Arthrometric examination showed a mean side to side difference (SSD) of 1.66 mm ±1.5. The mean Lysholm score was 87.2 ±12.5 and 22 patients had a B rating (nearly normal) on IKDC scoring. The Mark II Soffix group had a mean SSD of 1.23 mm ±1.3, a mean Lysholm score of 85.8 ±14.6 and IKDC B rating in 11/15. The lowest clinical scores were in 4 multiply operated knees but the SSDs were comparable with other groups. The Mark 1 Soffix group had a mean SSD of 2.0 mm ±1.6, Lysholm score of 84.6 ±14.3 and 13/16 had a B rating (IKDC). The smaller SSD in the Mark I Soffix was statistically significant (p<
0.05) when compared with the Mark I device. Multiply operated knees had worse IKDC and Lysholm scores (not statistically significant).
In 7 cases there was no enlargement, in 5 cases there was cylindrical enlargement, in 12 cases there was conical enlargement but no cavitation was noted. A maximum mean CSA of 33% ± 38.84 In addition the MRI scan showed no evidence of excessive granulation tissue ingrowth or synovial fluid between the graft and the tunnel wall. It would appear that micro-motion which is a major factor in tunnel enlargement is eliminated by the combination of a tight fitting graft, the strength and stiffness of the fixation device and highly accurate, low stress placement of the tibial tunnel. Post operative KT 2000 arthrometric testing of the mean side to side difference (SSD) was 1.71 mm ± 1.82