Are Kinematics an Indicator of Outcome After Total Knee Arthroplasty?

BACKGROUND: A proportion of total knee arthroplasty (TKA) patients are dissatisfied postoperatively, particularly with their ability to perform higher-demand activities including deep-kneeling and step-up where kinematic parameters are more demanding. The purpose of this study was to examine the relationship between knee kinematics of step-up and deep-kneeling and patient-reported outcome measures following TKA. METHODS: Sixty-four patients were included at minimum 1-year follow-up. Participants performed a step-up and deep-kneeling task which was imaged via single-plane fluoroscopy. 3-dimensional prosthesis computer-aided design models were registered to the fluoroscopy, yielding in-vivo kinematic data. Associations between kinematics and patient-reported outcome measures, including Oxford Knee Score, American Knee Society Score, surgical satisfaction, and pain were assessed using log-transformed step-wise linear regressions. RESULTS: A higher total Oxford Knee Score was associated with more external rotation and more adduction at maximal flexion during kneeling and more external rotation and minimum flexion during step-up. Improved American Knee Society Score was associated with increased internal-external rotation during step-up. Improved surgical satisfaction was associated with greater maximum flexion and more external rotation at maximal flexion during deep-kneeling and more femoral internal rotation at terminal extension during step-up. An improved pain score was associated with greater maximum flexion and more femoral external rotation during deep-kneeling, as well as greater internal femoral rotation during step-up. CONCLUSION: The ability to move through full flexion/extension range and end-of-range rotation is important kinematic parameters that influence patient-reported outcome measures. Implant designs and postoperative rehabilitation should continue to focus on achieving these kinematic targets for enhanced outcomes after TKA.

The use of intra-articular vancomycin is safe in primary hip and knee arthroplasty.

Background: The use of a single dose of intra-articular antibiotic (IAA) has been reported in reducing the rate of prosthetic joint injection after total hip and knee arthroplasty. We examine the safety of IAA in primary hip and knee replacement surgery and the blood levels and joint fluid levels of vancomycin utilising this technique. Methods: From August to October 2021, 68 patients undergoing primary total joint arthroplasty (THA & TKA) were given 1g vancomycin intra-articularly (IA)after closure of the fascia. All patients received 2g cefazolin intravenously (IV) 30 min prior to the procedure as is our standard prophylaxis, and 21 of the patients (IA + IV) were also administered an additional 1 gm vancomycin IV. Post-operative blood vancomycin, creatinine land eGFR level monitoring was performed d1 and d3. To determine the post-operative intra-articular vancomycin levels, surgical drain fluid was sampled at day 1 and 2, in 10 patients. Results: All patients had serum vancomycin levels measured on day 1 and 3. In the group where vancomycin was injected after fascial closure, the average blood vancomycin level day 1 was 5.2 µg/ml (range 2.0-10.9) and day 3 was <1.4 µg/ml. The average pre-op creatinine levels were 69.4 µmol/L (56.1-82.6) compared to 70.2 µmol/L (57.0-83.4) on day 1 and 66.1 µmol/L (52.6-79.6) on day 3, (p = 0.663). The average pre-op eGFR levels (ml/min/1.73 m2) were 82.2 (76.0-88.3) compared to 81.7 (75.6-87.8) on day 1 and 83.0 (76.8-89.2) on day 3 (p = 0.736). Samples of joint fluid aspirated from surgical drains on day 1 and day 2 showed average vancomycin levels of 224 µg/ml and 51 µg/ml respectively, significantly higher than the MIC for Staph aureus. Conclusions: The use of intra-articular vancomycin is safe in primary TJA, with no renal damage and delivers levels within the joint which are highly therapeutic for at least 48 h post injection.

Evidence for key individual characteristics associated with outcomes following combined first-line interventions for knee osteoarthritis: A systematic review.

