Females with patellofemoral pain have impaired impact absorption during a single-legged drop vertical jump

BackgroundFemales with patellofemoral pain (PFP) have been reported to land with altered biomechanics in some, but not all studies. Kinematic alterations previously reported may indicate, and relate to potential impairments in absorbing impact.Research questionTo compare vertical ground reaction force (vGRF) and lower limb kinematics during single-legged drop vertical jumps in females with and without PFP; and establish the relationship between vGRF and kinematics during this task.MethodsFifty-two physically active females (26 with PFP and 26 controls) participated in the present cross-sectional study. Peak of vGRF was evaluated during landing; and lower limb kinematics in the sagittal and frontal planes during deceleration (landing) and acceleration (take-off) phases were evaluated.ResultsThe PFP group had 11% greater vGRF (p < 0.01); and 13–24% lower hip, knee and ankle excursion in the sagittal plane during acceleration and deceleration phases (p ≤ 0.02) compared to the control group. No significant between group differences (p > 0.05) for hip, knee and ankle excursion in the frontal plane were identified. Greater impact was significantly correlated with reduced knee (r = –0.56), hip (r = –0.50) and ankle (r = –0.41) excursion in the sagittal plane during the acceleration phase in the control group, but not in the PFP group. No significant correlations were found between vGRF and kinematics variables during the deceleration phase in either group.SignificanceImpaired ability to absorb load and reduced lower limb movement in the sagittal plane during landing in females with PFP may provide separate treatment targets during rehabilitation.     

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

ObjectivesThe 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.MethodSubjects 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.ResultsA 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.ConclusionIn 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.     

Femoral medial deviation angle during a one-leg squat test in individuals with patellofemoral pain syndrome

ObjectivesPatients with patellofemoral pain syndrome (PFPS) often demonstrate a collapse of the knee in the medial direction during a one-leg squat. This study investigated the medial displacement magnitude of the knee during a one-leg squat test in females with PFPS.DesignThe study design was a cross sectional comparative investigation.ParticipantsThirteen healthy females and 12 females with PFPS.Main measuresParticipants were tested during a one-leg squat test using a single camera. The thigh segment alignment in the frontal plane was measured by the angle projected between the long axis of the thigh and the foot (femoral frontal angle) and the horizontal deviation (femoral deviation) of the distal thigh relative to the foot.ResultsA one-way ANOVA showed that the femoral frontal angle was significantly larger (p=0.019) for the PFPS group with no significant differences for the femoral deviation (p=0.288). Both measurements showed good trial-to-trial reliability while the femoral frontal angle showed good test–retest reliability.ConclusionThe increased femoral frontal angle magnitude during the one-leg squat demonstrates that the one-leg squat may be a useful clinical tool for the evaluation process of PFPS.     

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.     

Technical errors during medial patellofemoral ligament reconstruction could overload medial patellofemoral cartilage: a computational analysis

BACKGROUND: The influence of reconstruction of the medial patellofemoral ligament on the patellofemoral force and pressure distributions has not yet been investigated. HYPOTHESIS: Technical errors can cause tension to develop within a reconstructed medial patellofemoral ligament, which will adversely alter the normal patellofemoral force distribution by increasing the load applied to the medial cartilage. STUDY DESIGN: Controlled laboratory study. METHODS: Four computational knee models were used to simulate knee function from 30 degrees to 90 degrees of flexion with (1) an intact medial patellofemoral ligament, (2) an anatomically correct reconstruction using a double hamstring tendon autograft, (3) a 5-mm proximally malpositioned femoral attachment site, (4) a graft that is 3 mm shorter than the intact medial patellofemoral ligament, and (5) combined proximal malpositioning and a short graft. RESULTS: The results were similar for the intact and anatomically reconstructed medial patellofemoral ligament. Proximal malpositioning of the femoral attachment and using a short graft increased the graft tension during flexion, which decreased the lateral force and the lateral tilt moment acting on the patella. When a short graft was combined with proximal malpositioning, the compressive force applied to the medial cartilage at least doubled at low flexion angles, which increased the peak medial pressure by more than 50% at low flexion angles. CONCLUSION: When the medial patellofemoral ligament is reconstructed, small errors in graft length and position can dramatically increase the force and pressure applied to medial patellofemoral cartilage. CLINICAL RELEVANCE: Overloading the medial cartilage after medial patellofemoral ligament reconstruction could lead to degradation, pain, and arthrosis.     

