Radiologic and Serologic Factors Associated with Bone Union at Femoral Atypical Fracture

Article information

J Musculoskelet Trauma. 2019;32(1):27-34

Publication date (electronic) : 2019 January 10

doi : https://doi.org/10.12671/jkfs.2019.32.1.27

Suc Hyun Kweon, M.D., Ph.D., Byung Min Yoo, M.D.

Department of Orthopedic Surgery, Wonkwang University Hospital, Iksan, Korea

Correspondence to: Suc Hyun Kweon, M.D., Ph.D. Department of Orthopedic Surgery, Wonkwang University Hospital, 895 Muwang-ro, Iksan 54538, Korea Tel: +82-63-859-1360 Fax: +82-63-852-9329 E-mail: osksh@wonkwang.ac.kr

Received 2018 August 09; Revised 2018 November 05; Accepted 2018 December 28.

Abstract

Purpose

The purpose of this study was to investigate the radiologic and serologic factors related to postoperative union using intramedullary (IM) internal fixation in atypical femoral fractures (AFF), which are closely related to bisphosphonates (BPs) for osteoporosis.

Materials and Methods

From February 2008 to December 2016, 65 patients (71 cases) who had undergone IM nail fixation after diagnosis of AFF were enrolled in this study. Patients were divided into group A, who experienced union within 6 months and group B, who did not experience union within 6 months. They were evaluated for duration of BPs use, radiologic factors and serological factors.

Results

The mean duration of BPs use was 6.17 years in group A and 8.24 years in group B (p=0.039). In the subtrochanteric area, there were 14 cases (27.5%) in group A and 14 cases (70.0%) in group B. In the femoral shaft, there were 37 cases (72.5%) in group A and 6 cases (30.0%) in group B (p=0.001). On the preoperative, the flexion in the coronal plane was 5.9^o (2.1^o-9.2^o) in group A and 8.0^o (3.1^o-12.1^o) in group B (p=0.041). On the postoperative, conversion to valgus was 15 cases (29.4%), 8 cases (40.0%); conversion to neutral was 34 cases (66.7%) and 8 cases (40.0%); conversion to varus was 2 cases (3.9%) and 4 cases (20.0%), each (p=0.037). The fracture site gap was 1.5 mm (0–2.9 mm) on the front side and 1.2 mm (0–2.2 mm) on lateral side and 2.2 mm (0.9–4.7 mm) and 1.9 mm (0.5–3.5 mm), each (p=0.042, p=0.049). Among serological factors, there was no significant difference between the two groups.

Conclusion

Factors adversely affecting the union should be recognized before surgery, such as longterm BPs use or a severe degree of bending of the femur in the coronal plane. During surgery, proper reduction and spacing of the fracture site on the coronal plane should allow adequate reduction of the anterior and posterior surfaces. Obtaining anatomic reduction would be most beneficial for union, but if that is not possible, obtaining congenital valgus rather than varus on the coronal plane may be helpful for union.

Keywords: Femoral fractures; Atypical fracture; Osteoporosis

Fig. 1.

(A) Coronal view of the angle formed by two straight lines that pass the center of the proximal and distal parts, parallel to each other (letter ‘A’). (B) Lateral view of the same two lines (letter ‘B’).

Fig. 2.

In the coronal plane, the angle that the proximal and distal fragments make on the same line as the fracture line based on the unaffected side (letter ‘C’), The angle that the distal and proximal fragments make on the basis of the fracture site of the affected side (letter ‘D’). If C-D is 0: neutral, (–): valgus, (+): varus.

Fig. 3.

(A) The angle that the proximal and distal fragments make based on the fracture site in the coronal plane (letter ‘E’). (B) The value of the unaffected site on the basis of the affected site (letter ‘F’). If E-F is 0: neutral, (+): flexion, (–): extension.

Fig. 4.

(A) Incidence of delayed union according to the correction angle in the coronal plane. (B) Incidence of delayed union according to the sum of the remaining anterior, posterior, medial and lateral gap sizes obtained from anteroposterior and lateral radiographs. Group A experienced union within 6 months of surgery. Group B did not experience union within 6 months.

Table 1.

Baseline Patients Characteristics

Table 2.

Fracture Site and Bisphosphonate Administration History

Table 3.

Radiographic Characteristics

Table 4.

Serologic Characteristics

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Fig. 4.

Table 1.

Baseline Patients Characteristics

Characteristic	Group A (n=51)	Group B (n=20)	p-value
Age (yr)	76.7±5.3	77.2±7.4	0.876
Sex (female:male)	50:1	19:1	0.487
Mean BMI (kg/m²)	19.9	20.1	0.242
Mean BMD (T-score)	−3.1	−3.4	0.725
Comorbidity
HTN	17 (33.3)	6 (30.0)	0.787
DM	15 (29.4)	4 (20.0)	0.420
RA	7 (13.7)	3 (15.0)	1.000
Cardiovascular Dz.	9 (17.6)	3 (15.0)	1.000
Cerebrovascular Dz.	3 (5.9)	2 (10.0)	0.616
Smoking	1 (2.0)	1 (5.0)	0.487
ASA grade			0.616
I or II	48 (94.1)	18 (90.0)
III or IV	3 (5.9)	2 (10.0)

Values are presented as mean±standard deviation, number only, or number (%). Group A experienced union within 6 months of surgery. Group B did not experience union within 6 months. BMI: body mass index, BMD: bone mineral density, HTN: hypertension, DM: diabetes mellitus, RA: rheumatoid arthritis, Dz.: disease, ASA: American Society of Anesthesiologists.

