title: Outcomes of operative treatment of unstable ankle fractures: a comparison of metallic and biodegradable implants.
abstract: BACKGROUND
  Biodegradable implants for internal fixation of ankle fractures may overcome some disadvantages of metallic implants, such as imaging interference and the potential need for additional surgery to remove the implants. The purpose of this study was to evaluate the outcomes after fixation of ankle fractures with biodegradable implants compared with metallic implants.
  
  
  METHODS
  In this prospectively randomized study, 109 subjects with an ankle fracture underwent surgery with metallic (Group I) or biodegradable implants (Group II). Radiographic results were assessed by the criteria of the Klossner classification system and time to bone union. Clinical results were assessed with use of the American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot scale, Short Musculoskeletal Function Assessment (SMFA) dysfunction index, and the SMFA bother index at three, six, and twelve months after surgery.
  
  
  RESULTS
  One hundred and two subjects completed the study. At a mean of 19.7 months, there were no differences in reduction quality between the groups. The mean operative time was 30.2 minutes in Group I and 56.4 minutes in Group II (p < 0.001). The mean time to bone union was 15.8 weeks in Group I and 17.6 weeks in Group II (p = 0.002). The mean AOFAS score was 87.5 points in Group I and 84.3 points in Group II at twelve months after surgery (p = 0.004). The mean SMFA dysfunction index was 8.7 points in Group I and 10.5 points in Group II at twelve months after surgery (p = 0.060). The mean SMFA bother index averaged 3.3 points in Group I and 4.6 points in Group II at twelve months after surgery (p = 0.052). No difference existed between the groups with regard to clinical outcomes for the subjects with an isolated lateral malleolar fracture.
  
  
  CONCLUSIONS
  The outcomes after fixation of bimalleolar ankle fractures with biodegradable implants were inferior to those after fixation with metallic implants in terms of the score on the AOFAS scale and time to bone union. However, the difference in the final AOFAS score between the groups may not be clinically important. The outcomes associated with the use of biodegradable implants for the fixation of isolated lateral malleolar fractures were comparable with those for metallic implants.
authors.affiliation: Departments of Orthopaedic Surgery, Kangwon National University Hospital, 156 Baengnyeong-ro, Chuncheon-si, Gangwon-do 200-722, South Korea. bestknee@hotmail.com
authors.forename: Jung Ho
authors.initials: JH
authors.lastname: Noh
authors.forename: Young Hak
authors.initials: YH
authors.lastname: Roh
authors.forename: Bo Gyu
authors.initials: BG
authors.lastname: Yang
authors.forename: Seong Wan
authors.initials: SW
authors.lastname: Kim
authors.forename: Jun Suk
authors.initials: JS
authors.lastname: Lee
authors.forename: Moo Kyung
authors.initials: MK
authors.lastname: Oh
mesh_terms: D020341:Absorbable Implants; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016512:Ankle Injuries / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery*; D001863:Bone Screws; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D005593:Fracture Fixation, Internal / Q000295:instrumentation* / Q000379:methods; D017102:Fracture Healing / Q000502:physiology; D050723:Fractures, Bone / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D015601:Injury Severity Score; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000209:etiology / Q000601:surgery*; D008297:Male; D008670:Metals; D008875:Middle Aged; D011183:Postoperative Complications / Q000503:physiopathology / Q000628:therapy; D011446:Prospective Studies; D011859:Radiography; D020127:Recovery of Function; D018570:Risk Assessment; D013639:Tarsal Bones / Q000000981:diagnostic imaging / Q000293:injuries / Q000601:surgery; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D008670:Metals