessness whereby more pain and disability were associated with perceptions of helplessness and helplessness was associated with lower satisfaction. MCS did not mediate the relationship of pain and function with satisfaction. CONCLUSION: Helplessness plays an important role in understanding patient satisfaction. Interventions aimed at improving patient outcome should target not only pain and function but also should address strategies to support people in managing following knee revision surgery to maximize satisfaction with outcome.

Latissimus dorsi tendon transfer for irreparable tears of the rotator cuff: An anatomical study to assess the neurovascular hazards and ways of improving tendon excursion.

Latissimus dorsi tendon transfer (LDTT) is technically challenging. In order to clarify the local structural anatomy, we undertook a morphometric study using six complete cadavers (12 shoulders). Measurements were made from the tendon to the nearby neurovascular structures with the arm in two positions: flexed and internally rotated, and adducted in neutral rotation. The tendon was then transferred and measurements were taken from the edge of the tendon to a reference point on the humeral head in order to assess the effect of a novel two-stage release on the excursion of the tendon. With the shoulder flexed and internally rotated, the mean distances between the superior tendon edge and the radial nerve, brachial artery, axillary nerve and posterior circumflex artery were 30 mm (26 to 34), 28 mm (17 to 39), 21 mm (12 to 28) and 15 mm (10 to 21), respectively. The mean distance between the inferior tendon edge and the radial nerve, brachial artery and profunda brachii artery was 18 mm (8 to 27), 22 mm (15 to 32) and 14 mm (7 to 21), respectively. Moving the arm to a neutral position reduced these distances. A mean of 15 mm (8 to 21) was gained from a standard soft-tissue release, and 32 mm (20 to 45) from an extensile release. These figures help to define further the structural anatomy of this region and the potential for transfer of the latissimus dorsi tendon.

A prospective randomised controlled trial comparing three alternative bearing surfaces in primary total hip replacement.

The ideal bearing surface for young patients undergoing total hip replacement (THR) remains controversial. We report the five-year results of a randomised controlled trial comparing the clinical and radiological outcomes of 102 THRs in 91 patients who were < 65 years of age. These patients were randomised to receive a cobalt-chrome on ultra-high-molecular-weight polyethylene, cobalt-chrome on highly cross-linked polyethylene, or a ceramic-on-ceramic bearing. In all, 97 hip replacements in 87 patients were available for review at five years. Two hips had been revised, one for infection and one for peri-prosthetic fracture. At the final follow-up there were no significant differences between the groups for the mean Western Ontario and McMaster Universities osteoarthritis index (pain, p = 0.543; function, p = 0.10; stiffness, p = 0.99), Short Form-12 (physical component, p = 0.878; mental component, p = 0.818) or Harris hip scores (p = 0.22). Radiological outcomes revealed no significant wear in the ceramic group. Comparison of standard and highly cross-linked polyethylene, however, revealed an almost threefold difference in the mean annual linear wear rates (0.151 mm/year versus 0.059 mm/year, respectively) (p < 0.001).

The biomechanics of plate fixation of periprosthetic femoral fractures near the tip of a total hip implant: cables, screws, or both?

Femoral shaft fractures after total hip arthroplasty (THA) remain a serious problem, since there is no optimal surgical repair method. Virtually all studies that examined surgical repair methods have done so clinically or experimentally. The present study assessed injury patterns computationally by developing three-dimensional (3D) finite element (FE) models that were validated experimentally. The investigation evaluated three different constructs for the fixation of Vancouver B1 periprosthetic femoral shaft fractures following THA. Experimentally, three bone plate repair methods were applied to a synthetic femur with a 5 mm fracture gap near the tip of a total hip implant. Repair methods were identical distal to the fracture gap, but used cables only (construct A), screws only (construct B), or cables plus screws (construct C) proximal to the fracture gap. Specimens were oriented in 15 degrees adduction to simulate the single-legged stance phase of walking, subjected to 1000 N of axial force, and instrumented with strain gauges. Computationally, a linearly elastic and isotropic 3D FE model was developed to mimic experiments. Results showed excellent agreement between experimental and FE strains, yielding a Pearson linearity coefficient, R2, of 0.92 and a slope for the line of best data fit of 1.06. FE-computed axial stiffnesses were 768 N/mm (construct A), 1023 N/mm (construct B), and 1102 N/mm (construct C). FE surfaces stress maps for cortical bone showed Von Mises stresses, excluding peaks, of 0-8 MPa (construct A), 0-15 MPa (construct B), and 0-20 MPa (construct C). Cables absorbed the majority of load, followed by the plates and then the screws. Construct A yielded peak stress at one of the empty holes in the plate. Constructs B and C had similar bone stress patterns, and can achieve optimal fixation.

