Psychological and pain profiles in persons with patellofemoral pain as the primary symptom

Influence of unilateral versus bilateral patellofemoral pain on physical activity, pain self-efficacy, and disability

BACKGROUND

Patellofemoral pain (PFP) affects physical and psychosocial health; however, it is unclear if unilateral and bilateral PFP induce similar levels of impairments.

OBJECTIVES

We aimed to compare physical activity (PA), pain self-efficacy, and disability between individuals with unilateral and bilateral PFP, and to compare these groups against pain-free controls.

DESIGN

Cross-sectional case-control.

METHOD

Sixty-two individuals with PFP (25 unilateral and 37 bilateral) and 20 pain-free controls completed the PA assessment using an accelerometer by daily steps, light PA, and moderate-to-vigorous PA (MVPA). We also calculated variability in each PA variable. Pain self-efficacy and disability were measured using the Pain Self-Efficacy Questionnaire and Anterior Knee Pain Scale, respectively.

RESULTS

Individuals with bilateral PFP took fewer daily steps compared to pain-free controls (9568.1 ± 3827.0 vs. 12,285.8 ± 2821.2 steps/day; P = 0.018, Cohen d = 0.79), whereas individuals with unilateral PFP did not (11,099.2 ± 3547.1 steps/day; P = 0.503, Cohen d = 0.37). Individuals with bilateral PFP showed greater variability in MVPA compared to individuals with unilateral PFP (42.9 ± 23.1 vs. 29.0 ± 15.9; P = 0.011, Cohen d = 0.91) and pain-free controls (42.9 ± 23.1 vs. 17.6 ± 6.1; P < 0.001, Cohen d = 1.21). Individuals with unilateral and bilateral PFP similarly exhibited less time spent in MVPA, greater variability in daily steps, lower pain self-efficacy, and greater disability compared to pain-free controls (P < 0.001, Cohen d = 1.14-3.89).

CONCLUSIONS

Versus pain-free controls, individuals with bilateral PFP displayed greater variability in MVPA than individuals with unilateral PFP. However, it is important to note that unilateral PFP influenced time spent in MVPA, variability in daily steps, pain self-efficacy, and disability at similar levels to bilateral PFP.

Lower Extremity Muscle Volume in Unilateral and Bilateral Patellofemoral Pain: A Cross-Sectional Exploratory Study Including Superficial and Deep Muscles

CONTEXT

Existing patellofemoral pain (PFP) literature has primarily been focused on quadriceps muscle volume, with limited attention given to the deep and superficial muscle volume of the lower limbs in individuals with unilateral and bilateral PFP. In this paper, we aim to fill this gap.

OBJECTIVE

To explore superficial and deep lower extremity muscle volume in women with unilateral or bilateral PFP compared with a normative database of pain-free women.

DESIGN

Cross-sectional study.

SETTING

University imaging research center.

PATIENTS OR OTHER PARTICIPANTS

Twenty women with PFP (10 unilateral and 10 bilateral) and 8 pain-free women from a normative database.

MAIN OUTCOME MEASURE(S)

We quantified lower extremity muscle volume via 3.0-T magnetic resonance imaging. Two separate 1-way analyses of variance were performed: (1) unilateral PFP (painful versus nonpainful limb) versus pain-free control groups and (2) bilateral PFP (more painful versus less painful limb) versus pain-free control groups.

RESULTS

We observed no differences in age and body mass index across groups (P > .05). Compared with the pain-free group, the unilateral and bilateral PFP groups had bilaterally smaller volumes of the anterior (iliacus: P ≤ .0004; d range, 2.12-2.65), medial (adductor brevis, adductor longus, gracilis, and pectineus: P ≤ .02; d range, 1.25-2.48), posterior (obturator externus, obturator internus, and quadratus femoris: P < .05; d range, 1.17-4.82), and lateral (gluteus minimus: P ≤ .03; d range, 1.16-2.09) hip muscles and knee extensors (rectus femoris: P ≤ .003; d range, 1.67-2.16) and flexors (long and short head of the biceps femoris: P ≤ .01, d range, 1.56-1.93).

CONCLUSIONS

Women with unilateral and those with bilateral PFP displayed less volume of multiple superficial and deep muscles of the bilateral hips and knees than pain-free women. Interventions should bilaterally target lower limb muscles when treating PFP, and hypertrophy exercises for specific muscles should be explored to increase choices for intervention.

Correlations of The Central Sensitization Inventory, conditioned pain modulation, cognitions and psychological factors in individuals with chronic neck pain: A cross-sectional study

INTRODUCTION

Chronic neck pain (CNP) is a global public health problem, with high prevalence and absenteeism rates. Central sensitization (CS) as a basis for chronic pain may play an essential role in its development and progression. It is often comorbid with low conditioned pain modulation (CPM) effects, cognitions, and psychological problems.

