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http://upload.orthobullets.com/topic/4040/images/southwick.jpg
http://upload.orthobullets.com/topic/4040/images/kleins line_moved.jpg
http://upload.orthobullets.com/topic/4040/images/pinning_moved.jpg
Introduction
  • Disorder of the proximal femoral physis that leads to slippage of the epiphysis relative to the femoral neck
  • Epidemiology
    • incidence
      • most common disorder affecting adolescent hips, found in 10 per 100,000
    • demographics
      • more common in
        • obese children (single greatest risk factor)
        • males (male to female ratio is 3:2)
        • African Americans
        • Pacific islanders
        • during period of rapid growth
      • average age is
        • 13.4 for boys
        • 12.2 for girls
        • associated with puberty
    • location
      • left hip is more common
      • bilateral in 17 to 50%
    • risk factors
      • femoral retroversion
      • obesity (single greatest risk factor for SCFE)
      • history of previous radiation therapy to the femoral head region
  • Pathophysiology
    • mechanism
      • due mechanical forces acting on a susceptible physis
    • pathoanatomy
      • slippage occurs though the hypertrophic zone of the physis 
        • caused by weakness of the perichondral ring
        • cartilage in the hypertrophic zone acts as a weak spot 
      • epiphysis stays in the acetabulum while the neck displaces anteriorly and externally rotates (epiphysis is posterior)
  • Associated conditions
    • endocrine disorders
      • conditions to look for  
        • hypothyroidism (labs show elevated TSH)
        • osteodystrophy of chronic renal failure (abnormal BUN and creatinine)
        • growth hormone treatment
      • indications for endocrine workup
        • child is < 10 years old
        • weight is < 50th percentile
Classification
 
Stable vs. Unstable Classification (Loder Classification)
Stable Able to bear weight with or without crutches
Minimal risk of osteonecrosis (<10%)
Unstable Unable to ambulate (not even with crutches)
Associated with high risk of osteonecrosis (~47%)
  • Provides prognostic information
 
Temporal Classification (rarely used)
Acute Symptoms that persist for less than 3 weeks
Chronic Symptoms that persist for more than 3 weeks
Acute on Chronic Acute exacerbation of long-standing symptoms
 
Southwick Angle Classification
Mild <30°
Moderate 30-50°
Severe >50°
  • Measurement of the difference between both hips in the femoral head-shaft angle on the frog lateral radiograph  
  • Difference between these two angles obtained on the affected and unaffected sides determines the degree of slip and resulting abnormal alignment
 
 Grading System for SCFE
Grade I 0-33% of slippage
Grade II 34-50% of slippage
Grade III >50% of slippage
 
