Abstract
BackgroundMechanical alignment guides are designed to compensate for variations in the valgus alignment angle; however, these guides may not be adequate when a patient has coronal alignment with marked bowing deformity. Previous study demonstrates better radiographic results, but the clinical benefits are a matter of speculation. The aim of this study was to investigate whether radiographic benefits of computer-assisted surgery total knee arthroplasty (CAS-TKA) would translate to clinical outcomes.MethodsPatients with osteoarthritis and coronal alignment with marked bowing deformity who underwent total knee arthroplasty (TKA) at our institution between January 2005 and June 2012 were entered into this retrospective study. Patients were divided into three groups: patients with coronal alignment with marked bowing deformity treated with CAS-TKA; with coronal alignment with marked bowing deformity treated with conventional TKA; and without marked coronal bowing deformity treated with conventional TKA. The computer-assisted navigation and the conventional technique were then compared by radiographic parameters. The International Knee Society (IKS) scores and patellar score were obtained for all patients preoperatively and at the last follow-up visit.ResultsOne hundred and thirty-seven patients (198 knees) met the inclusion criteria. For patients with osteoarthritic knees with marked femoral bowing deformity, the reconstructed mechanical axis (MA) was significantly closer to normal in the CAS-TKA group (P = 0.002) than in the conventional group. Significant differences in the reconstructed MA after conventional TKA were noted between patients without bowing and those with bowing (P = 0.003). Using the patellar score and IKS score, at a mean follow-up of 52.2 months, the differences did not achieve statistical significance among the three groups.ConclusionsCAS-TKA was an effective alternative for obtaining proper alignment in patients with coronal alignment with marked bowing deformity. However, there was no statistically significant difference in clinical function between patients treated with CAS-TKA and conventional TKA. Long-term follow-up will be needed to determine if the improvement in radiographic results translates to better clinical outcomes.
Highlights
Patient factors, prosthetic design, and surgical technique all affect the survivorship of total knee arthroplasty (TKA) [1,2,3,4,5,6]
Studies using finite element models as well as long-term survival studies confirm that the longevity of the implants and optimal long-term outcomes depend on the accuracy of bone cuts and proper restoration of the mechanical axis of the leg [7,8,9,10,11,12]
The prevalence of coronal alignment with marked bowing deformity in patients with end-stage osteoarthritis of the knee is relevant in Asian populations because this deformity reportedly affects as many as 62% of Asians [18,19,20]
Summary
Prosthetic design, and surgical technique all affect the survivorship of total knee arthroplasty (TKA) [1,2,3,4,5,6]. The prevalence of coronal alignment with marked bowing deformity in patients with end-stage osteoarthritis of the knee is relevant in Asian populations because this deformity reportedly affects as many as 62% of Asians [18,19,20]. Such deformities will alter the desired angle between the mechanical and anatomical axis of the lower extremity and thereby jeopardize positioning of the femoral component and postoperative mechanical axis of the limb [18,19,20,21,22]. The aim of this study was to investigate whether radiographic benefits of computer-assisted surgery total knee arthroplasty (CAS-TKA) would translate to clinical outcomes
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