Effects of Lateral and Medial Wedged Insoles on Knee and Ankle Internal Joint Moments During Walking in Healthy Men.

BACKGROUND: Wedged insoles have been used to treat knee pathologies and to prevent injuries. Although they have received much attention for the study of knee injury, the effects of wedges on ankle joint biomechanics are not well understood. This study sought to evaluate the immediate effects of lateral and medial wedges on knee and ankle internal joint loading and center of pressure (CoP) in men during walking. METHODS: Twenty-one healthy men walked at 1.4 m/sec in five footwear conditions: neutral, 6° (LW6) and 9° (LW9) lateral wedges, and 6° (MW6) and 9° (MW9) medial wedges. Peak internal knee abduction moments and angular impulses, internal ankle inversion moments and angular impulses, and mediolateral CoP were analyzed. Analysis of variance with post hoc analysis and Pearson correlations were performed to detect differences between conditions. RESULTS: No differences in internal knee joint loading were found between neutral and any of the wedge conditions. However, as the wedge angle increased from medial to lateral, the internal ankle inversion moment (LW6: P = .020; LW9: P < .001; MW6: P = .046; MW9: P < .001) and angular impulse (LW9: P = .012) increased, and the CoP shifted laterally (LW9: P < .001) and medially (MW9: P < .001) compared with the neutral condition. CONCLUSIONS: Neither lateral nor medial wedges were effective in altering internal knee joint loading during walking. However, the greater internal ankle inversion moment and angular impulse observed with lateral wedges could lead to a higher risk of ankle injury. Thus, caution should be taken when lateral wedges need to be prescribed.

Reduced knee adduction moments for management of knee osteoarthritis:: A three month phase I/II randomized controlled trial.

Wedged insoles are believed to be of clinical benefit to individuals with knee osteoarthritis by reducing the knee adduction moment (KAM) during gait. However, previous clinical trials have not specifically controlled for KAM reduction at baseline, thus it is unknown if reduced KAMs actually confer a clinical benefit. Forty-eight participants with medial knee osteoarthritis were randomly assigned to either a control group where no footwear intervention was given, or a wedged insole group where KAM reduction was confirmed at baseline. KAMs, Knee Injury and Osteoarthritis Outcome Score (KOOS) and Physical Activity Scale for the Elderly (PASE) scores were measured at baseline. KOOS and PASE surveys were re-administered at three months follow-up. The wedged insole group did not experience a statistically significant or clinically meaningful change in KOOS pain over three months (p=0.173). Furthermore, there was no association between change in KAM magnitude and change in KOOS pain over three months within the wedged insole group (R2=0.02, p=0.595). Improvement in KOOS pain for the wedged insole group was associated with worse baseline pain, and a change in PASE score over the three month study (R2=0.57, p=0.007). As an exploratory comparison, there was no significant difference in change in KOOS pain (p=0.49) between the insole and control group over three months. These results suggest that reduced KAMs do not appear to provide any clinical benefit compared to no intervention over a follow-up period of three months. ClinicalTrials.gov ID Number: NCT02067208.

Control conditions for footwear insole and orthotic research.

Footwear insoles/orthotics alter variables associated with musculoskeletal injury; however, their clinical effectiveness is inconclusive. One explanation for this is the possibility that control conditions may actually produce biomechanical changes that induce clinical responses. The purpose of this study was to compare insole/orthotic control conditions to identify if variables at the ground, ankle and knee that are associated with injury are altered relative to what participants would normally experience in their own shoes. Gait analysis was performed on 15 participants during walking and running while wearing (1) their own shoes, (2) #1 with a 3mm flat insole, (3) a standardized shoe, and (4) #3 with a 3mm flat insole, where external knee adduction moments, external knee adduction angular impulses, internal ankle inversion moments, and vertical ground reaction force loading rates were determined. Conditions 2-4 were expressed as percent changes relative to condition 1, and tests of proportions assessed if there were a significant number of individuals experiencing a biomechanically relevant change for each variable. Repeated-measures ANOVAs were used to identify group differences between conditions. The majority of movement-footwear-variable combinations contained a proportion of individuals experiencing biomechanically relevant changes compared to condition 1 that was significantly greater than the expected proportion of 20%. No systematic differences were found between conditions. This suggests that conditions 2-4 may alter biomechanics relative to baseline for many participants, but not in a consistent way across participants. It is recommended that participant's own footwear be used as control conditions in future trials where biomechanics are primary variables of interest.

