Hip Replacement Surgery Research Articles

Advanced Multi-Layer Watertight Closure versus Conventional Closure in Total Hip and Knee Replacement Surgery.

In total joint replacement procedures, surgeons have increasingly adopted advanced multi-layer, watertight closure. The objective of the study was to compare the clinical and economic outcomes for advanced multi-layer, watertight closure patients to those with conventional closure with sutures and skin staples. Patients aged ≥18 years were included in the study if they underwent total joint arthroplasty of the hip or knee as an elective, primary, inpatient procedure between January 2014 and March 2019. Cohorts having advanced multi-layer, watertight closure or conventional closure were compared using multivariable regression analysis of surgical site infections, length of stay, operating room time, procedure time, discharge status, readmissions, reoperations, and hospital emergency department visits. A total of 1828 patients received at least one total hip or knee replacement, of which 434 (23.7%) had advanced multi-layer, watertight closure and 1394 (76.3%) had conventional closure. Unadjusted time to readmission, when occurring, was considerably longer following advanced multi-layer, watertight closure (89.9 vs 51.1 days, p < 0.0001), and a lower proportion of the advanced multi-layer, watertight closure cohort required reoperation within 90 days (0.0% vs 2.6%, p < 0.0001). Adjusted mean hospital length of stay was approximately half of a day shorter for advanced multi-layer, watertight closure patients (1.10 vs 1.65 days; p < 0.001), and they were also more likely to be discharged to home (Odds Ratio: 4.61; p = 0.002). Among patients undergoing total hip and knee arthroplasty in a highly optimized real-world clinical practice, advanced multi-layer, watertight closure was associated with significantly shorter inpatient length of stay and increased likelihood of being discharged to home compared with conventional closure. These findings suggest that advanced multi-layer, watertight closure is a valuable component of an optimal workflow for total hip or knee replacement, and may be especially valuable for high-risk patients.

When is vancomycin prophylaxis necessary? Risk factors for MRSA surgical site infection.

The 2022 SHEA/IDSA/APIC guidance for surgical site infection (SSI) prevention recommends reserving vancomycin prophylaxis to patients who are methicillin-resistant Staphylococcus aureus (MRSA) colonized. Unfortunately, vancomycin prophylaxis remains common due to the overestimation of MRSA risk and the desire to cover MRSA in patients with certain healthcare-associated characteristics. To optimize vancomycin prophylaxis, we sought to identify risk factors for MRSA SSI. This was a single-center, case-control study of patients with a postoperative SSI after undergoing a National Healthcare Safety Network operative procedure over eight years. MRSA SSI cases were compared to non-MRSA SSI controls. Forty-two demographic, medical, and surgical characteristics were evaluated. Of the 441 patients included, 23 developed MRSA SSIs (rate = 5.2 per 100 SSIs). In the multivariable model, we identified two independent risk factors for MRSA SSI: a history of MRSA colonization or infection (OR, 9.0 [95% CI, 1.9-29.6]) and hip or knee replacement surgery (OR, 3.8 [95% CI, 1.3-9.9]). Hemodialysis, previous hospitalization, and prolonged hospitalization prior to the procedure had no measurable association with odds of MRSA SSI. Patients with prior MRSA colonization or infection had 9-10 times greater odds of MRSA SSI and patients undergoing hip and knee replacement had 3-4 times greater odds of MRSA SSI. Healthcare-associated characteristics, such as previous hospitalization or hemodialysis, were not associated with MRSA SSI. Our findings support national recommendations to reserve vancomycin prophylaxis for patients who are MRSA colonized, as well as those undergoing hip and knee replacement, in the absence of routine MRSA colonization surveillance.

Results of Total Hip Replacement Surgery Using Short-Stem Spiron Prosthesis in Vietnamese Adults.

Total hip arthroplasty with traditional stem joints, although bringing many benefits to patients indicated for hip replacement, faces many difficulties in reoperations in young patients due to the limited lifespan of the artificial joint. Recently, the short-stem joint was introduced to help overcome this problem. This study aims to evaluate the results of short-stem implants for primary total hip arthroplasty in Vietnamese adults. The study design is retrospective longitudinal. The study subjects were 91 patients with aseptic necrosis of the femoral head who underwent short-shaft cementless total hip replacement surgery from February 2012 to December 2018. Outcomes that were assessed included implant survivorship, Harris hip scores, thigh pain, periprosthetic fracture, subsidence, proximal stress shielding, the prevalence of stem malalignment, and inappropriate implant sizing. Our research group has 119 hips of 91 patients (28 patients had hip replacements on both sides), with the average follow-up time of 67.1 months. Seven cases of early joint loosening required replacing the traditional stem. The survival rate is 94.1%. The average Harris hip score 24 months after surgery was statistically significantly higher than before (92.00 ± 4.47 and 45.56 ± 3.22, respectively, p < 0.001). The average leg length discrepancy between the two limbs before surgery was 9.5 ±mm and 24 months after surgery was 3.4 ± 2.9 mm. There were 12 cases (10.1%) of partial bone loss around the femoral stem; 12 cases of joint displacement of more than 2 mm, accounting for 10.1%; and 1 case of acetabular fracture, accounting for 0.8%. The Spiron short stem has certain advantages suitable for young patients, restoring the hip anatomy and significantly improving postoperative hip function. However, this is a complex technique that needs to be performed by experienced surgeons who have practiced for a long time. We encourage using the short-stem implant during primary total hip arthroplasty in Vietnamese adult patients.

Trends in revision hip replacement surgery - a 21-year review of the New Zealand Joint Registry

Introduction: This study aimed to examine the changing trends in the reasons for total hip replacement (THR) revision surgery, in one country over a twenty-one-year period, in order to assess whether changes in arthroplasty practices have impacted revision patterns and whether an awareness of these changes can be used to guide clinical practice and reduce future revision rates. Methods: The reason for revision THR performed between January 1999 and December 2019 was extracted from the New Zealand Joint Registry (NZJR). The results were then grouped into seven 3-year periods to allow for clearer visualization of trends. The reasons were compared across the seven time periods and trends in prosthesis use, patient age, gender, body mass index (BMI) and American Society of Anesthesiologist (ASA) grade were also reviewed. We compared the reasons for early revision, within one year, with the overall revision rates. Results: There were 20,740 revision THR registered of which 7665 were revisions of hips with the index procedure registered during the 21-year period. There has been a statistically significant increase in both femoral fracture (4.1 - 14.9%, p&lt;0.001) and pain (8.1 - 14.9%, p&lt;0.001) as a reason for hip revision. While dislocation has significantly decreased from 57.6% to 17.1% (p&lt;0.001). Deep infection decreased over the first 15 years but has subsequently seen further increases over the last 6 years. Conversely both femoral and acetabular loosening increased over the first 12 years but have subsequently decreased over the last 9 years. The rate of early revisions rose from 0.86% to 1.30% with a significant rise in revision for deep infection (13-33% of all causes, p&lt;0.001) and femoral fracture (4-18%, p&lt;0.001), whereas revision for dislocation decreased (59-30%, p&lt;0.001). Adjusting for age and gender femoral fracture and deep infection rates remained significant for both (p&lt;0.05). Adjusting for age, gender and ASA was only significant for infection. Conclusions: The most troubling finding was the increased rate of deep infection in revision THR, with no obvious linked pattern, whereas the reduction in revision for dislocation, aseptic femoral and acetabular loosening can be linked to the changing patterns of the use of larger femoral heads and improved bearing surfaces.

Morphological and Morphometric Variations of Fovea Capitis Femoris: A Cross-sectional Study from Kolkata, West Bengal, India

