Abstract
Introduction
Total knee arthroplasty (TKA) has proven to be cost-effective and efficative in the treatment of osteoarthritic knees. Although traditional computer navigation systems improve implant placement, they require fixation of the femoral and tibial reference arrays for software recognition using anchoring pins. This increases the risk of bony fracture, pin sites infection and osteomyelitis. Our study aims to investigate the accuracy of a new inless navigation system (Brainlab VectorVision Knee 2.5 Navigation System) that would avoid these complications.
Methods
119 patients were prospectively recruited over a year. These patients all underwent a primary TKA by a senior surgeon who performs more than 200 TKAs per annum. They were divided into two surgical technique arms. In Group 1, 74 patients underwent TKA using conventional techniques. In Group 2, 45 patients underwent TKA using a pinless navigation system.
Post-operative films were taken and three radiographic measurements were measured: 1) Hip-Knee-Ankle Angle (HKA); 2) Coronal Femoral-Component Angle (CFA); 3) Coronal Tibia-Component Angle (CTA) (Figure 1). Two reviewers blinded to the surgical method performed the measurements on the radiographic films on two separate occasions.
Results
There was no significant difference between the two groups for age, BMI, gender and side of operated knee. Similarly, there was no difference between the duration of surgery and length of hospital stay in both groups.
The mean HKA and CFA were significantly more accurate in the pinless navigation group compared to the conventional group (p=0.003 and p<0.001 respectively). There was no significant difference between the two groups for CTA (Table 1).
There was a significant improvement in reducing the number of outliers for lower limb alignment (HKA) and implant placement (CFA and CTA) for the pinless navigation group compared to the conventional group (p<0.05) (Table 2).
The radiographic measurements of CFA and CTA on post-operative X-rays were similar to the intra-operative readings obtained from the pinless navigation system (p>0.05) (Table 3).
Conclusion
This new pinless navigation system improves lower limb alignment and implant placement in TKA patients, without the risk of pin-related bony fracture, pin sites infection and osteomyelitis.