Presentation
  • Symptoms
    • groin and thigh pain
      • most common presentation
    • knee pain
      • can frequently present as knee pain (15-23%)   
    • motion
      • patients prefer to sit in a chair with affected leg crossed over the other
    • duration
      • symptoms are usually present for weeks to several months before diagnosis is made
  • Physical exam
    • abnormal gait
      • coxalgic, externally rotated gait or Trendelenburg gait
    • decreased hip motion
      • obligatory external rotation during passive flexion of hip
      • loss of hip internal rotation, abduction, and flexion
    • abnormal leg alignment
      • externally rotated foot progression angle
    • weakness
      • thigh atrophy
Imaging
  • Radiographs
    • recommended views
      • AP & frog-leg lateral of right and left hip 
        • lateral radiograph is best way to identify a subtle slip
    • findings on AP of pelvis
      • Klein's line 
        • line drawn along superior border femoral neck will not intersect femoral head in a child with SCFE (does in a normal hip) 
      • epiphysiolysis (growth plate widening or lucency) 
        • an early radiographic findings
      • blurring of proximal femoral metaphysis (metaphyseal blanch sign of Steel)
        • seen on AP due to overlapping of the metaphysis and posteriorly displaced epiphysis
  • MRI 
    • indications
      • can help diagnose a preslip condition when radiographs are negative
    • findings
      • shows growth plate widening and increased signal of the metaphysis
Treatment
  • Operative
    • percutaneous in situ fixation   
      • indications
        • both stable and unstable slips
      • technique
        • one vs. two cannulated screws is controversial
          • 2 screw constructs have greater biomechanically stable than the single screw constructs 
          • benefit of 2 screws needs to be considered in the face of greater violation of the physis +/- articular surface
    • contralateral in situ prophylactic pinning (bilateral in situ fixation)
      • indications   
        • remains controversial
        • current indications are high risk patients (contralateral slip ~ 40-80%)
          • obese males
          • endocrine disorders (e.g. hypothyroidism)
          • initial slip at younger age (<10 years old or have open triradiate cartilage)
    • epiphyseal reduction and pinning
      • indications
        • reduction remains controversial
        • unstable, high grade SCFEs
    • proximal femoral osteotomy
      • indications
        • correction of painful or function-limiting proximal femoral deformities associated with severe, chronic slip
Techniques
  • Percutaneous in situ fixation
    • goal
      • stabilize the epiphysis from further slippage and promote closure of the proximal femoral physis 
    • technique
      • reductions
        • forceful reduction is not indicated and increases risk of osteonecrosis
        • "serendipitous reduction" is often obtained with positioning
      • screw fixation
        • single cannulated screw sufficient and decreases risk of osteonecrosis (compared to multiple pins) in unstable SCFE   
        • screw must start on the anterior surface of the neck in order to cross perpendicular to the physis enter into the central portion of the femoral head  (which has slipped posteriorly) on both the AP and lateral views 
        • minimum of 3 threads crossing the physis
        • screws should be at least 5mm from subchondral bone in all views
      • imaging
        • use fracture table to obtain good radiographic visualization
        • rotate under live fluoroscopy to confirm that pin is not penetrating the hip joint
    • postoperative
      • stable slips are able to bear weight after in situ pinning
      • unstable slips are made non-weight bearing
  • Open reduction with capital realignment
    • techniques
      • surgical dislocation with epiphyseal reorientation
      • modified Dunn procedure with formation of a epiphyseal vascular flap
  • Proximal femoral osteotomy
    • techniques
      • can be performed at the subcapital, femoral neck, intertrochanteric and subtrochanteric regions
      • subcapital and femoral neck osteotomies provide the most correction but are associated with the highest risks of osteonecrosis and should be avoided
    • typical correction consists of flexion, valgus and derotation
Complications 
  • Osteonecrosis of femoral head (4-6%)    
    • may occur as the result of
      • initial trauma
        • increased risk with high grade slips (~45-50%)
      • operative complication (4-6%)
        • hardware placement in posteriosuperior femoral neck has the greatest risk of disrupting the vascular supply 
  • Contralateral hip SCFE
    • most common complication after unilateral surgical fixation (20-80%) 
      • risk factors for contralateral slip include
        • male, obesity, young age of initial slip, endocrine disorders
  • Chondrolysis (0-2%)
    • associated with
      • unrecognized implant penetration of the articular surface (0-2%)
      • spica cast immobilization
      • decreased prevalence with modern fluoroscopy
  • Residual proximal femoral deformity & limb length discrepancy
    • increased α-angle associated with symptomatic impingement
    • caused by failure of proximal femur to remodel
    • treatment
      • intertrochanteric osteotomy (Imhauser) 
        • produces flexion, internal rotation and valgus
      • subtrochanteric osteotomy (Southwick's)
      • cuneiform osteotomy (controversial due to high rate of osteonecrosis and arthritis)
  • Slip progression
    • occurs in 1-2% of cases following single screw fixation
  • Infection (0-2%)
  • Chronic pain (5-10%)
  • Degenerative arthritis 
  • Pin associated proximal femur fracture
  • Labral tearing and degeneration
    • seen with high anterior and medial 2nd screw in-situ fixation 
 
 

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Questions (14)

(OBQ12.240) A 12-year-old mildly overweight female presents with complaints of left hip pain. She is not dependent on crutches for ambulation. Physical examination reveals external rotation of the extremity with hip flexion. Her parents indicate that outside radiographs were interpreted to be normal. They present an MRI of the pelvis, as shown in Figures A and B. What is next best step in management? Review Topic

QID:4600
FIGURES:
1

Observation

1%

(28/2022)

2

Arthroscopic labral repair

0%

(7/2022)

3

In situ screw fixation

91%

(1832/2022)

4

Closed reduction and percutaneous pinning

7%

(134/2022)

5

Debridement of CAM impingement femoral lesion

0%

(9/2022)

Select Answer to see Preferred Response

PREFERRED RESPONSE 3

Based on the clinical history and imaging provided, the patient has a diagnosis of a stable slipped capital femoral epiphysis. Considering the normal interpretation of the radiographs, either the read was incorrect or the slip had worsened by the time the MRI was obtained. Based on these findings, the next best step in management is in situ percutaneous screw fixation.

