Bio Mechanic of Elbow Joint

IBOMECHANIC OF ELBOW JOINT

ARAMBAM MEITEILEIMA

CHANU

1ST YEAR MPT.

CONTENTS• 1. INTRODUCTION

• 2. ANATOMY

• 3. KINEMATICS

• 4. CARRYING ANGLE

• 5. ELBOW STABILITY

• 6. KINETICS

• 7. ELBOW JOINT FORCES

8. SUMMARY

INTRODUCTION• THE ELBOW JOINT IS A COMPLEX JOINT

• IT FUNCTION AS A FULCRUM FOR THE FOREARM LIVER SYSTEM AND IS RESPONSIBLE FOR THE POSITIONING OF HAND AT SPACE

• THE ELBOW COMPLEX CONSIST OF ELBOW JOINT(HUMEROULNAR AND HUMERORADIAL ARTICULATION) AND THE DISTAL PROXIMAL RADIOULNAR JOINT.

FLEXOIN AND EXTENSION OCCUR AT THE SAGITTAL

PLANE AROUND THE CORONAL AXIS.SUPINATION AND PRONATION OCCUR AT THE TRANSVERSE PLANE

AROUND THE LONGITUDINAL AXIS.

ANATOMY

– The joint complex allow two types of movement namely flexion- extension and supination – pronation

• ARTICULATING SURFACE-THE ARTICULATING SURFACE OF THE RADIUS AND ULNAR INCLUDES THE RADIAL HEAD AND THE TROCHELAR NOTCH.THE ARTICULATING SURFACE ON THE DISTAL HUMEROUS INCLUDES THE CAPITULUM AND THE TROCHLEAR.

FLEXION AND EXTENSION IS ALLOW BY THE HUMERORADIAL AND HUMEROULNAR ARTICULATIONTI IS A HINGE OR SINGLYMOID JOINT.

THE PROXIMAL RADIOULAR ARTICULATION ALLOWS THE FOREARM PRONATION AND SUPINATIONAND IT IS CLASSIFIED AS A TROCHOID JOINT.

SO THE ELBOW JOINT COMPLEX IS TROCHLEOGINGLYMOID JOINT.

THE TROCHLEA AND CAPITELLUM OF THE DISTAL HUMEROUS ARE INTERNALLY ROTARTED TO 3 TO 8.AND 94 TO 98 OF VALGUS WITH RESPECT TO THE LONG

AXIS OF HUMEROUS.THE DISTAL HUMEROUS IS ANTERIORLY ANGULATED 30 ALONG THE AXIS OF THE

HUMEROUS.THE ARTICULATING SURFACE OF ULNA IS

ORIENTED IN APPROXIMATELY 4 TO 7 OF VALGUS

ANGULATION WITH RESPECT TO THE LONGITUDINAL AXIS OF THE ITS SHAFT.

Angular orientation of the distal humerus in the AP- A, L-B, and axial(c) projection

KINEMATICS• FLEXION - EXTENSION, SUPINATION -

PRONATION ARE THE MOVEMENTS OCCURING AT THE SHOULDER COMPLEX

• FLEXION -EXTENSION TAKE PLACE AT THE HUMEROULNAR AND HUMERORADIAL ARTICULATION.

• NORMAL RANGE- 0-146(FUNCTIONAL RANGE 30-130)

• AXIS IS RELATIVELY FIXED AND PASSES THROUGH THE CENTER OF CAPITULUM AND TROCHLEAR

• CAPITULUM BISECTING THE LONGITUDINAL AXIS OF THE SHAFT OF THE HUMEROUS

• • SUPINATION AND PORONATION TAKE PLACE AT THE

HUMERORADIAL AND APOXIMAL RADIOULNAR JOINT

• THE NORMAL RANGE OF FOREARM PRONATION SUPINATION AVERAGE FROM 71 OF PRONATION TO 81 OF SUPINATION

• THE AXIS OF MOTION IS A LONGITUDINAL AXIS EXTENDING FROM THE CENTER OF RADIAL HEAD TO THE CENTER OF ULNAR HEAD

• SUPINATION THE RADIUS AND ULNAR LIES PARALLEL TO ONE ANOTHER WHEREAS IN PRONATION THE RADIUS CROSS OVER THE ULNAR

• CARRYING ANGLE CAN BE DIFINE AS THE ANGLE BETWEEN THE ANATOMICAL AXIS OF THE ULNAR AND HUMEROUS(FIG)

• THE ANGLE IS LESS IN CHILD THEN IN ADULTS AND GREATER AT FIMALE THEN IN MALE AVERAGING 10 AND 13 OF VALGUS

CARRYING ANGLE

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Carrying angle of the elbow form byThe interception of the long axes of the humerus and ulna

*********• When the carrying angle is increase

beyond the normal range it is called cubitus valgus.

