Background

Before we continue to learn  about  the musculoskeletal system in detail we  need  to consider  some  background information  about  the  types of musculoskeletal problems   and  conditions and  about  the  terminology used during medical  examinations.

Types of musculoskeletal  problems and conditions

There are a surprisingly large number  of conditions (over 200) that can affect the musculoskeletal system. A careful history and examination will allow the doctor to classify the condition into one of the following broad groups:

• Conditions affecting the joints.  “Arthritis” is used  to describe  these conditions:
  • Osteoarthritis.
  • Inflammatory  arthritis, such as rheumatoid arthritis or gout.
• Conditions affecting the spine:
  • Neck pain.
  • Back pain.
• Conditions affecting soft tissues:
  • Bursitis.
  • Tendonitis.
  • Fibromyalgia.
• Conditions affecting the bones:
  • Osteoporosis

Sometimes  a person  has pain  affecting the musculoskeletal system and no physical  cause  can be found.

It is beyond  the scope  of the programme to consider  all of the musculoskeletal conditions  in  detail,  so  we  shall  concentrate on  the more common ones. It is important  to remember that other conditions do exist and as a Patient Partner you may have one of these other conditions. Do  not  be  worried  by this; the  ability  to demonstrate your  own  joint function  is what  is crucially  important  to the programme. If you would like to learn more about musculoskeletal conditions, then there are some books  and  websites  listed  at the  end  of the  manual  that you  may  find helpful.

Osteoarthritis

(os-tee-oh-are-thry-tis)

Osteoarthritis (OA) affects about  15 people  in 100,  and  after age 55 is more common in women  than men.

In OA  there  is a  thinning,  often  progressing  to  complete loss,  of the cartilage  that covers  the surface  of the joint (Figure 4). It can also affect the underlying  bone.

OA may arise without  an apparent cause  or may occur  after damage  to a  joint  from  inflammation (which  might  be  a  result  of infection), too much  stress on the joint or traumatic  injury. It can sometimes  run in the family. OA of the  hip  and  knee  are  more  common in people who  are overweight.

OA  commonly affects  load-bearing joints  such  as  the  spine,  hips  or knees and can also affect the finger joints; it may only affect one side of the body.

The most common symptom  of OA is pain  in the affected  joint(s) after repetitive  use. Joint pain  is usually  worse  later in the day. There can  be swelling,  warmth  and crepitus  (creaking) of the affected joints.

Pain  and  stiffness  of  the  joints  can  also  occur  after  long  periods   of inactivity – for example,  sitting watching  television  or in a car on a long journey.

In  severe  OA,  complete loss  of  the  cartilage  cushion   causes  friction between bones,  causing  pain at rest or pain with limited motion.

Symptoms of OA vary greatly from patient  to patient.  Some patients  can be debilitated by their symptoms.  On  the other  hand,  others  may have remarkably  few symptoms in spite of dramatic  degeneration of the joints apparent on x-rays. Symptoms also can be intermittent.  It is not unusual for patients  with OA of the hands  and  knees  to have  years of pain-free intervals between symptoms.

Rheumatoid arthritis

(rew-ma-toyd  are-thry-tis)

Rheumatoid  arthritis (RA) occurs   in  one   person   in  100   and   most commonly affects women  between the ages of 40–50.  It is an important cause  of disability.

In RA there is inflammation of the lining of the joints which  causes  joint damage  (Figure 6), which  starts early and progresses  slowly with time. It also  has  a  major  effect  on  what  people   can  do,  commonly  causing people  to have to give up their work. Modern  treatments can slow down the progression  of RA and have considerably improved  the outcome over the past 10 years.

The   causes   of  RA  are   unclear,  but   there   is  evidence  of  genetic predisposition to the disease.

RA is rare in young people;  in men peak incidence is at age 60–70 years, in  women   it increases   in  incidence in  the  mid–20s  to  reach  a fairly constant  level at 45–75  years, being slightly greater at 65–75  years.

Typically,   the   condition  most   commonly  affects   the   finger  joints, knuckles  and  wrists, feet and  ankles,  progressing  to the elbows, knees, shoulders   and   the  hips  and   less  commonly  the  cervical   spine.   RA generally  follows  a  symmetrical   pattern,  meaning  that  if tne  knee  or hand  is involved,  the other one is also affected.

In addition, people  with RA may have fatigue, and a general  sense of not feeling   well   (malaise).   Other   features   include   lumps (rheumatoid nodules) under the skin in areas subject to pressure (e.g. back of elbows).

RA affects people  differently. For a few people, it lasts only a few months or a year or two and goes away without causing any noticeable damage. Other  people  have  mild or moderate forms of the disease,  with periods of worsening  symptoms,  called  flares,  and  periods  in which  they  feel better,   called   remissions,   and   may   result   in   gradually   progressive problems.