OBJECTIVE: To identify individual characteristics associated with outcomes following combined first-line interventions for knee osteoarthritis. METHODS: MEDLINE, CINAHL, Scopus, Web of Science Core Collection and the Cochrane library were searched. Studies were included if they reported an association between baseline factors and change in pain or function following combined exercise therapy, osteoarthritis education, or weight management interventions for knee osteoarthritis. Risk of bias was assessed using Quality in Prognostic Factor Studies. Data was visualised and a narrative synthesis was conducted for key factors (age, sex, BMI, comorbidity, depression, and imaging severity). RESULTS: 32 studies were included. Being female compared to male was associated with 2-3 times the odds of a positive response. Older age was associated with reduced odds of a positive response. The effect size (less than 10% reduction) is unlikely to be clinically relevant. It was difficult to conclude whether BMI, comorbidity, depression and imaging severity were associated with pain and function outcomes following a combined first-line intervention for knee osteoarthritis. Low to very low certainty evidence was found for sex, BMI, depression, comorbidity and imaging severity and moderate certainty evidence for age. Varying study methods contributed to some difficulty in drawing clear conclusions. CONCLUSIONS: This systematic review found no clear evidence to suggest factors such as age, sex, BMI, OA severity and presence of depression or comorbidities are associated with the response to first-line interventions for knee OA. Current evidence indicates that some groups of people may respond equally to first-line interventions, such as those with or without comorbidities. First-line interventions consisting of exercise therapy, education, and weight loss for people with knee OA should be recommended irrespective of sex, age, obesity, comorbidity, depression and imaging findings.

Statistical shape modelling reveals differences in hamstring morphology between professional rugby players and sprinters.

Hamstring morphology may play an important role in understanding the aetiology of hamstring injury. Currently, the methods available to capture detailed morphological data such as muscle shape have not been utilized for the hamstring muscles. The aim of this study was to examine the utility of statistical shape modelling (SSM) for describing and comparing hamstring muscle shape in rugby and sprinting athletes. Magnetic resonance images of both thighs of nine elite male rugby players and nine track and field sprinters were analysed. Images were converted to three-dimensional models enabling generation of four statistical shape models. Principal components describing the shape variation in the cohort were derived and evaluated. Six principal components were sufficient to discriminate differences in the shape of the hamstring muscles of rugby and sprinting athletes with 89% classification accuracy. Distinct shape features distinguishing rugby players from sprinters included size, curvature and axial torsion. These data demonstrate that SSM is useful for understanding hamstring muscle shape and that meaningful variation can be identified within a small sample. This method can be used in future research to enhance the anatomical specificity of musculoskeletal modelling and to understand the relationship between hamstring shape and injury.

Shape modelling of the oropharynx distinguishes associations with body morphology but not whiplash-associated disorder.

Characterization of the oropharynx, a subdivision of the pharynx between the soft palate and the epiglottis, is limited to simple measurements. Structural changes in the oropharynx in whiplash-associated disorder (WAD) cohorts have been quantified using two-dimensional (2D) and three-dimensional (3D) measures but the results are inconsistent. Statistical shape modelling (SSM) may be a more useful tool for systematically comparing morphometric features between cohorts. This technique has been used to quantify the variability in boney and soft tissue structures, but has not been used to examine a hollow cavity such as the oropharynx. The primary aim of this project was to examine the utility of SSM for comparing the oropharynx between WAD cohorts and control; and WAD severity cohorts. The secondary aim was to determine whether shape is associated with sex, height, weight and neck length. Magnetic resonance (MR) T1-weighted images were obtained from healthy control (n = 20), acute WAD (n = 14) and chronic WAD (n = 14) participants aged 18-39 years. Demographic, WAD severity (neck disability index) and body morphometry data were collected from each participant. Manual segmentation of the oropharynx was undertaken by blinded researchers between the top of the soft palate and tip of the epiglottis. Digital 3D oropharynx models were constructed from the segmented images and principal component (PC) analysis was performed with the PC weights normalized to z-scores for consistency. Statistical analyses were undertaken using multivariate linear models. In the first statistical model the independent variable was group (acute WAD, chronic WAD, control); and in the second model the independent variable was WAD severity (recovered/mild, moderate/severe). The covariates for both models included height, weight, average neck length and sex. Shape models were constructed to visualize the effect of perturbing these covariates for each relevant mode. The shape model revealed five modes which explained 90% of the variance: mode 1 explained 59% of the variance and primarily described differences in isometric size of the oropharynx, including elongation; mode 2 (13%) primarily described lateral (width) and AP (depth) dimensions; mode 3 (8%) described retroglossal AP dimension; mode 4 (6%) described lateral dimensions at the retropalatal-retroglossal junction and mode 5 (4%) described the lateral dimension at the inferior retroglossal region. There was no difference in shape (mode 1 p = 0.52; mode 2 p = 0.96; mode 3 p = 0.07; mode 4 p = 0.54; mode 5 p = 0.74) between control, acute WAD and chronic WAD groups. There were no statistical differences for any mode (mode 1 p = 0.12; mode 2 p = 0.29; mode 3 p = 0.56; mode 4 p = 0.99; mode 5 p = 0.96) between recovered/mild and moderate/severe WAD. Sex was not significant in any of the models but for mode 1 there was a significant association with height (p = 0.007), mode 2 neck length (p = 0.044) and in mode 3 weight (p = 0.027). Although SSM did not detect differences between WAD cohorts, it did detect associations with body morphology indicating that it may be a useful tool for examining differences in the oropharynx.

