Stair descent biomechanics reflect perceived instability in people with unilateral ankle sprain history

BackgroundEfforts have been exerted to establish the correlation between objective variables and subjectively perceived ankle instability. Whether or not biomechanical parameters during stair descent can serve as potential assessment tools for perceived stability in people with unilateral ankle sprain history is unknown.MethodsTwenty-four subjects with unilateral ankle sprain history were categorized into four groups according to the severity of perceived stability during stair descent. Kinematic and kinetic parameters during stair descent were obtained with a motion analysis system. Spearman's correlation coefficient (ρ) was utilized to test the correlation between the score of perceived stability during stair descent and biomechanical variables.FindingsSubjects with increased perceived instability were likely to show increased ankle inversion (ρ = −0.46, p = .025) and increased ankle plantarflexion (ρ = 0.46, p = .025), with increased hip adduction (ρ = −0.43, p = .036), hip flexion (ρ = −0.56, p = .004), knee adduction (ρ = 0.45, p = .027), and knee flexion (ρ = −0.44, p = .031). No significant correlation was detected between kinetic variables and perceived stability.InterpretationSagittal and coronal plane motions of the ankle might require rehabilitative intervention to produce improved self-reported outcomes. Kinematic assessment during stair descent can aid in the quantification of subjective ankle instability.     

Lead limb loading during a single-step descent in persons with and without a transtibial amputation in the trailing limb

BackgroundDecreased mechanical work done by the trailing limb when descending a single-step could affect load development and increase injury risk on the leading limb. This study assessed the effect of trailing limb mechanics on the development of lead limb load during a step descent by examining individuals with unilateral transtibial amputations who are known to exhibit reduced work in the prosthetic limb.MethodsEight amputees and 10 able-bodied controls walked 5 m along the length of a raised platform, descended a single-step of 14 cm height, and continued walking. The intact limb of amputees led during descent. Kinematic and kinetic data were recorded using integrated motion capture and force platform system. Lead limb loading was assessed through vertical ground reaction force, and knee moments and joint reaction forces. Sagittal-plane joint work was calculated for the ankle, knee, and hip in both limbs.FindingsNo differences were found in lead limb loading despite differences in trail limb mechanics evidenced by amputees performing 58% less total work by the trailing (prosthetic) limb to lower the centre of mass (P = 0.004) and 111% less for propulsion (P < 0.001). Amputees descended the step significantly slower (P = 0.003) and performed significantly greater lead limb ankle work (P = 0.017). After accounting for speed differences, initial loading at the knee was significantly higher in the lead limb of amputees versus controls.InterpretationIncreasing lead limb work and reducing forward velocity may be effective compensatory strategies to limit lead limb loading during a step descent, in response to reduced trailing limb work.     

Increased knee loading in stair ambulation in patients dissatisfied with their total knee replacement

BackgroundTotal knee replacement patients have shown reductions in knee flexion range of motion, knee extensor moments, and gait speed during stair ascent and stair descent. However, it is unknown how patients dissatisfied with their total knee replacement differ from those who are satisfied during more difficult activities such as stair negotiation. Therefore, the purpose of this study was to compare knee biomechanics of patients who are dissatisfied with their joint replacement to those who are satisfied and healthy participants during stair negotiation.MethodsNine dissatisfied, fifteen satisfied patients and fifteen healthy participants participated, completing stair ascent and descent trials on an instrumented staircase. A 2 × 3 ANOVA was used to analyze biomechanical differences between groups and limbs during both activities.FindingsThe dissatisfied group showed reduced 2nd peak vertical GRF (P ≤ 0.0040) and loading-response knee extension moments (P ≤ 0.0041) in their operated limb compared to their non-operated limb and to satisfied and healthy groups during stair ascent. First peak vertical GRF (P < 0.0088) and both loading-response (P < 0.0117) and push-off abduction moments (P < 0.0028) showed reduced values in operated limbs compared to non-operated limbs for all groups. During stair descent, the dissatisfied group showed reduced loading-response and push-off knee extension moments (P ≤ 0.006) in their operated limb compared to their non-operated limb and the healthy group. The loading-response knee extension (P < 0.0379) and abduction moments (P ≤ 0.0048) were also reduced in the dissatisfied group compared to the satisfied group.InterpretationPatients who were dissatisfied showed asymmetrical loading of the knees in conjunction, which may have contributed to their dissatisfaction.     

Interface pressure in transtibial socket during ascent and descent on stairs and its effect on patient satisfaction

BackgroundTranstibial amputees encounter stairs and steps during their daily activities. The excessive pressure between residual limb/socket may reduce the walking capability of transtibial prosthetic users during ascent and descent on stairs. The purposes of the research were to evaluate the interface pressure between Dermo (shuttle lock) and Seal-In X5 (prosthetic valve) interface systems during stair ascent and descent, and to determine their satisfaction effects on users.MethodsTen amputees with unilateral transtibial amputation participated in the study. Interface pressure was recorded with F-socket transducer (9811E) during stair ascent and descent at self-selected speed. Each participant filled in a questionnaire about satisfaction and problems encountered with the use of the two interface systems.FindingsThe resultant mean peak pressure (kPa) was significantly lower for the Dermo interface system compared to that of the Seal-In X5 interface system at the anterior, posterior and medial regions during stair ascent (63.14 vs. 80.14, 63.14 vs. 90.44, 49.21 vs. 66.04, respectively) and descent (67.11 vs. 80.41, 64.12 vs. 88.24, 47.33 vs. 65.11, respectively). Significant statistical difference existed between the two interface systems in terms of satisfaction and problems encountered (P < 0.05).InterpretationThe Dermo interface system caused less pressure within the prosthetic socket compared to the Seal-In X5 interface system during stair negotiation. The qualitative survey also showed that the prosthesis users experienced fewer problems and increased satisfaction with the Dermo interface system.     

Influence of graft type on sagittal plane knee biomechanics during stair ambulation following anterior cruciate ligament reconstruction

BackgroundBoth graft type and surgical technique for anterior cruciate ligament reconstruction can affect knee biomechanics. Several studies reported the influence of graft type, but few have controlled the surgical technique and fully investigated stair ambulation. This study aimed to compare knee biomechanics during stair ambulation between patients treated with hamstring tendon graft and those treated with patellar tendon graft when anterior medial portal technique was used to drill femoral tunnel.MethodsTwo groups of patients (patellar tendon, n = 18; hamstring tendon, n = 18) at average 12 months after reconstruction surgery were recruited to ascend and descend a customized staircase in a gait lab. Joint kinematics and kinetics were calculated for both operated and contralateral intact limbs based on kinematic analysis and inverse dynamics. The influence of graft type on knee flexion angle and moment was identified using one-way mixed (graft type and limb side) analysis of variance with post-hoc paired t-test.FindingsSignificant interaction between graft and limb was found for knee flexion and range of motion. Only the hamstring tendon group had significant kinematic deficits on the operated limb than the contralateral limb during stair ascent and descent. No significant interaction was found for knee flexion moment. Both graft groups had significant deficits in peak knee flexion moment on the operated side during stair ascent and descent.InterpretationWhile the choice of graft type does not affect the restoration of knee dynamic loading, patellar tendon graft better restores knee flexion-extension kinematics during stair ambulation.     

Impact of a dynamic ankle orthosis on acute pain and function in patients with mechanical foot and ankle pain

BackgroundOver two million Americans visit the doctor each year for foot and ankle pain stemming from a degenerative condition or injury. Ankle-foot orthoses can effectively manage symptoms, but traditional designs have limitations. This study investigates the acute impact of a novel “dynamic ankle-foot orthosis” (“orthosis”) in populations with mechanical pain (from motion or weight-bearing).MethodsWith and without the brace, participants (n = 25) performed standing, over-ground level walking, treadmill level walking, stair ascent, stair descent, single leg hold, squat, and sitting. Instrumented insoles captured in-shoe vertical forces and a visual analog scale was used to assess pain levels during each activity. Subsequently, the self-perceived impact of the orthosis on the patient's symptoms and function was ranked on a scale from −10 (most worsened) to +10 (most improved).FindingsPeak in-shoe force was reduced during level and stair walking (P < 0.05). Average perceived pain was 1.2 to 1.6 points lower in the orthosis than the unbraced control for the active tasks. The majority of participants reported that the brace improved their symptoms (n = 19), while a smaller group reported that the brace did not affect their symptoms (n = 5), although average function scores were improved for both groups (+2.4 to +4.5). The group of individuals with improved symptoms included cases of osteoarthritis, tendon dysfunction, chronic pain, sprains, and nerve disorders.InterpretationThe orthosis effectively improved pain symptoms and improved the ability of impaired individuals to complete functional activities of daily living such as level walking and stair walking.     

