Evaluation and Treatment of Knee Pain: A Review.

Importance: Approximately 5% of all primary care visits in adults are related to knee pain. Osteoarthritis (OA), patellofemoral pain, and meniscal tears are among the most common causes of knee pain. Observations: Knee OA, affecting an estimated 654 million people worldwide, is the most likely diagnosis of knee pain in patients aged 45 years or older who present with activity-related knee joint pain with no or less than 30 minutes of morning stiffness (95% sensitivity; 69% specificity). Patellofemoral pain typically affects people younger than 40 years who are physically active and has a lifetime prevalence of approximately 25%. The presence of anterior knee pain during a squat is approximately 91% sensitive and 50% specific for patellofemoral pain. Meniscal tears affect an estimated 12% of the adult population and can occur following acute trauma (eg, twisting injury) in people younger than 40 years. Alternatively, a meniscal tear may be a degenerative condition present in patients with knee OA who are aged 40 years or older. The McMurray test, consisting of concurrent knee rotation (internal or external to test lateral or medial meniscus, respectively) and extension (61% sensitivity; 84% specificity), and joint line tenderness (83% sensitivity; 83% specificity) assist diagnosis of meniscal tears. Radiographic imaging of all patients with possible knee OA is not recommended. First-line management of OA comprises exercise therapy, weight loss (if overweight), education, and self-management programs to empower patients to better manage their condition. Surgical referral for knee joint replacement can be considered for patients with end-stage OA (ie, no or minimal joint space with inability to cope with pain) after using all appropriate conservative options. For patellofemoral pain, hip and knee strengthening exercises in combination with foot orthoses or patellar taping are recommended, with no indication for surgery. Conservative management (exercise therapy for 4-6 weeks) is also appropriate for most meniscal tears. For severe traumatic (eg, bucket-handle) tears, consisting of displaced meniscal tissue, surgery is likely required. For degenerative meniscal tears, exercise therapy is first-line treatment; surgery is not indicated even in the presence of mechanical symptoms (eg, locking, catching). Conclusions and Relevance: Knee OA, patellofemoral pain, and meniscal tears are common causes of knee pain, can be diagnosed clinically, and can be associated with significant disability. First-line treatment for each condition consists of conservative management, with a focus on exercise, education, and self-management.

Patellar Tracking: An Old Problem with New Insights.

Patellofemoral pain and instability are common indications for imaging that are encountered in everyday practice. The authors comprehensively review key aspects of patellofemoral instability pertinent to radiologists that can be seen before the onset of osteoarthritis, highlighting the anatomy, clinical evaluation, diagnostic imaging, and treatment. Regarding the anatomy, the medial patellofemoral ligament (MPFL) is the primary static soft-tissue restraint to lateral patellar displacement and is commonly reconstructed surgically in patients with MPFL dysfunction and patellar instability. Osteoarticular abnormalities that predispose individuals to patellar instability include patellar malalignment, trochlear dysplasia, and tibial tubercle lateralization. Clinically, patients with patellar instability may be divided into two broad groups with imaging findings that sometimes overlap: patients with a history of overt patellar instability after a traumatic event (eg, dislocation, subluxation) and patients without such a history. In terms of imaging, radiography is generally the initial examination of choice, and MRI is the most common cross-sectional examination performed preoperatively. For all imaging techniques, there has been a proliferation of published radiologic measurement methods. The authors summarize the most common validated measurements for patellar malalignment, trochlear dysplasia, and tibial tubercle lateralization. Given that static imaging is inherently limited in the evaluation of patellar motion, dynamic imaging with US, CT, or MRI may be requested by some surgeons. The primary treatment strategy for patellofemoral pain is conservative. Surgical treatment options include MPFL reconstruction with or without osseous corrections such as trochleoplasty and tibial tubercle osteotomy. Postoperative complications evaluated at imaging include patellar fracture, graft failure, graft malposition, and medial patellar subluxation. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Clinical results of pulsed signal therapy on patellofemoral syndrome with patellar chondropathy.