Individuals with gluteal tendon repair display similar hip biomechanics to those of a healthy cohort during a sit-to-stand task.

BACKGROUND: Gluteal-tendon repair (GTR) is reported to be effective for relieving pain and improving clinical function in patients with gluteal-tendon tears. The sit-to-stand (STS) task is an important activity of daily living and is often used to assess functional capacity in clinical populations. Understanding if and how STS performance is altered in individuals with gluteal tendon repair may be an effective marker of GTR outcomes as well as a possible therapeutic target for post-operative rehabilitation. RESEARCH QUESTION: Do biomechanical parameters during STS differ between age- and sex-matched participants with and without gluteal-tendon repair? METHODS: 27 participants with a GTR and 29 healthy participants performed the STS task. Data were acquired using the three-dimensional motion capture system and forceplates. Outcomes of interest were task duration, rate of force development, trunk, pelvis, and hip joint angles, moments and powers. Differences were assessed using Generalised linear multivariate models and statistical parametric mapping. RESULTS: GTR patients performed the STS movement significantly slower (1.4+/- 0.40 s) compared to controls (1.1+/ -0.2 s) with a significantly lower rate of force development (35.1+/- 5.7 N/kg/ms vs 30.3+/- 8.5 N/kg/ms). There were no group differences for hip, pelvis, or trunk angle over the movement cycle or for maximal or minimal values. Furthermore, there were no significant differences detected in hip joint kinetics. However, there appeared to be substantial between-subject variability indicating different patient-specific movements patterns. SIGNIFICANCE: Individuals with a GTR performed the STS task about 20 % slower than healthy controls with a lower rate of force development. The individual variations indicate that participants likely employed different movement strategies to achieve STS. While the lack of differences between groups could suggest that GTR helps restore function and corrects the proposed underlying aetiology, it is possible that the STS task was not sufficiently challenging to discriminate between groups.

Influence of component design on in vivo tibiofemoral contact patterns during kneeling after total knee arthroplasty: a systematic review and meta-analysis.

