[Computer assisted imaging guided total knee arthroplasty: preliminary clinical study of 46 cases]

To discuss the approach and curative effect of total knee arthroplasty by intraoperative digital 3D bone mode.

28 patients with bone arthritis, 7 with rheumatoid arthritis, 7 with ankylosing spondylitis, totally 46 patients with 54 knees affected, 29 males and 17 females, aged 48 (31 - 76), underwent total knee arthroplasty by digital 3D bone mode, including osteotomy, adjustment of soft tissue, and rotational positioning of prostheses. The operative time, hemorrhage and drainage 48 h after operation, and complication were observed. The pre-postoperative knee function was evaluated by HISS scoring system. The pre-postoperative range of motion of knee joint, and angle of KNA, variance of angle in exterior and interior stress and separation of joint space in tensile force, and postoperative rotational angle of tibia-femur prostheses were measured. X-ray tangential projection photography of patella was used to evaluate the apposition of patellofemoral joint. The postoperative curative effect was observed for 3 months.

No complication as injury of nerves and blood vessel, bone fracture, fat embolism and so on was observed. The operative time was 80 +/- 15 min per knee. The hemorrhage and drainage in 48 h was 550 +/- 60 ml per knee. The Hand Injury Severity Score (HISS) 2 weeks after the operation was (92 +/- 4), significantly higher than that before operation [(46 +/- 6), P < 0.01]. There were statistically significant differences in the KNA angle, variance of angle under exterior stress, interior stress, and separation of joint space in tensile force pre- and postoperatively (all P < 0.01). The postoperative rotational angle of tibia-femur prostheses was (4.2 +/- 0.4) degrees. The X-ray tangential projection photograph of patella showed excellent apposition of patellofemoral joint, and no dislocation and unsteadiness. The postoperative range of motion of knee joint was 120 degrees +/- 9 degrees 3 months after operation. No joint laxity was found.

Computer assisted imaging guidance actually and dynamically observe the changes of line of force of the lower limbs, knee joint rotational apposition and ligament balance, provides geometrical and morphological data and rebuild the knee joint bio-mechanically and anatomically, thus elevating the reproducibility of total knee arthroplasty and ensuring the safety of the system.