Medial Shift Research Articles

Robot-aided in vitro measurement of patellar stability with consideration to the influence of muscle loading.

BackgroundAnterior knee pain is often associated with patellar maltracking and instability. However, objective measurement of patellar stability under clinical and experimental conditions is difficult, and muscular activity influences the results. In the present study, a new experimental setting for in vitro measurement of patellar stability was developed and the mediolateral force–displacement behavior of the native knee analyzed with special emphasis on patellar tilt and muscle loading.MethodsIn the new experimental setup, two established testing methods were combined: an upright knee simulator for positioning and loading of the knee specimens, and an industry robot for mediolateral patellar displacement. A minimally invasive coupling and force control mechanism enabled unconstrained motion of the patella as well as measurement of patellar motion in all six degrees of freedom via an external ultrasonic motion-tracking system. Lateral and medial patellar displacement were measured on seven fresh-frozen human knee specimens in six flexion angles with varying muscle force levels, muscle force distributions, and displacement forces.ResultsSubstantial repeatability was achieved for patellar shift (ICC(3,1) = 0.67) and tilt (ICC(3,1) = 0.75). Patellar lateral and medial shift decreased slightly with increasing flexion angle. Additional measurement of patellar tilt provided interesting insights into the different displacement mechanisms in lateral and medial directions. For lateral displacement, the patella tilted in the same (lateral) direction, and tilted in the opposite direction (again laterally) for medial displacement. With regard to asymmetric muscle loading, a significant influence (p < 0.03, up to 5 mm shift and 8° tilt) was found for lateral displacement and a reasonable relationship between muscle and patellar force, whereas no effect was visible in the medial direction.ConclusionThe developed experimental setup delivered reproducible results and was found to be an excellent testing method for the in vitro analysis of patellar stability and future investigation of surgical techniques for patellar stabilization and total knee arthroplasty. We demonstrated a significant influence of asymmetric quadriceps loading on patellar stability. In particular, increased force application on the vastus lateralis muscle led to a clear increase of lateral patellar displacement.

Nail–medullary canal ratio affects mechanical axis deviation during femoral lengthening with an intramedullary distractor

IntroductionCallus distraction of the femur using an intramedullary distractor has several advantages over the use of external fixators. However, difficulty in controlling the mechanical axis during lengthening may cause deformities and knee osteoarthritis. Purpose of the study is to answer the following questions: (1) is lengthening with an intramedullary device associated with a medial or lateral shift of the mechanical axis? (2) Which factors are associated with varisation/valgisation of the mechanical axis during lengthening? Materials and methodsWe analysed pre-treatment and post-treatment radiographs from 20 patients who underwent unilateral femoral-lengthening procedures using intramedullary distractors. Patients with acute correction of pre-existing deformities or combined ipsilateral femoral and tibial lengthening were excluded. Mechanical axis deviations, osteotomy level, and nail–medullary canal ratio were recorded. ResultsCompared to the preoperative axis, the mechanical axis shifted medially in 7 patients (varisation group) and laterally in 13 patients (valgisation group). The groups did not significantly differ regarding preoperative leg length discrepancy (LLD), mechanical axis alignment, LLD-cause and implants used. The nail–medullary canal ratio significantly differed between groups (p<0.001), being <85% in the varisation group and >85% in the valgisation group. The distance between the lesser trochanter and the osteotomy site was significantly longer in the valgisation group (58.9±16.3mm, middle third of the femur) compared to the varisation group (40.6±11.4mm, proximal third of the femur; p=0.02). ConclusionThe nail–medullary canal ratio should be considered during preoperative planning. To avoid a varisation effect—for example, in cases with pre-existing varus alignment—it would be advisable to perform an osteotomy at the middle third of the femur with implantation of a nail that fully covers the medullary canal at the osteotomy site. Level of evidenceLevel IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

The effect of tonic contraction of the finger muscle on the motor cortical representation of the contracting adjacent muscle