Slipped capital femoral epiphysis (SCFE) is a slippage of the epiphysis relative to the femoral neck through the zone of hypertrophy. The ability to bear weight without crutches indicates minimal risk of AVN (< 10%). An MRI can be useful in the diagnosis of SCFE when plain radiographs are normal; there is increased edema within the metaphysis and physeal widening. Treatment requires percutaneous in-situ pinning.

Umans et al. reviewed 13 patients with 15 symptomatic hips secondary to SCFE who had radiographs and MRI studies completed. They found that on MRI, patients with SCFE or pre-slip conditions, were found to have physeal widening and metaphyseal marrow edema. These findings were present at times when CT and radiographs were normal. They recommend use of MRI to evaluate for SCFE when radiographs are normal.

Shank et al. describe treatment and management of 12 patients with the less common valgus SCFE. They found that these patients presented at a younger age and were predominantly female. 33% of patients had a endocrine disturbance. In this patient population they recommend a more medial starting point to account for the valgus.

Figures A and B show representative coronal sequences from a T2 weighted MRI of the pelvis in a patient with a slipped epiphysis. Notice the increased signal within the metaphyseal region and widening of the physis.

Incorrect Answers
Answer 1: Observation is not indicated as left alone, the SCFE may further displace.
Answers 2, 5: There is no evidence of a labral tear on the MRI or the presence of a CAM bump on the femoral neck.
Answer 4: Closed reduction is not indicated in this stable SCFE. This may in fact lead to increased rates of AVN.


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(OBQ12.259) A 13-year-old male presents with left hip pain and an inability to ambulate. He does not have a history of kidney disease. The initial radiograph is shown in Figure A. Which of the following zones of the growth plate (Figures B-F, all the same magnification) is most commonly involved in this condition? Review Topic

QID:4619
FIGURES:
1

Figure B

2%

(67/3110)

2

Figure C

16%

(488/3110)

3

Figure D

66%

(2059/3110)

4

Figure E

13%

(396/3110)

5

Figure F

2%

(70/3110)

Select Answer to see Preferred Response

PREFERRED RESPONSE 3

The radiograph and clinical presentation are consistent with slipped capital femoral epiphysis, which most commonly injures the hypertrophic zone of the growth plate, demonstrated in Figure D. It should be noted that SCFE secondary to renal osteodystrophy occurs at the secondary spongiosa.

The normal growth plate consists of the reserve zone (resting zone), proliferative zone, zone of hypertrophy, and primary spongiosa (or vascular invasion zone). The reserve zone is characterized by a sparse distribution of chondrocytes in a vast matrix. The proliferative zone is characterized by longitudinal columns of flattened chondrocytes, and is responsible for longitudinal growth. The zone of hypertrophy consists of chondrocytes that are 5-10x the size of normal chondrocytes, and is responsible for the synthesis of novel matrix proteins. Finally, the primary spongiosa (or zone of vascular invasion) consists of chondrocytes that are in the process of becoming mineralized, as well as a dense supply of vascular tissue.

Aronsson et al. review slipped capital femoral epiphysis. They note there is an increased incidence of chondrocyte degeneration and death within the hypertrophic zone in the pathological state.

Kandzierski et al. perform a morphological analysis of the shape of the proximal femoral growth plate in children ages 6 to 13. They found that a change in the shape of this growth plate from pleated to spherical is a risk factor for SCFE in children older than 10 years of age.

Figure A is an AP pelvis radiograph showing a left-sided slipped capital femoral epiphysis. Figure D is the zone of hypertrophy. Note the large chondrocytes that are 5-10x the size of normal chondrocytes. Illustration A shows all of the zones of the growth plate in one image.

