Abstract
Intramedullary (IM) femoral alignment guide for unicondylar knee arthroplasty (UKA) is a classic and generally accepted technique to treat unicompartmental knee osteoarthritis. However, IM system has a risk of excessive blood loss, fat embolism and activation of coagulation.Moreover, the implant placement and limb alignment may be less accurate in IM for UKA than total knee arthroplasty. So we try to use extramedullary (EM) femoral alignment for UKA to avoid above disadvantages. To our knowledge, few current studies have been reported by now. We reported a series of cases treated through a newly developed EM technique and evaluated the accuracy of femoral component alignment and preliminary clinical results. Between January 2009 and January 2010, 11 consecutive patients(15 knees)consisting of 8 males and 3 females were enrolled. There were 7 cases in unilateral knee and 4 cases in bilateral knees. The mean age was 65.2 years (range 60∼72 years). Incision, surgical time, blood loss and complications were measured. The pre- and post operative function of the knees were evaluated by HSS score system. The pre- and postoperative femoral component alignment was measured and compared. All cases were followed up for average 15 months (10-22 months). The mean length of incision was 7.2cm (range 6 to 8cm), the mean surgical time was 115.0min(range 90 to 125min),the mean blood loss was 50.8ml (range 50 to 80ml). The mean preoperative HSS score increased from 75 (range 63 to 83) to 95 (range 88 to 97) postoperatively (p<0.05). All femoral components were within the recommended range for varus/valgus (±10 degree) and lexion/extension (±5 degree) angle. None had complications associated with reamed canal injury. By using our EM technique, we could achieve an accurate femoral component alignment and satisfactory clinical effect. However, strict comparison between EM and cconventional IM technique and large amount of cases are essential. Further mid- and long-term studies are required.
