Alignment Of Prosthesis Research Articles

Navigation-assisted versus conventional total knee replacement: no difference in patient-reported outcome measures (PROMs) at 1 and 2 years.

Navigation technique for total knee replacement has been shown to improve accuracy of prosthesis alignment in several studies. The purpose was to compare the patient-reported outcome measures in primary total knee replacement (TKR) using navigation versus conventional surgical technique at 1- and 2-year follow-up. A retrospective review of prospectively collected patient-reported outcome data for 351 consecutively performed primary TKR was included in the study. The study group (N = 113) included patients who had Triathlon TKR using articular surface mounted (ASM Stryker) navigation technique and control group (N = 238) included patients who had Triathlon TKR using conventional jig. In addition to the WOMAC (Western Ontario and McMaster University Osteoarthritis Index) and SF-36 (Medical Outcomes Trust Short Form-36), a short self-report questionnaire evaluating the level of satisfaction, quality of life and whether patients would undergo knee replacement again. WOMAC: no significant difference between the groups was noted in mean WOMAC pain, function and stiffness scores at 1- and 2-year follow-up. SF-36: no significant difference between the groups was seen except in the physical function component of score at 1 year (p = 0.019). Navigation group mean 56.78 (CI 51.06-62.5) versus conventional group mean 48.34 (44.68-52.01) but this difference was not observed at 2-year follow-up. The overall patient-reported outcome scores improved after total knee replacement but appear to be comparable in both groups at 1- and 2-year follow-up.

Chirurgia protesica mini-invasiva computer-assistita nell’artrosi di ginocchio in esiti di osteosintesi per fratture di femore

Post-traumatic knee arthrosis can be the result of residual misalignment outcome of the fracture or the result of a direct injury of the articular surface. Hardware presence and bone sclerosis often make impossible the use of intramedullary guides for the correct prosthesis alignment.

Socket reaction moments in transtibial prostheses during walking at clinically perceived optimal alignment.

The socket reaction moments are directly measured at the base of a socket and may be useful for fitting a prosthesis. Previous studies have focused on the effect of prosthetic alignment changes on them. The aim of this study was to explore their range at clinically perceived optimal alignment by investigating the individual differences. In total, 11 amputees using unilateral transtibial prostheses with solid-ankle-cushion-heel (SACH) feet were recruited. The socket reaction moments were measured using a custom instrumented prosthesis alignment component and plotted. Eight variables that were related to their magnitude (N m/kg) and timing (% stance of event) as well as cadence (steps/minute) were calculated for each amputee. Their mean, standard deviation, maximum value, minimum value, and range were subsequently analyzed. This study may serve as a foundation to explore the range of individual differences in socket reaction moments in transtibial prostheses. Socket reaction moments can be conveniently measured in the clinical setting. Prosthetists could potentially use them as one of the criteria to align prosthesis in addition to observational gait analysis and amputees perception.

Long term survivorship following Scorpio Total Knee Replacement

BackgroundThe Scorpio Total Knee Replacement (TKR) is one of the most commonly used prosthesis in the United Kingdom. Concerns arose at our institution that there was a high revision rate for this prosthesis. No study has assessed survivorship of this prosthesis over 10 years. MethodsFour hundred and fifty-six consecutive patients, who underwent a primary Scorpio TKR, were clinically and radiologically evaluated. WOMAC, Oxford Knee Score and all complications including the reason for revision surgery were recorded. The Knee Society Roentgenographic Evaluation and Scoring System was used to evaluate all radiographs for prosthesis alignment and degree of subsequent lucency. Survival analysis for the prosthesis was calculated using Kaplan–Meier curves, with revision as an end-point. Patient reported outcome measures were compared against radiographic evaluation. ResultsAt a mean of 12.5 years (range 10–14 years), 196 (43.0%) patients were available for review; 124 (27.2%) were lost to follow-up and 136 (29.8%) patients had died of unrelated causes. Seven (3.6%) patients required revision surgery at a mean of 5.4 years; five because of aseptic loosening and two because of septic loosening. Cumulative survival for the prosthesis was 99.5% for any cause at five years and 97.4% at 14 years. The mean OKS and WOMAC score at final follow-up was 30.64 (range12–48) and 74 (18.9–100) respectively. ConclusionThe Scorpio TKR has good long term survivorship and functional outcomes. There is no apparent increased revision rate for this prosthesis in our study. Level of evidenceLevel IV case series.