Incorrect Answers:
Answer 1: Figure B is the resting, or reserve zone. Note the sparse distribution of chondrocytes. The resting zone is frequently associated with Gaucher's, pseudoachondroplasia, and diastrophic dysplasia.
Answer 2: Figure C is the proliferative zone. Note the chondrocytes are arranged in longitudinal columns. The proliferative zone is frequently associated with achondroplasia, gigantism, and MHE.
Answer 4: Figure E is the primary spongiosa, or vascular invasion zone.
Answer 5: Figure F shows another example of the proliferative zone.

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(OBQ11.81) An 11-year-old obese male presents with a slipped capital femoral epiphysis. Which of the following figures accurately represents the method used to determine the radiographic severity of the epiphyseal slip and help guide treatment? Review Topic

QID:3504
FIGURES:
1

Figure A

84%

(2339/2787)

2

Figure B

14%

(389/2787)

3

Figure C

1%

(20/2787)

4

Figure D

1%

(20/2787)

5

Figure E

1%

(15/2787)

Select Answer to see Preferred Response

PREFERRED RESPONSE 1

Figure A represents the Southwick method of determining slip severity, and this can help guide treatment and determine slip severity. Determining the severity of SCFE using the Southwick method or slip angle is accomplished by subtracting the epiphyseal-shaft angle on the uninvolved side from that on the side with SCFE on the frog leg lateral pelvis radgiograph. The degree of slip is classified as mild (<30°), moderate (30° to 50°),or severe (>50°). Figure A shows an example of this calculation, where the slip angle is 44 degrees.

Aronson et al discuss the early findings of SCFE on AP pelvis and frog leg lateral radiographs including the use of Klein's line and the presence of the metaphyseal blanch sign of Steel. They also discuss two radiographic methods to determine SCFE severity; the Southwick method and measuring the displacement of the epiphysis on the metaphysis. This second method is classified based on displacement in relation to the width of the metaphysis: mild (<33%), moderate (33% to 50%), or severe (>50%). Illustration A is a figure from their article demonstrating this method.

Southwick et al reported their results and technique of osteotomy through the lesser trochanter for treatment of SCFE. They had no necrosis of the femoral head and generally good results.

Incorrect Answers:
Answer 2: Figure B shows a left side SCFE as demonstrated by Klein's line. This line is drawn parallel to anterosuperior aspect of the femoral neck to determine level of intersection with epiphysis.
Answer 3: Angle between the Hilgenreiner line and a line drawn from the triradiate epiphysis to the lateral edge of the acetabulum. This describes the method used to measure acetabular index in cases of DDH, and is shown in Figure C.
Answer 4: Degree of disruption in line drawn from the medial aspect of the femoral neck to the inferior border of the pubic rami. This describes the measurment of Shenton's line, and is shown in Figure D. A disruption in Shenton's line can indicate the presence of hip subluxation or dislocation.
Answer 5: Figure E shows the center edge angle measurement. It is defined as the angle formed by a line drawn through the center of the femoral head and the edge of the acetabulum and another line perpendicular to a line drawn through the center of the femoral heads. It can also be useful in diagnosing DDH.

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(OBQ11.127) A 12-year-old girl presents with groin pain six months after treatment of a slipped capital femoral epiphysis. Preoperative radiographs are seen in Figure A, radiographs six months after in situ fixation are seen in Figure B. Which of the following is associated with the radiographic abnormality seen in Figure B? Review Topic

QID:3550
FIGURES:
1

Lack of reduction prior to fixation

8%

(106/1344)

2

Single screw fixation

6%

(79/1344)

3

Female sex

3%

(45/1344)

4

Inability to bear weight preoperatively

77%

(1037/1344)

5

Obesity

6%

(74/1344)

Select Answer to see Preferred Response

PREFERRED RESPONSE 4

The patient presents with femoral head osteonecrosis (Figure B), following in-situ screw fixation of a severe SCFE (Figure A). The inability to bear weight, even with assistive devices, preoperatively indicates an unstable SCFE, which is associated with significantly increased rates of osteonecrosis.

Kennedy et al retrospectively reviewed the rates of osteonecrosis for patients with stable and unstable SCFEs at a single institution. Patients identified as having an unstable SCFE based on the clinical criteria of inability to bear weight were found to have significantly increased risk for development of osteonecrosis (4 of 27 patients). None of the patients with stable slips had evidence of osteonecrosis (0 of 272 patients).

