SINGLE-EVENT VERSUS STAGED OPEN REDUCTION IN BILATERAL DEVELOPMENTAL DYSPLASIA OF THE HIP: DOES RATE OF EARLY DISLOCATION VARY?

There are currently no guidelines on surgical timing for bilateral developmental dysplasia of the hip (DDH) pathologies. The decision to perform single-event or staged open reduction (OR) is often dictated by surgeon or centre preference. Consequently, the influence of staged OR on treatment outcomes is poorly understood. This study aimed to investigate early re-dislocation rates following single-event and staged bilateral ORs in a prospective cohort of patients with DDH. A global multi-center, prospective database of patients diagnosed with DDH was queried for patients who underwent bilateral OR. Patients with syndromic-associated hip dislocations/dysplasia were excluded. Included patients were divided into two groups depending on whether both hips underwent OR in a single event (Group 1), or as a staged procedure (Group 2). Patient demographics, risk factors, and diagnostic details were assessed pre-operatively. Post-operative outcomes included reduction status (IHDI grade) and re-dislocation rate in the early-mid post-operative period. The presence of avascular necrosis (AVN), residual dysplasia, and re-operation rate will be examined in longer-term analyses. In total, 72 patients (144 hips) identified from 12 centres globally underwent bilateral OR: 42 patients (84 hips) in Group 1 (single event) and 30 patients (60 hips) in Group 2 (staged). The study population included 55 females, 20 breech born and nine with positive family history. Patients were diagnosed at an average of 26.9 months (95% CI [21.4, 32.4]). Group 2 was significantly older at time of first surgery than Group 1 (42.1 months vs. 20,3 months). In Group 2, ORs were staged a median of 49 days apart (range 14-362). Group 2 hips more often underwent concomitant acetabular osteotomy and/or femoral osteotomy (80% compared to 25%); only 6/30 patients (12/60 hips) did not undergo an additional procedure. On the other hand, 31/42 patients did not undergo any additional procedure in Group 1. Reduction status and re-dislocation rate was evaluated at a mean follow-up of 6.8 months [6.4,7.2] postoperatively to capture early re-dislocations. Loss of reduction was seen in 23 hips (in 16 patients) total: 18 hips (12 patients) in Group 1 and five hips (four patients) in Group 2 (p=0.034). In Group 2, the interval between the two surgeries in 2/4 who underwent staged OR was less than eight weeks. Of the 23 hips that had a loss of reduction, 21 (91%) were IHDI Grade 2. In this cohort, loss of reduction occurred more frequently after single-event bilateral OR; however, complete re-dislocation (IHDI Grade 4) occurred in only two hips. Longer follow-up will be required to examine reduction status, rates of AVN and re-operation. The staged group was significantly older at time of diagnosis and first surgery, and more frequently underwent concomitant femoral/pelvic osteotomy, suggesting the influence of surgical decision-making on the decision to stage or perform single-event. A larger sample size and long-term follow-up will be required to formulate a management protocol to instill best treatment practices in order to optimize patient outcomes.