Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota, USA.
Department of Orthopedic Surgery, Emory University, Atlanta, Georgia, USA.
J Surg Oncol. 2021 Feb;123(2):505-509. doi: 10.1002/jso.26300. Epub 2020 Dec 1.
The proximal humerus is a common location for primary and non-primary tumors. Reconstruction of the proximal humerus is commonly performed with an endoprosthesis with low rates of structural failure. The incidence and risk factors for stress shielding are under reported.
Thirty-nine (19 male, 20 female) patients underwent resection of the proximal humerus and reconstruction with a cemented modular endoprosthesis between 2000 and 2018. The mean resection length was 12 ± 4 cm and was most commonly performed for metastatic disease (n = 26, 67%).
Stress shielding was observed in 9 (23%) patients at a mean of 29 (6-132) months postoperatively. Patients with stress shielding were noted to have shorter intramedullary stem length (87 vs. 107 mm, p < .001), longer extramedullary implant length (16 vs. 14 cm, p = .01) and a higher extramedullary implant to stem length ratio (2.1 vs. 1.1, p < .001). The incidence of stress shielding was higher (p = .003) in patients reconstructed with 75 mm stem (n = 6, 67%) lengths.
Stress shielding of the humerus was associated with the use of shorter stems and long extramedullary implants. The long-term ramifications of stress shielding on implant stability, complications at the time of revision surgery, and overall patient outcomes remain unknown.
肱骨近端是原发性和非原发性肿瘤的常见部位。肱骨近端的重建通常采用假体进行，假体的结构失败率较低。应力遮挡的发生率和风险因素报道较少。
2000 年至 2018 年间，39 例（19 名男性，20 名女性）患者接受了肱骨近端切除和用骨水泥固定的模块化假体重建。平均切除长度为 12 ± 4cm，最常见的是转移性疾病（n=26，67%）。
术后 29（6-132）个月，9 例（23%）患者出现应力遮挡。发生应力遮挡的患者髓内干长度较短（87 比 107mm，p<.001），髓外植入物长度较长（16 比 14cm，p=.01），髓外植入物与干长度比更高（2.1 比 1.1，p<.001）。75mm 干（n=6，67%）长度重建的患者发生应力遮挡的几率更高（p=.003）。
肱骨的应力遮挡与使用较短的干和长的髓外植入物有关。应力遮挡对植入物稳定性、翻修手术时并发症以及患者整体预后的长期影响尚不清楚。