Still others  have  a severe  form of the disease  that is active  most of the time, lasts for many years or a lifetime, and leads to serious joint damage and disability. However, modern  treatment  can reduce  inflammation and joint damage  and improve  the long-term  outcome.

As shown  in the diagrams  above,  there  are important  differences  in the way  OA  and  RA affect  the  hands   and  wrists.  These differences   are covered  in detail in the hand  and wrist section.

Terminology

In order to communicate effectively with doctors  you will need  to learn how to describe  the body in medical  terms. In the following sections you will encounter some fairly detailed  anatomical descriptions of the joints which  contain  some  unfamiliar  and,  at first sight, seemingly frightening and difficult words.  Do not be daunted by these terms – they are not so difficult and,  once  mastered, you will be able to describe a joint with a degree  of accuracy and economy of words that is simply not achievable using “everyday” language.

Directional terms

A number  of directional terms  are  used  to  describe  how  the  body  is organised  and  how  various  structures  are  located   in  relation  to each other.

The     starting     point     for these descriptions is the anatomical  position.  In this position  the body  is upright and   facing   forward,   arms are outstretched with palms of the hands facing forwards and the thumbs  facing away from the body. Unlike a theatrical stage, where the audience is  looking  at  the actors  and  what  is right  to the  audience is  left  to  the actor, there is no ambiguity: right means  the body’s right side  and  left the body’s left side wherever  it is being viewed  from.

If a person  is lying down  on his face,  he  is in the  prone position  with  the  palms  of the hands  facing down  and thumbs  out.  Somebody lying on his back with the palms  of  the  hands   facing up and  thumbs  out is in the supine position.

The term superior means towards the upper portion of the body or limb; the term inferior means towards the lower portion of the body or limb. Also, a structure  may be described as superior  or inferior to another  structure.

In anatomical terminology  sometimes  a shortened version  of the word can  be incorporated into other  words.  So when  you come  to the knee you will find a suprapatellar bursa  above the patella  (knee cap) and  an infrapatella  bursa below  the patella.

Similarly the terms anterior and posterior  refer to structures  towards  the front and towards  the back respectively. Your knee cap is on the anterior aspect  of your leg, your shoulder  blade  is on the posterior  surface of the body. These terms are also used  to describe  position  in relation  to each other – for example,  the nose is anterior  to the ear.

The words to describe  relative positions  in the side-to-side  direction  are medial  and  lateral.  Medial  structures  are  close  to  an imaginary line down the middle of the body. Lateral structures are further away from the midline.

So when  changes  in the big toe joint occur  that cause  the bone  of the foot (metatarsal) to move which produces a bulge inwards or towards the other foot and the big toe to point outwards  or towards  the other toes on the  foot  (commonly   called  a  bunion),  it is described medically   as  a medial  displacement of the  metatarsal   and  a  lateral  deviation  of the phalanx  (toe). (The medical  name  for bunion  is hallux valgus).

This  is  a   classic   example   of  the   advantages  of  using   seemingly complicated anatomical language. It took 36 words to clumsily describe the foot deformity in everyday  language, but the anatomical description was unambiguous in just 12!

The  last  two  useful  terms  are  proximal  and  distal.  Structures  that  are proximal  are nearer  the point  of attachment, the centre  of the body,  or the point of reference. So an elbow is proximal to a wrist, a patch of skin on your thigh is proximal  to one  on your calf. Distal points are farthest from  the  point  of attachment, the  centre  of the  body  or  the  point  of reference. Your feet are distal to your knees.

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Summary

Superior	:	Toward the head
Inferior	:	Away from the head
Anterior	:	The front of the body or body part
Posterior	:	The back of the body or body part
Medial	:	Toward the midline that divides left and right
Lateral	:	To the side, away from the midline
Proximal	:	Closer to the torso
Distal	:	Farther away from the torso

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Movements

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Summary

Extension	:	Increasing the angle of the joint
Flexion	:	Decreasing the angle of a joint
Elecation	:	Moving to a superior position
Abduction	:	Away from the body
Adduction	:	Towards the body
Rotation	:	Turning about the long axis of a bone
Supination	:	Rotating forearm laterally
Pronation	:	Rotating forearm medially

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There are specific  anatomical terms used  to describe  the movement of limbs or joints.

Straightening,  or increasing  the angle of a joint is called extension, while bending   or  decreasing the  angle  or  making  it  smaller  is  flexion.  So extension  of the elbow  will straighten  the arm, and you will need  to flex your knee  to kneel  down.  (As an aide memoire remember extension  is extending the length of your arm.)

Moving a limb to a superior  position  is elevation.  So putting your hands above  your head  is elevating  them.

Abduction  refers to moving a limb away from the body or away from the midline.  In abduction of the  fingers  it means  spreading  them apart  – moving the other fingers away from the third or middle  finger or moving the other toes away from the second  toe.

Adduction  is moving  the  limb  in the  opposite  direction  – towards  the body  or  midline.   Adduction   of  the  digits  means   moving  the fingers towards  the third finger of the hand  or the toes towards  the second  toe. (As an  aide  memoire,  remember abducting someone  is taking  them away.)

Rotation  refers  to  turning  or  revolving  a  part  of the  body  around   its longitudinal axis, such as turning one’s head  to the side.

Supination  is rotating  the  forearm  laterally  to turn  the  thumb  out  and pronation is rotating the forearm medially to turn the thumb in. So if you hold you hand out in front of you with the back of your hand uppermost and thumb  pointing  inwards  and then turn you hand  over so the palm is uppermost and  the  thumb  is pointing  outwards  you  have  performed  a supination of your hand.

Introduction to the structure of the musculoskeletal system

The musculoskeletal system is composed of bones,  joints,  muscles  and other connective tissues.

Bone

Bones form the skeleton  which  gives support  for the body,  protects  vital structures  and  gives the mechanical basis  for movement. The bones  of the  head,  neck,  trunk  (ribs, vertebrae  and  sacrum)  make  up  the  axial skeleton. The limb bones  make up the appendicular skeleton.

Cartilage

Cartilage is a resilient semi-rigid material  that forms part of the skeleton where  movement occurs.  It may form the hinge of the joint itself. Alternatively,  it may  cover  the  ends  of the  bone  in joints  which  move freely (synovial joints).

Joints

Joints are where  two bones  meet.  Some joints have no movement, such as those  between the bones  of the skull, but movement is an important function  of many joints.

There are three basic types of joint:

• a fibrous joint – relatively immoveable. These joints are firmly held together  by a thin layer of strong connective tissue. There is virtually no movement between the bones.  Fibrous joints include  the sutures of the skull and the joint between teeth and their sockets.
• a cartilaginous joint – partly moveable. Cartilaginous joints are joints where   the  articular   surfaces  of  the  bones   forming  the joints  are attached to each other by means of fibrocartilaginous discs which are soft and  able  to change  shape  (plastic  or deformable)  or ligaments which  allow  only a limited  degree  of movement. Examples are the cartilaginous joints between the vertebrae  of the spine  (the “discs” which  so  often  become “slipped”), the  cartilage  in  the  symphysis which  binds the pubic  bones together  at the front of the pelvic girdle and the cartilage  in the joint between the sacrum  and the hip bone.
• a synovial  joint  – freely moveable. Synovial  joints  are  where  one surface   slides   freely  over   another   and   movement  is positively encouraged – for this is the role of the synovial joint.

Periarticular structures

There  are  other  structures   around   the  joint.  Joints  are  stabilised   by ligaments,  which  are  tough  bands  of white  connective tissue that  link two bones  together  at a joint. Ligaments are flexible but not elastic; they strengthen  the joint and limit its movements to certain directions.

Tendons attach  muscles  to bones.  The junction  of the tendon  and  bone at the point  of attachment is called  the enthesis.  Tendons  are made  of parallel  bundles  of collagen.  Like ligaments,  tendons  are  flexible  and inelastic  and assist in concentrating the pull of a muscle  on a small area of bone.  The flexor tendons  in the  ankle  and  wrist are  surrounded by synovial membranes and fluid.

Movement   of a  joint  is produced by  contraction of muscles  and  the movement is transmitted  via the tendons  to the bones.

Bursae (singular bursa) are small sacs of fibrous tissue filled with synovial fluid.  Bursae  occur  where  parts  move  over  one  another   and help  to reduce   friction  and  cushion   joints.  They  are  normally  formed  round joints and in places  where  ligaments  and tendons  pass over bones.

If the bones  of a joint become displaced from their normal  position  such that there is a complete loss of contact  of the joint surfaces,  the joint is said  to be  dislocated. Luxation also  means  dislocation but  this term is rarely used.

Subluxation refers to a partial dislocation of a joint, where  the bones  are still in contact  but are not properly  aligned.

Structure of a synovial joint

The ends  of the bones  forming a synovial  joint are covered  with a thin layer  of cartilage  and  surrounded by a capsule  which  is lined with  a synovial  membrane   that  secretes  synovial  fluid  to  lubricate   the  joint. There  are  also  several  bursae  which  are  fibrous sacs  also  lined  with  a synovial  membrane   and  containing small  amounts   of  synovial  fluid. These sacs occur  where  parts move  over each  other,  to reduce  friction. They occur  around  joints  and  in places  where  tendons  and  ligaments pass over bones.