Factors predisposing to dislocation after primary total hip arthroplasty

Background Reports in the literature have linked high acetabular inclination angles to increased wear of ceramicon-ceramic bearings. However, many of these studies were only conducted in vitro and did not address the clinical relevance of such findings. Questions/purposes We therefore determined: (1) whether the cup inclination angle influences survival or function in patients with ceramic-on-ceramic implants; (2) the incidence of radiolucencies, osteolysis, and subsidence of ceramic-on-ceramic implants; and (3) whether the survival rate higher for ceramic-on-ceramic THAs than for conventional metal-on-polyethylene THAs.Methods We retrospectively reviewed 537 THAs performed in 512 prospectively followed patients having THA between October 1996 and October 2000. Eleven patients (12 hips) were lost to followup before 2 years, leaving 501 patients (525 THAs); of these, 421 were alumina ceramic-on-ceramic articulations and 104 cobaltchromium-on-polyethylene. The mean age was 54 years. We determined acetabular cup inclination angles, Harris hip scores, Health-Status-Questionnaire-12 scores, and presence and location of any radiolucencies, osteolysis, or radiographic subsidence. We compared survival using the Kaplan-Meier method. The minimum followup was 24 months (mean, 59 months; range, 24-120 months). Results Twenty-two of the 424 THAs (4.2%) were revised. We observed no difference in clinical or radiographic outcomes with respect to cup inclination angles. Radiographically, two loose acetabular components and two femoral components had subsided. The 5-year survival rate was slightly higher for ceramic-on-ceramic bearings (98%) than for metal-on-polyethylene (92%).

Section: Methodsmentioning

confidence: 89%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Does Acetabular Inclination Angle Affect Survivorship of Alumina-ceramic Articulations?

Johansson

Johnson

Zywiel

et al. 2011

“…There have been numerous reports regarding the optimal orientation of the acetabular component in THA [1][2][3][4][5]8]. Although debate remains on this topic, the classical target for cup orientation in THA is the so-called ''Lewinnek safe zone'' with an abduction angle of 40°± 10°and an anteversion angle of 15°± 10° [1][2][3][4][5]8]. Use of mechanical acetabular guides for intraoperative alignment leads to variations between the actual and desired implant orientation mainly as a result of the variations of the patient position on the operative table [5].…”

Section: Introductionmentioning

confidence: 99%

No Benefit After THA Performed With Computer-assisted Cup Placement: 10-year Results of a Randomized Controlled Study

Parratte

Ollivier

Lunebourg

et al. 2016

Background Computer-assisted surgery (CAS) for cup placement has been developed to improve the functional results and to reduce the dislocation rate and wear after total hip arthroplasty (THA). Previously published studies demonstrated radiographic benefits of CAS in terms of implant position, but whether these improvements result in clinically important differences that patients might perceive remains largely unknown.Questions/purposes We hypothesized that THA performed with CAS would improve 10-year patient-reported outcomes measured by validated scoring tools, reduce acetabular polyethylene wear as measured using a validated radiological method, and increase survivorship. Methods Sixty patients operated on for a THA between April 2004 and April 2005 were randomized into two groups using either the CAS technique or a conventional technique for cup placement. All patient candidates for a THA with the diagnosis of primary arthritis or avascular necrosis were eligible for the CAS procedure and randomly assigned to the CAS group by the Hospital Informatics Department with use of a systematic sampling method. The patients assigned to the freehand cup placement group were matched for sex, age within 5 years, pathological condition, operatively treated side, and body mass index within 3 points. All patients were operated on through an anterolateral approach (patient in the supine position) using cementless implants. In the CAS group, a specific surgical procedure using an imageless cup positioning computerbased navigation system was performed. There were 16 men and 14 women in each group; mean age was 62 years (range, 24-80 years), and mean body mass index was 25 ± 3 kg/m 2 . No patient was lost to followup at 10 years, but five patients have died (two in the CAS group and three in the control group). At the 10-year followup, an independent observer blinded to the type of technique performed patients' evaluation. Cup positioning was evaluated postoperatively using a CT scan in the two groups with results previously published. At 10 years, we assessed subjective functional outcome and quality of life using validated questionnaires (SF-12, Harris hip score [HHS], Hip injury and Osteoarthritis Outcome Score). Wear rate was then evaluated on standardized radiographs using a previously validated semiautomated computer analogic measurement Each author certifies that he, or a member of his immediate family, has no funding or commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research 1 editors and board members are on file with the publication and can be viewed on request. Clinical Orthopaedics and Related Research 1 neither advocates nor endorses the use of any treatment, drug, or device. Readers are encouraged to always seek additional information, including FDAapproval status, of any dr...

“…Extremes of component malpositioning are associated with an increased risk of dislocation and loosening [8,11,16,18,20,42,46]. 3D modeling and late implant retrievals have suggested even more subtle malpositioning is associated with edge impingement [3, 4, 22, 31-34, 45, 47].…”

Section: Introductionmentioning

confidence: 99%

Six Sigma Analysis of Minimally Invasive Acetabular Arthroplasty: A Preliminary Investigation

Heck¹,

Stiehl

2009

Minimally invasive techniques in THA may increase the difficulty of acetabular component insertion relative to the optimized position. We sought to determine the ability of eight surgeons to position an acetabular component placed using an anterior-lateral minimally invasive surgical (MIS) approach with conventional instruments or computer navigation using an optical imageless protocol compared with conventional true values determined by computed tomography (CT). We introduce a new approach, the Six Sigma process capability index, to assess outliers. Using the Six Sigma process capability index (Cp [ 1.3) and the criteria of Lewinnek et al. of ± 10°for adequate precision, three-dimensional (3D) CT was capable for inclination and anteversion. Computer navigation and visual cues with conventional instrumentation were precise for anteversion but not for inclination. We conclude image-free computer navigation was not better than conventional instrumentation with the surgeons' visual cues for acetabular cup placement. Six Sigma analysis allows comparison of various methods of referencing with literature controls, and our data suggest CT referencing is the most precise method.