Randomized Controlled Trials: Questions, answers and ... Fusion...However, randomised controlled clinical trials have shown that fusion procedures are not significantly more effective

FAILED FUSION SURGERY TREATED BY TRANSFORAMINAL ENDOSCOPIC

LUMBAR DECOMPRESSION & FORAMINOPLASTY

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Title

Failed Fusion Surgery treated by Transforaminal Endoscopic Lumbar

Decompression and Foraminoplasty – a 3 year prospective cohort study

Authors

Martin TN Knight, MD, FRCS, MBBS*

Ingrid Jago, SRN ONC RNT Cert Ed FETC*

Christopher Norris, PhD MSc MCSP†

Affiliations

* The Spinal Foundation, UK

† Norris Associates, UK

Contact details

* Sunnyside, Highfield Road, Congleton, Cheshire, CW12 3AQ

Tel: 01260 296 346

Fax: 01260 289 019

Email: [email protected]

† 16 Lawton Street, Congleton, Cheshire, CW12 1RP

mailto:[email protected]



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Abstract

Background

Treatment of back pain is often unsuccessful due to suboptimal identification of the

pain source. Aware state Transforaminal Endoscopic Lumbar Decompression and

Foraminoplasty (TELDF) offers a direct means of localizing and treating pain

persisting after fusion. This study examines the outcomes of TELDF in a cohort of 65

patients after Failed Fusion Surgery.

Methods

For 3 years prospective data were collected on 65 consecutive patients with failed

but immobile fusions who underwent TELDF. The level responsible for the

predominant presenting symptoms was defined by spinal probing and discography or

differential discography. Patients then underwent TELDF at the appropriate level.

Outcomes were assessed using the Visual Analogue Pain Scale (VAPS), the

Oswestry Disability Index (ODI), the Prolo Activity Score, SF36 Health Survey and

Zung Depression Index.

Results

Cohort integrity was 100%, 98% and 92% at 1, 2 and 3 years respectively. VAP

scores improved from a mean of 8.2 at baseline to 3.0, 3.1 and 3.2 at years 1, 2 and

3 respectively. ODI improved from a mean of 40 at baseline to 13.3, 13.4 and 13.2 at

years 1, 2 and 3 respectively. In total, 86% of reviewed patients fulfilled the definition

of “Good Clinical Impact” at year 1, 78% at year 2 and 76% at year 3. Based on Prolo

score, 44 patients (68%) were able to return to work or retirement activity post-

TELDF. Complications of TELDF were limited to transient nerve irritation, which

affected 18% of the cohort.



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Conclusions

TELDF is an effective intervention for the treatment of severely disabled patients with

multilevel Failed Fusion Surgery, resulting in considerable improvements in

symptoms and function.

Clinical Relevance

The efficacy of TELDF in patients with immobilised segments suggests that

extradiscal foraminal pathology may be a major cause of lumbar axial and referred

pain.

Keywords

Failed Fusion Surgery, Endoscopic Decompression, Foraminoplasty, Foraminotomy,

Differential Discography, Spinal Probing



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Introduction

Back pain is a common condition in the developed world1 but treatment is often

unsuccessful due to inaccurate identification of the pain source.2-12 Localization of

back pain conventionally relies upon clinical examination, X-ray findings, CT-

myelography, CAT and MRI scan results and, in certain centres, discography. With

the exception of discography, these techniques are indirect methods of assessment

that are not able to demonstrate definitively correlation between a given abnormality

and the patient‟s predominant presenting symptoms.

Conventional wisdom purports that back pain arises from the disc13 (discogenic pain)

or the facet joints14-23. Where physiotherapy and conservative measures (including

injections and nerve ablations) fail, the patient may be referred for an intervertebral

fusion to immobilise the disc24-28 and facet joints. However, randomised controlled

clinical trials have shown that fusion procedures are not significantly more effective

than regimens of exercise and Cognitive Behavioural Therapy29-34. Only 63% of

patients are satisfied with the results of such therapy and fusion is attended by

complications in 11–18% of interventions29-34.

The persistence of symptoms in patients undergoing intervertebral fusion may be due

to pain arising from pathology in the spinal foramen rather than the intervertebral disc

or facet joints. With the exception of transforaminal lumbar interbody fusion most

commonly-used fusion techniques do not address the entirety of foraminal pain

sources, which could explain the equivocal results of spinal fusion surgery.

