Abstract
This paper reports a series of comparative tests in-vitro that examined how lateral meniscectomy and meniscal allografting affected tibio-femoral joint contact pressures. 8 Cadaver knees (age range 81 – 98 years) were loaded in axial compression in an Instron materials testing machine up to 700N for 10 seconds and pressure maps obtained from the lateral compartment using Fuji Prescale film inserted below the meniscus. This was repeated after meniscectomy, then after meniscal allografting with fixation by a bone plug for the insertional ligaments, plus peripheral sutures. Finally, the pressure when the allograft was secured by peripheral sutures alone was measured.
Meniscectomy caused a significant increase in peak contact pressures (p=0.0002). Both of the reconstructive methods reduced the peak contact pressures significantly below that of the meniscectomised knee (p=0.0029 with bone block; p=0.0199 with sutures alone). A significant difference was not found between the peak contact pressures after the reconstructions and that of the intact knee (p=0.1721 with bone block; p=0.0910 with sutures alone). The peak pressures increased slightly when the allografts were converted from bone block to suture-only fixation (p=0.0349).
The principal finding was that both of the meniscal allograft insertion techniques reduced the peak contact pressure significantly below that of the meniscectomised knee, so that it did not then differ significantly from the peak contact pressure in the intact knee. When the two fixation methods were compared, the loss of the bone plug attachment caused a small increase in peak pressure.
This study suggests that meniscal allografting should have a chondroprotective effect and that there is a small advantage from adding bony fixation to suture fixation.
