Microprocessor Knee Research Articles

Effects of a low-cost prosthetic knee on amputee gait over uneven and even terrains.

Limited data are available related to using a low-cost prosthetic knee while walking. To address this gap, this study compared the performance of a low-cost prosthetic knee with 2 more advanced prosthetic knees while walking on even and uneven terrains. Two adult subjects with above-knee amputations completed walking trials using a low-cost prosthetic knee (ReMotion knee) and their personal prosthetic knees (Ottobock 3R60 Pro mechanical knee and Ossur Rheo microprocessor knee) over even and uneven terrains. Several measures of gait performance were obtained including step size, stability, energy expenditure, as well as user perception of ReMotion workload and performance during gait. Effects of the ReMotion knee were different between the mechanical and microprocessor knee user. In addition, subjects perceived the positive aspects associated with the ReMotion knee to be its lightweight feature and their perceived increased in stability during walking while both subjects disliked the inability of the ReMotion knee to adjust to preferred walking speeds. This study provided an understanding of low-cost prosthetic technology among lower-limb amputees compared to prosthetic technology with more technologically advanced assistance. These findings may help guide future low-cost prosthetic knee design considerations for use on various terrains.

Fuzzy Prosthesis

Artificial Intelligence AI and Machine Learning ML have paved the pathway for a brighter techy future in the field of Prosthetics by acting as a boon for Persons with DisabilityPeoples with Determination PwDs. Biomechanotronics is a branch of mechanotronics and involves four main units. This can be integrated with artificial intelligence for better results and user experiences. We have discussed microprocessor knee joint for better insight into this concept.

YouTube as a Source of Education and Information About Microprocessor Knee Prostheses

YouTube as a Source of Education and Information About Microprocessor Knee Prostheses

The Detection of Compensatory Movements in Gait by Evaluating Plantar Pressure in Transfemoral Amputees

Microprocessor-controlled prosthetic knees (MPKs) improve the safety and functional capabilities of transfemoral amputees, but there is a lack of information on plantar pressure distribution and effects among individuals who have undergone transfemoral amputation of the sound limb. (1) Background: The aim of this study was to determine possible compensatory mechanisms in gait by evaluating intact extremity foot plantar pressure distribution in young MPK prosthesis users. Twenty-one patients with unilateral transfemoral amputation (TFA) and twenty-four healthy individuals were selected for the study. (2) Methods: The WalkinSense system was used to assess different foot plantar pressure distribution parameters as the participants walked at their chosen walking speed. Plantar pressure peaks and activation percentages in the eight foot regions were measured during the gait cycle. (3) Results: The pressure peaks and activation percentages in the sound limb with TFA patients and healthy subjects were measured, and statistically significant differences between the two groups were identified. The 1-, 2-, 3-, 4-, and 6-point sensor activation percentages significantly increased, whereas the 7- and 8-point sensor activation percentages decreased in the sound limb TFA participants compared with the healthy subjects. Peak plantar pressure sensor points 1, 3, 4, and 6 increased in the TFA sound limb foot in relation to healthy individuals, while they decreased in point 8. (4) Conclusion: In this study, with the use of a microprocessor knee joint TF prosthesis, in the evaluation of the underfoot pressure of intact legs, the maximum pressure point shifted to the forefoot, and it was observed that the forefoot and midfoot were more active during walking compared with the control group. This may indicate that gait compensation and plantar flexion in the sound limb are used more forcefully in the gait cycle.

A pilot case series for concurrent validation of inertial measurement units to motion capture in individuals who use unilateral lower-limb prostheses.

