Ankle fractures have features of an osteoporotic fracture

Kyoung Min Lee MD

Department of Orthopaedic SurgerySeoul National University Bundang Hospital

Disclosures

The authors have no disclosures.

Introduction

Osteoporosis is a serious disease with high morbidity and mortality caused by fragility fractures, especially hip and spine fractures

Osteoporotic fracture is a special treatment problem that needs special care and instruments in operative treatment - poor fixation stability, more comminution?

Introduction

What is osteoporotic fracture? - fracture on osteoporotic bone

Osteoporosis - loss of bone mineral density - age, gender dependent (hormone)

Introduction

Is ankle fracture an osteoporotic fracture? - increasing incidence after menopause - and ??

Thur et al. 2012

Purpose

Investigate osteoporotic features of ankle fractures in terms of

(1) bone attenuation on CT (BMD)

(2) degree of trauma between the ages over 50 years and less than 50 years in patients with ankle fractures.

Materials and Methods

Retrospectively reviewed 194 consecutive patients with ankle fractures

CT examination

Exclusion : 30 patients - previous Op - congenital malformation - neuromuscular diseases - tumors or infections - interval of more than one week between the injury and CT examination

Demographic data - age, genderMechanism of injury - high/low energy traumaFracture type - medial malleolar, lateral malleolar, bimalleolar, trimalleolarBone attenuation on CT - ROI tool - talus, DT, LM, MM

Materials and Methods

Bone attenuation (housefield unit, ROI)

Bone attenuation (housefield unit, ROI)

Bone attenuation (housefield unit, ROI)

Data analysis

Reliability of CT measurement - ICC

Comparison between younger (<50 yrs) and older (>50 yrs) - t-test - chi-square test

Multiple regression analysis - effect of age and gender on bone attenuation

Results

Table 1. Data summary

Number of patients 194

Mean age (years) 51.0 (SD 15.8)

Male : Female, n (%) 98 (50.5) : 96 (49.5)

Right : Left, n (%) 109 (56.2) : 85 (43.8)

Low energy trauma : high energy trauma, n (%) 167 (86.1) : 27 (13.9)

Fracture type (medial malleolar/lateral malleolar/bimalleolar/trimalleolar)

23/76/58/37

Average bone attenuation on CT  

talus (HU) 350.7 (SD 97.3)

medial malleolus (HU) 293.1 (SD 101.0)

lateral malleolus (HU) 234.5 (SD 93.5)

distal central tibia (HU) 184.5 (SD 77.6)SD, standard deviation; HU, housefield units.

Table 2. ICC values of inter- and intraobserver reliabilities of bone attenuation measurements

  Talus Medial malleolus Lateral malleolus Distal central tibia

Interobserver

0.988 (0.970 to 0.995)

0.888 (0.739 to 0.954)

0.895 (0.756 to 0.957)

0.875 (0.712 to 0.949)

Intraobserver

0.983 (0.958 to 0.993)

0.981 (0.953 to 0.992)

0.986 (0.964 to 0.994)

0.943 (0.846 to 0.978)

Data are presented as ICC (95% confidence interval)

Table 3. Comparison between the younger and older age groups in male patients

  Younger age group Older age group p-value

Number of patients 53 45 -

Mean age (years) 35.8 (SD 8.9) 64.3 (9.3) <0.001

Low energy trauma : high energy trauma, n (%)40 (75.5) : 13 (24.5)

40 (88.9) : 5 (11.1)

0.087

Fracture type (medial malleolar/lateral malleolar/bimalleolar/trimalleolar)

7/27/14/5 8/12/10/15 0.012

Average bone attenuation on CT      

talus (HU) 392.7 (SD 85.1) 346.2 (SD 82.5) 0.008

medial malleolus (HU) 338.1 (SD 104.6) 296.4 (SD 86.1) 0.036

lateral malleolus (HU) 297.5 (SD 89.4) 233.7 (SD 69.1) <0.001

distal central tibia (HU) 225.5 (SD 85.9) 175.3 (SD 62.7) 0.002

SD, standard deviation; HU, housefield units.

Table 4. Comparison between the younger and older age groups in female patients

 Younger age group

Older age group p-value

Number of patients 35 61 -

Mean age (years) 36.9 (SD 8.1) 62.4 (SD7.1) <0.001

Low energy trauma : high energy trauma, n (%) 28 (80) : 7 (20)59 (96.7) : 2 (3.3)

0.011*

Fracture type (medial malleolar/lateral malleolar/bimalleolar/trimalleolar)

7/14/8/6 1/23/26/11 0.009

Average bone attenuation on CT      

talus (HU) 395.8 (SD 98.5) 291.7 (SD 85.9) <0.001

medial malleolus (HU) 321.2 (SD 86.0) 235.4 (SD 89.8) <0.001

lateral malleolus (HU) 245.6 (SD 86.8) 174.1 (SD78.6) <0.001

distal central tibia (HU) 216.0 (SD 55.3) 137.7 (SD 63.4) <0.001

SD, standard deviation; HU, housefield units; *, Fisher exact test.

Table 5. Effects of age and gender on bone attenuation in multiple regression analysisDependent variable (bone attenuation)

Independent variable Beta 95% CI p-value

Talus

Age -2.4 -3.2 to -1.6 <0.001

Gender -31.3 -56.3 to -6.3 0.014

Constant 52.1.7 469.1 to 574.4 <0.001

Medial malleolus

Age -2.5 -3.3 to -1.7 <0.001

Gender -41.8 -67.4 to -16.1 0.002

Constant 482.5 428.4 to 536.6 <0.001

Lateral malleolus

Age -2.6 -3.3 to -1.9 <0.001

Gender -57.0 -79.2 to -34.9 <0.001

Constant 451.6 405.0 to 498.3 <0.001

Dista central tibia

Age -2.3 -2.9 to -1.7 <0.001

Gender -26.4 -45.3 to -7.4 0.007

Constant 342.5 302.5 to 382.4 <0.001CI, confidence interval. In multiple regression analysis, dependent variable is bone attenuation (a surrogate marker of bone mineral density) of each bony structure, and independent variables are age and gender.Age and female gender show negative effect on bone attenuation.

Conclusions

- Ankle fracture had features of osteoporotic fracture that is characterized by age and gender dependent low bone attenuation. Ankle fracture should not be excluded from the clinical and research interest as well as from the benefit of osteoporosis management.

This study has been accepted in Osteoporos Int (IF=4.8)

Thank you!