The influence of altered lower-extremity kinematics on patellofemoral joint dysfunction: a theoretical perspective

The association between genu recurvatum angle and the strength of the hip and knee muscles in standing workers

BACKGROUND

Increased genu recurvatum (GR) angle is a risk factor for knee injury. Identification of factors causing GR is important for the prevention and rehabilitation of GR. Few studies have investigated the association between muscle strength and GR.

OBJECTIVE

To examine the association between GR angle and hip and knee muscle strength in standing workersMETHODS:The participants in this study were 110 healthy volunteers (59 male, 51 female) who performed standing work in a theme park. The GR angle, muscle strength, and strength ratio of the lower extremities were measured to determine their associations with GR. The GR angle was measured using a Smart KEMA motion sensor, and muscle strength was assessed using a Smart KEMA strength sensor. Stepwise multiple regression models were used to investigate which muscles contributed most to the extent of the GR angle.

RESULTS

Stepwise multiple regression analysis showed that the decreased hip external rotator to hip internal rotator ratio, increased knee extensor to knee flexor ratio, and young age were associated with an increased GR angle.

CONCLUSIONS

Many factors are known to increase the GR angle. However, this study investigated the roles of only hip and knee muscle strength. The results suggest that muscle strength ratios are more important than the weakness of any muscle.

Visual rating of movement quality in individuals with and without a history of intra-articular knee injury

Objective: To investigate the use of visually rated movement quality in a group including those with a history of intra-articular knee injury.Design: Historical cohort study.Setting: Laboratory.Participants: A total of 115 youth and young adults (62 previously injured).Main outcome measures: Inter-rater agreement for ratings of movement quality during single limb squat and vertical drop jump (VDJ) were assessed. Odds ratios were calculated to determine if the history of knee injury was associated with greater odds of poor movement quality. The difference in knee:ankle separation ratio between the injured and uninjured groups was compared.Results: Rater agreement was moderate to excellent (κ = 0.55 to 0.93). Comparing the injured and uninjured limb in previously injured participants or injured participants to matched uninjured controls, there was no significant difference in the proportion of good versus poor movement ratings (diff = 0% to 10%; p ≥ 0.23). Prior history of knee injury did not increase the odds of poor movement quality during the VDJ (OR 0.91; 95% CI 0.41 to 2.03) or single leg squat (OR 1.04; 95% CI 0.38 to 2.85) and there was no significant difference in the knee:ankle separation ratios (mean diff -0.03; p = 0.30).Conclusion: Visual rating of movement in individuals with and without a history of knee injury is reliable. A history of knee injury does not increase the likelihood of poor visually rated movement quality.

A descriptive report of the variability in 3D hip and knee kinematics during a single limb squat in women who have patellofemoral pain and visually classified dynamic knee valgus

Objective: To describe the variability in: (1) the contributions of 3D hip and knee kinematics to the dynamic knee valgus (DKV) movement pattern during a single limb squat in women with patellofemoral pain; and (2) the 3D strategies used to reduce DKV following an intervention.Methods: Secondary analysis of a feasibility study investigating a movement training intervention. In 23 participants, 2D knee frontal plane projection angles (FPPA) and 3D hip and knee frontal and transverse plane angles at peak knee flexion were calculated during a single limb squat at pre- and post-intervention, and the change in 2D and 3D angles computed. 3D angles at pre-intervention were summed for each participant to create cumulative bar graphs. Similar graphs were created for change in 3D angles. For visual comparison, graphs were ordered by increasing knee FPPA or change in knee FPPA.Results: The knee FPPA decreased from a mean of 7.2 degrees (SD: 7.1) to a mean of -8.9 degrees (SD: 8.9) following the intervention. A large portion of DKV, and change in DKV, was due to hip adduction and knee lateral rotation, yet participants with similar knee FPPA and change in knee FPPA displayed variation in all 3D components and change in 3D components.Conclusion: People who demonstrate similar observed movement patterns during a weight-bearing task may use different 3D strategies for execution.

Rotational Malalignment of the Knee Extensor Mechanism: Defining Rotation of the Quadriceps and Its Role in the Spectrum of Patellofemoral Joint Instability

Osseous rotational malalignment of the lower limb is widely accepted as a factor contributing to patellofemoral instability, particularly in pediatric patients. Patellar instability occurs when the lateral force vector generated by the quadriceps exceeds the restraints provided by osseous and soft-tissue anatomy. The anatomy and activation of the quadriceps are responsible for the force applied across the patellofemoral joint, which has previously been measured using the quadriceps (Q)-angle. To our knowledge, the contribution of the quadriceps anatomy in generating a force vector in the axial plane has not previously been assessed. The primary aim of this study was to introduce the quadriceps torsion angle, a measure of quadriceps rotational alignment in the juvenile population. The secondary aims of this study were to determine the inter-assessor and intra-assessor reliability of the quadriceps torsion angle in the juvenile population and to investigate whether a large quadriceps torsion angle is a classifier of patellar dislocator group membership in a mixed cohort of patellar dislocators and typically developing controls.

Influence of the Powers™ strap on pain and lower limb biomechanics in individuals with patellofemoral pain

BACKGROUND

Abnormal biomechanics, especially hip internal rotation and adduction are known to be associated with patellofemoral pain (PFP). The Powers™ strap was designed to decrease hip internal rotation and to thereby stabilise the patellofemoral joint.

OBJECTIVES

This study aimed to investigate whether the Powers™ strap influenced pain and lower limb biomechanics during running and squatting in individuals with PFP.

METHODS

Twenty-four individuals with PFP were recruited using advertisements that were placed at fitness centres. They were asked to perform a single leg squat task (SLS) and to run on an indoor track at their own selected speed during two conditions: with and without the Powers™ strap. Immediate pain was assessed with the numeric pain rating scale. Three-dimensional motion and ground reaction force data were collected with 10 Qualisys cameras and three AMTI force plates.

RESULTS

Immediate pain was significantly reduced with the Powers™ strap (without the Powers™ strap: 4.04 ± 1.91; with the Powers™ strap: 1.93 ± 2.13). The Powers™ strap condition significantly increased hip external rotation by 4.7° during the stance phase in running and by 2.5° during the single leg squat task. Furthermore, the external knee adduction moment during the SLS and running increased significantly.

CONCLUSION

This study assessed the effect of the Powers™ strap on lower limbs kinematics and kinetics in individual with PFP. The results suggest that the Powers™ strap has the potential to improve abnormal hip motion. Furthermore, the Powers™ strap demonstrated an ability to significantly reduce pain during functional tasks in patients with PFP.

Update of Risk Factors, Diagnosis, and Management of Patellofemoral Pain

PURPOSE OF REVIEW

Patellofemoral pain is the most common cause of anterior knee pain. The purpose of this review is to examine the latest research on risk factors, physical examination, and treatment of patellofemoral pain to improve accuracy of diagnosis and increase use of efficacious treatment modalities.

RECENT FINDINGS

The latest research suggests patellofemoral pain pathophysiology is a combination of biomechanical, behavioral, and psychological factors. Research into targeted exercise therapy and other conservative therapy modalities have shown efficacy especially when used in combination. New techniques such as blood flow restriction therapy, gait retraining, and acupuncture show promise but require further well-designed studies. Patellofemoral pain is most commonly attributed to altered stress to the patellofemoral joint from intrinsic knee factors, alterations in the kinetic chain, or errors in training. Diagnosis can be made with a thorough assessment of clinical history and risk factors, and a comprehensive physical examination. The ideal treatment is a combination of conservative treatment modalities ideally individualized to the risk factors identified in each patient. Ongoing research should continue to identify biomechanical risk factors and new treatments as well as look for more efficient ways to identify patients who are amenable to treatments.

