Aims

Symptomatic spinal stenosis is a very common problem, and decompression surgery has been shown to be superior to nonoperative treatment in selected patient groups. However, performing an instrumented fusion in addition to decompression may avoid revision and improve outcomes. The aim of the SpInOuT feasibility study was to establish whether a definitive randomized controlled trial (RCT) that accounted for the spectrum of pathology contributing to spinal stenosis, including pelvic incidence-lumbar lordosis (PI-LL) mismatch and mobile spondylolisthesis, could be conducted.

Aims

Cam and pincer morphologies are potential precursors to hip osteoarthritis and important contributors to non-arthritic hip pain. However, only some hips with these pathomorphologies develop symptoms and joint degeneration, and it is not clear why. Anterior impingement between the femoral head-neck contour and acetabular rim in positions of hip flexion combined with rotation is a proposed pathomechanism in these hips, but this has not been studied in active postures. Our aim was to assess the anterior impingement pathomechanism in both active and passive postures with high hip flexion that are thought to provoke impingement.

Aims. Anterior cruciate ligament (ACL) rupture commonly leads to post-traumatic osteoarthritis, regardless of surgical reconstruction. This study uses standing MRI to investigate changes in contact area, contact centroid location, and tibiofemoral alignment between ACL-injured knees and healthy controls, to examine the effect of ACL reconstruction on these parameters. Methods. An upright, open MRI was used to directly measure tibiofemoral contact area, centroid location, and alignment in 18 individuals with unilateral ACL rupture within the last five years. Eight participants had been treated nonoperatively and ten had ACL reconstruction performed within one year of injury. All participants were high-functioning and had returned to sport or recreational activities. Healthy contralateral knees served as controls. Participants were imaged in a standing posture with knees fully extended. Results. Participants’ mean age was 28.4 years (SD 7.3), the mean time since injury was 2.7 years (SD 1.6), and the mean International Knee Documentation Subjective Knee Form score was 84.4 (SD 13.5). ACL injury was associated with a 10% increase (p = 0.001) in contact area, controlling for compartment, sex, posture, age, body mass, and time since injury. ACL injury was associated with a 5.2% more posteriorly translated medial centroid (p = 0.001), equivalent to a 2.6 mm posterior translation on a representative tibia with mean posteroanterior width of 49.4 mm. Relative to the femur, the tibiae of ACL ruptured knees were 2.3 mm more anteriorly translated (p = 0.003) and 2.6° less externally rotated (p = 0.010) than healthy controls. ACL reconstruction was not associated with an improvement in any measure. Conclusion. ACL rupture was associated with an increased contact area, posteriorly translated medial centroid, anterior tibial translation, and reduced tibial external rotation in full extension. These changes were present 2.7 years post-injury regardless of ACL reconstruction status. Cite this article: Bone Joint J 2021;103-B(9):1505–1513

Femoroacetabular impingement (FAI) deformities are a potential precursor to hip osteoarthritis and an important contributor to non-arthritic hip pain. Some hips with FAI deformities develop symptoms of pain in the hip and groin that are primarily position related. The reason for pain generation in these hips is unclear. Understanding potential impingement mechanisms in FAI hips will help us understand pain generation. Impingement between the femoral head-neck contour and acetabular rim has been proposed as a pathomechanism in FAI hips. This proposed pathomechanism has not been quantified with direct measurements in physiological postures. Research question: Is femoroacetabular clearance different in symptomatic FAI hips compared to asymptomatic FAI and control hips in sitting flexion, adduction, and internal rotation (FADIR) and squatting postures?. We recruited 33 participants: 9 with symptomatic FAI, 13 with asymptomatic FAI, and 11 controls from the Investigation of Mobility, Physical Activity, and Knowledge Translation in Hip Pain (IMAKT-HIP) cohort. We scanned each participant's study hip in sitting FADIR and squatting postures using an upright open MRI scanner (MROpen, Paramed, Genoa, Italy). We quantified femoroacetabular clearance in sitting FADIR and squatting using beta angle measurements which have been shown to be a reliable surrogate for acetabular rim pressures. We chose sitting FADIR and squatting because they represent, respectively, passive and active maneuvers that involve high flexion combined with internal/external rotation and adduction/abduction, which are thought to provoke impingement. In the squatting posture, the symptomatic FAI group had a significantly smaller minimum beta angle (−4.6º±15.2º) than the asymptomatic FAI (12.5º ±13.2º) (P= 0.018) and control groups (19.8º ±8.6º) (P=0.001). In the sitting FADIR posture, both symptomatic and asymptomatic FAI groups had significantly smaller beta angles (−9.3º ±14º [P=0.010] and −3.9º ±9.7º [P=0.028], respectively) than the control group (5.7º ±5.7º). Our results show loss of clearance between the femoral head-neck contour and acetabular rim (negative beta angle) occurred in symptomatic FAI hips in sitting FADIR and squatting. We did not observe loss of clearance in the asymptomatic FAI group for squatting, while we did observe loss of clearance for this group in sitting FADIR. These differences may be due to accommodation mechanisms in the active, squatting posture that are not present in the passive, sitting FADIR posture. Our results support the hypothesis that impingement between the femoral head-neck contour and acetabular rim is a pathomechanism in FAI hips leading to pain generation

