Correlation of pain sensitization with muscle strength and angular kinematics in women with patellofemoral pain

BackgroundPatellofemoral pain has a poor long-term prognosis, which can be explained by a pain sensitization process. The pain sensitization process may be related to the increase of stress in the patellofemoral joint that is already associated with kinematic alterations and weakness in the musculature of the hip and knee.MethodsWere compared the pressure pain threshold, temporal summation, conditioned pain modulation, angular kinematics, and muscle strength between 26 patellofemoral pain and 24 asymptomatic women and then correlated pain sensitization variables with biomechanical variables in pain group. The pressure pain threshold was determined on seven points of the knee, tibialis anterior muscle, and elbow. Ten consecutive stimuli were performed for temporal summation, and cold water was used as the conditioning stimulus for conditioned pain modulation. The strength of hip and knee muscles was determined using a manual dynamometer. Three-dimensional kinematics were evaluated during the lateral step down, considering peak and excursion values of the movement and the Movement Deviation Profile.FindingsThe pressure pain threshold of the elbow (2.13 [1.84–2.41] vs. 1.63 [1.25–2] kg/cm²), all sites of the knee were lower, as well as the Movement Deviation Profile was higher (9.33 [9.20–9.46] vs. 12.43 [12.1–12.75]) in the pain group. No difference in temporal summation, conditioned pain modulation, muscle strength and discrete kinematic values were found. No significant correlation was found between the Movement Deviation Profile and pressure pain threshold.InterpretationBiomechanical factors, pain processing, and modulation in women with patellofemoral pain, when different from asymptomatic individuals, are not necessarily associated.     

Gluteal muscle activation during running in females with and without patellofemoral pain syndrome

Background

Hip and knee joint motion in the transverse and frontal plane during running may increase patellofemoral joint stress and contribute to the etiology of patellofemoral joint pain. We evaluated the association between these kinematics and the magnitude and timing of gluteus medius and maximus activity during running in females with patellofemoral pain. We also compared the magnitude and timing of gluteal muscle activity during running between females with and without patellofemoral pain.

Methods

Twenty females with patellofemoral pain and twenty females without knee pain participated in this study. Three-dimensional running kinematics, gluteus medius and gluteus maximus onset time, activation duration, mean activation level, and peak activation level were recorded simultaneously. Gluteal muscle timing and activation level were compared between groups using independent t-tests. The association of gluteal muscle activation parameters running kinematics in females with patellofemoral pain was quantified using Pearson correlation coefficients.

Findings

Females with patellofemoral pain demonstrated delayed (P = 0.028, effect size = 0.76) and shorter (P = 0.01, effect size = 0.88) gluteus medius activation than females without knee pain during running. The magnitude and timing of gluteus maximus activation was not different between groups. Greater hip adduction and internal rotation excursion was correlated with later gluteus medius and gluteus maximus onset, respectively.

Interpretation

Neuromuscular control differences of the gluteal muscles appear to exist among females with patellofemoral pain during running. Interventions to facilitate earlier activation of these muscles may be warranted among females with patellofemoral pain who demonstrate altered running kinematics.     

Efficacy of isokinetic exercise on joint position sense and muscle strength in patellofemoral pain syndrome

OBJECTIVE: The objective of this study was to demonstrate the impairment of knee joint position sense in individuals with patellofemoral pain syndrome and investigate the effects of isokinetic exercise on knee joint position sense and muscle strength. DESIGN: A total of 24 male patients complaining of anterior knee pain caused by overexertion and 24 male healthy individuals without symptoms were included for this investigation. Isokinetic exercise protocol was carried out at angular velocities of 60 degrees/sec and 180 degrees/sec. These sessions were repeated three times per week and lasted for 6 wks. At the beginning and after 6 wks of knee passive joint position sense, quadriceps and hamstring muscle strength and pain assessments were performed. RESULTS: After the isokinetic exercise, flexion peak torque (P < 0.05), extension peak torque (P < 0.01), flexion total work (P < 0.001), extension total work (P < 0.001), passive reproduction of knee joint position sense for 40 degrees of flexion (P < 0.05) and 50 degrees of extension (P < 0.01), and pain score (P < 0.001) improved significantly in the patellofemoral pain syndrome group. CONCLUSION: Isokinetic exercises have positive effects on passive position sense of knee joints, increasing the muscular strength and work capacity. These findings show that using the present isokinetic exercise in rehabilitation protocols of patients with patellofemoral pain syndrome not only improves the knee joint stabilization but also the proprioceptive acuity.     

