Special Focus Section

177

Patient-Specific Instrumentation in Total Knee Arthroplasty Julio J. Jauregui, MD1 Jeffrey J. Cherian, DO1 Bhaveen H. Kapadia, MD1 Samik Banerjee, MS (Orth), MRCS (Glasg)1 Kimona Issa, MD1 Steven F. Harwin, MD2 Michael A. Mont, MD1 1 Center for Joint Preservation and Replacement, Rubin Institute for

Advanced Orthopedics, Baltimore, Maryland 2 Department of Orthopaedic Surgery, Beth Israel Medical Center, New York, New York

Address for correspondence Michael A. Mont, MD, Center for Joint Preservation and Replacement, Rubin Institute for Advanced Orthopedics, 2401 West Belvedere Avenue, Baltimore, MD 21215 (e-mail: [email protected]).

Abstract

Keywords

► patient-specific instrumentation ► total knee arthroplasty ► preoperative templating

Patient-specific instrumentation (PSI) is a technology that allows the surgeon to perform a total knee arthroplasty (TKA) potentially more easily with preformed cutting blocks and jigs, which are developed from preoperative computed tomographic or magnetic resonance image scans of the knee. It was introduced with the goal of reducing surgical time, minimizing costs, improving alignment, and reducing radiographic outliers when performing a TKA. Although multiple reports have demonstrated that PSI can reduce the amount of trays and instrumentation required, operative time, and turnover rates, this has not been extrapolated to an overall cost reduction. This is potentially related to the costs of preoperative imaging and the intrinsic costs of production of the patientspecific guides. With the present technology, it is also controversial whether improvements in alignment can be achieved. In addition, it remains to be seen whether this will lead to a reduction in costs and improvements in clinical, radiographic, and functional outcomes. As PSI is relatively new, there is a paucity of long-term studies, which makes it difficult to predict whether long-term improvements in implant survivorship will lead to substantial improvements in patient function, overall outcomes, or cost benefits.

Patient-specific instrumentation (PSI) is a technique that potentially permits more accurate alignment for a total knee arthroplasty (TKA). This alignment is achieved by using specific cutting blocks created from a three-dimensional (3D) model obtained from a computed tomographic (CT) or a magnetic resonance image (MRI) of the lower extremity. Since its introduction in 2006, PSI-assisted TKAs have been utilized more frequently. A recent study reported that in 2012 there were 82,556 PSI-assisted TKAs performed worldwide.1 The benefits of this technique are to preoperatively allow the surgeon customize their instrumentation, accurately select the implant size, and determine implant positing while maintaining correct overall limb alignment when performing a TKA. These benefits are purported to achieve improved costeffectiveness with a desire to obtain better outcomes.2

Accurate implant positioning and optimal alignment are crucial for obtaining successful outcomes after TKA.3 To achieve adequate alignment, long intramedullary femoral rods have been utilized to determine the exact cutting block positioning when using conventional instrumentation.4 However, the use of intramedullary rods has demonstrated to increase the risk for systemic and/or pulmonary emboli and the alignment has not always been satisfactory.5–7 To avoid using intramedullary guides, computer-assisted surgery (CAS) was developed, which demonstrated satisfactory improvements in alignments when compared with conventional techniques. Despite the initial enthusiasm for this technology, in the United States less than 5% of the TKAs are performed each year with CAS. This is due to concerns of increased institutional costs, longer operating times, and high

received February 19, 2014 accepted March 16, 2014 published online April 24, 2014

Copyright © 2014 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA. Tel: +1(212) 584-4662.

DOI http://dx.doi.org/ 10.1055/s-0034-1374813. ISSN 1538-8506.

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J Knee Surg 2014;27:177–184.

Patient-Specific Instrumentation in Total Knee Arthroplasty learning curves. Hence, the development of PSI might be another way to obtain improved alignment for TKA. The purpose of the following review of PSI in TKA is to discuss the technique, to provide a brief historical perspective with initial results, to review current results and economic considerations, and to provide a future outlook for this technology.

