FITBONE vs PRECICE: what a 41-patient Istanbul comparison found

The two groups matched where a fair comparison needs them to: age, height, the amount of shortening and every preoperative angle measurement. They differed in how the femoral nails went in, with far more FITBONE nails inserted from the knee (retrograde) and more PRECICE nails from the hip (antegrade), and in follow-up time, which was significantly longer in the PRECICE group (p = .027). The PRECICE nails were the second-generation model. All 41 patients completed their lengthening, and nobody was excluded.

Nail length was chosen from calibrated digital X-rays so that, fully extended, at least 2 to 3 cm of the nail's thicker part would still sit inside the lengthening zone, as the manufacturers advise. Where a deformity needed correcting, the bone was cut at the apex of the deformity and straightened during the operation. For pure shortening, the cut was placed in the shaft to avoid creating a new deformity. The osteotomy itself was made through a small incision with a drill and finished with a thin osteotome.

FITBONE needs one extra step: a tunnel for the cable that runs from the motor unit to an antenna placed under the skin. Before the patient woke, each nail was lengthened by 1 to 2 mm under fluoroscopy to confirm it worked. In the tibia, the team also fixed the lower tibiofibular joint with a screw and removed a 1 cm block of fibula.

Hip, knee and ankle exercises started the day after surgery. Lengthening began after a 7-day pause for the femur and 5 to 7 days for the tibia, at 1 mm a day in four 0.25 mm steps. X-rays were taken every two weeks while lengthening and every six weeks during consolidation, and full weight-bearing was allowed once three of the four bone cortices had bridged. Patients with a congenitally short femur and deficient knee ligaments wore a knee brace in full extension 22 hours a day.

No. Both nails lengthened at a similar pace, the new bone consolidated at a similar pace, and neither difference was statistically significant. The study measured healing with two standard ratios. The distraction index is millimeters gained per day of lengthening. The consolidation index is the time until three of four cortices have bridged on X-ray, divided by the centimeters gained; lower is faster.

At 31 to 32 days per centimeter, a patient who gained the PRECICE group's average of 5.7 cm would reach that three-cortex point roughly six months after surgery. Every patient consolidated. Delayed union occurred in one FITBONE patient and two PRECICE patients, and all went on to heal after further surgery with bone grafting, including a nail exchange to a rigid nail in the PRECICE cases. On the ASAMI-modified Paley bone score, 90% of the FITBONE group and 85.71% of the PRECICE group were rated very good, and the rest good.

Neither did. In the 27 patients who had lengthening alone, the mechanical axis and the distal femoral angles did not change significantly as the bone grew longer. That answers a real worry with long nails: that the bone drifts off line as it lengthens.

Fourteen patients had a deformity corrected in the same operation, 8 bowed inward (varus) and 6 outward (valgus), spread evenly between the groups. In the varus cases the mechanical axis deviation fell from 29.6 to 12 mm; in the valgus cases it moved from −14.7 to 7 mm, and the distal femoral joint angle returned to normal limits. The two groups' postoperative alignment did differ on three measures, but the authors trace that to which patients had deformity corrections, not to the nails.

One honest wrinkle. All measurements were made on full-length standing X-rays viewed from the front, so the side-on (sagittal) plane was not fully assessed.

Complications affected 3 of 20 FITBONE patients (20%; the authors count four complications) and 4 of 21 PRECICE patients (19.05%). None changed the final result, none left a permanent problem, and every bone had united at final follow-up. The table lists each one with its fix, because the type of complication tells you more than the rate.

The authors set these figures against a 2021 systematic review of 983 segments lengthened with FITBONE and PRECICE nails, which found one complication per three segments and a major-impact complication in one segment of every four. Their own rates, they conclude, were close to the literature. They also cite a 2020 review by Morrison and colleagues listing the problems specific to motorized nails: a nail that will not distract, poor regenerate and nonunion, device breakage, new deformity, joint contracture or subluxation, and nerve or vessel injury.

The PRECICE patients who had complications were followed for 24 to 39 months; in the FITBONE group the longest follow-up was 29 months.

Function ended up the same. The Lower Extremity Functional Scale (LEFS), a patient questionnaire about everyday activities scored here as a percentage, averaged 78.50% (± 12.5) with FITBONE and 78.75% (± 13.7) with PRECICE, with no significant difference (p = .425).

The lowest scores followed the underlying condition rather than the nail. In the FITBONE group they belonged to three patients lengthened for hemihypertrophy, polio sequelae and developmental dysplasia of the hip. In the PRECICE group, they belonged to a patient with osteogenesis imperfecta lengthened for post-traumatic shortening and to one with fibular hemimelia.

For context, the authors cite a 15-patient series of post-traumatic lengthening with an external limb reconstruction system that reported a mean LEFS of about 75%, similar to theirs, and a patient-satisfaction study in which people who had tried both preferred nails to external fixators for pain, appearance and ease of rehabilitation. Their own reading is careful. The common view, they note, is that nails make the lengthening period more comfortable without changing final function; they call that open to discussion and suggest scoring function before and after surgery to settle it.

The authors list practical differences even though their outcomes did not separate the nails. PRECICE comes in more lengths and diameters than FITBONE, and it can be wound back: the nail can shorten, which helps if a bone has been over-lengthened and allows alternating distraction and compression when a regenerate is slow to unite. FITBONE, lengthened by a fully enclosed motor that draws energy from an external control unit through a receiver under the skin, can cause problems with placing that antenna, and the authors describe a risk of fracture during surgery from the way its locking screws are driven.

"The PRECICE nail appears to be more advantageous for application," they write, and in the next breath say their study produced no data to support that. Which nail a patient received depended on what was available at the time, not on the patient's characteristics.

For device-level detail, including the newer PRECICE generations and their recall history, see our method pages for FITBONE, PRECICE 2 and PRECICE Max.

If you are weighing the two for a limb-length discrepancy or a deformity, this study gives no reason to think the nail will decide your outcome. Healing speed, complication rates and final function were statistically the same. The factors the authors call critical are harder to see in a brochure: surgical training, careful preoperative planning, minimally invasive technique, the mechanical integrity of the construct, and control of the distraction rate and rhythm.

Keep the limits in view. The study was retrospective and not randomized, with 41 patients; the femoral nails went in by different routes in the two groups; and it covered one bone per patient, for medical reasons, using the second-generation PRECICE rather than the newer PRECICE Max. It cannot tell you how either nail performs in bilateral cosmetic lengthening. On FITBONE vs PRECICE, the fair summary is a tie in this series, with PRECICE more flexible on paper. Ask your surgeon which nail they use most, and how many of each they have implanted.