Comparison of muscle energy technique and facet joint mobilisation in the patient with chronic neck pain: A randomized controlled trial

Objective: To compare the eﬀects of muscle energy techniques, facet joint mobilisation and conventional physical therapy on pain, disability, cervical lordosis and range of motion in patients with chronic neck pain. Method: The parallel-design randomised controlled trial was conducted at the Physical Therapy and Rehabilitation


Introduction
In the developed world, the prevalence of the chronic neck pain is reported to be ranging from 7% to 22% among women and from 5% to 16% among men. 1 Prevalence studies showed that cervical pain is more prevalent among middle-aged women compared to their male counterparts. 2ronic neck pain is one of the most common and debilitating forms of musculoskeletal dysfunction which is aggravated with neck movements, sustained neck posture and cervical muscle palpation. 3Pain started after minor positional fault or malalignment in the cervical spine curve due to muscle guarding and tightness.Muscular activity also has a contribution to the magnitude and change in shape of the cervical lordosis.There is a significant association between the loss of cervical lordosis and the weakness of cervical extensor group of muscles. 4,5e natural biomechanical alignment of the spine is essential to distribute most of the load posteriorly.Therefore, any deviation from this natural alignment might lead to the development of cervical pathology. 6A sustained forward head posture is mostly adopted during repetitive workload that would lead to long-standing neck pain and stiffness which causes loss of cervical lordosis or cervical straightening. 7e most common approaches used for evaluation of the biomechanical orientation of cervical curve are the Cobb angle method and the posterior tangent method. 8As compared to the Cobb angle method, the standard error rate of posterior tangent method is lower and it gives more accurate measurements than the Cobb angle method, as posterior tangent slopes along the curve and can provide an analysis of any buckled area of cervical curve. 9onservative treatment approaches for cervical pain include management plan by a general practitioner, manual physical therapy, exercise therapy, graded strengthening and endurance programmes by physiotherapists and combinations of these. 10 terms of preference of techniques for the management of neck pain, exercise therapy and manual therapy are mostly applied by physiotherapists.Manual therapy techniques include joint mobilisation and soft tissue mobilisation techniques.Restoration of joint arthrokinematics is achieved by joint mobilisations, whereas soft tissue techniques, such as muscle energy techniques (MET) and static stretching, focus on flexibility of soft tissues, like extensibility of muscle and connective tissues. 11Conventional static stretching is commonly applied in the management of neck pain and other mechanical disorders, but it directs effect only on the passive component of muscle, like connective tissues or perimysium, whereas METs focus on the active component of muscle tone in addition to the passive component. 11T is also known as post-isometric relaxation (PIR) technique or post-facilitation stretch (PFS), as it is a direct active post-facilitating technique. 12MET promotes reflex relaxation of hyperactive and tight deep cervical extensor muscles through autogenic or reciprocal inhibition, thereby increasing extensibility and viscoelasticity of the muscles. 13However, Joint mobilisation promotes activation of mechanoreceptors which promotes proprioception of neck muscles. 14Maitland's application involves rhythmical and oscillatory mobilisations along with stretching techniques to reduce muscle spasm and pain prior to mobilisations. 15,16Sustained natural apophyseal glides (SNAG) is one of the best sustained mobilisation techniques as it improves the range of motion (ROM) of the patient by correcting the biomechanics of the joint, unlocking a jammed facet, and releasing the entrapped meniscoid between the joints. 17terature suggests that in comparison to Kaltenborn's mobilisation techniques, after 2 weeks of treatment, oscillatory Maitland's mobilisation appeared to be superior with respect to functional disability and cervical ROM (CROM). 18Moreover, in comparison to conventional physical therapy (CPT), evidence suggests METs to be superior in relieving pain and improving disability among the patients with non-specific neck pain. 19wever, to our knowledge, no evidence exists regarding the comparison of MET and facet joint mobilisation (FJM) on cervical lordosis.The current study was planned to fill the gap by comparing the effects of MET, FJM and CPT on pain, disability, cervical lordosis and ROM in patients with chronic neck pain.