Introduction: The proximal end of the femur is an important anatomical modification in humans, widely explored to acquire detailed knowledge that aids in determining the exact size of hip prosthesis and minimising postoperative complications. However, thorough analysis of the various parameters of the Fovea Capitis Femoris (FCF) is frequently overlooked, yet it is also important during reconstructive surgery of the ligamentum teres femoris, radiographic evaluation of hip dysplasia, or as an anatomical landmark in hip arthroscopy. Detailed morphological and morphometric measurements of the FCF in the West Bengal population would help bridge this gap, as there are few Indian studies regarding the fovea. Aim: To determine the morphological and morphometric measurements of the FCF in the West Bengal population. Materials and Methods: A cross-sectional study was conducted among 297 dry femora from the Department of Anatomy at Kolkata Medical College, Kolkata, West Bengal, India from October 2023 to February 2024. The position and shape of the fovea were recorded. Morphometric measurements of the fovea (depth, transverse diameter, and vertical diameter) and the head of the femur (transverse and vertical diameters) were taken using a vernier caliper. The collected data were compiled in a Microsoft Excel sheet and analysed using Jamovi software (free version). The Pearson’s correlation formula was used to determine the correlation between various parameters of the fovea and femoral head. A p-value of &lt;0.05 was considered statistically significant. Results: All femora had a single distinct fovea. The most frequent shape of the fovea was oval 135 (45.45%), and its most common position was in the posterior-inferior quadrant 263 (88.55%) of the femoral head. Regarding morphometric measurements, the mean values of the transverse diameter, vertical diameter, and Depth of the Fovea (DF) were 1.53±0.367 cm, 1.28±0.303 cm, and 0.304±0.141 cm, respectively. A positive correlation was found between the transverse and vertical diameters of the fovea (Pearson’s correlation r=0.239), and a significant p-value (p&lt;0.001) was also found between them. Conclusion: Knowledge of these variations may be useful for anatomists, radiologists, anthropologists, forensic experts, and orthopaedic surgeons when planning and executing hip replacement surgeries.

Neuromonitoring in pre-post and intraoperative total hip replacement surgery in type 4 high-riding developmental dysplasia of the hip.

The choice approach to treating congenital dislocation of the hip joint is total hip replacement (THR). One of the severe but uncommon complications of THR is nerve damage. The most common nerve injury associated with total hip arthroplasty (THA) is sciatic nerve palsy, and the second typical nerve damage with THA is femoral nerve paralysis. In this prospective cohort study, 35 patients with type 4 high riding developmental dysplasia of the hip (DDH) who were candidates for THA were enrolled. The somatosensory evoked potential (SSEP), motor evoked potential (MEP), and electromyography (EMG) were measured pre-post and intraoperatively to check the status of the sciatic and femoral nerves. After collecting the mentioned information, the data was analyzed by SPSS V. 26 software. Out of 35 patients with DDH type 4 who were candidates for THR, nine patients showed a 50 percent decrease in SSEP amplitude, and six patients showed a 10 percent decrease in SSEP latency. One patient during and two patients after the surgery showed more than an 80 percent decrease in MEP amplitude. Meanwhile, 14 patients showed abnormal spikes during and two patients after surgery regarding EMG. All patients with disturbed neurophysiological findings reverted to normal in the further investigation during follow-up. No correlation was found between increasing limb shortness and these modalities. Using neuromonitoring techniques during Total Hip Arthroplasty (THA) can help identify potential early nerve damage, prevent post-surgical complications, and improve high-riding DDH patient outcomes.

Trends in revision hip replacement surgery - a 21-year review of the New Zealand Joint Registry

Trends in revision hip replacement surgery - a 21-year review of the New Zealand Joint Registry

Early hip fracture surgery and rehabilitation. How to improve functional quality outcomes. A retrospective study.

Hip fractures are one of the major disability causes associated with a high morbidity and mortality rate. Early surgery and stable fixation could be associated with better pain control, possibly lower mortality rates, and early recovery of autonomy.

Robotic-assisted burring in total hip replacement: A new surgical technique to optimise acetabular preparation.

In Total Hip replacement (THR) surgery, a critical step is to cut an accurate hemisphere into the acetabulum so that the component can be fitted accurately and obtain early stability. This study aims to determine whether burring rather than reaming the acetabulum can achieve greater accuracy in the creation of this hemisphere. A preliminary robotic system was developed to demonstrate the feasibility of burring the acetabulum using the Universal Robot (UR10). The study will describe mechanical design, robot trajectory optimisation, control algorithm development, and results from phantom experiments compared with both robotic reaming and conventional reaming. The system was also tested in a cadaver experiment. The proposed robotic burring system can produce a surface in 2min with an average error of 0.1 and 0.18mm, when cutting polyurethane bone block #15 and #30, respectively. The performance was better than robotic reaming and conventional hand reaming. The proposed robotic burring system outperformed robotic and conventional reaming methods to produce an accurate acetabular cavity. The findings show the potential usage of a robotic-assisted burring in THR for acetabular preparation.

