Is patellofemoral osteoarthritis a common sequela of patellofemoral pain?

"I believe it will not get worse": A mixed-methods longitudinal study about patient's perspective of recently developed patellofemoral pain

OBJECTIVES

This study aimed to: (i) understand how women perceived their recently developed patellofemoral pain (PFP) regarding its cause, prognosis, and willingness to seek treatment; (ii) investigate self-reported function, knee-related quality of life (QoL), fear of movement, and physical activity level at the onset of PFP.

DESIGN

Mixed-methods longitudinal study.

SETTING

University.

PARTICIPANTS

Sixty-eight pain-free women were followed up over one year.

MAIN OUTCOME MEASURES

Those who developed PFP were interviewed within one month of the development of symptoms. Self-reported function, kinesiophobia, knee-related QoL, and physical activity were obtained at baseline and follow-up assessments.

RESULTS

Twenty-one women developed PFP. Most participants reported believing the increase in physical activity and/or sitting time was associated with the onset of PFP. Many reported believing symptoms would improve over time without any treatment. Only a small number of participants intended to seek care. Quantitatively, decreases in self-reported function and QoL, as well as increases in the physical activity level were observed after PFP development.

CONCLUSION

Although decreases in self-reported function and QoL were observed, women reported believing their PFP is self-limiting and do not need treatment. Strategies to accurately disseminate knowledge about PFP are needed to help stimulating early care.

Effect of soft tissue tension around the knee joint on medio-lateral patellar position

Patellofemoral pain (PFP) is one of the most common sports injuries of the knee joint and has a high persistence and recurrence rate. Medio-lateral patellar position in the knee extension position during contraction is associated with PFP. However, soft tissue tension that most influences the medio-lateral patellar position in the knee extension position during contraction in vivo is unclear. We aimed to clarify the relationship between medio-lateral patellar position and soft tissue tension around the knee joint. Twelve patients with PFP and 20 healthy participants were included. Medio-lateral patellar position and tension of the rectus femoris, vastus lateralis (VL), vastus medialis, iliotibial band (ITB), lateral patellofemoral ligament, and medial patellofemoral ligament were measured during contraction and rest. The tensions of the VL and ITB during contraction and the medio-lateral patellar position at rest were significantly associated with medio-lateral patellar position during contraction (β = 0.449, 0.354, and 0.393, respectively). In addition, the tension of ITB was significantly associated with the medio-lateral patellar position at rest (β = 0.646). These relationships were not affected by the presence of PFP. These findings suggest that the patellar position during contraction became more lateral as the tension in the VL and ITB increased, regardless of the presence of PFP. These results may facilitate the prevention and treatment of PFP.

Supratrochlear Rim is Correlated with Isolated Patellar Chondromalacia on Magnetic Resonance Imaging of the Knee

Purpose

To investigate the relationship between the supratrochlear rim and isolated patellar chondromalacia (PC) using magnetic resonance imaging (MRI) scans of the knee.

Methods

Patients without patellofemoral pain (control group) and patients with patellofemoral pain and diagnosed with stage III or IV PC based on MRI (defect group) were retrospectively identified. Patients with a history of patellar subluxation were excluded. We used patient MRI scans to perform 20 anatomical measurements of the patellofemoral joint. We also performed 2 measurements of the anterior femoral curvature. A total of 30 patients (29 ± 8.7 years) were in the control group, and 20 patients were in the defect group (29.4 ± 9.7 years).

Results

The maximum curvature (P < .001) and mean curvature (P < .001) of the anterior femoral condyle were found statistically significantly different between the groups. Patellotrochlear index (P = .03) and Insall-Salvati index (P < .001) were also found statistically significantly different between the 2 groups. Patella type III and trochlear dysplasia grade B were found more common in the defect group.

Conclusions

In this Level III prognostic, case-control study, we have shown through MRI knee measurements that the isolated patellar chondromalacia in patients without a history of patellar subluxation and dislocation is correlated with the increased anterior femoral curvature in combination with patella alta.

Influence of foot strike patterns and cadences on patellofemoral joint stress in male runners with patellofemoral pain

OBJECTIVES

This study aimed to determine the effect of foot strike patterns and cadences in male runners with patellofemoral pain (PFP).

DESIGN

Cross-sectional study.

SETTING

Biomechanics lab.

METHODS

20 male runners with PFP were instructed to randomly complete six running conditions (three cadence conditions in rearfoot strike pattern (RFS) or forefoot strike (FFS)) under a preferred running speed.

MAIN OUTCOME MEASURES

The primary outcomes were peak knee joint and moment, and secondary outcomes were patellofemoral joint stress.

RESULTS

Running with increased cadence has a lower flexion angle (P = 0.027, η2 = 0.45), lower extension moment (P = 0.011, η2 = 0.29), lower internal rotation moment (P = 0.040, η2 = 0.17), lower patellofemoral stress (P = 0.029, η2 = 0.52) than preferred cadence. FFS running performed significantly lower flexion angle (P = 0.003, η2 = 0.39), lower extension moment (P < 0.001, η2 = 0.91), lower adduction moment (P = 0.020, η2 = 0.25) lower patellofemoral stress (P < 0.001, η2 = 0.81) than RFS running for all cadence.

CONCLUSIONS

Preliminary findings provide new perspectives for male runners with PFP to unload patellofemoral joint stress in managing PFP through the combination of the FFS pattern and increased cadence.

Sex Differences in Knee Extensor Neuromuscular Function in Individuals With and Without Patellofemoral Pain

BACKGROUND

Impaired knee extensor neuromuscular function has been frequently observed in individuals with patellofemoral pain (PFP); however, few researchers have aimed to understand the influence of sex on knee extensor neuromuscular function in this pathological population. The authors aimed to determine whether there are differences in knee extensor neuromuscular function between sexes in individuals with and without PFP.

HYPOTHESIS

Women with PFP would exhibit greater deficits in knee extensor neuromuscular function than men with PFP, compared with sex-matched individuals without PFP.

STUDY DESIGN

Cross-sectional, case-control study.

LEVEL OF EVIDENCE

Level 4.

METHODS

A total of 110 individuals were classified into 4 groups: women with PFP (n = 25); men with PFP (n = 30); women without PFP (n = 25); and men without PFP (n = 30). Knee extensor strength (isometric peak torque [PT]), activation (central activation ratio), early, late, and total phase rate of torque development (RTD0-100, RTD100-200, and RTD20-80%), and endurance (isokinetic average PT) were assessed using an isokinetic dynamometer. Group differences were assessed using a 2-way multivariate analysis of variance (sex by PFP).

RESULTS

Both women and men with PFP exhibited lower knee extensor strength, activation, early, late, and total phase RTD, and endurance versus sex-matched individuals without PFP (P < 0.05 for all comparisons). Women with PFP exhibited lower early phase (7.91 ± 2.02 versus 9.78 ± 2.43 N·m/s/kg; P < 0.01; Cohen d = 0.83), late phase (5.34 ± 1.02 versus 7.28±2.28 N·m/s/kg; P < 0.01; Cohen d = 1.37), and total phase (7.40 ± 2.57 versus 8.72 ± 2.57 N·m/s/kg; P = 0.03; Cohen d = 0.51) RTD than men with PFP.

CONCLUSION

Compared with sex-matched pain-free individuals, women with PFP displayed lower RTD than men with PFP. Clinicians should note that among individuals with PFP, women are more likely to experience a greater impairment in their knee extensor torque-generating capacity than men.

CLINICAL RELEVANCE

Additional treatment strategies that effectively improve the ability to rapidly generate torque should be developed and implemented, especially when treating women with PFP.

Exploring overweight and obesity beyond body mass index: A body composition analysis in people with and without patellofemoral pain

BACKGROUND

We compared body mass index (BMI), body fat, and skeletal muscle mass between (1) a mixed-sex nonathletic cohort of people with patellofemoral pain (PFP) and pain-free people, and (2) a nonathletic cohort of people with PFP and pain-free people subgrouped by sex (i.e., men and women with PFP vs. pain-free men and women).

METHODS

This cross-sectional study included 114 people with PFP (71 women, 43 men) and 54 pain-free controls (32 women, 22 men). All participants attended a single testing session to assess body composition measures, which included BMI, percentage of body fat (%BFBioimpedance), and skeletal muscle mass (both assessed by bioelectrical impedance analysis), and percentage of body fat (%BFSkinfold) (assessed by skinfold caliper analysis). A one-way univariate analysis of covariance (age and physical activity levels as covariates) was used to compare body composition measures between groups (i.e., PFP vs. pain-free group; women with PFP vs. pain-free women; men with PFP vs. pain-free men).

RESULTS

Women with PFP presented significantly higher BMI, %BFBioimpedance, and %BFSkinfold, and lower skeletal muscle mass compared to pain-free women (p ≤ 0.04; effect size : ‒0.47 to 0.85). Men with PFP and men and women combined had no differences in BMI, %BFBioimpedance, %BFSkinfold, and skeletal muscle mass compared to their respective pain-free groups (p > 0.05).

CONCLUSION

Our findings indicate that BMI and body composition measures should be considered as part of the evaluation and management of people with PFP, especially in women, who have demonstrated higher BMI and body fat and lower skeletal muscle mass compared to pain-free controls. Future studies should not assess body composition measures in a mixed-sex population without distinguishing men participants from women participants.

