Objectives. The use of the haptically bounded saw blades in robotic-assisted total knee arthroplasty (RTKA) can potentially help to limit surrounding soft-tissue injuries. However, there are limited data characterizing these injuries for cruciate-retaining (CR) TKA with the use of this technique. The objective of this cadaver study was to compare the extent of soft-tissue damage sustained through a robotic-assisted, haptically guided TKA (RATKA) versus a manual TKA (MTKA) approach. Methods. A total of 12 fresh-frozen pelvis-to-toe cadaver specimens were included. Four surgeons each prepared three RATKA and three MTKA specimens for cruciate-retaining TKAs. A RATKA was performed on one knee and a MTKA on the other. Postoperatively, two additional surgeons assessed and graded damage to 14 key anatomical structures in a blinded manner. Kruskal–Wallis hypothesis tests were performed to assess statistical differences in soft-tissue damage between RATKA and MTKA cases. Results. Significantly less damage occurred to the PCLs in the RATKA versus the MTKA specimens (p < 0.001). RATKA specimens had non-significantly less damage to the deep medial collateral ligaments (p = 0.149), iliotibial bands (p = 0.580), poplitei (p = 0.248), and patellar ligaments (p = 0.317). The remaining anatomical structures had minimal soft-tissue damage in all MTKA and RATKA specimens. Conclusion. The results of this study indicate that less soft-tissue damage may occur when utilizing RATKA compared with MTKA. These findings are likely due to the enhanced preoperative planning with the robotic software, the real-time intraoperative feedback, and the haptically bounded saw blade, all of which may help protect the surrounding soft tissues and ligaments. Cite this article: Bone Joint Res 2019;8:495–501

Aims

The objective of this study is to assess the use of ultrasound (US) as a radiation-free imaging modality to reconstruct 3D anatomy of the knee for use in preoperative templating in knee arthroplasty.

We report the clinical and radiological results of a two- to three-year prospective randomised study which was designed to compare a minimally-invasive technique with a standard technique in total knee replacement and was undertaken between January 2004 and May 2007. The mini-midvastus approach was used on 50 patients (group A) and a standard approach on 50 patients (group B). The mean follow-up in both groups was 23 months (24 to 35). The functional outcome was better in group A up to nine months after operation, as shown by statistically significant differences in the mean function score, mean total score and the mean Oxford knee score (all, p = 0.05). Patients in group A had statistically significant greater early flexion (p = 0.04) and reached their greatest mean knee flexion of 126.5° (95° to 135°) 21 days after operation. However, at final follow-up there was no significant difference in the mean maximum flexion between the groups (p = 0.08). Technical errors were identified in six patients from group A (12%) on radiological evaluation. Based on these results, the authors currently use minimally-invasive techniques in total knee replacement in selected cases only

Introduction

The objective of this study is to assess the use of ultrasound (US) as a radiation free imaging modality to reconstruct three-dimensional knee anatomy.

Introduction

Arthrofibrosis remains a persistent complication following total knee arthroplasty (TKA). Although manipulation under anesthesia (MUA) is an effective early treatment, the risks and value of this procedure beyond 3 months after TKA remain controversial. The purpose of this study was to examine the safety and efficacy of late MUAs for arthrofibrosis.

This prospective study describes the complications and survival of the first 688 Phase 3 Oxford medial unicompartmental knee replacements implanted using a minimally-invasive technique by two surgeons and followed up independently. None was lost to follow-up. We had carried out 132 of the procedures more than five years ago. The clinical assessment of 101 of these which were available for review at five years is also presented.

Nine of the 688 knees were revised: four for infection, three for dislocation of the bearing and two for unexplained pain. A further seven knees (1%) required other procedures: four had a manipulation under anaesthesia, two an arthroscopy and one a debridement for superficial infection. The survival rate at seven years was 97.3% (95% confidence interval 5.3). At five years, 96% of the patients had a good or excellent American Knee Society score, the mean Oxford knee score was 39 and the mean flexion was 133°. This study demonstrates that the minimally-invasive Oxford unicompartmental knee replacement is a reliable and effective procedure.

