Summary

Slipped Upper Femoral Epiphysis (SUFE) is the displacement of the femoral neck relative to the femoral head, occurring through the physis (Growth Plate). It is a Salter-Harris Type I fracture. It typically affects obese male adolescents (12-16 years) during a rapid growth spurt. Classification into Stable (able to weight bear) and Unstable (unable to weight bear) is critical, as unstable slips carry a 50% risk of Avascular Necrosis (AVN). Treatment is definitive surgical stabilization (Pinning In Situ). [1,2,3]

Key Facts

• The "Ice Cream Scoop": The femoral head (scoop) stays in the acetabulum. The neck (cone) slips anteriorly and superiorly. (So the head is technically posterior and inferior).
• The "Obligatory External Rotation": As you flex the patient's hip, the leg automatically rotates outwards. This is pathognomonic.
• Bilateral Risk: 20-40% of cases become bilateral. We often pin the other side prophylactically, especially in younger patients with endocrine issues.

Clinical Pearls

"The Painless Knee": 50% of SUFEs present with ONLY knee pain (referred via Obturator nerve). Every teenager with a sore knee needs a hip exam.

"Don't Reduce It!": Trying to force the bone back into place stretches the retinacular vessels and causes AVN. We pin it "as it lies" (In Situ) to prevent further slip.

"Fat and Young = Endocrine": A SUFE in a 10-year-old or a thin patient is weird. Check Thyroid (TSH), Renal function, and Growth Hormone.

                 ADOLESCENT HIP PAIN
                        ↓
                  X-RAY (AP + FROG)
             ┌──────────┴──────────┐
          NORMAL                 SLIP CONFIRMED
             ↓                         ↓
         CONSIDER MRI          ASSESS STABILITY
        (Pre-slip?)          (Can they walk?)
                             ┌─────────┴─────────┐
                          STABLE              UNSTABLE
                             ↓                   ↓
                        URGENT OR           EMERGENCY OR
                     (Pin In Situ)       (Decompression + Pin)
                                             (High AVN Risk)

1. Surgery: Screw Fixation In Situ (Gold Standard)

• Technique: A single cannulated screw (6.5mm or 7.3mm) passed through the neck into the center of the head.
• Goal: Prevent further slip. Encourage fusion of the physis.
• Trajectory: Must be in the center to avoid Joint Penetration.
• Reduction?: NO. Do not manipulate. It risks blood supply.

2. Prophylactic Pinning

• Indication: The "other" hip.
• Controversy: Many surgeons pin the contralateral hip if specific risk criteria are met (Young age, Endocrine, Open Triradiate Cartilage), as the risk of a second slip is high.

3. Corrective Osteotomy (Late)

• Indication: Severe deformity causing impingement.
• Timing: Done after the physis has fused and the slip is healed.
• Type: Subtrochanteric or Dunns Osteotomy (High risk).

The Loder Classification (1993)

• Established the distinction between Stable and Unstable slips purely on weight-bearing status. This correlates directly with AVN risk (0% vs 47%).

Prophylactic Pinning Debate

• Current trend favours pinning the other side if the Posterior Sloping Angle (PSA) >12 degrees or the patient is young (<10y boys, <12y girls).

What is a Slipped Epiphysis?

The top of the thigh bone (femur) has a growth plate made of cartilage. In teenagers, this plate is weak. Due to weight/growth, the ball of the hip "slips" off the neck, like a scoop of ice cream sliding off a cone.

Why the Knee Pain?

The nerves that supply the hip also supply the knee. Your brain gets confused and thinks the pain is coming from the knee, even though the knee is fine.

The Surgery

We need to put a screw across the growth plate to "weld" it shut. This stops the ball slipping any further. We usually pin it exactly where it is, rather than trying to force it back, because forcing it back can snap the blood vessels.

Will I need a Hip Replacement?

Hopefully not. If we catch it early and pin it, the hip usually works well for decades. If the slip is severe or the blood supply is damaged, arthritis may develop early.

Q1: What is Trethowan's Sign? A: On an AP pelvis X-ray, a line drawn along the superior border of the femoral neck (Klein's Line) should intersect the epiphysis (femoral head). If the line stays superior to the head (i.e., the head has slipped inferiorly), the sign is positive for SUFE.

Q2: Why do we not reduce a stable SUFE? A: Forced reduction stretches the posterior retinacular vessels, which are already under tension due to the slip. Manipulation dramatically increases the risk of kinking/tearing these vessels, leading to Avascular Necrosis (AVN).

Q3: What endocrine conditions are associated with SUFE? A: Hypothyroidism (most common), Growth Hormone Deficiency (during treatment), Renal Osteodystrophy, and Panhypopituitarism. Suspect these if the patient is atypically young (<10) or thin.

(End of Topic)