Preoperative measurement of femoral head using 3D-CT spherical fitting technique for the guidance of femoroplasty in arthroscopic treatment of cam-type femoroacetabular impingement: a cohort validation

Purpose Arthroscopic femoroplasty is the primary treatment of Cam-type femoroacetabular impingement (FAI), in which the most important problem is how to evaluate Cam deformity sufficiently and remove osteophytes accurately. This study aimed to measure Cam deformity in each patient with 3D-CT spherical fitting technique, plan the resection range of Cam deformity preoperatively, so as to achieve precise resection intraoperatively and evaluate the prognosis. Methods Patients of Cam-type FAI and underwent hip arthroscopy during August 2024 to February 2025 were involved. Preoperatively, all patients underwent CT scan, the spherical fitting measurement was performed to plan the resection range of Cam deformity, and the surgical operation was guided according to the plan. The post-operative alpha angle, femoral head-neck off-set ratio, as well as the mHHS and VAS at 3 and 6 months after the surgery were collected, and compared with that before the surgery. Results 29 patients were included and followed with no missing cases. The postoperative average alpha angle was 44.2 ± 4.1 degrees, significantly lower than that before surgery (75.3 ± 6.3) ( p = 0.017). The postoperative average femoral head-neck off-set ratio was 0.20 ± 0.04, significantly better than that before surgery (0.16 ± 0.06) ( p = 0.033). The average mHHS increased sequentially at 3 and 6 months after surgery, which was 73.2 ± 14.5 ( p = 0.015) and 77.9 ± 15.8 ( p = 0.010) respectively, were higher than that before surgery (52.5 ± 11.7). The average VAS decreased sequentially from 3.4 ± 0.9 preoperatively to 2.4 ± 0.6 ( p = 0.029) and 2.3 ± 0.8 ( p = 0.025) at 3 and 6 months after surgery ( p < 0.05). Conclusion The 3D-CT spherical fitting technique combined with the outside-in hip arthroscopy approach provided promising short-term clinical and imaging outcomes for Cam-type FAI. This combined method may represent a reliable and reproducible strategy for achieving precise cam resection in hip arthroscopy.