This study was designed to evaluate the effect of pulsed signal therapy (PST) on patellofemoral pain syndrome associated with patellar chondropathy. A prospective randomized double-blind placebo controlled trial included 25 patients (41 knees) between 20 and 50 years with pain due to isolated patellofemoral syndrome with chondropathy. PST group received nine 60-min daily sessions of PST treatment. Control group received the same protocol of blinded placebo treatment. The main outcome was change from baseline Kujala score at 3 months. After 3 months, patients in the control group received effective treatment (placebo post-treatment). All patients were then followed, for up to 12 months. Seventeen knees (5 males and 12 females, mean age 36.7 ± 7.9) received placebo and 24 knees (8 males and 16 females, mean age 35.5 ± 8.9) received PST. By the third month, PST group exhibited a mean change from baseline of 9.63 ± 7.5 Kujala points, compared to 0.53 ± 1.8 in the placebo group (P < 0.001). A significant progressive improvement was seen in the PST group between the 3rd and 6th and between the 6th and 12th month (P < 0.016). Patients initially allocated in the control group also improved at 3 months (P < 0.001) and 6 months (P = 0.005) post-effective treatment. In conclusion, PST in patellofemoral pain syndrome with chondropathy was effective compared to placebo at 3 months, showing an important improvement of Kujala score. The improvement was progressive and maintained up to 12 months. PST is safe and should be considered as a non-invasive option for management of this condition. Bioelectromagnetics. 40:83-90, 2019. © 2019 Bioelectromagnetics Society.

Young females with long-standing patellofemoral pain display impaired conditioned pain modulation, increased temporal summation of pain, and widespread hyperalgesia.

Patellofemoral pain (PFP) is a common and recurrent knee condition in young females, characterized by pressure hyperalgesia and reduced pain inhibitory control. This study investigated antinociceptive and pronociceptive profiles in young females with long-standing (>5 years) PFP (current-PFP), those who recovered from adolescent PFP (recovered-PFP), and pain-free controls. This preregistered, assessor-blinded, cross-sectional study included 87 females younger than 25 years: 36 current-PFP, 22 recovered-PFP, and 29 pain-free controls. The primary outcome was conditioned pain modulation (CPM) assessed by increase of cuff pain thresholds during painful cuff conditioning on the contralateral leg. Secondary outcomes included pressure pain thresholds at the knee, shin, and forearm, and temporal summation of pain, assessed by pain intensity recordings on a visual analogue scale during repeated cuff pressure pain stimulations on the leg. Compared with the recovered-PFP, the current-PFP had impaired CPM (mean difference: 11.6%; P = 0.004) and reduced pressure pain thresholds at the knee, shin, and forearm which were also reduced compared to current-PFP (mean difference: 85-225 kPa; P < 0.05). There were no differences between current-PFP and controls in CPM. Current-PFP and recovered-PFP demonstrated facilitated temporal summation of pain, compared to controls (mean difference: 0.7-0.8 visual analogue scale change; P < 0.05). Compared with controls, the recovered-PFP also had reduced pressure pain thresholds at the knee, which were higher than the current-PFP (mean difference: 110-225 kPa; P < 0.05). In conclusion, both current-PFP and recovered-PFP displayed altered pain mechanisms compared to controls with no history of knee pain, despite resolution of symptoms in the recovered-PFP group. The implications of these findings in the recurrent nature of PFP requires further studies.

A sequential cognitive and physical approach (SCOPA) for patellofemoral pain: a randomized controlled trial in adolescent patients.

