Purpose of Technology: Patient-specific instruments (PSI) for total knee arthroplasty (TKA) are custom-made bone-cutting guides for use during TKA surgical implantation that are manufactured for each patient based on analysis of presurgical magnetic resonance imaging or computed tomography.

Controversy: Although many factors may contribute to poor TKA outcomes, malalignment of the implant in particular has been associated with poor clinical outcomes, early implant loosening, premature implant wear, and arthroplasty failure. PSI are intended to improve alignment compared with conventional instruments (CI). While the proposed benefits of PSI are appealing, the superiority of PSI compared with CI has not been established, and PSI cost more than CI. There are also questions related to whether alignment outcomes are an appropriate surrogate for revision/reoperation rates, which are patient-important outcomes.

Relevant Questions:

  • Do PSI lower surgical revision rates?

  • Do PSI lead to lower proportion of postoperative knee alignment outliers?

  • Do PSI lead to reduction in surgical time or length of hospital stay?

  • Is there greater improvement in function with use of PSI?

  • What are the harms or complications, including intraoperative abandonment of use of PSI?

  • Have definitive patient selection criteria been established for the use of PSI?

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