The psychology of rock climbing: A systematic review.

BACKGROUND: Psychology plays an important role in rock climbing performance and safety. Many studies have examined the psychology of rock climbing, a sport that has grown in popularity and status over the past few decades. OBJECTIVE: This systematic review aimed to summarize published research on the psychology of rock climbing, find commonalities and disagreements within the current research and illuminate future research areas. METHODS: A systematic literature search was conducted in three electronic databases (Scopus, PsycINFO and SPORTDiscus) in July 2023. Key search terms such as 'sport climbing' and 'psychology' were included and combined using the operators "AND", "OR". The search syntax initially identified 504 records. After screening abstracts and full texts, 83 studies examining the psychology of rock climbing remained. RESULTS: Studies were sorted by whether they measured climbing-specific or psychological variables. Climbers are conscientious, intrinsically motivated and task-oriented. Flow is brought on by novel, challenging climbing situations and increases enjoyment and performance. Climbing ability correlates with self-confidence, decision-making ability, tactile and spatial perception and anxiety facilitation. Better and more experienced climbers better manage risk with less psychophysiological effects. Weaknesses of the current body of literature and avenues for future research were highlighted. CONCLUSION: Findings from this review suggest rock climbers are a unique group of athletes who balance risk with performance in different environments. Flow, confidence, anxiety facilitation and perception all play key roles in climbing performance. The optimal levels and development of these and more psychological variables have yet to be clarified by existing literature.

Variability of three-dimensional knee morphology cannot be effectively assessed using a coronal plane knee alignment classification in total knee arthroplasty patients.

Purpose: Optimal reproduction of the native three-dimensional (3D) alignment in total knee arthroplasty (TKA) influences outcomes; however, much of the modern TKA alignment research, such as the coronal plane alignment of the knee (CPAK), focuses only on coronal alignment. Tibial, femoral and tibiofemoral measurements on the axial and sagittal planes were evaluated for their relationship to the arithmetic hip-knee-ankle angle (aHKA) and joint-line obliquity (JLO). These 3D anatomical measurements are also evaluated across CPAK groups. Methods: A retrospective analysis of the 360 Med Care computed tomography (CT) database was performed. Patient CT scans were segmented and landmarked. Linear regression analysis compared 12 axial and sagittal plane measurements (representing tibial, femoral and tibiofemoral rotation, tibial slope and femoral flexion) with both aHKA and JLO. Nonparametric tests assessed these anatomical measurements across the different CPAK groups, while Cohen's delta (d) determined the effect size. Results: With a sample size of 7450 osteoarthritic knees, significant but weak relationships (r < 0.30) were observed between all 12 anatomical measurements and both aHKA and JLO. Tibiofemoral rotations between Insall's axis and both the posterior condylar and the surgical transepicondylar axes demonstrated large effect sizes (d > 0.80). However, trivial to small effect sizes (d < 0.50) were broadly observed across the 12 axial and sagittal measurements, underscoring their limited clinical significance. Conclusions: While useful for describing coronal knee anatomy, CPAK phenotypes fail to differentiate tibial, femoral and tibiofemoral rotation, tibial slope or femoral flexion-crucial aspects of 3D surgical planning. Therefore, more comprehensive knee phenotyping solutions are required to guide individualised TKA alignment strategies. Level of Evidence: Level II.

Functional preoperative assessment of coronal knee laxity better predicts postoperative patient outcomes than intraoperative surgeon-defined laxity in total knee arthroplasty.