OBJECTIVE:: To compare a sequential treatment algorithm considering psychosocial and physical impairments, with a conventional rehabilitation approach considering only physical impairments in adolescents with patellofemoral pain. DESIGN:: A randomized, single-blind, controlled study. PARTICIPANTS:: Fifty-five adolescents (36 females; mean age 14.3 ± 1.8 years). INTERVENTIONS:: The sequential cognitive and physical approach (SCOPA) group ( n = 28) was treated based on sequential testing and treatment of activity-related fear, flexibility, kinematics, and strength. The comparator group ( n = 27) was treated with a non-sequential physical impairment-based approach. Both groups received treatment two times a week for up to six weeks. MEASUREMENTS:: Function (Anterior Knee Pain Scale), pain (Numeric Pain Rating Scale), and Global Rating of Change were assessed at baseline, three weeks, and six weeks, with a six-month follow-up. RESULTS:: Both groups had similar function (73.7 ± 9.6) and pain (6.0 ± 2.3) at baseline. A third of individuals with patellofemoral pain demonstrated elevated activity-related fear at baseline. Patients randomized to the SCOPA group had clinically significant greater improvements at six weeks in function (SCOPA, 95.0 ± 7.4 and comparator, 84.8 ± 10.4; mean difference: 10.2, 95% CI: 5.3, 15.1) and pain (SCOPA, 0.9 ± 1.9 and comparator, 2.7 ± 2.1; mean difference: 1.7, 95% CI: 0.5, 2.9). No differences were noted in Global Rating of Change. No between-group differences were noted in any outcome at six-month follow-up. CONCLUSION:: The sequential cognitive and physical approach resulted in greater improvements in short-term function and pain. By six months, both groups demonstrated similar clinically significant improvements in all outcomes.

Hip rate of force development and strength are impaired in females with patellofemoral pain without signs of altered gluteus medius and maximus morphology.

OBJECTIVES: To compare rate of force development (RFD) and isometric muscle strength of the hip abductors and extensors; and the thickness and the amount of non-contractile tissue of the gluteus medius and maximus between females with and without patellofemoral pain (PFP). DESIGN: Cross-sectional study. METHODS: Fifty-four physically active females (27 with PFP and 27 healthy individuals) were studied. Hip muscle isometric strength and RFD was evaluated using isokinetic dynamometry. RFD was measured until 30%, 60%, and 90% of the maximal isometric torque (MIT). Hip muscle morphology was evaluated using ultrasonography. RESULTS: The PFP group possessed slower RFD compared to the control group by 33% for hip abductors until 90%MIT (-0.23%/ms, 95%CI -0.44 to -0.02, ES=0.59); by 51% for hip extensors until 30%MIT (-0.42%/ms, 95%CI -0.66 to -0.18, ES=0.97); and by 55% for hip extensors until 60%MIT (-0.36%/ms, 95%CI -0.60 to -0.12, ES=0.81). The PFP group possessed reduced isometric torque compared to the control group by 10% for hip abduction (-16.0Nm/kg×100, 95% CI -30.2 to -1.9, ES=0.61) and by 15% for hip extension (-30.1Nm/kg×100, 95%CI -51.4 to -8.9, ES=0.76). No significant between group differences for the thickness and the amount of non-contractile tissue of the gluteus medius and maximus were identified. CONCLUSIONS: Females with PFP have deficits in isometric strength and RFD in hip abduction and extension. RFD deficits are greater than strength deficits which may highlight their potential importance. Hip muscle strength and RFD deficits do not appear to be explained by muscle thickness or proportion of non-contractile tissue of the gluteal musculature as measured by ultrasound.

Is body mass index associated with patellofemoral pain and patellofemoral osteoarthritis? A systematic review and meta-regression and analysis.

BACKGROUND: Patellofemoral pain (PFP) occurs frequently, and may be related to patellofemoral osteoarthritis (PFOA). Obesity is associated with increased risk of knee OA. This systematic review involves a meta-regression and analysis to determine the relationship between body mass index (BMI) and PFP and PFOA, and to determine the link between BMI and interventional outcomes. METHODS: We searched seven electronic databases and reference lists of relevant papers and systematic reviews, for cross-sectional, prospective, human-based observational and interventional studies reporting BMI in individuals with PFP or PFOA compared to healthy controls. Two independent reviewers appraised methodological quality (epidemiological appraisal instrument). Where possible, data from prospective studies were pooled to conduct meta-regression and case-control, and intervention studies to conduct meta-analysis using the following categories: adolescents with PFP, adults with PFP and PFOA. RESULTS: 52 studies were included. We found greater BMI in adults with PFP (standardised mean difference: 0.24, 95% CI 0.12 to 0.36) and PFOA (0.73, 0.46 to 0.99) compared to healthy controls, but not in adolescents with PFP (-0.19, -0.56 to 0.18). We also observed statistical trends (p<0.10) towards higher BMI being a predictor for development of PFP in adults (0.34, -0.04 to 0.71). No significant link between BMI and intervention outcomes in adults with PFP was identified. CONCLUSIONS: Higher BMI is present in PFP and PFOA, but not in adolescents with PFP. PROSPERO REGISTRATION NUMBER: CRD42015024812.