Hip Abductor and Adductor Muscles Activity Patterns During Landing After Anterior Cruciate Ligament Injury

Context: Hamstring and quadriceps activity adaptations are well known in individuals with anterior cruciate ligament deficiency (ACLD) and reconstructed (ACLR) to potentially compensate for knee joint instability. However, few studies have explored hip muscles activity patterns after ACL injury. Objective: To examine the activation characteristics of gluteus medius (GMED) and adductor longus in ACLR and ACLD subjects compared with controls. Design: Case–control study. Setting: Athletic training room and university lab. Participants: Twelve healthy and 24 ACL-injured (12 ACLR and 12 ACLD) recreationally active male volunteers. Interventions: Surface electromyography of the GMED and adductor longus were recorded during a single-leg vertical drop landing and normalized to maximum voluntary isometric contractions. Main Outcome Measures: Preparatory and reactive muscle activity and coactivation were analyzed from 100 milliseconds prior to initial contact to 250 milliseconds postcontact. Results: During reactive activity, ACL-injured (ACLR and ACLD) participants demonstrated significantly lower peak GMED activity compared with controls (F = 4.33, P = .02). In addition, ACLR participants exhibited significantly lower reactive GMED:adductor longus coactivation muscle activity compared with controls (F = 4.09, P = .03). Conclusion: Our findings suggest neuromuscular adaptations of the hip musculature are present in people at least 2 years from ACL injury. GMED activation exercises should be considered in designing rehabilitation programs for ACL-injured individuals.

Use of Pelvic Corrective Force With Visual Feedback Improves Paretic Leg Muscle Activities and Gait Performance After Stroke

The purpose of this study was to examine the effects of combined pelvic corrective force and visual feedback during treadmill walking on paretic leg muscle activity and gait characteristics in individuals with post-stroke hemiparesis. Fifteen chronic stroke participants completed visual feedback only and combined pelvic corrective force and visual feedback conditions during treadmill walking. Each condition included: 1-minute baseline, 7-minute training with visual feedback only or additional pelvic corrective force, 1-minute post training, 1-minute standing break, and another 5-minute training. EMGs from the paretic leg muscles and step length were measured. Overground walking was evaluated before treadmill walking, immediately and 10 minutes after treadmill walking. Greater increases in integrated EMG of all muscles, except vastus medialis and tibialis anterior, were observed with the application of additional pelvic corrective force compared to visual feedback only during treadmill walking. Overground walking speed significantly increased after treadmill training with combined pelvic correction force and visual feedback, but was not significant for the visual feedback only condition. Voluntary weight shifting with additional pelvic corrective force enhanced paretic leg muscle activities and improved gait characteristics during walking. Individuals with post-stroke hemiparesis could adapt feedforward control and generalize the adaptation to overground walking.

Frequency and associated factors of poor knee alignment in young Brazilian volleyball players

Objectives: Poor knee alignment during the deceleration phase of closed kinetic chain movements, such as landings, is a relevant risk factor for injuries in sports. This study assessed the knee alignment and possible associated factors in young Brazilian volleyball athletes Methods: One hundred and seventeen athletes of both genders (9-19 years old) were assessed during a drop jump for the observation of knee alignment. Chi-square test was used to describe the association between poor knee alignment and: gender, age category (≤14 years and ≥15 years), sports experience, participation in competitions, the presence of knee pain during training, and history of lower limb injury Results: Seventy percent of athletes presented poor knee alignment, which was slightly associated with a sports experience lower than one year. Conclusion: Thus, considering the high number of volleyball practitioners and its strong presence in physical education classes, preventive measures should be adopted for young volleyball athletes of both genders, especially in the sports initiation phase.

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.

Added Value of Gluteus Medius and Quadratus Lumborum Dry Needling in Improving Knee Pain and Function in Female Athletes With Patellofemoral Pain Syndrome: A Randomized Clinical Trial

OBJECTIVE

To compare the effects of exercise therapy alone and exercise therapy plus gluteus medius (GM) and quadratus lumbarum (QL) dry needling on pain and function in female athletes with patellofemoral pain (PFP).

DESIGN

Single-blind randomized controlled trial with follow-up.

SETTING

Physiotherapy clinic.

PARTICIPANTS

Convenience sample of female athletes with PFP (N=40), who were randomly assigned to the exercise therapy (Ex group) or exercise-therapy+dry needling (Ex+DN group) group.

INTERVENTIONS

The Ex group received exercise therapy for 4 weeks, and the Ex+DN group received exercise therapy in combination with dry needling directed at GM and QL trigger points for 4 weeks.

MAIN OUTCOME MEASURES

In all participants, pain intensity, function (Kujala score, modified star excursion balance test, step-down test), and QL and GM pressure pain threshold (PPT) were recorded at baseline and at 4 and 6 weeks after the start of treatment. Analysis of variance (2 groups×3 times) was used to compare within- and between-group differences.

RESULTS

The group versus time interaction effect was significant for all variables (P<.05). Both groups showed significant improvements in pain, function, and PPT at weeks 4 and 6 compared to baseline (P<.05). Between-groups comparisons showed significantly greater improvements in pain, function, and PPT in the Ex+DN group (P<.05).

CONCLUSIONS

Targeting intervention to treat trigger points in the GM and QL muscles combined with exercise therapy had superior beneficial effects compared to exercise alone in managing PFP. Therefore, adding GM and QL muscle dry needling to exercise therapy may be advisable to enhance the effects of PFP rehabilitation.

Anterior Cruciate Ligament Injury Mechanisms and the Kinetic Chain Linkage: The Effect of Proximal Joint Stiffness on Distal Knee Control During Bilateral Landings

BACKGROUND

Neuromuscular deficits at the trunk and hip may contribute to dynamic knee valgus and anterior cruciate ligament injury mechanisms. However, comprehensive examination of neuromuscular patterns and their mechanical influence is lacking.

OBJECTIVES

To investigate the influence of lumbar spine joint rotational stiffness (JRS) and the gluteal musculature contribution to hip JRS on dynamic knee valgus.

METHODS

In this cross-sectional study, 18 university-aged women completed a drop vertical jump while we measured kinematics, kinetics, and 24 channels of electromyography (EMG) spanning the trunk and hip musculature. We classified each limb as high or low valgus, based on frontal plane knee displacement magnitude. We used anatomically detailed, EMG-driven biomechanical models to quantify lumbar spine JRS and muscle contributions to hip JRS.

RESULTS

Low-valgus limbs generated greater gluteus medius frontal JRS (P = .002; effect size, 1.3) and gluteus maximus transverse JRS (P = .003; effect size, 1.2) compared to high-valgus limbs. Participants with bilateral high-valgus collapse had substantially reduced lumbar spine sagittal JRS compared to the group with low valgus on both limbs (P = .05; effect size, 5.1). Those with low valgus on both limbs also had a peak lumbar spine flexion angle of 24° ± 4°, compared to the bilateral high-valgus group's angle of 38° ± 10° (P = .09; effect size, 1.8).

CONCLUSION

Participants who avoided high medial knee displacement had greater proximal JRS. Increased JRS at the lumbar spine and greater JRS contributions from the gluteal musculature are linked with preventing high medial knee displacement. J Orthop Sports Phys Ther 2019;49(8):601-610. Epub 26 May 2019. doi:10.2519/jospt.2019.8248.

Effect of muscle strengthening on perceived pain and static knee angles in young subjects with patellofemoral pain syndrome

The purpose of this pilot study was to determine the effects of strength training of the knee muscles on perceived pain and static knee angles in young subjects with patellofemoral pain syndrome (PFPS). Ten patients, 100% female (mean age, 18.2±3.8 years), with unilateral PFPS (anterior knee pain for at least 3 months), received muscle strengthening of the hip and knee (10 sessions over a period of 3 weeks). The outcome measures were perceived pain (visual analogue scale, VAS) and static knee angles (knee rotation measurer). All measures were collected at pre-, postintervention, and at 1-month follow-up (VAS). Muscle strengthening reduced perceived pain after intervention in 90.8% in subjects and this result was maintained at 1-month follow-up (all, P=0.001). Regarding changes in static knee angles, no significant improvements were found in internal and external rotation; valgus and varus; flexion and recurvatum (all, P>0.05). There was no significant difference between the symptomatic and healthy sides (all, P>0.05). Analyses of the correlation coefficients indicated no significant associations between changes in perceived pain and static knee angles. The current study found that muscle strengthening addressed to the symptomatic knee reduced pain; however, perceived pain was not associated with static knee angles in young subjects with unilateral PFPS.

Validity and clinical significance of a clinical method to measure femoral anteversion

BACKGROUND

An increased femoral anteversion may be a risk factor for patellofemoral pain and is measured by Craig's Test clinically using a goniometer. However, its validity has not been examined. The purpose of the present study was to examine the validity of Craig's Test, with those measured using computed tomography (CT), and to investigate the relationship between femoral anteversion and knee external rotation.

METHODS

Twenty-six college students (13 men and 13 women) were measured their femoral anteversion values by Craig's Test (FACraig) and CT (FACT) and knee external rotation values by CT (KERCT). Multiple regression analysis to predict FACraig using FACT and sex was conducted. Mixed design (Measurements × sex) ANOVA examined the difference in FACraig and FACT. Pearson's correlation coefficients examined the relationships between FACT and KERCT for each sex.

RESULTS

FACT (B=0.41, P=0.014) and sex (B=-5.22, P=0.075) together explained 23.4% of the variance in FACraig (F=3.52, P=0.046). FACraig was significantly smaller than FACT in females while no significant difference was found in males. Greater FACT was significantly related with greater KERCT (r=0.47, P=0.02) in females only.

CONCLUSIONS

Craig's Test does not provide highly valid values to reflect the true femoral anteversion despite its clinical significance. Greater femoral anteversion may be associated with increased static knee external rotation, possibly resulting in increased quadriceps-angle and thus patellofemoral pain risk.

Visual assessment of movement quality in the single leg squat test: a review and meta-analysis of inter-rater and intrarater reliability

Single leg squat (SLS) is a common tool used in clinical examination to set and evaluate rehabilitation goals, but also to assess lower extremity function in active people.

Avaliação funcional do movimento: incidência do valgo dinâmico do joelho em mulheres praticantes de musculação e sedentárias

RESUMO A avaliação do movimento é importante e necessária para identificar os riscos de lesão possibilitando a elaboração de programas de exercícios preventivos e corretivos, visando a melhora do desempenho das atividades funcionais e o consequente bem-estar. O objetivo deste estudo foi analisar e comparar a incidência do valgo dinâmico do joelho em mulheres praticantes de musculação e mulheres sedentárias, e identificar os sintomas álgicos e o potencial de lesão associados a essa alteração biomecânica. Sessenta mulheres foram divididas em dois grupos: praticantes de musculação e sedentárias, com idade entre 18 e 30 anos. Os dados foram coletados utilizando-se o sistema Functional Movement Screen e foram submetidos a análises estatísticas descritiva e inferencial. O valgo dinâmico do joelho é apresentado por 60% das mulheres sedentárias, quando comparadas às mulheres praticantes de musculação (33,3%), demonstrando associação entre o valgo dinâmico e o sedentarismo (p<0,03). Não houve associação entre a dor e o valgo dinâmico do joelho (p>0,06) para ambos os grupos. Das mulheres sedentárias, 50,0% apresentaram escore FMS abaixo de seis pontos, representando alto risco de lesão. Conclui-se que mulheres sedentárias apresentam maior predisposição ao valgismo dinâmico do joelho, maior sintomatologia dolorosa e maior risco de lesão nos membros inferiores.

Do neoprene sleeves and prophylactic knee braces affect neuromuscular control and cutting agility?

OBJECTIVES

To evaluate the effects of neoprene sleeves (NSs) and prophylactic knee braces (PKBs) on neuromuscular control and cutting agility.

DESIGN

Markerless motion-capture technology tracked subjects (1) without a brace as a control (2) with NSs and (3) with PKBs during single-leg drop vertical jump (SLDVJ), single-leg squat (SLS), Y-excursion, and cutting movements. Movements were recorded five times per bracing condition in three different sessions.

SETTING

University laboratory.

PARTICIPANTS

Ten healthy, active subjects (5 male, 5 female; age range, 22-26 years).

MAIN OUTCOME MEASURES

Degrees of motion and time to completion.

RESULTS

Use of NSs and PKBs reduced subjects' hip internal rotation in the loading phase of SLDVJ (p = 0.026, 0.02) and SLS (p = 0.005, <0.001), reduced knee flexion in the loading phase of SLDVJ (p = 0.038, <0.001), and reduced knee frontal plane abduction (FPA) with SLS (p = 0.015, 0.024) and Y-excursion (p = 0.002, 0.005) compared to control. Use of PKBs decreased subjects' hip internal rotation in the Y-excursion (p = 0.024) and reduced knee FPA in the SLDVJ loading phase (p = 0.014) compared to control. There was no difference in cutting agility for either group (p = 0.145, 0.347).

CONCLUSION

Both NSs and PKBs positively impacted neuromuscular control without impacting cutting agility.

MEDIAL AND LATERAL HAMSTRINGS RESPONSE AND FORCE PRODUCTION AT VARYING DEGREES OF KNEE FLEXION AND TIBIAL ROTATION IN HEALTHY INDIVIDUALS

Background

Hamstring weakness is a contributor to lower extremity pathology. Influence of knee flexion and tibial rotation on hamstrings muscle activation and knee flexion force has not been documented in the literature.

Hypothesis/Purpose

The purpose of the study was to determine the angle of knee flexion and tibial rotation that elicits the greatest knee flexion force and hamstrings activation in healthy, physically active adults.

Study Design

Descriptive, observational cohort study.

Methods

Eighteen young healthy adults were recruited for study participation. Each individual performed maximal voluntary isometric hamstrings contractions at six different knee flexion angles (15 °, 30 °, 45 °, 60 °, 75 ° & 90 °), each positioned at three different tibial rotation positions (internal rotation, neutral rotation and external rotation). Electromyographic activity of the medial and lateral hamstrings and knee flexion force production were recorded.

Results

On average, greatest force production was recorded at 30 ° knee flexion with tibia either in neutral rotation (124.1% of max) or in external rotation (123.5% of max). This same lower limb orientation also produced the highest amount of lateral hamstring activation (156.4% of max). Results also showed that force production and lateral hamstring activation decreased as knee flexion angle increased. Muscle activation for the medial hamstrings was not affected by knee flexion angle but did show higher activation in neutral or tibial internal rotation.

Conclusion

The results of the current research describe the relationship between knee flexion and tibial rotation and their effect on overall knee flexion force production and hamstrings activation. This research provides key insights about the specific knee joint angles and tibial orientation that may be preferred in exercise prescription for maximizing hamstring activation.

Level of Evidence

Level III.

The Effect of Valgus Control Instruction Exercises on Pain, Strength, and Functionality in Active Females With Patellofemoral Pain Syndrome

BACKGROUND

Patellofemoral pain syndrome (PFPS) is sometimes related to excessive hip adduction and internal rotation, as well as knee valgus during weightbearing activities in females. Research on injury prevention and rehabilitation strategies has shown the positive effects of valgus control instruction (VCI) exercise programs in training.