Using Dual-Orthogonal Fluoroscopy and CT to Assess the Relationship Between Knee Morphology and Patellar Kinematics in Patients With Patellofemoral Pain

INTRODUCTION

Patellofemoral pain (PFP) is one of the most common knee overuse injuries, with studies suggesting PFP as a precursor for early knee osteoarthritis. The etiology of PFP is multi-factorial; however, patellar mal-tracking has been regarded as a primary mechanism. Details of this multi-factorial mechanism have been unclear because of the limitations in evaluating in-vivo, three-dimensional (3D) patellofemoral joint movement during dynamic activities accurately. Alternatively, studies have demonstrated the high accuracy and repeatability of dual fluoroscopy and CT/MRI for measuring knee joint motion.

OBJECTIVE

This study uses dual fluoroscopy and CT to investigate the associations between joint morphology and patellar kinematics in healthy controls and subjects with PFP.

METHODS

Eight PFP females (29.7±10.6 years) and 10 healthy females (25.0±7.7 years) were recruited and screened by a sports medicine physician. CT imaging was performed on participants in a supine with the knee extended, and ankle and hip in neutral alignment. Dual-orthogonal fluoroscopy measured patellar movement while participants performed a lunge task. A calibration algorithm was used to register the 3D CT model to 2D fluoroscopy image to calculate the relative position and angles of the patella based on the clinical definition of patellar motion. Measures of patellar and trochlear morphology were generated and correlated to kinematic data.

RESULTS AND CONCLUSION

There was a significant difference in the patellar-to-trochlear width ratio; however, no other significant differences in CT morphology measurements were present between groups. For PFP patients in the weight-bearing extended position, there was a moderate positive correlation between the patellar-to-trochlear width ratio and medial-lateral patellar shift (τ = 0.643, p = 0.026). Healthy controls in this position demonstrated a moderate positive correlation between the lateral-trochlear inclination angle and medial-lateral patellar shift (τ = 0.600, p = 0.016) and moderate negative correlation between medial trochlear inclination angle and medial-lateral patellar shift (τ = -0.511, p = 0.040). The findings suggest that, for this cohort, there is correlation between morphology and patellar kinematics. Passive and active stabilizers likely have a role in mal-tracking.

3D patellar shape is associated with radiological and clinical signs of patellofemoral osteoarthritis

OBJECTIVE

To examine the association between 3D patellar shape and 1) isolated magnetic resonance imaging (MRI)-based patellofemoral osteoarthritis (PFOA), 2) the morphological features of PFOA, and 3) the clinical symptoms of PFOA.

DESIGN

MRI data from 66 women with isolated MRI-based PFOA and 66 age- and BMI-matched healthy women were selected from a cohort study. The patellae were manually segmented from MRI scans and used to create a 3D statistical shape model (SSM) of the patella. Structural abnormalities were semi-standardized scored on MRI using MRI osteoarthritis knee score (MOAKS). Regression analyses were applied to determine the associations between the shape parameters retrieved from the SSM, group status, clinical symptoms, and structural abnormalities.

RESULTS

Four shape variants showed a statistically significant (<0.05) association with the group status. The mode responsible for most of the shape variations showed participants with PFOA possess a relatively thicker dorsal bump on the articular part of the patella, compared to patellae of control participants. Three of these variants showed an association with the presence of osteophytes and cartilage loss on the patella. Multiple associations were found between patellar shape and the clinical symptoms of PFOA.

CONCLUSIONS

Patellar shape is associated with the prevalence of MRI-based PFOA in women. Some shape variants were also associated with clinical symptoms. Interestingly, one particular shape variant associated with the presence of MRI-based PFOA was earlier shown to be associated with structural abnormalities associated with OA in a population aged under 40. This may suggest that patellar shape may be an early detectable risk factor for PFOA.

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.

Overweight and obesity in young adults with patellofemoral pain: Impact on functional capacity and strength

PURPOSE

This study aimed to (a) investigate the proportion of overweight/obesity in a cohort of young adults with patellofemoral pain (PFP) and (b) explore the association of body mass index (BMI), body fat, and lean mass with functional capacity and hip and knee strength in people with PFP.

METHODS

We included a mixed-sex sample of young adults (18-35 years old) with PFP (n = 100). Measurements for BMI, percentage of body fat, and lean mass (assessed by bioelectrical impedance) were obtained. Functional capacity was assessed by the Anterior Knee Pain Scale, plank test, and single-leg hop test. Strength of the knee extensors, knee flexors, and hip abductors was evaluated isometrically using an isokinetic dynamometer. The proportion of overweight/obesity was calculated based on BMI. The association between BMI, body fat, and lean mass and functional capacity and strength was investigated using partial correlations, followed by hierarchical regression analysis, adjusted for covariates (sex, bilateral pain, and current pain level).

RESULTS

A total of 38% of our cohort had their BMI categorized as overweight/obese. Higher BMI was associated with poor functional capacity (ΔR² = 0.06-0.12, p ≤ 0.001) and with knee flexion strength only (ΔR² = 0.04, p = 0.030). Higher body fat was associated with poor functional capacity (ΔR² = 0.05-0.15, p ≤ 0.015) and reduced strength (ΔR² = 0.15-0.23, p < 0.001). Lower lean mass was associated with poor functional capacity (ΔR² = 0.04-0.13, p ≤ 0.032) and reduced strength (ΔR² = 0.29- 0.31, p < 0.001).

CONCLUSION

BMI, body fat, and lean mass should be considered in the assessment and management of young people with PFP because it may be detrimental to function and strength.

The Comparison of Psychological Barriers Between Individuals with a History of Anterior Knee Pain, Anterior Cruciate Ligament Reconstruction, and Healthy Individuals

Background

Psychological barriers due to anterior knee pain (AKP) and anterior cruciate ligament reconstruction (ACLR) may have a direct impact on an individual's return to physical activity. A comprehensive understanding of these psychological barriers in individuals with AKP and ACLR may help clinicians to develop and implement better treatment strategies to address deficits that may exist in these individuals.

Hypothesis/Purpose

The primary purpose of this study was to evaluate fear-avoidance, kinesiophobia, and pain catastrophizing in individuals with AKP and ACLR compared with healthy individuals. The secondary purpose was to directly compare psychological characteristics between the AKP and ACLR groups. It was hypothesized that 1) individuals with AKP and ACLR would self-report worse psychosocial function than healthy individuals and 2) the extent of the psychosocial impairments between the two knee pathologies would be similar.

Study Design

Cross-sectional study.

Methods

Eighty-three participants (28 AKP, 26 ACLR, and 29 healthy individuals) were analyzed in this study. Fear avoidance belief questionnaire (FABQ) with the physical activity (FABQ-PA) and sport (FABQ-S) subscales, Tampa scale of Kinesiophobia (TSK-11) and pain catastrophizing scale (PCS) assessed psychological characteristics. Kruskal-Wallis tests were used to compare the FABQ-PA, FABQ-S, TSK-11, and PCS scores across the three groups. Mann-Whitney U tests were performed to determine where group differences occurred. Effect sizes (ES) were calculated with the Mann-Whitney U z-score divided by the square root of the sample size.

Results

Individuals with AKP or ACLR had significantly worse psychological barriers compared to the healthy individuals for all questionnaires (FABQ-PA, FABQ-S, TSK-11, and PCS) (p<0.001, ES>0.86). There were no differences between the AKP and ACLR groups (p≥0.67), with a medium ES (-0.33) in the FABQ-S between AKP and ACLR groups.

Conclusion

Greater psychological scores indicate impaired psychological readiness to perform physical activity. Clinicians should be aware of fear-related beliefs following knee-related injuries and are encouraged to measure psychological factors during the rehabilitation process.

Level of Evidence

2.

Kinematic and Kinetic Gait Characteristics in People with Patellofemoral Pain: A Systematic Review and Meta-analysis

BACKGROUND

Patellofemoral pain (PFP) is a prevalent knee condition with many proposed biomechanically orientated etiological factors and treatments.

OBJECTIVE

We aimed to systematically review and synthesize the evidence for biomechanical variables (spatiotemporal, kinematic, kinetic) during walking and running in people with PFP compared with pain-free controls, and determine if biomechanical variables contribute to the development of PFP.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

We searched Medline, CINAHL, SPORTDiscus, Embase, and Web of Science from inception to October 2021.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

All study designs (prospective, case-control [± interventional component, provided pre-intervention data were reported for both groups], cross-sectional) comparing spatiotemporal, kinematic, and/or kinetic variables during walking and/or running between people with and without PFP.

RESULTS

We identified 55 studies involving 1300 people with PFP and 1393 pain-free controls. Overall pooled analysis identified that people with PFP had slower gait velocity [moderate evidence, standardized mean difference (SMD) - 0.50, 95% confidence interval (CI) - 0.72, - 0.27], lower cadence (limited evidence, SMD - 0.43, 95% CI - 0.74, - 0.12), and shorter stride length (limited evidence, SMD - 0.46, 95% CI - 0.80, - 0.12). People with PFP also had greater peak contralateral pelvic drop (moderate evidence, SMD - 0.46, 95% CI - 0.90, - 0.03), smaller peak knee flexion angles (moderate evidence, SMD - 0.30, 95% CI - 0.52, - 0.08), and smaller peak knee extension moments (limited evidence, SMD - 0.41, 95% CI - 0.75, - 0.07) compared with controls. Females with PFP had greater peak hip flexion (moderate evidence, SMD 0.83, 95% CI 0.30, 1.36) and rearfoot eversion (limited evidence, SMD 0.59, 95% CI 0.03, 1.14) angles compared to pain-free females. No significant between-group differences were identified for all other biomechanical variables. Data pooling was not possible for prospective studies.

