PDFDiagnostic tests and functional assessment are the two ways of identifying what might be wrong in a knee and what to do about it.
It is useful to remember that the nerves which convey pain signals inside the knee are not arranged so as to relate strictly to specific structures in a recognizable way. Your perception of where your pain is will not necessarily be an accurate diagnostic guide as to what structure(s) might have been damaged or how much damage has been done..
One cannot judge from touching the surface whether deeper-lying internal structures like a meniscus (soft cartilage) or a cruciate ligament have been damaged in an injury. Nor does the degree or absence of pain necessarily relate to the severity of the injury. A major injury like a cruciate ligament tear can happen with surprisingly little pain, as there are few pain receptor nerves in the centre of the knee. On the other hand, the more superficial tissues, such as the medial and lateral ligaments on the inner and outer sides of the knee, can be felt through the skin, and when they are damaged they hurt and become tender to the touch.
If we need to know for certain whether internal structures are torn or crushed, then it is best for the patient to be referred to an orthopaedic consultant to have diagnostic tests done, such as Magnetic Resonance Imaging (MRI) or Computerized Tomography (CT) scans. If there are indications of disease or infection, the patient may be referred to an appropriate medical specialist for blood tests. Once the technical diagnosis is established, accurate surgical or medical treatment can be offered.
The functional assessment aims to establish what limitations a problem is causing, as a basis for a treatment programme consisting of rehabilitation exercises and self-help measures. It does not seek to establish a precise diagnosis of what tissues are damaged, although it is often possible to be fairly accurate on this point, if the assessment has been done thoroughly. All knee problems need a functional recovery programme, to avoid recurrences, long-term repercussions or problems in related joints, especially the hip.
The functional assessment
My functional assessment for knee problems normally consists of three parts:
1. Your description of your problem, and your answers to my questions
2. Physical examination
3. Functional tests
The order of the assessment may vary. For instance, if your problem is not acutely painful, functional tests with you in the standing position may be done first. But if you cannot stand up because of your knee pain, then you would be placed on the couch straight away. The physical examination might happen simultaneously as you tell the story of what happened, and the functional tests would be limited.
At no point should the assessment cause you significant pain. In my opinion, at least, there is no need to put the patient through pain in order to identify what a problem is or why it is happening.
The assessment reveals the nature of your problem and the amount of physical limitation it is causing you. It also provides objective points for comparison as your treatment progresses, or if you come back much later with another injury or problem.
The assessment process doesn’t take as long to do as it does to read, unless the problem is very complicated. The completed assessment provides the basis for advising you on your possible self-help and treatment options.
How to prepare for assessment and treatment
* Bring written notes of what your problem is, so you can answer your practitioner’s questions accurately and succinctly.
* Write down any questions you know you will want to ask.
* Wear suitable comfortable clothing, which will allow your legs to be seen. Shorts are best for males or females, but modest underwear will do.
* If you have any skin infections on your feet, such as verrucas, make sure they are covered.
1. My questions
For a traumatic injury
If you have had an accident, I ask:
* What happened and when?
* Did your knee twist, bend or shear in the accident?
* Did you feel any abnormal movement in the joint?
* Did you hear or feel a snap, crack or tear?
* Was your weight on the leg at the time?
* Did the knee get hit or knocked?
* Did you have pain?
* If so, was it immediate or later? How bad was it?
* Did the knee swell up?
* If so, where? Was it straight away, a few hours later, or the next day?
* Could you put your weight on the injured leg immediately after the accident?
* Could you put your weight on it the next day?
* Did the knee lock? If so, did you manage to free it, did someone manipulate it to free it, or did it remain locked?
* Is the knee still swollen?
* If so, is it the same kind of swelling as at first, or has it changed?
* Is any part of the knee tender or sore to touch?
* Can you move the knee fully, or is it stiff or blocked?
* Did you hurt any other parts of the body in the accident?
* Have you had any cramp in any part of the leg?
For an attritional injury or painful condition
If your knee problem came on gradually, with or without an obvious cause, I ask:
* How did the problem start: did the symptoms come on suddenly or gradually?
* When did it start?
* What were you doing at the time? Was it anything unusual?
* Had you been doing anything unusual immediately beforehand or the previous day?
* Had you eaten or drunk anything unusual within the previous period before the problem started?
* Have you had the same or a similar problem before?
* What were the symptoms at the start?
* Are they the same now?
* Does the knee lock? If it does, can you free it?
* Does the knee feel unstable or give way? If so in what circumstances?
* Does the knee feel stiff?
* Is there any localized tenderness?
* If there is pain, is it constant, or does it come and go?
* Does any particular movement cause pain?
* Do you have pain at night?
* Is there pain when you are active?
* Is there pain when you are at rest?
* Is there pain when you put weight on the leg?
* Is there pain when you move the leg without your weight on it?
* Do you have pain standing or sitting still?
* Do you have pain walking on flat surfaces or uneven ground?
