Page 32 - Slipped Capital Femoral Epiphysis Pathogenetic and Clinical aspects

Chapter 2
Other authors recite 20% of development of AVN in all acute, unstable SCFE [69, 96, 110, 161]. Currently, it is not yet known which treatment can lower this rate. Immediate reduction, capsulotomy and decrease of the intracapsular pressure or an open reduction and fixation modified Dunn procedure have all been described for reducing the rate of AVN. [23, 72, 75]. AVN in acute SCFE seems to develop significantly more often in younger patients, with a shorter duration of prodromal symptoms [118].
In unstable hips, an incidental/gentle reposition is only recommended within 24 hours after the acute slip. After this time-span the incidence of AVN is likely to rise [100, 103, 142]. The slip severity before gentle manipulation does not seem influential [118]. Parsch et al. [99] claim less AVN (4.7%) in unstable SCFE after capsulotomy, evacuation of intra-articular hematoma, controlled gentle reduction and fixation of the reduced physis by smooth K-wires. Herrera-Soto et al. [46] describes an increased intra-capsular pressure (48mmHg) in unstable hips, which is about double the pressure of the unaffected side (23mmHg). Also, gentle reduction significantly further increased the pressure (75mmHg). They claim there is a need for urgent capsulotomy in unstable SCFE, especially around the gentle reduction of this slip. Possibilities after AVN are limited. Vascularised fibular grafts after AVN in SCFE seem to improve the Harris hip score (HHS) postoperatively, but five out of 52 patients received a THP after 8 years [16]. Articulated hip distraction did not improve pain in SCFE. Definitive surgical procedures, such as total hip prosthesis or arthrodesis are not postponed after distraction, meaning that distraction does not change the outcome of the patients with SCFE [37]. Bisphosphonate therapy, to preserve femoral head sphericity and congruence, is safe to give to children but whether or not it can prevent complications due to AVN in SCFE needs further study [51].
In conclusion: avascular necrosis of the femoral head is a devastating complication of SCFE. In unstable SCFE the risk is considerably increased. Accidental reduction of the slip within 24 hours and capsulectomy after the percutaneous pinning is advised. It remains unclear whether other surgical procedures as modified Dunn or open reduction will improve the outcome.
Prognosis.
The Southwick classification is important for the long-term prognosis of SCFE. Patients with mild SCFE (<30 degrees) have good prognoses, but patients with moderate and severe SCFE have an increased risk of developing osteoarthritis later
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