Pain and hip lateral rotator muscle strength contribute to functional status in females with patellofemoral pain

Background and Purpose . Patellofemoral pain (PFP) is a common musculoskeletal pain condition, especially in females. Decreased hip muscle strength has been implicated as a contributing factor, yet the relationships between pain, hip muscle strength and function are not known. The purpose of this study was to test the hypothesis that pain and hip muscle strength explain unique portions of variance in the functional status of females with PFP. Methods . An observational, cohort study was conducted. The subjects for this study were twenty‐one females with PFP (age: 26 ± 7 years; height: 163 ± 4 cm; and body mass: 62 ± 10 kg). Subjects had a minimum pain duration of two months (mean pain duration: 4.9 ± 3.6 years). The main measures were pain during a unilateral squat, measured with a visual analogue scale; isometric muscle force of gluteus medius, gluteus maximus and hip lateral rotators; and Kujala score (self‐report measure of function). Hierarchical multiple regression analysis was performed with Kujala score as the dependent variable. Pain and hip lateral rotator muscle strength were independent variables, entered in that order. Other strength measures were not correlated with the Kujala score, and as such, were not used in the analysis. Results . Pain explained 22% of the variance in the Kujala score (p = 0.03). Hip lateral rotator strength explained an additional 14% of the variance, after accounting for pain level (p = 0.06). Conclusions . Pain and hip lateral rotator strength contributed to the functional status of females with PFP. Improving pain and hip lateral rotator muscle strength may improve function in females with this common pain condition. Copyright © 2009 John Wiley & Sons, Ltd.     

Altered patterns of abdominal muscle activation in patients with chronic low back pain

This study investigated patterns of abdominal muscle recruitment during the abdominal drawing in manoeuvre in subjects with chronic low back pain (CLBP) and radiological diagnosis of spondylolysis or spondylolisthesis. Data were collected using surface electromyography from 12 physically active subjects with CLBP and 10 controls. The control subjects displayed an ability to preferentially activate internal oblique with minimal activation of upper rectus abdominis during the action of drawing in the abdominal wall. The group with CLBP were unable to achieve this. This finding may reflect the presence of neuromuscular dysfunction in this group. Further study is required to investigate if these findings are linked to the ability of patients with CLBP to provide dynamic stability of their lumbar spine.     

The lumbar multifidus muscle and patterns of pain

This paper describes the patterns of pain induced by injecting hypertonic saline into the lumbar multifidus muscle opposite the L5 spinous process in 15 healthy adult volunteers. All subjects experienced local pain while referred pain was reported by 13 subjects in one of two regions of the thigh; anterior (n=5) or posterior (n=8). These results confirm that the multifidus muscle may be a source of local and referred pain. Comparison of these maps with pain maps following stimulation of the L4 medial dorsal rami and L4-5 interspinous ligaments shows that pain arising from the band of multifidus innervated by the L4 dorsal ramus has a segmental distribution. In addition patterns of pain arising from multifidus clearly overlap those reported for other lumbar structures. These findings highlight the difficulty of using pain distribution to accurately identify specific lumbar structures as the source of pain.     