OBJECTIVES

The purposes of this study were to (1) explore the relationship between pain-related cognitions and psychological factors, CPM effects, and the central sensitization inventory (CSI) scores; and (2) determine whether cognitions and psychological factors can predict CSI scores and CPM effects in individuals with CNP.

METHODS

Fifty-four individuals with CNP were recruited for this cross-sectional study. The following outcome measures were evaluated: The CSI (screening tool) was compared with the cold pressor test (CPT), which was the psychophysical test used to assess the CPM; neck pain intensity using the visual analogue scale (VAS), as well as pain-related cognitions (including kinesiophobia and pain catastrophization) and psychological states (including anxiety and depression) using self-report questionnaires.

RESULTS

CSI score was not associated with the CPM effect (r = 0.257, p > 0.05), and no cognitions or psychological factors were associated with CPM (p > 0.05), but CSI score was moderately positively correlated with kinesiophobia (r = 0.554, p < 0.01), lowly positively correlated with pain catastrophization (r = 0.332, p = 0.017) and anxiety (r = 0.492, p < 0.01), but not depression (r = 0.207, p = 0.132). Multiple linear regression analysis showed that kinesiophobia (B = 1.308, p < 0.01) and anxiety (B = 1.806, p = 0.02) were significant positive predictors of CSI score.

CONCLUSIONS

The findings confirm some of our hypotheses. Accordingly, the findings inferred that the CSI does not seem to respond to CPM effect in patients with CNP effectively. In addition, CSI score was associated with cognitions and psychological factors, of which kinesiophobia and anxiety were effective predictors. In clinical practice, pain-related cognitions and psychological factors should be fully considered to manage neck pain efficiently.

Effects of high frequency strengthening on pain sensitivity and function in female runners with chronic patellofemoral pain

OBJECTIVE

To investigate the effects of a high frequency strengthening program on function, pain, and pain sensitization in female runners with chronic patellofemoral pain (PFP).

DESIGN

Cross-sectional study.

SETTING

University laboratory.

PARTICIPANTS

Thirty female runners (mean age 32 ± 8.1 years) with chronic PFP completed an 8-week home strengthening program.

MAIN OUTCOME MEASURES

Variables assessed at baseline, 8-weeks, and 12 weeks included single leg step down test (SLSD), pain, Anterior Knee Pain Scale (AKPS), University of Wisconsin Running Injury and Recovery Index (UWRI), and quantitative sensory testing.

RESULTS

There was large and statistically significant improvement at 8 and 12 weeks for average knee pain (ηp2 = 0.334, p < 0.001), worst knee pain (ηp2 = 0.351, p < 0.001), SLSD (ηp2 = 0.161, p = 0.001), AKPS (ηp2 = 0.463, p < 0.001), and UWRI (ηp2 = 0.366, p < 0.001). A medium to large effect and statistically significant improvement in pressure pain threshold testing was found for all local and remote structures (ηp2 range, 0.110 to 0.293, range p < 0.001 to p = 0.009) at 8 and 12 weeks.

CONCLUSIONS

There was a significant decrease in local and remote hyperalgesia via mechanical and thermal pain sensitivity testing in female runners with chronic PFP. There was a large effect and significant improvement in self-reported pain and function.

Is muscle activation diverse in females with isolated patellofemoral osteoarthritis contrasted with age-matched healthy controls during stair descent task?

Background: Patellofemoral osteoarthritis (PF OA) is exceptionally predominant and limiting. However, little is known about the risk factors that contribute to its onset and progression. Purpose: The aim of this study was to decide if women with PF OA descend stairs using different muscular activation strategies compared to similarly aged healthy controls. Methods: Thirty-one women with isolated PF OA and 11 similarly aged healthy women took part in this study. The activation onset and duration of PF OA in vastus medialis oblique (VMO), vastus lateralis (VL), gluteus medius (GM), transversus abdominis (TrA), and multifidus muscles were evaluated during the stair descent task using surface electromyography (EMG). Results: There was a non-significant difference between women with PF OA and healthy controls regarding all tested variables, except for the GM activation onset that was significantly delayed in women with PF OA, with the p-value of 0.011. Conclusion: The causes of PF OA differ and might not always be due to a lack of quadriceps strength or VMO activation deficiency, and prospective longitudinal studies are required to confirm this assumption.

The relationship of behavioral and psychological traits with pain sensitivity in females with patellofemoral pain: A cross-sectional study

OBJECTIVE

The purpose of this study was to describe the relationship between behavioral and psychological traits with indicators of central sensitization in female runners with patellofemoral pain (PFP), and to determine if behavioral and psychological traits improve with strength training.

DESIGN

Cross-sectional study.

SETTING

University laboratory.

PARTICIPANTS

Twenty-eight active females (mean age 32 ± 8.1 years) with PFP completed testing at baseline, 8 weeks (post intervention), and 12 weeks.

