Weight-bearing Magnetic Resonance Research Articles

Meniscal extrusion consensus statement: Acollaborative survey within the Meniscus International Network (MenIN) Study Group.

The purpose of the present study was to perform a survey administered to members of the Meniscus International Network (MenIN) Study Group, seeking to delineate the most contentious aspects of meniscal extrusion classification and provide a foundation for new, more comprehensive definitions and treatments for these pathologies. MenIN Study Group is a group of international experts treating and performing research on meniscus pathology and treatment. All MenIN Study Group members were asked to complete a survey aimed at establishing criteria for the optimal classification system for meniscal extrusion. Data obtained from the completed questionnaires were transferred into a spreadsheet and then analysed. All responses are presented as counts, percentagesor means. Forty-seven (85.5%) MenIN Study Group members completed the survey and were included in this analysis. Key aspects recommended for inclusion in a comprehensive classification system for meniscal extrusion included laterality (93.6%), anatomical location (76.6%), patient age (76.6%), body mass index (BMI) (68.1%)and aetiology (68.1%). For classifying meniscal extrusion, 53.2% considered the distance in millimetres from the tibial plateau's outer margin as the most reliable measurement technique on imaging. Preferences for imaging modalities varied, with 44.7% favouring weight-bearing magnetic resonance imaging (MRI) and 36.2% opting for weight-bearing ultrasound due to its greater availability. Respondents advocated for a classification system addressing stability or progression of meniscal extrusion (66%), reducibility (53.2%), potential progression of knee osteoarthritis (OA) (83%), influencing treatment approaches (83%), a gradation system (83%), consideration of dynamic factors (66%), association with clinical outcomes and prognosis (76.6%)and investigation around centralization procedures (57.4%). In conclusion, the findings of this survey shed light on the global perspectives regarding meniscal extrusion classification. It was generally felt that a new classification of extrusion measured on MRI scans at the mid-tibial plateau should be developed, which considers factors such as laterality, anatomical location, age, BMIand aetiology. Additionally, the results support the integration of dynamic factors and clinical outcomes in MRI-based classifications to inform treatment approaches. Level IV.

Lumbar Spine Anatomy in Supine versus Weight- Bearing Magnetic Resonance Imaging: Detecting Significant Positional Changes and Testing Reliability of Quantification.

Testing between and within group differences and assessing reliability of measurements. To study and compare lumbar spine morphology in supine and weight-bearing (WB) magnetic resonance imaging (MRI). Upright lumbar MRI may uncover anatomical changes that may escape detection when using conventional supine imaging. This study quantified anatomical dimensions of the lumbar spine in the supine and WB MRI, compared specific morphometric differences between them, and tested the intra-rater reliability of the measurements. Repeated measures analysis was used to compare within- and between-session measurements performed on the supine and WB images. Reliability and agreement were assessed by calculating intraclass correlation (ICC) coefficient. Data from 12 adults without any history of back pain were used in this study. Sagittal T2-weighted images of the lumbar spine were acquired in the supine and WB positions twice (in two separate sessions scheduled within a week). Linear, angular dimensions, and cross-sectional areas (CSAs) were measured using proprietary software. Supine and WB data acquired from the two imaging sessions were tested for intra-rater reliability. Quantified data were normalized for each session to test the significance of differences. ICC was calculated to test the reliability of the measurements. Linear, angular, and CSA measurements demonstrated strong within-position (supine and WB) correlations (r -values, 0.75-0.97). Between-position (supine vs. WB) differences were significant for all measured dimensions (p<0.05). Between-session measurements demonstrated a strong correlation (r -values, 0.64-0.83). Calculated ICC showed strong agreement among the measurements. Anatomical dimensions of the lumbar spine may demonstrate consistent and significant differences between supine and WB MRI for specific structural parameters.