PURPOSE: Modern TKR prostheses are designed to restore healthy kinematics including high flexion. Kneeling is a demanding high-flexion activity. There have been many studies of kneeling kinematics using a plethora of implant designs but no comprehensive comparisons. Visualisation of contact patterns allows for quantification and comparison of knee kinematics. The aim of this systematic review was to determine whether there are any differences in the kinematics of kneeling as a function of TKR design. METHODS: A search of the published literature identified 26 articles which were assessed for methodologic quality using the MINORS instrument. Contact patterns for different implant designs were compared at 90° and maximal flexion using quality-effects meta-analysis models. RESULTS: Twenty-five different implants using six designs were reported. Most of the included studies had small-sample sizes, were non-consecutive, and did not have a direct comparison group. Only posterior-stabilised fixed-bearing and cruciate-retaining fixed-bearing designs had data for more than 200 participants. Meta-analyses revealed that bicruciate-stabilised fixed-bearing designs appeared to achieve more flexion and the cruciate-retaining rotating-platform design achieved the least, but both included single studies only. All designs demonstrated posterior-femoral translation and external rotation in kneeling, but posterior-stabilised designs were more posterior at maximal flexion when compared to cruciate retaining. However, the heterogeneity of the mean estimates was substantial, and therefore, firm conclusions about relative behaviour cannot be drawn. CONCLUSION: The high heterogeneity may be due to a combination of variability in the kneeling activity and variations in implant geometry within each design category. There remains a need for a high-quality prospective comparative studies to directly compare designs using a common method. LEVEL OF EVIDENCE: Systematic review and meta-analysis Level IV.

The influence of total knee arthroplasty design on kneeling kinematics: a prospective randomized clinical trial.

AIMS: Modern total knee arthroplasty (TKA) prostheses are designed to restore near normal kinematics including high flexion. Kneeling is a high flexion, kinematically demanding activity after TKA. The debate about design choice has not yet been informed by six-degrees-of-freedom in vivo kinematics. This prospective randomized clinical trial compared kneeling kinematics in three TKA designs. METHODS: In total, 68 patients were randomized to either a posterior stabilized (PS-FB), cruciate-retaining (CR-FB), or rotating platform (CR-RP) design. Of these patients, 64 completed a minimum one year follow-up. Patients completed full-flexion kneeling while being imaged using single-plane fluoroscopy. Kinematics were calculated by registering the 3D implant models onto 2D-dynamic fluoroscopic images and exported for analysis. RESULTS: CR-FB designs had significantly lower maximal flexion (mean 116° (SD 2.1°)) compared to CR-RP (123° (SD 1.6°)) and PS-FB (125° (SD 2.1°)). The PS-FB design displayed a more posteriorly positioned femur throughout flexion. Furthermore, the CR-RP femur was more externally rotated throughout kneeling. Finally, individual patient kinematics showed high degrees of variability within all designs. CONCLUSION: The increased maximal flexion found in the PS-FB and CR-RP designs were likely achieved in different ways. The PS-FB design uses a cam-post to hold the femur more posteriorly preventing posterior impingement. The external rotation within the CR-RP design was surprising and hasn't previously been reported. It is likely due to the polyethylene bearing being decoupled from flexion. The findings of this study provide insights into the function of different knee arthroplasty designs in the context during deep kneeling and provide clinicians with a more kinematically informed choice for implant selection and may allow improved management of patients' functional expectations. Cite this article: Bone Joint J 2021;103-B(1):105-112.

People after gluteal tendon repair have gait characteristics which are similar to those of a healthy cohort.

BACKGROUND: Gluteal-tendon repair is reported to be effective for relieving pain and improving function in patients with gluteal-tendon tears. However, post-operative three-dimensional gait analysis has never been conducted in gluteal-tendon repair patients. Thus, our primary aim was to investigate how biomechanical gait parameters differ between age- and sex-matched participants with and without gluteal-tendon repair. METHODS: Vicon motion analysis technology was used to measure gait characteristics of 25 gluteal-tendon repair participants and 29 matched healthy comparison group participants. A generalised linear multivariate model was used to compare external hip-adduction moment, range of movement in hip adduction and internal rotation, pelvic obliquity, trunk lean, stride length and velocity of both cohorts throughout stance. FINDINGS: There were no differences between the groups in external hip adduction moment, pelvic obliquity and range of movement in hip adduction and internal rotation. Gluteal-tendon repair participants had a shorter stride length (P = 0.031) and reduced walking velocity (P = 0.015). Ipsilateral trunk lean was reduced in gluteal-tendon repair participants at the first-peak external hip-adduction moment (P = 0.016), mid-stance minimum external hip-adduction moment (P = 0.029) and second-peak external hip-adduction moment (P = 0.006). INTERPRETATION: There were no differences between the gluteal-tendon repair and comparison groups for external hip-adduction moment and pelvic obliquity. This suggests that gluteal-tendon repair may restore hip control in stance. Slower walking speed, reduced stride length and decreased ipsilateral trunk lean may reflect persistence of pre-operatively developed gait adaptations. Future studies of gait biomechanics before and after gluteal-tendon repair would be needed to substantiate this theory.