MAIN OUTCOME MEASURES

Behavioral and psychological questionnaires included the General Anxiety Disorder-7, Patient Health Questionairre-9, Pain Catastrophizing Scale, Tampa Scale of Kinesiophobia-11, and Central Sensitization Inventory. Quantitative sensory testing (QST) measures were also collected. After baseline testing, subjects were instructed in a hip and knee strengthening intervention to be completed twice daily over 8 weeks.

RESULTS

A statistically significant improvement was found at 12 weeks for anxiety (p = .015; ηp (Boling et al., 2010) = 0.099) and kinesiophobia (p = .041; ηp (Boling et al., 2010) = 0.076). There was no significant improvement for depression, catastrophizing, or subjective central sensitization. No significant correlations were found between any of the behavioral and psychological questionnaires with baseline QST variables.

CONCLUSIONS

No relationship was found for behavioral and psychological characteristics with QST measures in female runners with persistent PFP.

Is Adding Education to Trunk and Hip Exercises Beneficial for Patellofemoral Pain? A Randomized Controlled Trial

OBJECTIVE

To investigate the effect of adding education to trunk and hip exercises in patients with patellofemoral pain (PFP).

DESIGN

A randomized controlled trial.

SETTING

Research laboratory.

PARTICIPANTS

Sixty patients with PFP (N=60) were randomly assigned to either an experimental group (education followed by trunk and hip exercises, n=30) or a control group (trunk and hip exercises, n=30).

INTERVENTIONS

Both groups received 8 weeks of trunk and hip exercises, while patients in the experimental group participated in 3 prior education sessions.

MAIN OUTCOME MEASURES

The primary outcome was pain; secondary outcomes were pain catastrophizing, kinesiophobia, function, and muscle strength. Outcomes were assessed at baseline, after 8 weeks (post-intervention), and 3 months post-intervention (follow-up).

RESULTS

No significant between-group differences were observed for pain outcome post-intervention. The experimental group showed superiority over the control group in the improvement of pain catastrophizing (mean difference: -2.32; 95% confidence interval [CI] -1.059 to 0.028) and kinesiophobia (mean difference: -3.56; 95% CI -1.067 to -0.035) at post-intervention. In the experimental group, improvements were maintained at follow-up assessment for all outcomes, except muscle strength.

CONCLUSION

Adding education to trunk and hip exercises was associated with greater improvements in psychological outcomes than trunk and hip exercises alone after the intervention. Education can be incorporated when designing trunk and hip exercises for patients with PFP.

Kinesiophobia Is Associated With Poor Function and Modifiable Through Interventions in People With Patellofemoral Pain: A Systematic Review With Individual Participant Data Correlation Meta-Analysis

OBJECTIVE

The aim of this systematic review and correlation meta-analysis was to identify factors associated with kinesiophobia in individuals with patellofemoral pain (PFP) and to identify interventions that may reduce kinesiophobia in individuals with PFP.

METHODS

Seven databases were searched for articles including clinical factors associated with kinesiophobia or interventions that may reduce kinesiophobia in individuals with PFP. Two reviewers screened articles for inclusion, assessed risk of bias and quality, and extracted data from each study. A mixed-effects model was used to calculate correlations of function and pain with kinesiophobia using individual participant data. Meta-analyses were performed on interventional articles; Grading of Recommendations, Assessment, Development, and Evaluation was used to evaluate certainty of evidence. Results were reported narratively when pooling was not possible.

RESULTS

Forty-one articles involving 2712 individuals were included. Correlation meta-analyses using individual participant data indicated a moderate association between self-reported function and kinesiophobia (n = 499; r = -0.440) and a weak association between pain and kinesiophobia (n = 644; r = 0.162). Low-certainty evidence from 2 articles indicated that passive treatment techniques were more effective than minimal intervention in reducing kinesiophobia (standardized mean difference = 1.11; 95% CI = 0.72 to 1.49). Very low-certainty evidence from 5 articles indicated that interventions to target kinesiophobia (psychobehavioral interventions, education, and self-managed exercise) were better in reducing kinesiophobia than physical therapist treatment approaches not specifically targeting kinesiophobia (standardized mean difference = 1.64; 95% CI = 0.14 to 3.15).

CONCLUSION

Higher levels of kinesiophobia were moderately associated with poorer function and weakly associated with higher pain in individuals with PFP. Taping and bracing may reduce kinesiophobia immediately after use, and specific kinesiophobia-targeted interventions may reduce kinesiophobia following the full intervention; however, the certainty of evidence is very low.

IMPACT

Assessment of kinesiophobia in clinical practice is recommended, on the basis of the relationships identified between kinesiophobia and other important factors that predict outcomes in individuals with PFP.

