The present invention provides a support element for implantation into or between a subject's bones, characterized in that: the support element is a hollow nestable structure having expandable elasticity, and can be in a contracted configuration or a distended configuration. The present invention also provides an implant component, comprising: the support element; and a limiting member to prevent the support element from expanding and thereby keep the support element in the contracted configuration. The present invention also provides an implant system applicable to a subject's spine, the implant system comprising: the support element as a first support element; and optionally one or a plurality of the support elements in the hollow nestable structure of the first support element. The support element can be nested until the support provided by the entire implant system reaches the desired level.