PurposeThe purpose of this study is to compare and analyze the precision of optical and electromagnetic navigation systems in total knee arthroplasty (TKA).Materials and MethodsWe retrospectively reviewed 60 patients who underwent TKA using an optical navigation system and 60 patients who underwent TKA using an electromagnetic navigation system from June 2010 to March 2012. The mechanical axis that was measured on preoperative radiographs and by the intraoperative navigation systems were compared between the groups. The postoperative positions of the femoral and tibial components in the sagittal and coronal plane were assessed.ResultsThe difference of the mechanical axis measured on the preoperative radiograph and by the intraoperative navigation systems was 0.6 degrees more varus in the electromagnetic navigation system group than in the optical navigation system group, but showed no statistically significant difference between the two groups (p>0.05). The positions of the femoral and tibial components in the sagittal and coronal planes on the postoperative radiographs also showed no statistically significant difference between the two groups (p>0.05).ConclusionsIn TKA, both optical and electromagnetic navigation systems showed high accuracy and reproducibility, and the measurements from the postoperative radiographs showed no significant difference between the two groups.

Purpose: Our purpose was to assess the results of lunate excision and tendon ball implantation with temporary scaphocapitate fixation for Lichtman stage IIIB Kienböck's disease in middle-aged patients. Methods: Ten patients with Lichtman stage IIIB Kienböck's disease who underwent lunate excision and tendon ball implantation and followed up at least 24 months were analyzed. There were 4 males and 6 females. The mean age at the time of surgery was 55.4 years (range, 48-67 years), and follow-up period ranged from 24 to 68 months (mean, 46 months). Radiocarpal joint pain, grip strength, return to daily living activity, range of motion were evaluated and radiologic findings of preoperative, postoperative and last follow-up were evaluated. Results: All patients returned to daily living activity after 6 months of surgery. At the last follow up, 8 patients had no pain and 2 patients experienced mild pain occasionally. The mean improvement of extension arc was 14.5°, and the mean flexion arc improved 8.5°. The mean grip strength was 88% of unaffected side. The mean carpal height ratio was 0.49 preoperatively, 0.47 at final followup. No patients showed osteoarthritis change at the last follow-up. The mean Cooney's wrist function were 83, 4 patients had excellent, 4 had good, and 2 had fair. Conclusion: Lunate excision and tendon ball implantation with temporary scaphocapitate fixation for Lichtman stage IIIB Kienböck's disease in middleaged patients showed satisfactory clinical, functional and radiological results.So this can be a reasonable treatment option.