Hip Sonography (eBook)

Contributors 8
Acknowledgement 9
Foreword 10
Introduction 12
Where Is the Problem? 12
How to Solve the Problem 12
How to Use This Manual 13
Contents 14
1 Technique 16
1.1 Equipment 17
1.2 Additional Equipment for Hip Ultrasound 17
1.3 Image Projection 17
2 Anatomy and Ultrasound of the Normal Infant Hip Joint 20
2.1 Explanation of Terminology Used in Describing the Ultrasound Anatomy 21
2.2 Ultrasound Characteristics of the Different Tissues in the Region of the Hip Joint 21
2.3 The Proximal Femur in Hip Ultrasound 21
2.4 Femoral Head 22
2.5 The Acetabulum (Fig. 2.8) 29
3 The Standard Plane 34
3.1 The Principle of the “Standard Plane” 35
3.2 The Problem of the Variable Bone Coverage of the Femoral Head 36
4 Identifying the Anatomy and Checking the Landmarks and Tilting Eff ects 42
4.1 Anatomical Identification 43
4.2 Checking the Landmarks 43
4.3 Checking a Hip Sonogram 45
5 Definition of Types 46
5.1 Type I 48
5.2 Type II 49
5.3 Type III 49
5.4 Type IV 50
5.5 Differentiation Between Ossification and Degeneration 50
6 Ultrasound Classification 54
6.1 Description 55
6.2 Systematic Reporting of a Sonogram 58
7 Measurement Technique 60
7.1 The Bony Roof Line ( Fig. 7.1a) 61
7.2 Base Line ( Fig. 7.2a – c) 61
7.3 Cartilage Roof Line ( Fig. 7.3a – c) 63
8 Classification Using the Sonometer 66
8.1 The Alpha Values 67
8.2 The Beta Value 68
8.3 Classification in Premature Infants 8.4 Certainty of the Diagnosis 70
9 Instability 72
9.1 Elasticity “ Elastic Whipping” ( Fig. 9.1. b – d) 74
9.2 Pathological Instability 75
9.3 Summary of the Principal Differences Between Elasticity and ( Pathological) Instability 75
10 The Terminology of Dislocation 76
11 Scanning Technique 78
11.1 Preparation 79
11.2 Leading and Guiding the Mother 79
11.3 Scanning Procedure 80
11.4 Errors 84
12 Errors Due to Tilting the Probe 90
12.1 Antero- posterior Tilting 91
12.2 Postero-anterior Tilting 91
12.3 Cranio- caudal Tilting 91
12.4 Caudo- cranial Tilting 91
12.5 Cradle and Probe- Guiding Equipment ( Figs. 11.1c, 11.4b) 92
13 Documentation and Quality 96
13.1 Image Documentation 97
13.2 Written Report 97
13.3 Tips for Checking and Ensuring the Quality of One’s Own Sonograms 97
14 Principles of Ultrasound- Based Management 98
14.1 Basic Biomechanical Aspects Behind the Principles of Treatment 99
14.2 Goals of Treatment 99
14.3 Stages of Treatment 99
14.4 Why Errors Occur 108
15 Appendix 110
Suggested Reading 122

2 Anatomy and Ultrasound of the Normal Infant Hip Joint (p. 5-6)

2.1 Explanation of Terminology Used in Describing the Ultrasound Anatomy Echo hole:
("Sound hole") anechoic or hypoechoic area caused by tissues with low echogenicity (re- flectivity), e.g. hyaline cartilage

Echo shadow or acoustic shadow: anechoic area caused by total reflection of the ultrasound beam, e.g. bone

2.2 Ultrasound Characteristics of the Different Tissues in the Region of the Hip Joint

Bone: Seen as a bright echo with an acoustic shadow behind it. This is because bone is highly reflective and blocks the through transmission of the ultrasound beam, preventing structures deep to the bone being seen by ultrasound. Relevant structures in the region of the hip joint are where the bone meets cartilage:

• The ilium immediately above the acetabulum.
• The lower limb of the os ilium in the floor of the acetabular fossa.
• Femoral head ossific nucleus (when present)
• The bony ischium.

Collagenous Connective Tissue and Fibrocartilaginous Structures: These are highly echogenic but echolucent allowing through transmission of the ultrasound beam so that structures deep to them can be seen.

These are:

• The joint capsule and the synovial (capsular) fold.
• The perichondrium of the cartilaginous acetabular roof and of the greater trochanter.
• The acetabular labrum.
• The ligamentum teres and the fovea in the femoral head.
• The intermuscular septa and the tendons of the reflex head of the rectus femoris muscle.
• The transverse acetabular ligament.

Ossification Within Hyaline Cartilage: Developing blood vessels and the condensation of cells that precede ossification give bright echoes but are sonolucent. These occur within the femoral head and at the chondro-osseous junction in the acetabular roof. These must be differentiated from the echoes that can occur in the hyaline cartilage roof of decentred hip joints when fibrocartilaginous degeneration caused by pathological pressure and shearing occurs.

Fat and Fibrous Connective Tissue: Usually give few or weak echoes, sometimes fat may be anechoic. In the infant hip fatty tissue may be seen as a hypoechoic zone in the acetabular fossa between the lower limb of the os ilium and the ligamentum teres or between the insertion of the joint capsule and the reflex head of the rectusfemoris muscle.

Hyaline Cartilage: Is hypoechoic or anechoic (depending on machine settings). The sinusoidal vessels may be seen as faint serpiginous echoes. Hyaline cartilage is found in:

• The femoral head, proximal femoral neck and greater trochanter of the femur.
• The cartilaginous portion of the acetabular roof.
• The lunate surface of the acetabulum.
• The triradiate cartilage.