Novel Approach to Reducing Discrepancies in Radiographic and Navigational Limb Alignments in Computer-Assisted TKA
ABSTRACT This study was conducted (1) to document discrepancies between preoperative and postoperative radiographic measurements and postregistration and postimplantation intraoperative navigational measurements of coronal limb alignments, and (2) to identify predictors of discrepancies between radiographic and navigational measures. In addition, we propose the use of a novel radiographic measuring method, and we demonstrate that this method reduces discrepancies. For 107 total knee arthroplasties performed using a navigation system, coronal alignment were assessed using preoperative and postoperative whole limb radiographs using the standard and novel radiographic methods. During surgery, coronal limb alignment was measured using the navigation system postregistration and postprosthesis implantation. Strengths of correlations and discrepancies between radiographic and navigational assessments were compared between the standard and novel methods. Multivariate regression was performed to identify predictors of discrepancies. Differences between radiographic and navigational measurements were observed for both preoperative and postoperative assessments, but discrepancies were greater for preoperative assessments, despite their stronger correlations. Extent of preoperative varus deformity was identified as the strongest predictor of discrepancy in preoperative radiographic and navigational measurements, and varus malalignment was identified as the strongest predictor of discrepancy in postoperative measurements. Strengths of correlations between radiographic and navigational measurements were similar for the standard and novel radiographic methods, but discrepancies between the 2 were significantly smaller for the novel method for both preoperative and postoperative assessments. The authors propose the use of the described novel radiographic method that reduces discrepancies between radiographic and navigational measurements.
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ABSTRACT: The aim of computer-assisted surgery is to improve accuracy and limit the range of surgical variability. However, a worldwide debate exists regarding the importance and usefulness of computer-assisted navigation for total knee arthroplasty (TKA). The main purpose of this study is to summarize and compare the radiographic outcomes of TKA performed using imageless computer-assisted navigation compared with conventional techniques. An electronic search of PubMed, EMBASE, Web of Science, and Cochrane library databases was made, in addition to manual search of major orthopedic journals. A meta-analysis of 29 quasi-randomized/randomized controlled trials (quasi-RCTs/RCTs) and 11 prospective comparative studies was conducted through a random effects model. Additional a priori sources of clinical heterogeneity were evaluated by subgroup analysis with regard to radiographic methods. When the outlier cut-off value of lower limb axis was defined as ±2° or ±3° from the neutral, the postoperative full-length radiographs demonstrated that the risk ratio was 0.54 or 0.39, respectively, which were in favor of the navigated group. When the cut-off value used for the alignment in the coronal and sagittal plane was 2° or 3°, imageless navigation significantly reduced the outlier rate of the femoral and tibial components compared with the conventional group. Notably, computed tomography scans demonstrated no statistically significant differences between the two groups regarding the outliers in the rotational alignment of the femoral and tibial components; however, there was strong statistical heterogeneity. Our results indicated that imageless computer-assisted navigation systems improve lower limb axis and component orientation in the coronal and sagittal planes, but not the rotational alignment in TKA. Further multiple-center clinical trials with long-term follow-up are needed to determine differences in the clinical and functional outcomes of knee arthroplasties performed using computer-assisted techniques.Journal of Surgical Research 10/2010; 171(2):590-600. DOI:10.1016/j.jss.2010.05.006 · 1.94 Impact Factor
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ABSTRACT: BACKGROUND: The mechanical alignment of the knee is an important factor in planning for, and subsequently assessing the success of a knee replacement. It is most commonly measured using a long-leg anteroposterior radiograph (LLR) encompassing the hip, knee and ankle. Other modalities of measuring alignment include computer tomography (CT) and intra-operative computer navigation (Cas). Recent studies comparing LLRs to Cas in measuring alignment have shown significant differences between the two and have hypothesized that Cas is a more accurate modality. This study aims to investigate the accuracy of the above mentioned modalities. METHODOLOGY: A prospective study was undertaken comparing alignment as measured by long-leg radiographs and computer tomography to intra-operative navigation measurements in 40 patients undergoing a primary total knee replacement to test this hypothesis. Alignment was measured three times by three observers. Intra- and inter-observer correlation was sought between modalities. RESULTS: Intra-observer correlation was excellent in all cases (>0.98) with a coefficient of repeatability <1.1°. Inter-observer correlation was also excellent measuring >0.960 using LLRs and >0.970 using CT with coefficient of repeatability <2.8°. Inter-modality correlation proved to be higher when comparing LLRs and CT (>0.893), than when comparing either of these modalities with Cas (>0.643 and >0.671 respectively). Pre-operative values had the greatest variability. CONCLUSION: Given its availability and reduced radiation dose when compared to CT, LLRs should remain the mainstay of measuring the mechanical alignment of the lower limb, especially post-operatively. LEVEL OF EVIDENCE: II.The Knee 08/2012; 20(4). DOI:10.1016/j.knee.2012.07.009 · 1.94 Impact Factor
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ABSTRACT: BACKGROUND: Coronal alignment is considered key to the function and longevity of a TKA. However, most studies do not consider femoral and tibial anatomical features such as lateral femoral bowing and the effects of these features and subsequent alignment on function after TKA are unclear. QUESTIONS/PURPOSES: We therefore determined (1) the prevalence of lateral femoral bowing, varus femoral condylar orientation, and severe tibia plateau inclination in female Koreans undergoing TKA; (2) whether postoperative alignments are affected by these anatomical features and improved by the use of navigation; and (3) whether postoperative coronal alignments are associated with function. METHODS: We measured alignment in 367 knees that underwent TKA and 60 sex- and age-matched normal knees (control group). We determined patterns and degrees of femoral bowing angle, femoral condylar orientation, and tibial plateau inclination on preoperative full-limb radiographs. Postoperatively, coronal alignment of limbs and of femoral and tibial components was measured. We compared American Knee Society scores, WOMAC scores, and SF-36 scores in aligned knees and outliers (beyond ± 3° or ± 2°) at 1 year. RESULTS: The prevalence of lateral femoral bowing was 88% in the TKA group and 77% in the control group. Mean femoral condylar orientation angle was varus 2.6° in the TKA group and valgus 1.1° in the control group, and mean tibial plateau inclination was varus 8.3° in the TKA group and varus 5.4° in the control group. Femoral lateral bowing and varus femoral condylar orientation were associated with postoperative alignments. Several clinical outcome scales were inferior in the outliers in mechanical tibiofemoral angle, anatomical tibiofemoral angle, and tibial coronal alignment but not in femoral coronal alignment outliers. CONCLUSIONS: Lateral femoral bowing, varus condylar orientation, and severe varus inclination of the tibia plateau should be considered when performing TKA in Korean patients or patients with otherwise similar anatomical features.Clinical Orthopaedics and Related Research 09/2012; 471(5). DOI:10.1007/s11999-012-2618-7 · 2.77 Impact Factor