To determine the risk of total knee replacement (TKR) for primary osteoarthritis (OA) associated with overweight/obesity in the Australian population. This population-based study analyzed 191,723 cases of TKR collected by the Australian Orthopaedic Association National Joint Registry and population data from the Australian Bureau of Statistics. The time-trend change in incidence of TKR relating to BMI was assessed between 2015-2018. The influence of obesity on the incidence of TKR in different age and gender groups was determined. The population attributable fraction (PAF) was then calculated to estimate the effect of obesity reduction on TKR incidence. The greatest increase in incidence of TKR was seen in patients from obese class III. The incidence rate ratio for having a TKR for obesity class III was 28.683 at those aged 18-54 years but was 2.029 at those aged >75 years. Females in obesity class III were 1.7 times more likely to undergo TKR compared to similarly classified males. The PAFs of TKR associated with overweight or obesity was 35%, estimating 12,156 cases of TKR attributable to obesity in 2018. The proportion of TKRs could be reduced by 20% if overweight and obese population move down one category. Obesity has resulted in a significant increase in the incidence of TKR in the youngest population in Australia. The impact of obesity is greatest in the young and the female population. Effective strategies to reduce the national obese population could potentially reduce 35% of the TKR, with over 10,000 cases being avoided

All over the world, obesity rates are on the rise. Medical complications and increased health risks are often associated with being overweight or obese, but a thorough understanding of in vivo motions for obese, overweight and normal weight subjects does not exist. Therefore, the objective of this study was to compare knee kinematics in TKA subjects by body mass index (BMI). In vivo knee kinematics were determined for 253 TKA subjects during a Deep Knee Bend (DKB) from full extension to maximum flexion using a 3D to 2D image registration technique. Each of these subjects was then classified into one of three BMI categories: obese (BMI greater than or equal to 30), overweight (BMI greater than or equal to 25 and less than 30) and normal weight (BMI less than 25 and greater than or equal to 18.5). Subjects were provided by 11 surgeons using ten different TKA devices. All subjects were deemed clinically successful. On average, weight bearing range of motion (ROM) for the obese (n=79), overweight (n=113) and normal weight (n=61) groups were 107.7° (range: 74° to 136°, standard deviation (σ) =14.9°), 109.6° (60° to 150°, σ=17.5°) and 114.1° (72° to 147°, σ=14.4), respectively. ROM of 90° or less was seen in 16.5% of the obese subjects, 14.2% of the overweigh subjects and 6.6% of the normal weight subjects. ROM of 125° or more was seen in 15.2% of the obese subjects, 16.8% of the overweight subjects and 23.0% of the normal weight subjects. From full extension to maximum flexion the obese, overweight and normal weight groups averaged 8.65° (−5.14° to 22.51°, σ=6.22°), 7.58° (−2.85° to 24.72°, σ=5.71°) and 5.72° (−4.84° to 19.43°, σ=5.65°) of axial rotation. Axial rotation of 3° or less was seen in 20.25% of the obese subjects, 23.01% of the overweight subjects and 39.34% of the normal weight subjects. Axial rotation of greater than 9° was seen in 51.90% of the obese subjects, 35.40% of the overweight subjects and 26.23% of the normal weight subjects. Opposite axial rotation was seen in 8.86% of the subjects in the obese group, 9.73% of the overweight group and 9.84% of the normal weight group. On average, from full extension to maximum flexion, the medial condyle for the obese, overweight and normal weight groups experienced −5.44mm (−22.20mm to 8.04mm, σ=7.9mm), −6.30mm (−25.22mm to 5.35mm, σ=7.36mm) and −4.78mm (−20.79mm to 5.49mm, σ=6.68mm) of posterior femoral rollback (PFR), respectively. The obese, overweight and normal weight groups averaged −12.66 mm (−34.57mm to 0.34mm, σ=9.32mm), −12.38mm (−36.72mm to 1.83mm, σ=10.33mm) and −9.39 mm (−34.55mm to 0.35mm, σ=8.98mm) of lateral PFR, respectively. Condylar lift-off of greater than 1mm was seen in 16.46% of obese subjects, 10.62% of overweight subjects and 11.48% of normal weight subjects. Various statistical differences were seen across the groups. The normal weight subjects had significantly higher ROM that the obese subjects (p=0.0184), while there was no difference seen between the normal weight and overweight groups or the overweight and obese groups. The obese and the overweight groups had significantly more axial rotation than the normal weight group from 0° to 90°, 0° to maximum flexion, 30° to 90°, 30° to maximum flexion and 60° to 90°. There were a significantly higher number of cases of condylar lift-off for obese subjects when compared to both normal weight and overweight groups. It can be concluded that body mass index does play a factor in TKA kinematics

