INTRODUCTION

Patients with intractable lumbar radiculopathy, due to a lumbar disc herniation, require surgery. Lumbar discectomy is the standard of care. This invasive technique aims to release the pressure on the nerve caused by a prolapsed disc, while minimizing scar tissue formation, avoiding nerve damage and biomechanical destabilization.¹ Rehabilitation following lumbar disc surgery has received far less attention than the operation itself. One could speculate that this is because after lumbar disc surgery the problems have been resolved and, therefore, rehabilitation is unnecessary. The reality is that in the long term too many patients still show considerable symptoms, reduced daily functional capacities, and disability.^2,³ In other words, surgery to remove the lumbar disc protrusion does not solve all back or leg problems and a substantial number of patients continue to suffer residual complaints. That is, complaints remain or return after surgery.

In general, the success rate of lumbar disc surgery varies from 60% to 90%.⁴^–⁶ It has been reported that, after lumbar disc surgery, 22–45% of patients experience residual leg pain and 30–70% have residual low back pain.⁷^–⁹ The range of these statistics reflects the different inclusion criteria for lumbar disc surgery and the various definitions of a successful outcome. It is often not clear from these studies what kind of post surgical care, if any, was provided to subjects in a particular study.

Very specific and individualized rehabilitation is an important tool that can minimize these remaining complaints. In particular, active treatment options could be important in maximizing patients’ functional status. This chapter will focus on the active rehabilitation after lumbar discectomy. The first part of this chapter will briefly discuss the controversial diagnosis of ‘failed back surgery syndrome’ and will explain possible reasons for these less favorable outcomes. In the second part, scientific evidence regarding postoperative rehabilitation programs following lumbar disc surgery will be highlighted. For this purpose, randomized controlled trials as well as nonrandomized controlled trials were considered. This is in line with the evidence-based approach because these designs are most appropriate for establishing sound evidence. This chapter will conclude with the proposal of a treatment protocol, which when possible, is based on the evidence as described in the second part of this chapter.

A ‘FAILED’ SURGERY?

For the situation where complaints remain or return, the term ‘failed back surgery syndrome’ has been used.^10,¹¹ This is a controversial term.^12,¹³ The authors agree with Verbeek¹³ that this term is not particularly helpful and even authors of articles who use these diagnostic terms admit that they are better avoided since they do not help to identify a cause or a treatment. After all, the only characteristics that these patients share are that they have been operated on for a lumbar disc surgery and that back-related complaints or leg pain remained or returned at some point after the operation. In contradistinction to Verbeek, the authors think that the term non-specific low back pain for this condition might also be somewhat misleading because that term is used for the general situation where the so-called ‘red flags’ have been excluded. The authors propose the term ‘residual complaints following lumbar disc surgery,’ because in the opinion of the authors that describes the situation most appropriately. First of all, it has not the negative connotation (both for surgeons and patients) that the surgery has ‘failed,’ but on the other hand it acknowledges the fact that there has been a surgery.

Different underlying mechanisms before, during, and after surgery have been described that could explain the persistent symptoms, the reduced daily functional capacities, and the disability inherent in this group of patients. Knowledge of these mechanisms is important to understanding the rationale of the proposed treatment strategy.

Before surgery

Before surgery, many patients have a long history of recurrent low back and leg pain.

Panjabi ¹⁴ assumes that, as a result of injury, degenerative disc disease and muscle weakness, the control over the neutral zone of the spinal segment is decreased, which may lead to instability. The herniated disc as part of the degenerative cascade¹⁵ affects the stability of the spine: an increase in neutral zone to range of motion ratio in the different loading directions is reported.¹⁶ The stability around the spinal segment is conserved by the sensory-motor control system.¹⁷ There is extensive evidence of changes in both of these systems in patients with low back pain. After the first episode of low back pain, the lumbar multifidus, which is an important stabilizer, is inhibited and does not spontaneously recover, even when the patient is asymptomatic.¹⁸ Furthermore, as a result of a herniated disc, abnormal changes in the characteristics and the activity of the paraspinal muscles are observed on the involved side. In addition, the contraction of the tranversus abdominus muscle, the other important stabilizer, is altered and delayed in patients with low back pain when performing upper and lower limb movements, leading to inefficient muscular stabilization of the lumbar spine.¹⁹ Lumbar proprioception, postural control, and feed forward control of the paraspinal muscles seem to be impaired in patients with sciatica.²⁰ In general, these patients often have a long medical history of pain and functional limitation, which can lead to long-term disability, antalgic posture, muscle imbalance, and reduced cardiovascular capacities.²¹ Other factors that play an important role, which are superimposed upon these neuromusculoskeletal abnormalities, include psychological influences such as anxiety or problems at work. Disability and patients’ expectation regarding the surgery have also been reported.^10,^22,²³

During surgery

During surgery the functional spinal unit will be altered. The lumbodorsal fascia is incised, the paraspinal muscles are dissected and elevated off the spinous process, a portion or the entire lamina is removed, and the ligamentum flavum is incised. Depending on the size and location of the herniated fragment, a laminectomy or facet-otomy is necessary.²⁴ The annulus fibrosis is also incised. It is obvious that injury to these tissues will necessarily interrupt the biomechanical integrity of the functional spinal unit. Another concern develops as a result of retraction of the paraspinal muscles. Even with careful dissection, damage to the medial branches of the posterior rami of the spinal nerves and denervation of the multifidus muscle can occur.²⁵ In those instances in which the injury presumably results from ischemia, a risk factor for nerve root injury results and, moreover, the neural damage does not necessarily spontaneously recover.²⁶ Of course, if the medial branch was surgically lysed, the probability of recovery is even lower.

After surgery

In the first period after surgery, local tissue response to the surgical intervention is detected on MRI and considered as normal.²⁷ This postoperative edema gradually decreases at 3 weeks and may last up to 6 months. There is a plethora of evidence documenting the decreased stability of the lumbar motion segment as a result of surgical intervention. In the immediate postoperative period, disc height loss may be detected²⁷ but generally no gross instability is reported. However, in the long term, even if an increase of motion does not occur shortly after surgery, reduced stiffness of the spine is observed, resulting in some degree of increased spinal motion.²⁸ Repetitive loading of the spine and the presence of scar tissue appear to be two of the major factors for the development of spinal instability.²⁹ Other factors that contribute to spinal instability include a higher load on the posterior elements,³⁰ increased development of degenerative spondylosis,³¹ and instability of the level above.²⁸ Evidence shows that the sensory-motor control system that, in normal conditions, can compensate for this acquired instability may fail to provide adequate control. A loss of muscle support and disturbed innervation is observed as a result of low back pain and sciatica in conjunction with the effects of the operative procedure.³² The deep back muscles not only stabilize the local segment, but also contribute to spinal stability as a whole. The instability is reinforced, leading to increased mechanical strain and further injury. With respect to the neurological deficits, immediate recovery is observed in a number of patients, as a result of the resolution of nerve root ischemia, but in a number of patients the paresis and the sensory disturbance do not spontaneously recover.³³

For a portion of patients that experience residual complaints following lumbar disc surgery there is no real diagnosis and no specialist or operation which can simply stop the pain.^10,^11,^34,³⁵ For those patients, and certainly for any patient with primary postoperative axial pain, the main outcome or goal of the rehabilitation program should be aimed at restoring normal function during activities of daily living and/or work. But what is the evidence for these kinds of rehabilitation programs?

EVIDENCE REGARDING POSTOPERATIVE REHABILIATION PROGRAMS

In the international literature there is a surprisingly wide variation in the content of rehabilitation programs.³⁶^–³⁸ Despite many plausible theories on the effectiveness of active, as well as passive, interventions following lumbar disc surgery, sound evidence is lacking. The choice of a specific method of rehabilitation is mainly based on the personal experience of care providers or on the results of studies of generally poor methodological quality. It has been suggested that passive treatment modalities should have no place in rehabilitation following first-time lumbar disc surgery and that active treatment is of paramount importance.³⁹ Indeed, an active rehabilitation program is considered to enhance a patient’s independence from healthcare services in the long run. Here, the focus will be on the evidence regarding active rehabilitation programs.

