Shoulder pain and jerk during recovery phase of manual wheelchair propulsion

Abstract

Repetitive loading of the upper limb due to wheelchair propulsion plays a leading role in the development of shoulder pain in manual wheelchair users (mWCUs). There has been minimal inquiry on understanding wheelchair propulsion kinematics from a human movement ergonomics perspective. This investigation employs an ergonomic metric, jerk, to characterize the recovery phase kinematics of two recommended manual wheelchair propulsion patterns: semi-circular and the double loop. Further it examines if jerk is related to shoulder pain in mWCUs. Data from 22 experienced adult mWCUs was analyzed for this study (semi-circular: n=12 (pain/without-pain:6/6); double-loop: n=10 (pain/without-pain:4/6)). Participants propelled their own wheelchair fitted with SMARTWheels on a roller dynamometer at 1.1 m/s for 3 min. Kinematic and kinetic data of the upper limbs were recorded. Three dimensional absolute jerk experienced at the shoulder, elbow and wrist joint during the recovery phase of wheelchair propulsion were computed. Two-way ANOVAs were conducted with the recovery pattern type and shoulder pain as between group factors.

Findings: (1) Individuals using a semi-circular pattern experienced lower jerk at their arm joints than those using a double loop pattern (P<0.05, η(2)=0.32)wrist;(P=0.05, η(2)=0.19)elbow;(P<0.05, η(2)=0.34)shoulder and (2) individuals with shoulder pain had lower peak jerk magnitude during the recovery phase (P≤0.05, η(2)=0.36)wrist;(P≤0.05, η(2)=0.30)elbow;(P≤0.05, η(2)=0.31)shoulder.

Conclusions: Jerk during wheelchair propulsion was able to distinguish between pattern types (semi-circular and double loop) and the presence of shoulder pain. Jerk provides novel insights into wheelchair propulsion kinematics and in the future it may be beneficial to incorporate jerk based metric into rehabilitation practice.

Keywords: Ergonomics of movement; Jerk cost; Motor control; Repetitive strain injury; Shoulder rehabilitation; Wheelchair propulsion.

Figure 1

The instantaneous resultant velocity, acceleration and jerk at wrist from a sample DLOP (a1–a4) and SC (b1–b4) recovery pattern type. The solid lines in all the plots belong to the recovery phase and the dotted line to the push phase. The resultant velocity plot for wrist during the recovery for a DLOP (solid lines - a2) has two asymmetric velocity profile one for each loop as opposed to a SC pattern (solid line - b2). The rate of change of acceleration and deceleration for a DLOP (solid line – a3) is greater than a SC (solid line – b3) pattern. The jerk magnitude for the DLOP (solid line – a4) is greater than a SC (solid line – b4) pattern.

Figure 2

A sample time normalized (0% – 100% points) recovery trajectory absolute jerk curve at wrist for SC and DLOP patterns. (a) & (b) Push (dotted lines) and recovery (solid lines) phases for a SC and DLOP pattern respectively. The 0% and 100% points represent the start and end of the recovery phase. There are 100 data points between the 0% to 100% points; (c) & (d): Peak jerk magnitudes at wrist during a SC and the DLOP recovery pattern respectively. Peak jerk magnitude at wrist occurred between 0% to 30% (P1,P3,P4) and 70% to 100% (P2,P5) intervals along the recovery trajectory. These peak jerk points typically were seen to occur at those intervals along the recovery phase that required steep acceleration and deceleration rate of change.

Figure 3

The jerk cost criteria (J_c). (a) & (b) a sample SC and DLOP pattern recovery phase absolute jerk curve depicting the area under curve as shaded regions respectively. The scheme used for computing J_c is shown below the figures. C_m : the propulsion cycle located closest to the mid of the trial (i.e. 90 seconds from the start of trial).

Figure 4

The peak jerk criteria (PJ_c). (a) a sample plot from the SC group comparing P_{max(0%–30%)} values between two individuals, with and without shoulder pain. (b) a sample plot from the DLOP group comparing P_{max(0%–30%)} values between two individuals, with and without shoulder pain. The scheme used for computing P_max and PJ_c is shown below the figures. C_m : the propulsion cycle located closest to the mid of the trial (i.e. 90 seconds from the start of trial).

Figure 5

Group mean comparison for J_c at the arm joints between SC and DLOP groups (a) group mean J_c at wrist joint for SC group is lower than that of the DLOP group; (b) group mean J_c at elbow joint for SC group is lower than that of the DLOP group; (c) group mean J_c at shoulder joint for SC group is lower than that of the DLOP group. (*P≤0.05).

Figure 6

Group mean comparison for PJ_c at arm joints between groups with and without shoulder pain. (a) Group mean PJ_c at wrist joint for shoulder pain group is lower than that of the group without shoulder pain; (b) Group mean PJ_c at elbow joint for shoulder pain group is lower than that of the group without shoulder pain; (c) Group mean PJ_c at shoulder joint for shoulder pain group is lower than that of the group without shoulder pain. (*P≤0.05).