Contact area and pressure changes of patellofemoral joint during stair ascent and stair descent

PurposeTo investigate the differences of patellofemoral joint pressure and contact area between the process of stair ascent and stair descent.MethodsThe finite element models of 9 volunteers without disorders of knee (9 males) to estimate patellar cartilage pressure during the stair ascent and the stair descent. Simulations took into account cartilage morphology from magnetic resonance imaging, joint posture from weight-bearing magnetic resonance imaging, and ligament model. The three-dimension models of the patella, femur and tibia were developed with the medical image processing software, Mimics 11.1. The ligament was established by truss element of the non-linear FE solver. The equivalent gravity direction (-z direction) load was applied to the whole end of femur (femoral head) according to the body weight of the volunteers, and the force of patella was observed. A paired-samples t-test or Wilcoxon rank sum test to make comparisons between stair ascent and stair descent. Statistical analyses were performed using SPSS 22.0 using a P value of 0.05 to indicate significance.ResultsDuring the stair descent (knee flexion at 30°), the contact pressure of the patella was 2.59 ± 0.06Mpa. The contact pressure of femoral trochlea cartilage was 2.57 ± 0.06Mpa. During the stair ascent (knee flexion at 60°), the contact pressure with patellar cartilage was 2.82 ± 0.08Mpa. The contact pressure of the femoral trochlea cartilage was 3.03 ± 0.11Mpa. The contact area between patellar cartilage and femoral trochlea cartilage was 249.27 ± 1.35mm2 during the stair descent, which was less than 434.32 ± 1.70mm2 during the stair ascent. The area of high pressure was located in the lateral area of patella during stair descent and the area of high pressure was scattered during stair ascent.ConclusionThere are small change in the cartilage contact pressure between stair ascent and stair descent, indicating that the joint adjusts the contact pressure by increasing the contact area.

High-grade pivot-shift phenomenon after anterior cruciate ligament injury is associated with asymmetry of lateral and medial compartment anterior tibial translation and lateral meniscus posterior horn tears.

To investigate whether the high-grade pivot-shift phenomenon is associated with asymmetry of the lateral and medial compartment anterior tibial translation (L-ATT and M-ATT) and lateral meniscus posterior horn (LMPH) tears in anterior cruciate ligament (ACL) injuries. A retrospective analysis was performed on 192 consecutive patients who had complete ACL injuries between January 2019 and December 2020. Among these, 156 met the inclusion criteria. L-ATT and M-ATT were measured using preoperative weight-bearing magnetic resonance imaging (MRI), and the differences between L-ATT and M-ATT were calculated. Thirty-five patients who demonstrated excessive differences in L-ATT and M-ATT (> 6.0mm) were regarded as asymmetric (study group), and 36 patients with minimal or no differences in L-ATT and M-ATT (< 3.0mm) were allocated to the control group. Demographic data, grade of the pivot-shift test, integrality of LMPH, and medial meniscus posterior horn (MMPH) were compared between the groups. Moreover, predictors of high-grade pivot-shift phenomenon, including asymmetry of L-ATT and M-ATT, integrity of LMPH and MMPH, time from injury to surgery, sex, age, and body mass index (BMI) were assessed using multivariable logistic regression analysis. The difference between L-ATT and M-ATT in the study group was significantly higher than that in the control group (mean ± SD: 8.4 ± 2.1mm vs. 1.5 ± 1.0mm, P < 0.001). A higher proportion of patients with high-grade pivot-shift phenomenon (2 + and 3 +) and LMPH tears were identified in the study group (high-grade pivot-shift phenomenon: 25/35 vs. 13/36, P = 0.003; LMPH tears: 18/35 vs. 5/36, P = 0.001). Additionally, asymmetry of L-ATT, M-ATT (odds ratio 5.8; 95% CI 1.7-19.8; P = 0.005), and LMPH tears (odds ratio 3.8; 95% CI 1.3-11.6; P = 0.018) were found to be good predictors of the high-grade pivot-shift phenomenon after ACL injury, whereas MMPH tears, time from injury to surgery, sex, age, and BMI were not. In patients with ACL injury, the high-grade pivot-shift phenomenon is associated with asymmetry between L-ATT and M-ATT, and LMPH tears. III.

