Lumbar Traction for Managing Low Back Pain: A Survey of Physical Therapists in the United States

Methods

Results

Discussion

Several systematic reviews and clinical practice guidelines have concluded that spinal traction has limited effectiveness for treating LBP.^8,33,35,49 Despite those guidelines, evidence suggests that a specific subset of patients with LBP may respond positively to traction.^9–11 Furthermore, while traction utilization in some European countries may be declining,²⁷ physical therapists in the UK have commonly used traction for patients with LBP and symptoms of nerve root compression.^12,15,16 We surveyed physical therapists in the United States about their use of spinal traction, including whether the use of traction was consistent with a classification system identifying patients for whom traction may be beneficial, and their preferred traction delivery modes and parameters, and we examined their use of supplemental interventions. Our findings suggest that a majority of APTA Orthopaedic Section members use traction and use it consistent with recommendations from a classification system that preliminarily identifies patients in whom traction may provide benefit.^9–11,15 In contrast, approximately one third of respondents indicated that they would use traction for patients in a manner that is contrary to that classification, and respondents were quite variable in their selection of traction modes and parameters. Additionally, physical therapists use traction as a component of comprehensive plans of care that include multiple interventions.

A majority of respondents (76.6%) indicated that they used traction in their practices. This proportion is higher than that identified by Harte et al,¹⁶ who reported that 41% of physical therapists in the UK used traction. Whereas Harte et al¹⁶ reported an 83% response rate, our response rate (25.5%) was considerably lower. While reasons for the differential response rates are not entirely clear, the length of the survey (28 open- and closed-ended questions) and potentially the perceived importance of the survey's topic by invited participants are factors that might have contributed to the response rate.^2,4 The differences in the proportions of respondents reporting that they use traction in their practices may reflect a response bias, whereby physical therapists who use traction were more likely to respond. Differences may also be accounted for by varying sampling approaches used in the studies. Harte et al¹⁶ surveyed a random sample of chartered physical therapists in the UK who specialized in musculoskeletal management. The manner in which they determined which therapists specialized in musculoskeletal management, however, was not described. The present study, on the other hand, exclusively surveyed physical therapists who were members of the APTA's Orthopaedic Section. It is, therefore, possible that the sample included a higher proportion of physical therapists whose patient populations were more likely to have LBP. Moreover, differences could also reflect changes in practice over time. Harte et al¹⁶ published their findings a decade ago. While more recent evidence suggests that traction utilization in some European countries may be declining,²⁷ it is possible that contemporary practice changes might have influenced traction usage rates in the United States, particularly because much of the work regarding a traction classification has occurred since that time.^10,11

Historically, care for LBP has revolved around the belief that patients with LBP represent a homogeneous group.^7,8 More recently, clinicians have theorized that patients with LBP are heterogeneous and should be classified into subgroups accordingly, and they propose that patients in each subgroup will more likely respond to distinct treatment strategies.^7,9–11,30 While the evidence is preliminary, the subgroup most likely to respond to traction is hypothesized to be patients with signs and symptoms of nerve root irritation who do not centralize with lumbar movements.¹⁰ We therefore examined whether physical therapists in the United States were using traction for patients identified by Fritz et al¹⁰ as those most likely to benefit from traction. The first clinical scenario in the survey (APPENDIX, questions 13 and 14) specifically addressed this purpose, in which the patient presented with peripheralization of symptoms with standing lumbar extension movements and a positive crossed straight leg raise, both of which are signs by which a patient presumably would be classified into the traction subgroup.⁷ We hypothesized that most respondents would opt to use traction in that scenario. The results partially supported our hypothesis. While a majority (58.4%) indicated that they would use traction, nearly one third of respondents (31.4%) indicated that they would not use traction in that scenario. Further, we presented a second scenario (APPENDIX, questions 16 and 17) in which the patient presumably would not be classified into the traction subgroup. While most respondents (56.7%) indicated that they would not use traction, more than one third (34.6%) indicated that they would. An implication of these findings is that approximately one third of physical therapists may not incorporate lumbar traction in a manner that is consistent with current recommendations for its use.

We then examined preferred traction delivery modes and parameters. With regard to traction delivery modes, respondents most often administered traction manually (68.3%) or with a mechanical traction table permitting multiple angles of pull (44.9%). The preference for administering traction manually makes it difficult to ascertain preferred loading magnitudes. The proportion of respondents using manual traction techniques, however, is comparable to the proportion of physical therapists using manual traction in the UK (53%).¹⁶ In contrast, the proportion using mechanical traction tables (44.9%) is considerably less than that reported by Harte et al¹⁶ (79%). Per several ad hoc comments, many respondents indicated that they lacked access to mechanical traction tables in their particular practice settings, which may account for this difference. With regard to magnitude of traction delivery, most respondents preferred to administer lumbar traction at 30% to 50% of body weight. These magnitudes are consistent with the assumptions that intervertebral separation is necessary for therapeutic efficacy and that loads of 20% to 50% of body weight are required to achieve intervertebral separation.^3,20,21,42 Those assumptions, however, have not been confirmed through controlled trials, and our findings suggest only that physical therapists in the United States, with lack of confirmatory evidence to guide clinical decisions for loading most often apply lumbar traction at magnitudes of 30% to 50% of a patient's body weight. As a comparison, Meszaros et al³¹ reported that pain-free straight leg raise measurements in patients with LBP and lower extremity pain improved following traction application at 30% and 60% body weight, but not at 10% body weight. Despite that report, evidence-based recommendations for loading parameters have yet to be clearly articulated.

