Dart Thrower's Motion of the Wrist: Clinical Guide

By Joseph Sharaya, OTD, OTR/L, CHT · Certified Hand Therapist · Last reviewed April 2026

Dart Thrower's Motion is an oblique plane of wrist movement that travels from radial extension to ulnar flexion — the arc the wrist traces when throwing a dart, hammering a nail, or casting a fishing rod.

The DTM plane sits approximately 30 to 45 degrees off the sagittal plane, although individual variation is wide. Measurements in healthy adults have ranged from 28 to 57 degrees off the flexion-extension axis, depending on the task being performed (Vardakastani et al., 2018; Moritomo et al., 2014).

Two subtypes worth knowing

The 2013 IFSSH Committee report formally distinguishes between two forms of DTM (Moritomo et al., 2014):

Pure DTM

A theoretical plane in which the oblique arc intercepts the coronal and sagittal planes at neutral. In this plane, scaphoid and lunate motion approach zero, and wrist rotation occurs almost exclusively at the midcarpal joint (Moritomo et al., 2014; Crisco et al., 2005).

Functional DTM

The plane observed during real activities of daily living — hammering, pouring, pounding. It is offset approximately 36 degrees into extension from the pure DTM plane, and at this offset the scaphoid and lunate contribute around 40 to 41 percent of total wrist motion (Moritomo et al., 2014; Leventhal et al., 2010). This is the DTM most patients actually use.

Why DTM matters — proximal row protection

The landmark Crisco et al. (2005) study of 28 healthy wrists across 504 three-dimensional positions showed that scaphoid and lunate motion is significantly smaller along the DTM path than along any other direction of wrist movement. The DTM path marks the transition point where scaphoid and lunate switch between flexion and extension rotation.

This has clinical consequences. Because the proximal row moves so little during DTM, rehabilitation protocols that constrain motion to the DTM plane can allow functional wrist movement while minimizing stress on the radiocarpal joint and the scapholunate interosseous ligament (Werner et al., 2004; Moritomo et al., 2014). Early mobilization in the DTM plane has been proposed for post-surgical protocols ranging from radiocarpal fusion to distal radius fracture management.

DTM and PNF D2 · the wrist endpoint connection

For clinicians trained in Proprioceptive Neuromuscular Facilitation, the relationship between DTM and PNF D2 is worth understanding explicitly.

PNF D2 is a full upper-extremity diagonal pattern defined primarily at the shoulder. The D2 flexion pattern — often cued as combing hair or reaching overhead — terminates at the wrist with extension and radial deviation. That's the up endpoint of DTM. The D2 extension pattern — sword sheathing — terminates at the wrist with flexion and ulnar deviation. That's the down endpoint of DTM.

In other words: the wrist component of PNF D2 is DTM. The distinction is that DTM is defined at the wrist alone, while D2 integrates the kinetic chain through the shoulder, forearm, and hand.

When to use DTM in rehabilitation

Distal radius fracture

DTM is highly appropriate. Early controlled mobilization in the DTM plane has been shown feasible after surgical fixation in pilot-level evidence, and DTM is the most common functional motion pattern patients need to recover for daily activity (Kaufman-Cohen et al., 2020; Feehan & Fraser, 2016).

Lunotriquetral injury

The flexion phase of DTM recruits extensor carpi ulnaris, which provides dynamic midcarpal and DRUJ stabilization in LT-deficient wrists (León-López et al., 2013; Iida et al., 2012). DTM is generally appropriate; forearm neutral positioning is ideal.

Triangular fibrocartilage complex injury

DTM is functional and ECU activation during the flexion phase supports DRUJ stability. Assess DRUJ stability before progressing to full-range DTM, especially if combined with forearm rotation (Chen, 2018).

Scapholunate injury — the caveat

It is often repeated that DTM is SL-protective because the scaphoid and lunate barely move during the motion. That claim holds for healthy wrists. It does not hold cleanly once the scapholunate interosseous ligament is injured.

In SL-deficient wrists, the scaphoid and lunate begin to move differently from each other during DTM. Imaging studies have documented a separation — an SL gap — developing during the motion, which can stress a torn or repaired ligament (Garcia-Elias, 2014). A scoping review of the evidence concluded that caution is warranted, particularly at end-range motion where the gap tends to be largest (Bergner et al., 2020).

The safe clinical position: DTM is not unconditionally safe for SL injury. In the conservative or early post-repair setting, use caution, limit motion to mid-range arcs, avoid end-range loading, and consider a dart-thrower orthosis that blocks orthogonal planes during early rehabilitation. DTM becomes appropriate later in recovery, once the joint is stable — either naturally or after surgical stabilization — and should be introduced with physician clearance.

How to train DTM using WristSkill™

WristSkill's D1 and D2 planes correspond to the diagonal patterns that include the DTM plane at the wrist. A clinician who wants to work the DTM arc with a patient can:

1. Pick the right mode. Use Performance Mode when you want all three metrics — Targets Hit, Time to Target, and Path Efficiency — captured and saved. Use Free Play when you only need targets-hit tracking during an open practice session.
2. Select the appropriate hand. The mapping of D1 and D2 to specific wrist motions differs between right and left — the app handles this once the hand is selected.
3. Position the patient. A forearm position around 45 degrees of pronation approximates the functional DTM plane (Leventhal et al., 2010), but the exact angle varies by task and patient. The guiding principle is that the screen must remain visible to the patient throughout the trial — adjust posture, forearm support, or phone grip as needed to keep the screen in view.
4. Focus the session. Run the D1 or D2 diagonal plane based on the clinical goal. The D2 plane is the closer approximation of DTM at the wrist.
5. Track change. Compare session-over-session performance against the patient's own baseline.