Electric muscle stimulation of the quadriceps in the treatment of patellofemoral pain

OBJECTIVE: To compare a commercially available electric muscle stimulation regimen with a novel form of stimulation for the rehabilitation of the quadriceps muscle, in patients with patellofemoral pain syndrome. DESIGN: Double-blinded randomized trial with a parallel control group and stratified randomization. SETTING: Home-based rehabilitation program assessed in research center. PARTICIPANTS: Eighty patients (47 women, 33 men) with patellofemoral pain syndrome. INTERVENTIONS: One group (EMPI) received 1 uniform constant frequency component of 35Hz. The other (EXPER) group received an experimental form of stimulation that contained 5 simultaneously delivered frequency components of 125, 83, 50, 2.5, and 2Hz. Stimulation was applied to the quadriceps muscles of the affected leg for 1 hour daily for 6 weeks, a total of 42 treatments. MAIN OUTCOME MEASURES: Lower-limb isometric and isokinetic torque, quadriceps fatigue, knee flexion, patellar pain, a step test, quadriceps cross-sectional area, and Kujala patellofemoral score for pain before and after treatment. RESULTS: Seventy-four patients (43 women, 31 men) completed the trial. Patients in both groups showed significant improvements in all outcomes (P<.05). No significant differences existed between the 2 stimulators in any outcome (P>.05) except for quadriceps cross-sectional area (P=.023). CONCLUSIONS: One form of stimulation was just as efficacious as the other in improving subjective and objective measures.     

Effectiveness of hip muscle strengthening in patellofemoral pain syndrome patients: a systematic review

Introduction:

Patellofemoral pain syndrome (PFPS) is characterized by anterior knee pain, which may limit the performance of functional activities. The influence of hip joint motion on the development of this syndrome has already been documented in the literature. In this regard, studies have investigated the effectiveness of hip muscle strengthening in patients with PFPS.

Objectives:

The aims of this systematic review were (1) to summarize the literature related to the effects of hip muscle strengthening on pain intensity, muscle strength, and function in individuals with PFPS and (2) to evaluate the methodological quality of the selected studies.

Method:

A search for randomized controlled clinical trials was conducted using the following databases: Google Scholar, MEDLINE, PEDro, LILACS, and SciELO. The selected studies had to distinguish the effects of hip muscle strengthening in a group of patients with PFPS, as compared to non-intervention or other kinds of intervention, and had to investigate the following outcomes: pain, muscle strength, and function. The methodological quality of the selected studies was analyzed by means of the PEDro scale.

Results:

Seven studies were selected. These studies demonstrated that hip muscle strengthening was effective in reducing pain. However, the studies disagreed regarding the treatments'' ability to improve muscle strength. Improvement in functional capabilities after hip muscle strengthening was found in five studies.

Conclusion:

Hip muscle strengthening is effective in reducing the intensity of pain and improving functional capabilities in patients with PFPS, despite the lack of evidence for its ability to increase muscle strength.     

The study of respiratory muscles activation during respiratory muscle strength effort in adult females with chronic neck pain

[Purpose] This study aimed to compare maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP) values and muscle activity during MIP and MEP between chronic neck pain and healthy participants. [Participants and Methods] Twenty chronic neck pain and 20 non-symptomatic females participated in this study. Maximal airway pressure (MIP and MEP) and surface electromyography (sEMG) for both sides of the upper trapezius, anterior scalene, pectoralis major and 6th intercostal muscles were recorded simultaneously. [Results] Significant differences of MIP and MEP values were found between the groups. The muscle activities of both sides of upper trapezius and 6th intercostal muscles during MEP were significantly higher in the chronic neck pain group than the healthy group except both sides of anterior scalene and pectoralis major muscles. During MIP, the activities of upper trapezius, 6th intercostal muscles and anterior scalene were significantly different between the two studied groups. Higher activity of left pectoralis major was found in the chronic neck pain group. [Conclusion] Decreasing values of MEP and MIP as well as muscles activities elevation in chronic neck pain participants were clearly demonstrated. Besides the musculoskeletal treatment, we suggest breathing exercise training to be considered in treatment programs.     

The effect of medial patellar taping on pain, strength and neuromuscular recruitment in subjects with and without patellofemoral pain

Objectives

Patellar taping is used by clinicians to reduce pain, increase strength and enhance neuromuscular recruitment in patients with patellofemoral pain. This study explored the effect of medial patellar taping on these parameters in physically active subjects with and without patellofemoral pain.

Study design

A placebo-controlled clinical trial with randomised interventions.

Setting

Sport Science Institute of South Africa.

Participants

Fifteen subjects with patellofemoral pain (experimental group) and 20 subjects without patellofemoral pain (healthy cohort).