PURPOSE: Intraoperative laxity assessments in total knee arthroplasty (TKA) are subjective, with few studies comparing against standardised preoperative and postoperative assessments. This study compares coronal knee laxity in TKA patients awake and anaesthetised, preprosthesis and postprosthesis implantation, evaluating relationships to patient-reported outcome measures. METHODS: A retrospective analysis of 49 TKA joints included preoperative and postoperative computed tomography scans, stress radiographs and knee injury and osteoarthritis outcome score (KOOS) questionnaire results preoperatively and 12 months postoperatively. The imaging was used to assess functional laxity (FL) in awake patients, whereas computer navigation measured intraoperative surgical laxity (SL) preimplantation and postimplantation, with patients anaesthetised. Varus and valgus stress states and their difference, joint laxity, were measured. RESULTS: SL was greater than FL in both preimplantation [8.1° (interquartile range, IQR 2.0°) and 3.8° (IQR 2.9°), respectively] and postimplantation [3.5° (IQR 2.3°) and 2.5° (IQR 2.7°), respectively]. Preimplantation, SL was more likely than FL to categorise knees as correctable to ±3° of the mechanical axis. Preoperative FL correlated with KOOS Symptoms (r = 0.33, p = .02) and quality of life (QOL) (r = 0.38, p = .01), whereas reducing medial laxity with TKA enhanced postoperative QOL outcomes (p = .02). CONCLUSIONS: Functional coronal knee laxity assessment of awake patients is generally lower than intraoperative surgical assessments of anaesthetised patients. Preoperative SL may result in overcorrection of coronal TKA alignment, whereas preoperative FL better predicts postoperative patient outcomes and reflects the patients' native and tolerable knee laxity. Preoperative FL assessment can be used to guide surgical planning. LEVEL OF EVIDENCE: Level II.

Determination of preoperative risk factors for iliopsoas tendonitis after total hip arthroplasty: A simulation study.

This study aims to identify preoperative risk factors for iliopsoas tendonitis after total hip arthroplasty, a complication typically attributed to acetabular cup position and orientation, using a validated iliopsoas impingement detection simulation. Analyzing CT scans and X-rays of 448 patients using a validated preoperative planning protocol, patients were simulated for iliopsoas impingement and categorized into at-risk and not at-risk groups based on a prior validation study, with a 23% at-risk incidence. Implementing a propensity score matching algorithm to reduce covariate imbalance, we identified factors that may exacerbate risk of iliopsoas tendonitis. Parameters that were investigated included standing pelvic tilt, functional femoral rotation, and the difference between the planned acetabular cup diameter and native femoral head diameter (ΔC-NFH). Comparing pelvic tilt, we found a significant difference between the groups (at-risk: -6.0°, not at-risk: -0.7°; p << 0.01). A similar trend was noted for ΔC-NFH (at-risk: +5.7 mm, not at-risk: +5.1 mm; p = 0.01). Additional simulations of at-risk patients indicated increased anteversion of the acetabular cup reduces impingement risk more effectively than medialisation. These findings suggest that spinopelvic parameters may exacerbate iliopsoas irritation risk, underscoring their importance in preoperative planning and patient expectation management. Similar findings of a greater than 6 mm difference between cup size and native femoral head diameter being a significant risk for iliopsoas tendonitis have been observed before, underscoring its potential veracity. These results may provide surgeons with a simple threshold that can be used in determining a cup size to reduce the risk of iliopsoas tendonitis.

Comparison of iliopsoas tendonitis after hip resurfacing arthroplasty and total hip arthroplasty: A case-controlled investigation using a validated simulation.

Iliopsoas tendonitis, typically caused by impingement with the acetabular cup, occurs in up to 18% of patients after total hip arthroplasty (THA) and up to 30% of patients after hip resurfacing arthroplasty (HRA). We have developed a simulation for detecting iliopsoas impingement and validated it in a previous study of THA patients. However, due to the difference in incidence between HRA and THA, this study had two aims. First, to validate the simulation in a cohort of HRA patients and, second, to comparethe results of the HRA and THA patients to understand any differences in their etiology. We conducted a retrospective search in an experienced surgeon's database for HRA patients with iliopsoas tendonitisand control patients without iliopsoas tendonitis, resulting in two cohorts of 12 patients. Using CT scans, 3D models of the each patient's prosthetic and bony anatomy were generated, landmarked, and simulated. Regarding validation of the simulation for HRA patients, impingement significantly predicted the probability of iliopsoas tendonitis in logistic regression models and the simulation had a sensitivity of 83%, specificity of 100%, and an AUC ROC curve of 0.95. Unexpectedly, the HRA cohort exhibited less impingement than the THA cohort. Our novel simulation has now been demonstrated to detect iliopsoas impingement and differentiate between the symptomatic and asymptomatic cohorts in investigations of THA and HRA patients. This tool has the potential to be used preoperatively, to guide decisions about optimal cup placement, and postoperatively, to assist in the diagnosis of iliopsoas tendonitis.