Weight-Bearing Magnetic Resonance Imaging as a Diagnostic Tool That Generates Biomechanical Changes in Spine Anatomy.

Weight-bearing magnetic resonance imaging (MRI) is a unique modality in diagnostic imaging that allows for the assessment of spinal pathology in ways considered previously inaccessible or insufficient with the conventional MRI technique. Due to limitations in positioning within the MRI machine itself, difficulties would be posed in determining the underlying cause of a patient’s pain or neurological symptoms, as the traditional supine position utilized can, in many cases, alleviate the severity of presented symptoms. Weight-bearing MRI addresses this concern by allowing a clinician to position a patient (to a certain degree) into flexion, extension, rotation, or side-bending with an axial load that can mimic physiologic conditions in order to replicate the conditions the patient experiences in order to give clinicians a clearer understanding of the anatomical relationship of the spine and surrounding tissues that may lead to a particular presentation of symptoms. These findings can then guide treatment approaches that are better tailored to a patient’s needs in order to initiate treatment earlier and shorten the duration of treatment necessary for patient benefit. The goal of this review is to describe and differentiate weight-bearing MRI from conventional MRI as well as examine the advantages and disadvantages of either imaging modality. This will include assessing cost-effectiveness and improvements in clinical outcomes. Further, the advancements of weight-bearing MRI will be discussed, including potentially unique clinical applications in development.

Evaluation of the Peripheral Rim Instability of the Discoid Meniscus in Children by Using Weight-Bearing Magnetic Resonance Imaging.

The aim of the study was to assess the peripheral rim instability and the clinical value of discoid meniscus. We retrospectively studied 79 magnetic resonance imaging (MRI) examinations of discoid meniscus from May 2017 to September 2019. The patient symptoms and physical findings were documented. The patients underwent "dedicated" 0.25 T supine and weight-bearing MRI examination. Finally, all patients underwent arthroscopy. Sound/clicking during motion (P = 0.009) and limited extension (P = 0.044) of subjective symptoms, clunk during motion (P = 0.035), and flexion contracture (P = 0.012) of physical findings were significant predictors of peripheral rim instability. The comparison of the weight-bearing MRI with the supine position MRI demonstrated that the disformed discoid meniscus was shifted significantly and that no shift was displaced centrally (P = 0.001). A correlation between discoid meniscal displacement and the presence of peripheral rim instability in arthroscopy was noted (P < 0.001) using weight-bearing MRI. The clinical symptoms of the patients combined with weight-bearing MRI can determine peripheral rim instability optimally.

Analysis of Clinical Value of Weight-Bearing Magnetic Resonance Diagnosis of Ankle Ligament Sports Injury

Observe and analyze the effect of weighted magnetic resonance imaging in the diagnosis of ankle ligament sports injury. Methods: A total of 50 patients with ankle ligament sports injuries were recruited as research subjects to conduct clinical diagnostic research. After admission, the patient first underwent MRI diagnosis of ankle joint ligament sports injury and then received surgical treatment. Based on the results of surgical treatment, the diagnostic effect of weighted magnetic resonance imaging and the detection of concurrent injuries were compared. After surgery, a total of 24 cases of ankle ligament contusion were confirmed in 50 patients, 19 cases were partially ruptured, 7 cases were completely ruptured, and 26 cases had joint effusion, tendon injuries in 17 cases, fractures in 8 cases, and talar articular cartilage lesions in 19 cases. After comparison, there was no significant difference between the results of weight-bearing magnetic resonance diagnosis and the detection rate of concurrent injuries compared with the surgical results, P> 0.05. Conclusion: The application of weight-bearing magnetic resonance imaging in the diagnosis of ankle ligament sports injury can effectively diagnose the patient's ligament injury and the type of combined injury, and has significant clinical application value.