It is unclear why ACL rupture increases osteoarthritis risk, regardless of ACL reconstruction. Our aims were: 1) to establish the reliability and accuracy of a direct method of determining tibiofemoral contact in vivo with UO-MRI, 2) to assess differences in knees with ACL rupture treated nonoperatively versus operatively, and 3) to assess differences in knees with ACL rupture versus healthy knees.

We recruited a convenience sample of patients with prior ACL rupture. Inclusion criteria were: 1) adult participants between 18–50 years old; 2) unilateral, isolated ACL rupture within the last five years; 3) if reconstructed, done within one year from injury; 4) intact cartilage; and 5) completed a graduated rehabilitation program culminating in return to sport or recreational activities. Participants were excluded if they had other ligament ruptures, osteoarthritis, an incompletely rehabilitated injury, were prohibited from undergoing MRI, or had a history of ACL re-rupture. Using the UO-MRI, we investigated tibiofemoral contact area, centroid location, and six degrees of freedom alignment under standing, weightbearing conditions with knees extended. We compared patients with ACL rupture treated nonoperatively versus operatively, and ACL ruptured knees versus healthy control knees. We assessed reliability using the intra-class correlation coefficient, and accuracy by comparing UO-MRI contact area with a 7Tesla MRI reference standard. We used linear mixed-effects models to test the effects of ACL rupture and ACL reconstruction on contact area. We used a paired t test for centroid location and alignment differences in ACL ruptured knees versus control knees, and the independent t test for differences between ACL reconstruction and no reconstruction. Analyses were performed using R version 3.5.1. We calculated sample size based on a previous study that showed a contact area standard deviation of 13.6mm2, therefore we needed eight or more knees per group to detect a minimum contact area change of 20mm2with 80% power and an α of 0.05.

We recruited 18 participants with ACL rupture: eight treated conservatively and 10 treated with ACL reconstruction. There were no significant differences between the operative and nonoperative ACL groups in terms of age, gender, BMI, time since injury, or functional knee scores (IKDC and KOOS). The UO-MRI demonstrated excellent inter-rater, test-retest, and intra-rater reliability with ICCs for contact area and centroid location ranging from 0.83–1.00. Contact area measurement was accurate to within 5% measurement error. At a mean 2.7 years after injury, we found that ACL rupture was associated with a 10.4% larger medial and lateral compartment contact areas (P=0.001), with the medial centroid located 5.2% more posterior (P=0.001). The tibiae of ACL ruptured knees were 2.3mm more anterior (P=0.003), and 2.6° less externally rotated (P=0.010) relative to the femur, than contralateral control knees. We found no differences between ACL reconstructed and nonreconstructed knees.

ACL rupture was associated with significant mechanical changes 2.7 years out from injury, which ACL reconstruction did not restore. These findings may partially explain the equivalent risk of post-traumatic osteoarthritis in patients treated operatively and nonoperatively after ACL rupture.

