TIS
Chapter 8
Knee Evaluation and Differential Diagnosis
- Introduction
Principles of Exam:
- communication issues
- contralateral limb examined first
- know what's normal
- well-thought out, orderly sequence
- purpose is to:
- establish clinical diagnosis
- establish physical therapy goals
- determine contraindications
- identify any potential problems interfering with therapy
- confirm patient goals
- let patient know what's expected
- Subjective exam
- 80% of pertinent information collected here
- communication essential
- establish mechanism of injury
- previous history
- patient goals and motivation
- identify potential problems
- establish rapport
HISTORY:
Mechanism of injury:
- chronic vs. acute
- onset, number of episodes, relationship with other variables
- why now and not before?
- why this knee and not the other?
- why this person/athlete and not someone else?
- contact vs. noncontact
- blow, fall; speed, distance, padding, object size, shape
- acceleration, deceleration, take-off, landing, pivot, plant & twist, hills, stairs, etc.
- position of the knee
- position of the body
Swelling:
- how much?
- when? early vs. late (acute); related to what? (chronic)
to within 24 hrs. of indication of patello-femoral injury
Pain:
- how much?
- where?
- what exacerbates?
- what relieves?
- how long does it last?
Other:
- locking (genuine vs. perceived)
- popping (associated with pain?)
- giving way (primary vs. secondary)
- catching
- slipping
Correlations: mechanism and diagnosis (acute injuries):
Rotation on a fixed foot:
- patellar subluxation/dislocation
- meniscus tear
- ACL tear
- tibial spine avulsion fracture (adolescent)
- collateral ligament tear
- osteochondral lesion
Valgus stress:
- medial collateral ligament ± ACL
- growth plate fracture
- medial meniscus tear ± ACL
- patellar subluxation/dislocation
Varus stress:
- lateral collateral ligament ± ACL
- growth plate fracture
- posterolateral complex
- lateral meniscus tear
Hyperextension:
- ACL ± meniscus
- tibial spine avulsion fracture (adolescent)
- ACL ± posterolateral corner
Hyperflexion:
Cutting/deceleration:
- ACL ± meniscus, collateral
Other:
- Direct blow on flexed knee: PCL
Correlations: swelling and diagnosis:
- immediate, tense hemarthrosis: ACL or patellar dislocation
- late, synovial swelling: meniscus
- chronic, trace to 1+ effusion: meniscus tear or DJD
Correlations: pain and diagnosis (acute iniuries):
- posterior: ACL, meniscus
- anterior: patellar subluxation/dislocation
- medial or lateral: respective collateral lig or meniscus
- joint line: meniscus
- adductor tubercle, proximal lateral patella: patellar sublux/dislocation
- severe: may be fracture/tumor
- pain can be anywhere with a blow, fall
Correlations: pain and diagnosis (chronic iniuries)
- anterior: patellar problems, fat pad, Osgood-Schlatter's, chronic PCL deficient, plica, DJD
- medial: chronic medial meniscus tear, DJD, chronic PCL deficient, pes anserine tendinitis, osteochondral lesion
- lateral: chronic lateral meniscus tear, DJD, chronic ACL deficient, discoid meniscus, hamstring tendinitis, ITBS, osteochondral lesion
- posterior: hamstring tendinitis, chronic meniscus tear, insertional gastroc tendinitis, popliteus tendinitis, chronic ACL deficient
- diffuse: RSD, slipped capital femoral epiphysis, tumor, other pathological diseases
Other:
- pop: ACL, meniscus
- clunk: meniscus
- catch: meniscus, patellofemoral, plica
- locking: flexion (meniscus), extension (patellofemoral)
- giving way: ACL, patellofemoral pain, pain for any reason
- Observation - in general
- movement, including gait
- guarding
- resting position
- ecchymosis, swelling, obvious deformity
- Anterior - standing
- hip, knee levels
- varus, valgus
- anteversion, retroversion
- patellar position
- tibial torsion
- pronation, foot alignment
- muscular development, atrophy
- Lateral - standing
- Posterior - standing
- muscular development, atrophy
- fibular head levels
- popliteal crease levels
- calcaneal position
