Rationale

Recent studies have reported the importance of hip capsular decompression with gentle repositioning/inadvertent reduction and/or open reduction; however, the ideal treatment to reduce the risk of osteonecrosis after unstable SCFE remains controversial.

Clinical comment

Osteonecrosis of the femoral head is the most common complication associated with unstable SCFE. The outcomes of unstable SCFE are severely compromised by the occurrence of osteonecrosis as there is no definitive treatment for osteonecrosis and typically the hip will deteriorate to osteoarthritis. Osteonecrosis is the most common reasons why patients with a history of SCFE undergo a total hip arthroplasty (THA) in adult life.

Available literature and quality of the evidence

• Level III: 5 therapeutic studies.¹–⁵
  
• Level IV: 3 therapeutic studies.⁶–⁸

Findings

SCFE is defined as unstable if the child has such severe pain that walking is not possible even with crutches, regardless of the duration of the symptoms.⁵ Osteonecrosis of the femoral head is the most feared complication following treatment of unstable SCFE. According to Loder et al. 47% of unstable SCFEs treated with fixation following reduction developed osteonecrosis of the femoral head.⁵ Since Loder and colleagues proposed their classification, there has been persistent controversy about the ideal management of unstable SCFE.⁵ Given that closed reduction with subsequent fixation results in a high proportion of osteonecrosis, several studies of open reduction have been reported.

Ziebarth et al. reported the results of the modified Dunn procedure for patients with moderate and severe SCFE.⁷ In their series, no patients developed osteonecrosis of the femoral head. However, only four patients were found to have unstable SCFE. However, a multicenter North American series reported a 26% prevalence (seven out of 27 hips) of osteonecrosis after the modified Dunn procedure for unstable SCFE. Parsch et al. reported on 64 consecutive cases of unstable SCFE using a Watson‐Jones approach to expose the hip joint and to perform a capsulotomy that allows for the surgeon to place the fingertip in the gap between the metaphysis and the epiphysis while gentle traction is achieved.⁶ They reported 4.7% (three out of 64 hips) occurrence of osteonecrosis.

There are very few comparative studies in the literature. In a small series, Alves et al. compared six patients treated with closed reduction and percutaneous fixation versus six patients treated with open reduction using the modified Dunn procedure.¹ They noted osteonecrosis in four (66.7 %) patients after a modified Dunn procedure, while two (33.3 %) patients had osteonecrosis after closed reduction. Similarly, in a small series, Souder et al. reported that three of seven hips stabilized with a percutaneous screw developed osteonecrosis (43%) compared to two of the seven unstable SCFE treated by the modified Dunn procedure developed avascular necrosis (AVN) (29%).⁴

Two larger comparative studies have also been reported. Walton et al. compared 16 hips that underwent intracapsular cuneiform osteotomy and 30 that underwent fixation after varying degrees of serendipitous reduction.³ Osteonecrosis developed in four hips (25%) following osteotomy and in 11 (42%) following fixation after serendipitous reduction. The proportion of osteonecrosis was significantly higher following fixation with complete reduction than that following intracapsular osteotomy. Novais et al. evaluated 45 patients with unstable SCFE treated using the modified Dunn procedure (n = 27) or percutaneous pinning after inadvertent reduction (n = 18). Of the 27 patients treated by a modified Dunn procedure, seven (26%) developed osteonecrosis compared to 28% (5/18) patients treated by percutaneous pinning (p >0.999).²

Resolution of clinical scenario

In the treatment of unstable SCFE, there is low‐quality evidence suggesting that open reduction using the modified Dunn yields better clinical and radiographic results but does not reduce the proportion of osteonecrosis when compared to in situ pinning after inadvertent reduction. Open reduction through an anterolateral approach seems to be a promising technique, but further comparative studies are required.

Rationale

The uninvolved contralateral hip in patients presenting with unilateral SCFE is at risk of slip. Prophylactic fixation would avoid a subsequent slip; however, it is controversial whether the risk outweighs the benefits.

Clinical comment

SCFE presents with unilateral involvement in 77–91% of patients.⁹–¹¹ However, between 18 and 41% of patients will develop a contralateral slip,¹⁰–¹⁵ typically during the first 18 months after the initial diagnosis.¹¹

Available literature and quality of the evidence

• Level III: 2 therapeutic studies.¹⁶,¹⁷
  
• Level IV: 1 case report¹⁸ and 3 therapeutic studies.¹⁹–²¹

Findings

Bhattacharjee et al. compared 44 patients who underwent prophylactic fixation to 36 patients managed by observation and observed a higher incidence of sequential SCFE of initially unaffected hips in the observation group compared to those with prophylactic fixation without any cases of osteonecrosis or chondrolysis.¹⁶

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