Immediate effects of foot orthoses on pain during functional tasks in people with patellofemoral osteoarthritis: A cross-over, proof-of-concept study.

BACKGROUND: The purpose of the study was to determine whether prefabricated foot orthoses immediately reduce pain during functional tasks in people with patellofemoral osteoarthritis, compared to flat insoles and shoes alone. METHODS: Eighteen people with predominant lateral patellofemoral osteoarthritis (nine women; mean [SD] age 59 [10]years; body mass index 27.9 [3.2]kg/m2) performed functional tasks wearing running sandals, and then wearing foot orthoses and flat insoles (random order). Participants rated knee pain during each task (11-point numerical rating scales), ease of performance and knee stability (five-point Likert scales), and comfort (100mm visual analogue scales). RESULTS: Compared to shoes alone, foot orthoses (p=0.002; median difference 1.5 [IQR 3]) and flat insoles (p<0.001; 2 [3]) significantly reduced pain during step-downs; foot orthoses reduced pain during walking (p=0.008; 1 [1.25]); and flat insoles reduced pain during stair ambulation (p=0.001; 1 [1.75]). No significant differences between foot orthoses and flat insoles were observed for pain severity, ease of performance or knee stability. Foot orthoses were less comfortable than flat insoles and shoes alone (p<0.05). CONCLUSIONS: In people with patellofemoral osteoarthritis, immediate pain-relieving effects of prefabricated, contoured foot orthoses are equivalent to flat insoles. Further studies should investigate whether similar outcomes occur with longer-term wear or different orthosis designs.

La osteotomía patelar coronal de la faceta externa asociada a liberación del retináculo lateral mejora los resultados clínicos de la liberación lateral aislada en el síndrome de compresión lateral de rótula / Coronal patellar osteotomy of the external facet combined with the release of the lateral retinaculum improves the clinical outcomes of isolated lateral release in lateral knee compartment syndrome

Objetivo. Descripción de una nueva osteotomía coronal de la faceta externa de la rótula y valorar si los resultados del tratamiento del síndrome de compresión lateral de la rótula (SCLR) con nuestra osteotomía junto a la liberación del retináculo lateral externo son mejores que la liberación aislada del retináculo lateral. Material y métodos. Estudio prospectivo con 2 años de seguimiento, donde tratamos 70 pacientes diagnosticados de SCLR y distribuidos en 2 grupos: un primer grupo de 50 pacientes en los que se realizó la liberación del retináculo lateral asociada a osteotomía, y un segundo grupo de 20 pacientes en los que se realizó una liberación aislada del retináculo lateral. Se midió la escala funcional de Werner de forma preoperatoria y a los 3, 12 y 24 meses. Resultados. Existen diferencias significativas en el estado funcional global postoperatorio entre grupos (mejor el grupo de osteotomía en todos los intervalos, p<0,05). La mejoría, que es progresiva hasta los 12 meses, experimenta un ligero retroceso a los 24, aunque los valores siguen siendo mejores que los preoperatorios en ambos grupos. Todas las variables muestran valores mejores en el grupo de la osteotomía. La variable con mayor mejoría es aparición del dolor. Los pacientes con SCLR con signos degenerativos presentaron un beneficio en todos los casos. Conclusión. Los resultados muestran que la técnica de osteotomía rotuliana descrita asociado a la liberación del retináculo lateral mejora de forma significativa el dolor y la escala funcional de pacientes con SCLR a los 2 años de seguimiento, en mayor grado que lo hace la liberación aislada del retináculo lateral, incluso en aquellos en los que existe evidencia de signos degenerativos (AU)