In their review of the management of slipped capital femoral epiphysis, Aronsson et al state that those patients with an unstable SCFE may have rates of osteonecrosis as high as 50%. Patient with a stable SCFE have rates of osteonecrosis of 0-5%.

Incorrect Answers:
Answer 1: In-situ screw fixation of unstable SCFE has not been show to be a risk factor for osteonecrosis.
Answer 2: Fixation with a single screw, although less stable than alternative methods, does not lead to increased risk of osteonecrosis.
Answer 3: Sex is not predictive of rates of osteonecrosis.
Answer 5: Obesity is not associated with osteonecrosis


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(OBQ10.66) A 13-year-old boy complains of a 3-month history of left knee, thigh and groin pain. His pain has significantly worsened over the past week. He denies pain in the right leg. Radiographs are taken and shown in Figures A and B. The history and physical do not reveal any findings concerning for an endocrine disorder. What is the preferred method of treatment? Review Topic

QID:3153
FIGURES:
1

Subtrochanteric valgus, extension, and external rotational osteotomy

1%

(11/2169)

2

Non weight bearing on the left side for 6 weeks.

1%

(28/2169)

3

Bilateral in situ single screw insertion across the proximal femoral physis

9%

(190/2169)

4

In situ single screw insertion across the left proximal femoral physis only

89%

(1921/2169)

5

Varus derotational osteotomy of the proximal femur

1%

(15/2169)

Select Answer to see Preferred Response

PREFERRED RESPONSE 4

Acute or acute on chronic slipped capital femoral epiphysis (SCFE) can be adequately stabilized with a single percutaneous screw fixation across the proximal femoral physis.

Goodman et al retrospectively demonstrated that in situ, single screw fixation across the proximal femoral physis in patients with acute or acute on chronic SCFE, was sufficient to allow closure of the physis with no change in head-shaft angles from the preoperative radiographs.

Morrissy in an instructional course lecture, illustrates the principles of in situ fixation in chronic SCFE. Pinning of the contralateral physis should strongly be considered for boys under 12 and girls under 10, the presence of an open triradiate cartilage, or evidence of an endocrinopathy.


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(OBQ07.2) Southwick angle (epiphyseal-shaft angle) serves what purpose in the evaluation of a slipped capital femoral epiphysis (SCFE)? Review Topic

QID:663
1

Determine prognosis for AVN

5%

(51/995)

2

Determine the severity of the slip

85%

(841/995)

3

Determine the presence or absence of a slip

9%

(90/995)

4

Determine the etiology of a slip

0%

(4/995)

5

Determine the chronicity of the slip

0%

(4/995)

Select Answer to see Preferred Response

PREFERRED RESPONSE 2

The epiphyseal-shaft angle, as described by Southwick, is measured on the frog-leg lateral radiograph to determine the degree of the slip, which is calculated by subtraction of the angle on the normal side from the angle of the affected hip. The Southwick angle is also helpful when planning an osteotomy for post-SCFE impingement.

The classification of SCFE based on grading the severity of the slip by xrays is the Southwick angle and is based on the difference between the two hips on the cross-table lateral: 1) mild, 0 to 29 degrees; 2) moderate, 30 to 60 degrees; severe, 3) greater than 60 degrees. The classic xrays to view a slip are the AP pelvis and frog-leg lateral. The frog leg lateral often gives a better image of the slip compared to the AP b/c the epiphysis is posterior relative to the neck and this is better seen on a lateral view.

Aronsson et al provides a good overview of SCFE, including the different classifications utilized. The Loder classification identifies stable vs unstable slips and provides prognostic information in regards to likelihood of AVN. Kleins line is used to identify the presence of a slip. The age or chronicity of the slip is based on the duration of symptoms, with acute being <3wks and chronic >3wks of symptoms. The article also reviews treatment options and confirms that the treatment of choice for stable chronic SCFE is stabilization in situ with single-screw fixation.

Illustration A shows the epiphyseal-shaft angle is 44 degrees (56 degrees minus 12 degrees). Illustration B is a picture of Klein’s Line on AP Xrays with SCFE on patient’s Left.

