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A 10-year-old girl with intermittent left hip pain
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A 10-year-old girl presented with a 2-week history of intermittent left hip pain, which became acutely worse on the morning of presentation. While she had been mobilizing with crutches for the 2 weeks prior to evaluation, on presentation, she was unable to mobilize with or without the use of crutches.
The patient’s left lower extremity was resting in an externally rotated position. On exam, she had pain with logroll. She was neurovascularly intact distally. Given her level of discomfort, further range of motion examination was deferred. The contralateral lower extremity had a full, pain-free range of motion without obligate external rotation. AP and frog-lateral views of the pelvis were obtained (Figure 1).
Supine anteroposterior plain radiograph of the pelvis demonstrates left slipped capital femoral epiphysis (SCFE). Note that Klein’s line of the left hip does not intersect the femoral head (a). On the frog-leg lateral radiograph, Southwick angle of the left hip is about 55° (b).
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Slipped capital femoral epiphysis
The patient presented with an unstable slipped capital femoral epiphysis (SCFE). Her slip was classified as acute, severe and unstable. For most surgeons, the treatment of choice at the time of presentation remains in-situ screw stabilization. However, recent technical advances in the management of moderate to severe slips have allowed treatment of potential pathologic deformity during initial surgical management.
Background and clinical outcomes
SCFE is one of the most common hip disorders affecting adolescents, with an incidence upwards of 10 in 100,000. The incidence is increasing, which is thought to be due to the overall trend toward obesity in adolescents. The epiphysiolysis and subsequent displacement of the proximal femoral epiphysis relative to the metaphysis results in a 3-D deformity — varus, extension and external rotation. Even with relatively minimal displacement, the ensuing deformity has been shown to result in a high rate of pistol-grip deformity and an increased risk for osteoarthritis (OA). There is a linear relationship between degree of deformity and subsequent degenerative changes.
There is a growing body of literature demonstrating the association between SCFE, osteochondral damage and associated arthritic changes. The deformity associated with uncorrected SCFE leads to an anterior metaphyseal prominence, which effectively decreases head-neck offset, causing direct mechanical abutment of the femoral neck against the acetabular rim with hip flexion — a phenomenon called femoroacetabular impingement (FAI). This leads to labral damage, eventual loss of peripheral articular cartilage and OA. This has been demonstrated in cadaveric retrieval studies and in clinical and radiographic long-term follow-up studies.
Intraoperative fluoroscopy showing fixation of the femoral head after reduction of the head onto the femoral neck. Fixation was provisionally held with two threaded K-wires. After reduction of the hip, the more central K wire was replaced with a 7.3-mm cannulated screw (a). Anteroposterior (b) and lateral (c) of the left hip after fixation of the greater trochanter in a more distalized position.
Treatment options
The goals of surgical management for all SCFEs are prevention of further slip, prevention of avascular necrosis (AVN), correction of the deformity to prevent secondary impingement and ongoing assessment of the contralateral hip to prevent bilateral involvement. Most North American surgeons agree there is a benefit to surgical intervention within 24 hours of presentation of an unstable SCFE to theoretically decrease vascular compromise to the femoral head. The same is not necessarily true for patients who present with stable SCFE.
The preferred initial treatment of North American surgeons for both stable and unstable SCFE is in-situ screw fixation with a single transphyseal screw. This screw decreases the risk of further slip propagation and is a reasonable option even in unstable, severe slips. Historical reports of acute deformity correction had unacceptably high rates of associated AVN. Screw stabilization more reliably achieves the first two goals of management. However, in order to achieve prevention of deformity one must consider alternative surgical approaches.
Three-phase bone scan obtained on postoperative day 3 reveals diminished but adequate blood flow to the left hip.
As compared to historical data, modern approaches to deformity correction are associated with an improved safety profile and lower rates of resultant AVN. As such, more surgeons are adopting more nuanced surgical approaches to SCFE management. For minor deformity, in-situ stabilization combined with osteochondroplasty to achieve impingement-free range of motion is an option. For moderate to severe slips with limited impingement-free range of motion, both proximal femoral osteotomy and surgical dislocation with modified Dunn osteotomies are suitable surgical options, if performed by surgeons with appropriate expertise. If the treating surgeon is not familiar with these techniques, the most appropriate management remains initial in-situ fixation with referral for possible deformity correction in a staged fashion.
