Computer-Assisted Surgical Navigation Does Not Improve the Alignment and Orientation of the Components in Total Knee Arthroplasty

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1 This is an enhance PDF from The Journal of Bone an Joint Surgery The PDF of the article you requeste follows this cover page. Computer-Assiste Surgical Navigation Does Not Improve the Alignment an Orientation of the Components in Total Knee Arthroplasty Young-Hoo Kim, Jun-Shik Kim, Yoowang Choi an Oh-Ryong Kwon J Bone Joint Surg Am. 2009;91: oi: /jbjs.g This information is current as of January 2, 2009 Supplementary material Reprints an Permissions Publisher Information Commentary an Perspective, ata tables, aitional images, vieo clips an/or translate abstracts are available for this article. This information can be accesse at Click here to orer reprints or request permission to use material from this article, or locate the article citation on jbjs.org an click on the [Reprints an Permissions] link. The Journal of Bone an Joint Surgery 20 Pickering Street, Neeham, MA

2 14 COPYRIGHT Ó 2009 BY THE JOURNAL OF BONE AND JOINT SURGERY, INCORPORATED Computer-Assiste Surgical Navigation Does Not Improve the Alignment an Orientation of the Components in Total Knee Arthroplasty By Young-Hoo Kim, MD, Jun-Shik Kim, MD, Yoowang Choi, MD, an Oh-Ryong Kwon, MD Investigation performe at The Joint Replacement Center of Korea, Ewha Womans University School of Meicine, Seoul, South Korea Backgroun: Whether total knee arthroplasty with use of computer-assiste surgical navigation can improve the limb an component alignment is a matter of ebate. We hypothesize that total knee arthroplasty with use of computer-assiste surgical navigation is superior to conventional total knee arthroplasty with regar to the precision of implant positioning. Methos: Sequential simultaneous bilateral total knee arthroplasties were carrie out in 160 patients (320 knees). One knee was replace with use of a computer-assiste surgical navigation system, an the other was replace conventionally without use of computer-assiste surgical navigation. The two methos were compare for accuracy of orientation an alignment of the components as etermine by raiographs an compute tomography scans. The mean uration of follow-up was 3.4 years. Results: The mean preoperative Knee Society score was 26 points, with an improvement to 92 points postoperatively, in the computer-assiste total knee arthroplasty group an 25 points, with an improvement to 93 points postoperatively, in the conventional total knee arthroplasty group. Preoperative an postoperative ranges of motion of the knees were similar in both groups. The operating an tourniquet times were significantly longer in the computer-assiste total knee arthroplasty group than in the conventional total knee arthroplasty group (p < 0.001). The groups were not significantly ifferent with regar to the accuracy of component positioning an the number of outliers for the various raiographic parameters (p > 0.05). Conclusions: Our ata emonstrate that total knee arthroplasty with use of computer-assiste surgical navigation i not result in more accurate implant positioning than that achieve in conventional total knee arthroplasty, as etermine by both raiographs an compute tomography scans. Level of Evience: Therapeutic Level II. See Instructions to Authors for a complete escription of levels of evience. Recently, there has been increase interest in total knee arthroplasty with use of computer-assiste surgical navigation 1-8. Computer-assiste surgical navigation systems are esigne to increase the precision of implantation of the components. Some stuies have foun a clear tenency towar improve alignment of the limb an the component position with use of computer-assiste surgical navigation 1,3,5,7,9-11.Other stuies have inicate that no significant ifference was foun between total knee arthroplasty with use of computer-assiste surgical navigation an conventional total knee arthroplasty 9,12. These conflicting results are partially attribute to the measurement of the alignment of the limb an the position of the component on full-length staning raiographs of the lower extremity. A limitation to this measurement metho is imaging errors cause by images that are not strictly coronal or sagittal, extension eficits, an rotation between the femur an the tibia 13. The alignment an position of the component can only be precisely escribe with the use of a three-imensional imaging proceure, separately evaluating the