CONCLUSION

A limited number of biomechanical differences exist when comparing people with and without PFP, mostly characterized by small-to-moderate effect sizes. People with PFP ambulate slower, with lower cadence and a shortened stride length, greater contralateral pelvic drop, and lower knee flexion angles and knee extension moments. It is unclear whether these features are present prior to PFP onset or occur as pain-compensatory movement strategies given the lack of prospective data.

TRIAL REGISTRATION

PROSPERO # CRD42019080241.

Six Treatments Have Positive Effects at 3 Months for People With Patellofemoral Pain: A Systematic Review With Meta-analysis

OBJECTIVE: To determine the effects of nonsurgical treatments on pain and function in people with patellofemoral pain (PFP). DESIGN: Systematic review with meta-analysis. LITERATURE SEARCH: We searched MEDLINE, Web of Science, and Scopus databases from their inception until May 2022 for interventional randomized controlled trials (RCTs) in people with PFP. STUDY SELECTION CRITERIA: We included RCTs that were scored ≥7 on the PEDro scale. DATA SYNTHESIS: We extracted homogenous pain and function data at short- (≤3 months), medium- (>3 to ≤12 months) and long-term (>12 months) follow-up. Interventions demonstrated primary efficacy if outcomes were superior to sham, placebo, or wait-and-see control. Interventions demonstrated secondary efficacy if outcomes were superior to an intervention with primary efficacy. RESULTS: We included 65 RCTs. Four interventions demonstrated short-term primary efficacy: knee-targeted exercise therapy for pain (standardized mean difference [SMD], 1.16; 95% CI: 0.66, 1.66) and function (SMD, 1.19; 95% CI: 0.51, 1.88), combined interventions for pain (SMD, 0.79; 95% CI: 0.26, 1.29) and function (SMD, 0.98; 95% CI: 0.47, 1.49), foot orthoses for global rating of change (OR = 4.31; 95% CI: 1.48, 12.56), and lower-quadrant manual therapy for function (SMD, 2.30; 95% CI: 1.60, 3.00). Two interventions demonstrated short-term secondary efficacy compared to knee-targeted exercise therapy: hip-and-knee-targeted exercise therapy for pain (SMD, 1.02; 95% CI: 0.58, 1.46) and function (SMD, 1.03; 95% CI: 0.61, 1.45), and knee-targeted exercise therapy and perineural dextrose injection for pain (SMD, 1.34; 95% CI: 0.72, 1.95) and function (SMD, 1.21; 95% CI: 0.60, 1.82). CONCLUSIONS: Six interventions had positive effects at 3 months for people with PFP, with no intervention adequately tested beyond this time point. J Orthop Sports Phys Ther 2022;52(11):750-768. Epub: 8 September 2022. doi:10.2519/jospt.2022.11359.

Prevalence of Patellofemoral Pain and Knee Pain in the General Population of Saudi Arabia

Background

Patellofemoral pain (PFP) is a common cause of knee pain. This condition can restrict daily activities by trying to avoid activities that aggravate their pain. This study aimed to determine the prevalence of PFP and knee pain and its associated factors among Saudi young adults.

Methods

A descriptive cross-sectional study was conducted in Saudi Arabia. A validated translated Arabic questionnaire was used. Data was collected through an online self-administered questionnaire. Saudi young adults of both genders aged between (18 to 40 years) were included. The mean ±SD was described for continuous variables, whereas categorical variables were reported using frequencies and percentages. The chi-square test was used for descriptive analysis.

Results

A total of 1558 subjects were enrolled in the current study. About 663 (42.6%) were males and 895 (57.4%) were females. Of the total participants, 718 (46%) were within the age group of 18 to 25. The overall prevalence of PFP among the current study participant was found to be 30.3%. The prevalence of PFP among males was found to be 31.4% and the prevalence of PFP among females was found to be 29.5%. The overall prevalence of knee pain among study participants was found to be 13.2% as 205 of the participants reported knee pain. The prevalence of knee pain among males was found to be 14% and the prevalence of knee pain among females was found to be 12.3%. The multivariate analysis included the following variables: age, gender, and marital status. The following factors predicted higher rate of PFP: being 18 to 25 years old (p-value < 0.001, odds ratio = 1), being 26 to 35 years old (p-value = 0.001, odds ratio = 1.689).

Conclusion

The prevalence of PFP and knee pains was found to be relatively high in Saudi Arabia. Age less than 40 years old was found to be associated with a higher prevalence of PFP and knee pain when compared to other age groups.

Automatic Bone Segmentation from MRI for Real-Time Knee Tracking in Fluoroscopic Imaging

Recent progress in real-time tracking of knee bone structures from fluoroscopic imaging using CT templates has opened the door to studying knee kinematics to improve our understanding of patellofemoral syndrome. The problem with CT imaging is that it exposes patients to extra ionising radiation, which adds to fluoroscopic imaging. This can be solved by segmenting bone templates from MRI instead of CT by using a deep neural network architecture called 2.5D U-Net. To train the network, we used the SKI10 database from the MICCAI challenge; it contains 100 knee MRIs with their corresponding annotated femur and tibia bones as the ground truth. Since patella tracking is essential in our application, the SKI10 database was augmented with a new label named UofA Patella. Using 70 MRIs from the database, a 2.5D U-Net was trained successfully after 75 epochs with an excellent final Dice score of 98%, which compared favourably with the best state-of-the-art algorithms. A test set of 30 MRIs were segmented using the trained 2.5D U-Net and then converted into 3D mesh templates by using a marching cube algorithm. The resulting 3D mesh templates were compared to the 3D mesh model extracted from the corresponding labelled data from the augmented SKI10. Even though the final Dice score (98%) compared well with the state-of-the-art algorithms, we initially found that the Euclidean distance between the segmented MRI and SKI10 meshes was over 6 mm in many regions, which is unacceptable for our application. By optimising many of the hyper-parameters of the 2.5D U-Net, we were able to find that, by changing the threshold used in the last layer of the network, one can significantly improve the average accuracy to 0.2 mm with a variance of 0.065 mm for most of the MRI mesh templates. These results illustrate that the Dice score is not always a good predictor of the geometric accuracy of segmentation and that fine-tuning hyper-parameters is critical for improving geometric accuracy.

Efficacy of Patellar Taping and Electromyographic Biofeedback Training at Various Knee Angles on Quadriceps Strength and Functional Performance in Young Adult Male Athletes with Patellofemoral Pain Syndrome: A Randomized Controlled Trial

Background

The severity of the articular lesion is the single most essential element in investigating the extent of flexion that is required for activities. However, a prior study found no differences in muscle strength gains of quadriceps muscles at different knee angles in people with patellofemoral pain syndrome (PFPS).

Objective

The effects of patellar taping and electromyographic biofeedback (EMG-BF)-guided isometric quadriceps strengthening at different knee angles (e.g., 30°, 60°, and 90° of knee flexion) on quadriceps strength and functional performance in people with PFPS were compared in this single-blind randomized controlled parallel trial.

Methods

Sixty adult male athletes with PFPS (age: 26.9 ± 1.4 years) were randomly divided into two groups. The experimental group (n = 30) received patellar taping and EMG-BF-guided isometric contraction exercise at 30°, 60°, and 90° angles, and the control group (n = 30) received sham patellar taping without EMG-BF-guided exercises for six weeks. Pain intensity, knee function, muscle strength, and the single-leg triple hop (SLTH) test were assessed.

Results

The pain intensity and SLTH scores between the groups were significantly different at the end of the trial (p ≤ 0.001). The EMG-BF and control groups had mean pain scores of 1.3 (0.8) and 4.5 (0.8), respectively. The EMG-BF and control groups had mean functional scores of 80.4 (5.1) and 69.1 (6.1), respectively. The mean SLTH score for the EMG-BF group was 540.7 (51.2) and for the control group it was 509.4 (49.8) after the trial. Quadriceps muscle strength was significantly higher in those who performed quadriceps strength training at 60° of knee flexion after six weeks than in those who performed strength training at 30° or 90° of knee flexion.

Conclusion

The findings indicated that individuals who trained their quadriceps at a 60° knee angle had significantly stronger quadriceps muscles than individuals who trained at 30° or 90° of knee flexion. Trial Registration. This trial is registered at Clinical Trials.gov under the identifier NCT05055284.

Anterior Knee Pain: State of the Art

Anterior knee pain (AKP) is one of the most common conditions to bring active young patients to a sports injury clinic. It is a heterogeneous condition related to multiple causative factors. Compared to the general population, there appears to be a higher risk of development of patellofemoral osteoarthritis in patients with AKP. AKP can be detrimental to the patient’s quality of life and, in the larger context, significantly burdens the economy with high healthcare costs. This study aims to present a comprehensive evaluation of AKP to improve clinical daily practice. The causes of AKP can be traced not only to structures within and around the knee, but also to factors outside the knee, such as limb malalignment, weakness of specific hip muscle groups, and core and ligamentous laxity. Hence, AKP warrants a pointed evaluation of history and thorough clinical examination, complemented with relevant radiological investigations to identify its origin in the knee and its cause. Conservative management of the condition achieves good results in a majority of patients with AKP. Surgical management becomes necessary only when it is deemed to provide benefit—when the patient has well-characterized structural abnormalities of the knee or limb that correlate with the AKP clinically or in situations where the patient does not obtain significant or sustained relief from symptoms. AKP has a multifactorial etiology. The treatment strategy must be individualized to the patient based on the patient profile and specific cause identified. Hence, treatment of AKP warrants a pointed evaluation of history and thorough clinical examination complemented with relevant radiological investigations to identify the condition’s origin and its cause. A holistic approach focused on the patient as a whole will ensure a good clinical outcome, as much as a focus on the joint as the therapeutic target.

