Dorsiflexion Stiffness Research Articles

Is there a correlation among landing stability, ankle dorsiflexion range of motion, and ankle stiffness during single-leg landing?

BackgroundEven though both landing stability and ankle dorsiflexion stiffness (ankle DR-stiffness) have been independently identified as risk factors associated with non-contact injuries, no study has specifically investigated the relationship between these two variables.MethodsTwenty male recreational athletes volunteered to participate in this study. Their ankle DF-ROM based on the weight-bearing lunge test, and landing stability based on the dynamic postural stability index (DPSI) and time to stabilization (TTS) were evaluated during a single-leg landing (SLL).ResultsThere was no statistically significant difference among ankle DF-ROM, ankle DF-stiffness, DPSI, and TTS during the SLL task (p > .05). Although a moderately positive relationship was observed between ankle DF-ROM and ankle DF-stiffness (p = .177; r = .354 [95% CI, -.153 to .653]) and a moderately negative relationship between ankle DF-ROM and TTS (p = .163; r = -.375 [95% CI, -.598 to .098]), these were not statistically significant.ConclusionThe findings indicate that ankle DF-stiffness as an independent variable, does not significantly affect landing stability based on the TTS and DPSI indexes. However, its interaction with other variables, such as sex, age, and the nature of the movement task, may influence landing stability. This study area warrants further research.

Low-Intensity Resistance Exercise Based on Myofascial Chains Alters the Lower-Limb Tension and Improves Health Status in Female Individuals With Knee Osteoarthritis.

Low-intensity resistance exercise therapy (LIRET) based on myofascial chains, applied to both affected and nonlocal joints, is an effective method for knee osteoarthritis (OA) rehabilitation. This study applied LIRET in a comparison of prevalues and postvalues of lower-limb tension in female patients with knee OA and asymptomatic participants. Twenty-four female participants with knee OA and 20 asymptomatic women took part in a 3-month long application of LIRET. Participants' ankle passive torque and ankle range of motion in the sagittal plane were assessed with an isokinetic dynamometer. The collected values were used to estimate the sagittal-plane lower-limb tension. Compared with the asymptomatic group, participants with knee OA presented decreased maximum ankle dorsiflexion (P < .001), decreased ankle plantar flexion range (P = .023), ankle resting position more inclined to dorsiflexion (P = .017), increased ankle dorsiflexion stiffness (P = .005), and lower ankle plantar flexion stiffness (P = .034). After exercise intervention, the knee OA group self-reported less knee pain (P < .001), improved physical function (P < .001), increased maximum dorsiflexion (P = .021), and increased plantar flexion range (P < .001). While plantar flexion stiffness increased (P = .037), dorsiflexion stiffness decreased (P = .015) and ankle resting position moved toward dorsiflexion (P = .002). Results suggest possible decreased anterior leg tension and possible increased posterior leg tension in patients with knee OA. The results supported that knee OA patients present imbalanced myofascial tension of lower limbs. LIRET based on myofascial chains appears to decrease pain, and stiffness, and improve physical function of patients with knee OA and change their lower-limb tension.

The Effect of Prosthetic Ankle Dorsiflexion Stiffness on Standing Balance and Gait Biomechanics in Individuals with Unilateral Transtibial Amputation.

ABSTRACT Introduction Modular prosthetic ankle components have been shown to improve walking in transtibial prosthesis users, but they may reduce stability during standing. Therefore, the stiffness of the prosthetic foot-ankle components may need to be appropriately tuned to provide a balance between walking mobility and standing balance. The present research investigates both concepts to improve our knowledge about how prosthetic ankle stiffness influences standing and walking performance. Methods Ten individuals with unilateral transtibial amputation and categorized as minimum K3-level ambulators participated. Standing balance and gait analyses at three self-selected speeds were performed at three different levels of ankle dorsiflexion stiffness (Soft, Medium, and Firm) using the College Park Venture foot (College Park Industries, Warren, MI, USA). Repeated-measures analyses of variance (ANOVAs) were performed on relevant standing balance, gait spatiotemporal, and roll-over shape (ROS) outcomes. Gait kinetic and kinematic data were analyzed using a one-dimension statistical parametric analysis. Results Ankle dorsiflexion stiffness influenced balance and gait. Overall, the Firm dorsiflexion stiffness provided a smaller body sway on standing balance, a ROS radius close to the one of able-bodied individuals, and reduced step length asymmetry while walking. Furthermore, walking speed had an influence on ROS radii, resulting in a larger radius for slow walking speeds and a smaller one for fast walking speeds. Discussion The Firm stiffness appeared to offer the most advantages for balance and gait. The radius of ROS under the Firm condition, close to the radius of able-bodied individuals, could have caused the improvement in step length symmetry by a greater progression of the center of pressure, resulting in further progression of the prosthetic side. This information, in addition to the observed walking speed effect on ROS radii, encourages us to develop studies to examine the effect of walking speed on foot performance and improve prosthetic foot design to maintain the same gait characteristics under different walking speeds. Clinical Relevance These results improve our understanding of how a specific prosthetic ankle dorsiflexion stiffness affects standing balance and gait, which supports the prosthetist's evaluation process to determine specific individual stiffness for each prosthesis user.

A novel apparatus to assess the mechanical properties of Ankle-Foot Orthoses: Stiffness analysis of the Codivilla spring

Ankle-Foot Orthoses (AFOs) are the most common devices prescribed to support the ankle and restore a quasi-normal gait pattern in drop-foot patients. AFO stiffness is possibly the main mechanical property affecting foot and ankle biomechanics. A variety of methods to evaluate this property have been reported, however no standard procedure has been validated and widely used. This study is reporting the repeatability of a novel apparatus to measure AFO stiffness in ideal frictionless conditions.The apparatus is based on a servo-hydraulic testing machine and allows to apply a displacement-controlled rotation of the AFO shell, simulating the physiological ankle dorsi/plantarflexion movement. The repeatability of the apparatus in measuring AFO stiffness in dorsiflexion and plantarflexion was assessed intra- and inter-session in a sample of standard polypropylene AFOs of different sizes (Codivilla spring).The repeatability of the apparatus in measuring the AFO stiffness was high. The Intra- and Inter-session Coefficient of Variation ranged between 0.02 ÷ 1.3 % and 1.3 ÷ 5 %, respectively. The Intra Class Correlation Coefficient ranged between 0.999 ÷ 1 intra- and 0.993 ÷ 0.997 inter-session. AFOs stiffness was observed to increase with the AFO size.The setup is easy to replicate and can be implemented with any torsion-controlled servo-hydraulic testing machine and has resulted simple to use and flexible enough to adapt to AFOs with different sizes. The frictionless contacts characterizing the apparatus make it possible to measure the ideal AFO stiffness by excluding the effect of the fixation methods to the leg and help to improve the repeatability of measurements.

Design and Initial Validation of a Multiple Degree-of-Freedom Joint for an Ankle-Foot Orthosis

Abstract This paper presents the novel design of a multi-degree-of-freedom joint (M-DOF) for an ankle-foot orthosis (AFO) that aims to improve upon the commercially available double action joint (DAJ). The M-DOF is designed to maintain the functionality of the DAJ, while increasing dorsiflexion stiffness and introducing inversion/eversion. This increase in range of motion is designed to produce greater engagement from lower limb muscles during gait. The M-DOF was experimentally validated with one able-bodied and one stroke subject. Across walking speeds, the M-DOF AFO minimally affected the able-bodied subject's joint kinematics. The stroke subject's ankle dorsiflexion/plantarflexion and knee flexion were not heavily altered when wearing the M-DOF AFO, compared to the DAJ AFO. The new DOF allowed by the M-DOF AFO increased the inversion/eversion of the ankle by ∼3 deg, without introducing any new compensations compared to their gait with the DAJ AFO.

Effects of Robot-Aided Rehabilitation on the Ankle Joint Properties and Balance Function in Stroke Survivors: A Randomized Controlled Trial.

Background: Stroke survivors with impaired control of the ankle due to stiff plantarflexors often experience abnormal posture control, which affects balance and locomotion. Forceful stretching may decrease ankle stiffness and improve balance. Recently, a robot-aided stretching device was developed to decrease ankle stiffness of patient post-stroke, however, their benefits compared to manual stretching exercises have not been done in a randomized controlled trial, and the correlations between the ankle joint biomechanical properties and balance are unclear.Objective: To compare the effects of robot-aided to manual ankle stretching training in stroke survivors with the spastic ankle on the ankle joint properties and balance function post-stroke, and further explore the correlations between the ankle stiffness and balance.Methods: Twenty inpatients post-stroke with ankle spasticity received 20 minutes of stretching training daily over two weeks. The experimental group used a robot-aided stretching device, and the control group received manual stretching. Outcome measures were evaluated before and after training. The primary outcome measure was ankle stiffness. The secondary outcome measures were passive dorsiflexion ranges of motion, dorsiflexor muscle strength, Modified Ashworth Scale (MAS), Fugl-Meyer Motor Assessment of Lower Extremity (FMA-LE), Berg Balance Scale (BBS), Modified Barthel Index (MBI), and the Pro-Kin balance test.Results: After training, two groups showed significantly within-group improvements in dorsiflexor muscle strength, FMA-LE, BBS, MBI (P < 0.05). The between-group comparison showed no significant differences in all outcome measures (P > 0.0025). The experimental group significantly improved in the stiffness and passive range of motion of dorsiflexion, MAS. In the Pro-Kin test, the experimental group improved significantly with eyes closed and open (P < 0.05), but significant improvements were found in the control group only with eyes open (P < 0.05). Dorsiflexion stiffness was positively correlated with the Pro-Kin test results with eyes open and the MAS (P < 0.05).Conclusions: The robot-aided and manual ankle stretching training provided similar significant improvements in the ankle properties and balance post-stroke. However, only the robot-aided stretching training improved spasticity and stiffness of dorsiflexion significantly. Ankle dorsiflexion stiffness was correlated with balance function.Clinical Trial Registration: www.chictr.org.cn ChiCTR2000030108.

Impact of intertibiofibular graft on the ankle joint: Medium-term radiologic and clinical assessment

HypothesisIntertibiofibular graft (ITFG) bridges tibial non-union, but blocks bimalleolar mortise opening, leading to loss of ankle dorsiflexion. The aim of the present study was to assess dorsiflexion loss and to determine whether it was associated with secondary osteoarthritis.Material and method A 2-center retrospective study included cases of tibial non-union, without initial involvement of the ankle, treated by ITFG with more than 2 years’ consolidation. Clinical, functional and radiographic parameters were analyzed. Dorsiflexion stiffness was defined as<10° flexion. Symptomatic osteoarthritis was defined by radiologic joint impingement and/or osteophytosis associated with pain>4/10 on visual analog scale (VAS) restricting walking distance to less than 1 kilometer. ResultsThirty-one cases were analyzed at a mean 7±2.8 years’ follow-up. Mean pain on VAS was 3±2.6. Mean AOFAS score was 62.3±20.5 and mean SEFAS was 28.3±10.5. Mean dorsiflexion was significantly lower on the ITFG side, at 6.6±7.9° versus 15.1±4.8° on the healthy side. There was dorsiflexion stiffness in 26 cases. No correlation emerged between dorsiflexion stiffness and onset of osteoarthritis. ConclusionDorsiflexion was the most severely impacted motion. The rate of osteoarthritis was too low for any implication of dorsiflexion loss to be demonstrated, especially in traumatic contexts. Level of evidenceIV; retrospective study.