Pain is the main indication for performing total knee replacement (TKR). In most patients after TKR there is an improvement, but a few continue to have pain. Generally, the cause of the pain can be addressed when it is identified. However, unexplained pain can be more difficult to manage because revision surgery is likely to be unrewarding in this group. In our study of 622 cemented TKRs in 512 patients with a mean age of 69 years (23 to 90) treated between January 1995 and August 1998, we identified 24 patients (knees) with unexplained pain at six months. This group was followed for five years (data was unavailable for 18 knees) and ten patients (55.5%) went on to show an improvement without intervention.

In the case of unexplained pain, management decisions must be carefully considered, but reassurance can be offered to patients that the pain will improve in more than half with time.

The kinematic alignment (KA) approach to total knee arthroplasty (TKA) has recently increased in popularity. Accordingly, a number of derivatives have arisen and have caused confusion. Clarification is therefore needed for a better understanding of KA-TKA. Calipered (or true, pure) KA is performed by cutting the bone parallel to the articular surface, compensating for cartilage wear. In soft-tissue respecting KA, the tibial cutting surface is decided parallel to the femoral cutting surface (or trial component) with in-line traction. These approaches are categorized as unrestricted KA because there is no consideration of leg alignment or component orientation. Restricted KA is an approach where the periarthritic joint surface is replicated within a safe range, due to concerns about extreme alignments that have been considered ‘alignment outliers’ in the neutral mechanical alignment approach. More recently, functional alignment and inverse kinematic alignment have been advocated, where bone cuts are made following intraoperative planning, using intraoperative measurements acquired with computer assistance to fulfill good coordination of soft-tissue balance and alignment. The KA-TKA approach aims to restore the patients’ own harmony of three knee elements (morphology, soft-tissue balance, and alignment) and eventually the patients’ own kinematics. The respective approaches start from different points corresponding to one of the elements, yet each aim for the same goal, although the existing implants and techniques have not yet perfectly fulfilled that goal

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

Aims. Thresholds of acceptable early migration of the components in total knee arthroplasty (TKA) have traditionally ignored the effects of patient and implant factors that may influence migration. The aim of this study was to determine which of these factors are associated with overall longitudinal migration of well-fixed tibial components following TKA. Methods. Radiostereometric analysis (RSA) data over a two-year period were available for 419 successful primary TKAs (267 cemented and 152 uncemented in 257 female and 162 male patients). Longitudinal analysis of data using marginal models was performed to examine the associations of patient factors (age, sex, BMI, smoking status) and implant factors (cemented or uncemented, the size of the implant) with maximum total point motion (MTPM) migration. Analyses were also performed on subgroups based on sex and fixation. Results. In the overall group, only fixation was significantly associated with migration (p < 0.001). For uncemented tibial components in males, smoking was significantly associated with lower migration (p = 0.030) and BMI approached significance (p = 0.061). For females with uncemented components, smoking (p = 0.081) and age (p = 0.063) approached significance and were both associated with increased migration. The small number of self-reported smokers in this study warrants cautious interpretation and further investigation. For cemented components in females, larger sizes of tibial component were significantly associated with increased migration (p = 0.004). No factors were significant for cemented components in males. Conclusion. The migration of uncemented tibial components was more sensitive to patient factors than cemented implants. These differences were not consistent by sex, suggesting that it may be of value to evaluate female and male patients separately following TKA. Cite this article: Bone Joint J 2022;104-B(4):444–451

