Nasal capsule shape changes following septopremaxillary ligament resection in a chimpanzee animal model.

Recent human data suggest a relationship between the disruption of the septopremaxillary ligament (SPL) attachment and lack of anterior midfacial growth in cleft lip and palate (CLP) individuals. Early SPL resection in chimpanzees resulted in premaxillary growth deficits through 1200 days. Since the SPL is also continuous with the nasal bones, the present study was undertaken to investigate compensatory nasal capsule shape changes following SPL resection in a chimpanzee animal model. The study used 17 chimpanzees (Pan troglodytes): seven unoperated controls, five sham surgical controls, and five animals with early (average 144 days) SPL resection. Lateral head x-ray films and dental study models were collected quarterly and landmarks representing boundaries of the nasal capsule were identified. Mean nasal capsule polyhedrons were constructed from linear measurements at 200, 600, and 1000 days. In animals with SPL resection, the nasal capsule appeared truncated, shortened anteroposteriorly, and nasion was displaced posteriorly compared to controls by 600 days. Tensor biometric analysis of the growth/shape changes of the nasal capsule triangles revealed no significant differences across age in SPL resection animals while significant (p less than .05) age-related changes were noted in both control groups. Results showed that early SPL resection resulted in maintaining the neonatal nasal capsule morphology in the chimpanzee and suggested that such early growth mechanisms may be operating in complete CLP individuals as well. These data support the concept of early re-establishment of the SPL in primary nasolabial cleft repair to facilitate midfacial and nasal capsule growth.