Gait Disorder among Elderly People, Psychomotor Disadaptation Syndrome: Post-Fall Syndrome, Risk Factors and Follow-Up – A Cohort Study of 70 Patients

Introduction: Falls among older people are a major health issue and the first cause of accidental death after 75 years of age. Post-fall syndrome (PFS) is commonly known and yet poorly studied. Objective: Identify risk factors for PFS and do a follow-up 1 year later. Methods: We included all patients over 70 years of age hospitalized after suffering a fall in a case-control study, and then followed them in a cohort study. PFS was retained in case of functional mobility decline (transferring, walking) occurring following a fall in the absence of an acute neurological, orthopedic or rheumatic pathology directly responsible for the decline. The data initially collected were: clinical (anamnestic, emergency and departmental/ward evolution, medical history, lifestyle, treatments, clinical examination items); and imaging if the patient had been subjected to brain imaging in the last 3 years prior to inclusion. Regarding the follow-up at 1 year, we collected from the general physician the occurrence and the characteristics of new falls, functional mobility assessment, hospitalization and death. Results: Inclusion took place from March 29, 2016 to June 7, 2016 and follow-up until June 30, 2017. We included 70 patients. A total of 29 patients exhibited a PFS (41.4 %). Risk factors for PFS included age, walking disorder prior to the fall, the use of a walking aid prior to the fall, no unaccompanied outdoor walk in the week before the fall, visual impairment making close reading impossible, stiffness in ankle dorsiflexion, grip strength and the fear of falling. Among patients with PFS, 52.9% could still perform a transfer at 1 year and 64.7% could still walk against 80.7% and 85.2%, respectively, for patients without PFS. Conclusion: The study showed the existence of body functions/structure impairments and activity limitations prior to the fall among patients exhibiting a PFS. This suggests the existence of a pre-fall syndrome, i.e., a psychomotor disadaptation syndrome existing prior to the fall. Among the 8 risk factors, fear of falling, vision impairment and muscle strength could be targeted for improvement. The diagnosis of PFS could be a marker of loss of functional mobility at 1 year.

Inferior tibiofibular joint mobilization with movement and taping does not improve chronic ankle dorsiflexion stiffness: a randomized placebo-controlled trial

ABSTRACT Objective This study compared the modification of musculoarticular stiffness (MAS) and clinical outcomes after mobilization with movement (MWM) on the inferior tibiofibular joint and a placebo MWM. Moreover, injured and non-injured ankle MAS were compared after MWM therapy. Methods A single-blinded randomized trial was conducted on 75 participants (mean age: 22.3 ± 2.17 years) with chronic self-reported asymmetric perception of ankle dorsiflexion stiffness. Participants were allocated to one of three groups: inferior tibiofibular MWM (ITFMWM), placebo and non-injured. Sinusoidal oscillation methods were used for experimental quantification of the MAS and clinical outcomes were assessed using the weight-bearing lunge test (WBLT), pain and stiffness perception. Three assessments were made: one pre-treatment (T0), one after the manual technique (T1) and one after taping (T2). Results Two-way ANOVA showed no significant differences between the groups and no interaction effect for the outcome measures. However, a significant difference for the time effect (T0-T1-T2) was found in the three groups for WBLT dorsiflexion range of motion (p < 0.001, Cohen’s d = 0.21) and stiffness perception (p < 0.001, Cohen’s d = 0.54) but the minimal clinically important differences were not reached for either value. Discussion The results could not support that a single session of ITFMWM modifies MAS or the clinical outcomes compared to placebo treatment. Furthermore, injured MAS does not differ from non-injured MAS in chronic ankle dorsiflexion stiffness. Further studies should assess subjects’ responsiveness concerning the Mulligan concept and focus on a medium- to long-term follow-up.

Plantar fasciopathy: A current concepts review.

Plantar fasciopathy is very prevalent, affecting one in ten people in their lifetime.Around 90% of cases will resolve within 12 months with conservative treatment.Gastrocnemius tightness has been associated with dorsiflexion stiffness of the ankle and plantar fascia injury.The use of eccentric calf stretching with additional stretches for the fascia is possibly the non-operative treatment of choice for chronic plantar fasciopathy.Medial open release of approximately the medial third of the fascia and release of the first branch of the lateral plantar nerve has been the most accepted surgical treatment for years.Isolated proximal medial gastrocnemius release has been reported for refractory plantar fasciopathy with excellent results and none of the complications of plantar fasciotomy.Cite this article: EFORT Open Rev 2018;3:485-493. DOI: 10.1302/2058-5241.3.170080.