Effectiveness of adjunctive treatment combined with exercise therapy for patellofemoral pain: a protocol for a systematic review with network meta-analysis of randomised controlled trials

INTRODUCTION

Patellofemoral pain (PFP) is a chronic condition that affects up to 25% of the general population and has a negative impact on functionality and quality of life due to the high levels of pain experienced by these patients. In order to improve pain and function, rehabilitation programmes that combine adjunctive treatments with exercise therapy are often used in research and clinical settings. However, despite the variety of adjunctive treatments available, their effectiveness when compared with exercise therapy has yet to be elucidated. Thus, the aim of this study is to evaluate the effectiveness of adjunctive treatments plus exercise therapy versus exercise therapy, and determine the relative efficacy of different types of adjunctive treatments plus exercise therapy for individuals with PFP.

METHODS AND ANALYSIS

A systematic review and network meta-analysis will be conducted based on the Cochrane Collaboration recommendations and reported in line with Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines. We will search Embase, PubMed (MEDLINE), CENTRAL, CINAHL, PEDro, SPORTDiscus, Web of Science and OpenGrey. It will be included randomised controlled trials that compared adjunctive treatment plus exercise therapy to placebo adjunctive treatment plus exercise therapy or exercise therapy. The outcomes of interest will be pain and function, with no restrictions on language, setting or year of publication. Study selection will be performed by two independent reviewers, based on the eligibility criteria. Risk of bias will be assessed using the Physiotherapy Evidence Database scale and the evidence summarised via the Grading of Recommendation, Assessment, Development and Evaluation approach. A Bayesian network meta-analysis will be performed to compare the efficacy of different adjunctive treatments plus exercise therapy. Consistency between direct and indirect comparisons will be assessed.

ETHICS AND DISSEMINATION

No ethical statement will be required for this systematic review and meta-analysis. The findings will be published in a relevant international peer-reviewed journal and presented at conferences.

PROSPERO REGISTRATION NUMBER

CRD42020197081.

Patellofemoral joint degeneration: A review of current management

The patellofemoral component of the knee joint is affected by a wide range of degenerative causes without involving the other parts of the knee. It is often the presenting pathology in early knee osteoarthritis and missed due to a variable presentation. Accurate examination and focused investigation can help with early diagnosis and guide treatment. Various aspects to treatment need to be addressed after thorough evaluation. Guidelines to approach the multifactorial pathology of the patello-femoral joint are provided with focus on the degenerative component of disease.

Trunk muscle endurance in individuals with and without patellofemoral pain: Sex differences and correlations with performance tests

OBJECTIVES

To compare trunk muscle endurance among females and males with and without patellofemoral pain (PFP), and to investigate the correlations between trunk muscle endurance and performance of the single leg hop test (SLHT) and forward step-down test (FSDT).

DESIGN

Cross-sectional.

SETTING

Laboratory-based study.

PARTICIPANTS

110 females and 38 males with PFP, 61 females and 31males without PFP.

MAIN OUTCOME MEASURES

Anterior and lateral trunk muscle endurance were assessed with the prone and bilateral side-bridge tests, respectively. Performance during the SLHT and FSDT was also assessed.

RESULTS

Lower anterior and lateral trunk muscle endurance were identified in females (p < .001; d = -0.74 to -0.86), but not in males (p ≥ .806; d = -0.04 to 0.05) with PFP as compared to sex-matched controls. Moderate to large, positive correlations between anterior and lateral trunk muscle endurance with performance in the SLHT and FSDT were identified in females (r = .27 to .50; p < .004) and males (r = 0.27 to 0.59; p < .031) with PFP and females without PFP (r = 0.26 to 0.40; p < .044).

CONCLUSION

Our findings highlight that assessing trunk muscle endurance is advised in females with PFP. Trunk muscle endurance of individuals with PFP may have a role in the performance of hopping and stepping down tasks.

REPORT-PFP: a consensus from the International Patellofemoral Research Network to improve REPORTing of quantitative PatelloFemoral Pain studies

Patellofemoral pain is a common and often debilitating musculoskeletal condition. Clinical translation and evidence synthesis of patellofemoral pain research are compromised by heterogenous and often inadequately reported study details. This consensus statement and associated checklist provides standards for REPORTing of quantitative PatelloFemoral Pain (REPORT-PFP) research to enhance clinical translation and evidence synthesis, and support clinician engagement with research and data collection. A three-stage Delphi process was initiated at the 2015 International Patellofemoral Research Network (iPFRN) retreat. An initial e-Delphi activity (n=24) generated topics and items, which were refined at the 2017 iPFRN retreat, and voted on prior to and following the 2019 iPFRN retreat (n=51 current and past retreat participants). Voting criteria included 'strongly recommended' (essential), 'recommended' (encouraged) and uncertain/unsure. An item was included in the checklist if ≥70% respondents voted 'recommended'. Items receiving ≥70% votes for 'strongly recommended' were labelled as such. The final REPORT-PFP checklist includes 31 items (11 strongly recommended, 20 recommended), covering (i) demographics (n=2,4); (ii) baseline symptoms and previous treatments (n=3,7); (iii) outcome measures (2,4); (iv) outcomes measure description (n=1,2); (v) clinical trial methodology (0,3) and (vi) reporting study results (n=3,0). The REPORT-PFP checklist is ready to be used by researchers and clinicians. Strong stakeholder engagement from clinical academics during development means consistent application by the international patellofemoral pain research community is likely. Checklist adherence will improve research accessibility for clinicians and enhance future evidence synthesis.

Outcomes After Deepening Trochleoplasty and Concomitant Realignment in Patients With Severe Trochlear Dysplasia With Chronic Patellofemoral Pain: Results at 2-Year Follow-up

Background

Abnormal patellofemoral joint stress appears to have major relevance in a subgroup of patients with patellofemoral pain (PFP).

Purpose

To evaluate whether patients with chronic PFP and trochlear dysplasia-induced patellofemoral joint malalignment benefit from a deepening trochleoplasty procedure with the aim of improving patellotrochlear congruence.

Study Design

Case series; Level of evidence, 4.

Methods

Included were 15 patients (male/female, 1/14; mean age, 30.3 years [range, 19-51 years]) with 8.8 years (range, 1-20 years) of chronic PFP and severe trochlear dysplasia. All patients underwent correction of patellotrochlear malalignment with deepening trochleoplasty and concomitant realignment procedures. The Kujala score and a numerical analog scale (0-10) for intensity of pain were used to assess symptoms preoperatively and at 12 and 24 months postoperatively. Pre- and postoperative magnetic resonance imaging (MRI) scans from the patients were compared with the MRI scans of age- and sex-matched controls regarding the patellotrochlear contact area and contact ratio, patellar tilt, patellotrochlear index, and lateral trochlear inclination (LTI) angle.

Results

The Kujala score increased from a mean of 55 (range, 15-81) preoperatively to 82.5 (range, 53-98) after 12 months (95% CI, -42.56 to -12.37; P < .001) and to 84.2 (range, 59-99) after 24 months (95% CI, -44.29 to -14.11; P < .001). The intensity of PFP decreased from 5.7 (range, 3-10) preoperatively to 1.4 (range, 0-4) after 12 months (95% CI, 2.57 to 5.96; P < .001) and had a mean of 1.6 (range, 0-6) after 24 months (95% CI, 2.44 to 5.75; P < .001). Preoperatively, parameters in the study group indicated significant patellotrochlear malalignment, which improved and normalized (except for the LTI angle) postoperatively compared with the values of the control group (P > .05).

Conclusion

In a subgroup of patients with chronic PFP due to severe trochlear dysplasia, deepening trochleoplasty and concomitant realignment procedures significantly reduced pain and improved knee joint function while normalizing patellotrochlear congruence.

A comparison between whole-body vibration and conventional training on pain and performance in athletes with patellofemoral pain

INTRODUCTION

Patellofemoral pain (PFP) is the most common cause of anterior knee pain in athletes, which affects their performance especially during single leg activities. The aim of this study was to compare the effects of whole-body vibration training (WBVT) and conventional training (CT) on pain and performance in athletes with PFP.

METHODS

30 athletes with unilateral PFP were randomly assigned to the WBVT (6 women, 9 men) or CT (7 women, 8 men) group. All participants received training for 4 weeks in 12 sessions. The outcomes of pain and performance were measured at three points in time: baseline, immediately after training and 2 weeks after training. Pain was assessed with the Numeric Pain Rating Scale (NPRS). Performance was measured with the leg-press test and the Kujala Patellofemoral Score (KPS).

RESULTS

In both groups, pain intensity decreased significantly (p < 0.001) and the KPS and number of leg presses increased significantly (p < 0.001) with time. There was no significant difference between groups for changes in the pain score (p = 0.896), KPS (p = 0.463) or leg press (p = 0.796) results.

CONCLUSION

Whole-body vibration training had the same effect as exercise therapy on pain reduction and on improvements in performance in athletes with PFP.