Postoperative Migration of Short Stem Prosthesis of the Hip Joint

Hip replacement surgery is a popular procedure that provides predictable, long-lasting and good effects. The use of short stem prostheses helps preserve an intact medullary cavity and proximal diaphysis. It has been demonstrated that the use of short stem prostheses leads to better clinical results compared to standard stem prostheses. The study aimed to assess the migration of the stem of the Proxima hip prosthesis. Migration was defined as a change in the angle of stem position towards a varus deformity. The study involved 164 patients (83 women, 81 men) who underwent hip replacement surgery with a total of 185 Proxima prostheses in the Cracow Rehabilitation Centre between 2007 and 2012. Radiographic analysis included a series of three radiographs obtained for each patient on Day 0 and after 6 and 12 months. Stem migration towards a varus deformity was reported during the follow-up period. There was a correlation between the change in the angle of varus prosthesis alignment and the length of follow-up. The mean change of the varus angle was 8.21° after 12 months. There was a statistically significant difference in the angle of the varus prosthesis alignment between the sexes. After 12 months the total change was 6.82° in women and 9.65° in men. There was no significant correlation between a patient's BMI, age, the total length of the neck of the implant and the progression of the angle of varus prosthesis alignment. 1. The greatest displacement of the Proxima short stem implant towards a varus deformity is seen within the first 6 months following implantation. 2. The change of the angle of varus prosthesis alignment depends on the initial positioning of the prosthesis and the sex of the patient. 3. The change of the angle of varus prosthesis alignment is independent from the patient's age and BMI.

The effects of changes in the sagittal plane alignment of running-specific transtibial prostheses on ground reaction forces.

[Purpose] To verify the effects of sagittal plane alignment changes in running-specific transtibial prostheses on ground reaction forces (GRFs). [Subjects and Methods] Eight transtibial amputees who used running-specific prostheses during sprinting participated. The sprint movements were recorded using a Vicon-MX system and GRF measuring devices. The experiment levels were set as regularly recommended alignment (REG; the normal alignment for the subjects) and dorsiflexion or plantar flexion from the REG. [Results] The subjects were classified into fast (100-m personal best < 12.50 s) and slow (100-m personal best ≥ 12.50 s) groups. In both groups, there were no significant differences in the center of gravity speed; further, the difference in the stance time was significant in the slow group but not in the fast group. Significant differences were observed in the step length for the fast group, whereas the stance time and step rate significantly differed in the slow group. The GRF impulse showed significant differences in the vertical and braking directions in both groups. [Conclusion] The GRFs are affected by sagittal plane alignment changes in running-specific prostheses. Moreover, our results suggest that the change in GRFs along with the altered sagittal plane alignment influenced the step length and step rate.

Assessment of prosthesis alignment after revision total knee arthroplasty using EOS 2D and 3D imaging: a reliability study.

IntroductionA new low-dose X-ray device, called EOS, has been introduced for determining lower-limb alignment in 2D and 3D. Reliability has not yet been assessed when using EOS on lower limbs containing a knee prosthesis. Therefore purpose of this study was to determine intraobserver and interobserver reliability of EOS 2D and 3D knee prosthesis alignment measurements after revision total knee arthroplasty (rTKA).MethodsForty anteroposterior and lateral images of 37 rTKA patients were included. Two observers independently performed measurements on these images twice. Varus/valgus angles were measured in 2D (VV2D) and 3D (VV3D). Intraclass correlation coefficients and the Bland and Altman method were used to determine reliability. T-tests were used to test potential differences.ResultsIntraobserver and interobserver reliability were excellent for VV2D and VV3D. No significant difference or bias between the first and second measurements or the two observers was found. A significant mean and absolute difference of respectively 1.00° and 1.61° existed between 2D and 3D measurements.ConclusionsEOS provides reliable varus/valgus measurements in 2D and 3D for the alignment of the knee joint with a knee prosthesis. However, significant differences exist between varus/valgus measurements in 2D and 3D.