This study examined the effect of tonic contraction of the finger muscle on the motor cortical representation of the contracting adjacent muscle. A representation map of the motor evoked potential (MEP) in the first dorsal interosseous (FDI) and abductor digiti minimi (ADM) muscles was obtained with the subject at rest or during tonic contraction of the ADM muscle while the FDI muscle was tonically contracted. The center of gravity (COG) of the MEP map in the FDI muscle shifted medially during contraction of the ADM muscle. Motor cortical excitability in the motor cortical representation of the FDI muscle that did not overlap with the motor cortical representation of the ADM muscle was suppressed, but motor cortical excitability in the motor cortical representation of the FDI muscle overlapping with the motor cortical representation of the ADM muscle was not suppressed during contraction of the ADM muscle. The motor cortical representation of the FDI muscle not overlapping with the motor cortical representation of the ADM muscle was located lateral to that of the FDI muscle that did overlap with the motor cortical representation of the ADM muscle. Medial shift of the COG of the motor cortical representation of the contracting finger muscle induced by tonic contraction of the adjacent finger muscle must be due to suppression of motor cortical excitability in the lateral part of the representation, which is not shared by the adjacent representation.

Comparison of Two Taping Techniques on Navicular Drop and Center-of-Pressure Measurements During Stance

This study examined the eff ectiveness of an antipronation spiral stirrup (APSS) taping technique, compared with the augmented low-Dye (ALD) technique, in controlling navicular drop (ND) and producing a lateral shift in the center-of-pressure (COP) line during the stance phase of gait. Twenty college volunteers participated in a crossover design, testing 2 taping techniques across 3 conditions. Repeated measures analysis of variance revealed that the APSS technique produced signifi cantly less ND, compared with the ALD technique, at the pre(P .05) and postexercise (P .05) conditions. The APSS technique produced signifi cantly less ND than the barefoot condition at preand postexercise (P .01) conditions. A signifi cant (P .05) lateral shift in COP was noted between 30% and 90% of the stance phase in the tape reexercise condition in the APSS technique. The APSS technique seems to be eff ective at controlling ND and preventing a medial shift of the COP during the deceleration phase of foot pronation. [Athletic Training & Sports Health Care. 2014;6(6):252-260.] Overuse lower-leg injuries, although often of uncertain etiology, are frequently affected by anatomical, mechanical, training intensity, volume, and injury type factors.1,2 The catch-all term shin splints has been used to describe a variety of conditions, including compartment syndrome, periostitis, stress fractures, nerve entrapment syndrome, and various tendinopathies.3,4 More recently, the shin splints term has been used interchangeably with an equally ambiguous, but more medically descriptive phrase, medial–tibial stress syndrome (MTSS).5 This syndrome is characterized by exercise-induced pain along the posteromedial border of the tibia, is not attributed to compartment syndrome or stress fracture,6,7 and is of idiopathic origins. A common link of these varied pathologies with abnormalities in foot position is an increased drop in the location of the navicular bone. This drop, resulting in a “fallen arch,”8 is often referred to as pes planus. In a pes planus foot, the center of pressure (COP) is deviated more medially during gait than in those with a neutrally aligned foot.9-12 Williams et al13 found that low-arched individuals have a more medial COP than those with high arches, allowing the possibility that COP may be useful in detecting changes in foot orientation throughout the stance phase of gait (heel strike through toe-off).9-13 In addition, pes planus feet have been associated with tibialis posterior dysfunction.14,15 One of the primary functions of the tibialis posterior is to contract eccentrically throughout the deceleration phase of foot pronation.16 If the tibialis posterior is dysfunctional, it cannot effectively control the force that must be transferred from the foot to the lower leg, leading to its inability to control the “falling” of the arch. This hyperpronation during gait can result in lower-leg pain,3 which supports the theory that suggests that foot overpronation, attributable to tibialis posterior muscle dysfunction, is a possible cause of MTSS.7 Several researchers13,14 have studied the effectiveness of taping or use of custom shoe inserts as an effort to control navicular drop (ND). Orthotic inserts have proven to be Ms Prusak from Maple Mountain High School, Spanish Fork; and Dr Prusak is from the Department of Teacher Education, and Dr Hunter, Dr Seeley, and Dr Hopkins are from the Department of Exercise Sciences, Brigham Young University, Provo, Utah. Received: December 9, 2013 Accepted: November 12, 2014 Posted Online: December 3, 2014 The authors acknowledge the contributions of Devin Francom, MS (Brigham Young University), for his creative use of functional statistical analyses and cubic smoothing splines, allowing for the examination of changes in the center-of-