The Effect of Diacutaneous Fibrolysis on Local and Widespread Hyperalgesia and Muscle Length in Patients With Patellofemoral Pain Syndrome: Secondary Analysis of a Pretest-Posttest Clinical Trial

CONTEXT

Localized and widespread hyperalgesia has been observed in patients with patellofemoral pain. Diacutaneous fibrolysis (DF) has shown to be effective in reducing pain in several musculoskeletal conditions including patellofemoral pain syndrome, but no studies have evaluated the effects of this technique in reducing localized and widespread hyperalgesia.

OBJECTIVE

To assess the effect of DF on the pressure pain threshold and muscle length tests in patients with patellofemoral pain syndrome.

DESIGN

A single-group, pretest-posttest clinical trial.

SETTING

University of Zaragoza.

PARTICIPANTS

Forty-six subjects with patellofemoral pain (20 males and 26 females: age 27.8 [6.9] y).

INTERVENTION

Three sessions of DF.

MAIN OUTCOME MEASURES

Pressure pain threshold using a handheld pressure algometer (4 sites around the knee, on tibialis anterior muscle, and one remote site on the upper contralateral limb); muscle length test of the iliotibial band, rectus femoris, and hamstring muscles; and patient-perceived treatment effect score.

RESULTS

The application of 3 sessions of DF significantly increased the pressure pain threshold in all sites at posttreatment evaluation (P < .001) and at a 1-week follow-up (P < .001). A significant increase in muscle length was also observed at the posttreatment evaluation (P < .001) and 1-week follow-up (P < .001). Ninety-seven percent of the patients reported subjective improvement at posttreatment and at 1-week follow-up.

CONCLUSION

This study found that local and widespread hyperalgesia was significantly reduced after 3 sessions of diacutaneous fibrolysis and at the 1-week follow-up. A significant improvement on muscle length tests was also observed, with high clinical satisfaction among patients.

Effect of Vastus Medialis Loss on Rabbit Patellofemoral Joint Contact Pressure Distribution

Vastus medialis (VM) weakness is thought to alter patellar tracking, thereby changing the loading of the patellofemoral joint (PFJ), resulting in patellofemoral pain. However, it is challenging to measure VM force and weakness in human studies, nor is it possible to measure the associated mechanical changes in the PFJ. To obtain fundamental insight into VM weakness and its effects on PFJ mechanics, the authors determined PFJ loading in the presence of experimentally simulated VM weakness. Skeletally mature New Zealand White rabbits were used (n = 6), and the vastus lateralis, VM, and rectus femoris were stimulated individually through 3 custom-built nerve cuff electrodes. Muscle torque and PFJ pressure distribution were measured while activating all muscles simultaneously, or when the vastus lateralis and rectus femoris were activated, while VM was not, to simulate a quadriceps muscle strength imbalance. For a given muscular joint torque, peak pressures were greater and joint contact areas were smaller when simulating VM weakness compared with the condition where all muscles were activated simultaneously. The results in the rabbit model support that VM weakness results in altered PFJ loading, which may cause patellofemoral pain, often associated with a strength imbalance of the knee extensor muscle group.

Psychological and Pain Sensitization Characteristics Are Associated With Patellofemoral Osteoarthritis Symptoms: The Multicenter Osteoarthritis Study

OBJECTIVE

Determine the relation of symptomatic and structural features of patellofemoral osteoarthritis (PFOA) to psychological characteristics and measures of pain sensitization, in older adults with or at risk of knee osteoarthritis (OA).

METHODS

This study included 1112 participants from the Multicenter Osteoarthritis Study (713 females, mean age 66.8 ± SD 7.6 yrs, body mass index 29.5 ± 4.8 kg/m²). Participants were grouped based on the presence of PFOA symptoms (anterior knee pain and pain on stairs) and magnetic resonance imaging (MRI) PFOA (full-thickness cartilage lesion with bone marrow lesion): (1) patellofemoral (PF) symptoms with MRI PFOA; (2) PF symptoms without MRI PFOA; (3) MRI PFOA without PF symptoms; and (4) no PF symptoms or MRI PFOA (no PFOA). Relation of PFOA classification to depressive symptoms, catastrophizing, temporal summation (TS) and pressure pain thresholds (PPT) was evaluated using logistic (categorical variables) and linear regression (continuous variables).

RESULTS

Compared with no PFOA, those with PF symptoms with or without MRI PFOA had significantly greater odds of depressive symptoms, catastrophizing, and patellar TS (OR range 1.5-2.01), and those with PF symptoms without MRI PFOA had significantly greater odds of wrist TS (OR 1.66). Males with PF symptoms without MRI PFOA had significantly lower pressure PPT at the patella compared with no PFOA and those with MRI PFOA only (no symptoms). There were no significant differences at the wrist for males, or the patella or wrist for females.

CONCLUSION

Persons with PFOA symptoms, regardless of MRI PFOA status, are more likely to demonstrate depressive symptoms, catastrophizing, and TS. Males with PFOA symptoms without MRI PFOA demonstrate local hyperalgesia.

Is patellofemoral pain preventable? A systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

To evaluate the effectiveness of interventions to reduce the risk of incident patellofemoral pain.

DESIGN

Systematic review and meta-analysis, with strength of evidence evaluated separately for each intervention type.

DATA SOURCES

MEDLINE, EMBASE, CINAHL, Web of Science and SPORTDiscus.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Randomised controlled trials evaluating the effectiveness of interventions to reduce patellofemoral pain risk compared with a control/non-exposed group.

RESULTS

Thirteen trials of mostly military recruits and young athletes analysed six different interventions. There was low certainty evidence from two trials (227 participants) that patellofemoral braces worn during physical activity (compared with no brace) effectively reduced the risk of patellofemoral pain (risk ratio (RR) 0.40, 95% CI 0.22 to 0.73; I2=24.0%). There was low certainty evidence from one trial (320 participants) that running technique retraining to (run softer) reduced patellofemoral pain risk (RR 0.21, 95% CI 0.07 to 0.60). There was low certainty evidence from four trials (3364 participants) that multicomponent (strengthening/neuromuscular) exercise programmes did not significantly reduce the risk of patellofemoral pain (RR 0.49, 95% CI 0.18 to 1.36; I2=64.9%), although broad CIs may reflect exercise dose variations among studies. There was very low certainty evidence from four trials (2314 participants) that foot orthoses (compared with flat inserts/no orthosis) did not significantly reduce the risk of patellofemoral pain (RR 0.63, 95% CI 0.35 to 1.13; I2=0.0%). Static stretching and a running programme that progressed intensity (compared with volume) did not significantly influence patellofemoral pain risk (single studies).

CONCLUSION

There is low-level evidence that patellofemoral braces and running technique retraining can reduce the risk of patellofemoral pain by 60%-79%.

Kneeling as a risk factor of patellofemoral joint cartilage damage worsening: an exploratory analysis on the Osteoarthritis Initiative

OBJECTIVES

To determine whether kneeling activity is associated with the MRI measures of patellofemoral (PF) joint cartilage damage worsening in subjects with/without patella alta (PA).

METHODS

Baseline and 24-month 3-T MR images and semi-quantitative MRI Osteoarthritis Knee Score (MOAKS) of PF joint of 600 subjects from the FNIH study, a nested study within the Osteoarthritis Initiative (OAI), were extracted. At baseline visit, subjects were asked how many days per week they participated in kneeling activities lasted ≥ 30 min. Insall-Salvati ratio (ISR) (patellar tendon/patellar height) was measured on baseline MRIs by a musculoskeletal radiologist; ISR ≥ 1.3 was considered PA. Regression analysis adjusted for confounding variables was used to assess the impact of kneeling on worsening of MOAKS cartilage over 24 months. The potential moderating effect of PA was evaluated using adjusted regression analysis.

RESULTS

Six hundred subjects (58.8% female, years, BMI = 30.7 ± 4.8 kg/m²) were included; 13.7%, 6.2%, and 5.5% of participants reported 1 day, 2-5 days, and ≥ 6 days of kneeling activities per week. A higher frequency of kneeling activity was associated with the increased risk of MOAKS cartilage score worsening (adjusted OR (95% CI): 2.33 (1.08-5.06)). Stratification analysis showed that only ≥ 6 days/week of kneeling activities was associated with the worsening of MOAKS cartilage scores (2.74 (1.03-7.27)). When we included the presence of PA in regression models, the OR (95% CI) for the association between kneeling and PF cartilage damage will decrease to 1.26 (0.78-2.04), suggesting the potential role of PA as the moderator variable.

CONCLUSION

Extensive kneeling activity (≥ 6 days/week) may be associated with the MRI-based worsening of PF cartilage damage, specifically in subjects with an underlying patella alta.

KEY POINTS

• Frequent daily kneeling activity is associated with a higher risk of patellofemoral cartilage damage resulting in patellofemoral osteoarthritis. • The cartilage damage associated with extensive kneeling activity may be worse in subjects with an underlying patella alta (i.e., high-riding patella).

Patellofemoral Mechanics: a Review of Pathomechanics and Research Approaches

PURPOSE OF REVIEW

The patellofemoral joint is a complicated articulation of the patella and femur that is prone to pathologies. The purpose of this review is to report on the current methods of investigating patellofemoral mechanics, factors that affect joint function, and future directions in patellofemoral joint research with emerging technologies and techniques.

