Study protocol for effects of prone spinal decompression therapy in addition to Mckenzie exercises versus Mckenzie exercises only on pain and functional disability in lumbar radiculopathy–A randomized clinical trial

Abstract

BACKGROUND:

Lumbar radiculopathy, which affects both men and women equally, are associated with symptoms of back and leg pain that significantly impairs body functioning, walking ability, and quality of life. Therefore, determining the optimal treatment protocol is necessary. The objective of the study is to evaluate the efficacy of prone spinal decompression therapy (SDT) combined with McKenzie exercises compared with McKenzie exercises alone on pain and functional disability in patients diagnosed with lumbar radiculopathy.

MATERIALS AND METHODS:

A single-blinded randomized clinical trial will be conducted using simple randomization at university physiotherapy department. According to sample size calculation, we aim to recruit 44 participants aged between 25 and 55 years with lumbar radiculopathy. Participants will be allocated using computer generated method and will be randomized into 2 groups: Group A (SDT + McKenzie) and Group B (McKenzie only) and each session will be lasted for 20–30 min. Outcome measures include visual analogue scale, Roland Morris disability questionnaire, Tampa Scale of Kinesiophobia, Short Form-36, and patient satisfaction outcome. Global rating of change will be assessed post intervention. All outcomes measured will be evaluated at baseline, after 4 weeks (post intervention) and after week 12 (follow up).

RESULTS:

Based on the normality of the, parametric and nonparametric will be applied. ANOVA with Bonferroni post hoc will be used for follow-up analysis. Results will be reported with 95% confidence intervals and P values.

CONCLUSION:

If the findings support the combined approach, it may provide a superior conservative treatment option for lumbar radiculopathy.

Introduction

Low back pain (LBP) is a prevalent condition globally, affecting 1.2%–43% of the population, with rates in India reaching 60%–85%.[1] While lumbar radiculopathy, characterized by radiating pain due to nerve root compression, occurs in approximately 3%–5% of individuals and is often linked to intervertebral disc issues.[2,3] Despite various treatment options, including physical therapy and surgical interventions, standardized nonoperative guidelines remain scarce.[4,5] Among the various manual therapy techniques, Mechanical diagnosis and therapy or McKenzie method, focusing on directional preference exercises, has shown promise in centralizing symptoms, particularly with extension exercises.[6,7] Recent advancements have introduced spinal decompression therapy (SDT), a nonsurgical method that uses a computerized feedback system to decompress spinal nerve roots through targeted motorized segmental distraction. This technique reduces pressure within the intervertebral disc, facilitating nutrient delivery, enhancing intervertebral space, and restoring disc height. Additionally, SDT alleviates tension in the lumbar spine by relaxing tightened paraspinal muscles and ligaments.[8,9] While supine positioning is often preferred for traction, prone positioning can also be beneficial, as patient comfort and muscle relaxation are crucial for optimal results. A study found that sacrospinal muscle activity was significantly lower in the prone position, suggesting that this approach may be more effective for individuals with LBP.[10] This study aims to evaluate the effectiveness of McKenzie exercises alone and in combination with prone SDT on pain relief and functional limitations in patients with lumbar radiculopathy, as the benefits of this combined approach remain unclear.

Objectives:

To evaluate the efficacy of prone SDT and Mckenzie exercises compared to Mckenzie exercise alone on pain relief and functional improvement in patients diagnosed with lumbar radiculopathy.

Study novelty

SDT aims to reduce pressure on compressed nerve roots, while McKenzie therapy promotes symptom centralization through specific movements. This is the first study to give an insight into the efficacy of combined versus isolated interventions in lumbar radiculopathy, aiming to guide clinical decision-making.

Materials and Methods

Study design and setting

This study will be a single-blinded, randomized clinical trial conducted at the musculoskeletal outpatient department of the Institute of Physiotherapy, Srinivas University, from April 2024 to June 2025. The trial design adheres to the SPIRIT guidelines, ensuring methodological rigor and transparency.[11] Participants presenting with symptoms indicative of lumbar radiculopathy wil be recruited as per inclusion and exclusion criteria and assessed within this clinical setting after obtaining informed consent [Table 1].