Vehicular homicide or cardiovascular event? The importance of the autopsy findings

We present the case of a 61 years old woman who was hit by a car, resulting in fractures of the pubic bone, left ischium-pubis ramus and right femur, with need of hip replacement surgery. In the next days she was affected by two episodes of acute coronary syndrome, treated with coronary angioplasty surgery. After undergoing total hip replacement surgery an episode of asystole caused her death. A full autopsy showed coronary stenosis and chronic ischemic heart disease associated with a recent myocardial infarction. The pre-existing condition of T.L. could not be ignored but the initial traumatic event and the subsequent fractures played a further co-occurrent causal role. The initial trauma represented the first step of the phenomenological chain that led to a series of adverse cardiological events and to an irreversible asystole, so that the car driver should be partly considered accountable for the death of the woman.

Vancomicina en polvo en la prevención de la infección en artroplastia primaria de rodilla y cadera: estudio de casos y controles con 1.151 artroplastias

Background and objectiveVancomycin powder (VP) has been positively used in spinal surgery to reduce the rate of infections. Hardly any data have been published on hip and knee joint replacement surgery, and its usefulness is questioned. Our objective was to investigate the effectiveness of VP in reducing prosthetic infection and its possible complications. MethodsPrimary hip (THA) and knee (TKA) arthroplasties were reviewed, performed by five surgeons in one hospital center, between 2017 and 2018. 1g of VP was used on the implant prior to surgical closure based on the surgeon's preferences. With a 5-year follow-up in which the infection rate and local complications were analyzed. ResultsOne thousand one hundred and fifty one arthroplasties were performed, 748 were TKA and 403 were THA. Nine patients were diagnosed with prosthetic infection, of which five received VP and four did not (P=.555). Likewise, another 15 patients suffered wound complications, of which 11 received VP and 4 did not (P=.412). There were no differences, either, in the rest of the complications depending on the use or not of VP (P=.101). Likewise, the number of patients who needed reintervention was similar (P=.999).No systemic complications were detected due to the use of VP. ConclusionsIt has not been possible to demonstrate that the use of VP reduces the rates of prosthetic infection in the hip and knee, so we cannot recommend its use.

Anesthesia in Low Ejection Fraction Patient : Case Report

Ejection fraction (EF) is the percentage of the difference between the end-diastolic volume and the end-systolic volume divided by the end-diastolic volume. This measurement is important in determining how well the heart is pumping out blood and in diagnosing heart failure (HF). Normally the percentage of EF is above 50%. A decrease in EF will make it difficult to perform anesthesia during surgery due to life-threatening irregular heartbeats, leading to sudden cardiac arrest and sudden death. Patients with a very low ejection fraction require identification of risk factors, preoperative evaluation and optimization, medical therapy, monitoring, and appropriate anesthetic technique and drugs. In this report, we present a 67-year-old woman with HFmrEF (estimated ejection fraction 46%) and coronary artery disease who underwent partial hip replacement surgery under general anesthesia. General anesthesia was performed on the patient and induction used fentanyl, midazolam, and atracurium. Management of patients is aimed at maintaining cardiac output and avoiding myocardial depression by maintaining a balance between oxygen supply and demand. Therefore good anesthetic management is needed to maintain the hemodynamic stability of the patient.

Assessing socio-economic damage caused by coxarthrosis in the population

Background. About 40 % of patients diagnosed with coxarthrosis annually seek medical help and receive social support due to this disease. Increased use of an expensive surgery for treatment of coxarthrosis and projected growth of its prevalence in the population determine the relevance of socio-economic analysis. The aim of the study. To assess the value and structure of economic damage caused by the delivering health and social care to patients with coxarthrosis at the state level of the Russian Federation. Methods. To assess economic damage, we used the average annual number of various categories of patients and disabled people with coxarthrosis in the Irkutsk region for 2008–2017. Three main categories were identified: patients who visited the outpatients’ clinic; patients with total hip replacement; disabled people due to coxarthrosis. For each category, we calculated weighted average damage per 1 conventional patient, taking into account direct and indirect costs and subsequent multiplication by the average annual number of individual categories of patients. Calculations were performed in 2017 prices. Results. The average annual socio-economic damage from coxarthrosis amounted to 1.39 (1.34÷1.43) billion rubles or 0.1 % of the gross regional product. The most of the damage (64.4 %) were indirect costs associated with disability due to coxarthrosis, 22.2 % of the total amount were the costs of hip replacement surgery, 13.4 % were the costs of outpatient visits. Indirect economic losses due to disability in patients of working age were 4.2 times higher than losses due to disability of oldage pensioners. Conclusion. The results of the study confirm the economic feasibility of surgical treatment of coxarthrosis, especially in patients of working age.

