An Unusual Case of Non-Traumatic, Non-Pathologic Acetabular Stress Fracture with Subsequent Fracture in a Healthy Active Man

• Stress fractures are an overuse injury of bone due to repetitive microtrauma.

• Fatigue fracture: abnormal stress on normal bone.

• Insufficiency fracture: normal stress on abnormal bone.

• The first stress fracture was described by Briefhaupt in 1855.4

• Acetabular stress fractures are exceedingly rare.

• Although the exact incidence is unknown, pelvic stress fractures account for 1-2% of all stress fractures.2

• Acetabular fracture from any cause (usually high velocity trauma) is also rare, incidence of 0.5-7.5%.3

• Stress Fractures in any location are twice as common in women than men.4

• Extrinsic risk factors for stress fractures: –Overuse–lack of conditioning –poor technique–inappropriate footwear–nonabsorbent training surface

• Intrinsic risk factors for stress fractures: –muscle imbalance–Malalignment–gait abnormality– low bone mineral density–bone disease–nutritional deficits

• 63 YO male with left hip pain x 2 months

• Sudden increase in pain with severe night pain, awakening him from sleep

• Injury 2 months ago involved hanging leg raise with 5# weight, audible “pop”, & sudden onset of anterior hip pain

• X-rays negative.

• Patient continued to exercise daily: walking 6 miles daily or elliptical x 1.5 hrs, in addition to 30 min. pilates daily

• Walking was on cement with dress shoes.

• 2 days prior to presentation: sudden intolerable pain

• Physical Exam: no limp, tenderness over Left ASIS, mild tenderness over left trochanteric bursa,

• Ober test + (IT band tightness)

• Thomas test + (hip flexor tightness)

• Pain with internal and external rotation of hip

• Neurological exam normal

(note increased signal at L acetabular roof and fracture line anterior collumn)

• MRI: extensive marrow edema anterior column and roof with fracture line, increased signal at rectus femoris origin

• DEXA: normal bone mineral density

• Bone Scan: abnormal uptake at L hip only

• Pt treated conservatively with 12 weeks partial non-weightbearing and PT

• Healing was confirmed by repeat MRI

• Exact cause unclear in this case, likely prior injury altered gait mechanics which over time caused repetitive microtrauma leading to stress fracture and eventual fracture

• X-Rays are frequently negative in early stages of stress fracture, whereas MRI or triple phase bone scan is more sensitive

• Non-operative treatment is effective if fx is stable.10

• Similar cases in literature: military recruits9, track and field6, ballet dancer7and squash player8

• many of these cases are insufficiency, not fatigue fractures

(note near complete resolution of L acetabular bone marrow edema and fracture line)

• Although rare, physicians should be aware of possibility of acetabular stress fracture or fracture in patient with persistent hip pain, especially night pain

• MRI or bone scan is test of choice if clinical suspicion is high

• MRI can also evaluate for soft tissue pathology

1. Dugan, S. and Weber, K. “Stress Fractures and Rehabilitation” Phys Med Rehabil Clin N Am 18 (2007) 401-416

2. Eren, O. and Holtby, R. “Straddle Pelvic Stress Fracture in a Female Marathon Runner: A Case Report” American Journal of Sports Medicine, vol. 26; 6 (1998) 850-853.

3. Thacker, M., Tejwani, N., Thakkar, C. “Acetabulum Fractures” e-medicine Orthopedic Surgery. http://emedicine.medscape.com/article/1246057

4. Reeser, Jonathan C. “Stress Fracture” e-medicine Physical Medicine and Rehabilitation. http://emedicine.medscape.com/article/309106

5. Hodnett, P.A, Shelly, M.J., Kavanagh, E.C., Eustace, S.J., “MR Imaging of Overuse Injuries of the Hip” Magn Reson Imaging Clin N Am 17 (2009) 667-679

6. Touhy, J. Nattiv, A. “Iliac Stress Fracture in a Male Collegiate Track Athlete” American College of Sports Medicine Volume 7, No. 5, September/October 2008, 252-254.

7. Thienpont, E., Simon J.P. “Stress Fracture of the Acetabulum in a ballet dancer. A case report” Acta Orthopaedica Belgica, Vol. 71, No. 6, (2005) 740-742.

8. Patel, N.D., Trehan, R.K. “Acute isolated acetabular fracture following a game of squash: a case report” Journal of Medical Case Reports 2007, 1: 156

9. Williams, T.R. et al “Acetabular stress fractures in military endurance athletes and recruits: incidence and MRI and scintigraphic findings” Skeletal Radiol (2002) 31: 277-281.

10. Tornetta, P. “Non-operative management of acetabular fractures” J Bone Joint Surg (BR) 1999; 81-B: 67-70

SUMMARY

DISCUSSION

CASE SUMMARY

INTRODUCTION

REFERENCES

Doré E. DeBartolo, D.O., Rujuta Gandhi, M.D., Kathleen M. Weber, M.D.*

Department of Family Medicine, Advocate Christ Medical Center, Oak Lawn, IL*Midwest Orthopedics at Rush, Rush University Medical Center, Chicago, IL