The case for WristSkill™.

By Joseph Sharaya, OTD, OTR/L, CHT · Certified Hand Therapist · Updated September 2026

Wrist proprioception — the body's sense of joint position and movement — has emerged as a distinct field within hand therapy over the past decade. Published literature has expanded substantially, but clinical tools for measurement in everyday practice have not kept pace.

WristSkill was developed by a practicing hand therapist to provide a reliable clinical tool for measuring wrist performance at the bedside. The aim was simple: take the body of research on wrist proprioception and put a small piece of it into the hands of working clinicians.

The app began as a response to a gap in clinic. Continuing education sessions kept recommending gamified proprioception apps, but when I went to download them, many had been pulled from the store or carried ads incompatible with a clinical context. WristSkill is what I built instead — a clean, ad-free, clinically grounded tool I could confidently put in front of a patient.

Why wrist proprioception matters

It's functionally important.

Proprioception is the integrated sense of where a joint is in space and how it is moving. At the wrist, intact proprioception contributes to dynamic joint stability, accurate motor planning, and the fine adjustments that make hand use feel automatic. When proprioception is impaired — after a distal radius fracture, ligament injury, or surgical repair — pain and periods of immobilization often lead to a sense of “disconnection” (Hagert & Rein, 2024).

It's measurable.

A wrist position sense test in which patients match imposed wrist positions has shown high test-retest reliability (r = .88 and .92) in adults after stroke, and a change of 8 degrees can be interpreted, with 95% confidence, as genuine (Carey et al., 1996). In older women 8 weeks after distal radius fracture treatment, JPS error and grip force showed the largest group differences and the highest correlations with functional disability scores — as measured by the Patient-Rated Wrist Evaluation, or PRWE — of the sensorimotor measures tested (Karagiannopoulos et al., 2013). The active JPS test is also highly responsive to change, with effect sizes of 1.53 at 8 weeks and 2.36 at 12 weeks after treatment (Karagiannopoulos et al., 2016).

Healthy error is a few degrees.

Healthy young adults demonstrate mean absolute JPS error between 3.3 and 4.6 degrees at 20-degree flexion and extension targets (Shetty et al., 2024). On the stroke-rehabilitation test described above, healthy adults' average error ranged from 3.1 to 10.9 degrees, and impairment was conservatively defined as 11 degrees of average error (Carey et al., 1996). That criterion was set for stroke patients; after distal radius fracture, change on the active JPS test needs to exceed its minimum detectable change, 4.28 degrees at 8 weeks and 4.94 degrees at 12 weeks, to count as real (Karagiannopoulos et al., 2016). Acuity is not uniform across planes: robotic workspace mapping shows radial and ulnar deviation to be the most proprioceptively acute direction (3.68° ± 0.32°), compared with flexion and extension (4.64° ± 0.24°) and pronation and supination (5.15° ± 0.37°) (Marini et al., 2016).

The measurement gap

Despite the quality of this evidence, we found no FDA-cleared device for routine clinical wrist proprioception assessment with validated psychometric properties. Research-grade tools — robotic exoskeletons, psychophysical threshold testing rigs — remain inaccessible to the hand therapy clinic. Goniometer-based JPS testing is available in the clinic, but its reliability varies with the wrist angle tested and the tester's experience (Karagiannopoulos, 2024).

What WristSkill measures

WristSkill quantifies three performance metrics during brief, standardized, tilt-based targeting trials in six movement planes:

Targets hit

The output of successful motor planning and execution against a spatial goal.

Time to target

The temporal component of motor performance.

Path efficiency

The accuracy component, reflecting corrections, overshoot, and wandering during movement.

These metrics reflect kinesthesia, visuomotor integration, and conscious motor control during active wrist movement against gravity. They complement — rather than replace — validated static joint position sense testing. A clinician who uses WristSkill alongside JPS goniometry or a standardized outcome measure like the PRWE builds a more complete picture of sensorimotor recovery than either tool alone provides. See the functional goals reference for examples of how the three metrics can anchor SMART goals in clinical documentation.

Why six planes

The six-plane structure is intentional and informed by the literature. WristSkill maps it onto the four-stage wrist rehabilitation protocol proposed by Hagert and Rein (2024); the mapping is WristSkill's, not theirs:

Cardinal planes · Horizontal and Vertical

These correspond to flexion-extension and radial-ulnar deviation — the best-studied planes in the wrist proprioception literature and the starting point for proprioceptive awareness training (Hagert & Rein Stage 2). Radial-ulnar deviation shows the highest proprioceptive acuity of the three planes tested in healthy wrists (3.68° ± 0.32°) compared to flexion-extension (4.64° ± 0.24°) and pronation-supination (5.15° ± 0.37°), as measured by robotic workspace mapping (Marini et al., 2016).

Diagonal planes · D1 and D2

The diagonal planes capture the functional combined-axis movement patterns used during activities of daily living — simultaneous flexion-extension and radial-ulnar deviation, with some forearm rotation. The D2 diagonal at the wrist includes the arc from radial extension to ulnar flexion that has been proposed as the primary functional direction of the radiocarpal joint — the Dart Thrower's Motion (Crisco et al., 2005; Moritomo et al., 2014). The specific wrist motion in each diagonal differs between right and left hand. See the Dart Thrower's Motion page for the hand-by-hand mapping. WristSkill uses the diagonals for Stage 3, conscious neuromuscular control, which Hagert and Rein describe as training specific muscles consciously through isometric, eccentric, and co-activation exercises.

Circumduction · Clockwise and Counter-clockwise

Full-envelope rotation probes the most comprehensive form of multi-plane sensorimotor integration. Circumduction is appropriate for late-stage rehabilitation and advanced training. WristSkill places it with Stage 4, unconscious neuromuscular rehabilitation, which Hagert and Rein describe as training the reflex and joint-protective senses.

What WristSkill does not claim

WristSkill does not currently include a static joint position sense metric. A dedicated JPS hold-still trial is under consideration for a future version. Until that time, WristSkill metrics reflect dynamic motor performance, not static proprioceptive acuity as operationally defined in the research literature.

The psychometric properties of WristSkill — test-retest reliability, normative ranges, responsiveness to intervention — have not yet been established in peer-reviewed research. Reliability and normative-data studies are being developed in partnership with academic OT programs, and there are ongoing opportunities for investigators interested in this work.

Evidence gaps we're aware of

The published literature on wrist sensorimotor rehabilitation still has open questions. We list a few here because clinicians should know what is settled, what isn't, and where WristSkill sits within that landscape.

• No RCT has validated the four-stage protocol proposed by Hagert and Rein (2024).
• No RCTs directly compare Dart Thrower's Motion-based protocols to cardinal-plane rehabilitation outside a single pilot study in distal radius fracture (Kaufman-Cohen et al., 2021).
• Proprioceptive deficit is best documented in distal radius fracture and post-stroke populations; evidence for isolated scapholunate, lunotriquetral, and triangular fibrocartilage complex injury is thinner.
• Adding closed kinetic chain exercise to conventional therapy improved wrist JPS more than conventional therapy alone in one randomized trial after conservatively treated distal radius fracture (Menek & Dansuk, 2025) — but it is a single trial of 40 participants.
• In a randomized trial of 60 patients after distal radius fracture surgery, adding a sensorimotor protocol to standard therapy gave better clinical results, mostly at the wrist and not all significant, but did not show efficacy for proprioceptive deficits (Wollstein et al., 2019).