Ground reaction forces during stair locomotion in pregnant fallers and non-fallers

Background

More than 27% of pregnant women fall. Approximately 40% of falls occur during staircase locomotion. The purpose of this study was to examine ground reaction forces in pregnant fallers, pregnant non-fallers, and non-pregnant controls to determine if pregnant fallers display alterations to ground reaction forces that increase their risk of falling on stairs.

Methods

Fifteen pregnant fallers and 14 pregnant non-fallers participated during their second and third trimesters. Forty non-pregnant women served as controls. Subjects ascended and descended a four-step staircase. A force plate in the second stair collected ground reaction forces. Ascent and descent velocities were assessed. In the statistics, group (pregnant faller, pregnant non-faller, control) and subject were independent variables. Stance time and ascent/descent velocity were analyzed with an ANOVA. Mediolateral center of pressure excursion was analyzed with an analysis of covariance. Ground reaction forces were categorized into anterioposterior, mediolateral, and vertical forces and normalized to the subject's bodyweight. A multivariate analysis of covariance was used to compare between groups and subjects for each force category, with velocity as the covariate (α = 0.05).

Findings

Pregnant fallers had an increased anterioposterior braking impulse (P < 0.01), medial impulse (P = 0.02), and minimum between vertical peaks (P = < 0.01) during ascent. During descent, pregnant fallers demonstrated a smaller anterioposterior propulsive peak and propulsive impulse (P = 0.03) and a greater minimum between vertical peaks (P < 0.01).

Interpretation

These alterations are likely related to a strategy used by pregnant fallers to increase stability during staircase locomotion.     

The immediate effects of foot orthoses on hip and knee kinematics and muscle activity during a functional step-up task in individuals with patellofemoral pain

BackgroundEvidence shows that anti-pronating foot orthoses improve patellofemoral pain, but there is a paucity of evidence concerning mechanisms. We investigated the immediate effects of prefabricated foot orthoses on (i) hip and knee kinematics; (ii) electromyography variables of vastus medialis oblique, vastus lateralis and gluteus medius during a functional step-up task, and (iii) associated clinical measures.MethodsHip muscle activity and kinematics were measured during a step-up task with and without an anti-pronating foot orthoses, in people (n = 20, 9 M, 11 F) with patellofemoral pain. Additionally, we measured knee function, foot posture index, isometric hip abductor and knee extensor strength and weight-bearing ankle dorsiflexion.FindingsReduced hip adduction (0.82°, P = 0.01), knee internal rotation (0.46°, P = 0.03), and decreased gluteus medius peak amplitude (0.9 mV, P = 0.043) were observed after ground contact in the ‘with orthoses’ condition. With the addition of orthoses, a more pronated foot posture correlated with earlier vastus medialis oblique onset (r = − 0.51, P = 0.02) whilst higher Kujala scores correlated with earlier gluteus medius onset (r = 0.52, P = 0.02).InterpretationAlthough small in magnitude, reductions in hip adduction, knee internal rotation and gluteus medius amplitude observed immediately following orthoses application during a task that commonly aggravates symptoms, offer a potential mechanism for their effectiveness in patellofemoral pain management. Given the potential for cumulative effects of weight bearing repetitions completed with a foot orthoses, for example during repeated stair ascent, the differences are likely to be clinically meaningful.     

Dynamic stability during stair negotiation after total knee arthroplasty

BackgroundThe assessment of dynamic stability is crucial for the prevention of falls in the elderly and people with functional impairments. Evidence that total knee arthroplasty improves balance in patients with severe osteoarthritis is scarce and no information exists about how the surgery affects dynamic stability during stair negotiation.MethodsThis study aims to investigate if patients before and one year after surgery are less stable compared to asymptomatic controls. Seventeen control and twenty-seven patient participants with end-stage knee osteoarthritis that were scheduled to undergo unilateral total knee arthroplasty were recruited in this study. Participants' assessment was carried out by means of marker-based optical full-body motion capture with force platforms. The extrapolated Centre of mass and the margin of stability metrics were used to examine dynamic stability during stair ascent and descent.FindingsPatient participants, during both pre-operative and post-operative assessments, were equally balanced to the asymptomatic controls during stair gait (p > .188). Additionally, the patients' overall stability did not improve significantly one year after arthroplasty surgery (p > .252).InterpretationEven if pain from arthritis and fear of falling is decreased following surgery, our results indicate that stability in stair walking in not affected by osteoarthritis and total knee arthroplasty.Clinical trial registration number: NCT02422251.     