Table 1.

Selection criteria

Inclusion Criteria		Exclusion Criteria
Referred by orthopedician		On medications (NSAIDS, Corticosteroids)
Male and female aged between 25 and 55		Red flags such as cancer, inflammation or any infection, need for urgent surgery due to cauda equina syndrome or worsening weakness
LBP with unilateral radiating pain for at least 3 weeks		Past surgical history on LS, hip or pelvis
Positive slump test		Deformities in spine
Positive SLRT at hip flexion 30°–70°		Spondylolisthesis
Repeated movement testing centralization of symptoms		Multiple level disc herniation and degeneration
VAS score 4 or more		Pregnancy
Sensory abnormalities and motor weakness		Vascular, pulmonary or coronary artery disease

VAS=Visual analog scale, SLRT=Straight leg raise test, LS=Lumbar spine, NSAIDS=non-steroidal anti-inflammatory drugs, LBP=Low back pain

Study participants and sampling

Eligible participants include male and female individuals aged 25–55 years experiencing LBP with unilateral radiating symptoms persisting for at least 3 weeks. Participants will be included if they present with sensory abnormalities, motor weakness, symptom centralization with repeated movements and visual analogue scale (VAS) score greater than 4.[8,12] Participants will be referred by orthopedic specialists, with or without imaging (X-ray/MRI) for the study.[13,14] Diagnosis will be supported by positive findings on the Straight Leg Raise Test (30°–70° hip flexion) and the Slump Test.[15]

Exclusion criteria include red flags such as malignancy, infection, cauda equina syndrome, previous spinal or pelvic surgeries, spinal deformities, spondylolisthesis, multilevel disc degeneration, pregnancy, and systemic vascular or pulmonary diseases.[10]

Using a confidence level of 95% and a power of 80%, a sample size of 44 (22 per group) including 10% drop out was determined based on prior literature by Amjad et al.

Zα = 1.96 at 95% confidence level

Z = 1.84 at 80% power

d = 1.07 difference between mean of two groups

The participants will be allocated to study using simple randomization. The outcome assessor will be blinded. They will be randomized to either Group A (SDT + McKenzie) and Group B (McKenzie exercise) using computer generated sequence method. Twenty-two participants will be allocated in each group. A consort flow chart is used to represent the participants’ assignment [Flow Chart 1].

Flow Chart 1.

Consort flow chart

Data collection tool and technique

The descriptive details, such as height, weight, BMI and detailed clinical history, will be recorded. Pre- and post intervention outcome measure will be assessed using VAS, Roland Morris disability questionnaire (RMDQ), Tampa scale and SF 36 at baseline, post intervention, and at 4- and 12-week follow-ups. As a patient satisfaction outcome, global rating of change will be assessed only after 4^th and 12^th week.

Primary outcomes

Visual analog scale

It is a patient-reported outcome measure (PROM), where patients will mark their current pain level by scoring on a horizontal line in which “0”no pain and “10” being worst pain possible.[8]

Roland-Morris disability questionnaire

The RMDQ is a health status measure, which is designed to be completed by patients to assess their physical disability of LBP. It assesses functional limitations associated with lumbar spine dysfunction and is therefore well-suited for lumbar radiculopathy, where functional impairment is a major concern. It consists of 24 items addressing daily life and physical activity, such as personal care, sleeping, work, and walking. One point is assigned to each of these items, resulting in the total scores of 0 (no disability) to 24 (maximum disability) points. The RMDQ has content validity, reflects test-retest reliability for the 24-item, intraclass correlation ranges from 0.42 to 0.91.[16,17]

