title: Limb lengthening with fully implantable magnetically actuated mechanical nails (PHENIX(®))-preliminary results.
abstract: Limb lengthening and deformity correction with fully implantable systems is becoming more and more widespread. Different actuation techniques are known and every system has its specific limitations in distraction control and/or stability. A new system with magnetic actuation offers outstanding options. The mechanism of the Phenix M2(®) bone lengthening nail (Phenix Medical, France) is driven by a strong external magnet. The device can provide lengthening, shortening and bone transport. Between December 2011 and November 2012 we applied the nail in 10 patients with an average age of 25 years (range 15-40 years). There were 6 femoral and 4 tibial procedures. The intended distraction goal was achieved in 8 of 10 patients. In three cases we simultaneously corrected malalignment. Average lengthening was 4.6 cm (range 1.3-7.6 cm). Average distraction index was 0.85 mm/day (range 0.6-1.3mm/day). Average weight bearing index was 27 days/cm (range 16-37 days/cm). Three patients had revisions due to early distraction arrest. The early results are comparable to those of other intramedullary systems in the literature like the ISKD(®), the Albizzia(®) or the Fitbone(®) system. All intramedullary procedures require accurate analysis and planning, advanced operative technique and close follow-up. The custom made design of the Phenix nail with unique options for size, stroke and locking provides new options for small bones and improved stability. The shortening option may be helpful for soft tissue problems, joint subluxation and additional stimulation of bone formation. Magnetic forces have to be considered and too much soft tissue around the nail might be a limiting factor. The magnetically actuated Phenix nail offers new therapeutic options in limb lengthening.
authors: Department of Trauma Surgery, Campus Innenstadt, Ludwig-Maximilians-University Munich, Germany. Electronic address: peter.thaller@med.uni-muenchen.de.
authors: Peter Helmut
authors: PH
authors: Thaller
authors: Department of Traumatology and Orthopaedics, Klinikum Schwabing, Munich, Germany.
authors: Julian
authors: J
authors: Fürmetz
authors: Department of Trauma Surgery, Campus Innenstadt, Ludwig-Maximilians-University Munich, Germany.
authors: Florian
authors: F
authors: Wolf
authors: Department of Trauma Surgery, Campus Innenstadt, Ludwig-Maximilians-University Munich, Germany.
authors: Thorsten
authors: T
authors: Eilers
authors: Department of Trauma Surgery, Campus Innenstadt, Ludwig-Maximilians-University Munich, Germany.
authors: Wolf
authors: W
authors: Mutschler
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D001852:Bone Lengthening / Q000295:instrumentation / Q000379:methods*; D001858:Bone Nails; D004867:Equipment Design; D005260:Female; D005269:Femur / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000601:surgery*; D005594:Fracture Fixation, Intramedullary; D006801:Humans; D007870:Leg Length Inequality / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D060328:Magnetic Phenomena; D059346:Magnets; D008297:Male; D019857:Osteogenesis, Distraction; D019736:Prostheses and Implants; D011859:Radiography; D013977:Tibia / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000601:surgery*; D016896:Treatment Outcome; D016474:Weight-Bearing
keywords: Deformity correction; Distraction osteogenesis; Fully implantable; Intramedullary nail; Limb lengthening; Magnetic nail; PHENIX(®); Telescopic nail