Patellofemoral Pain Syndrome Subjects Research Articles

The Role of the Ultrasonographic Knee Assessment in the Diagnosis of Patellofemoral Pain Syndrome

Background: Patellofemoral Pain Syndrome (PFPS) is a common anterior knee compartment pain etiology. It has been aimed to assess the ultrasonographic findings of the patellofemoral joint in patients with PFPS versus healthy individuals. Materials and Methods: The current case-control investigation was performed on 30 cases suffering from patellofemoral joint pain and 30 healthy individuals in Isfahan during 2020-21. All cases underwent ultrasonography to assess cartilage thickness, sulcus angle, and sulcus depth. We also measured the Q angle with a manual goniometer. Results: In healthy individuals, Q angle scores were statistically lower than in the cases group (P=0.002). The sulcus angle was remarkably higher among the patients compared to the controls. The cartilage thickness (P=0.88) and sulcus depth (P=0.543) scores had no statistical difference between the PFPS and healthy subjects (P<0.05). Conclusions: Patients with PFPS had significantly higher Q angle and lower sulcus angle than the healthy controls.

Patellofemoral Pain Syndrome Modifies the Movement of the Rearfoot, but It Does Not Alter Plantar Pressure Distribution.

Objective To compare the plantar pressure distribution and the kinematics of the rearfoot on the stance phase of subjects with or without patellofemoral pain syndrome (PFPS). Methods A total of 26 subjects with PFPS and 31 clinically healthy subjects, who were paired regarding age, height and mass, participated in the study. The plantar pressure distribution (peak pressure) was assessed in six plantar regions, as well as the kinematics of the rearfoot (maximum eversion angle, percentage of the stance phase when the maximum angle was reached, and percentage of the stance phase in which the rearfoot was in eversion). The data were analyzed by descriptive and inferential statistics, with a significance level of p ≤ 0.05. Results The pressure on the six plantar regions analyzed and the magnitude of the maximum eversion angle of the rearfoot when walking on flat surfaces did not present differences among the subjects with PFPS. However, the PFPS subjects showed, when walking, an earlier maximum eversion angle of the rearfoot than the subjects on the control group, and stayed less time with the rearfoot in eversion. Conclusion The PFPS seems to be related to modifications on the temporal pattern on the kinematics of the rearfoot.

Effect of squatting velocity on hip muscle latency in women with patellofemoral pain syndrome.

[Purpose] Neuromuscular activity has been evaluated in patellofemoral pain syndrome but movement velocity has not been considered. The aim was to determine differences in onset latency of hip and knee muscles between individuals with and without patellofemoral pain syndrome during a single leg squat, and whether any differences are dependent on movement velocity. [Subjects and Methods] Twenty-four females with patellofemoral pain syndrome and 24 healthy females participated. Onset latency of gluteus maximus, anterior and posterior gluteus medius, rectus femoris, vastus medialis, vastus lateralis and biceps femoris during a single leg squat at high and low velocity were evaluated. [Results] There was an interaction between velocity and diagnosis for posterior gluteus medius. Healthy subjects showed a later posterior gluteus medius onset latency at low velocity than high velocity; and also later than patellofemoral pain syndrome subjects at low velocity and high velocity. [Conclusion] Patellofemoral pain syndrome subjects presented an altered latency of posterior gluteus medius during a single leg squat and did not generate adaptations to velocity variation, while healthy subjects presented an earlier onset latency in response to velocity increase.

Patellofemoral Pain Syndrome and Its Effect on the Walking of Affected Subjects: Update Review

Background: Patellofemoral pain syndrome (PFPS) is complication in the knee joint that can affect the gait of affected subjects. Various studies have been done in this field. The purpose of this study is to update the review article in the effect of PFPS on gait parameters. Method: This update review includes articles published between 1990 and 2018. Our search has been done in PubMed, Google scholar, Science direct and ISI web of knowledge databases. Finally, 20 studies entered this review. Results: Subjects with PFPS show changes in walking parameters such as speed, cadence, step length and some other parameters in comparison with normal people. Conclusion: It can be concluded that some gait parameters in PFPS subjects change, and this change can be a mechanism for the reduction of patella femoral joint reaction force and pain.

