Ergonomics in the Operating Room: The Cervicospinal Health of Today’s Surgeons

SPECIAL TOPIC
Ergonomics in the Operating Room: The
Cervicospinal Health of Today’s Surgeons
Sean M. Fisher, M.D.
Chad M. Teven, M.D.
David H. Song, M.D.,
M.B.A.
Seattle, Wash.; Chicago, Ill.;
and Washington D.C.
Downloaded from http://journals.lww.com/plasreconsurg by BhDMf5ePHKbH4TTImqenVGfKfUq8LcpjQKtsUv+NdvnTrq7SZoeGbnDW+PTfIitL on 10/27/2018
Summary: In its many forms, operating can lead surgeons to adopt postures
that have damaging long-term effects on physical health through imparting
musculoskeletal fatigue. One area that is particularly susceptible is the cervical spine, as surgeons are forced into positions that require sustained cervical
hyperflexion. The repercussions of resultant injuries can be steep, as they have
the potential to adversely affect one’s operative capacity. The purpose of this
article is to assess the spinal health of today’s surgeons by evaluating available
research in various surgical subspecialties. By focusing on the ergonomic principles that govern the surgical arena and identifying unifying themes between
plastic surgery and other surgical subspecialties, it is the goal of this article to
enhance the understanding of cervical spine health as it pertains to the plastic
and reconstructive surgeon. (Plast. Reconstr. Surg. 142: 1380, 2018.)
T
he principles of ergonomics have found considerable use in today’s society through application in industry, the military, and other
fields where physical performance and productivity are closely intertwined.1–4 These industries have
witnessed policies and best-practices change in an
effort to maximize human capital through the
reduction in work-related injuries, performance
errors, and lost productivity. Although health care
is often focused on the well-being of patients, the
physical health of surgeons is also imperative to
maintain given the impact their work efficiency
has on the delivery of operative care.5,6
Musculoskeletal disorders constitute the
most significant cause of work-related illnesses in
the United States,7 and the health care industry
represents an extreme example of this statistic.
Although population studies estimate that musculoskeletal disorders affect between 20 and 30
percent of the general population, select groups
within health care have been found to far exceed
these statistics.7–11 Surgeons are among those individuals most significantly affected, with a variety
of studies focusing on injuries in otolaryngology,
From the Section of Plastic and Reconstructive Surgery, University of Washington Medicine; the Section of Plastic and
Reconstructive Surgery, University of Chicago Medicine;
and the Department of Plastic and Reconstructive Surgery,
MedStar Georgetown University Hospital.
Received for publication November 7, 2017; accepted April
26, 2018.
Copyright © 2018 by the American Society of Plastic Surgeons
DOI: 10.1097/PRS.0000000000004923
1380
minimally invasive surgery, dentistry, and spinal
surgery.5,6,9,11–14
These findings should come as no surprise
given surgeons’ repeated exposure to risk factors associated with musculoskeletal disorders,
such as static and awkward positioning, repetitive
motions, hyperflexion of the cervical spine, and
limited recovery.14–18 These risk factors can manifest in a variety of ways, with the most frequently
affected regions being the neck, shoulders, and
lumbar spine.16,19,20 Although all physical ailments
have the potential to adversely affect surgeons’
performance, cervical spine injuries pose a particular threat given the possibility for progression to
degenerative disk disease with associated cervical
radiculopathy.
To date, there are limited data describing
the frequency or cause of cervical spine injuries
in plastic surgeons.6 A recent report by Khansa
et al. showed that plastic surgeons are at high
risk for work-related musculoskeletal injuries
Disclosure: None of the authors has any commercial
associations or financial relationships that might
create a conflict of interest with the work presented
in this article.
By reading this article, you are entitled to claim
one (1) hour of Category 2 Patient Safety Credit.
ASPS members can claim this credit by logging
in to PlasticSurgery.org Dashboard, clicking
“Submit CME,” and completing the form.
www.PRSJournal.com
Copyright © 2018 American Society of Plastic Surgeons. Unauthorized reproduction of this article is prohibited.
