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BWSTT in Chronic SCI

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Table 6: Studies Using Treadmill Training in Chronic SCI (>1 year post-injury)

Discussion

As shown in Table 6, there have been 13 pre-post studies, 5 RCTs (Musselman et al. 2009; Nooijen et al. 2009; Field-Fote et al. 2005; Field-Fote & Roach 2011; Wu et al. 2012) 1 prospective Controlled Trial (Gorassini et al. 2008) and 1 case-control study (Wernig et al. 1995) that altogether studied 1054 persons with complete and incomplete SCI, with chronicity ranging from 1 to 28.2 years post-injury (although years of chronicity was not specified in Field-Fote et al. 2011 study). Treatment intensity ranged from 45 to 300 minutes per week, and treatment duration lasted between 3 and 48 weeks. Based on the stated primary outcome measure of each study where data was available, about 70% of all subjects across these studies showed some improvement following treatment (Musselman et al. 2009; Gorassini et al. 2009; Hicks et al. 2005; Yang et al. 2011; Winchester et al. 2009; Protas et al. 2001; Thomas and Gorassini et al. 2005; Effing et al. 2006; Wernig et al. 1995). In the Harkema et al. 2012 study, 88% of patients had responded to locomotor training treatment, but this study included subjects that had been injured less than one year.

A large pre-post study utilized intensive locomotor training (a combination of body-weight supported treadmill training, overground training and community integration) in persons with SCI (AIS level C or D) (Harkema et al. 2012) (n = 95).  The investigators showed significant improvement in balance and walking outcomes, despite high variability in baseline measures. Patients had significant improvements no matter the number of years post-injury, but those who had more chronic injuries showed smaller improvements than those that had been more recently injured. However, there was no control group to provide information on whether this type of training is better than no therapy or other interventions.

There are two small RCTs (although some subjects overlapped between these two studies) that compared functional ambulation outcomes among four different approaches to gait training: manual- or robot-assisted BWSTT, BWSTT+FES, and overground gait training+FES (Nooijen et al. 2009; Field-Fote & Roach. 2011). For gait speed measured over a short distance (6 meters), participants in the BWSTT+FES group, manual assisted BWSTT group and those in the overground gait training+FES group showed better outcomes compared to participants in the robot-assisted BWSTT group. However, walking distance increased only for those in the overground+FES and the BWSTT+FES groups, with a greater increase in the overground+FES group. Thus, there is level 1b evidence that these different modes of gait training (except for robotic assisted treadmill training) result in similar effects on gait speed, and that walking distance increased with overground training+FES or BWSTT+FES. Additional analysis of the quality of the gait pattern also revealed that all these different modes of gait training yielded improvements in over ground walking cadence, step length, and stride length. Greatest improvements were seen in individuals who trained with FES and the least improvements were seen in individuals who trained with the Lokomat (Nooijen et al. 2009). Subjects with initially-slower walking speeds (< 0.10 m/s walking speed) tend to make the most improvements in locomotor function. Subjects with initially high walking capacity (> 0.10 m/s gait speed) or severely impaired, initially non-ambulatory subjects tend to show little improvement after gait retraining (Wernig et al. 1998, Wernig et al. 1995). Note that a large percent improvement from an initially low walking speed can be a result of the mathematics. More recent analysis of walking outcomes post-training showed that time post-injury, voluntary bowel and bladder voiding, functional spasticity, and walking speed before training were the strongest predictors of post-training overground walking speed (Winchester et al 2009). Taken from data from 30 subjects, this model could predict 78% of the variance of final walking speed. Of additional clinical interest is an understanding of how gains in walking speed translate to everyday function. For people with paraplegia, it has been suggested that an overground walking speed of at least 0.9 m/s is necessary for community ambulation (Cerny et al. 1980). Nevertheless, even modest gains in walking speed after treadmill training have been reported to translate into meaningful enhancements in daily function (Field-Fote et al. 2005; Field-Fote & Roach 2011).

Alternative gait retraining therapies or modified approaches to BWSTT for chronic SCI are being introduced (Musselman et al. 2009; Stevens and Morgan 2010; Wu et al. 2012). Musselman et al. (2009) presented a case series of 4 individuals with SCI who completed a cross-over study comparing BWSTT with over ground skilled walking training. The skilled walking training consisted of task-specific practice (without body weight support) of various gait tasks, such as stair climbing, obstacle crossing, and walking along sloped surfaces. In this small group of subjects, there was a tendency for participants to show better improvement in functional ambulation scores following skilled training vs. BWSTT, particularly in those who were more chronic (> 4 years post-SCI). Thus skilled walking training may provide additive benefits to those individuals who have already recovered some ambulatory capacity several years after their injury (Musselman et al. 2009). More recently, Wu et al. (2012) demonstrated a new cable-driven robotic device to apply resistance against leg movements during BWSTT. Subjects were randomized (in a cross-over design) to receive robotic resistance or assistance BWSTT. Although there were no significant differences in outcomes between the two modalities, there was some indication that robotic resistance enabled greater gains in over ground walking speed in individuals who tended to have better initial ambulatory capacity; conversely, robotic assistance seemed to enable greater gains in walking speed in those who were initially slower walkers. Further work is required to understand how best to tailor gait training strategies based on an individual’s initial status.

Conclusion

There is level 1b evidence from 1 RCT (Field-Fote & Roach 2011) that different strategies for implementing body weight support gait retraining all yield improved ambulatory outcomes in people with chronic, incomplete SCI, except for robotic assisted treadmill training which showed little change in walking speed. It is recommended that therapists may choose a body weight support gait retraining strategy based on available resources (Field-Fote & Roach 2011).

There is level 4 evidence from pre-test/post-test studies (Behrman et al. 2012; Buehner et al. 2012; Harkema et al. 2012; Lorenz et al. 2012; Winchester et al 2009; Hicks et al. 2005; Wirz et al. 2005; Thomas and Gorassini 2005; Protas et al. 2001; Wernig et al. 1998) that BWSTT is effective for improving ambulatory function in people with chronic, incomplete SCI.

  • Body weight-support gait training strategies can improve gait outcomes in chronic, incomplete SCI, but most body weight-support strategies (overground, treadmill, with FES) are equally effective at improving walking speed. Robotic training was the least effective at improving walking speed.