Influence of Compression and Stiffness Apparel on Vertical Jump Performance.

Compression apparel alters both compression of the soft tissues and the hip joint stiffness of athletes. It is not known whether it is the compression elements, the stiffness elements, or some combination that increases performance. Therefore, the purpose of this study was to determine how systematically increasing upper leg compression and hip joint stiffness independently from one another affects vertical jumping performance. Ten male athletes performed countermovement vertical jumps in 8 concept apparel conditions and 1 control condition (loose fitting shorts). The 8 apparel conditions, 4 that specifically altered the amount of compression exerted on the thigh and 4 that altered the hip joint stiffness by means of elastic thermoplastic polyurethane bands, were tested on 2 separate testing sessions (one testing the compression apparel and the other testing the stiffness apparel). Maximum jump height was measured, while kinematic data of the hip, knee, and ankle joint were recorded with a high-speed camera (480 Hz). Both compression and stiffness apparel can have a positive influence on vertical jumping performance. The increase in jump height for the optimal compression was due to increased hip joint range of motion and a trend of increasing the jump time. Optimal stiffness also increased jump height and had the trend of decreasing the hip joint range of motion and hip joint angular velocity. The exact mechanisms by which apparel interventions alter performance is not clear, but it may be due to alterations to the force-length and force-velocity relationships of muscle.

Altering Knee Abduction Angular Impulse Using Wedged Insoles for Treatment of Patellofemoral Pain in Runners: A Six-Week Randomized Controlled Trial.

OBJECTIVE: Determine if a change in internal knee abduction angular impulse (KAAI) is related to pain reduction for runners with patellofemoral pain (PFP) by comparing lateral and medial wedge insole interventions, and increased KAAI and decreased KAAI groups. DESIGN: Randomized controlled clinical trial (ClinicalTrials.gov ID# NCT01332110). SETTING: Biomechanics laboratory and community. PATIENTS: Thirty-six runners with physician-diagnosed PFP enrolled in the trial, and 27 were analyzed. INTERVENTIONS: Runners with PFP were randomly assigned to either an experimental 3 mm lateral wedge or control 6 mm medial wedge group. Participants completed a biomechanical gait analysis to quantify KAAIs with their assigned insole, and then used their assigned insole for six-weeks during their regular runs. Usual pain during running was measured at baseline and at six-week follow-up using a visual analog scale. Statistical tests were performed to identify differences between wedge types, differences between biomechanical response types (i.e. increase or decrease KAAI), as well as predictors of pain reduction. MAIN OUTCOME MEASURES: Percent change in KAAI relative to neutral, and % change in pain over six weeks. RESULTS: Clinically meaningful reductions in pain (>33%) were measured for both footwear groups; however, no significant differences between footwear groups were found (p = 0.697). When participants were regrouped based on KAAI change (i.e., increase or decrease), again, no significant differences in pain reduction were noted (p = 0.146). Interestingly, when evaluating absolute change in KAAI, a significant relationship between absolute % change in KAAI and % pain reduction was observed (R2 = 0.21; p = 0.030), after adjusting for baseline pain levels. CONCLUSION: The greater the absolute % change in KAAI during running, the greater the % reduction in pain over six weeks, regardless of wedge type, and whether KAAIs increased or decreased. Lateral and medial wedge insoles were similar in effectiveness for treatment of PFP. CLINICAL RELEVANCE: Altering KAAI should be a focus of future PFP research. Lateral wedges should be studied further as an alternative therapy to medial wedges for management of PFP. TRIAL REGISTRATION: ClinicalTrials.gov NCT01332110.

Calculation of external knee adduction moments: a comparison of an inverse dynamics approach and a simplified lever-arm approach.