Pain-related cognitions and emotional distress are not associated with conditioned pain modulation: an explorative analysis of 1142 participants with acute, subacute, and chronic pain

ABSTRACT

Reduced conditioned pain modulation (CPM) and psychological distress co-occur frequently in many pain conditions. This study explored whether common negative pain cognitions and emotional factors were related to lower CPM in individuals across the spectrum from acute to chronic pain. Previously collected data on the CPM effect, pain-related cognitions (fear of movement, pain catastrophizing), and emotional distress (depression, anxiety) through questionnaires from 1142 individuals with acute, subacute, or chronic pain were used. The presence of negative psychological factors was dichotomized according to cutoff values for questionnaires. Associations between the presence of each negative psychological factor and the amplitude of pain reduction in the CPM paradigm was explored with Generalized Linear Models adjusted for sex, age, body mass index, and pain duration. A secondary analysis explored the cumulative effect of psychological factors on CPM. When dichotomized according to cutoff scores, 20% of participants were classified with anxiety, 19% with depression, 36% with pain catastrophizing, and 48% with fear of movement. The presence of any negative psychological factor or the cumulative sum of negative psychological factors was associated with lower CPM (individual factor: β between -0.15 and 0.11, P ≥ 0.08; total: β between -0.27 and -0.12, P ≥ 0.06). Despite the common observation of psychological factors and reduced CPM in musculoskeletal pain, these data challenge the assumption of a linear relationship between these variables across individuals with acute, subacute, and chronic pain. Arguably, there was a nonsignificant tendency for associations in nonexpected directions, which should be studied in a more homogenous population.

What Do We Know about Nociplastic Pain?

Nociplastic pain is a recently distinguished type of pain, distinct from neuropathic and nociceptive pain, and is well described in the literature. It is often mistaken for central sensitization. Pathophysiology has not been clearly established with regard to alteration of the concentration of spinal fluid elements, the structure of the white and gray matter of the brain, and psychological aspects. Many different diagnostic tools, i.e., the painDETECT and Douleur Neuropathique 4 questionnaires, have been developed to diagnose neuropathic pain, but they can also be applied for nociplastic pain; however, more standardized instruments are still needed in order to assess its occurrence and clinical presentation. Numerous studies have shown that nociplastic pain is present in many different diseases such as fibromyalgia, complex regional pain syndrome type 1, and irritable bowel syndrome. Current pharmacological and nonpharmacological treatments for nociceptive and neuropathic pain are not entirely suitable for treating nociplastic pain. There is an ongoing effort to establish the most efficient way to manage it. The significance of this field has led to several clinical trials being carried out in a short time. The aim of this narrative review was to discuss the currently available evidence on pathophysiology, associated diseases, treatment possibilities, and clinical trials. It is important that physicians widely discuss and acknowledge this relatively new concept in order to provide optimized pain control for patients.

The association between kinesiophobia and functional limitations in service members with knee pain

BACKGROUND

Knee diagnoses account for more than 50% of lower extremity musculoskeletal conditions in non-deployed US Service members. However, there is limited information regarding kinesiophobia in Service members with non-operative knee diagnoses.

HYPOTHESES

The objectives of this study were to determine the prevalence of high levels of kinesiophobia in US military Service members with knee pain across different knee diagnoses, and to determine the relationships between kinesiophobia and lower extremity function and/or specific functional limitations in Service members with knee pain. It was hypothesized Service members with knee pain would exhibit high levels of kinesiophobia across all knee diagnoses examined, and higher levels of both kinesiophobia and pain would be associated with worse self-reported function in this population. It was also hypothesized higher levels of kinesiophobia would be associated with functional activities with high knee loading.

DESIGN

Retrospective cohort study.

LEVEL OF EVIDENCE

IV.

METHODS

Sixty-five US Service members presenting to an outpatient physical therapy clinic were included in this study (20 females; age = 30.8 ± 7.7 years; height = 1.74 ± 0.9 m; mass = 80.7 ± 16.2 kg). Inclusion criterion was the presence of knee pain (duration = 50 ± 59 months); exclusion criterion was knee pain as a sequela of knee surgery. Data regarding demographic, pain chronicity, pain by Numeric Rating Scale (NRS), Tampa Scale of Kinesiophobia (TSK), and Lower Extremity Functional Scale (LEFS) were retrospectively obtained from patients' medical records. A high level of kinesiophobia was defined as a TSK score of greater than 37 points. Patient diagnoses included: osteoarthritis (n = 16); patellofemoral pain syndrome (n = 23); and other non-operative knee diagnoses (n = 26). Commonality analysis was utilized to determine the effects of age, height, mass, NRS, and TSK on LEFS score. Predictor values were interpreted as <1% = negligible, >1% = small; >9% = moderate, >25% = large. Additionally, exploratory item-specific analyses examined the strength of the relationships between kinesiophobia and LEFS item responses. Binary logistic regression determined if difficulty with an individual LEFS item could be predicted from either NRS or TSK score. Statistical significance was set at P < 0.05.

RESULTS

High levels of kinesiophobia were identified in 43 individuals (66%). NRS and TSK explained 19.4% and 8.6% of the unique variance in LEFS, and 38.5% and 20.5% of total variance, respectively. Age, height, and mass explained negligible to small proportions of the unique variance in LEFS. TSK and NRS were independent predictors for 13/20 individual LEFS items, with odds ratios ranging from 1.12 to 3.05 (P < 0.05).

