The case for WristSkill™.

By Joseph Sharaya, OTD, OTR/L, CHT · Certified Hand Therapist · Last reviewed April 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 — patients often describe the wrist as feeling disconnected, even after range of motion and strength have returned (Hagert & Rein, 2024).

It's measurable.

Active joint position sense testing has demonstrated excellent test-retest reliability (ICC 0.88–0.92) in the populations where it has been applied, with a minimum detectable change of approximately 8 degrees (Carey et al., 1996). In patients after distal radius fracture, JPS error shows the strongest correlation with functional disability scores — as measured by the Patient-Rated Wrist Evaluation, or PRWE — of any sensorimotor measure tested (Karagiannopoulos et al., 2013), with responsiveness improving from 8 weeks (effect size 1.53) to 12 weeks post-injury (effect size 2.36) (Karagiannopoulos et al., 2016).

The healthy baseline is narrow.

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). The clinical impairment threshold is approximately 11 degrees — one standard deviation above the healthy range of 3.1 to 10.9 degrees (Carey et al., 1996). 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°), followed by flexion and extension (4.64° ± 0.24°), and pronation and supination (5.15° ± 0.37°) (Marini et al., reported in Hagert & Rein, 2024).

The measurement gap

Despite the quality of this evidence, no FDA-cleared device exists 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. Goniometric JPS testing is validated but labor-intensive and dependent on therapist skill (Hagert & Rein, 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 evidence-based. It maps onto the progressive staging of wrist sensorimotor rehabilitation described by Hagert and Rein (2024):

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., reported in Hagert & Rein, 2024).

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 represents a 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. Diagonals correspond to Stage 3 conscious neuromuscular control in the Hagert and Rein protocol.

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, aligning with Stage 4 unconscious and reactive neuromuscular control.

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 Hagert and Rein four-stage protocol as a whole, though its components are well-evidenced individually (Hagert & 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., 2020).
• 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.
• Closed kinetic chain exercise has the strongest direct evidence for improving wrist JPS (Özyürek & Tuna, 2025) — but it is a single trial of 40 participants.