Effects of physical exertion on trans-tibial prosthesis users' ability to accommodate alignment perturbations.

It has long been reported that a range of prosthesis alignments is acceptable in trans-tibial prosthetics. This range was shown to be smaller when walking on uneven surfaces. It has also been argued that findings on gait with prostheses that were obtained under laboratory conditions are limited in their applicability to real-life environments. This study investigated the hypothesis that efforts to compensate for suboptimal alignments by active users of trans-tibial prostheses become less effective when levels of physical exertion increase. A 2 × 2 repeated-measures analysis of variance was conducted to compare the effects of physical exertion and subtle alignment perturbations on gait with trans-tibial prostheses. The gait of eight subjects with trans-tibial amputation was analyzed when walking with two different prosthesis alignments and two different physical exertion levels. The main and interaction effects were statistically evaluated. Bilateral step length symmetry and measures of step variability within the same leg were found to be affected by the intervention. There was no significant effect on index variables that combined kinematic or kinetic measures. Findings showed that persons with trans-tibial prostheses responded heterogeneously to the interventions. For most variables, the research hypothesis could not be confirmed. Findings support the practice of allotting several sessions to the alignment of trans-tibial prostheses, as users' gait responds differently to perturbations when external factors (e.g. exertion) change. Furthermore, the found inhomogeneity in the population of persons with trans-tibial amputation supports the use of technical gait assessment methods in clinical practice.

Dynamic alignment of transtibial prostheses through visualization of socket reaction moments

Dynamic alignment of transtibial prostheses is generally performed based on visual interpretation of gait without the benefit of any kinetic analysis in the clinic. The aim of this technical note was to present and discuss the possibilities of assisting dynamic alignment of transtibial prostheses through visualization of socket reaction moments. Smart Pyramid™ (currently Europa™) was used to measure the socket reaction moments under various alignment conditions from an amputee with transtibial prosthesis. The socket reaction moments were plotted to visualize the effect of alignment changes on them, and they were clinically interpreted. Socket reaction moments could complement information available to prosthetists to optimize prosthetic alignment. They could be used to reduce excessive loading on sensitive areas, to improve gait stability, or to communicate the outcome of dynamic alignment with the amputees. Further research is needed to identify the contribution of kinematics and kinetics for optimal alignment. Dynamic alignment of transtibial prostheses is currently tuned subjectively based on prosthetists' experiences and skills. Socket reaction moments may potentially provide objective information for prosthetists to align transtibial prostheses in the clinic.

Individual responses to alignment perturbations in socket reaction moments while walking in transtibial prostheses

BackgroundThe alignment of transtibial prostheses has a systematic effect on the mean socket reaction moments in amputees. However, understanding their individual differences in response to alignment perturbations is also important for prosthetists to fully utilize the socket reaction moments for dynamic alignment in each unique patient. The aim of this study was to investigate individual responses to alignment perturbations in transtibial prostheses with solid-ankle-cushion-heel feet. MethodsA custom instrumented prosthesis alignment component was used to measure the socket reaction moments while walking in 11 amputees with transtibial prostheses under 17 alignment conditions, including 3° and 6° of flexion, extension, abduction, and adduction of the socket, 5mm and 10mm of anterior, posterior, lateral, and medial translation of the socket, and an initial baseline alignment. Coronal moments at 30% of stance and maximum sagittal moments were extracted for comparisons from each amputee. FindingsIn the coronal plane, varus moment at 30% of stance was generally reduced by adduction or medial translation of the socket in all the amputees. In the sagittal plane, extension moment was generally increased by posterior translation or flexion of the socket; however, this was not necessarily the case for all the amputees. InterpretationsIndividual responses to alignment perturbations are not always consistent, and prosthetists would need to be aware of this variance when addressing individual socket reaction moments during dynamic alignment in clinical setting.