position of the femoral component in reference to the femur (from the hip to the knee center) an the position of the tibial component in reference to the tibia (from the knee to the ankle center). Disclosure: The authors i not receive any outsie funing or grants in support of their research for or preparation of this work. Neither they nor a member of their immeiate families receive payments or other benefits or a commitment or agreement to provie such benefits from a commercial entity. No commercial entity pai or irecte, or agree to pay or irect, any benefits to any research fun, founation, ivision, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immeiate families, are affiliate or associate. A commentary is available with the electronic versions of this article, on our web site ( an on our quarterly CD-ROM/DVD (call our subscription epartment, at , to orer the CD-ROM or DVD). J Bone Joint Surg Am. 2009;91:14-9 oi: /jbjs.g.01700

3 15 Apart from the mechanical axis, the rotational alignments of the femoral an tibial components are important for the functional outcome. It has been unclear whether rotational alignment can be improve with the use of computer-assiste surgical navigation systems. We hypothesize that total knee arthroplasty with use of computer-assiste surgical navigation is superior to conventional total knee arthroplasty with regar to the precision of implant positioning as etermine by raiographs an threeimensional compute tomography scans. Fig. 1 Raiograph showing the mechanical axis in the coronal plane. The alignment of the femoral an tibial components was measure by the intersection of a line rawn across the base of each component an the mechanical axis. a = frontal femoral angle, an b = frontal tibial angle. Materials an Methos We prospectively enrolle 170 consecutive patients unergoing primary bilateral sequential total knee arthroplasties from January 2003 to March All patients provie informe consent. All operations were carrie out by a senior author (Y.-H.K.). We obtaine prior approval of our institutional review boar. Ten patients who were originally enrolle in the stuy were lost to follow-up one year after the operation. The final stuy group comprise the remaining 160 patients (320 knees). Each patient ha a total knee arthroplasty with use of computer-assiste surgical navigation in one knee an conventional total knee arthroplasty in the other. There was no significant ifference between the two cohorts in terms of preoperative conitions, incluing the extent of the inex isease, pain, functional isability, eformity, range of motion, bone loss, an prior surgical treatments. The stuy group consiste of 141 women an nineteen men with a mean age of 68.5 years (range, fifty-six to eightyone years) at the time of the inex surgery. The preponerance of women in this series is ue to this specific ethnic group of patients. The mean height of the patients was cm (range, 141 to 168 cm), the mean weight was 63 kg (range, 37 to 113 kg), an the mean boy mass inex was 26.8 kg/m 2 (range, 22 to 45 kg/m 2 ). In all knees, the iagnosis was osteoarthritis. All knees ha a varus eformity ranging from 8 to 20. A total of twenty-seven patients (17%) ha unergone an arthroscopic ébriement in one or both knees, an the remaining 133 ha ha no previous operation on their knee. A NexGen cruciate-retaining high-flex total knee prosthesis (Zimmer, Warsaw, Iniana), with a NexGen moular tibial component an an all-polyethylene patellar component, was cemente in all knees. The proceure was carrie out through a miline skin incision of 10 to 12 cm in length with use of a meial parapatellar arthrotomy. In all of the conventional total knee arthroplasties, extrameullary instrumentation was use for the tibial component an intrameullary instrumentation for the femoral sie. The computer-assiste surgical navigation system (VectorVision CT-free knee; BrainLAB, Munich, Germany) that was use ha an optical tracking unit, which etecte reflecting marker spheres with an infrare camera. Clinical an raiographic review was one at three months, one year, an yearly thereafter. The mean uration of follow-up was 3.4 years (range, three to four years). All of the clinical ata analysis an the raiographic an compute tomographic scanning measurements were performe an compile by one observer who was bline to the type of total knee arthroplasty. Preoperative an postoperative scores were obtaine for all patients with use of the Hospital for Special Surgery 14 an the Knee Society 15 knee-scoring systems.

4 16 The operative time, tourniquet time, amount of bloo loss, amount of transfusion, uration an volume of rainage, an rate of key complications were use to ientify the potential proficiency of the surgeon s surgical technique. Raiographic Measurements All patients ha complete raiographic follow-up examinations. All of the raiographs were reviewe by one observer who ha no knowlege of the patient. Full-length anteroposterior raiographs of the knee, incluing the femoral hea an the ankle, mae with an without weight-bearing, an lateral an skyline patellar raiographs were mae preoperatively an postoperatively an were assesse for the mechanical axis (Fig. 1), the position of the components (Fig. 2), an the location of raiolucent lines at the cement-bone interfaces as recommene by the Knee Society 15. Compute Tomographic Measurements Postoperative compute tomographic scans were obtaine with use of a multislice scanner (Light Plus; General Electric Meical Systems, Waukesha, Wisconsin). Threeimensional component alignment was etermine with use of the metho escribe by Matziolis et al. 16 (see Appenix). From the spatial relationship between the femoral an tibial components an the femoral an tibial mechanical axes, the following angles were etermine: the varus or valgus position of the femoral component relative to the femoral mechanical axis, the varus or valgus position of the tibial component relative to the tibial mechanical axis, the varus or valgus position of the entire limb as the sum of the tibial an femoral mechanical axes, the extension-flexion of the femoral component in relation to the femoral mechanical axis, the tibial posterior slope, the rotational eviation of the femoral component from the epiconylar axis, an the rotational eviation of the tibial component from the reference axis. Statistical Analysis Intraobserver reliability was almost perfect for both the computer-assiste total knee arthroplasties an the conventional total knee arthroplasties (p < 0.01 in each case) 17. The value of kappa was 0.97 for the computer-assiste total knee arthroplasties an 0.95 for the conventional total knee arthroplasties. With use of the Bonferroni metho 18, the alpha level of each iniviual test was ajuste ownwar to ensure that the overall risk for a number of tests remaine In our stuy, the alpha level shoul be < after thirty-seven outcome measures to have significance. The Kolmogorov-Smirnov 19 test was use to evaluate whether the axial alignment followe a normal (Gaussian) istribution, an the Levene 20 test was use to assess the homogeneity of variance (constant variance). The alignment of the limb an the uration of the operation were compare with use of an unpaire Stuent t test, with the assumption of homogeneity of variance use as appropriate. Fig. 2 Raiograph showing the measurement of flexion an extension of the femoral component an measurement of the posterior slope of the tibial component. g = sagittal femoral angle, an = sagittal tibial angle. Box-an-whisker plots were use to compare the postoperative alignment of the leg with use of meian quartiles an interquartile ranges, an eviations were compare with use of the nonparametric Mann-Whitney U test. For continuous variables an ifferences between two means, 95% confience intervals were calculate. Two-taile values of p < 0.05 were consiere to be significant. Power stuies suggeste that forty-five patients were neee in each group to etermine whether there was a clinically significant ifference (power = 0.8 an p < 0.05) between the groups with respect to the clinical, raiographic, an compute tomographic finings. Source of Funing There was no external funing for this stuy. Results With use of the Bonferroni metho for multiple comparison correction, the mean operating an tourniquet times were foun to be significantly longer in the computerassiste total knee arthroplasty group than in the conventional

