Microprocessor-controlled Prosthetic Knee Joint Research Articles

Effects of microprocessor-controlled prosthetic knees on self-reported mobility, quality of life, and psychological states in patients with transfemoral amputations.

This study aimed to determine the effects of the microprocessor-controlled prosthetic knee (MPK) joint on self-mobility, body perceptions, depression, and quality of life in patients with unilateral transfemoral amputations (TFAs). Thirty consecutive patients (28 males, mean age=38.5 years, age range=22-57) who had previously used non-MPKs and who were approved to use swing and stance phase-control MPKs were included in this 12-week clinical study. Before the MPK use and after the three-month follow-up, prosthetic use and locomotor capabilities were evaluated using the Houghton Scale and the Locomotor Capabilities Index (LCI-5), respectively. Body perception was assessed using the Amputee Body Image Scale (ABIS). The depressive symptoms and quality of life were evaluated using the Beck Depression Inventory (BDI) score and the 36-Item Short- Form Health Survey (SF-36), respectively. After MPK use, statistically significant ameliorations were observed in all outcome measures. The basic and advanced LCI-5 increased from 26.7±2.2 and 24.8±5.2 to 27.6±1.2 (p=0.007) and 27±2.1 (p=0.004), respectively. Houghton scores improved from 9±1 to 10.3±0.8 (p=0.000). The ABIS and BDI scores decreased from 43.2±10.9 and 5.7±6.6 to 37.1±8.9 (p=0.000) and 3.8±4.5 (p=0.015), respectively. Also, the SF-36 physical function and vitality subscales increased from 71.2±24.0 and 75.5±14.6 to 85.6±16.6 (p=0.001) and 81.7±14.1 (p=0.015), respectively. MPK use provides significant improvements in the locomotor capabilities, quality of life, and activities of daily living to patients with TFAs as well as improves their body image perceptions and depressive symptoms. Level III, Self controlled study.

RHEO KNEE: Microprocessor-controlled prosthetic knee joint with AI and MR actuator

RHEO KNEE: Microprocessor-controlled prosthetic knee joint with AI and MR actuator

Comparative biomechanical evaluation of two technologically different microprocessor-controlled prosthetic knee joints in safety-relevant daily-life situations.

Safety-relevant gait situations (walking on stairs and slopes, walking backwards, walking with small steps, simulated perturbations of swing phase extension) were investigated in a motion analysis laboratory with six unilateral transfemoral amputees using two different microprocessor-controlled prosthetic knee joints (Rheo Knee XC, C-Leg). A randomized crossover design was chosen. The study results imply that the performance and safety potential of a microprocessor-controlled knee joint can be associated with the individual control algorithms and the technological concepts that are implemented to generate motion resistances for controlling flexion and extension movements. When walking with small steps, advantages of the "default swing" concept used in the Rheo Knee XC were identified due to a highly reproducible swing phase release. However, when walking backwards, this concept may lead to an uncontrolled knee flexion which partly resulted in falls. When walking down stairs, walking on slopes or while recovering from a stumble after perturbations of the swing phase extension, the C-Leg demonstrated a reliable prosthetic side load-bearing capacity resulting in reduced loading on the residual body. In contrast, the Rheo Knee XC required increased compensatory movements of the remaining locomotor system in order to compensate for reduced load-bearing and safety reserves.

Reduced cortical brain activity with the use of microprocessor-controlled prosthetic knees during walking.

