Background: Proponents of navigated knee arthroplasty stress its potential to increase the precision of component placement. We conducted a systematic review and meta-analysis to substantiate the validity and relevance of this contention. Methods: We searched major medical and publishers' databases for randomized trials and any other studies comparing navigated with conventional knee arthroplasty. Major periodicals were searched manually. We made no restrictions for types of studies or language. Methodological features were rated independently by two reviewers. After testing for publication bias and heterogeneity was done, the data were aggregated by random-effects modeling. We estimated the weighted mean differences of mechanical limb axes and functional scales and the risk ratios of deviations from the straight axis with 95% confidence intervals. Results: We included thirty-three studies (eleven randomized trials) of varying methodological quality involving 3423 patients with a mean age (and standard deviation) of 67.3 ± 4.1 years (62.6% were women, and 83.7% had primary osteoarthritis). The mean preoperative deviation from the mechanical axis was 2.3° ± 5.1°. There was no evidence of publication bias, but there was strong statistical heterogeneity. The alignment of the mechanical axes did not differ between the navigated and conventional surgery group (weighted mean difference, 0.2°; 95% confidence interval, -0.2° to 0.5°). Patients managed with navigated surgery had a lower risk of malalignment at critical thresholds of >3° (risk ratio, 0.79; 95% confidence interval, 0.71 to 0.87) and >2° (risk ratio, 0.76; 95% confidence interval, 0.71 to 0.82). No conclusive inferences could be drawn on functional outcomes or complication rates. Navigation lengthened the mean duration of surgery by 23%. Conclusions: Navigated knee replacement provides few advantages over conventional surgery on the basis of radiographic end points. Its clinical benefits are unclear and remain to be defined on a larger scale. Level of Evidence: Therapeutic Level III. See Instructions to Authors for a complete description of levels of evidence.

Background: The routine removal of orthopaedic fixation devices after fracture healing remains an issue of debate. There are no evidence-based guidelines on this matter, and little is known on surgeons' practice and perceived effectiveness of implant removal in different clinical settings. Methods: A 41-item questionnaire was distributed to 730 attendees of the AO Principles and Masters Courses of Operative Fracture Treatment in Davos, Switzerland, to assess their attitudes towards removal of different types of implants, and perceived benefits and risks with this common procedure. Results: The response rate was 655/730 (89.7%), representing 54.6% of all 1199 course attendees. Surgeons from 65 countries (571 males and 84 females, mean age 39 ± SD 9 years) took part in the survey. Fifty-eight percent of the participants did not agree that routine implant removal is necessary, and 49% and 58% did not agree that indwelling implants pose an excess risk for fractures or general adverse effects. Forty-eight percent felt that removal is riskier than leaving the implant in situ. Implant removal in symptomatic patients was rated to be moderately effective (mean rating on a 10-point-scale, 5.8, 95% confidence interval 5.7–6.0). Eighty-five percent of all participants agreed that implant removal poses a burden to hospital resources. Surgeons were undetermined whether implant removal is adequately reimbursed by payers of health care services (44% "I-don't-know"-answers). Conclusion: Many surgeons refuse a routine implant removal policy, and do not believe in clinically significant adverse effects of retained metal implants. Given the frequency of the procedure in orthopaedic departments worldwide, there is an urgent need for a large randomized trial to determine the efficacy and effectiveness of implant removal with regard to patient-centred outcomes.