[AI-HIP system for prosthesis size, global femoral offset and osteotomy in total hip arthroplasty]

To explore planning effect of AI-HIP assisted surgical planning system in primary unilateral total hip arthroplasty (THA) and its influence on clinical outcomes.

A retrospective analysis was conducted on clinical data of 36 patients who underwent their first unilateral THA from March 2022 to November 2022 and continuously used AI-HIP system (AI-HIP group), including 16 males and 20 females, aged from 43 to 81 years old with an average of (62.2±10.9) years old. According to the matching principle, 36 patients who were planned by the traditional template method at the same period were selected as the control group, including 16 males and 20 females, aged from 40 to 80 years old with an average of (60.9±12.1) years old. The accuracy between two groups of prostheses were compared, as well as the combined eccentricity difference between preoperative planning and postoperative practice, lower limb length difference, osteotomy height from the upper edge of the lesser trochanter and top shoulder distance to evaluate planning effect. Harris score and visual analogue scale (VAS) were used to evaluate clinical efficacy.

Both groups were followed up for 12 to 18 months with an average of (14.5±2.1) months. The complete accuracy and approximate accuracy of acetabular cup and femoral stalk prosthesis in AI-HIP group were 72.2%, 100%, 58.3%, 88.9%, respectively, which were better than 44.4%, 83.3%, 33.3%, 66.7% in control group (P<0.05). There was no statistical significance in planning of femoral head prosthesis size (P>0.05). The actual combined eccentricity difference and combined eccentricity difference (practical-planning) in AI-HIP group were 1.0(0.2, 2.4) mm and 1.1(-2.1, 3.2) mm, respectively;which were better than 3.0 (1.4, 4.9) mm and 3.5 (-1.6, 6.5) mm in control group (P<0.05). There was no significant difference between two groups in actual osteotomy height of the upper margin of the lesser trochanter (P>0.05). In AI-HIP group, the actual difference of lower extremity length after surgery, the difference of lower extremity length (practical-planning), osteotomy height from the upper margin of lesser trochanter (practical-planning), actual topshoulder distance after surgery, and topshoulder distance (practical-planning) were 1.5 (0.2, 2.8), 1.1 (-0.3, 2.2), 2.1(-2.3, 4.1), (15.3±4.1), 2.2(-4.8, 0.3) mm, respectively;which were better than control group of 2.6(1.3, 4.1), 2.5 (0.3, 3.8), 5.8(-2.4, 7.7), (13.0±4.3), -5.7(-9.4, -2.2) mm(P<0.05). At final follow-up, there were no significant differences in Harris scores of pain, function, deformity, total scores and VAS between two groups (P>0.05). The range of motion score was 4.8±0.6 in AI-HIP group, which was higher than that in control group (4.4±0.8)(P<0.05).

Compared with traditional template planning, AI-HIP assisted surgical planning system has good accuracy in predicting the prosthetic size of the acetabular cup and femoral stalk, restoring joint eccentricity, planning lower limb length, osteotomy height and top shoulder distance on the first unilateral THA, and the clinical follow-up effect is satisfactory.