Development of an Ankle-Foot Orthosis That Provides Support for Flaccid Paretic Plantarflexor and Dorsiflexor Muscles.

ADJUST, a novel ankle-foot orthosis (AFO) that we have developed, allows the ankle a normal range of motion (ROM) while providing support for flaccid ankle-muscle paresis. It consists of two leaf-spring hinges that independently control plantarflexion and dorsiflexion stiffness. To evaluate whether ADJUST meets the minimum mechanical requirements, we quantified its ankle ROM and stiffness. To evaluate whether it meets the minimum ankle kinematic and kinetic goals for normal gait, a patient with both plantarflexor and dorsiflexor paralysis used it, and his own AFO, to walk. When fitted with stiff springs, ADJUST met all requirements and goals. During the stance and the swing phases, ankle ROM was within the normal range when ADJUST was fitted with stiff springs. Ankle ROM during stance was outside the normal range both with the patient's own AFO and with ADJUST when it was fitted with flexible springs. Power at the ankle met the minimum goal but was lower with ADJUST than with the patient's own AFO. The optimal stiffness configuration that would result in a higher power at the ankle with a normal ankle ROM was not reached for this patient. Walking with ADJUST seems feasible and could be profitable in patients with flaccid ankle muscle paresis.

Design of Powered Ankle-Foot Prosthesis With Nonlinear Parallel Spring Mechanism

In this paper, a powered ankle-foot prosthesis with nonlinear parallel spring mechanism is developed. The parallel spring mechanism is used for reducing the energy consumption and power requirement of the motor, at the same time simplifying control of the prosthesis. To achieve that goal, the parallel spring mechanism is implemented as a compact cam-spring mechanism that is designed to imitate human ankle dorsiflexion stiffness. The parallel spring mechanism can store the negative mechanical energy in controlled dorsiflexion (CD) phase and release it to assist the motor in propelling a human body forward in a push-off phase (PP). Consequently, the energy consumption and power requirements of the motor are both decreased. To obtain this desired behavior, a new design method is proposed for generating the cam profile. Unlike the existing design methods, the friction force is considered here. The cam profile is decomposed into several segments, and each segment is fitted by a quadratic Bezier curve. Experimental results show that the cam-spring mechanism can mimic the desired torque characteristics in the CD phase (a loading process) more precisely. Finally, the developed prosthesis is tested on a unilateral below-knee amputee. Results indicate that, with the assistance of the parallel spring mechanism, the motor is powered off and control is not needed in the CD phase. In addition, the peak power and energy consumption of the motor are decreased by approximately 37.5% and 34.6%, respectively.

Impact of ankle foot orthosis stiffness on Achilles tendon and gastrocnemius function during unimpaired gait

Ankle foot orthoses (AFOs) are designed to improve gait for individuals with neuromuscular conditions and have also been used to reduce energy costs of walking for unimpaired individuals. AFOs influence joint motion and metabolic cost, but how they impact muscle function remains unclear. This study investigated the impact of different stiffness AFOs on medial gastrocnemius muscle (MG) and Achilles tendon (AT) function during two walking speeds. We performed gait analyses for eight unimpaired individuals. Each individual walked at slow and very slow speeds with a 3D printed AFO with no resistance (free hinge condition) and four levels of ankle dorsiflexion stiffness: 0.25Nm/°, 1Nm/°, 2Nm/°, and 3.7Nm/°. Motion capture, ultrasound, and musculoskeletal modeling were used to quantify MG and AT lengths with each AFO condition. Increasing AFO stiffness increased peak AFO dorsiflexion moment with decreased peak knee extension and peak ankle dorsiflexion angles. Overall musculotendon length and peak AT length decreased, while peak MG length increased with increasing AFO stiffness. Peak MG activity, length, and velocity significantly decreased with slower walking speed. This study provides experimental evidence of the impact of AFO stiffness and walking speed on joint kinematics and musculotendon function. These methods can provide insight to improve AFO designs and optimize musculotendon function for rehabilitation, performance, or other goals.

