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Multiplanar Wrist Joint Proprioception: The Effect of Anesthetic Blockade of the Posterior Interosseous Nerve or Skin Envelope Surrounding the Joint
Kenneth F. Taylor, MD; Robert J. Lachky; Vanessa M. Meyer; Laurel B. Coffey; Michael B. Lustik; Tripler Army Medical Center
Tripler Army Medical Center, Honolulu, HI, USA
Introduction: Contribution of the posterior interosseous nerve (PIN) and the surrounding skin envelope to wrist joint proprioception is a topic of debate and the primary focus of this research.
Materials & Methods: A noninvasive multiplanar testing device isolated wrist motion. From a neutral start position, subjects pointed to specific hours on an analogue clock face hidden from view. One repetition for each hour was assigned randomly for each of three cycles. This was repeated for the opposite wrist. Subjects were randomized to two treatment groups. In one group, subjects underwent anesthetic lidocaine blockade of the PIN within the fourth dorsal wrist compartment. The opposite placebo control wrist underwent injection with sterile saline. In the second group, subjects underwent circumferential topical anesthetic lidocaine gel blockade of superficial cutaneous nerves about the treatment wrist. The opposite side received the placebo inert ultrasound gel. Subjects repeated joint proprioceptive testing.
Results: Eighty consecutive subjects, 45 male and 35 female, mean age 33 years (range, 19 to 64 years), completed testing. Overall accuracy and precision were generally good regardless of treatment, with approximately 90% of measurements falling within ± 18 degrees of the true value. Accuracy differed significantly across degrees. Participants were much less accurate when trying to hit 210° than other points. Using an acceptable range of within ± 18 degrees, the percent of measurements falling outside the range did not differ between baseline and post-treatment for the treated wrists and the control wrists for either PIN blockade (p=0.22; OR=1.14, 95% CI: 0.85, 1.51), or for circumferential skin anesthesia (OR=1.15, 95% CI: 0.92, 1.45). There was no significant difference between pretreatment measures and placebo control measures (p=0.38; OR=1.04, 95% CI: 0.87, 1.25, p=0.65), further indicating no treatment effect.
Conclusions: Previous studies have contributed to understanding of wrist proprioception but have been limited by methodological flaws. Some have compared patients with previous PIN neurectomy as part of varying surgical procedures to healthy controls. Some have measured reflexive muscular activation after stimulation of intrinsic ligaments. Most have only tested the wrist in isolated sagittal plane motion at large motion intervals. If an isolated mechanism such as the PIN or skin envelope were responsible for wrist proprioception, a double-blind randomized study of normal volunteers, in which the joint was assessed in multiple planes at close intervals, would most likely be of sufficient sensitivity to detect this change. Wrist proprioception is therefore likely to be a multifactorial phenomenon.
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