Stereophotogrammetric surface anatomy of the anterior cruciate ligament's tibial footprint: Precise osseous structure and distances to arthroscopically-relevant landmarks.

BACKGROUND: While femoral tunnel malposition is widely recognized as the main technical error of failed anterior cruciate ligament (ACL) surgery, tibial tunnel malposition is likely underrecognized and underappreciated. PURPOSE: To describe more precisely the qualitative and quantitative anatomy of the ACL's tibial attachment in vitro using widely available technology for stereophotogrammetric surface reconstruction, and to test its applicability in vivo. METHODS: Stereophotogrammetric surface reconstruction was obtained from fourteen proximal tibias of cadaver donors. Measurements of areas and distances from the center of the ACL footprint and the footprint of the obtained bundles to selected arthroscopically-relevant anatomic landmarks were carried out using a three-dimensional design software program, and means and 95% confidence intervals were calculated for these measurements. Reference landmarks were tested in three-dimensional models obtained with arthroscopic videos. MAIN FINDINGS: The osseous footprint of the ACL was described in detail, including its precise elevated limits, size, and shape, with its elevation pattern described as a quarter-turn-staircase-like ridge. Its internal indentations were related to inter-spaces identified as bundle divisions. Distances from the footprint center to arthroscopically relevant landmarks were obtained and compared to its internal structure, yielding a useful X-like landmark pointing to the most accurate placeholder for the ACL footprint's "anatomic" center. Certain structures and reference landmarks described were readily recognized in three-dimensional models from arthroscopic videos. CONCLUSIONS: Stereophotogrammetric surface reconstruction is an accessible technique for the investigation of anatomic structures in vitro, offering a detailed three-dimensional depiction of the ACL's osseous footprint.