Aims. Malignancy and surgery are risk factors for venous thromboembolism (VTE). We undertook a systematic review of the literature concerning the prophylactic management of VTE in orthopaedic oncology patients. Methods. MEDLINE (PubMed), EMBASE (Ovid), Cochrane, and CINAHL databases were searched focusing on VTE, deep vein thrombosis (DVT), pulmonary embolism (PE), bleeding, or wound complication rates. Results. In all, 17 studies published from 1998 to 2018 met the inclusion criteria for the systematic review. The mean incidence of all VTE events in orthopaedic oncology patients was 10.7% (1.1% to 27.7%). The rate of PE was 2.4% (0.1% to 10.6%) while the rate of lethal PE was 0.6% (0.0% to 4.3%). The overall rate of DVT was 8.8% (1.1% to 22.3%) and the rate of symptomatic DVT was 2.9% (0.0% to 6.2%). From the studies that screened all patients prior to hospital discharge, the rate of asymptomatic DVT was 10.9% (2.0% to 20.2%). The most common risk factors identified for VTE were endoprosthetic replacements, hip and pelvic resections, presence of metastases, surgical procedures taking longer than three hours, and patients having chemotherapy. Mean incidence of VTE with and without chemical prophylaxis was 7.9% (1.1% to 21.8%) and 8.7% (2.0% to 23.4%; p = 0.11), respectively. No difference in the incidence of bleeding or wound complications between prophylaxis groups was reported. Conclusion. Current evidence is limited to guide clinicians. It is our consensus opinion, based upon logic and deduction, that all patients be considered for both mechanical and chemical VTE prophylaxis, particularly in high-risk patients (pelvic or hip resections, prosthetic reconstruction, malignant diagnosis, presence of metastases, or surgical procedures longer than three hours). Additionally, the surgeon must determine, in each patient, if the risk of haemorrhage outweighs the risk of VTE. No individual pharmacological agent has been identified as being superior in the prevention of VTE events. Cite this article: Bone Joint J 2020;102-B(12)1743:–1751

Aims. We conducted a systematic review and meta-analysis to compare the mortality, morbidity, and functional outcomes of cemented versus uncemented hemiarthroplasty in the treatment of intracapsular hip fractures, analyzing contemporary and non-contemporary implants separately. Methods. PubMed, Medline, EMBASE, CINAHL, and Cochrane Library were searched to 2 February 2020 for randomized controlled trials (RCTs) comparing the primary outcome, mortality, and secondary outcomes of function, quality of life, reoperation, postoperative complications, perioperative outcomes, pain, and length of hospital stay. Relative risks (RRs) and mean differences (with 95% confidence intervals (CIs)) were used as summary association measures. Results. A total of 18 studies corresponding to 16 non-overlapping RCTs with a total of 2,819 intracapsular hip fractures were included. Comparing contemporary cemented versus uncemented hemiarthroplasty, RRs (95% CIs) for mortality were 1.32 (0.44 to 3.99) perioperatively, 1.01 (0.48 to 2.10) at 30 days, and 0.90 (0.71 to 1.15) at one year. The use of contemporary cemented hemiarthroplasty reduced the risk of intra- and postoperative periprosthetic fracture. There were no significant differences in the risk of other complications, function, pain, and quality of life. There were no significant differences in perioperative outcomes except for increases in operating time and overall anaesthesia for contemporary cemented hemiarthroplasty with mean differences (95% CIs) of 6.67 (2.65 to 10.68) and 4.90 (2.02 to 7.78) minutes, respectively. The morbidity and mortality outcomes were not significantly different between non-contemporary cemented and uncemented hemiarthroplasty. Conclusion. There are no differences in the risk of mortality when comparing the use of contemporary cemented with uncemented hemiarthroplasty in the management of intracapsular hip fractures. Contemporary cemented hemiarthroplasty is associated with a substantially lower risk of intraoperative and periprosthetic fractures. Cite this article: Bone Joint J 2020;102-B(9):1113–1121