HYPOTHESIS

A VCI program would result in a positive change in pain, eccentric hip muscle torque, and performance in females with PFPS.

STUDY DESIGN

Controlled laboratory study.

LEVEL OF EVIDENCE

Level 1.

METHODS

Sixty-four amateur female volleyball players from our university (age, 18-25 years) with PFPS and equal years of exercise experience were randomly divided into VCI (n = 32; age, 22.1 ± 5.88 years) and control (n = 32; age, 23.1 ± 6.49 years) groups. Function (single, triple, and crossover hops), strength (hip abductor and external rotators), pain (visual analog scale), and knee valgus angle (single-leg squat) were assessed at baseline and after intervention.

RESULTS

There was a significant difference before and after implementation of the VCI program with regard to pain (49.18% ↓, P = 0.000), single-leg hop test (24.62% ↑, P = 0.000), triple-hop test (23.75% ↑, P = 0.000), crossover hop test (12.88% ↑, P = 0.000), single-leg 6-m timed hop test (7.43% ↓, P = 0.000), knee dynamic valgus angle (59.48% ↓, P = 0.000), peak abductor to adductor eccentric torque ratio (14.60% ↑, P = 0.000), peak external (59.73% ↑, P = 0.023) and internal rotator (15.45% ↑, P = 0.028) eccentric torques, and the ratio of peak external to internal rotator eccentric torque (40.90% ↑, P = 0.000) ( P < 0.05).

CONCLUSION

PFPS rehabilitation and prevention programs should consider VCI exercises to decrease pain, improve strength, and increase athletes' functional performance.

CLINICAL RELEVANCE

This study investigated the effect of VCI exercises on knee valgus angle, pain, and functionality of individuals with PFPS. The VCI program improves performance, knee dynamic valgus angle, and strength in participants with PFPS. A controlled and optimal knee valgus angle during a functional task is the most important factor for injury prevention specialists. VCI training can be used as a supplemental method to prevent and treat lower extremity injury in patients with PFPS.

A study on muscle activity based on the ankle posture for effective exercise with indoor horse riding machine

[Purpose] Although much researches have been conducted on the hippotherapy, the intervention methods of the previous studies focus on the pelvis posture. Thus, this study analyzed the electromyogram (EMG) of trunk muscle and lower limb muscle to analyze the kinetic factors. Based on the analysis, this study aims to compare the muscle load and suggest effective exercise method. [Participants and Methods] This study checked the muscle activity of Rectus abdominis (RA), Erector spinae (ES), Rectus femoris (RF), Adductor magnus (AM) during the exercise using horse riding machine in dorsiflexion position by bending 20 degrees and in neutral position. Each position was performed for 5 minutes and the speed of the horse riding machine was set to medium speed. [Results] Rectus abdominis showed higher muscle activity in dorsiflexion position and the groups had significant differences. Elector spinae showed higher muscle activity in dorsiflexion position and the groups had significant differences. Rectus femoris showed higher muscle activity in dorsiflexion position and the groups had significant differences. Adductor magnus also showed higher muscle activity in dorsiflexion position and the groups had significant differences. [Conclusions] The study result showed that exercise with horse riding machine in dorsiflexion position activates trunk muscle and thigh muscle effectively. Thus, the study suggests more effective posture for the modern people who exercise with horse riding machine for strengthening physical health.

Association of quadriceps angle with plantar pressure distribution, navicular height and calcaneo-tibial angle

OBJECTIVE

The aim of study was to analyze the association between Quadriceps Angle (QA) and plantar pressure, navicular height (NH), and calcaneo-tibial angle (CTA).

METHODS

A total of 64 volunteers (mean age: 22.25 ± 2.54 (range:19-33)) participated in this cross sectional study. EMED-m (Novel GmbH, Germany) electronic pedobarograph was employed for dynamic plantar pressure measurement using two step protocol. The angle between the vertical axis of calcaneus and the long axis of Achilles tendon for CTA. The height of navicular tubercle from the ground was measured while the subject was standing on both feet for NH. QA was measured while the subject was standing in a relaxed posture where both feet bearing equal weight.

RESULTS

There were significant negative correlations between QA and maximum force (MxF) under the 4th. metatarsal head (MH4). The QA was also significantly correlated with MxF and force-time integral (FTI) under the bigtoe (BT). FTI under the 3rd. metatarsal head (MH3), MH4 and 5th. metatarsal head (MH5) were significantly negatively correlated with QA. Pressure-time integral (PTI) under the MH4 and MH5 were found to be significantly negatively correlated with QA. A significant correlation was also found between QA and NH (p < 0.0001), whilst there was no correlation between QA and CTA. Regression analysis showed that NH was appeared as the major contributor for the QA (β = -0.49, p < 0.001) in the dynamic condition, followed by BT-FTI (β = 0.37, p < 0.001) and MH5-MxF (β = -0.21, p < 0.037).

CONCLUSION

These findings may imply that the NH which can at least be controlled by appropriate shoe inserts may affect QA. This way, loading pattern of both plantar region and whole lower extremity may be altered.

LEVEL OF EVIDENCE

Level III, Diagnostic Study.

Ultrasound evaluation of the quadriceps muscles in pronated foot posture

OBJECTIVE

The main goal of this study was to investigate the size of all portions of the quadriceps muscles in individuals with pronated foot posture compared to normal foot posture using ultrasound imaging.

DESIGN

Twenty nine females with pronated foot posture and 29 age-, body weight-, body height-matched females with normal foot posture were recruited from university communities. The muscle thicknesses of the rectus femoris (RF), vastus medialis (VM), vastus medialis oblique (VMO), vastus lateralis (VL) and vastus intermedius (VI) were measured using ultrasound imaging.

RESULTS

The thicknesses of the RF and VMO were significantly smaller in individuals with pronated foot posture compared to normal foot posture (p<0.05). No significant differences were observed in the VM, VL, and VI muscle thicknesses in both groups.

CONCLUSION

Based on the results of the present study, it seems that besides the foot and lower leg muscles, an integrated assessment of proximal knee muscles, especially quadriceps, is required in individuals with pronated foot posture.

Impairment-Based Rehabilitation With Patterned Electrical Neuromuscular Stimulation and Lower Extremity Function in Individuals With Patellofemoral Pain: A Preliminary Study

CONTEXT

Patellofemoral pain (PFP) is a chronic condition that presents with lower extremity muscle weakness, decreased flexibility, subjective functional limitations, pain, and decreased physical activity. Patterned electrical neuromuscular stimulation (PENS) has been shown to affect muscle activation and pain after a single treatment, but its use has not been studied in a rehabilitation trial.

OBJECTIVE

To determine the effects of a 4-week impairment-based rehabilitation program using PENS on subjective function, pain, strength, range of motion, and physical activity in individuals with PFP.

DESIGN

Randomized controlled trial.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 21 patients with PFP (5 males, 16 females; age = 23.4 ± 7.6 years, height = 168.0 ± 7.5 cm, mass = 69.0 ± 19.5 kg).

INTERVENTION(S)

Participants completed a 4-week supervised rehabilitation program in conjunction with random assignment to receive PENS or sham treatments.

MAIN OUTCOME MEASURE(S)

Subjective function, pain, strength, range of motion, and physical activity levels were assessed prerehabilitation and postrehabilitation. Subjective function and pain were also assessed at 6 and 12 months postrehabilitation. Repeated-measures analyses of variance and Tukey post hoc testing were conducted with α ≤ .05. We calculated Cohen d effect sizes with 95% confidence intervals.

RESULTS

Both groups had statistically and clinically meaningful differences in subjective function, pain, strength, range of motion, and activity level after 4 weeks of impairment-based rehabilitation. Improved subjective function was observed in both groups at 6 and 12 months after the interventions. The PENS group had improvements in current pain for all 3 postrehabilitation times compared with baseline measures.

CONCLUSIONS

An impairment-based intervention effectively improved subjective function, pain, strength, range of motion, and physical activity levels in individuals with PFP. Participants who received PENS in addition to the rehabilitation program had improved current pain at 6 and 12 months postrehabilitation compared with baseline scores.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02441712.

Sex differences in sagittal plane control emerge during adolescent growth: a prospective investigation

PURPOSE

Females athletes have a higher incidence of non-contact knee joint injuries compared to their male counterparts. This may be attributable to sex-specific differences in neuromuscular control, which arise during the pubertal growth spurt. The purpose of this longitudinal study was to assess the development of landing kinematics of adolescent male and female athletes during the adolescent growth-spurt.

METHODS

One hundred and eighty-four adolescent athletes (55% male, 45% female; mean age = 13 ± 0.3 years) participated. Testing was undertaken at baseline and then repeated at 6, 12, 18 and 24 months. Participants performed three drop vertical jump (DVJ) trials from a 31 cm box. Frontal and sagittal plane knee joint angles were recorded. The average measurement of the three jumps was used for analysis at each time point. To assess maturation status, participants were categorised according to their age from peak height velocity at baseline. Pre-initial contact knee flexion (pre-IC), peak knee flexion and knee valgus displacement were the dependant variables. The categorical independent variables were sex (male versus female) and time.

RESULTS

There was a significant sex*time interaction for pre-IC knee flexion, with males increasing knee flexion with time to a greater extent than females. There was no significant sex*time interaction for knee valgus displacement; although females displayed greater knee valgus displacement across all time points.

CONCLUSIONS

Adolescent male and female athletes display differing kinematic profiles across growth and development. This has clinical relevance for emphasising increased knee flexion, as well as decreasing abnormal frontal plane displacement in injury prevention programmes for adolescent females.

LEVEL OF EVIDENCE

II.

The decline step-down test measuring the maximum pain-free flexion angle: A reliable and valid performance test in patients with patellofemoral pain

OBJECTIVES

Patients with patellofemoral pain (PFP) experience pain while descending stairs. To date no reliable and valid performance-test exists to assess the maximum pain-free knee flexion angle (MPFFA) as outcome measure during a step-down task. Therefore, the intra- and inter-observer reliability and construct validity of the decline step-down test (DSDT) measuring the MPFFA in patients with PFP were evaluated.

DESIGN

Reliability and construct validity.

SETTING

Private practices in Nijmegen and Utrecht, the Netherlands.

PARTICIPANTS

Patients with PFP.

MAIN OUTCOME MEASURES

The reliability was assessed by repeated measurements of the MPFFA during the DSDT. The construct validity was assessed by correlating the measurements on the DSDT with the Anterior Knee Pain Scale Dutch Version (AKPS-DV) based on a pre-set hypothesis.

RESULTS

Thirty-two participants (forty-eight knees) were eligible for inclusion. The intraclass correlation coefficient (ICC) for intra-observer reliability was ICC_2,1 = 0.83 and ICC_2,1 = 0.85 for inter-observer reliability. The 95% limits of agreement (LoA) showed a width of 27.56° for intra-observer reliability and a width of 24.42° for inter-observer reliability. There was an average positive correlation between the DSDT and the total score on the AKPS-DV (r_s = 0.31, p = 0.030).

CONCLUSION

The DSDT measuring the MPFFA is reliable and valid in patients with PFP.

Differences and mechanisms underpinning a change in the knee flexion moment while running in stability and neutral footwear among young females

Background

Higher peak external knee flexion moments (KFM) during running has been observed in healthy people wearing athletic footwear compared to barefoot, which may increase risk of knee pathologies such as patellofemoral pain. Currently, no studies have examined whether stability and neutral style athletic shoes influence the peak KFM differently, or explored the underlying biomechanical mechanisms by which footwear alters peak KFM in young females.

Methods

Lower limb biomechanics of sixty girls aged between 10 and 25 years old were collected while running in footwear (both stability and neutral) and barefoot. The external peak KFM, sagittal plane kinematics, sagittal plane knee ground reaction force (GRF) lever arm and sagittal plane resultant GRF magnitude were analysed by repeated measures Analysis of Variance. Linear mixed models were fit to identify predictors of a change in peak KFM, and to determine if the effects of these predictors differed between footwear conditions.

Results

The peak KFM was higher wearing both shoe styles compared to barefoot (p < 0.001), while no between-shoe differences were found (p > 0.05). Both shoes also increased kinematic variables at the hip, knee, and ankle (p < 0.05). When all these variables were entered into the mixed model, only a change in the knee-GRF lever arm was predictive of a change in peak KFM wearing shoes compared to barefoot (p < 0.001).

Conclusion

These findings provide evidence that stability and neutral shoes increase peak KFM compared to barefoot, which is associated with a change in the knee-GRF lever arm rather than a change in lower limb kinematics. Future studies may consider manipulating footwear characteristics to reduce the knee-GRF lever arm in an effort to reduce peak KFM and the potential risk of patellofemoral pain.

Electronic supplementary material

The online version of this article (10.1186/s13047-018-0307-9) contains supplementary material, which is available to authorized users.

Identification of knee gait waveform pattern alterations in individuals with patellofemoral pain using fast Fourier transform

Patellofemoral pain (PFP) is one of the most common overuse injuries of the knee. Previous research has found that individuals with PFP exhibit differences in peak hip kinematics; however, differences in peak knee kinematics, where the pain originates, are difficult to elucidate. To better understand the mechanism behind PFP, we sought to characterize differences in knee gait kinematic waveform patterns in individuals with PFP compared to healthy individuals using fast Fourier transform (FFT). Sixteen control and sixteen individuals with PFP participated in a fast walk protocol. FFT was used to decompose the sagittal, frontal and transverse plane knee gait waveforms into sinusoidal signals. A two-way ANOVA and Bonferroni post hoc analysis compared group, limb and interaction effects on sagittal, frontal and transverse amplitude, frequency and phase components between control and PFP individuals gait waveforms. Differences in frequency and phase values were found in the sagittal and frontal plane knee waveforms between the control and PFP groups. The signal-to-noise ratio also reported significant differences between the PFP and control limbs in the sagittal (p<0.01) and frontal planes (p = 0.04). The findings indicate that differences in gait patterns in the individuals with PFP were not the result of amplitude differences, but differences attributed to temporal changes in gait patterns detected by the frequency and phase metrics. These changes suggest that individuals with PFP adopted a more deliberate, stiffer gait and exhibit altered joint coordination. And the FFT technique could serve as a fast, quantifiable tool for clinicians to detect PFP.

THERABAND® CLX gold reduces knee-width index and range of motion during overhead, barbell squatting

This study examined the influence of the Theraband^TM CLX gold band on lower-limb muscle activity and kinematics during an overhead barbell squat. Participants performed two sets (band and no-band) of 12 repetitions of overhead barbell squats at 25% bodyweight. Three-dimensional kinematics were measured using motion capture with rigid bodies placed bilaterally on the foot, shank, thigh and thorax. Electromyography was collected from seven, bilateral muscles of the lower-limb and was unchanged for all muscles between conditions. Medial knee collapse was calculated using a knee-width index (KWI) ratio of the distance between the lateral epicondyles of the femur and the lateral malleoli. Average KWI was smaller during the band condition for the concentric (No band: 0.99 ± 0.05, Band: 0.97 ± 0.06, p < 0.05) and eccentric phases (No band: 1.00 ± 0.06, Band: 0.97 ± 0.05, p < 0.05). KWI was significantly smaller with the use of the Theraband^TM CLX. As the gold band is the strongest of the CLX offerings, any benefit of increased proprioception may have been lost due to the high resistance of the band. Further research examining the dose-response of elastic band resistance to knee alignment may be needed to inform proper exercise prescription.

