Abstract
Robotic-guided arthroplasty procedures are becoming increasingly common. We introduced a new computer-navigated TKA system with a robotic cutting-guide into a community-based hospital and characterized the accuracy and efficiency of the technique.
We retrospectively reviewed our first 100 cases following IRB approval. Tourniquet time, intraoperative bone-cut accuracy and final limb alignment as measured by the computer were collected and divided into consecutive quartiles: Groups I, II, III, and IV; 25 cases per group. All resections were planned neutral to the mechanical axis. Postoperative component alignment and overall mechanical axis limb alignment were also measured on standing long-leg radiographs by two independent observers at minimum six weeks follow-up. Radiographic alignment was available for 62 cases.
Intraoperative Computer Data: Bone-cut accuracy was a mean 0.1° valgus, SD±0.8° for both the femur and tibia (range, femur: 2.0° valgus to 1.5° varus; range, tibia: 3.5° valgus to 1.5° varus). Final limb alignment was within 3° for 98% (97/99) of cases (range: 2.0° valgus to 3.5° varus). Radiographic Alignment: Pre-operative mechanical alignment ranged from −14.5° valgus to 21.5° varus. Radiographic femoral and tibial component alignment was within 3° of neutral in 98.4% of cases (61/62). Final limb alignment was within 3° for 87.1% (54/62) of cases (range: 4.5° varus to 4.5° valgus). Learning curve: Mean tourniquet time was 60minutes ±9.9SD (range 46–79) for Group I and 49.5minutes for Groups II, III, and IV (range 35–68), p = 0.0001. Mean tourniquet time for the first ten and second ten procedures was 65±10.6minutes and 55±8.3minutes, respectively, p = 0.034. There were no differences in accuracy among the four groups (p>0.05).
Imageless computer-navigated TKA with a robotic cutting guide allowed one surgeon to make bone resections within 3° of neutral in 98% of cases. Radiographic limb alignment was less precise, which is consistent with the known limitations inherent to this measurement technique. Surgeons can expect this procedure to take 15 additional minutes during the first ten cases and five additional minutes during the second ten cases on average, without compromising accuracy.