Preoperative Joint Distraction Imaging and Planning Protocol for Total Knee Arthroplasty.

BACKGROUND: Current preoperative total knee arthroplasty (TKA) planning strategies are bone-referencing and do not consider the ligamentous profile of the knee. This study assessed the mean Hip-Knee-Ankle (HKA) angle of the planned Distracted Alignment (DA), an alignment output using a joint distraction radiology and planning protocol, which incorporates preoperative evaluation of ligament laxity. METHODS: A retrospective study of 144 knees undergoing TKA was performed. Each patient received a preoperative computer tomograph scan, a weight-bearing antero-posterior knee radiograph, and distracted knee radiographs in extension and flexion. The imaging was used to develop a preoperative DA plan aiming for medio-lateral and extension-flexion space balance. The mean DA, weight-bearing, and arithmetic HKA angles were compared to each other, and to the HKA of a healthy nonarthritic population. RESULTS: The mean weight-bearing, arithmetic, and planned DA HKA angles were 4.8° (interquartile range [IQR] 6.5°) varus, 0.4° (IQR 4.5°) varus, and 2.2° (IQR 4.0°) varus, respectively. This compares to a healthy adult HKA angle of 1.3° varus. The difference between the planned DA and arithmetic HKA angles was greater than 3° for 36% of the patients in the study population. CONCLUSIONS: The planned DA HKA angle was fundamentally different from the arithmetic HKA angle, but comparable to a healthy population. Considering both hard and soft tissue information of the knee, we believe the planned DA resulting from the joint distraction radiology protocol allows for optimized preoperative surgical planning in TKA. This protocol has been shown to be clinically viable.

Iliopsoas tendonitis after total hip arthroplasty : an improved detection method with applications to preoperative planning.

AIMS: Iliopsoas impingement occurs in 4% to 30% of patients after undergoing total hip arthroplasty (THA). Despite a relatively high incidence, there are few attempts at modelling impingement between the iliopsoas and acetabular component, and no attempts at modelling this in a representative cohort of subjects. The purpose of this study was to develop a novel computational model for quantifying the impingement between the iliopsoas and acetabular component and validate its utility in a case-controlled investigation. METHODS: This was a retrospective cohort study of patients who underwent THA surgery that included 23 symptomatic patients diagnosed with iliopsoas tendonitis, and 23 patients not diagnosed with iliopsoas tendonitis. All patients received postoperative CT imaging, postoperative standing radiography, and had minimum six months' follow-up. 3D models of each patient's prosthetic and bony anatomy were generated, landmarked, and simulated in a novel iliopsoas impingement detection model in supine and standing pelvic positions. Logistic regression models were implemented to determine if the probability of pain could be significantly predicted. Receiver operating characteristic curves were generated to determine the model's sensitivity, specificity, and area under the curve (AUC). RESULTS: Highly significant differences between the symptomatic and asymptomatic cohorts were observed for iliopsoas impingement. Logistic regression models determined that the impingement values significantly predicted the probability of groin pain. The simulation had a sensitivity of 74%, specificity of 100%, and an AUC of 0.86. CONCLUSION: We developed a computational model that can quantify iliopsoas impingement and verified its accuracy in a case-controlled investigation. This tool has the potential to be used preoperatively, to guide decisions about optimal cup placement, and postoperatively, to assist in the diagnosis of iliopsoas tendonitis.Cite this article: Bone Jt Open 2023;4(1):3-12.

Patient-reported impairment following TKA is reduced when a computationally simulated predicted ideal alignment is achieved.