Methods

Pain perception, quadriceps force output and electromyographic (EMG) data were collected during maximal quadriceps strength testing and submaximal step testing for each intervention.

Intervention

Subjects were tested during three different knee taping conditions: (1) no tape; (2) placebo tape; and (3) medial tape, in a randomised order.

Main outcome measures

Visual analogue scale (VAS), isokinetic and isometric force output, and EMG analysis.

Results

Medial patellar tape did not result in a significant reduction in pain during the step testing (step-up) in the group with patellofemoral pain (no tape condition: mean VAS 1.0, 95% confidence interval 0.30-1.70; taped condition: mean VAS 1.07, 95% confidence interval 0.22-1.91) or an increase in quadriceps force output. However, there was a significant decrease in EMG activity of the vastus medialis oblique in both groups during the closed chain step test (e.g. group with patellofemoral pain, no tape condition: mean 77%, 95% confidence interval 62-92%; taped condition: mean 64%, 95% confidence interval 53-75%, P < 0.05).

Conclusion

Although taping did not reduce pain in the patellofemoral pain group, it did enhance the efficiency of the vastus medialus oblique. Future studies should determine whether there are clinical benefits to these findings.     

Adolescents and adults with patellofemoral pain exhibit distinct patellar maltracking patterns

BackgroundChronic idiopathic patellofemoral pain is associated with patellar maltracking in both adolescents and adults. To accurately target the underlying, patient-specific etiology, it is crucial we understand if age-of-pain-onset influences maltracking.MethodsTwenty adolescents (13.9 ± 1.4 years) and 20 adults (28.1 ± 4.9 years) female patients with idiopathic patellofemoral pain (age-of-pain-onset: < 14 and > 18 years of age, respectively) formed the patient cohort. Twenty adolescents and 20 adults (matched for gender, age, and body mass index) formed the control cohort. We captured three-dimensional patellofemoral kinematics during knee flexion-extension using dynamic MRI. Patellar maltracking (deviation in patient-specific patellofemoral kinematics, relative to their respective age-controlled mean values) was the primary outcome measure, which was compared between individuals with adolescent-onset and adult-onset patellofemoral pain using ANOVA and discriminant analysis.FindingsThe female adolescent-onset patellofemoral pain cohort demonstrated increased lateral (P = 0.032), superior (P = 0.007), and posterior (P < 0.001) maltracking, with increased patellar flexion (P < 0.001) and medial spin (P = 0.002), relative to the adult-onset patellofemoral pain cohort. Post-hoc analyses revealed increased lateral shift [mean difference ± 95% confidence interval = −2.9 ± 2.1 mm at 10° knee angle], posterior shift [−2.8 ± 2.1 mm, −3.3 ± 2.3 mm & -3.1 ± 2.4 mm at 10°, 20°& 30°], with greater patellar flexion [3.8 ± 2.6 mm & 5.0 ± 2.8 mm, at 20°& 30°] and medial spin [−2.2 ± 1.7 mm & -3.4 ± 2.3 mm at 20°& 30°]. Axial-plane maltracking accurately differentiated the patient age-of-pain-onset (60–75%, P < 0.001).InterpretationAge-of-pain-onset influences the maltracking patterns seen in patients with patellofemoral pain; with all, but 1, degree of freedom being unique in the adolescent-onset-patellofemoral pain cohort. Clinical awareness of this distinction is crucial for correctly diagnosing a patient's pain etiology and optimizing interventional strategies.     