RECENT FINDINGS

While previous hypotheses have suggested that the patella is only a moment arm extender, recent literature has suggested that the patella influences the control of knee moments and forces acting on the tibia as well as contributes to various aspects of patellar function with minimal neural input. With advancements in simulating a six-degrees-of-freedom patellofemoral joint, we have gained a better understanding of patella motion and have shown that geometry and muscle activations impact patella mechanics. Research into influences on patella mechanics from other joints such as the hip and foot has become more prevalent. In this review, we report current in vivo, in vitro, and in silico approaches to studying the patellofemoral joint. Kinematic and anatomical factors that affect patellofemoral joint function such as patella alta and tilt or bone morphology and ligaments are discussed. Moving forward, we suggest that advanced in vivo dynamic imaging methods coupled to musculoskeletal simulation will provide further understanding of patellofemoral pathomechanics and allow engineers and clinicians to design interventions to mitigate or prevent patellofemoral pathologies.

Patellofemoral alignment and geometry and early signs of osteoarthritis are associated in patellofemoral pain population

Background

Patellofemoral pain (PFP) patients show increased prevalence of patellar malalignment. Structural and alignment abnormalities of the patellofemoral joint (PFJ) may play a role in development of PFP and patellofemoral osteoarthritis (PFOA).

Objectives

Evaluating associations of patellofemoral alignment and femoral geometry with bony and cartilaginous abnormalities in PFP patients and healthy control subjects.

Methods

Data from a case‐control study were used (64 PFP subjects, 70 control subjects, 57% female, age 23.2 (6.4)). Alignment and femoral geometry measures in the PFJ were determined using MRI. Structural abnormalities in the PFJ associated with OA (bone marrow lesions, osteophytes, minor cartilage defects and Hoffa‐synovitis), quantified cartilage composition (T1ρ relaxation times) in the PFJ and perfusion within the patellar bone were examined using different MRI techniques. Associations were analyzed using regression analyses, adjusted for potential confounders.

Results

Lateral patellar tilt was negatively associated with presence of osteophytes on both patella (OR 0.91; 95% CI 0.84 to 0.98), anterior femur (OR 0.92; 95% CI 0.84 to 0.99) and minor cartilage defects on patella (OR 0.91; 95% CI 0.84 to 0.99). Patella alta was positively associated with the presence of bone marrow lesions in the patella and minor cartilage defects (OR 48.33; 95% CI 4.27 to 547.30 and OR 17.51; 95% CI 1.17 to 262.57, respectively). Patella alta and medial patellar translation were positively associated with T1ρ relaxation times within trochlear cartilage (β 5.2; 95% CI 0.77 to 9.58, and 0.36; 95% CI 0.08 to 0.64, respectively). None of the alignment and geometry measures were associated with bone perfusion.

Conclusion

Our study implies that associations between patellofemoral alignment and geometry and structural joint abnormalities linked to OA are already present in both PFP patients and healthy control subjects.

Immediate effects of foot orthoses on gait biomechanics in individuals with persistent patellofemoral pain

BACKGROUND

The efficacy of foot orthoses in reducing patellofemoral pain (PFP) is well documented; however, the mechanisms by which foot orthoses modulate pain and function are poorly understood.

RESEARCH QUESTION

This within-subject study investigated the immediate effects of foot orthoses on lower limb kinematics and angular impulses during level walking and stair ambulation in individuals with persistent PFP.

METHODS

Forty-two participants with persistent PFP (≥3 months duration) underwent quantitative gait analysis during level walking, stair ascent and stair descent while using: (i) standard running sandals (control); and (ii) standard running sandals fitted with prefabricated foot orthoses. Hip, knee, and ankle joint kinematics and angular impulses were calculated and statistically analyzed using paired t-tests (p < 0.05).

RESULTS

Relative to the control condition, foot orthoses use was associated with small but significant decreases in maximum ankle inversion angles during walking (mean difference [95% confidence interval]: -1.00° [-1.48 to -0.53]), stair ascent (-1.06° [-1.66 to -0.45]) and stair decent (-0.94° [-1.40 to -0.49]). Foot orthoses were also associated with decreased ankle eversion impulse during walking (-9.8Nms/kg [-12.7 to -6.8]), and decreased ankle dorsiflexion and eversion impulse during stair ascent (-67.6Nms/kg [-100.7 to -34.6] and -17.5Nms/kg [-23.6 to -11.4], respectively) and descent (-50.4Nms/kg [-77.2 to -23.6] and -11.6Nms/kg [-15.6 to -7.5], respectively). Ankle internal rotation impulse decreased when participants ascended stairs with foot orthoses (-3.3Nms/kg [-5.4 to -1.3]). Limited changes were observed at the knee and hip.

SIGNIFICANCE

In individuals with persistent PFP, small immediate changes in kinematics and angular impulses - primarily at the ankle - were observed when foot orthoses were worn during walking or stair ambulation. The clinical implications of these small changes, as well as the longer-term effects of foot orthoses on lower limb biomechanics, are yet to be determined.

Effects of neuromuscular training and strengthening of trunk and lower limbs muscles in women with Patellofemoral Pain: A protocol of randomized controlled clinical trial, blinded

Background

Patellofemoral pain (PFP) often affects young women, and the etiology is multifactorial and poorly understood. Conservative intervention has been focused on risk factors or aggravating factors and is composed of hip- and knee-strengthening exercises, as this population often has muscle weakness and poor motor control during daily and sports activities. The objective of this study was to evaluate the additional effects of neuromuscular training in a conservative treatment of trunk-, hip-, and knee-muscle strengthening on pain, function, and kinematics of the trunk, pelvis, and lower limb in women with PFP.

Methods

This is a randomised clinical trial, controlled, blinded. Ninety women who are active and engage in physical activity up to twice a week will be recruited. All participants will undergo an individual physiotherapy assessment and then will be allocated randomly into two groups. Thereafter, both groups will undergo a 12-week intervention protocol: group 1 will perform strengthening exercises for the trunk, hip, and knee muscles, while group 2 will receive the same treatment, with the inclusion of neuromuscular training exercises on the fourth week. At the end of the intervention, the volunteers will be evaluated. The primary outcomes will be pain intensity (using a Visual Analog Scale: over the last month, squat 90°, and step of 26 cm during 1 min), functional capacity (Anterior Knee Pain Scale and Activities of Daily Living Scale), and 2D kinematics of the trunk, pelvis, and lower limb during the single-leg squat. The secondary outcomes correspond to the isometric muscular strength of the lower limb and the level of satisfaction from the intervention.

Discussion

The present study was initiated on 28 January 2018 and is currently in progress, scheduled for completion in July 2019. The results of this study should contribute to the physiotherapeutic treatment of women with PFP by aggregating information on the benefits of adding neuromuscular training to strengthening of the trunk and lower-limb muscles.

Trial registration

Registro Brasileiro de Ensaios Clínicos, ID: RBR-8c7267. Registered on 2 August 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3650-7) contains supplementary material, which is available to authorized users.

Altered pain processing and sensitisation is evident in adults with patellofemoral pain: a systematic review including meta-analysis and meta-regression

Background and aims

Previous systematic reviews have reported manifestations of pain sensitisation as a feature of painful knee disorders, in particular osteoarthritis, with moderate evidence for pain sensitisation in patellofemoral pain (PFP). However, despite past studies recruiting female mostly adolescent PFP patients, it is unclear if sex or age plays a role. Investigation is required to determine if altered pain processing is a key feature of PFP and if a subgroup of patients is at an increased risk to help provide targeted management. The primary aim of this systematic review was to examine evidence investigating pain processing in PFP. Secondary aims were to evaluate the relationship between pain processing and (1) sex, (2) age and (3) symptom duration.

Methods

The protocol was prospectively registered with PROSPERO (CRD42019129851). PubMed, CINAHL, Web of Science and EMBASE were systematically searched from inception to April 2019 for studies investigating pain processing in PFP patients compared to controls using quantitative sensory testing. Each included paper was assessed for methodological quality using a modified version of Downs and Black. Means and standard deviations were extracted to calculate standardised mean differences (SMD) and 95% confidence intervals (95% CI). Where possible meta-analysis and meta-regression were performed using a random effects model.

Results

Eleven studies were identified, two medium and nine high quality. Meta-analysis indicates moderate evidence for decreased pressure pain thresholds (SMD −0.68, 95% CI −0.93 to −0.43), increased tactile detection thresholds (SMD 1.35, 95% CI 0.49–2.22) and increased warmth detection thresholds (SMD 0.61, 95% CI 0.30–0.92) in PFP patients compared to controls. Secondary analysis indicates moderate evidence for decreased pressure pain thresholds in female compared to male patients (SMD −0.75, 95% CI −1.34 to −0.16). Meta-regression indicates a moderate correlation between decreasing local and distal pressure pain thresholds and decreasing patient age (local R2 = 0.556, p = 0.0211; distal R2 = 0.491, p = 0.0354) but no correlation with symptom duration (p > 0.05).

Conclusions

Evidence from this systematic review with meta-analysis and meta-regression appears to suggest the presence of altered pain processing and sensitisation in patients with PFP with increased sensitivity indicated in female patients and younger patients.

Implications

With evidence of altered pain processing and sensitisation in PFP, it may be beneficial for clinicians to consider management approaches that aim specifically at adressing neuropathic pain, for example neuroscience education, to improve patients outcomes. With female patients and younger patients indicated as experiencing greater degree of sensitivity, this may be a good demographic to start screening for sensitisation, in order to better identify and treat those most affected.

