It has recently been reported that the transverse
acetabular ligament (TAL) is helpful in determining the position
of the acetabular component in total hip replacement (THR). In this
study we used a computer-assisted navigation system to determine
whether the TAL is useful as a landmark in THR. The study was carried
out in 121 consecutive patients undergoing primary THR (134 hips),
including 67 dysplastic hips (50%). There were 26 men (29 hips)
and 95 women (105 hips) with a mean age of 60.2 years (17 to 82)
at the time of operation. After identification of the TAL, its anteversion
was measured intra-operatively by aligning the inferomedial rim
of the trial acetabular component with the TAL using computer-assisted
navigation. The TAL was identified in 112 hips (83.6%). Intra-observer reproducibility
in the measurement of anteversion of the TAL was high, but inter-observer
reproducibility was moderate. Each surgeon was able to align the trial component according
to the target value of the angle of anteversion of the TAL, but
it was clear that methods may differ among surgeons. Of the measurements
of the angle of anteversion of the TAL, 5.4% (6 of 112 hips) were
outliers from the safe zone. In summary, we found that the TAL is useful as a landmark when
implanting the acetabular component within the safe zone in almost
all hips, and to prevent it being implanted in retroversion in all
hips, including dysplastic hips. However, as anteversion of the
TAL may be excessive in a few hips, it is advisable to pay attention
to individual variations, particularly in those with severe posterior
pelvic tilt. Cite this article:
