Letters To The Editor-In-Chief
The recent and interesting article by Refshauge et al. (MSSE, 32:10–15,2000) addresses the issue of altered ankle joint proprioception in subjects suffering recurrent ankle sprains. The general questions of whether joint proprioception is diminished secondary to joint injury, and perhaps more importantly whether diminished proprioception contributes to recurrent joint dysfunction, are of broad clinical interest and potential importance in the area of sports medicine rehabilitation. With respect to the ankle complex, proprioception has been investigated for over 40 years.
Two issues seem central to the question of whether compromised ankle complex proprioception underlies recurrent ankle sprains. The first issue is the extent to which ankle complex proprioception is disrupted by joint injury. The second issue is whether diminished ankle complex proprioception contributes to chronic ankle complex dysfunction. The latter issue represents the more formidable of the two. With respect to the ankle complex, a relationship that meets the criteria of causality and that links diminished ankle complex proprioception and recurrent ankle sprains has not been demonstrated.
In light of the broad interest and potential importance of proprioception-related research to sports medicine rehabilitation, it is prudent to correct an error made by Refshauge et al. in their Introduction. The error is one of interpretation. Refshauge et al. cited Feuerbach et al. (1) as having reported that application of an Aircast Air-Stirrup did not enhance ankle complex proprioception in any plane of movement. This interpretation is incorrect. We used a three-dimensional angle-matching test to derive three measures of ankle complex proprioception during a control condition, in which an Aircast was not worn, and a second condition, in which an Aircast was worn. The dependent variables were mean constant error, mean absolute error, and mean variable error, each of which was measured for ankle plantarflexion and dorsiflexion, inversion and eversion, and abduction and adduction. The between-condition differences were not significant for constant error. However, the between-condition differences were significant for absolute and variable errors. Based on our findings, and in contrast to the interpretation of Refshauge et al., we concluded that ankle complex proprioception was facilitated by application of the Aircast Air-Stirrup. This finding is consistent with many published neurophysiological studies on the influence of stimulation of cutaneous receptors and increased proprioception (see review by Lephart et al. (2)). Indeed, we have reported increased excitability of peroneus longus spinal motorneurons after application of an Aircast Air-Stirrup (Nishikawa and Grabiner (3)).
Despite the differences in the manner in which Refshauge et al. and Feuerbach et al. measured of proprioception, our findings are not consistent with those of Refshauge et al. Although Refshauge et al. do not explicitly make this parallel in the paper, the misinterpretation made in their Introduction could lead readers to the wrong conclusion. In part, the importance of correcting the misinterpretation relates to there being only a small number of published papers on ankle complex proprioception, measured as the ability to sense isolated ankle complex position or motion. The findings of Refshauge et al. may be outnumbered by reports, including ours, in which proprioception has been improved by an orthosis or tape. I appreciate the opportunity to correct this matter of published record.
Mark D. Grabiner Ph.D., FACSM
1. Feuerbach, J. W., M. D. Grabiner, T. J. Koh, and G. G. Weiker. Effect of an ankle orthosis and ankle ligament anesthesia on ankle joint proprioception. Am. J. Sports Med. 22:223–229, 1994.
2. Lephart, S. M., D. M. Pincivero, J. L. Giraldo, and F. H. Fu. The role of proprioception in the management and rehabilitation of athletic injuries. Am. J. Sports Med. 25:130–137, 1997.
3. Nishikawa, T. and M. D. Grabiner. Prophylactic ankle bracing increases the excitability of peroneal muscle motorneurones. J. Orthop. Sports Physical Ther. 29:168–173, 1999.