Cha and Yoo BMC Musculoskeletal Disorders (2021) 22:461 https://doi.org/10.1186/s12891-021-04363-w RESEARCH Open Access Comparison of hip structure analysis and grip strength between femoral neck and basicervical fractures Yong-Han Cha1 and Jun-Il Yoo2* Abstract Background: The purpose of this study was to analyze differences in geometrical properties of the proximal femur and predict the occurrence of basicervical fractures through a comparative study of femoral neck and basicervical fractures in patients undergoing hip structural analysis (HSA). Methods: All patients with hip fractures who were at least 65 years old and admitted to our hospital between March 2017 and December 2019 were eligible for this study. During the study period, 149 femur neck fractures (FNF) and basicervical fractures (intertrochanteric fractures of A31.2) were included in this study. Fifty-nine patients were included in the final analysis. Factors considered to be important confounders affecting the occurrence of basicervical hip fractures were chosen for propensity-score analysis. A logistic model with basicervical hip fracture as the outcome and age, sex, weight, spinal T-score, hip T-score, and vitamin D levels as confounders was used to estimate the propensity score. Results: The cross-sectional moment of inertia (CSMI) of the intertrochanter was significantly lower in patients with basicervical hip fracture (HF) than in patients with FNF (p = 0.045). However, there was no significant differences in any other HSA variable between the two groups. Receiver operating characteristic (ROC) analysis showed that cutoff point for HSA was 100 for hip axis length (HAL) (AUC = 0.659, p < 0.001) and 5.712 for CSMI of the intertrochanter (AUC = 0.676, p < 0.001). ROC analysis showed that cutoff points of HAL, CSMI of intertrochanter, and handgrip strength were 104.8, 8.75, and 16.9, respectively (AUC = 0.726, p < 0.001). Conclusions: Proximal femoral geometric analysis using HSA is a useful method for predicting the type of hip fracture. Additionally, a lower CSMI, a shorter HAL, and a lower grip strength are major predictors of basicervical fractures. Keywords: Basicervical fracture, Hip fracture, Grip strength, Hip-structure analysis Introduction fractures are classified anatomically as intracapsular frac- Hip fractures occur in more than 250,000 people in the tures and extracapsular fractures, with femoral neck United States each year. They are estimated to double in fractures and intertrochanteric fractures in each category 2050 [1, 2]. In particular, osteoporotic hip fractures are [5]. Several factors such as demographic factors, the co- causing a socioeconomic problem worldwide [3, 4]. Hip morbidity of the patient, and fracture location are con- sidered when determining the treatment method [6]. Basicervical fractures are defined as proximal femoral * Correspondence: [email protected] 2Department of Orthopaedic Surgery, Gyeongsang national university fractures located at the base of the femoral neck at its hospital, Jinju, Gyeongnamdo, South Korea junction with the intertrochanteric region [7]. For this Full list of author information is available at the end of the article © The Author(s). 2021 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Cha and Yoo BMC Musculoskeletal Disorders (2021) 22:461 Page 2 of 9 reason, they are classified as femoral neck fractures. for several days after surgery could affect the skeletal However, from a therapeutic point of view, they are mass index, there was concern about changes in body similar to intertrochanteric fractures because they are composition. Our hospital operates under a protocol close to the intertrochanteric line [8]. Several studies in which hip fracture patients undergo DXA as soon have reported that failure rates of surgical treatment by as possible if there is no surgical delay. In this study, internal fixation are high [7, 9]. Causes of such high 16 (10.7%) patients who did not undergo DXA during failure rates have been explained by the anatomical loca- their hospital stay were excluded. We were concerned tion of the fracture, implant problems, and lack of rota- about a decrease in skeletal mass index due to bed tional stability [10, 11]. However, previous studies lacked rest for several days after surgery. Thus, only patients bone quality and geometrical analyses. who underwent DXA before surgery after admission Understanding changes in bony structure and strength were included in this study. Thus, 59 (39.6%) patients due to osteoporosis