Patient-Specific Instrumentation There are presently seven orthopedic manufacturers who offer patient-specific instruments (►Table 1). There are certain variations in the way these instruments are manufactured, but they are essentially conceived in a similar manner.1,2 The preoperative planning consists of obtaining an MRI or a CT scan, which is uploaded to an online system. The advantages of MRI are that it correctly depicts the cartilage and does not expose the patient to radiation. The advantage of CT is that it can be used whenever a patient has intrusive knee hardware or cannot be exposed to a great magnetic field. The manufacturer, using specific computer software, generates a 3D reconstruction of the patient’s bony anatomy as well as a simulated model of the patient-specific instrument. Before this process, the surgeon specifies the alignment used (mechanical, anatomic, or kinematic) and the manufacturer generates a report that includes the implant size, the distal and posterior resections, the flexion or extension, varus or valgus, and the overall component positioning for verification by the surgeon. Once verified, the blocks are manufactured from polymer and contain unique patient identifiers for use during surgery. The time frame across different manufacturers to deliver PSI guides varies, but the mean lead time reported in one study was found to be approximately 23 days.1

Jauregui et al. were used in spine surgery.8 Subsequently in 2006, OtisMed (Stryker Corporation, Mahwah, NJ) introduced the first patient-specific cutting blocks for knee arthroplasty. This system was designed to restore the prearthritic kinematic alignment of the knee.9 Although this technology is no longer available, it was similar to currently existing systems and consisted of custom-made cutting guides constructed from a 3D model of the arthritic knee.9 Two of the first outcome studies using PSI were reported by Lombardi et al and Howell et al in 2008.9,10 Lombardi et al evaluated 44 patients who underwent TKAs using patientspecific instruments for differences in operating time and radiographic alignment compared with conventional methods of alignment.10 The authors reported that with the use of PSI the operating time was significantly shorter (10 minutes; p < 0.03). In addition, the authors reported that all TKAs were found to have “satisfactory” alignment within 4 to 8 degrees of valgus. There were no cases of anteroposterior or mediolateral instability, or flexion or extension lag found during radiographic follow-up. The authors reported significant increases in Knee Society score at 3-month follow-up (p < 0.5). A similar study by Howell et al examined a series of 48 consecutive TKAs performed with the use of custom-fit positioning guides.9 The authors reported that patients achieved postoperative alignment measured with a longleg CT scan of 1.4  2.8 degrees of valgus. At 3-month follow-up, 95% of the patients subjectively felt as if their knees were normal or nearly normal. In addition in 2009, a study by Spencer et al compared the results of patients who underwent TKA using PSI (n ¼ 21) to conventional instrumentation (n ¼ 30).11 The authors found postoperative alignment of 1.2 degrees of varus  2.4 degrees. The authors concluded that custom-fit TKA appears to provide comparable alignment outcomes to previous reports of conventional and CAS methods.

Contemporary Studies

Outcomes Historical Perspective and Initially Reported Outcomes The concept of creating PSI for orthopedic surgery was first introduced in 1998, when customized surgical instruments

Since the introduction of PSI, several studies have compared the alignment outcomes of TKAs with PSI and conventional cutting blocks.12–14 A recent review by Ng et al, analyzed the alignment outcomes after conventional TKAs compared with

Table 1 Current PSI on the market Manufacturer

System trade name

Implant

Imaging required

Biomet

Signature Knee Instrumentation

Vanguard Complete Knee System

MRI or CT

ConforMIS

iTotal CR

iTotal G2

CT

DePuy

TruMatch Personalized Solutions

Sigma Knee Solutions

CT

Medacta

Medacta GMK Knee

GMK Total Knee System

MRI or CT

Smith & Nephew

Visionaire Patient Matched Instrumentation

Legion Total Knee System

MRI and radiographs

Wright Medical Technology

Prophecy knee guides

Advance and Evolution Medial Pivot knees

MRI or CT

Zimmer

PSI

NexGen, Natural, and Persona

MRI

Abbreviations: CT, computed tomography; MRI, magnetic resonance image; PSI, patient-specific instrumentation. The Journal of Knee Surgery