BACKGROUND: The external knee adduction moment (EKAM) is often studied in knee osteoarthritis research. This study compared EKAMs between two methods of calculation: a method that only requires ground reaction force and knee position data (i.e. lever-arm), and an inverse dynamics link-segment method. METHODS: Sixteen participants walked while wearing a control shoe with and without a six millimeter lateral wedge insole. Peak EKAMs between the lever-arm and inverse dynamics methods were compared for the control condition, and the %change in moment induced by the lateral wedge was compared between methods. RESULTS: When comparing EKAMs between methods, no correlation was found (r=0.24, p=0.36); peak EKAMs with the lever-arm method (26.0Nm) were significantly lower than EKAMs with the inverse dynamics method (40.2Nm, pb0.001); and Bland-Altman plots showed poor agreement between methods. When assessing the %change in moment with a lateral wedge, a moderate correlation was found (r=0.55, p=0.03) between methods; Bland-Altman plots showed moderate agreement between methods; and the lever-arm method (-6.4%) was not significantly different from the inverse dynamics method (-11.4%, p=0.09); however, the two methods produced opposite results 31% of the time. CONCLUSION: The lever-arm method cannot estimate peak EKAMs, and can only approximate the %change in moment induced by a lateral wedge; however, the error rate was 31%. Therefore, the lever-arm method is not recommended for use in its current form. CLINICAL RELEVANCE: This study may help guide the development of a fast and simple method for determining EKAMs for individuals with knee osteoarthritis.

Reduced knee joint loading with lateral and medial wedge insoles for management of knee osteoarthritis: a protocol for a randomized controlled trial.

BACKGROUND: Knee osteoarthritis (OA) progression has been linked to increased peak external knee adduction moments (KAMs). Although some trials have attempted to reduce pain and improve function in OA by reducing KAMs with a wedged footwear insole intervention, KAM reduction has not been specifically controlled for in trial designs, potentially explaining the mixed results seen in the literature. Therefore, the primary purpose of this trial is to identify the effects of reduced KAMs on knee OA pain and function. METHODS/DESIGN: Forty-six patients with radiographically confirmed diagnosis medial knee OA will be recruited for this 3 month randomized controlled trial. Recruitment will be from Alberta and surrounding areas. Eligibility criteria include being between the ages of 40 and 85 years, have knee OA primarily localized to the medial tibiofemoral compartment, based on the American College of Rheumatology diagnostic criteria and be classified as having a Kellgren-Lawrence grade of 1 to 3. Patients will visit the laboratory at baseline for testing that includes dual x-ray absorptiometry, biomechanical testing, and surveys (KOOS, PASE activity scale, UCLA activity scale, comfort visual analog scale). At baseline, patients will be randomized to either a wedged insole group to reduce KAMs, or a waitlist control group where no intervention is provided. The survey tests will be repeated at 3 months, and response to wedged insoles over 3 months will be evaluated. DISCUSSION: This study represents the first step in systematically evaluating the effects of reduced KAMs on knee OA management by using a patient-specific wedged insole prescription procedure rather than providing the same insole to all patients. The results of this trial will provide indications as to whether reduced KAMs are an effective strategy for knee OA management, and whether a personalized approach to footwear insole prescription is warranted. TRIAL REGISTRATION: NCT02067208.

The relationship between maximal hip abductor strength and resultant loading at the knee during walking.

The peak external knee adduction moment (KAM) is implicated in progression of knee osteoarthritis (OA). Recently, hip abductor weakness has also been found in patients with knee OA; however, it remains unknown as to how or if this weakness is a consequence of OA, or a predisposing factor. If it is the latter, a direct relationship between hip strength and KAM magnitude would be expected. The purpose of this study was to evaluate the relationship between hip abductor strength and KAM magnitude during walking. In fourteen adults, maximal isometric hip abductor strength was measured, and the KAM was quantified during gait. Additionally, internal hip abductor moments, vertical and medial ground-reaction-forces (GRFs), and GRF to knee joint center lever-arms were quantified during gait. The relationship between hip strength and GRFs, lever-arms and KAM were assessed using correlation. Internal hip abductor moments were compared to maximum hip strength by paired samples t-test. Correlations between hip strength and the vertical GRF (r = -0.05, p = 0.87), medial GRF (r = -0.24, p = 0.41), lever arm (r = -0.01, p = 0.97), and KAM (r = -0.24, p = 0.41) were not statistically significant. Peak internal hip abductor moments during gait (1.1 ± 0.2 Nm/kg) were significantly lower than maximal hip abductor strength (1.8 ± 0.3 Nm/kg, p < 0.001). It is concluded that hip abductor strength is not related to KAM magnitude. It seems more likely that hip abductor weakness is a consequence of OA rather than a predisposing factor.