Transforaminal endoscopic lumbar decompression and foraminoplasty (TELDF) is a

minimally invasive technique that allows real time, aware-state evaluation of the



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foraminal zone, disc and epidural space to identify clinically relevant foraminal

pathology and to treat such using endoscopic foraminotomy and foraminoplasty.

This prospective study assesses the outcome of aware state TELDF as a means of

treating patients with Failed Fusion Surgery by monitoring clinical outcome over a 3

year post-operative period.

Methods

Between January 2000 and 2001, prospective data were collected on 65 consecutive

patients with failed secure fusion surgery who underwent TELDF at the UK Spinal

Foundation.

Eligibility criteria

Patients presenting with a secure multi-level lumbar fusion performed at least 1 year

previously with persistent back, buttock or leg pain despite at least 3 months of

muscle balance physiotherapy were eligible to participate in the study. Patients were

excluded if intersegmental movement was detected on flexion/extension standing

and sitting X-rays or if they were pregnant, evidenced facet joint cysts, Cauda Equina

syndrome, systemic neurology or spinal tumours.

Eligible participants were consented for a staged procedure consisting initially of

aware state spinal probing and discography on two or more spinal segments to

establish which segment concordantly reproduced their back pain or peripheral

radiation. If the patient was unable to define the source of their predominant pain

then they proceeded to Differential Discography35-37. Once the spinal level

responsible for the patient‟s predominant presenting symptoms had been identified



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either by spinal probing and discography or by differential discography, patients

progressed to TELDF at the appropriate level.

Surgical procedure

TELDF was performed under aware-state analgesia with the patient in the prone

position on a humpback radiolucent table extension. It consisted of two phases of: 1)

transforaminal spinal probing and discography; and 2) TELDF.

Transforaminal spinal probing and discography procedure

Under X-ray guidance, a spinal probing cannula (Arthro Kinetics Plc) was inserted

into the spinal foramen via a posterolateral approach optimized by the use of a

specially designed X-ray alignment jig. The distribution of evoked sensations and the

degree to which they reproduced the patient‟s predominant presenting symptoms

was recorded on a data sheet by a trained observer during probing of the

paravertebral musculature, the lateral facet joint surface, the anterior facet joint

margin, the interval between the anterior facet joint margin and the annular (disc)

wall. Radio-opaque dye (Omnipaque® 240 [Nycomed Ltd, Romsey, Hampshire,

England]) was then injected into the intervertebral disc to evaluate its integrity. The

pattern of dye distribution, acceptance volume and leakage were recorded, together

with pain reproduction during discography pressurization.

Evoked sensations that reproduced the patient‟s predominant presenting symptoms

were classed as „concordant‟ symptoms. Patients in whom spinal probing and

discography demonstrated concordant symptoms proceeded immediately to TELDF

at the level evidencing the most concordant symptom reproduction. Where symptoms

were discordant (similar but not identical to the predominant presenting symptoms) or



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overlapping (symptoms arising at more than one spinal level), patients progressed to

differential spinal probing and discography35-37, in which steroid (80mg

Depomedrone) was inserted at the most responsive spinal level and anaesthetic

(2mls of 0.5% Naropine) was inserted at the adjacent level. Where the acceptance

volume was low, a radio-opaque dye-guided radiculogram was performed. Care was

taken to keep the medication located to the segment under evaluation. The temporal

modification of individual symptoms determined the source of the pain and the site

for subsequent TELDF.

TELDF procedure

Using the Arthro Kinetics Plc system, the needle used to perform discography was

removed from the spinal probing cannula and replaced with a long guide wire. An

endoscope dilator and cannula were railroaded along the guide wire to the foramen

under X-ray control. The dilator was removed and the endoscope was inserted to

offer visualization of the foraminal contents. A side-fire irrigated laser probe (Lisa

Laser Gmbh) was inserted through the endoscope‟s working channel. The laser was

used to define the margins of the foramen and to progressively remove tissue in the

Safe Working Zone38 until the nerve could be mobilized and the endoscope cannula

inserted securely and safely. The superior foraminal ligament35, 37, was defined and

removed. Any osteophytes were then removed with burrs, reamers and the side-fire

laser. Perineural scarring was removed from the dorsal root ganglion to the inferior

pedicle and the dorsal root ganglion and the nerve were mobilized with a nerve root

retractor until free of tethering. The foramen was enlarged with trephines, powered

reamers and manual burrs until clear access to the epidural space was achieved.