Individuals using a lower-limb prosthesis indicate that they need to concentrate on every step they take. Despite self-reports of increased cognitive demand, there is limited understanding of the link between cognitive processes and walking when using a lower-limb prosthesis. The objective was to assess cortical brain activity during level walking in individuals using different prosthetic knee components and compare them to healthy controls. It was hypothesized that the least activity would be observed in the healthy control group, followed by individuals using a microprocessor-controlled prosthetic knee and finally individuals using a non-microprocessor-controlled prosthetic knee. Cross-sectional study. An optical brain imaging system was used to measure relative changes in concentration of oxygenated and de-oxygenated haemoglobin in the frontal and motor cortices during level walking. The number of steps and time to walk 10 m was also recorded. The 6-min walk test was assessed as a measure of functional capacity. Individuals with a transfemoral or knee-disarticulation amputation, using non-microprocessor-controlled prosthetic knee ( n = 14) or microprocessor-controlled prosthetic knee ( n = 15) joints and healthy controls ( n = 16) participated in the study. A significant increase was observed in cortical brain activity of individuals walking with a non-microprocessor-controlled prosthetic knee when compared to healthy controls ( p < 0.05) and individuals walking with an microprocessor-controlled prosthetic knee joint ( p < 0.05). Individuals walking with a non-microprocessor-controlled prosthetic knee demonstrated an increase in cortical brain activity compared to healthy individuals. Use of a microprocessor-controlled prosthetic knee was associated with less cortical brain activity than use of a non-microprocessor-controlled prosthetic knee. Increased understanding of cognitive processes underlying walking when using different types of prosthetic knees can help to optimize selection of prosthetic components and provide an opportunity to enhance functioning with a prosthesis.

Perceived self-efficacy and specific self-reported outcomes in persons with lower-limb amputation using a non-microprocessor-controlled versus a microprocessor-controlled prosthetic knee

Purpose: To measure self-efficacy in a group of individuals who have undergone a lower-limb amputation and investigate the relationship between self-efficacy and prosthetic-specific outcomes including prosthetic use, mobility, amputation-related problems and global health. A second purpose was to examine if differences exist in outcomes based upon the type of prosthetic knee unit being used.Method: Cross-sectional study using the General Self-Efficacy (GSE) Scale and the Questionnaire for Persons with a Transfemoral Amputation (Q-TFA). Forty-two individuals participated in the study. Twenty-three used a non-microprocessor-controlled prosthetic knee joint (non-MPK) and 19 used a microprocessor-controlled prosthetic knee joint (MPK).Results: The study sample had quite high GSE scores (32/40). GSE scores were significantly correlated to the Q-TFA prosthetic use, mobility and problem scores. High GSE scores were related to higher levels of prosthetic use, mobility, global scores and negatively related to problem score. No significant difference was observed between individuals using a non-MPK versus MPK joints.Conclusions: Individuals with high self-efficacy used their prosthesis to a higher degree and high self-efficacy was related to higher level of mobility, global scores and fewer problems related to the amputation in individuals who have undergone a lower-limb amputation and were using a non-MPK or MPK knee.Implications for rehabilitationPerceived self-efficacy has has been shown to be related to quality of life, prosthetic mobility and capability as well as social activities in daily life.Prosthetic rehabilitation is primary focusing on physical improvement rather than psychological interventions.More attention should be directed towards the relationship between self-efficacy and prosthetic related outcomes during prosthetic rehabilitation after a lower-limb amputation.

Measures and procedures utilized to determine the added value of microprocessor-controlled prosthetic knee joints: a systematic review

BackgroundThe effectiveness of microprocessor-controlled prosthetic knee joints (MPKs) has been assessed using a variety of outcome measures in a variety of health and health-related domains. However, if the patient is to receive a prosthetic knee joint that enables him to function optimally in daily life, it is vital that the clinician has adequate information about the effects of that particular component on all aspects of persons’ functioning. Especially information concerning activities and participation is of high importance, as this component of functioning closely describes the person’s ability to function with the prosthesis in daily life. The present study aimed to review the outcome measures that have been utilized to assess the effects of microprocessor-controlled prosthetic knee joints (MPK), in comparison with mechanically controlled prosthetic knee joints, and aimed to classify these measures according to the components and categories of functioning defined by the International Classification of Functioning, Disability and Health (ICF). Subsequently, the gaps in the scientific evidence regarding the effectiveness of MPKs were determined.MethodsA systematic literature search in 6 databases (i.e. PubMed, CINAHL, Cochrane Library, Embase, Medline and PsychInfo) identified scientific studies that compared the effects of using MPKs with mechanically controlled prosthetic knee joints on persons’ functioning. The outcome measures that have been utilized in those studies were extracted and categorized according to the ICF framework. Also, a descriptive analysis regarding all studies has been performed.ResultsA total of 37 studies and 72 outcome measures have been identified. The majority (67%) of the outcome measures that described the effects of using an MPK on persons’ actual performance with the prosthesis covered the ICF body functions component. Only 31% of the measures on persons’ actual performance investigated how an MPK may affect performance in daily life. Research also typically focused on young, fit and active persons.ConclusionsScientifically valid evidence regarding the performance of persons with an MPK in everyday life is limited. Future research should specifically focus on activities and participation to increase the understanding of the possible functional added value of MPKs.