Lean,fast and strong: Determinants of functional performance in the elderly

BackgroundThe current literature indicates that functional capacity is associated with physical performance and body composition measurements in older adults. However, it is not clear which tests can best explain the functional capacity in this population. This study aimed to investigate the physical performance and body composition determinants of functional capacity in older adults.MethodTwenty-four older adults (66.4 ± 4.7y) undertook body composition (body fat and muscle), rate of torque development (0–50 and 0–200 ms); countermovement jump (height, power and impulse); leg-press and seated-leg-curl 5-repetition maximum; and functional-performance tests (Timed-up-and-go, stair ascent and stair descent).FindingsTimed-up-and-go correlated with countermovement jump (height, R² = 0.303; power, R² = 0.198; and impulse, R² = 0.224) and 5-repetition maximum (seated-leg-curl, R² = 0.172). Stair ascent correlated with body fat (R² = 0.213), rate of torque development (0–50 ms/body fat, R² = 0.301; 0–200 ms_, R² = 0.197; 0–200 ms/body fat, R² = 0.340), countermovement jump (height, R² = 0.325; power/body fat, R² = 0.413; impulse/body fat, R² = 0.422) and 5-repetiton maximum (leg-press/body fat, R² = 0.384; seated-leg-curl/body fat, R² = 0.341). Stair descent correlated with rate of torque development (0–50 ms/body fat, R² = 0.164; 0–200 ms, R² = 0.203; 0–200 ms/body fat, R² = 0.213), countermovement jump (height, R² = 0.458; power, R² = 0.212; power/body fat, R² = 0.358; impulse, R² = 0.218; impulse/body fat, R² = 0.369) and 5-repetition maximum (leg-press/body fat, R² = -0.227; seated-leg-curl/body fat, R² = 0.209; seated-leg-curl, R² = 0.181).InterpretationHigher body fat is associated with weaker stair ascent performance. An increase in the correlation coefficient was observed for the countermovement jump, rate of torque development, and 5-repetition maximum tests when normalized by body fat compared to the absolute values. Countermovement jump height presented the highest correlation to timed-up-and-go and stair descent, while impulse/body fat for stair ascent.     

Mobile-bearing insert reduced patellar contact force at knee flexion during posterior stabilized total knee arthroplasty

BackgroundThis study aimed to compare tibial rotation and patellar contact force between mobile- and fixed-bearing total knee arthroplasty from extension to flexion by using a navigation system and patellar contact force sensor on the same patients' knees.MethodsThirty-one consecutive patients who had undergone a primary posterior stabilized total knee arthroplasty were included. Patellar contact forces on the medial and lateral sides were measured at each flexion angle, and tibial rotation was assessed during 30–90°, and 90–120° knee flexion. The patellar contact force and tibial rotation were measured twice with the mobile- and fixed-platform trial components and compared between the two groups.FindingsThe patellar contact force was significantly lower with mobile than with fixed-bearing total knee arthroplasty on the medial side at 120° flexion (P = .0138) and lateral side at 60°, 90°, and 120° flexion (P = .0346, P = .0127, and P = .0376). There were no significant differences in tibial rotation between the mobile- and fixed-bearing inserts during both 30–90° and 90–120° knee flexion.InterpretationPatellar contact force was significantly lower, especially on the lateral side in mobile than in fixed-bearing total knee arthroplasty, whereas no significant difference in tibial internal rotation was found between the two inserts. Mobile-bearing inserts might reduce the patellar contact force by the bearing rotation, rather than natural tibial rotation during posterior stabilized total knee arthroplasty.     

Biomechanical compensations of the trunk and lower extremities during stepping tasks after unilateral transtibial amputation

BackgroundLower extremity movement compensations following transtibial amputation are well-documented and are likely influenced by trunk posture and movement. However, the biomechanical compensations of the trunk and lower extremities, especially during high-demand tasks such as step ascent and descent, remain unclear.MethodsKinematic and kinetic data were collected during step ascent and descent tasks for three groups of individuals: diabetic/transtibial amputation, diabetic, and healthy. An ANCOVA was used to compare peak trunk, hip and knee joint angles and moments in the sagittal and frontal planes between groups. Paired t-tests were used to compare peak joint angles and moments between amputated and intact limbs of the diabetic/transtibial amputation group.FindingsDuring step ascent and descent, the transtibial amputation group exhibited greater trunk forward flexion and lateral flexion compared to the other two groups (P < 0.016), which resulted in greater low back moments and asymmetric loading patterns in the lower extremity joints. The diabetic group exhibited similar knee joint loading patterns compared to the amputation group (P < 0.016), during step descent.InterpretationThis study highlights the biomechanical compensations of the trunk and lower extremities in individuals with dysvascular transtibial amputation, by identifying low back, hip, and knee joint moment patterns unique to transtibial amputation during stepping tasks. In addition, the results suggest that some movement compensations may be confounded by the presence of diabetes and precede limb amputation. The increased and asymmetrical loading patterns identified may predispose individuals with transtibial amputation to the development of secondary pain conditions, such as low back pain or osteoarthritis.     

Deep hip muscle activation during squatting in femoroacetabular impingement syndrome

BackgroundDeep hip muscle retraining is a common objective of non-operative management for femoroacetabular impingement (FAI) syndrome. These muscles are considered to have an important role in hip joint stabilization, however, it is unclear whether their function is altered in the presence of hip pathology. This exploratory study aimed to investigate activation patterns of the hip muscles during two squatting tasks in individuals with and without FAI syndrome.MethodsFifteen individuals with FAI syndrome (symptoms, clinical examination and imaging) and 14 age- and sex-comparable healthy controls underwent testing. Intramuscular fine-wire and surface electrodes recorded electromyographic activity of selected deep and superficial hip muscles during the squatting tasks. Activation patterns from individual muscles were compared between-groups using a wavelet-based linear mixed effects model (P < 0.05).FindingsThere were no between-group differences for squat depth or speed during descent or ascent for either task. Participants with FAI syndrome exhibited patterns of activation that differed significantly to controls across all muscles (P < 0.05) when squatting using their preferred strategy. Unlike controls, participants with FAI syndrome exhibited a pattern of activation for obturator internus during descent that was similar in amplitude to ascent, despite the contrasting contraction type (i.e. eccentric vs concentric).InterpretationIndividuals with FAI syndrome appear to implement a protective strategy as the hip descends towards the impingement position. Future studies should examine patients prospectively to establish whether these strategies are counterproductive for pathology and warrant rehabilitation.     

Hip kinematics and kinetics in persons with and without cam femoroacetabular impingement during a deep squat task

BackgroundPrevious studies have indicated that hip and pelvis kinematics may be altered during functional tasks in persons with femoroacetabular impingement. The purpose of this study was to compare hip and pelvis kinematics and kinetics during a deep squat task between persons with cam femoroacetabular impingement and pain-free controls.MethodsFifteen persons with cam femoroacetabular impingement and 15 persons without cam femoroacetabular impingement performed a deep squat task. Peak hip flexion, abduction, and internal rotation, and mean hip extensor, adductor, and external rotator moments were quantified. Independent t-tests (α < 0.05) were used to evaluate between group differences.FindingsCompared to the control group, persons with cam femoroacetabular impingement demonstrated decreased peak hip internal rotation (15.2° (SD 9.5°) vs. 9.4° (SD 7.8°); P = 0.041) and decreased mean hip extensor moments (0.56 (SD 0.12) Nm/kg vs. 0.45 (SD 0.15) Nm/kg; P = 0.018). In addition persons in the cam femoroacetabular impingement group demonstrated decreased posterior pelvis tilt during squat descent compared to the control group, resulting in a more anteriorly tilted pelvis at the time peak hip flexion (12.5° (SD 17.1°) vs. 23.0° (SD 12.4°); P = 0.024).InterpretationThe decreased hip internal rotation observed in persons with cam femoroacetabular impingement may be the result of bony impingement. Furthermore, the decrease in posterior pelvis tilt may contribute to impingement by further approximating the femoral head–neck junction with the acetabulum. Additionally, decreased hip extensor moments suggest that diminished hip extensor muscle activity may contribute to decreased posterior pelvis tilt.     

