Predictors of short and long term outcome in patellofemoral pain syndrome: a prospective longitudinal study

Endurance Sporting Events

Endurance sports encompass a broad range of events from marathons and triathlons to ultramarathons, long-distance cycling, skiing, and swimming. As these events have experienced a surge in popularity, we have a greater need to understand the associated medical risks. This article reviews the history of endurance races, reviews the most critical and common causes of cardiovascular, heat, electrolyte, and musculoskeletal injuries/illnesses, and discusses considerations for medical directors/personnel associated with such events.

Non-Invasive Radiofrequency Diathermy Neuromodulation Added to Supervised Therapeutic Exercise in Patellofemoral Pain Syndrome: A Single Blind Randomized Controlled Trial with Six Months of Follow-Up

The evidence-based treatment of patellofemoral pain (PFP) suggests that therapeutic exercise (TE) focused on improving muscle strength and motor control be the main conservative treatment. Recent research determined that the success of the TE approach gets improved in the short term by the addition of neuromodulation via radiofrequency diathermy (RFD). As there is no follow up data, the objective of this research is to assess the long-term effects of adding RFD to TE for the pain, function and quality of life of PFP patients. To this aim, a single-blind randomized controlled trial was conducted on 86 participants diagnosed of PFP. Participants who met the selection criteria were randomized and allocated into either a TE group or an RFD + TE group. TE consisted of a 20 min daily supervised exercise protocol for knee and hip muscle strengthening, while RFD consisted of the application of neuromodulation using a radiofrequency on the knee across 10 sessions. Sociodemographic data, knee pain and lower limb function outcomes were collected. The RFD + TE group obtained greater improvements in knee pain (p < 0.001) than the TE group. Knee function showed statistically significant improvements in Kujala (p < 0.05) and LEFS (p < 0.001) in the RFD + TE group in the short and long term. In conclusion, the addition of RFD to TE increases the beneficial effects of TE alone on PFP, effects that remain six months after treatment.

Patellofemoral pain in general practice: the incidence and management

BACKGROUND

Patellofemoral pain (PFP) is a nontraumatic knee problem primarily observed in physically active adolescents. The objective of this study was to determine the incidence and management of PFP in children and adolescents in general practice.

METHODS

A retrospective cohort study was conducted using a regional primary care database containing full electronic health records of over 300,000 patients. Patients with a new PFP diagnosis between the years 2013 and 2019 were extracted using a search algorithm based on International Classification of Primary Health Care coding and search terms in free text. Data on the management of PFP were manually checked and analysed. In addition, a sub-analysis for chronic and nonchronic PFP patients was performed.

RESULTS

The mean incidence of PFP over the study period was 3.4 (95% CI 3.2-3.6) per 1,000 person years in the age group of 7-24 years. Girls had a higher incidence rate (4.6 [95% CI 4.3-5.0]) compared to boys (2.3 [95% CI 2.1-2.5]). Peak incidence was at age 13 years for both sexes. The most commonly applied management strategy was advice (55.1%), followed by referral to physiotherapy (28.2%), analgesics prescription (10.4%), and referral to the orthopaedic surgeon (8.9%). No differences were found in age, sex, and treatment between chronic and nonchronic PFP patients.

CONCLUSIONS

The average Dutch general practitioner sees approximately 1.4 new child or adolescent with PFP per year. Overall management strategies were in concordance with current Dutch general practice guideline on nontraumatic knee problems. More insight should be gained in the population with chronic complaints.

The effects of a two-week neuromuscular intervention on biopsychosocial variables in people with patellofemoral pain: an observational study

Introduction

Patellofemoral pain (PFP) is common and predominately affects active populations. Altered biomechanics and psychosocial variables have been reported in people with PFP, but the effects of neuromuscular exercise on these variables is unknown. We aimed to investigate changes in biopsychosocial measures following a two-week neuromuscular intervention in people with PFP.

Materials and Methods

We measured pain (visual analogue scale), function (Kujala), activity level (Tegner), psychological well-being (Orebro), lower-limb isometric strength (handheld dynamometry), three-dimensional (3D) lower limb kinematics, and surface electromyography (sEMG), in people with PFP. 3D lower-limb kinematics and sEMG were synchronously sampled during step-up, step-down, and overground running. All measures were repeated after participants had completed a two-week neuromuscular intervention consisting of three exercises completed once per day, five days per week.

Results

18 participants completed pre/post testing (60% females, mean age 30.6 years ±7.0, height 173.4cm ±10.4, mass 70.2kg ±12.4, symptom duration 39.0 months ±58.8), with three of 21 participants lost to follow-up. Across all clinical measures (muscle onsets, muscle activation and kinematics), the 95% bootstrapped confidence intervals (CI) of the mean difference contained the null hypothesis following the two-week neuromuscular intervention, indicating no significant differences.

Conclusion

A two-week neuromuscular intervention did not change biomechanical or psychosocial measures in people with PFP. Interventions with a longer duration or greater load magnitude are required to fully evaluate the biopsychosocial mechanisms of effect for exercise in people with PFP.

Effects of Radiofrequency Diathermy Plus Therapeutic Exercises on Pain and Functionality of Patients with Patellofemoral Pain Syndrome: A Randomized Controlled Trial

Although consensus has been reached about the use of therapeutic exercise in patellofemoral pain syndrome, several techniques used worldwide such as radiofrequency diathermy could be useful as complementary therapy. The objective of this randomized controlled trial was to compare the effects of adding radiofrequency diathermy to therapeutic exercises in patients with patellofemoral pain syndrome. Fifty-six participants were randomly assigned either to radiofrequency diathermy plus therapeutic exercises group (n = 29) or therapeutic exercises group (n = 27). Both groups received the same therapeutic exercises, and the diathermy group additionally received monopolar dielectric diathermy for three weeks (5-3-2 weekly sessions). Data related to intensity of pain, probability of neuropathic pain, functionality, and range of movement of the knee were measured at baseline and three weeks after the intervention. Comparing pre-treatment and values obtained at the third week, significant improvements were found in intensity of pain, neuropathic pain, functionality, and range of motion in both groups (p < 0.05). The diathermy plus exercises group had significantly better intensity of pain than the control group at the end of the three weeks (p < 0.01). The addition of diathermy by emission of radiofrequency to the therapeutic knee exercise protocol is more effective than a therapeutic exercise protocol alone in the relief of intensity of pain in patients with patellofemoral pain in the immediate post-treatment follow-up compared with baseline scores.

Patellofemoral pain over time: Protocol for a prospective, longitudinal study investigating physical and non-physical features

Background

This is a protocol for a prospective longitudinal study that aims to investigate: (1) group-by-time changes over a minimum of 15 months follow-up in patellofemoral pain (PFP) symptoms, biomechanical, muscle function, pain processing, and psychological features; (2) the extent to which changes in biomechanical, muscle function, pain processing, and psychological features are associated with changes in self-reported pain, physical performance measures, self-reported function, health-related quality of life (HRQOL), and physical activity level.

Methods

Individuals with PFP (n = 144) and control individuals (n = 85) without PFP were assessed at baseline. Outcomes assessed included: 3D kinematics and kinetics during single leg squat, step-down and single leg hop; maximal torque and rate of torque development of hip abductors and knee extensors/flexors; force steadiness of hip abductors and knee extensors; anterior and lateral trunk endurance; pressure pain thresholds at the center of patella and contralateral shoulder; kinesiophobia (Tampa Scale for Kinesiophobia); pain catastrophizing (Pain Catastrophizing Scale); worst self-reported pain (Visual Analogue Scale); physical performance measures (Single Leg Hop Test and Forward Step-Down Test); self-reported function (Anterior Knee Pain Scale); HRQOL (Medical Outcome Short-Form 36), and physical activity level (Baecke's Questionnaire). Follow-up assessments will be identical to the baseline and will be performed after a minimum of 15 months. Generalized linear mixed model (GLMM) will be used to investigate group-by-time differences. Linear regression models will be used to determine the extent to which changes in biomechanical, muscle function, pain processing, and psychological features are associated with changes in self-reported pain, physical performance measures, self-reported function, HRQOL, and physical activity level.

Discussion

Physical and non-physical features have been previously associated with PFP. However, the present study will be the first to investigate their integrated evolution as part of the natural history of PFP and its progression. In doing so, we will be able to determine their behavior in the long-term, as well as how they prospectively associate with each other and with clinical outcomes. Ultimately, this will provide a greater understanding of predictors of long-term outcome and possible targets for interventions.

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.

A fused biometrics information graph convolutional neural network for effective classification of patellofemoral pain syndrome

Patellofemoral pain syndrome (PFPS) is a common, yet misunderstood, knee pathology. Early accurate diagnosis can help avoid the deterioration of the disease. However, the existing intelligent auxiliary diagnosis methods of PFPS mainly focused on the biosignal of individuals but neglected the common biometrics of patients. In this paper, we propose a PFPS classification method based on the fused biometrics information Graph Convolution Neural Networks (FBI-GCN) which focuses on both the biosignal information of individuals and the common characteristics of patients. The method first constructs a graph which uses each subject as a node and fuses the biometrics information (demographics and gait biosignal) of different subjects as edges. Then, the graph and node information [biosignal information, including the joint kinematics and surface electromyography (sEMG)] are used as the inputs to the GCN for diagnosis and classification of PFPS. The method is tested on a public dataset which contain walking and running data from 26 PFPS patients and 15 pain-free controls. The results suggest that our method can classify PFPS and pain-free with higher accuracy (mean accuracy = 0.8531 ± 0.047) than other methods with the biosignal information of individuals as input (mean accuracy = 0.813 ± 0.048). After optimal selection of input variables, the highest classification accuracy (mean accuracy = 0.9245 ± 0.034) can be obtained, and a high accuracy can still be obtained with a 40% reduction in test variables (mean accuracy = 0.8802 ± 0.035). Accordingly, the method effectively reflects the association between subjects, provides a simple and effective aid for physicians to diagnose PFPS, and gives new ideas for studying and validating risk factors related to PFPS.

Measurement Properties of Clinically Accessible Movement Assessment Tools for Analyzing Single-Leg Squats and Step-Downs: A Systematic Review

CONTEXT

Poor lower-extremity biomechanics are predictive of increased risk of injury. Clinicians analyze the single-leg squat (SLS) and step-down (SD) with rubrics and 2D assessments to identify these poor lower-extremity biomechanics. However, evidence on measurement properties of movement assessment tools is not strongly outlined. Measurement properties must be established before movement assessment tools are recommended for clinical use.

OBJECTIVE

The purpose of this study was to systematically review the evidence on measurement properties of rubrics and 2D assessments used to analyze an SLS and SD.

EVIDENCE ACQUISITION

The search strategy was developed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. The search was performed in PubMed, SPORTDiscus, and Web of Science databases. The COnsensus-based Standards for the selection of health Measurement INstruments multiphase procedure was used to extract relevant data, evaluate methodological quality of each study, score the results of each movement assessment, and synthesize the evidence.

EVIDENCE SYNTHESIS

A total of 44 studies were included after applying eligibility criteria. Reliability and construct validity of knee frontal plane projection angle was acceptable, but criterion validity was unacceptable. Reliability of the Chmielewski rubric was unacceptable. Content validity of the knee-medial-foot and pelvic drop rubrics was acceptable. The remaining rubrics and 2D measurements had inconclusive or conflicting results regarding reliability and validity.

CONCLUSIONS

Knee frontal plane projection angle is reliable for analyzing the SLS and SD; however, it does not serve as a substitute for 3D motion analysis. The Chmielewski rubric is not recommended for assessing the SLS or SD as it may be unreliable. Most movement assessment tools yield indeterminate results. Within the literature, standardized names, procedures, and reporting of movement assessment tool reliability and validity are inconsistent.

Measurement Properties of Clinically Accessible Movement Assessment Tools for Analyzing Jump Landings: A Systematic Review

CONTEXT

Lower-extremity musculoskeletal injury is commonly associated with poor movement patterns at the trunk, hip, and knee. Efforts have been focused on identifying poor lower-extremity movement using clinically friendly movement assessments, such as rubrics and 2D measures. Assessments used clinically or for research should have acceptable measurement properties, such as reliability and validity. However, the literature on reliability and validity of movement assessments to analyze jump landings has not been summarized.

OBJECTIVE

To systematically review measurement properties of rubrics and 2D measurements that aim to classify movement quality during jump landings.

EVIDENCE ACQUISITION

The search strategy was developed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. The search was performed in PubMed, SPORTDiscus, and Web of Science databases. The COnsensus-based Standards for the selection of health Measurement INstruments multiphase procedure was used to extract relevant data, evaluate methodological quality of each study, score the results of each movement assessment, and synthesize the evidence.

EVIDENCE SYNTHESIS

Twenty-two studies were included after applying eligibility criteria. Reliability and construct validity of the landing error scoring system were acceptable. Criterion validity of 2D knee flexion angle and medial knee displacement is acceptable. Reliability of 2D knee ankle separation ratio and knee frontal plane projection angle are acceptable.

CONCLUSION

The landing error scoring system is a valid way to determine poor movement quality and injury risk. Measures of 2D knee flexion angle and medial knee displacement are valid alternatives for 3D knee flexion angle and knee abduction moment, respectively. Knee ankle separation ratio and knee frontal plane projection angle are reliable but lack validity justifying their clinical use.

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.

Treatment of Patellofemoral Pain Syndrome with Dielectric Radiofrequency Diathermy: A Preliminary Single-Group Study with Six-Month Follow-Up

Background and Objectives: Notwithstanding patellofemoral pain syndrome (PFPS) being one of the most common causes of pain in the front of the knee in outpatients, few studies have shown the effects of radiofrequency on knee pain and function in this population. The aim of the present study was to determine whether outpatients diagnosed with PFPS obtained improvement in pain and function after treatment by dynamic application of monopolar dielectric diathermy by emission of radiofrequency (MDR). Materials and Methods: An experimental study was conducted with 27 subjects with PFPS. Subjects were treated with 10 sessions of MDR in dynamic application. The visual analogue scale (VAS), the Kujala scale, the DN4 questionnaire, the lower extremity function scale (LEFS), the range of movement (ROM) in knee flexion and extension and the daily drug intake were measured pre- and post-intervention and at the time of the follow-up (six months). Results: Statistically significant differences were found in pain perception (VAS: F_1,26 = 92.43, p < 0.000, ŋ² = 0.78 and DN4: F_1.26 = 124.15, p < 0.000, ŋ² = 0.82), as well as improvements in functionality (LEFS: F_1.26 = 72.42, p < 0.000, ŋ² = 0.74 and Kujala: F_1.26 = 40.37, p < 0.000, ŋ² = 0.61]) and in ROM (Flexion: F_1.26 = 63.15, p < 0.000, ŋ² = 0.71). No statistically significant changes in drug intake were found. Conclusions: The present study shows that the dynamic application of MDR seems effective in reducing pain and increasing functionality and knee flexion in patients with PFPS, after a follow-up of six months.