Inertial measurement units (IMUs) may be viable options to collect gait data in clinics. This study compared IMU to motion capture data in individuals who use unilateral lower-limb prostheses. Participants walked with lower-body IMUs and reflective markers in a motion analysis space. Sagittal plane hip, knee, and ankle waveforms were extracted for the entire gait cycle. Discrete points of peak flexion, peak extension, and range of motion were extracted from the waveforms. Stance times were also extracted to assess the IMU software's accuracy at detecting gait events. IMU and motion capture-derived data were compared using absolute differences and root mean square error (RMSE). Five individuals (n = 3 transtibial; n = 2 transfemoral) participated. IMU prosthetic limb data was similar to motion capture (RMSE: waveform ≤4.65°; discrete point ≤9.04°; stance ≤0.03s). However, one transfemoral participant had larger differences at the microprocessor knee joint (RMSE: waveform ≤15.64°; discrete ≤29.21°) from IMU magnetometer interference. Intact limbs tended to have minimal differences between IMU and motion capture data (RMSE: waveform ≤6.33°; discrete ≤9.87°; stance ≤0.04s). Findings from this pilot study suggest IMUs have the potential to collect data similar to motion capture systems in sagittal plane kinematics and stance time.

Creating Adjusted Scores Targeting mobiLity Empowerment (CASTLE 1): determination of normative mobility scores after lower limb amputation for each year of adulthood

Purpose As United States healthcare transitions from traditional fee-for-service models to value-based care, there is increased need to demonstrate quality care through clinical outcomes. Therefore, the purpose of this study was to create equations to calculate an expected mobility score for lower limb prosthesis users specific to their age, etiology, and amputation level to provide benchmarks to qualify good outcomes. Materials and Methods A retrospective cross-sectional analysis of outcomes collected during clinical care was performed. Individuals were grouped based on amputation level (unilateral above-knee (AKA) or below-knee (BKA)) and etiology (trauma or diabetes/dysvascular (DV)). The mean mobility score (PLUS-M® T-score) for each year of age was calculated. AKAs were further stratified into having a microprocessor knee (MPK) or non-microprocessor (nMPK) for secondary analysis. Results As expected, average prosthetic mobility declined with age. Overall, BKAs had higher PLUS-M T-scores compared to AKAs and trauma etiologies had higher scores compared to DV. For AKAs, those with a MPK had higher T-scores compared to those with a nMPK. Conclusions Results from this study provide average mobility for adult patients across every year of life. This can be leveraged to create a mobility adjustment factor to qualify good outcomes in lower limb prosthetic care. IMPLICATIONS FOR REHABILITATION Normative values of mobility are needed to qualify good outcomes in prosthetic care as healthcare shifts towards value-based care. Understanding where an individual is relative to others with similar characteristics (e.g., age, etiology, gender, amputation level, and device type) can provide clinicians with better benchmarks for individual goal-setting. The ability to generate predicted mobility scores specific to each individual can create a mobility adjustment factor to better qualify good outcomes.

Effect of slope in an immersive virtual environment on segmental asymmetry in people with femoral amputation and a microprocessor knee

Purpose The continued development of microprocessor-based knee prostheses has improved the independence of people with a femoral amputation in many environments. This study aimed to describe the effect of slopes on kinematic joint variables and segmental asymmetry. Methods Ten individuals with transfemoral amputation fitted with microprocessor-controlled knees performed 5 sessions of treadmill walking at their preferred speed in an immersive virtual environment in 5 incline conditions (Level, 3° and 6° Uphill, and 3° and 6° Downhill). The Human Body Model was used to quantify kinematic joint variables from motion capture system data. The perimeter-to-area method was used to determine the symmetry ratio of the trajectory of the leg segments in the sagittal plane Results There was a significant effect of the Uphill conditions on step length and width on the intact side and on all kinematic joint variables on both sides, although the changes differed according to the phase of the gait cycle. The segmental symmetry index was significantly modified in all slope conditions compared with Level. Conclusions Kinematic joint variables are affected by slopes; the effect was greater for the Uphill than Downhill conditions compared with the Level condition. The perimeter-to-area symmetry ratio differed from the Level condition for all slope conditions. These results indicate that, although microprocessor knees improve the autonomy of prosthesis users, work is required to improve their capacity of adaptation to varied terrain to reduce kinematic asymmetry.