Objective. To describe a novel coronal osteotomy of the external facet of the patella, and to evaluate if the outcomes of the treatment of lateral knee compartment syndrome (LKCS) with this osteotomy, combined with the release of the external lateral retinaculum, are better than the isolated lateral retinacular release. Material and methods. A prospective study with a 2 year follow up that included 70 patients diagnosed with LKCS, distributed into 2 groups. The first group included 50 patients on whom the lateral retinacular release combined with osteotomy was performed, and a second group on whom an isolated retinacular release was performed. Measurements were made using the Werner functional scale before the surgery and at 3, 12, and 24 months follow-up. Results. There were significant differences in the overall functional state between the two groups after the surgery (better in the osteotomy group at all the intervals, P<.05). The improvement, which was progressive up to 12 months, was slightly less at 24 months, although the values were still better than the pre-surgical ones in both groups. Pain was the variable that showed most improvement. The patients with LKCS with degenerative signs showed a benefit in all cases. Conclusion. The results demonstrate that the described patellar osteotomy technique, combined with lateral retinacular release, significantly improves the pain and the functional scale score of patients with LKCS after 2 years of follow-up, to a greater extent than isolated lateral retinacular release, including those in which there was evidence of degenerative signs (AU)

The Effects of a Multimodal Rehabilitation Program on Symptoms and Ground-Reaction Forces in Runners With Patellofemoral Pain Syndrome.

CONTEXT: Patellofemoral pain (PFP) is one of the most frequent running-related injuries. However, few interventions taking into consideration the specificity of running have been shown to be effective in runners with PFP. OBJECTIVE: To evaluate the effects of a multimodal rehabilitation program including lower-limb-strengthening/ motor-control exercises, advice on running biomechanics, and symptoms management on symptoms, strength, and ground-reaction forces in runners with PFP. DESIGN: Pre- to post- quasi-experimental. SETTING: Gait-analysis laboratory and private physical therapy clinic. PARTICIPANTS: 21 runners with PFP (34.1 ± 6.0 y old, symptoms duration 38.1 ± 45.5 mo). INTERVENTION: An 8-wk multimodal rehabilitation program including lower-limb- and core-strengthening and motor-control exercises, as well as advice on running gait and symptoms management. MAIN OUTCOME MEASURES: The Activities of Daily Living Scale of the Knee Outcome Survey (KOS-ADLS) questionnaire and visual analog scales for usual pain (VAS-U), worst pain (VAS-W), and pain during running (VAS-R) were used to assess changes in symptoms and function. Vertical ground-reaction forces (VGRF) during running and lower-limb isometric strength were also measured. RESULTS: Statistically and clinically significant improvements (P < .001) were reported on KOS-ADLS (+17.8 pts), VAS-U (-19.2 pts), VAS-W (-28.7 pts), and VAS-R (-32.2 pts) after the intervention. No significant changes in isometric strength were observed. The instantaneous vertical loading rate was decreased after the intervention (P = .002), and this reduction was correlated with changes in KOS-ADLS scores (P = .028). CONCLUSION: This multimodal intervention was successful in reducing pain and improving function of runners with PFP. However, no significant changes in lower-limb strength were observed. It appears that changes in VGRF combined with appropriate training advice could explain the clinical outcomes.

Knee Pain and Low Back Pain Additively Disturb Sleep in the General Population: A Cross-Sectional Analysis of the Nagahama Study.

INTRODUCTION: Association of knee and low back pain with sleep disturbance is poorly understood. We aimed to clarify the independent and combined effects of these orthopedic symptoms on sleep in a large-scale general population. METHODS: Cross-sectional data about sleep and knee/low back pain were collected for 9,611 community residents (53±14 years old) by a structured questionnaire. Sleep duration less than 6 h/d was defined as short sleep. Sleep quality and the presence of knee and low back pain were evaluated by dichotomous questions. Subjects who complained about knee or low back pains were graded by tertiles of a numerical response scale (NRS) score and a Roland-Morris disability questionnaire (RDQ) score respectively. Multivariate regression analyses were performed to determine the correlates of short sleep duration and poor sleep quality. RESULTS: Frequency of participants who complained of the orthopedic symptoms was as follows; knee pain, 29.0%; low back pain, 42.0% and both knee and low back pain 17.6%. Both knee and low back pain were significantly and independently associated with short sleep duration (knee pain: odds ratio (OR) = 1.19, p<0.01; low back pain: OR = 1.13, p = 0.01) and poor sleep quality (knee pain: OR = 1.22, p<0.01; low back pain; OR = 1.57, p<0.01). The group in the highest tertile of the NRS or RDQ score had the highest risk for short sleep duration and poor sleep quality except for the relationship between the highest tertile of the RDQ score and short sleep duration.(the highest tertile of the NRS: OR for short sleep duration = 1.31, p<0.01; OR for poor sleep quality = 1.47, p<0.01; the highest tertile of the RDQ: OR for short sleep duration = 1.11, p = 0.12; OR for poor sleep quality = 1.81, p<0.01) Further, coincident knee and low back pain raised the odds ratios for short sleep duration (either of knee or low back pain: OR = 1.10, p = 0.06; both knee and low back pain: OR = 1.40, p<0.01) and poor sleep quality (either of knee or low back pain: OR = 1.61, p<0.01; both knee and low back pain: OR = 2.17, p<0.01). CONCLUSION: Knee and low back pains were independently associated with short sleep duration and poor sleep quality. Further, they additively increased the correlation with these sleep problems in the general population.