Neurophysiological features of motor cortex excitability and plasticity in Subcortical Ischemic Vascular Dementia: A TMS mapping study

ObjectiveTo evaluate neurophysiological features of M1 excitability and plasticity in Subcortical Ischemic Vascular Dementia (SIVD), by means of a TMS mapping study. MethodsSeven SIVD and nine AD patients, along with nine control subjects were tested. The M1 excitability was studied by resting thresholds, area and volume of active cortical sites for forearm and hand’s examined muscles. For M1 plasticity, coordinates of the hot-spot and the center of gravity (CoG) were evaluated. The correlation between the degree of hyperexcitability and the amount of M1 plastic rearrangement was also calculated. ResultsMultivariate analysis of excitability measures demonstrated similarly enhanced cortical excitability in AD and SIVD patients with respect to controls. SIVD patients showed a medial and frontal shift of CoG from the hot-spot, not statistically different from that observed in AD. A significant direct correlation was seen between parameters related to cortical excitability and those related to cortical plasticity. ConclusionsThe results suggest the existence of common compensatory mechanisms in different kind of dementing diseases supporting the idea that cortical hyperexcitability can promote cortical plasticity. SignificanceThis study characterizes neurophysiological features of motor cortex excitability and plasticity in SIVD, providing new insights on the correlation between cortical excitability and plasticity.

Radiographic analysis of the restoration of hip joint center following open reduction and internal fixation of acetabular fractures: a retrospective cohort study.

BackgroundUnfavorable reduction is considered one of the key factors leading to joint degeneration and compromised clinical outcome in acetabular fracture patients. Besides the columns, walls, and superior dome, the postoperative position of hip joint center (HJC), which is reported to affect hip biomechanics, should be considered during the assessment of quality of reduction. We aimed to evaluate the radiographic restoration of HJC in acetabular fractures treated with open reduction and internal fixation.MethodsPatients with a displaced acetabular fracture that received open reduction and internal fixation in the authors’ institution during the past five years were identified from the trauma database. The horizontal and vertical shifts of HJC were measured in the standard anteroposterior view radiographs taken postoperatively. The radiographic quality of fracture reduction was graded according to Matta’s criteria. The relationships between the shift of HJC and the other variables were evaluated.ResultsTotally 127 patients with 56 elementary and 71 associated-type acetabular fractures were included, wherein the majority showed a medial (89.0%) and proximal (93.7%) shift of HJC postoperatively. An average of 2.8 mm horizontal and 2.2 mm vertical shift of HJC were observed, which correlated significantly with the quality of fracture reduction (P < 0.001 for both). The horizontal shift of HJC correlated with the fracture type (P = 0.022).ConclusionsThe restoration of HJC correlates with the quality of reduction in acetabular fractures following open reduction and internal fixation. Further studies are required to address the effects of HJC shift on the biomechanical changes and clinical outcomes of hip joint, especially in poorly reduced acetabular fractures.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2474-15-277) contains supplementary material, which is available to authorized users.

Do surgical patellar interventions restore patellar kinematics in fixed-bearing, cruciate-retaining total knee arthroplasty?: An in vitro study

Despite different surgical patellar interventions, the decision how to treat the patella during TKA remains controversial. The purpose of this study was to quantify the effect of different reconstructive patellar interventions on patellar kinematics during TKA using optical computer navigation. We implanted ten navigated TKAs in full body specimens. During passive motion, the effect of different surgical patellar interventions on patellar kinematics was analysed. A contrarily tilt behaviour was observed in the TKA group without patellar intervention compared to the natural knee. Lateral release led to similar tilt values (P<0.05). All surgical interventions led to a 3 to 5mm medial shift of the patella (P<0.05). None of the analysed surgical patellar interventions could restore natural patellar kinematics after TKA.

