PELVIS AND SACROILIAC JOINT

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CHAPTER NINE PELVIS AND SACROILIAC JOINT

AXIOMS IN ASSESSING THE PELVIS AND THE SACROILIAC JOINTS

• The primary function of the pelvis, including the bones, joints, ligaments, and muscles, is mechanical transfer of weight.

• A secondary function of the bony pelvis is protection of viscera.

INTRODUCTION

The pelvis is a uniquely devised mechanism designed to transfer the body weight from the single weight-bearing axis of the trunk to the bipolar weight bearing of the lower extremities. The spine attaches to the pelvis by a single connection to the sacrum. Weight transfers through the bony ring of the pelvis from the spinal column to the two lower extremities. Enclosed within the pelvis are the bladder, the female genitalia, the rectum, and the great vessels and nerves that extend to the lower extremities.

Narrow, closely fitted, irregularly shaped, and cartilage-covered surfaces of the posterior and internal ilium and the lateral border of the sacrum form the sacroiliac articulation. The lumbosacral trunk lies anteriorly in direct relationship to the sacroiliac articulation. An inflammatory neuritis is a common accompaniment of sacroiliac arthritis. The anterior ligaments are thin and easily distended by intraarticular swelling.

The upper two thirds of the joint are covered posteriorly by the posterior end of the ilium. The lower third of the joint is covered by the sacroiliac ligaments but can often be palpated in thin individuals.

The conditions that affect the sacroiliac joints are those that involve any joint. The sacroiliac articulation is a favored site for tuberculous infection and is often the starting point for ankylosing spondylitis. Degenerative arthritic changes are often significant at this joint.

TABLE 9-1 PELVIS AND SACROILIAC CROSS-REFERENCE TABLE BY ASSESSMENT PROCEDURE

TABLE 9-2 PELVIS AND SACROILIAC JOINT CROSS-REFERENCE TABLE BY SYNDROME OR TISSUE

Fracture	Iliac compression test
Lumbosacral syndrome	Belt test Gaenslen test Smith-Petersen test

Pyogenic sacroiliitis Knee-to-shoulder test Sacroiliac disease

Anterior innominate test

Goldthwait sign

Iliac compression test

Knee-to-shoulder test

Lewin-Gaenslen test

Sacral apex test

Smith-Petersen test

Sprain

Iliac compression test

Knee-to-shoulder test

Lewin-Gaenslen test

Sacral apex test

Sacroiliac resisted-abduction test

Subluxation

Iliac compression test

Knee-to-shoulder test

Lewin-Gaenslen test

Sacral apex test

Sacroiliac resisted-abduction test

The stability of the sacroiliac joint lies in the nature of its articular surfaces and ligaments. Cardinal in this role are the dense, interosseous ligaments lying dorsal to the joint and the ventral sacroiliac ligament covering its anterior aspect.

In ankylosing spondylitis, the patient complains of spinal pain and stiffness. The sacroiliac joints are affected initially; increasing loss of spinal mobility can lead to loss of the lumbar lordosis.

A common tender fatty nodule in the sacroiliac area is sometimes called the episacroiliac lipoma or back mouse. In this instance, fatty tissue herniates through the normal deep fascia and become edematous and a source of pain. Clinically, the patient complains of pain in the tender nodules that are palpable and often bilateral. The mass is usually palpable as a mobile soft tumor that slips beneath the examining finger. Such a lipoma mass must be differentiated from the peripelvic serosanguineous cyst.

ESSENTIAL ANATOMY

The two innominate bones (or hip bones), the sacrum, and the coccyx make up the pelvis. The innominate bone consists of the ilium, ischium, and pubis.

ORTHOPEDIC GAMUT 9-1 INNOMINATE BONE

Exterior surfaces of the innominate bones:

1. An upper area, the lateral surface of the ilium

2. A central depressed socket, the acetabulum

3. A lower region, in which curved rami of the pubis and ischium form the obturator foramen

ORTHOPEDIC GAMUT 9-2 SUPERIOR HALF OF THE PELVIS

Interior surfaces of the superior half of the pelvis include:

1. Superiorly, the iliac fossa, a shallow depression in the ilium

2. A posterior roughened articular surface

3. Inferiorly, the medial surface of obturator foramen

The lumbosacral plexus takes shape on the medial surface of the levator ani muscle (Table 9-3).

TABLE 9-3 SACRAL PLEXUS

Anterior Divisions	Posterior Divisions
Nerve to quadratus femoris/inferior gemellus	Nerve to piriformis
	Superior gluteal nerve
Nerve to obturator internus/superior gemellus	Inferior gluteal nerve
	Posterior femoral cutaneous nerve^*
Posterior femoral cutaneous nerve^*	Common peroneal nerve
Tibial nerve Pudendal nerve Pelvic splanchnic nerves Nerve to levator ani/coccygeus

Perforating cutaneous nerve

* Both divisions contribute to this nerve.

Adapted from Mathers LH et al: Clinical anatomy principles, St Louis, 1996, Mosby.

ESSENTIAL MOTION ASSESSMENT

Although firmly constrained by its ligaments, the sacroiliac joint exhibits movements that are small in magnitude and complex in nature. The amplitude of nutation of the sacrum is normally not more than 2 mm or 2 degrees.