Shape is only a weak predictor of deep knee flexion kinematics in healthy and osteoarthritic knees.

Tibiofemoral shape influences knee kinematics but little is known about the effect of shape on deep knee flexion kinematics. The aim of this study was to examine the association between tibiofemoral joint shape and kinematics during deep kneeling in patients with and without osteoarthritis (OA). Sixty-one healthy participants and 58 patients with end-stage knee OA received a computed tomography (CT) of their knee. Participants completed full flexion kneeling while being imaged using single-plane fluoroscopy. Six-degree-of-freedom kinematics were measured by registering a three-dimensional (3D)-static CT onto 2D-dynamic fluoroscopic images. Statistical shape modeling and bivariate functional principal component analysis (bfPCA) were used to describe variability in knee shape and kinematics, respectively. Random-forest-regression models were created to test the ability of shape to predict kinematics controlling for body mass index, sex, and group. The first seven modes of the shape model up to three modes of the bfPCAs captured more than 90% of the variation. The ability of the random forest models to predict kinematics from shape was low, with no more than 50% of the variation being explained in any model. Furthermore, prediction errors were high, ranging between 24.2% and 29.4% of the data. Variations in the bony morphology of the tibiofemoral joint were weakly associated with the kinematics of deep knee flexion. The models only explained a small amount of variation in the data with high error rates indicating that additional predictors need to be identified. These results contribute to the clinical understanding of knee kinematics and potentially the expectations placed on high-flexion total knee replacement design.

Total volume of cam deformity alone predicts outcome in arthroscopy for femoroacetabular impingement.

PURPOSE: Rates for arthroscopic surgery for femoroacetabular impingement (FAI) are rising and there is growing concern related to the effectiveness and costs associated with this treatment. There is a general lack of consensus as to the criteria for surgical selection of patients. The purpose of this study was to determine whether patient outcome following arthroscopic surgery for FAI could be predicted based on the size and location of deformity. The specific questions were: (1) what is the morphology of FAI in terms of size and location of deformity in a cohort of patients selected for surgery? (2) Do morphological factors predict postoperative improvement in hip scores? (3) Do morphological factors predict preoperative hip scores? (4) Are there clusters of morphological factors which explain postsurgical improvement in hip scores? MATERIALS AND METHODS: Computer tomography (CT) surgical plans of 90 hips in 79 patients who had undergone primary hip arthroscopy for FAI were retrospectively reviewed. Four parameters for the femur and acetabulum were created: total depth of deformity, maximal depth, extent and the position of maximal deformity. This data were compared with prospectively acquired preoperative and postoperative patient outcome data using generalised linear models. RESULTS: The cohort comprised 33 males and 46 females aged 37.9 (18-61). The majority (74%) had mixed morphology, 23% isolated cam, and 3% isolated pincer. Overall, the bone depth was greatest and more extensive on the femur. Increased total additional cam deformity alone predicted poorer postoperative outcome (p = 0.045). None of the morphological factors were related to preoperative scores and there was no association between the meta-variables and postoperative outcome. CONCLUSIONS: The results of this study indicate that a greater total volume of cam deformity led to poorer postoperative patient outcome scores at 1 year. This information provides the surgeon with more accurate patient-specific data for prediction of expected outcomes. LEVEL OF EVIDENCE: Level III diagnostic.

Age has a minimal effect on knee kinematics: A cross-sectional 3D/2D image-registration study of kneeling.

