Tactile Perception of Pressure and Volitional Thrust Intensity Modulate Spinal Manipulation Dose Characteristics

OBJECTIVE

The purpose of this study was to examine clinicians' ability to modulate spinal manipulation (SM) thrust characteristics based on their tactile perception of pressure and volitional intensity.

METHODS

In a cross-sectional, within-participants design, 13 doctors of chiropractic delivered SM thrusts of perceived least, appropriate, or greatest intensity of their perceived safe output level for an SM thrust on low-fidelity thoracic spine models of 4 different pressure levels. The participants performed SM over the course of 96 trials in a randomized order on combinations of thrust intensity and pressure. Dependent variables included normalized preload force, thrust force, thrust duration, peak acceleration, time to peak acceleration, and displacement. For all dependent measures, 2-factor within-participants analysis of variance models with repeated measures on both factors were performed.

RESULTS

Preload force increased with intensity (F_2,24 = 9.72; P < .001) and model pressure (F_3,36 = 4.27; P = .011). Participants modulated thrust force and displacement as each also increased with intensity escalation (F_2,24 = 22.53, P < .001; F_2,18 = 45.20, P < .001). The highest accelerations were observed during the greatest intensity. Increased thrust force was delivered at higher model pressures (F_3,36 = 6.43; P < .001). A significant interaction demonstrated that as volitional thrust intensity increased, greater displacement was attained, particularly on low pressure models (F_6,54 = 11.06; P < .001). Thrust duration and time to peak acceleration yielded no significant differences.

CONCLUSION

Spinal manipulation thrust dosage was modulated by the chiropractors' tactile perception of pressure and volitional intensity.

Differences of Cutaneous Two-Point Discrimination Thresholds Among Students in Different Years of a Chiropractic Program

OBJECTIVES

The aim of this study was to investigate if there were differences in the two-point discrimination (2-PD) of fingers among students at different stages of a chiropractic program.

METHODS

This study measured 2-PD thresholds for the dominant and nondominant index finger and dominant and nondominant forearm in groups of students in a 4-year chiropractic program at the International Medical University in Kuala Lumpur, Malaysia. Measurements were made using digital calipers mounted on a modified weighing scale. Group comparisons were made among students for each year of the program (years 1, 2, 3, and 4). Analysis of the 2-PD threshold for differences among the year groups was performed with analysis of variance.

RESULTS

The mean 2-PD threshold of the index finger was higher in the students who were in the higher year groups. Dominant-hand mean values for year 1 were 2.93 ± 0.04 mm and 1.69 ± 0.02 mm in year 4. There were significant differences at finger sites (P < .05) among all year groups compared with year 1. There were no significant differences measured at the dominant forearm between any year groups (P = .08). The nondominant fingers of the year groups 1, 2, and 4 showed better 2-PD compared with the dominant finger. There was a significant difference (P = .005) between the nondominant (1.93 ± 1.15) and dominant (2.27 ± 1.14) fingers when all groups were combined (n = 104).

CONCLUSIONS

The results of this study demonstrated that the finger 2-PD of the chiropractic students later in the program was more precise than that of students in the earlier program.

PROSPECTIVE STUDY ON TACTILE SENSITIVITY IN THE HANDS OF A BRAZILIAN POPULATION USING THE PRESSURE-SPECIFIED SENSORY DEVICE

OBJECTIVE

To evaluate the pressure perception thresholds on the pulp of two fingers (index and little fingers), among a Brazilian population with no nerve injury or neuropathy.

METHODS

We used the Pressure-Specified Sensory Device (a computerized device) to derive static and dynamic normal pressure perception thresholds and two-point discrimination distances.

RESULTS

We tested finger sensitivity on 30 volunteers. Significance analyses were performed using the Student t test. The mean values (g/mm(2)) for static one and two-point pressure thresholds (s1PD, s2PD) and dynamic one and two-point discrimination (m1PD, m2PD) in the dominant index finger were: s1PD = 0.4, m1PD = 0.4, s2PD = 0.48, m2PD = 0.51.

CONCLUSION

There was no significant difference in sensitivity between the dominant and nondominant hands.