Abstract 148: Natural Trajectory of Midface Growth in Unoperated Cleft Defects: A Systematic Review and Meta-analysis

Purpose: Orofacial cleft deformities are prevalent congenital defects which can affect approximately 7.75 neonates out of every 10,000 live births in the United States. After surgical repair of the orofacial cleft, high rates of midface hypoplasia requiring orthognathic repair has been reported in the literature. The etiology of this midface hypoplasia is incompletely understood. Popular belief suggests that either an intrinsic growth retardation of the maxilla or scar tissue formation and disruption of the natural growth plates caused by surgical repair is responsible for the increased rates of midface hypoplasia. In various countries with less access to surgical care, older patients with unoperated clefts have been examined to gauge the underlying growth potential of the maxilla untouched by surgical intervention. However, as a result of small patient populations in each individual study, limited conclusions can be drawn. We, therefore, perform a meta-analysis of studies examining maxillary cephalometric measurements in unoperated cleft patients to gain a more complete understanding of the cleft palate’s underlying growth potential. Methods: A systematic literature review and meta-analysis was performed according to PRISMA guidelines in the PubMed database. Studies were included for their focus on cephalometric measurements in unoperated and operated cleft patients, or maxillary growth mechanics in cleft deformity patients. Means and standard deviations of SNA, SNB, and ANB angles were collected from patients who possessed unoperated unilateral cleft lip and palate (UCLP), bilateral cleft lip and palate (BCLP), and isolated cleft palate groups (ICP). Age-matched control groups were abstracted from the papers and compiled for comparisons against the cleft groups. Statistical analysis was run with independent parametric t-tests. Results: A total of 155 peer reviewed articles in the appropriate patient population were included in the study. From these, 10 and 28 articles included the appropriate cephalometric measurements in unoperated patients and operated cleft patients, respectively. SNA angles of the UCLP and BCLP groups demonstrated significant increases from the control group and operated groups (84.5 ± 4.0° vs. 82.3 ± 3.5° and 76.2 ± 4.2°, p≤0.001) and (85.8 ± 2.8° vs. 82.3 ± 3.5° and 80.9 ± 3.8° p≤0.001), respectively. Unoperated ICP demonstrated a decrease in SNA angle vs. the control group (79.2 ± 4.2° vs. 82.3 ± 3.5° p≤0.001) and no change when compared to the operated group (79.2 ± 4.2° vs. 79.0 ± 4.3° p=0.78). Conclusion: In patients with unoperated cleft deformities, the maxilla does not exhibit the degree of midface hypoplasia typically seen after operative repair. This suggests that midface hypoplasia could be attributable to extrinsic factors. More studies are required to delineate the contributing factors to midface hypoplasia typically seen after operative repair.