Kinematic gait analysis of a young man after amputation of the toes

Transcription

1 Original Paper Biomedical Human Kinetics, 6, 40 46, 2014 DOI: /bhk Kinematic gait analysis of a young man after amputation of the toes Wanda Forczek, Tadeusz Ruchlewicz, Anna Gawęda Department of Biomechanics, Faculty of Physical Education and Sport, University School of Physical Education, Krakow, Poland Summary Study aim: the foot is recognised as a functional unit with two important aims: to support body weight and to serve as a lever to propel the body forward. When it is impaired, the locomotor pattern has to adapt to compensate for the dysfunction. The purpose of this study was to investigate gait kinematics of a man after bilateral partial amputation of the toes. Material and methods: the subject of the study was a young man aged 30 years (body height and mass: 186 cm, 82 kg) who suffered a frostbite injury in the feet while climbing in the severe mountain conditions. After a few months of treatment, the necessary amputation occurred. Three-dimensional lower limb kinematics was collected from motion capture system (Vicon 250) and Golem marker set-up using 5 video-based cameras with infrared strobes. The subject performed over-ground walking at self-selected speed, first barefoot, then wearing athletic shoes. Results: the patient s results are the mean values of sixteen full gait cycles. The spatiotemporal parameters were lower during gait without shoes. In terms of the angular changes of the lower limb joints in sagittal plane, the analysis revealed similar functional patterns and typical trends in both recorded conditions. The differences, however, occurred in their amplitude. A larger range of motion was generally noted in shod conditions. The higher the joint was, the smaller the differences were. Conclusions: changes in gait due to the forefoot dysfunction may be stabilizing adaptations related to fear of falling. Footwear provided more stable conditions. Key words: Biomechanics Barefoot Footwear Frostbite Forefoot Introduction Human gait, as the basis of daily activity, only appears to be a simple task. We realize its complexity when even one element of the kinematic chain, which is the lower limb, is impaired. Then, we need to adapt our locomotor pattern to compensate for the dysfunction. The research revealed that even a partial loss of the toes not only changes the anatomical structure of the foot but also modifies the gait pattern [9, 23]. We need to bear in mind that the toes are a crucial element in increasing the weight-bearing area during walking [6], as well as the first metatarsophalangeal joint complex, an important component in both stance and propulsive phases of gait [16]. The risk of toe damage is involved in alpine climbers activity. They are very often subject to long exposure to cold that may result in frostbite, the most serious peripheral injury. It can occur when temperatures drop low enough for tissue to freeze [3]. Historically, it has been a disease of wars, but it is a hazard for anyone who ventures outdoors in cold weather [24]. Frostbite can be classified as superficial, without permanent tissue loss, or deep, with varying degrees of permanent tissue loss. The latter one often results in some form of amputation. This kind of surgical treatment is especially related to the foot. From the biomechanical perspective, the foot is identified as a functional unit with two important aims: to support body weight and to serve as a lever to propel the body forward [17]. Human foot bones form three strong arches: two lengthwise and one across the foot. Arch structures and toes are recognised as critical to gait because of the large range of motion displayed by the ankle [23]. Although many aspects of pathological gait have been the subject of scientific inquiry, to the knowledge of the authors, the mechanism of locomotion after toe amputation due to frostbite was not documented. It seems hard to understand this situation, since climbing and mountaineering sports are gaining more public interest. That is why the purpose of this study was to investigate the gait kinematics of a young man after frostbite requiring bilateral partial amputation of the toes in two footwear conditions: while walking barefoot and in athletic shoes. Author s address W. Forczek, Department of Biomechanics, Faculty of Physical Education and Sport, University School of Physical Education, Al. Jana Pawła II 78, Kraków, Poland, wanda.forczek@gmail.com

