Orthopedic Teaching Cases 2023, Jan, 17 | 12:00 am

6 Pediatrics CASES

CASE                                6                               

 

A 12-year-old girl presents to clinic with complaints of right hip pain over the last 2 weeks. She reports that her pain has progressively worsened and has had difficulty bearing weight. She denies any trauma to her hip, fevers, chills, or night sweats. She also endorses a 2-year history of intermittent left hip pain. Physical examination is notable for a well-appearing adolescent girl, weight of 85 kg, and bilateral hip pain (right > left) with range of motion, pain with logroll, and limited internal rotation. X-rays of the pelvis/hip were obtained (Fig. 10–9A–C).

 

Figure 10–9 A

 

 

Figure 10–9 B–C

 

Which of the following are risk factors associated with the condition shown in

Figure 10–9A–C?

  1. Age

  2. Weight

  3. Femoral anteversion

  4. Endocrinopathies

  5. A, B, and D

  6. All of the above

 

Discussion

The correct answer is (E). Obesity has been found to be the greatest risk factor for developing slipped capital femoral epiphysis (SCFE). The etiology of this condition is thought to be a combination of biomechanical and biochemical factors that weaken the physis. Femoral retroversion is thought to increase the load across the physis, particularly when in an obese patient. It is femoral retroversion, not femoral anteversion, that is a risk factor for SCFE. SCFE has also been shown to be associated with endocrine disorders such as hypothyroidism, osteodystrophy of chronic renal failure, and hypogonadism. SCFE is most common in children ages 10 to 16 (12–16 for boys and 10–14 for girls).

You discuss the risk and benefits of surgical management with the patient’s parents, and they elect to proceed with surgery. You recommend single-screw fixation.

What is the ideal position of the screw in single-screw fixation?

  1. Anteroinferior to the epiphysis, perpendicular to the physis, and <5 threads engaged in the epiphysis

  2. Center of the epiphysis, perpendicular to the physis, and ≥5 threads engaged in the epiphysis

  3. Center of the epiphysis, perpendicular to the physis, and <5 threads engaged in the epiphysis

  4. Posterosuperior to the epiphysis, oblique to the physis, and ≥5 threads engaged in the epiphysis

  5. Posterosuperior to the epiphysis, perpendicular to the physis, and <5 threads engaged in the epiphysis

Discussion

The correct answer is (B). The ideal position for single-screw fixation is in the center of the epiphysis, perpendicular to the physis (best achieved with a start point on the anterior surface of the femoral neck), and at least 5 threads engaged in the

epiphysis. Carney et al. reported progression of greater than 10 degrees in 9 out of 22 patients with <5 threads across the physis versus none in patients with ≥5 threads engaged in the epiphysis. Placement of the screw into the posterosuperior femoral neck can disrupt the vascular supply and result in osteonecrosis.

Which of the following statements is true with regards to the development of osteonecrosis of the affected hip?

  1. Complete or partial reduction of an unstable SCFE increases the risk of osteonecrosis

  2. Screw position has not been shown to affect the rate of osteonecrosis

  3. Higher rates of osteonecrosis are associated with grade 1 (mild) SCFE

  4. Multiple screw fixation has been shown to decrease the rate of osteonecrosis

 

Discussion

The correct answer is (A). A study by Tokmakova found that complete or partial reduction of an unstable SCFE, greater severity of slip at time of presentation, multiple pin fixation, pin penetration, and pin position are associated with increased risk of osteonecrosis.

If this patient had presented to your clinic prior to the acute slip of her right hip, what would be the indications for prophylactic screw fixation?

  1. Age at presentation <10 years

  2. Family history of SCFE

  3. History of endocrinopathies (hypothyroidism or growth hormone deficiency)

  4. A and B

  5. A and C

 

Discussion

The correct answer is (E). Although there is controversy with recommendations for prophylactic fixation of an asymptomatic contralateral hip, there are studies to support prophylactic fixation in patients with risk factors for bilateral hip involvement. The overall reported rate of bilateral hip involvement ranges from 17% to 50% in all-comers and higher in those with endocrine disorders. Loder et al. reported a prevalence of bilateral hip involvement in 61% of patients with hypothyroidism or growth hormone deficiency. A decision analysis model developed by Schultz et al. also supported prophylactic pining in patients at high risk for contralateral slip, including those with endocrinopathies, obese children,

age <10 years, or open triradiate cartilage.

 

Objectives: Did you learn...?

 

 

The risk factors associated with slipped capital femoral epiphysis? Ideal positioning for single-screw fixation?

 

Risks associated with osteonecrosis?

 

Indications for prophylactic fixation of an asymptomatic contralateral hip?