The effects of swing assistance in a microprocessor-controlled transfemoral prosthesis on walking at varying speeds and grades.

This article proposes, describes, and tests a swing-assist walking controller for a stance-controlled, swing-assisted knee prosthesis that aims to combine benefits of passive swing mechanics (e.g., quiet operation, biomimetic function, and low power requirements) with benefits of powered swing assistance (e.g., increased robustness of swing-phase motion and specifically increased toe clearance). A three-participant, multislope, multispeed treadmill walking study was performed using the swing-assist prosthesis and controller, as well as using the participants' prescribed microprocessor knee devices. The swing-assist device and approach were found to improve user minimum foot clearance during walking at slopes and speeds, and also to improve symmetry of knee motion. Hip power inputs from stance knee release to heel strike indicated that, on average, less hip power was required when using the swing-assist prosthesis, indicating that the observed benefits were likely the result of the knee device and its control methodology, rather than a result of increased hip joint effort.

How does ankle power on the prosthetic side influence loading parameters on the sound side during level walking of persons with transfemoral amputation?

Background:Increased ankle power on the prosthetic side seems to decrease biomechanical loading parameters on the sound side. This assumption is based on biomechanical comparisons of different foot constructions. However, such study designs could not show whether the amount of ankle power solely influences the sound side.Objective:To analyze the influence of divergent ankle power, resulting from different foot constructions and from different ankle power settings, on the sound side loading parameters.Study design:Interventional cross sectional study.Methods:Level walking of transfemoral amputees with a microprocessor knee joint and Solid Ankle Cushioned Heel (SACH), energy storing and returning (ESR) and powered foot (PF) was analyzed. The PF was adapted in three configurations: without power (np), low power (lp), and optimal power (op). An optoelectronic camera system with 12 cameras and two force plates were used.Results:The ankle power on the prosthetic side shows significant differences about foot types and different settings of the PF. The knee adduction moment, the knee flexion moment, and the vertical ground reaction forces on the sound side were significantly reduced with PF_op and ESR in comparison to SACH. When analyzing these parameters for the different PF configurations, only some show significant results at normal velocity.Conclusions:The additional positive mechanical work for an active push off in the PF tends to have a relieving effect. The biomechanical sound side loading parameters are reduced with PF_op in comparison to SACH and ESR, resulting in a relief of the sound side of lower limb amputees.

Microprocessor knee versus non-microprocessor knee for backup device in lower limb prostheses: A qualitative study

LAY SUMMARY Current policy in the Canadian Armed Forces (CAF) and Veterans Affairs Canada (VAC) is to provide individuals with an amputation through or above the knee with a prosthesis with a microprocessor knee (MPK) unit for daily use and a backup prosthesis with a non-microprocessor knee (N-MPK) unit. These knee units have significant functional differences. The purpose of this study was to gain an understanding of users’ device preference and the impact of switching between the MPK and N-MPK. To study this, six members participated in semi-structured interviews. Analysis found seven major categories driving prosthetic preference: functionality, physical aspects, mental aspects, activity, maintenance, safety, and health-related quality of life. The MPK was superior in all categories, and immediate switching between devices was problematic. As a result, participants who had an N-MPK backup did not use the device and instead received a loaner MPK from their prosthetist when required. These results suggest that for individuals who do not have ready access to their prosthetist to obtain a loaner knee unit, consideration should be given for a backup prosthesis with the same MPK unit as their daily-use prosthesis. Otherwise, no routine need for a backup N-MPK was identified.

