= BONE & JOINT = ANATOMY & NORMAL US FINDINGS

Transcription

1 Dongguk Univeristy 1 = BONE & JOINT = ANATOMY & NORMAL US FINDINGS 동국대일산병원재활의학과이호준

2 Dongguk Univeristy 2 = BONE = ANATOMY (& HISTOLOGY)

3 Dongguk Univeristy 3 Bone : Histology Epiphysis Filled with bone marrow Developed from a secondary ossification center Metaphysis Epiphyseal plate epiphyseal line Diaphysis Cortical (compact)bone : peripheral Medullary cavity : central (trabecular or cancellous) Thickness Diaphysis cortical bone > trabecular bone Metaphysis / epiphysis cancellous bone > cortical bone

4 Dongguk Univeristy 4 Bone : Histology Medullary cavity (bone marrow) Yellow marrow (housing fat, connective tissue) Red marrow (hematopoietic cells, fat, connective tissue)

5 Dongguk Univeristy 5 Bone : Histology Cortical bone Periosteum perforating Sharpey fibers anchored to the cortical bone Allowing rapid healing of fractures Nutrient foramina Nutrient arteries and emissary veins cross the cortical bone.

6 Dongguk Univeristy 6 Ossifications Intramembranous ossification Direct mineralization of vascular connective tissue Stem cell: osteoblast Growth of flat bones Contributes to the width of the shaft of long bones. Endochondral ossification Within a cartilage model (in hyaline cartilage) Stem cell: chondroblast, osteoblast The longitudinal growth of long bones the formation of the axial skeleton

7 Dongguk Univeristy 7 Intramembranous ossification

8 Endochondral ossification Dongguk Univeristy 8

9 Dongguk Univeristy 9 = BONE = NORMAL US FINDINGS

10 US - Bone Acoustic impedance high mismatch Reflectivity R(%) = {(Z 2 -Z 1 ) / (Z 2 +Z 1 )} 2 x 100 (angle:90) Acoustic impedance of various materials Material Acoustic impedance (gm/cm 2 sec x 10-5 ) Air Fat 1.38 Water 1.54 Blood 1.61 Muscle 1.70 Cortical bone 7.8

11 Dongguk Univeristy 11 US - Bone Bone cortex Regular continuous bright hyperechoic line Strong posterior acoustic shadowing Limitations of US Deeper structures : inaccessible Internal cortical architecture Endosteum Underlying trabecular bone Periosteum (normal adult) cannot be detected as a separate structure Artifact: Reverberation

12 Dongguk Univeristy 12 Vs other modalities Simple radiography first-line imaging modality for assessment of bone disorders CT More accurate analysis complex anatomic areas optimal assessment of the bone cortex MRI evaluate the bone marrow

13 Dongguk Univeristy 13 Bone surface abnormality Outgrows (or plus images ) Irregularities of the cortical outline Defects (or minus images )

14 Dongguk Univeristy 14 Normal anatomy can be confused as abnormality Nutrient vessels sites of penetration subtle surface irregularities Doppler imaging: helpful

15 Dongguk Univeristy 15 Normal anatomy can be confused as abnormality Sesamoid / Calcification posterior acoustic shadowing located in close relationship with the bone surface cortical breaks (X)

16 Dongguk Univeristy 16 Normal anatomy can be confused as abnormality Growth plates in the immature skeleton resemble a focal discontinuity of the bone surface peculiar anatomic location distinguished from fractures

17 Normal anatomy can be confused as abnormality Marginal osteophytes or bone spurs project over the cortex mimic focal break Dongguk Univeristy 17 Need close correlation with standard radiographs

18 Normal anatomy can be confused as abnormality Previous surgery Focal interruptions of the hyperechoic cortical line After construction of bone tunnels After ligament reconstruction surgery After ablation of screws and pins close correlation with standard radiographs Dongguk Univeristy 18

19 Dongguk Univeristy 19 Normal anatomy can be confused as abnormality Focal projections (tuberosities, ridges) & defects (fossae, sulci) of bone Modulate the cortical surface associated with tendon or ligament insertion (tuberosities, ridges) or tendon and nerve reflecion (sulci) outgrowth or depression of otherwise straight cortical outline

20 Dongguk Univeristy 20 Normal anatomy can be confused as abnormality Anatomic variation of sulci & tubercle Shallow bony groove (ex: biceps tendon instability) Predispose to tendon instability Tubercle hypertrophy (ex: peroneal tubercle hypertrophy) Act as reflection pulley for tendon stenosing tenosynovitis

21 Endochondral ossification Dongguk Univeristy 21

22 Dongguk Univeristy 22 = JOINT = ANATOMY (& HISTOLOGY)

23 Dongguk Univeristy 23 Classification (anatomic structure) of joint Fibrous joints Cartilaginous joints Synovial joints (m/c)

24 Dongguk Univeristy 24 Fibrous joints (Dense fibrous tissue) Linked by invervening solid connective tissue (fibrous tissue) No cavity Sutural ligament (sutures) (Ex: skull) Collagenous inter-osseous ligament or membrane (syndesmoses) Cartilaginous periodontium (gomphoses)