Relationship between patellar mobility and patellofemoral joint cartilage degeneration after anterior cruciate ligament reconstruction

Patellofemoral cartilage degeneration is a potential complication of anterior cruciate ligament reconstruction (ACLR) surgery. Hypomobility of the patella in the coronal plane is often observed after ACLR. Few studies, however, have examined the relationship between cartilage degeneration in the patellofemoral joint and mobility after ACLR. The present study investigated 1) the coronal mobility of the patella after ACLR, 2) the relationship between patellar mobility and cartilage degeneration of the patellofemoral joint, and 3) the relationship between patellar mobility and knee joint function after ACLR. Forty patients who underwent medial hamstring-based ACLR participated in the study. Lateral and medial patellar displacements were assessed with a modified patellofemoral arthrometer, and the absolute values of the displacements were normalized to patient height. The International Cartilage Repair Society (ICRS) cartilage injury classification of the patellar and femoral (trochlear) surfaces, and the Lysholm Knee Scoring Scale were used to evaluate knee function. Lateral and medial patellar displacements were reduced compared with the non-operated knee at the second-look arthroscopy and bone staple extraction operation (second operation; 24.4 ± 7.9 months after ACLR, P<0.01). The ICRS grades of the patellofemoral joint (patella and trochlea) were significantly worse than those pre-ACLR. Neither lateral nor medial patellar mobility, however, were significantly correlated with the ICRS grade or the Lysholm score. Although patellar mobility at approximately 2 years after ACLR was decreased compared to the non-operated knee, small displacement of the patella was not related to cartilage degeneration or knee joint function at the time of the second operation.

Correlation between the Q angle and the isokinetic knee strength and muscle activity

OBJECTIVES

The aim of this study was to investigate the correlation between the Q angle and the isokinetic knee strength and muscle activity.

PATIENTS AND METHODS

Between March 2016 and April 2016, a total of 50 healthy and right-leg dominant men (mean age 22.3±2.3 years; range, 18 to 27 years) with a Q angle between 5° and 20° and active in sports were included. An isokinetic strength test of the knee joint extensor and flexor muscles at angular velocities of 60, 120, 180, 240, and 300°·s-1 was tested who had a Q angle of 5 to 20° and were active in sports. Surface electromyography (sEMG) was used to determine these muscles' activity levels.

RESULTS

Negative correlations were between the Q angle and the average peak torque (APT) in extension (E) and flexion (F), the average power (APE,F) at all angles, the joint angle at the PT (JAPTE) at 240, 180, 120 and 60°·s-1; JAPTF at 300, 240 and 180°·s-1; and the time to PT (TPTF) at 180°·s-1. There was a positive correlation between the Q angle and TPTE (at 60°·s-1). No significant relationship between the Q angle and the level of EMG activity at any angular velocity of the muscles, as well as the VM:VL EMG activity ratio was found.

CONCLUSION

A higher Q angle is associated with decreased isokinetic knee strength, power output, and torque angles. It is thought that possible high Q angle-related knee joint disorders and sports injuries can be avoided by including proper quadriceps strength exercises in exercise prescriptions to be prepared.

Are tibial angles measured with inertial sensors useful surrogates for frontal plane projection angles measured using 2-dimensional video analysis during single leg squat tasks? A reliability and agreement study in elite football (soccer) players

During single leg squats (SLS), tibial angle (TA) quantification using inertial measurement units (IMU) may offer a practical alternative to frontal plane projection angle (FPPA) measurement using 2-dimensional (2D) video analysis. This study determined: (i) the reliability of IMUs and 2D video analysis for TA measurement, and 2D video analysis for FPPA measurement; (ii) the agreement between IMU TA and both 2D video TA and FPPA measurements during single leg squats in elite footballers. 18 players were tested on consecutive days. Absolute TA (ATA) and relative TA (RTA) were measured with IMUs. ATA and FPPA were measured concurrently using 2D video analysis. Within-session reliability for all measurements varied across days (intraclass correlation coefficient (ICC) range = 0.27-0.83, standard error of measurement (SEM) range = 2.12-6.23°, minimal detectable change (MDC) range = 5.87-17.26°). Between-sessions, ATA reliability was good for both systems (ICCs = 0.70-0.74, SEMs = 1.64-7.53°, MDCs = 4.55-7.01°), while IMU RTA and 2D FPPA reliability ranged from poor to good (ICCs = 0.39-0.72, SEMs = 2.60-5.99°, MDCs = 7.20-16.61°). All limits of agreement exceeded a 5° acceptability threshold. Both systems were reliable for between-session ATA, although agreement was poor. IMU RTA and 2D video FPPA reliability was variable. For SLS assessment, IMU derived TAs are not useful surrogates for 2D video FPPA measures in this population.

Lower-Extremity Muscle Activity, Kinematics, and Dynamic Postural Control in Individuals With Patellofemoral Pain

CONTEXT

Altered lower-extremity muscle activity has been associated with lower-extremity kinematics in individuals with patellofemoral pain (PFP). However, few studies have examined these relationships, and the results are inconsistent.

OBJECTIVE

To compare the lower-extremity muscle activity, kinematics, pain level, and reach distance during the anterior reach of the star excursion balance test (SEBT) between participants with PFP and healthy individuals (control [CON] group).

DESIGN

Case control.

SETTING

Research laboratory.

PARTICIPANTS

Twenty-eight (PFP = 14 and CON = 14) participants volunteered.

INTERVENTION

Each participant performed 3 maximal voluntary isometric contractions of the gluteus maximus, gluteus medius (GMED), adductor longus (AL), and vastus medialis, and 5 anterior reaches of the SEBT.

MAIN OUTCOME MEASURES

Three-dimensional joint kinematics of the hip and knee at the time of touchdown of the SEBT and integrated electromyography of each muscle were recorded during the descent phase of the SEBT. Coactivation ratios between the GMED and AL were calculated (GMED/AL). Pain level was assessed at the baseline and during performance of the SEBT, using a visual analog scale.

RESULTS

Participants with PFP demonstrated decreased GMED/AL coactivation ratio (P = .01) and shorter reach distance (P = .01) during anterior reach of the SEBT compared with the CON group. Participants with PFP demonstrated higher pain levels at baseline (P = .03) and during test performance (P < .001) compared with the CON group and increased pain level during the test performance compared with the baseline (P < .001). No other significant differences were observed.

CONCLUSIONS

There were alterations in muscle activity during SEBT performance, suggesting that overactivity of AL relative to GMED is a unique neural recruitment pattern in those with PFP. However, hip and knee joint kinematics did not seem to contribute to deficits in the anterior reach distance, suggesting a need for continued assessment of these deficiencies.

National Athletic Trainers' Association Position Statement: Management of Individuals With Patellofemoral Pain

OBJECTIVE: 

To present recommendations for athletic trainers and other health care providers regarding the identification of risk factors for and management of individuals with patellofemoral pain (PFP).

BACKGROUND: 

Patellofemoral pain is one of the most common knee diagnoses; however, this condition continues to be one of the most challenging to manage. Recent evidence has suggested that certain risk factors may contribute to the development of PFP. Early identification of risk factors may allow clinicians to develop and implement programs aimed at reducing the incidence of this condition. To date, clinicians have used various treatment strategies that have not necessarily benefitted all patients. Suboptimal outcomes may reflect the need to integrate clinical practice with scientific evidence to facilitate clinical decision making.