2 41 Kinematic gait analysis of a young man after amputations of the toes a) b) Fig. 1. Climber s toes before (a) and after (b) amputation Material and methods height, weight, left and right leg length, left and right knee width, and right and left ankle width. Participant The subject of our study was a young man aged 30 years (body height and mass: 186 cm, 82 kg, respectively). As an alpinist, he suffered a frostbite injury to the feet while mountain climbing (August 2010). The treatment process took two years. After numerous stays in hospitals in Poland and abroad, the necessary amputation occurred: at first right (November 2010), and three weeks later, left toes (December 2010). After 1.5 years, the patient s state was as follows: in the right foot, the absence of the half of distal phalanx of the great toe and half of the distal phalanx of 2nd and 3rd toes, while in the left foot, the absence of distal phalanx and 1/3 proximal phalanx of the great toe, distal and medial phalanx of the 2nd, 3rd and 4th toes, and distal phalanx of the 5th toe. Results Gait analysis The locomotion recording was carried out in the Biomechanics Laboratory in University of Physical Education in Krakow. Three-dimensional lower limb segment kinematics was collected from motion capture system (Vicon 250; Oxford Metrics Ltd.; Oxford, UK) using 5 video-based cameras with infrared strobes. The subject performed over-ground walking at self-selected speed in two footwear conditions: barefoot and shod (subject s athletic shoes). Due to that, we assumed the impact of footwear on the lower extremity biomechanics. In both conditions, 16 complete gait cycles for each leg were recorded, and the analysed parameters were averaged over all trials. The whole body of the patient was covered with the reflective markers placed on the skin in 39 anthropometric points according to Golem set-up. In the shod condition, 4 markers were placed on the shoe surface as close as possible to the original position. Prior to data collection, the following physical measurements of the subjects were recorded: The patient s results are the average of sixteen full gait cycles (32 steps) recorded during walking trials performed at natural speed in two conditions: barefoot and wearing shoes. These include the space-time parameters and instantaneous changes of the angle of the lower limb joints (ankle, knee and hip) in sagittal plane. Data for each cycle were normalized: 0% 100% GC (gait cycle). Spatiotemporal parameters The analysis allowed differences in the variables reflecting amputee gait performed barefoot and in shoes to be observed. The data are included in table 1. As we can see in table 1, the velocity was higher during shod walking than barefoot (approx. 0.2 ms 1). Additionally, the basic parameters determining velocity, which are step frequency and step length, consequently were lower during gait without shoes. Considering the remaining time Tab. 1. Descriptive statistics of spatiotemporal parameters (SPT) during subject s gait in two footwear conditions: barefoot and shod (v velocity, f step frequency, SS, DS single support, double support, respectively, ST, SL step time and step length, respectively) SPT Barefoot Shod v [m/s] 1.10 ± ± 0.04 f [step/min] 105 ± ± 3.0 SS [s] 0.44 ± ± 0.02 DS [s] 0.26 ± ± 0.05 SL [m] 0.62 ± ± 0.02 ST [s] 0.57 ± ± 0.02

3 42 W. Forczek et al. variables, we noticed only minimal differences; thus, single support and double support as well as step time were similar. Joint angular changes in sagittal plane In terms of the angles of the lower limb joints in sagittal plane, the analysis revealed similar functional patterns and typical trends in both recorded conditions. The differences, however, occurred in their amplitude. A larger range of motion was generally noted in shod conditions. There was a clear trend observed: the higher the joint was, the smaller the differences were. The particular cases are noted below. Figure 2 illustrates angular changes of the ankle joint. The ankle moves through four arcs of motion during each stride. Quite similar values were recorded during the stance phase in both walking conditions, except for the heel strike moment. Then the ankle was positioned neutrally during barefoot walking, while shod gait started with small dorsal flexion (4.5 ). Concerning the joint amplitude, we noticed a large discrepancy in shod conditions compared to gait without shoes (27.62 vs ). Another difference was clearly visible during limb advancement; plantar flexion was smaller in barefoot (5 ) and greater (about 15 ) when the subject walked with shoes. Thus, the difference between the minimal values of the ankle joint was about 10. The time when the dorsal flexion started again in the swing phase was also shifted by 10% GC: while walking without shoes, it was approximately 70% GC and approximately 80% GC with shoes. 25 ANKLE DORSI/PLANTAR 20 Angle (degrees) Dors BAREFOOT 10 Plan SHOES Time (Samples) Fig. 2. Angular changes of the ankle in the sagittal plane during walking with natural velocity in two footwear conditions: barefoot and shod

