Angulation vs translation of transtibial prosthetic socket: their difference analyzed by socket reaction moments

BackgroundPrevious studies investigated the effects of alignment changes in transtibial prostheses on socket reaction moments. However, the effects of angular and translational alignment changes with equal displacement between the foot and the socket were not directly compared.Research questionsWhat are the different effects of angular and translational alignment changes in transtibial prostheses?MethodsTen individuals with transtibial prostheses participated in the measurement of temporo-spatial parameters, socket reaction moments, and their timings under nine alignment conditions (3° flexion/extension, anterior/posterior translation, 6° adduction/abduction, medial/lateral translation, and baseline). The displacement of the prosthetic feet was set to be equal between the angular and translational changes.ResultsNo significant changes in walking speed were found. Similar effects were observed in the magnitudes, but not in timing, of the moments under angular and translational changes in the sagittal plane (p < 0.01 for the differences in peak extension moment among anterior translation, baseline, and extension conditions, and in peak flexion moment among anterior translation, baseline, and extension conditions). In the coronal plane, similar effects were found in the magnitudes of the moments in the early stance (p < 0.01 at 5 %, 20 %, and 75 % stance). A significant difference in magnitude was observed in the late stance (p < 0.01 between adduction and medial translation conditions).SignificanceThe timing of the socket reaction moment may be different in the sagittal plane, while the magnitudes of the socket reaction moment in the late stance may be different in the coronal plane between the angular and translational alignment changes.     

Dynamic alignment using external socket reaction moments in trans-tibial amputees

BackgroundProsthetic alignment is used to optimize prosthetic functioning and comfort. Spatio-temporal and kinematic gait parameters are generally observed to guide this process. However, they have been shown to be influenced by compensations, which reduces their sensitivity to changes in alignment. Alternatively, the use of moments working at the base of the prosthetic socket, external socket reaction moments (ESRM), has been proposed to quantify prosthetic alignment.Research questionTo investigate if a predetermined kinetic alignment criterion, 0Nm averaged over the stance phase, can be used to fine-tune prosthetic alignment.Methods10 transtibial amputees were included in this intervention study. Firstly, their prostheses were aligned using conventional alignment procedures. Kinetic parameters and Socket Comfort Score (SCS) were measured in this initial alignment (IA) condition. Subsequently, the coronal plane ESRM during gait was presented to the prosthetist in real time using a Gait Real-time Analysis Interactive Lab. The prosthetist iteratively adapted the prosthetic alignment towards a predetermined average ESRM during the stance phase of 0 Nm. At the Final Alignment (FA), kinetic parameters and SCS were measured again and a paired sample t-test was performed to compare ESRMs and SCSs between alignments.ResultsA significant (p < 0.001) change was found in the absolute coronal plane ESRM (mean ± SD) from IA (|0.104| ± 0.058 Nm/kg) to FA (|0.012| ± 0.015 Nm/kg). In addition a significant (p < 0.001) change of the external coronal adduction knee moments was observed from IA (−0,127 ± 0.079 Nm/kg) to FA (−0.055 ± 0.089 Nm/kg), however this change was more variable among participants. On average, no significant (p = 0.37) change in the SCS was observed.SignificanceWhile this study shows the potential of quantifying and guiding alignment with the assistance of kinetic criteria, it also suggests that a sole reliance on the ESRM as a single alignment criterion might be too simple.     