Aims. The purpose of this study was to: review the efficacy of the induced membrane technique (IMT), also known as the Masquelet technique; and investigate the relationship between patient factors and technique variations on the outcomes of the IMT. Methods. A systematic search was performed in CINAHL, The Cochrane Library, Embase, Ovid MEDLINE, and PubMed. We included articles from 1 January 1980 to 30 September 2019. Studies with a minimum sample size of five cases, where the IMT was performed primarily in adult patients (≥ 18 years old), in a long bone were included. Multivariate regression models were performed on patient-level data to determine variables associated with nonunion, postoperative infection, and the need for additional procedures. Results. A total of 48 studies were included, with 1,386 cases treated with the IMT. Patients had a mean age of 40.7 years (4 to 88), and the mean defect size was 5.9 cm (0.5 to 26). In total, 82.3% of cases achieved union after the index second stage procedure. The mean time to union was 6.6 months (1.4 to 58.7) after the second stage. Our multivariate analysis of 450 individual patients showed that the odds of developing a nonunion were significantly increased in those with preoperative infection. Patients with tibial defects, and those with larger defects, were at significantly higher odds of developing a postoperative infection. Our analysis also demonstrated a trend towards the inclusion of antibiotics in the cement spacer having a protective effect against the need for additional procedures. Conclusion. The IMT is an effective management strategy for complex segmental bone defects. Standardized reporting of individual patient data or larger prospective trials is required to determine the optimal implementation of this technique. This is the most comprehensive review of the IMT, and the first to compile individual patient data and use regression models to determine predictors of outcomes. Cite this article: Bone Joint J 2020;102-B(12):1723–1734

Aims. To analyze outcomes reported in trials of childhood fractures. Methods. OVID MEDLINE, Embase, and Cochrane CENTRAL databases were searched on the eighth August 2019. A manual search of trial registries, bibliographic review and internet search was used to identify additional studies. 11,476 studies were screened following PRISMA guidelines. 100 trials were included in the analysis. Data extraction was completed by two researchers for each trial. Study quality was not evaluated. Outcomes reported by trials were mapped onto domains in the World Health Organization (WHO) International Classification of Function framework. Results. In all, 525 outcomes were identified representing 52 WHO domains. Four domains were reported in more than 50% of trials: structure of upper/lower limb, sensation of pain, mobility of joint function, and health services, systems and policies. The Activities Scale for Kids performance (ASK-p) score was the most common outcome score reported in 6/72 upper limb and 4/28 lower limb trials. Conclusion. There is a diverse range of outcomes reported in trials of childhood fractures covering all areas in the International Classification of Functioning, Disability and Health (ICF) framework. There were three common upper limb and three common lower limb outcomes. In the absence of a core outcome set, we recommend that upper limb trials report pain, range of movement and radiograph appearance of the arm and lower limb trials report pain, radiograph appearance of the leg and healthcare costs to improve consistency of reporting in future trials. Cite this article: Bone Joint Open 2020;1-5:167–174

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

Aim. The coronavirus disease 2019 (COVID-19) pandemic presents significant challenges to healthcare systems globally. Orthopaedic surgeons are at risk of contracting COVID-19 due to their close contact with patients in both outpatient and theatre environments. The aim of this review was to perform a literature review, including articles of other coronaviruses, to formulate guidelines for orthopaedic healthcare staff. Methods. A search of Medline, EMBASE, the Cochrane Library, World Health Organization (WHO), and Centers for Disease Control and Prevention (CDC) databases was performed encompassing a variety of terms including ‘coronavirus’, ‘covid-19’, ‘orthopaedic’, ‘personal protective environment’ and ‘PPE’. Online database searches identified 354 articles. Articles were included if they studied any of the other coronaviruses or if the basic science could potentially applied to COVID-19 (i.e. use of an inactivated virus with a similar diameter to COVID-19). Two reviewers independently identified and screened articles based on the titles and abstracts. 274 were subsequently excluded, with 80 full-text articles retrieved and assessed for eligibility. Of these, 66 were excluded as they compared personal protection equipment to no personal protection equipment or referred to prevention measures in the context of bacterial infections. Results. There is a paucity of high quality evidence surrounding COVID-19. This review collates evidence from previous coronavirus outbreaks to put forward recommendations for orthopaedic surgeons during the COVID-19 pandemic. The key findings have been summarized and interpreted for application to the orthopaedic operative setting. Conclusion. For COVID-19 positive patients, minimum suggested PPE includes N95 respirator, goggles, face shield, gown, double gloves, and surgical balaclava. Space suits not advised. Be trained in the correct technique of donning and doffing PPE. Use negative pressure theatres if available. Minimize aerosolization and its effects (smoke evacuation and no pulse lavage). Minimize further unnecessary patient-staff contact (dissolvable sutures, clear dressings, split casts)