Effects of walking speed and prosthetic knee control type on external mechanical work in transfemoral prosthesis users

During human locomotion, each limb performs step-to-step work on the body center of mass to maintain forward walking. This energy exchange relies on physiological mechanisms which are altered or impaired in transfemoral prosthesis users (TFPUs). Exploring step-to-step energy exchange modifications displayed by TFPUs at greater walking speeds may provide insight into their means for improving gait efficiency. The primary aim of this study was to characterize the effects of walking speed on mechanical work in unilateral TFPUs. The secondary aim assessed the effect of prosthetic knee (microprocessor, mechanical passive) on limb collision work. Twenty-five TFPUs walked with their customary prosthesis on a split-belt instrumented treadmill at eight speeds (0.55–1.53 m/s range), and collision, midstance, and push-off work were calculated for each limb. TFPUs displayed a significant (p < 0.001) bilateral increase in collision work with increased walking speed, but midstance and push-off work increased only for the sound limb and remained nearly constant for the prosthetic limb. TFPUs displayed significantly (p < 0.001) less push-off work generated by the prosthetic limb across all speeds. A microprocessor knee was associated with reduced sound limb collision work across speeds with the peak (negative) power being significantly greater for mechanical knees (p = 0.032). Results suggest that TFPU gait inefficiency may be related to a near complete loss of energy transfer on the prosthetic limb, relying on the sound limb to drive energy changes. Such reliance emphasizes need for attention to the long-term effects on sound limb health and possible benefit of microprocessor knees to offset that impact.

Design and Initial Evaluation of a Low-Cost Microprocessor-Controlled Above-Knee Prosthesis: A Case Report of 2 Patients

For prosthesis users, knee units can range from simple devices costing $2000 up to $45,000 for high-end, microprocessor-controlled systems. These higher-end electronic knees provide significant advantages in stability, gait, and metabolic rate compared to their passive or mechanical counterparts. However, the high cost of such systems makes them inaccessible to most amputees. In this study, it was hypothesized that a microprocessor knee could be manufactured for less than $1000, with comparable stability and user experience to a high-end industry standard device. A prototype (E-Knee) was designed with a specific emphasis on stance stability, and was tested during patient gait trials. The gait trials used a repeated measures design to compare three knee devices (a simple passive knee, the prototype E-Knee, and a high-end knee). Ground reaction forces and a functionality questionnaire were used to compare devices. A microprocessor locking test was used to evaluate the prototype’s ability to prevent falls. Building on the LIMBS M3, a passive four-bar polycentric device, the E-Knee added sensing, computing, and controlling capabilities for a material cost of $507. Initial data from a two-subject trial served as proof-of-concept to validate the prototype and found that it improved gait by providing more stability than the M3 and had more gait-pattern similarities to the Ottobock C-Leg than to the M3. Patients reported no perceived differences in stability between the E-Knee and the C-Leg. Patient trials supported that the E-Knee prototype behaved more naturally than the low-end M3 device and had similar ground reaction forces to the C-Leg.

A Retrospective Review of Psychosocial Outcomes After Microprocessor Knee Prescription

ABSTRACT Introduction Microprocessor knees have been shown to improve gait biomechanics and to reduce the frequency of falls, but evidence of their influence on psychosocial health is limited. Study Design Retrospective analysis. Objective The aim of this study was to evaluate the change in psychosocial outcome measures when prosthetic users change from a non–microprocessor-controlled prosthetic knee (NMPK) to a microprocessor-controlled prosthetic knee (MPK). Methods Using validated outcome measures, physical and psychological attributes of 26 MPK users were analyzed using data collected at routine appointments. Baseline data were collected using NMPK limbs first, then compared with data collected 4 weeks and 6 months after initial MPK fitting. Results A significant improvement of 13.7% in Reintegration to Normal Living Index (RNLI) scores was observed after 6 months (P = 0.001). The Patient Health Questionnaire-9 (PHQ-9) demonstrated a 64.6% significant reduction in the presence of depression-like symptoms after 6 months of MPK use (P &lt; 0.001), including four participants who previously scored highly enough to be diagnosed with major depressive disorder. Frequency of falls reduced significantly as well (P &lt; 0.001). Increases in self-selected walking speed were seen in both the 2-minute walk and 6-minute walk tests. Conclusions Significant improvements were seen in all psychosocial outcome measures, indicating participants' psychosocial health improved with the prescription of an MPK despite a lack of clinically important improvements in parallel performance-based outcome measures. Clinical Relevance MPKs are well documented to reduce trips and falls, which is corroborated by this research. However, the psychosocial benefits of MPKs are not documented extensively; this study provides evidence of an improvement in psychological wellbeing in this cohort.