Compensatory mechanisms of transtibial amputees during circular turning

Turning plays a prominent role in daily living activities and requires the modulation of the ground reaction forces to accelerate the body's center-of-mass along the path of the turn. With the ankle plantarflexors being prominent contributors to the propulsive ground reaction forces, it is not clear how transtibial amputees perform turning tasks without these important muscles. The purpose of this study was to identify the compensatory mechanisms used by transtibial amputees during a simple turning task by analyzing the radial and anterior–posterior ground reaction impulses and sagittal, transverse and coronal joint work of the residual and intact legs. These quantities were analyzed with the residual leg on both the inside and outside of the turn and compared to non-amputees. The analysis showed that amputees and non-amputees use different joint strategies to turn. Amputees rely primarily on sagittal plane hip joint work to turn while non-amputees rely primarily on ankle work in the sagittal plane and hip joint work in the coronal plane. Differences in strategies are most likely due to the minimal power output provided by the passive prosthetic feet used by amputees and perhaps a desire to minimize the risk of falling. Understanding these differences in turning strategies will aid in developing effective rehabilitation therapies and prosthetic devices that improve amputee mobility.     

The impact of transfemoral socket adduction on pelvic and trunk stabilization during level walking – A biomechanical study

BackgroundIt is common practice to align transfemoral prosthetic sockets in adduction, due to the physiologic, adducted femoral alignment in unimpaired legs. An adducted femoral and socket alignment helps tightening hip abductors to stabilize the pelvis and reduce pelvic and trunk related compensatory movements.Research questionHow do different socket adduction conditions (SAC) of transfemoral sockets affect pelvic and trunk stabilization during level ground walking in the frontal plane?MethodsSeven persons with transfemoral amputation with medium residual limb length participated in this study. The prosthetic alignment in the sagittal plane was performed according to established recommendations. SAC varied (0°, 3°, 6°, 9°). Kinematic and kinetic parameters were recorded in a gait laboratory with a 12-camera optoelectronic system and two piezoelectric force plates embedded in a 12-m walkway. The measurements were performed during level ground walking with self-selected comfortable gait speed.ResultsIn the frontal plane, nearly all investigated kinematic and kinetic parameters showed a strong correlation with the SAC. The pelvis was raised on the contralateral side throughout the gait cycle with increasing SAC. During the prosthetic side stance phase, the mean shoulder obliquity and mean lateral trunk lean to the prosthetic side tended to be reduced with increased SAC. Prosthetic side hip abduction moment decreased with increasing SAC.SignificanceThe results confirm that transfemoral SAC contributes to pelvic stabilization and reduced compensatory movements of the pelvis and trunk. Transfemoral SAC of 6 ± 1° for bench alignment seems adequate for amputees with medium residual limb length. However, the optimum value for the individual patient may differ slightly.     

Native anterior cruciate ligament obliquity versus anterior cruciate ligament graft obliquity: an observational study using navigated measurements

BACKGROUND: The goal of anterior cruciate ligament reconstruction is to attain a graft that closely resembles the native anterior cruciate ligament anatomy. By reconstructing the original anatomy, one hopes to eliminate issues related to graft elongation, impingement, and excessive tension while achieving ideal knee kinematics. HYPOTHESIS: Clinical grafts placed using the transtibial technique will differ in the sagittal and coronal planes when compared with obliquity of the anatomic anterior cruciate ligament. STUDY DESIGN: Controlled laboratory study/case series; Level of evidence, 4. METHODS: With the assistance of computer navigation, our study compared the anterior cruciate ligament orientation of 5 cadaver knees with 12 clinical anterior cruciate ligament-reconstructed knees using the transtibial technique. Results: Clinical graft obliquity differed from the anatomic anterior cruciate ligament in all flexion angles: 0 degrees, 30 degrees, 60 degrees, and 90 degrees. In the sagittal plane, the clinical graft obliquity differed from the anatomic anterior cruciate ligament by 13.6 degrees, 12.7 degrees, 16.7 degrees, and 17 degrees, respectively. In the coronal plane, the clinical graft obliquity differed from the anatomic anterior cruciate ligament by 4.9 degrees, 7.6 degrees, 8.9 degrees, and 12.7 degrees, respectively. Paired t tests demonstrated that the difference between the clinical and anatomic anterior cruciate ligament was significant (P <.05), except in the coronal plane at 0 degrees of flexion. In spite of this, all patients demonstrated a negative pivot shift and Lachman at the conclusion of their reconstructions and at 6-month follow-up. CONCLUSION: The sagittal and coronal plane obliquity of well-functioning grafts placed using the transtibial technique were more vertical than anatomic fibers. CLINICAL RELEVANCE: Graft obliquity, in both the coronal and sagittal plane, may be an important means to target appropriate anterior cruciate ligament graft position and can be monitored using surgical navigation systems.     

Conventional or navigated total knee arthroplasty affects sagittal component alignment

Purpose

Navigation systems have recently been developed to achieve highly reliable prosthetic alignment in total knee arthroplasty (TKA). However, component alignment in the sagittal plane is less reliable than that in the coronal plane even when navigation systems are used. Previous reports examining men showed differences in targeted sagittal prosthetic alignments of TKA achieved using the conventional technique and various navigation systems. However, there have been few studies examining the use of this technique in women, who are the primary candidates for TKA.

Methods

Radiographs of the entire lower extremity were obtained from 20 elder women while standing and sagittal prosthetic alignments in TKA were planned using the conventional technique as well as three navigation approaches to establish reference frames, and the observations were compared.

Results

Sagittal alignments simulated using the radiographs for the conventional technique and navigation systems differed within a mean of 3.2°?±?1.7° (mean?±?SD) to 6.3°?±?2.0°. The use of different reference points on the distal femoral condyles (insertion point of the intramedullary rod, center of the anteroposterior direction of the femoral condyles, and most distal point of the femoral condyles) for each navigation system resulted in differences in the sagittal plane up to 3.0°?±?1.5°. The use of navigation systems resulted in a more hyperextended position between the femoral and tibial components compared to that for the conventional technique.

Conclusions

Targeted sagittal prosthetic alignments of TKA achieved using the conventional technique and various navigation systems differed in elderly women. The use of different reference points on the distal femoral condyle for navigation systems resulted in different alignment in the sagittal plane. This study showed that alignment tendencies are similar in men and women.

Level of evidence

Prognostic studies, IV.     

Rotation of intramedullary alignment rods affects distal femoral cutting plane in total knee arthroplasty

Purpose

Intramedullary rods are widely used to align the distal femoral cut in total knee arthroplasty. We hypothesised that both coronal (varus/valgus) and sagittal (extension/flexion) cutting plane are affected by rotational changes of intramedullary femoral alignment guides.

Methods

Distal femoral cuts using intramedullary alignment rods were simulated by means of a computer-aided engineering software in 4°, 6°, 8°, 10°, and 12° of valgus in relation to the femoral anatomical axis and 4° extension, neutral, as well as 4°, 8°, and 12° of flexion in relation to the femoral mechanical axis. This reflects the different angles between anatomical and mechanical axis in coronal and sagittal planes. To assess the influence of rotation of the alignment guide on the effective distal femoral cutting plane, all combinations were simulated with the rod gradually aligned from 40° of external to 40° of internal rotation.

Results

Rotational changes of the distal femoral alignment guides affect both the coronal and sagittal cutting planes. When alignment rods are intruded neutrally with regards to sagittal alignment, external rotation causes flexion, while internal rotation causes extension of the sagittal cutting plane. Simultaneously the coronal effect (valgus) decreases resulting in an increased varus of the cutting plane. However, when alignment rods are intruded in extension or flexion partly contradictory effects are observed. Generally the effect increases with the degree of valgus preset, rotation and flexion.

Conclusion

As incorrect rotation of intramedullary alignment guides for distal femoral cuts causes significant cutting errors, exact rotational alignment is crucial. Coronal cutting errors in the distal femoral plane might result in overall leg malalignment, asymmetric extension gaps and subsequent sagittal cutting errors.

