Viewing the spine looking at the back is the diagram in figure 1(below it is an M.RI. of the same region of the lumbar spine).The blue circles are of a typical L4/L5 postero-lateral disc herniation impinging the L5 nerve root. The red arrow in figure 1 M.R.I. is a typical postero-lateral disc bulge. Viewing the spine looking from the top-down is figure 2 (below it is an M.R.I. of the same region of the lumbar spine). The red circles are of an atypical far lateral disc herniation impinging the L4 nerve root. In figure 2 the red arrow is how a far lateral disc herniation looks like in an M.R.I. Symptoms of the blue circles/red arrow in figure 1 M.R.I. (L5 nerve root compression) pain in the back of the leg, in the lower leg it winds around the outer aspect of the calf and spreads down the top of the foot over the big toe. Symptoms of the red circles/red arrow in figure 2 M.R.I. (L4 nerve root compression) pain to the outside of the thigh, winding around the front of the knee and down the inner aspect of the lower leg. Failure to diagnose far lateral disc herniations can direct surgery to the wrong disc level giving a poor outcome.

Most FL.D.H.'s occur in older individuals and originate from upper lumbar levels - the L3-4 and L4-5 discs. In contrast, classic disc herniations usually originate from the lower lumbar levels - the L4-5 and L5-S1 discs. Because of the anatomical location of F.L.D.H.'s, their clinical presentation often differs from that of classic herniations. Classic herniations usually produce lower back pain and pain in the posterolateral thigh with radiation to the foot. On the other hand, F.L.D.H.'s can cause sudden onset of pain in the anterolateral thigh. Additionally, the patient will likely have weakness in the quadriceps, decreased patellar reflex, decreased sensation in the associated dermatome, and referred pain to the knee.

Hip pain, recently I was fortunate to attend a seminar presented by Dr John O'Donnell Orthopaedic surgeon specialising in hip arthroscopies. He is one of the early pioneers in this field and is one of a handful of high volume hip arthroscopists in the world having performed over 4000 hip arthroscopies. Pain from the hip can be felt from the groin, buttock, side of the hip and even be felt radiating down the thigh to the knee. Osteoarthritis (degeneration of the joint cartilage surfaces) is common.

This movie is normal segmental lower back movement

The image below is an example of a labral tear of the hip joint

What makes a person suffering from lower back pain, disc damage, sciatica and hip pain a Chiropractic patient is based on Chiropractic's principle that joint dysfunction termed "Subluxation" is the cause of a patient's signs and

symptoms. The American Chiropractic Association has defined subluxation as "the alignment / physiological function of a motion segment as being altered although contact between the joint surfaces remains intact (1)." This altered alignment / physiological function (2) to the musculoskeletal system notably cause changes in tissue sensory beds, which have been implicated in subluxation theories. The effects of altered sensory input on central and efferent activity is of great interest to clinicians as Chiropractic analyses have been developed in an attempt to locate dysfunction or subluxation. Changes that occur due to joint alterations from micro trauma, sustained loading such as in an abnormal posture, repetitive motions, many times work related may also be a mechanism of injury.

Sports, hobbies, and recreation which may lead to acute or chronic dysfunction and pain syndromes. In addition the effects of ageing, or of a lifetime of micro trauma and macro trauma injuries leading to degeneration immobilization and pain.

Below is a 3D creation of the lower 3 lumbar vertebrae (lower back)

Connective tissue changes as a result of inflammation and oedema reorganize  tissues, possibly perpetuating immobility and further degeneration.Under normal conditions (2) the nociceptive system is silent because the high threshold of the nociceptor does not receive the amount of sensory   stimulation necessary to initiate an action potential. However when adequately stimulated nociceptors fire continuously in a non adaptive nature until the stimulus is removed. Thus the person is apprised of a damaging stimulus that causes pain as long as it persists. Three types of stimuli excite nociceptors, mechanical, thermal and chemical.

It is this subluxation that we as Chiropractors, find and restore to normal alignment and hence function.What we do with the Activator Adjusting Instrument is adjust these subluxations, in doing so we initiate passive joint movement , which results in stimulating movement as well as the nerves that sense movement, this stops the nerves that are responsible for pain from being active, and hence abolish or diminish pain (3).

Creation of normal joint structure and function through Chiropractic adjustments may cause the nerves responsible for sensing normal joint movement, and those nerves responsible for sensing pain to work appropriately, meaning that when the joints are working properly then the pain fibre nerves remain dormant, only when there is joint damage or dysfunction are the pain fibres to operate (3).

Disc damage (4)
Findings of a research of 193 patients showed the most common tissue of pain origin was the outer layer of the annulus fibrosis and the posterior longitudinal ligament. More recently biomechanical factors have been shown to be involved in pain syndromes with degenerative disc disease. Similar studies (5) of local anaesthetic and confirmatory blocks have also implicated the lumbar facet joints as a source of pain. In summary the way (6) Chiropractic adjustments work  is (i) Reduce a subluxation by 1-2mm of the facet joints (ii) Stretching of hypertonic posterior segmental spinal muscles abolishing pain coming from muscles, ligaments and tendons because of sretching (iii) increased neural output produced by mechanoreceptor stimulation that may modulate pain.

Sciatica (4)
Is a result of a spinal nerve root being irritated / compromised by herniated discs, posterior osteophytes, facet hypertrophy, spinal stenosis, spondylolisthesis, infection, tumour, fracture or disease. Other structures within the I.V.F may also be compromised creating a pathological state. Notably lymphatic channels, segmental arteries, communicating veins and venous plexuses, or recurrent meningeal nerves. Authors have noted some degree of inflammation and irritation of the nerve root must exist to lead to the objective signs and symptoms of sciatica.

Sacro-iliac joint syndrome
The sacro-iliac joint (8) has well developed cartilage surfaces, a synovial membrane, strong anterior and posterior ligaments, and a large internal sacro-iliac ligament. The joint surfaces can rotate 3-5 ° in the younger symptom free patient. The joint has two functions to provide elasticity to the pelvic ring and to serve as a buffer between the lumbo-sacral spine and hip joints. The pain syndrome presents with pain over one sacro-iliac joint in the region of the posterior superior iliac spine. This maybe accompanied by referred pain in the leg. In the sacro-iliac joint syndrome (9) local and reflex pain is present and movement is restricted. Chiropractic adjustments directed specifically to this joint however often relieve the symptoms. Possibly the effects they produce is by stretching posterior muscles, breaking intra-articular adhesions and relieving the joint fixation with resultant stimulation of the surrounding mechanoreceptors.

The 2 blue arrows are the sacro-iliac joints which you can consider as part of your pelvis/ hips

The green arrow is your sacrum

The red arrows indicate a pars defect / fracture-spondylolysis