SYNOSTE Nitinail System Trial

SYNOSTE Nitinail System Trial is an international multicenter open label single-arm equivalence study to verify whether the leg-lengthening procedure can be adequately controlled with the SNS system as measured with the lengthening control index (LCI) at the end of the distraction period.

The SYNOSTE Nitinail System (SNS) is an assembly of an active implantable distraction nail (SYNOSTE Nitinail), Locking screws, accessory instruments for surgery and the home care unit (also External control unit (ECU) or Halo). It includes also, a software tool, Syndex, that supports setting up the number of lengthening activations needed per day. The SNS is intended for lengthening of the femur by distraction osteogenesis. The study will consist of a recruitment period of 3 months and an observation period of roughly 24 months (6 months after explantation). The observation period is split in two parts: The first part contains the most critical treatment phases from implantation surgery of the device through the actual lengthening phase up to the end of the bone healing. The second part contains only two visits: the explantation surgery of the device and a control at 6 months of further follow-up. After the fist part of the trial, a primary analysis of the data including the hypothesis testing will be carried out. After the second part of the trial a follow-up analysis will be done. 16 (max 20) patients will be recruited in Finland and Turkey.

distraction osteogenesis, bone lengthening, leg length discrepancy, callotasis, Intramedullary distraction nail

Mode of application: 1. Implantation surgery: osteotomy and antegrade implantation of SNS in femur for distraction osteogenesis (callotasis), 2. distraction osteogenesis (implant lengthening phase), 3. Bone healing (implant as stabilizing element during consolidation phase), 4. Explantation after consolidation.

The primary objective is to verify whether the leg-lengthening procedure can be adequately controlled with the SNS system as measured with the lengthening control index (LCI) at the end of the distraction period defined as LCI = DIachieved / DIscheduled ,where DIachieved = Achieved distraction index, ie. the daily rate of distraction has on average occurred during the lengthening phase in mm/d. DIscheduled = mean scheduled lengthening rate in mm/day. Analyzed at primary analysis.

Mechanical stability of Nitinail as defined by the ratio of the numbers of breakages (nail and screws) to total nails implanted (% and absolute values) at the end of consolidation

Nitinail lengthening target achieved as defined by % of targeted lengthening achieved by Nitinail determined at the end of lengthening period

Nitinail lengthening target achieved as defined by absolute value of targeted lengthening achieved by Nitinail determined at the end of lengthening period

Translation of nail lengthening to bone lengthening as % of the Bone gap increase from achieved lengthening of Nitinail determined at the end of lengthening period

Translation of nail lengthening to bone lengthening as absolute value of the Bone gap increase from achieved lengthening of Nitinail determined at the end of lengthening period

Retention of achieved length by Nitinail as change of achieved lengthening of Nitinail between end of distraction and end of consolidation

Patient satisfaction as the overall satisfaction value from Numeric Rating Scale at end of consolidation and final follow-up. The NRS for overall outcomes is a undimensional measure of satisfaction intensity, where the patient selects among 0-10 integers to describe the intensity of their overall satisfaction with the treatment outcomes on a horizontal line. "0" represents completely dissatisfied and "10" fully satisfied

Patient satisfaction as the aesthetic outcomes value from Numeric Rating Scale (NRS) at end of consolidation and final follow-up. The NRS for aesthetic outcomes is a undimensional measure of satisfaction intensity, where the patient selects among 0-10 integers to describe the intensity of their satisfaction with the aesthetic outcomes on a horizontal line. "0" represents completely dissatisfied and "10" fully satisfied.

Change in scores of SF-36 from preoperative baseline to end of consolidation for Primary analysis and to last visit for the Follow-up analysis. The used version of the SF-36 is the RAND 36-item health survey 1.0 (1993) with a time frame of 4 weeks. The SF-36 is an established and widely used set of generic, coherent, and easily administered quality-of-life measures in adults. Scoring will be done according to the instructions provided by RAND. Single item scores as well as health concept scale scores range from 0 to 100. A higher score defines a more favorable health state, with a value of 100 representing full health.

Patient pain status as change of Numeric Rating Scale (NRS) from preoperative baseline to End of distraction (2,5 months). The NRS for pain is a undimensional measure of pain intensity, where the patient selects among 0-10 integers to describe the intensity of their pain on a horizontal line. "0" represents no pain and "10" worst possible pain.

Patient pain status as the pain profile of the Numeric Rating Scale (as described above) during the treatment (until 24 months)

Length of sick leave due treatment in days assessed until the end of consolidation and end of treatment for Primary and Follow-up analyses, respectively

Femur lengthening target achieved as % of the achieved femoral length increase of the targeted femoral length increase in mm determined at the end of consolidation and end of treatment for Primary and Follow-up analyses

Femur lengthening target achieved as absolute value of the achieved femoral length increase of the targeted femoral length increase in mm determined at the end of consolidation and end of treatment for Primary and Follow-up analyses

Weight bearing index as time to final full weight bearing (in days) per the achieved femoral length increase (in cm)

Consolidation index as time to radiological confirmation of 3 cortices bridging the bony gap (in days) per the achieved femoral length increase (in cm)

Knee and hip joint Range of Motion (ROM) as flexion and extension at preoperative baseline, End of distraction and End of consolidation and compared to normal population values

Number and type of device related (Serious)Adverse Events reported until the end of consolidation and end of treatment.

Length of hospital stay of Nitinail related surgeries in days the patient spent in hospital perioperatively.

Patient compliance to lengthening protocol as ratio of lengthening periods with non- compliance to protocol with all lengthening periods with one patient.

Release of metallic ions from the Nitinail as Cobalt and Chromium ion concentrations in blood from preoperative baseline to end of distraction.

Inclusion Criteria: Indication for femoral lengthening from different etiologies of max. 70 mm at single lengthening 18 to 65 years regardless of gender Suitable anatomy for SNS Able and willing to comply with study procedures Exclusion Criteria: Other electronic implants Other Metallic implants in the affected limb below the osteotomy level Need for Magnetic Resonance imaging during the study BMI>30kg/m2 or weight>100kg Smoker Known hypersensitivity to Co, Ni, Cr or Ti metals Known hypersensitivity to Poly-Ether-Ether-Ketone (PEEK) or Ultrahigh Molecular Weight Poly-Ethylene (UHMWPE) Open growth plates Malignancy or tumor in bone Osteitis or soft tissue infection Significant existing deficit in range of motion of the adjacent joints Pseudoarthrosis Pregnancy Low psychological compliance (e.g. drug abuse) Simultaneous bilateral lengthening Need for osteotomies at multiple levels