PURPOSE: Joint dynamics following Total Knee Arthroplasty (TKA) may influence patient-reported outcome. Simulations allow many knee alignment approaches to a single patient to be considered prior to surgery. The simulated kinematics can be matched to patient-reported outcome to predict kinematic patterns most likely to give the best outcome. This study aims to validate one such previously developed algorithm based on a simulated deep knee bend (the Dynamic Knee Score, DKS). METHODS: 1074 TKA patients with pre- and post-operative Computerised Tomography (CT) scans and 12-month post-operative Knee Injury and Osteoarthritis Outcomes (KOOS) Scores were identified from the 360 Med Care Joint Registry. Landmarking and registration of implant position was performed on all CT scans, and each of the achieved TKAs was computationally simulated and received a predictive outcome score from the DKS. In addition, a set of potential alternative surgical plans which might have been followed were simulated. Comparison of patient-reported issues and DKS score was evaluated in a counter-factual study design. RESULTS: Patient-reported impairment with the knee catching and squatting was shown to be 30% lower (p = 0.005) and 22% lower (p = 0.026) in patients where the best possible DKS result was the one surgically achieved. Similar findings were found relating attainment of the best tibial slope and posterior femoral resection DKS plans to patient-reported difficulty straightening the knee (40% less likely, p < 0.001) and descending stairs (35% less likely, p = 0.006). CONCLUSION: The DKS has been shown to correlate with presence of patient-reported impairments post-TKA and the resultant algorithm can be applied in a pre-operative planning setting. Outcome optimization in the future may come from patient-specific selection of an alignment strategy and simulations may be a technological enabler of this trend. LEVEL OF EVIDENCE: III (Retrospective Cohort Study).

Comparative effectiveness of standard vs. AI-assisted PET/CT reading workflow for pre-treatment lymphoma staging: a multi-institutional reader study evaluation.

Background: Fluorine-18 fluorodeoxyglucose (FDG)-positron emission tomography/computed tomography (PET/CT) is widely used for staging high-grade lymphoma, with the time to evaluate such studies varying depending on the complexity of the case. Integrating artificial intelligence (AI) within the reporting workflow has the potential to improve quality and efficiency. The aims of the present study were to evaluate the influence of an integrated research prototype segmentation tool implemented within diagnostic PET/CT reading software on the speed and quality of reporting with variable levels of experience, and to assess the effect of the AI-assisted workflow on reader confidence and whether this tool influenced reporting behaviour. Methods: Nine blinded reporters (three trainees, three junior consultants and three senior consultants) from three UK centres participated in a two-part reader study. A total of 15 lymphoma staging PET/CT scans were evaluated twice: first, using a standard PET/CT reporting workflow; then, after a 6-week gap, with AI assistance incorporating pre-segmentation of disease sites within the reading software. An even split of PET/CT segmentations with gold standard (GS), false-positive (FP) over-contour or false-negative (FN) under-contour were provided. The read duration was calculated using file logs, while the report quality was independently assessed by two radiologists with >15 years of experience. Confidence in AI assistance and identification of disease was assessed via online questionnaires for each case. Results: There was a significant decrease in time between non-AI and AI-assisted reads (median 15.0 vs. 13.3 min, p < 0.001). Sub-analysis confirmed this was true for both junior (14.5 vs. 12.7 min, p = 0.03) and senior consultants (15.1 vs. 12.2 min, p = 0.03) but not for trainees (18.1 vs. 18.0 min, p = 0.2). There was no significant difference between report quality between reads. AI assistance provided a significant increase in confidence of disease identification (p < 0.001). This held true when splitting the data into FN, GS and FP. In 19/88 cases, participants did not identify either FP (31.8%) or FN (11.4%) segmentations. This was significantly greater for trainees (13/30, 43.3%) than for junior (3/28, 10.7%, p = 0.05) and senior consultants (3/30, 10.0%, p = 0.05). Conclusions: The study findings indicate that an AI-assisted workflow achieves comparable performance to humans, demonstrating a marginal enhancement in reporting speed. Less experienced readers were more influenced by segmentation errors. An AI-assisted PET/CT reading workflow has the potential to increase reporting efficiency without adversely affecting quality, which could reduce costs and report turnaround times. These preliminary findings need to be confirmed in larger studies.

Leg length discrepancy assessment in total hip arthroplasty: is a pelvic radiograph sufficient?