Trunk and lower extremity segment kinematics and their relationship to pain following movement instruction during a single-leg squat in females with dynamic knee valgus and patellofemoral pain.

OBJECTIVES: To understand how instructing females with patellofemoral pain to correct dynamic knee valgus affects pelvis, femur, tibia and trunk segment kinematics. To determine if pain reduction in the corrected condition was associated with improved segment kinematics. DESIGN: Cross-sectional. METHODS: A 3D-motion capture system was used to collect multi-joint kinematics on 20 females with dynamic knee valgus and patellofemoral pain during a single-leg squat in two conditions: usual movement pattern, and corrected dynamic knee valgus. During each condition pain was assessed using a visual analog scale. Pelvis, femur, tibia and trunk kinematics in the frontal and transverse planes were compared between conditions using a paired T-test. Pearson correlation coefficients were generated between visual analog scale score and the kinematic variables in the corrected condition. RESULTS: In the corrected condition subjects had increased lateral flexion of the pelvis toward the weight-bearing limb (p<0.001), decreased femoral adduction (p=0.001) and internal rotation (p=0.01). A trend toward decreased tibial internal rotation (p=0.057) and increased trunk lateral flexion toward the weight-bearing limb (p=0.055) was also found. Lower pain levels were associated with less femoral internal rotation (p=0.04) and greater trunk lateral flexion toward the weight-bearing limb (p=0.055). CONCLUSIONS: Decreased hip adduction after instruction was comprised of motion at both the pelvis and femur. Decreased pain levels were associated with lower extremity segment kinematics moving in the direction opposite to dynamic knee valgus. These results increase our understanding of correction strategies used by females with patellofemoral pain and provide insight for rehabilitation.

Patellofemoral pain syndromealters joint position sense: a case-control study / A síndrome da dor patelofemoral altera a sensação de posição articular: estudo caso-controle

Introduction: The evaluation of changes in joint position sense (JPS) of the knee may be crucial for the identification of disorders that could start during the development of patellofemoral pain syndrome (PFPS). Objective: To evaluate JPS of the knee in PFPS. Methods: Twenty nine women (15 healthy and 14 with PFPS) reproduced knee flexion angles of 45° and 60° during open kinetic chain exercises and of 45° during closed kinetic chain exercises. Results: The absolute error in the active reproduction of 45° in open kinetic chain exercises was significantly higher in the experimental group. There were significant differences in absolute and relative errors between the groups for active reproduction at 45° in open and closed kinetic chain exercises. Conclusions: This study suggests that PFPS alters JPS during active reproduction of the 45° angle in both open and closed kinetic chain exercises.

Resumo Introdução: A avaliação de alterações do senso de posição articular (SPA) do joelho é crucial para a identificação de desordens que ocorrem durante o desenvolvimento da síndrome da dor patelofemoral (SDPF). Objetivo: Avaliar o SPA do joelho na SDPF. Métodos: Vinte e nove mulheres (15 saudáveis e 14 com SDPF) reproduziram os ângulos de 45° e 60° de flexão do joelho em cadeia cinética aber - ta e de 45° em cadeia cinética fechada. Resultados: O erro absoluto na reprodução ativa do ângulo de 45° em cadeia cinética aberta foi significativamente maior no grupo experimental. Foi observada diferença significante entre os grupos nos erros relativo e absoluto para a reprodução ativa do ângulo de 45° em cadeia cinética aberta e fechada. Conclusões: Este estudo sugere que a SDPF altera a SPA durante reprodução ativa do ângulo de 45°, tanto em cadeia cinética aberta quanto em fechada.