CONCLUSION

The majority of US Service members in this study exhibited high levels of kinesiophobia. Kinesiophobia was significantly related to self-reported functional scores and performance on individual functional tasks in Service members with knee pain.

CLINICAL RELEVANCE

Treatment strategies addressing both fear of movement and pain reduction in patients with knee pain may help optimize functional outcomes.

Are Physical Function and Fear of Movement Risk Factors for Patellofemoral Pain? A 2-Year Prospective Study

CONTEXT

To determine (1) whether physical function and fear of movement are prospectively associated with the risk of females developing patellofemoral pain (PFP) and (2) whether they change following development of PFP.

DESIGN

Prospective observational study.

METHODS

A total of 114 asymptomatic females (18-22 y old) completed assessment of physical function (forward step-down test and single-leg hop for distance) and fear of movement using the Tampa Scale for Kinesiophobia at baseline and 2-year follow-up. Presence of symptoms of PFP was monitored bimonthly.

RESULTS

Ninety participants (retention rate = 79%) completed the 2-year follow-up assessment, with 27 (24% of the cohort) developing PFP. Physical function, including forward step-down test (P = .659) and single-leg hop for distance (P = .825), and fear of movement (P = .479) were not associated with the risk of developing PFP. Females who developed PFP presented with reduced forward step-down repetitions (mean difference = 2.8; 95% confidence interval, 0.2 to 5.3) and single-leg hop for distance (10.2; 95% confidence interval, 2.7 to 17.7 cm) at 2-year follow-up. There was no statistically significant difference between those who did and did not develop PFP for fear of movement (-3.4; 95% confidence interval, -7.0 to 0.2).

CONCLUSIONS

Physical function and fear of movement were not associated with the risk of developing PFP in young females. However, the change over time in the step-down and single-leg hop for distance tests may suggest that, even in the early stages of PFP, young females present impaired physical function compared with females who did not develop symptoms. Fear of movement may develop due to persistent PFP, and does not appear to be a risk factor or key feature in females with PFP of short symptoms duration.

Body fat and skeletal muscle mass, but not body mass index, are associated with pressure hyperalgesia in young adults with patellofemoral pain

BACKGROUND

Young adults with patellofemoral pain (PFP) have a high prevalence of being overweight or obese, which is associated with impaired lower limb function and muscle weakness. However, the impact of being overweight or obese on pain sensitivity has not been explored.

OBJECTIVES

We investigated the association between body fat, skeletal muscle mass, and body mass index (BMI) with pressure hyperalgesia and self-reported pain in young adults with PFP.

METHODS

114 adults with PFP (24 ± 5 years old, 62% women) were recruited. Demographics and self-reported pain (current and worst knee pain intensity in the previous month - 0-100 mm visual analog scale) were recorded. Body fat and skeletal muscle mass were measured using bioelectrical impedance. Pressure hyperalgesia was measured using a handheld algometer (pressure pain threshold) at three sites: center of patella of the painful knee, ipsilateral tibialis anterior, and contralateral upper limb. The association between body fat, skeletal muscle mass, and BMI with pressure hyperalgesia and self-reported pain were investigated using partial correlations and hierarchical regression models (adjusted for sex, bilateral pain, and symptoms duration).

RESULTS

Higher body fat and lower skeletal muscle mass were associated with local, spread, and widespread pressure hyperalgesia (ΔR²=0.09 to 0.17, p ≤ 0.001; ΔR²=0.14 to 0.26, p<0.001, respectively), and higher current self-reported pain (ΔR²=0.10, p<0.001; ΔR²=0.06, p = 0.007, respectively). Higher BMI was associated with higher current self-reported pain (ΔR²=0.10, p = 0.001), but not with any measures of pressure hyperalgesia (p>0.05).

CONCLUSION

Higher body fat and lower skeletal muscle mass help to explain local, spread, and widespread pressure hyperalgesia, and self-reported pain in people with PFP. BMI only helps to explain self-reported pain. These factors should be considered when assessing people with PFP and developing their management plan, but caution should be taken as the strength of association was generally low.

Self-efficacy and Emotional Distress in a Cohort With Patellofemoral Pain

Background:

Patellofemoral pain (PFP) is commonly described and approached in biomechanical terms despite strong evidence that psychosocial factors such as kinesiophobia, emotional distress, and self-efficacy are important in long-standing musculoskeletal pain.

Purpose:

To describe levels of self-efficacy, emotional distress, kinesiophobia, and widespread pain in a cohort with long-standing PFP and determine their association with measures of pain, function, and health-related quality of life.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

Included were 112 patients with PFP (age range, 16-40 years) who had been recruited to a randomized controlled trial. Seven baseline factors (patient sex, pain duration, number of pain sites throughout the body, kinesiophobia [Tampa Scale of Kinesiophobia], emotional distress [Hopkins Symptom Checklist], self-efficacy, and knee extension strength) were investigated for associations with the following outcomes: symptoms of PFP (Anterior Knee Pain Scale), pain (worst and usual), and health-related quality of life (5-level EuroQol-5 Dimensions [EQ-5D-5L]). We used bivariate models and multivariable linear regression models with a stepwise backward removal method to find associations with the outcomes. Internal validation was conducted, and adjusted coefficients after shrinkage are presented.

