Ergonomic considerations from head to toe

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Ergonomics is a wide ranging field that seeks to design tools, equipments and tasks to optimize human capabilities. The term ergonomics was coined from Greek worda 'ergon' (meaning "work") and 'nomous' (meaning "rule"), so the literal meaning is "the rule of work" which is a handy concept to think about and then apply.

Rehabilitation practitioners (Occupational Therapist and Physiotherapist) have a distinct value in the area of ergonomics based on understanding the complex and dynamic interactions of the person, the task (i.e., job), and the context and environment (e.g., culture and personality, and where the task occurs). The skills and knowledge of rehabilitation practitioners in anatomy, physiology, and activity analysis make them highly qualified to work in the area of ergonomics, often within an interdisciplinary team. Rehabilitation practitioners are well equipped to facilitate the successful return of patient to optimal function through education and intervention of person, and adaptation or modification of physical environment like home, workplace or public areas.

In the previous article we have learned about Principles of Ergonomics (click on the below link)

https://otpthealthcarerehab.blogspot.com/2020/10/principles-of-ergonomics.html

Knowledge of ergonomic practice is critical to help the patients and common people to adapt postures and modify activities or work techniques, that are performed on a sustained or repetitive basis at work, at home, recreationally, or socially, if they are contributing to the postural stresses and musculoskeletal disorders. There are many evidences available in various journals which will show the readers, the positive impact of ergonomic practices in daily living and daily activities.

Why to practice ergonomics ???

Implementation of ergonomic principles in daily activities will help to improve the quality of life and decreases the risk of health problems and injuries in patients and common people.
Ergonomic practice helps to conserve energy of our body during work and helps to maintain the quality of work and mental functioning of the worker.
Good ergonomics can put people in a better position to do the job they are capable of. Ergonomics can be applied to any human activity, including home chores and leisure activities.
Ergonomically designed activities and work environment will decrease the physical, cognitive and psychosocial health complaints related to work. It helps to maintain the quality of life, reduce stress and increase work performance, increase work satisfaction and better work environment and social interaction is maintained.
When you learn the ergonomic principles then it can be applied in almost every performance areas (ADL, Work and leisure). Educating ergonomic principles and applications to worker will provide safety in their job. It can be applied in

house environment, house work (daily chores, ways of sweeping floor, methods used for washing and cleaning clothes or utensils, body posture during occupational performance, kitchen platform height)
industrial workstation (lifting techniques, worksurface height, platform height, tool or equipment handling and ways to perform, environmental conditions, proper fitting of safety wear objects)
restaurants (sitting arrangements and table height, ceiling height, kitchen platform height, choice of cutlery or knives for making or preparing food)
office environment (sitting or laptop arrangment, work hours or shifts, ergonomic chair),
hospital and rehabilitation settings (bed height, toilet area, wheelchair maneuvering space, considering the therapist or patients body posture during exercise sessions, chair height, exercise equipments or machinary usage by various age group patients)
Sports and leisure activities (footwear or shoes selection and fitting, sport environment, type of sports or leisure activities, weight or height or size of objects used during play, body postural requirements during performance, proper fitting of safety wear items )

Fig : Wrong ergonomics posture during work can cause excessive stress and challenge on the specific joint, it's muscles, tendon and ligaments.

When the work involves frequent use of a specific joint then ergonomics principles for that joint should also be understood and applied accordingly during any activity performance. Every body part has its potential musculoskeletal disorders (MSDs) and ergonomic design principles for prevention of joint stress. In this article we will gain knowledge about MSDs occurring due to cumulative trauma or overuse syndrome of specific joints.

We will understand the ergonomic considerations from head to toe :

1) Head/ Neck : Nerve supply to the entire body is travelled via neck to rest of the body parts. Neck is a mobile structure through which all the sensitive ascending and descending nerve pathways are passing. It has the high potential to get injured due to sudden jerk, accidents, muscle strain or ligament sprain (due to heavy lifting or awkward postures).

Potential MSDs are thoracic outlet syndrome, tension neck syndrome, prolapsed intervertebral disc, cervical disc disease.
Ergonomic design principles :

Avoid prolonged and forced forward headed posture and flexed position of neck.
Use of machineries for lifting of heavy loads instead of carrying it individually on head or on shoulders. Take assistance from co-workers, for lifting and carrying loads, when needed.
Avoid narrow viewing angles and visual obstruction. Provide head clearance, in working space areas, to avoid excessive bending and awkward posture of neck.
Avoid maintaining the shoulder against gravity for longer duration in overhead activities. Prolonged overhead or against gravity posture of shoulder girdle can cause fatigue and weakness of trapezius and shoulders muscles. Take a rest pause in between the work or allow the other person to continue with the work whenever possible.
Allow the tallest workers for specific job which require high height level work. Assigning a right worker, for a specific activity, with respect to job requirements is essential.
Natural posture is to look down naturally. Excessive extension or flexion posture of neck can cause stretch weakness, strain of muscle and thus increases the load on passive structures of the joint like ligaments or joint capsule.

