T-GAP Assessment

The thumb grasp and pinch assessment (T-GAP) is a participation measure developed to rate the hands ability to formulate grasp and pinch during nine object manipulation routines. The T-GAP provides a new perspective that grades hand dexterity based on the skill level of grasp and stabilization rather than measuring timed speed, which is the focus of most dexterity assessments. The T-GAP was standardized in 2018 for construct and concurrent validity as well as inter and intra rater reliability.

The T-GAP was developed to understand how the hand formulates grasp in children with congenital thumb hypoplasia with absent or weak thumb musculature. The T-GAP includes nine tasks based on developmental stages of hand function for three different age groups: 18 months to 4 years, 5 to 7 years and 8 to 18 years. The tasks were selected using activity analysis for nine specific object manipulation routines to elicit large grasp, medium grasp, small grasp, lateral pinch, tip pinch, tripod pinch, manipulation, resistance, school and ADLs. The tasks are video recorded during a 5-10-minute semi structured play session and scored during a subsequent viewing. Experienced raters can score the T-GAP during the assessment.

Each of the nine tasks are scored using an eight-point hierarchical scale ranging from the most primitive grasp styles which do not include the thumb (0-3 points) to more sophisticated patterns that engage the thumb in distal patterns of radial digital opposition (4-7 points). Scoring involves the use of grasp style photo examples, written descriptions and variant patterns which occur less frequently. The T-GAP total score is calculated as the sum of all 9 tasks and has a theoretical range of 0-63 with a higher score indicating a higher thumb opposition skill level. In addition, the T-GAP measures whether the hand is able to formulate a variety of grasp styles and the frequency of thumb use during specific grasp and pinch tasks.

Wendy Tomhave, OTR/L, is the primary developer of the Thumb Grasp and Pinch Assessment (T-GAP). Learn more about Wendy.

View or download the T-Gap Assessment Materials.