Literature Review of Published Research Investigating Microprocessor-Controlled Prosthetic Knees

Since 2009, several articles on microprocessor-controlled prosthetic knee (MPK) joint mechanisms have been published. Recent published data are generally rated as providing moderate to low levels of evidence because of structural weakness of the study designs. These weaknesses are due to low statistical power, a lack of blinding, industry funding, precise measures with no estimate of minimal clinically important difference (MCID), or subjective participant responses on questionnaires. Strong support for the advantages of MPKs is not available within this cohort of studies. Statistically significant improvements were observed in some gait measures when comparing MPKs with non-MPKs (NMPKs), but the values are not close to those of intact individuals. For measures of gait kinematics, gait kinetics, gait parameters, gait symmetry, or performance time, MPKs seem to offer marginal improvements over NMPKs in a few measures. There are few data and information on the differences between the types of MPKs currently on the market. Several of the articles in this review do provide novel outcome measures that incorporate multiple domains in biomechanics, function, and patient perception. The strongest metric in all studies is patient preference for MPKs, as opposed to technical gait metrics, objective functional improvements in mobility, or the activity of prosthetic users. This patient preference might easily be influenced by marketing or design appeal rather than objective technical or functional outcome measures. Although MPKs seem to produce minor improvements in some aspects of gait over NMPKs, the cost-benefit ratio of MPKs is not available.

Biomechanical study on the functional performance of a new microprocessor-controlled prosthetic knee joint

Biomechanical study on the functional performance of a new microprocessor-controlled prosthetic knee joint

Immediate Effects of a New Microprocessor-Controlled Prosthetic Knee Joint: A Comparative Biomechanical Evaluation

Bellmann M, Schmalz T, Ludwigs E, Blumentritt S. Immediate effects of a new microprocessor-controlled prosthetic knee joint: a comparative biomechanical evaluation. ObjectiveTo investigate the immediate biomechanical effects after transition to a new microprocessor-controlled prosthetic knee joint. DesignIntervention cross-over study with repeated measures. Only prosthetic knee joints were changed. SettingMotion analysis laboratory. ParticipantsMen (N=11; mean age ± SD, 36.7±10.2y; Medicare functional classification level, 3–4) with unilateral transfemoral amputation. InterventionsTwo microprocessor-controlled prosthetic knee joints: C-Leg and a new prosthetic knee joint, Genium. Main Outcome MeasuresStatic prosthetic alignment, time-distance parameters, kinematic and kinetic parameters, and center of pressure. ResultsAfter a half-day training and an additional half-day accommodation, improved biomechanical outcomes were demonstrated by the Genium: lower ground reaction forces at weight acceptance during level walking at various velocities, increased swing phase flexion angles during walking on a ramp, and level walking with small steps. Maximum knee flexion angle during swing phase at various velocities was nearly equal for Genium. Step-over-step stair ascent with the Genium knee was more physiologic as demonstrated by a more equal load distribution between the prosthetic and contralateral sides and a more natural gait pattern. When descending stairs and ramps, knee flexion moments with the Genium tended to increase. During quiet stance on a decline, subjects using Genium accepted higher loading of the prosthetic side knee joint, thus reducing same side hip joint loading as well as postural sway. ConclusionsIn comparision to the C-Leg, the Genium demonstrated immediate biomechanical advantages during various daily ambulatory activities, which may lead to an increase in range and diversity of activity of people with above-knee amputations. Results showed that use of the Genium facilitated more natural gait biomechanics and load distribution throughout the affected and sound musculoskeletal structure. This was observed during quiet stance on a decline, walking on level ground, and walking up and down ramps and stairs.

