What is the GMFM?
• The Gross Motor Function Measure (GMFM) is a clinical measure designed and validated
to evaluate changes in the gross motor function in children with cerebral palsy (CP).
• There are two versions of the GMFM: the original 88-item measure (GMFM-88) and
the 66-item measure (GMFM-66). These items are administered in the same way—the
difference between the two versions simply concerns which of the items (from the full
pool of 88 possible items) are included in GMFM-66.
• There are three methods of administering the GMFM to obtain a GMFM-66 score. All
three methods require the Gross Motor Ability Estimator (GMAE-2) scoring software to
convert the item data into a GMFM-66 score. Administration methods include the following:
(1) GMFM-66: administer all 66 items; (2) GMFM-66-Item Sets (GMFM-66-IS): use
a scoring algorithm to identify a subset of items to administer; and (3) GMFM-66 Basal &
Ceiling (GMFM-66-B&C): use a basal/ceiling approach to identify a subset of items.
Items on the GMFM-88 span aspects of what the World Health Organization’s International
Classification of Functioning, Disability and Health refers to as gross motor
‘activity’, ranging from activities such as lying and rolling to walking, running and
jumping skills. The GMFM-66 consists of a subset of the 88 items that has been shown to be unidimensional.