Dynamic analysis of the ulnar nerve in the cubital tunnel using ultrasonography

We investigated the dynamics of the ulnar nerve during elbow flexion and the relationships between these dynamics and the morphology of the ulnar nerve groove in healthy individuals. Twenty healthy volunteers (40 elbows) underwent ultrasonographic examination of the ulnar nerve at the elbow. We measured the breadth and depth of the ulnar nerve groove at 90° of elbow flexion and calculated the depth-to-breadth ratio. We recorded the distance from the trochlea of the humerus to the nerve and the short-axis diameter of the nerve at 30°, 60°, 90°, and 120° of elbow flexion. We calculated the medial shift and flattening of the ulnar nerve at each angle relative to 30° of flexion, compared the values among the different angles, and compared the depth-to-breadth ratio with the location, medial shift, and flattening ratio of the ulnar nerve. The medial shift was significantly greater at 120° than at other angles (P < .001). Flattening increased with increasing elbow flexion and was significantly different at 60°, 90°, and 120° (all P < .001). The flattening ratios were significantly correlated with the depth-to-breadth ratio at 120° (r = -0.43, P = .005). The ulnar nerve moves medially and is flattened with the elbow flexed between 90° and 120°. When the ulnar nerve groove is shallow, high degrees of elbow flexion result in flattening of the ulnar nerve in the groove.

Quantitative stress radiography of the patella and evaluation of patellar laxity before and after lateral release for recurrent dislocation patella

The aims of the present controlled clinical study were to (1) compare patella laxity determined in the outpatient clinic with that in anaesthetized patients and (2) evaluate patella laxity before and after lateral release. The study evaluated data on 33 knees from 33 patients (average age 19.7years) between 2007 and 2011. All patients were diagnosed with recurrent dislocation of the patella. Patellar stability was evaluated in each patient thrice: patellas were first imaged in the outpatient clinic prior to surgery at 45° knee flexion with 20N stress from the medial to lateral side and from the lateral to medial side; then, at the time of surgery, patella stress images were obtained in the same manner before and after the lateral release procedure. Radiological assessments were performed using the medial stress shift ratio (MSSR) and lateral stress shift ratio (LSSR). There were no significant differences in the LSSR and MSSR before surgery (outpatient data) and in anaesthetized patients before the lateral release procedure. Furthermore, there was no significant difference in MSSR at the time of surgery before and after the lateral release procedure. However, LSSR increased significantly after the lateral release procedure. The results of the present study suggest that quantitative patella stress radiography in the outpatient clinic is useful when it comes to investigating laxity of the patella, and that lateral release significantly increases lateral, but not medial, laxity in patients with recurrent patellar dislocation. IV.

Effect of Achilles tendon vibration on posture in children

This study investigated the effect of unilateral Achilles tendon vibration on postural response in children and young adults during standing. Thirty healthy subjects participated in this study including ten 6-year-old children (YC group), ten 10-year-old children (OC group), and ten young adults (YA group). Eight-second vibration was elicited in each trial from a small vibrator attached above the right Achilles tendon when participants stood barefoot on a force platform. Three 40-s trials were collected under both eyes-open and eyes-closed conditions. Center of pressure (COP) was calculated to examine postural response during the pre-vibration, vibration and post-vibration phases. Results show that both the YC and OC groups had a greater COP average velocity than the YA group in all three phases. Tendon vibration induced a directionally specific postural response in all three groups such that the onset of vibration induced a posterior and medial COP shift during the vibration phase, and the offset of vibration induced an anterior and lateral COP shift during the post-vibration phase. Timing of the maximal COP shift was comparable among three groups in both anterior–posterior (AP) and medial–lateral (ML) directions. However, only the OC group showed an adult-like magnitude of the maximal COP shift during the post-vibration phase in the AP direction. These results suggest that 6-year-old children may start showing an adult-like directionally specific response and temporal parameter to tendon vibration during standing; however, the development of an adult-like spatial postural response to tendon vibration may take more than 10 years.

Effectiveness and limitations of reconstruction of the medial patellofemoral ligament using a titanium interference screw in single patellar and femoral bone tunnels

No standard surgical procedure for medial patellofemoral ligament (MPFL) reconstruction exists. The purpose of this study was to evaluate the clinical effectiveness and limitation of the reconstructions of the MPFL in single patellar and femoral bone tunnels. The methods used a hamstring tendon and titanium interference screws in patients with recurrent patellar dislocation. Nineteen knees in 17 patients were studied. Subjects underwent MPFL reconstruction with or without lateral release using interference screws in single patellar and femoral tunnels. Patients were evaluated using preoperative and postoperative physical and radiographic examinations, including apprehension testing, assessment of tilting and congruence angles, medial and lateral shift ratios under stress X-ray imaging, and Kujala and Lysholm scores. Average follow-up was 22 months (12–71 months). None experienced recurrent postoperative episodes of dislocation or subluxation. By the final follow-up, patellar apprehension had disappeared in all patients except for one with generalized joint laxity. In addition, patients showed significant improvement in the following areas: tilting angle (from 14.4 ± 5.6° to 6.4 ± 4.6°, p < 0.0001), congruence angle (0.5 ± 16° to −9.2 ± 6.9°, p < 0.001), lateral shift ratio (23.8 ± 11.3% to 11.6 ± 13.4%, p < 0.001), Kujala score (74.0 ± 7.8 points to 95.7 ± 4.4 points, p < 0.0001), and Lysholm score (71.0 ± 10 points to 95.5 ± 5.3 points, p < 0.0001). MPFL reconstruction methods, using titanium interference screws in single patellar and femoral tunnels provide acceptable short-term results for the treatment of recurrent patellar dislocations.

Value of Preoperative Analysis Using Three-Dimensional Imaging of Leg Deformity after Injury to the Distal Femoral Epiphysis

Background: Assessment of lower extremity alignment is important. The malalignment test is generally assessed two-dimensionally on plain radiographs. In patients with complex deformities, the key points are set inaccurately on Roentgenogram images, leading to problems with both accuracy and reproducibility. Computed tomography (CT) is the current gold standard for evaluating femoral torsion measurements. However, CT images vary depending on slice orientation during scanning, images of flexion deformities are affected by the orientation of the CT slice, making accurate evaluation impossible should a flexion deformity be present. For this reason, three-dimensional preoperative analysis is required. We report a case in which three-dimensional preoperative analysis was used for a patient with leg deformity after injury to the distal femoral epiphysis, with good results. Methods: CT scanning was used to establish a preoperative plan and produced a surface morphology model from CT axial data. Free software was then used to create mirror images of the affected and unaffected sides from these data. The mirror image of the unaffected side was then positioned in three-dimensional space, and vectors were set. The fragment proximal to the osteotomy plane was defined as the reference fragment (RF) and the distal fragment as the corresponding fragment (CF), with the functional axis of the unaffected side forming the helical axis (HA). The amount of deformity correction of the CF required was then calculated automatically in terms of the two parameters of rotation and translation in three dimensions by shifting the CF along the HA. A Taylor spatial frame (TSF) was used to perform gradual correction surgery. Results: The rotational deformity was corrected, a 20-mm medial shift and 12-mm posterior shift persisted. Correction was carried out a second time to correct this deformity. Conclusion: Three-dimensional analysis of long-bone may prove useful for the correction of long bones deformities in the legs when complex deformity is present.

Evidence-based support for S1 transpedicular screw entry point modification

BackgroundIn the literature, ‘below and lateral to the superior S1 facet’ is defined as the basic technique for screw introduction. Until a recently published modification, no analysis for alternative starting point has been proposed nor evaluated, although some surgeons claim to use some modifications. In this study, we analyse the data from anatomical and radiological studies for optimal starting point in transpedicular S1 screw placement.MethodsA Medline search for key word combination: sacrum, anatomy, pedicle, screws and bone density resulted in 26 publications relevant to the topic. After a review of literature, two articles were chosen, as those including the appropriate set of data. The data retrieved from the articles is used for the analysis. The spatial relation of S1 facet, pedicles and vertebral body with cortical thickness and bone density in normal, osteopenic and osteoporotic sacrum is analysed.ResultsPresented data advocates for more medial placement of the screws due to higher bone density and lower bone loss in osteoporosis. Medial shift of the starting point does not increase the risk of spinal canal perforation. Osteoarthritic changes within the facet can augment the posterior supporting point for screw. The facet angular orientation is similar to convergent screw trajectory.ConclusionsModified technique for S1 screw placement takes advantage of latest anatomical and clinical data. In our opinion, technique modification improves the reproducibility and may increase stability and the screws within the posterior cortex of the S1 vertebra. Further biomechanical and clinical study should be performed to prove its superiority to classical technique.

Arthroscopic Evaluation of Patellofemoral Congruence With Rotation of the Knee Joint and Electrical Stimulation of the Quadriceps

The aim of this study was to investigate the pathoanatomic features of patellar instability by arthroscopically comparing patellofemoral congruence with rotation of the knee joint and/or electrical stimulation of the quadriceps (ESQ) between knees with and without patellar instability. We retrospectively examined 83 knee joints in 83 patients. The joints were classified into 2 groups: group 1 comprised those without a history of patellar dislocation and included 59 patients (25 male and 34 female patients), and group 2 comprised those with a history of patellar dislocation and included 24 patients (9 male and 15 female patients). Evaluation of patellofemoral congruence at 30° of flexion of the knee joint was conducted based on an axial radiograph and arthroscopic findings. The congruence angle was measured on the radiograph. The position of the patellar central ridge (PPCR) on the trochlear groove during arthroscopy was measured using still video frames of knee joints with rotational stress and/or ESQ. Statistical differences in the measurements between the 2 groups were assessed with the unpaired t test and the area under the receiver operating characteristic curve of each measurement. There were significant differences (P < .0001) between the 2 groups in the congruence angle on radiographs and PPCR in knee joints with rotational stress and/or ESQ on arthroscopy. External and internal rotation of the knee joint caused lateral and medial patellar shift, respectively, in both groups, but the shift was significantly larger in group 2. ESQ in addition to rotation caused further patellar shift in group 2 but reduced patellar shift in group 1. Measurement of PPCR with external rotation of the knee and ESQ was the only method to show an area under the receiver operating characteristic curve of 1. There were significant differences in the effects of rotation of the knee joint and/or ESQ on patellofemoral congruence at 30° of flexion of the knee joint on arthroscopy between knees with and without patellar instability. Level III, diagnostic study of nonconsecutive patients.

Impaired executive function following ischemic stroke in the rat medial prefrontal cortex

Small (lacunar) infarcts frequently arise in frontal and midline thalamic regions in the absence of major stroke. Damage to these areas often leads to impairment of executive function likely as a result of interrupting connections of the prefrontal cortex. Thus, patients experience frontal-like symptoms such as impaired ability to shift ongoing behavior and attention. In contrast, executive dysfunction has not been demonstrated in rodent models of stroke, thereby limiting the development of potential therapies for human executive dysfunction. Male Sprague-Dawley rats (n=40) underwent either sham surgery or bilateral endothelin-1 injections in the mediodorsal nucleus of the thalamus or in the medial prefrontal cortex. Executive function was assessed using a rodent attention set shifting test that requires animals to shift attention to stimuli in different stimulus dimensions. Medial prefrontal cortex ischemia impaired attention shift performance between different stimulus dimensions while sparing stimulus discrimination and attention shifts within a stimulus dimension, indicating a selective attention set-shift deficit. Rats with mediodorsal thalamic lacunar damage did not exhibit a cognitive impairment relative to sham controls. The selective attention set shift impairment observed in this study is consistent with clinical data demonstrating selective executive disorders following stroke within specific sub-regions of frontal cortex. These data contribute to the development and validation of a preclinical animal model of executive dysfunction, that can be employed to identify potential therapies for ameloriating cognitive deficits following stroke.