Stair ascent with an innovative microprocessor-controlled exoprosthetic knee joint

Climbing stairs can pose a major challenge for above-knee amputees as a result of compromised motor performance and limitations to prosthetic design. A new, innovative microprocessor-controlled prosthetic knee joint, the Genium, incorporates a function that allows an above-knee amputee to climb stairs step over step. To execute this function, a number of different sensors and complex switching algorithms were integrated into the prosthetic knee joint. The function is intuitive for the user. A biomechanical study was conducted to assess objective gait measurements and calculate joint kinematics and kinetics as subjects ascended stairs. Results demonstrated that climbing stairs step over step is more biomechanically efficient for an amputee using the Genium prosthetic knee than the previously possible conventional method where the extended prosthesis is trailed as the amputee executes one or two steps at a time. There is a natural amount of stress on the residual musculoskeletal system, and it has been shown that the healthy contralateral side supports the movements of the amputated side. The mechanical power that the healthy contralateral knee joint needs to generate during the extension phase is also reduced. Similarly, there is near normal loading of the hip joint on the amputated side.

Influence of advanced prosthetic knee joints on perceived performance and everyday life activity level of low-functional persons with a transfemoral amputation or knee disarticulation

To assess the effects of two types of microprocessor-controlled prosthetic knee joints (MPKs) on perceived performance and everyday life activity level. Randomized cross-over trial. Thirty persons with a unilateral above-knee amputation or knee disarticulation classified as Medicare Functional Classification Level-2. Participants were measured in 3 conditions, i.e. using a mechanically controlled prosthesis, an MPK featuring a microprocessor-controlled stance and swing phase (MPKA), and an MPK featuring a microprocessor-controlled stance phase (MPKB). Subjects' perceived performance regarding prosthesis use was measured with the Prosthesis Evaluation Questionnaire. Subjects' activity level was quantified using accelerometry. As high within-group variability regarding subjects' functional performance was expected to impede detection of possible effects of an MPK, data were analysed for the total group and for 3 subgroups of participants. Participants' perception regarding ambulation, residual limb health, utility, and satisfaction with walking were significantly higher in the MPKA condition compared with the mechanical knee joint condition. Participants' activity level was similar in all knee joint conditions. Although Medicare Functional Classification Level-2 amputees report benefitting in terms of their performance from using an MPK, this is not reflected in their actual daily activity level after one week of using an MPK.

Functional added value of microprocessor-controlled knee joints in daily life performance of Medicare Functional Classification Level-2 amputees

To assess the effects of using a microprocessor-controlled prosthetic knee joint on the functional performance of activities of daily living in persons with an above-knee leg amputation. To assess the effects of using a microprocessor-controlled prosthetic knee joint on the functional performance of activities of daily living in persons with an above-knee leg amputation. Randomised cross-over trial. Forty-one persons with unilateral above-knee or knee disarticulation limb loss, classified as Medicare Functional Classification Level-2 (MFCL-2). Participants were measured in 3 conditions, i.e. using a mechanically controlled knee joint and two types of microprocessor-controlled prosthetic knee joints. Functional performance level was assessed using a test in which participants performed 17 simulated activities of daily living (Assessment of Daily Activity Performance in Transfemoral amputees test). Performance time was measured and self-perceived level of difficulty was scored on a visual analogue scale for each activity. High levels of within-group variability in functional performance obscured detection of any effects of using a microprocessor-controlled prosthetic knee joint. Data analysis after stratification of the participants into 3 subgroups, i.e. participants with a "low", "intermediate" and "high" functional mobility level, showed that the two higher functional subgroups performed significantly faster using microprocessor-controlled prosthetic knee joints. MFCL-2 amputees constitute a heterogeneous patient group with large variation in functional performance levels. A substantial part of this group seems to benefit from using a microprocessor-controlled prosthetic knee joint when performing activities of daily living.