Introduction. The purpose of this study is to estimate the cost-effectiveness of performing total hip arthroplasty (THA) versus nonoperative management (NM) in non-obese (BMI 18.5–24.9), overweight (25–29.9), obese (30–34.9), severely-obese (35–39.9), morbidly-obese (40–49.9), and super-obese (50+) patients. Methods. We constructed a state-transition Markov model to compare the cost-utility of THA and NM in the six above-mentioned BMI groups over a 15-year time period. Model parameters for transition probability (i.e. risk of revision, re-revision, death), utility, and costs (inflation adjusted to 2017 US dollars) were estimated from the literature. Direct medical costs of managing hip arthritis were accounted in the model. Indirect societal costs were not included. A 3% annual discount rate was used for costs and utilities. The primary outcome was the incremental cost-effectiveness ratio (ICER) of THA versus NM. One-way and Monte Carlo probabilistic sensitivity analysis of the model parameters were performed to determine the robustness of the model. Results. Over the 15-year time period, the ICERs for THA versus NM were: normal-weight ($6,043/QALY), overweight ($5,770/QALY), obese ($5,425/QALY), severely-obese ($7,382/QALY), morbidly-obese ($8,338/QALY), and super-obese ($16,651/QALY). The two highest BMI groups had higher incremental QALYs and incremental costs. The probabilistic sensitivity analysis suggests that THA would be cost-effective in 100% of the normal, overweight, obese, severely-obese, and morbidly-obese simulations, and 99.95% of super-obese simulations at an ICER threshold of $50,000/QALY. Conclusion. Even at a willingness-to-pay threshold of $50,000/QALY, which is considered low for the United States, our model showed that THA would be cost effective for all obesity levels. Therefore, invoking BMI cut-offs for THA may lead to unjustifiable loss of healthcare access for obese patients with end-stage hip osteoarthritis

Background: In Denmark there is every year performed 5000 total knee Arthroplasty, and the number increase fast every year. The most common indication for total knee Arthroplasty is arthrosis which constitute 80 %. Convincing studies shows that overweight and obesity are the most important reason for develop arthrosis. On the contrary the relationship between overweight and outcome are ambiguous. This study examinant whether there is association between body mass index and the clinical outcome at 1 year following primary total knee Arthroplasty. Method and material: A total of 158 patients, 116 woman and 42 men undergoing a total knee Arthroplasty replacement from the hospital of southern Jutland Sonderborg in the period January 1. 2005 – December 31. 2006. Each patient where followed from the day of the surgery to 1 year postoperative. There were four clinical outcome measures; functional score, knee score, functional score improvement and knee score improvement. Data was collected from medical records and the database Dansk Knæalloplastik Register. Results: In woman there were found significant negative linear relationship between body mass index and knee score improvement – 0.97 (p=0.003). The correlations coefficient for body mass index and knee score was significant (p=0.04). There were significant associations between body mass index and all four outcome measures for patients > 65 years; functional score (p= 0.006), knee score (p=0.01), functional score improvement – 1.09 (p=0.017) and knee score improvement – 1.14 (p=0.006). For the patients < 65 years there was a positively significant linear relationship between body mass index and functional score improvement 1.47 (p=0.01). In the functional score there was not found significant relationship whit body mass index in this age group (p=0.12). Conclusion: This study shows evidence for overweight and obesity in patients undergone a total knee Arthroplasty has implications for how much the patient achieves clinical improvement after 1 year postoperative. The higher body mass index the patient has, the worse score obtained