Effectiveness of Tele-Prescription of Therapeutic Physical Exercise in Patellofemoral Pain Syndrome during the COVID-19 Pandemic

The health crisis caused by COVID-19 has had a huge impact on the provision of physiotherapists’ services during the pandemic. Patellofemoral pain syndrome (PFPS) is a major health problem and one of the most common causes of pain in the front of the knee in outpatients. The objective was to evaluate the effectiveness of a therapeutic physical exercise (TPE) program supervised by a physiotherapist using telematic channels in reducing pain and disability in a sample of 54 patients with PFPS in the Physiotherapy Service of the San José de la Rinconada Health Center (Seville). Subjects were evaluated pre- and post-intervention (4 weeks—12 treatment sessions). An analysis was made of perceived pain—using the visual analog scale (VAS) and the DN4 neuropathic pain questionnaire—and functional balance—through the Kujala Score test and the Lower Extremity Functional Scale. The supervised TPE program in patients with PFPS produced a reduction in pain: VAS F_{1, 52} = 8.68 (p = 0.005) η² = 0.14 and DN4: F_{1, 52} = 69.94 (p = 0.000) η² = 0.57; and in Lower Extremity Functional Scale (LEFS) disability: F_{1, 52} = 19.1 (p = 0.000) η² = 0.27 and KUJALA: F_{1, 52} = 60.28 (p = 0.000) η² = 0.54, which was statistically significant (p = 0.000 for p < 0.05). Hence, the TPE program presented was effective in reducing pain and disability in patients with PFPS.

High-frequency follow-up studies in musculoskeletal disorders: a scoping review

OBJECTIVES

This scoping review identifies research in musculoskeletal disorders that uses high frequency follow-up of symptoms. The aim was to investigate whether symptom variability is investigated as a predictor of disease outcome and how intensive follow-up methods are used in musculoskeletal research.

METHODS

Embase, MEDLINE and PsycInfo were searched using OVID, and the Institute of Electrical and Electronic Engineers was also searched using the Institute of Electrical and Electronic Engineers Xplore search engine. Studies were systematically reviewed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses, but no meta-analysis was done because the priority in this study is to identify gaps in available literature.

RESULTS

Twenty-one papers were included. There was a mean of 54 patients per study (s.d. of 27.7). Two-thirds of the papers looked at how a symptom influences another in the short-term (subsequent assessment in the same day or next day), but none looked at the long-term. Only one study considered symptom variability investigating how higher variability in pain (defined by the s.d.) is associated with higher average pain severity and lower average sleep quality.

CONCLUSION

The methodology of musculoskeletal disorder research has changed from completing paper booklets to using electronic data capture (smartphones). There has also been a trend of collecting more intensive longitudinal data, but very little research utilizes these data to look at how symptom variability affects symptom outcomes. This demonstrates a gap in research where furthering understanding of this will help clinicians decide on the most important symptom to address in future patients.

Monopolar dielectric diathermy by emission of radiofrequency in Patellofemoral pain. A single-blind-randomized clinical trial

Despite the high incidence of patellofemoral pain syndrome (PFPS), few studies show the effects of radiofrequency on pain and functionality in these patients. For this reason, the aim of this study was to determine the efficacy of monopolar dielectric diathermy by emission of radiofrequency (MDR) in dynamic applications aimed at treating pain and improving function in patients with PFPS. For this purpose, a single-blind randomized clinical trial was conducted. Eighty-four participants with PFPS were evenly divided into an experimental group (EG) and a control group (CG). All subjects receive 10 min of daily home exercises along 3 weeks, and in addition, the subjects of the EG received 10 sessions based on the dynamic application of MDR. Variables measured included Visual Analogue Scale (VAS), DN4 questionnaire, Lower Extremity Functionality Scale (LEFS), Kujala scale, Range of Movement (ROM) in knee flexion and extension and drug intake. The EG showed a statistically significant reduction in pain (VAS = 4.8 [5.5-4.1] [p < .001]; DN4 = 3.8 [4.4-3.2] [p < .001]), and an increase in functionality (LEFS = 16 [19-13] [p < .001]; Kujala = 19 [23-14] [p < .001]) and in ROM (flexion 18º [21º-16º] [p < .001]). No statistically significant changes in drug intake were found. Based on this data, the dynamic application of MDR seems effective in reducing pain and increasing functionality and flexion in patients with PFPS. Diathermy by emission of radiofrequency could be recommended as complement or main therapy in the treatment of PFPS.

Predictors of Pain, Function, and Change in Patellofemoral Pain

BACKGROUND

Identification of factors predictive of outcome and change is important to improve treatment for patellofemoral pain (PFP). Few studies have examined the predictive value of psychological factors in PFP, although they have been reported to be important predictors in other musculoskeletal pain conditions.

PURPOSE

To evaluate predictors of pain, function, and change 1 year after an exercise-based intervention in PFP.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

In sum, 112 patients were recruited to a randomized controlled trial; 98 attended 1-year follow-up. There were no between-group differences in the trial; thus, the material was analyzed as 1 cohort. Nine baseline factors-sex, bilateral pain, worst pain, pain duration, Anterior Knee Pain Scale (AKPS), kinesiophobia, anxiety and depression, self-efficacy, and number of pain sites throughout the body-were investigated for their predictive ability on outcome at 1 year (AKPS, worst pain) and for change at 1 year (global change score, change in AKPS, and change in worst pain). Multivariable linear regression models with stepwise backward removal method were used to find predictors of poor outcome.

RESULTS

Number of pain sites at baseline was a significant predictor of worse outcome for AKPS (B = -2.7; 95% CI, -4.0 to -1.3; P < .01), worst pain (B = 0.5; 95% CI, 0.2-0.8; P < .01), global change (B = -0.8; 95% CI, -1.2 to -0.5; P < .01), change in AKPS (B = -2.7; 95% CI, -4.0 to -1.3; P < .01), and change in worst pain (B = 0.5, 95% CI, 0.2-0.8; P < .01) at 1 year. Baseline scores for AKPS and worst pain predicted respective 1-year levels and change scores (P < .01). Lower self-efficacy and male sex predicted less global change (P < .01). Longer pain duration predicted final score and change score for worst pain (P < .01). The predictive models had reasonable fit with adjusted R² from 0.22 to 0.35.

CONCLUSION

Higher number of pain sites throughout the body was a consistent predictor of poor outcome and less change at 1 year. Baseline levels for AKPS and worst pain predicted respective final scores and change scores.

REGISTRATION

NCT02114294 ( ClinicalTrials.gov identifier).

