title: Complications of the Intramedullary Skeletal Kinetic Distractor (ISKD) in distraction osteogenesis.
abstract: BACKGROUND
  The Intramedullary Skeletal Kinetic Distractor (ISKD) (Orthofix Inc, Lewisville, TX, USA) is an intramedullary device designed for more comfortable limb lengthening than that with external fixators; lengthening is achieved with this nail using rotational oscillation between two telescoping sections. However, the degree to which this device achieves this goal and its complication rate have not been fully documented.
  
  
  OBJECTIVE
  We determined (1) the frequency with which distraction was not achieved at the desired rate, (2) whether pain differed between patients with normally and abnormally distracting nails, (3) risk factors for abnormal nails, and (4) other complications.
  
  
  METHODS
  We analyzed 35 lengthening segments (26 femurs, nine tibias) in 19 patients. Mean length achieved was 47 mm. Femoral nails were categorized into four groups according to distraction rate: normal, runaway (unintentionally faster rate [> 1.5 mm/day]), difficult-to-distract (slower rate [< 0.8 mm/day] requiring manual manipulation but not requiring general anesthesia), and nondistracting (slower rate [< 0.8 mm/day] requiring manual manipulation under general anesthesia or reosteotomy). Possible risk factors, including age, BMI, preoperative thigh circumferences, degree of intramedullary overreaming, and length of the thicker portion of the nail within the distal fragment, were compared among groups. VAS pain scores were compared among groups under three conditions: rest, physiotherapy, and distraction motion. Complications were also analyzed. Minimum followup was 15 months (mean, 26 months; range, 15-38 months) after first-stage surgery.
  
  
  RESULTS
  Abnormal distraction rate was observed in 21 of 35 segments (60%; 17 femurs, four tibias). VAS pain scores showed no differences among groups during rest or physiotherapy but were higher (p = 0.02) in the problematic nails (7-8 points) versus normal nails (3 points) during distraction. Only mean length of the thicker portion of the nail within the distal fragment differed between normally and abnormally distracting nails (95 mm versus 100 mm; p = 0.03), although this was unlikely to be clinically important. Complications occurred in 10 patients (53%), including five with decreased ankle ROM during distraction, four with delayed bone healing, and one with mechanical device failure during distraction.
  
  
  CONCLUSIONS
  Rate control was difficult to achieve with the ISKD nail for femoral and tibial lengthenings, complications were relatively common, and among patients in whom rate control was not achieved, pain levels were high. Based on our findings, we believe that surgeons should avoid use of this nail.
  
  
  METHODS
  Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopaedic Surgery, Severance Hospital, College of Medicine, Yonsei University, 134 Sinchondong, CPO Box 8044, Seoul, Republic of Korea, orthopaedee@naver.com.
authors.forename: Dong Hoon
authors.initials: DH
authors.lastname: Lee
authors.forename: Keun Jung
authors.initials: KJ
authors.lastname: Ryu
authors.forename: Hae Ryong
authors.initials: HR
authors.lastname: Song
authors.forename: Soo-Hong
authors.initials: SH
authors.lastname: Han
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000843:Ankle Joint / Q000503:physiopathology; D001696:Biomechanical Phenomena; D001858:Bone Nails / Q000009:adverse effects*; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019857:Osteogenesis, Distraction / Q000009:adverse effects* / Q000295:instrumentation*; D010147:Pain Measurement; D010149:Postoperative Pain / Q000175:diagnosis / Q000209:etiology*; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D012307:Risk Factors; D013977:Tibia / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult