title: Can computer-assisted surgery help restore leg length and offset during THA? A continuous series of 321 cases.
abstract: BACKGROUND
  Total hip arthroplasty (THA) can bring about complications - particularly leg length differences - that are becoming increasingly litigious. Computer-assisted orthopedic surgery (CAOS) can help optimize the procedure, but its ability to effectively restore leg length is controversial. As a consequence, we carried out a study to determine: (1) its contribution to meeting leg length and offset objectives, (2) its reliability, by evaluating the correlation between radiological and navigation data, (3) its safety, by evaluating navigation-specific and non-specific complications.
  
  
  OBJECTIVE
  CAOS will help to restore leg length within ± 5 mm in more than 80% of cases.
  
  
  METHODS
  A series of 321 continuous cases of cementless THA implanted through the posterolateral approach using CAOS was analyzed retrospectively. With a minimum 1 year follow-up, we evaluated whether the leg length and offset goals were achieved, how well the navigation and radiology data were correlated and whether navigation-specific and non-specific complications occurred. Based on our hypothesis that 80% of patients would have less than 5 mm leg length difference and the null hypothesis (PA = P0) with an alpha of 0.05, 200 observations were required to achieve a power of 90%.
  
  
  RESULTS
  The leg length and offset objectives were achieved in 83.3% and 88% of cases, respectively. Twenty-two patients required a heel wedge to compensate for leg length differences. The correlation between the radiology and surgical navigation data was satisfactory - the Pearson coefficient was 0.79 for length and 0.74 for offset. Intraoperative and postoperative complications or adverse events were found in 14.6% of cases; these were specific to CAOS in 12.1% of cases and non-specific in 2.5% of cases.
  
  
  CONCLUSIONS
  This study shows the relevance of CAOS for achieving preoperative leg length objectives, with good correlation between navigation and radiology data, and without major complications.
  
  
  METHODS
  IV - retrospective study.
authors.affiliation: Université de Bretagne Occidentale, Faculté de Médecine, 22, avenue Camille-Desmoulins, 29200 Brest, France; CHRU Brest, Service de Chirurgie Orthopédique et Traumatologique de la Cavale Blanche, boulevard Tanguy-Prigent, 29200 Brest, France; LaTIM, INSERM UMR 1101, 2, avenue Foch, 29609 Brest, France. Electronic address: arnaud.clave@orange.fr.
authors.forename: A
authors.initials: A
authors.lastname: Clavé
authors.affiliation: Université de Bretagne Occidentale, Faculté de Médecine, 22, avenue Camille-Desmoulins, 29200 Brest, France; CHRU Brest, Service de Chirurgie Orthopédique et Traumatologique de la Cavale Blanche, boulevard Tanguy-Prigent, 29200 Brest, France.
authors.forename: V
authors.initials: V
authors.lastname: Sauleau
authors.affiliation: Université de Bretagne Occidentale, Faculté de Médecine, 22, avenue Camille-Desmoulins, 29200 Brest, France; CHRU Brest, Service de Chirurgie Orthopédique et Traumatologique de la Cavale Blanche, boulevard Tanguy-Prigent, 29200 Brest, France.
authors.forename: D
authors.initials: D
authors.lastname: Cheval
authors.affiliation: Université de Bretagne Occidentale, Faculté de Médecine, 22, avenue Camille-Desmoulins, 29200 Brest, France; CHRU Brest, Service de Chirurgie Orthopédique et Traumatologique de la Cavale Blanche, boulevard Tanguy-Prigent, 29200 Brest, France.
authors.forename: T
authors.initials: T
authors.lastname: Williams
authors.affiliation: Université de Bretagne Occidentale, Faculté de Médecine, 22, avenue Camille-Desmoulins, 29200 Brest, France; CHRU Brest, Service de Chirurgie Orthopédique et Traumatologique de la Cavale Blanche, boulevard Tanguy-Prigent, 29200 Brest, France; LaTIM, INSERM UMR 1101, 2, avenue Foch, 29609 Brest, France.
authors.forename: C
authors.initials: C
authors.lastname: Lefèvre
authors.affiliation: Université de Bretagne Occidentale, Faculté de Médecine, 22, avenue Camille-Desmoulins, 29200 Brest, France; CHRU Brest, Service de Chirurgie Orthopédique et Traumatologique de la Cavale Blanche, boulevard Tanguy-Prigent, 29200 Brest, France; LaTIM, INSERM UMR 1101, 2, avenue Foch, 29609 Brest, France.
authors.forename: E
authors.initials: E
authors.lastname: Stindel
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000601:surgery; D006801:Humans; D007870:Leg Length Inequality / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012189:Retrospective Studies; D025321:Surgery, Computer-Assisted; D055815:Young Adult
keywords: Computer-assisted orthopedic surgery; Limb length discrepancy; Total hip arthroplasty