AIMS: Leg length discrepancy (LLD) is a common pre- and postoperative issue in total hip arthroplasty (THA) patients. The conventional technique for measuring LLD has historically been on a non-weightbearing anteroposterior pelvic radiograph; however, this does not capture many potential sources of LLD. The aim of this study was to determine if long-limb EOS radiology can provide a more reproducible and holistic measurement of LLD. METHODS: In all, 93 patients who underwent a THA received a standardized preoperative EOS scan, anteroposterior (AP) radiograph, and clinical LLD assessment. Overall, 13 measurements were taken along both anatomical and functional axes and measured twice by an orthopaedic fellow and surgical planning engineer to calculate intraoperator reproducibility and correlations between measurements. RESULTS: Strong correlations were observed for all EOS measurements (rs > 0.9). The strongest correlation with AP radiograph (inter-teardrop line) was observed for functional-ASIS-to-floor (functional) (rs = 0.57), much weaker than the correlations between EOS measurements. ASIS-to-ankle measurements exhibited a high correlation to other linear measurements and the highest ICC (rs = 0.97). Using anterior superior iliac spine (ASIS)-to-ankle, 33% of patients had an absolute LLD of greater than 10 mm, which was statistically different from the inter-teardrop LLD measurement (p < 0.005). DISCUSSION: We found that the conventional measurement of LLD on AP pelvic radiograph does not correlate well with long leg measurements and may not provide a true appreciation of LLD. ASIS-to-ankle demonstrated improved detection of potential LLD than other EOS and radiograph measurements. Full length, functional imaging methods may become the new gold standard to measure LLD.Cite this article: Bone Jt Open 2022;3(12):960-968.

Functional Femoral Anteversion: Axial Rotation of the Femur and its Implications for Stem Version Targets in Total Hip Arthroplasty.

Background: Acetabular and femoral component positioning are important considerations in reducing adverse outcomes after total hip arthroplasty (THA). Previous assessments of femoral anteversion examined anatomic femoral anteversion (AFA) referenced to anatomic landmarks. However, this does not provide a functional understanding of the femur's relationship to the hip. We investigate a new measurement, functional femoral anteversion (FFA), and sought to measure its variability across a large sample of patients undergoing THA. Methods: A total of 1008 consecutive patients underwent THA surgery between September 2019 and July 2021. All patients were measured for supine and standing functional femoral rotation (FFR), AFA, and FFA. Results: The mean standing FFA was 13.2° ± 12.2° (-27.8° to 52.3°). The mean change in FFR from supine to standing was -2.2° ± 11.8° (-43.0° to 41.9°). Of all, 161 (16%) patients had standing FFA version greater than 25°. Four hundred sixty (46%) patients had standing FFR (internal or external) greater than 10°. One hundred twenty-three (12%) patients exhibited an increase in external rotation from supine to standing of greater than 10°. A moderate, negative linear relationship was observed between AFA and standing external femoral rotation (P <<.001, R = -0.46), indicating people may externally rotate their femur as AFA decreases with age. Conclusions: Functional alignment of the femur in patients requiring THA is understudied. It is now understood that the femur, like the pelvis, can rotate substantially between functional positions. Enhancing our understanding of FFA and FFR may improve both acetabular and femoral component positioning.

Pre- and postoperative physiotherapy using a digital application decreases length of stay without reducing patient outcomes following total knee arthroplasty.

INTRODUCTION: Total Knee Arthroplasty (TKA) for both patients and the surgical team is a journey spanning many months, rather than purely a hospital episode of care. To improve patient outcomes and reduce costs in TKA, greater emphasis should be placed on the pre- and postoperative periods as, historically, innovation has focused on the intraoperative execution of the surgery. The purpose of this study was to determine if a pre- and postoperative physiotherapy program delivered via a digital application could reduce hospital length of stay (LOS) without compromising patient outcomes. METHODS: A retrospective series of 294 patients who underwent TKA from a single-surgeon in a single-centre was examined. This included 232 patients who underwent a pre- and postoperative physiotherapist-led program delivered via a digital application and 62 patients who underwent a conventional pre- and postoperative protocol. 2:1 nearest neighbour propensity score matching was performed to establish covariate balance between the cohorts. Data collected included pre- and postoperative Knee Injury and Osteoarthritis Outcome Score (KOOS), KOOS for Joint Replacement (KOOS, JR), and acute, rehabilitation, and total LOS. RESULTS: No significant difference in KOOS or KOOS, JR scores was observed at 12-month follow-up. A significantly reduced rehabilitation (P = 0.014) and total LOS (P = 0.015) was observed in the patients who received the digital physiotherapy program. CONCLUSIONS: There may be significant economic benefits to a pre- and postoperative physiotherapy program delivered via a digital application. Our results suggest that a digital physiotherapist-led patient program may reduce the need for inpatient rehabilitation services without compromising patient outcomes.

Correctability of the knee joint observed under a stressed state.

BACKGROUND: Well-balanced postoperative knee joints are often based on subjective 'feel' of experienced surgeons rather than quantifiable references. Most alignment strategies continue to reference the bone despite the complexity in anatomical variations and presence of deformity. Categorical prescription of a singular alignment philosophy for all patients may not be appropriate. This study aims to characterize coronal alignment correctability in relation to anatomical measures to develop a mechanism for distinguishing patients for whom repeatable strategies are optimal in the form of alternative alignment techniques or advanced soft tissue balancing. METHODS: A consecutive series of 103 pre-operative knees who underwent primary total knee arthroplasty (TKA) were analysed. Pre-operative supine computer tomography (CT) scans were segmented, with output STL bone models placed against several stressed positions determined by the TELOS SD-900 (METAX, Germany) device. Anatomical analysis using two-dimensional (2D) -3D image registration was performed. Statistical analysis was conducted for variations in anatomical morphology and regression modelling was used to determine the relationship between these measurements and correctability of a patient. RESULTS: The mean preoperative supine hip-knee-ankle (HKA) angle was 5.1° and 2.3°, lateral distal femoral angle (LDFA) was 2.0° and 3.1°, medial proximal tibial angle (MPTA) was 3.7° and 3.0° varus for male and female, respectively. The mean laxity range was 4.3°. We found 36% of valgus patients and 55% of mild varus patients to be correctable. Supine HKA was a statistically significant predictor for correctability (P < 0.001). A statistically significant correlation between laxity and the HKA (P = 0.01) as well as LDFA angles (P = 0.01) exist for the mild varus cohort. CONCLUSION: Relationship between HKA angle and the correctability of the knee joint to neutral in patients presenting with mild to moderate varus cannot be consistently predicted using bony anatomy. If there is a desire to avoid ligament release during TKA, careful consideration of both a patient's bony anatomy and soft tissue laxity envelope must be made prior to surgery.

Can TKA outcomes be predicted with computational simulation? Generation of a patient specific planning tool.

BACKGROUND: Computer simulations of knee movement allow Total Knee Arthroplasty (TKA) dynamic outcomes to be studied. This study aims to build a model predicting patient reported outcome from a simulation of post-operative TKA joint dynamics. METHODS: Landmark localisation was performed on 239 segmented pre-operative computerized tomography (CT) scans to capture patient specific soft tissue attachments. The pre-operative bones and 3D implant files were registered to post-operative CT scans following TKA. Each post-operative knee was simulated undergoing a deep knee bend with assumed ligament balancing of the extension space. The kinematic results from this simulation were used in a Multivariate Adaptive Regression Spline algorithm, predicting attainment of a Patient Acceptable Symptom State (PASS) score in captured 12 month post-operative Knee Injury and Osteoarthritis Outcome Scores (KOOS). An independent series of 250 patients was evaluated by the predictive model to assess how the predictive model behaved in a pre-operative planning context. RESULTS: The generated predictive algorithm, called the Dynamic Knee Score (DKS) contained features, in order of significance, related to tibio-femoral force, patello-femoral motion and tibio-femoral motion. Area Under the Curve for predicting attainment of the PASS KOOS Score was 0.64. The predictive model produced a bimodal spread of predictions, reflecting a tendency to either strongly prefer one alignment plan over another or be ambivalent. CONCLUSION: A predictive algorithm relating patient reported outcome to the outputs of a computational simulation of a deep knee bend has been derived (the DKS). Simulation outcomes related to tibio-femoral balance had the highest correlation with patient reported outcome.

Correlation of tibial component size and rotation with outcomes after total knee arthroplasty.

INTRODUCTION: Tibial component design and positioning contribute more to patient satisfaction than previously realized. A surgeon needs to decide on the size and rotation, bearing in mind that coverage should be as high as possible, whilst malrotation and overhang should be avoided. No study investigates the impact of each of these components on clinical outcomes in a single cohort. MATERIALS AND METHODS: This is a retrospective analysis of 1-year postoperative outcomes measured with the Knee Injury and Osteoarthritis Outcome (KOOS) Score, as well as a previously validated rotational CT protocol. Coverage, rotation from Insall's axis, and overhang of an asymmetric tibial baseplate were measured, and positive and negative correlations to clinical outcomes were calculated. RESULTS: A total of 499 knees were analyzed. Patient average age was 68.4 years. Rotation within 7° internal and 5° external from Insall's axis was a "safe zone". Mean coverage was 76%. A total of 429 knees (94%) had a coverage of at least 70% and 102 knees (22%) greater than 80%. Overhang was detected in 23% of the cohort. Increased coverage was correlated to increased KOOS score and overhang correlated with a decreased KOOS score (p = 0.008). CONCLUSIONS: This study demonstrates the individual role of three aspects of tibial component implantation properties in postoperative pain and short-term functional outcomes. Upsizing to the point of overhang with rotational tolerance of 7° internal and 3° external to Insall's axis demonstrates best patient reported outcomes. Overhang decreases the clinical outcome by the same margin as loss of 16% of coverage.

Clinical and Statistical Validation of a Probabilistic Prediction Tool of Total Knee Arthroplasty Outcome.

BACKGROUND: Predicting patients at risk of a poor outcome would be useful in patient selection for total knee arthroplasty (TKA). Existing models to predict outcome have seen limited functional implementation. This study aims to validate a model and shared decision-making tool for both clinical utility and predictive accuracy. METHODS: A Bayesian belief network statistical model was developed using data from the Osteoarthritis Initiative. A consecutive series of consultations for osteoarthritis before and after introduction of the tool was used to evaluate the clinical impact of the tool. A data audit of postoperative outcomes of TKA patients exposed to the tool was used to evaluate the accuracy of predictions. RESULTS: The tool changed consultation outcomes and identified patients at risk of limited improvement. After introduction of the tool, patients booked for surgery reported worse Knee Osteoarthritis and Injury Outcome Score pain scores (difference, 15.2; P < .001) than those not booked, with no significant difference prior. There was a 27% chance of not improving if predicted at risk, and a 1.4% chance if predicted to improve. This gives a risk ratio of 19× (P < .001) for patients not improving if predicted at risk. CONCLUSION: For a prediction tool to be clinically useful, it needs to provide a better understanding of the likely clinical outcome of an intervention than existed without its use when the clinical decisions are made. The tool presented here has the potential to direct patients to surgical or nonsurgical pathways on a patient-specific basis, ensuring patients who will benefit most from TKA surgery are selected.

Accurate determination of post-operative 3D component positioning in total knee arthroplasty: the AURORA protocol.

BACKGROUND: Successful component alignment is a major metric of success in total knee arthroplasty. Component translational placement, however, is less well reported despite being shown to affect patient outcomes. CT scans and planar X-rays are routinely used to report alignment but do not report measurements as precisely or accurately as modern navigation systems can deliver, or with reference to the pre-operative anatomy. METHODS: A method is presented here that utilises a CT scan obtained for pre-operative planning and a post-operative CT scan for analysis to recreate a computation model of the knee with patient-specific axes. This model is then used to determine the post-operative component position in 3D space. RESULTS: Two subjects were investigated for reproducibility producing 12 sets of results. The maximum error using this technique was 0.9° ± 0.6° in rotation and 0.5 mm ± 0.3 mm in translation. Eleven subjects were investigated for reliability producing 22 sets of results. The intra-class correlation coefficient for each of the three axes of rotation and three primary resection planes was > 0.93 indicating excellent reliability. CONCLUSIONS: Routine use of this analysis will allow surgeons and engineers to better understand the effect of component alignment as well as the placement on outcome.

Patient-Specific Simulated Dynamics After Total Knee Arthroplasty Correlate With Patient-Reported Outcomes.