Volume 142, Number 5 • Operating Room Ergonomics
across the body.21 The goal of this review is to
evaluate the intraoperative and biomechanical
principles that contribute to neck injuries, and
to summarize the findings of studies in related
surgical fields so as to direct future research into
this topic as it pertains to the plastic surgeon.
BIOMECHANICS OF THE CERVICAL
SPINE
The cervical spine is composed of four distinct sections that contribute in unique ways to the
overall kinematics of the neck (Fig. 1). The cradle,
composed of the atlas, occiput, and corresponding
Fig. 1. (Above) The cradle allows for articulation between the atlas
and occiput by means of the atlantooccipital joints, permitting flexion and extension of the occiput. (Center) Much of the lateral rotation of the cranium is facilitated through the relationship of the atlas
(C1) and the dens of the axis. (Below) The prominent body of the axis
serves as a kind of root in which the apparatus that moves the head
is securely anchored to the remaining cervical spine. Further architectural differences exist in the zygapophysial joints of this third
functional segment, resulting in medially inclined joints that affect
the overall kinematics.
1381
Copyright © 2018 American Society of Plastic Surgeons. Unauthorized reproduction of this article is prohibited.
Plastic and Reconstructive Surgery • November 2018
atlanto-occipital joints, allows for finite nodding
(i.e., flexion/extension) between the two structures. The axis constitutes the second section,
permitting significant axial rotation of the atlas,
and thus the cranium, about the dens. The root
is composed of the C2-3 junction and, because of
variable architecture, it exhibits kinematic differences in lateral flexion from the remaining cervical spine.22 The column (C3-C7) represents the
final unit, and it allows for significant flexion and
extension, lateral flexion, and axial rotation.22
Given the possibility for triplanar deviation
from neutral positioning, 12 distinct movements
exist for each functional unit of the cervical spine
at any given moment, as it pertains to the axis of
rotation (Fig. 2).17,23 As such, accurate measurements of cervical strain in totality and anatomical
isolation are difficult to quantify intraoperatively.1
However, numerous studies have used both cadaveric and experimental models to demonstrate the
substantial loads placed on a variety of cervical
structures during physiologic range of motion.24–26
Of particular interest to the field of surgery is
the substantial increase in force that is imparted
on cervical structures during varying degrees of
neck flexion. With the head positioned 30 degrees
beyond a neutral position, there is a 4-fold increase
in the weight observed by the cervical spine.27
Clinically, this degree of flexion translates to a relative risk of greater than 2.0 for the development
of neck pain.28 Although this oversimplifies the
Fig. 2. In addition to those movements that occur along translational planes, allowing for forward/backward and left/right
movements, consideration must be given to those movements
that occur about rotational axes. These rotational planes permit
(A) roll, (B) pitch, and (C) and yaw.
complex kinematics at work by neglecting lateral
flexion and rotation, it underscores the considerable effect that deviations from neutral can have
on surrounding tissues.
POSTURE
As a surrogate for these increased forces, there
is now considerable clinical evidence that identifies static posture of the neck and shoulders as a
risk factor for the development of musculoskeletal
disorders of the neck and upper extremities.29–31
Such injuries are frequently observed in industries in which a downward gaze predominates the
working environment, as is the case in the operating room, leading to a sustained forward head
posture.32,33 Such positioning entails flexion of the
lower cervical spine with associated scapular protraction, and although it is difficult to establish a
causal relationship, many individuals suffering
neck-related musculoskeletal disorders exhibit
such postural abnormalities.32,34,35 If left unopposed
over long periods, this maladapted posture imparts
an increased compressive load on surrounding tissues that has the potential to adversely affect various soft-tissue components, bony structures, and
neural elements.36–38 To date, there have been no
studies that evaluate these postural abnormalities
in the context of plastic surgery. However, studies
in operatively comparable fields provide a lens with
which to evaluate the possible correlation between
poor posture and neck injuries in our own field.
Numerous studies in dentistry have noted that
musculoskeletal disorders of the upper extremities,
including neck injuries, account for a large proportion of musculoskeletal injuries in the field.10,13,39–41
With up to 70 percent of dentists reporting some
degree of neck pain, it is believed that the major
contributing factor to these injuries is the roughly
60 percent of working time dentists spend in a
fixed, flexed posture.1,40–42 This is likely the result of
both the intraoral nature of dental procedures and
the frequent use of loupe magnification.
Further evidence for the detrimental effects of
operating has been demonstrated in the field of
oculoplastic surgery, with nearly 60 percent of surgeons reporting neck pain associated with surgery
and 42 percent modifying operating room practices because of symptoms.43 The use of loupes and
headlamps is believed to contribute to these symptoms in oculoplastic surgery, as their use has considerable effect on user posture.44 This sentiment
has been reflected by a recent field study measuring postural data in various operative procedures.
In the group with 50 or more hours of recorded
1382
Copyright © 2018 American Society of Plastic Surgeons. Unauthorized reproduction of this article is prohibited.
Volume 142, Number 5 • Operating Room Ergonomics
operative time, 85 percent of time was spent in
a nonneutral posture with at least 15 degrees of
cervical flexion, and 25 percent of operating
time was spent in an extreme posture with at least
45 degrees of flexion.45,46 In addition, the study
found that participants spent equal amounts of
time with added lateral flexion and rotation ranging from 15 to 45 degrees, thus increasing the
overall strain placed on cervical structures.45,46
Further insight as to the effects of posture on
cervical spine injuries in the field of plastic surgery may be gained by also considering literature
from other surgical subspecialties. Babar-Craig et
al.12 reported a 72 percent prevalence of back and
neck pain among ear, nose, and throat surgeons
in the United Kingdom. The authors noted that
otology demonstrated the highest prevalence in
the field and attributed these findings to the frequency of microscope use. Orthopedic surgeons
have also been found to have high reported rates
of neck and upper extremity symptoms, as Mirbod
et al.47 demonstrated that the prevalence of subjective complaints of the neck and shoulders were
38.9 percent and 31.5 percent, respectively. These
findings were further corroborated by Knudsen et
al.48 who, in addition to noting high rates of neck
and upper extremity pain, found that the overwhelming majority of respondents (84 percent)
felt that the nature of their work contributed to
their symptoms. Similar high rates of neck pain
and discomfort have been reported in the context
of thoracic surgery and urology.47,49,50 A recent
survey of plastic surgeons in the United States,
Canada, and Norway demonstrated a high rate of
musculoskeletal injury in our field, with approximately two-thirds of respondents reporting neck
discomfort related to their occupation.21
THE EFFECT OF EQUIPMENT ON
CERVICAL SPINE INJURIES
Recent developments have revolutionized
ergonomics in the operating room by improving posture, including video-assisted surgery and
intraoperative robotics (e.g., da Vinci Surgical
System; Intuitive Surgical, Inc., Sunnyvale Calif.).
Unfortunately, these technologies are not often
used by plastic surgeons. Of particular interest
to our field is the use of loupes and headlamps.
Because plastic surgeons are among the most
frequent users of these devices, a greater understanding of their impact on posture and cervical
neck health is crucial.51
Loupe magnification has been shown to pose a
serious threat to cervical health, as over 80 percent
of surgeons who use it report neck symptoms.46
This is quantifiably observed by the fact that the
use of loupes increases mean cervical load by 40
percent, at all postures and across all cervical levels.45,46 Although their use is imperative to plastic
surgeons, individuals must be diligent in selecting
proper equipment to minimize prolonged hyperflexion. The most significant factors to consider
when making such a selection are the declination
angle and working distance of the lenses. These
factors play a critical role in maintaining proper
posture while operating, as they contribute to
the overall line of sight of the surgeon.14 Loupes
that have an improper working distance for the
required task and/or a declination angle greater
than 25 degrees predispose surgeons to postures
that may result in associated neck symptoms.14
Nearly 70 percent of plastic surgeons also
endorse using headlamps.43 When considered
together, loupe and headlamp use should raise
concern, as Sahni et al.14 demonstrated that spinal surgeons who frequently used both reported
an increase in the frequency and severity of
neck symptoms. This is the result of the additional moment arm that is imparted on cervical
structures while wearing a headlamp. The added
weight yields concomitant increases in cervical
load at all angles, which may hasten degeneration over time.14 Furthermore, any discrepancy
between the focal length of loupes and that of
the headlamp provide greater opportunity for the
surgeon to assume threatening postures.44 Therefore, the surgeon must be diligent in their selection and judicious in their use to avoid protracted
exposure to harmful postures.
LONGITUDINAL ASSESSMENT
Although biomechanical modeling can provide quantitative insight into the direct forces that
result from time spent in the operating room, it
is not practical for day-to-day use. Rather, it provides a snapshot of operative conditions with
limited ability to temporally assess a surgeon’s
spinal health. Alternatively, radiographic images
or surface landmarks may be of greater value in
such longitudinal assessment, as they can identify
postural changes over time. Although there is not
a clearly defined association between craniocervical posture and neck-related musculoskeletal
disorders, a number of studies have noted significant differences in easily obtained measurements between asymptomatic patients and those
with neck symptoms.52–55 Furthermore, given the
growing sentiment that forward head posture is
1383
Copyright © 2018 American Society of Plastic Surgeons. Unauthorized reproduction of this article is prohibited.
Plastic and Reconstructive Surgery • November 2018
related to both the development and persistence
of a number of disorders, ongoing measurements
of cervical landmarks among surgeons may provide temporal insight into their spinal health.54,56
Radiologic assessment has historically been the
standard for measuring cervical spine position.57–60
Although the practicality of using radiographs
for longitudinal assessment has been questioned
because of ongoing radiation exposure and excessive
cost, there is evidence to suggest that measurements
obtained from such imaging can accurately evaluate
head position.59–61 Using lateral radiographs, the cervical angle (angle between posterior tangent lines
of C2 and C7) can be used to assess the presence
of forward head posture.62,63 In addition, various
horizontal distances (C1 vertebral body to C7 spinous process and ear hole to C7 vertebral body) can
establish the presence of forward head posture.62
Despite the development of low-dose radiography
techniques, the use of landmark measurements
from photographs (i.e., photogrammetry) to assess
cervical posture has gained interest as a safe method
of assessment.59,60 Using these techniques, the craniovertebral angle is commonly tested, as studies
have shown that there is a higher likelihood of neck
symptoms as craniovertebral angle decreases.64,65
Further advantages of these techniques include the
provision of longitudinal information and the ability
to test posture in a manner that is neither disruptive
nor costly. Disadvantages include uncertain intrarater and interrater reliability, calling into question
the accuracy of measurements.58,60,66
the performance of exercise of more than 5 hours/
week and/or 3 or more days/week.43,68 Targeted
exercises that focus on concentric and eccentric
contractions with slow lifting velocity (e.g., front
shoulder raises, lateral shoulder raises, dumbbell
flies, and shoulder shrugs) have also been shown
to reduce neck and shoulder pain.69
Technological advancements are also crucial
to helping curb musculoskeletal disorders of the
neck and upper extremities in surgeons. Of particular relevance to plastic surgeons is the development of deflection prismatic lenses. These lenses
are equipped with a built-in declination angle,
which permits the viewing field to reside at a fixed
angle below a true horizontal line of sight (Fig. 3).
Available commercially since 2007, these
lenses clinically reduce neck and shoulder pain
by minimizing the degree of neck flexion.28,70
Early studies used lenses with a modest declination angle of 4.6 degrees; newer loupes, such
as those from PENTAX (HOYA Technosurgical Company, Tokyo, Japan), are equipped with
prism lenses that demonstrate a declination angle
of 48 degrees (Fig. 3).70
SUMMARY
The field of surgery, regardless of the specialty,
entails placing the well-being of the patient before
one’s own health. Although some degree of physical discomfort is inevitable in such a demanding field, it should not be the expectation that a
career in surgery results in long-term disability.
