Hip displacement and dislocation are among the most disabling musculoskeletal sequelae of cerebral palsy (CP) yet reported incidence and risk-factor estimates vary widely across studies. We undertook a systematic review and pooled analysis to quantify cumulative incidence across Gross Motor Function Classification System (GMFCS) strata and identify reproducible clinical and radiographic predictors. A protocol was registered in PROSPERO (CRD420251026860). MEDLINE (PubMed), Embase, CINAHL and CENTRAL were searched from inception to March 30, 2025. Eligible longitudinal studies enrolled ≥30 children with CP aged 2-18 years, provided ≥2 years' follow-up without confounding hip-directed intervention, and reported migration percentage (MP) data or equivalent permitting derivation. Hip displacement and dislocation were harmonized as MP >30 % and >50 %, respectively. Study quality was appraised with ROBINS I. Proportions were stabilized with the Freeman-Tukey double-arcsine transformation and pooled in random-effects (REML) models; odds ratios (ORs) for candidate predictors were combined using inverse-variance random-effects methods. Heterogeneity (I², τ²), prediction intervals, influence diagnostics, Hartung-Knapp sensitivity and Egger tests were performed. Certainty was graded with adapted GRADE. Nineteen studies met inclusion; nine natural-history cohorts (n = 1556; median follow-up 5.1 y) contributed extractable incidence data. The pooled cumulative incidence of hip displacement/dislocation was 38.2 % (95 % CI 31.7-45.1 %; I² = 77 %; prediction interval 6.0 53.8 %). Incidence was 17.1 % in ambulant children (GMFCS I-III) and 71.9 % in non-ambulant children (IV-V), yielding an OR 3.72 (95 % CI 2.56-5.40) for non-ambulant vs ambulant groups. A baseline MP ≥ 30 % quadrupled subsequent risk (OR 4.48, 95 % CI 2.66-7.54; I² = 0 %). Pelvic obliquity ≥10° was associated with increased risk in a single cohort (OR 2.70, 95 % CI 1.34-5.46) and should be regarded as suggestive pending replication. No consistent effects were found for sex, gestational age or CP subtype. Approximately four in ten children with CP, and more than two thirds of those in GMFCS IV-V, develop clinically important hip displacement without targeted intervention. GMFCS IV-V status and an early MP ≥ 30 % are robust, actionable triggers for intensifying hip surveillance to six-monthly radiography; pelvic obliquity ≥10° may further stratify risk but requires confirmation. Uniform MP thresholds, time-to-event analyses and reporting of modifiable exposures are needed in future multicenter cohorts to refine preventive care.

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.