"A Comparative Study of Lower Extremity Angles Inpatients with Patello Femoral Pain Syndrome (PFPS)compared to Normal Subjects During Stancephase Of Gait Cycle"

Background: PFPS commonly leads to anterior or retro patellar knee pain. The etiology of PFPS is multi-factorial and various studies have identified abnormal patellar tracking, patellar malalignment, abnormal subtalar motion, decrease in navicular angle as some of the possible factors which might lead to PFPS. This comparative study investigates the lower extremity alignment during stance phase of gait cycle in subjects with and without patellafemoral pain syndrome.Methods: In this experimental study 14 male subjects suffering from PFPS were taken into Group A and 20 asymptomatic male subjects were taken into Group B. Video analysis of both groups were done in anterior, posterior and sagittal view. Still frames of initial contact, mid stance and terminal stance phases of the gait cycle and five angles i.e. standing foot angle, navicular angle, Q angle, A angle and rear foot angle for each of three phases were measured with image tool software.Results: The mean data showed that the standing foot angle, navicular angle, Q angle, A angle were increased in asymptomatic group when compared to the PFPS group in initial contact, mid stance and terminal stance but these increase in angles were not statistically significant. However the increase in rear foot angle in terminal stance of normal subjects compared to PFPS group was statistically significant (p value= 0.047)Conclusion: There exists an association of lower extremity angles with PFPS. Significant difference exists with respect to rear foot angle between PFPS and asymptomatic individuals. Rear foot angle decreases during the terminal stance in the PFPS subjects when compared to asymptomatic subjects

Kinematic and electromyographic analysis in patients with patellofemoral pain syndrome during single leg triple hop test

Possible delays in pre-activation or deficiencies in the activity of the dynamic muscle stabilizers of the knee and hip joints are the most common causes of the patellofemoral pain syndrome (PFPS). The aim of the study was to compare kinematic variables and electromyographic activity of the vastus lateralis, biceps femoris, gluteus maximus and gluteus medius muscles between patients with PFPS and health subjects during the single leg triple hop test (SLTHT). This study included 14 female with PFPS (PFPS group) and 14 female healthy with no history of knee pain (Healthy group). Kinematic and EMG data ware collected through participants performed a single session of the SLTHT. The PFPS group exhibited a significant increase (p<0.05) in the EMG activity of the biceps femoris and vastus lateralis muscles, when compared with the healthy group in pre-activity and during the stance phase. This same result was also found for the vastus lateralis muscle (p<0.05) when analyzing the EMG activity during the eccentric phase of the stance phase. In kinematic analysis, no significant differences were found between the groups. These results indicate that biceps femoris and vastus lateralis muscles mainly during the pre-activation phase and stance phases of the SLTHT are more active in PFPS group among healthy group.

The Effect of a Patellar Bandage on the Postural Control of Individuals with Patellofemoral Pain Syndrome

A patellar bandage is often used by individuals with patellofemoral pain syndrome (PPS) to reduce pain and the additional sensorial input improves proprioception of the knee joint. The aim of this work was to assess the effect of a patellar bandage on the postural control of individuals with and without PPS. [Subjects and Methods] An analysis was performed of variables of center of pressure (CoP) as recorded by a force plate. Information about the forces and moments in three directions was used to obtain the CoP. Thirty women participated in this study: 15 with PPS and 15 without PPS. All subjects performed 3 trials in a unipodal stance with and without a patellar bandage. The force plate data were used to calculate the following variables: CoP sway area, CoP displacement frequency, and CoP mean velocity for the anteroposterior (AP) and mediolateral (ML) directions. A the linear mixed effects model was used for statistical analysis. [Results] Postural sway was significantly reduced in individuals with PPS when a patellar bandage was applied. [Conclusion] Additional sensory input from a patellar bandage increase proprioceptive feedback and this could be related to the improvement in postural control of PPS subjects.