Aims: To compare the clinical and functional outcomes of autologous chondrocyte implantation for treatment of osteochondral defects of the knee performed in overweight, obese and patients of ‘ideal weight’as defined by their BMI. Methods: We analysed the data on all our patients that have been followed up for a minimum of 2 years and had their height and weight recorded initially in our database. Functional assessment consisted of the Modified Cincinatti Scores (collected prospectively at 6 months, 1 year, 2 years and 3 years following surgery). Patients were placed into 3 groups according to their body mass index (BMI). Group A consisted of patients with BMI of 20 to 24.9, group B patients with BMI of 25 to 29.9 and Group C are patients with BMI of 30 to 39.9. Results: There were 80 patients (41 males and 39 females) with a mean age of 35.4 (range 18 to 49). The mean BMI for the entire group was 26.6. The pre-operative, 6 month, 1 year, 2 year, and 3 year Modified Cin-cinatti Score in Group A (32 patients) was 54.4, 80.3, 82.7, 74.7 and 72.6. Similarly in Group B, the scores were 53, 41, 54, 56, 49.5 and in Group C the scores were 36.3, 36.3, 49.6, 36, and 35.7. The wound infection rate in Group A was 6.25%, in Group B was17.6% and Group C was 14.3%. Conclusions: Initial results from this study suggest that BMI is an important predictor of outcome after chon-drocyte implantation. The group of patients that would gain most benefit from ACI are patients that are not overweight (defined by BMI in the range of 20 to 24.9). Further work is being carried out to support the hypothesis that surgeons should strongly consider not operating on patients unless the BMI is less than 25

Purpose. Weight loss is often advised to our patients and considered to make a substantial difference in most musculoskeletal symptoms. Patients with end stage ankle arthrosis have severe pain, diminished health related quality of life, and limited physical function. They frequently refer to increased weight as a simple indicator of decline in their quality loose weight. Patients assume that weight loss will follow after surgery secondary to increased activity with reduced pain and disability. Method. Changes in the body mass index, mental and physical component of SF36 and Ankle Scale Osteoarthritis of 145 overweight and obese patients after ankle surgery were assessed up to five year after surgery with a mean of 37.1 month follow up from 2002 to 2009. Results. The Ankle Osteoarthritis Scale and Physical component of SF36 significantly improved, by a mean of 34.8, 9.8, respectively after ankle surgery but there was not significant change in Body mass index. Conclusion. Pain and disability of end stage ankle arthritis usually resolve gradually within one and two year after surgery but body mass index changes was insignificant in five year period. In fact following successful ankle fusion or replacement, 1/3 of our patients gained 1 unit BMI or more, 1/3 lost one unit BMI or more and 1/3 remained within one unit of their pre op BMI. This suggests that obesity is a multifactorial and an independent disease

Introduction: Several studies have implicated excessive weight as a negative predictor of success of total knee arthroplasty. In addition, obese patients are known to have increased risk of wound complications after orthopaedic and general surgery. The purpose of this study was to compare the clinical and functional outcomes of autologous chondrocyte implantation for treatment of osteochondral defects of the knee performed in obese patients with those performed in non-obese patients. Methods: We analysed the data on all our patients that have been followed up for a minimum of 2 years and had their height and weight recorded initially in our database. Functional assessment consisted of Bentley Functional Rating Score, Visual Analogue Score, and the Modified Cincinatti Scores (collected prospectively at 6 months, 1 year, 2 years and 3 years following surgery). Patients were placed into 3 groups according to their body mass index (BMI). Group A consisted of patients with BMI of 20 to 24.9, group B patients with BMI of 25 to 29.9 and Group C are patients with BMI of 30 to 39.9. Results: There were 80 patients (41 males and 39 females) with a mean age of 35.4 (range 18 to 49). The mean BMI for the entire group was 26.6. The pre-operative, 6 month, 1 year, 2 year, and 3 year Modified Cincinatti Score in Group A (32 patients) was 54.4, 80.3, 82.7, 74.7 and 72.6. Similarly in Group B, the scores were 53, 41, 54, 56, 49.5 and in Group C the scores were 36.3, 36.3, 49.6, 36, and 35.7. The wound infection rate in Group A was 6.25%, in Group B was 17.6% and Group C was 14.3%. Conclusions: Initial results from this study suggest that BMI is an important predictor of outcome after chondrocyte implantation. The group of patients that would gain most benefit from ACI are patients that are not overweight (defined by BMI in the range of 20 to 24.9). Further work is being carried out to support the hypothesis that surgeons should strongly consider not operating on patients unless the BMI is less than 25

Introduction: Primary Care Trusts (PCT) in Suffolk have recently withdrawn funding for hip (THA) or knee replacement (TKA) surgery for obese patients (Body Mass Index (BMI) > 30). We have estimated the number of patients affected by this restriction by reviewing our joint replacement database and have sought evidence for this decision being evidenced based.