Methods

In a systematic review that assessed the effectiveness of such programs used in the rehabilitation of patients following lumbar disc surgery,⁴⁰ relevant randomized controlled trials (RCTs) and nonrandomized controlled clinical trials (CCTs) were included. This systematic review was conducted according to the method guidelines of the Cochrane Back Review Group.⁴¹ For this chapter, the literature was updated by searching PUBMED through December, 2003. RCTs or CCTs were included if they used at least one of the four primary outcome measures that were considered to be important, that is: (1) pain (e.g. VAS), (2) a global measure of improvement (overall improvement, proportion of patients recovered, subjective improvement of symptoms), (3) back pain-specific functional status (e.g. Roland Disability Questionnaire, Oswestry Scale), and (4) return to work (return to work status, days off work). Outcomes of physical examination (e.g. range of motion, spinal flexibility, degrees of straight leg raising or muscle strength), behavioral outcomes (e.g. anxiety, depression, pain behavior), and generic functional status (SF-36, Nottingham Health Profile, Sickness Impact Profile) were considered as secondary outcomes. Other outcomes such as medication use and side effects were also considered.

In assessing the quality of the included studies, the criteria list recommended in the method guidelines for systematic reviews by the Cochrane Back Review Group was applied.⁴¹ Only items reflecting the internal validity were used in assessing the quality of the included studies. One point was scored for each item in which a satisfactory response was obtained, and high quality was defined as fulfilling at least five of the validity criteria.

Internal validity criteria are:

1a. Method of randomization,

1b. Concealment of randomization,

2a. Dropout rate during the intervention period,

2b. Withdrawals during follow-up,

3. Co-interventions avoided or equal,

4. Blinding of patients,

5. Blinding of outcome assessment,

6. Blinding of care providers,

7. Intention-to-treat analysis,

8. Compliance,

10. Adequate length of follow-up

For summarizing the evidence, a rating system consisting of four levels of scientific evidence was used.

1. Strong evidence – provided by generally consistent findings in multiple high-quality RCTs.

2a. Moderate evidence – provided by generally consistent findings in multiple low-quality RCTs.

2b. Moderate evidence – provided by generally consistent findings in multiple CCTs.

3. Limited or conflicting evidence – only one RCT or CCT (of either high or low quality) or inconsistent findings in multiple RCTs or CCTs.

4. No evidence – no RCTs or CCTs.

The treatments are clustered here according to the timing of the start of treatment. In total, 15 studies were included, eight of which were of high quality.

Results

Active rehabilitation programs that start immediately postsurgery

Two studies assessed neural mobilization. A high-quality RCT ⁴² added an active and passive neural mobilization program to a standard 6-week physical therapy program that consisted of isometric and dynamic exercises. These exercises were increased in intensity from day 1 postsurgery as tolerated. The control group received the same standard physical therapy without the neural mobilization. This study revealed evidence that adding a neural mobilization program to a standard physical therapy program does not provide any additional benefits on any of the main outcome measures (level 3) on both short-term and long-term follow-up. This constitutes limited evidence (level 3) since there is only one high-quality RCT supporting this conclusion.

A low-quality RCT ⁴³ compared an intensive 7-day auto-assisted straight leg raise (SLR) regime for eight times a day with a 2-hour interval with a mild straight leg raise regimen that performed this same exercise only once a day for 7 days. This study revealed no significant differences between the two neural mobilization programs on pain, disability, or SLR at the 1-week and the 6-week measurement. No data were presented with regard to re-operation rates. Hence, there is limited evidence (level 3) that an intensive straight leg raise regimen is no more effective than a mild straight leg raise regimen.

A high-quality RCT ⁴⁴ evaluated an intensive exercise program that consisted of increasing daily activities, home training (mobilization, trunk strengthening) and later mainly intensive muscle strengthening exercises and cardiovascular exercises. The control group received no increase in daily activities, exercises only once a day, and no promotion of cardiovascular exercises. The results show that there are no statistically significant differences on any of the primary outcome measures, but some differences of the secondary outcomes. There was one re-operation (3.4%) in the intervention group and 2 re-operations (6.5%) in the control group. This is limited evidence (level 3) that there is no difference in effectiveness between an intensive exercise program and a less active program in the long term for global perceived effect, pain, and return to work.