ILLUSTRATIONS:

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(OBQ07.187) Which of the following treatment techniques decreases the risk of osteonecrosis in patients with unstable slipped femoral capital epiphysis (SCFE)? Review Topic

QID:848
1

Open reduction and pinning with multiple cannulated screws in an inverted triangle configuration

7%

(24/342)

2

Closed reduction and pinning with multiple cannulated screws in an inverted triangle configuration

6%

(22/342)

3

Closed reduction and pinning with a single cannulated screw

8%

(29/342)

4

In situ percutaneous pinning with multiple cannulated screws in an inverted triangle configuration

9%

(31/342)

5

In situ percutaneous pinning with a single cannulated screw

68%

(234/342)

Select Answer to see Preferred Response

PREFERRED RESPONSE 5

As described in the review article by Loder, an unstable SCFE is one where the child cannot walk, with or without crutches. Reduction attempts of unstable SCFE have been associated with a higher rate of osteonecrosis after pinning. Osteonecrosis is also more likely to develop in patients treated with multiple pins than in those treated with a single cannulated screw. However, in unstable SCFE's surgeons often elect to utilize two screws for stabilization. Inverted triangle screw placement is utilized for adults with femoral neck fractures.

Tomkmakova concluded that: "Pinning in situ without reduction with a single cannulated screw is the method of choice for the treatment of a slipped capital femoral epiphysis."


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(OBQ06.183) Hypothyroidism is most commonly associated with which of the following pediatric conditions? Review Topic

QID:369
1

Legg Calve Perthes

3%

(30/889)

2

Slipped capital femoral epiphysis

90%

(797/889)

3

Toxic synovitis

0%

(3/889)

4

Achondroplasia

2%

(19/889)

5

Rickets

4%

(38/889)

Select Answer to see Preferred Response

PREFERRED RESPONSE 2

SCFE is a disorder of the proximal femoral epiphysis caused by weakness of the perichondral ring and slippage through the hypertrophic zone of the growth plate. The femoral neck displaces anteriorly and externally rotates. An AP radiograph, shown in Illustration A, and lateral (as the epiphysis most commonly appears posterior to the metaphysis) views often can illustrate the deformity seen with SCFE. Consideration is given to obtaining a cross table lateral view as a frog-lateral may worsen the unstable slip. SCFE is seen most commonly in African American, obese, and adolescent boys (10 – 16 yrs old) with a positive family history. Twenty-five to 50% of cases are bilateral and thought to be related to hormonal disorders in young children, such as hypothyroidism or renal osteodystrophy. Careful endocrine screening is warranted in at risk patients. Loder et al reviewed 85 pediatric patients with both SCFE and endocrine disorders and found hypothryoidism in 40% and growth hormone deficiency in 25%. All the patients with hypothyroidsim developed bilateral SCFE.

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(OBQ05.60) An 11-year-old girl with hypothyroidism and obesity presents with groin pain and the inability to ambulate. Her radiograph is shown in Figure A. What is the most appropriate treatment? Review Topic

QID:946
FIGURES:
1

Toe-touch weightbearing for 3 weeks

0%

(4/952)

2

Hip spica cast and non-weight bearing for 4 weeks

1%

(8/952)

3

In situ pinning of the right hip

13%

(123/952)

4

Open reduction and pinning of the right hip

2%

(20/952)

5

In situ pinning of both hips

83%

(794/952)

Select Answer to see Preferred Response

PREFERRED RESPONSE 5

The radiographs show a slipped capital femoral epiphysis (SCFE) of the right hip. Patients with endocrine disease such as hypothyroidism commonly demonstrate prevalence of bilaterality (as high as 80% in some reports), prophylactic treatment of the opposite hip should be considered. When adding additional risks of contralateral hip slip of obesity and young age and the significant morbidity of displacement of slipped capitol femoral epiphysis, the controversy of prophylactic contralateral pinning is diminished.

The general recommendations for prophylactic pinning include inability to obtain regular follow up, metabolic/endocrine disorders, open triradiate cartilage, girls younger than 10, and boys younger than 12.5 years.