Patients and Methods
The parallel-design randomised controlled trial (RCT) was conducted at the Physical Therapy and Rehabilitation Department of the Heavy Industries Taxila (HIT) Hospital, Taxila Cantt, Pakistan, from December 2020 to May 2021.
After approval from the ethics review committee of Riphah International University, Islamabad, Pakistan, the RCT was prospectively registered (Sept 2021).
The sample size was calculated using OpenEpi tool with confidence interval 95%, power 80% in line with literature. 11The sample was raised using purposive sampling technique.The subjects were randomised using sealed envelope method into MET group A, FJM group B and CPT group C. The participants were kept blinded to the group orientation.
Both male and female patients with age 35-50 years, having chronic neck pain for more than 12 weeks ranging from 4-8 on Numeric Pain Rating Scale (NPRS), patients having recurrent neck pain aggravated at least once in the preceding month, and those with cervical spine curve straightening on X-rays and limited and painful CROM (flexion <80 o , extension <70 o , rotation <90 o to both sides, lateral flexion <35 o ) were included after taking informed consent from each of them.Patients with any history of tumour, recent trauma, acute inflammation, vertebrobasilar insufficiency, cervical radiculopathy or myelopathy and any serious systemic underlying pathology were excluded.
All patients received moist hot pack of 14/15ʹ over cervical region for 15 minutes.Hydro collator temperature, according to standardised hot pack, is 40-45 degree Celsius along with application of transcutaneous electrical nerve stimulation with frequency of 120Hz at low intensity below the local painful sensory threshold with pulse width 50-200 micro-sec was applied for 10 minutes followed by treatment through particular intervention.
Group A received METs.Based on 3-5 repetitions of the post-isometric relaxation (PIR), 30-50% isometric contraction of the agonist muscle was performed for 7-10 seconds while holding the breath during isometrics.The patients were then asked to exhale and relax for 5 seconds and then repeat the movement in new restrictive barrier with a gentle stretch of 10-60-second hold. 12,14The whole procedure was repeated for a minimum of 3 times during each session for a period of 2 weeks.The technique was applied to the shortened muscles of the cervical region, which get shortened due to static abnormal posture muscles, including anterior scaleni, middle scaleni, posterior scaleni, sternocleidomastoid (SCM), the levator scapulae and the upper fibres of trapezius muscles.
Group B received FJM.Treatment was based on 3 sets of 15 repetitions of the unilateral poster-anterior glides (UPA) on the cervical spine C2-C7. 18Initially grade I and II mobilisations were used, followed by grade III of Maitland manual therapy on selected tender and painful cervical vertebral segments.While on hypomobile segments, 5 repetitions of extension SNAGs were applied. 20oup C controls received CPT to improve flexibility of short muscles by sustained stretching and strengthening of weak musculature by isometrics.Treatment approach based on 2 sets of 5-10 repetitions of isometric exercises for muscles which are prone to weakness, including serratus anterior, middle and lower fibres of trapezius, deep cervical flexors, and major and minor rhomboids, and 5 repetitions with holding time of 20 seconds tagetted stretching exercises for the short muscles prone to tightness, including pectoralis muscles, suboccipital, levator scapulae and upper trapezius.
Outcome measuring tools included NPRS 21 for pain, neck disability index (NDI) 21 for neck disability, and goniometry for CROM, while cervical lordosis was measured through radiograph using posterior tangent method C2-C7. 22,23ta was collected at baseline, after 2 weeks of treatment, and after 4 weeks.The home exercise programme was given to all the patients during the 4-week study.All groups received a 2-week interventional plan.The patients in all groups received 20-30-minute sessions on 3 alternate days for two consecutive weeks, making it a total of 6 sessions.Patients were advised to revisit after 4 weeks (1 month from the baseline) for follow-up.Data was analysed using SPSS 21.Shapiro-Wilk test was used to determine data normality.Parametric testing included one-way independent-measure analysis of variance (ANOVA) for intergroup comparisons, followed by Bonferroni test for post-hoc analysis of NDI, cervical lordosis and CROM.Non-parametric testing included Kruskal-Wallis test for intergroup comparison to analyse effects on NPRS.P<0.05 was considered significant.The statistical analysis for those lost to follow up post-intervention was performed on an intention-to-treatment basis.
Among the participants, 39 (37.4%) reported onset of neck pain 3 months before presentation, 58 (55.4%) said 6 months, and 8 (7.2%) said 12 months.In general, 67 (63.8) participants were housewives, 18 (17.1%)labourers, 5  In term of pain intensity, there was significant intragroup differences in all the 3 groups post-intervention compared to the baseline (p<0.05).There was no significant difference between groups A and B related to NPRS and NDI (p>0.05), but both groups were superior to group C (Table 2).
In relation to flexion, rotation and side-bending, a significant intragroup improvement was observed in all the groups (p<0.05).Group A had better outcomes compared to group B with respect to ROM in flexion, rotation and side-bending towards both sides (p<0.05).For extension ROM and cervical lordosis, group B did better than group A (p<0.05).No significant difference was found between groups A and B for NDI (p>0.05).Group B overall did better than group C(p<0.05).Group A was superior to group C with respect to NDI and CROMs, but there was no significant difference for cervical lordosis (p>0.05)(Table 3).
Mean cervical lordosis in group A increased from the baseline score of 21.23 degrees to 26.34 degrees, whereas mean cervical lordosis in groups B and C increased from the baseline scores of 22.20 degrees and 20.97 degrees to 33.46 and 26.60degrees, respectively.Hence, all groups showed significant improvement in cervical lordosis, but group B was superior to the other groups (p<0.001).