A geometric approach to study the contact mechanisms in the patellofemoral joint of normal versus patellofemoral pain syndrome subjects

The biomechanics of the patellofemoral (PF) joint is complex in nature, and the aetiology of such manifestations of PF instability as patellofemoral pain syndrome (PFPS) is still unclear. At this point, the particular factors affecting PFPS have not yet been determined. This study has two objectives: (1) The first is to develop an alternative geometric method using a three-dimensional (3D) registration technique and linear mapping to investigate the PF joint contact stress using an indirect measure: the depth of virtual penetration (PD) of the patellar cartilage surface into the femoral cartilage surface. (2) The second is to develop 3D PF joint models using the finite element analysis (FEA) to quantify in vivo cartilage contact stress and to compare the peak contact stress location obtained from the FE models with the location of the maximum PD. Magnetic resonance images of healthy and PFPS subjects at knee flexion angles of 15°, 30° and 45° during isometric loading have been used to develop the geometric models. The results obtained from both approaches demonstrated that the subjects with PFPS show higher PD and contact stresses than the normal subjects. Maximum stress and PD increase with flexion angle, and occur on the lateral side in healthy and on the medial side in PFPS subjects. It has been concluded that the alternative geometric method is reliable in addition to being computationally efficient compared with FEA, and has the potential to assess the mechanics of PFPS with an accuracy similar to the FEA.

Frontal Plane Biomechanics in Males and Females with and without Patellofemoral Pain

The study's purpose was to compare trunk, pelvis, hip, and knee frontal plane biomechanics in males and females with and without patellofemoral pain syndrome (PFPS) during stepping. Eighty recreational athletes were equally divided into four groups: female PFPS, female controls, male PFPS, and male controls. Trunk, pelvis, hip, and knee frontal plane kinematics and activation of the gluteus medius were evaluated at 15°, 30°, 45°, and 60° of knee flexion during the downward and upward phases of the stepping task. Isometric hip abductor torque was also evaluated. Females showed increased hip adduction and knee abduction at all knee flexion angles, greater ipsilateral trunk lean and contralateral pelvic drop from 60° of knee flexion till the end of the stepping task (P = 0.027-0.001), diminished hip abductor torque (P < 0.001), and increased gluteus medius activation than males (P = 0.008-0.001). PFPS subjects presented increased knee abduction at all the angles evaluated; greater trunk, pelvis, and hip motion from 45° of knee flexion of the downward phase till the end of the maneuver; and diminished gluteus medius activation at 60° of knee flexion, compared with controls (P = 0.034-0.001). Females with PFPS showed lower hip abductor torque compared with the other groups. Females presented with altered frontal plane biomechanics that may predispose them to knee injury. PFPS subjects showed frontal plane biomechanics that could increase the lateral patellofemoral joint stress at all the angles evaluated and could increase even more from 45° of knee flexion in the downward phase until the end of the maneuver. Hip abductor strengthening and motor control training should be considered when treating females with PFPS.

No deficit in hip isometric strength or concentric endurance in young females with mild patellofemoral pain

Previous research has linked deficits in hip muscle strengt h and endurance to patellofemoral pain syndrome (PFPS). This study investigated if females with mild PFPS displayed hip isometric strength and endurance deficits compared to un injured controls. Hip abduction, internal rotation (IR) and extern al rotation (ER) were assessed using an isokinetic dynamometer in 12 females with PFPS and 12 age- and gender-matched controls. Independent t-tests were used to examine between-group differences and Pearson's Correlation Coefficient examine d the relationship between isometric strength and endurance. No significant between-group differences for IR, ER and abduct ion strength or endurance were found (all p > 0.05). Strength and endurance measurements showed significant moderate correl ations for abduction (R = 0.496, p = 0.014) and ER (R = 0.592, p = 0.002) only. The PFPS subjects had mild pain (Numerical Rating Scale: mean 1.3 cm) and disability (Anterior Knee Pain Scale: mean 81/100), which may partly explain the lack of significant between-group differences. The results suggest th at female subjects with PFPS associated with mild pain and disability do not demonstrate hip IR, ER or abduction endurance or isometric strength deficits. Further research is required to clarify t he role of factors including hip strength and endurance in the management of more severe PFPS.

