The Knee

Introduction

The  knee   is  the   largest   and   most   complicated  joint   in  the   body. It depends for  stability  on  internal  soft  tissue  structures  such  as  the cruciate   ligaments   and   on  external   soft  tissues  of  the  capsule   and capsular   ligaments.  This joint  is  the  most  vulnerable to  injury,  loose bodies  and several arthritic conditions.  It is very important  for mobility.

Anatomy of the the knee

The knee  articulates  (or joins) the bones  of the leg; the femur (or thigh bone) is superior  to the knee, the fibula (or small bone  of the lower leg) is inferior and lateral to the knee and the tibia (or large bone of the lower leg) is inferior and medial  to the knee. The patella or kneecap is located over the anterior  section  of the knee.

K-1 The knee-anterior view K-2 The knee-posterior view K-3 The knee-joint structure

The knee  contains  several  bursae, the most significant  of which  are the prepatellar  bursa located  over the patella,  the infrapatella bursa located below  the  patella,  and  the  suprapatella pouch  located  anteriorly  and slightly superior  to the patella.  The quadricep muscles are anterior  and superior  to the knee joint.

The knee is stabilised by the anterior and posterior  cruciate ligaments at the back  of the knee  and  the medial  and  lateral  collateral  ligaments  at the  side  of  the  knee.  (Cruciate  means  like  a  “cross”  and  these  two ligaments  are  arranged  in a cross  formation  to provide  stability  to the knee.) The anterior  cruciate  ligament  prevents  a posterior  displacement of the femur on the tibia, and the posterior cruciate  ligament prevents an anterior  displacement of the femur on the tibia.

K-4 The knee-cruciate ligaments

The  collateral   ligaments   prevent   the  knee   from  rotating  when   it  is extended; they extend  down  the medial  and lateral aspects  of the knee. The patella is secured  by the patellar ligament and muscles,  which allow the kneecap some movement. The popliteal  fossa is the space formed by the soft tissues at the posterior  aspect  of the knee.

Problems of the knee

Problems of the knee may present  as:

  • Pain – which  may  be  constant   or  intermittent,   or  precipitated by activities such as sport or walking up or downhill.
  • Swelling.
  • Stiffness or limited movement.
  • A hot, red and swollen joint.
  • Crepitation.
  • Locking.
  • Giving way.

There  are  several  common causes  of knee  problems.  In young  adults trauma and sports injuries are the most common causes. In older people, osteoarthritis  is the most common cause.

Articular causes

Osteoarthritis Patellofemoral joint

Knee joint

Inflammatory  arthritides Rheumatoid  arthritis

Spondyloarthropathy

Crystal arthritis

Infection

Mechanical Meniscus problems

Periarticular problems

Bursitis Prepatellar  bursitis, Anserine bursitis
Tendinitus Tibial tendinitus, Adductor  insertion tendinitus
Popliteal cyst Also known  as Baker’s cyst
Ligament problems Cruciate ligament, Collateral  ligament

Pain  and  crepitation suggests  roughening of the  patellar  undersurface that articulates  with the femur.

Note: crepitation alone,  without  pain,  is not significant.

Giving a history of knee problems

Invite the doctor to carry out a consultation by first asking you about your history  related  to the  experience you  have  of your condition. This will then be followed  by the physical  examination.

The doctor  should  first ask you ‘What is the problem?’ and  you should give a short response  describing  your symptoms  and their effect on your quality of life.

Develop  a script based  on your own experience. You may still have the symptoms  or you  may  be  describing  an  episode  you  have  had  as if it were still present.

Describe  as fully as you  can  your  own  symptoms,  including  where  in and around  the knee you feel/felt pain or discomfort. Say if you have any stiffness,  swelling  or  other  symptoms.   Mention   how  the  problem   is having/had an impact  on your daily life, your work or your sleep.

Remember  to describe  how  your condition affects/affected  your quality of life. Consider  self care  (e.g. ability  to wash,  dress,  toilet  and  feed), domestic   care   (e.g.   ability   to   cook,   clean,   launder,   shop),   work (e.g. ability to stand, sit, type), leisure (e.g. ability to play sports, walk, go out for meals). Explain about  the way it limits/limited  your activities and restricts/restricted  your participation in normal  life.

Do  not  tell  him  everything  spontaneously  –  just  the  important   part. He  will  then  need  to  ask  further  questions  to  fully characterise your problem.  Develop  a set of answers  with  your  trainer  to the  following points. Prompt them if they omit important  questions.