Management of our patient
This slip was classified as an acute, severe, unstable SCFE. The family opted for surgical dislocation and modified Dunn osteotomy with staged contralateral prophylactic pinning. Specific risks discussed included AVN, hardware failure, nonunion, chondrolysis, dislocation and infection.
Postoperative radiograph 3 months after the two-stage procedure for left SCFE and right-sided prophylactic pinning. The first stage consisted of a surgical hip dislocation of the left hip with a modified-Dunn procedure to correct the deformity. The second stage consisted of right hip in-situ fixation.
The patient was placed in the lateral-decubitus position. A laterally-based incision was made centered over the greater trochanter. A trochanteric osteotomy was performed, creating a 12-mm to 13-mm thick trochanteric fragment, containing the medius insertion and the origin of the vastus lateralis. The osteotomized fragment was moved anteriorly, exposure of the anterior capsule was completed, and a Z-type capsulotomy was performed. Just prior to dislocation, a threaded k-wire was placed across the femoral neck and into the epiphysis to protect the retinacular vessels from excessive stretch during dislocation. The head was then dislocated anteriorly. The posterior-superior aspect of the remaining trochanter was excised to allow improved access to the posterior femoral neck. Extremely cautious subperiosteal dissection to separate the neck from the adherent anterior and posterior periosteum resulted in an extended retinacular flap. At this point, the k-wire that had been previously placed was removed, and the epiphysis was carefully mobilized from the metaphysis. Limited femoral neck shortening allowed for tension-free repositioning. Physeal cartilage was excised, and the femoral head was reduced on the neck. A 2-mm drill hole was created to assess epiphyseal perfusion, which demonstrated brisk bleeding from the head. The reduction was held in place with two threaded K-wires. One of these was ultimately replaced with a cannulated 7.3-mm screw. The hip was reduced, and perfusion of the femoral head was rechecked, again exhibiting brisk osseous bleeding. The periosteal sleeve and capsule were loosely approximated. The greater trochanter was reattached with two 3.5-mm cortical screws in a distalized/lateralized position to optimize hip stability and abductor function (Figure 2). The fascia and skin were closed. The patient was placed into a hip abduction wedge.
On postoperative day 3, a three-phase bone scan was obtained to assess arterial flow to the femoral head, revealing diminished but adequate flow (Figure 3). Inadequate flow on bone scan is indicative of occlusion of the retinacular vessels from kinking or stretching after reduction, which would warrant re-exploration of the operative hip. No further surgical intervention was deemed necessary for the affected side in this patient. However, the contralateral hip was pinned prophylactically that day, as planned. While contralateral prophylactic fixation is not required in all cases, it should be considered in younger patients and in those who have endocrine or metabolic diseases/abnormalities. In patients who do not require prophylactic pinning, the family should be instructed to return immediately for any contralateral hip, knee, thigh or groin pain.
Our patient was made toe-touch weight-bearing with hip precautions until radiographic evidence of healing of the greater trochanteric osteotomy was present (at 6 weeks). Thereafter, she was advanced to full weight-bearing, and her range of motion, strength and stability were regained. At 3-month follow-up the patient was clinically doing well (Figure 4). At last follow-up (6 months), the patient had a full, pain-free range of motion with a mild Trendelenberg gait.
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For more information:
Rachel E. Mednick, MD; Eric B. Fuller, MD; and Vineeta T. Swaroop, MD, can be reached at Northwestern Memorial Hospital, 251 E. Huron St., Chicago, IL 60611; Prasad Gourineni, MD, can be reached at Advocate Christ /Hope Hospitals, 3420 Adams Rd., Oak Brook, IL 60523; Mednick’s email: rachel-mednick@northwestern.edu; Fuller’s email: eric-fuller@northwestern.edu; Gourineni’s email: pgourineni@gmail.com; Swaroop’s email: vswaroop@ric.org.
Disclosures: Mednick, Fuller, Gourineni and Swaroop have no relevant financial disclosures.