Skip to main content
NCBI home page
Acta Orthopaedica logoLink to Acta Orthopaedica
. 2009 Oct 1;80(5):538–544. doi: 10.3109/17453670903350073

Navigated cup implantation in hip arthroplasty

A meta-analysis

Johannes Beckmann 1,✉, Dirk Stengel 2, Markus Tingart 1, Jürgen Götz 1, Joachim Grifka 1, Christian Lüring 1
PMCID: PMC2823338  PMID: 19916685

Abstract

Background and purpose Many studies have suggested that navigation-based implantation can improve cup positioning in total hip arthroplasty (THA). We conducted a systematic review and meta-analysis to compile the best available evidence, and to overcome potential shortcomings because of small sample sizes in individual studies.

Methods The search strategy covered the major medical databases from January 1976 through August 2007, as well as various publishers' databases. The internal validity of individual studies was evaluated independently by 3 reviewers. We used random-effects modeling to obtain mean differences in cup angulation and relative risk (RR) of cup positioning outside Lewinnek's safe zone.

Results Of 363 citations originally identified, 5 trials of moderate methodology enrolling a total of 400 patients were included in the analysis. Mean cup inclination and anteversion were not statistically significantly different between the conventional groups and the navigated groups. Navigation reduced the variability in cup positioning and the risk of placing the acetabular component beyond the safe zone (RR = 0.21, CI: 0.13–0.32).

Interpretation Based on the current literature, navigation is a reliable tool to optimize cup placement, and to minimize outliers. However, long-term outcomes and cost utility analyses are needed before conclusive statements can be drawn about the value of routine navigation in THA.

Introduction

The work flow in operating rooms worldwide has been markedly influenced by computer-assisted surgery (CAS) (Stindel et al. 2007). About 10 years after its introduction, many applications are available for orthopedic and trauma procedures (Jenny 2006, Holly and Foley 2007, Stindel et al. 2007). CAS has gained acceptance, especially for arthroplasty of the knee and hip (Amiot and Poulin 2004, Stindel et al. 2007, Bauwens et al. 2007). There are 3 types of imaging systems used to simultaneously generate different planes of the target object, all of which need intraoperative registration of anatomical landmarks (Sikorski and Chauhan 2003). Either CT-based, fluoroscopically-assisted, or imageless methods are used to simultaneously generate different planes of the therapeutic object to be treated (Grutzner et al. 2004, Widmer and Grutzner 2004, Ottersbach and Haaker 2005, Honl et al. 2006, Kalteis et al. 2006a).

Recent studies have shown that even experienced surgeons often fail to place the acetabular component within Lewinnek's “safe zone” (i.e. inclination of 40° ± 10°, anteversion of 15° ± 10°) (Lewinnek et al. 1978) when using a freehand technique (Saxler et al. 2004a, Tannast et al. 2005a, Honl et al. 2006, Kalteis et al. 2006a, Bosker et al. 2007, Leichtle et al. 2007).

On the other hand, preliminary results from laboratory studies, larger case series, and multicenter experience suggest that navigation-based implantation improves cup positioning in THA (Saxler et al. 2004b, Honl et al. 2006, Minoda et al. 2006, Kalteis et al. 2006a, Leichtle et al. 2007, Parratte and Argenson 2007, Sugano et al. 2007). However, conflicting statements and suspected methodological limitations in an arbitrary sample of the studies that we reviewed led us to conduct a systematic review of the international literature on navigated THA with emphasis on cup orientation.

We wanted to compile the current best evidence by pooling all RCT and quasi-RCT studies of comparisons between navigated and conventional cup positioning in THA, and to examine whether they support the assumption of better radiographic and clinical results with navigation.

Methods

We identified all investigations that (1) compared navigation-based THA and conventional THA with emphasis on cup implantation, regardless of the underlying condition, disease, or navigation system (ITT), and that (2) met a level of evidence of II or higher, according to the suggestions of the Oxford Center for Evidence-Based Medicine (i.e. prospective cohort study, low-quality RCT, quasi-RCT, and individual RCT). We made no restrictions about language.

Study designs representing a lower level of evidence, especially retrospective cohort studies, were excluded from the analysis. We reasoned that only experimental and quasi-experimental designs minimize the risk of confounding, and allow valid estimates of the efficacy of navigation.

Our search strategy covered all major medical databases (Medline, Embase, SciSearch, Cinahl, and the Cochrane Central Register of Trials) from January 1976 through August 2007.

We used the following medical subject headings, or their equivalents: ‘position*’, ‘orient*’, ‘inclin*’, ‘anteversion’, ‘dislocation’, ‘luxation’, ‘wear’, ‘loosening’, ‘computer assisted’, ‘computer based’, ‘imageless’, ‘image based’, ‘CT-based’, ‘navig*’, ‘CAOS’, ‘CAS’, each in combination with ‘hip’, ‘cup’, ‘arthroplasty’, ‘THA’ ‘prospective’, ‘meta’, ‘review’ and ‘random*’. We also scanned publishers’ databases and conducted manual searches in the Journal of Bone and Joint Surgery (American and British Volumes, including supplements), Clinical Orthopaedics and Related Research, Journal of Arthroplasty, and Acta Orthopaedica. The bibliographies of the papers identified were searched for additional relevant citations. Potentially eligible studies were selected by taking the title and abstract. If the title and the abstract were inadequate to reach a final decision, we obtained the full paper.

The internal validity of individual studies was evaluated independently by 3 reviewers (JB, CL, and DS). We assessed the following methodological issues: (1) Did the authors put forward a clear study hypothesis? (2) Did they perform a sample-size calculation? (3) Did they report their results according to the CONSORT statement (including an illustration of the flow)? (4) did they respect the intention-to-treat principle (e.g. were patients who had been assigned to navigated THA still analyzed as navigated if the system had failed? (5) Did they provide sufficient numerical information in order to be able to recalculate the results reported?

To test the hypothesis that cup placement in THA is more precise with navigation (compared to the conventional technique), we focused on the inclination and anteversion of the cup as target criteria. We also used criteria according to Lewinnek's ‘safe zone’ to investigate this hypothesis.

Statistics

We abstracted and tabulated baseline details of patients enrolled in individual studies, where available (e.g. age, sex, underlying condition). Weighted means and weighted mean differences in inclination and anteversion between navigated and conventional cup placement were calculated with their 95% confidence intervals (CIs). We also computed the risk ratio (RR) of cup placement outside Lewinnek's ‘safe zone’. Heterogeneity was assessed with chi-square statistics. A p-value of < 0.1 was considered suggestive of statistical heterogeneity, prompting random effects modeling.

We attempted to measure publication bias—that is, a lack of small studies without significant results—by the linear regression test for funnel plot asymmetry described by Egger et al. (1997). However, because of the small sample of eligible studies, this was meaningless. Also, the sample size prohibited random-effects meta-regression to adjust common effect estimates for potential confounders.

All analyses were performed in an exploratory fashion. We used the STATA statistical software package version 10.0 (StataCorp, College Station, TX) for all analyses.

Results

Search results

Our search strategy revealed 363 citations, 326 of which were excluded after scanning the title and the abstract. 37 clinical reports were considered potentially eligible for this meta-analysis and were retrieved as full text. The study flow according to the QUOROM (Quality of Reporting Meta-Analyses) is depicted in Figure 1. Identified and excluded studies are listed in Tables 1 and 3 (See Appendix).

Figure 1.

Figure 1.

Open in a new tab

Study selection process according to QUOROM (Quality of Reporting of Meta-Analyses) standards.

Table 1.

Demographic baseline data

Author Year Conventional Navigation
n Mean age, years (SD) No. of male patients Primary OA n Mean age, years (SD) No. of male patients Primary OA
– : not specified.
Leenders 2002 50 65 (–) 21 38 50 61 (–) 21 40
Stipcak 2004 25 57 (8) 13 20 25 54 (11) 19 20
Ottersbach 2005 50 60 (12) 22 – 50 59 (13) 27 –
Kalteis 2006a 30 65 (9) 13 30 60 64 (9) 30 60
Paratte 2007 30 63 (10) 16 26 30 61 (13) 16 27
Open in a new tab

The selection procedure left 5 eligible studies involving 400 enrolled patients (198 men, 202 women) with a mean age of 61 (SD 25) years. Of these, 2 studies were published in English, 2 in German, and 1 was published in the Czech language. 4 studies specified the underlying etiology of the osteoarthritis (OA), with 261/300 replacements (87%) performed because of primary OA. Patient samples were well balanced with regard to the basic demographic items available (Table 1).

One trial (Parratte and Argenson 2007) was published twice, in French and English. We included only the English paper. The authors’ line, IRB reference number, recruitment period, and number of subjects noted in another paper was suggestive of continued work (Kalteis et al. 2005, Kalteis et al. 2006a). We only included the most recent study in our analysis, which was a three-arm trial (CT-based navigation versus imageless-navigation versus conventional cup positioning). Since both navigation methods showed similar trends compared to conventional surgery—proportion of cups outside the safe zone: CT-based 5/30 (0.2, CI: 0.1–0.4), imageless 2/30 (0.1, CI: 0.1 – 0.2), freehand 16/30 [0.5, CI: 0.3–0.7)—results of the computer-assisted procedures were merged to facilitate analysis and to increase power.

Altogether, the methodological quality was moderate (Table 2). 1 trial indexed as RCT was, in fact, a matched-pair analysis in which “the first patient was randomly chosen and then one patient was selected out of every eight patients on a list of all patients meeting the inclusion criteria who were candidates for a THA. The patients assigned to the freehand cup placement group were matched for gender, age within five years, pathological condition, operatively treated side, and body-mass index within 3 points.” (Leenders et al. 2002). They mixed a cohort design with an RCT. The authors reported on 50 patients undergoing THA at their department prior to the establishment of a navigation system. Another 100 patients were randomly allocated to either CAS or conventional surgery. Of note, while the precision in cup positioning improved over time, there was no difference between navigated and freehand cup placement in the RCT part of the study. We only included the results from randomly assigned patients. The reasoning for the target sample size was reported in a single paper (Kalteis et al. 2006a). None fulfilled the ITT principle or represented a consort flow diagram. Studies provided no detailed information on complication rates, length of hospital stay, functional scoring, and other clinically relevant outcomes, or on costs or cost utility.

Table 2.

Studies included in the meta-analysis, with details of methodology

Author Year Cup Navigation system IRB approval Clear hypothesis Sample size calculation Randomization procedure ITT analysis CONSORT flow diagram
– : not specified; IRB: institutional review board; ITT: intention-to-treat; CONSORT: Consolidated Standards of Reporting Trials; RCT: randomized controlled trial.
Kalteis 2006 Press-fit (Pinnacle, DePuy, Warsaw, IN) VectorVision hip 3.0 system (BrainLAB, Heimstetten, Germany) yes yes yes “by lot” no no
Paratte 2007 Press-fit (Hilock, Symbios, Yverdon, Switzerland) Praxim Medivision, Grenoble, France yes yes – Indexed as RCT; actually matched pair design no no
Stipcak 2004 Press-fit (Plasma- cup, Aesculap, Nemêcko, Czech Republic) OrthoPilot (B. Braun Aesculap) – yes – – no no
Ottersbach 2005 Press-fit Plasma-cup (n = 91), cemented PE (n = 9) OrthoPilot (B. Braun Aesculap) – – – “by random ” no principle no
Leenders 2002 Uncemented, metal-backed cup Surgi-Gate, Medivision, Oberdorf, Switzerland – yes – Indexed as RCT; actually mixed cohort study and RCT no no
Open in a new tab

Treatment results

Cup inclination averaged 44° (CI: 40 – 48) in the conventional arm and 43° (CI: 40 – 46) in the navigation arm. The weighted mean difference in inclination between conventional and computer-assisted positioning was not statistically significant (–0.89°, CI: -4.2–2.4) (Figure 2). Means from Leenders' trial had to be derived from a histogram. When excluding this trial from random-effects pooling, the mean difference between groups was –0.30° (CI: -0.83–0.22). Cup anteversion averaged 17° (CI: 11–22) in the conventional arm and 15° (CI: 11–18) in the navigation arm. Again, this difference was compatible with chance (Figure 3).

Figure 2.

Figure 2.

Open in a new tab

Forest plot showing that there was no statistically significant difference in mean inclination of cups placed with and without navigational support. Mean effect sizes of individual studies are expressed as squares, with larger squares denoting larger sample sizes, higher precision, and higher relative weight within the meta-analysis. Values lower than zero favor navigation and values higher than zero favor conventional cup positioning. The diamond shows the pooled overall effect size with the 95% confidence interval. When the 95% confidence interval includes the zero, it can be assumed that there is no statistical significance at the two-tailed p < 0.05 level.

Figure 3.

Figure 3.

Open in a new tab

Forest plot showing that there was no statistically significant difference in mean anteversion of cups placed with and without navigational support. No information on anteversion was available in the trial by Leenders et al. (Leenders et al. 2002).

Overall, navigation reduced the variability in cup positioning statistically significantly, and reduced the risk of placing the acetabular component beyond the safe zone (Figure 4). The pooled RR of 0.21 (CI: 0.13–0.32) translates to a risk difference of 37% (CI: 45–29) in favor of navigation.

Figure 4.

Figure 4.

Open in a new tab

Forest plot showing the statistically significantly reduced relative risk of cup positioning outside the safe zone with navigation.

Discussion

Correct cup positioning is crucial for the short- and long-term success of THA. Many studies have suggested that there is improved cup positioning with navigation-based implantation (Saxler et al. 2004a, Honl et al. 2006, Kalteis et al. 2006a, Leichtle et al. 2007, Parratte and Argenson 2007). However, individual studies are too small to allow conclusive statements on the potential benefit of navigation in THA.

Our meta-analysis demonstrates a clear advantage of navigated cup orientation over conventional freehand cup orientation in THA. As discussed later, however, various severe pitfalls and possible inherent error or bias must be considered. As with total knee arthroplasty and screw positioning in spinal surgery, the major benefit of navigation is the reduction of outliers, that is, cup positioning beyond the “safe zone” with an inclination of 40° (± 10°) and anteversion of 15° (± 10°) (Saxler et al. 2004a, Honl et al. 2006, Kalteis et al. 2006a, Minoda et al. 2006, Leichtle et al. 2007, Parratte and Argenson 2007, Sugano et al. 2007). Moreover, it seems that navigation-based cup positioning in THA meets the criteria of evidence by reducing the amount of outliers in cup orientation (Leenders et al. 2002, Stipcak et al. 2004, Ottersbach and Haaker 2005, Kalteis et al. 2006a, Parratte and Argenson 2007).

The findings from experimental and quasi-experimental investigations are supported by those from observational studies that were excluded from the present meta-analysis. Sugano et al. (2007) found none of 59 navigated cups as compared to 31 of 111 conventional implanted cups to be outside the “safe zone” (p < 0.001). There was no significant difference in mean inclination, but a significantly greater mean anteversion with conventional cup placement (p < 0.001). In a multicenter study, a significantly higher variability in both inclination and anteversion (p < 0.001) was found after conventional cup implantation (Saxler et al. 2004a).

In a minimally invasive THA study, significant variances in both inclination (p < 0.01) and anteversion (p < 0.03) were reported (Wixson and MacDonald 2005). In retrospective studies, a statistically significant difference in variation for both inclination and anteversion has been found (Haaker et al. 2007), and also an advantage in navigation-based cup placement in dysplastic hips (Haaker et al. 2003).

The reduction of outliers is of clinical relevance, as malpositioning of the acetabular component may cause impingement and restrict the range of motion. It is a known risk factor for dislocation and can lead to increased and premature wear, with elevated metal-ion concentrations in serum and an overall increased risk of loosening and revision (Patil et al. 2003, Brodner et al. 2004, Nishii et al. 2004).

The proven advantages of navigation must be traded off against the argument of prolonged surgery and higher costs (Eingartner 2007).

The number of studies, patients, and outcome data is still limited, and we also noted some weaknesses in trial methodology, which highlights various pitfalls and possible inherent error or bias that warrant further discussion. First, there was no clear evidence of publication error, and it is likely that the published information reflects the best results currently achievable with navigated cup positioning in THA. Future trials must adhere to methodological standards such as proper random assignment and intention-to-treat analyses, and aim for a thorough comparison of radiographic and functional results, complication and survival rates, quality of life, and also extra costs and cost utility.

Secondly, one uncertainty and limitation of evidence is the status of current discussion about the correct incorporation of the pelvic anatomy (Beckmann et al. 2008) regarding the generation of landmarks as a basis for imageless navigation (Lembeck et al. 2005, Richolt et al. 2005, Stiehl et al. 2005, Wolf et al. 2005, Mayr et al. 2006, Spencer et al. 2006, Beckmann et al. 2008) and the correct radiological assessment of the implant position (Olivecrona et al. 2004, Blendea et al. 2005, Tannast et al. 2005b, Jaramaz and Eckman 2006, Kalteis et al. 2006b, Liaw et al. 2006, Marx et al. 2006, Muller et al. 2006, Penney et al. 2007, Beckmann et al. 2008).

Thirdly, apart from cup orientation, outcomes such as longevity, range of motion, impingement, and dislocation further depend on the head-neck ratio, the offset, and the stem orientation (D'Lima et al. 2000, Widmer and Zurfluh 2004, Pedersen et al. 2005, Widmer and Majewski 2005, Masaoka et al. 2006, Yoshimine 2006, Malik et al. 2007, Widmer 2007). In addition, the surgical approach and endogenous factors such as comorbidity and muscular status may contribute to the fate of the hip joint (Soong et al. 2004, Zwartele et al. 2004, Meek et al. 2006).

Lastly, although we took care not to miss any relevant publication, we did not ask the authors for individual patient data or ongoing studies. Occasionally, editing of manuscripts and limited space in scientific journals may obscure some methodological features originally respected by study protocols.

In conclusion, based on the current literature, navigation is a reliable tool for optimization of cup placement in THA. Navigation reduces the incidence of outliers beyond the so-called desired “safe zone”. Long-term outcomes have to be awaited before making final statements about longevity of the prosthesis and patient satisfaction, which depend on factors other than just cup orientation. A corresponding cost utility analysis must also be done.

Acknowledgements

JB and CL initiated the study and contributed to all parts of the manuscript. DS, MT, and JüG did the statistical analyses and proofreading. JoG supervised the study as head of the department.

No competing interests declared.

APPENDIX

Table 3.

Excluded studies

Author Year Journal Level of evidence Study description
Zheng 2002 Comput Aided Surg V mechanistic study, imageless navigation for cup positioning
Amiot 2004 Clin Orthop V cadaver study with repeated measurements of navigated cup positioning
Jolles 2004 Clin Orthop V mechanistic study, freehand vs. computer-assisted cup positioning
Kalteis 2004 Biomed Tech (Berl) V cadaver study of imageless navigation (VectorVision) for cup positioning
Nogler 2004 Clin Orthop V cadaver study, freehand vs. imageless navigation
Honl 2005 J Bone Joint Surg (Br) V mechanistic study of five different navigation systems (imageless and CT-based Navitrack, OrthoPilot, Surgetics Station, VectorVision) for cup positioning
Stiehl 2005 Comput Aided Surg V cadaver study, fluoroscopy-based navigated cup positioning
Tannast 2005 Comput Aided Surg V cadaver study, fluoroscopy-based navigated cup positioning
Belei 2007 Comput Aided Surg V cadaver study of navigated surface replacement
Cobb 2007 Clin Orthop V navigated cup positioning in sawbones
DiGoia 1998 Clin Orthop IV CT-based navigated cup positioning
Bernsmann 2001 Z Orthop Ihre Grenzgeb IV different cups and techniques influencing navigated cup positioning (Medivision, Optotrack)
DiGoia 2002 J Arthroplasty IV mechanical acetabular alignment guide for cup positioning
Hube 2003 Surg Technol Int IV CT-based and fluoroscopy-based systems for navigated cup positioning
Kiefer 2003 Int Orthop IV imageless navigation (OrthoPilot) for cup positioning
von Recum 2003 Unfallchirurg IV CT-free navigation (SurgiGate) for cup positioning
Wentzensen 2003 Int Orthop IV CT-free navigation (SurgiGate) for cup positioning
Grützner 2004 Injury IV imageless navigated cup postioning
Widmer 2004 Injury IV CT-based navigation for cup positioning
Dorr 2005 Iowa Orthop J IV imageless navigated cup postioning
Laffargue 2006 Rev Chir Orthop R A M IV imageless navigation for cup positioning
Blendea 2007 Comput Aided Surg IV + V cadaver and clinical studies of navigated cup positioning
Bosker 2007 Arch Orthop Trauma Surg IV freehand cup positioning - clinical estimation vs. radiological measurement
Dorr 2007 Clin Orthop IV clinical estimation vs. navigation accuracy, influence of the surgeon's experience on cup positioning
Haaker 2003 Z Orthop Ihre Grenzgeb III dysplastic hips, freehand vs. imageless navigation (SurgiGate) for cup positioning
Saxler 2004 Z Orthop Ihre Grenzgeb III freehand vs. imageless navigated (SurgiGate) cup positioning
Wixson 2005 J Arthroplasty III imageless navigated vs. freehand cup positioning
Saxler 2004 Int Orthop III freehand vs. imageless navigated (SurgiGate) cup positioning
Stipcak 2006 Acta Chir Orthop Traumatol Cech III freehand vs. imageless navigated (OrthoPilot) cup positioning with a minimally-invasive posterolateral approach
Haaker 2007 J Arthroplasty III retrospective, CT-based navigated vs. freehand cup positioning
Sugano 2007 J Bone Joint Surg (Br) III freehand vs. CT-based navigated cup positioning
Open in a new tab

References

  1. Amiot LP, Poulin F. Computed tomography-based navigation for hip, knee, and spine surgery. Clin Orthop. 2004;((421)):77–86. doi: 10.1097/01.blo.0000126866.29933.42. [DOI] [PubMed] [Google Scholar]
  2. Bauwens K, Matthes G, Wich M, Gebhard F, Hanson B, Ekkernkamp A, Stengel D. Navigated total knee replacement. A meta-analysis. J Bone Joint Surg (Am) 2007;89:261–9. doi: 10.2106/JBJS.F.00601. [DOI] [PubMed] [Google Scholar]
  3. Beckmann J, Luring C, Tingart M, Anders S, Grifka J, Kock FX. Cup positioning in THA: current status and pitfalls. A systematic evaluation of the literature. Arch Orthop Trauma Surg. 2008;129:863–72. doi: 10.1007/s00402-008-0686-7. [DOI] [PubMed] [Google Scholar]
  4. Bernsmann K, Langlotz U, Ansari B, Wiese M. Computer-assisted navigated cup placement of different cup types in hip arthroplasty—a randomised controlled trial. Z Orthop Ihre Grenzgeb. 2001;139:512–7. doi: 10.1055/s-2001-19233. [DOI] [PubMed] [Google Scholar]
  5. Blendea S, Eckman K, Jaramaz B, Levison TJ, Digioia AM., III Measurements of acetabular cup position and pelvic spatial orientation after total hip arthroplasty using computed tomography/radiography matching. Comput Aided Surg. 2005;10:37–43. doi: 10.3109/10929080500178032. [DOI] [PubMed] [Google Scholar]
  6. Bosker BH, Verheyen CC, Horstmann WG, Tulp NJ. Poor accuracy of freehand cup positioning during total hip arthroplasty. Arch Orthop Trauma Surg. 2007;127:375–9. doi: 10.1007/s00402-007-0294-y. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Brodner W, Grubl A, Jankovsky R, Meisinger V, Lehr S, Gottsauner-Wolf F. Cup inclination and serum concentration of cobalt and chromium after metal-on-metal total hip arthroplasty. J Arthroplasty. 2004;19:66–70. doi: 10.1016/j.arth.2004.09.003. [DOI] [PubMed] [Google Scholar]
  8. D'Lima DD, Urquhart AG, Buehler KO, Walker RH, Colwell CW., Jr The effect of the orientation of the acetabular and femoral components on the range of motion of the hip at different head-neck ratios. J Bone Joint Surg (Am) 2000;82:315–21. doi: 10.2106/00004623-200003000-00003. [DOI] [PubMed] [Google Scholar]
  9. Egger M, Davey SG, Schneider M, Minder C. Bias in meta-analysis detected by a simple. graphical test. BMJ. 1997;315:629–34. doi: 10.1136/bmj.315.7109.629. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Eingartner C. Current trends in total hip arthroplasty. Ortop Traumatol Rehabil. 2007;9:8–14. [PubMed] [Google Scholar]
  11. Grutzner PA, Zheng G, Langlotz U, von RJ, Nolte LP, Wentzensen A, Widmer KH, Wendl K. C-arm based navigation in total hip arthroplasty-background and clinical experience. Injury (Suppl 1) 2004;35:S-5. doi: 10.1016/j.injury.2004.05.016. [DOI] [PubMed] [Google Scholar]
  12. Haaker R, Tiedjen K, Rubenthaler F, Stockheim M. [Computer-assisted navigated cup placement in primary and secondary dysplastic hips]. Z Orthop Ihre Grenzgeb. 2003;141:105–11. doi: 10.1055/s-2003-37306. [DOI] [PubMed] [Google Scholar]
  13. Haaker RG, Tiedjen K, Ottersbach A, Rubenthaler F, Stockheim M, Stiehl JB. Comparison of conventional versus computer-navigated acetabular component insertion. J Arthroplasty. 2007;2:151–9. doi: 10.1016/j.arth.2005.10.018. [DOI] [PubMed] [Google Scholar]
  14. Holly LT, Foley KT. Image guidance in spine surgery. Orthop Clin North Am. 2007;38:451–61. doi: 10.1016/j.ocl.2007.04.001. [DOI] [PubMed] [Google Scholar]
  15. Honl M, Schwieger K, Salineros M, Jacobs J, Morlock M, Wimmer M. Orientation of the acetabular component. A comparison of five navigation systems with conventional surgical technique. J Bone Joint Surg (Br) 2006;88:1401–5. doi: 10.1302/0301-620X.88B10.17587. [DOI] [PubMed] [Google Scholar]
  16. Jaramaz B, Eckman K. 2D/3D registration for measurement of implant alignment after total hip replacement. Med Image Comput Comput Assist Interv Int Conf Med Image Comput Comput Assist Interv. 2006;9:653–61. doi: 10.1007/11866763_80. [DOI] [PubMed] [Google Scholar]
  17. Jenny JY. The history and development of computer assisted orthopaedic surgery. Orthopade. 2006;35:1038–42. doi: 10.1007/s00132-006-0994-y. [DOI] [PubMed] [Google Scholar]
  18. Kalteis T, Handel M, Herold T, Perlick L, Baethis H, Grifka J. Greater accuracy in positioning of the acetabular cup by using an image-free navigation system. Int Orthop. 2005;29:272–6. doi: 10.1007/s00264-005-0671-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Kalteis T, Handel M, Bathis H, Perlick L, Tingart M, Grifka J. Imageless navigation for insertion of the acetabular component in total hip arthroplasty: is it as accurate as CT-based navigation? J Bone Joint Surg (Br) 2006a;88:163–7. doi: 10.1302/0301-620X.88B2.17163. [DOI] [PubMed] [Google Scholar]
  20. Kalteis T, Handel M, Herold T, Perlick L, Paetzel C, Grifka J. Position of the acetabular cup—accuracy of radiographic calculation compared to CT-based measurement. Eur J Radiol. 2006b;58:294–300. doi: 10.1016/j.ejrad.2005.10.003. [DOI] [PubMed] [Google Scholar]
  21. Leenders T, Vandevelde D, Mahieu G, Nuyts R. Reduction in variability of acetabular cup abduction using computer assisted surgery: a prospective and randomized study. Comput Aided Surg. 2002;7:99–106. doi: 10.1002/igs.10033. [DOI] [PubMed] [Google Scholar]
  22. Leichtle U, Gosselke N, Wirth CJ, Rudert M. Radiologic evaluation of cup placement variation in conventional total hip arthroplasty. Rofo. 2007;179:46–52. doi: 10.1055/s-2006-927085. [DOI] [PubMed] [Google Scholar]
  23. Lembeck B, Mueller O, Reize P, Wuelker N. Pelvic tilt makes acetabular cup navigation inaccurate. Acta Orthop. 2005;76:517–23. doi: 10.1080/17453670510041501. [DOI] [PubMed] [Google Scholar]
  24. Lewinnek GE, Lewis JL, Tarr R, Compere CL, Zimmerman JR. Dislocations after total hip-replacement arthroplasties. J Bone Joint Surg (Am) 1978;60:217–20. [PubMed] [Google Scholar]
  25. Liaw CK, Hou SM, Yang RS, Wu TY, Fuh CS. A new tool for measuring cup orientation in total hip arthroplasties from plain radiographs. Clin Orthop. 2006;((451)):134–9. doi: 10.1097/01.blo.0000223988.41776.fa. [DOI] [PubMed] [Google Scholar]
  26. Malik A, Maheshwari A, Dorr LD. Impingement with total hip replacement. J Bone Joint Surg (Am) 2007;89:1832–42. doi: 10.2106/JBJS.F.01313. [DOI] [PubMed] [Google Scholar]
  27. Marx A, von KM, Pfortner J, Wiese M, Saxler G. Misinterpretation of cup anteversion in total hip arthroplasty using planar radiography. Arch Orthop Trauma Surg. 2006;126:487–92. doi: 10.1007/s00402-006-0163-0. [DOI] [PubMed] [Google Scholar]
  28. Masaoka T, Yamamoto K, Shishido T, Katori Y, Mizoue T, Shirasu H, Nunoda D. Study of hip joint dislocation after total hip arthroplasty. Int Orthop. 2006;30:26–30. doi: 10.1007/s00264-005-0032-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Mayr E, de la Barrera JL, Eller G, Bach C, Nogler M. The effect of fixation and location on the stability of the markers in navigated total hip arthroplasty: a cadaver study. J Bone Joint Surg (Br) 2006;88:168–72. doi: 10.1302/0301-620X.88B2.17257. [DOI] [PubMed] [Google Scholar]
  30. Meek RM, Allan DB, McPhillips G, Kerr L, Howie CR. Epidemiology of dislocation after total hip arthroplasty. Clin Orthop. 2006;((447)):9–18. doi: 10.1097/01.blo.0000218754.12311.4a. [DOI] [PubMed] [Google Scholar]
  31. Minoda Y, Kadowaki T, Kim M. Acetabular component orientation in 834 total hip arthroplasties using a manual technique. Clin Orthop. 2006;((445)):186–91. doi: 10.1097/01.blo.0000201165.82690.f8. [DOI] [PubMed] [Google Scholar]
  32. Muller O, Reize P, Trappmann D, Wulker N. Measuring anatomical acetabular cup orientation with a new X-ray technique. Comput Aided Surg. 2006;11:69–75. doi: 10.3109/10929080600640618. [DOI] [PubMed] [Google Scholar]
  33. Murray DW. The definition and measurement of acetabular orientation. J Bone Joint Surg (Br) 1993;75:228–32. doi: 10.1302/0301-620X.75B2.8444942. [DOI] [PubMed] [Google Scholar]
  34. Nishii T, Sugano N, Miki H, Koyama T, Takao M, Yoshikawa H. Influence of component positions on dislocation: computed tomographic evaluations in a consecutive series of total hip arthroplasty. J Arthroplasty. 2004;19:162–6. doi: 10.1016/j.arth.2003.09.005. [DOI] [PubMed] [Google Scholar]
  35. Olivecrona H, Weidenhielm L, Olivecrona L, Beckman MO, Stark A, Noz ME, Maguire GQ, Jr, Zeleznik MP, Svensson L, Jonson T. A new CT method for measuring cup orientation after total hip arthroplasty: a study of 10 patients. Acta Orthop Scand. 2004;75:252–60. doi: 10.1080/00016470410001169. [DOI] [PubMed] [Google Scholar]
  36. Ottersbach A, Haaker R. Optimization of cup positioning in THA–comparison between conventional mechanical instrumentation and computer-assisted implanted cups by using the orthopilot navigation system. Z Orthop Ihre Grenzgeb. 2005;143:611–5. doi: 10.1055/s-2005-872525. [DOI] [PubMed] [Google Scholar]
  37. Parratte S, Argenson JN. Validation and usefulness of a computer-assisted cup-positioning system in total hip arthroplasty. A prospective, randomized, controlled study. J Bone Joint Surg (Am) 2007;89:494–9. doi: 10.2106/JBJS.F.00529. [DOI] [PubMed] [Google Scholar]
  38. Patil S, Bergula A, Chen PC, Colwell CW, Jr, D'Lima DD. Polyethylene wear and acetabular component orientation. J Bone Joint Surg (Am) (Suppl 4) 2003;85:56–63. doi: 10.2106/00004623-200300004-00007. [DOI] [PubMed] [Google Scholar]
  39. Pedersen DR, Callaghan JJ, Brown TD. Activity-dependence of the “safe zone” for impingement versus dislocation avoidance. Med Eng Phys. 2005;27:323–8. doi: 10.1016/j.medengphy.2004.09.004. [DOI] [PubMed] [Google Scholar]
  40. Penney GP, Edwards PJ, Hipwell JH, Slomczykowski M, Revie I, Hawkes DJ. Postoperative calculation of acetabular cup position using 2-D-3-D registration. IEEE Trans Biomed Eng. 2007;54:1342–8. doi: 10.1109/TBME.2007.890737. [DOI] [PubMed] [Google Scholar]
  41. Pradhan R. Planar anteversion of the acetabular cup as determined from plain anteroposterior radiographs. J Bone Joint Surg Br. 1999;((81)):431–435. doi: 10.1302/0301-620x.81b3.9067. [DOI] [PubMed] [Google Scholar]
  42. Richolt JA, Effenberger H, Rittmeister ME. How does soft tissue distribution affect anteversion accuracy of the palpation procedure in image-free acetabular cup navigation? An ultrasonographic assessment. Comput Aided Surg. 2005;10:87–92. doi: 10.3109/10929080500229447. [DOI] [PubMed] [Google Scholar]
  43. Saxler G, Marx A, Vandevelde D, Langlotz U, Tannast M, Wiese M, Michaelis U, Kemper G, Grutzner PA, Steffen R, von KM, Holland-Letz T, Bernsmann K. [Cup placement in hip replacement surgery–A comparison of free-hand and computer assisted cup placement in total hip arthroplasty –a multi-center study. Z Orthop Ihre Grenzgeb. 2004a;142:286–91. doi: 10.1055/s-2004-822696. [DOI] [PubMed] [Google Scholar]
  44. Saxler G, Marx A, Vandevelde D, Langlotz U, Tannast M, Wiese M, Michaelis U, Kemper G, Grutzner PA, Steffen R, von KM, Holland-Letz T, Bernsmann K. The accuracy of free-hand cup positioning–a CT based measurement of cup placement in 105 total hip arthroplasties. Int Orthop. 2004b;28:198–201. doi: 10.1007/s00264-004-0542-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
  45. Sikorski JM, Chauhan S. Computer-assisted orthopaedic surgery: do we need CAOS? J Bone Joint Surg (Br) 2003;85:319–23. doi: 10.1302/0301-620x.85b3.14212. [DOI] [PubMed] [Google Scholar]
  46. Soong M, Rubash HE, Macaulay W. Dislocation after total hip arthroplasty. J Am Acad Orthop Surg. 2004;12:314–21. doi: 10.5435/00124635-200409000-00006. [DOI] [PubMed] [Google Scholar]
  47. Spencer JM, Day RE, Sloan KE, Beaver RJ. Computer navigation of the acetabular component: a cadaver reliability study. J Bone Joint Surg (Br) 2006;88:972–5. doi: 10.1302/0301-620X.88B7.17468. [DOI] [PubMed] [Google Scholar]
  48. Stiehl JB, Heck DA, Lazzeri M. Accuracy of acetabular component positioning with a fluoroscopically referenced CAOS system. Comput Aided Surg. 2005;10:321–7. doi: 10.3109/10929080500379499. [DOI] [PubMed] [Google Scholar]
  49. Stindel E, Merloz P, Graf P, Massin P, Gruber P, Robert H, Moineau G, Colmar M. Computer assisted orthopedics surgery. Rev Chir Orthop Reparatrice Appar Mot. 2007;93:2S11–2S32. [PubMed] [Google Scholar]
  50. Stipcak V, Stoklas J, Hart R, Janecek M. Implantation of a non-cemented acetabulum with the use of a navigation system. Acta Chir Orthop Traumatol Cech. 2004;71:288–91. [PubMed] [Google Scholar]
  51. Sugano N, Nishii T, Miki H, Yoshikawa H, Sato Y, Tamura S. Mid-term results of cementless total hip replacement using a ceramic-on-ceramic bearing with and without computer navigation. J Bone Joint Surg (Br) 2007;89:455–60. doi: 10.1302/0301-620X.89B4.18458. [DOI] [PubMed] [Google Scholar]
  52. Tannast M, Langlotz F, Kubiak-Langer M, Langlotz U, Siebenrock KA. Accuracy and potential pitfalls of fluoroscopy-guided acetabular cup placement. Comput Aided Surg. 2005a;10:329–36. doi: 10.3109/10929080500379481. [DOI] [PubMed] [Google Scholar]
  53. Tannast M, Langlotz U, Siebenrock KA, Wiese M, Bernsmann K, Langlotz F. Anatomic referencing of cup orientation in total hip arthroplasty. Clin Orthop. 2005b;((436)):144–50. doi: 10.1097/01.blo.0000157657.22894.29. [DOI] [PubMed] [Google Scholar]
  54. Widmer KH. A simplified method to determine acetabular cup anteversion from plain radiographs. J Arthroplasty. 2004;19:387–90. doi: 10.1016/j.arth.2003.10.016. [DOI] [PubMed] [Google Scholar]
  55. Widmer KH. Containment versus impingement: finding a compromise for cup placement in total hip arthroplasty. Int Orthop (Suppl 1) 2007;31:S29–S33. doi: 10.1007/s00264-007-0429-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
  56. Widmer KH, Grutzner PA. Joint replacement-total hip replacement with CT-based navigation. Injury (Suppl 1) 2004;35:S-9. doi: 10.1016/j.injury.2004.05.015. [DOI] [PubMed] [Google Scholar]
  57. Widmer KH, Majewski M. The impact of the CCD-angle on range of motion and cup positioning in total hip arthroplasty. Clin Biomech (Bristol, Avon) 2005;20:723–8. doi: 10.1016/j.clinbiomech.2005.04.003. [DOI] [PubMed] [Google Scholar]
  58. Widmer KH, Zurfluh B. Compliant positioning of total hip components for optimal range of motion. J Orthop Res. 2004;22:815–21. doi: 10.1016/j.orthres.2003.11.001. [DOI] [PubMed] [Google Scholar]
  59. Wixson RL, MacDonald MA. Total hip arthroplasty through a minimal posterior approach using imageless computer-assisted hip navigation. J Arthroplasty. 2005;20:51–6. doi: 10.1016/j.arth.2005.04.024. [DOI] [PubMed] [Google Scholar]
  60. Wolf A, Digioia AM, III, Mor AB, Jaramaz B. Cup alignment error model for total hip arthroplasty. Clin Orthop. 2005;((437)):132–7. doi: 10.1097/01.blo.0000164027.06880.3a. [DOI] [PubMed] [Google Scholar]
  61. Yoshimine F. The safe-zones for combined cup and neck anteversions that fulfill the essential range of motion and their optimum combination in total hip replacements. J Biomech. 2006;39:1315–23. doi: 10.1016/j.jbiomech.2005.03.008. [DOI] [PubMed] [Google Scholar]
  62. Zwartele RE, Brand R, Doets HC. Increased risk of dislocation after primary total hip arthroplasty in inflammatory arthritis: a prospective observational study of 410 hips. Acta Orthop Scand. 2004;75:684–90. doi: 10.1080/00016470410004049. [DOI] [PubMed] [Google Scholar]

Articles from Acta Orthopaedica are provided here courtesy of Nordic Orthopaedic Federation

RESOURCES