Pain is usually present  and questions  should  establish:

  • How the pain started and developed.
  • The nature of the pain.
  • The exact distribution of the pain.
  • Whether the pain has increased or decreased over time.
  • Whether it affects sleep.
  • Whether anything  exacerbates or relieves the pain. Stiffness may be a symptom  and questions  should  establish:
  • If you are stiff at all?
  • When it is worse?
  • What improves it?

Swelling may be a symptom  and questions  should  establish:

  • If you have noticed any swelling and where.
  • If it is always present.
  • If it is painful or tender.
  • If it is increasing.

They need  to ask about  the  pattern  of all the  symptoms  – where  they started and if they have spread  anywhere.

You may prompt  the doctor  (if you have not already  told them) to make sure that they include  the following information:

  • Your age, occupation and hobbies.
  • Your general health.
  • Your past medical history.
  • Whether you have injured  or strained  your knee.
  • Whether the knee locks or gives way.
  • Whether there is any impairment of function  and how this impacts on your daily activities and quality of life.
  • Knee problems typically cause  difficulty in walking, walking up or down  slopes, rising from a seated  position  or kneeling  down.
  • Whether you have had previous  treatment  and if so whether  it was successful.

The  effect  of any  problem   depends on  your  personal   circumstances. The doctor  needs  to know  about  what  you need  to do in the home,  at work, your leisure interests and your expectations.

You may  have  symptoms  affecting  other  parts  of your  musculoskeletal system.  You may prompt the doctor to ensure he has asked whether  you have  any  other  problems  affecting  your  muscles,  joints,  neck  or back.

You may go into further details about  how your problem  affects your life and  the  treatment  you  have  received  at  the  end  of the  session  when discussing  the findings.

Example of a Script

You should  develop  something  like this, based  on your own story. First you need  to ask me:

What is your problem?

“I have  worsening  pain  in my knee  when  I walk, and  now  even  when I am sitting in a chair.  It has given way a few times, and is stopping  me going for a walk and I am getting unfit.”

You should then respond  to questions,  guiding and prompting  the doctor through  the information  as listed above.

Knee Examination Script

Describe   the  examination  to  the  doctor   using  the  anatomical and directional  terms  you  have  learnt.  You  can  use  your  knowledge  of anatomy   best  when   the  doctor   is  feeling  the  joint  and  periarticular structures.

“I  would  now  like  to  invite  you  to  find out  a little  bit more  about my problems,  by role play, using me as your patient and examining me.

Look

Standing

With   the   patient   standing,   look   from  the   front  and   back   for  any malalignment.

Valgus angulation (knock-knees)  (most common in RA)

Varus angulation (bow-legs) (most common in OA)

K-5 Valgus and varus angulation

Look at the front of the thigh for any wasting of the quadricep muscles with loss of muscle  bulk.

Also while  the patient  is standing  with both  knees  fully extended, look behind   the  knee  for  any  fluid  accumulation. This  could   indicate   a popliteal   (Bakers)  cyst,   a   fluid   filled  protrusion   of  the   synovial membrane into the popliteal  fossa in a knee affected by OA. If there is a swelling,  palpate  whilst the patient  is still standing  to confirm  that it is fluid. A popliteal  cyst is best palpated when the knee is fully extended as otherwise  it can remain  undetected in the joint space  when  the knee  is flexed.

Lying down

Now  with the patient  lying, look for redness  and  swelling  of the joint. You may  see  swelling  on  either  side  of the  patella  (loss of the  normal hollows  around  the  patella)  and  around  the  suprapatellar pouch  (the horseshoe-shaped  area  above   the  patella   which   is  part  of  the  joint space).

What do you see?

Feel

Lying down

With  the  patient  lying and  the  leg outstretched feel for heat  generally, palpate  for swelling  and  tenderness of the  knee  joint  and  around  all bursae  including  the suprapatellar pouch  which  is additionally checked for synovial thickening  and effusions.

Start above the superior border of the patella (well above the pouch) and feel the soft tissues between your thumb  and  fingers. Move your hand distally in progressive steps, trying to identify the pouch.   Swelling above and adjacent to the patella suggests synovial thickening  or effusion in the knee joint.