Results:

Of the study patients, 28% reported emotional distress (Hopkins Symptom Checklist ≥1.75), 69% reported multiple pain sites, and 33% had widespread pain. The kinesiophobia score was elevated, with a mean score of 35.4 ± 8.2. Self-efficacy was strongly associated with better function (Anterior Knee Pain Scale) and health-related quality of life (EQ-5D-5L) as well as lower pain scores in bivariate and multivariable models. Self-efficacy and emotional distress explained 50% of the variance in health-related quality of life (EQ-5D-5L).

Conclusion:

Our findings support other studies of PFP suggesting elevated levels of kinesiophobia and emotional distress and higher rates of widespread pain compared with the general population or pain-free controls. Higher self-efficacy was associated with better function and health-related quality of life. Together with emotional distress, it explained half the variance of health-related life quality. The results underline the importance of approaching these patients in a biopsychosocial model.

Registration:

NCT02114294 ( ClinicalTrials.gov identifier).

Brain Activity During Experimental Knee Pain and Its Relationship With Kinesiophobia in Patients With Patellofemoral Pain: A Preliminary Functional Magnetic Resonance Imaging Investigation

Context: The etiology of patellofemoral pain has remained elusive, potentially due to an incomplete understanding of how pain, motor control, and kinesiophobia disrupt central nervous system functioning. Objective: To directly evaluate brain activity during experimental knee pain and its relationship to kinesiophobia in patients with patellofemoral pain. Design: Cross-sectional. Methods: Young females clinically diagnosed with patellofemoral pain (n = 14; 14.4 [3.3] y; body mass index = 22.4 [3.8]; height = 1.61 [0.1] m; body mass = 58.4 [12.7] kg). A modified Clarke test (experimental pain condition with noxious induction via patella pressure and quadriceps contraction) was administered to the nondominant knee (to minimize limb dominance confounds) of patients during brain functional magnetic resonance imaging (fMRI) acquisition. Patients also completed a quadriceps contraction without application of external pressure (control contraction). Kinesiophobia was measured using the Tampa Scale of Kinesiophobia. The fMRI analyses assessed brain activation during the modified Clarke test and control contraction and assessed relationships between task-induced brain activity and kinesiophobia. Standard processing for neuroimaging and appropriate cluster-wise statistical thresholds to determine significance were applied to the fMRI data (z > 3.1, P < .05). Results: The fMRI revealed widespread neural activation in the frontal, parietal, and occipital lobes, and cerebellum during the modified Clarke test (all zs > 4.4, all Ps < .04), whereas neural activation was localized primarily to frontal and cerebellar regions during the control contraction test (all zs > 4.4, all Ps < .01). Greater kinesiophobia was positively associated with greater activity in the cerebello-frontal network for the modified Clarke test (all zs > 5.0, all Ps < .01), but no relationships between kinesiophobia and brain activity were observed for the control contraction test (all zs < 3.1, all Ps > .05). Conclusions: Our novel experimental knee pain condition was associated with alterations in central nociceptive processing. These findings may provide novel complementary pathways for targeted restoration of patient function.

Developing Clinical and Research Priorities for Pain and Psychological Features in People With Patellofemoral Pain: An International Consensus Process With Health Care Professionals

OBJECTIVE

To decide clinical and research priorities on pain features and psychological factors in persons with patellofemoral pain.

DESIGN

Consensus development process.

METHODS

We undertook a 3-stage process consisting of (1) updating 2 systematic reviews on quantitative sensory testing of pain features and psychological factors in patellofemoral pain, (2) an online survey of health care professionals and persons with patellofemoral pain, and (3) a consensus meeting with expert health care professionals. Participants responded that they agreed, disagreed, or were unsure that a pain feature or psychological factor was important in clinical practice or as a research priority. Greater than 70% participant agreement was required for an item to be considered important in clinical practice or a research priority.

RESULTS

Thirty-five health care professionals completed the survey, 20 of whom attended the consensus meeting. Thirty persons with patellofemoral pain also completed the survey. The review identified 5 pain features and 9 psychological factors-none reached 70% agreement in the patient survey, so all were considered at the meeting. After the meeting, pain catastrophizing, fear-avoidance beliefs, and pain self-efficacy were the only factors considered clinically important. All but the thermal pain tests and 3 psychological factors were considered research priorities.

