ACL reconstruction is successful in restoring sagittal stability of the knee but has been less consistent in restoring rotational stability. Increasing coronal graft obliquity improves rotational constraint of the knee in cadaveric biomechanical models. The purpose of this study was to determine whether there is a correlation between coronal graft alignment and tibial rotation during straight line activities.

Seventy-four patients who had undergone ACL reconstruction using a transtibial technique were evaluated. They came from three distinct time periods during which the operating surgeon had deliberately changed the position of the femoral tunnel to progressively achieve a more oblique graft alignment in the coronal plane. Post-operative radiographs were analyzed for the coronal graft orientation and femoral and tibial tunnel positions. Tibial rotation was measured during level walking (n=74) and single-limb landing (n=42) tasks using a motion analysis system. Radiographic measurements of graft and tunnel orientation were correlated with rotational excursion of the knee recorded during these tasks. No correlations were found between knee rotational excursion and either the coronal tibial tunnel angle or the coronal graft angle during level walking. For the single-limb landing task, a significant negative correlation was observed between the coronal angle of the tibial tunnel and rotational excursion (r=−0.3, p=0.05) i.e. increasing tunnel obliquity was associated with decreasing rotational excursion. For the coronal angle of the ACL graft, the correlation was also negative, but was not significant (r=−0.24, p=0.12).

Increases in graft obliquity in the coronal plane were associated with reduced tibial rotational excursions during single limb landing. These findings support the notion that ACL graft orientation may play a role in rotational kinematics of the ACL reconstructed knee, particularly during higher impact activities.

Purpose: To comapre the clinical results and costs of a non-modular, all-polyethylene tibial component versus a modular tibial component in patients older than 70.

Methods: A multi-center (London, Ontario; Halifax, Nova Scotia) prospective randomized clinical trial was designed to compare modular metal-backed versus an all polyethylene tibial component in patients over 70 years. Primary outcome measures include Knee Society Clinical Rating System, WOMAC, SF-12, Kaplan-Meier Survivorship.

Results: Between September 1995 and August 1997, 127 total knee replacements (Genesis I, Smith & Nephew) were randomized to receive either a non-modular (all-polyethylene) tibial baseplate or a modular (metal-backed) baseplate. Minimum follow-up was 8 years. Excluding patients who died or became disabled due to medical problems, no consistent significant differences have been seen in regard to the WOMAC, SF-12, and Knee Society scores between the two groups. Kaplan-Meier Survivorship is 93% with a mean survival time of 9.36 years for the non-modular group and 94.1% with a mean survival time of 9.49 years for the modular group. The cost saving in the non-modular group was approximately $800 per TKR without any compromise in clinical outcome.

Conclusions: There was no difference found in the clinical outcome scores between an all polyethylene tibial baseplate and a modular tibial component in patients over 70 years of age. Non-modular tibial baseplates have a list price of 23–65% the cost of their modular counterparts. A high mortality rate exists in this age group limiting the numbers available for longer term review. The use of an all polyethylene tibial component is a cost effective and clinically successful alternative in the older patient requiring total knee replacement.