Upward Squatting in Individuals With and Without Patellofemoral Pain Syndrome: A Biomechanical Study

The purpose of the study was to test the hypothesis on whether individuals with patellofemoral pain syndrome (PFPS) try to avoid knee position during upward squatting so as not to aggravate this syndrome. Also, we tested whether PFPS would generate changes in the kinetic and electromyographic (EMG) strategies used to perform this task. Eight healthy subjects and 8 subjects with PFPS, but without a history of pain for at least 30 days, took part in the experiment. They were asked to perform upward squatting with knees initially flexed at 60° (very flexed) until reaching an upright position. Angle, velocity, and acceleration (kinematic) were reconstructed for knee and ankle joints. The torques at these joints were calculated using inverse dynamics, taking into account anthropometric and inertial characteristics of each subject, including records from force data. Only activities of major muscles were recorded. The kinetic and EMG profiles were quantified during acceleration and deceleration phases of the upward squatting. Both healthy and PFPS subjects used the same kinetic and EMG strategies to perform the upward squatting, even though the magnitude of the muscle activities were decreased for the latter group. Compared to the control group, the PFPS subjects presented larger joint ankle torques and smaller knee joint torques. However, the subjects avoided keeping their knees very flexed at the initial position. Group differences in the kinetic and EMG strategies can be explained by differences in the initial position, suggesting a protective strategy used by subjects with PFPS. Therefore, for these subjects, coaches and therapists should avoid using this exercise when the knee is required to move above 40° flexion.

Kinematic and kinetic features of normal level walking in patellofemoral pain syndrome: More than a sagittal plane alteration

Patients with patellofemoral pain syndrome (PFPS) often report discomfort and pain during walking. To date, most of the studies conducted to determine gait alterations in PFPS patients have focused on sagittal plane alterations. Physiological and biomechanical factors, however, suggest that frontal and transverse plane alterations may be involved in PFPS. We therefore decided to conduct a kinematic and kinetic evaluation on all three planes in 9 PFPS subjects and 9 healthy sex- and age-matched controls. General gait characteristics were similar in patients and controls, with the exception of swing velocity, which was lower in PFPS patients. Patients also displayed an increased knee abductor and external rotator moments in loading response, and reduced knee extensor moment both in loading response and in terminal stance. We speculate that these findings may be linked both to a pain-avoiding gait pattern and to alterations in the timing of activation of different components of the quadriceps muscle, which is typical of PFPS. The relevance for clinicians is this gait pattern may represent a biomechanical risk factor for future knee osteoarthritis. We therefore recommend that treatments aimed at PFPS should also attempt to restore a correct walking pattern.

Medial contact and smaller plantar loads characterize individuals with Patellofemoral Pain Syndrome during stair descent

Objectives To investigate plantar pressure distribution in individuals with and without Patellofemoral Pain Syndrome during the support phase of stair descent. Design Observational case–control study. Participants 30 young adults with Patellofemoral Pain Syndrome and 44 matched controls. Main outcome measures Contact area, peak pressure and pressure–time integral (Novel Pedar-X system) were evaluated in six plantar areas (medial, central and lateral rearfoot; midfoot; medial and lateral forefoot) during stair descent. Results Contact area was greater in the Patellofemoral Pain Syndrome Group at medial rearfoot ( p = 0.019) and midfoot ( p < 0.001). Subjects with Patellofemoral Pain Syndrome presented smaller peak pressures ( p < 0.001). Conclusion The pattern of plantar pressure distribution during stair descent in Patellofemoral Pain Syndrome subjects was different from controls. This seems to be related to greater medial rearfoot and midfoot support. Smaller plantar loads found in Patellofemoral Pain Syndrome subjects during stair descent reveal a more cautious motor pattern in a challenging task.

