Transtibial amputation (TTA), a life-changing event, is the most frequent type of amputation in the working-age population.1,2 Workers with TTA face the risk of residual limb (residuum) injury during performance of work-related activities,2 despite proclaimed advances in rehabilitation and prosthetic technology.3 Work performance capacity during walking, lifting, and carrying can progressively deteriorate.3 And, because injured workers with TTA are unable to comfortably wear their prosthetic limb for a prolonged period during residuum recovery, their labor force retention is placed in peril.2–4
Many health professionals in care research for persons with amputation assume that, when patients demonstrate minimal to no differences in step length, stride length, or cadence during gait, then the patients can rejoin the workforce.5 Walking with a symmetrical gait pattern can minimize injury risk.6 However, investigation has not focused on those with TTA who are members of the labor force. Others postulate that susceptibility to injury is linked to progressive deterioration of distal residuum muscle and other soft tissues following amputation surgery. This phenomenon has been demonstrated in those with conventional TTA6 but inadequately in a work-related context or in those with other amputation surgical approaches.
A growing number of people with TTA have undergone one unique surgical approach to TTA, called osteomyoplastic TTA, in which the distal-most tibia and fibula are surgically synostosed using osteo-periosteal flaps to form a weight bearing bone “bridge.”7 Anterior, lateral, and posterior muscle compartments in the lower leg are then reattached distally to create length-tension relationship in these distal-most muscles.7
Dionne and colleagues8 found in a cross-sectional study that male workers with TTA (conventional and osteomyoplastic) were able to walk at two different speeds (self-paced, brisk) at the same capacity as matched controls without amputation during 2-minute walk tests (2MWTs). However, the overall group of individuals with amputation was unable to lift or carry as much as the control group, implying that those with amputation may require further strengthening and training related to these two work-related activities. Furthermore, as this was a cross-sectional study, no measurements were taken to determine consistency in performance over a period of time.8
Little is known about performance of typical work-related activities, symmetry in gait parameters, perceived exertion, or residuum anthropometric changes over a set time period in the working-age group with TTA, regardless of surgical approach to TTA. Rehabilitation professionals need to proactively detect injury risk factors and intervene with effective treatment. For prosthetists and other rehabilitation professionals to target risk factors and appropriately intervene, performance of typical work-related activities and residuum anthropometric measures in workers with TTA must first be examined.
The purposes of this study were to examine and compare performance of gait and other work-related activities, perceived exertion, and residuum measures at two time points 12 months apart in otherwise healthy men with unilateral TTA. The work-related tasks analyzed in this study were timed self-paced walk (2MWT9), brisk (at capacity) walk (2MWT),9 floor-to-knuckle lift,10 and 25-ft carry.10 The investigators hypothesized that there would be a comparative asymmetry in gait as measured by step length, stride length, and cadence during self-paced and brisk gait. They also hypothesized that workers with TTA would demonstrate less capacity in lift and carry testing, report increased exertion, as well as demonstrate a decrease in residuum measures (girths, length) across a 12-month period. The 12-month timeframe was assumed by the investigators an adequate period of time to allow detection of changes (improvement or deterioration) in overall work performance in this cohort.
The University of Oklahoma Health Sciences Center Institutional Review Board for protection of human subjects approved the protocol before participant enrollment. This prospective study was part of a larger research program during which the investigators also studied serous bone biomarkers, residuum muscle activity, and prosthetic socket interfacial loads.
Formally consenting participants were included if they were men between 18 and 64 years of age, with unilateral TTA due to a traumatic event, of at least 6 months duration since amputation surgery, and otherwise healthy and could walk without an assistive device such as a cane. Subjects were excluded if they had comorbidities such as diabetes or any other significant endocrine, peripheral vascular, or neuromuscular condition. Women were excluded to minimize the variability in bone biomarkers related to bone loss uniquely linked to perimenopausal factors, in addition to factors linked with TTA in the overall study.
At both visits, all personal and demographic data were collected. Participants responded to the Prosthetic Evaluation Questionnaire (PEQ)11 and Locomotor Capacity Index-5 (LCI-5)12 questionnaire, which quantify perceived ability and mobility relative to active prosthetic use.11,12 The responses from the questionnaires were considered part of the descriptive data. Residuum length (from knee joint line to distal end) and circumference (at tibial tubercle, 5 cm distal, proximal third, distal third) measurement data were taken by trained investigators. At each visit, participants were monitored via a portable gait analysis system (IDEAA®)8 to determine cadence, step length, and stride length. They underwent self-paced and at-capacity brisk 2MWTs. Saremi et al.13 found that the portable gait system as a… “convenient, reliable (P > 0.10, meaning no difference), and valid measure of spatiotemporal parameters of the gait cycle across upper range of walking velocities.”(p9) In addition, the 2MWT has been validated in controlled study of adults with amputation.9 Participants also performed standardized work-related tasks such as the 25-ft carry and floor-to-knuckle lift capacity tests.10 Report of perceived exertion (RPE; “Borg scale”14) was concurrently recorded during visits 1 and 2 throughout all testing.