Materials and Methods: All patients undergoing joint replacement at our hospital have their BMI recorded prospectively. We have established the number of patients having hip or knee replacements with a BMI of greater than 30. A Medline literature search identified studies that examined the influence of BMI on outcome of joint replacement surgery

Results: 328 (24%) of 1366 people undergoing THA between 2000–2005, and 225 (38.5%) of 567 undergoing TKA between 2003–2005 had a BMI > 30. The difference between these groups is significant (p 0.001 CI 0.095 to 0.191.). There was no difference between the sexes in the hip group, but more women than men were obese in the knee group (p< .001 CI 0.096–0.25). We identified 19 studies that examined the impact of BMI on joint replacement surgery.

Discussion: Based on National joint register figures, a similar policy enacted in England and Wales would affect about 20,000 patients a year.

The literature produces some evidence of a higher early complication rate in obese patients undergoing THA, and operative time seems to be longer and blood loss greater than for matched controls. The only study looking at long-term outcome of THA showed no difference in hip survivorship at 10–18 years between obese and normal weight patients. We conclude that where THA is concerned, the PCT policy has no clinical or evidence based justification.

Purpose

The purpose of this study were to investigate whether there is an association between the preoperative body mass index in total knee replacement patients and the effect three to five years postoperative.

In total hip arthroplasty (THA), it is preferable that patients have an ideal preoperative Body Mass Index (within 20% of the normal). The purpose of this study is to determine whether patients maintain their preoperative reduced weight after THA and whether the effort of encouragement and cost of a dietician to lose weight preoperatively is worthwhile.

Conducted over five years, this study included 100 patients with a mean age of 62.5 years (34 to 83). Preoperative and postoperative weights were obtained from clinical records.

There was a postoperative weight increase in 51% of patients and a decrease in postoperative weight in 46%. Pre-operative weight was maintained in 3%.

The aim of this study was to examine the incidence of obesity in patients undergoing primary total shoulder replacement (TSR) (stemmed and reverse) for osteoarthritis (OA) in Australia compared to the incidence of obesity in the general population. A 2017–18 cohort of 2,621 patients from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) who underwent TSR, were compared with matched controls from the Australian Bureau of Statistics (ABS) National Health Survey from the same period. The two groups were analysed according to BMI category, sex and age. According to the 2017–18 National Health Survey, 35.6% of Australian adults are overweight and 31.3% are obese. Of the primary TSR cases performed, 34.2% were overweight and 28.6% were obese. The relative risk of requiring TSR for OA increased with increasing BMI category. Class-3 obese females, aged 55–64, were 8.9 times more likely to require TSR compared to normal weight counterparts. Males in the same age and BMI category were 2.5 times more likely. Class-3 obese patients underwent TSR 4 years (female) and 7 years (male) sooner than their normal weight counterparts. Our findings suggest that the obese population is at risk for early and more frequent TSR for OA. Previous studies demonstrate that obese patients undergoing TSR also exhibit increased risks of longer operative times, higher superficial infection rates, higher periprosthetic fracture rates, significantly reduced post-operative forward flexion range and greater revision rates. Obesity significantly increases the risk of requiring TSR. To our knowledge this is the first study to publish data pertaining to age and BMI stratification of TSR Societal efforts are vital to diminish the prevalence and burden of obesity related TSR. There may well be reversible pathophysiology in the obese population to address prior to surgery (adipokines, leptin, NMDA receptor upregulation). Surgery occurs due to recalcitrant or increased pain despite non-op Mx