Differences in patellofemoral contact mechanics associated with patellofemoral pain syndrome

Patellofemoral pain syndrome (PFPS) is a disorder of the patellofemoral (PF) joint in which abnormal tracking is often cited as a factor in pain development. PF tracking is partially dependent on passive stabilizers (ex: PF geometry). Relations amongst PFPS, PF tracking, and contact mechanics are poorly understood. In-vivo investigation of passive PF joint stabilizers including PF tracking, contact mechanics, cartilage thickness, and patellar shape will allow structural characterization of the PF joint and may highlight differences associated with PFPS. This study examined the role that passive stabilizers play in PFPS ( n=10) versus healthy subjects ( n=10). PF tracking (contact area centroid migration), cartilage thickness, shape, congruence, and contact patterns were quantified using magnetic resonance imaging during isometric loading at 15°, 30°, and 45° of knee flexion. Distinct relationships were identified between patellar shape and tracking and contact, particularly at low flexion (15–30°). Healthy subjects exhibited distinct PF tracking and contact patterns related to Type I patella shape (80%) with increasing total contact area ( p<0.001) and proximal centroid migration (15–30° p=0.012; 30–45° p<0.001) for increasing knee angles. PFPS subjects deviated from these patterns at low flexion, demonstrating higher total contact area than healthy subjects ( p=0.046 at 15°), lack of proximal centroid migration (15–30°), and more Type II (30%) and III (20%) patella shapes. This study highlights a new finding that patellar shape combined with low degrees of flexion (15–30°) may be important to consider, as this is where PFPS tracking and contact patterns deviate from healthy.

Lower Extremity Strength and Mechanics during Jumping in Women with Patellofemoral Pain

Lower extremity (LE) weakness might be associated with altered mechanics during weight bearing in subjects with patellofemoral pain syndrome (PFPS). To analyze LE strength, mechanics, and the association between these variables among women with and without PFPS during a simulated athletic task. Case control. Motion-analysis laboratory. 20 women with PFPS and 20 healthy women. Peak isometric lateral trunk-flexion, hip-abduction, hip external-rotation, knee-flexion, and knee-extension strength, as well as hip- and knee-joint excursions and angular impulses during single-leg jumps. PFPS subjects produced less hip-abduction, hip external-rotation, and trunk lateral-flexion force than the control group. The PFPS group also demonstrated greater hip-adduction excursion and hip-abduction impulses. The association between the strength measurements and LE mechanics was low. Women with PFPS demonstrate specific weaknesses and altered LE mechanics. Weakness is not, however, highly correlated with observed differences in mechanics.

Frontal plane leg alignment and muscular activity during maximum eccentric contractions in individuals with and without patellofemoral pain syndrome

Purpose The role of frontal plane tibiofemoral alignment in subjects with patellofemoral pain syndrome (PFPS) is controversial and rarely discussed in the literature. As well, little research has been done on the effects of the hamstrings muscles on PFPS. The aim of the current study was to determine whether, in individuals with PFPS, frontal plane tibiofemoral alignment or muscular activity of the index knee's crossing muscles is altered during maximum eccentric leg press exercise. Methods This cross-sectional study involved 19 patients with PFPS and 19 control subjects who were matched according to gender, age, and physical activity. During eccentric leg press action, frontal plane tibiofemoral alignment was assessed with a motion analysis system based on skin markers. Simultaneously, surface-electromyography was used to assess the activity levels of the relevant knee crossing muscles. To assess the activity under functional conditions, a leg press with a footplate having variable stability was used for barefoot testing. Results The PFPS subjects did not have significantly different frontal plane leg alignment compared to controls. On electromyography (EMG), PFPS patients had significantly lower levels of hamstring activity during eccentric leg exercise. The differences between the two groups (%; absolute differences normalized EMG) ranged from 20% (semitendinosus; stable footplate; p = 0.017) to 21% (biceps femoris; unstable footplate; p = 0.019) and 32% (semitendinosus; unstable footplate; p = 0.002). Conclusions PFPS is not linked to altered frontal plane leg alignment during eccentric leg pressing. However, PFPS is associated with eccentric under-activation of the hamstrings, which may be a compensatory strategy that maintains patellofemoral joint pressure within bearable levels.