Aims. Though the pathogenesis of Legg-Calve-Perthes disease (LCPD) is unknown, repetitive microtrauma resulting in deformity has been postulated. The purpose of this study is to trial a novel upright MRI scanner, to determine whether any deformation occurs in femoral heads affected by LCPD with weightbearing. Methods. Children affected by LCPD were recruited for analysis. Children received both standing weightbearing and supine scans in the MROpen upright MRI scanner, for coronal T1 GFE sequences, both hips in field of view. Parameters of femoral head height, width, and lateral extrusion of affected and unaffected hips were assessed by two independent raters, repeated at a one month interval. Inter- and intraclass correlation coefficients were determined. Standing and supine measurements were compared for each femoral head. Results. Following rigorous protocol development in healthy age-matched volunteers, successful scanning was performed in 11 LCPD-affected hips in nine children, with seven unaffected hips therefore available for comparison. Five hips were in early stage (1 and 2) and six were in late stage (3 and 4). The mean age was 5.3 years. All hips in early-stage LCPD demonstrated dynamic deformity on weightbearing. Femoral head height decreased (mean 1.2 mm, 12.4% decrease), width increased (mean 2.5 mm, 7.2% increase), and lateral extrusion increased (median 2.5 mm, 23% increase) on standing weightbearing MRI compared to supine scans. Negligible deformation was observed in contra-lateral unaffected hips, with less deformation observed in late-stage hips. Inter- and intraclass reliability for all measured parameters was good to excellent. Conclusion. This pilot study has described an effective novel research investigation for children with LCPD. Femoral heads in early-stage LCPD demonstrated dynamic deformity on weightbearing not previously seen, while unaffected hips did not. Expansion of this protocol will allow further translational study into the effects of loading hips with LCPD. Cite this article: Bone Joint Open 2020;1-7:364–369

Cam-type femoroacetabular impingement (cam-FAI) can be treated with femoral neck osteochondroplasty to increase the clearance between the femoral head/neck and the acetabular rim. Because femur-acetabulum contact is very difficult to assess directly in patients, it is not clear if this surgery achieves its objective of reducing femur-acetabulum contact, and it is not clear how much of the femoral head/neck region should be resected to allow clearance in all activities. Our research question was: “Does femoral neck osteochondroplasty increase femur-acetabulum clearance in an extreme hip posture in patients with cam FAI?”. We recruited 8 consecutive patients scheduled to undergo arthroscopic femoral neck osteochondroplasty to treat cam-type FAI. We assessed clearance between the acetabulum and the femoral neck before surgery and at 6 months post-op using an upright open MRI scanner that allowed the hip to be scanned in flexed postures. We scanned each subject in a supine hip flexion (90 degree), adduction and internal rotation (FADIR) posture. We measured the beta angle, which describes clearance between the acetabular rim and the femoral head/neck deformity. Osteochondroplasty increased clearance from a mean beta angle of −9.4 degrees (SD 19.3) to 4.4 degrees (SD 16.2°) (p<0.05). This finding suggests that femoral neck osteochondroplasty increases femur-acetabulum clearance substantially for a posture widely accepted to provoke symptoms in patients with cam-FAI

This pilot study aims to investigate the utility and feasibility of a unique upright MR scan for imaging hips affected by Legg-Calve-Perthes Disease (LCPD) with patient standing up, in comparison to the standard supine scans. Protocol development using this unique upright MRI included healthy adult and child volunteers. Optimum patient positioning in a comparable way between supine to standing was assessed. The balance between shorter scan time (to what a child can tolerate) and longer scan time (for better image acquisition). The study protocol has begun in 2 children with LCPD. Patient recruitment continues. Early results indicate a dynamic deformity of the femoral head in early stage LCP disease. Femoral epiphysis height decreased on standing (7.8 to 6.8mm), width increased on standing (16.6 to 20.9mm) and lateral extrusion increased (3.5 to 4.1mm). Overall epiphyseal shape changed from trapezoidal (LCP femoral head when supine) to flattened triangular (LCP femoral head when standing). Differences were thus demonstrated in all parameters of bony epiphyseal height, width, extrusion and shape of a femoral head with LCP Disease when the child stood and loaded the affected hip. Satisfactory image acquisition was possible with Coronal T1 GFE sequences, with both hips in the Field of View. 2.5min scans were performed with the child standing first, then supine. Hip position was comparable when standing and supine. Longer scans were not tolerated by younger children, more so those with LCP disease. To our knowledge this is the first reported use of standing MRI in LCPD. A dynamic deformity has been demonstrated, with flattening, widening and worsened lateral extrusion when the child is standing compared to supine. This proof of concept investigation demonstrates the feasibility of upright MRI scanning and may demonstrate previously undetected deformity

