The pelvic girdle and low back by drdoc on-line
Regional Anatomy and Rheumatic Disease Syndromes Associated with the Low Back, Pelvis and Hip Joints

The symptoms of low back and hip pain present frequently to the practitioner, and a systematic approach is necessary to diagnose the exact cause.
In order to do this, a basic knowledge of the regional anatomy is required.

In general, pain may arise from :

1) Articular source.
2) Extra-articular....including muscle / tendon / ligaments / bursa and nerves.
3) Referral from distant site

The aetiology may be further classified into :

a) Mechanical
b) Inflammatory

Thereafter a specific disease entity can be ascribed to the symptom and signs recorded by the examiner, and appropriate therapy initiated, following appropriate investigations. BASIC REGIONAL ANATOMY


The basic functional unit of the spine consists of:

1. Adjacent halves of 2 vertebrae.
2. Interposed disc
3. Facet joints.
4. Supporting ligaments and muscles
5. Blood vessels.
6. Neural structures.

The intervertebral disc consists of:

1. Inner fluid Nucleus Pulposus surrounded by a zone of irregular connective tissue bands rich in fluid. 2. The lamellae of the annulus fibrosus. The vertebral bodies and disc are ensheathed by periosteum. This is thickened anteriorly and posteriorly to constitute the anterior and posterior longitudinal ligaments. The periosteum is innervated and vascular where it covers the disc. The disc itself is devoid of blood supply and nutrients are obtained by osmosis. Movement of fluid into the disc is enhanced in situations of low intradisc pressure i.e.. bed rest, and decreased with high disc pressures.

Disc Pressure with Activity:

Activity Disc pressure
Sitting Increased load by 30%
Walking Increased load by 15%
Coughing Increased load by 50%
Jumping Increased load by 50%
Bending Increased load by 85%
Lifting 20kg Increased load by 300% ( knees bent)
Lifting 20kg Increased load by 500% (knees straight)
Sitting with backrest Decreased load by 10-20%
Abdo muscle contraction Decreased load by 30-50%

The facet joints

These posterior articulations are synovial joints with a fibrous capsule and restrict spinal movement. Whilst they are almost horizontal in the cervical spine, they are more vertical in the lumbar spine and hence allow flexion and extension.

The nerve roots exit through foramina, bounded above and below by the vertebral lamina.
Anteriorly to the root lie the intervertebral disc and the vertebral bodies.
Posteriorly are the facet joints.
The lumbosacral articulation is angulated, as the disc space anteriorly is greater than posteriorly, and thus the sacrum has a posterior angulation.
The facet joints have two principal movements:

Translocation = sliding (Bilateral translocation causes forward bending, unilateral translocation causes side bending).
Distraction = gapping (Distraction produces rotation).

The Spinal Ligaments

These prevent excessive motion

1. Interspinous ligaments : From the lamina to the underside of the spinous process above
2. Supraspinous ligaments : Between the ends of the spinous processes. Below L4, is replaced by decussating fibres of the erector spinae.
3. Ligamentum flavum : Forms the smooth posterior wall of the spinal canal. Is elastic and assists in regaining posture after flexion.
4. Iliolumbar ligament : Between the tip of transverse process L5 and spreading to the lip of the iliac crest.

The Spinal Muscles

A. Posterior

Consist of three layers:


i) Superficial : Trapezius (in cervical and thoracic spine) Latissimus dorsi Gluteus maximus

ii) Intermediate : Erector spinae muscles

iii) Deep : Interspinous muscle Intertransverse muscle Multifidus muscles

B. Anterior = flexors

i) The abdominal wall muscles : internal obliques, external obliques, recti
ii) The deep anterior muscles : quadratus lumborum, psoas

Neuroanatomy of the lumbar spine

The spinal cord terminates at the inner border of L1 and the lumbar and sacral roots leave the cord between T10 and L1.
The roots leave with a sheath of arachnoid and dura. Before emerging from the spinal neural canal, they cross the intervertebral disc and then pass through the foramen of the segment below. The root divides into a dorsal and ventral primary ramus. The dorsal ramus supplies branches to the vertebral posterior muscles, supraspinous and interspinous ligaments, posterior longitudinal ligament, disc, ligamentum flavum and facet joints as well as a branch to the posterior sacroiliac joint. The ventral ramus gives rise to the lumbar plexus from roots L1,2,3,4 and the sacral plexus from roots L4, L5, S1,2,3.
The lumbar plexus gives rise to the femoral and obturator nerves. The sacral plexus gives off branches, including the sciatic nerve. Irritation or compression of the nerves, or nerve roots, cause sensory abnormalities in a dermatome distribution. In contrast, lesions of the lumbar spine have vague and varied distribution of referred pain, as these structures are innervated by 2 or 3 segmental nerves.


