Phase Level Assessment of Ergonomic Intervention Effectiveness in Reducing Knee Musculoskeletal Disorder Risks During
Nazia Zerin1, Scott P Breloff2, Fei Dai1
1Wadsworth Department of Civil and Environmental Engineering, West Virginia University, Morgantown, West Virginia, USA.
Background:
This study aimed to assess how knee savers (KSs) and knee pads (KPs) alleviate risks of knee musculoskeletal disorders (MSDs) among roofers during various phases of shingle installation. These phases encompass (1) reaching for shingles, (2) placing shingles, (3) grabbing a nail gun, (4) moving to the first nailing position, (5) nailing shingles, (6) replacing the nail gun, and (7) returning to an upright position.
Methods:
In a laboratory setting, nine male participants simulated the shingle installation task on a slope-adjustable roof platform (0°, 15°, and 30° slopes) under four intervention conditions: no intervention (NO); with KPs only (KP); with KSs only (KS); and with both KPs and KSs (BO). Knee flexion, abduction, adduction, and internal/external rotations were measured to assess intervention impact through statistical analysis.
Results:
Phase 5 (nailing shingles), one of the riskiest phases, saw reduced knee rotations, with BO and KP interventions being the most effective. Phase 6 (replacing the nail gun) exhibited notable reductions in all knee rotations, primarily due to BO intervention. Significant improvements in certain knee angles for other phases were noted, particularly with BO intervention.
Conclusions:
BO and KP can lower knee strain by minimizing extreme knee postures and thereby reducing the risk of MSDs during the installation of shingles, especially at critical periods and on steeper slopes. This study highlights the importance of applying focused ergonomic techniques in the roofing sector to improve workers' musculoskeletal health.