CONCLUSION

Pain catastrophizing, pain self-efficacy, and fear-avoidance beliefs were factors considered important in treatment planning, clinical examination, and prognostication. Quantitative sensory tests for pain were not regarded as clinically important but were deemed to be research priorities, as were most psychological factors. J Orthop Sports Phys Ther 2022;52(1):29-39. doi:10.2519/jospt.2022.10647.

A Review of the Relationships Between Knee Pain and Movement Neuromechanics

CONTEXT

Knee injury and disease are common, debilitating, and expensive. Pain is a chief symptom of knee injury and disease and likely contributes to arthrogenic muscle inhibition. Joint pain alters isolated motor function, muscular strength, and movement biomechanics. Because knee pain influences biomechanics, it likely also influences long-term knee joint health.

OBJECTIVE

The purpose of this article is 2-fold: (1) review effects of knee pain on lower-extremity muscular activation and corresponding biomechanics and (2) consider potential implications of neuromechanical alterations associated with knee pain for long-term knee joint health. Experimental knee pain is emphasized because it has been used to mimic clinical knee pain and clarify independent effects of knee pain. Three common sources of clinical knee pain are also discussed: patellofemoral pain, anterior cruciate ligament injury and reconstruction, and knee osteoarthritis.

DATA SOURCES

The PubMed, Web of Science, and SPORTDiscus databases were searched for articles relating to the purpose of this article.

CONCLUSION

Researchers have consistently reported that knee pain alters neuromuscular activation, often in the form of inhibition that likely occurs via voluntary and involuntary neural pathways. The effects of knee pain on quadriceps activation have been studied extensively. Knee pain decreases voluntary and involuntary quadriceps activation and strength and alters the biomechanics of various movement tasks. If allowed to persist, these neuromechanical alterations might change the response of articular cartilage to joint loads during movement and detrimentally affect long-term knee joint health. Physical rehabilitation professionals should consider neuromechanical effects of knee pain when treating knee injury and disease. Resolution of joint pain can likely help to restore normal movement neuromechanics and potentially improve long-term knee joint health and should be a top priority.

How Do Hip Exercises Improve Pain in Individuals With Patellofemoral Pain? Secondary Mediation Analysis of Strength and Psychological Factors as Mechanisms

OBJECTIVE

To determine whether the effect of hip exercise on patellofemoral pain is mediated through changes in hip muscle strength or psychological factors.

DESIGN

Secondary mediation analysis of a randomized clinical trial, in which 218 participants with patellofemoral pain were randomly assigned to receive foot orthoses or hip exercises.

METHODS

Pain (Knee injury and Osteoarthritis Outcome Score pain subscale) and number of pain-free squats at 12 weeks were the outcomes for this mediation analysis, as they are pathognomonic of patellofemoral pain. Hip strength dynamometry (abduction, adduction, and external rotation) and psychological characteristics (pain catastrophizing, kinesiophobia, and anxiety) measured at 6 weeks were considered as potential mediators. We used mediation analysis to decompose the total effect of treatment on the outcome into (1) the "indirect effect" (ie, the portion acting through the mediator) and (2) the "direct effect."

RESULTS

The effect of hip exercise on pain and squats was not mediated by any of the strength or psychological mediators analyzed. All indirect effects were small and showed wide 95% confidence intervals (CIs) that contained zero (eg, for pain-free squats: abduction strength, -0.13; 95% CI: -0.49, 0.23; Tampa Scale of Kinesiophobia, -0.17; 95% CI: -0.64, 0.30).

CONCLUSION

Hip strength improved after hip exercise, yet strength did not mediate improvements in pain and pain-free squats, and alternative psychological mediators were not implicated. J Orthop Sports Phys Ther 2021;51(12):602-610. doi:10.2519/jospt.2021.10674.

ICD-11 Classification of Pediatric Chronic Pain Referrals in Ireland, with Secondary Analysis of Primary vs Secondary Pain Conditions

Objective

To classify pediatric chronic pain referrals in Ireland according to the classification system of the 11^th version of the International Classification of Diseases (ICD-11). In addition, differences between primary and secondary pain groups were assessed.

Methods

Retrospective review of complex pain assessment forms completed at the time of initial attendance at pediatric chronic pain clinics in Dublin, Ireland. Patients were classified as having a chronic primary (CPP) or chronic secondary (CSP) pain condition as per ICD-11 classification. Secondary analysis of between-group and within-group differences between primary and secondary pain conditions was undertaken.

Results

Of 285 patients coded, 123 patients were designated as having a CPP condition (77% of whom were assigned an adjunct parent code) and 162 patients as having a CSP condition (61% of whom were assigned an adjunct parent code). Between-group comparisons found that the lowest reported pain scores were higher in CPP than in CSP conditions. There were stronger correlations between parental pain catastrophizing and pain intensity, school attendance, and pain interference with social activities in the CSP group than in the CPP group.

Conclusions

The majority of children with both CPP and CSP were assigned multiple parent codes. There appears to be a gradient in the differences in biopsychosocial profile between CPP and CSP conditions. Additional field testing of the ICD-11 classification in pediatric chronic pain will be required.