     

The accuracy of intramedullary tibial guide of sagittal alignment of PCL-substituting total knee arthroplasty

Experimental and clinical studies on the accuracy of the intramedullary alignment method have produced different results, and few have addressed accuracy in the sagittal plane. Reported deviations are not only attributable to the alignment method but also to radiological errors. The purpose of this study was to evaluate the accuracy of the intramedullary alignment method in the sagittal plane using computed tomography (CT) and 3-dimensional imaging software. Thirty-one TKAs were performed using an intramedullary alignment method involving the insertion of a long 8-mm diameter rod into the medullary canal to the distal metaphysis of the tibia. All alignment instruments were set to achieve an ideal varus/valgus angle of 0° in the coronal plane and a tibial slope of 0° in the sagittal plane. The accuracy of the intramedullary alignment system was assessed by measuring the coronal tibial component angle and sagittal tibial slope angles, i.e., angles between the tibial anatomical axis and the tangent to the medial and lateral tibial plateau or the cut-surface. The mean coronal tibial component angle was 88.5° ± 1.2° and the mean tibial component slope in the sagittal plane was 1.6° ± 1.2° without anterior slope. Our intramedullary tibial alignment method, which involves passing an 8-mm diameter long rod through the tibial shaft isthmus, showed good accuracy (less than 3 degrees of variation and no anterior slope) in the sagittal plane in neutral or varus knees.     

Lumbopelvic coordination while walking in service members with unilateral lower limb loss: Comparing variabilities derived from vector coding and continuous relative phase

BackgroundContinuous relative phase and vector coding are two common approaches for quantifying lumbopelvic coordination and variability. Evaluating the application of such methodologies to the lower limb loss population is important for better understanding reported asymmetrical movement dynamics of the lumbopelvic region.Research QuestionHow do coordination variabilities derived from trunk-pelvic coupling angles and continuous relative phases compare among individuals with and without unilateral lower limb loss walking at self-selected speeds?MethodsFull-body kinematics were obtained from thirty-eight males with unilateral lower limb loss (23 transtibial and 15 transfemoral) and fifteen males without limb loss while walking along a 15 m walkway. Coordination variabilities were derived from trunk-pelvic coupling angles and continuous relative phases and compared using a multivariate approach, as well as in unilateral outcome measures between control participants and participants with lower limb loss.ResultsOverall, tri-planar measures of continuous relative phase variability were 19–43% larger compared to coupling angle variabilities for individuals without limb loss and individuals with transtibial limb loss. Individuals with transfemoral limb loss had 27% and 31% larger sagittal and transverse variabilities from continuous relative phases compared to coupling angles, respectively. During both prosthetic and intact limb stance, individuals with transtibial limb loss had 19–35% greater tri-planar measures of continuous relative phase variability compared to coupling angle variabilities. During intact stance phase, tri-planar measures of continuous relative phase variability were 27%− 42% larger compared to coupling angle variabilities for individuals without limb loss.SignificanceWhile both methods provide valid estimates of lumbopelvic movement variability during gait, continuous relative phase variability may provide a more sensitive estimate in the lower limb loss population capturing velocity-specific motions of the trunk and pelvis.     

Navigated total knee arthroplasty: is it error-free?

Purpose

The aim of this study was to determine whether errors do occur in navigated total knee arthroplasty (TKAs) and to study whether errors in bone resection or implantation contribute to these errors.

Methods

A series of 20 TKAs was studied using computer navigation. The coronal and sagittal alignments of the femoral and tibial cutting guides, the coronal and sagittal alignments of the final tibial implant and the coronal alignment of the final femoral implant were compared with that of the respective bone resections. To determine the post-implantation mechanical alignment of the limb, the coronal alignment of the femoral and tibial implants was combined.