RECOMMENDATIONS: 

The recommendations are based on the best available evidence. They are intended to give athletic trainers and other health care professionals a framework for identifying risk factors for and managing patients with PFP.

Effects of Corrective Training on Drop Landing Ground Reaction Force Characteristics and Lower Limb Kinematics in Older Adults With Genu Valgus: A Randomized Controlled Trial

The aim of this study was to identify the effects of a corrective exercise program on landing ground reaction force characteristics and lower limb kinematics in older adults with genu valgus. A total of 26 older male adults with genu valgus were randomized into two groups. An experimental group conducted a 14-week corrective exercise program, whereas a control group did not perform any exercise. The experimental group displayed lower peak vertical, peak anterior and posterior, and peak medial ground reaction force components during the posttest compared with the pretest. The vertical loading rate, impulses, and free moment amplitudes were not statistically different between groups. In the experimental group, the peak knee abduction during the posttest was significantly smaller and the peak hip flexion angle was significantly greater than during the pretest. The authors suggest that this corrective exercise program may be a suitable intervention to improve landing ground reaction forces and lower limb kinematics in older male adults with genu valgus.

Two-dimensional frontal plane projection angle can identify subgroups of patellofemoral pain patients who demonstrate dynamic knee valgus

BACKGROUND

Identifying individuals with patellofemoral pain who demonstrate similar modifiable factors including dynamic knee valgus may be useful in establishing subgroups of patients that can undergo individualised management strategies. However, a lack of objective assessment criteria means that the findings are of limited value to clinicians aiming to distinguish between patients with and without altered frontal plane knee kinematics. Therefore, the aim of the study was to investigate dynamic knee valgus in individuals with and without patellofemoral pain by determining frontal plane knee alignment during functional activity.

METHODS

Thirty recreationally active individuals with patellofemoral pain and 30 non-injured individuals had frontal plane knee alignment assessed via two-dimensional analysis of the frontal plane projection angle during single limb stance and single limb squats to 60° of knee flexion.

FINDINGS

Individuals with patellofemoral pain demonstrated excessive frontal plane knee alignment (P = .003; ES = 0.68) compared to uninjured participants during single limb squats. In addition, assessing frontal plane knee alignment using two-dimensional analysis had fair specificity and sensitivity of discriminating patellofemoral pain injury.

INTERPRETATION

Clinical quantification of two-dimensional frontal plane knee alignment may be utilised to subgroup patients with patellofemoral pain that display dynamic knee valgus during single limb squats. Furthermore, this may be a useful clinical tool to determine individuals that may be at risk of developing pain in the future.

Exercise for posterior tibial tendon dysfunction: a systematic review of randomised clinical trials and clinical guidelines

Objective

To systematically review all randomised clinical trials to determine the efficacy of local strengthening exercises compared with other forms of conservative management for adults with posterior tibial tendon dysfunction.

Design

Systematic review.

Data sources

Four electronic databases (Cumulative Index to Nursing and Allied Health Literature, Cochrane, Embase and PubMed) were searched up to June 2018.

Eligibility criteria for selecting studies

The study included randomised clinical trials investigating individuals with posterior tibial tendon dysfunction where local strengthening was compared with other forms of conservative management with respect to pain, function and/or physical impairment outcome measures. Standardised mean differences (SMDs) were used to compare change scores between groups and descriptors of exercise prescription assessed according to the Template for Intervention Description and Replication and the Toigo and Boutellier recommendations.

Results

3 studies (n=93) were eligible for inclusion in the review. Varying strengthening exercises were compared with stretching and foot orthoses (n=2) or no intervention (n=1). Moderate effects (SMD 0.6-1.2) were found for reducing pain and disability with eccentric strengthening in conjunction with stretching and orthoses compared with concentric exercises, stretching and orthoses combined, and stretching and orthoses alone. Evaluation of exercise prescription parameters demonstrated minimal reporting, with the only consistent parameters being the number of sets and repetitions of the exercises, and the duration of the experimental period.

Conclusion

This review demonstrates the paucity of high-quality research for the conservative management of posterior tibial tendon dysfunction, and highlights the lack of exercise prescription parameters reported in clinical trials.

Trial registration number

CRD42017076156.

Vastus lateralis and vastus medialis produce distinct mediolateral forces on the patella but similar forces on the tibia in the rat

Improper activation of the quadriceps muscles vastus medialis (VM) and vastus lateralis (VL) has been implicated in the development of patellofemoral pain (PFP). This explanation of PFP assumes that VM and VL produce opposing mediolateral forces on the patella. Although studies have provided evidence for opposing actions of VM and VL on the patella, other studies have suggested that their actions might be similar. In this study, we took advantage of the experimental accessibility of the rat to directly measure the forces on the patella produced by VM and VL. We found that VM and VL produce opposing mediolateral forces on the patella when the patella was lifted away from the femur. These distinct mediolateral forces were not transmitted to the tibia, however: forces measured at the distal tibia were very similar for VM and VL. Further, when the patella was placed within the trochlear groove, the forces on the patella produced by VM and VL were very similar to one another. These results suggest that mediolateral forces produced by VM and VL are balanced by reaction forces from the trochlear groove and so are not transmitted to the tibia. These results provide a rich characterization of the mechanical actions of VM and VL and have implications about the potential role of these muscles in PFP and their neural control during behavior.

A cadaveric model to evaluate the effect of unloading the medial quadriceps on patellar tracking and patellofemoral joint pressure and stability

BACKGROUND

Vastus Medialis Muscles (VMM) damage has been widely identified following patellar dislocation. Rehabilitation programmes have been suggested to strengthen the VMM and reduce clinical symptoms of pain and instability. This controlled laboratory study investigated the hypothesis that reduced Vastus Medialis Obliquus (VMO) and Vastus Medialis Longus (VML) muscle tension would alter patellar tracking, stability and PFJ contact pressures.

METHODS

Nine fresh-frozen dissected cadaveric knees were mounted in a rig with the quadriceps and iliotibial band loaded to 205 N. An optical tracking system measured joint kinematics and pressure sensitive film between the patella and trochlea measured PFJ contact pressures. Measurements were repeated for three conditions: 1. With all quadriceps heads and iliotibial band (ITB) loaded; 2. as 1, but with the VMO muscle unloaded and 3. as 1, but with the VMO and VML unloaded. Measurements were also repeated for the three conditions with a 10 N lateral displacement force applied to the patella.

RESULTS

Reduction of VMM tension resulted in significant increases in lateral patellar tilt (2.8°) and translation (4 mm), with elevated lateral and reduced medial joint contact pressures from 0.48 to 0.14 MPa, and reduced patellar stability (all p < 0.05).

CONCLUSIONS

These findings provide basic scientific rationale to support the role of quadriceps strengthening to resist patellar lateral maltracking and rebalance the articular contact pressure away from the lateral facet in patients with normal patellofemoral joint anatomy.

Association of altered frontal plane kinematics and physical activity levels in females with patellofemoral pain

BACKGROUND

Females with patellofemoral pain (PFP) present with altered frontal plane kinematics, decreased physical activity, and elevated psychological features. However, the relationship between these factors has not been evaluated.

RESEARCH QUESTION

Does a relationship exist between frontal plane kinematics, physical activity levels, and fear avoidance beliefs in females with PFP.