Discussion
The findings indicated that MET and FJM were efficient in improving chronic neck pain intensity, cervical lordosis, ROM and NDI.In terms of neck pain intensity and functional disability, both MET and FJM were superior to CPT with non-significant difference among the three.An earlier study combined the effects of MET and FJM on cervical spine curvature, and concluded that there was a significant improvement in patients with respect to cervical spine lordotic curve, pain intensity, functional disability score, CROMs and isometric strength of muscle.However, there was no comparative group in that pilot study. 20An RCT concluded that adding manual therapy to the conventional protocol significantly improved neck pain, disability, ROM and perception of movement. 24The current study also reported that the manual FJM showed significant improvement in outcome measures as compared to conventional therapy.However, there was no MET group in the earlier study and the effects on cervical lordosis were not observed either. 24e current findings are supported by a study showing cervical SNAGs to be superior over the control group in terms of pain intensity, disability score and CROM, but due to the absence of MET group, it is not possible to compare between MET and manual therapy. 25 line with the current findings, a study comparing CPT with and without MET concluded that both protocols were beneficial in improving pain and NDI scores, but MET was superior to CPT. 26 On the other hand, contrary to the current results, a three-group comparative study of myofascial release, MET and manual therapy demonstrated no significant difference (p>0.05) in terms of ROM, disability and proprioception in patients with postural neck pain. 14ased on the review of existing literature, it is important to mention that prior to the current study, no evidence existed regarding the comparison of MET and FJM on cervical lordosis.
The results of the current study are in accordance with an RCT which demonstrated significant MET results compared to passive sustained static stretching for improving pain intensity and disability level among patients with neck pain.However, there was no FJM group in the earlier study and the effects on cervical lordosis and CROM were not observed either. 3e current study suggested a significant improvement in cervical spine lordosis with FJM among patients with chronic neck pain, unlike previous studies which  demonstrated an improvement in cervical spine lordotic curvature after use of spinal manual therapy techniques and cervical manipulation along with mechanical traction. 22,23e current study demonstrated FJM to be superior to MET for improving cervical lordosis and extension ROMs.The findings can be explained in a physiological perspective as both techniques improve muscle balance and joint integrity, but MET improves muscle flexibility by reducing tension on targeted structures, whereas FJM promotes activation of mechanoreceptors which promote proprioception of cervical structures 14 thus suggesting FJM to be superior to MET for improving cervical lordosis.
The current study has limitations as there was no long-term follow-up of interventions to assess the sustainability of treatment effects.Besides, the sample was also small.Future studies should focus on long-term follow-up of interventions with larger sample sizes.Future studies should also look into the effects of each interventional technique in terms of curve measurement via quantitative angle measuring software and addition of electromyography (EMG) for muscle strength analysis.

Conclusion
MET and FJM were found to be more effective for reducing neck pain and disability via improved CROMs compared to CPT, except for cervical lordosis and extension ROMs where FJM was superior to both groups.While MET was superior to FJM with respect to flexion, rotation and side-bending towards both sides, there was no significant difference between FJM and MET with respect to pain intensity and functional disability.

Figure :
Figure: Consolidated Standards of Reporting Trials (CONSORT) flow chart.

Table - 1
: Baseline comparison of the study groups.

Table - 3
: Follow-up inter-group comparison of outcome variables after 4 weeks.