Abstract. INTRODUCTION. COVID-19 reduced availability of cross-sectional imaging, prompting the need to clinically justify pre-operative computed tomography (CT) in tibial plateau fractures (TPF). The study purpose was to establish to what extent does a CT alter the pre-operative plan in TPF compared to radiographs. There is a current paucity of evidence assessing its impact on surgical planning. METHODOLOGY. 50 consecutive TPF with preoperative CT were assessed by 4 consultant surgeons. Anonymised radiographs were assessed defining the column classification, planned setup, approach, and fixation technique. At a 1-month interval, randomised matched CT scans were assessed and the same data collected. A tibial plateau disruption score (TPDS) was derived for all 4 quadrants (no injury=0,split=1,split/depression=2 and depression=3). Radiograph and CT TPDS were assessed using an unpaired T-test. RESULTS. 26 female and 24 male patients, mean age 50.3, were included. Mean TPDS on radiographs and CT scans were 2.77 and 3.17 respectively. A significant higher net CT TPDS was observed of 0.4 (95%CI 0.10-0.71)[P=0.0093]. Both radiograph and CT TPDS ANOVA were significant (P<0.0001), showing high intraobserver variability for TPF classification. Fracture apex requiring fixation changed in 34% of cases between the radiographs and CT, whilst set-up and surgical approach changed in 27% and 28.5% of cases respectively. All surgeons agreed no CT was required in only 11 out of 50 cases. CONCLUSION. CT scanning in TPF significantly affects the classification, setup, approach and fixation technique when compared to radiographs alone and can justifiably be requested as part of pre-operative planning

Aims. The diagnosis of periprosthetic joint infection (PJI) continues to present a significant clinical challenge. New biomarkers have been proposed to support clinical decision-making; among them, synovial fluid alpha-defensin has gained interest. Current research methodology suggests reference methods are needed to establish solid evidence for use of the test. This prospective study aims to evaluate the diagnostic accuracy of high-performance liquid chromatography coupled with the mass spectrometry (LC-MS) method to detect alpha-defensin in synovial fluid. Methods. Between October 2017 and September 2019, we collected synovial fluid samples from patients scheduled to undergo revision surgery for painful total knee arthroplasty (TKA). The International Consensus Meeting criteria were used to classify 33 PJIs and 92 aseptic joints. LC-MS assay was performed to measure alpha-defensin in synovial fluid of all included patients. Sensitivity, specificity, positive predictive value, negative predictive value, and the area under the receiver operating characteristic curve (AUC) were calculated to define the test diagnostic accuracy. Results. The AUC was 0.99 (95% confidence interval (CI) 0.98 to 1.00). Receiver operating characteristic (ROC) analysis showed that the optimal cut-off value of synovial fluid alpha-defensin was 1.0 μg/l. The sensitivity of alpha-defensin was 100% (95% CI 96 to 100), the specificity was 97% (95% CI 90 to 98), the positive predictive value was 89.2% (95% CI 82 to 94), and negative predictive value was 100% (95% CI 96 to 100). ROC analysis demonstrated an AUC of 0.99 (95% CI 0.98 to 1.0). Conclusion. The present study confirms the utility of alpha-defensin in the synovial fluid in patients with painful TKA to select cases of PJI. Since LC-MS is still a time-consuming technology and is available in highly specialized laboratories, further translational research studies are needed to take this evidence into routine procedures and promote a new diagnostic approach. Cite this article: Bone Joint J 2022;104-B(9):1047–1051

Aims. A functional anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) has been assumed to be required for patients undergoing unicompartmental knee arthroplasty (UKA). However, this assumption has not been thoroughly tested. Therefore, this study aimed to assess the biomechanical effects exerted by cruciate ligament-deficient knees with medial UKAs regarding different posterior tibial slopes. Methods. ACL- or PCL-deficient models with posterior tibial slopes of 1°, 3°, 5°, 7°, and 9° were developed and compared to intact models. The kinematics and contact stresses on the tibiofemoral joint were evaluated under gait cycle loading conditions. Results. Anterior translation increased in ACL-deficient UKA cases compared with intact models. In contrast, posterior translation increased in PCL-deficient UKA cases compared with intact models. As the posterior tibial slope increased, anterior translation of ACL-deficient UKA increased significantly in the stance phase, and posterior translation of PCL-deficient UKA increased significantly in the swing phase. Furthermore, as the posterior tibial slope increased, contact stress on the other compartment increased in cruciate ligament-deficient UKAs compared with intact UKAs. Conclusion. Fixed-bearing medial UKA is a viable treatment option for patients with cruciate ligament deficiency, providing a less invasive procedure and allowing patient-specific kinematics to adjust posterior tibial slope. Patient selection is important, and while AP kinematics can be compensated for by posterior tibial slope adjustment, rotational stability is a prerequisite for this approach. ACL- or PCL-deficient UKA that adjusts the posterior tibial slope might be an alternative treatment option for a skilled surgeon. Cite this article: Bone Joint Res 2022;11(7):494–502

Aims. The aim of this study was to establish consensus statements on the diagnosis, nonoperative management, and indications, if any, for medial patellofemoral complex (MPFC) repair in patients with patellar instability, using the modified Delphi approach. Methods. A total of 60 surgeons from 11 countries were invited to develop consensus statements based on their expertise in this area. They were assigned to one of seven working groups defined by subtopics of interest within patellar instability. Consensus was defined as achieving between 80% and 89% agreement, strong consensus was defined as between 90% and 99% agreement, and 100% agreement was considered to be unanimous. Results. Of 27 questions and statements on patellar instability, three achieved unanimous consensus, 14 achieved strong consensus, five achieved consensus, and five did not achieve consensus. Conclusion. The statements that reached unanimous consensus were that an assessment of physeal status is critical for paediatric patients with patellar instability. There was also unanimous consensus on early mobilization and resistance training following nonoperative management once there is no apprehension. The statements that did not achieve consensus were on the importance of immobilization of the knee, the use of orthobiologics in nonoperative management, the indications for MPFC repair, and whether a vastus medialis oblique advancement should be performed. Cite this article: Bone Joint J 2023;105-B(12):1259–1264

Abstract. Introduction. There is a need to develop approaches to reduce chronic pain after total knee replacement. There is an established link between disturbed sleep and pain. We tested the feasibility of a trial evaluating the clinical and cost-effectiveness of a pre-operative sleep assessment and complex intervention package for improving long-term pain after TKR. Methodology. REST was a feasibility multi-centre randomised controlled trial with embedded qualitative study and health economics. Participants completed baseline measures and were randomised to usual care or the intervention, a tailored sleep assessment and behavioural intervention package delivered by an extended scope practitioner three months pre-operatively with a follow-up call up at four-weeks. Patient reported outcomes were assessed at baseline, one-week pre-surgery, and 3-months post-surgery. Results. 57 patients were randomised and 20 had surgery within the study timelines. All patients allocated the intervention attended an appointment and most engaged with treatment. The intervention group reported improvements in sleep (Sleep Conditions Indicator) and neuropathic pain (painDETECT) scores. Participants found the sleep treatments and study processes to be acceptable. The mean cost of the intervention was estimated at £134.45 per patient. Conclusion. The feasibility study has shown that patient recruitment is feasible, engagement with and adherence to the intervention is high, and the intervention is acceptable to patients and clinicians. Preliminary findings show that the intervention group had improved sleep quality and had reduced levels of pre-operative neuropathic pain. This study has demonstrated that a full RCT is feasible and identified areas for improvement to optimize the trial design