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tients had femoral component alignments within 2 degrees of the femoral mechanical axis (90 vs. 100%, respectively; p < 0.05). The authors concluded that, despite some of the potential benefits of PSI, the overall mechanical and tibial component alignment was less accurate when compared with computer-assisted navigation. Please refer to ►Table 2 for the complete list of studies. However, because of conflicting results there is no clear evidence to suggest that alignment outcomes are better with PSI compared with conventional instrumentation.

Economic Considerations The cost of PSI has been reported to range from $520 to $1,020. However, these numbers can increase to over $1,800 when the costs of preoperative imaging, as well as the extra effort and time spent by the surgeon are added.1,18 Theoretically, this extra cost can be offset through (1) potential reductions in operative costs achieved through decrease in the surgical times or through improvements in operating room turnover time, and (2) better alignments in three planes and superior functional outcomes after TKA. However, it is currently unclear whether PSI leads to marked reduction in operating room times. A study by Chotanaphuti et al compared the outcomes of patients who underwent PSI-assisted versus conventionally instrumented TKAs (n ¼ 40 vs. 40 TKAs, respectively).14 The authors reported significantly lower operative times in patients who underwent PSI-assisted TKA when compared with conventionally instrumented TKAs (skin to skin mean of 57.5 vs. 62.1 minutes, respectively; p < 0.001). Similarly, a study by Noble et al reported that the overall surgical time was 6.7 minutes quicker with PSI, compared with conventional instrumentation (121.4 and 128.1 minutes, respectively; p < 0.05).19 In addition, Barrack et al analyzed the instrument tray processing requirements with PSI and conventional instrumentation (n ¼ 100 vs. 100 TKAs, respectively).18 They reported that the postoperative tray collection, manual washing of trays and instruments, and tray reassembly took significantly less time with PSI (savings of approximately 90 minutes; p < 0.05). The authors reported that the hospital’s cost savings per surgery using PSI was approximately $628. A similar study by Watters et al also analyzed the operative room time savings and the number of trays that required processing and concluded that the net savings of using PSI was approximately $290 per case.20 Although PSI may decrease costs by reducing the operative time and the number of instruments and trays used, these savings may potentially be surpassed by the increased costs of imaging and PSI manufacturing. In contrast, a study by Hamilton et al evaluated the differences in operative times and number of trays used during surgery with PSI-assisted versus conventional TKAs (n ¼ 23 vs. 23 TKAs, respectively) and found that total surgical time was over 4 minutes longer in patients in the PSI-assisted group (p > 0.05).21 However, the authors reported significant reduction in the number of trays used during surgery in the PSI group (mean of 2.5 vs. 7.3 trays, respectively; p < 0.001) compared with the conventional cohort. Previously The Journal of Knee Surgery