BACKGROUND: Component alignment variation following total knee arthroplasty (TKA) does not fully explain the instance of long-term postoperative pain. Joint dynamics following TKA vary with component alignment and patient-specific musculoskeletal anatomy. Computational simulations allow joint dynamics outcomes to be studied across populations. This study aims to determine if simulated postoperative TKA joint dynamics correlate with patient-reported outcomes. METHODS: Landmarking and 3D registration of implants was performed on 96 segmented postoperative computed tomography scans of TKAs. A cadaver rig-validated platform for generating patient-specific simulation of deep knee bend kinematics was run for each patient. Resultant dynamic outcomes were correlated with a 12-month postoperative Knee Injury and Osteoarthritis Outcome Score (KOOS). A Classification and Regression Tree (CART) was used for determining nonlinear relationships. RESULTS: Nonlinear relationships between the KOOS pain score and rollback and dynamic coronal alignment were found to be significant. Combining a dynamic coronal angular change from extension to full flexion between 0° and 4° varus (long leg axis) and measured rollback of no more than 6 mm without rollforward formed a "kinematic safe zone" of outcomes in which the postoperative KOOS score is 10.5 points higher (P = .013). CONCLUSION: The study showed statistically significant correlations between kinematic factors in a simulation of postoperative TKA and postoperative KOOS scores. The presence of a dynamic safe zone in the data suggests a potential optimal target for any given individual patient's joint dynamics and the opportunity to preoperatively determine a patient-specific alignment target to achieve those joint dynamics.

The effect of seated pelvic tilt on posterior edge-loading in total hip arthroplasty: A finite element investigation.

Edge-loading of a ceramic-on-ceramic total hip replacement can lead to reproducible squeaking and revision. A patient's functional acetabular cup orientation, driven by their pelvic tilt, has been shown to be a significant factor in squeaking during hip flexion. The aim of this study was to investigate the effect of seated pelvic tilt on the contact mechanics at the ceramic bearing surface. A finite element model of a ceramic-on-ceramic total hip replacement was created. The cup was orientated at 40° inclination and 15° anteversion relative to the anterior pelvic plane. The stem was flexed 90° to replicate sitting in a chair. The model was loaded using data from in vivo measurements taken during a sit-to-stand activity. The pelvis was modelled in seven different sagittal positions, ranging from -30° to 30° of pelvic tilt, where a positive value denotes anterior pelvic tilt. Three different head sizes were investigated: 32, 36 and 40 mm. The maximum contact pressure and contact patch to rim distance were determined for each of the 21 simulations. Edge-loading (contact patch to rim distance < 0 mm) occurred with all head sizes when seated pelvic tilt was ≥10° and induced a large increase in contact pressure on the liner, with a maximum pressure exceeding 500 MPa. Edge-loading initiated at seated pelvic tilts of 7°, 9° and 5° for the 32, 36 and 40 mm heads, respectively. Patients with anterior pelvic tilts in the seated position are susceptible to posterior edge-loading. As the position of the pelvis when seated is patient specific, cup orientation should be adjusted on an individual basis to minimise edge-loading.

Measurement of physical activity in the pre- and early post-operative period after total knee arthroplasty for Osteoarthritis using a Fitbit Flex device.

Total knee arthroplasty (TKA) is a standard treatment for patients with end stage knee Osteoarthritis (OA) to reduce pain and restore function. The aim of this study was to assess pre- and early post-operative physical activity (PA) with Fitbit Flex devices for patients with OA undergoing TKA and determine any benchmarks for expected post-operative activity. Significant correlations of pre-operative step count, post-operative step count, Body Mass Index (BMI) and Short Form 12 Physical Component Summaries (SF-12 PCS) were found. Mean step counts varied by 3,203 steps per day between obese and healthy weight patients, and 3,786 steps per day between those with higher and lower SF-12 PCS scores, suggesting the need for benchmarks for recovery that vary by patient pre-operative factors. A backwards stepwise regression model developed to provide patient specific step count predictions at 6 weeks had an R2 of 0.754, providing a robust patient specific benchmark for post-operative recovery, while population means from BMI and SF-12 subgroups provide a clinically practical alternative.