Footwear traction and three-dimensional kinematics of level, downhill, uphill and cross-slope walking.

Outdoor activities are a popular form of recreation, with hiking being the most popular outdoor activity as well as being the most prevalent in terms of injury. Over the duration of a hike, trekkers will encounter many different sloped terrains. Not much is known about the required traction or foot-floor kinematics during locomotion on these sloped surfaces, therefore, the purpose was to determine the three-dimensional foot-floor kinematics and required traction during level, downhill, uphill and cross-slope walking. Ten participants performed level, uphill, downhill and cross-slope walking along a 19° inclined walkway. Ground reaction force data as well as 3D positions of retro reflective markers attached to the shoe were recorded using a Motion Analysis System. Peak traction coefficients and foot-floor kinematics during sloped walking were compared to level walking. When walking along different sloped surfaces, the required traction coefficients at touchdown were not different from level walking, therefore, the increased likelihood of heel slipping during hiking is potentially due to the presence of loose material (rocks, dirt) on hiking slopes, rather than the overall lack of traction. Differences in required traction were seen at takeoff, with uphill and cross-sloped walking requiring a greater amount of traction compared to level walking. Changes in sagittal plane, frontal plane and transverse plane foot-floor angles were seen while walking on the sloped surfaces. Rapid foot-floor eversion was observed during cross-slope walking which could place the hiker at risk of injury with a misstep or if there was a slight slip.

Knee abduction angular impulses during prolonged running with wedged insoles.

Wedged insoles may produce immediate effects on knee abduction angular impulses during running; however, it is currently not known whether these knee abduction angular impulse magnitudes are maintained throughout a run when fatigue sets in. If changes occur, this could affect the clinical utility of wedged insoles in treating conditions such as patellofemoral pain. Thus, the purpose of this study was to determine whether knee abduction angular impulses are altered during a prolonged run with wedged insoles. It was hypothesized that knee abduction angular impulses would be reduced following a prolonged run with wedged insoles. Nine healthy runners participated. Runners were randomly assigned to either a 6-mm medial wedge condition or a 6-mm lateral wedge condition and then ran continuously overground for 30 min. Knee abduction angular impulses were quantified at 0 and 30 min using a gait analysis procedure. After 2 days, participants returned to perform the same test but with the other wedge type. Two-way repeated-measures analysis of variance was used to evaluate main effects of wedge condition and time and interactions between wedge condition and time (α = 0.05). Paired t-tests were used for post hoc analysis (α = 0.01). No interaction effects (p = 0.958) were found, and knee abduction angular impulses were not significantly different over time (p = 0.384). Lateral wedge conditions produced lesser knee abduction angular impulses than medial conditions at 0 min (difference of 2.79 N m s, p = 0.006) and at 30 min (difference of 2.76 N m s, p < 0.001). It is concluded that significant knee abduction angular impulse changes within wedge conditions do not occur during a 30-min run. Additionally, knee abduction angular impulse differences between wedge conditions are maintained during a 30-min run.

Development and validation of a computerized visual analog scale for the measurement of pain in patients with patellofemoral pain syndrome.

OBJECTIVE: To develop a computerized visual analog scale (cVAS) system and determine if it could be used in place of the traditional 100-mm paper-based visual analog scale (pVAS) method for the measurement of pain in patients with patellofemoral pain syndrome (PFPS). DESIGN: Descriptive laboratory study. SETTING: Biomechanics laboratory. PARTICIPANTS: Thirty-six runners diagnosed with PFPS. INTERVENTIONS: A cVAS system was custom-coded for this study. Participants completed both the cVAS survey and a pVAS survey that measured usual knee pain during running, walking, prolonged sitting, stair ascent, stair descent, and squatting movements. Thus, 216 paired measurements were made in total. MAIN OUTCOME MEASURES: Pearson correlation coefficients and slopes of the line of best fit were calculated to assess the relationship between cVAS and pVAS scores, and Bland-Altman plots were constructed to determine cVAS agreement to pVAS scores. RESULTS: All cVAS measures were highly correlated to pVAS scores (all r values were >0.9), and slopes were always near 1.0. Bland-Altman plots demonstrated that there was good agreement between the 2 methods. CONCLUSIONS: The cVAS system that was developed is a valid method for measurement of pain in patients with PFPS. Further use of the cVAS for studies involving PFPS is supported.