Aims. The aims of this study were to validate the outcome of total elbow arthroplasty (TEA) in patients with rheumatoid arthritis (RA), and to identify factors that affect the outcome. Methods. We searched PubMed, MEDLINE, Cochrane Reviews, and Embase from between January 2003 and March 2019. The primary aim was to determine the implant failure rate, the mode of failure, and risk factors predisposing to failure. A secondary aim was to identify the overall complication rate, associated risk factors, and clinical performance. A meta-regression analysis was completed to identify the association between each parameter with the outcome. Results. A total of 38 studies including 2,118 TEAs were included in the study. The mean follow-up was 80.9 months (8.2 to 156). The implant failure and complication rates were 16.1% (95% confidence interval (CI) 0.128 to 0.200) and 24.5% (95% CI 0.203 to 0.293), respectively. Aseptic loosening was the most common mode of failure (9.5%; 95% CI 0.071 to 0.124). The mean postoperative ranges of motion (ROMs) were: flexion 131.5° (124.2° to 138.8°), extension 29.3° (26.8° to 31.9°), pronation 74.0° (67.8° to 80.2°), and supination 72.5° (69.5° to 75.5°), and the mean postoperative Mayo Elbow Performance Score (MEPS) was 89.3 (95% CI 86.9 to 91.6). The meta-regression analysis identified that younger patients and implants with an unlinked design correlated with higher failure rates. Younger patients were associated with increased complications, while female patients and an unlinked prosthesis were associated with aseptic loosening. Conclusion. TEA continues to provide satisfactory results for patients with RA. However, it is associated with a substantially higher implant failure and complication rates compared with hip and knee arthroplasties. The patient’s age, sex, and whether cemented fixation and unlinked prosthesis were used can influence the outcome. Level of Evidence: Therapeutic Level IV. Cite this article: Bone Joint J 2020;102-B(8):967–980

The application of robotics in the operating theatre for knee arthroplasty remains controversial. As with all new technology, the introduction of new systems might be associated with a learning curve. However, guidelines on how to assess the introduction of robotics in the operating theatre are lacking. This systematic review aims to evaluate the current evidence on the learning curve of robot-assisted knee arthroplasty. An extensive literature search of PubMed, Medline, Embase, Web of Science, and Cochrane Library was conducted. Randomized controlled trials, comparative studies, and cohort studies were included. Outcomes assessed included: time required for surgery, stress levels of the surgical team, complications in regard to surgical experience level or time needed for surgery, size prediction of preoperative templating, and alignment according to the number of knee arthroplasties performed. A total of 11 studies met the inclusion criteria. Most were of medium to low quality. The operating time of robot-assisted total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA) is associated with a learning curve of between six to 20 cases and six to 36 cases respectively. Surgical team stress levels show a learning curve of seven cases in TKA and six cases for UKA. Experience with the robotic systems did not influence implant positioning, preoperative planning, and postoperative complications. Robot-assisted TKA and UKA is associated with a learning curve regarding operating time and surgical team stress levels. Future evaluation of robotics in the operating theatre should include detailed measurement of the various aspects of the total operating time, including total robotic time and time needed for preoperative planning. The prior experience of the surgical team should also be evaluated and reported. Cite this article: Bone Joint J 2020;102-B(4):407–413

