Aims. Describe a statistical and economic analysis plan for the Distal Radius Acute Fracture Fixation Trial 2 (DRAFFT2) randomized controlled trial. Methods. DRAFFT2 is a multicentre, parallel, two-arm randomized controlled trial. It compares surgical fixation with K-wires versus plaster cast in adult patients who have sustained a dorsally displaced fracture of the distal radius. The primary outcome measure is the Patient-Rated Wrist Evaluation (PRWE, a validated assessment of wrist function and pain) at 12 months post-randomization. Secondary outcomes are measured at three, six, and 12 months after randomization and include the PWRE, EuroQoL EQ-5D-5L index and EQ-VAS (visual analogue scale), complication rate, and cost-effectiveness of the treatment. Results. This paper describes the full details of the planned methods of analysis and descriptive statistics. The DRAFFT2 study protocol has been published previously. Conclusion. The planned analysis strategy described records our intent to conduct statistical and within-trial cost-utility analyses. Cite this article: Bone Joint Open 2020;1-6:245–252

Aims

The aim of this study was to perform the first population-based description of the epidemiological and health economic burden of fracture-related infection (FRI).

Open lower limb fractures are resource-intensive fractures, accounting for a significant proportion of the workload and cost of orthopaedic trauma units. A recent study has evaluated that the median cost of direct inpatient treatment of open lower-limb fractures in the National Health Service (NHS) is steep, at £19189 per patient. Healthcare providers are expected to be aware of the costs of treatments, although there is very limited dissemination of this information, neither on a national or local level. Older adults (>65 years old) are at an increased risk of the types of high-energy injuries that can result in open lower limb fractures. Generally, there remains a significant lack of literature surrounding the cost of open fracture management, especially in specific patient groups that are disproportionately affected by these fractures. This study has calculated the direct inpatient care costs of older adults with open lower limb fractures.

Open lower limb fractures in adult patients over 65 years old treated at Addenbrooke's Hospital of Cambridge University Hospitals NHS Trust were identified over the period of March 2014-March 2019. Isolated fractures of the femur, tibia and fibula over this time period were included. Direct inpatient care costs were calculated using information about the sustained fracture, operative time, implant(s) and theatre kit(s) used, the number of patient bed-days on the orthopaedic ward and critical care unit, and the number of hours of inpatient physiotherapy received. Direct inpatient care costs were compared with the income received by our centre for each of these cases, according to Healthcare Resource Group (HRG) cost codes. Our data was also compared with existing literature on Patient Level Costing (PLC) figures for open lower limb fractures.

We extracted data from 58 patients over the age of 65 years treated for open isolated lower limb fractures at Addenbrooke's Hospital, Cambridge University Hospitals NHS Trust, between March 2014 and March 2019. The median cost of inpatient care calculated in this study was £20,398 per patient, resulting in a financial loss to the hospital of £5113 per patient. When the results were disaggregated by sex, the median cost for an open lower limb fracture in a male patient was £20,886 compared to £19,304 in a female patient. Data were also disaggregated by the site of injury, which produced a median cost for an open femur fracture of £23,949, and £24,549 and £15,362 for open tibia and ankle fractures, respectively.

The absence of published primary literature and clinical audits on this topic continues to hinder the inclusion of cost-effectiveness as an important factor in clinical decision-making. This study provides valuable insight into the true cost of open lower limb fractures in a key patient population in a Major Trauma Centre in England and highlights the large losses incurred by hospitals in treating these cases. These results support the revision of the remuneration structures in the NHS for the treatment of elderly patients with these injuries.

