The default distraction rate in limb lengthening is 1 mm/day.
Yet real patients rarely fit the “default”. Smoking, vitamin D status, BMI and pre-existing
muscle tightness can change the safe speed. Here’s a clear, patient-friendly guide.
Updated: 07 September 2025 • Your surgeon’s protocol prevails
Smoking
Vasoconstriction from nicotine reduces blood flow and slows regenerate formation.
Smokers often show delayed and weaker bone on X-rays.
Typical response: consider a slower rate 0.5–0.75 mm/day and tighter follow-up.
Vitamin D
Critical for mineralisation; deficiency is linked with low bone density and slow healing.
If levels are low, consolidation takes longer even at 1 mm/day.
For marked deficiency, use supplements and consider a temporary rate reduction.
Body Mass Index (BMI)
High BMI (>30): Greater mechanical load on the regenerate → avoid aggressive speeds;
many patients do well around ~0.75 mm/day.
Low BMI (<18.5): Lower muscle/bone reserves; consider modest rate and emphasise physiotherapy and nutrition.
Muscle Tightness
Pre-tight hamstrings, gastrosoleus (calf) or quadriceps raise risks of stiffness and contracture.
Common strategy: 0.5–0.75 mm/day with intensified stretching/physio.
Short “holiday” pauses may be used if nerve symptoms or range-of-motion loss appears—always surgeon-led.
Key Takeaways
The distraction rate must be personalised. In smokers, vitamin D deficiency,
high/low BMI, or notable muscle tightness, the rate is usually reduced and follow-up is more frequent.
The right speed protects bone quality and functional recovery.