Aims. Metabolic profiling is a top-down method of analysis looking at metabolites, which are the intermediate or end products of various cellular pathways. Our primary objective was to perform a systematic review of the published literature to identify metabolites in human synovial fluid (HSF), which have been categorized by metabolic profiling techniques. A secondary objective was to identify any metabolites that may represent potential biomarkers of orthopaedic disease processes. Methods. A systematic review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines using the MEDLINE, Embase, PubMed, and Cochrane databases. Studies included were case series, case control series, and cohort studies looking specifically at HSF. Results. The primary analysis, which pooled the results from 17 published studies and four meeting abstracts, identified over 200 metabolites. Seven of these studies (six published studies, one meeting abstract) had asymptomatic control groups and collectively suggested 26 putative biomarkers in osteoarthritis, inflammatory arthropathies, and trauma. These can broadly be categorized into amino acids plus related metabolites, fatty acids, ketones, and sugars. Conclusion. The role of metabolic profiling in orthopaedics is fast evolving with many metabolites already identified in a variety of pathologies. However, these results need to be interpreted with caution due to the presence of multiple confounding factors in many of the studies. Future research should include largescale epidemiological metabolic profiling studies incorporating various confounding factors with appropriate statistical analysis to account for multiple testing of the data. Cite this article:Bone Joint Res. 2020;9(3):108–119

Aims. The aims of this systematic review were to describe the quantity and methodological quality of meta-analyses in orthopaedic surgery published during the last 17 years. Materials and Methods. MEDLINE, EMBASE, and PubMed, between 1 January 2000 and 31 December 2016, were searched for meta-analyses in orthopaedic surgery dealing with at least one surgical intervention. Meta-analyses were included if the interventions involved a human muscle, ligament, bone or joint. Results. A total of 392 meta-analyses met eligibility criteria, for which the mean AMSTAR quality score was 7.1/11. There was a positive correlation between the year of publication and the quality of the meta-analysis (r = 0.238, p < 0.001). Between 2000 and 2011, the mean AMSTAR score corresponded to that of a medium quality review. However, between 2012 and 2016, the mean scores have been consistently equivalent to those of a high-quality review. The number of meta-analyses published increased 10-fold between 2005 and 2014. Conclusion. The quantity and quality of meta-analyses in orthopaedic surgery which have been published has increased, reaching a plateau in 2012. Methodological flaws remain to be addressed in future meta-analyses in order to continue increasing the quality of the orthopaedic literature. Cite this article: Bone Joint J 2018;100-B:1270–4

Aims. Computer-based applications are increasingly being used by orthopaedic surgeons in their clinical practice. With the integration of technology in surgery, augmented reality (AR) may become an important tool for surgeons in the future. By superimposing a digital image on a user’s view of the physical world, this technology shows great promise in orthopaedics. The aim of this review is to investigate the current and potential uses of AR in orthopaedics. Materials and Methods. A systematic review of the PubMed, MEDLINE, and Embase databases up to January 2019 using the keywords ‘orthopaedic’ OR ‘orthopedic AND augmented reality’ was performed by two independent reviewers. Results. A total of 41 publications were included after screening. Applications were divided by subspecialty: spine (n = 15), trauma (n = 16), arthroplasty (n = 3), oncology (n = 3), and sports (n = 4). Out of these, 12 were clinical in nature. AR-based technologies have a wide variety of applications, including direct visualization of radiological images by overlaying them on the patient and intraoperative guidance using preoperative plans projected onto real anatomy, enabling hands-free real-time access to operating room resources, and promoting telemedicine and education. Conclusion. There is an increasing interest in AR among orthopaedic surgeons. Although studies show similar or better outcomes with AR compared with traditional techniques, many challenges need to be addressed before this technology is ready for widespread use. Cite this article: Bone Joint J 2019;101-B:1479–1488