- pronation, rearfoot, forefoot positions
- Sitting
- patellar position, motion
- knee mobility (resting position)
- femur, tibial lengths
- STTT
- active movements - flex, ext, tibial rotation, ankle, hip motions
- passive movements - flex, ext, tibial rotation, ankle, hip motions
- resistive movements - flex, ext, tibial rotation, ankle, hip motions
- have patient reproduce painful motion
- Special tests:
Ligamentous laxity (single plane):
- valgus 0 & 30 degrees: PCL/MCL
- varus 0 & 30 degrees: PCL/LCL
- Lachman's: ACL
- Anterior drawer: ACL
- Posterior drawer: PCL
- Posterior sag: PCL
Ligamentous laxity (combination):
- pivot shift: ACL
- Losee: ACL
- posteromedial drawer sign: posteromedial capsule complex
- posterolateral drawer test: arcuate lig complex
- reverse pivot shift: arcuate lig complex
- external rotation recurvatum: arcuate lig complex
Meniscus injury:
- McMurray's
- Apley's
- Bounce home
Plica tests:
Swelling tests:
- patellar ballotment test
- fluctuation test
Other:
- patellar apprehension
- Q angle
- leg length
- Noble compression test (ITB)
- McConnell's tests
- Waldron's (palpation while squatting for PF pain)
- Accessory motion
- patella: 4 directions
- tibio-fibular
- Palpation
- tibial tubercle
- pes anserine insertion
- patella: distal pole, medial, lateral facets
- patellar tendon
- fat pad
- plica
- quadriceps tendon
- medial joint line
- pes anserine tendon
- MCL
- medial femoral condyle
- lateral joint line
- lateral femoral condyle
- iliotibial band
- fibular head
- biceps feinoris tendon
- LCL
- popliteal fossa
- Radiography/medical tests
Radiographs:
- standing AP both knees
- lateral at 30/45 degrees
- notch view (tunnel)
- skyline (infrapatellar) both knees
- stress films in adolescents
Correlation of radiographs with diagnosis:
- lateral capsular fracture: ACL
- tibial spine avulsions: ACL
- stress films: MCL, LCL
- fabella: normal finding
Radiographs & DJD (Fairbanks changes):
- osteophyte ridging & flattening of MFC
- joint space narrowing
- subchondral sclerosis
- squaring of the tibial plateau
Ahlback's DJD staging:
- joint space narrowing
- obliteration of joint space
- minor bone attrition
- major bone attrition
- major bone attrition, often with subluxation and secondary arthrosis of opposite compartment
Arthrogram:
- inject air, followed by dye
- serial radiographs while flexing and rotating knee
- looking for menisoal tear primarily, cruciate secondarily
- invasive, painful, radiography
- accuracy ~ 90% medial, ~ 50% lateral
Magnetic Resonance Imaging (MRI):
- no radiation
- problems with claustrophobia
- assess menisci, ligaments, joint surfaces, fluid, soft tissues
- T1 & T2 weighted: inherent properties of the tissue that relate to the liquidity and chemical and molecular composition
- T1: has a short time of repetition (TR) and short time to echo (TE); subcutaneous fat and bone marrow have brightest signal (white), hyaline cartilage is intermediate (gray), and muscle is less (dark gray to black)
- T2: long TR and long TE; effusions have the brightest signal, followed in decreasing order by subcutaneous fat, bone marrow and muscle; ligaments, tendons and cortical bone are low in signal intensity
- acute hemarthrosis generally shows intermediate signal on T1's and bright signal on T2's
- generally obtain T1 and T2-weighted images in coronal and sagittal planes
- portable scanners have lower magnet and images are not as good as those from a permanent scanner
- accuracy for meniscus tears = 93%
- PCL easily viewed in the sagittal plane
- AOL less so, but best seen in the sagittal plane; discontinuity plus increased signal on T2's suggestive of tear; accuracy 95%; now studying in plane of ACL
- LCL, MCL best seen on sagittal views; T2's for edema helpful
- have seen "bone bruises" following ACL tears; new finding previously undetected; significance unclear
- Other considerations
- slipped captital femoral epiphysis
- osteosarcoma
- rheumatoid arthritis
- Lyme's disease