Purpose. There is increasing evidence that primary fixation of displaced mid-shaft fractures of the clavicle results in superior short-term outcomes when compared to traditional non-operative methods. However, the results from published studies are limited to relatively short-term (one year or less) follow-up. Accurate data of longer follow-up is important for a number of reasons, including patient prognostication, counseling and care, the design of future trials, and the economic analysis of treatment. The purpose of this paper was to examine the results of the two year follow up of patients enrolled in a previously published randomized clinical trial of operative versus non-operative treatment of displaced fractures of the clavicle. Method. Using a comprehensive and standard assessment that included DASH (Disabilities of the Arm, Shoulder and Hand) and CSS (Constant Shoulder Scores) scores, we evaluated ninety-five patients of the original cohort of one hundred and thirty-two patients at two years following their injury. Results. Statistical analysis performed on the two year follow up data revealed that DASH and CSS scores remained essentially unchanged at two years post-injury compared to one year post-injury for both operative and non-operative groups (p>0.05). Additionally, outcome scores in the operative group remained superior to the non-operative group (DASH operative 4 +/− 7 versus DASH non-operative 11 +/− 20, p<0.014, CSS operative 97 +/− 4 versus CSS non-operative 92 +/− 14, p<0.012) at two years post-injury. Conclusion. The improvement in outcome seen with primary fixation of displaced clavicle fractures persists at two years but does not differ significantly from values seen after one year of follow-up, suggesting that clinically a steady state has been reached whereby outcome is unlikely to change with time. This has clinical, economic, and research implications

Summary Statement

Using current analysis/methodology, new implant technology is unlikely to demonstrate a large enough change in patient function to impact on the cost-effectiveness of the procedure.

Aims

Torus fractures of the distal radius are the most common fractures in children. The NICE non-complex fracture guidelines recently concluded that bandaging was probably the optimal treatment for these injuries. However, across the UK current treatment varies widely due to a lack of evidence underpinning the guidelines. The Forearm Fracture Recovery in Children Evaluation (FORCE) trial evaluates the effect of a soft bandage and immediate discharge compared with rigid immobilization.

Introduction: Closed and open grade I (low energy) tibial shaft fractures are a common and costly event and optimal management for such injuries remains uncertain.

Methods: We explored costs associated with treatment of low energy tibial fractures with either casting, casting with therapeutic ultrasound, or intramedullary nailing (with and without reaming) by use of a decision tree.

Results: From a governmental perspective the mean associated costs were USD $3 365 (standard deviation [SD] ± 1 425) for operative management by reamed intramedullary nailing, $5 041 (SD ± 1 363) for operative management by non-reamed intramedullary nailing, $5 017 (SD±1 370) for casting, and $5 312 (SD±1 474) for casting with therapeutic ultrasound. From a societal perspective the mean associated costs were ($12 449; SD±4 894) for reamed intramedullary nailing, ($13 266; SD±3 692) for casting with therapeutic ultrasound, ($15 571; SD±4 293) for operative management by non-reamed intramedullary nailing, and ($17 343; SD±4 784) for casting alone.

Interpretation: Our analysis suggests that, from an economical standpoint, reamed intramedullary nailing is the treatment of choice for closed and open grade I tibial shaft fractures. There is preliminary evidence, from a societal perspective, that treatment of low energy tibial fractures with therapeutic ultrasound and casting may also be an economically-sound intervention.

Purpose: The purpose of this study was two-fold. First, we wanted to compare the cost of liquid waste disposal from the operating rooms (ORs) via a 3rd party medical waste company, with utilization of the sewer system at Kingston General Hospital. Secondly, we sought to assess national trends in liquid waste disposal, in order to make a national recommendation for liquid waste disposal from the OR.

Method: The hospital cost for OR liquid waste disposal at Kingston General Hospital was calculated by weighing the liquid waste from 871 surgical cases over a 5-week period in 2008. The materials, manpower and weight of the waste were used to calculate the costs for the two methods of liquid waste disposal. Seventy teaching hospitals across Canada were surveyed to determine their practice of liquid waste disposal in the OR.

Results: The raw cost per kg of liquid waste disposal using a medical waste company was found to be 57.126 % greater than utilizing the sewer system. Using the sewer system resulted in a total cost reduction of 40% compared with using a medical waste company. Sixty-three out of seventy teaching hospitals across the nation (90%) were found to utilize medical waste companies, while seven out of seventy hospitals (10%) utilized the sewer system to dispose of liquid waste.

Conclusion: The sewer system is an under-utilized yet safe, legal, and cost effective way to dispose of liquid waste from the OR. Using the sewer system to dispose of liquid waste would save the Canadian health care system millions of dollars compared with disposal via medical waste companies.

The introduction of new treatments needs to be both clinically effective and cost effective. Clinicians tend to be unaware of the importance of the latter, and how health economic assessments are undertaken, especially in a public health system where the inclusion of funded treatments is made on a national basis. The purpose of this study was to determine the cost savings from a societal perspective in the use of recombinant human Bone Morphogenetic Protein -2 (rhBMP-2) in grade III A and B open tibia fractures treated with a locked intramedullary nail and soft-tissue management in the UK, Germany, and France. Healthcare system (direct healthcare costs) and costs for productivity losses (indirect health-care costs) were calculated using the raw data from the Bone Morphogenetic Protein Evaluation Group in Surgery for Tibial Trauma “BESTT study”. Return-to-work time for estimation of productivity losses was assumed to correspond with the time of fracture healing. For calculation of secondary interventions costs and productivity losses the respective 2007/08 national tariffs for surgical procedures and average national wages for the UK, Germany, and France were used. From a societal perspective, overall savings per case of €7911 for the UK, €9270 for Germany, and €9291 were calculated. Those savings largely offset the upfront price of rhBMP-2 of €2266(£1,790) in the UK, €2970 in Germany, and €2950 in France. Total net savings can be estimated to be €9.6 million for the UK, €14.5 million for Germany, and €11.4 million for France. For all three countries reduced productivity losses are the key driver for the overall savings. In summary, despite the apparent high direct cost of rhBMP-2 in grade III A and B open tibia fractures, at a national level there are net cost-savings from a societal perspective for all three countries.

Revision arthroplasty of the hip is expensive owing to the increased cost of pre-operative investigations, surgical implants and instrumentation, protracted hospital stay and drugs. We compared the costs of performing this surgery for aseptic loosening, dislocation, deep infection and peri-prosthetic fracture. Clinical, demographic and economic data were obtained for 305 consecutive revision total hip replacements in 286 patients performed at a tertiary referral centre between 1999 and 2008. The mean total costs for revision surgery in aseptic cases (n = 194) were £11 897 (sd 4629), for septic revision (n = 76) £21 937 (sd 10 965), for peri-prosthetic fracture (n = 24) £18 185 (sd 9124), and for dislocation (n = 11) £10 893 (sd 5476). Surgery for deep infection and peri-prosthetic fracture was associated with longer operating times, increased blood loss and an increase in complications compared to revisions for aseptic loosening. Total inpatient stay was also significantly longer on average (p < 0.001). Financial costs vary significantly by indication, which is not reflected in current National Health Service tariffs.

The ability to calculate quality-adjusted life-years (QALYs) for degenerative cervical myelopathy (DCM) would enhance treatment decision making and facilitate economic analysis. QALYs are calculated using utilities, or health-related quality-of-life (HRQoL) weights. An instrument designed for cervical myelopathy disease would increase the sensitivity and specificity of HRQoL assessments. The objective of this study is to develop a multi-attribute utility function for the modified Japanese Orthopedic Association (mJOA) Score. We recruited a sample of 760 adults from a market research panel. Using an online discrete choice experiment (DCE), participants rated 8 choice sets based on mJOA health states. A multi-attribute utility function was estimated using a mixed multinomial-logit regression model (MIXL). The sample was partitioned into a training set used for model fitting and validation set used for model evaluation. The regression model demonstrated good predictive performance on the validation set with an AUC of 0.81 (95% CI: 0.80-0.82)). The regression model was used to develop a utility scoring rubric for the mJOA. Regression results revealed that participants did not regard all mJOA domains as equally important. The rank order of importance was (in decreasing order): lower extremity motor function, upper extremity motor function, sphincter function, upper extremity sensation. This study provides a simple technique for converting the mJOA score to utilities and quantify the importance of mJOA domains. The ability to evaluate QALYs for DCM will facilitate economic analysis and patient counseling. Clinicians should use these findings in order to offer treatments that maximize function in the attributes viewed most important by patients