Variation in patellofemoral kinematics due to changes in quadriceps loading configuration during in vitro testing

This study investigated changes in patellofemoral (PF) kinematics for different loading configurations of the quadriceps muscle: single line of action (SL), physiological-based multiple lines of action (ML), weak vastus medialis (WVM), and weak vastus lateralis (WVL). Fourteen cadaveric knees were flexed from 15° to 120° knee flexion using a loading rig with the ability to load different heads of the quadriceps and hamstring muscles in their anatomical orientation. PF rotation in the sagittal plane) and medial lateral translation were significantly different (p<0.05) for SL and ML, with maximum differences of 2.8° and 0.9mm at 15° and 45° knee flexion, respectively. Compared to the ML, the WVM induced an average lateral shift of 1.5mm and an abduction rotation of 0.8°, whereas a 0.9mm medial shift and 0.6° adduction rotation was seen when simulating a WVL. The difference in the sagittal plane resultant force orientation of 26° between SL and ML was the major contributor to the change in PF rotation in the sagittal plane, while the difference in the frontal plane resultant force orientation of both the WVM and WVL from the ML (17° medial and 8° lateral, respectively) were the primary reasons for the change in PF frontal plane rotation and medial lateral translation. The two PF kinematic were significantly different from the ML for WVM and WVL (p<0.05). The results suggest that quadriceps muscle loading configuration can have a large influence on PF kinematics during full extension but less in deeper flexion. Therefore, using quadriceps single line loading for simulating activities with low flexion angles might not be sufficient to accurately replicate the physiological condition.

Medial Patellofemoral Ligament Influence on Patellofemoral Joint Kinematics: An In-Vitro Analysis

Lyon Ortho Clinic, Lyon, France Patellar stability is an important component for a correct kinematic behavior of the knee. Patellofemoral (PF) maltracking can lead to joint disorders associated with pain and mobility alterations. The goal of this work was to study the morphology of the Medial Patellofemoral Ligament (MPFL) and its effect on knee kinematics. Evaluation of patello-femoral joint pathology and efficacy of treatment is challenged by lack of consensus on its kinematics [1]. Specifically damages to the Medial Patello-femoral Ligament (MPFL) has been suggested to be the essential lesion in lateral patellar dislocation [2,3]. While MPFL reconstruction has better results compared to previous procedures, a recent systematic review advocated a greater knowledge of MPFL behavior to prevent alteration of patello-femoral kinematics, joint compression and long term chondral degeneration after reconstruction [4]. The objective of this study was to analyse the morphology of the MPFL and its influence on patello-femoral kinematics with reference to the trochlea. A kinematic study on six cadaveric knees, using a non-image based navigation system, under an axial quadriceps load of 60 N, in MPFL-intact and MPFL-deficient state, with and without a laterally directed load of 25 N at 0°, 30°, 60° and 90°, was performed. The MPFL was isolated from the Medial Menisco-Tibial Ligament, the navigation system was used to define its insertions, four representative fibers and trochlear surface. The MPFL femoral insertion exhibited a high intra-group variability with a mean surface area of 36.5 ± 11.74 mm2. During flexion, the superior decussation were almost isometric, while the inferior two bundles moved closer significantly. The medial shift between 20°-25° of tibial flexion in the MPFL intact, was absent in the MPFL-deficient state and the patella lateralized even without a laterally directed load. The patella did not exhibit any medial tilt between 20°-25° in the current study. A laterally directed load significantly increased the lateral patellar shift after MPFL dissection, peaking at 30° and 60°. The variable femoral insertion of the MPFL is in agreement with previous literature. The isometric insertion points of the superior fiber pair can be compared to Victor et. al’s isometric central bundle. No fibers exhibited kinematic behavior comparable to Victor et. al’s cranial bundle, which probably represents an aponeurosis for the insertion of the VMO. The current study shows a statistically significant lateral shift and tilt in this state. The peak patellar shift under load between 30° and 50° in MPFL deficient state probably reflects the peak strain on the MFPL in this range of knee flexion These comparisons clarify that the MFPL has an aponeurotic nature that works as a restraint during motion, with an active role under stress, but low role during neutral knee flexion.