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PSI (n ¼ 155 vs. 569 TKAs, respectively).13 The authors reported that the overall mechanical axis passed through the central third of the knee more frequently in patients who had TKA performed with PSI when compared with conventional TKA (88 vs. 78%; p < 0.05). In addition, the authors reported that there were less mechanical axis outliers with PSI, compared with conventional instrumentation (9 vs. 22%, respectively; p < 0.05). However, there was no significant difference in the mean hip-knee-ankle between the two groups (p > 0.05). Similarly, Chotanaphuti et al, in a prospective study, evaluated the accuracy of component alignment after TKA with patient-specific cutting blocks (n ¼ 40 knees) and conventional instrumentation (n ¼ 40 knees).14 They found that PSI-assisted TKAs provided significantly better accuracy in rotational alignment (p < 0.05). In addition, the authors noted that the postoperative mechanical axes measurements were comparable with the use of PSI to those in the comparison cohort (p > 0.05). In a recent study, Yaffe et al compared the clinical, functional, and radiographic outcomes between TKAs performed with patient-specific cutting guides (n ¼ 42 TKAs) to those with manual instruments and CAS (n ¼ 38 TKAs).15 Preoperative, 1-month postoperative, and 6-month postoperative knee scores, function scores, range of motion, and pain scores were higher in the PSI group compared with CAS and manual instrumentation. At 6-month follow-up, PSI-TKA was associated with a statistically significant improvement in functional score when compared with manual TKA (24.5 vs. 3.8 points; p < 0.0009). Despite the promising results reported in the previous studies, some reports have demonstrated that PSI has no add improvement in outcomes. A recent meta-analysis of level I and level II studies by Russell et al evaluated 559 patients in 7 studies to determine if PSI improved the mechanical alignment of the lower extremity compared with conventional instrumentation in TKA.16 The authors found that there were no significant benefits in relation to mean coronal alignment between the two cohorts (PSI, 0.78 degrees; and conventional instrumentation I, 0.81 degrees). However, they noted that there were fewer outliers in the PSI cohort (21.1%) compared with conventional instrumentation cohort (23.2%), but this was found to not be statistically significant (p ¼ 0.59). The authors concluded PSI does not improve mechanical alignment after TKA, or the number of outliers compared with that of conventional instruments. In another study, Victor et al evaluated three plane alignments after TKA using patientspecific guides and compared them to conventional cutting blocks (n ¼ 64 vs. 64 TKAs, respectively).12 The authors did not find significant differences in the incidence of alignment outliers in the three planes in both the cohorts (p > 0.05). Nam et al compared the alignments of PSI-TKAs to CAS-TKAs (n ¼ 41 vs. 41 TKAs, respectively).17 The authors reported that in the PSI cohort fewer patients had overall alignments within 3 degrees of neutral mechanical axes compared with the CAS-TKA cohort (71 vs. 93%, respectively; p < 0.05). In addition, the PSI group had significantly fewer patients with a tibial component alignment within 2 degrees of the mechanical axes of the tibia compared with the CAS group (88 vs. 100%, respectively; p < 0.05). Also, significantly fewer pa-

Jauregui et al.

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II

III

III

III

III

III

III

Nam et al,17 2013

Ng et al,13 2012

Nunley et al,32 2012

Pietsch et al,33 2013

Vundelinckx et al,34 2013

Yaffe et al,15 2013

II

Conteduca et al,30 2013

42

31

50

100

569

41

20

12

40

30

29

100



45

15

100

No. of PSI-assisted TKAs

Higher improvement in functional score PSI vs. CI (p < 0.05); other metrics (p > 0.05)

Similar pain, satisfaction, functional outcomes, radiographic alignment, and precision of bone cuts (p > 0.05)

PSI should be verified by surgeon

Similar number of outliers in the mechanical axis in both the groups (p > 0.05)

The overall mechanical axis passed through the central third of the knee in 88% PSI vs. 78% CI (p < 0.05)

PSI had 70.7% of TKA within 3 degrees of a neutral mechanical axis vs. 92.7% with CAS (p ¼ 0.02)

No significant difference (p > 0.05)

Adequate alignment control is recommended before performing the cuts

PSI provided better rotational alignment (p < 0.05); no differences in mechanical axis (p > 0.05)

Objective verification of the alignment should be made

Does not improve rotational alignment

Similar number of outliers in both the groups (p < 0.05); higher costs in PSI group

Coronal alignment with outliers > 3 degrees in PSI ranged from 6 to 31%

No difference obtaining neutral mechanical axis and a correct prosthesis positioning