Patellofemoral Pain

Patellofemoral pain (PFP) is a common musculoskeletal-related condition that is characterized by insidious onset of poorly defined pain, localized to the anterior retropatellar and/or peripatellar region of the knee. The onset of symptoms can be slow or acutely develop with a worsening of pain accompanying lower-limb loading activities (eg, squatting, prolonged sitting, ascending/descending stairs, jumping, or running). Symptoms can restrict participation in physical activity, sports, and work, as well as recur and persist for years. This clinical practice guideline will allow physical therapists and other rehabilitation specialists to stay up to date with evolving PFP knowledge and practices, and help them to make evidence-based treatment decisions. J Orthop Sports Phys Ther. 2019;49(9):CPG1-CPG95. doi:10.2519/jospt.2019.0302.

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.

Toward the Development of Data-Driven Diagnostic Subgroups for People With Patellofemoral Pain Using Modifiable Clinical, Biomechanical, and Imaging Features

BACKGROUND

Unfavorable treatment outcomes for people with patellofemoral pain (PFP) have been attributed to the potential existence of subgroups that respond differently to treatment.

OBJECTIVES

This study aimed to identify subgroups within PFP by combining modifiable clinical, biomechanical, and imaging features and exploring the prognosis of these subgroups.

METHODS

This was a longitudinal cohort study, with baseline cluster analyses. Baseline data were analyzed using a 2-stage cluster analysis; 10 features were analyzed within 4 health domains before being combined at the second stage. Prognosis of the subgroups was assessed at 12 months, with subgroup differences reported as global rating of change and analyzed with an exploratory logistic regression adjusted for known confounders.

RESULTS

Seventy participants were included (mean age, 31 years; 43 [61%] female). Cluster analysis revealed 4 subgroups: "strong," "pronation and malalignment," "weak," and "active and flexible." Descriptively, compared to the strong subgroup (55% favorable), the odds of a favorable outcome were lower in the weak subgroup (31% favorable; adjusted odds ratio [OR] = 0.30; 95% confidence interval [CI]: 0.07, 1.36) and the pronation and malalignment subgroup (50%; OR = 0.64; 95% CI: 0.11, 3.66), and higher in the active and flexible subgroup (63%; OR = 1.24; 95% CI: 0.20, 7.51). After adjustment, compared to the strong subgroup, differences between some subgroups remained substantive, but none were statistically significant.

CONCLUSION

In this relatively small cohort, 4 PFP subgroups were identified that show potentially different outcomes at 12 months. Further research is required to determine whether a stratified treatment approach using these subgroups would improve outcomes for people with PFP.

LEVEL OF EVIDENCE

Diagnosis, level 2b. J Orthop Sports Phys Ther 2019;49(7):536-547. doi:10.2519/jospt.2019.8607.

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.

Hip muscle strength and protection against structural worsening and poor function and disability outcomes in knee osteoarthritis

OBJECTIVE

Examine associations of hip abductor strength with (1) cartilage damage worsening in the tibiofemoral and patellofemoral compartments 2 years later, and (2) poor function and disability outcomes 5 years later.

METHODS

Participants had knee osteoarthritis (K/L ≥ 2) in at least one knee. Hip abductor strength was measured using Biodex Dynamometry. Participants underwent 3.0T MRI of both knees at baseline and 2 years later. Baseline-to-2-year cartilage damage progression, defined as any worsening of WORMS cartilage damage score, was assessed at each tibiofemoral and patellofemoral surface. LLFDI (Late-Life Function and Disability Instrument) and Chair-Stand-Rate were recorded at baseline and 5-year follow-up; outcomes analyzed using quintiles. Poor outcomes were defined as remaining in the same low-function quintiles or being in a worse quintile at 5-year follow-up. We analyzed associations of baseline hip abductor strength with cartilage damage worsening and function and disability outcomes using multivariable log-binomial models.

RESULTS

275 knees from 164 persons [age = 63.7 (SD = 9.8) years, 79.3% women] comprised the structural outcome sample, and 187 persons [age = 64.2 (9.7), 78.6% women] the function and disability outcomes sample. Greater baseline hip abductor strength was associated with reduced risks of baseline-to-2-year medial patellofemoral and lateral tibiofemoral cartilage damage worsening [adjusted relative risks (RRs) range: 0.80-0.83) and with reduced risks of baseline-to-5-year poor outcomes for Chair-Stand-Rate and LLFDI Basic Lower-Extremity Function and Disability Limitation (adjusted RRs range: 0.91-0.94).

CONCLUSION

Findings support a beneficial role of hip abductor strength for disease modification and for function and disability outcomes, and as a potential therapeutic target in managing knee osteoarthritis.

Backward walking alters vastus medialis oblique/vastus lateralis muscle activity ratio in females with patellofemoral pain syndrome

Objectives

This study aims to examine the effect of backward walking (BW) and forward walking (FW) on the myoelectric activity ratio of the vastus medialis oblique (VMO)/vastus lateralis (VL) in females with patellofemoral pain syndrome (PFPS).

Patients and methods

Between September 2016 and December 2016, a total of 40 female participants (mean age 20.9±1.9 years; range, 19 to 26 years) were included in the study. The participants were divided into two groups as those with unilateral PFPS (PFPS group, n=20) and healthy controls (Control group, n=20). Surface electromyography (EMG) from VMO and VL muscles were collected during FW and BW at a speed of 3 km/h using the Myomonitor® IV EMG system.

Results

There was a significant increase in the EMG activities of the VMO and VL muscles during BW compared to FW in PFPS and healthy groups (p=0.001). During BW, the VMO activity of PFPS was significantly higher than the healthy controls (p=0.013) without any significant difference in the VL activity (p=0.916). During FW, there was no significant difference in the VMO and VL activities between the groups (p=0.348 and p=0.705), respectively. The VMO/VL ratio of the PFPS group during BW was significantly higher than the FW ratio (p=0.001) without any significant difference between BW and FW of the healthy group (p=0.841). During BW, the ratio of the PFPS group was significantly higher than compared to the healthy controls (p=0.016) without any significant difference between the groups during FW (p=0.100).

Conclusion

Our study results show that BW increases the VMO muscle activation and preserve the ideal VMO/VL ratio in PFPS patients. Therefore, clinicians should consider BW training when developing rehabilitation programs for females with PFPS.

Hip abductor muscle volumes are smaller in individuals affected by patellofemoral joint osteoarthritis

OBJECTIVE

The aims of this study were twofold: firstly, to compare hip abductor muscle volumes in individuals with patellofemoral joint (PFJ) osteoarthritis (PFJ OA) against those of healthy controls; and secondly, to determine whether hip muscle volumes and hip kinematics during walking are related in individuals with PFJ OA and healthy controls.

METHODS

Fifty-one individuals with PFJ OA and thirteen asymptomatic, age-matched healthy controls ≥40 years were recruited. Volumes of the gluteus medius, gluteus minimus and tensor fasciae latae were obtained from magnetic resonance (MR) images. Video motion capture was used to measure three-dimensional hip joint kinematics during overground walking.

RESULTS

Significantly smaller gluteus medius (P = 0.017), gluteus minimus (P = 0.001) and tensor fasciae latae (P = 0.027) muscle volumes were observed in PFJ OA participants compared to controls. Weak correlations were observed between smaller gluteus minimus volume and larger hip flexion angle at contralateral heel strike (CHS) (r = -0.279, P = 0.038) as well as between smaller gluteus minimus volume and increased hip adduction angle at CHS (r = -0.286, P = 0.046).

CONCLUSION

Reduced hip abductor muscle volume is a feature of PFJ OA and is associated with increased hip flexion and adduction angles during the late stance phase of walking for PFJ OA participants and healthy controls.

Backward walking effects on activation pattern of leg muscles in young females with patellofemoral pain syndrome

Background/Aims:

Little is known regarding the activation of knee and hip muscles during backward walking in patellofemoral pain syndrome. This study examineD the effects of backward walking and forward walking on the activation of knee extensors, hip abductors, and adductors in patients with patellofemoral pain syndrome.

Methods:

A total of 20 females with patellofemoral pain syndrome and 20 age-matched typically healthy female controls participated in this study. Surface electromyography from vastus medialis obliquus, vastus lateralis, gluteus medius, and adductor longus muscles were collected during forward walking and backward walking.

Findings:

The patellofemoral pain syndrome group had a significantly higher normalised root mean square of the vastus medialis obliquus, vastus lateralis and gluteus medius muscles (P=0.001), without significant difference in adductor longus muscle activity during backward walking versus forward walking (P=0.098). During forward walking, the patellofemoral pain syndrome group showed significantly higher activation of adductor longus muscle (P=0.001) and significantly lower activation of the gluteus medius muscle (P=0.002) compared to the healthy group. During backward walking there was a significant increase in the vastus medialis obliquus and adductor longus muscle activity of the patellofemoral pain syndrome group compared to the control group (P=0.003, 0.001) respectively.

Conclusions:

Clinicians should consider backward walking training to increase the muscle strength of knee extensors and hip abductors when developing rehabilitation programmes for patients with patellofemoral pain syndrome.

Are Patellofemoral Joint Alignment and Shape Associated With Structural Magnetic Resonance Imaging Abnormalities and Symptoms Among People With Patellofemoral Pain?

BACKGROUND

Patellofemoral malalignment has been observed among people with patellofemoral pain (PFP) and may be associated with the presence of imaging features of osteoarthritis, symptoms, and function.