Weight-bearing Magnetic Resonance Imaging of the Cervical Spine

The cervical spine is subject to the effect of gravity in the upright position. Weight-bearing upright magnetic resonance imaging (MRI) potentially allows a better diagnosis and evaluation of cervical spine pathology that may be masked or not fully appreciated in the usual non-weight-bearing supine position. Only limited studies are currently available in this area. This article summarizes the current literature on weight-bearing MRI of the cervical spine.

Dynamic Weight-bearing Magnetic Resonance in the Clinical Diagnosis of Internal Temporomandibular Joint Disorders.

Temporomandibular joint (TMJ) disorders can be painful and cause functional limitations and bone changes. Deeper clinical knowledge of the pathologies related to the TMJ has always been hindered by the difficult identification of the causes that limit its movement. Weight-bearing magnetic resonance imaging (WBMRI) can reproduce the articular movement in orthostasis and allows the evaluation of joint movement. WBMRI, compared with other procedures such as double-type condylography and real-time dynamic ultrasound, helps to better identify tissue characteristics of the articular glenoid-condylar surfaces, articular space, disk position on both the open and closed mouth, and the locoregional musculotendinous area. WBMRI also identifies the true position of the articular disk in orthostasis, emphasizing the different joint positions compared with the study carried out in a clinostatic (supine) position.

Knee stability after anterior cruciate ligament reconstruction with weight-bearing magnetic resonance imaging

Objective: To investigate the application value of the weight-bearing magnetic resonance imaging (MRI) in evaluating the stability of knee joint after anterior cruciate ligament reconstruction. Methods: From July 2011 to August 2013, a total of 25 patients with anterior cruciate ligament rupture and reconstruction surgery in the Second Affiliated Hospital of Soochow University were enrolled in this study, including 18 males and 7 females, with an average age of (32±5) years. All the patients underwent the weight-bearing MRI, knee joint passive relaxation test (Kneelax 3), and Lysholm score before the surgery and 3 and 6 months after the surgery. The three examinations before and after the operation were analyzed by repeated measures of general linear model, and paired t test was used to compare the results before and after the operation. The correlation between the three preoperative examinations was statistically analyzed. Results: The relaxation data measured by Kneelax 3 after the surgery was significantly lower than that before the operation [(1.1±0.9) mm vs (6.1±1.3) mm, t=16.9, P<0.01]. The post-operative lateral tibial plateau anterior shift score was less than the pre-operative score [(3.0±0.7) mm vs (4.8±1.2) mm, t=6.2, P<0.01]. The post-operative Lysholm score was significantly higher than that before the operation (89±6 vs 64±14, t=-8.3, P<0.05). There was a negative correlation between the anterior displacement of the lateral platform and Lysholm score (r=-0.902, P<0.01). There was no correlation between anterior displacement and passive relaxation of the lateral platform in preoperative weight-bearing MRI. Conclusions: Anterior cruciate ligament reconstruction can improve the knee stability. The stability of knee joint can be evaluated by weight-bearing MRI. The anterior tibial displacement measured by the weight-bearing MRI is correlated with the clinical score.

Assessment of In Vivo Lumbar Inter-Vertebral Motion: Reliability of a Novel Dynamic Weight-Bearing Magnetic Resonance Imaging Technique Using a Side-Bending Task.

