title: Subtalar joint arthrodesis using a single lag screw.
abstract: BACKGROUND
  This study tested the hypotheses that fusing the subtalar joint with a single lag screw from the posteroinferior calcaneus to the anterior talar neck is an effective technique and that factors affecting the time to fusion can be identified.
  
  
  METHODS
  Between October, 1995, and July, 2002, the senior author (RAM) performed 101 isolated subtalar arthrodeses using a technique of single lag-screw fixation from posteroinferior to anterosuperior across the posterior facet of the subtalar joint combined with the application of an autograft taken from the floor of the sinus tarsi and anterior process. The average patient age was 52 (range 17 to 82) years. There were 52 women (53 arthrodeses) and 48 men (48 arthrodeses). Eight of 101 (8%) arthrodeses were revisions. The indications included posttraumatic arthritis (45), posterior tibial tendon dysfunction (18), failed prior ankle joint fusion (14), idiopathic disorders (12), hindfoot coalition (7), rheumatoid arthritis (3), and Charcot-Marie-Tooth disease (2). Fifteen of 101 patients (15%) smoked an average of 0.9 +/- 0.5 pack of cigarettes per day.
  
  
  RESULTS
  Two of 101 joints did not fuse, resulting in an overall fusion rate of 98%. The average time to fusion was 12.3 +/- 3.4 weeks. The presence of a prior ankle fusion significantly prolonged the time to fusion of the subtalar joint (11.9 +/- 2.3 vs. 14.9 +/- 7.0, p = .003). Other factors, including smoking, revision surgery, patient age, and patient sex, did not affect time to fusion. The fixation screw was removed in 13 of 101 (13%) joints at an average of 8.8 +/- 0.5 months.
  
  
  CONCLUSIONS
  Using a single 7.0-mm lag screw across the posterior facet of the subtalar joint results in fusion of the subtalar joint in 98% of patients. A prior ankle arthrodesis delays the time to fusion of the subtalar joint by 3 weeks. This is a simple and reliable technique for achieving fusion of the subtalar joint.
authors.affiliation: Palo Alto Medical Foundation, Palo Alto, California, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Haskell
authors.forename: Cynthia
authors.initials: C
authors.lastname: Pfeiff
authors.forename: Roger
authors.initials: R
authors.lastname: Mann
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001174:Arthrodesis / Q000295:instrumentation* / Q000379:methods; D001863:Bone Screws; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013380:Subtalar Joint / Q000601:surgery*; D016896:Treatment Outcome