The influence of computer-assisted surgery on rotational, coronal and sagittal alignment in revision total knee arthroplasty

BackgroundDespite good results of primary total knee arthroplasty (TKA), the number of revision total knee arthroplasties (rTKAs) is rising. Proper implant position is essential, since malposition leads to worse clinical outcome. In rTKA most anatomical landmarks have disappeared because of extensive bone loss, making it more difficult to adequately implant the knee prosthesis. In primary TKA, computer-assisted surgery (CAS) leads to better prosthetic alignment than mechanical navigation guides. Literature about the use of CAS in rTKA is scarce though, and the effect on rotational prosthetic alignment has not been investigated yet. Hence the primary objective of this study is to compare rotational prosthetic alignment when using CAS in rTKA compared to a mechanical navigation guide. Secondary objectives are to compare prosthetic alignment in the coronal and sagittal planes. It is hypothesized that CAS leads to better rotational, coronal and sagittal prosthetic alignment when used during rTKA.Methods/DesignA prospective clinical intervention study with use of a historical control group will be conducted. Forty-four patients with a minimum age of 18 to be admitted for CAS-rTKA between September 2012 and September 2015 will be included in the intervention group. Forty-four patients with a minimum age of 18 who underwent rTKA with the use of a mechanical navigation guide between January 2002 and April 2012 will form the historical control group. Both groups will be matched according to gender and type of revision prosthesis. Rotational prosthesis alignment will be evaluated using a CT-scan of the knee joint.DiscussionProper implant position is essential, since malposition leads to worse clinical outcome. Several studies show a significantly positive influence of CAS on prosthetic alignment in primary TKA, but literature about the use of CAS in rTKA is limited. The purpose of this study is thus to investigate the influence of CAS during rTKA on postoperative prosthetic alignment, compared to mechanical navigation guides.Trial registrationNetherlands National Trial Register NTR3512

Effect of prosthetic alignment changes on socket reaction moment impulse during walking in transtibial amputees

The alignment of a lower limb prosthesis affects the way load is transferred to the residual limb through the socket, and this load is critically important for the comfort and function of the prosthesis. Both magnitude and duration of the moment are important factors that may affect the residual limb health. Moment impulse is a well-accepted measurement that incorporates both factors via moment–time integrals. The aim of this study was to investigate the effect of alignment changes on the socket reaction moment impulse in transtibial prostheses. Ten amputees with transtibial prostheses participated in this study. The socket reaction moment impulse was measured at a self-selected walking speed using a Smart Pyramid™ in 25 alignment conditions, including a nominal alignment (clinically aligned by a prosthetist), as well as angle malalignments of 2°, 4° and 6° (abduction, adduction, extension and flexion) and translation malalignments of 5mm, 10mm and 15mm (lateral, medial, anterior and posterior). The socket reaction moment impulse of the nominal alignment was compared for each condition. The relationship between the alignment and the socket reaction moment impulse was clearly observed in the coronal angle, coronal translation and sagittal translation alignment changes. However, this relationship was not evident in the sagittal angle alignment changes. The results of this study suggested that the socket reaction moment impulse could potentially serve as a valuable parameter to assist the alignment tuning process for transtibial prostheses. Further study is needed to investigate the influence of the socket reaction moment impulse on the residual limb health.

New socket-less prosthesis concept facilitating comfortable and abrasion-free cycling after Van Nes rotationplasty

Current leg prostheses in rotationplasty typically feature a thigh cuff, which, in cycling, may cause perspiration problems and friction-related abrasions of the skin. The aim has been to develop a socket-less prosthetic device for persons with a rotationplasty to be able to engage in high-intensity cycling without contracting abrasions. The new device (Socket-Less Rotationplasty Prosthesis for Cycling) features a standard cycling shoe on the rotationplasty foot, replacing the conventional socket and thigh cuff. A reinforced 12-layer carbon fibre frame bolted to the aforementioned shoe, replacing the standard tube, connects to a prosthetic foot and a second cycling shoe. Alignment of the Socket-Less Rotationplasty Prosthesis for Cycling is done both statically and dynamically. The Socket-Less Rotationplasty Prosthesis for Cycling is lightweight and more ventilated relative to conventional sockets. All components can be replaced easily. Most important, however, is that the current user now can cycle 135 km on end without skin abrasions. The Socket-Less Rotationplasty Prosthesis for Cycling concept enables patients with a leg rotationplasty to engage in high-intensity cycling without contracting skin problems, thereby facilitating clients' participation.

