探讨设计一种三维打印定制无水泥间质型颈内弯干预假体的关键要点，并评估其在重建近端股骨超短骨段中的中期疗效。2015年10月至2021年1月，17名患者接受了具有颈内弯干预假体的3D打印定制无水泥间质型假体的重建手术。其中男性11例，女性6例，年龄范围10至76岁，平均年龄30.1岁。9例为骨肉瘤，4例为尤文肉瘤，2例为软骨肉瘤，1例为脂肪肉瘤，1例为肌纤维母细胞瘤。疾病持续时间为5至14个月，平均为9.5个月。Enneking分期中，16例为ⅡB期，1例为ⅢB期。手术前通过X线图像测量了股骨头中心至骨干中线及髋臼顶部的距离。此外，术后立即和最后一次随访时测量了颈内弯干预假体尖端至骨干中线及髋臼顶部的距离。颈干角度也在术前、术后立即和最后一次随访时进行测量。通过X线片、CT和Tomosynthesis-Shimadzu金属伪影减少技术（T-SMART）评估了骨-假体界面的骨整合情况和骨生长情况。评估了患者的生存状况、局部复发或远处转移的存在以及术后并发症的发生。使用肌肉骨骼肿瘤学会（MSTS）评分系统评估了术前和术后下肢功能的恢复情况，并使用视觉模拟评分（VAS）评估了疼痛缓解情况。 患者股骨截骨长度为（163.1±57.5）mm，剩余近端股骨长度为（69.6±9.3）mm，股骨截骨长度占总股骨长度的百分比为38.7%±14.6%。所有17名患者在术后经过25至86个月的随访，平均58.1个月。随访期间，1名患者在术后46个月因肺转移死亡，其余16名患者术后存活无肿瘤。没有发生周围假体感染、延迟切口愈合、无菌松动、假体骨折或周围性假体骨折等并发症。在X线和T-SMART评估中，未检测到植入假体的干预干根周围的微动或磨损迹象。所有颈内弯干预假体中观察到无显著放射学透明线，并且观察到骨成长进入骨-假体界面的放射学证据。与手术前相比，术后立即和最后一次随访时颈内弯干预假体尖端至骨干中线和髋臼顶部的距离没有显著差异（P>0.05），术后立即和最后一次随访时上述指标之间也没有显著差异（P>0.05）。不同时间点的颈干角度差异也无显著性（P>0.05）。最后一次随访时，MSTS评分为26.1±1.2，VAS评分为0.1±0.5，与手术前相比显著改善[分别为19.4±2.1和5.7±1.0]（t=14.735，P<0.001；t=21.301，P<0.001）。在最后一次随访时，没有患者使用拐杖或其他助行器辅助行走。3D打印定制无水泥间质型颈内弯干预假体是重建近端股骨恶性肿瘤切除后超短骨段的有效方法。手术可靠，术后下肢功能满意，并发症发生率低。

To explore the design points of a three-dimensional (3D) printed customized cementless intercalary endoprosthesis with an intra-neck curved stem and to evaluate the key points and mid-term effectiveness of its application in the reconstruction of ultrashort bone segments in the proximal femur.Between October 2015 and January 2021, 17 patients underwent reconstruction with a 3D printed-customized cementless intercalary endoprosthesis with an intra-neck curved stem. There were 11 males and 6 females, the age ranged from 10 to 76 years, with an average of 30.1 years. There were 9 cases of osteosarcoma, 4 cases of Ewing sarcoma, 2 cases of chondrosarcoma, 1 case of liposarcoma, and 1 case of myofibroblastoma. The disease duration was 5-14 months, with an average of 9.5 months. Enneking staging included 16 cases of stage ⅡB and 1 case of stage ⅢB. The distances from the center of the femoral head to the body midline and the acetabular apex were measured preoperatively on X-ray images. Additionally, the distances from the tip of the intra-neck curved stem to the body midline and the acetabular apex were measured at immediate postoperatively and last follow-up. The neck-shaft angle was also measured preoperatively, at immediate postoperatively, and at last follow-up. The status of osseointegration at the bone-prosthesis interface and bone growth into the prosthesis surface were assessed by X-ray films, CT, and Tomosynthesis-Shimadzu metal artefact reduction technology (T-SMART). The survival status of the patients, presence of local recurrence or distant metastasis, and occurrence of postoperative complications were assessed. The recovery of lower limb function was evaluated pre- and post-operatively using the Musculoskeletal Tumor Society (MSTS) scoring system, and pain relief was evaluated using the visual analogue scale (VAS) scores.The patient's femoral resection length was (163.1±57.5) mm, the remaining proximal femoral length was (69.6±9.3) mm, and the percentage of femoral resection length/total femoral length was 38.7%±14.6%. All 17 patients were followed up 25-86 months with an average of 58.1 months. During the follow-up, 1 patient died of lung metastasis at 46 months postoperatively, and the remaining 16 patients survived tumor-free. There was no complication such as periprosthetic infection, delayed incision healing, aseptic loosening, prosthesis fracture, or periprosthetic fracture. No evidence of micromotion or wear around the implanted stem of the prosthesis was detected in X-ray and T-SMART evaluations. There was no significant radiolucent lines, and radiographic evidence of bone ingrowth into the bone-prosthesis interface was observed in all stems. There was no significant difference in the distance from the tip of the curved stem to the body midline and the apex of the acetabulum at immediate postoperatively and last follow-up compared with the distance from the center of the femoral head to the body midline and the apex of the acetabulum before operation, respectively (P>0.05), and there was no significant difference in the above indexes between immediate postoperatively and last follow-up (P>0.05). The differences in the neck-shaft angle at various time points before and after operation were also not significant (P>0.05). At last follow-up, the MSTS score was 26.1±1.2 and the VAS score was 0.1±0.5, which were significantly improved when compared with those before operation [19.4±2.1 and 5.7±1.0, respectively] (t=14.735, P<0.001; t=21.301, P<0.001). At last follow-up, none of the patients walked with the aid of crutches or other walkers.The 3D printed customized cementless intercalary endoprosthesis with an intra-neck curved stem is an effective method for reconstructing ultrashort bone segments in the proximal femur following malignant tumor resection. The operation is reliable, the postoperative lower limb function is satisfactory, and the incidence of complications is low.