PREOPERATIVE ANXIETY STATUS OF PATIENTS WITH HIP AND KNEE REPLACEMENT SURGERY

Objectives: This study was conducted to estimate the prevalence of preoperative anxiety status and find out some related factors in hip and knee replacement patients at the Department of Orthopedic Surgery and Sports Medicine, Hanoi Medical University Hospital. Subjects and Methods: A cross-sectional study recruited 102 patients scheduled for hip and knee replacement surgery. The research was conducted from June to September 2022. Preoperative anxiety status was measured by the Hospital Anxiety and Depression Scale (HADS). Results: The population ages varied from 22 to 92 years (mean age=62.11 ± 15.35 years). Nearly half of patients (48%) experienced preoperative anxiety ranging from mild to severe, with a mean HADS score was 7.21±3.13, and 32% of patients had mild anxiety. Surgical types and gender associated with preoperative anxiety status. The proportion of patients who reported being afraid of intra- and/ or postoperative complications, postoperative disabilities, and the pain was 80.4%, 65.7%, and 58.8%, respectively. Conclusion: The proportion of hip and knee replacement surgery patients who experienced preoperative anxiety was high. Surgical types and gender were significantly associated with the preoperative anxiety status of hip and knee replacement surgery patients (p&lt;0.05).

Predicting the development of hemophilic arthropathy in patients with hemophilia based on patient age: a retrospective single-center database study

ABSTRACT Background Patients with hemophilia (PWH) develop hemophilic arthropathy of the major joints due to recurrent hemarthrosis. This study retrospectively estimated the age at which PWH may expect to develop hemophilic arthropathy and undergo joint replacement surgery. Research design and methods Using retrospective data from PWH at a Czech orthopedic center, Kaplan Meier analyses were used to estimate the cumulative proportions of patients with hemophilic arthropathy and undergoing joint replacement surgery as a function of age. Results Based on 1028 joint examinations in 167 PWH, hemophilic arthropathy of the knees, elbows, ankles and hips was estimated to develop by a median age of 48, 51, 52 and 61 years, respectively, with ≈80% of patients having such damage by ≈70 years of age. Hemophilic arthropathy of the shoulder occurred much later (median >80 years). In patients undergoing knee or hip replacement surgery, hemophilic arthropathy of the knee and hip occurred at a median age of ≈50 and ≈60 years, respectively, with replacement surgery occurring at a median of ≈70 and >75 years. Conclusions In PWH, the risk of developing hemophilic arthropathy accumulates continuously over the patient’s lifetime, allowing predictions about the ages at which such damage and joint replacement surgery may occur.

Trabecular, but not cortical, bone tissue protein synthesis rates are lower in the femoral head when compared to the proximal femur following an intracapsular hip fracture.

All musculoskeletal tissues are in a constant state of turnover, with a dynamic equilibrium between tissue protein synthesis and breakdown rates. The synthesis of protein allows musculoskeletal tissues to heal following injury. Yet, impaired tissue healing is observed following certain injuries, such as geriatric hip fractures. It is assumed that the regenerative properties of femoral head bone tissue are compromised following an intracapsular hip fracture and therefore hip replacement surgery is normally performed. However, the actual impact on in vivo bone protein synthesis rates has never been determined. In the present study, 10 patients (age: 79±10 y, BMI: 24±4kg/m2) with an acute (<24h) intracapsular hip fracture received a primed continuous intravenous infusion of L-[ring-13C6]-phenylalanine before and throughout their hip replacement surgery. Trabecular and cortical bone tissue from both the femoral head and proximal femur were sampled during surgery to assess protein synthesis rates of affected (femoral head) and unaffected (proximal femur) bone tissue, respectively. In addition, tissue samples of gluteus maximus muscle, synovium, ligamentum teres, and femoral head cartilage were collected. Tissue-specific protein synthesis rates were assessed by measuring L-[ring-13C6]-phenylalanine incorporation in tissue protein. Femoral head trabecular bone protein synthesis rates (0.056 [0.024-0.086] %/h) were lower when compared to proximal femur trabecular bone protein synthesis rates (0.081 [0.056-0.118] %/h; P=0.043). Cortical bone protein synthesis rates did not differ between the femoral head and proximal femur (0.041 [0.021-0.078] and 0.045 [0.028-0.073] %/h, respectively; P>0.05). Skeletal muscle, synovium, ligamentum teres, and femoral head cartilage protein synthesis rates averaged 0.080 [0.048-0.089], 0.093 [0.051-0.130], 0.121 [0.110-0.167], and 0.023 [0.015-0.039] %/h, respectively. In contrast to the general assumption that the femoral head is avital after an intracapsular displaced hip fracture in the elderly, our data show that bone protein synthesis is still ongoing in femoral head bone tissue during the early stages following an intracapsular hip fracture in older patients. Nonetheless, trabecular bone protein synthesis rates are lower in the femoral head when compared to the proximal femur in older patients following an acute intracapsular hip fracture. Trial register no: NL9036.

