Dalhousie Mini Med School
Born Loose Vs Torn Loose
Why Do Joints Dislocate?
October 15, 2015
Catherine Coady, MD, FRCSC
Dalhousie University
BORN VS TORN
LOOSE
LOOSE
01 BALL & SOCKET
02 HINGE
Ball & socket joints have a rounded ball
like end on one side fitting into a cuplike socket on the other side. This type
of joint allows for the greatest range of
motion.
Hinge joints allow bending and straightening movements. The elbow joint is an
example of a hinged joint.
03
Types of Joints
GLIDING
Gliding (planar) joints have joint surfaces
that are relatively flat and similar in size.
Side to side and back and forth movement
is allowed with these joints. Examples
include the carpal bones of the wrist and
the tarsal bones of the foot.
FIBROUS
The bones of fibrous joints
are joined by fibrous tissue,
such as the sutures in the
skull or the pelvis. Fibrous
joints allow no movement at
all.
CARTILAGINOUS
The bones of cartilaginous
joints are joined by cartilage,
such as the sternocostal joint
between the sternum and
first rib. These joints allow a
very small amount of movement.
SYNOVIAL
The bones of synovial joints
meet in a joint capsule, such as
the knee joint where the femur
and tibia meet. These joints are
the most common and most
moveable joints in the human
body.
SYNOVIAL
JOINTS
“909 Types of Synovial Joints” by OpenStax College - Anatomy & Physiology, Connexions Web site. http://cnx.org/content/col11496/1.6/, Jun
19, 2013.. Licensed under CC BY 3.0 via Commons - https://commons.
wikimedia.org/wiki/File:909_Types_of_Synovial_Joints.jpg#/media/
File:909_Types_of_Synovial_Joints.jpg
04 SADDLE
05 PIVOT
The joints have surfaces that resemble a
saddle. They allow for side to side and
back and forth movements. An example
is the base of the thumb joint.
“JOINT”
Pivot type of joints allow for rotation of
one bone on another. An example of this
joint is in your neck between the C1 vertebrae (atlas) and C2 vertbebrae (axis)
A joint (articulation) is the location where the bones connect.
They allow movement and provide
mechanical support.
06 ELLIPSOID
Ellipsoid (condyloid) joints allow back
& forth and side to side movements.
Examples would be the joints in the wrist
and fingers.
HOW DO
JOINTS
DISLOCATE?
Synovial joints are the most movable
type of joint in the human body
Articular Cartilage:
Ligaments:
Joint Capsule:
Meniscus:
Synovial Fluid:
Bursa:
Smooth glisteny surface that covers
the ends of the joint surfaces. It protects the joint surface and reduces
friction.
Strong fibrous tissue that surrounds the joint. It adds stability
to the joint and protects the joint.
It also allows the synovial fluid to
be contained.
Fluid that lubricates the joint
surfaces, provides nutrients for the
cartilage and forms a fluid cushion
between surfaces.
Strong fibrous bands that join the
bones together at the joint. They
assist in contorlling movement and
they provide joint stability.
Tough fibrous tissue that are present
in certain synovial joints (knee).
They function as shock absorbers.
They also protect the articular cartilage and assist in joint stability.
They are found in certain synovial
joints. They help reduce friction
especially where tendons are close
to boney prominences.
BORN
TORN
Loose
Dislocation
vs
Subluxation
Loose
Dislocation
Also known as luxation, occurs when
the ends of your bones are forced out
of position.
JOINT HYPERMOBILITY
“Double Jointed” - “Loose Jointed”
• 10% of general population have a degree of hypermobility
• Women: Men ration is 3: 1
• Hypermobility is a common condition in children since their connective tissues are not completely developed. Some children may
“outgrow” their hypermobility.
• Hypermobile joints occur when the ligaments holding the joints
are loose and is often associated with muscle weakness around the
joints.
• Most people with hypermobility do not develop any problems
from their “loose jointedness”
Joints most
commonly
affected by
hypermobility
include:
Shoulders
Elbows
Wrists
Fingers
Knees
Beighton Score:
• Is a screening technique for
hypermobility
• There are a total of 9 maneuvers.
• A point is gained for each
movement that the person can
positively perform
• A score of 3/9 is mildly hypermobile.
• A score of 9/9 would indicate
extreme hypermobility
Subluxation
Occurs when the joint comes out of
place partially and then goes back into
position (reduces)
Beighton Score
Joint Dislocations
Any joint in the body has the potential
to dislocate. However, there are some
that are more susceptible than others
such as the shoulder joint. Other
common joints for dislocation are
patellofemoral, elbow, wrist, finger,hip
and the foot.
Joint dislocations are caused by
trauma to the joint. Typically there
is a significant and sudden force
applied by either a blow or a fall
that causes the bones in the joint
to dislocate from their normal position. With each dislocation, the
ligaments that help to stabilize the
joint can be damaged or loosened
making it easier for the joint to dislocate in the future.
Normal X-ray of kneecap (patella)
Bankart Tear
X-ray of dislocated kneecap (patella)
In individuals who have traumatic joint
dislocations, there is further trauma to
the joint stabilizing structures such as the
ligaments, the surrounding soft tissues
and muscles, as well as the bone. In the
shoulder joint, there can be damage to
the labrum, the ligaments, the rotator cuff
muscles, the humeral head (Hills Sachs
lesion) and the glenoid (socket of the
shoulder joint).