Abstract. Introduction. Total knee replacement (TKR) aims to reduce pain and functional limitations. Despite a good outcome for many, 15–20% patients report chronic pain three months after TKR. The STAR Care Pathway is a clinically important and cost effective treatment to improve pain outcomes over 1 year for people with chronic pain at 3 months after total knee replacement surgery. The care pathway is delivered by specially trained Extended Scope Practitioners (ESPs). There is a gap between research findings and translation into practice. This work shows how the STAR trial findings were implemented into NHS practice at a single centre and the further work required to enable national implementation. Methodology. Trial findings were presented to NHS managers with a business case for an implementation pilot. Trial documentation was adapted for use in usual care using the COM-B model for behaviour change and evidence-based approaches to increase the return of postal questionnaires. Trial sites were contacted to understand their capacity to implement the intervention locally. Results. The STAR care pathway was successfully implemented into NHS practice with a screening response rate of 83%. It is now permanently part of usual care at North Bristol NHS Trust. Trial centres indicated that lack of availability of STAR trained ESPs as a barrier to implementation. The trial manual and training session were adapted for online delivery in partnership with Health Education England. Conclusion. The STAR care pathway has been successfully embedded into NHS care. A toolkit and online clinician training package enables national implementation

Abstract. Introduction. Isolated patellofemoral joint(PFJ) osteoarthritis affects approximately 10% of patients aged over 40 years and treatment remains controversial. Our aim was to evaluate long term functional and radiological outcomes following PFJ arthorplasty with the Femoro Patella Vialli (FPV) prosthesis as this evidence is lacking in literature. Methodology. A retrospective review of prospectively collected PROMS in patients undergoing Patellofemoral arthroplasty. Single centre trial. Between 2004 and 2008, 101 FPV patellofemoral arthroplasties were performed in 80 patients with isolated patellofemoral joint osteoarthritis. Data was collected as a part of routine follow-up for up to 6 years and additional long term data was collected at 16 years. Results. At 6 year follow up the mean OKS was 29 and by 16 year follow up it was 26 which was not a statistically significant drop. 22 patients (29 knees) had died, 32 (32%) had been revised, 25 to total knee replacement using primary arthroplasty components. Mean OKS in the revised group was 27 which was not a statistically significant difference when compared to the unrevised group. Mean time to revision was 4 years. The cumulative survival analysis of the FPV implant was 76% at 5 years, 64% at 10 years. Conclusion. Our findings suggest the FPV patellofemoral prosthesis provides good pain relief and clinical outcomes however, the survivorship for this particular implant maybe lower as compared to the available literature. Patient reported outcomes are maintained over the implant life and are no worse once revised implying a staged approach to arthroplasty is reasonable

Abstract. Introduction. Challenges in surgical training have led to the exploration of technologies such as augmented reality (AR), which present novel approaches to teaching orthopaedic procedures to medical students. The aim of this double-blinded randomised-controlled trial was to compare the validity and training effect of AR to traditional teaching on medical students’ understanding of total knee arthroplasty (TKA). Methodology. Twenty medical students from 7 UK universities were randomised equally to either intervention or control groups. The control received a consultant-led teaching session and the intervention received training via Microsoft HoloLens, where surgeons were able to project virtual information over physical objects. Participants completed written knowledge and practical exams which were assessed by 2 orthopaedic consultants. Training superiority was established via 4 quantitative outcome measures: OSATS scores, a checklist of TKA-specific steps, procedural time, and written exam scores. Qualitative feedback was evaluated using a 5-point Likert scale. Results. AR training was superior in teaching basic technical proficiency and understanding of TKA, with the intervention group significantly outperforming the control group in 3 metrics [OSATS (38.6%, p=0.021), checklist (33%, p=0.011) and written exam (54.5%, p=0.001)]. Procedural time was equivalent between cohorts (p=0.082). AR was rated as significantly more enjoyable (p=0.044), realistic (p=0.003), easy to understand (p=0.040), and proficient in teaching (p=0.02). Conclusion. In this adequately powered, double-blinded randomised-controlled trial, AR training demonstrated substantially improved translational technical skills and knowledge needed to understand TKA over traditional learning in medical students. Additionally, the results showed face, content, and transfer validity for AR in surgical training