Diagnostic accuracy of the electromyography parameters associated with anterior knee pain in the diagnosis of patellofemoral pain syndrome.

OBJECTIVE: To assess the diagnostic accuracy of the surface electromyography (sEMG) parameters associated with referred anterior knee pain in diagnosing patellofemoral pain syndrome (PFPS). DESIGN: Sensitivity and specificity analysis. SETTING: Physical rehabilitation center and laboratory of biomechanics and motor control. PARTICIPANTS: Pain-free subjects (n=29) and participants with PFPS (n=22) selected by convenience. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: The diagnostic accuracy was calculated for sEMG parameters' reliability, precision, and ability to differentiate participants with and without PFPS. The selected sEMG parameter associated with anterior knee pain was considered as an index test and was compared with the reference standard for the diagnosis of PFPS. Intraclass correlation coefficient, SEM, independent t tests, sensitivity, specificity, negative and positive likelihood ratios, and negative and positive predictive values were used for the statistical analysis. RESULTS: The medium-frequency band (B2) parameter was reliable (intraclass correlation coefficient=.80-.90), precise (SEM=2.71-3.87 normalized unit), and able to differentiate participants with and without PFPS (P<.05). The association of B2 with anterior knee pain showed positive diagnostic accuracy values (specificity, .87; sensitivity, .70; negative likelihood ratio, .33; positive likelihood ratio, 5.63; negative predictive value, .72; and positive predictive value, .86). CONCLUSIONS: The results provide evidence to support the use of EMG signals (B2-frequency band of 45-96 Hz) of the vastus lateralis and vastus medialis muscles with referred anterior knee pain in the diagnosis of PFPS.

Changes in catastrophizing and kinesiophobia are predictive of changes in disability and pain after treatment in patients with anterior knee pain.

PURPOSE: The purpose of the study was to investigate if changes in psychological variables are related to the outcome in pain and disability in patients with chronic anterior knee pain. METHODS: A longitudinal observational study on 47 patients with chronic anterior knee pain was performed in a secondary healthcare setting. Pain was measured with the visual analogue scale and disability with the Lysholm scale. The psychological variables, such as anxiety, depression, pain coping strategies, catastrophizing and fear to movement beliefs, were studied by using self-administered questionnaires. RESULTS: Among the pain coping strategies, only the catastrophizing subscale showed a significant reduction. Similarly, anxiety, depression and kinesiophobia were significantly reduced after treatment. Those patients who decreased the catastrophizing, kinesiophobia, anxiety and depression showed a greater improvement in pain and disability after a purely biomedical treatment. A multiple regression analysis revealed that changes in catastrophizing predicted the amount of improvement in pain severity and that changes in both catastrophizing and anxiety predicted changes in disability after treatment. CONCLUSION: What has been found suggests that clinical improvement in pain and disability is associated with a reduction in catastrophizing and kinesiophobia. Therefore, co-interventions to reduce catastrophizing thinking and kinesiophobia may enhance the results. LEVEL OF EVIDENCE: Prospective Cohort Study, Level I for prognosis.

Does quadriceps atrophy exist in individuals with patellofemoral pain? A systematic literature review with meta-analysis.