• Normaly carrying angle is disappear when the forearm is pronated and the elbow is in full extension and when the forearm is flexed against the humerous in full elbow flexion.

ELBOW STABILITY

• IT IS PROVIDED BY THE LEGAMENTS,MUSCLES,CAPSULES, AND ARTICULATING SURFACE OF THE ELBOW JOINT.

• THE MEDIAL COLLATERAL LEGAMENT AND JALERAL COLLATERAL LEGAMENT ARE MAINLY RESPONSIBLE FOR ELBOW STABILITY.

.

• Valgus force are resisted primarily by the anterior band.It is tighten in elbow at extension and posterior band tighten during the elbow flexion

• However in case there is disrupted anterior band the radial head becomes the primary restraint to valgus stress emphasizing it function as a secondary stabilizer in elbow with an intact MCL.

*******• In extension resistance to valgus force

is sear equaly by MCL complex , capsule(anterior)joint articulation.

• In flexion the primary resistor to valgus stress is the MCL complex the elbow articulation follow by the anterior capsule and LCL complex.

*****• The LCL is important stabilizer of the

humeroulnar joint.The ulnar collateral legament is the primary risistent to posterolateral instability to the elbow joint follow by the radial colletral legament and capsule

• Structure limiting the passive flexion include capsule,triceps,coronoid process and radial head.

• Structure limiting extension include olecranon process and anterior band of MCL complex

Legamentous structures that provide stability for the radioulnar joint

*********• The annular legament is a srtong band that

forms four-fifth of a ring that encircle thr radial head.

• The quadrate legament extend from the inferior edge of the ulnar”s radial notch to insert the neck of the radius.

• The qoadrate legament reinforces the inferior aspect of the joint capsule and help to maintain the radial hear in appositon to the ridial notch

The qoadrate legament also limits the spin of the radial Head in supination and pronation .The olique cord extendFrom the attachment just inferior to the radial notch to the Ulna.

fibres of the olique cord are at right angle to the Fibres of inrerosseous membrane.its function is to assist In preventing seperation of radius and ulna.

The interosseous membrane is a broad collaginous sheet That run between the radius and ulna.It provide stability To both the superior and inferior radioulna jointIt also provide the transmission of force from hand andDistal end of the radius to the ulna..

KINETICS

• ELBOW JOINT FORCES-43% forces acting longitudinaly to the elbow joint are transmited through the ulnotrochlear joint and 57% are transmited through radiocapitellar joint(halls and travill)

• The elbow joint compressive force is eight times the weight held by the outstretch hand.(ewald)

****• joint ranges from one to three times body

weight.force transmited through the radial head is gretest between 0 and 30 of flexion and is greatest in pronation than supination.(an and morrey)

• During weight lifting the resultant force at glnohumeral joint ranges from one to three times body weight.

****• Increase flexion strength and decrease elbow

force is seen with the elbow at 90 flexion.this is because of the increase mechanical advantage of the elbow flexor secondary to the lengthening of the flexor moment arm.

• The force generated to elbow has been seen to be three times body weight than the body weight in certain activities .during dressing and eating activity the joint reaction force is 300 N

****• Rising from the chair resulted in a joint reaction force of 1700N and pulling a table 1,900,N

summary

• The elbow joint consist of 3 articulation that allow 2 movement

• Functional range of elbow motion is 30 to 130 of flexion and extension and 50 to 50 of pronation-supination

• Axis of rotation of flexion and extension is located at the centre of trochlear and capitulum in lateral view

• Carrying angle

*****• Anterior band of MCL is the primary stabilizer to valgus force.lateral ulnar collateral legament is the stabilizer to p-l rotatory instability of elbow

• Brachialis and tricep are the primary flexor and extensors,.bicep brachii and pronatar quadratus are the primary supinator and pronator respectively

• Force in elbow is 3 times the body weight when doing activitys

THANK U