HengaoDe HAD-999 Eyes-Closed Single-Leg Stance Timer

Overview

The HengaoDe HAD-999 Eyes-Closed Single-Leg Stance Timer is a dedicated clinical and rehabilitation assessment instrument engineered for objective quantification of static postural stability under proprioceptively challenged conditions. It operates on the principle of timed motor task execution—measuring the duration an individual can maintain unilateral stance with eyes closed, thereby isolating vestibular and somatosensory integration while suppressing visual input. This protocol aligns with standardized balance evaluation frameworks used in geriatric assessment, neurological screening (e.g., post-stroke or Parkinson’s disease monitoring), sports medicine return-to-play protocols, and physical therapy outcome measurement. The device features a microprocessor-controlled timing circuit with zero-drift calibration, ensuring high reproducibility across repeated trials without manual stopwatch dependency.

Key Features

• High-resolution digital display with 1-second resolution and ±1% full-scale accuracy over the 1–999 second range
• Dedicated tactile push-button interface: power toggle, manual reset, and peak-hold function for immediate result capture
• AC-powered operation (220 V, 50 Hz) with stable internal voltage regulation to prevent timing drift under line fluctuations
• Robust industrial-grade enclosure rated for continuous use in clinical laboratories, rehabilitation centers, and field testing environments
• Low-power standby mode with automatic display blanking after idle timeout, extending component service life
• No embedded software dependencies—fully deterministic hardware-based timing architecture compliant with ISO/IEC 17025 traceability requirements for manual timing instruments

Sample Compatibility & Compliance

The HAD-999 is designed for human subject testing only and requires no consumables, reagents, or calibration standards beyond initial factory verification. It supports standard clinical protocols including the NIH Toolbox® Balance Battery and the Berg Balance Scale (BBS) single-leg stance subtest. While not a medical device under FDA 21 CFR Part 820 or EU MDR Annex II, its measurement methodology conforms to consensus guidelines published by the American College of Sports Medicine (ACSM) and the International Society of Postural Control and Gait Research (ISPGR). The unit complies with GB/T 28803–2012 (“General Requirements for Medical Electrical Equipment Used in Clinical Assessment”) for electrical safety and electromagnetic compatibility (EMC) in non-invasive diagnostic instrumentation.

Software & Data Management

The HAD-999 is a standalone hardware timer with no onboard data logging, network connectivity, or firmware-upgradable components. All measurements are displayed in real time and retained in volatile memory until manually cleared using the reset button. For longitudinal tracking, users must record results externally—either in paper-based case report forms (CRFs) or electronic health records (EHRs) compliant with HIPAA or GDPR. Its simplicity ensures full auditability: no software validation is required per FDA 21 CFR Part 11, and no electronic records are generated that would necessitate ALCOA+ (Attributable, Legible, Contemporaneous, Original, Accurate, Complete, Consistent, Enduring, Available) compliance documentation. This makes it suitable for GLP-regulated preclinical studies where minimal instrument qualification is mandated.

Applications

• Clinical neurology: Quantitative assessment of cerebellar dysfunction, peripheral neuropathy, and vestibular hypofunction
• Geriatric fall risk stratification per CDC STEADI initiative protocols
• Sports rehabilitation: Monitoring recovery progression following ACL reconstruction, ankle sprain, or concussion management
• Occupational health: Baseline and periodic postural stability screening for workers in high-fall-risk roles (e.g., construction, utility line maintenance)
• Academic research: Standardized endpoint collection in randomized controlled trials evaluating balance-training interventions
• Regulatory submissions: Supporting functional outcome data in 510(k)-exempt Class I device dossiers where static balance is a secondary endpoint

FAQ

Is the HAD-999 certified as a medical device?

No. It is classified as a general-purpose clinical timing instrument under Chinese regulatory framework GB/T 19001 and does not carry CE marking, FDA 510(k), or NMPA registration. Its use is restricted to non-diagnostic, observational balance assessment.

Does the device require annual calibration?

While not mandated by international standards for manual timers, we recommend verification against a traceable time standard (e.g., NIST-traceable quartz oscillator) every 12 months in accredited laboratories performing ISO/IEC 17025-compliant testing.

Can it be integrated with EMG or force plate systems?

No. The HAD-999 has no analog/digital output ports, TTL triggers, or synchronization interfaces. Timing initiation is strictly operator- or subject-initiated via mechanical contact.

What environmental conditions affect measurement reliability?

Ambient temperature extremes (40 °C) may induce minor LCD response lag; relative humidity above 90% RH risks condensation on internal PCB traces. Operation within specified ranges ensures metrological integrity.

Is training required to operate the instrument?

Minimal—standardized administration follows published test protocols (e.g., “stand on dominant leg, close eyes, lift contralateral foot freely”). No technical certification is needed, though inter-rater reliability training is recommended for multi-clinician deployments.