Study DesignBetween-session reliability of a magnetic resonance imaging (MRI) based experimental technique to quantify lumbar inter-vertebral motion in humans.PurposeWe have developed a novel, dynamic, MRI-based approach for quantifying in vivo lumbar inter-vertebral motion. In this study, we present the protocol’s reliability results to quantify inter-vertebral spine motion.Overview of LiteratureMorphometric studies on intervertebral displacements using static, supine MRI and quantification of dynamic spine motion using different X-ray based radiography techniques are commonly found in the literature. However, reliability testing of techniques assessing real-time lumbar intervertebral motion using weight-bearing MRI has rarely been reported.MethodsTen adults without a history of back pain performed a side-bending task on two separate occasions, inside an open-MRI, in a weight-bearing, upright position. The images were acquired during the task using a dynamic magnetic resonance (MR) sequence. The MRI imaging space was externally calibrated before the study to recreate the imaging volume for subsequent use in an animation software. The dynamic MR images were processed to create side-bending movement animations in the virtual environment. Participant-specific three-dimensional models were manually superimposed over vertebral image silhouettes in a sequence of image frames, representing the motion trials. Inter-vertebral axes and translation and rotational displacements of vertebrae were quantified using the animation software.ResultsQuantification of inter-vertebral rotations and translations shows high reliability. Between-session reliability results yielded high values for the intra-class correlation coefficient (0.86–0.93), coefficient of variation (13.3%–16.04%), and Pearson’s correlation coefficients (0.89–0.98).ConclusionsThis technique may be developed further to improve its speed and accuracy for diagnostic applications, to study in vivo spine stability, and to assess outcomes of surgical and non-surgical interventions applied to manage pathological spine motion.

Sagittal Plane Corrections around the Knee.

AbstractStability of the knee joint depends on soft tissues integrity and bony balance in the frontal and sagittal planes during gait. Although frontal plane imbalance is a well-known knee pathology, commonly treated by high tibial osteotomy, sagittal plane imbalance is less common, with fewer and more challenging surgical treatment options. The purpose of this review is to describe the biomechanical effects of sagittal knee imbalances and to outline the indications, techniques, and outcomes of sagittal knee osteotomies. The article details the reference axes and methods to measure posterior tibial slope (PTS), the principal indicator of sagittal imbalance, and its influence on anteroposterior tibial translations and rotational stability of the joint. The authors also outline the roles of the anterior and posterior cruciate ligaments in maintaining sagittal balance, with focus on the associations between PTS and ligament deficiencies, as well as posterolateral corner injuries. Different techniques and indications of tibial osteotomy in the sagittal plane, both above and below the anterior tibial tubercle, are compared in terms of technical difficulty, clinical benefits, and complication rates. The authors conclude on the importance of understanding sagittal knee imbalance, particularly in cases of ligament deficiencies, where the deformity can be the primary cause for lesions. Surgeons must identify the underlying deformities associated with sagittal imbalance, which can be recognized on weight-bearing X-rays and magnetic resonance imaging scans. Different techniques of sagittal osteotomies offer effective treatments for certain indications and should be considered in selected cases for unstable knees with ligament lesions.

The Role of Cartilage Stress in Patellofemoral Pain.

Elevated cartilage stress has been identified as a potential mechanism for retropatellar pain; however, there are limited data in the literature to support this mechanism. Females are more likely to develop patellofemoral pain than males, yet the causes of this dimorphism are unclear. We used experimental data and computational modeling to determine whether patients with patellofemoral pain had elevated cartilage stress compared with pain-free controls and test the hypothesis that females exhibit greater cartilage stress than males. We created finite element models of 24 patients with patellofemoral pain (11 males and 13 females) and 16 pain-free controls (8 males and 8 females) to estimate peak patellar cartilage stress (strain energy density) during a stair climb activity. Simulations took into account cartilage morphology from magnetic resonance imaging, joint posture from weight-bearing magnetic resonance imaging, and muscle forces from an EMG-driven model. We found no difference in peak patellar strain energy density between those with patellofemoral pain (1.9 ± 1.23 J·m(-3)) and control subjects (1.66 ± 0.75 J·m(-3), P = 0.52). Females exhibited greater cartilage stress compared with males (2.2 vs 1.3 J·m(-3), respectively; P = 0.0075), with large quadriceps muscle forces (3.7 body weight in females vs 3.3 body weight in males) and 23% smaller joint contact area (females, 467 ± 59 mm2, vs males, 608 ± 95 mm2). Patients with patellofemoral pain did not display significantly greater patellar cartilage stress compared with pain-free controls; however, there was a great deal of subject variation. Females exhibited greater peak cartilage stress compared with males, which might explain the greater prevalence of patellofemoral pain in females compared with that in males, but other mechanical and biological factors are clearly involved in this complex pathway to pain.