Association Between Self-reported Measures, Physical Examination, and Early Magnetic Resonance Imaging Signs of Osteoarthritis in Patients With Patellofemoral Pain

BACKGROUND

Structural abnormalities associated with osteoarthritis (OA) are found in some patients with patellofemoral pain (PFP).

OBJECTIVES

To investigate the association between early signs of OA on magnetic resonance imaging (MRI) and characteristics from self-reported measures and physical examination in patients with PFP.

METHODS

This exploratory study included data from patients with PFP from a previously published cross-sectional case-control study (n = 64; 55% female; mean ± SD age, 23.4 ± 7.0 years). Structural OA features (osteophytes, bone marrow lesions, cartilage defects, Hoffa synovitis, patellar tendon abnormalities) and quantitative T2 measurements of cartilage composition were extracted from MRI. Associations between characteristics from self-reported measures (pain at rest, pain during stair walking, knee function, duration of complaints, hours of sports participation each week), physical examination (crepitus, quadriceps strength), and early MRI signs of OA were assessed.

RESULTS

Symptom duration was associated with bone marrow lesions in the patella (odds ratio [OR] = 1.1; 95% confidence interval [CI]: 1.0, 1.2). Sports participation (hours per week) was inversely associated with patellar tendon abnormalities on MRI (OR = 0.8; 95% CI: 0.6, 1.0). Crepitus and bilateral nature of the complaints were associated with minor patellar cartilage defects (OR = 12.0; 95% CI: 2.3, 63.6 and OR = 7.6; 95% CI: 1.1, 53.8, respectively). There were no significant associations between clinical characteristics and cartilage T2 relaxation time.

CONCLUSION

Presence of crepitus, bilateral complaints, a long PFP symptom duration, and reduced weekly sport participation were associated with early signs of OA in a young PFP population.

LEVEL OF EVIDENCE

Etiology, level 2c. J Orthop Sports Phys Ther 2019;49(9):634-639. Epub 10 Jul 2019. doi:10.2519/jospt.2019.8889.

Pressure pain thresholds in adults with patellofemoral pain and patellofemoral joint osteoarthritis: a case-control study

Background and aims

Patellofemoral pain (PFP) and patellofemoral joint osteoarthritis (PFJOA) are common non-self-limiting conditions causing significant pain and disability. The underlying pain pathologies lack consensus with evidence suggesting reduced pressure pain thresholds (PPTs) in adolescent females with PFP and individuals with knee osteoarthritis. A paucity of evidence exists for mixed-sex adults with PFP and PFJOA in isolation. Exploring if pain sensitisation is a dominant feature of PFP and PFJOA may have important implications for the delivery of a patient centred management approach. The primary aim was to measure local and remote PPTs in PFP and PFJOA patients compared to matched controls. Secondary aims were to evaluate the relationship between PPTs and (1) condition severity and (2) knee function.

Methods

13 PFP patients plus 20 matched controls and 15 PFJOA patients plus 34 matched controls were recruited from a UK mixed-sex adult population. Controls were matched on age, sex and activity level. Demographic details, Tegner activity level score, symptom duration, condition severity (Kujala and KOOS-PF scores for PFP and PFJOA, respectively) and knee function (Modified Whatman score rating of five single leg squats) were recorded. PPTs were measured at six sites: five local around the knee, one remote on the contralateral leg. Between-group differences were tested using a two-way mixed model analysis of variance with repeated measures. Strength of association between PPTs and condition severity and knee function were tested using Spearman’s rank order correlation.

Results

No statistically significant difference in PPTs were observed between the PFP patients [F(1,31) = 0.687, p = 0.413, η2 = 0.022] or PFJOA patients [F(1,47) = 0.237, p = 0.629, η2 = 0.005] and controls. Furthermore, no correlation was found between PPTs and condition severity or knee function in PFP or PFJOA (p > 0.05).

Conclusions

Results suggest mechanical pain sensitisation is not a dominant feature of UK mixed-sex adults with PFP or PFJOA.

Implications

PFP and PFJOA remain persistent pain complaints which may not be well explained by objective measures of sensitivity such as PPTs. The findings suggest that peripheral pain processing changes leading to pain sensitisation is not a key feature in PFP or PFJOA. Instead the underlying pain pathway is likely to remain primary nociceptive, possibly with a subgroup of patients who experience pain sensitisation and might benefit from a more targeted management approach.

Treatment Success of Hip and Core or Knee Strengthening for Patellofemoral Pain: Development of Clinical Prediction Rules

CONTEXT

  Patellofemoral pain (PFP) is a common injury that interferes with quality of life and physical activity. Clinical subgroups of patients may exist, one of which is caused by proximal muscle dysfunction.

OBJECTIVES

  To develop clinical prediction rules that predict a positive outcome after either a hip and core- or knee-focused strengthening program for individuals with PFP.

DESIGN

  Secondary analysis of data from a randomized control trial.

SETTING

  Four university laboratories.

PATIENTS OR OTHER PARTICIPANTS

  A total of 199 participants with PFP.

INTERVENTION(S)

  Participants were randomly allocated to either a hip and core-focused (n = 111) or knee-focused (n = 88) rehabilitation group for a 6-week program.

MAIN OUTCOME MEASURE(S)

  Demographics, self-reported knee pain (visual analog scale) and function (Anterior Knee Pain Scale), hip strength, abdominal muscle endurance, and hip range of motion were evaluated at baseline. Treatment success was defined as a decrease in visual analog scale score by ≥2 cm or an increase in the Anterior Knee Pain Scale score by ≥8 points or both. Bivariate relationships between the outcome (treatment success) and the predictor variables were explored, followed by a forward stepwise logistic regression to predict a successful outcome.

RESULTS

  Patients with more pain, better function, greater lateral core endurance, and less anterior core endurance were more likely to have a successful outcome after hip and core strengthening (88% sensitivity and 54% specificity). Patients with lower weight, weaker hip internal rotation, stronger hip extension, and greater trunk-extension endurance were more likely to have success after knee strengthening (82% sensitivity and 58% specificity).

CONCLUSION

  The patients with PFP who have more baseline pain and yet maintain a high level of function may experience additional benefit from hip and core strengthening. The clinical prediction rules from this study remain in the developmental phase and should be applied with caution until externally validated.

How to manage patellofemoral pain - Understanding the multifactorial nature and treatment options

Patellofemoral pain (PFP) is one of the most prevalent conditions within sports medicine, orthopaedic and general practice settings. Long-term treatment outcomes are poor, with estimates that more than 50% of people with the condition will report symptoms beyond 5 years following diagnosis. Additionally, emerging evidence indicates that PFP may be on a continuum with patellofemoral osteoarthritis. Consensus of world leading clinicians and academics highlights the potential benefit of delivering tailored interventions, specific to an individual's needs, to improve patient outcome. This clinical masterclass aims to develop the reader's understanding of PFP aetiology, inform clinical assessment and increase knowledge regarding individually tailored treatment approaches. It offers practical application guidance, and additional resources, that can positively impact clinical practice.

Is hip strengthening the best treatment option for females with patellofemoral pain? A randomized controlled trial of three different types of exercises

OBJECTIVE

To evaluate the effect of three types of exercise intervention in patients with patellofemoral pain and to verify the contributions of each intervention to pain control, function, and lower extremity kinematics.

