Abstract
Computer-assisted navigation during total knee replacement has been advocated to improve component alignment and hence reduce failure rates and improve quality of life. The technique involves the placement of trackers via pins placed in both the femur and tibia throughout the surgery. It has been proposed that complication rates are higher in knee arthroplasty when computer navigation is used, compared to when it is not, due to increased risks from the pin tracker sites. Potential risks from pin sites include infection, fractures of the tibia or femur and pin site pain. In this study we present the post-operative complication rates related to pin tracker sites of computer navigated knee arthroplasty from a single surgeon at one centre.
A database was compiled including all patients undergoing knee arthroplasty with computer navigation between January 2009 and December 2013 performed by a single surgeon at one centre. A retrospective study was undertaken having identified a total of 321 patients (642 pin sites) with 287 having undergone total knee replacement, 29 Uni-condylar knee replacement and five having undergone patellofemoral knee replacement. There 131 males and 190 females with a mean age of 69.4 [range 48–89]. There were no exclusions. The patient's notes were reviewed for any complications that occurred as a result of pin sites including infection, pin site pain and fracture.
Only one patient (0.03%) was identified with a superficial pin site infection that was successfully managed with oral antibiotics only. There were no fractures or other complications identified in any of the other patients.
In this series, the complication rates resulting from pin tracker sites was very low suggesting computer navigation does not increase the risks of knee arthroplasty. There were no cases of femoral or tibial fractures in this series, as have previously been reported. It is therefore likely that the technique of pin site placement is important in limiting the risk of complications. In this series a standard technique was used in all cases. Stab incisions are always used rather than a percutaneous technique and the wounds closed with clips and protected with dressings at the end of the surgery. Uni-cortical drilling is sufficient to provide stability of the trackers intra-operatively and minimises the risk of thermal necrosis therefore bi-cortical placement is avoided. Self-drilling pins are used on power and inserted perpendicular to the bone on high torque and low speed. The tourniquet is not inflated until after the pins have been inserted. It is thought that using this technique offers a safe method of pin tracker placement ensuring low complication rates.