Aims. Postoperative rehabilitation regimens following ankle arthrodesis vary considerably. A systematic review was conducted to determine the evidence for weightbearing recommendations following ankle arthrodesis, and to compare outcomes between different regimens. Patients and Methods. MEDLINE, Web of Science, Embase, and Scopus databases were searched for studies reporting outcomes following ankle arthrodesis, in which standardized postoperative rehabilitation regimens were employed. Eligible studies were grouped according to duration of postoperative nonweightbearing: zero to one weeks (group A), two to three weeks (group B), four to five weeks (group C), or six weeks or more (group D). Outcome data were pooled and compared between groups. Outcomes analyzed included union rates, time to union, clinical scores, and complication rates. Results. A total of 60 studies (2426 ankles) were included. Mean union rates for groups A to D were 93.2%, 95.5%, 93.0%, and 93.0%, respectively. Mean time to union was 10.4 weeks, 14.5 weeks, 12.4 weeks, and 14.4 weeks for groups A to D, respectively. Mean complication rates were 22.3%, 23.0%, 27.1%, and 28.7% for groups A to D, respectively. Reporting of outcome scores was insufficient to conduct meaningful analysis. Conclusion. Outcomes following ankle arthrodesis appear to be similar regardless of the duration of postoperative nonweightbearing, although the existing literature is insufficient to make definitive conclusions. Cite this article: Bone Joint J 2019;101-B:1256–1262

Aims. The purpose of this study was to compare the effectiveness of surgical repair to conservative treatment and subacromial decompression for the treatment of chronic/degenerative tears of the rotator cuff. Materials and Methods. PubMed, Cochrane database, and Medline were searched for randomized controlled trials published until March 2018. Included studies were assessed for methodological quality, and data were extracted for statistical analysis. The systematic review was conducted following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Results. Six studies were included. Surgical repair resulted in a statistically significantly better Constant–Murley Score (CMS) at one year compared with conservative treatment (mean difference 6.15; p = 0.002) and subacromial decompression alone (mean difference 5.81; p = 0.0004). In the conservatively treated group, 11.9% of patients eventually crossed over to surgical repair. Conclusion. The results of this review show that surgical repair results in significantly improved outcomes when compared with either conservative treatment or subacromial decompression alone for degenerative rotator cuff tears in older patients. However, the magnitude of the difference in outcomes between surgery and conservative treatment may be small and the ‘success rate’ of conservative treatment may be high, allowing surgeons to be judicious in choosing those patients who are most likely to benefit from surgery. Cite this article: Bone Joint J 2019;101-B:1100–1106

Objectives. The aim of this study was to review the impact of smoking tobacco on the musculoskeletal system, and on bone fractures in particular. Methods. English-language publications of human and animal studies categorizing subjects into smokers and nonsmokers were sourced from MEDLINE, The Cochrane Library, and SCOPUS. This review specifically focused on the risk, surgical treatment, and prevention of fracture complications in smokers. Results. Smokers have an increased risk of fracture and experience more complications with delayed bone healing, even if they have already stopped smoking, because some adverse effects persist for a prolonged period. Some risks can be reduced during and after surgery by local and general prevention, and smoking cessation is an important factor in lessening this risk. However, if a patient wants to stop smoking at the time of a fracture, the cessation strategies in reducing tobacco use are not easy to implement. The patient should also be warned that using e-cigarettes or other tobaccos does not appear to reduce adverse effects on health. Conclusion. The evidence reviewed in this study shows that smoking has a negative effect in terms of the risk and treatment of fractures. Cite this article: J. Hernigou, F. Schuind. Tobacco and bone fractures: A review of the facts and issues that every orthopaedic surgeon should know. Bone Joint Res 2019;8:255–265. DOI: 10.1302/2046-3758.86.BJR-2018-0344.R1