Aims. Distal femoral resection in conventional total knee arthroplasty (TKA) utilizes an intramedullary guide to determine coronal alignment, commonly planned for 5° of valgus. However, a standard 5° resection angle may contribute to malalignment in patients with variability in the femoral anatomical and mechanical axis angle. The purpose of the study was to leverage deep learning (DL) to measure the femoral mechanical-anatomical axis angle (FMAA) in a heterogeneous cohort. Methods. Patients with full-limb radiographs from the Osteoarthritis Initiative were included. A DL workflow was created to measure the FMAA and validated against human measurements. To reflect potential intramedullary guide placement during manual TKA, two different FMAAs were calculated either using a line approximating the entire diaphyseal shaft, and a line connecting the apex of the femoral intercondylar sulcus to the centre of the diaphysis. The proportion of FMAAs outside a range of 5.0° (SD 2.0°) was calculated for both definitions, and FMAA was compared using univariate analyses across sex, BMI, knee alignment, and femur length. Results. The algorithm measured 1,078 radiographs at a rate of 12.6 s/image (2,156 unique measurements in 3.8 hours). There was no significant difference or bias between reader and algorithm measurements for the FMAA (p = 0.130 to 0.563). The FMAA was 6.3° (SD 1.0°; 25% outside range of 5.0° (SD 2.0°)) using definition one and 4.6° (SD 1.3°; 13% outside range of 5.0° (SD 2.0°)) using definition two. Differences between males and females were observed using definition two (males more valgus; p < 0.001). Conclusion. We developed a rapid and accurate DL tool to quantify the FMAA. Considerable variation with different measurement approaches for the FMAA supports that patient-specific anatomy and surgeon-dependent technique must be accounted for when correcting for the FMAA using an intramedullary guide. The angle between the mechanical and anatomical axes of the femur fell outside the range of 5.0° (SD 2.0°) for nearly a quarter of patients. Cite this article: Bone Jt Open 2024;5(2):101–108

Aims. Single-stage revision total knee arthroplasty (rTKA) is gaining popularity in treating chronic periprosthetic joint infections (PJIs). We have introduced this approach to our clinical practice and sought to evaluate rates of reinfection and re-revision, along with predictors of failure of both single- and two-stage rTKA for chronic PJI. Methods. A retrospective comparative cohort study of all rTKAs for chronic PJI between 1 April 2003 and 31 December 2018 was undertaken using prospective databases. Patients with acute infections were excluded; rTKAs were classified as single-stage, stage 1, or stage 2 of two-stage revision. The primary outcome measure was failure to eradicate or recurrent infection. Variables evaluated for failure by regression analysis included age, BMI, American Society of Anesthesiologists grade, infecting organisms, and the presence of a sinus. Patient survivorship was also compared between the groups. Results. A total of 292 consecutive first-time rTKAs for chronic PJI were included: 82 single-stage (28.1%); and 210 two-stage (71.9%) revisions. The mean age was 71 years (27 to 90), with 165 females (57.4%), and a mean BMI of 30.9 kg/m. 2. (20 to 53). Significantly more patients with a known infecting organism were in the single-stage group (93.9% vs 80.47%; p = 0.004). The infecting organism was identified preoperatively in 246 cases (84.2%). At a mean follow-up of 6.3 years (2.0 to 17.6), the failure rate was 6.1% in the single-stage, and 12% in the two-stage groups. All failures occurred within four years of treatment. The presence of a sinus was an independent risk factor for failure (odds ratio (OR) 4.97; 95% confidence interval (CI) 1.593 to 15.505; p = 0.006), as well as age > 80 years (OR 5.962; 95% CI 1.156 to 30.73; p = 0.033). The ten-year patient survivorship rate was 72% in the single-stage group compared with 70.5% in the two-stage group. This difference was not significant (p = 0.517). Conclusion. Single-stage rTKA is an effective strategy with a high success rate comparable to two-stage approach in appropriately selected patients. Cite this article: Bone Joint J 2021;103-B(8):1373–1379