4 Kinematic gait analysis of a young man after amputations of the toes 43 KNEE FLEXION/EXTENSION 50 SHOES Angle (degrees) Flex Ext 0 BAREFOOT Time (Samples) Fig. 3. Angular changes of the knee in the sagittal plane during walking with natural velocity in two footwear conditions: barefoot and shod The knee moves through four arcs of motion during one gait cycle. The values of these joint angular changes are slightly lower in gait without shoes (fig. 3). When the patient walked with shoes, the knee joint was 1 2 more flexed during the single limb support task. The largest difference was recorded during the swing phase in maximal flexion: and 37.62, for shod and barefoot walking, respectively. As we can see, the mobility of the knee was larger in shod walking (46 vs. 40 ). The hip moves through only two arcs of motion during a normal stride: extension during stance and flexion in swing. Considering the amplitude of the hip joint, there was only 4 difference between the two footwear conditions (39 vs. 43 ) (fig. 4). Most of gait cycle was characterised by similar functional patterns of this joint. The only differences were recorded at the initial and terminal phases of the stride when the subject performed a slightly higher (by about 3.5 ) value of angle during the shod gait. Discussion Gait stability is an important and necessary precondition for walking without falling [4]. In order to maintain balance during dynamic activities, corrections to the base of support are provided by suitable foot placement. Foot behaviour, therefore, provides the key to understand gait stability. In alpine climbing, the acute and chronic musculoskeletal injuries mostly affect the lower extremity [19]. The subject of the study was a young alpinist who suffered frostbite injury to the feet when climbing in the severe mountain conditions. Our main task was to identify his lower limb joint kinematics after partial amputation of the toes in two footwear conditions: barefoot and shod. We expected that comparison of the results would demonstrate different locomotor patterns. We could form this hypothesis since the assessment of the occurrence of falls

5 44 W. Forczek et al. 35 HIP FLEXION/EXTENSION 30 Angle (degrees) Flex SHOES 0 5 Ext 10 BAREFOOT Time (Samples) Fig. 4. Angular changes of the hip in the sagittal plane during walking with natural in two footwear conditions: barefoot and shod in the elderly population (more prone to falls) provided evidence that footwear had a substantial effect on the risk of falls [8]. Additionally, it was also proved that the use of proper footwear could provide more stable posture [2]. To our surprise, there are no investigations considering the mode of body transfer after amputations due to frostbite. That is why, in this part of the paper, our observations are supported by the results of the foot dysfunctions following other deformities. The analysis of spatiotemporal parameters of the patient walking barefoot allowed us to notice a slower speed, shorter steps and decreased step frequency. Additionally, slightly increased values for the double support phase and stride time were noted. It means that our subject, while performing locomotion without shoes, was more careful in placing the feet on the ground than in the shod condition. This kind of mechanism in the pattern of the patient s locomotion was also revealed in several studies carried out in diabetic patients [1, 13], patients with rheumatoid arthritis (RA) [10, 14] and transtibial amputees [5, 7, 20]. They have demonstrated a decrease in the quality of spatiotemporal gait parameters: a slowing in the walking velocity, a shortened stride length and increased doublestance period, as compared to able-bodied individuals. Such observations were also present in the study of the heel strike, foot flat and toe-off sequences have been replaced by a flat-footed type of gait [12]. Maki (1997) and Tinetti andpowell (1993) stated that gait instability likely contributes to changes in neuropsychological and functional status, including a fear of falling and decreased