Trunk kinetic effort during step ascent and descent in patients with transtibial amputation using angular momentum separation

BackgroundPatients with transtibial amputation adopt trunk movement compensations that alter effort and increase the risk of developing low back pain. However, the effort required to achieve high-demand tasks, such as step ascent and descent, remains unknown.MethodsKinematics were collected during bilateral step ascent and descent tasks from two groups: 1) seven patients with unilateral transtibial amputation and 2) seven healthy control subjects. Trunk kinetic effort was quantified using translational and rotational segmental moments (time rate of change of segmental angular momentum). Peak moments during the loading period were compared across limbs and across groups.FindingsDuring step ascent, patients with transtibial amputation generated larger sagittal trunk translational moments when leading with the amputated limb compared to the intact limb (P = 0.01). The amputation group also generated larger trunk rotational moments in the frontal and transverse planes when leading with either limb compared to the healthy group (P = 0.01, P < 0.01, respectively). During step descent, the amputation group generated larger trunk translational and rotational moments in all three planes when leading with the intact limb compared to the healthy group (P < 0.017).InterpretationThis investigation identifies how differing trunk movement compensations, identified using the separation of angular momentum, require higher kinetic effort during stepping tasks in patients with transtibial amputation compared to healthy individuals. Compensations that produce identified increased and asymmetric trunk segmental moments, may increase the risk of the development of low back pain in patients with amputation.     

Comparison of gluteus medius muscle activity during functional tasks in individuals with and without osteoarthritis of the hip joint

Background

Neuromuscular alterations have been reported for patients with osteoarthritis of the hip joint; however, the underlying cause associated with altered gluteus medius muscle function has not been examined. This study assessed electromyographic amplitudes of the gluteus medius muscles during function in patients with unilateral end-stage osteoarthritis of the hip joint compared to controls.

Methods

Patients with unilateral end-stage hip joint osteoarthritis (n = 13) and asymptomatic control participants (n = 17) participated. Average root-mean squared muscle amplitudes represented as a percent of maximum voluntary isometric contraction for both the involved and uninvolved limb gluteus medius muscles were analyzed during step up, step down, and gait. The association between muscle activation and impact forces during stepping tasks was assessed.

Findings

Patients with hip osteoarthritis exhibited increased gluteus medius muscle electromyographic amplitudes bilaterally during stair ascent, stair descent, and gait compared to controls, regardless of which limb they led. Involved limb muscle activity was inversely related to impact force during step down onto the ipsilateral limb.

Interpretation

Patients with hip osteoarthritis demonstrated increased gluteus medius muscle activation levels during stepping tasks and gait when compared to controls. The increased activation is most likely a compensatory response to muscle weakness. Therefore, application of strengthening exercises which target the gluteal muscles should assist in neuromuscular control and result in improved strength for patients with hip joint osteoarthritis.     

Delayed onset of quadriceps activity and altered knee joint kinematics during stair stepping in individuals with knee osteoarthritis

OBJECTIVE: To determine if the electromyographic onset of vastus lateralis and kinematic knee joint motion in individuals with knee osteoarthritis (OA) differs from that of asymptomatic persons, during the task of stair stepping. DESIGN: Cross-sectional. SETTING: University laboratory in Australia. PARTICIPANTS: Twenty-five participants with symptomatic knee OA and 33 asymptomatic controls. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Surface electromyography to determine the onset of vastus lateralis activity. Two-dimensional kinematic analysis of sagittal plane knee motion during stance phase of stair ascent and descent. RESULTS: Participants with knee OA showed delayed onset of vastus lateralis activity during stair descent (P<.05) but not ascent. Both groups displayed a similar total range of knee motion. However, during stair descent, participants with OA had less knee flexion during early stance (P<.05) than controls. CONCLUSION: Individuals with knee OA display altered quadriceps function and knee joint kinematics during stair descent. These impairments may have implications for force attenuation across the knee joint and warrant future investigation.     

