title: Individual headless compression screws fixed with three-dimensional image processing technology improves fusion rates of isolated talonavicular arthrodesis.
abstract: BACKGROUND
  Screw fixation is a typical technique for isolated talonavicular arthrodesis (TNA), however, no consensus has been reached on how to select most suitable inserted position and direction. The study aimed to present a new fixation technique and to evaluate the clinical outcome of individual headless compression screws (HCSs) applied with three-dimensional (3D) image processing technology to isolated TNA.
  
  
  METHODS
  From 2007 to 2014, 69 patients underwent isolated TNA by using double Acutrak HCSs. The preoperative three-dimensional (3D) insertion model of double HCSs was applied by Mimics, Catia, and SolidWorks reconstruction software. One HCS oriented antegradely from the edge of dorsal navicular tail where intersected interspace between the first and the second cuneiform into the talus body along the talus axis, and the other one paralleled the first screw oriented from the dorsal-medial navicular where intersected at the medial plane of the first cuneiform. The anteroposterior and lateral X-ray examinations certified that the double HCSs were placed along the longitudinal axis of the talus. Postoperative assessment included the American Orthopaedic Foot & Ankle Society hindfoot (AOFAS), the visual analogue scale (VAS) score, satisfaction score, imaging assessments, and complications.
  
  
  RESULTS
  At the mean 44-months follow-up, all patients exhibited good articular congruity and solid bone fusion at an average of 11.26 ± 0.85 weeks (range, 10 ~ 13 weeks) without screw loosening, shifting, or breakage. The overall fusion rates were 100%. The average AOFAS score increased from 46.62 ± 4.6 (range, 37 ~ 56) preoperatively to 74.77 ± 5.4 (range, 64-88) at the final follow-up (95% CI: -30.86 ~ -27.34; p < 0.001). The mean VAS score decreased from 7.01 ± 1.2 (range, 4 ~ 9) to 1.93 ± 1.3 (range, 0 ~ 4) (95% CI: 4.69 ~ 5.48; p < 0.001). One cases (1.45%) and three cases (4.35%) experienced wound infection and adjacent arthritis respectively. The postoperative satisfaction score including pain relief, activities of daily living, and return to recreational activities were good to excellent in 62 (89.9%) cases.
  
  
  CONCLUSIONS
  Individual 3D reconstruction of HCSs insertion model can be designed with three-dimensional image processing technology in TNA. The technology is safe, effective, and reliable to isolated TNA method with high bone fusion rates, low incidences of complications.
authors.affiliation: Department of Orthopaedic Surgery, Southwest Hospital, The Third Military Medical University, Gaotanyan Str. 30, Chongqing city, 400038, People's Republic of China.
authors.forename: Mei-Ming
authors.initials: MM
authors.lastname: Xie
authors.affiliation: Department of Orthopaedic Surgery, Southwest Hospital, The Third Military Medical University, Gaotanyan Str. 30, Chongqing city, 400038, People's Republic of China.
authors.forename: Kang
authors.initials: K
authors.lastname: Xia
authors.affiliation: Department of Orthopaedic Surgery, Southwest Hospital, The Third Military Medical University, Gaotanyan Str. 30, Chongqing city, 400038, People's Republic of China.
authors.forename: Hong-Xin
authors.initials: HX
authors.lastname: Zhang
authors.affiliation: Department of Orthopaedic Surgery, Southwest Hospital, The Third Military Medical University, Gaotanyan Str. 30, Chongqing city, 400038, People's Republic of China.
authors.forename: Hong-Hui
authors.initials: HH
authors.lastname: Cao
authors.affiliation: Department of Orthopaedic Surgery, Southwest Hospital, The Third Military Medical University, Gaotanyan Str. 30, Chongqing city, 400038, People's Republic of China.
authors.forename: Zhi-Jin
authors.initials: ZJ
authors.lastname: Yang
authors.affiliation: Department of Orthopaedic Surgery, Southwest Hospital, The Third Military Medical University, Gaotanyan Str. 30, Chongqing city, 400038, People's Republic of China.
authors.forename: Hai-Feng
authors.initials: HF
authors.lastname: Cui
authors.affiliation: Department of Orthopaedic Surgery, Southwest Hospital, The Third Military Medical University, Gaotanyan Str. 30, Chongqing city, 400038, People's Republic of China.
authors.forename: Shang
authors.initials: S
authors.lastname: Gao
authors.affiliation: Department of Orthopaedic Surgery, Southwest Hospital, The Third Military Medical University, Gaotanyan Str. 30, Chongqing city, 400038, People's Republic of China. tangkanglai@hotmail.com.
authors.forename: Kang-Lai
authors.identifier: http://orcid.org/0000-0002-0370-106X
authors.initials: KL
authors.lastname: Tang
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D001174:Arthrodesis / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods / Q000534:rehabilitation; D001863:Bone Screws; D019245:Compressive Strength; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D008875:Middle Aged; D017060:Patient Satisfaction; D011300:Preoperative Care / Q000379:methods; D013628:Talus / Q000000981:diagnostic imaging / Q000601:surgery*; D013639:Tarsal Bones / Q000000981:diagnostic imaging / Q000601:surgery*; D014057:Tomography, X-Ray Computed / Q000379:methods; D016896:Treatment Outcome
keywords: 3D reconstruction; Arthrodesis; Headless compression screws; Individualized preoperative planning; Talonavicular