Ergonomics design principles and it's applications for healthcare workers namely Surgeons, Dentist, Physiotherapist, Occupational Therapist should also be considered. While treating patients these healthcare professionals has to adopt various postures involving neck, spine, shoulder and lower limbs joints.

During a long surgical procedure and unfavourable environment conditions (light level, temperature) the doctors unknowingly display poor posture commonly like forward head, excessive neck flexion more that 30 degree, shoulder protracted and elevated, excessive leaning and hunched back, etc.
Even Physiotherapist and Occupational Therapist can display wrong or awkward posture at some moments while rehabilitating patient during exercises, gait training, ADL training, teaching transfers, handling heavy patients, balance training etc. Musculoskeletal stress can occur due adoption of awkward posture in small work space area, inappropriate bed height, heavy or tall patients compared to therapist muscular physique, non-cooperative or resistive patient, non-availability of exercise machinary which will substitute for manual work by therapist, unfavourable environmental conditions, treating patients with passive range of movement exercises or while giving manual muscle stretching, etc. This can lead to neck or shoulder pain and strain, low back pain, upper or middle back pain, knee pain.
If these workers adopt wrong or awkward postures then it can lead to musculoskeletal stress on muscles, ligaments or tendons. This can lead to stretch weakness (when muscles are habitually kept in stretched position) or tight weakness (when muscles are habitually kept in shortened position).

2) Shoulder : MSDs of shoulder joint occurs after placing excessive heavy load on it's muscles and ligaments. Shoulder joint and scapular (upper-limbs) structure provides us with large amplitude range of motion, circumduction movement and a very long lever arm. Taking advantage of this we usually unknowingly place heavy stress on the shoulder joint by applying wrong joint biomechanics. Since the upper limb provides very long lever arm or moment arm, holding even small loads in the hand with the arm held away from the body will quickly result in shoulder fatigue and discomfort, and place substantial stress on the tendons in the shoulder.

Potential MSDs are Rotator cuff tendinitis (impingement syndrome), bicipital tenosynovitis, Frozen shoulder or adhesive capsulitis.
Ergonomic design principles :

Replace manual activities, involving shoulder repetitive end range motion, with machine work. Let machine do the work. Make use of trollies or wheeled table to transfer heavy object from one place to other
Place objects between shoulder and waist height. Generally, place heavy objects at a lower level and light or small object at higher level. This will reduce the stress on the shoulder muscles.
Avoid frequent reaches above shoulder and reduce excessive reaching.
Avoid prolonged working greater than 45 degrees of shoulder flexion or abduction. If activities are placed at a higher level then use a raised platform or step to perform the work instead of keeping the arms raised higher than 90 degrees.

3) Elbow and forearm complex : the elbow is a hinge type joint, which helps in elbow flexion and extension, forearm pronation and supination (over pivot point). There are numerous vulnerable soft tissues (tendon, nerves, blood vessels) that passes through the elbow to reach the forearm and hand.

Overuse can occur in any musculotendinous structure in the elbow region, including flexors and extensors of the elbow, but it most commonly occur in the muscles attached to the lateral or medial epicondyles in response to repetitive stressful wrist and elbow motion. Overuse of medial or lateral structures causes microscopic tear and inflammation, termed as epicondylitis and overuse of distal biceps and triceps tendons causes tendonitis.
Potential MSDs are lateral and medial epicondylitis, radial tunnel syndrome, cubital tunnel syndrome, biceps or brachioradialis or triceps strain.
Ergonomic design principles :

Normal work (medium weight) the work surface design should be just below elbow height.
For precision work (light weight) raise the surface above elbow height and provide upper extremity weight bearing support when possible.
For heavy work, the work surface should be 6 to 8 inches below the elbow height.
Avoid fast, frequent, jerky and continuous loading and unloading of heavy object from higher to lower height which require extreme end range elbow extension.

4) Wrist complex : The wrist is the final link of joints that positions the hand for functional activities. It has the significant function of controlling the length-tension relationship of the multiarticular muscles of the hand as they adjust to various activities and grips. The wrist is an incredibly mobile joint that contains numerous tendons, nerves, and blood vessels, which service the hand and are vulnerable to MSD.