Aims. The aim of this study was to evaluate the healthcare costs and benefits of enoxaparin compared to aspirin in the prevention of symptomatic venous thromboembolism (VTE) after total hip arthroplasty (THA) or total knee arthroplasty (TKA) using data from the CRISTAL trial. Methods. This trial-based economic analysis reports value for money as incremental cost per quality-adjusted life-year (QALY) gained in 2022 Australian dollars, compared to a single threshold value of AUD$70,000 per QALY. Event costs were estimated based on occurrence of VTEs and bleeds, and on published guidelines for treatment. Unit costs were taken from Australian sources. QALYs were estimated using CRISTAL six-month follow-up data. Sensitivity analyses are presented that vary the cost of VTE treatment, and extend the analyses to two years. Results. The CRISTAL trial found that enoxaparin was more effective than aspirin in preventing symptomatic VTE within 90 days of THA or TKA (risk difference 1.97% (95% confidence interval (CI) 0.54% to 3.41%; p = 0.007)). The additional cost after a THA or TKA was AUD$83 (95% CI 68 to 97) for enoxaparin, and enoxaparin resulted in an additional 0.002 QALYs (95% CI -0.002 to 0.005). Incremental cost per QALY gained was AUD$50,567 (95% CI 15,513, dominated) for enoxaparin. We can be 60% confident that the incremental cost per QALY does not exceed the willingness-to-pay threshold of AUD$70,000. Increasing the cost of VTE treatment and extension of costs and consequences to two years suggested greater confidence that enoxaparin is good value for money (70% and 63% confidence, respectively). Conclusion. This analysis provides strong evidence that enoxaparin thromboprophylaxis following THA or TKA reduced VTEs, but weak evidence of net economic benefits over aspirin. If the value of avoiding VTEs is high, and there is a strong likelihood of VTE-related health impairments, we can be more confident that enoxaparin is cost-effective compared to aspirin. Cite this article: Bone Joint J 2024;106-B(6):589–595

Aims. Ankle fracture is one of the most common musculoskeletal injuries sustained in the UK. Many patients experience pain and physical impairment, with the consequences of the fracture and its management lasting for several months or even years. The broad aim of ankle fracture treatment is to maintain the alignment of the joint while the fracture heals, and to reduce the risks of problems, such as stiffness. More severe injuries to the ankle are routinely treated surgically. However, even with advances in surgery, there remains a risk of complications; for patients experiencing these, the associated loss of function and quality of life (Qol) is considerable. Non-surgical treatment is an alternative to surgery and involves applying a cast carefully shaped to the patient’s ankle to correct and maintain alignment of the joint with the key benefit being a reduction in the frequency of common complications of surgery. The main potential risk of non-surgical treatment is a loss of alignment with a consequent reduction in ankle function. This study aims to determine whether ankle function, four months after treatment, in patients with unstable ankle fractures treated with close contact casting is not worse than in those treated with surgical intervention, which is the current standard of care. Methods. This trial is a pragmatic, multicentre, randomized non-inferiority clinical trial with an embedded pilot, and with 12 months clinical follow-up and parallel economic analysis. A surveillance study using routinely collected data will be performed annually to five years post-treatment. Adult patients, aged 60 years and younger, with unstable ankle fractures will be identified in daily trauma meetings and fracture clinics and approached for recruitment prior to their treatment. Treatments will be performed in trauma units across the UK by a wide range of surgeons. Details of the surgical treatment, including how the operation is done, implant choice, and the recovery programme afterwards, will be at the discretion of the treating surgeon. The non-surgical treatment will be close-contact casting performed under anaesthetic, a technique which has gained in popularity since the publication of the Ankle Injury Management (AIM) trial. In all, 890 participants (445 per group) will be randomly allocated to surgical or non-surgical treatment. Data regarding ankle function, QoL, complications, and healthcare-related costs will be collected at eight weeks, four and 12 months, and then annually for five years following treatment. The primary outcome measure is patient-reported ankle function at four months from treatment. Anticipated impact. The 12-month results will be presented and published internationally. This is anticipated to be the only pragmatic trial reporting outcomes comparing surgical with non-surgical treatment in unstable ankle fractures in younger adults (aged 60 years and younger), and, as such, will inform the National Institute for Health and Care Excellence (NICE) ‘non-complex fracture’ recommendations at their scheduled update in 2024. A report of long-term outcomes at five years will be produced by January 2027. Cite this article: Bone Jt Open 2024;5(3):184–201

