Effect of Using an 8-Figure Shoulder Brace on Posture and Muscle Activities during the Performance of Dental Hygiene Procedures

The incidence of work-related musculoskeletal disorders (MSDs) among dental workers has been increasing. Many ergonomic devices and accessories have been introduced. The aim of this study was to investigate the effects of an 8-figure shoulder brace on posture-related muscle activities in dental hygiene practitioners during scaling procedures. In this study, 33 participants (age: 21.9 ± 2.1 years, height: 162.0 ± 6.0 cm, weight: 55.8 ± 9.0 kg, body mass index: 21.2 ± 2.4 kg/m2) performed the scaling procedure with and without the 8-figure shoulder brace in a randomized order. The normalized electromyography activity in the amplitude probability distribution function and joint angles (cervical, thoracic, lumbar, and shoulder joints) were simultaneously recorded during scaling. A paired t test was used to compare the differences in muscle kinematics, with the alpha level set at 0.05. The dental hygienists who wore the 8-figure shoulder brace during scaling showed thoracic and lumbar extension, improved sitting postures, and reduced shoulder joint abduction. However, we also observed an unintended increase in internal rotation. Use of the 8-figure shoulder brace could prevent work-related MSDs in lumbar and thoracic regions by reducing the effort exerted by the upper trapezius and deltoid muscles, despite the increased muscular effort of the cervical erector spinae.

Intentional Overscrewing of Humeral Head in Comminuted Fracture of Proximal Humerus and its Impact on Shoulder Function . A Case Study

An 86-year-old female was operated on due to a comminuted fracture of the right proximal humerus whose configu­ration necessitated over-screwing of the humeral head to improve stability, with the screws directed divergently: anteriorly and poste­riorly, to minimize their conflict with the acetabulum. 3.5 years later she sustained a corresponding fracture of the left shoulder which was stabilized without over-screwing. On both occasions, the fractures were stabilized with titanium interlocking plates (ChM, Poland) and the limbs were immobilized in a shoulder brace for three weeks followed by in­tensive rehabilitation. The patient attended a follow-up visit at 12 months (i.e. 52 months post the right shoulder fracture) which included an assess­ment of radiographs, pain and limb function as well as tests of the range of movement of the shoulder and girdle. Assessments were repeated at 12 and 18 months afterwards. Patient denied limb pain and dysfunction. Abduction was reduced by 20°, which was compensated for by the scapulothoracic joint. Shoulder (girdle) abduction reached 50° (150°) for the right and 70° (170°) for the left extremity. Flexion was reduced by 20°, but extension and rotations were comparable. At 12 months post fracture, no improvement of limb mobility was noted despite continued intensive physiotherapy. X-rays showed satisfactory bone union. The patient scored 87 for the right and 89 for the left shoulder according to the Con­stant score and 6.8 points for each limb according to the QuickDash score. Overscrewing of the humeral head is not the most beneficial method for improving stability of comminuted proximal humeral fractures; however, it may be used when alternative and more suitable methods are unavailable. Moreover, directing screws divergently anteriorly and posteriorly to minimize their conflict with the scapular acetabulum does not interfere with joint function outcomes.

Evaluating the Usability of Alternative Shoulder Stabilization Methods

Braces are commonly used to stabilize and restrict movement of the arm and shoulder after injury, such as dislocation (Itoi, Hatakeyama, and Kido, 2003). However, secondary pain and discomfort cause concern for clinicians when prescribing braces to patients that require shoulder stability, and may result in poor compliance by the patient if prescribed for long durations. Popularly used braces have been associated with secondary pain in surrounding areas, such as the neck and shoulders, compared to rehabilitative outcomes without the use of braces (Struijs, Kerkhoffs, Assendelft, and van Dijk, 2004). Straps are often used in conventional brace design for stability, yet they are potential sources of discomfort. Novel supporting methods used in more recently developed braces could mitigate the above concerns associated with traditional bracing methods (i.e., discomfort and low ease of use) while stabilizing the shoulder. We examined the usability of five brace designs, including a newly developed brace. Selected existing products were used to represent a spectrum of different design approaches (e.g., brace shape and coverage, connector locations, and straps) and included, in alphabetical order: 1) Bledsoe Clinic Shoulder Immobilizer (“Sling”) (Bledsoe Brace Systems, Grand Prairie, TX, bledsoebrace.net ), 2) Breg SlingShot 3 Shoulder Brace (“SlingShot”) (Breg, Inc. Carlsbad, CA, www.breg.com ), 3) Breg Straight Shoulder Immobilizer (“Straight”) (Breg, Inc. Carlsbad, CA, www.breg.com ), and 4) Bledsoe Sling and Swathe Immobilizer (“Swathe”) (Bledsoe Brace Systems, Grand Prairie, TX, bledsoebrace.net ). The new brace design ( www.kaykare.net ) includes a sleeve and single waist strap. A total of 10 young adults (M = 24.2±4.9 years old) and 10 older adults (M = 66.9±4.3 years old), gender-balanced in each group, were recruited to enhance generalizability of results. A within-subjects design was implemented to test donning/doffing performance, perceived stability and comfort of the selected arm braces. The study included controlled tasks involving donning and doffing on the self and on a simulated “patient” as the participant acted as a “caregiver,” along with simulated activities of daily living, to compare brace performance. Outcome measures included donning/doffing times, ratings and rankings of ease of use, and stability and comfort ratings and rankings, and these were compared between age, gender, and braces using Analyses of Variance. Participants had significantly lower donning and doffing times while using the new brace versus the other braces, and it was rated as having a higher level of ease when donning/doffing. The “Swathe” type of brace was rated as having the highest level of stability, while comfort ratings were not significantly different between braces. Braces more frequently selected as the preferred brace at the end of the study, such as the “Sling,” are more commonly provided braces at clinics or in emergency scenarios (Hatta, Sano, Yamamoto, and Itoi, 2013). Non-traditional strapping methods used in the new brace and the “Straight” were often perceived as being less stable due to fewer straps. Throughout data collection, it was found that as straps increase on the brace, greater stability is perceived, although application ease and donning time will likely increase. These results reveal that the newer brace design offers a potential solution to emergency shoulder immobilizing when compared to popularly supplied braces, though patients may perceive greater support while wearing a brace with more straps. However, the current work is limited by a healthy participant pool, and future work should explore patient responses to actual prescription of each brace. Long-term use should also be examined to capture experiences beyond the laboratory.