What if an articular bone fragment drops on the floor in the course of osteosynthesis? An experimental study.

This study aimed to evaluate the effectiveness of a 1-min 10% povidone-iodine immersion in the decontamination of dropped osteochondral fragments. Forty-eight sets of sterile osteochondral bone fragments, each consisting of three samples, were prepared from removed femoral heads that would otherwise be discarded during different hip replacement surgeries. Immediately afterward, each set was dropped on the floor right behind the surgeon in another operating room in which fracture fixation operations were being performed. Samples were picked up with sterile gloves. A swab culture of the floor was taken. One of the three pieces was kept as the control group. The second one (saline group) was washed with saline and subsequently soaked in saline for 1 min. The last one (treatment group) was first immersed in a 10% povidone-iodine solution for 1 min, then rinsed with saline and soaked in saline for 1 min. The samples were cultured in nutrient media, and microorganisms were identified at the microbiology laboratory. The groups were compared in terms of positive culture rates. The positive culture (contamination) rates were 100%, 58.3%, 39.6%, and 10.4% for the swab samples, control group, saline group, and treatment group respectively. The decontamination ratio in the treatment group was significantly more than both the control group (p<0.001) and the saline group (p=0.001). Handling only with saline did not significantly decontaminate compared to the control group (p=0.066). Immersing the dropped osteochondral fragments in 10% povidone-iodine solution for 1 min and then rinsing with saline may provide statistically significant decontamination but cannot be accepted to be safe enough for clinical practice. Further studies are needed to find the optimal time needed for safe decontamination without compromising the viability of cartilage tissue.

Qualitative and quantitative analysis of post-operative drainage: pilot study.

Surgical drains can be placed after an operation to collect postoperative blood loss. However, these could be overestimated. Indeed, the fluid elapsed after the first postoperative day would no longer be pure blood. An early withdrawal of redon could then be considered. A monocentric prospective study of 25 patients undergoing total knee or primary hip replacement surgery, for osteo-arthritis, was conducted. Redon flow was evaluated in total volume and in composition by the sedimentation study. A qualitative analysis of the content of the redon was also carried out. To compare the elements found in the drained liquid with the blood data, a preoperative and two postoperative blood samples were taken. 18 TKA and 7 THA were included. A qualitative analysis of the postoperative flow of 11 TKA and 5 THA was requested. Decreases of sedimentation volumes and protein levels were found in the drained liquid compared to the blood for both TKA and THA. Our results tend to prove that on postoperative D1, the liquid drained in the redon would be blood, but that the liquid drained on D2 and D3 would be a mixture of blood and serum. Therefore, the real postoperative blood loss would be overestimated.

The impact of restricted provision of publicly funded elective hip and knee joints replacement during the COVID-19 pandemic in England.