Dynamic measurement of patello-femoral joint alignment using weight-bearing magnetic resonance imaging (WB-MRI)

ObjectiveAim of our work was to compare standard and weight-bearing WB-MRI to define their contribution in unmasking patello-femoral (PF) maltracking and to define what measurement of patellar alignment is the most reliable. MethodsWe prospectively collected 95 non consecutive patients, clinically divided into 2 groups: group A (the control group), including 20 patients (negative for patellar maltracking), and group B including 75 patients (positive for patellar maltracking). The patients underwent a dedicated 0.25T MRI, in supine and WB position, with knee flexion of 12–15°. The following measurements were performed: Insall-Salvati index (IS), lateral patellar displacement (LPD), lateral patello-femoral angle (LPA) and lateral patellar tilt (LPT). Quantitative and qualitative statistical analyses were performed to compare the results obtained before and after WB-MRI. Measurements were subsequently performed on both groups. ResultsGroup A patients showed no statistically significant variations at all measurements both on standard and WB-MRI. On the basis of measurements made on standard MRI, group B patients were divided into group B1 (23 patients) (negative or positive at 1 measurement) and group B2 (52 patients) (positive at 2 or more measurements). After WB-MRI, group B1 patients were divided into group B1a (6 patients), in case they remained positive at 0/1 measurement, and group B1b (17 patients), in case they became positive at 2 or more measurements. All group B2 patients confirmed to be positive at 2 or more measurements at WB-MRI. Quantitative statistical analysis showed that LPT and LPA were the most reproducible and clinically useful measurements. Qualitative statistical analysis performed on standard and WB-MRI demonstrated that LPT was the best predictive measurement. ConclusionsThis study demonstrates both the high diagnostic value of WB-MRI in unmasking PF-maltracking and the best predictive value of LPT measurement.

The effects of a dynamic patellar realignment brace on disease determinants for patellofemoral instability in the upright weight-bearing condition.

BackgroundPatellar stabilizing braces are used to alleviate pain and prevent subluxation/dislocation by having biomechanical effects in terms of improved patellar tracking. The purpose of this study is to analyze the effects of the dynamic patellar realignment brace, Patella Pro (Otto Bock GmbH, Duderstadt, Germany), on disease determinants in subjects with patellofemoral instability using upright weight-bearing magnetic resonance imaging (MRI).MethodsTwenty subjects (8 males and 12 females) with lateral patellofemoral instability were studied in an open-configuration magnetic resonance imaging scanner in an upright weight-bearing position at full extension (0° flexion) and 15° and 30° flexion with and without the realignment brace. Disease determinants were defined by common patellofemoral indices that included the Insall–Salvati Index, Caton–Deschamps Index, and the Patellotrochlear Index to determine patella height and patella tilt angle, bisect offset, and tuberositas tibiae–trochlear groove (TT–TG) distance to determine patellar rotation and translation with respect to the femur and the alignment of the extensor mechanism.ResultsAnalyses of variance revealed a significant effect of the brace with reduction of the three patellar height ratios, patella tilt angle, and bisect offset as well as TT–TG distance. Post hoc pairwise comparisons of the corresponding conditions with and without the realignment brace revealed significantly reduced patella height ratios, patella tilt angles, and bisect offsets at full extension and 15° and 30° flexion. No significant differences between the TT–TG distances at full extension but significant reductions at 15° and 30° flexion were observed when using the realignment brace compared to no brace.ConclusionsThis study suggests that the dynamic patellar realignment brace is capable of improving disease determinants in the upright weight-bearing condition in the range of 0° to 30° flexion in patients with patellofemoral instability.