Exploring the Pain in Patellofemoral Pain: A Systematic Review and Meta-Analysis Examining Signs of Central Sensitization

BACKGROUND

Patellofemoral pain (PFP) has high recurrence rates and minimal long-term treatment success. Central sensitization refers to dysfunctional pain modulation that occurs when nociceptive neurons become hyperresponsive. Researchers in this area of PFP have been increasingly productive in the past decade.

OBJECTIVE

To determine whether evidence supports manifestations of central sensitization in individuals with PFP.

DATA SOURCES

We searched MeSH terms for quantitative sensory testing (QST) pressure pain thresholds (PPTs), conditioned pain modulation (CPM), temporal summation, sensitization, hyperalgesia, and anterior knee pain or PFP in PubMed, SPORTDiscus, CINAHL, Academic Search Complete, and EBSCOhost.

STUDY SELECTION

Peer-reviewed studies that were written in English and published between 2005 and 2020 and investigated QST or pain mapping in a sample with PFP were included in this review.

DATA EXTRACTION

The initial search yielded 140 articles. After duplicates were removed, 78 abstracts were reviewed. The full text of 21 studies was examined, and we included 15 studies in our evaluation: 6 in the meta-analysis, 4 in the systematic review, and 5 in both the meta-analysis and systematic review.

DATA SYNTHESIS

A random-effects meta-analysis was conducted for 4 QST variables (local PPTs, remote PPTs, CPM, temporal summation). Strong evidence supported lower local and remote PPTs, impaired CPM, and facilitated temporal summation in individuals with PFP compared with pain-free individuals. Evidence for heat and cold pain thresholds was conflicting. Pain mapping demonstrated expanding pain patterns associated with long duration of PFP symptoms.

CONCLUSIONS

Signs of central sensitization were present in individuals with PFP, indicating altered pain modulation. The etiologic and treatment models of PFP should reflect the current body of evidence regarding central sensitization. Signs of central sensitization should be monitored clinically, and treatments with central effects should be considered as part of a multimodal plan of care.

Heightened pain facilitation rather than impaired pain inhibition distinguishes those with moderate/severe disability in work-related neck pain

ABSTRACT

To better understand the mechanisms underpinning work-related neck pain, this cross-sectional and single-blinded study compared somatosensory profiles among sonographers with varied neck disability levels. Based on K-mean cluster analysis of scores on the neck disability index (NDI), participants were classified into no (NDI ≤ 8%, n = 31, reference group), mild (NDI = 10%-20%, n = 43), or moderate/severe (NDI ≥ 22%, n = 18) disability groups. Data were collected on bodily pain distribution and severity and psychological measures including depression, anxiety, pain-catastrophizing, and fear-avoidance beliefs using validated scales. Participants attended 1 session of quantitative sensory testing performed according to a standardized protocol, including local and remote thermal and mechanical pain thresholds, temporal summation of pain (TSP), conditioned pain modulation, and an exercise-induced analgesia paradigm. Compared with participants with no and mild disability, those with moderate/severe disability showed more widespread pain, cold and mechanical hyperalgesia at a remote nonpainful site, and significantly higher TSP. Participants with mild disability demonstrated significantly higher TSP than those with no disability. These group differences were attenuated after adjusting for depression or anxiety, indicating these psychological factors may mediate the somatosensory changes associated with neck disability. Group differences were not found for conditioned pain modulation or exercise-induced analgesia. These findings suggest that heightened pain facilitation, rather than impaired pain inhibition may underpin nociplastic pain in participants with moderate/severe disability, and it may be associated with depression and anxiety. Clinicians should be aware that individuals with work-related neck pain presenting with moderate/severe disability display distinct somatosensory features and tailor management strategies accordingly.

Non-operative Management of Anterior Knee Pain: Patient Education

PURPOSE OF REVIEW

Anterior knee pain is a multifactorial, often chronic condition, which can lead to long-term pain and disability. The purpose of this review is to examine the latest research on patient education for anterior knee pain. We will focus on how we might use patient education to increase the adoption of other efficacious treatment modalities and offer some suggestions for content and form of effective patient education.

RECENT FINDINGS

New research suggests that patient education, alone, or in combination with targeted exercise therapy, can be effective in reducing pain and improving function in patients with patellofemoral pain. Addressing non-physical or psychological factors may also be an important component of patient education in many patients with chronic pain. Incorporation of new technologies into patient education, such as those available online, or through phone- or tablet-based apps, is likely to be helpful in the future, as we move more towards connecting with patients virtually. Patient education has been shown to be effective in decreasing pain and improving activity in patients with patellofemoral pain. Patient education should be individualized to the patient, focus on the latest effective treatments, and emphasize those treatments that can be self-managed by the patient. Emphasis should also be placed on patient understanding of risk factors and patterns of movement that may lead to, or exacerbate, anterior knee pain. Future research should continue to further characterize the elements of patient education that offer the most efficient treatment benefit.