Studies have shown that 10–30% patients do not achieve optimal function outcomes after total hip replacement (THR). High quality randomised controlled trials (RCTs) evaluating the clinical and cost-effectiveness of techniques to improve functional outcomes after THR are lacking. We performed this study to evaluate the feasibility of a RCT comparing patient-reported functional outcomes after hybrid or fully cemented THR (ISRCTN11097021). Patients were recruited from two centres and randomised to receive either a fully cemented or hybrid THR. Data collection included Patient Reported Outcome Measures (PROMs), non-serious adverse events of special interest (AESI), serious adverse device effects (SADE) and NHS resource use. Qualitative interviews were undertaken to understand a) patient experiences of study processes and their reasons for taking part or not, and b) to understand surgeons’ perceptions of the study, factors affecting willingness to participate, and barriers to implementation of the future RCT findings. The target of 40 patients were successfully recruited for the feasibility RCT; the ratio of successful recruitment to eligible patients was 0.61 across both sites. Treatment crossovers occurred in four patients, all related to bone quality. Four patients were withdrawn due to not undergoing surgery within the study window because of the pandemic. Follow-up was 100% and PROMs were completed by all patients at all time points. The feasibility of conducting a within-trial cost-utility analysis was demonstrated. Interviews were conducted with 27 patients and 16 surgeons. Patients and surgeons generally found the study procedures acceptable and workable. Some declined participation because they did not want treatment allocated at random, or because blinding was off-putting. Surgeons’ perceptions of equipoise varied, and implementation of findings from the future RCT would need to recognise the ‘craft’ nature of surgery and the issue of training. We conclude that a full RCT with economic analysis will be both feasible and practicable, although mechanisms to safely implement potential changes to practice because of RCT findings may need consideration by the wider arthroplasty community

Is Non-Weight-Bearing Necessary? (INWN) is a pragmatic multicentre randomised controlled trial comparing immediate protected weight-bearing (IWB) with non-weight-bearing cast immobilisation (NWB) following ankle fracture fixation (ORIF). This trial compares; functional outcomes, complication rates and performs an economic analysis to estimate cost-utility. IWB within 24hrs was compared to NWB, following ORIF of all types of unstable ankle fractures. Skeletally immature patients and tibial plafond fractures were excluded. Functional outcomes were assessed by the Olerud-Molander Ankle Score (OMAS) and RAND-36 Item Short Form Survey (SF-36) taken at regular follow-up intervals up to one year. A cost-utility analysis via decision tree modelling was performed to derive an incremental cost effectiveness ratio (ICER). A standard gamble health state valuation model utilising SF-36 scores was used to calculate Quality Adjusted Life Years (QALYs) for each arm. We recruited 160 patients (80 per arm), aged 15 to 94 years (M = 45.5), 54% female. Complication rates were similar in both groups. IWB demonstrated a consistently higher OMAS score, with significant values at 6 weeks (MD=10.4, p=0.005) and 3 months (MD 12.0, p=0.003). Standard gamble utility values demonstrated consistently higher values (a score of 1 equals perfect health) with IWB, significant at 3 months (Ẋ = 0.75 [IWB] / 0.69 [NWB], p=0.018). Cost-utility analysis demonstrated NWB is €798.02 more expensive and results in 0.04 fewer QALYs over 1 year. This results in an ICER of −€21,682.42/QALY. This negative ICER indicates cost savings of €21,682.42 for every QALY (25 patients = 1 QALY gain) gained implementing an IWB regime. IWB demonstrates a superior functional outcome, greater cost savings and similar complication rates, compared to NWB following ankle fracture fixation