Comparative Biomechanical Analysis of Current Microprocessor-Controlled Prosthetic Knee Joints

Bellmann M, Schmalz T, Blumentritt S. Comparative biomechanical analysis of current microprocessor-controlled prosthetic knee joints. Objective To investigate and identify functional differences of 4 microprocessor-controlled prosthetic knee joints (C-Leg, Hybrid Knee [also called Energy Knee], Rheo Knee, Adaptive 2). Design Tested situations were walking on level ground, on stairs and ramps; additionally, the fall prevention potentials for each design were examined. The measuring technology used included an optoelectronic camera system combined with 2 forceplates as well as a mobile spiroergometric system. Setting The study was conducted in a gait laboratory. Participants Subjects with unilateral transfemoral amputations (N=9; mobility grade, 3–4; age, 22–49y) were tested. Interventions Participants were fitted and tested with 4 different microprocessor-controlled knee joints. Main Outcome Measures Static prosthetic alignment, time distance parameters, kinematic and kinetic data and metabolic energy consumption. Results Compared with the Hybrid Knee and the Adaptive 2, the C-Leg offers clear advantages in the provision of adequate swing phase flexion resistances and terminal extension damping during level walking at various speeds, especially at higher walking speeds. The Rheo Knee provides sufficient terminal extension; however, swing phase flexion resistances seem to be too low. The values for metabolic energy consumption show only slight differences during level walking. The joint resistances generated for descending stairs and ramps relieve the contralateral side to varying degrees. When walking on stairs, safety-relevant technical differences between the investigated joint types can be observed. Designs with adequate internal resistances offer stability advantages when the foot is positioned on the step. Stumble recovery tests reveal that the different knee joint designs vary in their effectiveness in preventing the patient from falling. Conclusions The patient benefits provided by the investigated electronic prosthetic knee joints differ considerably. The C-Leg appears to offer the amputee greater functional and safety-related advantages than the other tested knee joints. Reduced loading of the contralateral side has been demonstrated during ramp and stair descent. Metabolic energy consumption does not vary significantly between the tested knees. Hence, this parameter seems not to be a suitable criterion for assessing microprocessor-controlled knee components.

Energy Expenditure and Activity of Transfemoral Amputees Using Mechanical and Microprocessor-Controlled Prosthetic Knees

Kaufman KR, Levine JA, Brey RH, McCrady SK, Padgett DJ, Joyner MJ. Energy expenditure and activity of transfemoral amputees using mechanical and microprocessor-controlled prosthetic knees. Objective To quantify the energy efficiency of locomotion and free-living physical activity energy expenditure of transfemoral amputees using a mechanical and microprocessor-controlled prosthetic knee. Design Repeated-measures design to evaluate comparative functional outcomes. Setting Exercise physiology laboratory and community free-living environment. Participants Subjects (N=15; 12 men, 3 women; age, 42±9y; range, 26–57y) with transfemoral amputation. Intervention Research participants were long-term users of a mechanical prosthesis (20±10y as an amputee; range, 3–36y). They were fitted with a microprocessor-controlled knee prosthesis and allowed to acclimate (mean time, 18±8wk) before being retested. Main Outcome Measures Objective measurements of energy efficiency and total daily energy expenditure were obtained. The Prosthetic Evaluation Questionnaire was used to gather subjective feedback from the participants. Results Subjects demonstrated significantly increased physical activity–related energy expenditure levels in the participant's free-living environment ( P=.04) after wearing the microprocessor-controlled prosthetic knee joint. There was no significant difference in the energy efficiency of walking ( P=.34). When using the microprocessor-controlled knee, the subjects expressed increased satisfaction in their daily lives ( P=.02). Conclusions People ambulating with a microprocessor-controlled knee significantly increased their physical activity during daily life, outside the laboratory setting, and expressed an increased quality of life.

Gait and balance of transfemoral amputees using passive mechanical and microprocessor-controlled prosthetic knees

Background Microprocessor-controlled knee joints appeared on the market a decade ago. These joints are more sophisticated and more expensive than mechanical ones. The literature is contradictory regarding changes in gait and balance when using these sophisticated devices. Methods This study employed a crossover design to assess the comparative performance of a passive mechanical knee prosthesis compared to a microprocessor-controlled knee joint in 15 subjects with an above-knee amputation. Objective measurements of gait and balance were obtained. Results Subjects demonstrated significantly improved gait characteristics after receiving the microprocessor-controlled prosthetic knee joint ( p < 0.01). Improvements in gait were a transition from a hyperextended knee to a flexed knee during loading response which resulted in a change from an internal knee flexor moment to a knee extensor moment. The participants’ balance also improved ( p < 0.01). All conditions of the Sensory Organization Test (SOT) demonstrated improvements in equilibrium score. The composite score also increased. Conclusions Transfemoral amputees using a microprocessor-controlled knee have significant improvements in gait and balance.

