保留骨骺铰链型膝关节假体治疗儿童股骨远端骨肉瘤的疗效

Physeal-sparing distal femur megaprothesis for skeletally immature patients with osteosarcoma

目的探讨保留骨骺铰链型膝关节假体治疗儿童股骨远端骨肉瘤的临床疗效、胫骨近端生长潜能的保留效果以及术后并发症。方法回顾性收集2015年8月至2019年1月于北京大学人民医院骨与软组织肿瘤治疗中心诊治的37例儿童股骨远端骨肉瘤患儿资料,男21例、女16例,年龄(9.1±2.1)岁(范围5~12岁);身高为(140±10)cm(范围115~160 cm)。所有患儿均接受股骨远端瘤段截除,重建方式采用保留患侧胫骨近端骨骺的特制单纯铰链型膝关节假体。术前及术后每3个月复查双下肢全长X线片,测量双侧下肢全长、胫骨长度,与术前下肢全长、胫骨长度进行比较,计算患侧胫骨的生长潜能。术后功能采用骨与软组织肿瘤协会(Musculoskeletal Tumor Society,MSTS)评分系统评估,并记录患者的术后并发症。结果37例患儿均顺利完成手术,手术时间为(143±41)min(范围90~250 min),术中失血量(314±397)ml(范围30~2200 ml)。随访时间为(42.3±12.1)个月(范围24~64个月)。患儿术后膝关节活动度为屈伸115.6°±7.2°(范围100°~130°)。术后MSTS评分为(26.7±1.6)分(范围23~30分),末次随访时双下肢不等长为(4.0±2.1)cm(范围1.3~10 cm),患侧胫骨长度较健侧短缩(1.3±1.0)cm(范围0~3.8 cm)。患侧胫骨近端骨骺生长百分比为70%±17%(范围30%~100%)。13例发生并发症,发生率为35%(13/37),其中假体相关并发症发生率为16%(6/37)。3例手术切口愈合不良,经清创联合抗生素治疗后愈合;1例术后3年外伤后出现股骨柄松动,更换为成人型肿瘤关节;2例分别在术后30、33个月外伤后发生股骨柄断裂,接受股骨侧假体翻修手术;1例患儿术后10个月出现非外伤性股骨柄断裂,行翻修手术治疗后好转;6例术后出现肿瘤复发,其中4例软组织肿瘤复发者行局部切除、2例股骨近端复发者行截肢或翻修手术治疗。结论单纯铰链膝关节假体能保留胫骨近端骺板的生长潜能,术后早中期功能满意,假体相关并发症发生率低。

Objective To evaluate the clinical outcome of a special physeal sparing knee prosthesis for pediatric distal femoral osteosarcoma regarding the functional outcome,retention of the growth potential of the proximal tibia,and postoperative complications.Methods A retrospective study was conducted to review 37 pediatric patients with osteosarcoma of distal femur who were treated in a single musculuskeletal tumor center between August 2015 and January 2019.Among them,21 were boys and 16 were girls,aged from 5 to 12 years at the time of operation,with an average age of 9.1±2.1 years and the height of 115 to 160 cm,with an average of 140±10 cm.Tumor resection of distal femur was performed and the bone defect was reconstructed by a special hinged knee prosthesis which can preserve the proximal tibial epiphyseal plate.Demographic data was recorded.Overall leg length and tibial length was assessed by full-length standing anteroposterior radiographs of bilateral lower extremity with the patella pointing anteriorly preoperativelly and postoperativelly at each follow up.And the growth potential of the affected proximal tibia was calculated by comparing with the preoperative length of tibia.Meanwhile,the functional outcome was assessed by using the Musculoskeletal Tumor Society(MSTS)system,and the postoperative complications were analysed.Results All patients underwent the tumor resection and reconstruction operation successfully.The average operation duration was 143±41 minutes,ranging 90 to 250 minutes.The average intraoperative blood loss was 314±397 ml,ranging 30 to 2200 ml.The patients were followed up for 24 to 64 months,averaging 42.3±12.1 months.The postoperative knee range of motion was 100-130 degrees,with an average of 115.6±7.2 degrees.The postoperative MSTS score was 23-30,with an average of 26.7±1.6.To the last follow-up,the limb length discrepancy of the lower limb was 1.3 to 10 cm,and the length of the tibia was shortened from 0 to 3.8 cm compared with the opposite side,with an average of 1.3±1.0 cm.The growth percentage of the proximal tibial epiphysis on the affected side was 30%to 100%,with an average of 70%±17%.Totally,13 patients suffered postoperative complication,the overall incidence of complications was 35%(13/37),and prosthesis-related complications were 16%(6/37).Three patients with wound dehiscence were managed by debridement and antibiotics.Radiographs revealed femoral stem loosening in a single patient 3 years after the initial operation and then the prosthesis was converted to an adult tumor knee endoprosthesis.Two cases experienced breakage of the femoral stem at 30 and 33 months,respectively,due to an accidental injury.They received revision surgery,and a new femoral prosthesis component was replaced.One patient developed femoral stem breakage at 10 months after surgery due to fatigue fracture,which treated with revision surgery.Tumor recurrence occurred in 6 patients.Among them,tumor recurrence in soft tissue occurred in 4 patients,and treated with regional resection without further recurrence.The other 2 patients experienced tumor recurrence at the distal femoral site,and treated with resection and prosthetic revision.Conclusion The physeal sparing pediatric knee prosthesis can preserve the growth potential of the proximal tibial epiphyseal plate with good postoperative function and low incidence of prosthesis complications.Therefore,it can be an alternativeespecially for skeletally immature patients with distal femur osteosarcoma.