This articulates between S1,2,3 and occasionally L4,L5.S4 and the ileum.

The sacral surface is concave whilst the ilial surface is convex.
Both are pitted and ridged in congruity.
There is a synovial joint with a surrounding capsule. The bones interdigitate closely and are bridged by tough sacroiliac ligaments.
Posteriorly the sacrotuberous and sacrospinous ligaments strengthen the joint.
Movement of the joint is small - approximately 0,5 cm but increases during pregnancy.


Ball and socket joint between the head of femur and the acetabulum of os coxae.
The articular capsule encloses the head and the greater part of the neck of femur. It is attached to the circumference of the acetabulum close to the edge. Below, it attaches anteriorly to the anterior trochanteric line and posteriorly to the neck of the femur.
Anteriorly the capsule is thickened as the iliofemoral ligament. This prevents over-extension.
Medially the capsule is thickened to form the pubofemoral ligament. The acetabular margin is ringed by the labrum acetabulare which deepens the socket.
The head of femur is connected with the hip bone by the ligament of head of femur which connects the pit on the head and the margins of the acetabular notch.

Muscles of the Hip Joint

1. Hip flexors Iliopsoas (supplied by sartorious femoral nerve) Rectus femoris
2. Abductors Gluteus medius (inserts into greater trochanter)
3. Adductors Adductor brevis/longus/magnus Gracilis Pectineus
4. Extensors Hamstrings Gluteus maximus (Inserts into the gluteal tuberosity and joins tensor fascia lata distally to form the iliotibial tract.)

Bursae of the Hip Region

1. Iliopsoas bursa : anterior to psoas
2. Trochanteric bursa : between gluteus maximus and the postero-lateral greater trochanter
3. Ischiogluteal bursa : overlying ischial tuberosity
LOW BACK SYNDROMES Mechanical / Inflammatory

A : Mechanical

Characterized by episodic, interrupted pain. Aggravated by posture/trauma/lifting weights. Worse in the evening and with exercise. Relieved with rest. Transient stiffness 1/2 hr. Related to extent of overuse. May occur transiently after resting during the day.
Examination may reveal asymmetrical spinal limitation. Posterior Facet Joint syndrome Dull low back ache with radiation to the thighs and buttock. Secondary spasm of posterior spinal muscles. May recall a strain injury in 20%. May occur in attacks with frequent recurrences, and subsequently become chronic. Predisposed to by posture, structural disturbance i.e...... spondylolisthesis, disc disease. On examination, one finds tender low lumbar muscles, tightening of hamstrings and sacrospinalis on flexion and asymmetrical back limitation.

Nerve Entrapment Syndromes

i) Sciatica with root compression. Characterized by pain and neuritic features of numbness/paraesthesia. See radiation to buttock/posterolateral thigh and lateral foreleg. May occasionally have no back pain itself. Worse with increased intrathoracic/intra-abdominal pressure. i.e.. lifting or sneezing. Usually intermittent if disc herniation. Constant if tumor. Examination may reveal neurological deficit including dermatome sensory loss. Straight leg raising test usually positive <<70o (Lasegue's test ).

Spinal Stenosis. Causes nerve root irritation and vascular embarrassment. Walking produces ache/pain/paraesthesia in the buttock with reduced coordination of the lower limbs. Relieved with sitting/bending. Initially intermittent. May progress until patient is progressively sedentary. Worse with hyperextension. Eased with spinal flexion. May see neurological deficit on examination. This includes reduced reflexes in the lower limbs. Severe spinal stenosis above Lumbar 3 may affect bladder function.

The diagnosis is confirmed on MRI / CT / myelography. MRI is the method of choice.