* Do you have pain going up and/or down stairs?
* Does the knee ever feel hot?
* Does the skin of the knee or leg ever change colour?
General questions
In all cases, I ask:
* What are your normal activities?
* Is the knee limiting you, and if so how?
* Have you had previous injuries to this knee?
* Have you had any previous injury to this leg?
* Do you tend to get cramp in the calf or any other part of the body, especially at night?
* Have you had any previous injury to the other leg, or any other part of the body?
* Have you ever had any significant illnesses (eg glandular fever, heart problems)
* Is there any history of hereditary diseases in your family?
* Do you take any medicines of any kind for any reason?
* Do you have any allergies that you know of?
* Do you have any particular stresses?
* What is your normal diet?
* How regular is your fluid intake? How much water have you drunk today?
If the patient is female, I might ask, according to her age:
* Is your menstrual cycle regular and normal?
* Have you had any children?
* Are you or could you possibly be pregnant now?
* Do you take the contraceptive pill?
* Do you take any form of hormone replacement therapy?
2. Physical examination
As you lie on your back with your head supported (with a rolled towel under your injured knee if it is painful when straight):
* I look at your knees to compare them for size, shape and colour. I also compare your leg muscle groups and check the alignment of your legs.
* I feel your injured knee gently, checking for swelling, warmth and localized tenderness.
* I ask you to straighten both knees without force, to tighten and relax the kneecaps, while I watch and feel the vastus medialis obliquus muscle to see how well it works on each leg.
* I ask you to straighten and relax the injured knee gently, to check whether you can activate and control the vastus medialis obliquus muscle.
* I straighten the knee fully, and ask you to tighten the thigh muscles to hold the position. This shows if the vastus medialis obliquus muscle is weak.
* I ask you to bend and straighten the injured knee as far as you can.
* I gently bend your knee passively to see whether it has more movement than when you bend it actively.
* I move your hip, first on the uninjured side, then the injured, to check whether there is limitation in either hip, stiffness in the muscles connecting the hip to the knee, or the hip is contributing to your symptoms.
* I ask you to bend your knees, lift your hips up so you balance on your shoulders and feet, straighten one knee, then bend it to replace the foot on the couch, straighten the other knee and replace the foot, then lower the hips. This shows whether there is weakness or imbalance in the muscles at the back of the thigh and hip on either leg.
As you lie on your stomach (with a folded towel under your thigh if it is painful for the injured knee to rest on the couch):
* I look at and feel the backs of both knees for comparison.
* I look at and feel the back of the injured knee, checking for abnormal temperature, subtle swelling and localized tender areas.
* I ask you to bend both knees, to compare the range of movement.
* I bend your uninjured knee passively, then the injured one, to check the freedom of the joint, and how tight the front-thigh muscles are.
* I ask you to straighten your knee and lift the leg up backwards, keeping the knee locked straight, first on the uninjured leg, then the injured one.
3. Functional tests in the standing position
(You stand close to a support in case of need)
* I look at your legs, as you stand straight, checking for obvious signs of injury in your knee, comparing your two knees and the muscle balance on either leg, and looking at the alignment of your legs.
* I check your posture, noting whether you stand evenly on both legs, and whether you tend to drop one shoulder or hold your head to one side.
* I ask you to straighten your knee by gently tightening and relaxing your kneecaps. I assess whether you can tighten the thigh muscles to draw the kneecap up, and whether you can relax the muscles so that the kneecap is free.
* I ask you to balance on your uninjured leg, then on the injured one. This shows how well you can take weight through the leg, and whether your balance mechanisms are impaired.
* I ask you to stand on your uninjured leg and lift the other leg straight out sideways 3 or 4 times without putting the foot to the floor. Then you do the same exercise standing on the injured leg. This shows whether there is weakness in the hip muscles on either side, and whether the hip on the injured leg might be contributing to your symptoms.
* I ask you to go up and down on your toes 5 or 6 times, standing on both legs and keeping your knees straight. I check whether you tend to throw your weight on to the uninjured leg.
* I ask you to stand on the uninjured leg and go up and down on your toes 5 or 6 times, keeping the knee locked straight. Then you do the same on the injured leg. I check whether you can do the movement keeping the knee straight: if not, there is weakness in the soleus muscle in the calf which both a postural muscle and part of the leg’s shock absorption mechanism during walking, running or jumping.
What I don’t do
I never do tests which involve forcefully stressing the knee joint to check for laxity and possible internal damage. Such tests are not necessarily accurate, and they can cause pain. Making the patient’s pain worse, even temporarily, restricts the rest of the functional assessment. The patient’s description of the injury, pain and other symptoms, combined with the physical examination, furnish enough clues as to whether there is significant internal damage or a medical condition rather than a musculoskeletal problem. Even if such problems are not obvious at first, they will become so as rehabilitation progresses, at which point the patient can be advised to refer for diagnostic tests and specialist medical or surgical treatment.