5 17 TABLE I Operative Data Parameters* Computer-Assiste Total Knee Conventional Total Knee P Value Operating time (min) 97 (65 to 110) 79 (55 to 91) <0.001 Tourniquet time (min) 75 (59 to 90) 49 (56 to 85) <0.001 Mean length of incision (cm) Extension 14.2 (12 to 16.5) 13.0 (11 to 16) Flexion 15.9 (13.5 to 18) 14.4 (12.5 to 17.5) Intraoperative bloo loss (ml) 231 (65 to 550) (110 to 620) Drainage (ml) (130 to 1330) (55 to 1550) Drainage uration (ays) 4.7 (2 to 6) 4.6 (3 to 7) Volume of transfusion (ml) (100 to 2780) (270 to 2650) *The values are given as the mean, with the range in parentheses. total knee arthroplasty group (p < 0.001) (Table I). There were no ifferences between the groups in terms of knee score, range of motion, implant position, or the prevalence of outliers of implant position. The length of the incision, the intraoperative bloo loss, the uration an volume of rainage, an the transfusion volume were not significantly ifferent between the groups (p > 0.05) (Table I). The Kolmogorov-Smirnov test reveale that the groups arose from the same population istributions (p = 0.05). The samples in our stuy ha equal variances accoring to the Levene test. The mean preoperative an postoperative Knee Society knee an functional scores an the Hospital for Special Surgery knee scores in the groups were similar. Also, the preoperative an postoperative ranges of motion of the knee were similar in the two groups of patients (Table II). All clinical ata emonstrate no ifference between the groups at three months, one year, an a mean of 3.4 years after the operation. Raiographic Results (Table III) Raiographic results were similar in both the computerassiste an the conventional total knee arthroplasty groups with regar to the alignment of the knee an the position of the femoral an tibial components in the coronal an sagittal planes. If one assumes a tolerance level of 3, the prevalence of outliers range from 8% to 15% for all parameters in the computer-assiste arthroplasty group an from 13% to 21% in the conventional total knee arthroplasty group. These ifferences between the groups were not significant (p > 0.05). Also, these ifferences were not clinically meaningful. The raiographic ata were not ifferent between the groups at three months, one year, an a mean of 3.4 years after the operation. Results of Three-Dimensional Compute Tomography (Appenix) The three-imensional compute tomographic evaluations were similar in both the computer-assiste an the conventional TABLE II Comparison of Knee Scores in Groups at Preoperative an Mean 3.4-Year Postoperative Evaluations Computer-Assiste Total Knee Conventional Total Knee Parameters Preop. Postop. Preop. Postop. Knee Society knee score* (points) 26 (9 to 41) 92 (91 to 100) 25 (10 to 42) 93 (89 to 100) Knee Society pain score* (points) 21 (0 to 30) 42 (41 to 50) 20 (9 to 35) 43 (39 to 50) Knee Society eformity score* (points) 5 (2 to 10) 0.4 (0 to 2) 5 (0 to 30) 0.5 (0 to 5) Knee Society function score* (points) 19 (15 to 31) 83 (69 to 100) 23 (17 to 41) 81 (69 to 100) Hospital for Special Surgery knee score* (points) 48 (11 to 57) 89 (75 to 100) 51 (16 to 55) 91 (78 to 100) Range of motion* (eg) 125 (100 to 148) 123 (115 to 145) 128 (95 to 150) 126 (100 to 145) Prior arthroscopic ébriement (patients/knees) 15/22 12/19 *The values are given as the mean, with the range in parentheses.

6 18 TABLE III Raiographic Results at a Mean of 3.4 Years of Follow-up Parameters Computer-Assiste Total Knee Conventional Total Knee P Value Mechanical axis (coronal plane) 4.8 of varus to 5.1 of valgus alignment 4.9 of varus to 4.7 of valgus alignment Outliers (>3 ) (no. of knees) 20 (13%) 30 (19%) Femoral angle (coronal plane) Outliers (>3 ) (no. of knees) 18 (11%) 28 (18%) Femoral angle* (sagittal plane) 1.8 ± ± Outliers (>3 ) (no. of knees) 12 (8%) 20 (13%) Tibial angle (coronal plane) Outliers (>3 ) (no. of knees) 14 (9%) 28 (18%) Tibial angle (sagittal plane) Outliers (>3 ) (no. of knees) 24 (15%) 34 (21%) *The values are given as the mean flexion an the stanar eviation total knee arthroplasty groups with regar to the alignment of the knee an the position of the femoral an tibial components in the coronal, sagittal, an rotational planes. Complications Six knees (4%) in the computer-assiste total knee arthroplasty group ha anterior femoral notching. One knee in the computer-assiste total knee arthroplasty group ha a woun infection, which was manage with open ébriement followe by intravenous antibiotics for six weeks. There was no further recurrence of infection. No complication was note in the 160 total knee arthroplasties that were performe without computer-assiste surgical navigation. Discussion In the current stuy, the postoperative mechanical limb axis as etermine by raiographic evaluation was not significantly better in the group that ha total knee arthroplasty with use of computer-assiste surgical navigation than in the group that ha conventional total knee arthroplasty. The postoperative mechanical limb axis exceee 3 of varus-valgus eviation in 13% of the patients manage with use of computer-assiste surgical navigation an in 19% of the patients manage with the