Purpose and background. To evaluate the clinical and cost-effectiveness of a physical and psychological group intervention (BOOST programme) compared to physiotherapy assessment and advice (best practice advice [BPA]) for older adults with neurogenic claudication (NC) which is a debilitating spinal condition. Methods and results. A randomised controlled trial of 438 participants. The primary outcome was the Oswestry Disability Index (ODI) at 12 months. Data was also collected at 6 months. Other outcomes included Swiss Spinal Stenosis Questionnaire (symptoms), ODI walking item, 6-minute walk test (6MWT) and falls. The analysis was intention-to-treat. We collected the EQ5D and health and social care use to estimate cost-effectiveness. Participants were, on average, 74.9 years old (SD 6.0). There was no significant difference in ODI scores between groups at 12 months (adjusted mean difference (MD): −1.4 [95% Confidence Intervals (CI) −4.03,1.17]), but, at 6 months, ODI scores favoured the BOOST programme (adjusted MD: −3.7 [95% CI −6.27, −1.06]). Symptoms followed a similar pattern. The BOOST programme resulted in greater improvements in walking capacity (6MWT MD 21.7m [95% CI 5.96, 37.38]) and ODI walking item (MD −0.2 [95% CI −0.45, −0.01]) and reduced falls risk (odds ratio 0.6 [95% CI 0.40, 0.98]) compared to BPA at 12 months. Probability that the BOOST programme is cost-effective ranged from 67%–89% across cost-effectiveness thresholds. Conclusions. The BOOST programme improves mobility and reduces falls in older adults with NC compared to BPA at 12 months follow-up. It is good value for the NHS. Future iterations of the programme will consider ways to reduce symptoms and disability long-term. Conflicts of interest: No conflicts of interest. Sources of funding: National Institute of Health Research – Programme for Applied Research NIHR - PTC-RP-PG-0213-20002: Better Outcomes for Older people with Spinal Trouble (BOOST). Publication and presentations: The clinical effectiveness paper has just been accepted for publication in the Journal of Gerontology Series A. The health economic analysis is not yet published. It was presented at the Physiotherapy UK conference and the International Back and Neck Pain Forum in 2021

Abstract. Introduction. This multi-centre randomised controlled trial evaluated the clinical and cost effectiveness of liposomal bupivacaine for pain and recovery following knee replacement. Methodology. 533patients undergoing primary knee replacement were randomised to receive either liposomal bupivacaine (266mg) plus bupivacaine hydrochloride (100mg) or control (bupivacaine hydrochloride 100mg), administered at the surgical site. The co-primary outcomes were pain visual analogue score (VAS) area under the curve (AUC) 6 to 72hours and the Quality of Recovery 40 (QoR-40) score at 72hours. Results. Primary analysis found no difference in pain VAS AUC 6 to 72hours between liposomal bupivacaine and control (MD -21.5 (97.5% CI -46.8 to 3.8; p=0.057)), nor the QoR-40 at 72hours (MD 0.54, 97.5% CI -2.05 to 3.13, p=0.643). Analyses of pain VAS and QoR-40 scores on days 0, 1, 2 and 3 demonstrated only one significant difference, with the liposomal bupivacaine arm having lower pain scores the evening of surgery (day0; MD -0.54, 97.5% CI -1.07 to -0.02; p=0.021). No difference in cumulative opioid consumption or functional outcome at 6weeks, 6months or 1year was detected. Heath economic analysis found liposomal bupivacaine to be less effective in terms of QALYs as well as more costly. No difference in adverse events between arms was identified. Conclusion. This is the largest RCT evaluating the clinical and cost effectiveness of liposomal bupivacaine It found that compared to bupivacaine hydrochloride local infiltration of liposomal bupivacaine at the surgical site does not provide any clinical or cost benefit for knee replacement and therefore should not be routinely used

Aims. The aim of this study was to assess the quality and scope of the current cost-effectiveness analysis (CEA) literature in the field of hand and upper limb orthopaedic surgery. Materials and Methods. We conducted a systematic review of MEDLINE and the CEA Registry to identify CEAs that were conducted on or after 1 January 1997, that studied a procedure pertaining to the field of hand and upper extremity surgery, that were clinical studies, and that reported outcomes in terms of quality-adjusted life-years. We identified a total of 33 studies that met our inclusion criteria. The quality of these studies was assessed using the Quality of Health Economic Analysis (QHES) scale. Results. The mean total QHES score was 82 (high-quality). Over time, a greater proportion of these studies have demonstrated poorer QHES quality (scores < 75). Lower-scoring studies demonstrated several deficits, including failures in identifying reference perspectives, incorporating comparators and sensitivity analyses, discounting costs and utilities, and disclosing funding. Conclusion. It will be important to monitor the ongoing quality of CEA studies in orthopaedics and ensure standards of reporting and comparability in accordance with Second Panel recommendations. Cite this article: Bone Joint J 2018;100-B:1416–23

