Does patellar ligament length change after dome-type high tibial osteotomy?

This study investigates whether there was a shortening of the patellar ligament--which is seen on other techniques--after dome-type high tibial osteotomy (HTO). Forty patients who had undergone unilateral HTO for primary knee arthrosis were retrospectively reviewed. Maquet barrel-vault dome-type HTO associated with a lower segment fibular osteotomy was used as the operative technique. To allow early mobilization, only a simple Charnley external fixator was used. The mean interval between operation and final radiographic examination was 55 months (range: 11 to 131 months). The pre-operative and postoperative Insall-Salvati index (IS), Blackburne-Peel index (BP), and Caton-Deschamps index (CD) were calculated. With respect to pre-operative measurements, a significant decrease in all indices was observed postoperatively. The mean pre-operative IS index was 1.03 and this changed to 0.90 postoperatively; the mean pre-operative BP index was 0.86 and became 0.80 postoperatively; and the mean pre-operative CD index was 0.97 and this became 0.90 post-operatively. Except for the IS index, BP and CD indices were in correlation with each other both pre-operatively and postoperatively. The length of the follow-up period did not have a significant effect on the patellar ligament changes. Dome osteotomy, and an external fixator to allow early mobilization, does not prevent patellar ligament shortening.