Abstract
Introduction
The incorporation of computer navigation in total hip arthroplasty (THA) has been much slower then for total knee arthroplasty (TKA). Computer navigation has proven itself in the realm of TKA but still has yet to advance in THA. The reasons for this include the lack of ease of incorporation, accuracy and precision, and the addition of overall operative time. Another reason for this lack of progress is that a majority of THA's are done with the patient in the lateral position through a posterior or lateral approach making the tracker placement and the registration process somewhat cumbersome. In the direct anterior approach the patient is in the supine position, which accommodates pelvic tracker placement and significantly facilitates the registration process. At our institution we use the direct anterior approach and computer navigation on all of our primary THA's. We hypothesized that computer navigation facilitates cup placement and leg length determination with out significantly increasing our operative time.
Materials and Methods
This was a prospective study comparing a consecutive series of 150 computer navigated total hips to a consecutive series of 150 none navigated total hips. The two groups were similar by age, sex, and BMI. Operative times were collected using our secure online database. The start and stop of operative time was incision to final reduction respectively. Post operative radiographs were analyzed using TraumaCad 2.0 (Voyant Health, Columbia, MD). Cup angle and leg length were measured on A/P pelvic views. Simple descriptive statistics and t-tests were used to analyze data.
Results
There were a total of 134 men and 166 women with a pre operative diagnosis of osteoarthritis. The conventional cohort contained 64 men and 86 women with an average age of 65.6 (26.1-91.3) and BMI of 29.3(15.7-50.9). The computer navigation cohort contained 70 men and 80 women with an average age of 65.5 (44.8-90.2) and BMI of 28.6 (17.5-44.0). The average operative times of the conventional and computer navigation cohorts were 62.4 min (33-165) and 53.0 min (38-63) (p<0.0001) respectively. The average cup angle was 37.2 (25-52) for the conventional cohort and 41.0 (26-55) for the computer navigation cohort (p=0.0046). The leg length discrepancy average was 3.2 mm (-13.0mm to 13.0mm) for the conventional cohort and 2.1 mm (-6.0mm to 15.0mm) for the computer navigation cohort (p=0.0012).
Conclusion
The results from our study suggest that computer navigation is easy to incorporate when utilizing a direct anterior approach and in fact shortens the operative time. The accuracy and precision of cup angle placement and leg length discrepancy are comparable to our conventional method but appears to be slightly improved with computer navigation. Although more work is needed to progress this promising technology, we feel that incorporating computer navigation for hip surgery in the supine position is simple and of great value.