METHODS

A randomized controlled, single-blinded trial was conducted. Forty women with patellofemoral pain were randomly allocated into four groups: hip exercises, quadriceps exercises, stretching exercises and a control group (no intervention). Pain (using a visual analog scale), function (using the Anterior Knee Pain Scale), hip and quadriceps strength (using a handheld isometric dynamometer) and measuring lower limb kinematics during step up and down activities were evaluated at baseline and 8 weeks post intervention.

RESULTS

All treatment groups showed significant improvements on pain and Anterior Knee Pain Scale after intervention with no statistically significant differences between groups except when compared to the control group. Only hip and quadriceps groups demonstrated improvements in muscle strength and knee valgus angle during the step activities.

CONCLUSION

Hip strengthening exercises were not more effective for pain relief and function compared to quadriceps or stretching exercises in females with patellofemoral pain. Only hip and quadriceps groups were able to decrease the incidence of dynamic valgus during step-down activity. This study was approved by Brazilian Clinical Trials Registry registration number: RBR-6tc7mj (http://www.ensaiosclinicos.gov.br/rg/RBR-6tc7mj/).

Disparities in Outcomes for Blacks versus Whites Undergoing Total Hip Arthroplasty: A Systematic Literature Review

Objective.

Total hip replacement (THA) surgery is a successful procedure, yet blacks in the United States undergo THA less often and reflect poorer outcomes than whites. The purpose of this study is to systematically review the literature on health-related quality of life after THA, comparing blacks and whites.

Methods.

A librarian-assisted search was performed in Medline through PubMed, Embase, and Cochrane Library on February 27, 2017. Original cohort studies examining pain, function, and satisfaction in blacks and whites 1 year after elective THA were included. Using the Patient/Population–Intervention–Comparison/Comparator–Outcome (PICO) process format, our population of interest was US black adults, our intervention was elective THA, our comparator was white adults, and our outcomes of interest were pain, function, and satisfaction after elective THA. The protocol was registered under the PROSPERO international register, and the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines were followed.

Results.

Of the articles, 4739 were screened by title, 180 by abstract, 25 by full text, and 4 remained for analysis. The studies represented 1588 THA patients, of whom 240 (15%) were black. All studies noted more pain and worse function for blacks; although differences were statistically significant, they were not clinically significant. One study sought and identified less satisfaction for blacks after THA, and 1 study showed worse fear and anxiety scores in blacks.

Conclusion.

When measured, there are small differences in THA outcomes between blacks and whites, but most studies do not analyze/collect race. Future studies should address the effect of race and socioeconomic factors on healthcare disparities.

Incidence and prevalence of patellofemoral pain: A systematic review and meta-analysis

BACKGROUND

Patellofemoral pain is considered one of the most common forms of knee pain, affecting adults, adolescents, and physically active populations. Inconsistencies in reported incidence and prevalence exist and in relation to the allocation of healthcare and research funding, there is a clear need to accurately understand the epidemiology of patellofemoral pain.

METHODS

An electronic database search was conducted, as well as grey literature databases, from inception to June 2017. Two authors independently selected studies, extracted data and appraised methodological quality. If heterogeneous, data were analysed descriptively. Where studies were homogeneous, data were pooled through a meta-analysis.

RESULTS

23 studies were included. Annual prevalence for patellofemoral pain in the general population was reported as 22.7%, and adolescents as 28.9%. Incidence rates in military recruits ranged from 9.7-571.4/1,000 person-years, amateur runners in the general population at 1080.5/1,000 person-years and adolescents amateur athletes 5.1%-14.9% over 1 season. One study reported point prevalence within military populations as 13.5%. The pooled estimate for point prevalence in adolescents was 7.2% (95% Confidence Interval: 6.3%-8.3%), and in female only adolescent athletes was 22.7% (95% Confidence Interval 17.4%-28.0%).

CONCLUSION

This review demonstrates high incidence and prevalence levels for patellofemoral pain. Within the context of this, and poor long term prognosis and high disability levels, PFP should be an urgent research priority.

PROSPERO REGISTRATION

CRD42016038870.

Foot exercises and foot orthoses are more effective than knee focused exercises in individuals with patellofemoral pain

OBJECTIVES

To examine the effect of knee targeted exercises compared to knee targeted exercises combined with foot targeted exercises and foot orthoses in patients with patellofemoral pain.

DESIGN

Forty adult individuals (28 women, 12 men) diagnosed with patellofemoral pain and screened for excessive calcaneal eversion were randomized to knee targeted exercises or knee targeted exercises combined with foot targeted exercise and orthoses.

METHODS

The knee targeted exercises were prescribed during three supervised consultations. Individuals were instructed to perform the exercises 3 times per week during a 12-week period. The foot targeted exercises were prescribed for 2 times per week for 12 weeks with one session per week being supervised by a physiotherapist. The primary outcome was the subscale "pain" in the Knee Injury and Osteoarthritis Outcome Score (KOOS) at 4 months.

RESULTS

Individuals randomized to knee targeted exercises combined with foot targeted exercises and foot orthoses had 8.9 points (95%CI: 0.4; 17.4) - NNT=3 (2-16) larger improvement in KOOS pain at the primary endpoint.

CONCLUSIONS

The addition of foot targeted exercises and foot orthoses for 12 weeks was more effective than knee targeted exercises alone in individuals with patellofemoral pain. The effect was apparent after 4 months, but not significantly different after 12 months.

Current management strategies for patellofemoral pain: an online survey of 99 practising UK physiotherapists

BACKGROUND

Patellofemoral pain (PFP) is considered one of the commonest forms of knee pain. This study aimed to identify how physiotherapists in the United Kingdom (UK) currently manage patellofemoral pain (PFP), particularly in relation to exercise prescription, and response to pain.

METHODS

An anonymous survey was designed with reference to previous surveys and recent systematic reviews. Practising UK physiotherapists who treat patients with PFP were invited to take part via an invitation email sent through professional networks, the 'interactive Chartered Society of Physiotherapy (iCSP)' message board, and social media (Twitter). Descriptive statistics were used to analyse the data.

RESULTS

A total of 99 surveys were completed. Responders reported a wide range of management strategies, including a broad selection of type and dose of exercise prescription. The five most common management strategies chosen were: closed chain strengthening exercises (98%); education and advice (96%); open chain strengthening exercises (76%); taping (70%) and stretches (65%). Physiotherapists with a special interest in treating PFP were statistically more likely to manage patients with orthotics (P = 0.02) and bracing (P = 0.01) compared to physiotherapists without a special interest. Approximately 55% would not prescribe an exercise if it was painful. Thirty-one percent of physiotherapists would advise patients not to continue with leisure and/or sporting activity if they experienced any pain.

CONCLUSION

Current UK practice in the management strategies of PFP is variable. Further high quality research on which to inform physiotherapy practice is warranted for this troublesome musculoskeletal condition.

Longitudinal bone, muscle and adipose tissue changes in physically active subjects - sex differences during adolescence and maturity

OBJECTIVES

To explore changes in bone, muscle and adipose tissue composition in athletes with high physical activity levels at different stages of life.

METHODS

Thigh MRIs were acquired at baseline and 2-year follow-up for 20 young (16±1 years) and 20 mature (46±5 years) athletes (10 males, 10 females, respectively). Longitudinal changes in cross-sectional areas (CSAs) of femoral bone, quadriceps muscle, and thigh subcutaneous (SCF) and intermuscular (IMF) adipose tissue were evaluated.