STUDY DESIGN: Systematic literature review. OBJECTIVES: To investigate whether quadriceps atrophy is present in the affected limb of individuals with patellofemoral pain (PFP). BACKGROUND: PFP is a common condition. Atrophy of the quadriceps femoris, in particular the vastus medialis obliquus, is often assumed to be present by clinicians, and its resolution may underpin the reported effectiveness of quadriceps strengthening intervention in PFP rehabilitation. METHODS: A systematic search of the literature was conducted to identify studies that measured the size of the quadriceps in individuals with PFP. Meta-analyses were performed to determine whether quadriceps size in limbs with PFP differed from that in comparison limbs. Separate meta-analyses were performed for quadriceps size measured as girth and quadriceps size measured with imaging (thickness, cross-sectional area, and volume). RESULTS: Ten studies were included in this review. The meta-analysis of girth measurements (3 studies) found no atrophy in limbs with PFP (P = .638). The meta-analyses for imaging techniques (thickness, cross-sectional area, or volume measurements) showed atrophy in the limb with PFP compared to both the asymptomatic limb (3 studies) (P = .036) and limbs from a comparison group (3 studies) (P = .001). The single study that compared the vastus medialis obliquus and vastus lateralis in individuals with PFP found atrophy of both the vastus medialis obliquus and vastus lateralis but no significant difference in the amount of atrophy between them (P = .179). CONCLUSION: Quadriceps muscle atrophy was shown to be present in PFP when analyzed by imaging, but not by girth measures. Insufficient data were available to determine if there was greater atrophy of the vastus medialis obliquus than the vastus lateralis. These findings support the rationale for use of quadriceps strengthening as part of a rehabilitation program for PFP.

The role of muscle strength & activation patterns in patellofemoral pain.

BACKGROUND: To investigate the extent to which quadriceps muscle activation and strength are responsible for patellofemoral pain. METHODS: A pain on-off switch system synchronized with a force transducer and surface electromyography was utilized on 32 volunteer patellofemoral pain patients during maximal isometric and squat exercises. FINDINGS: There were 26 patients out of the 32 tested who complained of pain during the squat or isometric test, of these 20 subjects presented a significant advantage for the vastus lateralis compared to the vastus medialis obliquis activation and 12 patients had decreased quadriceps strength of the symptomatic compared to the non symptomatic leg. All patients who demonstrated weak vastus medialis obliquis activation during the isometric exercise possessed the same symptoms during the squat. On the other hand, 9 patients who showed diminished vastus medialis obliquis activation during the squat displayed equal activation between the vastus medialis obliquis and the vastus lateralis during the isometric task. With regard to the timing for the onset of muscle activation, there were only 4 patients who had a difference (P=0.03) between the symptomatic (0.042 s) and non-symptomatic legs (0.011 s). INTERPRETATION: Causes for patellofemoral pain vary and are not necessarily a result of quadriceps strength deficit or vastus medialis obliquis activation weakness. Patellofemoral pain patients who possess lower vastus medialis obliquis activation compared to the vastus lateralis do not necessarily have quadriceps weakness while patients presenting with quadriceps strength deficits do not always have an imbalance between vastus medialis obliquis and vastus lateralis activation.

Clinically insignificant association between anterior knee pain and patellofemoral lesions which are found incidentally.

BACKGROUND: Patellofemoral chondral lesions are frequently identified incidentally during the arthroscopic treatment of other knee pathologies. A role has been described for arthroscopic debridement when symptoms are known to originate from pathology of the patellofemoral joint. However, it remains unclear how to manage lesions which are found incidentally whilst tackling other pathologies. The purpose of this study was to establish the strength of association between anterior knee pain and patellofemoral lesions identified incidentally in a typical arthroscopic population. METHODS: A consecutive series of patients undergoing arthroscopy for a range of standard indications formed the basis of this cross section study. We excluded those with patellofemoral conditions in order to identify patellofemoral lesions which were solely incidental. Pre-operative assessments were performed on 64 patients, where anterior knee pain was sought by three methods: an annotated photographic knee pain map (PKPM), patient indication with one finger and by palpated tenderness. A single blinded surgeon, performed standard arthroscopies and recorded patellofemoral lesions. Statistical correlations were performed to identify the association magnitude. RESULTS: Associations were identified between incidental patellofemoral lesions and tenderness palpated on the medial patella (P = 0.007, χ(2) = 0.32) and the quadriceps tendon (P = 0.029, χ(2) = 0.26), but these associations were at best fair, which could be interpreted as clinically insignificant. CONCLUSION: Incidental patellofemoral lesions are not necessarily associated with anterior knee pain, we suggest that they could be left alone. This recommendation is only applicable to patellofemoral lesions which are found incidentally whilst addressing other pathology.

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).