Potential MSDs are tendonitis, carpal tunnel syndrome, ganglion cysts, trigger finger, De Quervain's tenosynovitis.
MSDs of hand tissue can occur due to local factors including synovial thickening and scarring in the tendon sheaths (tendinosis) or irritation, inflammation, and swelling of the tendons (tendinitis) as a result of repetitive or sustained wrist flexion, extension, or gripping activities.
Ergonomic Design Principles:

Maintain wrist in neutral position : awkward wrist postures (flexion or extension), compressive forces from sustained equipment usage, and vibration against the carpel tunnel could also lead to median nerve compression and trauma.
Avoid repeated or sustained flexion and ulnar deviation
Avoid repeated or sustained pinching and allow for small hands when designing gripping tasks and selecting hand tools. Allow plenty of access space for large hands.
Injury or irritation of ulnar nerve can occur in Guyon canal or ulnar tunnel as a result of : 1) prolonged handwriting or leaning forward onto extended wrists while biking, 2) from synovial inflammation due to repetitive use of gripping action of the 4th and 5th fingers in activities like knitting, tying knots, using pliers and staplers, 3) from a space occupying lesion, such as ganglion or aneurysm of the ulnar artery.

5) Lower Back : The back is a flexible curved column composed of a series of bones (vertebrae) separated by shock absorbing discs. The structure is held together by a large number of muscles and ligaments. Acting together, they give the spine the ability to bend and twist. The spine protects the spinal cord and acts as a distribution center for the nerves.

Potential MSDs are degenerative disc disease (lumbar spondylosis), strain of spinal muscles, sprain of spinal ligaments and capsule, risk of prolapsed intervertebral disc.
Correct postural alignment is required to perform any activity. Poor posture significantly increases the effective load (weight) to the spinal joints and triggers counterbalancing muscle contraction (effort).
Ergonomic Design Principles:

Avoid repeated lifting that requires excessive forward bending.
Avoid sustained forward bending. Avoid extreme end range postures; instead use steps or platforms to keep objects at a higher level.
Always remember to maintain your spine in neutral as much as possible while performing any activity. Try to relieve extra pressure off spine by making efficient use of upper and lower limbs strength, adopting ergonomically correct postures, environment modifications. Adaptations like working at proper height, use of foot rest or platforms for standing table-top work, alternate with sitting and standing postures (change postures), avoid lifting and placing of heavy object by twisting or rotating body.
When bending from spine (thoracic joints), the lifting force is at a greater perpendicular distance to the pivot (vertebral joint). In this position, the back muscles must exert a huge force to provide a torque that balances the torque from the weight being lifted. If the spinal structure of the back is weak then this will lead to muscle strain or ligament sprain. Majority of injury occurs due to overloading and incorrect execution of movement. Therefore, it is important to keep load close to body (decreased perpendicular distance to pivot) while lifting as well as doing some amount of squatting (using hip and knee musculature) as performed by the man in right side.

6) Legs : Very little research exists on the relationship between work activities and lower extremity MSDs. However, there are some MSDs associated with the legs, and ergonomic design principles that we should keep in mind.

Potential MSDs are Plantar fasciitis, tailor's bunion, tarsal tunnel syndrome, heel spurs, stiffness and pain of knee or ankle joint, bursitis, patellofemoral stress syndrome or illiotibial band syndrome in sports person.
Ergonomic Design Principles:

Avoid repetitive, continuous foot actuation if possible. Add rest pause between work hours.
Avoid repeated walking up and down steps. Eliminate or modify and physical activities that cause knee pain, especially stair climbing, kneeling, squatting and running.
Avoid mechanical stress on the legs. Avoid working conditions in which knee joints are forced in varus or valgus stresses.
Maintain good lower extremity flexibility and strength. Maintain a healthy body weight, which will decrease the direct affect of heavy weight on the knee joint while working in standing or walking for longer duration.
Allow for long legs: Insufficient knee space is a common problem in the industrial workplace, although every part of the body can be affected — the head, torso, feet and hands. For sitting activities the work surface should allow extra space for knee clearance.
Provide adjustments or footrests for shorter legs for prolonged sitting.
Wearing heels or shoes with tapering one end (in front), for longer duration, while working or walking can cause corns or bunion of toe. Wear a comfortable footwear or shoes with proper fit and cushion for shock absorbing. Prefer shoes or footwear with medial arch support. Using a silicone insole or silicone heel pad is also helpful to distribute pressure or decrease pressure at a localized area.
When office workspace is not adequate for proper sitting posture. Contact stress from sitting on hard surfaces, which is the epitome of discomfort from pressure points, can be lessened with cushioning and contouring. Proper seat height greatly affects pressure points on the legs. If the seat is too high and the legs dangle, the pressure behind the knees can be excessive. If the seat is too low, the weight of the body concentrates on the buttocks, again creating discomfort.