The efficacy of lumbar spine surgery (including fusion and decompression) remains unknown as to our knowledge there are no published placebo-controlled trials,1,2 but rates of surgery are rising. In Australia, there was an increase in the annual rates of fusion (1.3–8 per 100,000) and decompression (19.0–22.1 per 100,000) from 2003 to 2013.3 In the United States, there was a 2.8–3.0-fold increase in the annual rates of fusion from 2000 to 2009.4

In terms of rehabilitation following lumbar spine surgery, low- to very low-certainty evidence (Cochrane review, 5 trials, n = 272 participants) suggests there are small, short-term benefits of exercise therapy if it commences 4–6 weeks following lumbar disk surgery (e.g. standard discectomy, microdiscectomy) and involves 8–24 sessions.5 Rehabilitation that starts before four weeks post-operatively appears to have little to no beneficial effect.5,6

Post-operative physical therapy appears widely utilized following lumbar spine surgery but there is variation in how much physical therapy is provided. A survey of 86 spine surgeons in the Netherlands found most spine surgeons always refer to physical therapy following lumbar disk surgery (65%) and nearly half believe post-operative physical therapy is essential (45%).7 A survey of 51 spine surgeons in the United Kingdom found nearly half (45%) refer their patients to physical therapy following lumbar spine surgery and these patients typically receive 3–6 physical therapy sessions.8 A survey of hospital physical therapy departments in the United Kingdom (n = 69 departments)9 found nearly 50% commenced patient rehabilitation within 0–4 weeks following lumbar discectomy (contrary to the best available evidence.)5 The study also found that 63% of patients receive 5–10 physical therapy sessions before discharge, while 12% receive more than 10 sessions.

No study to our knowledge has investigated variation in the number of physical therapy sessions patients receive following lumbar spine surgery in a workers’ compensation setting, or in Australia. Filling this evidence gap will provide information on how patients in this setting are managed, facilitating comparison to other healthcare settings as well as stimulating dialog about appropriate care pathways. It could also give insight into whether patients are receiving appropriate care according to the best available evidence. Determining the number and timing of physical therapy sessions received following lumbar spine surgery will help us understand whether some patients are receiving excessive, insufficient, or timely care following surgery. This has implications for potential implementation strategies to improve the quality and value of physical therapy in this setting.

The primary aim of this study was to describe the number of physical therapy sessions patients in a worker's compensation cohort receive in the 12 months following lumbar spine surgery, stratified by type of surgery (lumbar fusion versus lumbar decompression). The secondary aims were to:

• i.

  Describe the number of physical therapy sessions patients receive up to 12 months post-operatively and cost of this physical therapy, by year (2010–2017).

• ii.

  Describe the time to initiation of post-operative physical therapy and the percentage of patients who commence post-operative physical therapy at different time points, by year (2010–2017).

• iii.

  Describe the number of physical therapy sessions (continuous variable) and physical therapy utilization at 12 months post-operatively (dichotomous variable) by return-to-work status.

Patients who had lumbar spine surgery funded by NSW Workers’ Compensation between 2010 and 2017 had, on average, 22 physical therapy sessions to 12 months post-operatively (costing AU$1902 and US$1217 per patient). One-third had 9–24 sessions, one-quarter had 25–50 sessions, and one in 10 had > 50 sessions. Patients who had fusion had more post-operative physical therapy and higher physical therapy-related costs compared to those who had decompression. Although the number of physical therapy sessions patients received following lumbar spine surgery remained stable between 2010 and 2017, the time to initiate postoperative physical therapy increased. One in four patients were still receiving physical therapy at 12 months, and most of these patients were not working.

Some patients who have lumbar spine surgery funded by NSW Workers’ Compensation are receiving physical therapy treatment beyond what may be necessary. Effective rehabilitation programs following lumbar spine surgery typically involve 8–24 sessions,5 and in our sample 35% of cases had 25 sessions or more and one in 10 had > 50 sessions in the 12 months following surgery. This suggests that some of the funded physical therapy care received by the workers may be unnecessary. Modest return-to-work rates at 12 months following surgery and the percentage of patients still receiving physical therapy at 12 months (24%) also raises questions about the effectiveness of lumbar spine surgery and post-operative physical therapy for some patients.