Table 2.

Fracture Site and Bisphosphonate Administration History

Variable	Group A (n=51)	Group B (n=20)	p-value
Fracture site			0.001
Subtrochanteric	14 (27.5)	14 (70.0)
Shaft	37 (72.5)	6 (30.0)
Bisphosphonate history	50 (98.0)	20 (100)
Administration period (yr)	6.17±2.04 (0–8.66)	8.24±1.74 (4.66–11.66)	0.039
Time to operation from onset (d)	3.8±1.0 (1–5)	3.9±1.2 (1–6)	0.814

Values are presented as number (%) or mean±standard deviation (range). Group A experienced union within 6 months of surgery. Group B did not experience union within 6 months.

Table 3.

Radiographic Characteristics

Variable	Group A (n=51)	Group B (n=20)	p-value
Preoperative
Neck-shaft angle (°)	131.2±6.1 (128–133)	131.1±4.8 (128–132)	0.578
Coronal bowing (°)	5.9±1.1 (2.1–9.2)	8.0±1.5 (3.1–12.1)	0.041
Sagittal bowing (°)	7.0±1.6 (3.0–10.1)	4.2±1.3 (2.0–8.0)	0.240
Cortical thickness (subtrochanteric, mm)
Anterior	4.2±1.5 (3.1–5.2)	4.6±1.2 (2.9–5.1)	0.660
Posterior	4.1±1.3 (3.9–4.9)	5.6±1.6 (4.0–6.1)	0.451
Medial	6.4±1.6 (4.8–7.9)	6.4±1.3 (5.1–7.9)	0.658
Lateral	6.0±1.8 (5.1–7.2)	6.8±2.0 (5.3–7.5)	0.513
Cortical thickness (isthmus, mm)
Anterior	5.7±1.1 (4.2–7.1)	5.8±1.3 (4.3–7.2)	0.451
Posterior	5.2±1.3 (3.9–6.9)	6.0±1.1 (4.0–7.9)	0.667
Medial	6.8±1.8 (5.1–7.5)	7.2±1.7 (5.5–7.9)	0.512
Lateral	7.0±1.3 (6.1–8.9)	7.2±1.5 (6.2–8.9)	0.476
Postoperative
Coronal plane			0.037
Valgus	15 (29.4)	8 (40.0)
Neutral	34 (66.7)	8 (40.0)
Varus	2 (3.9)	4 (20.0)
Sagittal plane			0.690
Flexion	3 (5.9)	2 (10.0)
Neutral	35 (68.6)	12 (60.0)
Extension	13 (25.5)	6 (30.0)
Fracture site gap (mm)
Anterior	1.5±1.6 (0–2.9)	2.2±1.2 (0.9–4.7)	0.042
Posterior	1.7±1.3 (0–2.2)	1.9±1.5 (0.5–3.5)	0.246
Medial	2.1±1.5 (0–2.9)	2.2±1.6 (1.0–3.5)	0.461
Lateral	1.2 ± 0.7 (0–2.2)	1.9 ± 0.8 (0.5–3.5)	0.049

Values are presented as mean±standard deviation (range) or number (%). Group A experienced union within 6 months of surgery. Group B did not experience union within 6 months.

Table 4.

Serologic Characteristics

Serologic marker	Group A (n=51)	Group B (n=20)	p-value
IGF-1 (ng/ml)	100.89±23.7 (80.12–157.58)	113.6±35.7 (72.15–157.22)	0.551
PTH (pg/ml)	45.13±15.7 (21.78–69.25)	58.34±23.6 (19.75–81.35)	0.241
Ca (mg/dl)	8.76±3.65 (5.72–15.87)	9.1±7.62 (2.59–31.22)	0.495
Ca²⁺ (mg/dl)	4.58±2.64 (2.23–11.67)	4.72±3.12 (1.99–15.28)	0.471
25(OH) vitamin D (ng/ml)	24.34±11.62 (11.71–39.22)	20.78±12.01 (10.85–35.54)	0.158
Uric acid (mg/dl)	3.17±1.28 (1.22–10.25)	4.73±1.64 (1.19–8.25)	0.224
Bone ALP (IU/L)	8.21±2.65 (2.45–22.71)	6.72 ± 2.52 (3.12–17.74)	0.246

Values are presented as mean±standard deviation (range). Group A experienced union within 6 months of surgery. Group B did not experience union within 6 months. IGF-1: insulin-like growth factor, PTH: parathyroid hormone, ALP: alkaline phosphatase.