Robotic and navigated TKA procedures have been introduced to improve component placement precision for the purpose of improving implant survivorship and other clinical outcomes. Although numerous studies have shown enhanced precision in placing components, adoption of technology-assistance (TA) for TKA has been relatively slow. One reason for this has been the difficulty in demonstrating the cost-effectiveness of implementing TA-TKA systems and assessing their impact on revision rates. In this study, we aimed to use a simulation approach to answer the following questions: (1) Can we determine the distribution of likely reductions in TKA revision rates attributable to TA-TKA in an average US patient population? And, (2) What reduction in TKA revision rates are required to achieve economic neutrality?. In a previous study, we developed a method for creating large sets of simulated TKA patient populations with distributions of patient-specific factors (age at index surgery, sex, BMI) and one surgeon-controlled factor (coronal alignment) drawn from registry data and published literature. Effect sizes of each factor on implant survival was modeled using large clinical studies. For 10,000 simulated TKA patients, we simulated 20,000 TKA surgeries, evenly split between groups representing coronal alignment precisions reported for manual (±3°) and TA-TKA (±1.0°), calculating the patient-specific survival curve for each group. Extending our previous study, we incorporated the probability of each patient's expected survival into our model using publicly available actuarial data. This allowed us to calculate a patient-specific estimate of the Reduction in Lifetime Risk of Revision (RLRR) for each simulated patient. Our analysis showed that 90% of patients will achieve an RLRRof 1.5% or less in an average US TKA population. We then conducted a simplified economic analysis with the goal of determining the net cost of using TA-TKA per case when factoring in future savings by TKA revision rates. We assumed an average cost of revision surgery to be $75,000 as reported by Delanois (2017) and an average added cost incurred by TA-TKA to be $6,000 per case as reported by Antonis (2019). We estimate the net cost per TA-TKA case (CNet) to be the added cost per TA-TKA intervention (CInt), less the cost of revision surgery (CRev) multiplied by the estimated RLRR: CNet = CInt - CRev∗RLRR. We find that, under these assumptions, use of TA-TKA increases expected costs for all patients with an RLRR of under 8%. Based on these results, it appears that it would not be cost-effective to use TA-TKA on more than a small fraction of the typical US TKA patient population if the goal is to reduce overall costs through reducing revision risks. However, we note that this simulation does not consider other possible reported benefits of TA-TKA surgery, such as improved functional and pain outcome scores which may justify its use on other grounds. Alternative costs incurred by TA-TKA will be evaluated in a future study. To reach economic neutrality, TA-TKA systems either must reduce the added cost per intervention or increase RLRR by better addressing the root causes of revision

Background. There are advantages and disadvantages of Unicompartmental (UKR) and Total Knee Replacement, with UKR having better functional outcomes with fewer complications but a higher revision rate. The relative merits depend on patient characteristics. The aim was to compare UKR and TKR risk-benefits and cost-effectiveness in patients with severe systemic morbidity. Methods. Data from the National Joint Registry for England, Wales and Northern Ireland was linked to hospital inpatient and patient-reported outcomes data. Patients with American Society of Anesthesiologists (ASA) grade ≥3 undergoing UKR or TKR were identified. Propensity score stratification was used to compare 90-day complications and 5-year revision and mortality of 2,256 UKR and 57,682 TKR, and in a subset of 145 UKR and 23,344 TKR Oxford Knee Scores (OKS). A health-economic analysis was based on EQ-5D and NHS hospital costs. Results. The OKS was significantly better following UKR than TKR with a difference of 1.83 (95%CI 0.10–3.56). UKR was associated with lower relative risks of venous thromboembolism (0.33, CI0.15–0.74), myocardial infarction (0.73, CI0.36–1.45) and early joint infection (0.85, CI0.33–2.19) but only the decrease in venous thromboembolism was significant. The revision risk following UKR was significantly higher than following TKR (hazard ratio 2.70, CI2.15–3.38) and the mortality was significantly lower (0.52, CI0.36–0.74). At five years the cumulative incidence of revision was 8% higher with UKR, and the cumulative incidence of death was 13% lower. The health economic analysis found that UKR dominated TKR having lower costs (£359, CI340-378) and higher quality-of-life gains (0.33, CI-0.31–0.970). Conclusions. For patients with ASA ≥3, UKR was safer and more cost-effective than TKR. In particular if UKR was used instead of TKR the number of lives saved was higher than the number of extra revisions. UKR should be considered the first option for suitable patients with severe co-morbidity