Primary cartilage lesions and outcome among subjects with patellofemoral pain syndrome

We investigated the association between cartilage lesion and future symptoms in two groups of subjects with patellofemoral pain syndrome (PFPS). Group A consisted of 31 men (mean age 20.9 years, range 19–32) and group B of 28 consecutive patients (12 men and 16 women; mean age 27.8 years, range 15–50) operated on for PFPS. The mean follow-up time was 3.4 (range 1–7) years in group A and 4.9 (range 1–6) years in group B. At follow-up the subjects in group A with severe cartilage lesion (n=10) reported more knee symptoms as measured by their Kujala score (mean 75.1, SE 3.6 vs. 88.5, SE 2.4) than those with minor cartilage lesion (n=21) (age and follow-up time-adjusted P<0.01). In group B the subjects with severe cartilage lesion tended to report more knee symptoms according to their Kujala score (mean 71.0, SE 7.0 vs. 86.1, SE 5.9; age, sex and follow-up time-adjusted P=0.15) and VAS score (mean 51.8, SE 11.8 vs. 12.7, SE 10.4; adjusted P=0.04) than the subjects without cartilage lesion. Our study shows that among the patients with PFPS, the subjects with severe cartilage lesion of the patella or femoral trochlea reported more subjective symptoms and functional limitations at follow-up than those without or with small cartilage lesion of the patella or femoral trochlea.     

Validity and reliability of 2-dimensional trunk,hip, and knee frontal plane kinematics during single-leg squat,drop jump,and single-leg hop in females with patellofemoral pain

ObjectivesTo investigate validity and between-session reliability of frontal plane trunk, hip, and knee kinematics during three functional tasks in females with patellofemoral pain (PFP).DesignObservational.SettingResearch Laboratory.Participants20 females with PFP (22.7 ± 3.2 years, 69.9 ± 9.2 kg, 167.7 ± 9.6 cm).Main outcome measuresTrunk, hip, and knee frontal plane peak angles during the single leg squat (SLS), drop vertical jump (DVJ), and single leg hop (SLH) kinematics were evaluated using 2-dimensional (2D) and 3-dimensional (3D) motion capture. Participants returned to the lab one week later and competed a second 2D analysis of the functional tasks. Concurrent validity was assessed by evaluating relationship between 2D and 3D frontal plane kinematics with Pearson correlations. Between-session reliability was assessed by evaluating 2D kinematics with intraclass correlation coefficients by a single assessor.ResultsModerate to strong correlations (r = 0.55–0.76, p < .05) were found for frontal plane hip kinematics during all three tasks and the trunk during the SLH. Frontal plane kinematics demonstrated good to excellent test-retest reliability for each of the three tasks, (ICC _(2,1) = 0.70–0.90).Conclusion2D hip joint angles during the three functional tasks were the only valid frontal plane angles. Trunk, hip, and knee 2D frontal plane kinematics ranged between good-excellent reliability.     

Effect of patellofemoral pain on foot posture and walking kinematics

Background Excessive pronation has been implicated in patellofemoral pain (PFP) aetiology and foot orthoses are commonly prescribed for PFP patients. Pronation can be assessed using foot posture tests, however, the utility of such tests depends on their association with foot and lower-limb kinematics.Research questions Do PFP participants compared with healthy participants (1) have a more pronated foot measured with static foot tests and a kinematic multi-segmental foot model and (2) is there an association between static foot posture and foot and lower limb kinematics during walking?Methods A case-control study including 22 participants (n = 11 PFP, 5 females per group, aged 24 ± 3 (mean ± SD) years) was conducted. Foot posture measures included Arch Height Ratio, Navicular Drop (ND), and Foot Posture Index. Between-group comparisons of foot posture, segment and joint angle magnitudes, and associations between foot posture and kinematic data during gait were evaluated.Results There were no group differences in foot posture tests and mean joint angles. PFP participants had greater internal rotation of the shank and rearfoot segments, and adduction of the mid- and forefoot in the transverse plane (all p < 0.05). Greater ND was associated with increased forefoot abduction (rho=-0.68, p = 0.02) in healthy participants but no relationships were found between foot posture and kinematics in PFP participants.Significance Foot posture and kinematic data did not indicate excessive pronation in PFP participants questioning the use of orthoses to correct pronation. Larger studies are needed to determine the utility of foot posture tests as indicators of gait abnormalities in PFP.     

