Ligament imbalance in prosthetic correction of severe arthrosis of the varus knee [La problematica legamentosa nella protesizzazione del grave ginocchio varo artrosico]

Aim. We evaluated the efficacy of noncemented implantation of the TACK prosthesis for axial deviation of the lower limb with degenerative arthrosis in which mediolateral ligament imbalance requires rebalancing to restore joint stability and adequate range of function. Methods. At our unit from 1996 to 2002, 103 TACK Link knee prostheses were implanted for varus knee arthrosis with deformities greater than 8°. The case series comprised 18 men and 81 women; mean age 70 years. In 53 cases the right knee, in 40 the left knee, and in 10 both knees were treated. All operations were performed according to the same protocol: no cementation of the components, no prosthetic correction of the patella, the same surgeon, standard rehabilitation program with passive mobilization the first day and deambulation after 7 days. Results. Evaluation based on the HSS score profiles showed results that were excellent in 60 cases, good in 26, satisfactory in 16 and poor in 1. Stability assessment showed grade 0 in 64 cases, grade I in 30 and grade II in 9. No cases of residual grade III laxity were found. The one poor result was due to luxation of a polyethylene component that first required reoperation for thicker positioning and then reimplantation using a semirestraining rotational Endomodel prosthesis. Conclusions. Long-term follow-up results suggest that the TACK system is a valuable device in the treatment of arthrosis of the varus knee with imbalance of the mediolateral capsule ligaments.