Riad et al evaluated chronological age at presentation, sex, race and status of triradiate cartilage and a modified Oxford bone age were assessed. In this analysis, chronological age was the only significant predictor for developing a contralateral slip.

Loder et al reviewed 85 patients with endocrine disorders and slipped capital femoral epiphysis (SCFE). They found the average age at diagnosis was 13.2 years and only patients with hypothyroidism or growth hormone deficiency were diagnosed at ages less than 10 years. Because of the rate of SCFE occurring bilaterally, these authors recommend prophylactic pinning of the contralateral hip.

Schultz et al used a decision analysis model predicting the probabilities of occurrence of a contralateral slip and the associated severity of that slip to analyze the benefit of prophylactic pinning. Their data suggest that treatment of the contralateral hip with prophylactic pinning is beneficial to the long term outcome of that hip. As such, they recommend this treatment for patients at high risk of SCFE.


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(OBQ05.125) A 13-year-old Polynesian boy presents with left groin pain and inability to place weight on the left leg. His radiographs are shown in Figures A and B. All of the following are true regarding this condition EXCEPT: Review Topic

QID:1011
FIGURES:
1

The left hip is more commonly involved

24%

(183/769)

2

Forceful manipulation is not indicated because it is associated with an increased risk of complications

2%

(19/769)

3

Associated with decreased femoral anteversion and decreased femoral neck-shaft angle

20%

(152/769)

4

Pain is localized to the knee more often than the hip on initial presentation

51%

(392/769)

5

Males are more commonly affected than females

3%

(22/769)

Select Answer to see Preferred Response

PREFERRED RESPONSE 4

This patient has a left slipped capital femoral epiphysis. Option 4 is incorrect as hip pain is more common then knee pain. Options 1,2,3, and 5 are all true statements as stated in AAOS Comprehensive Orthopaedic Review.

Matava et al reviewed 106 patients with SCFE and found that 77-85% presented with hip or groin pain. 15%- 23% of patients had complaints of knee pain or distal thigh pain, which can lead to unnecessary tests or misdiagnoses.

The review article by Calmbach and Hutchens states that SCFE should still be in the differential diagnosis in children presenting with knee pain.


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(OBQ05.162) A 14-year-old boy presents with left groin and knee pain for 3 weeks. He is now unable to place weight on the left lower extremity, even with the assistance of crutches. AP pelvis radiograph is shown in Figure A. He is treated with surgical intervention and post-operative radiographs are shown in Figures B and C. What is the most common limb length and rotational profile found as a sequelae of this condition? Review Topic

QID:1048
FIGURES:
1

Limb shortening, decreased hip flexion and decreased hip internal rotation

82%

(643/781)

2

Limb lengthening, increased hip flexion, and increased hip internal rotation

0%

(2/781)

3

Limb lengthening, decreased hip flexion, and decreased hip external rotation

3%

(25/781)

4

Limb shortening, decreased hip flexion, and increased hip internal rotation

6%

(49/781)

5

Limb shortening, increased hip flexion, and decreased hip internal rotation

7%

(58/781)

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PREFERRED RESPONSE 1

This patient underwent in-situ pinning of an unstable slipped capital femoral epiphysis (SCFE). Forceful manipulation is not indicated because it is associated with an increased risk of osteonecrosis. Patients with SCFE can present with an out-toeing gait, limb shortening, decreased hip flexion, decreased hip abduction, and decreased hip internal rotation. A frequently seen sign associated with SCFE includes obligatory abduction and external rotation during passive hip flexion from an extended position.

Level 4 evidence by Song et al reviewed 20 unilateral SCFE patients. With increasing slip angles, passive hip flexion, hip abduction, and internal rotation decreased significantly.

The study by Rab used computer modeling of SCFE patients to determine that posterior epiphyseal displacement in the plane of the physis is the etiology for the resultant deformities found in SCFE. Additionally, they found that sitting increases impingement for all slip geometries, requiring proportionately greater external rotation and accounting for why patients feel better to cross the affected leg while sitting in a chair.