RESULTS

Adolescent males displayed significant muscle (+5.0%, 95%CI: 0.8, 9.2) and bone growth (+2.9%, 95%CI: 1.3, 4.5), whereas adolescent females did not (muscle: +0.8%, 95%CI: -2.2, 3.8; bone: +1.9%, 95%CI: -2.1, 5.6). Adolescent and mature females showed significant SCF increases (+11.0%, 95%CI: 0.9, 21.1 and +6.0%, 95%CI: 0.6, 11.4, respectively), whereas adolescent and mature males did not (+7.2%, 95%CI: -8.0, 22.5 and +1.5%, 95%CI: -9.7, 11.8, respectively). Muscle and bone changes were highly correlated in adolescent males (r=0.66), mature males (r=0.75) and mature females (r=0.68) but not in adolescent females (r=-0.11).

CONCLUSIONS

The results suggest sex-specific patterns of age-related change in bone, muscle and adipose tissue, and tight coupling of bone and muscle growth. Sex-specific bone-muscle-adipose tissue relationships may have implications for understanding sex differences in fracture risk.

Factors Affecting Length of Stay in Adult Outpatient Physical Rehabilitation: A Scoping Review of the Literature

PURPOSE

To identify factors affecting length of stay (LOS) for adults participating in outpatient physical or occupational therapy programmes.

METHOD

A scoping review of the literature was conducted using the Ovid MEDLINE, EMBASE, CINAHL, AMED, and Cochrane Library databases.

RESULTS

A total of 19 articles were retained from the search, and 2 additional articles were retrieved from grey literature (i.e., non-published sources). Personal factors affecting LOS are age and sex, both of which had inconsistent effects on LOS, and communication, language, physical, and cognitive difficulties, for which higher levels of function were generally associated with shorter LOS. Institutional factors affecting LOS were location, interdisciplinary communication, number of disciplines involved, and type of rehabilitation setting. Finally, two clinician-related factors-fewer treatment goals and a selection of evidence-informed treatment techniques-were associated with shorter LOS.

CONCLUSIONS

Research on factors affecting adult outpatient rehabilitation LOS is limited and inconsistent. A preliminary list of LOS factors was produced, but this topic should be further explored with the collaboration of researchers and clinical institutions.

Analysis of patient-reported anterior knee pain scale: implications for scale development in children and adolescents

PURPOSE

The purpose of this investigation was to estimate and document the reliability and validity of the Anterior Knee Pain Scale (AKPS) and to estimate its relative prediction accuracy of anterior knee pain in young females.

METHODS

Data from a prospective, epidemiologic study to diagnose patellofemoral knee pain among female athletes (n = 499) using the Anterior Knee Pain Scale (AKPS). Data were treated in 4 phases (descriptive phase, reliability phase, scale refinement phase) and a final validation stage that was focused on an effort to test and document the validation of the AKPS short form and perform head-to-head comparisons of the 6-item short form with the original, 13-item form.

RESULTS

The AKPS was reduced from 13 items (αCoeff = 0.77, σSEM = 0.004) to 6 items (αCoeff = 0.78, σSEM = 0.004). Point-biserial correlations with patellofemoral pain diagnosis were comparable: r [498] = 0.70 (R(2) = 0.49, short form) and r [498] = 0.71 (R(2) = 0.51, long form), as was sensitivity: 84% (short form) and 80% (long form), and specificity: 89% (short form) and 90% (long form; AUC = 0.94 both).

CONCLUSION

The current analyses indicate that a subset of measures from the AKPS is responsive to patellofemoral pain symptoms and may support screening for related diagnoses. A simpler and quicker scale optimized for diagnostic accuracy could reduce the demand on patients, clinicians and research teams focused on the identification and management of patellofemoral pain.

LEVEL OF EVIDENCE

III.

Can we predict which patients with patellofemoral pain are more likely to benefit from exercise therapy? A secondary exploratory analysis of a randomized controlled trial

STUDY DESIGN

Secondary exploratory analysis of a randomized controlled trial comparing supervised exercise therapy to usual care in patients with patellofemoral pain (PFP).

OBJECTIVE

To explore which patients with PFP are more likely to benefit from exercise therapy.

BACKGROUND

Patellofemoral pain is a common condition for which exercise therapy is effective in reducing pain and improving function. However, not all patients benefit from exercise therapy.

METHODS

The present study explored patient characteristics that might interact with treatment effects of PFP in 131 patients treated with usual care or exercise therapy. These characteristics were tested for interaction with treatment in a regression analysis. The primary outcomes were function and pain on activity at a 3-month follow-up.

RESULTS

None of the tested variables had a significant interaction with treatment. A positive trend was seen for females with PFP: they were more likely to report higher function scores with exercise therapy than with usual care compared to males with PFP (β = 12.1; 95% confidence interval: 0.23, 24.0; P = .05). A positive trend was seen for patients with a longer duration of complaints (greater than 6 months); they were more likely to report higher function scores and to have less pain on activity with exercise therapy than with usual care compared to those with a shorter duration of complaints (β = 12.3; 95% confidence interval: -0.08, 24.7; P = .05 and β = -1.74; 95% confidence interval: -3.90, 0.43; P = .12, respectively).

CONCLUSION

Two factors, sex and duration of complaints, may have a predictive value for response to exercise therapy at 3-month follow-up. Due to the exploratory design of the study, future research should confirm this tendency.

Comparison of frequency and time domain electromyography parameters in women with patellofemoral pain

BACKGROUND

Despite its high incidence, patellofemoral pain etiology remains unclear. No prior study has compared surface electromyography frequency domain parameters and surface electromyography time domain variables, which have been used as a classic analysis of patellofemoral pain.

METHODS

Thirty one women with patellofemoral pain and twenty eight pain-free women were recruited. Each participant was asked to descend a seven step staircase and data from five successful trials were collected. During the task, the vastus medialis and vastus lateralis muscle activities were monitored by surface electromyography. The data were processed and analyzed in four variables of the frequency domain (median frequency, low, medium and high frequency bands) and three time domain variables (Automatic, Cross-correlation and Visual Onset between the vastus medialis and vastus lateralis muscles). Reliability, Receiver Operating Characteristic curves and regression models were performed.

FINDINGS

The medium frequency band was the most reliable variable and different between the groups for both muscles, also demonstrated the best values of sensitivity and sensibility, 72% and 69% for the vastus medialis and 68% and 62% for the vastus lateralis, respectively. The frequency variables predicted the pain of individuals with patellofemoral pain, 26% for the vastus medialis and 20% for the vastus lateralis, being better than the time variables, which achieved only 7%.

INTERPRETATION

The frequency domain parameters presented greater reliability, diagnostic accuracy and capacity to predict pain than the time domain variables during stair descent and might be a useful tool to diagnose individuals with patellofemoral pain.

Predictors for identifying patients with patellofemoral pain syndrome responding to femoral nerve mobilization

OBJECTIVE

To identify the predictors for successful neurodynamic management in patients with patellofemoral pain syndrome.

DESIGN

Prospective cohort, prediction rule study.

SETTING

Hospital.