Purpose and Background:. The spread of upright MRi scanning is a relatively new development in the UK. However, there is a lack of information about whether weight bearing scans confer any additional useful information for low back conditions. Methods and Results:. Forty-five patient referrals to the upright MRI Department at the AECC for weight bearing lumbar spine scans between November 1. st. 2014 and June 30. th. 2015, and the resulting radiologists' reports were reviewed. Age, gender, clinical history, summary of findings, type of weight bearing scanning performed (sitting, standing, flexion, extension) were abstracted. All patients were scanned in a 0.5T Paramed MRopen scanner and all also received supine lumbar spine sagittal and axial scans. The patients comprised 18 females and 27 males, mean age 52 years, (SD 15.5). Thirty had leg pain, 6 of which was bilateral. In 15, a stenotic lesion was suspected. Other reasons for referral were; possible malignancy (1), effects of degenerative change (4), spondylolisthesis (2), fracture, (1), previous surgery (3), trauma (1), sacroiliitis (1) and instability (3). In 12/45 cases, reportable findings were more prominent, and sometimes only identifiable, on weight bearing scans, while in a further 4, the reverse was true. All but one of these involved disruption of the spinal or root canals. Eight of them also involved positional alignment. Conclusion:. In this case series nearly a third of referred patients had reportable findings relating to the spinal or nerve root canals that were differentiated by upright MRI scans

Purpose. to evaluate the kinematics of a knee with a polyurethane meniscal scaffold for partial meniscus defect substitution during flexion under weightbearing conditions in an upright MRI. In addition, radial displacement and the surface of the scaffold was compared to the normal meniscus. Materials and Methods. One cadaver with a normal lateral meniscus and medial scaffold in the left knee and with a normal medial meniscus and lateral scaffold in the right knee. The scaffolds were implanted to substitute a 3 cm meniscus defect in the posterior horn. The cadaver was scanned in an 0,7T open MRI with a range of motion from 0-30-60-90 to hyperflexion. Kinematics were evaluated on sagittal images by the following two parameters: the position of the femoral condyle, identified by the centre of its posterior circular surface, which is named the flexion facet centre (FFC), and the point of closest approximation between the femoral and tibial subchondral plates, the contact point (CP). Both were identified in relation to the posterior tibial cortex. The displacement, measured on coronal images, is defined as the distance between the tibial plateau and the outer edge of the meniscus. The surface was also measured on coronal slices and contains the triangular surface of the meniscus. Results. Medially from 0 degrees to hyperflexion the FFC does not move anteroposteriorly. Laterally the FFC moves 12 mm backwards. The CP moves 15 mm backwards both lateral and medial. The lateral femoral condyle does roll-back with flexion but the medial does not, so the femur rotates externally around a medial centre. By contrast, both medial and lateral contact points move back, roughly in parallel, from 0 degrees to hyperflexion. The kinematics of the involved compartment is not influenced by the presence of the scaffold compared to the controlateral normal compartment. The radial displacement remains stable during full flexion: both the normal and scaffold meniscus have no different (p > 0,05) position. Both for the normal and the scaffold meniscus there is no difference (p > 0,05) in surface; there is no compression of the meniscus during flexion. Conclusion. The polyurethane implant, indicated for partial meniscus defect substitution, has no effect on the normal kinematics of the knee. Additionally, the degree of flexion has no effect on the external displacement, the surface and compressibility of both the implanted scaffold and the meniscus

Abnormal knee kinematics following reconstruction of the anterior cruciate ligament may exist despite an apparent resolution of tibial laxity and functional benefit. We performed upright, weight-bearing MR scans of both knees in the sagittal plane at different angles of flexion to determine the kinematics of the knee following unilateral reconstruction (n = 12). The uninjured knee acted as a control. Scans were performed pre-operatively and at three and six months post-operatively. Anteroposterior tibial laxity was determined using an arthrometer and patient function by validated questionnaires before and after reconstruction. In all the knees with deficient anterior cruciate ligaments, the tibial plateau was displaced anteriorly and internally rotated relative to the femur when compared with the control contralateral knee, particularly in extension and early flexion (mean lateral compartment displacement: extension 7.9 mm (sd 4.8), p = 0.002 and 30° flexion 5.1 mm (sd 3.6), p = 0.004). In all ten patients underwent post-operative scans. Reconstruction reduced the subluxation of the lateral tibial plateau at three months, with resolution of anterior displacement in early flexion, but not in extension (p = 0.015). At six months, the reconstructed knee again showed anterior subluxation in both the lateral (mean: extension 4.2 mm (sd 4.2), p = 0.021 and 30° flexion 3.2 mm (sd 3.3), p = 0.024) and medial compartments (extension, p = 0.049).