Positional pelvic organ prolapse (POP) evaluation using open, weight-bearing magnetic resonance imaging (MRI).

Magnetic resonance imaging (MRI) of patients with pelvic organ prolapse (POP) is completed in the supine position. Open magnetic resonance imaging (MRO) uses vertical magnets, allowing imaging in a variety of upright postures. This pilot study used MRO to evaluate the change of prolapse in different positions compared to non-prolapsed images. In total, 11 women (6 POP, 5 controls) aged 24 to 65 years had 12 MRO images (midline sagittal pelvic line) consecutively when supine, sitting and standing with a full and empty bladder. Lengths between the lowest point of the bladder to the pubococcygeal (PC) and pubopromontoreal (PP) lines in each image were compared, and the ratio of bladder area under the PC and PP lines to the total bladder area. Significant elongation between the PC line and lowest point of the bladder was evident in subjects with POP comparing supine and standing images (p = 0.03), but not controls (p = 0.07). Similarly, this axis was significantly longer in cystocele subjects versus controls only in the standing position. Bladder area under the PC line was significantly increased between supine and standing positions only among subjects with cystocele (p < 0.01), and significantly larger among the study group in the standing position (p < 0.005), less significant in the supine position (p = 0.015), and not significant in the sitting position (p = 0.3). MRO imaging allows us to investigate the effects of upright position and weight bearing on the staging of POP. Imaging patients when sitting and standing identified that significant changes occur in the maximal descent of the bladder.

The effect of a patellar brace on patella position using weight bearing magnetic resonance imaging.

s / Osteoarthritis and Cartilage 22 (2014) S7–S56 S55 which is consistent with the pattern seen from the logistic regression analysis. In FOA, BMLs in the medial PFJ were more strongly associated with knee pain than were lateral PFJ BMLs, while neither compartment individually were associated with pain when defined by cartilage loss (Table 1). Similar results were observed when using WORMS >1 for BMLs and when removing knees with TFJ damage. Conclusions: Pain was commonly reported in knees with either medial or lateral PFJ structural damage. Yet, despite the high prevalence of potentially pain-producing full-thickness cartilage loss and BMLs in the medial PFJ, knee painwasmost prevalent andmost severe among knees with damage that was either isolated to or inclusive of the lateral PFJ. These findings have implications for treatments that seek to reduce knee pain by altering load distribution over the medial and lateral PFJ. 83 THE EFFECT OF A PATELLAR BRACE ON PATELLA POSITION USING WEIGHT BEARING MAGNETIC RESONANCE IMAGING. M.J. Callaghan y, H. Guney y, D. Bailey z, N. Reeves x, K. Kosolovska x, K. Maganaris x, A. Ireland x, R. Hodgson y, D.T. Felson ky. y The Univ. of Manchester, Manchester, United Kingdom; z The Univ. of Warwick, Coventry, United Kingdom; xManchester Metropolitan Univ., Manchester, United Kingdom; kBoston Univ., Boston, MA, USA Purpose: Isolated patellofemoral OA (PFOA) is associated with pain, stiffness and functional limitation. Non-surgical treatments for isolated PFOA include a PF brace which has been successful in clinical trials treating symptomatic PFOA. One of the proposed reasons for clinical success is that the brace may alter the position of the patella relative to the trochlear groove during weight bearing activities but this has not been examined in vivo. Weight bearing magnetic resonance images (MRIs) may give a more valid view of patellofemoral congruence and position under natural loads exerted by body mass. The purpose of this study was, using weight bearing MRIs to assess whether a patellar brace altered patellar position and alignment. The hypothesis was that there would be differences in patellar position when the brace was applied compared to no brace. Methods: Subjects age 40-70 years old with knee pain were included if they had a radiographic K-L score grade 2 or 3 in the PFJ which was greater than K-L score for the tibiofemoral compartments. Subjects had symptomatic PFJOA defined as pain with stair climbing, kneeling, prolonged sitting or squatting and tenderness over lateral or medial patellar facet on palpation or a positive patellar compression test. Figure 1. Measurement of patellar separation: Area A/ Length B measured on axial slicewhere patellar separation smallest. Thismeasures the distance between the bone of the lateral patellar facet and the bone of the femur.

Lateral Patellar Translation Effects after Arthroscopic Partial Meniscectomy of Torn Discoid Lateral Meniscus

To investigate the effects of arthroscopic partial meniscectomy of torn discoid lateral meniscus on patellar tracking. In all, 112 patients (112 knees) who underwent arthroscopic partial meniscectomy participated in the study. All subjects were examined with standing weight-bearing magnetic resonance imaging (MRI) preoperatively and one month postoperation. Axial-plane images through the maximum width of the patella and the maximum dorsal area of the femoral condyles were superimposed and the bisect offset index used to quantify patellar translation. Differences between pre- and postoperation in the bisect offset indexes were calculated and compared by Student's paired t-test. P < 0.05 was considered statistically significant. Before surgery, the mean bisect offset index was 0.574 (0.437-0.692). One month postoperation, the mean bisect offset index was 0.622 (0.510-0.801). The postoperation bisect offset index increased by an average of 0.048 (-0.018 to 0.129) compared with the preoperation value; this difference is statistically significant result (t = 18.33, P < 0.01). After arthroscopic partial meniscectomy, the patella translates more lateral to the femoral trochlear groove. These results suggest that arthroscopic partial meniscectomy may result in patellar maltracking.

External pneumatic compression device prevents fainting in standing weight-bearing MRI: a cohort study

To investigate if a peristaltic external pneumatic compression device attached to the legs, while scanning, can reduce a substantial risk of fainting in standing weight-bearing magnetic resonance imaging (MRI). This study comprised all patients with low back pain referred to standing MRI of the lumbar spine, using a 0.25-T open G-Scanner, from June 2011 to April 2012. The standing MRI protocol included a sagittal TSE T2w and an axial GRE T2w sequence giving a total scan time of 17min. The first patients were scanned standing without a device (control group), and then from January to April 2012 the patients were scanned in the standing position using an external pneumatic compression device, attached to the legs (experimental group). One hundred and forty-nine patients (mean age 42.5, standard deviation 12.5, and range 20-77years) were included and scanned standing. No significant difference in age (p = 0.51) or gender (p = 0.47) was observed between the control group (n = 86) and the experimental group (n = 63). Sixteen patients (19%) fainted in the control group during the standing MRI scan, compared to one patient (2%) in the experimental group where the pneumatic compression device was applied. The difference between groups was highly significant (p = 0.001; Fisher's exact test), with an OR = 0.071 (exact 95%CI: 0.002 to 0.486) for the pneumatic compression device. A substantial risk of fainting during standing MRI was almost eliminated by using an external peristaltic pneumatic compression device.

Patellar tilt correlates with vastus lateralis: Vastus medialis activation ratio in maltracking patellofemoral pain patients

Patellofemoral (PF) pain is a common ailment of the lower extremity. A theorized cause for pain is patellar maltracking due to vasti muscle activation imbalance, represented as large vastus lateralis:vastus medialis (VL:VM) activation ratios. However, evidence relating vasti muscle activation imbalance to patellar maltracking is limited. The purpose of this study was to investigate the relationship between VL:VM activation ratio and patellar tracking measures, patellar tilt and bisect offset, in PF pain subjects and pain-free controls. We evaluated VL:VM activation ratio and VM activation delay relative to VL activation in 39 PF pain subjects and 15 pain-free controls during walking. We classified the PF pain subjects into normal tracking and maltracking groups based on patellar tilt and bisect offset measured from weight-bearing magnetic resonance imaging. Patellar tilt correlated with VL:VM activation ratio only in PF pain subjects classified as maltrackers. This suggests that a clinical intervention targeting vasti muscle activation imbalance may be effective only in PF pain subjects classified as maltrackers.