Stability and Falls Evaluations in AMPutees (SAFE-AMP 1): Microprocessor knee technology reduces odds of incurring an injurious fall for individuals with diabetic/dysvascular amputation

ABSTRACT Individuals with lower limb amputation have a high incidence of falls. Above-the-knee amputation and diabetes/vascular disease are both risk factors for falls. Microprocessor knee (MPK) technology may reduce falls in this population. The objective was to determine the association between MPKs and reduced injurious falls. A retrospective analysis of injurious falls within a large, national outcomes database was conducted. Inclusion was limited to adult K3 ambulators with unilateral, transfemoral, or knee disarticulation amputation due to diabetes/vascular disease. There were 744 out of 881 individuals that did not receive an MPK. Results showed that 16.3% of non-MPK users experienced an injurious fall compared to 7.3% of MPK users (p = .007). Not having an MPK resulted in significantly increased odds (unadjusted: OR: 2.47, 95% CI: 1.26–4.83, p = .009; adjusted for confounders: OR: 2.52, 95% CI: 1.28–4.94, p = .007) of incurring an injurious fall over a 6-month period. In conclusion, the current study found use of an MPK strongly associated with reduced injurious falls in a population of patients with amputation due to diabetes/vascular disease. The findings strongly support the use of MPK technology to mitigate fall risk, and in particular injurious falls requiring medical intervention.

Assessment of lower limb peripheral nerves with ultrasound in patients with traumatic amputation.

Objectives This study aims to assess the sciatic nerve (SN), common peroneal nerve (CPN), and tibial nerve (TN) by ultrasound in patients with traumatic lower limb amputation (LLA) and to examine the possible relationship between ultrasonographic and clinical findings. Patients and methods This cross-sectional study included a total of 33 male patients (mean age: 36.6±8.7 years; range, 21 to 48 years) who had LLA due to traumatic injury between May 2019 and April 2020. Amputation and prosthesis use and functional K level of activity were recorded. Ultrasound examinations were performed to measure the cross-sectional areas (CSAs) of the SN, CPN, and TN bilaterally at the same levels. The values from the normal sides were accepted as controls. Results The CSA values were greater on the amputated sides than the non-amputated sides for SN (p=0.001), TN (p=0.001), and CPN (p=0.015), regardless of the activity level. The amputated side SN (p=0.001), TN (p=0.001), and CPN (p=0.016) were thicker in patients with level of K4 activity than the non-amputated side. For the patients with K3 activity level, larger TN CSA values were determined on the amputated side, compared to those at the K4 level (p=0.035). The SN was found to be greater in patients using microprocessor-controlled knee prosthesis (p=0.032) and TN was larger in hypobaric sealing membrane users on the amputated sides (p=0.041). Conclusion The SN, CPN, and TN were found to be larger in all patients on the amputated sides and in patients with K4 activity level. Based on these findings, the K3 activity level and the use of hypobaric sealing membrane seems to affect the CSA values of TN. Additionally, the use of microprocessor knee prosthesis affects the CSA values of SN. We believe that these results may be essential for the analysis or prediction of lower extremity nerve involvement according to the K activity level and the use of prosthesis in patients with traumatic LLA.