Results

The median deviation between the femoral cutting guide and bone resection was 0° (range ?0.5° to +0.5°) in the coronal plane and 1.0° (range ?2.0° to +1.0°) in the sagittal plane. The median deviation between the tibial cutting guide and bone resection was 0.5° (range ?1.0° to +1.5°) in the coronal plane and 1.0° (range ?1.0° to +3.5°) in the sagittal plane. The median deviation between the femoral bone resection and the final implant was 0.25° (range ?2.0° to 3.0°) in the coronal plane. The median deviation between the tibial bone resection and the final implant was 0.75° (range ?3.0° to +1.5°) in the coronal plane and 1.75° (range ?4.0° to +2.0°) in the sagittal plane. The median post-implantation mechanical alignment of the limb was 0.25° (range ?3.0° to +2.0°).

Conclusions

When navigation is used only to guide the positioning of the cutting jig, errors may arise in the manual, non-navigated steps of the procedure. Our study showed increased cutting errors in the sagittal plane for both the femur and the tibia, and following implantation, the greatest error was seen in the sagittal alignment of the tibial component. Computer navigation should be used not only to guide the positioning of the cutting jig, but also to check the bone resection and implant position during TKA.

Level of evidence

IV.     

Trunk and pelvis movement compensation in people with multiple sclerosis: Relationships to muscle function and gait performance outcomes

BackgroundProblems with gait are common in people with multiple sclerosis (MS), but little is known about pelvis and trunk kinematics, especially in the frontal plane.Research questionAre pelvis and trunk kinematics in people with MS related to muscle function, spatiotemporal parameters, and gait performance?MethodsIn this cross-sectional study, 20 people with MS (Expanded Disability Status Scale 1.5–5.5) and 10 people with comparable age and sex (CTL) underwent threedimensional gait analysis, muscle function assessments (hip and trunk strength and endurance), and gait performance measures (Timed 25-Foot Walk – T25FW, 2-Minute Walk Test – 2MWT). Frontal and sagittal plane pelvis and trunk excursion during the stance period of walking were compared between groups; and in the MS group, associations were determined between kinematic variables, muscle function, spatiotemporal parameters, and gait performance.ResultsCompared to the CTL group, the MS group had significantly greater sagittal plane trunk and pelvis excursion for both the stronger (p = 0.031) and weaker (p = 0.042) sides; less frontal plane trunk and pelvis excursion for both the stronger (p = 0.008) and weaker (p = 0.024) sides; and more sagittal plane trunk excursion for the stronger side (p = 0.047) during stance phase. There were low-to-moderate correlations in the MS group for sagittal plane pelvis excursion with muscle function (p = 0.019 to 0.030), spatiotemporal parameters (p < 0.001 to 0.005), and gait performance (p = < 0.001 to 0.001). Using linear regression, frontal and sagittal plane pelvis excursion were significant predictors of both T25FW and 2MWT, explaining 34 % and 46 % of the variance of each gait performance measure, respectively.SignificanceRehabilitation interventions may consider addressing pelvis movement compensations in order to improve spatiotemporal parameters and gait performance in people with MS.     

Intra- and post-operative accuracy assessments of two different patient-specific instrumentation systems for total knee replacement

Purpose

The aim of this study is to assess and compare the accuracy of two different patient-specific instrumentation (PSI) systems for total knee replacement, both intra-operatively for bone preparation and post-operatively for final component alignment.

Methods

Twenty-five patients were treated according to a computer tomography (CT)-based PSI system (group A) and 25 to a magnetic resonance imaging (MRI)/X-ray-based system (group B). Alignments on the three anatomical planes and resection thickness at the cutting blocks and at the resulting bone cuts were recorded intra-operatively by a standard surgical navigation system. Alignments of the prosthetic components and mechanical axis were also measured post-operatively on radiographs. These measurements at both the femur and tibia were compared with those of the corresponding pre-operative planning, considering discrepancies larger than 3° as outliers.

Results

In both groups, the mean absolute differences between pre-operatively planned alignments and corresponding intra- and post-operative measurements ranged from a minimum of 1.2° to a maximum of 2.9° in all three anatomical planes. In both groups and in both femur and tibia, the plane with the smallest percentage of outliers was the coronal, maximum 17 %. The comparison between two groups was statistically significant (p = 0.02) in the femoral sagittal plane, where group B showed smaller alignment discrepancies at the cutting blocks.

