Anatomy of the anterior cruciate ligament related to hamstring tendon grafts. A cadaveric study

BackgroundThe aim of modern techniques for anatomic reconstruction of the ACL is to reproduce ACL footprints, in order to restore anatomy and therefore normal biomechanics. Is there an oversizing of the hamstring grafts related to ACL dimensions?MethodsTwenty-two paired cadaver knees were dissected. ACL dimensions at mid-portion and ACL footprints were measured after removing the synovial membrane.Hamstrings were harvested and prepared in a quadruple strand graft in order to measure the mean circumference.ResultsThe average ACL tibial and femoral insertion site areas of the ACL were 117.9 mm2 (range, 90 to 130 mm) and 96.8 mm2 (range, 80 to 121 mm), respectively.The average diameter and cross sectional area of the ACL tendon at mid-portion were 6.1 mm (range, 5 to 7 mm) and 29.2 mm2 (range, 20 to 38.9), respectively. The average diameter and cross-sectional area of the 4-stranded hamstring tendons were 6.7 (range, 5 to 8) and 35.3 mm2 (range, 20 to 50), respectively.There was a correlation between the 4-stranded hamstring grafts and ACL dimensions (footprints, ligament at mid substance, p < 0.01). The cross sectional area of hamstring tendon was significantly larger than the ACL area at mid-portion (mean 20.9%, p < 0.05).ConclusionWith current ACL reconstruction techniques, the graft is oversized at a mean of 21%, despite a good correlation between the ACL and the hamstring tendon, especially among small subjects and women. The question arises whether the anatomic reconstruction of the ACL should fill ACL footprints or mimic the ligament itself.Clinical relevanceHamstrings grafts are significantly larger than native ACL.