In vivo Evaluation of Patellar Tendon Stiffness in Individuals with Patellofemoral Pain Syndrome

The objective of this study was to utilise an ultrasonic technique to assess the effect of patellofemoral pain syndrome (PFPS) on the mechanical properties of the patellar tendon. Seven subjects with PFPS and seven matched control subjects volunteered to participate in this study. Subjects were asked to perform isometric maximal voluntary contractions of the knee extensors while their knee extension torque was monitored and the displacement of the patellar tendon was recorded with an ultrasonic system. Our results showed significantly lower tendon stiffness (by ∼30%) in the PFPS subjects. Although tendon secant modulus was lower by 34% in the PFPS subjects, the difference was not statistically significant. Therefore, we conclude that the ultrasonic technique was able to detect a decrease in the structural stiffness of the patellar tendon associated with PFPS. The decrease in tendon stiffness was moderately correlated with the length of symptoms in these individuals.

Do patients with patellofemoral pain syndrome exhibit alterations in steadiness on hip and knee flexion?

1. Summary Patellofemoral pain syndrome (PFPS) can lead to knee pain and disability. The aim of this study was to investigate whether patients with PFPS have altered steadiness on hip and knee flexion (measured as standard deviation of acceleration of hip and knee flexion) during two tasks. A three dimensional motion analysis system was used to record the acceleration occurring at the hip and knee joints in patients with PFPS and healthy subjects, during single knee bends and double leg squats. No significant differences in steadiness at the hip and knee joints were found between patients and healthy subjects (p > 0.05). However, a significant correlation (p = 0.02) was found between knee steadiness and the presence of knee pain during a double leg squat in patients. This alteration in knee steadiness in PFPS patients may be a compensatory mechanism to reduce patellofemoral symptoms.

Tibia and rearfoot motion and ground reaction forces in subjects with patellofemoral pain syndrome during walking

Abnormal subtalar joint function and the consequent rotation of the tibia during walking are thought to contribute to patellofemoral pain syndrome (PFPS). The purpose of this study was to measure rearfoot and tibia motion, and the ground reaction force (GRF) during the stance phase of walking in subjects with PFPS and compare them to healthy subjects. A four camera motion analysis system with a single force plate was used to investigate rearfoot motion relative to the tibia in three planes, the tibial transverse plane rotation and the GRF during the stance phase of walking in 13 female subjects diagnosed with PFPS and 14 healthy females. Analysis showed significantly delayed peak rearfoot eversion (p=0.02), and earlier occurrence of peak dorsiflexion (p=0.02) for the PFPS group. Furthermore, significantly lower peak medial GRF (p=0.03), minimum vertical GRF trough (p=0.02) and the second vertical GRF peak (p=0.01) were found in the PFPS group. Tibial transverse rotation was not shown to be different in PFPS subjects. However, there was prolonged rearfoot eversion during the stance phase of walking. The earlier appearance of rearfoot dorsiflexion as well as the lower GRFs indicate altered propulsive function of the foot during supination.

The heel strike transient during walking in subjects with patellofemoral pain syndrome

Objectives The foot impact during the initial ground contact has been suggested to be related to pain and injury to joints. This study investigated the peak heel strike transient vertical force; its timing and the rearfoot angle relative to the tibia in the frontal plane at this time in 11 females with patellofemoral pain syndrome (PFPS) compared to 14 healthy controls. Method Subjects were examined during five walking trials across a Kistler force plate (1000 Hz). The rearfoot angle relative to the tibia was measured by attaching external markers to a tibia shell and the calcaneus using a four-camera (50 Hz) motion analysis system. Results A one-way ANOVA showed a significantly delayed appearance of the peak heel strike transient and a reduction in its magnitude in the PFPS group. PFPS subjects also exhibited a rearfoot everted posture at time of heel strike transient while the control group exhibited an inverted posture. There was no significant difference in the walking velocity between the groups. Conclusion In PFPS subjects the heel strike transient magnitude was lower and occurred significantly later which were not due to altered walking velocity. Rather, the simultaneous rearfoot everted posture may affect the heel strike transient magnitude by attenuating the impact force.