The morphology of lumbar sympathetic trunk in humans: a cadaveric study

The vasospastic diseases and chronic pain related to lower limb have been successfully treated by surgical ablation of lumbar sympathetic trunk for last 80 years.Precise knowledge of anatomy of lumbar sympathetic trunk and its adjoining structures is mandatory for safe and uncomplicated lumbar and spinal surgeries.We aim to study the detailed anatomy of entry and exit of lumbar sympathetic trunk, the number, dimensions and location of lumbar ganglia in relation to lumbar vertebra. Thorough dissection was carried out in 30 formalin embalmed cadavers available in the Department of Anatomy, Pravara Institute of Medical Sciences (PIMS), Rural Medical College (RMC), Loni, Maharashtra. A total of 238 ganglia were observed in 60 lumbar sympathetic trunks. The sympathetic trunk traversed dorsal to the crus of diaphragm in 72.6% and in 13.3% it entered dorsal to the medial arcuate ligament. The most common site of the location of lumbar ganglia was in relation to the second lumbar vertebra, sometimes extending up to the L2-L3 vertebral disc. There was a medial shift of sympathetic trunk in lumbar region and it coursed over sacral promontory to reach the pelvic region in 96% of specimens. These variations should be kept in mind in order to prevent hazardous complications like accidental avulsion of first lumbar ganglia and genitofemoral neuritis.

Effect of specific gait modifications on medial knee loading, metabolic cost and perception of task difficulty

BackgroundThe metabolic cost and cognitive demand of altering natural gait have not been well studied. The purpose of this investigation was to assess three modified patterns – toe out, ipsilateral trunk lean and a medial weight shift at the foot – on the basis of 1) medial knee joint load reduction, 2) metabolic cost of performance and 3) subject perception of task difficulty. Methods12 healthy individuals underwent 3 dimensional motion analysis and metabolic testing to assess the gait mechanics and energy expenditure of natural gait and the three experimental gait patterns, performed to a self-selected moderate degree. Walking speed was controlled. Perceived workload was assessed using the NASA Task Load Index. FindingsTrunk lean significantly reduced first peak knee adduction moment (↓32%, P<0.001) as well as KAM impulse (↓35%, P<0.001), but was costly in terms of energy expenditure (↑11%, P<0.001) and perceived workload (↑1178%, P<0.001). A moderate toe-out pattern significantly reduced the second peak knee adduction moment (↓32%, P<0.001) and KAM impulse (↓14%, P=0.026), but had no effect on the first peak. Conversely, toe-out was least demanding in terms of additional energy expenditure (↑2%, P=0.001) and perceived workload (↑314%, P=0.001). Medial shift did not reduce knee adduction moment. InterpretationThe prioritization of joint load reduction versus additional metabolic and cognitive demands could play a substantial role in the clinical decision making process of selecting a modified gait pattern.

BioTrak virtual reality system: Effectiveness and satisfaction analysis for balance rehabilitation in patients with brain injury

ObjectiveTo study effectiveness and satisfaction with a virtual reality-based balance rehabilitation system (BioTrak) for patients with acquired brain injury (ABI). Materials and methodsTen patients with chronic hemiparesis (chronicity>6 months) following an ABI completed a 20-session programme using the balance reaching-task module of the BioTrak system. All patients were assessed at baseline, at the end of treatment and one month later with the Berg Balance Scale (BBS), the Tinetti Performance-Oriented Mobility Assessment (POMA), and the computerised posturography tool NedSVE/IBV. The posturography study included analysis of sensory indexes, limits of stability and rhythmic weight shift. The usability study was conducted using an ad hoc questionnaire. ResultsRepeated measures ANOVA showed a significant improvement in BBS (P<.01), TBS (P<.01), vestibular index (P<.05), and anterior–posterior weight shift (P<.05); a trend in the same direction was also found for medial lateral weight shift (P=.059). The post hoc analysis revealed significant improvement between the initial and final assessments for BBS, POMA and anterior–posterior weight shift control; gains remained a month after completing the programme. The system showed a high degree of usability in terms of presence, immersion and user-friendliness, and there was a significant absence of adverse effects. ConclusionOur results confirm the utility of virtual reality systems for balance rehabilitation in this population. Usability data suggest that BioTrak could be adapted for use in multiple rehabilitation settings by a high number of patients.