Using a microprocessor knee (C-Leg) with appropriate foot transitioned individuals with dysvascular transfemoral amputations to higher performance levels: a longitudinal randomized clinical trial

BackgroundIndividuals with transfemoral amputations who are considered to be limited community ambulators are classified as Medicare functional classification (MFCL) level K2. These individuals are usually prescribed a non-microprocessor controlled knee (NMPK) with an appropriate foot for simple walking functions. However, existing research suggests that these individuals can benefit from using a microprocessor controlled knee (MPK) and appropriate foot for their ambulation, but cannot obtain one due to insurance policy restrictions. With a steady increase in older adults with amputations due to vascular conditions, it is critical to evaluate whether advanced prostheses can provide better safety and performance capabilities to maintain and improve quality of life in individuals who are predominantly designated MFCL level K2. To decipher this we conducted a 13 month longitudinal clinical trial to determine the benefits of using a C-Leg and 1M10 foot in individuals at K2 level with transfemoral amputation due to vascular disease. This longitudinal clinical trial incorporated recommendations prescribed by the lower limb prosthesis workgroup to design a study that can add evidence to improve reimbursement policy through clinical outcomes using an MPK in K2 level individuals with transfemoral amputation who were using an NMPK for everyday use.MethodsTen individuals (mean age: 63 ± 9 years) with unilateral transfemoral amputation due to vascular conditions designated as MFCL K2 participated in this longitudinal crossover randomized clinical trial. Baseline outcomes were collected with their current prosthesis. Participants were then randomized to one of two groups, either an intervention with the MPK with a standardized 1M10 foot or their predicate NMPK with a standardized 1M10 foot. On completion of the first intervention, participants crossed over to the next group to complete the study. Each intervention lasted for 6 months (3 months of acclimation and 3 months of take-home trial to monitor home use). At the end of each intervention, clinical outcomes and self-reported outcomes were collected to compare with their baseline performance. A generalized linear model ANOVA was used to compare the performance of each intervention with respect to their own baseline.ResultsStatistically significant and clinically meaningful improvements were observed in gait performance, safety, and participant-reported measures when using the MPK C-Leg + 1M10 foot. Most participants were able to achieve higher clinical scores in gait speed, balance, self-reported mobility, and fall safety, while using the MPK + 1M10 combination. The improvement in scores were within range of scores achieved by individuals with K3 functional level as reported in previous studies.ConclusionsIndividuals with transfemoral amputation from dysvascular conditions designated MFCL level K2 benefited from using an MPK + appropriate foot. The inference and evidence from this longitudinal clinical trial will add to the knowledgebase related to reimbursement policy-making.Trial registration This study is registered on clinical trials.gov with the study title “Functional outcomes in dysvascular transfemoral amputees” and the associated ClinicalTrials.gov Identifier: NCT01537211. The trial was retroactively registered on February 7, 2012 after the first participant was enrolled.

Comparison of patient-reported and functional outcomes following transition from mechanical to microprocessor knee in the low-activity user with a unilateral transfemoral amputation.

The Scottish Specialist Prosthetics Service has provided microprocessor knees (MPKs) through the National Health Service since 2014, predominantly to high-activity transfemoral amputations (TFAs). Benefits of MPKs to the lower-activity TFA are less established in the literature. This study aimed to compare patient-reported and functional measures in low-activity TFAs transitioning from a mechanical knee to a MPK. This is a retrospective cohort analysis of low-activity individuals with a unilateral TFA provided with an MPK. Patient-reported measures were recorded in routine clinical care before and 6 months after MPK provision. These included HR-QoL (EQ-5D-5L Health Index), Activities Balance Confidence score, Prosthetic Limb User Survey of Mobility, falls frequency, use of walking aids, and Socket Comfort Score. Functional measures included the two-minute walk test (2MWT), L-test, and Amputee Mobility Predictor score, and three-dimensional gait analysis was used to generate a Gait Profile Score (GPS). The primary outcomes were HR-QoL and GPS. Forty-five participants fulfilled the inclusion criteria. Thirty-one had pre-MPK and post-MPK measures, of which 15 had three-dimensional gait analysis. The mean age (n = 31) was 60 years (SD 11), and 68% were male. HR-QoL and GPS did not significantly improve with MPK provision (p = 0.014 and p = 0.019); Amputee Mobility Predictor score, L-Test, 2MWT, falls, and Activities Balance Confidence score showed a significant improvement with MPK provision (p < 0.001). Although no statistically significant change in the primary outcomes was measured, there were sufficient data to support MPK provision in low-activity prosthetic users with participants demonstrating improvements in balance, 2MWT, falls frequency, and confidence.