Aims. Short-stemmed femoral implants have been used for total hip arthroplasty (THA) in young and active patients to conserve bone, provide physiological loading, and reduce the incidence of thigh pain. Only short- to mid-term results have been presented and there have been concerns regarding component malalignment, incorrect sizing, and subsidence. This systematic review reports clinical and radiological outcomes, complications, revision rates, and implant survival in THA using short-stemmed femoral components. Materials and Methods. A literature review was performed using the EMBASE, Medline, and Cochrane databases. Strict inclusion and exclusion criteria were used to identify studies reporting clinical and radiological follow-up for short-stemmed hip arthroplasties. Results. A total of 28 studies were eligible for inclusion. This included 5322 hips in 4657 patients with a mean age of 59 years (13 to 94). The mean follow-up was 6.1 years (0.5 to 20). The mean Harris Hip Score improved from 46 (0 to 100) to 92 (39 to 100). The mean Oxford Hip Score improved from 25 (2 to 42.5) to 35 (12.4 to 48). The mean Western Ontario & McMaster Universities Osteoarthritis Index improved from 54 (2 to 95) to 22 (0 to 98). Components were aligned in a neutral coronal alignment in up to 90.9% of cases. A total of 15 studies reported component survivorship, which was 98.6% (92% to 100%) at a mean follow-up of 12.1 years. Conclusion. Short-stemmed femoral implants show similar improvement in clinical and radiological outcomes compared with conventional length implants. Only mid-term survivorship, however, is known. An abundance of short components have been developed and used commercially without staged clinical trials. Long-term survival is still unknown for many of these components. There remains tension between innovation and the moral duty to ensure that the introduction of new implants is controlled until safety and patient benefit are demonstrated. Implant innovation and subsequent use should be driven by proven clinical outcomes, rather than market and financial forces, and ethical practice must be ensured. Cite this article: Bone Joint J 2019;101-B:502–511

Aims. We performed a meta-analysis investigating the association between preoperative psychological distress and postoperative pain and function after total knee arthroplasty (TKA). Materials and Methods. Pubmed/Medline, Embase, PsycINFO, and the Cochrane library were searched for studies on the influence of preoperative psychological distress on postoperative pain and physical function after TKA. Two blinded reviewers screened for eligibility and assessed the risk of bias and the quality of evidence. We used random effects models to pool data for the meta-analysis. Results. Six prospective cohort studies, with a total of 1525 patients, were included. The random effects models showed significantly poorer outcomes in patients who preoperatively had elevated scores on the pain catastrophizing scale, worse 36-Item Short-Form Health Survey (SF-36) mental health score, symptoms of anxiety and/or depression, and somatization dysfunction. After 12 months, the standard mean difference for pain was −0.74 (95% confidence interval (CI) −1.04 to −0.44) and −0.56 (95% CI −0.80 to −0.32) for function. Conclusion. Preoperative pain catastrophizing, mental distress, symptoms of anxiety and/or depression, and somatoform disorders appear to adversely affect pain and function after TKA. Some patients undergoing TKA may therefore need psychological support to improve the outcome and quality of life

Aims. Prosthetic joint infection (PJI) remains a serious complication that is associated with high morbidity and costs. The aim of this study was to prepare a systematic review to examine patient-related and perioperative risk factors that can be modified in an attempt to reduce the rate of PJI. Materials and Methods. A search of PubMed and MEDLINE was conducted for articles published between January 1990 and February 2018 with a combination of search terms to identify studies that dealt with modifiable risk factors for reducing the rate of PJI. An evidence-based review was performed on 12 specific risk factors: glycaemic control, obesity, malnutrition, smoking, vitamin D levels, preoperative Staphylococcus aureus screening, the management of anti-rheumatic medication, perioperative antibiotic prophylaxis, presurgical skin preparation, the operating room environment, irrigant options, and anticoagulation. Results. Poor glycaemic control, obesity, malnutrition, and smoking are all associated with increased rates of PJI. Vitamin D replacement has been shown in preliminary animal studies to decrease rates of PJI. Preoperative Staphylococcus aureus screening and appropriate treatment results in decreased rates of PJI. Perioperative variables, such as timely and appropriate dosage of prophylactic antibiotics, skin preparation with chlorohexidine-based solution, and irrigation with dilute betadine at the conclusion of the operation, have all been associated with reduced rates of PJI. Similarly, aggressive anticoagulation and increased operating room traffic should be avoided to help minimize risk of PJI. Conclusion. PJI remains a serious complication of arthroplasty. Surgeons should be vigilant of the modifiable risk factors that can be addressed in an attempt to reduce the risk of PJI

