title: Influence of fragment size and postoperative joint congruency on long-term outcome of posterior malleolar fractures.
abstract: BACKGROUND
  One of the factors contributing to long-term outcome of posterior malleolar fractures is the development of osteoarthritis. Based on biomechanical, cadaveric, and small population studies, fixation of posterior malleolar fracture fragments (PMFFs) is usually performed when fragment size exceeds 25-33%. However, the influence of fragment size on long-term clinical and radiological outcome size remains unclear.
  
  
  METHODS
  A retrospective cohort study of 131 patients treated for an isolated ankle fracture with involvement of the posterior malleolus was performed. Mean follow-up was 6.9 (range, 2.5-15.9) years. Patients were divided into groups depending on size of the fragment, small (<5%, n = 20), medium (5-25%, n = 86), or large (>25%, n = 25), and presence of step-off after operative treatment. We have compared functional outcome measures (AOFAS, AAOS), pain (VAS), and dorsiflexion restriction compared to the contralateral ankle and the incidence of osteoarthritis on X-ray.
  
  
  RESULTS
  There were no nonunions, 56% of patients had no radiographic osteoarthritis, VAS was 10 of 100, and median clinical score was 90 of 100. More osteoarthritis occurred in ankle fractures with medium and large PMFFs compared to small fragments (small 16%, medium 48%, large 54%; P = .006). Also when comparing small with medium-sized fragments (P = .02), larger fragment size did not lead to a significantly decreased function (median AOFAS 95 vs 88, P = .16). If the PMFF size was >5%, osteoarthritis occurred more frequently when there was a postoperative step-off ≥1 mm in the tibiotalar joint surface (41% vs 61%, P = .02) (whether the posterior fragment had been fixed or not). In this group, fixing the PMFF did not influence development of osteoarthritis. However, in 42% of the cases with fixation of the fragment a postoperative step-off remained (vs 45% in the group without fixation).
  
  
  CONCLUSIONS
  Osteoarthritis is 1 component of long-term outcome of malleolar fractures, and the results of this study demonstrate that there was more radiographic osteoarthritis in patients with medium and large posterior fragments than in those with small fragments. Radiographic osteoarthritis also occurred more frequently when postoperative step-off was 1 mm or more, whether the posterior fragment was fixed or not. However, clinical scores were not different for these groups.
  
  
  METHODS
  Level IV, retrospective case series.
authors: Departement of General Surgery, Bronovo Hospital, The Hague, Netherlands cdrijfhout@gmail.com.
authors: Cornelis Christiaan
authors: CC
authors: Drijfhout van Hooff
authors: Departement of General Surgery, Medisch Centrum Haaglanden, The Hague, Netherlands.
authors: Samuel Marinus
authors: SM
authors: Verhage
authors: Departement of General Surgery, Medisch Centrum Haaglanden, The Hague, Netherlands.
authors: Jochem Maarten
authors: JM
authors: Hoogendoorn
mesh_terms: D000328:Adult; D000368:Aged; D064386:Ankle Fractures / Q000000981:diagnostic imaging / Q000601:surgery*; D000843:Ankle Joint / Q000000981:diagnostic imaging; D015331:Cohort Studies; D004185:Disability Evaluation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000000981:diagnostic imaging*; D011859:Radiography; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D064232:Visual Analog Scale; D055815:Young Adult
keywords: AAOS; AOFAS; VAS; ankle; dorsiflexion; follow-up; fracture; fragment; long-term; malleolar; osteoarthritis; posterior; postoperative; step-off; trimalleolar