Where indicated, protruding disc was removed with care to avoid exposing

intervertebral graft or cages. Where there was a contributory disc protrusion,

extrusion or sequestrum or radial tear, the disc was stained with indigo-carmine dye



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and a limited herniectomy of the disc material was performed. Only degenerate disc

material accessed endoscopically through a 3.5mm portal was removed. Where

necessary, shrinkage of the posterior annulus and sealing of local tears

(annuloplasty) was performed using the side-fire laser.

Once the nerve had been mobilized, it was returned to its natural pathway. After

insertion of Depomedrone 80mg and Gentamycin 80mg in the operation zone, the

wound was closed with a single suture.

Postoperative management

Patients were discharged the day of, or morning following, surgery. A muscle balance

physiotherapy staged regime was re-commenced on the first day following surgery,

amplified with neural mobilization drills and continued on a monitored self-help basis

for 3 months. Patients were reviewed at 6 and 12 weeks unless clinical symptoms

required closer supervision, and annually according to the study protocol.

Outcome measures

Patients used a pain mannikin to prioritize the predominant symptoms responsible for

most of their suffering and functional impairment. Three zones corresponding to

target symptom clusters were defined as: back pain; buttock, groin or thigh pain; and

below knee pain.

Symptoms were assessed using the Visual Analogue Pain Scale (VAPS). Functional

impairment was assessed using the Oswestry Disability Score (ODI) and Prolo

Activity Score together with the SF36 Health Survey and Zung Depression Index and

pain diaries at each review point.



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Outcomes of TELDF were assessed by analyzing the change in VAPS and ODI for

up to 3 years post-operatively. “Good Clinical Impact” (GCI) was defined as 50%

improvement in pain scores in all symptom clusters (back, buttock, groin, thigh and

legs) plus 50% improvement in ODI. Failure in any cluster denoted failure overall.

Patients were followed up annually with a full questionnaire that included the VAPS,

ODI, Prolo Score, SF36 Health Survey and Zung Index. Patients were additionally

reviewed where there was deterioration or upon demand.

Results

Baseline characteristics

A cohort of 65 consecutive patients was recruited into the study. A summary of their

baseline demographics is shown in Table 1. All patients had multilevel chronic

lumbar spondylosis with back or referred pain and multilevel degenerative disc

disease on MRI scan. All had undergone a lumbar fusion at 1–3 disc levels and had

been deemed untreatable by further surgery. All had been referred for chronic pain

management. Post-fusion diagnoses included compressive radiculopathy, lateral

recess stenosis, axial stenosis, graft failure, implant failure, perineural scarring and

persistent nerve memory pain or neuroplasticity.

Of the 65 patients in the cohort, 26 were unemployable due to the severity of their

symptoms. A further 24 patients were retired but deemed the quality of their

retirement severely degraded as a result of their symptoms.



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Table 1 Summary of baseline patient demographics & post-fusion treatment

* The symptom cluster responsible for most suffering and functional impairment; symptoms; other

symptoms may also be present

Total number of eligible patients 65

Age (years)

Mean SD

Range

53 9.2

42–81

Males 37

Predominant presenting symptom*

Back pain

Buttock, groin or proximal limb pain

Limb pain extending below the knee

Equivalent predominance of back, buttock and limb pain

Bilateral or oscillating limb pain

32

12

10

8

3

Duration of symptoms (years)

Mean SD

Range

9.2 4.2

5–27

Lumbar intervertebral fusion

1 level

2 levels

3 levels

30

32

3

Prior pain management

Post-fusion chronic pain management

Coping courses

Residential cognitive behavioural therapy

Eligible for dorsal column stimulator

65

35

22

12



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Prior surgical interventions

The cohort had undergone a total of 164 open spinal procedures addressing at least

230 discs, with a range of 1–6 procedures per patient (Table 2). A variety of different

fusion procedures had been performed. Importantly, however, none of the patients in

the cohort had undergone a transforaminal lumbar interbody fusion (TLIF).

