Leg length discrepancy (LLD) -- a difference in the functional or structural length between the two legs -- is significantly more common than is generally recognised. True structural LLD (different bone lengths) affects approximately 70-90% of the population to some degree, with differences of under 10mm considered within normal variation. Clinically significant LLD (typically over 20mm functional difference) causes altered gait mechanics, pelvic obliquity, and secondary musculoskeletal effects that may warrant intervention.
How LLD Affects Gait
LLD causes systematic gait compensation that varies depending on the side and magnitude of the discrepancy:
- Short-leg-side adaptations: The pelvis drops on the short side (Trendelenburg-like sign without the associated weakness), the ankle plantarflexes to lengthen the effective leg, and the knee flexes on the long side
- Energy cost: Compensatory gait requires more energy per step than normal gait -- the body is working against itself to maintain a functional walking pattern
- Secondary effects: Chronic LLD gait compensation contributes to lumbar scoliosis (functional), sacroiliac joint dysfunction, hip OA (typically on the longer limb, which bears greater impact loading), and knee OA
Primary Treatment: Shoe Lift
The first-line intervention for clinically significant LLD is a shoe lift (heel raise) to partially or fully equalise limb length. This is not a cane function and should be pursued with an orthotist or podiatrist. However, many LLD patients are either awaiting assessment, have an undiagnosed LLD contributing to their symptoms, or have LLD in combination with other conditions where the compensatory mechanics create secondary pain.
Where a Cane Helps in LLD
A cane can help LLD patients in several specific scenarios:
- While awaiting shoe lift assessment: The cane provides stability during the period when LLD-related gait dysfunction is present but not yet corrected
- Pain-generating compensation: If the LLD compensation is causing hip, knee, or back pain, the cane on the appropriate side reduces loading on the symptomatic joint
- Post-surgical LLD: Hip replacement and other procedures can create or resolve LLD. The period after surgery during which the new length is being adapted to benefits from cane support
- In combination with secondary OA: If LLD has caused hip or knee OA, the cane addresses the secondary OA-related pain and loading (contralateral to the affected joint)
Cane Side in LLD
The correct cane side depends on which problem is being addressed:
| Primary Problem | Cane Side | Rationale |
|---|---|---|
| Hip pain on long-leg side | Contralateral (short-leg side hand) | Offloads the painful long-leg hip |
| Hip pain on short-leg side | Contralateral (long-leg side hand) | Offloads the painful short-leg hip |
| Knee pain on either side | Contralateral to painful knee | Standard contralateral rule |
| Back pain from LLD scoliosis | Physiotherapist assessment needed | Case-dependent |
Cane Height in LLD
For LLD patients without a shoe lift, the correct cane height should be calibrated in the normal standing position (with the natural compensatory posture). If a shoe lift is introduced, cane height should be recalibrated with the lift in place, as the lift changes standing posture and therefore optimal cane height. Use the DaiWalk cane length calculator.
View the full DaiWalk cane range. Related: Walking Cane for Hip Dysplasia | Walking Cane for Hip and Knee Osteoarthritis
