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Femoral Neck Stress Fracture

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Other Names

  • Femoral neck stress fractures (FNSF)

Background

  • This page describes stress fracture of the neck of the Femur

History

  • Initially reported by the German Military as early as 1905[1]

Epidemiology

  • Account for around 3% of all stress fractures seen in the athlete[2]
    • Account for 4.1% of stress fractures in female athletes, only 1.8% in male athletes
  • Represent 50% of all femoral stress fractures[3]
  • Age range 16-56, more common in women[4]

Introduction

Illustration of compression and tension type femoral neck stress fractures[5]

General

  • Occur as a result of repetitive submaximal mechanical load across the femoral neck
  • As with all stress fractures, this occurs when the bone absorption exceeds mechanical repair during remodeling
  • Vast majority of cases occur in individuals with normal bone and excessive forces
  • Starts with a "crack" but can propagate with inadequate healing time
  • Femur can tolerate 3-5 times body weight during exercise
  • Early detection is important
    • Increased awareness has been shown to improve early detection[6]

Types

  • Compression-type
    • Occur due to compressive forces on the inferomedial neck
    • Typically remains stable until it reaches 50% of the femoral neck width[7]
    • More oblique then tension-type, considered more stable and less likely to displace
  • Tension-type
    • Occur due to tension forces on the superolateral neck
    • Normally counterbalancd by Gluteus Medius, Gluteus Minimus
    • However when these muscles become fatigued, tension forces develop on the superior neck
    • This creates a fracture line at 90° to the broken cortex
    • Results in a transverse fracture which is more unstable and likely to displace

Pathoanatomy


Risk Factors


Differential Diagnosis

Differential Diagnosis Hip Pain


Clinical Features

Clinical demonstration of the fulcrum test[11]

History

  • Gradual or insidious onset of poorly localized pain
  • Worse with weight bearing or activity, improves with rest
  • In one study, 87% of patients endorsed anterior groin pain[12]
  • Typically involves a recent increase in training intensity
  • Early in disease state, pain only arrives towards the later stages of exercise
  • Later in the disease process, the pain arrives early in exercise
  • Eventually pain can even occur at night or at rest
  • If it goes on long enough, patients may endorse popping or cracking sensation as the fracture starts to displace

Physical Exam: Physical Exam Hip

  • Examination is often non-specific
  • Painful at extreme arc of motion of hip, especially with internal rotation
  • May be tender on anterior palpation of the hip

Special Tests

  • Fulcrum Test: Arm is placed under affected femur and used as a fulcrum to recreate pain
  • Hop Test: Patient jumps up and down on affected limb to recreate pain

Evaluation

Linear sclerotic line at the base of the left femoral neck.[13]
Linear hypointense signal at the base of the femoral neck flanked by a moderate amount of marrow edema. Mild volume of joint effusion.[14]
Cortical fissure at the medial aspect of the femoral neck surrounded by a sclerotic band and edema.[15]

Radiographs

  • Standard Radiographs Hip
    • Views should include AP Pelvis, AP and lateral of hip
  • Findings, when present, include:[16]
    • Periosteal and endosteal callous formation
    • Sclerotic linear region traversing the primary trabeculae of the femoral neck
    • Radiolucent fracture line
  • Up to 2/3 of patients will have normal radiographs
    • 6-8 weeks often required for radiographic changes
    • Around half of patients will never have radiographic changes[17]

MRI

  • Generally considered second line imaging but is the gold standard for FNSF
  • Strongly consider in all athletes with suspected stress fracture and negative XR
  • Sensitivity, specificity and accuracy are 100%[18]
  • Findings include:
    • Diffuse, ill-defined, rounded hypo-intense area (T1-weighted images)
    • Equivalent hyper-intense signal (on fat-suppressed T2-weighted images)
    • When present, the fracture line is seen as a linear area of hypo-intense signal, extending at right angles from the affected cortex

CT

  • Findings
    • Similar to radiographs
    • Sclerosis, new bone, periosteal reaction, fracture line
  • Indication
    • Differentiate stress fracture from malignancy, osteomyelitis

Bone Scan

  • Radionucleotide bone scan largely replaced by MRI
  • Consider if MRI unavailable or patient unable to obtain

Laboratory Evaluation


Classification

Fullerton & Snowdy

  • Type I: fractures occurred on the tension-side of the femoral neck[19]
    • "Tension side" on the superolateral neck
  • Type II: fractures on the compression-side
    • "Compression side" on the inferomedial neck
  • Type III: fractures were displaced

Shin & Gillingham

  • Subdivides type II into fractures lines to greater or less than 50% of the femoral neck[17]

Management

Prevention

  • US Military: Introduction of prompt imaging of all suspected serviceman has lead to a reduction displacd FNSF
  • Limit training volume increases to no more than 10% per week
  • For beginners, total training volume should not exceed 160 km over a 12 week period

Nonoperative

  • Indications
    • Incomplete Compression-type (<50% femoral neck width)
    • Atypical Tension

Operative

  • Indications
    • Incomplete Tension-type
    • Complete Tension-type
    • Complete Compression-type
    • Displaced
  • Technique
    • Dynamic Hip Screw
    • Cannulated Hip Screw

Rehab and Return to Play

Rehabilitation

  • Post-operative
    • Non-weight bearing or toe-touch for 6 weeks
    • Followed by partial weight bearing for 6 weeks
    • Upper Limb: Unrestricted post-operatively
    • Hydrotherapy can start as early as 2 weeks
    • Weight bearing should not commence until radiographic and clinical evidence of fracture union
    • Graduated return to activity typically begins about week 12
    • Physical Therapy: emphasis on hip strength, range of motion
    • Gradual increase in running program during which patient can progress if pain free
  • Non-operative
    • Similar management to operative cases
    • Athlete should be limited weight bearing on crutches until pain free, which typically takes 6-8 weeks
    • Rehabilitation is similar to surgical where there should be clinical and radiographic evidence of fracture union
    • Athlete should be pain free with full activity before return to sport, typically around 12 weeks