Obesity is a known risk factor for developing osteoarthritis and is also associated with an increased risk of developing complications post total hip replacement (THR). This study investigated the association between obesity and the risk of undergoing THR in Australia. From July 2017 to June 2018 a National Health Survey was conducted by the Australian Bureau of Statistics to collect height and weight data on a representative sample of patients across urban and rural areas across the country. This study examined a cohort of patients undergoing primary THR utilising data from the Australian Orthopaedic Association National Joint Replacement Registry from the same time period. Obesity classes were determined according to WHO criteria. Body mass index (BMI) for patients undergoing THR were obtained and the distribution of THR patients by BMI category was compared to the general population, in age and sex sub-groups. Generalised linear models assuming a binomial distribution and a log link were used to generate relative risks. Data from underweight categories, and age categories 34 years and younger, were excluded from further analyses because of small numbers. Data from the health survey showed there were 35.6% of persons overweight and 31.3% obese. During the same period, 32,495 primary THR were performed for osteoarthritis in Australia on patients who had a BMI recorded. Of these patients 37.1% were overweight and 41.7% were obese. Compared to the general population, there was a higher incidence of Class I, II, and III obesity in patients undergoing THR in both sexes aged 35 to 74 years. Class III obese females and males aged 55–64 years were 2.9 and 1.7 times more likely to undergo HR, respectively (p<0.001). Class III obese females and males underwent THR on average 5.7 and 7.0 years younger than their normal weight counterparts, respectively. Obese Australians are at increased risk of undergoing THR, and at a younger age. A national approach to address the prevalence of obesity, and possible prevention strategies, is needed

Introduction. Total hip replacement (THR) patients are often considered a homogenous group whereas in reality, patients are heterogeneous. Variation in revision rates between patient groups suggest that implants are exposed to different environmental conditions in different patients [1]. Previous reports suggest that for every unit increase of BMI, there is a 2% increased risk of revision of a THR [2]. The aim of this study was to better understand the effect of patient-specific characteristics such as BMI on hip motions and to explore the possible impact on wear. Methods. 137 THR patients, at least 12 months post-surgery, underwent 3D kinematic (Vicon, Oxford, UK) and kinetic (AMTI, USA) analysis whilst walking at self-selected walking speed. 3D kinematic data were then mapped onto a modelled femoral cup at 20 pre-determined points to create pathways for femoral head contact, which were then quantified by deriving the aspect ratio (AR). Patients were stratified into three groups determined by BMI scores; healthy weight (BMI ≤25 kg/m. 2. ) (n=34); overweight (BMI >25kg/m. 2. to ≤ 30 kg/m. 2. ) (n=66) and obese patients (BMI > 30 kg/m. 2. ) (n=37). Comparisons were made using 95% confidence intervals (CI) and one way ANOVAs. Results. The healthy weight strata demonstrated a minimum flexion angle of 0.59°(CI −2.15 to 3.32), compared to overweight 1.12°(CI 0.99 to 2.11) and obese strata 1.37°(−0.72 to 3.46). The healthy weight strata exhibited a lower frontal ROM 7.91° (CI 7.02 to 8.80) (p<0.000) compared to the overweight (9.42°, CI 8.76 to 10.08) and obese strata (9.79°; CI 9.08 to 10.50). No differences between strata were observed in the transverse plane. The real-world gait inputs resulted in a lower aspect ratio for all three patient groups compared to the ISO standard AR of 3.86. There was a trend towards a higher AR in patients with a lower BMI. Obese patients had a reduced AR of 3.33 (CI 3.08 to 3.58) compared to the overweight and healthy weight patients, demonstrating AR of 3.36(CI 3.21 to 3.52) and 3.48 (CI 3.25 to 3.70), respectively. Discussion. There were few hip kinematic differences between BMI strata, except for a lower frontal ROM in the healthy weight patients. There was a resulting trend towards an increased AR in the healthy weight group. Notwithstanding the effect of contact force which was not modelled in this study, increased AR in the healthy weight group might assist long molecule entrainment and hence reduce risk of polyethylene wear for equivalent levels of activity. These results highlight the conservative nature of the ISO standard ISO-14242 and provide a possible link between kinematics and the observed increased in revision rates in patients with high BMI