PURPOSE

To determine whether patellofemoral joint alignment and bony shape are associated with (1) cartilage, bone, and soft tissue morphological abnormalities defined on magnetic resonance imaging (MRI) and (2) reported symptoms and function among people with PFP.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Participants (mean ± SD age, 30.2 ± 9.5 years; range, 14-50 years; 78 females, 58.6%) completed questionnaires regarding demographics, pain, symptoms, and function and underwent a 3-T MRI scan of their more symptomatic eligible knee. Structural MRI abnormalities were scored with the MOAKS (Magnetic Resonance Imaging Osteoarthritis Knee Score), and MRI alignment and shape were measured with standardized methods. Associations among MOAKS features, PFP symptoms, and alignment and shape measures were evaluated with regression analyses (α = .05).

RESULTS

Minor cartilage defects were present in 22 (16.5%) participants, patellar osteophytes in 83 (62.4%), anterior femur osteophytes in 29 (21.8%), Hoffa synovitis in 81 (60.9%), and prefemoral fat pad synovitis in 49 (36.8%). A larger Insall-Salvati ratio was significantly associated with the presence of patellar osteophytes (odds ratio [OR], 51.82; 95% CI, 4.20-640.01), Hoffa synovitis (OR, 60.37; 95% CI, 4.66-782.61), and prefemoral fat pad synovitis (OR, 43.31; 95% CI, 4.28-438.72) in the patellofemoral joint. A larger patellar tilt angle was significantly associated with the presence of minor cartilage defects (OR, 1.10; 95% CI, 1.00-1.20), the presence of patellar osteophytes (OR 1.12; 95%CI 1.02-1.22), and prefemoral fat pad synovitis (OR, 1.11; 95% CI, 1.03-1.20) in the patellofemoral joint. Finally, a larger bisect offset was significantly associated with the presence of minor cartilage defects (OR, 1.05; 95% CI, 1.00-1.11) and patellar osteophytes (OR, 1.07; 95% CI, 1.01-1.14) in the patellofemoral joint. The majority of patellofemoral alignment measures were not associated with symptoms or function.

CONCLUSION

For people with PFP, the presence of morphological abnormalities defined on MRI appears to be related to particular patellofemoral alignment measures, including higher Insall-Salvati ratio (indicating patella alta), larger patellar tilt angle (indicating greater lateral tilt), and larger bisect offset (indicating greater lateral displacement). Hardly any associations were found with symptoms or function. So there might be a distinct subgroup of PFP that is more prone to developing patellofemoral osteoarthritis later in life, as particular alignment measures seem to be associated with the presence of patellar osteophytes. Prospective studies are required to investigate the longitudinal relationship between alignment or bony shape and morphological abnormalities defined on MRI in this patient population.

Is patellofemoral pain a precursor to osteoarthritis?: Patellofemoral osteoarthritis and patellofemoral pain patients share aberrant patellar shape compared with healthy controls

Objectives

It has been hypothesized that patellofemoral pain, a common knee condition in adolescents and young adults, may be a precursor of degenerative joint changes and may ultimately lead to patellofemoral osteoarthritis. Since both conditions share several mechanical disease characteristics, such as altered contact area between the femur and patella and increased joint stress, we investigated whether these conditions share similar and different shape characteristics of the patella compared with normal controls.

Methods

This cross-sectional study compared three different study populations: 32 patellofemoral pain subjects (mean age, 32 years (22 to 45); 72% female); 56 isolated radiological patellofemoral osteoarthritis subjects (mean age, 54 years (44 to 58); 89% female); and 80 healthy control subjects (mean age, 52 years (44 to 58); 74% female). Measurements included questionnaires, and lateral and skyline radiographs of the knee. Two separate 30-point 2D statistical shape models of the patella were created from the lateral and skyline radiographs. A general linear model was used to test for differences in standardized shape modes (a specific shape variant of the patella) between patellofemoral osteoarthritis, patellofemoral pain, and controls, using Bonferroni correction and adjustment for body mass index and gender.

Results

Five shape modes showed statistically significant differences between groups: skyline modes 1 (p < 0.001), 8 (p = 0.004), and 10 (p < 0.001); and lateral modes 5 (p = 0.002) and 7 (p = 0.002). Skyline mode 8 and lateral mode 5 were similar for patellofemoral osteoarthritis and patellofemoral pain populations, while being statistically significant different from the control group.

Conclusion

Our results indicate that patellofemoral pain and patellofemoral osteoarthritis share similar shape characteristics, which are different from control subjects. These findings support the proposed continuum disease model of patellofemoral pain predisposing to the development of patellofemoral osteoarthritis.

Cite this article: J. F. A. Eijkenboom, J. H. Waarsing, E. H. G. Oei, S. M. A. Bierma-Zeinstra, M. van Middelkoop. Is patellofemoral pain a precursor to osteoarthritis? Patellofemoral osteoarthritis and patellofemoral pain patients share aberrant patellar shape compared with healthy controls. Bone Joint Res 2018;7:541–547. DOI: 10.1302/2046-3758.79.BJR-2018-0112.R1.

Risk factors for patellofemoral pain: a systematic review and meta-analysis

BACKGROUND

Patellofemoral pain (PFP) is a prevalent condition commencing at various points throughout life. We aimed to provide an evidence synthesis concerning predictive variables for PFP, to aid development of preventative interventions.

METHODS

We searched Medline, Web of Science and SCOPUS until February 2017 for prospective studies investigating at least one potential risk factor for future PFP. Two independent reviewers appraised methodological quality using the Newcastle-Ottawa Scale. We conducted meta-analysis where appropriate, with standardised mean differences (SMD) and risk ratios calculated for continuous and nominal scaled data.

RESULTS

This review included 18 studies involving 4818 participants, of whom 483 developed PFP (heterogeneous incidence 10%). Three distinct subgroups (military recruits, adolescents and recreational runners) were identified. Strong to moderate evidence indicated that age, height, weight, body mass index (BMI), body fat and Q angle were not risk factors for future PFP. Moderate evidence indicated that quadriceps weakness was a risk factor for future PFP in the military, especially when normalised by BMI (SMD -0.69, CI -1.02, -0.35). Moderate evidence indicated that hip weakness was not a risk factor for future PFP (multiple pooled SMDs, range -0.09 to -0.20), but in adolescents, moderate evidence indicated that increased hip abduction strength was a risk factor for future PFP (SMD 0.71, CI 0.39, 1.04).

CONCLUSIONS

This review identified multiple variables that did not predict future PFP, but quadriceps weakness in military recruits and higher hip strength in adolescents were risk factors for PFP. Identifying modifiable risk factors is an urgent priority to improve prevention and treatment outcomes.

Patellar Tendon Reflex and Vastus Medialis Hoffmann Reflex Are Down Regulated and Correlated in Women With Patellofemoral Pain

OBJECTIVES

The aims of this study were threefold: (1) to compare the amplitude of patellar tendon reflex (T-reflex) between women with patellofemoral pain (PFP) and pain-free controls; (2) to compare the amplitude of vastus medialis Hoffmann reflex (VM H-reflex) between women with PFP and pain-free controls; (3) to investigate the association between the amplitude of patellar T-reflex and VM H-reflex in women with PFP and pain-free controls.

DESIGN

Cross-sectional observational study.

SETTING

Laboratory of biomechanics and motor control.

PARTICIPANTS

Thirty women with PFP and 30 pain-free women aged 18 to 35 years (N=60).

MAIN OUTCOME MEASURES

Peak-to-peak amplitudes of maximal VM H-reflex (elicited via electrical stimulation on the femoral nerve) and patellar T-reflex (elicited via mechanical percussion on the patellar tendon) were estimated.

RESULTS

Women with PFP had significant lower amplitude of patellar T-reflex (mean difference=0.086; 95% confidence interval=0.020 to 0.151; P=.010; moderate effect) and VM H-reflex (mean difference=0.150; 95% confidence interval =0.073 to 0.227; P<.001; large effect) compared to pain-free controls. The VM H-reflex was strongly correlated with patellar T-reflex in both PFP group (r=0.66; P<.001) and control group (r=0.72; P<.001).

CONCLUSIONS

As the T-reflex is easier to perform than H-reflex assessments in a clinical setting, it represents a feasible option to assess the impaired excitability of the stretch reflex pathway associated with PFP.

Differences in pain and function between adolescent athletes and physically active non-athletes with patellofemoral pain

OBJECTIVES

To investigate pain level and function limitation in adolescent athletes and physically active non-athletes with PFP.

DESIGN

Cross-sectional study.

SETTING

Adolescent athletes were recruited at a sport center complex. Adolescent non-athletes were recruited from upper secondary schools.

PARTICIPANTS

108 adolescents diagnosed with PFP: 42 adolescent athletes and 66 adolescent non-athletes.

MAIN OUTCOME MEASURES

To evaluate the level of pain, a visual analog scale (VAS) was used and to evaluate the overall function, the Knee Outcome in Osteoarthritis Survey (KOOS) was used.

RESULTS

The adolescent athletes scored significantly higher in the VAS (Mean difference = 0.97 (95% CI = 0.35; 1.60) p = 0.003) compared to adolescent non-athletes. Adolescent athletes scored lower in the KOOS - Symptoms, Pain, Knee-related quality of life and Sport and recreation dimensions - than the non-athletes, however, the minimally clinically important difference was not achieved in Pain dimension. There was no significant difference in the Activities of daily living dimension of the KOOS.

CONCLUSIONS

Adolescent athletes presented higher levels of pain and lower physical function status compared with physically active non-athletes. This provides an important insight to the management of PFP in adolescent athletes as worst functional status is linked with poor prognosis in patients with PFP.