Background: 

Fractures often occur in patients with normal dual x-ray absorptiometry (DXA)-measured bone mineral density (BMD). DXA does not consider clinical fracture risk factors or bone quality. We hypothesized that patients with normal BMD who sustain a fracture have other characteristics suggesting abnormal bone and an elevated fracture risk requiring additional bone health evaluation and potential anti-osteoporotic treatment.

Methods: 

A total of 7,219 patients who were ≥50 years of age, had sustained a fracture from July 2016 to July 2021, and had DXA data in the American Orthopaedic Association’s Own the Bone (AOA OTB) registry were included in this study. The index and prior fracture site data were obtained. BMD status was classified by the World Health Organization T-score criteria. The Fracture Risk Assessment Tool (FRAX) scores with and without BMD were calculated in patients with normal BMD. An elevated risk was defined as a major osteoporotic fracture risk of ≥20% or a hip fracture risk of ≥3%.

Results: 

The mean patient age (and standard deviation) was 70.8 ± 9.71 years, 84% of patients were female, and 92% of patients were Caucasian. Normal BMD was present in 8.6% of patients. The index fracture was a major osteoporotic fracture in 68.6% of patients with normal BMD and 75.6% of patients with osteoporosis. The most common site for index and prior fractures other than major osteoporotic fractures was the foot and ankle; of patients with normal BMD, 13.9% had this as the most common index site and 17.4% had this as the most common prior site. The FRAX risk calculated without BMD was elevated in 72.9% of patients with normal BMD, and the FRAX risk calculated with BMD was elevated in 12.0% of patients.

Conclusions: 

Most patients with a fracture and normal BMD met indications, including a prior fracture or elevated FRAX risk, for anti-osteoporotic therapies. Most patients were Caucasian and therefore potentially had a higher baseline fracture risk. The FRAX risk calculated without BMD was elevated more often than the FRAX risk with BMD, implying that clinical risk factors, which highlight multiple opportunities for non-pharmacologic secondary fracture prevention, should be considered along with DXA. Fractures other than major osteoporotic fractures were more common in patients with normal BMD, suggesting that minor fractures in adults who are ≥50 years of age should be considered sentinel events warranting further evaluation. Surgeons must recognize that other important risk factors apart from BMD may help to guide further bone health evaluation.

Level of Evidence: 

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

中文翻译：

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骨矿物质密度正常的患者骨折：美国骨科协会自己的骨登记处的评估

背景： 

骨折通常发生在双 X 射线吸收测定法 (DXA) 测量的骨矿物质密度 (BMD) 正常的患者中。DXA 不考虑临床骨折风险因素或骨骼质量。我们假设骨密度正常但发生骨折的患者具有其他特征，表明骨异常和骨折风险升高，需要额外的骨骼健康评估和潜在的抗骨质疏松治疗。

方法： 

共有 7,219 名年龄≥50 岁、在 2016 年 7 月至 2021 年 7 月期间发生过骨折且在美国骨科协会的 Own the Bone (AOA OTB) 登记处有 DXA 数据的患者被纳入本研究。获得了指数和之前的骨折部位数据。BMD 状态按世界卫生组织 T 评分标准分类。在 BMD 正常的患者中计算有和没有 BMD 的骨折风险评估工具 (FRAX) 评分。风险升高定义为主要骨质疏松性骨折风险≥20% 或髋部骨折风险≥3%。

结果： 

平均患者年龄（和标准差）为 70.8 ± 9.71 岁，84% 的患者为女性，92% 的患者为高加索人。8.6% 的患者 BMD 正常。68.6% 的正常 BMD 患者和 75.6% 的骨质疏松症患者的指数骨折是严重的骨质疏松性骨折。除主要骨质疏松性骨折外，最常见的指数骨折和既往骨折部位是足部和踝部；在 BMD 正常的患者中，13.9% 将此作为最常见的指示部位，17.4% 将此作为最常见的先前部位。在 BMD 正常的患者中，72.9% 的不考虑 BMD 计算的 FRAX 风险升高，而在 12.0% 的患者中，使用 BMD 计算的 FRAX 风险升高。

结论： 

大多数骨折且 BMD 正常的患者符合抗骨质疏松治疗的适应症，包括既往骨折或 FRAX 风险升高。大多数患者是高加索人，因此基线骨折风险可能更高。在没有 BMD 的情况下计算的 FRAX 风险比有 BMD 的 FRAX 风险更高，这意味着临床风险因素，强调非药物二级骨折预防的多种机会，应该与 DXA 一起考虑。骨质疏松性骨折以外的其他骨折在 BMD 正常的患者中更常见，这表明 ≥ 50 岁的成年人的轻微骨折应被视为需要进一步评估的哨兵事件。外科医生必须认识到，除 BMD 之外的其他重要风险因素可能有助于指导进一步的骨骼健康评估。

证据等级： 

预后三级。有关证据等级的完整描述，请参阅作者须知。