PARTICIPANTS

Patients with patellofemoral pain syndrome (N=51) underwent clinical examination and measurement of physical parameters, including femoral slump test, lower-extremity alignment, flexibility and muscle strength, and functional level.

INTERVENTION

Patients received 6 treatment sessions of femoral nerve mobilization within 2 weeks.

MAIN OUTCOME MEASURES

Pain level during functional testing was assessed before and after the first and sixth session of treatment. Patients were then grouped into responder and nonresponder groups. Criteria for the responder group was a pain score decrease ≥50% or Global Rating Scale score ≥4. Chi-square and independent t tests were used to identify potential variables with a significance level of .10, and stepwise logistic regression was used to find predictors with a significance level of .05.

RESULTS

Twenty-five patients responded to the initial treatment (immediate effect), and 28 patients responded after 6 sessions (longer-term effect). A positive femoral slump test was identified as the predictor for the immediate treatment effect. The prediction factors for the longer-term effect included responding to femoral nerve mobilization the first time and a bilateral difference in hip extension angles. Application of the clinical predictors improved the success rate to 90% for 1 treatment session and 93% for 6 treatment sessions.

CONCLUSIONS

Clinicians could use the positive femoral slump test and a bilateral difference in hip extension angles during the femoral slump test to determine whether or not patients with patellofemoral pain syndrome might benefit from femoral nerve mobilization.

Successful conservative treatment of patients with MRI-verified meniscal lesions

PURPOSE

To follow a prospective cohort of consecutive patients with MRI-verified meniscal lesions to identify pre-treatment prognostic factors for long-term results following arthroscopic or conservative treatment.

METHODS

In the course of 1 year, 291 patients with knee pain and clinically suspected of meniscal lesion were referred to the regional orthopaedic division and subjected to MRI and clinical examination by an experienced surgeon. Patients with MRI-verified meniscal lesions were treated according to an arthroscopy restrictive strategy meaning that treatment was initiated by conservative treatment. Arthroscopy was only performed if satisfying pain relief was not obtained. The Lysholm score and Knee Injury and Osteoarthritis Outcome Score (KOOS) were obtained at baseline and after 12-24 months. A multiple linear regression model was used to investigate which pre-treatment prognostic factors were associated with improvement in the KOOS subscale pain from baseline to follow-up.

RESULTS

An MRI-verified meniscal lesion was found in 185 patients (64%). Among these, 58% were treated successfully by conservative treatment. A high KOOS subscale pain score at baseline was associated with less improvement from baseline to follow-up. Bucket-handle lesions were associated with larger improvement from baseline to follow-up compared to flap-tear lesions.

CONCLUSION

MRI findings and clinical status measured by KOOS subscale pain are prognostic for improvement among patients treated for MRI-verified meniscal lesions. Good results were observed for both operative and conservative treatment. The success rate for conservative treatment was 58%.

LEVEL OF EVIDENCE

Prospective cohort study, Level II.

Sex differences in trunk, pelvis, hip and knee kinematics and eccentric hip torque in adolescents

BACKGROUND

Adolescents have a high incidence of knee joint dysfunctions, with up to 28% of adolescents reporting knee pain. Although adolescent females have a greater incidence of knee injuries in comparison to males, few studies conducted biomechanical evaluations in this population aiming to identify sex differences. If trunk and/or lower limb biomechanical impairments are identified in female adolescents, the implementation of early interventions for injury prevention will be better justified. The purpose of this study was to compare the trunk, pelvis, hip and knee kinematics during a single-leg squat task, as well as the isokinetic eccentric hip torque, between male and female healthy adolescents.

METHODS

Forty-four healthy adolescents were divided into two groups, group of males (n=22) and group of females (n=22). Kinematics during single-leg squat were assessed using a electromagnetic tracking system. For the evaluation of eccentric hip torque in the three planes an isokinetic dynamometer was used. Group differences were assessed using a one-way multivariate analysis of variance.

FINDINGS

Results showed that adolescent females presented greater hip adduction, hip external rotation and knee abduction, as well as smaller trunk flexion during single-leg squat in comparison to males. Additionally, adolescent females showed smaller isokinetic eccentric hip torque normalized by body mass in all planes in comparison to males.

INTERPRETATION

These sex differences in terms of trunk/lower limb kinematics and eccentric hip torque generation might play an important role in the greater incidence of overuse knee injuries observed in adolescent females.

Measurement properties of patient-reported outcome measures (PROMS) in Patellofemoral Pain Syndrome: a systematic review

This systematic review investigated the measurement properties of disease-specific patient-reported outcome measures used in Patellofemoral Pain Syndrome. Two independent reviewers conducted a systematic search of key databases (MEDLINE, EMBASE, AMED, CINHAL+ and the Cochrane Library from inception to August 2013) to identify relevant studies. A third reviewer mediated in the event of disagreement. Methodological quality was evaluated using the validated COSMIN (Consensus-based Standards for the Selection of Health Measurement Instruments) tool. Data synthesis across studies determined the level of evidence for each patient-reported outcome measure. The search strategy returned 2177 citations. Following the eligibility review phase, seven studies, evaluating twelve different patient-reported outcome measures, met inclusion criteria. A 'moderate' level of evidence supported the structural validity of several measures: the Flandry Questionnaire, Anterior Knee Pain Scale, Functional Index Questionnaire, Eng and Pierrynowski Questionnaire and Visual Analogue Scales for 'usual' and 'worst' pain. In addition, there was a 'Limited' level of evidence supporting the test-retest reliability and validity (cross-cultural, hypothesis testing) of the Persian version of the Anterior Knee Pain Scale. Other measurement properties were evaluated with poor methodological quality, and many properties were not evaluated in any of the included papers. Current disease-specific outcome measures for Patellofemoral Pain Syndrome require further investigation. Future studies should evaluate all important measurement properties, utilising an appropriate framework such as COSMIN to guide study design, to facilitate optimal methodological quality.

Assessing the influence of treating therapist and patient prognostic factors on recovery from axial pain

BACKGROUND

Limited research exists regarding the influence of a treating physical therapist on patient recovery (deemed therapist effects). Recent randomized clinical trials data provide an indication of small therapist effects for manual therapy; however, the extent to which therapist effects exist in the average outpatient facility is not clear. Moreover, patient-related prognostic factors, like fear-avoidance or pain duration, are important to consider since these may also influence the extent of therapist effects.

OBJECTIVE

To assess therapist effects and the influence of patient prognostic factors on recovery from axial pain in an outpatient orthopedic physical therapy facility.

METHODS

Clinical data were collected from consecutive patients with musculoskeletal neck and low back pain. Patient outcomes included pain intensity (visual analog scale) and functional measure (CareConnections functional outcomes index) scores. Therapist effects estimates and the influence of intake fear-avoidance (fear-avoidance beliefs questionnaire) and pain duration (days) were examined using multilevel linear or regression modeling.

RESULTS

A total of 258 patients (160 females; mean age 46.4±14.9 years) completed physical therapy and the required outcome measures. Five physical therapists (1-13 years of experience, mean 5.8 years) provided treatment. Therapists effects did not exist for discharge pain intensity or function after accounting for intake scores (P > 0.05). Further, therapist experience did not influence patient outcomes. Patient prognostic factors of fear-avoidance and pain duration did not influence therapists effects on the same patient outcome measures (P > 0.05).