If you suspect  a small amount  of fluid around  the knee test by:

The  bulge  sign  (for  minor  effusions).  With  the  knee  closest  to  you extended, squeeze the area  above  the knee,  applying  firm pressure  on the  suprapatellar pouch,   and  pushing  downward  toward  the  patella. With the other hand,  stroke towards  the patella  on the medial  aspect  of the  knee  two  to  three  times,  displacing  or  “milking”  fluid  under  the patella  and applying firm pressure to force fluid towards the lateral area. Maintaining  the  grip on  the  superior  aspect  of the  knee,  remove  your hand from the medial aspect of the knee and quickly press firmly against the lateral margin of the patella. A fluid wave or bulge on the medial side between the patella  and femur confirms an effusion.

K-6 The bulge sign

Tapping the patella (for large effusions). Push firmly down  on the suprapatellar pouch  with  the  palm  of one  hand  while  squeezing the lateral side of the knee with the thumb and fingers. With the other hand, encircle  the inferior aspect of the knee, pressing toward the patellar. With your dominant index  finger, firmly “ballotte” or quickly  tap the patella against  the femur to see if it bounces, which  it will do if there  is fluid trapped  beneath it. Sometimes  a clicking sound is heard. Watch for fluid returning  to the suprapatella pouch  as the hand  is removed.

K-7 Patellar tap

Feel for tenderness or a popliteal  cyst by gently putting the fingers of both hands  into the popliteal  fossa and gradually  exerting more force.

Feel  the  margin  of the  joint.  With  the  knee  semiflexed  at  about  90°, palpate  along the sides of the patella  and then the rim of the knee. Note where  it is painful  as this may be a sign of meniscal  injury.   Note  any irregular  bony ridges along the joint margins,  which  may be felt in OA. Then feel specifically  for the medial  and lateral collateral  ligaments  and their insertions.

What do you feel?

Move

Lying down.

Passive Range of Motion (ROM)

Ask the patient  to lie supine.  Move the knee by holding  the leg midcalf with one hand  and holding  the patella  with the other hand.

Flexion – Bend the knee, bringing heel to buttocks.

Extension – Straighten the leg.

K-8 Flexion, extension

Movement against resistance

Test the quadriceps power  with the patient  lying with the leg extended. Place one hand proximal to the patella and feel the muscle and assess its strength when  you ask them to lift the leg against your pressure.

Wasting   of  the   quadriceps  can   also   be   assessed   by  measure   the quadriceps by measuring  the circumference of the thigh will also point to unilateral  wasting.  Measure  3” or 7.5 cm above  the superior  pole  of the patella and mark. Measure the circumference of the quads bilaterally. This measurement should  be used over time to track wasting or increase in muscle  bulk.

What have you found?

Stress

Ligament Stability Tests

Assessing ligament  stability is important.  The following are examples  of tests to determine stability:

Cruciate Ligament Stability Test – Anterior drawer sign

With  the  patient  supine,  hips  and  knees  flexed  and  feet  flat  on  the examining  table  (if possible)  stabilize  the distal portion  of the leg with one  hand   and  place   the  other  hand   behind   the  knee.   Pull  on  the proximal posterior aspect of the tibia, drawing the tibia forward. Observe if the tibia slides forward (like a drawer) from under the femur. Compare the degree  of forward  movement with that of the opposite  knee.  A few degrees   of  forward  movement  are  normal  if present  equally  on  the opposite  side.

A forward  motion  showing  the contours  of the upper  tibia is a positive anterior drawer sign which suggests involvement of the anterior cruciate ligament.

K-9 Anterior drawer sign

Collateral Ligament Stability Test

Ask the patient  to extend  the knee.  Stabilise the joint margin  with one hand  under  the knee,  allowing  the knees  to relax and  flex very slightly into your hand. The other hand should hold the distal aspect of the lower leg  (just  above  the  ankle),  raise  the  foot  slightly  and  rock  the  distal portion  of the  leg medially  and  laterally.  There  should  be  little  or no movement of the proximal  aspects  of the tibia and fibula.

K-10 Collateral ligament test

Listen

During all tests listen for signs of crepitus.

Special tests

No additional test for the knee are needed routinely.

“We  have  now  come  to the end  of this mock  consultation. You should have    learned    quite    a    bit    about    my    condition   from    taking my  history  and  examining  my  joints,  however,   I  would  be  happy  to provide  you with a bit more  detail  about  the progress  of my condition and how it affects my life, if you would  find this useful.”

[Please give a brief description  of your condition:

  • When  and how  it started.
  • Physical and psychological  affects on you.
  • Treatments  offered.
  • How  your condition progressed.
  • How this affected  your life: Home, education, work,  leisure, ability to travel, relationships etc.]

“Does  anyone  have any further questions?”

“Thank  you  again  for attending   this  session.  I  hope  you  have  found it useful.”