Spross Christian, Kaestle Nicola, Benninger Emanuel, Fornaro Jürgen, Erhardt Johannes, Zdravkovic Vilijam, Jost Bernhard
Department of Orthopaedics and Traumatology, Kantonsspital St. Gallen, Rorschacherstrasse 95, 9007, St. Gallen, Switzerland,
Clin Orthop Relat Res. 2015 Sep;473(9):3038-45. doi: 10.1007/s11999-015-4322-x. Epub 2015 Apr 25.
Osteoporosis may complicate surgical fixation and healing of proximal humerus fractures and should be assessed preoperatively. Peripheral quantitative CT (pQCT) and the Tingart measurement are helpful methods, but both have limitations in clinical use because of limited availability (pQCT) or fracture lines crossing the area of interest (Tingart measurement). The aim of our study was to introduce and validate a simple cortical index to assess the quality of bone in proximal humerus fractures using AP radiographs.
QUESTIONS/PURPOSES: We asked: (1) How do the deltoid tuberosity index and Tingart measurement correlate with each other, with patient age, and local bone mineral density (BMD) of the humeral head, measured by pQCT? (2) Which threshold values for the deltoid tuberosity index and Tingart measurement optimally discriminate poor local bone quality of the proximal humerus? (3) Are the deltoid tuberosity index and Tingart measurement clinically applicable and reproducible in patients with proximal humerus fractures?
The deltoid tuberosity index was measured immediately above the upper end of the deltoid tuberosity. At this position, where the outer cortical borders become parallel, the deltoid tuberosity index equals the ratio between the outer cortical and inner endosteal diameter. In the first part of our study, we retrospectively measured the deltoid tuberosity index on 31 patients (16 women, 15 men; mean age, 65 years; range, 22-83 years) who were scheduled for elective surgery other than fracture repair. Inclusion criteria were available native pQCT scans, AP shoulder radiographs taken in internal rotation, and no previous shoulder surgery. The deltoid tuberosity index and the Tingart measurement were measured on the preoperative internal rotation AP radiograph. The second part of our study was performed by reviewing 40 radiographs of patients with proximal humerus fractures (31 women, nine men; median age, 65 years; range, 22-88 years). Interrater (two surgeons) and intrarater (two readings) reliabilities, applicability, and diagnostic accuracy were assessed.
The correlations between radiograph measurements and local BMD (pQCT) were strong for the deltoid tuberosity index (r = 0.80; 95% CI, 0.63-0.90; p < 0.001) and moderate for the Tingart measurement (r = 0.67; 95% CI, 0.42-0.83; p < 0.001). There was moderate correlation between patient age and the deltoid tuberosity index (r = 0.65; p < 0.001), patient age and the Tingart measurement (r = 0.69; p < 0.001), and patient age and pQCT (r = 0.73; p < 0.001). The correlation between the deltoid tuberosity index and the Tingart measurement was strong (r = 0.84; p < 0.001). We determined the cutoff value for the deltoid tuberosity index to be 1.44, with the area under the curve = 0.87 (95% CI, 0.74-0.99). This provided a sensitivity of 0.88 and specificity of 0.80. For the Tingart measurement, we determined the cutoff value to be 5.3 mm, with the area under the curve = 0.83 (95% CI, 0.67-0.98), which resulted in a sensitivity of 0.81 and specificity of 0.85. The intraobserver reliability was high and not different between the Tingart measurement (intraclass correlation coefficients [ICC] = 0.75 and 0.88) and deltoid tuberosity index (ICC = 0.88 and 0.82). However, interobserver reliability was higher for the deltoid tuberosity index (ICC = 0.96; 95% CI, 0.93-0.98) than for the Tingart measurement (ICC = 0.85; 95% CI, 0.69-0.93).The clinical applicability on AP radiographs of fractures was better for the deltoid tuberosity index (p = 0.025) because it was measureable on more of the radiographs (77/80; 96%) than the Tingart measurement (69/80; 86%).
The deltoid tuberosity index correlated strongly with local BMD measured on pQCT and our study evidence shows that it is a reliable, simple, and applicable tool to assess local bone quality in the proximal humerus. We found that deltoid tuberosity index values consistently lower than 1.4 indicated low local BMD of the proximal humerus. Furthermore, the use of the deltoid tuberosity index has important advantages over the Tingart measurement regarding clinical applicability in patients with proximal humerus fractures, when fracture lines obscure the Tingart measurement landmarks. However, further studies are needed to assess the effect of the deltoid tuberosity index measurement and osteoporosis on treatment and outcome in patients with proximal humerus fractures.