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

BackgroundThe efficacy of foot orthoses in reducing patellofemoral pain (PFP) is well documented; however, the mechanisms by which foot orthoses modulate pain and function are poorly understood.Research questionThis within-subject study investigated the immediate effects of foot orthoses on lower limb kinematics and angular impulses during level walking and stair ambulation in individuals with persistent PFP.MethodsForty-two participants with persistent PFP (≥3 months duration) underwent quantitative gait analysis during level walking, stair ascent and stair descent while using: (i) standard running sandals (control); and (ii) standard running sandals fitted with prefabricated foot orthoses. Hip, knee, and ankle joint kinematics and angular impulses were calculated and statistically analyzed using paired t-tests (p < 0.05).ResultsRelative to the control condition, foot orthoses use was associated with small but significant decreases in maximum ankle inversion angles during walking (mean difference [95% confidence interval]: −1.00° [−1.48 to −0.53]), stair ascent (−1.06° [−1.66 to −0.45]) and stair decent (−0.94° [−1.40 to −0.49]). Foot orthoses were also associated with decreased ankle eversion impulse during walking (−9.8Nms/kg [−12.7 to −6.8]), and decreased ankle dorsiflexion and eversion impulse during stair ascent (−67.6Nms/kg [−100.7 to −34.6] and −17.5Nms/kg [−23.6 to −11.4], respectively) and descent (−50.4Nms/kg [−77.2 to −23.6] and −11.6Nms/kg [−15.6 to −7.5], respectively). Ankle internal rotation impulse decreased when participants ascended stairs with foot orthoses (−3.3Nms/kg [−5.4 to −1.3]). Limited changes were observed at the knee and hip.SignificanceIn individuals with persistent PFP, small immediate changes in kinematics and angular impulses – primarily at the ankle – were observed when foot orthoses were worn during walking or stair ambulation. The clinical implications of these small changes, as well as the longer-term effects of foot orthoses on lower limb biomechanics, are yet to be determined.     

Patellofemoral stress during walking in persons with and without patellofemoral pain

OBJECTIVE: To determine whether individuals with patellofemoral pain (PFP) demonstrate elevated patellofemoral joint (PFJ) stress compared with pain-free controls during free and fast walking. DESIGN: A cross-sectional study utilizing an experimental and a control group. BACKGROUND: Although the cause of PFJ pathology is believed to be related to elevated joint stress (force per unit area), this hypothesis has not been adequately tested and causative mechanisms have not been clearly defined. METHODS: Ten subjects with a diagnosis of PFP and 10 subjects without pain participated. All subjects completed two phases of data collection: 1) magnetic resonance imaging (MRI) assessment to determine PFJ contact area and 2) comprehensive gait analysis during self-selected free and fast walking velocities. Data obtained from both phases were required as input variables into a biomechanical model to quantify PFJ stress. RESULTS: On the average, PFJ stress was significantly greater in subjects with PFP compared with control subjects during level walking. The observed increase in PFJ stress in the PFP group was attributed to a significant reduction in PFJ contact area, as the PFJ reaction forces were similar between groups. CONCLUSION: Our results are consistent with the hypothesis that increased patellofemoral joint stress may be a predisposing factor with respect to development of PFP. Clinically, these findings indicate that treatments designed to increase the area of contact between the patella and the femur may be beneficial in reducing the PFJ stress during functional activities. RELEVANCE: Patellofemoral pain affects about 25% of the population, yet its etiology is unknown. Knowledge of the biomechanical factors contributing to patellofemoral joint pain may improve treatment techniques and guide development of prevention strategies.     

