Unequal leg lengths : Limb Length Discrepancy

LLD : Limb Length Discrepancy

Limb Length Discrepancy (LLD)

Definition: where one limb is in a different length than its opposing limb, can be longer or shorter due to many causes.

Causes

1. Congenital (from birth)
2. Developmental:  can be from a childhood disease or injury that slows down or damages the growth plates
3. Post-traumatic

• Car accident that causes a fracture which leads to shortening of the bone ends)

How to attend to patient?

Intro:

• Confirm name, age
• Ask chief complain and other important history (any motor vehicle accident before?)
• Ask for consent and a chaperone if needed.
• Always be friendly and make patient comfortable.

Inspection

For 4 aspects when the patient is Standing → check front, side and back↔ check for DAWSSS

• Deformity
• Asymmetry
• Wasting
• Swelling
• Scar
• Straight

Gait

Ask patient to walk normally and to walk on heels and toes.

Types of gait to look out for:

• Short limb gait : dislocation of femur head or others -- confirm with bryant's triangle
• Tredelenburg : Gluteus weakness, can be direct or indirect
• Stiff knee : Osteoarthritis, Rheumatoid Arthritis
• Antalgic gait : Pain, Limping and lag gait
• High Stepping : Common among patient with peroneal nerve injury or palsy / sciatic nerve injury
• Others: Spastic(Cerebral palsy), scissoring(UMN issue)

Supine on bed : Lie flat and inspect 

If there are gait issue go straight to finding the source

Check apparent length

- Measure the length from xiphisternum to medial malleolus of left and right

- Compare both sides

Check True length

- measure from Anterior Superior Iliac Spine(ASIS) to medial malleolus
-Compare both sides

Interpretation:
True shortening>Apparent shortening: Deformity compensated by pelvis tilt
True shortening<Apparent shortening: Fixed Deformity without any compensation

If there is one side longer than the other(suspect injury above knee joint) perform the specific tests

1. Galaezzi Test

• Check for hip dislocation
• Check when the patient is in supine position. 
• Performed by flexing the knees while lying down so that the feet touch the surface and ankles at buttocks. 
• Check the tibial length by flexing knee 90 degree and ankle 45 degree

Interpretation:

• Shorter leg is the affected leg (femur head dislocated)
• Knee shifts cephalad(outward) when the femoral length is reduced, and caudally(inward) when the tibial length is reduced
• If it is parallel: LLD is below knee joint

2. Bryant's Triangle test

• to check LLD above knee joint

Line A: Line connecting the greater trochanter of femur with ASIS

Line B: Vertical line done from ASIS towards the bed (perpendicular with bed)

Line C: Horizontal line starting from greater trochanter to meet end of line B

(compare length of line C on both sides for diagnosis)

Interpretation: 

• diminution or increase in the length of line C : 
• to measure supra trochanteric shortening
• anterior or posterior displacement of the greater trochanter
• can be cause by: dislocation of hip, fracture of femur neck , hip deformity, intra-trochanteric fracture
• If both side are the same: the injury/ fracture might be in the middle of femur

Palpation and sensation

• Tone - Hip Knee Ankle
• Pain/tenderness - Hip, pubic symphysis, anterior superior iliac spine, axis, PSIS, greater trochanter
• Temperature of each part. 

Motor Examination

• Ideally would be to do a full motor examination, 
• If the patient is in pain, focus on the examination specific to the patient's issue. They will be grateful that you help them attend to the issue ASAP. 
• Range of movement for: hip, knee and ankle

Neurovascular Examination:

• pulse
• sensory
• example: wriggle toes and see if they can feel which toe is moving

Other special tests: 

• Thomas Test
• Check the fixed and flexion deformity of hip

• 1st picture is normal and 2nd is abnormal
• Ensure their lower back is flat. 
• Abnormal: Posterior thigh does not touch the table, knee flexion < 80 degrees

• Tredelenburg test
• examine strength of the abductor mechanism of hip
• One legged stance, if the weight bearing hip is unstable the pelvis drop to unsupported side

•  X-ray: check the AP view and lateral view

Ideally to take full history, examine spine and knee, access patient with radiography.

Other references:
1. http://www.limblength.org/conditions/limb-length-discrepancy-lld/
2. https://www.slideshare.net/ManishShetty8/clinical-examination-of-hip-122918037

3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1796883/