Aims. Robotic-assisted unicompartmental knee arthroplasty (UKA) promises accurate implant placement with the potential of improved survival and functional outcomes. The aim of this study was to present the current evidence for robotic-assisted UKA and describe the outcome in terms of implant positioning, range of movement (ROM), function and survival, and the types of robot and implants that are currently used. Materials and Methods. A search of PubMed and Medline was performed in October 2018 in line with the Preferred Reporting Items for Systematic Review and Meta-Analysis statement. Search terms included “robotic”, “knee”, and “surgery”. The criteria for inclusion was any study describing the use of robotic UKA and reporting implant positioning, ROM, function, and survival for clinical, cadaveric, or dry bone studies. Results. A total of 528 articles were initially identified from the databases and reference lists. Following full text screening, 38 studies that satisfied the inclusion criteria were included. In all, 20 studies reported on implant positioning, 18 on functional outcomes, 16 on survivorship, and six on ROM. The Mako (Stryker, Mahwah, New Jersey) robot was used in 32 studies (84%), the BlueBelt Navio (Blue Belt Technologies, Plymouth, Minnesota) in three (8%), the Sculptor RGA (Stanmore Implants, Borehamwood United Kingdom) in two (5%), and the Acrobot (The Acrobot Co. Ltd., London, United Kingdom) in one study (3%). The most commonly used implant was the Restoris MCK (Stryker). Nine studies (24%) did not report the implant that was used. The pooled survivorship at six years follow-up was 96%. However, when assessing survival according to implant design, survivorship of an inlay (all-polyethylene) tibial implant was 89%, whereas that of an onlay (metal-backed) implant was 97% at six years (odds ratio 3.66, 95% confidence interval 20.7 to 6.46, p < 0.001). Conclusion. There is little description of the choice of implant when reporting robotic-assisted UKA, which is essential when assessing survivorship, in the literature. Implant positioning with robotic-assisted UKA is more accurate and more reproducible than that performed manually and may offer better functional outcomes, but whether this translates into improved implant survival in the mid- to longer-term remains to be seen. Cite this article: Bone Joint J 2019;101-B:838–847

Aims. Surface replacement arthroplasty (SRA), compared with traditional total hip arthroplasty (THA), is more expensive and carries unique concern related to metal ions production and hypersensitivity. Additionally, SRA is a more demanding procedure with a decreased margin for error compared with THA. To justify its use, SRA must demonstrate comparable component survival and some clinical advantages. We therefore performed a systematic literature review to investigate the differences in complication rates, patient-reported outcomes, stress shielding, and hip biomechanics between SRA and THA. Materials and Methods. A systematic review of the literature was completed using MEDLINE and EMBASE search engines. Inclusion criteria were level I to level III articles that reported clinical outcomes following primary SRA compared with THA. An initial search yielded 2503 potential articles for inclusion. Exclusion criteria included review articles, level IV or level V evidence, less than one year’s follow-up, and previously reported data. In total, 27 articles with 4182 patients were available to analyze. Results. Fracture and infection rates were similar between SRA and THA, while dislocation rates were lower in SRA compared with THA. SRA demonstrated equivalent patient-reported outcome scores with greater activity scores and a return to high-level activities compared with THA. SRA more reliably restored native hip joint biomechanics and decreased stress shielding of the proximal femur compared with THA. Conclusion. In young active men with osteoarthritis, there is evidence that SRA offers some potential advantages over THA, including: improved return to high level activities and sport, restoration of native hip biomechanics, and decreased proximal femoral stress shielding. Continued long-term follow up is required to assess ultimate survivorship of SRA

Aims

Perthes' disease (PD) is a relatively rare syndrome of idiopathic osteonecrosis of the proximal femoral epiphysis. Treatment for Perthes' disease is controversial due to the many options available, with no clear superiority of one treatment over another. Despite having few evidence-based approaches, many patients with Perthes' disease are managed surgically. Positive outcome reporting, defined as reporting a study variable producing statistically significant positive (beneficial) results, is a phenomenon that can be considered a proxy for the strength of science. This study aims to conduct a systematic literature review with the hypothesis that positive outcome reporting is frequent in studies on the treatment of Perthes' disease.