How the timeline is worked out
| Milestone | How it is estimated |
|---|---|
| Lengthening starts | 7 days after surgery in most protocols (Becker Betz Institute, Kocaoglu 2017); the BETZBONE diaries started after a median of 6 days |
| Lengthening done | Planned millimetres ÷ average millimetres per day. The defaults are what people reached, not what was planned: PRECICE and FITBONE 0.9 for thighs (Galal 2022) and 0.7 for shins (Reif 2025), BETZBONE 0.7 and 0.5 (diaries since 2022), LON 0.85 and 0.75 (Fragomen 2018, Lee 2014) |
| Frame off (LON) | 7 days after the last lengthening for thighs and 5 for shins (Kocaoglu 2017, patient diaries) |
| Walking without crutches | PRECICE and FITBONE: when the bone has healed, because weight is limited until then (Reif 2025). BETZBONE: 60 days after the last lengthening for thighs (median of 17 diaries), about 105 for shins (one diary). LON: 37 days after the frame comes off for thighs (4 diaries) and 60 for shins (14 diaries) |
| Bone healed | Days per cm from surgery until 3 of 4 cortices are bridged. PRECICE and FITBONE thighs 21 ± 6 (Reif 2025, 62 cosmetic femurs); shins 35 (25–43), between the 25 of 8 cosmetic shins and the 39–43 of larger groups. BETZBONE thighs 26 ± 6, borrowed from the steel weight-bearing STRYDE nail (Galal 2022) because no BETZBONE study exists. LON thighs 37 (30–43) and shins 48 (30–58), the median of published series. Never sooner than 25, 66 or 107 days after the last lengthening (66 ± 41 days in Reif 2025) |
| Nail removal | PRECICE and FITBONE: half of 314 nails came out 11–21 months after surgery, median 13.5 (Frost 2023). BETZBONE: 17–24 months where diaries reported it. LON: optional, 6–12 months after healing (Burghardt 2016) |
Example timelines
8 cm of thigh and 6 cm of shin at the default rates. Months are counted from surgery.
| Plan | Lengthening done | No crutches | Bone healed |
|---|---|---|---|
| BETZBONE, 8 cm thigh | Week 18 | 6 months | 5.5–8.5 months |
| BETZBONE, 6 cm shin | Week 19 | 7.5 months | 5–8.5 months |
| PRECICE, 8 cm thigh | Week 14 | 5.5 months | 4–7 months |
| PRECICE, 6 cm shin | Week 14 | 7 months | 5–8.5 months |
| LON, 8 cm thigh | Week 15 | 5 months | 8–11.5 months |
| LON, 6 cm shin | Week 13 | 5 months | 6–11.5 months |
What BETZBONE patients report
No published study reports BETZBONE results, so we read every patient diary we could find on the Limb Lengthening Forum and r/limblengthening: 41 thigh and 7 shin patients from 2013 to 2026, each counted once.
- Speed. About 20 clicks make 1 mm. Early patients clicked about 20 a day for the first few centimetres, then 15; since 2022 most click 10–14 a day. From surgery to the last click took a median of 125 days for a median 8.75 cm, about 15 days per cm since 2022, and 77% of 26 finished diaries slowed or paused at least once.
- Walking. Crutch walking from day 0–2. Crutches gone a median of 60 days after lengthening (0–149 days, 17 diaries), about six months after surgery; four more were still on crutches 6–8 months after surgery.
- Life. Desk or remote work after about 4.5 weeks, jobs on your feet after 5–6 months, running after about a year.
- Problems. 6 of about 33 first-hand thigh diaries needed another operation: four tendon or contracture releases, one loose screw, one re-break after the bone healed too early. People who post diaries are self-selected, and many diaries stop early.
- Shins. Only three finished diaries (5, 7.6 and about 10 cm), at about 0.5 mm a day with lengthening starting after 10–11 days. Two stopped or were told to stop because of a tight calf (equinus).
LON: frame first, then the nail
In lengthening over a nail, an external frame does the lengthening around a standard nail inside the bone. When the planned length is reached the nail is locked and the frame comes off, so the frame stays on for about 2–3 months instead of the whole healing time. In 32 cosmetic patients who gained 7.5 cm, the frame was on for 85.9 days and the bone healed at 30 days per cm; only 6 of them had the nail taken out (Kocaoglu 2017). Across cosmetic LON studies the frame stayed on 17.4 days per cm (Marwan 2020). In patient diaries the frame came off around day 88 for shins (20 diaries) and day 93 for thighs (7), and a tight calf, often released at frame removal, was the most common problem.
The methods compared
| Method | How it lengthens | Weight during treatment |
|---|---|---|
| BETZBONE | A mechanical ratchet (Medi-Tech, Germany): by patients' and the clinic's account, each inward-outward turn of the leg gives a click of about 0.05 mm. Up to 12.3 cm in the thigh, 10 cm in the shin | Full weight, according to the Becker Betz Institute |
| PRECICE | A magnet inside the nail, turned by a remote controller held against the leg. Up to 8 cm | Limited to about 50–75 lb until the bone has healed (Galal 2022) |
| FITBONE | An electric motor, powered through a receiver under the skin. Up to 8 cm | Limited; full weight came at the same time as with PRECICE (Calder 2024) |
| LON | An external frame lengthens the bone around a standard nail, then comes off | With crutches; more once the frame is off |
Weight seems to help healing: with the steel STRYDE nail, which allowed more weight than PRECICE, patients walked unaided after 12 weeks instead of 17 and their new bone mineralised faster (Bafor 2022). STRYDE was recalled in early 2021 over bone changes around the nail's junction (2022 study).
Why shins take longer
Shins are lengthened more slowly and heal more slowly. In 286 PRECICE lengthenings at one hospital, 20% of shins had a complication needing treatment against 10% of thighs, and 13.6% of all lengthenings needed another operation (Reif 2025), which adds time the calculator cannot show. The same study found faster healing in younger patients, in cosmetic lengthening and in lengthenings over 3 cm, so a bigger lengthening does not heal more slowly per centimetre, only for longer in total.
To see what a given lengthening does to your proportions, try it on your own photo in the limb lengthening simulator or check your femur to tibia ratio.