METHODS

16 females with PFP (Age = 23.2 ± 4.9years; Height = 166.1 ± 5.9 cm; Mass = 66.3 ± 13.5 kg) completed a 3-D biomechanical assessment during a single leg squat, step-down, and jogging task. Physical activity was collected with an activity monitor over 2-weeks and the Fear Avoidance Belief Questionnaire physical activity subscale was used to assess fear avoidance beliefs. Frontal plane kinematics were correlated with physical activity and fear avoidance, with significant variables included in a multiple regression.

RESULTS

Significant correlations were identified between physical activity and single leg squat hip adduction (r=-0.626, p = 0.01), step-down knee abduction (r=-0.783, p < 0.001) and jogging hip adduction (r=-0.639, p = 0.008). Step-down knee abduction predicted activity level and accounted for 61% of the total variance. Correlations between fear avoidance belief and single leg squat hip adduction (r = 0.477, p = 0.049), step-down knee abduction (r = 0.644, p = 0.007), jogging knee abduction (r = 0.558, p = 0.025), and jogging hip adduction (r = 0.557, p = 0.025) were also identified. Knee abduction during the step-down and single leg squat hip adduction accounted for 37.5% of the variance in the Fear Avoidance Belief Questionnaire.

SIGNIFICANCE

Altered frontal plane kinematics during step-down and jogging provide insight for clinicians to identify females with patellofemoral pain that may be less physically active, while step-down and squatting kinematics related to fear avoidance beliefs. While these relationships were found, it is essential to identify the underlying mechanism for this activity modification so clinicians and researchers can evaluate successful interventions.

Age-Dependent Patellofemoral Pain: Hip and Knee Risk Landing Profiles in Prepubescent and Postpubescent Female Athletes

BACKGROUND

Female athletes are at an increased risk of developing patellofemoral pain (PFP) relative to male athletes. The unique effects of maturation may compound that risk. Hypothesis/Purpose: The purpose was to evaluate the neuromuscular control mechanisms that are adaptive to pubertal maturation and determine their relative contribution to PFP development. It was hypothesized that aberrant landing mechanics (reduced sagittal-plane and increased frontal- and transverse-plane kinematics and kinetics) would be associated with an increased risk for PFP.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

There were 506 high school female athletes who completed a detailed medical history, the Anterior Knee Pain Scale, and a knee examination for the diagnosis of PFP and attended follow-up appointments. Athletes performed a drop vertical jump task instrumented with force plates, and biomechanical measures generated from standard 3-dimensional biomechanical analyses were used to classify participants into high- or low-risk knee and hip landing profiles for the development of PFP. The biomechanical measures used in the knee landing profile included sagittal-plane knee range of motion, peak knee abduction angle, peak knee abduction moment, and peak-to-peak transverse-plane knee moment. The biomechanical measures used in the hip landing profile included sagittal-plane hip range of motion, peak hip extensor moment, peak abductor moment, and peak hip rotator moment. Testing was conducted at sport-specific preseason appointments over the course of 2 years, and changes in pubertal status, landing profile, and PFP development were documented.

RESULTS

Female athletes with high-risk hip landing profiles experienced increased hip flexion and decreased abductor, rotator, and extensor moments. Participants with high-risk hip landing profiles who transitioned to postpubertal status at follow-up had higher odds (odds ratio, 2.1 [95% CI, 1.1-4.0]; P = .02) of moving to a low-risk hip landing profile compared with those who had not reached postpubertal status at follow-up. Participants with high-risk knee landing profiles experienced decreased knee flexion and increased knee abduction, external abductor, and external rotator moments. Pubertal maturation was not associated with a change in the high-risk knee landing profile at follow-up.

CONCLUSION

The progression from prepubertal to postpubertal status may have a protective effect on high-risk hip mechanics but no similar adaptations in high-risk knee mechanics during maturation. These data indicate that before puberty, maladaptive hip mechanics may contribute to PFP, while aberrant knee mechanics associated with PFP are sustained throughout the maturational process in young female athletes.

Descending stairs: Good or bad task to discriminate women with patellofemoral pain?

BACKGROUND

There is no consensus on kinematics alterations during descending stairs in females with patellofemoral pain (PFP). In addition, there are no studies that have evaluated the three dimensional kinematics of the trunk, pelvis, hip, knee, and ankle using a multi-segmental model of the foot simultaneously during this task in patients with PFP and evaluated the subphases of stair descent. The objectives of this study were to compare the three dimensional kinematics of the trunk, pelvis, and lower limbs during different subphases of stair descent and identify the discriminatory capacity of the kinematic variables among women with PFP and healthy women.

METHODS

In this cross-sectional study, thirty-four women with PFP and thirty-four pain free women between 18 and 35 years-old were submitted to three-dimensional kinematic evaluation during stair descent.

RESULTS

It was observed that kinematic differences between the groups occurred in the first double support phase of the stair descent, with the variables of internal rotation of the hindfoot in relation to the tibia in the initial contact (2.1°; sensitivity = 68.6%, specificity = 61.8%) and contralateral pelvic drop in load response (1.3°, sensitivity = 65.7%, specificity = 63.7%) presenting the best ability to discriminate women with and without PFP.

CONCLUSION

Our results suggest that kinematic changes during stair descent should be used with caution during the evaluation and decision-making process in women with PFP.

Lower Extremity Strength and Range of Motion in High School Cross-Country Runners

Cross-country running is becoming an increasingly popular sport, with a significant participation noted at the high school level. The aim of this study was to compare gender and bilateral hip extension range of motion and hip and knee extension strength of high school cross-country runners. 31 participants volunteered from a local high school cross-country team (16 males and 15 females). The modified Thomas test was utilized to measure hip extension range of motion bilaterally using a digital inclinometer. In order to measure hip and knee isometric strengths, an isokinetic dynamometer was employed. A mixed model approach revealed a statistically significant difference in peak hip extension strength between genders but not the side. Male athletes demonstrated a 29.2 Nm/kg (P < 0.05) greater force production than females during isometric hip extension strength testing. There were no significant differences in peak knee extension isometric strength, hip extension range of motion, and the ratio of peak hip and knee strength between genders and the dominant and nondominant leg. Female cross-country runners should focus on increasing hip extension strength to help maintain hip stability during running. This may be beneficial in decreasing the chances of experiencing patellofemoral pain in long-distance runners.

Runners With Patellofemoral Pain Exhibit Greater Peak Patella Cartilage Stress Compared With Pain-Free Runners

The primary purpose of this study is to determine whether recreational runners with patellofemoral pain (PFP) exhibit greater peak patella cartilage stress compared with pain-free runners. A secondary purpose was to determine the kinematic and/or kinetic predictors of peak patella cartilage stress during running. A total of 22 female recreational runners (12 with PFP and 10 pain-free controls) participated in this study. Patella cartilage stress profiles were quantified using subject-specific finite element models simulating the maximum knee flexion angle during the stance phase of running. Input parameters to the finite element model included subject-specific patellofemoral joint geometry, quadriceps muscle forces, and lower-extremity kinematics in the frontal and transverse planes. Tibiofemoral joint kinematics and kinetics were quantified to determine the best predictor of stress using stepwise regression analysis. Compared with the pain-free runners, those with PFP exhibited greater peak hydrostatic pressure (PFP vs control: 21.2 [5.6] MPa vs 16.5 [4.6] MPa) and maximum shear stress (PFP vs control: 11.3 [4.6] MPa vs 8.7 [2.3] MPa). Knee external rotation was the best predictor of peak hydrostatic pressure and peak maximum shear stress (38% and 25% of variances, respectively), followed by the knee extensor moment (21% and 25% of variances, respectively). Runners with PFP exhibit greater peak patella cartilage stress during running compared with pain-free individuals. The combination of knee external rotation and a high knee extensor moment best predicted the elevated peak stress during running.

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.