CHAPTER 43: FUNCTIONAL DEXTERITY TEST (FDT)

Description

The Functional Dexterity Test (FDT; 1983) is designed to purvey information regarding a person’s ability to use the hand for functional tasks requiring the use of gross prehension patterns (Aaron & Stegink-Jansen, 2003). During assessment the subject is required to turn over pegs from a pegboard starting from the opposite corner of the hand being tested in a zigzag fashion until all rows are overturned. The pegboard is a square wooden board that contains places for 16 pegs that are larger than typical pegboard assessments (i.e., 2.2 cm in diameter and 4 cm long), thus large enough for the client to exhibit the need for gross motor grasp such as three jaw chuck prehension between the fingers and thumb. The board’s dimensions are roughly 20 cm x 20 cm and 4 cm deep and contains rows, 4 × 4 to accommodate the 16 pegs. While administering the test the clinician examines for unusual movements and the subject is scored according to the time it takes to turn over all pegs. Various time infractions can be incurred such as when a peg is dropped or if the person completely supinates their hand. Two scores are possible (1) total time and (2) total time plus penalties. Higher scores (in seconds) indicate more impairment and a score over 55 seconds is considered non-functional. The FDT can be completed in less than 5 minutes.

Psychometrics

Using 3 raters, Aaron and Stegink-Jansen (2003) found that for score 1 (total time) inter-rater reliability was excellent (r= 0.99); however, for score 2, which takes into account penalties, intra-class correlation coefficients were lower for the uninjured hand at r = 0.88 and for the injured hand it was 0.73. The same developmental study established validity by comparing FDT scores with the ability to complete four functional activities of daily living (buttoning a button, tying shoe laces, screwing a nut and bolt, and lacing yarn) with the injured hand where subjects were considered functional for those activities where for FDT scores between 16 and 25 seconds they were considered functional; scores between 26 to 33 seconds they were considered moderately functional; and at 34 to 50 seconds they were considered minimally functional. A subsequent study by Sartorio et al. (2013) of 324 healthy volunteers displayed excellent test-retest reliabilities of the FDT with values higher than r = 0.90.

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