Abstract. Introduction. The effectiveness of single intra-articular injections of polyacrylamide hydrogel (iPAAG) and hyaluronic acid (HA) was compared in subgroups of participants from an RCT based on baseline age, BMI or Kellgren-Lawrence (KL) grade. Methodology. 239 participants were randomised to 6 mL iPAAG (Arthrosamid; n=119) or 6 mL HA (Synvisc-One; n=120). Participants continued analgesics (except 48 hours prior to visits) and non-pharmacological therapy. Topical therapies and intra-articular corticosteroids were not allowed. Pre-specified subgroup analyses (age: <70 years, ≥70 years; BMI: normal, overweight, obese; KL grade: 2, 3, 4, 2–3) of change from baseline in WOMAC pain subscale at 52 weeks were based on the least squares means for the treatment-by-week interaction effect using a mixed model for repeated measurement with a restricted maximum likelihood-based approach. Results. Across all patients, change from baseline in WOMAC pain subscale in the iPAAG group was non-inferior to HA at 26 weeks and approached superiority (p=0.0572) at 52 weeks. Treatment differences for change from baseline in WOMAC pain subscale in favour of iPAAG over HA were statistically significant for the age <70 years (p=0.019), BMI normal (p=0.011) and KL grade 2–3 (p=0.033) subgroups. Treatment differences for all other subgroups favoured iPAAG, except for KL grade 4 which favoured HA, without reaching statistical significance. Conclusion. iPAAG approached superiority to HA across all participants at 52weeks, but demonstrated statistical superiority in participants with normal BMI, participants <70 years old or participants with KL score 2–3. iPAAG represents a useful alternative to HA for the treatment of knee OA

Aim. To describe the risk factors, microbiology and treatment outcome polymicrobial prosthetic joint infections (PJI) compared to monomicrobial PJI. Methods. Between January 2011 and December 2021, a total of 536 patients were diagnosed with PJI at our institution. Clinical records were revised, and 91(16.9%) had an isolation of two or more pathogens. Age, sex, previous conditions, Charlson comorbidity score, previous surgery, PJI diagnosis and surgical and antibiotic treatment, from the index surgery onwards were reviewed and compared between groups. Results. Polymicrobial PJI success rate was 57.1%, compared to 85.3% of the monomicrobial PJI(p=0.0036). There were no statistically significative differences between acute and chronic infections. In terms of related risk factors, revision surgery(p=0.0002), fracture(p=0.002), tobacco(p=0.0031) and Body Mass Index (BMI) between 20–25(p=0.0021) were associated to monomicrobial PJI, whereas overweight(p=0.005) and obesity(p=0.02) were linked to polymicrobial PJI. Regarding pathogens, the most common microorganism isolated in monomicrobial was S.aureus (33.5%), followed by S. epidermidis(20%) and gram negative bacilli (12.2%); while S. epidermidis(56%), gram negative bacilli (41.8%) and E.colli (30.8%) were the most frequent in the polymicrobial PJI. Enterococci(p=0.0008), S. epidermidis(p=0.007), E.colli (p=0.0008), gram negative bacilli (p=0.00003) and atypical bacteria (p=0.00001) statistically significative linked to polymicrobial PJI; while S.aureus (p=0.018) was related to monomicrobial PJI. Conclusion. Polymicrobial PJI showed worse outcome compared to monomicrobial PJI in our cohort. In terms of risk factors, overweight, obesity and some pathogens like gram negative bacilli, atypical bacteria, enterococci, S. epidermidis and E.colli were associated with Polymicrobial PJI

Partial meniscectomy patients have a greater likelihood for the development of early osteoarthritis (OA). To prevent the onset of early OA, patient-specific treatment algorithms need to be created that predict patient risk to early OA after meniscectomy. The aim of this work was to identify patient-specific risk factors in partial meniscectomy patients that could potentially lead to early OA. Partial meniscectomy patients operated between 01/2017 and 12/2019 were evaluated in the study (n=317). Exclusion criteria were other pathologies or surgeries for the evaluated knee and meniscus (n = 114). Following informed consent, an online questionnaire containing demographics and the “Knee Injury and Osteoarthritis Outcome Score” (KOOS) questionnaire was sent to the patient. Based on the KOOS pain score, patients were classified into “low” (> 75) and “high” (< 75) risk patients, indicating risk to symptomatic OA. The “high risk” patients also underwent a follow-up including an MRI scan to understand whether they have developed early OA. From 203 participants, 96 patients responded to the questionnaire (116 did not respond) with 61 patients considered “low-risk” and 35 “high-risk” patients. Groups that showed a significant increased risk for OA were patients aged > 40 years, females, overweight (BMI >25 kg/m2 ≤ 30 kg/m2), and smokers (*p < 0.05). The “high-risk”-follow-up revealed a progression of early osteoarthritic cartilage changes in seven patients, with the remaining nineteen patients showing no changes in cartilage status or pain since time of operation. Additionally, eighteen patients in the high-risk group showed a varus or valgus axis deviation. Patient-specific factors for worse postoperative outcomes after partial meniscectomy and indicators for an “early OA” development were identified, providing the basis for a patient-specific treatment approach. Further analysis in a multicentre study and computational analysis of MRI scans is ongoing to develop a patient-specific treatment algorithm for meniscectomy patients