INTRODUCTION: Kneeling is an activity of daily living which becomes difficult with knee pathology and increasing age. This study aimed to capture kneeling kinematics in six-degrees-of-freedom in healthy adults as a function of age. METHODS: 67 healthy knee participants aged from 20 to 90 years were categorised into four 20-year age-groups. 3D knee kinematics were captured using 3D/2D image-registration of CT scan and fluoroscopy during kneeling. Kinematic variables of position, displacement and rate-of-change in six-degrees-of-freedom were compared between age-groups while controlling for University of California Los Angeles activity scale and the Assessment of Quality of Life physical score. RESULTS: Over the entire kneeling cycle there were few differences between the age-groups. Results are reported as pairwise contrasts. At 110° flexion, 80+ knees were more varus than 20-39 and 40-69 (4.9° (95%CI: 0.6°, 9.1°) and 6.4° (2.1°, 10.7°), respectively). At 120° flexion, the 80+ age-group femur was 5.5 (0.0, 11.0) mm more anterior than 20-39. Between 120° to maximum flexion, 80+ knees rotated into valgus more than 20-39, 40-59 and 60-79 (5.5° (1.2°, 9.8°); 5.5° (1.1°, 9.8°); and 4.5° (0.9°, 7.5°), respectively). CONCLUSION: This is the first study to report kneeling knee kinematics of ageing using 3D/2D image registration. We found that ageing does not change knee kinematics under 80 years, and there are minimal changes between 120° and maximum flexion between the younger and 80+ age-groups. Thus, difficulty kneeling should not be considered to be an inevitable consequence of ageing.

Statistical shape modelling reveals large and distinct subchondral bony differences in osteoarthritic knees.

Knee osteoarthritis (OA) results in changes such as joint-space narrowing and osteophyte formation. Radiographic classification systems group patients by the presence or absence of these gross anatomical features but are poorly correlated to function. Statistical-shape modelling (SSM) can detect subtle differences in 3D-bone geometry, providing an opportunity for accurate predictive models. The aim of this study was to describe and quantify the main modes of shape variation which distinguish end-stage OA from asymptomatic knees. Seventy-six patients with OA and 77 control participants received a CT of their knee. 3D models of the joint were created by manual segmentation. A template mesh was fitted to all meshes and rigidly aligned resulting in a set of correspondent meshes. Principal Component Analysis (PCA) was performed to create the SSM. Logistic regression was performed on the PCA weights to distinguish morphological features of the two groups. The first 7 modes of the SSM captured >90% shape variation with 6 modes best distinguishing between OA and asymptomatic knees. OA knees displayed sub-chondral bone expansion particularly in the condyles and posterior medial tibial plateau of up to 10 mm. The model classified the two groups with 95% accuracy, 96% sensitivity, 94% specificity, and 97% AUC. There were distinct features which differentiated OA from asymptomatic knees. Further research will elucidate how magnitude and location of shape changes in the knee influence clinical and functional outcomes.

Analysis of Kneeling by Medical Imaging Shows the Femur Moves Back to the Posterior Rim of the Tibial Plateau, Prompting Review of the Concave-Convex Rule.

BACKGROUND: Physical therapists assess joint movement by observation and palpation. New imaging technologies that enable vision of bones and joints during functional activities can be used to analyze joint kinematics and review traditional assumptions. PURPOSE: The purpose was to measure relations between flexion, rotation, and translation at the knee and to validate these visually. DESIGN: This was a prospective, observational study. METHODS: Twenty-five healthy participants aged >45 years (13 males) knelt from upright kneeling to full flexion with the foot free. Fluoroscopy recorded movement at 30 frames per second of x-ray. A computed tomography scan provided 3-dimensional data, which were registered to the fluoroscopy frames to provide a moving model. Motion in 6 degrees of freedom was analyzed for coupling of movements. RESULTS: Mean (standard deviation) flexion reached by participants was 142 (6)° in kneeling. Posterior femoral translation was coupled to flexion (r = 0.96). From 90° to 150° flexion, the femur translated posteriorly by 36 (3) mm to finish 23 (3) mm posterior to the center of the tibia at 150° flexion. From 90° to 150° flexion, the femur externally rotated from 8 (6)° to 16 (5)°. Flexion was coupled to rotation (r = 0.47). Abduction was <3° and lateral translation was <3 mm. Visually, the femur appeared to translate posteriorly until the femoral condyles rested on the posterior rim of the tibial plateau with concurrent external rotation so that the popliteal fossa aligned with the posterior margin of the medial tibial plateau. LIMITATIONS: A limitation of the study is that knee flexion can include squat and lunge as well as kneeling. CONCLUSION: Deep flexion requires femoral posterior translation and external rotation. These findings invite review of the concave-convex rule as it might apply to manual therapy of the knee.