Mechanical alignment closer to neutral zero in PSI (1.7 vs. 2.8 degrees, p < 0.05); reduction operative time PSI (p < 0.05)

Better sagittal plane alignment in MRI-based PSI (p ¼ 0.02)

Conclusions

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PSI vs. CAS and CI

PSI vs. CI

PSI

PSI vs. CI

PSI vs. CI

PSI vs. CAS

PSI vs. CI

PSI

PSI vs. CI

PSI vs. CAS

PSI vs. CI

PSI vs. CI

PSI vs. CAS and CI

PSI vs. CI

PSI vs. CI

CT PSI vs. MRI PSI

Comparison group

NR

NR

6.0

26.0

9.0

29.3

4.0

NR

5.0

26.6

31.0

31.0

NR

30.0

NR

37 vs. 18

HKA (%)

NR

NR

8.0

NR

10.0

12.8

NR

16.7

NR

NR

10.0

NR

NR

9.0

NR

NR

CTA (%)

NR

NR

10.0

NR

22.0

9.8

NR

7.4

NR

NR

7.0

NR

NR

13.0

NR

NR

CFA (%)

NR

NR

6.0

NR

NR

NR

NR

58.4

NR

NR

24.0

NR

NR

33.0

NR

NR

STA (%)

NR

NR

6.0

NR

NR

NR

NR

29.0

NR

NR

24.0

NR

NR

49.0

NR

NR

SFA (%)

Patient-Specific Instrumentation in Total Knee Arthroplasty

Parratte et al,31 2013

II

II

Chotanaphuti et al,14 2014

2014

II

Chen et al,28 2014

Scholes et al,

II

Barrack et al,18 2012

29

I

Conteduca et al,27 2014

I

Noble et al,19 2012

I

I

Ensini et al,25 2014

Boonen et al,26 2013

LOE

Author, year

Table 2 Outcomes with use of PSI

180 Jauregui et al.

Jauregui et al.

181

mentioned studies evaluated cost savings by reductions in operative time, number of instruments, and number of trays used. However, a study by Slover et al, using Markov modeling, determined that a decrease in the 20-year revision rate of 50% compared with conventional instrumentation would be necessary for PSI to be cost-effective.22

Concerns of Implant Sizing and Incidence of Intraoperative Adjustments In a recent study, Issa et al, evaluated the accuracy of PSI to predict implant alignments and sizing after TKA (n ¼ 84 TKAs).23 The authors reported that the preoperative plan was able to correctly predict the tibial and femoral component sizes in 93 and 95.5% of the surgeries, respectively. In addition, the authors described that 13 major intraoperative modifications were necessary in their study. In one case, the femoral resection was not acceptable, in another, the proposed femoral and tibial components needed to be upsized. Moreover, in two cases, the femoral components were downsized and in four cases the tibial components were downsized. The authors also reported that 16 minor modifications were also necessary. In another study, Victor et al also evaluated the accuracy of the cutting blocks in PSI in 64 TKAs.12 The authors reported that three patients could not be operated using specific cutting blocks because the guides were done for the wrong knee (one patient), guides were made for the wrong patient (one patient), and the guides were not ready on time (one patient). Also, they reported that modifications in the technique were necessary in 13 patients because of inaccuracy in the sizing of the components. In addition, in nine patients the levels of the cuts were inappropriate and needed intraoperative corrections. Similarly, Stronach et al evaluated whether the use of PSI improves surgical precision and decreases operative time in 66 TKA.24 The authors noted that there were 2.4 changes required per knee performed with PSI, and implant size had to be changed intraoperatively in 77% of femurs and 53% of tibias. In addition, the cutting guides were found to not fit securely on eight femurs (12%) and three tibias (5%). The authors concluded that surgeons should use caution with the blind acceptance of PSI. In addition, they reported that there were no improvements in tourniquet time and blood loss with the use of PSI.24 The evidence suggests that even with the current generation of PSI, some inaccuracies may occur during manufacturing of patient-specific guides. However, surgeon experience is an essential key to recognizing these inaccuracies in component sizing, surgical resection, or less optimal alignment when performing PSI-assisted TKA.

Future Directions With added pressures for a more cost-effective health care system and the continuous advent of new technology, PSIassisted TKA will continue to exist. However, as with other tools, the manufacturing costs will have to decrease with a concomitant increase in the accuracy of this system in predicting sizing and alignment during TKA. In addition, The Journal of Knee Surgery

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Abbreviations: CAS, computer-assisted surgery; CFA, coronal femoral angle; CI, conventional instrumentation; CTA, coronal tibial angle; HKA, hip knee angle; LOE, level of evidence; NR, not reported; PSI, patientspecific instrumentation; SFA, sagittal femoral angle; STA, sagittal tibial angle; TKA, total knee arthroplasty.

NR NR 1

82,556 V Thienpont et al, 2013

PSI

PSI should be used with preoperative planning/ validation by the surgeon

NR

NR

NR

9.0 12.3 301 IV Koch et al,37 2013

PSI

Compared with literature, there is no difference

11.7

3.8

4.5

NR NR 100 IV Daniilidis and Tibesku,36 2013

PSI

11and 3% TKA had hip-knee-ankle outliers greater than 3 and 5 degrees, respectively

11.0

NR

NR

NR NR 32 IV Bali et al,35 2012

PSI

Can be safely used in most of the cases of osteoarthritis

9.4

NR

NR

SFA (%) No. of PSI-assisted TKAs LOE Author, year

Table 2 (Continued)

Comparison group

Conclusions

HKA (%)

CTA (%)

CFA (%)

STA (%)

Patient-Specific Instrumentation in Total Knee Arthroplasty

Patient-Specific Instrumentation in Total Knee Arthroplasty because PSI is a relatively new tool, no mid- to long-term results are available. Additional trials with longer follow-up and larger sample sizes are needed to better evaluate the clinical, radiographic, and functional outcomes following PSI.

Jauregui et al. 8 Radermacher K, Portheine F, Anton M, et al. Computer assisted

9

Conclusion

10

There is controversial data reporting whether PSI has actually increased the precision of the knee arthroplasty. Some reports favor PSI-assisted TKA compared with conventionally instrumented TKA, but others describe no significant differences between both. Overall, most studies describe better component positioning and less outliers in the mechanical axis, particularly in the sagittal plane. However, most of the studies comparing these two were possibly biased, because these studies were made by high-volume surgeons working in specialized centers.1 Patient-specific instruments have also been introduced to reduce the surgical time and the overall costs of the implants. While most studies describe a reduction in the operative time, reduction in the number of instruments and trays used, and faster turnover of the operating, the actual cost-effectiveness of this procedure has not been proven. It is believed that this is because the overall cost reduction may be outweighed by the costs of preoperative imaging and instrument fabrication. Currently, in cases in which PSI is used, we recommend performing an accurate control of the alignment before and after any cuts and in any further step of the procedure, to avoid possible outliers. In addition, the surgeon can override these guides and use conventional instrumentation if needed. Therefore, even if the results of PSI appear to be promising, their accuracy could still be improved, possibly leading to greater reliability. In addition, we recommend that orthopedic surgeons should always be analytical when introducing novel technologies, by comparing the risks and benefits of every new tool in the orthopedic armamentarium.

11

12

13

14

15

16

17

18

19

20

References 1 Thienpont E, Bellemans J, Delport H, et al. Patient-specific instru-

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3 4

5

6

7

ments: industry’s innovation with a surgeon’s interest. Knee Surg Sports Traumatol Arthrosc 2013;21(10):2227–2233 Lachiewicz PF, Henderson RA. Patient-specific instruments for total knee arthroplasty. J Am Acad Orthop Surg 2013;21(9): 513–518 Lotke PA, Ecker ML. Influence of positioning of prosthesis in total knee replacement. J Bone Joint Surg Am 1977;59(1):77–79 Elloy MA, Manning MP, Johnson R. Accuracy of intramedullary alignment in total knee replacement. J Biomed Eng 1992;14(5): 363–370 Kalairajah Y, Cossey AJ, Verrall GM, Ludbrook G, Spriggins AJ. Are systemic emboli reduced in computer-assisted knee surgery?: A prospective, randomised, clinical trial J Bone Joint Surg Br 2006; 88(2):198–202 Church JS, Scadden JE, Gupta RR, Cokis C, Williams KA, Janes GC. Embolic phenomena during computer-assisted and conventional total knee replacement. J Bone Joint Surg Br 2007;89(4):481–485 Caillouette JT, Anzel SH. Fat embolism syndrome following the intramedullary alignment guide in total knee arthroplasty. Clin Orthop Relat Res 1990;(251):198–199

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orthopaedic surgery with image based individual templates. Clin Orthop Relat Res 1998;(354):28–38 Howell SM, Kuznik K, Hull ML, Siston RA. Results of an initial experience with custom-fit positioning total knee arthroplasty in a series of 48 patients. Orthopedics 2008;31(9):857–863 Lombardi AV Jr, Berend KR, Adams JB. Patient-specific approach in total knee arthroplasty. Orthopedics 2008;31(9):927–930 Spencer BA, Mont MA, McGrath MS, Boyd B, Mitrick MF. Initial experience with custom-fit total knee replacement: intra-operative events and long-leg coronal alignment. Int Orthop 2009; 33(6):1571–1575 Victor J, Dujardin J, Vandenneucker H, Arnout N, Bellemans J. Patient-specific guides do not improve accuracy in total knee arthroplasty: a prospective randomized controlled trial. Clin Orthop Relat Res 2014;472(1):263–271 Ng VY, DeClaire JH, Berend KR, Gulick BC, Lombardi AV Jr. Improved accuracy of alignment with patient-specific positioning guides compared with manual instrumentation in TKA. Clin Orthop Relat Res 2012;470(1):99–107 Chotanaphuti T, Wangwittayakul V, Khuangsirikul S, Foojareonyos T. The accuracy of component alignment in custom cutting blocks compared with conventional total knee arthroplasty instrumentation: prospective control trial. Knee 2014;21(1):185–188 Yaffe M, Luo M, Goyal N, et al. Clinical, functional, and radiographic outcomes following total knee arthroplasty with patient-specific instrumentation, computer-assisted surgery, and manual instrumentation: a short-term follow-up study. Int J Comput Assist Radiol Surg 2013; December 13 (Epub ahead of print); doi: 10.1007/s11548-013-0968-6 Russell R, Brown T, Huo M, Jones R. Patient-specific instrumentation does not improve alignment in total knee arthroplasty. J Knee Surg 2014; February 6 (Epub ahead of print); doi: 10.1055/s-00341368143 Nam D, Maher PA, Rebolledo BJ, Nawabi DH, McLawhorn AS, Pearle AD. Patient specific cutting guides versus an imageless, computerassisted surgery system in total knee arthroplasty. Knee 2013; 20(4):263–267 Barrack RL, Ruh EL, Williams BM, Ford AD, Foreman K, Nunley RM. Patient specific cutting blocks are currently of no proven value. J Bone Joint Surg Br 2012;94(11, Suppl A ):95–99 Noble JW Jr, Moore CA, Liu N. The value of patient-matched instrumentation in total knee arthroplasty. J Arthroplasty 2012; 27(1):153–155 Watters TS, Mather RC III, Browne JA, Berend KR, Lombardi AV Jr, Bolognesi MP. Analysis of procedure-related costs and proposed benefits of using patient-specific approach in total knee arthroplasty. J Surg Orthop Adv 2011;20(2):112–116 Hamilton WG, Parks NL, Saxena A. Patient-specific instrumentation does not shorten surgical time: a prospective, randomized trial. J Arthroplasty 2013;28(8, Suppl):96–100 Slover JD, Rubash HE, Malchau H, Bosco JA. Cost-effectiveness analysis of custom total knee cutting blocks. J Arthroplasty 2012; 27(2):180–185 Issa K, Rifai A, McGrath MS, et al. Reliability of templating with patient-specific instrumentation in total knee arthroplasty. J Knee Surg 2013;26(6):429–433 Stronach BM, Pelt CE, Erickson J, Peters CL. Patient-specific total knee arthroplasty required frequent surgeon-directed changes. Clin Orthop Relat Res 2013;471(1):169–174 Ensini A, Timoncini A, Cenni F, et al. Intra- and post-operative accuracy assessments of two different patient-specific instrumentation systems for total knee replacement. Knee Surg Sports Traumatol Arthrosc 2014;22(3):621–629 Boonen B, Schotanus MG, Kerens B, van der Weegen W, van Drumpt RA, Kort NP. Intra-operative results and radiological outcome of conventional and patient-specific surgery in total