Conclusions

Both PSI systems showed good alignments in the coronal plane in all stages. For a few measurements, a better performance was observed in the MRI/X-ray-based system than in the CT-based system.

Level of evidence

I.     

Muscle capacity to accelerate the body during gait varies with foot position in cerebral palsy

BackgroundChildren with cerebral palsy (CP) often have altered gait patterns compared to their typically developing peers. These gait patterns are characterized based on sagittal plane kinematic deviations; however, many children with CP also walk with altered transverse plane kinematics.Research QuestionHow do both altered skeletal alignment and kinematic deviations affect muscles’ capacity to accelerate the body during gait?MethodsA three-dimensional gait analysis was completed for 18 children with spastic CP (12.5 ± 2.9 years; GMFCS level II). Musculoskeletal models were developed for each participant, and tibial torsion, measured during a static standing trial and assessed using motion capture, was incorporated. An induced acceleration analysis was performed to evaluate the capacity of muscles to accelerate the body center of mass throughout stance. Differences between the root-mean-square muscle capacity for children with CP walking with internally rotated, standard, and externally rotated postures were evaluated.ResultsExternally rotated postures resulted in a lower capacity to accelerate the body center of mass compared with internally rotated postures. Both changes in skeletal alignment and kinematics contributed to changes in muscle capacity to accelerate the body.SignificanceAltered transverse plane skeletal alignment and compensatory kinematics should both be considered in surgical treatment of children with CP.     

The change in sagittal plane gait patterns from childhood to maturity in bilateral cerebral palsy

BackgroundThe longitudinal stability of sagittal gait patterns in diplegic cerebral palsy (CP), stratified using the Rodda classification, is currently unknown.Research questionWhat is the trajectory of sagittal plane gait deformities as defined by the Rodda classification in a large cohort treated with orthopedic surgery guided by gait analysis?MethodsA retrospective study utilized gait analysis to evaluate sagittal gait parameters before age 8 and after age 15 years. Individual limbs were categorized at each time point according to the Rodda classification based on mean sagittal plane knee and ankle angle during stance. Welch’s t-tests compared gait variables from early childhood with maturity and examined changes associated with plantarflexor lengthening surgery.Results100 youth with CP were evaluated twice: at a mean age of 5.49 ± 1.18 and 19.09 ± 4.32 years, respectively. Gross Motor Function Classification System distribution at maturity was I (10.5 %), II (55.2 %), III (28.6 %), and IV (5.7 %). At the initial visit, most limbs were in either true equinus (30 %) or jump-knee gait (26.5 %). At maturity, crouch gait (52.5 %) was the most common classification, of which 47.6 % were mild (1–3 standard deviations from age-matched norm; 21°–30°) and 52.4 % moderate or severe. For the entire cohort, at initial and final visits, respectively, mean knee flexion in stance was 26.8°±14.8° and 25.9°±11.4° (p = 0.320), ankle dorsiflexion in stance increased from −0.3°±11.5° to 9.0°±6.0° (p < 0.001), and passive knee flexion contracture was −2.3°±7.0° and -3.9°±8.0° (p = 0.043). In children who started in true equinus, apparent equinus, and crouch, there was no difference in stance phase knee flexion at maturity between those who underwent plantarflexor lengthenings versus those who did not (p > 0.18).SignificanceThe trend in this cohort was toward crouch with increased stance phase ankle dorsiflexion from early childhood to maturity. Plantarflexor lengthenings were not a significant factor in the progression of stance phase knee flexion.     

