Failure of Intramedullary Nailing for Subtrochanteric Atypical Femoral Fractures Caused by Endosteal Cortical Thickening

Article information

J Musculoskelet Trauma. 2019;32(4):211-221

Publication date (electronic) : 2019 January 10

doi : https://doi.org/10.12671/jkfs.2019.32.4.211

Young Ho Roh, M.D., Kimoon Kang, M.D., Hee Joong Kim, M.D., Ph.D., Kwang Woo Nam, M.D., Ph.D.

Department of Orthopaedic Surgery, Jeju National University Hospital, Jeju, Korea

Department of Orthopaedic Surgery, Seoul National University Hospital, Seoul, Korea

Correspondence to: Kwang Woo Nam, M.D., Ph.D. Department of Orthopaedic Surgery, Jeju National University Hospital, 15 Aran 13-gil, Jeju 63241, Korea Tel: +82-64-717-1690 Fax: +82-64-717-2714 E-mail: kangu70@snu.ac.kr Financial support: This work was supported by the Academic Research Foundation of Jeju National University Institute of Medical Science in 2014. Conflict of interests: None.

Received 2019 September 25; Revised 2019 October 04; Accepted 2019 October 13.

Abstract

Purpose

Recent literature has noted incidences of subtrochanteric atypical femoral fractures (AFFs) in patients who have taken long-term bisphosphonates (BPs). Most cases of subtrochanteric AFFs have been treated with intramedullary nailing and cases of delayed union have been reported. On the other hand, there is no data available on the complications associated with endosteal thickening or cortical thickening. This study evaluated the results of surgical treatment according to the endosteal thickening of the lateral cortex in subtrochanteric AFFs.

Materials and Methods

Investigation was performed at the Department of Orthopaedic Surgery, Jeju National University Hospital. The study consisted of patients with subtrochanteric AFFs, defined by the American Society for Bone and Mineral Research (ASBMR) major criteria, who underwent intramedullary nailing from March 2012 to October 2014. The cases were categorized into two groups based on the presence of endosteal thickening. The evaluation included the demographic data, radiographic data of initial reduction state, and duration of BPs.

Results

The demographic data and duration of BPs were similar in the two groups. On the other hand, varus reduction (Group I: 12.5% vs. Group II: 78.9%; p=0.001), delayed union (Group I: 0% vs. Group II: 70.0%; p=0.003), nonunion (Group I: 0% vs. Group II: 47.4%; p=0.017), and union time (Group I: 5.5 months vs. Group II: 8.3 months; p<0.001) were significantly different in the two groups.

Conclusion

Endosteal thickening of the lateral cortex in subtrochanteric AFFs was identified as an independent factor that decides the reduction of the fracture and nonunion. The endosteal thickening should be removed to obtain anatomical alignment for successful surgical results.

Keywords: Femur; Femoral fractures; Subtrochanteric; Bone nails; Ununited; Insufficiency fracture

Fig. 1.

(A) Atypical subtrochanteric fracture in the right femur, antero-posterior (AP) view. Endosteal thickening of the lateral cortex at the fracture site is depicted by a white arrow. (B) Atypical subtrochanteric fracture in the left femur, AP view. Endosteal thickening of the lateral cortex at the fracture site is depicted by a white arrow. (C) Atypical subtrochanteric fracture in the right femur, AP view. The lateral cortex thickness at the fracture site does not differ from the distal part (white arrowhead). (D) Atypical subtrochanteric fracture in the left femur AP view. Periosteal thickening of the lateral cortex is observed, but endosteal cortical thickening is not observed (white arrowhead).

Fig. 2.

(A) Coronal plane femoral bowing was measured as the angulation between the proximal and distal quarters of the femoral diaphysis in the femur antero-posterior view. (B) Sagittal plane femoral bowing was measured as the angulation between the proximal and distal quarters of the femoral diaphysis in the femur lateral view.

Fig. 3.

(A, B) Atypical subtrochanteric fracture in the left femur, anteroposterior (AP) and lateral (LAT) views. Shortening, varus deformation, and total displacement of fracture were observed. Endosteal thickening of the lateral cortex at the fracture site is depicted by a white arrowhead. (C, D) These are left femur AP and LAT views taken nine months after surgery. The atypical subtrochanteric fracture was fixed with a long cephalo-medullary nail and cerclage cable. Callus formation was observed at four cortical regions (medial, lateral, anterior and posterior cortex) in the fracture site marked with white arrows.

Fig. 4.

(A) Atypical subtrochanteric fracture in the right femur, antero-posterior (AP) view. (B) This is right femur AP view taken immediately after surgery. The atypical subtrochanteric fracture was fixed with a long cephalo-medullary nail. Compared to the contralateral side, 13 varus reduction was observed (asterisk). (C) This is the right femur AP view taken 12 months after surgery. Breakage of the distal interlocking screw (white arrow) and nonunion of the fracture are observed. (D) This is the right femur AP view after performing re-operation using a plate.

Fig. 5.

Cox proportional hazard survival curve (solid line: Group I, dotted line: Group II).

Fig. 6.

Thickening of the lateral cortex in subtrochanteric regions is observed on both sides. On the right side, both endosteal and periosteal cortical thickening are observed (white arrows), whereas only periosteal cortical thickening is observed on the left side (white arrowhead).

Table 1.

ASBMR Task Force 2013 Case Definition of AFFs Baseline⁴

Table 2.

Baseline Characteristics Included in This Study

Table 3.

Intra- and Postoperative Variables

Table 4.

Univariate Comparison between the Union and Nonunion Groups

Table 5.