The effects of wedged footwear on lower limb frontal plane biomechanics during running.

OBJECTIVE: Patellofemoral pain syndrome (PFPS), the most common running injury, has been associated with increased internal knee abduction angular impulses (KAAI). Wedged footwear can reduce these impulses during walking, but their effects during running are not well understood. The purpose of this study was to identify the effects of wedged footwear on KAAIs and describe the mechanism by which wedged footwear alters KAAIs during running. DESIGN: Controlled laboratory study. SETTING: Motion analysis laboratory. PARTICIPANTS: Nine healthy male subjects. INTERVENTIONS: Participants ran at a speed of 4 m/s with 7 different footwear conditions (3-, 6-, and 9-mm lateral wedges; 3-, 6-, and 9-mm medial wedges; neutral). MAIN OUTCOME MEASURES: Knee abduction angular impulses and 8 predictor variables were measured and compared by 1-way repeated measures analysis of variance (α = 0.05) with Bonferroni-adjusted 2-tailed paired t tests for post hoc analysis (α = 0.002). Correlation (α = 0.05) was used to determine the relationship between the mediolateral center of pressure to ankle joint center (COP-AJC) lever arm length and KAAIs. RESULTS: Laterally wedged conditions produced significantly lower KAAIs (P = 0.001) than medial wedge conditions. Peak knee abduction moments decreased (P = 0.001), whereas ankle inversion moments (P = 0.041) and the COP-AJC lever arms increased (P < 0.001) as wedges progressed from medial to lateral. KAAIs were negatively correlated with COP-AJC lever arm length (r = -0.50, P < 0.001). CONCLUSIONS: KAAIs are reduced with laterally wedged footwear because of lateral shifts in the center of pressure beneath the foot, which then increases ankle inversion moments and decreases peak knee abduction moments. Laterally wedged footwear may therefore offer greater relief to runners with PFPS than medially wedged footwear by reducing KAAIs.

Early heelstrike kinetics are indicative of slip potential during walking over a contaminated surface.

OBJECTIVE: The objective of this study is to examine ground kinetics early in stance while walking on a contaminated surface and assess the potential of kinetics to quantify risk of slipping. BACKGROUND: Prior studies of slipping have dismissed early ground kinetic data,and therefore no prior literature has been able to assess the viability of using these data to quantify slip potential. METHOD: A total of 11 healthy male participants volunteered to walk over a force plate that was at random times contaminated with soap.Ground kinetics were measured by the force plate (2400 Hz), and heel displacement was quantified using high-speed video cameras (240 Hz) and retro-reflective markers. RESULTS: The results indicated a significant reduction in shear force as early as 0.42 ms after heelstrike for contaminated trials, whereas for utilized coefficient of friction, a significant reduction was not seen until 11.34 ms. Heel displacements considered "safe" in the literature (< 30 mm) demonstrated proportionally different thresholds for shear force and utilized coefficient of friction. CONCLUSION: The authors suggest that shear force in early stance shows more promise in quantifying slip potential as compared to utilized coefficient of friction given that (a) significant differences are seen earlier in shear than utilized coefficient of friction and (b) the threshold for utilized coefficient of friction, over which heel displacement stabilized to a"safe" value, exceeded values for utilized coefficient of friction that have been recommended as "safe". APPLICATION: These results have wide implications for standards related to the design and testing of interventions to prevent injuries because of slipping.

Pattern classification of kinematic and kinetic running data to distinguish gender, shod/barefoot and injury groups with feature ranking.

The identification of differences between groups is often important in biomechanics. This paper presents group classification tasks using kinetic and kinematic data from a prospective running injury study. Groups composed of gender, of shod/barefoot running and of runners who developed patellofemoral pain syndrome (PFPS) during the study, and asymptotic runners were classified. The features computed from the biomechanical data were deliberately chosen to be generic. Therefore, they were suited for different biomechanical measurements and classification tasks without adaptation to the input signals. Feature ranking was applied to reveal the relevance of each feature to the classification task. Data from 80 runners were analysed for gender and shod/barefoot classification, while 12 runners were investigated in the injury classification task. Gender groups could be differentiated with 84.7%, shod/barefoot running with 98.3%, and PFPS with 100% classification rate. For the latter group, one single variable could be identified that alone allowed discrimination.