Causes of spinal stenosis include:

Developmental Dysplastic disorder
Degenerative disease
Post op bone hypertrophy

Muscle/ Ligamentous Origin

These may benefit from local injection, and are important to recognize.

i) Iliolumbar Syndrome. (Between L5- iliac crest) Occurs after strain injuries and present with pain and tenderness in the low back. Pain is worse bending away from the involved side.
Examination reveals local tenderness at the insertion of the Iliolumbar ligament, over the posterior iliac crest.

ii) Quadratus lumborum Syndrome. (Between iliac crest and the transverse processes of the L2-L5 and the lst rib) Similar clinically to the Iliolumbar syndrome.

iii) Piriformis Syndrome (Arises from the sacral border, runs through sciatic notch. Inserts on greater trochanter.) Causes a sciatica syndrome, from compression of the sciatic nerve at the sciatic notch by inappropriate contraction of piriformis, secondary to trauma/sprain or inflammation.

Myofascial Back Pain/Fibrositis

Seen from 3-5th decade. Causes dull pain waxing and waning. Worse with work/sitting. Relieved with heat/walking/bed rest. Associated with poor sleep pattern.
Note trigger points on examination:
Sacrospinalis origin.
Gluteus maximus origin.
Over SI joints.
Over gluteal fascia.

May respond to local injections.


This is rare ( % of patients) .
Present with vague pain. Often secondary gain/ underlying depression.

Referred from Viscera.

Aneurysm / pancreatic / renal / gastric / ...etc.

Fibromyalgia syndrome

This is one of the commonest causes of pain all over with a dominance in the neck, shoulder girdle and the low back.
It is characterised by body pain especially in the neck shoulder girdle and low back, with some stiffness and associated with multiple other symptoms including headaches and migraines, irritable bowel, irritable bladder, jaw pain, temperature irregularity, pins and needles, memory disturbance, visual blurring, fatigue and tiredness. Patients tend to sleep badly and never feel rested. They tend not to dream. Examination will reveal tender points at multiple sites in the neck, shoulders low back knees and elbows.
Patientsare frequently labelled as neurotic as there is an association with depression or stress.

patients did not respond to analgesia or anti-inflammatories and the treatment of choices amitryptilline and Cymbalta or Lyrica


B: Inflammatory:

Characterized by :

Low back pain.
Stiffness, especially morning stiffness. On taking the history,the longer stiffness duration the more severe the inflammation.
Improves with exercise and through the day.
Examination reveals spinal limitation to all ranges of motion

Lateral Flexion <30 degrees is abnormal
Extension <40 degrees is abnormal
Rotation (thoraco-lumbar) <30 degrees is abnormal

Anterior Flexion
Tested by the Shober test. This measures the distraction of skin marks (placed 15cm) apart, on flexion. Distraction of <5 cm is considered abnormal.
Costovertebral motion. Tested by measuring maximal chest expansion at the 4th intercostal space. <3 cm is considered abnormal.
There may be local tenderness, usually mild.
Sacroiliitis may be found and is usually seen in association with the Seronegative spondyloarthropathies, i.e. Ankylosing spondylitis, Psoriatic spondyloarthropathy, Inflammatory Bowel disease, and Reiter's syndrome.


Sacroiliitis :
The signs of sacroiliitis, may be unreliable, and the involvement of the sacroiliac joint may be completely asymptomatic. Thus Radiological examination is essential if the condition is suspected. Clinical tests and signs:
1. Local tenderness over the joint itself on palpation. The joint is palpated medial to the posterior iliac spine.
2. Hyperextend the leg and thigh over the edge of the examination couch, with the pelvis prone.
3. Compress the pelvis laterally. Pain may reflect sacroiliitis (Erichsens sign).
Radiographic demonstration is best seen with AP prone views.
Occasionally, oblique (80-85 degree ) views may be helpful.
During childhood and active growth, the cortical margins are ill-defined, and thus may give a false impression of sacroiliitis.

Radiological grading of sacroiliitis

Grade 1: widening and periarticular porosis.
Grade 2: superficial erosion and focal areas of sclerosis.
Grade 3: proliferation of bone. Partial bridging.
Grade 4: osseous fusion.

The HLA B27 tissue type may be present in those patients with inflammatory spondyloarthropathies.

Osteitis condensans ilii

Patients with this syndrome may have a clinical picture resembling fibrositis (in 2/3 of cases). Some have symptoms of sciatica (1/3). Sclerosing densities are seen on the iliac side of the pelvis. Osteitis Pubis Patients present with pain in the low pelvis, often radiating to the adductors of the thigh. May arise secondary to local sepsis, Ankylosing spondylitis, chondrocalcinosis and polymyalgia.