Active rehabilitation programs that start 4–6 weeks postsurgery

Two high-quality RCTs ^39,⁴⁵ and one low-quality RCT⁴⁶ compared intensive exercise programs with mild exercise programs. The two high-quality RCTs reported no statistically significant differences between groups in overall improvement at 12-month follow-up. The low quality RCT did not include a long-term follow-up. All three studies showed a statistically significant difference on functional status in favor of the intensive exercise program on short-term follow-up and in one study⁴⁵ on long-term follow-up. In the two high-quality studies return to work and daily activities were statistically significantly better in the intensive exercise programs in the short-term but not over the long term. The RCTs by Danielsen⁴⁵ and Yilmaz⁴⁶ revealed a statistically significant improvement in short-term pain relief in favor of the intensive program (but not long-term⁴⁵). Furthermore, Danielsen⁴⁵ observed 1-year re-operation rates that were negligible.

The above translates to strong evidence (level 1) that intensive exercise programs are more effective in improving functional status and faster return to work in short-term follow-up and there is strong evidence that on long-term follow-up there is no difference between interventions with regard to overall improvement. There is moderate evidence (level 2) that intensive exercise programs are more effective for pain relief in the short term. For all other primary outcome measures there is conflicting evidence (level 3) with regard to long-term benefit.

One high-quality RCT ⁴⁷ compared a behavioral graded activity program that was based on operant treatment principles and was time contingent (time dependent) with usual care as provided by physical therapists. On the post-treatment measurement, 67% of the patients treated with care as usual had recovered versus 48% of the patients treated with behavioral graded activity. This 19% difference was statistically significant. On long-term follow-up, 73% of patients receiving care as usual and 75% of patients receiving behavioral graded activity had recovered. This difference was no longer statistically significant. On all other main outcome measures there were no statistically significant or clinically relevant differences. This study provides limited evidence (level 3) that there are no long-term differences in effectiveness between a behavioral graded activity program and usual care as provide by physical therapists.

One low-quality RCT ⁴⁸ compared a supervised exercise program to home exercises. Both interventions incorporated the same exercises and at the same intensity. Re-operation rate was negligible in both groups. There is limited evidence (level 3) that supervised exercises and home exercises are equally effective on global perceived effect, disability, pain, and mobility.

One low-quality RCT ⁴⁹ added horseback riding (three times per week for 20 minutes per session) to an intensive 4-week rehabilitation program. There were no statistically significant differences for overall improvement in the short term. (No long-term follow-up was performed.) There was a statistically significant more rapid return to work in the intervention group. There were no statistically significant differences in pain and physical measures. This study provided limited evidence (level 3) that adding therapeutic horseback riding to a rehabilitation program is effective for return to work, but not for overall improvement.

One low-quality RCT ⁵⁰ compared a multidisciplinary rehabilitation program that consisted of sessions with a physical therapist, psychiatrist, occupational therapist, psychologist, social worker, and an intensive back training with usual care. At 1-year follow-up, there were no statistically significant differences between groups on global perceived effect, sick leave, or re-operation rate (3.7% in both groups). This study offered limited evidence (level 3) that multidisciplinary rehabilitation and usual care are equally effective.

One low-quality CCT ⁵¹ added aerobic exercises to a treatment program. All outcome measures were performed only at 3 months. This is limited evidence (level 3) that adding aerobic exercises to a treatment program is not more effective on functional status, pain, and depression than exercises alone.

Rehabilitation in an occupational setting

Two studies specifically included patients in a work setting. One high-quality RCT ⁵² compared a multidisciplinary rehabilitation-oriented approach in insurance medicine with usual care. This work provides limited evidence (level 3) that a rehabilitation-oriented approach in insurance medicine is more effective in affecting return to work at long-term follow-up. One low-quality CCT ⁵³ assessed a functional restoration program versus usual care. This study does not present comparisons between groups.

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