Gluteus medius muscle activation patterns as a predictor of low back pain during standing

BACKGROUND: Low back pain is a primary source of disability and economic costs. Altered trunk muscle activation in people with low back pain, specifically agonist/antagonist co-activation, has been previously demonstrated. Prevailing theory considers this muscle activation pattern to be adaptive to low back pain. Muscle activation patterns prior to, and during, the development of low back pain in asymptomatic individuals, have not been well studied. METHODS: Participants, without a history of low back pain, stood in a constrained area for 2 h. Continuous surface electromyography was collected from trunk and hip muscles. Participants rated their discomfort level on visual analog scale every 15 min. Cross-correlation analyses were used to determine co-activation patterns. Blind predictions were made to categorize participants into low back pain and non-low back pain groups, and comparisons made to visual analog scale scores. FINDINGS: 65% of previously asymptomatic participants developed low back pain during the protocol. Co-activation of the bilateral gluteus medius muscles was found to be prevalent in the low back pain group (P= .002). 76% of the participants were correctly classified into low back pain and non-low back pain groups based on presence or absence of gluteus medius co-activation, with sensitivity= .87 and specificity= .50. INTERPRETATION: Agonist-antagonist co-activation may not be entirely adaptive, and may in fact predispose some individuals to develop low back pain. Muscle activation patterns at the hip may be a useful addition for screening individuals to identify those at risk of developing low back pain during standing.     

The role of visual feedback in respiratory muscle activation and pulmonary function

[Purpose] It is well known that visual feedback is an important factor contributing to balance and postural control. Nevertheless, there has been little discussion about the effects of visual feedback on pulmonary function. This study was conducted to investigate the role of visual feedback on respiratory muscle activation and pulmonary function. [Subjects and Methods] The subjects were 37 healthy adults who consented to participate in this study. The study measured the muscular activation of the trunk and pulmonary function according to the absence or presence of visual feedback. [Results] The results revealed significant changes in muscular activation and pulmonary function with the use of visual feedback. [Conclusion] These findings suggest that visual feedback may play a role in increasing respiratory muscle activity and pulmonary function.Key words: Visual feedback, Respiratory muscles, Pulmonary function     

Quadriceps muscle activity in women runners with and without patellofemoral pain syndrome.

The purpose of this study was to determine whether there was a difference in the electromyographic (EMG) patterns of the quadriceps muscles in women runners diagnosed with patellofemoral pain syndrome (PFPS) compared to the quadriceps activity of women runners free of knee pain and with normal lower extremity alignment. Linear envelope EMGs from vastus medialis, vastus lateralis, and rectus femoris, together with a footswitch signal, were recorded as each subject ran on a treadmill at 80% of their normal running pace and at 12km/h. Each stride period was normalized to 100%, then the linear envelopes for ten trials were ensemble averaged to achieve a mean ensemble for each muscle from each subject. Subsequently, the ensembles for each subject were normalized by dividing by the maximum EMG per cycle; they were then averaged across subjects to obtain the grand mean ensembles of each muscle for each group. Comparisons between the experimental and control groups at both speeds showed that nowhere during the stride cycle did the mean EMG levels of the two groups differ by more than two standard deviations. It was concluded that any changes in the running pattern of the runners with patellofemoral pain syndrome could not be detected by changes in the EMG patterns.     

Trunk muscle strength and low back pain

The strength of the trunk muscles was measured in a group of young males with low back insufficiency (n=7) and in an age matched (19-21 yrs) healthy control group (n=8). A recently designed new application of the isokinetic technique was used to record maximal torque produced by the trunk muscles during flexion, extension and lateral flexion. Trunk muscle strength was measured during isometric contractions in different trunk positions and during slow isokinetic contractions in the whole range of motion. No significant differences between the groups were observed for trunk extension, lateral flexion or flexion with the centre of rotation at L2-L3 level. However, in the initial part of isokinetic trunk flexion with the pivot point at the hip joint the strength values for the back patients were significantly lower than for the controls. The present results demonstrate the importance of a comprehensive approach to the assessment of trunk muscle strength, including different movement velocities, body positions and pivot points. Further studies are needed to evaluate the significance of the specific weakness observed in dynamic trunk flexion strength in the back patients.     

肌力训练对下背痛患者胸腰椎生物力学的影响

目的 探讨肌力训练对下背痛患者胸腰椎生物力学的影响.方法 分为观察组与对照组2组,观察组为2008年9月～2010年8月间本院门诊的50例下背痛患者,其中男24例,女26例,年龄50～70岁,平均(59.7±5.7)岁.对照组为50～70岁的正常人群,其中男23例,女27例,平均(61.1±5.6)岁.观察组进行肌力训...