Background. Weightbearing computed tomography scans allow for better understanding of foot alignment in patients with Progressive Collapsing Foot Deformity. However, soft tissue integrity cannot be assessed via WBCT. As performing both WBCT and magnetic resonance imaging is not cost effective, we aimed to assess whether there is an association between specific WBCT and MRI findings. Methods. A cohort of 24 patients of various stages of PCFD (mean age 51±18 years) underwent WBCT scans and MRI. In addition to signs of sinus tarsi impingement, four three-dimensional measurements (talo-calcaneal overlap, talo-navicular coverage, Meary's angle axial/lateral) were obtained using a post processing software (DISIOR 2.1, Finland) on the WBCT datasets. Sinus tarsi obliteration, spring ligament complex and tibiospring ligament integrity, as well as tibialis posterior tendon degeneration were evaluated with MRI. Statistical analysis was performed for significant (P<0.05) correlation between findings. Results. None of the assessed 3D measurements correlated with spring ligament complex or tibiospring ligament tears. Age, body mass index, and TCO were associated with tibialis posterior tendon tears. 75% of patients with sinus tarsi impingement on WBCT also showed signs of sinus tarsi obliteration on MRI. Of the assessed parameters, only age and BMI were associated with sinus tarsi obliteration diagnosed on MRI, while the assessed WBCT based 3D measurements were, with the exception of MA axial, associated with sinus tarsi impingement. Conclusion. While WBCT reflects foot alignment and indicates signs of osseous impingement in PCFD patients, the association between WBCT based 3D measurements and ligament or tendon tears in MRI is limited. Partial or complete tears of the tibialis posterior tendon were only detectable in comparably older and overweight PCFD patients with an increased TCO. WBCT does not replace MRI in diagnostic value. Both imaging options add important information and may impact decision-making in the treatment of PCFD patients

Instability is a common indication for revision total hip arthroplasty (THA). However, even after the initial revision, some patients continue to have recurrent dislocations. This study investigates those at risk for recurrent dislocation after revision THA for instability at a single institution. Between 2009 and 2019, 163 patients underwent revision THA for instability at a single institution. Thirty-three of these patients required re-revision THA due to recurrent dislocation. Cox proportional hazard models with death as a competing event were used to analyze risk factors, including prosthesis sizing and alignment. Paired t-tests or Wilcoxon signed rank tests were used to assess patient outcomes (Veterans RAND 12 (VR-12) physical score, VR-12 mental score, Harris Hip Score, and hip disability and osteoarthritis outcome score for joint replacement). Duration of follow-up until either re-revision or final follow-up was a mean of 45.3 ± 38.2 months. The 1-year cumulative incidence for recurrent dislocation after revision was 8.7%, which increased to 19.6% at 5 years and 32.9% at 10 years postoperatively. In the multivariable analysis, high ASA score [HR 2.71], being underweight (BMI<18 kg/m. 2. ) [HR 36.26] or overweight/obese (BMI>25 kg/m. 2. ) [HR 4.31], use of specialized liners [HR 5.51–10.71], lumbopelvic stiffness [HR 6.29], and postoperative abductor weakness [HR 7.20] were significant risk factors for recurrent dislocation. Increasing the cup size decreased the dislocation risk [HR 0.89]. The dual mobility construct did not affect the risk for recurrent dislocation in univariate or multivariable analyses. VR-12 physical and HHS (pain and function) scores improved postoperatively at midterm. Patients requiring revision THA for instability are at risk for recurrent dislocation. Higher ASA scores, abnormal BMI, use of special liners, lumbopelvic stiffness, and postoperative abductor weakness are significant risk factors for re-dislocation