ESSENTIAL MUSCLE FUNCTION ASSESSMENT

The gluteal and erector muscles aid in stabilizing the spine and provide extension. To evaluate functional strength in spinal extension, the examiner places the patient in a prone position. The patient raises one arm out straight in front and simultaneously lifts the leg on the opposite side out straight. The patient holds this position for 5 to 10 seconds, and the examiner notes any fatigue or inability to gain a healthy contraction, especially on the side of the leg lift. This side activates the hip and spinal extensor mass. The patient repeats the exercise on the opposite side, and the examiner compares the observations.

ORTHOPEDIC GAMUT 9-3 LUMBOPELVIC FLEXIBILITY TESTING PROCEDURES

1. Spinal erector muscles: With the patient in the supine position, the examiner gently bends the patient’s knee to the chest.

2. Hip flexor muscles: With the patient prone, the examiner places the patient’s affected hip into extension and then abducts the thigh.

3. Hamstring muscles: Placing the patient supine and keeping the patient’s hips and buttocks down to the table, the examiner performs a straight leg raise with the patient’s knee held in extension.

4. Gluteal muscles: The patient should be supine and placed in hip flexion with a bent knee. The lower leg can be internally rotated with thigh adduction to facilitate a stretch of the rotator muscles of the hip, such as the gluteus medius and piriformis.

5. Quadriceps muscles: With the patient prone and the examiner’s inferior hand on the patient’s affected knee, the examiner uses the shoulder to move the patient’s lower leg gently toward the ipsilateral buttock to induce knee flexion.

ESSENTIAL IMAGING

The pelvis can be well visualized by a routine anteroposterior (AP) roentgenogram. In addition, the sacrum and coccyx may be studied by lateral views and AP views angled 15 degrees cephalad and caudad.

Radiographic evaluation can play an important role in ruling out an inflammatory arthritis. Conditions such as ankylosing spondylitis can have a clinical presentation similar to other spondyloarthropathies, with referral of pain into the hip and gluteal regions. After pregnancy, conditions such as osteitis condensans ilii can also be identified with plain films. In this case, the soft-tissue findings cannot be evaluated with plain films.

ANTERIOR INNOMINATE TEST

ALSO KNOWN AS MAZION PELVIC MANEUVER

Assessment for Unilateral Forward Displacement of the Ilia on the Sacrum

Comment

Many cases of acute low back pain that are not correctly identified evolve into a chronic spinal problem with significant disability at the muscular level (Table 9-4). Muscular fixation alone can be the cause of spinal joint dysfunction.

TABLE 9-4 LUMBOPELVIC SYNDROMES

Diagnosis	Site of Complaint
Quadratus lumborum syndrome	Gluteal region, anterior iliac spine, greater trochanter of femur
Gluteus maximus or medius syndrome	Sacral and gluteal region, lateral hip
Gluteus minimus syndrome	Lateral hip, thigh, and calf
Chronic lumbar strain (spinal erector muscles)	Laterally to ribs, caudally toward lumbosacral junction
Piriformis syndrome	Sacroiliac region; posterior hip, thigh, calf; possibly sole of foot

Adapted from Brier SR: Primary care orthopedics, St Louis, 1999, Mosby.

ORTHOPEDIC GAMUT 9-4 LUMBOPELVIC MUSCLES

Results of lumbopelvic muscle contractures:

1. Contracture of lumbodorsal fascia

2. Anterior pelvic tilt

3. Inappropriate transfer of loads to the lumbar spine

4. Difficulty in attaining the proper biomechanical posture for lifting

PROCEDURE

• The patient with lower trunk pain is in the standing position and is instructed to place the lower extremity that is opposite the painful side approximately 2 or 3 feet in front of the foot of the other extremity.

• This position is such that the patient appears to be taking a big step forward.

• The patient then bends the upper trunk acutely over the forward extremity so as to put all the weight on the front leg.

• The patient flexes to the point at which the heel of the back foot rises from the floor (Fig. 9-1).

• The production or aggravation of lower trunk pain on the side of the posterior leg indicates a positive test.

• A positive test indicates unilateral forward displacement of the ilia (anterior innominate) in relation to the sacrum.

FIG. 9-1

The sacroiliac joint, most inaccessible to palpation, is difficult to assess clinically. Only florid inflammation or damage to the fibrous portion is likely to result in local posterior tenderness. This tenderness is probably ligamentous.

BELT TEST

SUPPORTED ADAMS TEST

Assessment for Sprain of the Sacroiliac Ligaments or Lumbosacral Capsular Sprain

PROCEDURE

• The patient with lower back symptoms is in the standing position.

• The patient flexes the dorsolumbar spine while the examiner notes the amount of movement necessary to aggravate the pain.

• While positioned behind the patient, the examiner grasps the patient’s iliac crests and braces a hip against the patient’s sacrum.

• The patient flexes the spine again as the examiner immobilizes the patient’s pelvis (Fig. 9-2).

• If the lesion is of a pelvic nature, flexing the spine with the pelvis immobilized will not reproduce the discomfort.

• If the lesion is of a spinal nature, the pain will be aggravated in both instances.

FIG. 9-2

Because of the stabilizing effect of the very strong ligamentous structures, sprain of the sacroiliac ligaments accompanies sacroiliac subluxation and is a subluxation sprain. Posterior subluxation results from a flexion-type injury, which occurs with activities such as lifting or pushing. Anterior subluxation results from extension-type injuries, which occur when falling forward or extending the leg.

ERICHSEN SIGN

Assessment for Sacroiliac Disease versus Pathologic Conditions Involving the Hip Joint

ORTHOPEDIC GAMUT 9-6 ACETABULAR FRACTURES

In general, acetabular fractures involve one or more of the following:

1. The posterior rim

2. The posterior column

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