CONSISTENCY OF DYNAMIC KNEE VALGUS KINEMATICS AND PAIN ACROSS FUNCTIONAL TASKS IN FEMALES WITH PATELLOFEMORAL PAIN: A CROSS-SECTIONAL STUDY

Background and Purpose:Dynamic knee valgus has been associated with patellofemoral pain (PFP) during high-level tasks, however, repeated lower-level stresses may be an alternative pain mechanism. The primary purpose of the current study was to examine the consistency of dynamic knee valgus and task-elicited pain demonstrated by females with PFP across four common functional tasks (stair ascent, stair descent, sit-to-stand, and stand-to-sit). A secondary purpose was to assess the correlation between the clinical test of single-limb squat and functional tasks.Hypothesis:Females with patellofemoral pain will demonstrate a positive relationship in magnitude of dynamic knee valgus and task-elicited pain across functional tasks. Individuals who demonstrated greater dynamic knee valgus and task-elicited pain during the clinical test of single-limb squat would demonstrate greater dynamic knee valgus and task elicited pain during stair ascent/descent and sit-to-stand/stand-to-sit tasks.Study Design:Cross-sectional study; secondary analysis of a feasibility intervention study.Methods:Twenty-three women with patellofemoral pain (age: 21.8 SD 3.7 years; BMI: 22.2 SD 2.0 kg/m²) participated. Three-dimensional kinematic data were captured during task completion. Hip and knee frontal and transverse plane angles at 45 ° of knee flexion, and pain using a visual analog scale, were assessed during single-limb squat, stair ascent/descent, and sit-to-stand. Pearson product-moment correlation coefficients were calculated to examine between-task relationships for each variable at the pre-intervention assessment.Results:Correlation coefficients between tasks ranged from 0.23-0.76 for hip frontal plane measures (7/10 significant relationships, p<0.02), 0.31-0.90 for hip transverse plane measures (7/10 significant, p<0.01), 0.87-0.95 for knee frontal plane measures (10/10 significant, p<0.01), and 0.54-0.86 for knee transverse plane measures (10/10 significant, p<0.01). Correlations spanned 0.59-0.85 for pain during tasks (10/10 significant, p<0.01).Conclusion:Females with patellofemoral pain demonstrated positive correlations in dynamic knee valgus kinematics and task-elicited pain across five tasks. Movement and pain during the clinical test of single-limb squat test also was correlated with movement and pain during the functional tasks of stair ascent/descent and sit-to-stand.Level of Evidence:Level 2b.     

Stair negotiation time in community-dwelling older adults: normative values and association with functional decline

Oh-Park M, Wang C, Verghese J. Stair negotiation time in community-dwelling older adults: normative values and association with functional decline.

Objectives

To establish reference values for stair ascent and descent times in community-dwelling, ambulatory older adults, and to examine their predictive validity for functional decline.

Design

Longitudinal cohort study. Mean follow-up time was 1.8 years (maximum, 3.2y; total, 857.9 person-years).

Setting

Community sample.

Participants

Adults 70 years and older (N=513; mean age, 80.8±5.1y) without disability or dementia.

Interventions

Not applicable.

Main Outcome Measures

Time to ascend and descend 3 steps measured at baseline. A 14-point disability scale assessed functional status at baseline and at follow-up interviews every 2 to 3 months. Functional decline was defined as an increase in the disability score by 1 point during the follow-up period.

Results

The mean±SD stair ascent and descent times for 3 steps were 2.78±1.49 and 2.83±1.61 seconds, respectively. The proportion of self-reported and objective difficulty was higher with longer stair ascent and descent times (P<.001 for trend for both stair ascent and descent). Of the 472 participants with at least 1 follow-up interview, 315 developed functional decline, with a 12-month cumulative incidence of 56.6% (95% confidence interval [CI], 52.1%–61.3%). The stair negotiation time was a significant predictor of functional decline after adjusting for covariates including gait velocity (adjusted hazard ratio [aHR] per 1-s increase: aHR=1.12 [95% CI, 1.04–1.21] for stair ascent time; aHR=1.15 [95% CI, 1.07–1.24] for stair descent time). Stair descent time was a significant predictor of functional decline among relatively high functioning older adults reporting no difficulty in stair negotiation (P=.001).

Conclusions

The stair ascent and descent times are simple, quick, and valid clinical measures for assessing the risk of functional decline in community-dwelling older adults including high-functioning individuals.