Normalization of ground reaction forces, joint moments, and free moments in human locomotion.

Authors who report ground reaction force (GRF), free moment (FM), and resultant joint moments usually normalize these variables by division normalization. Normalization parameters include body weight (BW), body weight x height (BWH), and body weight x leg length (BWL). The purpose of this study was to explore the appropriateness of division normalization, power curve normalization, and offset normalization on peak GRF, FM, and resultant joint moments. Kinematic and kinetic data were collected on 98 subjects who walked at 1.2 and 1.8 m/s and ran at 3.4 and 4.0 m/s. Linear curves were best fit to the data, and regression analyses performed to test the significance of the correlations. It was found that the relationship between peak force and BW, as well as joint moments and BW, BWH, and BWL, were not always linear. After division normalization, significant correlations were still found. Power curve and offset normalization, however, were effective at normalizing all variables; therefore, when attempting to normalize GRF and joint moments, perhaps nonlinear or offset methods should be implemented.

Footwear traction and lower extremity joint loading.

BACKGROUND: Traction is influenced by the sole architecture and playing surface, with increases in traction potentially leading to injury. The mechanism as to how or why increased traction could lead to injury remains unknown. PURPOSE: This study was undertaken to determine how shoes of different sole designs and traction influence knee and ankle joint moments. STUDY DESIGN: Controlled laboratory study. METHODS: Traction testing was performed on 2 shoes of varying sole designs (tread vs smooth) using a robotic testing machine. All testing was conducted on a 60-cm x 90-cm piece of sample track surface. Kinematic and kinetic data were then collected on 13 recreational athletes performing running V-cuts in the 2 different shoe conditions. Five trials per condition were collected with reflective markers placed on the right shank and shoe of each participant. Kinematic and kinetic data were collected using an 8-high-speed camera system and force plate. RESULTS: The coefficient of translational traction and the peak moment of rotation were both significantly higher in the tread shoe compared with the smooth shoe (1.00 vs 0.87 and 23.87 N.m vs 16.12 N.m, respectively). The high-traction shoe had significantly higher peak ankle external rotation moments (89.58 N.m vs 80.17 N.m), peak knee external rotation moments (36.23 N.m vs 32.02 N.m), peak knee adduction moments (224.0 N.m vs 186.8 N.m), and knee adduction angular impulse (2.10 Nms vs 1.83 Nms) compared with the low-traction shoe. CONCLUSION: Increased shoe traction significantly increased ankle and knee joint moments during a V-cut. Despite the significant difference in traction, no difference in performance was observed. These changes could have an effect on ankle and knee joint injury. CLINICAL RELEVANCE: Shoes with decreased traction could be used in sports to reduce the joint moments in the knee and ankle and potentially reduce injury without a loss in performance.

Knee angular impulse as a predictor of patellofemoral pain in runners.

BACKGROUND: Identification of mechanical factors associated with patellofemoral pain, the most prevalent running injury, is necessary to help in injury prevention, but unfortunately they remain elusive. HYPOTHESIS: Runners who develop patellofemoral pain have increased knee joint angular impulse in the frontal plane. STUDY DESIGN: Case control study; Level of evidence, 3. METHODS: A retrospective study compared knee abduction impulses of 20 patellofemoral pain patients with those of 20 asymptomatic patients. A second prospective study quantified knee angular impulses during the stance phase of running of 80 runners at the beginning of the summer running season. Epidemiologic data were then collected, recording the type and severity of injury of these runners during a 6-month running period. RESULTS: The patellofemoral pain patients in the retrospective study had significantly higher (P = .026) knee abduction impulses (17.0 +/- 8.5 Nms) than did the asymptomatic patients (12.5 +/- 5.5 Nms). Six patients developed patellofemoral pain during the prospective study. The prospective data showed that patients who developed patellofemoral pain had significantly higher (P = .042) knee abduction impulses (9.2 +/- 3.7 Nms) than did matched patients who remained uninjured (4.7 +/- 3.5 Nms). CONCLUSION: The data indicate that increased knee abduction impulses should be deemed risk factors that play a role in the development of patellofemoral pain in runners. CLINICAL RELEVANCE: Footwear and running style can influence knee angular impulse, and the appropriate manipulation of these variables may play a preventive role for patients who are predisposed to patellofemoral pain.