(7) Failure Rates Based on Alveolar Cleft Size: An Analysis of the Critical Size Defect for rhBMP-2/DBM and ICGB in Alveolar Cleft Repair

Thursday, September 15, 2022

1:30 PM – 3:00 PM CDT

Figure 1. rhBMP-2/DBM Failure Rate Based on Preoperative Volumetric Defects

Figure 2. ICBG Failure Rate Based on Preoperative Volumetric Defects

Figure 3. Statistical Analysis of Bony Bridge Formation, Bergland Score, and Bridge Thickness for ICBG and rhBMP-2/DBM

Presenting Author(s)

Simon Youn, DDS

Resident
University of Southern California
San Gabriel, California, United States

Co-Author(s)

Katelyn Kondra, MD

Resident
Keck Medicine of USC
Los Angeles, California, United States
Christian Jimenez, BS

Medical Student
Keck School of Medicine of USC
Los Angeles, California, United States
Eloise Stanton, BA

Medical Student
Keck School of Medicine of USC
LOS ANGELES, California, United States
KC

Kevin Chen, MD

Fellow
Children's Hospital Los Angeles
Los Angeles, California, United States
JH

Jeffrey Hammoudeh, MD, DDS

Attending Physician
Children's Hospital Los Angeles
Los Angeles, California, United States

Disclosure(s):

Simon Youn, DDS: No financial relationships to disclose

Katelyn Kondra, MD: No financial relationships to disclose

Christian Jimenez, BS: I do not have any relevant financial / non-financial relationships with any proprietary interests.

Eloise Stanton, BA: No financial relationships to disclose

Kevin Chen, MD: I do not have any relevant financial / non-financial relationships with any proprietary interests.

Jeffrey Hammoudeh, MD, DDS: I do not have any relevant financial / non-financial relationships with any proprietary interests.

Abstract: Alveolar cleft repair (ACR) using iliac crest bone graft (ICBG) is the standard of care at many institutions for children with complete cleft lip and palate at mixed dentition. Harvesting bone may result in donor site morbidity, protracted operations, and longer hospitalizations. With the advent of recombinant human bone morphogenetic protein (rhBMP-2) and demineralized bone matrix (DBM), the inherent drawbacks of using ICBG during ACR can be avoided. Recent studies demonstrate that rhBMP-2 with DBM (rhBMP-2/DBM) has equal graft success versus ICBG without incurring serious adverse events.1 Other studies report superior radiographic outcomes and significantly greater coronal bridging with rhBMP-2/DBM versus ICBG.2 However, a critical size defect for graft failure has yet to be established. We aim to determine the critical size defect by analyzing failure rates for ICBG and rhBMP-2/DBM to provide a guideline for surgeons for ACR.

An IRB-approved retrospective review evaluated patients undergoing ACR between December 2016 and September 2021 at Children's Hospital Los Angeles. Patients with 1) unilateral complete alveolar clefts secondary to incomplete or complete unilateral cleft palate, 2) who underwent rhBMP-2/DBM or ICBG, 3) and obtained preoperative and postoperative cone beam computed tomography (CBCT) scans were included. Syndromic patients, those with bilateral clefts, or those not operated on by our Plastic & Maxillofacial Surgeons were excluded. Our protocol employs an extra-small sponge of rhBMP-2 layered with DBM packed into the alveolar cleft. The protocol for ICBG utilizes a trephine for harvest of compressed bone. The 3-dimensional volumetric defect sizes were calculated as a trapezoidal pyramid using preoperative CBCT scans. Bergland scale score, bony bridge formation (BBF), and bony bridge thickness were calculated using postoperative scans. Success versus failure was defined by BBF with the goal of restoration of the edentulous space. Statistical analyses were performed using IBM SPSS Statistics software with statistical significance for calculations defined as α=0.05.

Of 140 patients, 61 met inclusion criteria and underwent ICBG (n=28) or rhBMP-2/DBM (n=33). Failure rates (FR) were analyzed against preoperative volumetric defects (Figures 1 and 2) and were identified at 25% (FR25), 50% (FR50), 75% (FR75), and 100% (FR100) using an exponential trendline of best fit. RhBMP-2/DBM demonstrated FR25: 584.26mm3, FR50: 876.73mm3, FR75: 1047.81mm3, FR100: 1169.19mm3. ICBG demonstrated FR25: 621.17mm3, FR50: 918.66mm3, FR75: 1092.67mm3, FR100: 1216.14mm3. We evaluated for significance surrounding the median defect volumes (Figure 3). There was significantly more bony bridge formation in the ICBG cohort in clefts < 811.68 mm3 versus >811.68 mm3 (p < 0.001). Similarly, there was significantly more bony bridge formation in the rhBMP-2/DBM cohort in clefts < 810.98 mm3 versus >810.98 mm3 (p < 0.02). Notably, there was no significant difference in FR at the median values between ICBG and rhBMP-2 patients.

We identified FR based on cleft defects across ICBG and rhBMP-2/DBM. Additionally, we demonstrated significantly more graft failures at defects greater than the median value of each cohort; notably, there was no significance across cohorts of FR at the median cleft volumes. We hope these results will guide providers in graft selection when treating various cleft sizes. However, future work should strive to identify the ideal material for larger defects and assess whether a hybrid of materials or higher dose of rhBMP-2 is required for these patients.

References
1. Hammoudeh JA, Fahradyan A, Gould DJ, et al. Comparative Analysis of Recombinant Human Bone Morphogenetic Protein-2 with a DBM versus ICBG for Secondary Alveolar Bone Grafts in Patients with Cleft Lip and Palate: Review of 501 Cases. Plast Reconstr Surg. 2017;140(2):318e-325e.
2. Francis CS, Mobin SSN, Lypka MA, et al. rhBMP-2 with a demineralized bone matrix scaffold versus autologous ICBG for alveolar cleft reconstruction. Plast Reconstr Surg. 2013;131(5):1107-1115.