Background. Postoperative dislocation is one of the main surgical complications and the primary cause for revision surgery after 2-stage implant exchange due to periprosthetic infection of a total hip arthroplasty. Objective. The aims of our study were (1) to determine the incidence of dislocation after two-stage THA reimplantation without spacer placement, (2) to evaluate relevant risk factors for dislocation and (3) to assess the final functional outcome of those patients. Method. We prospectively analyzed 187 patients who underwent a two-stage total hip arthroplasty (THA) revision after being diagnosed with periprosthetic joint infection (PJI) from 2013 to 2019. The mean duration of follow-up was 54.2 ± 24.9 months (>36 months). The incidence of postoperative dislocation and subsequent revision was estimated through Kaplan-Meier curves and potential risk factors were identified using Cox hazard regression. The functional outcome of the patients was assessed using the modified Harris Hip Score (mHHS). Results. The estimated cumulative dislocation-free survival was 87.2% (95% CI: 81.2%-91.3%) with an estimated 10% and 12% risk for dislocation within the first 6 and 12 months, respectively. The use of a dual-mobility construct had no significant impact on the dislocation rate. Increasing body mass index (BMI) (HR=1.11, 95% CI: 1.02-1.19, p=0.011), abductor mechanism impairment (HR=2.85, 95% CI: 1.01-8.01, p=0.047), the extent of elongation of the affected extremity between stages (HR=1.04, 95% CI: 1.01-1.07, p=0.017), the final leg length discrepancy (HR=1.04, 95% CI: 1.01-1.08, p=0.018) and PJI recurrence (HR=2.76, 95% CI: 1.00-7.62, p=0.049) were found to be significant risk factors for dislocation. Overall revision rates were 17% after THA reimplantation. Dislocated hips were 62% more likely to undergo re-revision surgery (p<0.001, Log-rank= 78.05). A significant average increase of 30 points in mHHS scores after second-stage reimplantation (p=0.001, Wilcoxon-rank) was recorded, but no difference was noted in the final HHS measurements between stable and dislocated hips. Conclusion. Dislocation rates after 2-stage THA reimplantation for PJI remain high, especially regarding overweight or re-infected patients. Careful leg length restoration and an intact abductor mechanism seem critical to ensure stability in these complex patients

Aim. Swedish guidelines on antibiotic prophylaxis in arthroplasty surgery recommend cloxacillin in fixed doses that pay little attention to the patient's renal function and weight. Nevertheless, there are no studies on whether the resulting free prophylactic cloxacillin in vivo concentrations are optimal. We aimed to evaluate whether the current recommended prophylactic dosage of cloxacillin is adequate. Method. We performed a prospective two-centre study, measuring the free (active) cloxacillin concentrations in plasma throughout surgery, in patients subject to primary hip and knee prosthetic joint replacements, aiming at 100 patients per centre. To account for plasma-bone exposure differences, concentrations were considered adequate if twice the epidemiological cut-off value for cloxacillin concerning wild type Staphylococcus aureus whereas two-three times were labelled threshold values. The two enrolling hospitals are acute care hospitals in central Sweden, also performing 600 - 1200 primary hip and knee joint arthroplasties annually. All patients scheduled for elective primary hip or knee replacements from January 2022 to April 2024 were eligible for participation. Exclusion criteria were allergy towards penicillins, cognitive disorders leading to inability to sign informed consent, and an absence of interpreter in case of a patient not speaking Swedish or English. Results. We present results from the first 49 patients included. Four patients had free cloxacillin concentrations below cut-off (8.2%). These four cases had prolonged surgeries of 77-100 minutes. An additional 5/49 (10.2%) had threshold values. Conversely 5/49 (10.2%) cases had concentrations exceeding 15 times the needed. No cases with threshold or low cloxacillin concentrations were attributable to a lack of concerning timing and dosing of cloxacillin. All concentrations were above or equal to our cut-off at the start of surgery. Eighteen percent of patients were of normal of weight (BMI 18.5- 25). Of the rest 4% were morbidly obese (BMI >40), 41% obese (BMI 30-40) and 37% overweight (BMI 25-30). Twenty seven percent (43/159) had diabetes and 45% suffered cardiac disease. Conclusions. Some patients in our cohort had insufficient active cloxacillin levels at the end of prosthetic joint surgery. Previous studies indicate that insufficient prophylactic antibiotic concentrations might lead to an enhanced risk of prosthetic joint infections. Other patients were massively overdosed, leading to unnecessary ecological effects and potentially adverse reactions. As inadequate cloxacillin concentrations were not associated with a lack of compliance to current guidelines a change in practise might be needed. Our final results may help to determine how dosing should be adjusted