Performance evaluation of Jaipur knee joint through kinematics gait symmetry with unilateral transfemoral Indian amputees

2.1. Participants

The eleven participants (Table 1) suffering from above knee amputation in one limb after a physical injury or trauma, with no comorbidity voluntarily are involved in this study. On prior to study, written consent letter was taken from all participants. Every one of them was used to wear prosthesis for many years. During the experiment, the same patients were asked to wear their prosthesis with Jaipur knee for a certain acclimation period suggested by the clinician. The research was carried under the supervision of trained and skilled staff at gait lab. All the steps to be involved in this study were discussed with subjects. Gait lab staff verified for comfortable socket fit, the overall fitment and alignment of prosthesis to ensure stability and comfort for amputees. A complete physical checkup of all participants, was done based on their history and current data of back joints, hip joints and knee joint, any prior disease or injury etc. This pre-assessment of experienced clinician was to ensure that no related issues exist which may have altered their walking pattern. Improper alignment may result in uncomfortable fit and non-uniform pressure distribution on socket limb joint boundary and it may lead to reduced comfort, uneasiness and potential tissue injury [17].

2.2. Gait analysis

For kinematic evaluation data were recorded with the help of computerized video motion analysis system which included six Vicon camera having a frame rate of 60 (frames per seconds) fps and using infrared (IR) light-emitting diode strobes. The cameras were located such that they yielded accurate movement data of prominent joints like hip joints, knee joint and ankle joint for both legs in sagittal plane. The reflective markers were located to setup anatomic coordinate system at prescribed locations for gait test. Then movement data of both legs were recorded and processed by the motion capture system. During each trial first static data was recorded when participant was standing comfortably. This data supported in calculations of joint centers positions. A strain-gauzed AMTI force plate dimensions (508 mm×460 mm) was fitted on midpoint of defined pathway, measured data for ground reaction forces. The force plate data was synchronized to the computer system. The data received from marker coordinate system and from AMTI force plate were acted as input to calculate kinematics data. Two consecutive heel strike points were considered as gait cycle. Intermediate states of gait were represented as percentage of total distance during gait.

2.3. Symmetry index

The kinematics performance of both knee joints in comparison with intact leg is measured with symmetry index. The main idea to calculate symmetry was to evaluate notable distinctions by quantitative approach between the both legs during gait like Robinson adopted algebraic method to calculate symmetry index [18]:

where $X_R$ and $X_L$ are gait variables for both legs respectively. Ideally symmetry index should be equal to zero, when calculated the all gait variables on discrete level. The approach used in this study was reported by Crankshaw [19], he utilized singular value decomposition method. As acquired data was in a waveform. All variables got subtracted from its average values and translated accordingly. The resulted new data point were calculated as $2\times n$ matrix $M$. Eigen values along with Eigen vectors were determined from the matrix $M$. In graph, ‘0’ value indicates that the waveform was not affected while +1 and –1 donated the points of model symmetry and model asymmetry respectively. This data acquisition was done for both legs and kinematic analysis was done for hip joint, knee joint and ankle joints.

The movement of joints have been captured in sagittal plane. For statistics, a standard statistical analysis tool was used. As discussed before that two gait phases with one knee joints were recorded in many trials therefore two way analysis of variance (ANOVA) approach was preferred to measure deviation of symmetry while using two different knee joints units in prosthesis. Statistical significance of $p$ ≤ 0.05 was considered.

3.1. Participants

In this research, 11 unilateral transfemoral subjects [9 men and 2 women; mean age 45 years, (SD = 12 years,31-58 years range); and mean body mass index (BMI) of 29 kg/m², (SD = 6 kg/m²) were participated. These participants were used to wear prosthesis for long time with mean data of 16 years. They were tested with prosthesis with Jaipur knee and re-examined with an acclimation period (Average 14 weeks, SD = 6 weeks).

3.2. Kinematic symmetry

The symmetry as shown in (Fig. 1) with kinematic data is different as found by gait phase and joint level. The joints movement have recorded in sagittal plane, it is evident that appreciable symmetry is shown in swing phase as well as in stance phase of gait cycle. Index reported symmetry more than 0.90. In stance and swing phases, the sagittal motion exhibited good symmetry where the symmetry index was more than 0.90 at hip joint in the amputee population, standard significance was set ($p=$ 0.14). At knee joint notable symmetry deviation was seen during swing phase and stance phase ($p=$ 0.006) indicating maximum deviation in stance phase of knee joint. There was least symmetry reported during stance phase on changing knee locations with respect to loading conditions. On contrary many participants justified kinematics symmetry during swing phase ($p=$ 0.36). Likewise, at hip joint and ankle joint also, appreciable symmetry was reported in swing and stance phase. Data reported maximum asymmetry in graph indexed near to –1. In above knee prosthesis foot unit experiences less planter flexion than intact leg this causes maximum asymmetry at ankle joint in swing phase. The data from a representative subject may justify logically the visible in symmetry obtained in Jaipur knee (Fig. 2). The participants reported increased knee flexion against loading during gait, this response appreciably got compensated. That is why knee joint deviation in stance reported significant –0.012.

Fig. 1Kinematics symmetry index for joints (hip, knee, ankle) resulted from Jaipur knee joint recorded in sagittal plane

Fig. 2Kinematics results in sagittal plane indicating hip, knee & ankle joints for non-prosthetic leg NPL (solid line) versus the prosthetic leg (dashed line) where the participants were using a Jaipur knee joint.

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