Comprehensive systematic review and meta-analysis of the semitendinosus muscle and tendon: global morphometry, sex differences, and surgical implications.

Abstract

The semitendinosus tendon (STT) is one of the most commonly harvested autografts for anterior cruciate ligament reconstruction. However, morphometric data describing its anatomical variability remain inconsistent across studies. To systematically review and quantitatively synthesize available evidence on the morphometric characteristics of the semitendinosus muscle and tendon across different populations and sexes. A systematic review and meta-analysis were conducted in accordance with PRISMA guidelines. Fifty-three studies were included overall. Of these, 46 studies with extractable quantitative data contributed to the meta-analysis, comprising 3,134 measured STTs, while 7 additional studies were included in the qualitative synthesis only. The pooled mean STT length across all studies was 27.41 cm (95% CI: 26.73-28.09). Shorter tendons were observed in females compared with males (26.57 cm vs 28.99 cm) and in Asian populations compared with European and North American cohorts (26.19 cm vs 28.79 cm and 27.93 cm, respectively). Cadaveric studies reported shorter lengths (25.56 cm) compared with intraoperative (28.16 cm) and ultrasound measurements (29.59 cm). The tendinous portion within the muscle belly averaged 11.75 cm, while the distal tendon from the musculotendinous junction to the pes anserinus measured 15.22 cm. This meta-analysis provides a comprehensive synthesis of STT morphology across populations. The findings highlight population- and sex-related variability and provide anatomical reference data that may assist in understanding STT morphology in the context of ligament reconstruction.