Abstract
Background Increased tibial slope has been shown to be associated with higher anterior cruciate
ligament (ACL) reconstruction failure rate. Little is known about the correlation
of tibial slope and anterior tibial translation in ACL deficient and reconstructed
knees as well as the correlation of tibial slope and ACL reconstruction outcome.
Purpose/Hypothesis The purpose of this study was to investigate the correlation of tibial slope with
anterior tibial translation and ACL reconstruction outcome. It is hypothesized that
increased medial tibial slope is associated with increased anterior tibial translation
in the ACL deficient knee. Medial tibial slope is neither expected to affect anterior
tibial translation in the ACL reconstructed knee nor short-term ACL reconstruction
outcome.
Materials and Methods A cohort of 104 patients with unilateral isolated ACL deficiency undergoing hamstring
ACL reconstruction by a single surgeon between 2002 and 2004 was followed up prospectively.
Preoperative data were collected including patient demographics, time to surgery,
subjective and objective International Knee Documentation Committee (IKDC) outcome
scores, as well as manual maximum anterior tibial translation measured with the KT-1000
measuring instrument. Medial tibial slope was assessed on long lateral X-rays using
the method described by Dejour and Bonnin (1994). Intraoperative data were collected
including meniscal integrity; postoperative data were collected at 1-year follow-up
including manual maximum anterior tibial translation (KT-1000 measured), and subjective
and objective IKDC scores.
Results A significant positive correlation was seen between medial tibial slope in ACL deficient
knees and KT-1000–measured anterior tibial translation (r = 0.24; p = 0.003). The positive relationship increased when meniscal integrity was factored
in (r = 0.33; p < 0.001). No significant correlation was seen between medial or lateral meniscal
integrity and KT-1000–measured anterior tibial translation (r = −18; p = 0.06). No significant correlation was seen between KT-1000–measured anterior tibial
translation and time to surgery. One year postoperatively, 82 patients were assessed,
while 26 patients were lost to follow-up; no significant correlation was found between
increased medial tibial slope and poor ACL reconstruction outcome measured by post-ACL
reconstruction anterior tibial translation (KT-1000) or subjective and objective IKDC
scores.
Conclusion Increased medial tibial slope is associated with increased (KT-1000 measured) anterior
tibial translation in ACL deficient knees. No significant correlation is found between
increased medial tibial slope and poor short-term ACL reconstruction outcome.
Keywords
ACL - slope - ACL failure