DISCUSSION

Preliminary findings suggest that there are no major differences in patient outcome based on either the individual therapist (therapist effect) or therapist experience in this type of PT setting. Established prognostic factors had no influence on therapist effects for this cohort. Future analyses should consider intrinsic therapist factors (beliefs, equipoise), specific treatment parameters (dosage, type), and other patient prognostic factors (psychological, age, expectation, satisfaction) to further elucidate the influence of therapist effects.

High prevalence of daily and multi-site pain--a cross-sectional population-based study among 3000 Danish adolescents

Background

Daily pain and multi-site pain are both associated with reduction in work ability and health-related quality of life (HRQoL) among adults. However, no population-based studies have yet investigated the prevalence of daily and multi-site pain among adolescents and how these are associated with respondent characteristics. The purpose of this study was to investigate the prevalence of self-reported daily and multi-site pain among adolescents aged 12–19 years and associations of almost daily pain and multi-site pain with respondent characteristics (sex, age, body mass index, HRQoL and sports participation).

Methods

A population-based cross-sectional study was conducted among 4,007 adolescents aged 12–19 years in Denmark. Adolescents answered an online questionnaire during physical education lessons. The questionnaire contained a mannequin divided into 12 regions on which the respondents indicated their current pain sites and pain frequency (rarely, monthly, weekly, more than once per week, almost daily pain), characteristics, sports participation and HRQoL measured by the EuroQoL 5D. Multivariate regression was used to calculate the odds ratio for the association between almost daily pain, multi-site pain and respondent characteristics.

Results

The response rate was 73.7%. A total of 2,953 adolescents (62% females) answered the questionnaire. 33.3% reported multi-site pain (pain in >1 region) while 19.8% reported almost daily pain. 61% reported current pain in at least one region with knee and back pain being the most common sites. Female sex (OR: 1.35-1.44) and a high level of sports participation (OR: 1.51-2.09) were associated with increased odds of having almost daily pain and multi-site pain. Better EQ-5D score was associated with decreased odds of having almost daily pain or multi-site pain (OR: 0.92-0.94).

Conclusion

In this population-based cohort of school-attending Danish adolescents, nearly two out of three reported current pain and, on average, one out of three reported pain in more than one body region. Female sex, and high level of sports participation were associated with increased odds of having almost daily pain and multi-site pain. The study highlights an important health issue that calls for investigations to improve our understanding of adolescent pain and our capacity to prevent and treat this condition.

Lower mechanical pressure pain thresholds in female adolescents with patellofemoral pain syndrome

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

To compare pressure pain thresholds (PPTs) between adolescent females diagnosed with patellofemoral pain syndrome (PFPS) and gender- and age-matched controls without musculoskeletal pain.

BACKGROUND

PFPS is prevalent among adolescents and may be associated with reduced PPT both locally and remotely from the site of reported pain. This may indicate altered central processing of nociceptive information. However, this has never been investigated in adolescents with PFPS.

METHODS

Adolescents with PFPS and a comparison group without musculoskeletal pain were recruited from a population-based cohort of students from 4 upper secondary schools, aged 15 to 19 years. All 2846 students within that age range were invited to answer an online questionnaire regarding musculoskeletal pain. The students who reported knee pain were contacted by telephone and offered a clinical examination by an experienced rheumatologist, who made a diagnosis. PPTs were measured at 4 sites around the knee and 1 site on the tibialis anterior in the 57 female adolescents diagnosed with PFPS and in 22 female adolescents without musculoskeletal pain.

RESULTS

Adolescents with PFPS, compared to controls, had significantly lower PPTs (26%-37% [100-178 kPa]) at each of the 4 sites around the knee, suggesting localized hyperalgesia. On the tibialis anterior, adolescents with PFPS had a 33% (159 kPa) lower PPT (distal hyperalgesia) compared with controls.

CONCLUSION

These findings suggest that adolescent females with PFPS have localized and distal hyperalgesia. These findings may have implications for treating PFPS, as both peripheral and central mechanisms may be driving the pain. Registered at clinicaltrials.gov (NCT01438762).

Injury initiates unfavourable weight gain and obesity markers in youth

OBJECTIVE

The purpose of this study was to examine the association of knee injuries with subsequent changes in body mass index and body composition during maturation in young females.

METHODS

A prospective longitudinal study design was employed to evaluate young females active in soccer or basketball (N=862). Participants who completed at least 1-year follow-up to provide consecutive annual measures of BMIZ and %fat were included in the study analysis to determine the effect of knee injuries on the trajectory of these obesity markers in youth.

RESULTS

Of the 71 reported knee injuries, 12 (17%) occurred in athletes at the prepubertal stage, 24 (34%) in athletes at the pubertal stage, and 35 (49%) in postpubertal athletes. Controlling for the effects of maturation, female athletes who reported knee injury demonstrated a greater yearly increase in BMIZ (LS means and 95% CI for the injured group=0.039 (-0.012 to 0.089), for the non-injured group=-0.019 (-0.066 to 0.029), and group difference=0.057 (0.005 to 0.11), p=0.03) and in %body fat (LS means and 95% CI for the injured group=1.05 (0.45 to 1.65), for the non-injured group=0.22 (-0.21 to 0.064), and group difference=0.83 (0.21 to 1.45), p=0.009), compared to those without knee injuries. This indicates that the athletes with knee injuries will increase their body mass index percentile by up to 5 units more than someone of the same age without an injury, and in body fat by up to 1.5%, compared to their non-injured peers.

CONCLUSIONS

The present findings indicate that knee injury during the growing years may be associated with unfavourable changes in body composition.

What predicts functional outcome after treatment for patellofemoral pain?

PURPOSE

Although physical therapy is known to be effective in treating patellofemoral pain (PFP), there is considerable individual variation in the treatment response. It is unclear why some patients benefit from a specific treatment while others do not experience improvement. This study, using a prospective study design, aims to identify factors that could predict the short-term functional outcome and account for the variation frequently seen in the outcome after conservative treatment of PFP.

METHODS

Thirty-six patients (20 female and 16 male with a mean age of 23.8 ± 6.7 yr) followed a physical therapy rehabilitation program of 7 wk. Before this treatment, all patients were evaluated on subjective symptoms (pain on visual analog scales in millimeters) and functional performance (step test expressed as highest level, single-legged hop test in centimeters, and triple-hop test in centimeters). The concentric and eccentric knee extensor strength at 60°.s(-1) and 240°.s(-1) (N.m) were measured as well as the quadriceps muscle size by calculating the cross-sectional area (cm(2)) with magnetic resonance imaging. The success of the treatment was evaluated by the functional Kujala anterior knee pain scale. A linear regression model was used to identify predisposing factors for the functional outcome.

RESULTS

The total quadriceps cross-sectional area (P = 0.010), the eccentric average peak torque at 60°.s(-1) (P = 0.015), and the frequency of pain at baseline (P = 0.012) have been indicated as predisposing variables in the short-term functional outcome after a physical therapy rehabilitation program for PFP (adjusted R(2) = 0.46).

CONCLUSION

Patients with a greater quadriceps muscle size, lower eccentric knee strength, and less pain have a better short-term functional outcome after conservative treatment for PFP.