The Dark Side of Precision: Pin-Related Complications in Computer-Navigated and Robotic-Assisted Knee Arthroplasty

Background: With the rising volume of knee arthroplasty and increasing adoption of robotic- and computer-assisted systems, the routine use of tracker pins has introduced procedure-specific risks. This systematic review aimed to characterize the types and incidence of pin-site complications associated with robotic-assisted and computer-navigated primary knee arthroplasty and to describe the timing, management strategies, and reported outcomes. Methods: A PRISMA-guided search of PubMed/MEDLINE was performed using terms related to pin-related complications, robotic assistance, computer navigation, total and unicompartmental knee arthroplasty procedures. Clinical studies (RCTs, cohorts, case series, and case reports) that explicitly documented pin-related complications in robotic- or computer-assisted knee arthroplasty in English were included. Two independent reviewers performed study selection and data extraction; the methodological quality of non-randomized studies was assessed with the MINORS instrument. Extracted variables encompassed study design, patient demographics, pin characteristics, type and timing of complications, treatments, and outcomes. Descriptive statistics and means were used where appropriate. Results: From 1231 initial records, 28 studies met the inclusion criteria, comprising 15,004 cases in cohort/series analyses. The aggregate pin-related complication incidence in non-case-report series was 0.95% (142 events). Of these, 13.4% were intraoperative and 86.6% postoperative. The most common postoperative events were pin-site wound issues and infections (each ≈35.7% of complications); pin-site fractures accounted for 0.16% in cohort/series data. Case reports (n = 17 patients) showed fractures chiefly at femoral pin sites, arising on average 8.5 weeks postoperatively; management ranged from protected weight-bearing to intramedullary nailing or ORIF. Potential risk factors suggested in the literature include higher BMI, bicortical or transcortical fixation, metaphyseal pin placement, and larger pin diameter, but findings were inconsistent. Conclusions: Pin-related complications after robotic- and computer-assisted knee arthroplasty are uncommon but clinically significant (≈0.95%). There is insufficient evidence to define optimal pin-placement strategies or fixation configurations. Surgeons should include pin-related risks in informed consent discussions. Further prospective research is required to identify patient- and technique-specific risk factors and to establish evidence-based pin-placement guidelines.