Effects of Extension Biased External Limb Loading in Addition to McKenzie Extension Protocol in Lumbar Derangement Syndrome

Low back pain is one of the most common problem affecting one's daily living activities.

Back pain results from multifactorial etiology with anatomical, psychological, physiological and social consequences and it is often classified as acute, sub-acute and chronic according to pain duration. Upto 71% of people with acute low back pain in primary care report persistent symptoms and therefore there is requirement for effective treatments in those who have not recovered after acute phase. Therapeutic exercises, manual therapy, functional training, modalities, traction, endurance training of back extensors, Kinesio-taping, trigger point therapy, deep friction massage are some of the procedures being safely and effectively applied by physical therapists to combat back discomfort or disorder.

McKenzie Method of Mechanical Diagnostic Therapy (MDT) approach was developed by Robin McKenzie who was a physical therapist from New Zealand back in 1950s. MDT is an appealing modality of treatment focusing on five areas of benefit-including reliable assessment, early prognosis, self-treatment, better outcomes and prevention of recurrence. The evaluation also determine who will get benefit from treatment and who will require another treatment protocols. McKenzie classified the lumbar back pain into three categories i.e. lumbar postural syndrome, lumbar dysfunction syndrome and lumbar derangement syndrome based on symptomatic or mechanical responses observed during repeated lumbar end range movements. The McKenzie Institute Lumbar Spine Assessment will be used to classify the patients into different syndromes and to choose the desired one fulfilling the inclusion criteria of study.

When normal tissues are deformed over a prolonged period it ends with postural syndrome like slouched posture and the postural syndrome may lead to dysfunction or derangement syndromes. Deformation of structures and tissues that causes pain at end ranges of available motion is characterized as dysfunction syndrome. Derangement syndrome is related to displacement of intervertebral disc with or without involvement of radiating pattern of pain along with back pain and fluctuations in symptoms or pain with directional movements can be observed due to force changes on affected intervertebral disc.

Centralizing and Peripherilizing are two important concepts with a strong association towards derangement syndrome. Centralizing reveals that movements or loading moves the most distal pain proximally while Peripherilizing shows movements or loading moves the pain more distally. McKenzie lumbar extension exercises results in reduction, abolition or centralization of symptoms. In Lumbar derangement syndromes following MDT classification system, a subgroup in which symptoms improve with lumbar extension is labeled as posterior derangement syndrome whereas the subgroup in which symptoms improve with lumbar flexion is labeled as anterior derangement syndrome. Work of many researchers, like Peterson, Machado and Paatelma, provided the strongest evidence regarding the validity of McKenzie method of treatment.

Progressive limb loading exercises at lumbar region fall under two categories, one group emphasis on abdominal musculature and the second group emphasize on lumbar extensor musculature. Patient begins from quadruped position and progress towards prone position initiating with low intensity training and progressing towards greater intensity along with spinal compression in case of lumbar extensors. Progression towards prone position at the end range of motion requires greater control of neutral spine thus providing excellent stabilization of lumbar extensors.

A randomized controlled trial on McKenzie treatment approach in people with chronic low back pain conducted by M.H Halliday et al. provide preliminary evidence that treatment effects of McKenzie Exercises are greater when the core principles are followed with significant reduction in pain and disability of 15.2 [95% CI 7.6 to 22.7] and 11.7 [95% CI 5.4 to18.0]. Srivastav et al. conducted a study at mechanical low back pain with significant improvement having p\<0.05 at NPRS \& MODI after application of lumbar stabilization exercises along with conventional physical therapy.

An international survey conducted in 15 different countries in 2019 regarding McKenzie classification system involving 64.8% lumbar, 29.6% cervical, 5.6% thoracic spine of 750 patients fulfilling MDT criteria revealed 0.1% postural syndrome, 1.7% dysfunction syndrome, 75.4% derangement and 22.8% other. In derangement syndrome 82.5% were extension biased thus Derangement is the most commonly encountered pain syndrome and extension is so far the most common directional preference.

With the help of this study the investigators can determine the effects of extension biased lumbar limb loading exercises along with McKenzie extension protocols in the management of patients with lumbar derangement syndrome, which will also be a cost effective management option. It will add to the existing pool of knowledge in the fields of conservative spinal management, physical therapy, orthopedic manual therapy and musculoskeletal medicine.