25 Dongguk Univeristy 25 Cartilaginous joints Articulating bones connected by cartilage No joint cavity, No synovium Symphysis: (Ex: IV disk, symphsis pubis) Fibrocartilage Cartilage (hyaline) is fused to an intervening pad of fibrocartilage Synchondrosis: (Ex: 1 st rib sternum) Hyaline cartilage Epiphyseal plate connecting epiphysis and diaphysis regions of long bone

26 Dongguk Univeristy 26 Synovial joints (m/c) connected by a cavity lined by synovial membrane allow different degree of motion Articulating bone surfaces (bone plate) Fibrous capsule Ligaments Synovium Other intra-articular structures Meniscus Labrum Ligaments (Ex: ACL) Fat pads

27 Dongguk Univeristy 27 Synovial joint: hyaline cartilage 4 cartilage layers Superficial layer: Transitional layer: randomly arranged Radial zone, calcified layer: vertical orientation Composition Chondrocytes: 0.1% of cartilage volume Chondroid matrix (collagen, proteoglycans)

28 Dongguk Univeristy 28 Synovial joint: hyaline cartilage Main function Absorption of load (graded deformation & distribution to bone) Deformation: transient squeezing of water, compression of collagen fiber thickness Removal of load return to normal Cover articular surface protect bone plate Cartilage thickness variance Larger joint thicker (weight-bearing joints) same joint: as an expression of local differences in load

29 Dongguk Univeristy 29 Synovial joint: bone plate The subchondral bone plate thin layer of dense bone - linked to metaphysis Main function adsorb & transfer load to cortical bone through metaphysis Microstructure: peculiar orientation of trabeculae

30 Dongguk Univeristy 30 Synovial joint: capsule Thickness variance: local demand & fxn (fig 5-17 a) G-H joint: thin, lax allow wide ROM Ant hip joint: thick help in maintaining an erect posture Marginal to articular surface: insert into cortical bone and periosteum

31 Dongguk Univeristy 31 Synovial joint: synovium Synovium Produce Synovial fluid Clear, pale yellow viscus fluid Lubricate joint Cartilage nutrition Lines joint cavity Except hyaline cartilage, IA fibrocartilage, fat pad Bare area ( ) Transitional zone (bone) btw hyaline cartilage & capsule Synovial fluid invest Hyaline cartilage (-) vulnerable to synovitis-induced bone destruction Fibrocarilage structures (*) Fat pad ( ) Reinforcement, stabilization of capsule Stabilization of joint : by fiber orientation )

32 Dongguk Univeristy 32 Synovial joint: synovial recess Capsule: focal discontinuity synovial recess (1) Main function Facilitate gliding of paraarticular tendons Reservoir : limiting damage to intra-articular structures Link : joint cavity tendon sheath (2) Sesamoid (*) Small ossicle Can or can t articulate with joint surface

33 Dongguk Univeristy 33 Synovial joint: ligament 2 situations Completely independent of capsule (2) LCL (knee) Focal capsular thickening (1) G-H joint Strongest ligament (3) insert into para-articular bone ridge or tubercle oriented to counteract joint instability Functions Reinforcement, stabilization of capsule Stabilization of joint : by fiber orientation

34 Dongguk Univeristy 34 = JOINT = NORMAL US FINDINGS

35 Dongguk Univeristy 35 Advantage of US in joint Identify & quantify IA effusion (Ex: hip) US-guided arthrocentesis of joint fluid less painful, rapid sampling Correct IA injection Image of large and lax joint Improved by repositioning articular surface (dynamic scan) (Ex: trochlea in knee joint, MC head)

36 Dongguk Univeristy 36 US findings - Normal synovial joint Articular surfaces: covered with hyaline cartilage Superficial echogenic acoustic impedance mismatch (cartilage vs fluid) Intermittent hypoechoic band hyaline cartilage (d/t homogeneous transparency due to its high water content) Deep hyperechogenic layer cartilage subchondral bone interface

37 Dongguk Univeristy 37 US findings hyaline cartilage Hyaline cartilage Normal hyaline cartilage Homogenous hypoechoic smooth linear band Subchondral bone Regular, continuous bright hyperechoic line

38 Dongguk Univeristy 38 US findings capsule, synovium Joint capsule Hyperechoic line overlying cartilage Synovium Normal: too thin to detect Pathologic: thickening, hypertrophy Fat pad Hip joint Knee, suprapatellar recess

39 Dongguk Univeristy 39 US findings Fibrocartilage (1) Fibrocartilage - capsule Labrum (GH jt, hip jt) Adherent to bone or joint capsule Homogenous hyperechoic smooth linear band d/t collagen fiber (high reflectivity) : predominant Joint capsule hyperechoic line

40 Dongguk Univeristy 40 US findings Fibrocartilage (2), IA Meniscus, TFCC Not accurate Diagnosis of fibrocartilage tears Deep location, close contact with bone Ddx ( tear vs degenerative states ) : similar echo-textural pattern difficult Only superficial part detectable with US Extruded meniscus Menisco-capsular detachment with fluid intervening Meniscal ossicle Medial Meniscus TFCC

41 Dongguk Univeristy 41 US findings - ligaments Hyperechoic fibrillar band Anisotropy (+) Complex ligament MCL, deltoid lig Individual fiber distinguishable Best evaluated while stretched Ex: CFL - ankle Relaxed: concave cranial insertion: not visible ADF tighten push peroneals superficially better depicted Ligament vs capsule Internal: LCL Bending: MCL, ATFL, GH External: ACL