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(OBQ04.67) A 14-year-old female presents with a history of an undiagnosed left slipped capital femoral epiphysis 3 years ago. She has 2 years of activity-related left hip pain and pain with prolonged sitting. On physical examination she has restricted hip flexion motion, an external rotation deformity, and obligatory external rotation upon hip flexion manuevering. Radiographs are shown in Figures A and B. Which of the following osteotomies is MOST appropriate? Review Topic

QID:1172
FIGURES:
1

Medial displacement Chiari salvage osteotomy

1%

(6/724)

2

Proximal femoral varus osteotomy

3%

(25/724)

3

Flexion, internal rotation, and valgus-producing proximal femoral osteotomy (Imhauser osteotomy)

74%

(537/724)

4

Bernese periacetabular osteotomy with extension, external rotation, and valgus-producing femoral osteotomy

5%

(38/724)

5

Valgus-producing intertrochanteric proximal femoral osteotomy (Pauwel osteotomy)

16%

(117/724)

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PREFERRED RESPONSE 3

The Imhauser osteotomy (as shown in Illustration A) is described to correct the deformity often seen in the late treatment of SCFE. The osteotomy produces flexion, internal rotation and valgus (as shown in Illustration B).

This correction is obtained via an anterior-based closing wedge osteotomy, rotating the distal fragment internally, and utilizing the blade plate to create valgus. Valgus correction can be incorporated into the osteotomy to correct the medial displacement of the epiphysis. The osteotomy was designed to correct the retroversion deformity, improve hip motion and mechanics, and decrease the incidence of osteoarthritis. The retroversion deformity seen in late SCFE may cause anterior femoroacetabular impingement through a cam type mechanism, which may contribute to the early development of osteoarthritis.

Kuzyk et al present level 5 evidence stating that surgical hip dislocation is another option for post-SCFE hip impingement, and severe cases with a high epiphyseal-shaft angle may require both dislocation and intertrochanteric osteotomy.

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(OBQ04.83) A right hip of an 8-year-old patient is modeled in Figure A. Which of the following vessels gives the greatest blood supply to the femoral head? Review Topic

QID:1188
FIGURES:
1

1

1%

(10/840)

2

2

1%

(7/840)

3

3

85%

(713/840)

4

4

10%

(81/840)

5

5

3%

(26/840)

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PREFERRED RESPONSE 3

Answer 3 depicts the medial circumflex artery, which is the dominant blood supply of the femoral head in an 8-year-old.

The medial circumflex artery is the dominant blood supply to the femoral head in children older than 4 years of age. The lateral circumflex artery and ligamentum teres supplies a portion of the anterior femoral head until 2 to 4 years of age. When treating a patient with a SCFE its important to note that when multiple pins are placed in the posterosuperior quadrant, the lateral epiphyseal vessels may be damaged. This risk is minimized by placing a single screw in the center of the epiphysis.

Loder et al describes the vascular supply to the femoral head. The most important contribution to the vascular supply of the femoral head is from the posterosuperior lateral epiphyseal vessels that originate from the medial circumflex artery. These lateral epiphyseal vessels anastomose with the vessels from the round ligament and the posteroinferior epiphyseal vessels at the junction of the medial and central thirds of the femoral head.

Illustration A shows a labeled Figure A. Illustration B shows the epiphyseal vessels that originate from the medial circumflex artery.

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(OBQ04.165) A 14-year-old overweight boy complains of vague left knee pain which worsens with activity. He has an antalgic gait and increased external rotation of his foot progression angle compared to the contralateral side. Knee radiographs, including stress views, are negative. What is the next step in management? Review Topic

QID:1270
1

Knee MRI

1%

(6/717)

2

Knee CT

0%

(2/717)

3

AP pelvis and frog-lateral views

98%

(701/717)

4

Diagnostic knee arthroscopy

0%

(2/717)

5

Hip MRI

1%

(4/717)

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PREFERRED RESPONSE 3

In an adolescent boy with knee pain, always examine the hips and consider hip pathology, especially if the knee workup is negative. Matava et al discusses knee pain as the initial symptom of SCFE. This retrospective review of 65 patients found that 15 (23%) noted distal thigh pain, knee pain, or both as the presenting symptom. 12 were chronic slips (>3 weeks of pain) and 3 acute-on-chronic. Knee and thigh pain resulting from intra-articular hip pathology is a referred pain phenomenon, and is a common reason for misdiagnosis of SCFE leading to delay in treatment, possible further displacement, and worse prognosis.


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