Presents with pain in the low back and coccyx region. May occur post trauma or secondary to a low back problem with referral to the coccyx and causing secondary spasm of piriformis, levator ani and coccygeus muscle.


Problems that present with pain in the hip region must be differentiated between problems located in the hip joint and capsule itself (intra-articular), and extraarticular syndromes. In general, passive movement is not painful in extraarticular disorders, whereas resisted or active movement will be painful, especially in the direction of action of the affected muscle or tendon.
In an articular problem, active and passive movement will both be painful. In particular, the movements of abduction and internal rotation of the hip joint are most sensitive to pain and limitation in articular disease. This pattern constitutes the "capsular pattern" of the hip joint.

Extraarticular syndromes

1. Myofascial pain syndromes of the hip region.

a) Snapping hip syndrome : This is a painless condition, where a snapping sound is heard by the patient on hip flexion and extension. It is due to a slipping over the greater trochanter, of the iliotibial band (an extension of the fascia lata between the iliac crest, sacrum and ischium, stretching over the greater trochanter, to the lateral femoral condyle, tibial condyle and fibular head.
b) Fascia lata syndrome : This is associated with pain and trigger points over the lateral thigh region. c) Trochanteric bursitis : This is a commonly seen problem, presenting with pain over the lateral hip area and buttock. The patient may note difficulty lying on the affected side. Examination reveals local tenderness over the greater trochanter area, and resisted abduction may be tender. Passive abduction is painless.
d) Iliopectineal Bursitis : The bursa lies between the iliopsoas muscle and the iliopectineal eminence. Clinically, there is pain on resisted flexion, and tenderness overlying the capsule of the hip. Pain is felt over the anterior pelvis and groin area.
e) Iliopsoas Bursitis : Pain is felt over the anterior pelvis region and is accentuated on resisted flexion. f) Ischial Bursitis : This produces pain over the ischial prominence and hence is painful on sitting. The sciatic nerve lies closely related to the bursa anatomically, and may be subjected to local irritation.

2. Regional Nerve Entrapment Syndromes

a) Abdominal Cutaneous nerve : Entrapment occurs as the nerve emerges through a fibrous ring in the abdominal wall. Focal tenderness is felt at this site, and pain may be felt over the low abdominal wall. b) Obturator Nerve : Usually this follows trauma with pelvic fracture of osteitis. Pain is felt in the groin and down the inner thigh. The pain is aggravated by hip movement.
c) Lateral Femoral Cutaneous Nerve: (Meralgia Paraesthetica). This is a common entrapment syndrome, occurring at the anterior superior iliac spine, as the nerve passes through the inguinal ligament. Pain is felt over the upper anterolateral thigh region. It is caused by trauma, prolonged sitting with crossed legs, bulging abdominal girth, corsets and occasionally from car seat belts.

Articular Syndromes

It is important to observe the gait of the patient and the posture.
A pelvic tilt may be due to a structural scoliosis, a leg length discrepancy, or hip disease itself. Observation may reveal contractures or gait disturbance.
With an antalgic gait, the patient leans over the diseased hip during the period of weight bearing, placing the body weight directly over the joint to avoid contraction of the hip abductors.
A Trendelenburg gait is noted if there is a weakness of the hip abductors, or in the presence of a painful hip . In the assessment of the hip joint, the hip is passively taken through it's range of movement.

Normal ranges of movement are:
flexion 120 -------degrees
abduction 45 -----degrees
adduction 20-30 -degrees
ext rotation 45 --degrees
int rotation 40 --degrees

Pain and/or limitation of movement on passive motion may be noted, especially on abduction and internal rotation - the capsular pattern.
Flexion contracture of the hip, is assessed by flexing the opposite hip, to remove any lordosis and then extending the ipsilateral hip as much as possible.
The fabere test may be done. This consists of flexion, abduction, external rotation and then extension of the hip, which produces pain. The Trendelenburg test of abductor function, in which the patient, whilst standing, is asked to lift the leg of the affected side off the floor. In abductor mechanism weakness, or if inhibited by pain, the pelvis will tilt downward on the affected side, instead of lifting, as in normal people.

Leg length discrepancy, is measured by measuring the distances between medial malleolus and the anterior superior iliac spines. A difference of 1cm is significant.

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Original Article-copyright
Dr David Gotlieb: drdoc on-line
Cape Town
South Africa

Revised 2011..