Basically, the idea is to use the pectoral muscle to cover the upper portion of the implant, where it is most important. The difference between this and the dual-plane subpectoral method is that the split muscle technique preserves the normal attachments and function of the muscle by leaving the lower portion behind the implant. The reason for this is that the dual-plane method detaches the muscle from its attachment to the rib cage and this free edge of muscle then heals onto the scar capsule in front of the implant. When the muscle is contracted, it pulls on the capsule, causing animation deformity and often double bubble.