The accuracy and reliability of preoperative digital 2D templating in prosthesis size prediction in uncemented versus cemented total hip arthroplasty: a systematic review and meta-analysis

The purpose of this study was to compare the accuracy and the inter-and intra-observer reliability of preoperative digital 2D templating in prosthesis size prediction for the planning of cemented or uncemented THA. This study was registered in the NIHR PROSPERO database (ID: CRD420BLINDED) and conducted according to the PRISMA guidelines. A search of electronic databases in March 2021 found 29 papers overall. The quality of evidence was assessed using the IHE Quality Appraisal of Case Series Studies Checklist and the CASP Randomised Controlled Trials Checklist. A meta-analysis was conducted, and the accuracy was presented as proportions and the inter-and intra-observer reliability were measured using intraclass correlation coefficients (ICC). Accuracy within one prosthesis size (+/- 1) for cemented stems was 0.89 (95% confidence interval (CI) 0.83-0.95), cemented cups 0.78 (95% CI 0.67-0.89), uncemented stems 0.74 (95% CI 0.66-0.82) and uncemented cups 0.73 (95% CI 0.67-0.79) (test of group differences: p = 0.010). Inter-observer reliability (ICC) for uncemented cups was 0.88 (95% CI 0.85-0.91), uncemented stems 0.86 (95% CI 0.81-0.91), cemented stems 0.69 (95% CI 0.54-0.84) and cemented cups 0.68 (95% CI 0.55-0.81) (test of group differences: p = 0.004). Due to lack of data, intra-observer reliability (ICC) could only be calculated for uncemented prostheses, which for the stems was 0.90 (95% CI 0.88-0.92) and for the cups was 0.87 (95% CI 0.83-0.90) (test of group differences: p = 0.124). The accuracy of preoperative digital templating is greater for cemented prostheses, but the inter-observer reliability is greater for uncemented prostheses. The intra-observer reliability showed a high level of agreement for uncemented prostheses.