Revision of the primary fusion had occurred in 16 patients and a separate procedure

to remove metal implants had been required in 7 patients, although the exact extent

of these procedures was not well documented.

Table 2 Prior surgical interventions

Number of levels

Procedure 1 2 3 Total

Discectomy 22 27 0 49

Decompression 7 8 0 15

Re-exploration 7 5 0 12

Primary fusion 30 32 3 65

TELDF outcomes

Spinal probing and discography was performed at levels ranging from L2 to S1. In 52

patients, spinal probing and discography evoked concordant symptoms and was

sufficient to identify the appropriate spinal level for TELDF. The remaining 13 patients

required differential discography to identify the spinal level responsible for their

predominant presenting symptoms. All patients proceeded to TELDF.



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No patients were lost to follow-up during the first year post-operatively. During year 2,

one patient was lost to follow-up, and an additional four during year 3 which sadly,

included two patients who died from causes unrelated to their spinal symptoms and

their data have not been included in the year 3 results. Cohort integrity was 100%,

98% and 92% at 1, 2 and 3 years respectively.

Symptomatic improvement

Patients treated with TELDF experienced a consistent and marked reduction in pain

that was maintained up to 3 years post-operatively, as shown in Figure 1. In total,

86% of reviewed patients fulfilled the exacting definition of “Good Clinical Impact” at

year 1, 78% at year 2 and 76% at year 3.

Figure 1 Mean VAP score from baseline to 3 years post-operatively

Functional improvement

Improvement in functionality, as assessed by the Prolo Score, is shown in Figure 2.

At baseline, over half the patients in the cohort were assessed at Category 4 or 5 of

the Prolo Scale, indicating significant impairment of function; only one was classed at



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Category 2, indicating limited impairment of function; and none were classed at

Category 1 (no functional restrictions of any kind). One year following TELDF, only

seven patients fulfilled the criteria for Categories 4 or 5 (including only one at the

most severe classification) and 46 patients (71%) were classed as Category 1 or 2,

indicating an ability to return to work or retirement activities on at least a part-time or

limited basis. These improvements were maintained. By years 2 and 3, no patients

were assessed at Categories 4 or 5 (indicating the most severe disability).

Figure 2 Prolo Score categorization from baseline to 3 year post-operatively

Functionality was also assessed using the Oswestry Disability Index, as shown in

Figure 3. This confirms the improvement in function sustained over the three year

period noted in the patients‟ Prolo Scores.



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Figure 3 Mean ODI score from baseline to 3 years post-operatively

Requirement for further intervention

During years 2 and 3, two patients experienced deterioration in their symptoms

attributable to the level of the original TELDF procedure, one of which was on the

opposite side to the procedure. Neither of these patients considered further surgery

was necessary.

During year 2, three patients experienced a deterioration in symptoms attributable to

another site within the fusion (i.e. due to residual pathology arising from the original

failed back surgery), increasing to five patients by year 3. Three of these patients

underwent further TELDF at the additional pain site within the fusion with „excellent‟

(≥90% improvement in VAP score) or „good‟ (≥50% improvement in VAP score)

outcomes.



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In year 2, three patients exhibited symptoms arising from disc levels adjacent to the

fusion, increasing to five in year 3. Three of these patients underwent additional

TELDF at the adjacent level with „excellent‟ and „good‟ outcomes.

This pragmatic use of additional TELDF at painful or deteriorated levels increased

“Good Clinical Impact” outcomes to 86% at year 1, 83% at year 2 and 85% at year 3.

Complications

Postoperatively 12/65 (18%) patients had flares marked by a transient recurrence of

their predominant presenting symptoms commencing a week after surgery and

lasting 2–4 weeks. During this period one patient had a transient recurrence of

numbness in the great toe and another had transient calf allodynia. These short-lived

symptoms are most likely due to irritation of the nerve in the spinal foramen as it

swells in the healing phase following surgery.

There were no cases of disc or wound infection, deep venous thrombosis, chest or

urinary infections or cardiac dysfunction. All patients were discharged the morning

following surgery.