conventional metho. This ifference was not significant an is consistent with the results of Bauwens et al. 21, Mielke et al. 12, an Jenny an Boeri 9, who foun no significant ifference in postoperative mechanical limb axis alignment between total knee arthroplasty with computer-assiste surgical navigation an conventional total knee arthroplasty. By contrast, our finings were not in agreement with the results of many investigators who have emonstrate that total knee replacements implante with computer-assiste surgical navigation have more accurate alignment, on the basis of plain raiographs, than those implante conventionally 1,3,5,7,9-11.However, the improvement in accuracy through computer assistance has been shown to be a few egrees, which is within the range of inaccuracy prouce by projection-relate errors in staning raiographs 13. To avoi inaccuracy prouce by projection-relate errors in staning raiographs, three-imensional compute tomographic evaluation has been aopte by several investigators 2,8,16,22. With this metho, many authors 2,8,16,22 have emonstrate a higher accuracy of implant alignment through the use of a computer-assiste surgical navigation system in both the coronal an the rotational plane. In contrast, Oberst et al. 22 i not show a ifference in the accuracy of implant alignment, particularly in the rotational alignment of femoral an tibial components, between total knee arthroplasties performe with or without computer-assiste surgical navigation. Our finings are consistent with those of Oberst et al. Regarless of which implantation metho is use, the rotational alignment of the tibial component ha a consierable range, from 9.2 of internal rotation to 10.4 of external rotation. The high variability of tibial component rotation was attribute to two factors. First, intraoperative etermination of selecte lanmarks (the tibial tuberosity an the center of the tibia) was highly variable. Secon, postoperative etermination of selecte lanmarks of the tibia an the tibial components in the compute tomographic scanning also was highly variable. To minimize this variability, precision of the surgical technique (the center of the tibial component being irecte to the meial one-thir of the tibial tuberosity) an the use of a software program of compute tomographic scanning to reuce metallic interference are necessary. We foun no significant ifference between the two methos with regar to the accuracy of implantation of the tibial component. The fact that we foun no association between implant alignment an the early postoperative range of motion or the Hospital for Special Surgery an Knee Society scores may be

7 19 explaine by the consierably low eviation from the esignate axes in both groups of knees in this series. Almost as important as the improve accuracy is the reuction in the number of outliers for the various raiographic an compute tomographic parameters. The surgical outlier rate is epenent on the skill of the surgeon, the number of total knee arthroplasties performe, an his or her familiarity with the implant 1,10,11,22. No significant ifference was etecte between the groups of knees in our stuy with respect to the number of raiographic an compute tomographic outliers. This fining suggests that experience surgeons can perform total knee arthroplasties with computer-assiste surgical navigation or in the conventional manner to the point that the raiographic an compute tomographic results associate with the two techniques are equivalent. Our ata emonstrate that total knee arthroplasty with use of computer-assiste surgical navigation oes not result in more accurate implant positioning with regar to the alignment of the femoral an tibial components in the coronal, sagittal, an rotational planes than that achieve in conventional total knee arthroplasty, as etermine by both raiographs an three-imensional compute tomography scans. Appenix Figures an tables showing the compute tomographic measurements an their results are available with the electronic versions of this article, on our web site at jbjs.org (go to the article citation an click on Supplementary Material ) an on our quarterly CD/DVD (call our subscription epartment, at , to orer the CD or DVD). n Young-Hoo Kim, MD Jun-Shik Kim, MD Yoowang Choi, MD Oh-Ryong Kwon, MD The Joint Replacement Center of Korea at Ewha Womans University, Mok Dong Hospital, 911-1, MokDong, YangCheon-Ku, Seoul , South Korea. aress for Y.-H. Kim: younghookim@ewha.ac.kr References 1. 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