The role of custom cutting guides (CCG), also known as patient-specific instrumentation, in total knee arthroplasty (TKA) remains controversial. Originally, this technique potentially offered many benefits including: more accurate alignment, less surgical time, and reduced costs. It was hoped that this would translate into better outcomes and longer implant survivorship. In assessing the overall literature, some studies describe improved component positioning (fewer outliers) over manual alignment techniques (1-3). However, studies have demonstrated mixed results for all of the above mentioned parameters (4-6). Therefore, the role of patient-specific instrumentation remains unclear.
To further investigate the potential benefits of CCG, Nam and colleagues (7) performed a retrospective study of 224 patients. These were patients who self-selected to either undergo a standard TKA (n=120) or one utilizing CCG (N=124). Only patients who had a minimum of 1-year follow-up (mean, 3 years; range, 1 to 4 years) were included (97 of 120 in standard cohort, 104 of 124 in CCG cohort). This represents the longest follow-up of this technique to the best of the authors’ knowledge. The first consecutive 95 patients in each group were analyzed. The cohorts had no differences in their pre-operative demographics. At final follow-up, there were no differences between the two cohorts in outcomes of multiple parameters including: University of California Los Angeles activity score, short-form 12, and Oxford Knee score. Also, there were no differences in operative time and range-of-motion. Furthermore, there was a large percentage of outliers in each group (23% in standard cohort vs. 31% in CCG cohort, P=0.2). Thus, their findings add to the current body of literature suggesting little to no benefit of this technology in total knee arthroplasty (8-11). However, as the authors correctly stated, the design of their study was not optimal to fully investigate these factors; notably, the relatively small sample size, lack of randomization, and the strict inclusion criteria.
Additionally, we believe that the number of outliers is also important to address. Although this difference was not significant, the larger proportion of outliers in the CCG cohort is surprising. It would be interesting to sub-analyze outcome parameters in both patient groups by excluding the outliers, as this might give orthopaedists a clearer picture of what is happening with these optimal patients, and whether they differ from the outliers using either technique. Based on presentations, these authors are doing further research in this specific area with the results forthcoming. Nevertheless, it does not appear that the promised accuracy or improved outcomes of CCGs have been realized based on the results of this study. Perhaps better accuracy will be achieved with robot-assisted TKA and other newer technologies that are on the horizon.
As longer follow-up on these patients becomes available, we encourage the authors of the present study, and all other studies assessing CCG’s, to report longer term findings. This is important, as the mixed picture currently present in the literature does not offer adult reconstructive surgeons better direction with regards to the use of this technology. In addition, parameters such as surgical efficiency and costs of utilizing CCGs, just like CAS, do not appear to be well-investigated or encouraging. However, newer technologies, which aim to achieve similar objectives (better alignment and outcomes), such as robotic-arm assisted total knee arthroplasty; may help eventually replace this technology.
Conflicts of Interest: Dr. Mont is a consultant for, or has received institutional or research support from the following companies: Sage Products, TissueGene, OnGoing Care Solutions, DJO Global, Microport, Orthosensor, National Institutes of Health, Stryker, Johnson & Johnson, Pacira Pharmaceuticals, Merz, US Medical Innovations. He is on the editorial/governing board of the American Journal of Orthopedics, Journal of Arthroplasty, Journal of Knee Surgery, and Surgical Technology International. He is the board or committee member of AAOS; the other authors have no conflicts of interest to declare.
- Ast MP, Nam D, Haas SB. Patient-specific instrumentation for total knee arthroplasty: a review. Orthop Clin North Am 2012;43:e17-22. [Crossref] [PubMed]
- Krishnan SP, Dawood A, Richards R, et al. A review of rapid prototyped surgical guides for patient-specific total knee replacement. J Bone Joint Surg Br 2012;94:1457-61. [Crossref] [PubMed]
- Ng VY, DeClaire JH, Berend KR, et al. Improved accuracy of alignment with patient-specific positioning guides compared with manual instrumentation in TKA. Clin Orthop Relat Res 2012;470:99-107. [Crossref] [PubMed]
- Barrack RL, Ruh EL, Williams BM, et al. Patient specific cutting blocks are currently of no proven value. J Bone Joint Surg Br 2012;94:95-9. [Crossref] [PubMed]
- 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;22:630-5. [Crossref] [PubMed]
- Watters TS, Mather RC 3rd, Browne JA, et al. Analysis of procedure-related costs and proposed benefits of using patient-specific approach in total knee arthroplasty. J Surg Orthop Adv 2011;20:112-6. [PubMed]
- Nam D, Park A, Stambough JB, et al. The Mark Coventry Award: Custom Cutting Guides Do Not Improve Total Knee Arthroplasty Clinical Outcomes at 2 Years Followup. Clin Orthop Relat Res 2016;474:40-6. [Crossref] [PubMed]
- Sassoon A, Nam D, Nunley R, et al. Systematic review of patient-specific instrumentation in total knee arthroplasty: new but not improved. Clin Orthop Relat Res 2015;473:151-8. [Crossref] [PubMed]
- Vundelinckx BJ, Bruckers L, De Mulder K, et al. Functional and radiographic short-term outcome evaluation of the Visionaire system, a patient-matched instrumentation system for total knee arthroplasty. J Arthroplasty 2013;28:964-70. [Crossref] [PubMed]
- Woolson ST, Harris AH, Wagner DW, et al. Component alignment during total knee arthroplasty with use of standard or custom instrumentation: a randomized clinical trial using computed tomography for postoperative alignment measurement. J Bone Joint Surg Am 2014;96:366-72. [Crossref] [PubMed]
- 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 2014;9:837-44. [Crossref] [PubMed]