Elbow anatomy and biomechanics

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Elbow: Functional anatomy and biomechanics

Adam C Watts Consultant Elbow and Upper Limb Surgeon, Wrightington

Hospital

Visiting Professor, University of Manchester

4

5

“....just a hinge between the

shoulder and the wrist.”


Kinetic Chain

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Functional range

Flexion 30-130 degrees

Pronosupination 50-0-50

Range of motion

Extension 10 to -10

degrees

Flexion 135 to 145

degrees

Pronation 80 degrees

Supination 80 degrees

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Bones


Cubitus Varus Normal Cubitus Valgus


15 degrees


Intracapsular Structure

25


Coronoid


Posterior medial rotation Posteromedial rotatory instability


Ligaments

0%

100%

LATERAL

0%

100%

LATERAL

0%

100%

MEDIAL

0%

100%

MEDIAL

A B

C D


MEDIAL

MEDIAL

LATERAL

LATERAL

0%

100%

0%

100%

0%

100%

0%

100%

E

F



MRI elbow


PLRI

48


Muscles and Tendons

55


Distal Biceps Tendon Anatomy

56


Clinical Examination

60


O’Driscoll Hook Test


MRI - Snapping Triceps

66


Risk Factors

Male Gender

Youth (mean age 23 years)

Athlete

Previous supracondylar fracture

75


Is there a role for MRI?

80


Wrong Diagnosis


Joint Reaction Force

82


Load Transmission

60%

40%


Elbow Stability

Primary stabilisers MCL - anterior bundle Coronoid Lateral ligament complex Olecranon

Secondary stabilisers Radial head Common flexor and extensor origin Anterior capsule

Radial head Coronoid Lateral ligament complex MCL - anterior bundle Common flexor and extensor origin


Elbow Stability

At 90 degrees flexion Anterior bundle MCL primary valgus restraint

In extension Radial head = MCL = Capsule

Most instability is rotational Lateral ulna collateral ligament is prime

89


Summary

Elbow is a “sloppy hinge”

More “sloppy” laterally than medially

Stability comes from

Bone

Ligaments

Muscles

but … muscles require a nerve supply

90


Ulnar nerve


Applied Anatomy

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Arthroscopic arthrolysis97

How do elbow biomechanics change with pathology?

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How does OA change things?

Joint space narrowing radiocapitellar >> ulnohumeral

Osteophyte formation

Capsular thickening and contracture

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Patterns of Osteophyte Formation

64% Olecranon

95% Coronoid

86% Medial Ulnohumeral Joint

59% Anterior Trochlea

41% Radial Head


Boxers Elbow

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Pre-operative Plan

108


Summary

Elbow anatomy and biomechanics complex

Stability provided by bone, ligaments and muscles

abMCL, LCLC, Coronoid and radial head most important in trauma


60°

110°

130°

40°

Elbow anatomy and biomechanics

Healthcare

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