Elective hip and knee replacement operations were suspended in April 2020 due to the COVID-19 pandemic. The impact of this suspension and continued disruption to the delivery of joint replacement surgery is still emerging. We describe the impact of the pandemic on the provision of publicly funded elective hip and knee replacement surgery at one teaching hospital in England and on which patients had surgery. We included all elective primary and revision hip and knee replacements performed at one hospital between January 2016 and June 2021. Using data for the years 2016-2019, we estimated the expected number of operations and beds occupied per month in January 2020 to June 2021 using time series linear models (adjusting for season and trend). We compared the predictions with the real data for January 2020 to June 2021 to assess the impact of the pandemic on the provision of elective hip and knee replacements. We compared the length of stay and characteristics (age, gender, number of comorbidities, index of multiple deprivation) of patients who had surgery before the pandemic with those who had surgery during the pandemic. We included 6,964 elective primary and revision hip and knee replacements between January 2016 and June 2021. Between January 2020 and June 2021 primary hip replacement volume was 59% of predicted, and 47% for primary knee replacements. Revision hip replacement volume was 77% of predicted, and 42% for revision knee replacement. Median length of stay was one day shorter for primary (4 vs 3 days) and revision (6 vs 5 days) operations during the pandemic compared with before. Patients operated on during the pandemic were younger and had slightly more comorbidities than those operated on before the pandemic. The restricted provision of elective hip and knee replacements during the COVID-19 pandemic changed the patient casemix, but did not introduce new inequalities in access to these operations. Patients were younger, had more comorbidities, and stayed in hospital for less time than those treated before the pandemic. Approximately half the number of operations were performed during the pandemic than would have been expected and the effect was greatest for revision knee replacements.

The Aging Bone Marrow Niche Disrupts Glutamine Metabolism By Upregulating HSC Derived Glutamine Synthetase

As our aging population grows it is becoming increasingly important to better understand the physiological changes that drive that drive the aging process. Aging has long been known to drive haematopoietic stem cell (HSCs) dysfunction and therefore has been implicated in promoting the development of age-related haematopoietic diseases, such as leukaemia and myeloma. It is likely that a combination of intrinsic changes within the HSCs and extrinsic changes within the bone marrow (BM) microenvironment contribute to HSC aging. We have previously shown that the bone marrow niche accumulates senescent cells which contribute to impaired HSC response to stress 1. Here we investigate the intrinsic changes that can be observed in aged HSCs and how these are influenced by the bone marrow niche. In order to investigate the intrinsic changes that drive metabolic HSC aging we BM was isolated from young (8-12 weeks) and aged (18-24 months). Single HSCs were then FACS purified and sequenced using the SmartSeq2 protocol. Three transcriptionally distinct populations were identified, HSCs from young mice (Y), HSCs from aged mice with an aging transcriptional signature (O) and HSCs from aged mice that are transcriptionally similar to HSCs from young mice (OY). Assessment of differentially expressed genes between these three populations revealed that glutamine synthetase ( glul) is significantly upregulated in the O population compared to both the Y and OY population. Glul is responsible for the conversion of glutamate to glutamine and therefore levels of both were next measured in FACS purified HSCs from aged and young mice. Results show that whilst there was no difference in glutamate levels, the glutamine levels were significantly reduced in HSCs from aged mice. These data suggest that glutamine metabolism is impaired in aged HSC. Next, to determine the impact of the aged BM niche on glul expression in aged HSCs, HSCs from young and aged PepCboy (CD45.1+) mice were FACS purified and adoptively transferred into young C57Bl/6 mice. After 12 weeks the mice were sacrificed and engraftment of CD45.1+ cells was confirmed by flow cytometry. In addition CD45.1+ HSCs were FACS purified to assess glul expression and measure glutamine and glutamate levels. Results confirm that the mechanism for changes in glul expression and glutamine levels is driven by the aging BM niche and transplantation into a young niche reverses this change. To understand the importance of dysregulated glutamine metabolism in aged humans we collected BM from older patients undergoing elective hip replacement surgeries. All samples were collected following informed consent and under approval of the UK NHS Health Research Authority (ref07/H0310/146). CD34+ cells were isolated and RNA extracted to measure glul expression. Similarly, to data from aged mice glul expression was elevated in aged CD34+ cells compared to young CD34+ controls. Furthermore, glutamine levels were also low in aged CD34+ cells. This suggests that the changes in HSCs from aged mice correlate with finding in human stem cells and mice are therefore a suitable species to study dysregulated glutamine metabolism in aged HSCs. Together this work demonstrates that aging causes a disruption of glutamine and glutamate metabolism in HSCs. The cause for this disruption and its direct consequences on overall HSC metabolism remains to be explored. However, it is likely that these metabolic changes will have a knock-on effect on HSC function and may elucidate some of the drivers of metabolic HSC aging.