The Rotaglide mobile-bearing total knee arthroplasty: no difference between cemented and hybrid implantation

The optimal fixation of the Rotaglide total knee arthroplasty's (TKA) components is controversial. It is hypothesized that the hybrid fixation (cementless femoral component) in a mobile-bearing TKA system might cause increased rate of loosening--especially in the femoral part--and finally failure of the arthroplasty. Consequently, the aim of this study was to compare the survival and revision rates and also the clinical and radiological outcomes of the cemented and hybrid fixation of the Rotaglide TKA. One hundred patients, who underwent TKA with the Rotaglide prosthesis, were randomly placed in two groups. In the first group, the prosthesis was cemented, and in the second group, the hybrid technique was used. Revision and mortality rates were compared after 8-12 years of follow-up. Knee and Osteoarthritis Outcome Score (KOOS) questionnaire and the Knee Society Roentgenographic Evaluation and Scoring System were used to demonstrate clinical and radiographic differences. There were no statistically significant differences in revision (n.s.) or mortality (n.s.) rates between the two treatment arms. The clinical outcome at the time of last follow-up (mean 9.5 years, SD ± 1.4) ranged from very good to excellent (77.8 ± 17.5 for the cemented group and 77.2 ± 20.4 for the hybrid group). No statistically significant differences in all KOOS subscales. Radiographs showed no significant difference in prosthesis alignment and no evidence of loosening between groups. The hypothesis that the hybrid fixation in a mobile-bearing TKA system might cause increased rate of loosening and finally failure of the arthroplasty was not confirmed. The fixation technique (cemented or hybrid) had no influence on the prosthesis's survivorship, and also on mortality rates, clinical and radiographic outcomes in a mean follow-up time of 9.5 ± 1.4 years. The Rotaglide TKA is a safe and reliable prosthesis regardless the fixation technique.

Accuracy of patient specific cutting blocks in total knee arthroplasty.

Background. Long-term survival of total knee arthroplasty (TKA) is mainly determined by optimal positioning of the components and prosthesis alignment. Implant positioning can be optimized by computer assisted surgery (CAS). Patient specific cutting blocks (PSCB) seem to have the potential to improve component alignment compared to the conventional technique and to be comparable to CAS. Methods. 113 knees were selected for PSI and included in this study. Pre- and postoperative mechanical axis, represented by the hip-knee-angle (HKA), the proximal tibial angle (PTA), the distal femoral angle (DFA), and the tibial slope (TS) were measured and the deviation from expected ideal values was calculated. Results. With a margin of error of ±3°, success rates were 81.4% for HKA, 92.0% for TPA, and 94.7% for DFA. With the margin of error for alignments extended to ±4°, we obtained a success rate of 92.9% for the HKA, 98.2% for the PTA, and 99.1% for the DFA. The TS showed postoperative results of 2.86 ± 2.02° (mean change 1.76 ± 2.85°). Conclusion. PSCBs for TKA seem to restore the overall leg alignment. Our data suggest that each individual component can be implanted accurately and the results are comparable to the ones in CAS.

A-25 競技力の高い下腿切断者スプリンターにおける走行用義足のアライメント変化が地面反力に与える影響(パラリンピック2)

A-25 競技力の高い下腿切断者スプリンターにおける走行用義足のアライメント変化が地面反力に与える影響(パラリンピック2)

The use of a robotic gait simulator for the development of an alignment tool for lower limb prostheses

Background This tool meets the demand of prosthetists to optimise and objectify the dynamic alignment of transtibial prostheses. Nowadays, the prosthetists mainly rely on their own expertise and experience. Current methods to align the prosthesis start with a static alignment of transtibial prosthesis. This method does not take the individual patient comfort into account. Afterwards, adjustments to the alignment are done by trial and error. This is a time-consuming and exhausting activity for both prosthetist and patient.