Rear-foot, mid-foot and fore-foot motion during the stance phase of gait

This paper proposes a new protocol designed to track a large number of foot segments during the stance phase of gait with the smallest possible number of markers, with particular clinical focus on coronal plane alignment of the rear-foot, transverse and sagittal plane alignment of the metatarsal bones, and changes at the medial longitudinal arch. The shank, calcaneus, mid-foot and metatarsus were assumed to be 3D rigid bodies. The longitudinal axis of the first, second and fifth metatarsal bones and the proximal phalanx of the hallux were also tracked independently. Skin markers were mounted on bony prominences or joint lines, avoiding the course of main tendons. Trajectories of the 14 markers were collected by an eight-camera motion capture system at 100 Hz on a population of 10 young volunteers. Three-dimensional joint rotations and planar angles were calculated according to anatomically based reference frames. The marker set was well visible throughout the stance phase of gait, even in a camera configuration typical of gait analysis of the full body. The time-histories of the joint rotations and planar angles were well repeatable among subjects and consistent with clinical and biomechanical knowledge. Several dynamic measurements were originally taken, such as elevation/drop of the medial longitudinal arch and of three metatarsal bones, rear-foot to fore-foot rotation and transverse plane deformation of the metatarsus. The information obtained from this protocol, consistent with previous clinical knowledge, enhanced our understanding of the dynamics of the human foot during stance.     

Spring-mass behavioural adaptations to acute changes in prosthetic blade stiffness during submaximal running in unilateral transtibial prosthesis users

BackgroundIndividuals with lower-limb amputation can use running specific prostheses (RSP) that store and then return elastic energy during stance. However, it is unclear whether varying the stiffness category of the same RSP affects spring-mass behaviour during self-selected, submaximal speed running in individuals with unilateral transtibial amputation.Research questionThe current study investigates how varying RSP stiffness affects limb stiffness, running performance, and associated joint kinetics in individuals with a unilateral transtibial amputation.MethodsKinematic and ground reaction force data were collected from eight males with unilateral transtibial amputation who ran at self-selected submaximal speeds along a 15 m runway in three RSP stiffness conditions; recommended habitual stiffness (HAB) and, following 10-minutes of familiarisation, stiffness categories above (+1) and below (-1) the HAB. Stance-phase centre of mass velocity, contact time, limb stiffness’ and joint/RSP work were computed for each limb across RSP stiffness conditions.ResultsWith increased RSP stiffness, prosthetic limb stiffness increased, whilst intact limb stiffness decreased slightly (p<0.03). Centre of mass forward velocity during stance-phase (p<0.02) and contact time (p<0.04) were higher in the intact limb and lower in the prosthetic limb but were unaffected by RSP stiffness. Intact limb hip joint positive work increased for both the +1 and -1 conditions but remained unchanged across conditions in the prosthetic limb (p<0.02).SignificanceIn response to changes in RSP stiffness, there were acute increased mechanical demands on the intact limb, reflecting a reliance on the intact limb during running. However, overall running speed was unaffected, suggesting participants acutely adapted to an RSP of a non-prescribed stiffness.     

Sagittal alignment of the lower extremity while standing in female

There is only limited information available on the sagittal alignment of the lower extremity of normal subjects under weight-bearing conditions. Our aim was to determine the sagittal alignment of the lower extremity under such conditions. Anteroposterior and lateral radiographs were taken of the 20 lower extremities of 20 healthy female volunteers while standing. The coronal mechanical axis passed through 29% medial to the proximal tibial articulating surface. The sagittal mechanical axis passed through 44% anterior to the distal femoral condyle and 33% anterior to the proximal tibial articulating surface, and also passed 3 mm anterior to the intercondylar notch. Our study showed that the coronal and sagittal mechanical axes of the lower extremity do not always pass through the center of the knee. Our results will provide important information for alignment in surgery of lower extremity such as knee arthroplasty and osteotomy.     