Measurement of gastrocnemius muscle elasticity by shear wave elastography: association with passive ankle joint stiffness and sex differences.

Passive joint stiffness is an important quantitative measure of flexibility, but is affected by muscle volume and all of the anatomical structures located within and over the joint. Shear wave elastography can assess muscle elasticity independent of the influences of muscle volume and the other nearby anatomical structures. We determined how muscle elasticity, as measured using shear wave elastography, is associated with passive joint stiffness and patient sex. Twenty-six healthy men (24.4 ± 5.9 years) and 26 healthy women (25.2 ± 4.8 years) participated in this study. The passive ankle joint stiffness and tissue elasticity of the medial gastrocnemius (MG) were quantified with the ankle in 30° plantar flexion (PF), a neutral anatomical position (NE), and 20° dorsiflexion (DF). No significant difference in passive joint stiffness by sex was observed with the ankle in PF, but significantly greater passive ankle joint stiffness in men than in women was observed in NE and DF. The MG elasticity was not significantly associated with joint stiffness in PF or NE, but it was significantly associated with joint stiffness in DF. There were no significant differences in MG elasticity by sex at any ankle position. Muscle elasticity, measured independent of the confounding effects of muscle volume and the other nearby anatomical structures, is associated with passive joint stiffness in the joint position where the muscle is sufficiently lengthened, but does not vary by sex in any joint position tested.

The effects of prosthetic ankle stiffness on stability of gait in people with transtibial amputation.

The ability to control balance during walking is a critical precondition for minimizing fall risk, but this ability is compromised in persons with lower-limb absence because of reduced sensory feedback mechanisms and inability to actively modulate prosthesis mechanical function. Consequently, these individuals are at increased fall risk compared with nondisabled individuals. A number of gait parameters, including symmetry and temporal variability in step/stride characteristics, have been used as estimates of gait stability and fall risk. This study investigated the effect of prosthetic ankle rotational stiffness on gait parameters related to walking stability of transtibial prosthesis users. Five men walked with an experimental prosthesis that allowed for independent modulation of plantar flexion and dorsiflexion stiffness. Two levels of plantar flexion and dorsiflexion stiffness were tested during level, uphill, and downhill walking. The results demonstrate that low plantar flexion stiffness reduced time to foot-flat, and this was associated with increased perceived stability, while low dorsiflexion stiffness demonstrated trends in temporal-spatial parameters that are associated with improved gait stability (reduced variability and asymmetry). Prosthesis design and prescription for low rotational stiffness may enhance gait safety for transtibial prosthesis users at risk of unsteadiness and falls.

Deep transverse metatarsal ligament and static stability of lesser metatarsophalangeal joints: a cadaveric study.

The static support that guides motion around the lesser metatarsophalangeal joints (MTPJs) is complex. Biomechanical studies revealed important roles of both the plantar plane and collateral ligaments. Since part of the plantar plate is attached to the deep transverse metatarsal ligament (DTML), we hypothesized that the transection of the DTML in the intermetatarsal space may substantially reduce the MTPJ stability. The second, third, and fourth MTPJ stabilities of 6 fresh-frozen human cadaveric foot specimens were measured under load control. Both dorsiflexion and dorsal subluxation conditions were tested. After the intact condition was assessed, the DTML was sequentially transected such that each MTPJ had a unilateral and then a bilateral DTML transection. Stiffness data were calculated using the loading range in each test condition. Paired Student t tests were performed to test for statistical significance (P value less than .05). In intact specimens, the mean stiffness with dorsiflexion of the second, third, and fourth toes was 0.52 ± 0.15 N/deg. When the DTML was operatively transected on one side, the dorsiflexion stiffness significantly decreased 17.3% to an average of 0.43 ± 1.00 N/deg (P < .001). Subsequent transection of the DTML on the other side of each joint resulted in a further significant decrease of 5.8% to an average of 0.40 ± 0.08 N/deg (P < .001). The mean stiffness with dorsal subluxation of the intact second, third, and fourth toes was 3.55 ± 0.66 N/mm. When the DTML was operatively transected on one side, the dorsal subluxation stiffness significantly decreased 16.1% to an average of 2.98 ± 0.64 N/mm (P < .001). Subsequent transection of the DTML on the other side of each joint resulted in a further significance decrease of 7.6% to an average of 2.71 ± 0.48 N/mm (P = .016). The DTML has a significant role in maintaining lesser MTPJ ligament stability. Both unilateral and bilateral DTML transections caused substantial instability of the lesser MTPJ. The DTML is part of the natural static restraint to dorsiflexion or dorsal subluxation of the lesser MTPJ. Operative transection, injury, or degeneration of this ligament may predispose the adjacent MTPJ to instability.

The effects of prosthetic ankle stiffness on ankle and knee kinematics, prosthetic limb loading, and net metabolic cost of trans-tibial amputee gait

BackgroundPrevious studies of commercially-available trans-tibial prosthetic components have been unable to provide clear insight into the relationships between prosthetic mechanical properties and user performance (i.e., gait quality and energy expenditure), the understanding of which is key to improving prosthesis design and prescription. Many of these studies have been limited by not characterising the mechanical properties of the tested prostheses and/or only considered level walking at self-selected speeds. The aim of this study was to conduct a systematic investigation of the effects of ankle rotational stiffness on trans-tibial amputee gait during various walking conditions reflective of those encountered during daily ambulation. MethodsAnkle and knee kinematics, prosthetic limb normal ground reaction forces, and net metabolic cost were measured in five traumatic unilateral trans-tibial amputees during treadmill walking on the level, a 5% incline and a 5% decline whilst using an experimental articulated prosthetic foot with four different rotational stiffness setups and without changes in alignment between conditions. FindingsOverall, lower dorsiflexion stiffness resulted in greater prosthetic side dorsiflexion motion and sound side knee flexion, reduced normal ground reaction force during the loading phase of prosthetic stance and reduced net metabolic cost. InterpretationFew differences were observed with changes in plantarflexion stiffness, most likely due to the foot achieving early foot flat. Low dorsiflexion stiffness generally improved gait performance seemingly due to easier tibial progression during stance. However, observed differences were small, suggesting that a wider range of walking and stiffness conditions would be useful to fully explore these effects in future studies.

Passive dorsiflexion stiffness is poorly correlated with passive dorsiflexion range of motion

ObjectivesThe purpose of this study was to determine the relationships among passive measures of weight-bearing dorsiflexion range of motion, non-weight-bearing dorsiflexion range of motion and dorsiflexion stiffness, thereby establishing whether they assess similar mechanical characteristics, as each measure has been implicated in injury risk during landings. DesignCross-sectional study. MethodsPassive weight-bearing dorsiflexion range of motion, non-weight-bearing dorsiflexion range of motion and dorsiflexion stiffness were quantified for 42 males (22.8±5.0 years). The relationship between each data set was calculated using Pearson product-moment correlation coefficients. ResultsAlthough weight-bearing dorsiflexion range of motion and non-weight-bearing dorsiflexion range of motion were significantly correlated, the strength of the relationship was poor (r2=0.18; p=0.004). Weight-bearing dorsiflexion range of motion (mean=43.0±5.0°) was significantly greater than non-weight-bearing dorsiflexion range of motion (29.8±5.9°; p<0.001) and weight-bearing dorsiflexion range of motion and non-weight-bearing dorsiflexion range of motion were also poorly correlated with passive dorsiflexion stiffness (1.48±0.55Nm°−1; r2=0.04 and r2=0.14, respectively), despite the latter relationship being significant (p=0.017). ConclusionsPassive dorsiflexion stiffness was not strongly associated with dorsiflexion range of motion, despite the significant correlation in the non-weight-bearing condition. It must be acknowledged that passive dorsiflexion stiffness was weakly associated with dorsiflexion range of motion, although the strength of the association suggests that it may not necessarily determine dorsiflexion range of motion. Furthermore, the functional dorsiflexion limits of the ankle during weight-bearing tasks may be underestimated or misrepresented by non-weight-bearing measures of dorsiflexion range of motion. Therefore, although ankle dorsiflexion range of motion and dorsiflexion stiffness have been implicated in injury risk during weight-bearing tasks such as landings, it may be due to different mechanisms.