Personal and questionnaire data were compiled and analyzed with descriptive statistics. Performance and gait parameter symmetry data were compared between visits 1 and 2 using the Kruskal-Wallis analysis of variance. Significance was set at 0.05.
Of the 25 participants in this convenience sample originally enrolled in the study, 21 participants completed visits 1 and 2. Of the four who did not complete the study, one was lost to attrition, and the remaining three had incomplete data because of instrumentation error. The completed dataset was analyzed for the current study (see Table 1). Participants' body height was similar across the participant group. Their respective body weight, despite varying between individual participants, was essentially unchanged between visits. No differences between visits were noted in either the PEQ scores or LCI-5 Index scores. Little pain or discomfort was reported by any of the participants except for one instance, which was negligible (i.e., <3/10 cm visual analysis scale). Within the overall sample, two participants had undergone the conventional TTA procedure; 19 had undergone the osteomyoplastic TTA approach. Mean time since amputation surgery was 76.5 months (range, 11– 372 months). As for time since amputation, three participants reported 11 to 12 months, seven reported 12 to 24 months, two reported 24 to 36 months, with the remainder reporting more than 60 months. All had received some form of rehabilitative services varying from time of surgery through beyond initial receipt of prosthesis (n = 8; 38%) to only upon receipt of the initial prosthesis (n = 13; 62%).
No differences were noted between visits in residuum length or girth measures taken at the tibial tubercle, at 5 cm distal, at proximal third or distal third of the residuum (Table 2). As seen in Table 3, there were no differences in distances walked or resultant heart rates at either the self-paced or brisk 2MWTs between visits. However, participants reported a significant increase in perceived exertion at visit 2 compared with visit 1 during the brisk 2MWT, from a median score of RPE = 8.4 at visit 1 to RPE = 10.3 at visit 2 (p = 0.034).
There was a significant increase in the participants' lift capacity at visit 2 than the initial visit by 40.4 lbs (p = 0.034). However, when comparing symmetry in gait, that is, differences in cadence, stride length, and step length, between the intact and residual limbs, there was a progressively larger difference in cadence from visit 1 to visit 2 (increased asymmetry) during the timed self-paced walk test (Table 4; p = 0.026).
Participants were similar in age with little anthropomorphic variability and appear to be representative of others studied in the research literature.1 Body weight was stable, which indicates the stability of basic health and nutrition. There was a wide range of time since amputation surgery, with few (i.e., three) being less than 1 year. The residuum shape is cylindrical in the overall sample, and overall residuum length and girths were essentially unchanged during the study's 12-month time frame. Questionnaire scores (PEQ and LCI-5) were high and fairly stable, which shows this cohort was high functioning across the 12 months. Reported pain scores (visual analysis scale) were reported to be very low, indicative of little to no discomfort with functional fit of the prosthesis and with little influence on performance testing.
However, lift and carry capacities were greater at the second visit, with lift capacity significantly greater than at the initial visit. It is not known whether any of the participants underwent formal strength training or had become more at ease within the laboratory environment. However, lift and carry test performance did improve over time.
Distances traveled during the two timed tests, regardless of walking speed, marginally increased in the self-paced and the “at-capacity” brisk walk tests. The investigators opine that a 6MWT15 could have been more discriminative in this high-functioning test group. However, there was an increase in RPE for the brisk walk test, an indicator of a greater perceived effort to walk at capacity,16 a possible implication for intervention.
Generalization of results is limited because the subject sample comprised merely 21 otherwise healthy male workers. All but two participants underwent osteomyoplastic TTA, so adequate comparisons could not be made between the TTA subgroups based on amputation surgical approach.
However, all participants were similar in age and height and maintained their body weight. There was a wide-ranging time since amputation and type and timing of rehabilitation received, so residuum volume variability related to surgery as well as timing of rehabilitation apparently had little influence. Participants reported little to no discomfort or perceived functional limitation over a 12-month time span. Participants demonstrated that improvement in lift performance is possible and residual limb volume can remain stable. However, to draw more conclusive generalizations, a larger study is required that includes equal number of participants with conventional and osteomyoplastic TTA as well a proportionate number of participants who struggle to remain workforce-eligible because of discomfort or perceived limitation in work performance.
This study demonstrates that men with TTA in the workforce can be consistent in performance over a 1-year time span, with possible exception of symmetry in cadence during gait. Otherwise healthy working-age men with TTA may require continual advanced gait training to minimize this asymmetry, potentially reducing perceived exertion and residuum injury risk.
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