Return to Play

  • General
    • Typical full return to sport occurring around 3-6 months
    • Athletes should be followed radiographically for up to 2 years to ensure adequate fixation, lack of pain and absence of AVN
  • Running
    • Ramey et al: mean time to return to running was 14 weeks in one study[20]

Prognosis and Complications

Prognosis

  • Early detection is important[21]
    • Nondisplaced fractures are more easily treated with higher success rates, as high as 100%
    • Undetected fractures that become displaced have a worse prognosis, success rates as low as 0%
  • Displacd FNSF
    • Associated with 100% military discharge rate[22]
    • Post treatmentment AVN, need for further intervention as high as 42%[23]
  • 50% of all athletes fail to return to previous sporting levels[24]
    • Rates are closer to 60% in those who suffer a displaced fracture

Complications

  • Re-fracture
  • Fracture propagation and displacement
  • Surgical complications
    • Avascular Necrosis (24-42%)
    • Non-union (16-44%)
    • Delayed union (8–50%)
    • Malunion (5–33%)
    • Failure of fixation (14%)
    • Need for rvisional surgery (21–50%)
    • Hip Osteoarthritis (68%)

See Also

Internal

External


References

  1. Belcher A. Ueber den Einfluss des Parademarches auf dieEntstehung der Fussgeschwulst. Med Klin. 1905;1:305–306.
  2. Hulkko A, Orava S. Stress fractures in athletes. Int J Sports Med. 1987;8:221–226.
  3. O’Brien J, Taunton J, Larsen J, Forster B B. 31-year-old female runner with 5-week history of hip pain. Br J Sports Med. 2011;45:136–139.
  4. Robertson, Greg A., and Alexander M. Wood. "Femoral neck stress fractures in sport: a current concepts review." Sports Medicine International Open 1.02 (2017): E58-E68.
  5. Image courtesy of thephysiolab.com, "Running with hip pain"
  6. Scott S J, Feltwell D N, Knapik J J, Barkley C B, Hauret K G, Bullock S H, Evans R K. A multiple intervention strategy for reducing femoral neck stress injuries and other serious overuse injuries in U.S. Army Basic Combat Training. Mil Med. 2012;177:1081–1089.
  7. Egol K A, Koval K J, Kummer F, Frankel V H.Stress fractures of the femoral neck Clin Orthop Relat Res 1998. doi:http://www.ncbi.nlm.nih.gov/pubmed/955353672–78.
  8. Kupferer K R, Bush D M, Cornell J E, Lawrence V A, Alexander J L, Ramos R G, Curtis D. Femoral neck stress fracture in Air Force basic trainees. Mil Med. 2014;179:56–61.
  9. Pouilles J M, Bernard J, Tremollieres F, Louvet J P, Ribot C. Femoral bone density in young male adults with stress fractures. Bone. 1989;10:105–108.
  10. Carpintero P, Leon F, Zafra M, Serrano-Trenas J A, Roman M. Stress fractures of the femoral neck and coxa vara. Arch Orthop Trauma Surg. 2003;123:273–277.
  11. Behrens, Steve B., et al. "Stress fractures of the pelvis and legs in athletes: a review." Sports health 5.2 (2013): 165-174.
  12. Neubauer T, Brand J, Lidder S, Krawany M.Stress fractures of the femoral neck in runners: a review. Res Sports Med 2016. doi:10.1080/15438627.2016.11914891–15.
  13. Case courtesy of Hein Els, Radiopaedia.org, rID: 45605
  14. Case courtesy of Hein Els, Radiopaedia.org, rID: 45605
  15. Case courtesy of Roberto Schubert, Radiopaedia.org, rID: 15181
  16. Spitz D J, Newberg A H. Imaging of stress fractures in the athlete. Radiol Clin North Am. 2002;40:313–331.
  17. 17.0 17.1 Shin A Y, Gillingham B L. Fatigue fractures of the femoral neck in athletes. J Am Acad Orthop Surg. 1997;5:293–302.
  18. Shin A Y, Morin W D, Gorman J D, Jones S B, Lapinsky A S. The superiority of magnetic resonance imaging in differentiating the cause of hip pain in endurance athletes. Am J Sports Med. 1996;24:168–176.
  19. Fullerton L R, Jr., Snowdy H A. Femoral neck stress fractures. Am J Sports Med. 1988;16:365–377.
  20. Ramey L N, McInnis K C, Palmer W E. Femoral neck stress fracture: can MRI grade help predict return-to-running time? Am J Sports Med. 2016 doi: 10.1177/0363546516648319.
  21. Pihlajamaki H K, Ruohola J P, Weckstrom M, Kiuru M J, Visuri T I. Long-term outcome of undisplaced fatigue fractures of the femoral neck in young male adults. J Bone Joint Surg Br. 2006;88:1574–1579.
  22. Pihlajamaki H K, Ruohola J P, Kiuru M J, Visuri T I. Displaced femoral neck fatigue fractures in military recruits. J Bone Joint Surg Am. 2006;88:1989–1997.
  23. Visuri T, Vara A, Meurman K O. Displaced stress fractures of the femoral neck in young male adults: a report of twelve operative cases. J Trauma. 1988;28:1562–1569.
  24. Johansson C, Ekenman I, Tornkvist H, Eriksson E. Stress fractures of the femoral neck in athletes. The consequence of a delay in diagnosis. Am J Sports Med. 1990;18:524–528.
Created by:
John Kiel on 5 July 2019 08:29:44
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Last edited:
6 May 2024 00:01:46
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