Effects of passive ankle dorsiflexion stiffness on ankle mechanics during drop landings

ObjectivesVertical landing tasks strain the Achilles tendon and plantar-flexors, increasing acute and overuse strain injury risk. This study aimed to determine how passive ankle dorsiflexion stiffness affected ankle mechanics during single limb drop landings at different vertical descent velocities. DesignCross-sectional study. MethodsPassive ankle dorsiflexion stiffness and passive weight-bearing dorsiflexion range of motion (DROM) were quantified for 42 men. Participants were then grouped as having low (LPS: 0.94±0.15Nm°−1; n=16) or high (HPS: 2.05±0.36Nm°−1; n=16; p<0.001) passive ankle dorsiflexion stiffness. Three-dimensional ankle joint kinematics was quantified while participants performed drop landings onto a force platform at two vertical descent velocities (slow: 2.25±0.16ms−1; fast: 3.21±0.17ms−1). ResultsAlthough affected by landing velocity, there were no significant effects of passive ankle dorsiflexion stiffness, nor any significant ankle dorsiflexion stiffness×vertical descent velocity interactions on any outcome variables characterising ankle mechanics during drop landings. Furthermore, there was no significant difference between the groups for passive weight-bearing DROM (LPS: 43.9±4.1°; HPS: 42.5±5.7°), indicating that the results were not confounded by between-group differences in ankle range of motion. ConclusionsNeither high nor low passive ankle dorsiflexion stiffness was found to influence ankle biomechanics during drop landings at different descent velocities. Landing strategies were moderated more by the demands of the task than by passive ankle dorsiflexion stiffness, indicating that passive ankle dorsiflexion stiffness may not affect plantar-flexor strain during a drop landing.

A New Device for Assessing Ankle Dorsiflexion Motion: Reliability and Validity

Clinical measurement. To determine the validity and reliability of measures obtained using a custom-made device for assessing ankle dorsiflexion motion and stiffness. Limited dorsiflexion has been implicated in the evolution of foot pain in a number of clinical populations. Assessment of ankle dorsiflexion range of motion (ROM) is, therefore, commonly performed as part of a foot and ankle examination. Conventional goniometric assessment methods have demonstrated limited intertester reliability, while alternative methods of measurements are generally more difficult to use. The Iowa ankle range of motion (IAROM) device was designed in an attempt to develop a simple, clinically relevant, and time- and cost-effective tool to measure ankle dorsiflexion range of motion and stiffness. Validity and intertester reliability of dorsiflexion range-of-motion measures using the IAROM device were assessed at 10, 15, 20, and 25 Nm of passively applied dorsiflexion torque, with both the knee extended and flexed approximately 20°. Stiffness (change in torque/change in dorsiflexion angle) values were determined using the angular change obtained between the 15- and 25-Nm torque levels. Convergent validity (n = 12) was assessed through comparison of ankle dorsiflexion angles measured simultaneously with the IAROM device and an optoelectronic motion analysis system. Intertester reliability (n = 17) was assessed by 2 testers who took measurements within the same day. Validity testing demonstrated excellent agreement (intraclass correlation coefficient [ICC] values ranging from 0.95 to 0.98). Reliability testing demonstrated good to excellent intertester agreement (ICC values ranging from 0.90 to 0.95). The ICCs for ankle joint dorsiflexion stiffness were .71 and .85 for the knee in an extended and flexed position, respectively. The IAROM device provides valid and reliable measurement of ankle dorsiflexion ROM. The IAROM device also allows calculation of stiffness by measuring ROM at multiple torque levels, although the reliability of the measurement is not optimal.