6 Kinematic gait analysis of a young man after amputations of the toes 45 confidence. However, according to Dingwell et al. (2000), reductions in walking speed are a compensatory strategy used by neuropathic patients to maintain dynamic stability of the upper body during level walking. In normal feet, peak pressures are highest over the second and third metatarsal heads, with a gradual fall off medially and laterally. Woodburn and Helliwell (1996) emphasized raised pressures and abnormal distribution patterns as a reaction to pathological changes in the forefoot and gait modification as a pain avoidance strategy in RA patients. While Laroche et al. (2006) did not support pain influence on gait in RA patients, this observation was confirmed by the study of Minns and Craxford (1984), who analysed generation and transmission of forces under the foot in normal subjects and patients with rheumatoid arthritis. They concluded that changes recorded during walking without shoes were consequence of pain because the centre of pressure was shifted from the most painful parts of the foot [12]. Higher loads in anterior areas of the foot were also observed in diabetic neuropathy subjects. Increased pressure was concentrated in the mid-foot and in the forefoot areas during the support phase [18]. Thus, any changes in the foot architecture are important reasons to properly secure and stabilize this affected part of the body. Amputation of a great toe and part of all of the first metatarsophalagal joints disrupts the integrity of the medial column of the foot and the arch collapses [16]. It seems to be a rationale for using shoes in case of foot pathology. Wearing shoes provided more confidence and stability to our subject s body that was manifested by a higher velocity (by about 0.2 ms 1 ) compared to the barefoot condition. Consequently, the main parameters defining velocity, the cadence of steps and step length, were larger. Advancement of the body depends on stance limb mobility. The accomplishment of this function depends on a distinct motion pattern of the given joint of lower limb. Our study presents quantitative analysis of three lower extremity joints: ankle, knee and hip in the sagittal plane. As to their range of movements, smaller values were recorded in barefoot ambulation. Looking at the level of discrepancy, we observed that the higher the joint was located, the smaller the differences were. Limited joint mobility is common in diabetic neuropathy as demonstrated by the significant reductions in total ROM at ankle [13, 18], knee [1, 13] and hip [13]. The reduced ankle movement amplitude may interfere in the foot adaptation to changes in foot-floor interaction that may culminate in increased pressure on the plantar surface [18]. Besides, Muller et al. (1998) noticed that people with diabetes mellitus and transmetatarsal amputation showed lower peak moments and less power at the ankle, and an earlier onset of the hip flexor moment compared to agematched controls. Considering the transtibial amputee gait adaptation, knee flexion in the prosthetic limb has been reported as significantly higher than the intact limb at heel strike, which can be linked to the most optimal positioning of the prosthetic socket [7]. Bearing in mind the less stable situation in walking barefoot, we can use the conclusion of Tinetti and Powell (1993), who stated that gait instability likely contributes to self-imposed mobility restrictions. In our experiment, the athletic shoes provided increased range of motion of all the analysed joints. On the other hand, the comparison of the instanteous values of the angles allowed similar functional patterns of movements in both variants of gait to be observed. The observed discrepancy between the footwear conditions is consistent with this interpretation: in RA patients with reduced metatarsophalangeal mobility, the central nervous system might change lower limb segment coordination in order to reduce forefoot pressure and pain and/or to allow or facilitate walking [10]. Conclusions 1. Compensatory mechanisms following the forefoot impairments influence kinematic pattern of walking. 2. Reduced stability as a result of partial toe amputation imposes decreases in gait velocity, step length and step frequency. 3. Changes in gait due to the forefoot amputation may be stabilizing adaptations related to fear of falling. Footwear provided more stable conditions. References 1. Dingwell J.B., Cusumano J.P., Sternad D., Cavanagh P.R. (2000) Slower speeds in patients with diabetic neuropathy lead to improved local dynamic stability of continuous overground walking, J. Biomech., 33: Federolf P., Roos L., Nigg B. 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