Navigated Total Knee Arthroplasty (TKA) is a new technique in our hospital. Any new procedure can be associated with both technical difficulties and difficulties due to patient and theatre staff expectations. The aim of this study was to demonstrate our learning curve and assess patient and staff acceptance. We highlight common technical problems unique to navigation and offer our solutions.

A prospective study of 231 consecutive Emotion TKA were implanted over a 30 month period with Orthopilot version 4.2 Navigation system using soft tissue management (BBraun Aesculap, Tutlingen). They were done by a single knee surgeon previously experienced only in non-navigated TKA. Patient height and weight were measured preoperatively and the BMI calculated. Tourniquet times were recorded digitally with fixed timing criteria. Informed consent was obtained.

Our results showed a significant decrease of tourniquet time with experience (p=< 0.0001) with other possible factors being preoperative deformity and BMI. There was full patient acceptance with the exception of the first patient. The surgical team had to modify patient positioning on the operating table, setup of the theatre and navigation equipment, placement of the scrub staff and delegation of tasks.

Navigated Emotion TKA with Orthopilot software provided a comfortable learning curve. It was readily acceptable to patients and staff and has been adopted as our standard practice. The discussion of problems and the introduction of solutions had a positive effect on building our team. Further investigation is needed to elucidate other variables that affect the tourniquet time.

Valgus knees present a surgically demanding challenge. Dissimilar bone and soft-tissue deformities compared to varus knees complicate restoration of proper alignment, positioning of components, and attainment of joint stability. Our study examined the relationship between tourniquet time and valgus deformity.

A prospective study of all valgus knees were implanted over a 30 month period with Emotion Ortho-pilot version 4.2 Navigation system (BBraun Aesculap, Tutlingen). They were done by a single knee surgeon. Tourniquet times (TT) were recorded digitally with fixed timing criteria. The software recorded all pre- and post-operative deformities. We performed the lateral parapatella approach for all valgus knees. No patella resurfacing was done but all tibiae were cemented.

There were a total of 56 valgus knees (1° to 22°, Mean 5.9°, SD 4.9). The TT varied from 42 min to 121 min (mean 72 min, SD 17.4). There was a statistically significant relationship between TT and Valgus deformity. Tourniquet Time = 59.6 + 2.1 * Pre-operative Valgus (p= < 0.0001, R² = 36.4%)

Thirty six percent of the observations were explained by this analysis. Other factors will need to be considered in future studies. This equation can be used as a guide in the allocation of theatre time. It applies to a specific surgical team and we would expect different teams to have different coefficients. This may be useful in comparisons of different teams.