Our results show that despite improvement in laxity and functional benefit, abnormal knee kinematics remain at six months and actually deteriorate from three to six months following reconstruction of the anterior cruciate ligament.

Background and purpose of study: Intervertebral disc height loss is associated with decreased spinal stability and increased loading on spinal structures, which may be a source of back pain. In the past, total stature change, measured using stadiometry, has often been used as an indication of disc height loss and as an index of the load on the spine. The aim of this study was to use an upright MRI scanner to investigate the changes in lumbar disc dimensions following a short-term loading protocol. It was hypothesized that there would be a linear relationship between the loss in total lumbar disc height and a measure of stature change obtained from a stadiometer. Method and Results: Thirteen participants with no history of low back pain were recruited. Stadiometer measurements and MRI images of the lumbar spine were obtained both before and after 15-minutes of walking wearing a weighted vest. Contrary to the original hypothesis, no correlation (r = 0.32) was found between total disc height loss measured via MRI and via stadiometry. However a correlation (r = 0.54) was found between stature loss measured on the stadiometer and the decrease in posterior spine length. Conclusion: The results suggest that stadiometry should not be used to quantify the change in individual disc height or individual disc compression force. However, the correlation with the composite measure of spinal length does offer support to the use of stadiometry to assess the overall effect of loading

Purpose: To evaluate the changes in lumbar spine kinematics and clinical outcomes of patients with spinal stenosis 2 years after implantation of the X Stop interspinous decompression device. Methods: 10 patients (6 males; 4 females) underwent X Stop procedure. Age ranged from 57 years to 71 years. 15 levels were operated (5 single levels: L. 2-3. - 1, L. 4-5. - 4; 5 double levels: L. 3-4. +L. 4-5. – 4; L. 4-5. +L. 5. S. 1. – 1). A 0.6 Tesla Upright MRI scanner was used to acquire images in seated (flexion, extension, and neutral) and erect postures at preoperative, 6 months, and 2 years after surgery. The total range of motion of the lumbar spine and the operated segments were measured, along with changes in disc height, areas of the exit foramens, and dural sac. Clinical outcomes were assessed by Zurich Claudication Questionnaire before and 3, 6, 12, and 24 months after surgery. Results: Mean Zurich Claudication Scores (n=10). At 6 months, there was a significant increase in the spinal canal and foraminal dimension. However at 2 years there was a reduction in these dimensions such that there was no significant difference from the preop-erative measurements. Conclusion: The results of this prospective observational study indicate that X Stop offers significant short-term improvement. It is a safe, effective, and less invasive alternative for treatment of lumbar spinal stenosis. The maximum clinical benefit and mechanical efficacy seems to be realized in the early stages postoperatively with gradual reduction thereafter over 2 years. Co-existing co-morbidities such as obesity and osteoarthritis in the lower limbs may influence the clinical results

Purpose: To measure the effect of the X-Stop interspinous distraction device on spinal canal, exit foramina, and disc height dimensions at the operated level; and adjacent segment endplate angle, and lumbar spine movement in patients with symptomatic lumbar spinal stenosis using upright MRI. Methods /Results: 14 patients (9 M;5 F) were scanned before and six months after operation. Age ranged from 57 to 88 years. All had symptomatic lumbar spinal stenosis- single level- 9 (L2/3-1; L3/4-1; L4/5-7); double level 5 (L3/4, L4/5). Images were taken in sitting flexed, extended, neutral, and standing. The total range of motion of the lumbar spine and of the individual segments were measured, along with changes in disc height, areas of the exit foramina, and dural sac. The mean area of the dural sac at the operated levels increased from 62.46mm2 to 77.69mm2 (p=0.004) in the standing posture and from 70.85mm2 to 94.62mm2 (p=0.019) in extension postoperatively. The area of the exit foramina in extension increased from 83.57mm2 to 107.88mm2 (p=0.002) on the left side and from 83.77mm2 to 108.69mm2 (p=0.012) on the right. The overall changes in the range of movement of the individual segments or of the lumbar spine were statistically insignificant. Conclusions: This is the first study carried out using an upright MRI scanner in patients with lumbar spinal stenosis. The X-Stop device increases the cross-sectional area of the spinal canal and exit foramina by distracting the spinous processes of the operated level without significantly affecting overall posture of the lumbar spine