Logistic Regression Analysis of Nonunion

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Fig. 1.

Fig. 2.

Fig. 3.

Fig. 4.

Fig. 5.

Cox proportional hazard survival curve (solid line: Group I, dotted line: Group II).

Fig. 6.

Table 1.

ASBMR Task Force 2013 Case Definition of AFFs Baseline⁴

Major features
• The fracture is associated with minimal or no trauma, as in a fall from a standing height or less.
• The fracture line originates at the lateral cortex and is substantially transverse in its orientation, although it may become oblique as it progresses medially across the femur.
• Complete fractures extend through both cortices and may be associated with a medial spike; incomplete fractures involve only the lateral cortex.
• The fracture is noncomminuted or minimally.
• Localized periosteal or endosteal thickening of the lateral cortex is present at the fracture site (‘beaking’ or ‘flaring’).

^∗

F: female, M: male, Lt.: left, Rt.: right, BMD: bone mineral density, BMI: body mass index, VAS: visual analogue scale, Preop: preoperative, Postop: postoperative.

Table 2.

Baseline Characteristics Included in This Study

Variable	Group I (n=8)	Group II (n=19)	p-value
Age (yr)	68.0±9.2	65.4±5.6	0.367
Height (cm)	157.3±4.8	153.1±5.6	0.098
Weight (kg)	58.6±5.3	55.7±8.1	0.368
BMI (kg/m²)	23.9±3.2	24.6±3.4	0.621
BMD (T-score)	–2.3±0.9	–2.2±1.2	0.952
ASA classification			0.506
1	4 (50.0)	11 (57.9)
2	2 (25.0)	6 (31.6)
3	2 (25.0)	2 (10.5)
Duration of BPs (yr)	5.4±3.1	4.5±2.0	0.375
Presence of drug holiday			0.558
Yes	1 (12.5)	4 (21.1)
No	7 (87.5)	15 (78.9)
Prodromal symptoms			0.675
Yes	4 (50.0)	12 (63.2)
No	4 (50.0)	7 (36.8)
Follow-up (yr)	2.0±1.2	2.3±1.4	0.616
Side (right:left)	2:6 (25:75)	9:10 (47:53)	0.280

Values are presented as mean±standard deviation or number (%). BMI: body mass index, BMD: bone mineral density, ASA: American Society of Anesthesiologists, BPs: bisphosphonates.

Table 3.

Intra- and Postoperative Variables

Variable	Group I (n=8)	Group II (n=19)	p-value
Implant type			0.655
PFNA-II	5 (62.5)	13 (68.4)
A2FN	1 (12.5)	3 (15.8)
ITST	2 (25.0)	3 (15.8)
Implant length			0.558
Long	6 (75.0)	13 (68.4)
Short	2 (25.0)	6 (31.6)
Femur bowing (°)
Coronal plane	3.2±8.2	2.9±4.63	0.933
Sagittal plane	11.4±4.6	10.4±3.3	0.570
Varus reduction	1 (12.5)	15 (78.9)	0.001
Nonunion	0 (0)	9 (47.4)	0.017
Delayed union*	0 (0)	7/10 (70.0)	0.003
Union time (mo)	5.5±1.1	8.3±1.6	<0.001

Values are presented as mean±standard deviation or number (%). *This subject was presented as a percentage of patients who were finally bone healing. PFNA-II: Proximal Femoral Nail Antirotation II, A2FN: Expert Asian Femoral Nail, ITST: Intertrochanteric/Subtrochan-teric.

Table 4.

Univariate Comparison between the Union and Nonunion Groups

Variable	Union (n=18) N	Nonunion (n=9)	) p-value
Age (yr)	63.7±7.0	69.1±6.6	0.231
BMI (kg/m²)	22.9±3.4	25.2±3.1	0.153
BMD (T-score)	–2.0±0.8	–2.7±1.5	0.143
ASA classification			0.532
1	10 (55.6)	5 (55.6)
2	5 (27.8)	3 (33.3)
3	3 (16.7)	1 (11.1)
Duration of BPs (yr)	4.7±2.6	4.9±2.0	0.854
Presence of drug holiday			0.675
Yes	3 (16.7)	2 (22.2)
NO	3 (16.7)	2 (22.2)
Prodromal symptoms			0.551
Yes	11 (61.1)	5 (55.6)
No	7 (38.9)	4 (44.4)
Cortical thickening			0.026
Yes	10 (55.6)	9 (100)
No	8 (44.4)	0 (0)
Implant type			0.865
PFNA-II	12 (66.7)	6 (66.7)
A2FN	3 (16.7)	1 (11.1)
ITST	3 (16.7)	2 (22.2)
Implant length			0.550
Long	13 (72.2)	6 (66.7)
Sort	5 (27.8)	3 (33.3)
Femur bowing (°)
Coronal plane	3.4±6.3	2.1±4.7	0.626
Sagittal plane	10.7±4.7	10.8±2.9	0.925

Values are presented as mean±standard deviation or number (%). BMI: body mass index, BMD: bone mineral density, ASA: American Society of Anesthesiologists, BPs: bisphosphonates, PFNA-II: Proximal Femoral Nail Antirotation II, A2FN: Expert Asian Femoral Nail, ITST: Intertrochanteric/Subtrochanteric.

Table 5.

Logistic Regression Analysis of Nonunion

Variable	B value	95% CI	p-value
Age	0.956	0.885–1.033	0.257
BMI	0.789	0.611–1.018	0.068
BMD	0.813	0.753–1.125	0.192
Cortical thickening	7.198	1.718–30.154	0.007

CI: confidence interval, BMI: body mass index, BMD: bone mineral density.