Physical therapy practice for managing LBP is often characterized by a vast array of intervention approaches, such as stretching and strengthening exercises, direction-specific exercises, manual therapy approaches to mobilize spinal segments, soft tissue mobilization/massage, and the use of electrical or thermal modalities.^26,36 Therefore, we examined supplemental interventions in patients' plans of care. It was clear that respondents used traction as part of comprehensive plans of care incorporating multiple interventions. The most commonly used interventions included core stabilization exercises, education regarding posture and body mechanics, mobilization techniques, prescription of general exercise/fitness programs, and massage or soft tissue mobilization techniques. These findings are largely consistent with those of Harte et al,¹⁶ who reported that advice regarding posture and management, general exercise and physical activity, core stabilization exercises, and mobilization techniques were incorporated into the plans of care by over 50% of their respondents. One difference between our findings and those of Harte et al¹⁶ was that they reported massage as being used by 12.1% of the physical therapists in their study, whereas employing soft tissue mobilization or massage was identified by approximately 65% of our respondents as a supplement to traction. Given limited evidence for the effectiveness of massage for treating LBP when compared against other manual therapy approaches or against exercise and education,^18,25 the extent to which physical therapists in the United States use soft tissue mobilizations/massage in managing LBP may be concerning.

Last, we examined whether professional characteristics of respondents were associated with clinical decisions regarding traction. Two characteristics were associated with traction preferences. First, a higher proportion of physical therapists with ABPTS orthopaedic certification used traction (88.6%) than did physical therapists without certification (73.0%), and physical therapists with certification more commonly reported that patient positioning would be diagnosis specific (48.1%) than did respondents without certification (34.0%). Second, a higher proportion of physical therapists with entry-level degrees at the masters or doctoral level reported using manual traction techniques (58.2% and 59.5%, respectively) than did those educated at the bachelors or certificate level (28.6% and 42.9%, respectively).

Professional characteristics of respondents were also associated with many of the supplemental intervention options illustrated in the FIGURE. Respondents with a masters or doctoral level of preparation were more likely to include mobilization, manipulation, neuromobilization, interferential current, hot packs, massage/soft tissue mobilization, education on posture/body mechanics, and/or prescription of general exercise/fitness programs in their plans of care than were physical therapists with a certificate or bachelors level of preparation (FIGURE). Similarly, respondents with ABPTS orthopaedic certification were more likely to include mobilization, manipulation, directional-preference exercises, neuromobilization, education on posture/body mechanics, and prescription of general exercise/fitness programs and/or core stabilization exercises than were respondents without certification (FIGURE).

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It is evident from these collective findings that professional preparation is associated with treatment decisions regarding the use of traction. The finding supports hypotheses generated by others that higher levels of professional preparation may alter the way in which physical therapists practice. Several studies,^28,32,44 for example, have reported that recent graduates and physical therapists with specialty certification differ in terms of knowledge, skills, and attitudes toward evidence-based practice from generalists or those with more experience. Mikhail et al,³² using clinical vignettes similar to ours to elicit responses from physical therapists about preferred interventions for LBP, reported that therapists who chose interventions with high evidence of effectiveness were more likely to have practiced less than 15 years. Manns et al²⁸ reported that recent graduates demonstrated better knowledge of evidence-based practice skills than physical therapists with more years of experience. Last, van Bodegom-Vos et al⁴⁴ reported that generalists had more difficulty interpreting guidelines for rheumatoid arthritis and that specialists had more knowledge and positive attitudes regarding their use. Additional studies have examined outcomes associated with training levels. Hart and Dobrzykowski,¹⁴ for example, suggested that physical therapists with ABPTS orthopaedic certification treated patients over fewer visits and with a lower overall cost than did noncertified physical therapists. Resnik and Hart³⁷ reported that physical therapists who achieved superior patient outcomes were more likely to have ABPTS orthopaedic certification, training through the American Academy of Orthopaedic Manual Physical Therapists, or manual therapy certification than were those who achieved more moderate patient outcomes. Collectively, there is a growing body of evidence that higher levels of professional preparation influence clinical decision making and, potentially, patient outcomes. Our findings suggest, similarly, that one's level of degree attainment and/or ABPTS certification may influence how traction is administered or incorporated into plans of care for patients with LBP.

Several limitations might have influenced our findings. First, the survey was conducted among a random sample of APTA Orthopaedic Section members. Findings may not generalize to nonmembers of the section or to non-APTA members. Second, we had a 25.5% response rate. The characteristics of those who responded to the survey (TABLE 1) might have differed from those who did not, and therefore external validity of the study may be flawed. Because the survey was administered anonymously, we had no method of determining who the nonresponders were. Third, the high proportion of reported traction users (76.6%) may reflect a response bias; perhaps traction users were more likely to respond than were non-traction users. Fourth, while we asked respondents to indicate their most commonly used traction delivery modes and parameters, including patient positioning, we acknowledge that such decisions are often dependent on the patient's condition, including symptom acuity and severity, and therefore the survey had limited capacity to detect how physical therapists make clinical decisions regarding the use of traction for managing LBP. Despite these limitations, the findings present a novel representation of lumbar traction usage among physical therapists in the United States.

Conclusion

While systematic reviews and clinical practice guidelines generally do not provide support for spinal traction in managing LBP without signs of nerve root compression, physical therapists in the United States commonly use traction. Most employ traction consistent with a classification system that preliminarily identifies patients in whom traction may provide benefit, yet approximately one third of respondents indicated traction usage that would be contrary to that classification. Additionally, our findings imply that physical therapists use a variety of traction delivery modes and parameters, dependent on patients' conditions, and use traction as part of comprehensive plans of care incorporating multiple intervention modes. Last, professional characteristics (professional education levels and ABPTS orthopaedic clinical specialist credentialing) are associated with traction usage.

Key Points