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Related Experiment Video

Updated: May 31, 2026

Design and Application of a Fault Detection Method Based on Adaptive Filters and Rotational Speed Estimation for an Electro-Hydrostatic Actuator

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More malfunctioning Medos Hakim programmable valves: cause for concern?

Uwe Max Mauer¹, Ulrich Kunz

¹Department of Neurosurgery, German Armed Forces Hospital of Ulm, Germany. UweMaxMauer@bundeswehr.org

Journal of Neurosurgery

|July 12, 2011

Summary

Programmable valve defects, specifically stator dislodgement in Medos Hakim valves, are rare but require attention. Malfunctions were noted in nearly 3% of valves, particularly in infants.

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Area of Science:

Neurosurgery
Biomedical Engineering
Pediatric Surgery

Background:

Growing incidence of programmable valve defects observed.
Need to evaluate the frequency of specific valve malfunctions.

Purpose of the Study:

To assess the incidence of stator dislodgement in Medos Hakim programmable valves.
To identify risk factors associated with valve malfunction.

Main Methods:

Retrospective review of valve revisions between 1994 and 2010.
Focus on Medos Hakim programmable valves with prechambers.

Main Results:

15 valves (nearly 3%) removed due to stator dislodgement.
Valves were implanted between 1993 and 2002, in place for a mean of 11 years.
All malfunctioning valves were in children under one year at implantation.

Conclusions:

Medos Hakim programmable valve malfunctions, though rare, necessitate careful monitoring.
Suspect malfunction if pressure settings are unadjustable; use imaging.
Stator dislodgement represents a critical valve adjustment failure.