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Poor accuracy of freehand cup positioning during total hip arthroplasty

Poor accuracy of freehand cup positioning during total hip arthroplasty,10.1007/s00402-007-0294-y,Archives of Orthopaedic and Trauma Surgery,B. H. Bos

Poor accuracy of freehand cup positioning during total hip arthroplasty   (Citations: 12)
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Several studies have demonstrated a correlation between the acetabular cup position and the risk of dislocation, wear and range of motion after total hip arthroplasty. The present study was designed to evaluate the accuracy of the surgeon’s estimated position of the cup after freehand placement in total hip replacement. Peroperative estimated abduction and anteversion of 200 acetabular components (placed by three orthopaedic surgeons and nine residents) were compared with measured outcomes (according to Pradhan) on postoperative radiographs. Cups were placed in 49.7° (SD 6.7) of abduction and 16.0° (SD 8.1) of anteversion. Estimation of placement was 46.3° (SD 4.3) of abduction and 14.6° (SD 5.9) of anteversion. Of more interest is the fact that for the orthopaedic surgeons the mean inaccuracy of estimation was 4.1° (SD 3.9) for abduction and 5.2° (SD 4.5) for anteversion and for their residents this was respectively, 6.3° (SD 4.6) and 5.7° (SD 5.0). Significant differences were found between orthopaedic surgeons and residents for inaccuracy of estimation for abduction, not for anteversion. Body mass index, sex, (un)cemented fixation and surgical approach (anterolateral or posterolateral) were not significant factors. Based upon the inaccuracy of estimation, the group’s chance on future cup placement within Lewinnek’s safe zone (5–25° anteversion and 30–50° abduction) is 82.7 and 85.2% for anteversion and abduction separately. When both parameters are combined, the chance of accurate placement is only 70.5%. The chance of placement of the acetabular component within 5° of an intended position, for both abduction and anteversion is 21.5% this percentage decreases to just 2.9% when the tolerated error is 1°. There is a tendency to underestimate both abduction and anteversion. Orthopaedic surgeons are superior to their residents in estimating abduction of the acetabular component. The results of this study indicate that freehand placement of the acetabular component is not a reliable method.
Journal: Archives of Orthopaedic and Trauma Surgery - ARCH ORTHOP TRAUM SURG , vol. 127, no. 5, pp. 375-379, 2007
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    • ...Surgical factors influencing these risks include performing surgeon experience [5, 47], surgical approach [2, 9, 13, 28, 34, 47], prosthetic components [3, 18, 20, 22, 33, 35, 47], acetabular cup fixation method [10], and orientation of the acetabular cup [22, 33, 47]...
    • ...In a prospective analysis of 200 cups, orthopaedic surgeons and residents were asked to hit goal targets for abduction and version angles [5]...
    • ...Variables included in the analysis but not linked to inaccurate estimation were BMI, gender, operated side, acetabular fixation method, cup model, and surgical approach [5]...
    • ...While the effects of cup positioning on complications are well understood, a comprehensive analysis of patient and surgical factors contributing to poor implant positioning is lacking, with the exception of the study by Bosker et al. [5], which is limited by its relatively small sample size...
    • ...The literature inconsistently reports acceptable angle ranges for optimally positioned cups, and the percentage of acceptably placed cups in both abduction and version using the most widely used acceptable range (the Lewinnek range [26]) varies from 70.5% [5] to 25.7% [48]...
    • ...We found a similar percentage of acetabular cups within the ranges for abduction (62%) and version (79%) alone compared to the most accurate study in the literature with 85% and 83% optimally positioned in abduction and version respectively [5]...
    • ...This is in direct contrast to two previously published studies [5, 36] which show no link between surgical approach and cup positioning...
    • ...Three previous studies examined the effect of surgical volume and experience on cup positioning, two of which reported no affect of surgical experience [24, 45] while one found a substantial difference between surgeons compared to their residents [5]...
    • ...Two of these studies were limited by a small sample size [5, 36], and the third examined only surgeon qualifications, implanted model, and side [24]...
    • ...A previously mentioned study of acetabular cup placement by orthopaedic surgeons and residents found a difference between intended and actual angles for abduction but not for version [5]...
    • ...This contradicts three previous studies indicating no relationship between cup position and BMI, but those studies were also limited by their small sample size [5, 44, 53]...

    Mark C. Callananet al. The John Charnley Award: Risk Factors for Cup Malpositioning: Quality ...

    • ...Bosker et al. [4] Manual (orthopaedic surgeons) 19.7% 85 Radiograph 4.1 (standard deviation [SD], 3.9) 5.1 (SD, 4.5)...
    • ...According to previous reports [4, 6, 12, 22, 25, 26], 19.7% to 83.8% of the cases with conventional THAs did not achieve a range within 10 from the planned alignment of the cup...
    • ...Compared with previous reports, the surgical guide is superior to conventional techniques and comparable to navigation systems (0%‐25.3%) [4, 6, 11, 12, 22, 25, 26] (Table 2)...
    • ...Compared with previous reports regarding alignment accuracy of cup placement, our results with the conventional technique are comparable to those of previous conventional technique groups, which are reported as 4.1 to 6.3 for abduction and 5.1 to 13.0 for anteversion [4, 12] (Table 2). Our data using the surgical guide are superior to those of previous conventional technique groups and comparable to previous navigation technique groups, ...

    Takehito Hananouchiet al. Tailor-made Surgical Guide Reduces Incidence of Outliers of Cup Placem...

    • ...Bosker et al. [23] evaluated 200 acetabular components positioning with postoperative radiographs inserted by experienced surgeons as well as trainees...

    M. Ajith Kumaret al. Validation of navigation assisted cup placement in total hip arthropla...

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