Keywords: Subjective Ax, objective Ax, Passive ROM, Knee assessment, Active ROM, Knee pain, Strength Tests, Special tests, Differential Diagnosis, Red flags.
Physiotherapy Knee Assessment (Ax)
A good knee assessment is necessary to accurately diagnose the source of pain. The best way to learn good assessment skills is through hands on practice and watching experts. Try to spend a day with a consultant or extended scope practitioner to see how they perform an assessment. Visit the student room to find preparation notes for work experience days.
- HPC –Trauma/insidious onset
- Mechanism of injury
- Is pain in a dermatomal region?(Pain in the knee can be referred from the back)
- Is there hip pain? (Knee pain can be referred from the hip)
- Did the patient hear a pop/click at time of injury?
- Does the knee give way? ( instability/rupture of ligaments)
- Did the knee swell? How quickly? Where is the swelling? (Intra articular/ extra articular; immediate swelling usually indicates trauma within the knee such as ligament damage)
- Was there bruising? (Immediate bruising indicates significant trauma
- Cough/sneeze cause pain?
- Does the patient experiencing locking (may indicate a bucket handle meniscal tear).
- Age – The following conditions are not exclusive to these age groups but a higher prevalence is noted in these populations (elderly – OA?, young – osgoods schlatters, middle aged- meniscal).
- Type of shoes ( wear patterns/age of shoes/proper design)
What does this tell you?
Mechanism Of Injury
ACL strain/ tear
- H/o valgus or hyperextension force to knee if contact injury.
- Sharp change in direction in non contact injury.
- H/o audible ‘pop’
- H/o a quick stop, landing with knee fully extended
- Severe effusion within 4-6 hours.
- H/o increased training (ie running distance; intensity/distance/frequency)
- C/o lateral knee pain
MCL strain/ Tear
- Valgus force to knee in contact/non contact injury.
- C/o medial knee pain.
- Varus force to knee in contact/non contact injury.
- C/o lateral knee pain.
Chronic patella subluxation
- C/o giving way/instability/pain.
- C/o catching of the patella
- Localised pain on the medial aspect of patella.
- Restricted function/ sports due to apprehension of instability.
- H/o rotation or valgus force to knee.
- Patient may describe seeing dislocation that ‘popped back’ spontaneously or needed reduction by medical staff.
- Increased prevalence in females.
- C/o medial patella shift of knee.
Patella tendinopathy (Jumper’s knee)
These are the special questions which may indicate that something more sinister may be going on. Patients should be referred immediately back to the GP with your concerns noted. Ask a seniors advice on the severity of these symptoms and whether and A and E referral is more appropriate. Mechanism of Injury is important here, what force was exerted through the leg? Was it enough for a tibia/femur fracture? Loss of pulses in the foot may indicate vascular compromise due to a fracture. Fractures can lead to fatty embolisms therefore warrant immediate A and E referral.
- Bilateral pins and needles or numbness in the LL.
- Problems with bowel and bladder function where the patient is unable to feel themselves going to the toilet.
- Paraesthesia in the groin region.
- Loss of pulses in the LL (Vascular compromise).
- Obvious deformity.
The objective examination gives you quantifiable measures to rule out what structures are involved and to reassess after treatment to determine improvement/deterioration. For example documenting that a lady has 90 degrees knee flexion will allow you to re-assess at her next treatment session and monitor improvement or deterioration. This should help guide you on whether a treatment has been effective and can help confirm a diagnosis.
- AROM – Knee flexion(135-145degrees), Knee extension(0 degrees).
- Reflexes (Patella; L3-4, Ankle Jerk; S1, Babinski, Clonus).
- Sensation (Dermatomes)
- Palpation (MCL,LCL,PCL,ACL, joint lines)
- PA Spinous processes (To r/o back pathology)
- PA Tranverse processes (To r/o back pathology)
- Strength (Quads/Hamstrings/Gluts/Hip external rotators)
What does this tell you?
- Try to establish the structure involved. Pain at the end of the day after work may suggest structures that are stressed as the day goes on. Pain in morning could be due to inflammation (ie OA) however if the pain is easier in the morning this could be due to reduced swelling due to rest and elevation overnight .
- Poor Quality of movement – Is the muscle jerking or shaky which could indicate pain inhibition or fatigue.
- Throughout movements where does the patent feel their pain? Is the patient weak in a specific range or does the pain increase with soft tissue impingement ie end of range flexion?
- Does the patient present with significant guarding and unwillingness to move.
- Pins and needles of paraesthesia (numbness) in the lower limb? This normally suggests a neural element which maybe coming from the lumbar spine or compression of the nerve somewhere along its course.
- If you press on a structure and this reproduces the patients symptoms this may suggest referred pain is occurring.
- Lachmans (95% sensitivity)
- Valgus and varus stress tests (0 and 30 degrees)
- Anterior/posterior drawer (Sensitivity =91%, Specificity =100%)
- Flex-rot drawer, ER recurvatum
- Sag sign (compromised PCL)
- McMurrays (Sensitivity = 10-66%; Specificity = 57-89%)
- Bounce home,
- Joint line tenderness
- Apley’s Grinding
- Grind (Clarkes sign)
- Swelling/effusion, tenderness over plica with palpation.