Discussion

TELDF represents a novel approach to the treatment of Failed Fusion Surgery

because it is conducted in the aware state, allowing patient feedback to guide the

surgeon accurately to the source of pain. This improves diagnostic accuracy and

allows precise endoscopic targeting of the intervention with minimal disturbance of

surrounding tissues. The procedure can be conducted under local anaesthesia as a

day-case or with a single overnight hospital stay and does not require expensive



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implants. Due to its minimally invasive nature, TELDF can be used in the elderly and

in those with clinically significant co-morbidities.

In this cohort of 65 patients with Failed Fusion Surgery, TELDF demonstrated a

significant improvement in both symptoms and functionality that was sustained over 3

years. At all time points, over 75% of patients demonstrated a “Good Clinical Impact”.

Unlike many other studies, which use ≥20% improvement in symptoms or

functionality as an indicator of efficacy,41-43 “Good Clinical Impact” required a

minimum of 50% improvement in both pain and function outcomes. This definition

was based on observations in 150 patients35 who were asked if treatment had met

their expectations and made a meaningful improvement in their lifestyle. It was

evident that a reduction in overall pain was not enough unless all pain zones were

reduced and functionality was at least doubled. Despite using such a rigorous

endpoint, TELDF achieved positive outcomes in a severely disabled group of

patients, many of whom were elderly and suffering significant co-morbidity and all of

whom had been deemed untreatable by further surgery.

The “Good Clinical Outcome” result is supported by a clinically significant reduction in

VAP score (from a mean of 8.2 at baseline to 3.0, 3.1 and 3.2 at years 1, 2 and 3

respectively) and ODI (from a mean score of 40 at baseline to 13.3, 13.4 and 13.2 at

years 1, 2 and 3 respectively). The activity-related Prolo Score also indicates a

significant and progressive improvement: 44 patients in the cohort (68%) were able

to return to work or retirement activity post-TELDF (15 on a full-time basis and 29 in a

part time capacity). These findings indicate that TELDF is an effective technique

capable of improving both symptoms and function in patients with long-standing,

multi-level back or referred limb pain for whom other interventions had failed.



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Only one patient experienced deterioration of symptoms arising from the site of

TELDF, probably because adequate clearance of the scarring and bone impingement

could not be achieved and the nerve sufficiently liberated. The patient did not

consider further surgery necessary and the procedure was not, therefore, revised.

The revision rate to treat residual pathology arising from the original Failed Back

Surgery within the fused segments was 3/64 (5%) over the 3 year review. Similarly,

the requirement for surgical intervention in levels adjacent to the fused segments was

3/64 (5%). The aggravated degeneration above the fusion may be related to the

increased activity enabled by the primary TELDF procedure. The revision rate for

TELDF may be reduced in the future as improved instrumentation allows more rapid

and extensive surgery to be applied at additional levels during the same procedure

without diminishing the quality and completeness of nerve root liberation.

Complications of TELDF were limited to the transient recurrent irritation of the nerve

as it swelled in the healing phase following surgery within the narrow confines of the

minimally disturbed foramen. This affected 18% of the cohort but resolved

spontaneously with symptoms minimised with analgesia and Non Steroidal Anti-

Inflammatory Therapy.

The efficacy of TELDF in patients with long-standing back or referred pain despite

immobilised segments indicates that foraminal pathology (e.g. persistent nerve

irritation in the lateral foramen) rather than discal pathology may be a major cause of

back pain. Unlike most fusion procedures, TELDF comprehensively addresses

foraminal pathology through a combination of complete foraminotomy and

foraminoplasty: liberation of the nerve root from impingement or tethering,



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enlargement of the spinal foramen and correction of any misalignment of the nerve.

Further research on the role of foraminal pathology in chronic back pain is warranted.

In conclusion, TELDF has been shown to be an effective intervention for the

treatment of severely disabled patients with multilevel Failed Fusion Surgery,

resulting in considerable improvements in symptoms and function. Its efficacy in

patients with immobilised segments suggests that foraminal pathology may be a

major cause of back pain.



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Randomized Controlled Trials: Questions, answers and ... Fusion...However, randomised controlled clinical trials have shown that fusion procedures are not significantly more effective

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