[Application of preoperative digital-template planning in total hip arthroplasty via direct anterior approach]

To investigate the accuracy of preoperative digital-template planning in total hip arthroplasty (THA) via direct anterior approach (DAA) and its effect on the short-term effectiveness.

The clinical data of 77 patients (109 hips) with osteonecrosis of femoral head who underwent THA via DAA between January 2016 and May 2018 was retrospectively analyzed. According to the type of template, patients were divided into digital-template group (group A, 40 patients, 56 hips) and conventional-template group (group B, 37 patients, 53 hips). There was no significant difference in age, gender, body mass index, the stages of osteonecrosis of femoral head, and preoperative Harris hip score (HHS) ( P>0.05). The operation time, intraoperative blood loss, frequencies of intraoperative fluoroscopy, and complications were recorded. Otherwise, the consistency rate of preoperative planning and practical prosthesis size was analyzed. Position of acetabular prosthesis and femoral prosthesis alignment were measured on anteroposterior X-ray film of the pelvis at 3 months after operation. HHS was used to evaluate clinical function.

The consistency rate of preoperative planning and practical acetabular prosthesis size was significantly higher in group A (80.4%, 45/56) than that in group B (62.3%, 33/53), showing significant difference ( χ ²=4.38, P=0.04). But there was no significant difference in the consistency rate of preoperative planning and practical femoral prosthesis size between group A (83.9%, 47/56) and group B (79.2%, 42/53）( χ ²=0.40, P=0.53). The prosthesis abductions were (40.7±6.4)° in group A and (38.8±7.3)° in group B; the femoral prosthesis alignment deviations were (0.1±1.8)° in group A and (0.3±1.7)° in group B. There was no significant difference in the prosthesis abduction and femoral prosthesis alignment deviation between 2 groups ( P>0.05). No prosthesis sinking or loosening occurred during follow-up. The operation time and frequencies of intraoperative fluoroscopy were less in group A than those in group B ( P<0.05). But there was no significant difference in intraoperative blood loss between 2 groups ( t=1.92, P=0.06). The complication occurred in 1 hip of group A and 6 hips of group B, with no significant difference ( P=0.06). All patients were followed up 6-22 months (mean 13.8 months) in group A and 6-24 months (mean, 14.6 months) in group B. At last follow-up, the HHS scores were 91.8±3.1 in group A and 92.6±4.2 in group B, and the difference was not significant ( t=1.14, P=0.26).

Preoperative digital-template planning in THA via DAA is accurate, which can reduce the operation time and frequencies of intraoperative fluoroscopy without enhancing the risk of complication.