The median number of days to initiation of post-operative physical therapy increased from 1 to 2 days between 2010 and 2014 to 12–17 days between 2015 and 2017. This increase could be explained by possible uptake of new evidence that emerged in 2014. A 2014 Cochrane review found low- to very low-certainty evidence that exercise therapy improves pain and function in the short-term compared to no treatment, but only if exercise was delayed until 4–6 weeks post-operatively.5 Although there was an increase in the percentage of patients who commence physical therapy at least 6 weeks following surgery over time, there remains an evidence-practice gap. Since 2015, over 60% of patients still commence post-operative physical therapy within 4 weeks of surgery.

Data on physical therapy utilization following lumbar spine surgery are limited. If we compare our findings to the findings of a UK study,9 there appears to be substantial variation in the number of post-operative physical therapy sessions patients receive. The UK study, a survey of 69 outpatient physical therapy departments in the National Health Service (NHS), found 40% of patients in that setting receive 5–6 physical therapy sessions following lumbar disk surgery, while only 12% receive more than 10 sessions.9 Our study found that most patients in the workers’ compensation setting have 9–24 (30.5%) or 25–50 physical therapy sessions (24.9%) to 12 months post-operatively, and 10.6% have > 50 sessions. Variation in the amount of physical therapy provided could be explained by the increased clinical complexity of compensable patients and financial incentives to provide more care for these patients.

While numerous studies have explored the amount of physical therapy provided to patients with musculoskeletal conditions, most have reported substantially lower physical therapy utilization compared to our study. An audit of clinical notes for 200 patients with acute low back pain treated at a community-based physical therapy department in the United Kingdom found physical therapists provide a median of 5 sessions per patient (IQR: 4–7).15 A survey of 324 physical therapists in New Zealand found most physical therapists (67%) provide three treatments for patients with acute low back pain.16 For chronic low back pain, three retrospective audits of clinical notes (n = 200 patients in the United Kingdom,15n = 1254 in the Netherlands,17 and n = 3587 in the Netherlands18) and one survey of Irish physical therapists (n = 280)19 found that most physical therapists provide 6–10 sessions, with a small percentage providing over 20 sessions (< 10%). More data on practice patterns for physical therapists working with compensable patients is needed to better understand whether the relatively high amount of treatment provided in our sample can be explained by the practice setting.

Ensuring physical therapists provide care according to the best available evidence for compensable patients is vital. In NSW, there were nearly 5000 major work-related back injuries in 2015/16, costing over AU$99 million and representing 20% of all major workplace injuries.20 The lack of data on physical therapy practice patterns in this setting highlights the need for more research in this space. A separate issue yet to be investigated is what drives patterns of physical therapy practice in settings involving compensable patients. Physical therapists managing patients funded by NSW Workers’ Compensation are initially approved to provide eight sessions. Physical therapists do not need to justify the necessity of these sessions and can request additional sessions (in blocks of eight) if needed. Having physical therapy sessions approved in blocks through a relatively straight-forward process may be contributing to ongoing treatment in this setting despite any measurable improvement in outcomes such as return to work. Future qualitative research is needed to better understand the barriers and facilitators to providing evidence-based care in this setting and inform the development of interventions to improve physical therapy practice if necessary.

Our sample represents almost the entire population of patients who underwent elective lumbar spine surgery funded by NSW Workers’ Compensation between 2010 and 2017. A large sample size and 8 years of data allowed us to explore how physical therapy utilization and costs have changed over time. A key limitation is that we used administrative, billing data so were unable to discern whether physical therapy improved patient outcomes. We also had no data on the type of physical therapy provided (e.g. exercise, electrotherapy) so could not determine whether physical therapy provided following lumbar spine surgery aligns with current best available evidence. Because our data were limited to claims funded by NSW Workers’ Compensation, physical therapy treatments received after claims had closed or outside the scheme would not be detected.

There is substantial variation in how many physical therapy sessions patients funded by NSW Workers’ Compensation receive in the 12 months following lumbar spine surgery in Australia, the cost of this care, and the time from surgery to the initiation of physical therapy. On average, patients received 22 physical therapy sessions and generated physical therapy-related costs of AU$1902 and US$1217 per patient in the 12 months following lumbar spine surgery. For most claimants, the number of physical therapy sessions received aligned with the best available evidence. However, some patients may have received an excessive amount of physical therapy and initiated physical therapy too early. One in three patients received >24 sessions, one in 10 received >50 sessions, one in four were still having physical therapy by 12 months, and over two-thirds commenced physical therapy within 4 weeks of surgery. Physical therapists should reflect on these data when planning the management of patients following lumbar spine surgery. Patients who received > 50 sessions and who were still having physical therapy by 12 months were least likely to be working. Future research is needed to determine the value of physical therapy being provided in this setting.