Lower extremity joint moments throughout gait at two speeds more than 4 years after ACL reconstruction

BackgroundLong-term gait adaptations after anterior cruciate ligament reconstruction (ACLR) have been reported. However, it is still unclear if they persist more than 4 years after surgery and if they are affected by gait speed.Research question: To investigate differences between groups, legs and walking speeds for ankle, knee and hip joint moments in three planes throughout the stance phase of gait.MethodsReconstructed participants (n = 20 males, 32.5 years, 5.5 years post-ACLR) and healthy controls (n = 20 males, 30.6 years) took part in the study. Gait analysis was performed in two different speeds (self-selected and 30% faster). Sagittal, frontal and transverse plane external moments were measured for ankle, knee and hip and compared throughout the stance phase using 95% confidence intervals. Significant differences were established as a consecutive 5% of gait cycle in which 95% confidence interval did not overlap.ResultsThe reconstructed leg did not demonstrate higher joint moments; there were largely no differences while there was lower knee external rotation moment compared to the non-preferred leg of the control group. Higher joint moments were observed during fast speed walking on sagittal plane for knee and hip moments in both groups, and in the frontal and transverse plane for ankle moments.SignificanceGait kinetics appear to be largely normalized at a minimum of 4 years after ACLR. Faster walking speed increase lower extremity joint moments.     

Kinematics and kinetics with an adaptive ankle foot system during stair ambulation of transtibial amputees

Conventional prosthetic feet cannot adapt to specific conditions such as walking on stairs or ramps. Amputees are therefore forced to compensate their prosthetic deficits by modifying the kinematics and kinetics of their lower limbs. The Proprio-Foot™ (Ossur) intends to reduce these compensation mechanisms by automatically increasing dorsiflexion during stair ambulation thanks to an adaptive microprocessor-controlled ankle. The present investigation proposes to analyze the biomechanical effects of the dorsiflexion adaptation in transtibial (TT) amputees during stair ambulation.Sixteen TT amputees and sixteen healthy controls underwent conventional 3D gait analysis. Kinematics and kinetics of the lower limbs were compared during stair ascent and descent performed by patients with the prosthetic foot set to a neutral ankle angle and with an adapted dorsiflexion ankle angle of 4°. Norm distance as well as minimum and maximal values of sagittal kinematics and kinetics were calculated for comparisons between patients and control subjects.For both stair ascent and descent, an improvement of the knee kinematics and kinetics could particularly be noticed on the involved side with an increase of the knee flexion and an increase of the knee moment during stance.Therefore, despite its additional weight compared to a conventional prosthetic ankle, the Proprio-Foot™ should be beneficial to active TT amputees whose knee musculature strength does not constitute a handicap.     

Kinematic changes in patients with severe knee osteoarthritis are a result of reduced walking speed rather than disease severity

BackgroundKinematic changes in patients with knee osteoarthritis (OA) have been extensively studied. Concerns have been raised whether the measured spatiotemporal and kinematic alterations are associated with disease progression or merely a result of reduced walking speed.Research question: The purpose of this study was to investigate the effect of walking speed on kinematic parameters in patients with knee OA using statistical parametric mapping (SPM).MethodsTwenty-three patients with unilateral knee OA scheduled for a total knee replacement and 28 age matched control subjects were included in this study. Spatiotemporal parameters and sagittal plane kinematics were measured in the hip, knee, and ankle using the inertial sensors system RehaGait® while walking at a self-selected normal (patients and controls) and slow walking speed (controls) for a distance of 20 m. Gait parameters were compared between groups for self-selected walking speed and for matched walking speed using SPM with independent sample t tests.ResultsAt self-selected walking speed, patients had significantly lower knee flexion during stance (maximum difference, -6.8°) and during swing (-11.0°), as well as higher ankle dorsiflexion during stance phase (+12.5°) and lower peak hip extension at the end of stance compared to controls (+4.2°). At matched speed, there were no significant differences in joint kinematics between groups.SignificanceDifferences in sagittal plane gait kinematics between patients with knee OA and asymptomatic controls appear to be mainly a result of reduced walking speed. These results emphasize the importance of considering walking speed in research on gait kinematics in patients with knee OA and in clinical trials using gait parameters as outcome measures.