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patient-specific guides improve coronal alignment in total knee arthroplasty? Clin Orthop Relat Res 2012;470(3):895–902 Pietsch M, Djahani O, Hochegger M, Plattner F, Hofmann S. Patientspecific total knee arthroplasty: the importance of planning by the surgeon. Knee Surg Sports Traumatol Arthrosc 2013;21(10): 2220–2226 Vundelinckx BJ, Bruckers L, De Mulder K, De Schepper J, Van Esbroeck G. Functional and radiographic short-term outcome evaluation of the Visionaire system, a patient-matched instrumentation system for total knee arthroplasty. J Arthroplasty 2013; 28(6):964–970 Bali K, Walker P, Bruce W. Custom-fit total knee arthroplasty: our initial experience in 32 knees. J Arthroplasty 2012;27(6): 1149–1154 Daniilidis K, Tibesku CO. Frontal plane alignment after total knee arthroplasty using patient-specific instruments. Int Orthop 2013; 37(1):45–50 Koch PP, Müller D, Pisan M, Fucentese SF. Radiographic accuracy in TKA with a CT-based patient-specific cutting block technique. Knee Surg Sports Traumatol Arthrosc 2013;21(10):2200–2205

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knee arthroplasty: a multicentre, randomised controlled trial. Knee Surg Sports Traumatol Arthrosc 2013;21(10):2206–2212 Conteduca F, Iorio R, Mazza D, Ferretti A. Patient-specific instruments in total knee arthroplasty. Int Orthop 2014;38(2): 259–265 Chen JY, Yeo SJ, Yew AK, et al. The radiological outcomes of patient-specific instrumentation versus conventional total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc 2014;22(3): 630–635 Scholes C, Sahni V, Lustig S, Parker DA, Coolican MR. Patientspecific instrumentation for total knee arthroplasty does not match the pre-operative plan as assessed by intra-operative computer-assisted navigation. Knee Surg Sports Traumatol Arthrosc 2014;22(3):660–665 Conteduca F, Iorio R, Mazza D, et al. Evaluation of the accuracy of a patient-specific instrumentation by navigation. Knee Surg Sports Traumatol Arthrosc 2013;21(10):2194–2199 Parratte S, Blanc G, Boussemart T, Ollivier M, Le Corroller T, Argenson JN. Rotation in total knee arthroplasty: no difference between patient-specific and conventional instrumentation. Knee Surg Sports Traumatol Arthrosc 2013;21(10):2213–2219

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No. 3/2014

Patient-specific instrumentation in total knee arthroplasty.

Patient-specific instrumentation (PSI) is a technology that allows the surgeon to perform a total knee arthroplasty (TKA) potentially more easily with...
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