Response to: Letter to editor regarding: OASIS 1: Retrospective analysis of four different microprocessor knee types by Campbell etal.

Response to: Letter to editor regarding: OASIS 1: Retrospective analysis of four different microprocessor knee types by Campbell etal.

Instrumented Four Square Step Test in Adults with Transfemoral Amputation: Test-Retest Reliability and Discriminant Validity between Two Types of Microprocessor Knees.

Technology-based outcomes have recently been proposed to complement the standard Four Square Step Test (FSST) by providing a decomposition of the sequences and information about the stepping pattern. A test-retest study and a randomized crossover design have been used to determine immediate test-retest reliability and to assess discriminant validity, in persons with a unilateral transfemoral amputation, for the parameters computed by an instrumented version of the Four Square Step Test. Twenty adults, independent and unlimited community ambulators, with a unilateral transfemoral amputation, performed two Four Square Step Tests on a pressure mat first with a microprocessor knee, then, a few weeks later with another one. One of these prosthetic knees was acknowledged to be superior and to provide functional improvement. Test-retest, intraclass correlation coefficients and minimal detectable change at 95% confidence level were calculated for each variable. Paired samples t-tests were then used to identify differences between the two microprocessor knee systems. The test-retest reliability of most outcome measures was good to excellent. Few variables showed a systematic difference and a trend to improve between test 1 and test 2. When comparing both microprocessor knees, significant differences in the expected direction were observed, with interpretation in accordance with a functional improvement. Importantly, we highlighted that various strategies to improve the performance in the test might complexify the interpretation of the most detailed measurement. The instrumented Four Square Step test provides reliable measures with satisfactory test-retest reliability and discriminant validity in persons with unilateral transfemoral amputation.

OASIS 1: Retrospective analysis of four different microprocessor knee types.

IntroductionMicroprocessor knee analyses to date have been primarily limited to microprocessor knees as a category rather than comparisons across different models. The purpose of the current analysis was to compare outcomes from four common knee models.MethodsA retrospective analysis of clinical outcomes was performed. Outcomes for functional mobility, quality of life, satisfaction with amputee status, and injurious falls were compared. Specific knee types represented were C-Leg (Ottobock), Orion (Blatchford), Plié (Freedom Innovations), and Rheo (Össur).ResultsOutcomes from 602 individuals were included. No significant differences were noted for functional mobility (H = 2.91, p = 0.406) or satisfaction (H = 4.43, p = 0.219). For quality of life, differences existed for C-Leg versus Plié (p = 0.010). For injurious falls, C-Leg (χ2(1,137) = 10.99, p < 0.001) and Orion (χ2(1,119) = 4.34, p = 0.037) resulted in significantly reduced injurious falls compared to non-microprocessor knee users. C-Leg (H = 19.63, p < 0.001) and Plié (H = 14.04, p = 0.003) users saw declines with advanced aging.ConclusionsOur data indicate relative parity among the 4 microprocessor knees with regard to functional mobility and satisfaction. In contrast to mobility, neither satisfaction nor quality of life values reflected declines with aging. Finally, when compared to non-microprocessor knees, significant differences were observed across the microprocessor knee types in relation to the reduction of injurious falls.Keywords: MPK, mobility, quality of life, falls, amputee, outcomes