The biomechanics of plate repair of periprosthetic femur fractures near the tip of a total hip implant: the effect of cable-screw position.

Optimal surgical positioning of cable-screw pairs in repairing periprosthetic femur fractures near the tip of a total hip implant still remains unclear. No studies in the literature to date have developed a fully three-dimensional finite element (FE) model that has been validated experimentally to assess these injury patterns. The aim of the present study was to evaluate the biomechanical performance of three different implant-bone constructs for the fixation of periprosthetic femoral shaft fractures following total hip arthroplasty. Experimentally, three bone-plate repair configurations were applied to the periprosthetic synthetic femur fractured with a 5 mm gap near the tip of a total hip implant. Constructs A, B, and C, respectively, had successively larger distances between the most proximal and the most distal cable-screw pairs used to affix the plate. Specimens were oriented in 15 degrees adduction, subjected to 1000 N of axial force to simulate the single-legged stance phase of walking, and instrumented with strain gauges. Computationally, a linearly elastic and isotropic three-dimensional FE model was developed to mimic the experimental setup. Results showed excellent agreement between experimental versus FE analysis strains, yielding a Pearson linearity coefficient, R2, of 0.90 and a slope for the line of best data fit of 0.96. FE axial stiffnesses were 601 N/mm (Construct A), 849 N/mm (Construct B), and 1359 N/mm (Construct C). FE surface stress maps for cortical bone showed maximum von Mises values of 74 MPa (Construct A), 102 MPa (Construct B), and 57 MPa (Construct C). FE stress maps for the metallic components showed minimum von Mises values for Construct C, namely screw (716MPa), cable (445MPa), plate (548MPa), and hip implant (154MPa). In the case of good bone stock, as modelled by the present synthetic femur model, optimal fixation can be achieved with Construct C.

The trajectory of recovery and the inter-relationships of symptoms, activity and participation in the first year following total hip and knee replacement.

OBJECTIVE: Primary total hip (THR) and knee (TKR) replacement outcomes typically include pain and function with a single time of follow-up post-surgery. This research evaluated the trajectory of recovery and inter-relationships within and across time of physical impairments (PI) (e.g., symptoms), activity limitations (AL), and social participation restrictions (PR) in the year following THR and TKR for osteoarthritis. DESIGN: Participants (hip: n=437; knee: 494) completed measures pre-surgery and at 2 weeks, 1, 3, 6 and 12 months post-surgery. These included PI (Hip Disability and Osteoarthritis Outcome Score (HOOS)/Knee Injury and Osteoarthritis Outcome Score (KOOS) symptoms and Chronic Pain Grade); AL (HOOS/KOOS activities of daily living and sports/leisure activities); and, PR (Late Life Disability and the Calderdale community mobility). Repeated measures analysis of variance (RANOVA) was used to evaluate the trajectory of recovery of outcomes and the inter-relationships of PI, AL and PR were evaluated using path analysis. All analyses were adjusted for age, sex, obesity, THR/TKR, low back pain and mood. RESULTS: THR: age 31-86 years with 55% female; TKR: age 35-88 years with 65% female. Significant improvements in outcomes were observed over time. However, improvements were lagged over time with earlier improvements in PI and AL and later improvements in PR. Within and across time, PI was associated with AL and AL was associated with PR. The magnitude of these inter-relationships varied over time. CONCLUSION: Given the lagged inter-relationship of PI, AL and PR, the provision and timing of interventions targeting all constructs are critical to maximizing outcome. Current care pathways focusing on short-term follow-up with limited attention to social and community participation should be re-evaluated.