Function and Body Image Levels in Individuals with Transfemoral Amputations Using the C-Leg??

In Brief Using the Otto Bock C-Leg® (Otto Bock Health Care, Minneapolis, MN), a microprocessor-controlled prosthetic knee joint, may lead to an enhanced level of functional independence. It also was hypothesized that increased functional abilities and independence while using the C-Leg correlate with a positive body image. After Institutional Review Board approval was received, a purposive sampling method was used to recruit eight adult volunteers from a regional rehabilitation hospital. Inclusion criteria for participants in this study were: individuals with transfemoral amputation, currently using the C-Leg, older than 18 years, and without cognitive limitations. Subjects completed a series of three surveys: the Reintegration to Normal Living Index, the Situational Inventory of Body-Image Dysphoria, and the Function & Body Image Survey (FBIS). Survey questions pertained to personal satisfaction with the C-Leg, functional independence in role performance, and body image. Significant relationships were found between functional role performance and self-efficacy (rs = 0.863, p < 0.01), social integration (rs = 0.743, p < 0.05), personal relationships (rs= 0.711, p < 0.05), and an inverse relationship with psychological distress (rs = −0.772, p < 0.05). These correlations were supported by responses from the FBIS suggesting that the C-Leg can expand a client’s level of function, self-esteem, and motivation. Response categories of functional role performance and body image were correlated to test the second hypothesis, resulting in a fair but not statistically significant relationship (rs = −0.43, p > 0.05). Individuals using the C-Leg were found to exhibit high levels of role participation, functional activity performance, and self-confidence. Role participation improvements were associated with feeling safer and experiencing fewer falls. The most common improvements in functional activity performance were found with walking, climbing stairs, sports/recreation, work/employment, and decreased fatigue because of reduced energy expenditure. In addition, self-confidence was expressed in terms of improved social participation. Although there was only a fair correlation, body image was found to be improved because individuals were able to walk with a more natural gait and felt more secure in public places because of the stability the C-Leg offers. Results indicate the importance of psychosocial consideration in the selection of prosthetic knee technology. This study was designed to test the theory that individuals using the Otto Bock C-Leg®, a microprocessor controlled prosthetic knee joint, may experience an enhanced level of functional independence. Secondly, it was hypothesized that increased functional abilities and independence from using the C-Leg correlate with a positive body image. People using the C-Leg were found to exhibit high levels of role participation, functional activity performance, and self-confidence. Although there was only a fair correlation, body image was found to be improved because individuals were able to walk with a more natural gait, and also felt more secure in public places because of the stability the C-Leg offers. Results indicate the importance of psychosocial consideration in the selection of prosthetic knee technology.

Biomechanics and evaluation of the microprocessor-controlled C-Leg exoprosthesis knee joint

Also in the field of technical orthopedics, electronics and computer technology are being is used more and more often. This paper describes a microprocessor-controlled prosthetic knee joint with swing phase control and stance phase stability, the so-called C-Leg. The function of this electronic knee joint is explained. Prosthetic treatment using the C-Leg is compared with traditional prosthetic knee joints. 15 patients using the C-Leg have been observed over periods of 6 to 14 months. The treating prosthetists have given an assessment regarding the function and the improvements in comparison with the previously fitted knee joints. The patients, too, were asked to compare function and comfort of the new prosthetic fitting with the previous one. Both, prosthetists and patients marked this new type of microprocessor-controlled knee joint in nearly all points with "very good" and described a clear improvement to the previous, purely mechanical prosthetic fitting. Obviously, this new technology seems to be a milestone in prosthetic knee joint fitting, in order to clearly improve the prosthetic fitting of transfemoral amputees and thus their quality of life, especially of people who have several disabilities.