Secondary outcome

Tampa scale of kinesiophobia

This is a patient reported outcome which measures the fear of movement and re-injury. It consists of 17 items, each rated on a 4-point Likert scale, resulting in scores ranging from 17 to 68. Scores above 37 indicate potentially significant fear. It has excellent test-retest reliability and validity.[18]

RAND Short Form 36item health survey (SF36)

The SF-36 is a generic quality-of-life instrument that assesses eight health domains, including physical functioning, bodily pain, emotional well-being, vitality, general health, social functioning, role limitations due to physical health, and role limitations due to emotional problems. Scores in each domain range from 0 (worst health status) to 100 (best health status). It provides a comprehensive evaluation of health-related quality of life, particularly useful in conditions like lumbar radiculopathy that affect both physical and psychosocial domains.[8]

Global rating of change scale

This scale is a tool used to track changes in a patient’s condition after treatment. It is an 11-point scale. It uses a score of 0 to indicate no change, negative scores for worsening, and positive scores for improvement [Table 2].[19]

Table 2.

Outcome measures timeline

Outcome Measure		Type		Assessment Time		Purpose
VAS		Primary		Baseline, Post 4, 12 week		Pain intensity
Roland-Morris disability questionnaire		Primary		Baseline, Post 4th, 12th week		Functional disability
Tampa scale of kinesiophobia		Secondary		Baseline, Post 4th, 12th week		Fear of movement/reinjury
SF-36 health survey		Secondary		Baseline, post 4th, 12th week		Health-related quality of life
GRoC		Secondary		4th and 12th week		Subjective global improvement

GRoC=Global rating of change Scale, VAS=Visual analog scale

Ethical consideration

The study has received approval from the Institutional Ethical Committee of Srinivas University, Mangaluru. All participants will provide written informed consent in accordance with the Declaration of Helsinki. It has also been registered in clinical trials registry of India (CTRI) under registration number CTRI/2024/06/069366. Potential benefits and risks of the intervention will be explained in detail. Only qualified physiotherapists will administer the interventions.

Interventions

All included participants have been allocated into two intervention groups: Group A (SDT and McKenzie exercise) and Group B (McKenzie exercise only) [Table 3], after taking the written informed consent based on Helsinki declaration. Before starting with the treatment, every participant was physically assessed based on McKenzie assessment. The intervention will be given by qualified physiotherapist.

Table 3.

Intervention summary[2,3]

Group		Intervention		Frequency		Duration		Total Period
A		SDT + McKenzie Exercises		3/week		30–35 min		4 weeks
B		Mckenzie exercise only		3/week		10–15 min		4 weeks

SDT=Spinal decompression therapy

Mckenzie exercises

Extension in prone on hands full range

The position is same the last exercise, but this time fully straighten your arms to achieve the maximum range in your back and hold this position for 1–2 s [Figure 1].

Figure 1.

Image of Mckenzie extension prone on elbow

Extension in prone on elbow

The participants will be made to lie face down (prone). Then, lift their upper body using their elbow for support [Figure 2].

Figure 2.

Image of Mckenzie extension prone on hand

Extension in standing

Starting from a well-balanced standing position, instruct the participant to slowly lean back as far as comfortably possible. Allow their head to gently tilt back as they arch their spine. They should then return to a neutral standing position in a controlled manner.

The end range position will be held for 5 s. Participants will be performing all the three exercises with 10 repetitions each for 10–15 min total.[20]

Spinal decompression therapy

The therapist will secure the participant face down (prone) on the Triton SDT using a pelvic strap. Another strap will be anchored to the table and used to gently pull the pelvic strap until a specific tension level is reached on the unit’s display. This distraction force will be applied for 60 s, followed by a 30 s rest period. During the procedure, the traction will be set at a 30-degree angle. To ensure comfort, the decompression force will begin at less than half the patient’s weight and gradually increase to half their weight in subsequent sessions. Each session will last for 20 min [Figure 3]. [13,17]

Figure 3.