Walking mechanics for patellofemoral pain subjects with similar self-reported pain levels can differ based upon neuromuscular activation

Patellofemoral pain (PFP) is often studied on subjects who are classified using only self-reported data. Neuromuscular activation influences movement mechanics for PFP subjects, but is not likely to be self-reported. We compared lower-extremity mechanics, during a common movement (walking), between two subdivisions of a group of PFP subjects that were similar, based on common self-report tools, but different, based on a common objective measure of quadriceps activation. Our intent was to highlight the importance of objectively considering neuromuscular activation when researching PFP movement mechanics. Thirty similar PFP research subjects (based on four common self-report tools) were divided into two subdivisions, based on different quadriceps central activation ratios (CAR): a quadriceps deficit (QD; CAR <0.95) group and a no quadriceps deficit (NQD; CAR ≥0.95) group. All subjects in both groups performed five walking trials, while common mechanical characteristics were measured: 3D ground reaction force, and 3D joint kinematics and kinetics. Functional statistics were used to compare mechanical characteristics between the groups across the entire stance phase of gait (α = 0.05). Numerous differences were found between the two groups for ground reaction force, and joint kinematics and kinetics. For example, the NQD group exhibited 5% greater vertical ground reaction force at peak impact, and 5% less vertical ground reaction force during the unloading portion of stance, relative to the QD group. The results indicate that when researching movement mechanics associated with PFP, it is important to consider objectively-measured neuromuscular activation characteristics that are not likely to be self-reported by PFP subjects.     

Motor control of the vastus medialis oblique and vastus lateralis muscles is disrupted during eccentric contractions in subjects with patellofemoral pain

BACKGROUND: Inappropriate control of the vastus medialis oblique and vastus lateralis muscles by the central nervous system can contribute to maltracking of the patella. HYPOTHESIS: The activation timing and amplitude of the vastus medialis oblique and vastus lateralis muscles will be different between normal subjects and patients with patellofemoral pain. STUDY DESIGN: Controlled laboratory study. METHODS: Subjects with patellofemoral pain and asymptomatic control subjects performed maximum voluntary knee extension contractions initiated from a flexed and an extended position. The activation timing and amplitude of the vastus lateralis and vastus medialis oblique muscles were quantified from the recorded electromyographic signals. RESULTS: There were no between-group differences in activation timing. The activation amplitude of the vastus medialis oblique and vastus lateralis muscles of the patellofemoral pain subjects was altered to the greatest extent during eccentric contractions and differed significantly from that of control subjects. CONCLUSIONS: The activation amplitudes of the vastus medialis oblique and vastus lateralis muscles of subjects with patellofemoral pain are consistent with a laterally tracking patella during eccentric contractions. Clinical Relevance: The findings suggest the clinical importance of determining whether altered activation patterns are sensitive to rehabilitation, and, if so, if subjective reports of knee joint pain and function parallel changes in the activation patterns as a result of rehabilitation.     

The accessory navicular--an important cause of medial foot pain.

The accessory navicular is a commonly occurring accessory ossicle of the foot. In most instances this is an incidental finding. In some patients, the accessory navicular is the direct cause of foot pain. We present 10 such cases. The typical clinical picture is of a young female patient who presents with chronic or acute on chronic medial foot pain centered over the medial side of the navicular. The patient is usually physically active on her feet and localizes the pain accurately. Plain radiography reveals an accessory navicular united to the navicular by a synchondrosis (Type II). The diagnosis can be confirmed by showing increased localized uptake of isotope on a technetium 99m MDP bone scan. In some cases, the accessory navicular is mistaken for a fracture. Awareness of this accessory ossicle causing such symptoms should lead to the correct diagnosis.     

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

ObjectivesTo examine the effect of knee targeted exercises compared to knee targeted exercises combined with foot targeted exercises and foot orthoses in patients with patellofemoral pain.DesignForty adult individuals (28 women, 12 men) diagnosed with patellofemoral pain and screened for excessive calcaneal eversion were randomized to knee targeted exercises or knee targeted exercises combined with foot targeted exercise and orthoses.MethodsThe knee targeted exercises were prescribed during three supervised consultations. Individuals were instructed to perform the exercises 3 times per week during a 12-week period. The foot targeted exercises were prescribed for 2 times per week for 12 weeks with one session per week being supervised by a physiotherapist. The primary outcome was the subscale “pain” in the Knee Injury and Osteoarthritis Outcome Score (KOOS) at 4 months.ResultsIndividuals randomized to knee targeted exercises combined with foot targeted exercises and foot orthoses had 8.9 points (95%CI: 0.4; 17.4) – NNT = 3 (2–16) larger improvement in KOOS pain at the primary endpoint.ConclusionsThe addition of foot targeted exercises and foot orthoses for 12 weeks was more effective than knee targeted exercises alone in individuals with patellofemoral pain. The effect was apparent after 4 months, but not significantly different after 12 months.