Squatting, lunging and kneeling provided similar kinematic profiles in healthy knees-A systematic review and meta-analysis of the literature on deep knee flexion kinematics.

BACKGROUND: Understanding healthy deep flexion kinematics will inform the design of conservative clinical rehabilitation strategies for knee osteoarthritis and contribute to improved knee prosthesis design. This study is a systematic review and meta-analysis of the kinematic outcomes measured at the healthy tibiofemoral joint during loaded deep knee flexion. METHODS: A computerised literature search and bibliography review without date restriction identified twelve studies with 164 participants aged 25-61 years in-vivo, and 69-93 years in-vitro. Flexion higher than 120° was achieved by squatting, lunging or kneeling. Measurement technologies in-vivo included radiographs, open MRI and 2D-3D MRI or CT image registration on fluoroscopy. Microscribe was used in-vitro. RESULTS: Outcomes were either six degrees-of-freedom based on femur movement or contact patterns on the tibial plateau. The meta-analysis demonstrated that in-vivo, between 120° and 135° of flexion, the tibia internally rotated (mean difference (MD) = 4.6°, 95% CI 3.55° to 5.64°). Both the medial-femoral-condyle and lateral-femoral-condyle translated posteriorly, (MD = 10.4 mm, 95% CI 6.9 to 13.9 mm) and (MD = 5.55 mm, 95% CI 4.64 to 6.46 mm) respectively. There was some evidence of femoral medial translation (3.8 mm) and adduction (1.9° to 3.3°), together with medial compression (1.7 mm) and lateral distraction (1.9) mm. CONCLUSIONS: Across the in-vivo studies, consistent kinematic patterns emerged; despite the various measurement technologies and reference methods. In contrast, in-vivo and in-vitro results were contradictory. TRIAL REGISTRATION: This systematic review protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) on 25 February 2017 (registration number: 42017057614).

Kinematics of knees with osteoarthritis show reduced lateral femoral roll-back and maintain an adducted position. A systematic review of research using medical imaging.

BACKGROUND: While several studies describe kinematics of healthy and osteoarthritic knees using the accurate imaging and computer modelling now possible, no systematic review exists to synthesise these data. METHOD: A systematic review extracted quantitative observational, quasi-experimental and experimental studies from PubMed, Scopus, Medline and Web of Science that examined motion of the bony or articular surfaces of the tibiofemoral joint during any functional activity. Studies using surface markers, animals, and in vitro studies were excluded. RESULTS: 352 studies were screened to include 23 studies. Dynamic kinematics were recorded for gait, step-up, kneeling, squat and lunge and quasi-static squat, knee flexion in side-lying or supine leg-press. Kinematics were described using a diverse range of measures including six degrees of freedom kinematics, contact patterns or the projection of the femoral condylar axis above the tibia. Meta-analysis of data was not possible since no three papers recorded the same activity with the same measures. Visual evaluation of data revealed that knees with osteoarthritis maintained a more adducted position and showed less posterior translation of the lateral femoral condylar axis than healthy knees. Variability in activities and in recording measures produced greater variation in kinematics, than did knee osteoarthritis. CONCLUSION: Differences in kinematics between osteoarthritic and healthy knees were observed, however, these differences were more subtle than expected. The synthesis and progress of this research could be facilitated by a consensus on reference systems for axes and kinematic reporting.