Image of spinal decompression therapy

Statistical analysis

Data analysis will be conducted using SPSS software version 24.0 (IBM Corp., Armonk, New York, USA). Descriptive statistics will summarize demographic data. Normality of the distribution will be tested using the Shapiro-Wilk test. Parametric data will be expressed as mean ± SD and analyzed using Student’s unpaired t-test; nonparametric data will be reported as median (IQR) and analyzed using the Mann–Whitney U-test. For repeated measures and follow-up comparisons, ANOVA with Bonferroni post hoc tests will be employed. Statistical significance is set at P < 0.05. The results will be presented with 95% confidence intervals.

Data handling

Intention-to-treat analysis will be applied for missing data.

Discussion

This study describes the protocol to determine whether SDT and Mckenzie exercise or only McKenzie technique is useful in treatment of lumbar radiculopathy. Lumbar radiculopathy is a condition associated with symptoms of back and leg pain that can greatly impact a person’s functioning, walking duration, and quality of life leading to disability. So, determining the optimal conservative treatment protocol is important to improve the quality of life and reduce the treatment costs. SDT offers temporary relief of symptoms, whereas Mckenzie exercise provides more sustainable solution by improving symptoms over the long term and helping to maintain the lower level of disability. However, the relative effectiveness of these two interventions remains unclear because a comparison of both treatments has not been carried out. To best of our knowledge, this is the first study that uses McKenzie exercise when combined with SDT. Although there is scarcity of literature on whether SDT is effective than routine physical therapy intervention, a few studies have also found no superiority of SDT over conservative treatment. A detailed comparison with previous literature will be written in the main trial. The rationale behind combining these two treatment stems from the complementary nature of their mechanisms of action. While McKenzie exercises target the centralization of symptoms and restoration of spinal function through specific movements, SDT aims to alleviate pain by reducing pressure within the intervertebral disc and enhancing nutrient delivery to the affected segment. So, the best part of this study is by integrating these approaches, the study seeks to evaluate whether the adjunctive use of prone SDT yields superior outcomes in terms of pain relief and functional improvement compared to McKenzie exercises alone. The proposed study design incorporates rigorous methodology, including a randomized clinical trial framework with blinding of assessors to minimize bias. The inclusion criteria are well-defined, ensuring homogeneity among individuals (detailed evaluated participants) diagnosed with lumbar radiculopathy. Outcome measures encompass patient-reported outcomes, such as VAS, Roland-Morris disability questionnaire, measures of fear avoidance behavior and overall quality of life. This study has few limitations with include short-term follow-up, lack of objective driven outcome measure and setting specific generalizability. The outcome of this RCT may establish a new benchmark in nonsurgical treatment of lumbar radiculopathy. The proposed study addresses a clinically relevant question regarding the optimal management of lumbar radiculopathy by comparing the efficacy of McKenzie exercises alone versus combined with prone SDT.

Conclusion

If the findings demonstrate superiority of the combined approach, it could potentially inform evidence-based practice guidelines and improve outcomes for patients suffering from this debilitating condition. However, further research, including long-term follow-up and comparative effectiveness studies, may be warranted to verify and generalize the findings of this investigation.

Clinical implications

This study protocol may be clinically relevant to the physiotherapists to find the most effective treatment intervention in terms of durability and cost effectiveness in lumbar radiculopathy.

AI policy

No AI tools were used in the conduct or writing of this study.

Ethical approval

The present study has received from the institutional ethical committee/IRB approval department of Srinivas University ethics committee, mukka mangaluru with the approval number 18/PHT/EC/2024 on 5.05. 2024. It has also been registered in clinical trials registry of India (CTRI) under registration number CTRI/2024/06/069366.

Author’s contributions

PM, MP and TN: Concept, design, statistical analysis, guarantor. PR: Data acquisition, data analysis, manuscript preparation, editing and review.

Data availability statement

No datasets were generated or analyzed during the current study as this is a study protocol. Upon completion of the study, the datasets generated and/or analyzed will be available from the corresponding author on reasonable request.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.