Level IV, diagnostic study.
骨质疏松可能会使肱骨近端骨折的手术固定和愈合变得复杂，因此应在术前进行评估。外周定量CT（pQCT）和廷加特测量法是有用的方法，但由于可用性有限（pQCT）或骨折线穿过感兴趣区域（廷加特测量法），两者在临床应用中都存在局限性。我们研究的目的是引入并验证一种简单的皮质指数，用于通过前后位（AP）X线片评估肱骨近端骨折的骨质质量。
问题/目的：我们提出以下问题：（1）三角肌粗隆指数和廷加特测量法之间、与患者年龄以及通过pQCT测量的肱骨头局部骨密度（BMD）之间有何相关性？（2）三角肌粗隆指数和廷加特测量法的哪些阈值能最佳区分肱骨近端局部骨质质量差的情况？（3）三角肌粗隆指数和廷加特测量法在肱骨近端骨折患者中是否具有临床适用性和可重复性？
三角肌粗隆指数在三角肌粗隆上端正上方进行测量。在此位置，外侧皮质边界平行，三角肌粗隆指数等于外侧皮质与内侧骨内膜直径之比。在我们研究的第一部分，我们回顾性测量了31例计划进行非骨折修复择期手术患者（16名女性，15名男性；平均年龄65岁；范围22 - 83岁）的三角肌粗隆指数。纳入标准为有可用的原始pQCT扫描、内旋位的肩部AP X线片且既往无肩部手术史。在术前内旋位AP X线片上测量三角肌粗隆指数和廷加特测量值。我们研究的第二部分通过回顾40例肱骨近端骨折患者（31名女性，9名男性；中位年龄65岁；范围22 - 88岁）的X线片进行。评估了观察者间（两名外科医生）和观察者内（两次读数）的可靠性、适用性和诊断准确性。
X线片测量值与局部BMD（pQCT）之间的相关性，三角肌粗隆指数较强（r = 0.80；95%置信区间，0.63 - 0.90；p < 0.001），廷加特测量法中等（r = 0.67；95%置信区间，0.42 - 0.83；p < 0.001）。患者年龄与三角肌粗隆指数之间存在中等相关性（r = 0.65；p < 0.001），患者年龄与廷加特测量值之间（r = 0.69；p < 0.001），以及患者年龄与pQCT之间（r = 0.73；p < 0.001）。三角肌粗隆指数与廷加特测量值之间的相关性较强（r = 0.84；p < 0.001）。我们确定三角肌粗隆指数的截断值为1.44，曲线下面积 = 0.87（95%置信区间，0.74 - 0.99）。这提供了0.88的敏感性和0.80的特异性。对于廷加特测量法，我们确定截断值为5.3 mm，曲线下面积 = 0.83（95%置信区间，0.67 - 0.98），敏感性为0.81，特异性为0.85。观察者内可靠性较高，廷加特测量法（组内相关系数[ICC] = 0.75和0.88）与三角肌粗隆指数（ICC = 0.88和0.82）之间无差异。然而，观察者间可靠性对于三角肌粗隆指数（ICC = 0.96；95%置信区间，0.93 - 0.98）高于廷加特测量法（ICC = 0.85；95%置信区间，0.69 - 0.93）。骨折AP X线片上的临床适用性对于三角肌粗隆指数更好（p = 0.025），因为与廷加特测量法（69/80；86%）相比，它在更多的X线片上可测量（77/80；96%）。
三角肌粗隆指数与通过pQCT测量的局部BMD密切相关，我们的研究证据表明它是评估肱骨近端局部骨质质量的可靠、简单且适用的工具。我们发现三角肌粗隆指数值持续低于1.4表明肱骨近端局部BMD较低。此外，在骨折线模糊廷加特测量标志时，对于肱骨近端骨折患者，三角肌粗隆指数的应用在临床适用性方面比廷加特测量法具有重要优势。然而，需要进一步研究来评估三角肌粗隆指数测量和骨质疏松对肱骨近端骨折患者治疗及预后的影响。
IV级，诊断性研究。