Effect of alignment changes on socket reaction moments while walking in transtibial prostheses with energy storage and return feet

BackgroundEnergy storage and return feet are designed for active amputees. However, little is known about the socket reaction moments in transtibial prostheses with energy storage and return feet. The aim of this study was to investigate the effect of alignment changes on the socket reaction moments during gait while using the energy storage and return feet. MethodsA Smart Pyramid™ was used to measure the socket reaction moments in 10 subjects with transtibial prostheses while walking under 25 alignment conditions, including a nominal alignment (as defined by conventional clinical methods), as well as angle malalignments of 2°, 4° and 6° (flexion, extension, abduction, and adduction) and translation malalignments of 5mm, 10mm and 15mm (anterior, posterior, lateral, and medial) referenced from the nominal alignment. The socket reaction moments of the nominal alignment were compared with each malalignment. FindingsBoth coronal and sagittal alignment changes demonstrated systematic effects on the socket reaction moments. In the sagittal plane, angle and translation alignment changes demonstrated significant differences (P<0.05) in the minimum moment, the moment at 45% of stance and the maximum moment for some comparisons. In the coronal plane, angle and translation alignment changes demonstrated significant differences (P<0.05) in the moment at 30% and 75% of stance for all comparisons. InterpretationThe alignment may have systematic effects on the socket reaction moments in transtibial prostheses with energy storage and return feet. The socket reaction moments could potentially be a useful biomechanical parameter to evaluate the alignment of the transtibial prostheses.

The relationship between the survival of total knee arthroplasty and postoperative coronal, sagittal and rotational alignment of knee prosthesis

Our study sought to address four issues: (1) the relationship between postoperative overall anatomical knee alignment and the survival of total knee prostheses; (2) the relationship between postoperative coronal alignment of the femoral and tibial component and implant survival; (3) the relationship between postoperative sagittal alignment of the femoral and tibial components and implant survival; and (4) the relationship between postoperative rotational alignment of the femoral and tibial component and implant survival. We reviewed 1,696 consecutive patients (3,048 knees). Radiographic and computed tomographic examinations were performed to determine the alignment of the femoral and tibial components. The mean duration of follow-up was 15.8 years (range, 11-18 years). Thirty (1.0%) of the 3,048 total knee arthroplasties failed for a reason other than infection and periprosthetic fracture. Risk factors for failure of the components were: overall anatomical knee alignment less than 3° valgus, coronal alignment of the femoral component less than 2.0° valgus, flexion of the femoral component greater than 3°, coronal alignment of the tibial component less than 90°, sagittal alignment of the tibial component less than 0° or greater than 7° slope, and external rotational alignment of the femoral and tibial components less than 2° In order to improve the survival rate of the knee prosthesis, we believe that a surgeon should aim to place the total knee components in the position of: overall anatomical knee alignment at an angle of 3-7.5° valgus; femoral component alignment, 2-8.0° valgus; femoral sagittal alignment, 0-3°; tibial coronal alignment, 90°; tibial sagittal alignment, 0-7°; femoral rotational alignment, 2-5° external rotation; and tibial rotational alignment, 2-5° external rotation.

Effect of alignment changes on socket reaction moments during gait in transfemoral and knee-disarticulation prostheses: Case series

The alignment of a lower-limb prosthesis is critical to the successful prosthetic fitting and utilization by the wearer. Loads generated by the socket applied to the residual limb while walking are thought to be different in transfemoral and knee-disarticulation prostheses. The aim of this case series was to compare the socket reaction moments between transfemoral and knee-disarticulation prostheses and to investigate the effect of alignment changes on them. Two amputees, one with a transfemoral prosthesis and another with a knee-disarticulation prosthesis, participated in this study. A Smart Pyramid™ was used to measure socket reaction moments while walking under 9 selected alignment conditions; including nominally aligned, angle malalignments of 6° (flexion, extension, abduction and adduction) and translation malalignments of 15mm (anterior, posterior, medial and lateral) of the socket relative to the foot. This study found that the pattern of the socket reaction moments was similar between transfemoral and knee-disarticulation prostheses. An extension moment in the sagittal plane and a varus moment in the coronal plane were dominant during stance under the nominally aligned condition. This study also demonstrated that alignment changes might have consistent effects on the socket reaction moments in transfemoral and knee-disarticulation prostheses. Extension and posterior translation of the socket resulted in increases in an extension moment, while abduction and lateral translation of the socket resulted in increases in a varus moment. The socket reaction moments may potentially serve as useful biomechanical parameters to evaluate alignment in transfemoral and knee-disarticulation prostheses.