with an increasing age can be who underwent DXA after surgery were excluded. All accomplished by analysis of geometric properties of operations were performed within 2 days after injury. bony tissues [12]. Understanding the pathogenesis of Fifteen (10.1%) patients with mental health issues osteoporosis and hip fracture provides important infor- such as dementia, delirium, depression, and mental mation for the establishment of fracture treatment strat- retardation were also excluded. Finally, 59 patients egies. Bone mineral density measurements using dual- were included in this study for analysis. energy x-ray absorptiometry (DXA) can assess bone quantities. Geometrical properties can be evaluated Biochemical analyses using hip structural analysis (HSA), an output function Serum 25-hydroxyvitamin D (25[OH] vitamin D) levels of the DXA machine. Geometric parameters such as were measured using a 1470 Wizard gamma counter bucking ratio and intertrochanteric outer diameter can (Perkin Elmer, Finland), an Automatic Analyzer 7600 be used to predict incident hip fractures. Changes in (Hitachi, Japan), and LIAISON (DiaSorin, U.S.A.) for mechanical structure of the femoral neck area have been radioimmunoassay (25-hydroxyvitamin D 125 I RIA Kit; reported to be associated with the risk of subsequent DiaSorin). fractures of the contralateral hip [13, 14]. Previous stud- ies have also reported that evaluating geometrical prop- Measurements of appendicular skeletal muscle mass, erties of femurs in hip fractures can help predict the risk BMD, and handgrip strength of hip fractures [15, 16]. However, these studies only an- Body composition and bone mineral density (BMD) in alyzed geometries of the proximal femur and the risk of both groups (HF and non-HF) were calculated based on fractures without analyzing characteristics according to DXA using a QDR 4500A apparatus (Hologic, U.S.A.). the type of hip fractures. Bone mineral content, fat mass, and lean soft tissue mass Therefore, the purpose of this study was to analyze dif- were evaluated separately for each portion of the body, ferences in geometrical properties of the proximal femur including arms and legs. The lean soft tissue mass of and predict the occurrence of basicervical fractures by arms and legs was about equal to skeletal muscle mass. comparing patients with femoral neck fractures and Since the absolute muscle mass corresponds to the those with basicervical fractures undergoing HSA. height, SMI was determined as lean mass [kg]/height [m]2. Arm SMI was defined as arm lean mass [kg]/height Ethics statement [m]2. Leg SMI was defined as leg lean mass [kg]/height The design and protocol of this retrospective study were [m]2. Appendicular SMI was defined as the sum of arm approved by the Institutional Review Board of our hos- and leg SMIs. Each participant held a digital hand dyna- pital (GNUH-2019-05-018-007). The requirement to ob- mometer (Digital Grip Strength Dynamometer, T.K.K tain informed consent was waived by the board. 5401, Takei Scientific Instruments Co., Ltd., Tokyo, Japan) in a sitting position. The maximum grip strength Participants was measured with the elbow flexed at 90 degrees and All patients with a hip fracture who were at least 65 the shoulder connected to the chest with the wrist at a years old and admitted to our hospital between neutral position (0 degrees) [17]. In this study, hand grip March 2017 and December 2019 were eligible for this strength was used as a surrogate parameter to evaluate study. During the study period, 149 femur neck and the function and predict the prognosis after hip fracture basicervical fractures (intertrochanteric fractures of based on research results of Di Monaco et al. [18]. A31.2) were included in this study. Basicervical frac- tures were defined as proximal femoral fractures lo- Definition of osteoporosis cated at the base of the femoral neck at its junction Osteoporosis was defined as a BMD 2.5 standard devia- with the intertrochanteric region [7]. Because bed rest tions (SDs) below the peak bone mass of a young, healthy, Cha and Yoo BMC Musculoskeletal Disorders (2021) 22:461 Page 3 of 9 gender- and race-matched reference population according Results to the World Health Organization (WHO) diagnostic clas- Demographic characteristics of patients with basicervical sification. BMD (T-score) was used to classify osteoporotic hip fractures (T-score ≤−2.5), osteopenic (− 2.5 < T-score < − 1.0), and Forty patients with femur neck fractures (FNF) and 19 normal patients (T-score ≥−1).