PREVENTATIVE AND CORRECTIVE
STRATEGIES
With the recognition that there is a strong
association between cervical neck injury and the
performance of plastic surgery,21 it is incumbent
on us to devise strategies that improve and prevent
these injuries within our field. Physical fitness and
frequent exercise are common ways of combating
strenuous working conditions. Both targeted and
general fitness prevent and ameliorate neck injuries
by improving posture and reducing reported symptoms.33,46 Furthermore, forward head posture can
be corrected by stretching foreshortened trapezius,
sternocleidomastoid, and levator scapulae muscles
and by strengthening the deep cervical flexors.10,67
Although alterations in posture may translate
into an overall improvement in spinal health over
time, both targeted and general fitness should also
be emphasized for symptomatic management. Regular exercise directly reduces musculoskeletal disorder symptoms in surgeons, with studies supporting
Fig. 3. Prismatic loupes with deflection lenses permit reduced
neck strain by minimizing the need for cervical neck hyperflexion. This is accomplished as the user’s focal field (black arrow)
resides at a fixed angle below a horizontal line of sight (red
arrow).
1384
Copyright © 2018 American Society of Plastic Surgeons. Unauthorized reproduction of this article is prohibited.
Volume 142, Number 5 • Operating Room Ergonomics
Table 1. Emphasis on Various Technology
Specifications and General Principles in Fitness/
Wellness May Work to Avoid the Onset, and Prevent
the Progression, of Musculoskeletal Disorders in
Various Surgeon Populations
1. Avoid loupes with declination angle that exceeds 25
degrees
2. Consider the weight of frames and length of lenses when
choosing loupes
3. Minimize time spent using headlamps
4. Ensure table height is in accordance with the working
distance of loupes
5. Ensure the working distances of both loupes and headlamps are in accordance with one another
6. Perform frequent neck exercises that target stretching of
the trapezius, sternocleidomastoid, and levator scapulae,
as these are frequently shortened in forward head posture
7. Focus on eccentric/concentric exercises of the shoulders
and neck with an emphasis on slow lifting velocity
8. Attempt to exercise ≥3 times/wk
Deteriorating cervical spine health poses a major
threat to the current surgical community, as a
majority of surgeons report some degree of neck
pain or associated musculoskeletal disorder. To
address the impact of such injuries in the field
of plastic surgery, a greater understanding of the
problem is first needed. In gaining greater insight,
we can begin to create a more user-friendly operative environment that incorporates greater awareness, improved physical training, and ongoing
technologic advances (Table 1).1 Through the
implementation of such improvements, it is our
hope to protect both today’s and tomorrow’s
plastic surgeons from the threat of work-related
injuries.
David H. Song, M.D., M.B.A.
Department of Plastic and Reconstructive Surgery
MedStar Georgetown University Hospital
3800 Reservoir Road NW
Washington, D.C. 20007
REFERENCES
1. Berguer R. Surgery and ergonomics. Arch Surg.
1999;134:1011–1016.
2. Chavalitsakulchai P, Ohkubo T, Shahnavaz H. A model of
ergonomics intervention in industry: Case study in Japan. J
Hum Ergol (Tokyo) 1994;23:7–26.
3. Svensson E, Angelborg-Thanderz M, Sjöberg L. Mission challenge, mental workload and performance in military aviation. Aviat Space Environ Med. 1993;64:985–991.
4. Annett J. The learning of motor skills: Sports science and
ergonomics perspectives. Ergonomics 1994;37:5–16.
5. Davis WT, Sathiyakumar V, Jahangir AA, Obremskey WT,
Sethi MK. Occupational injury among orthopaedic surgeons. J Bone Joint Surg Am. 2013;95:e107.
6. Capone AC, Parikh PM, Gatti ME, Davidson BJ, Davison SP.
Occupational injury in plastic surgeons. Plast Reconstr Surg.
2010;125:1555–1561.
7. Punnett L, Wegman DH. Work-related musculoskeletal
disorders: The epidemiologic evidence and the debate.
J Electromyogr Kinesiol. 2004;14:13–23.
8. Ibrahim NI, Mohanadas D. Prevalence of musculoskeletal
disorders among staffs in specialized healthcare centre. Work
2012;41(Suppl 1):2452–2460.
9. Yu D, Green C, Kasten SJ, Sackllah ME, Armstrong TJ. Effect
of alternative video displays on postures, perceived effort,
and performance during microsurgery skill tasks. Appl Ergon.
2016;53:281–289.
10. Gupta BD, Aggarwal S, Gupta B, Gupta M, Gupta N. Effect of
deep cervical flexor training vs. conventional isometric training on forward head posture, pain, neck disability index in
dentists suffering from chronic neck pain. J Clin Diagn Res.
2013;7:2261–2264.
11. Auerbach JD, Weidner ZD, Milby AH, Diab M, Lonner BS.
Musculoskeletal disorders among spine surgeons: Results of
a survey of the Scoliosis Research Society membership. Spine
(Phila Pa 1976) 2011;36:E1715–E1721.
12. Babar-Craig H, Banfield G, Knight J. Prevalence of back
and neck pain amongst ENT consultants: National survey.
J Laryngol Otol. 2003;117:979–982.
13. Alexopoulos EC, Stathi IC, Charizani F. Prevalence of musculoskeletal disorders in dentists. BMC Musculoskelet Disord.
2004;5:16.
14. Sahni D, James KB, Hipp J, Holloway S, Marco RAW. Is
there an increased incidence of cervical degenerative disease in surgeons who use loupes and a headlight? J Spine
2015;4:256.
15. Rubin DI. Epidemiology and risk factors for spine pain.
Neurol Clin. 2007;25:353–371.
16. Ruitenburg MM, Frings-Dresen MH, Sluiter JK. Physical job
demands and related health complaints among surgeons. Int
Arch Occup Environ Health 2013;86:271–279.
17. Sivak-Callcott JA, Mancinelli CA, Nimbarte AD. Cervical
occupational hazards in ophthalmic plastic surgery. Curr
Opin Ophthalmol. 2015;26:392–398.
18. Larsson B, Søgaard K, Rosendal L. Work related neck-shoulder pain: A review on magnitude, risk factors, biochemical
characteristics, clinical picture and preventive interventions.
Best Pract Res Clin Rheumatol. 2007;21:447–463.
19. Esmaeilzadeh S, Ozcan E, Capan N. Effects of ergonomic
intervention on work-related upper extremity musculoskeletal disorders among computer workers: A randomized controlled trial. Int Arch Occup Environ Health 2014;87:73–83.
20. Soueid A, Oudit D, Thiagarajah S, Laitung G. The pain of
surgery: Pain experienced by surgeons while operating. Int J
Surg. 2010;8:118–120.
21. Khansa I, Khansa L,Westvik TS, Ahmad J, Lista F, Janis JE.
Work-related musculoskeletal injuries in plastic surgeons in
the United States, Canada, and Norway. Plast Reconstr Surg.
2018;141:165e–175e.
22. Bogduk N, Mercer S. Biomechanics of the cervical
spine: I. Normal kinematics. Clin Biomech (Bristol, Avon)
2000;15:633–648.
23. Iorio JA, Jakoi AM, Singla A. Biomechanics of degenerative
spinal disorders. Asian Spine J. 2016;10:377–384.
24. Yoganandan N, Kumaresan S, Pintar FA. Biomechanics of
the cervical spine Part 2. Cervical spine soft tissue responses
and biomechanical modeling. Clin Biomech (Bristol, Avon)
2001;16:1–27.
25. Goel VK, Clausen JD. Prediction of load sharing among spinal components of a C5-C6 motion segment using the finite
element approach. Spine (Phila Pa 1976) 1998;23:684–691.
26. Teo EC, Ng HW. Evaluation of the role of ligaments, facets
and disc nucleus in lower cervical spine under compression
1385
Copyright © 2018 American Society of Plastic Surgeons. Unauthorized reproduction of this article is prohibited.
Plastic and Reconstructive Surgery • November 2018
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
and sagittal moments using finite element method. Med Eng
Phys. 2001;23:155–164.
Hansraj KK. Assessment of stresses in the cervical spine
caused by posture and position of the head. Surg Technol Int.
2014;25:277–279.
Lindegård A, Gustafsson M, Hansson GÅ. Effects of prismatic
glasses including optometric correction on head and neck
kinematics, perceived exertion and comfort during dental
work in the oral cavity: A randomised controlled intervention. Appl Ergon. 2012;43:246–253.
Aarås A, Fostervold KI, Ro O, Thoresen M, Larsen S. Postural
load during VDU work: A comparison between various work
postures. Ergonomics 1997;40:1255–1268.
Schüldt K, Ekholm J, Harms-Ringdahl K, Németh G,
Arborelius UP. Effects of changes in sitting work posture
on static neck and shoulder muscle activity. Ergonomics
1986;29:1525–1537.
Winkel J, Westgaard R. Occupational and individual risk factors
for shoulder-neck complaints: Part II. The scientific basis (literature review) for the guide. Int J Ind Ergon. 1992;10:85–104.
Szeto GP, Straker L, Raine S. A field comparison of neck and
shoulder postures in symptomatic and asymptomatic office
workers. Appl Ergon. 2002;33:75–84.
Ruivo RM, Carita AI, Pezarat-Correia P. The effects of training and detraining after an 8 month resistance and stretching
training program on forward head and protracted shoulder
postures in adolescents: Randomised controlled study. Man
Ther. 2016;21:76–82.
Braun BL, Amundson LR. Quantitative assessment of head
and shoulder posture. Arch Phys Med Rehabil. 1989;70:322–329.
Hanten WP, Lucio RM, Russell JL, Brunt D. Assessment of
total head excursion and resting head posture. Arch Phys Med
Rehabil. 1991;72:877–880.
Moustafa IM, Diab AA. The effect of adding forward head
posture corrective exercises in the management of lumbosacral radiculopathy: A randomized controlled study. J
Manipulative Physiol Ther. 2015;38:167–178.
Harrison DE, Cailliet R, Harrison DD, Troyanovich SJ,
Harrison SO. A review of biomechanics of the central nervous system: Part II. Spinal cord strains from postural loads.
J Manipulative Physiol Ther. 1999;22:322–332.
Ferrara LA. The biomechanics of cervical spondylosis. Adv
Orthop. 2012;2012:493605.
Rafie F, Zamani Jam A, Shahravan A, Raoof M, Eskandarizadeh
A. Prevalence of upper extremity musculoskeletal disorders
in dentists: Symptoms and risk factors. J Environ Public Health
2015;2015:517346.
Lehto TU, Helenius HY, Alaranta HT. Musculoskeletal symptoms of dentists assessed by a multidisciplinary approach.
Community Dent Oral Epidemiol. 1991;19:38–44.
Rundcrantz BL, Johnsson B, Moritz U. Cervical pain and discomfort among dentists: Epidemiological, clinical and therapeutic aspects. Part 1. A survey of pain and discomfort. Swed
Dent J. 1990;14:71–80.
Jonker D, Rolander B, Balogh I. Relation between perceived
and measured workload obtained by long-term inclinometry
among dentists. Appl Ergon. 2009;40:309–315.
Sivak-Callcott JA, Diaz SR, Ducatman AM, Rosen CL,
Nimbarte AD, Sedgeman JA. A survey study of occupational
pain and injury in ophthalmic plastic surgeons. Ophthalmic
Plast Reconstr Surg. 2011;27:28–32.
Rohrich RJ. Why I hate the headlight: And other ways to protect
your cervical spine. Plast Reconstr Surg. 2001;107:1037–1038.
Nimbarte AD, Sivak-Callcott JA, Zreiqat M, Chapman M. Neck
postures and cervical spine loading among microsurgeons
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
61.
62.
63.
operating with loupes and headlamp. IIE Trans Occup Ergon
Hum Factors 2013;1:215–223.
Nimbarte AD, Zreiqat M, Chapman M, Sivak-Callcott JA.
Physical risk factors for neck pain among oculoplastic surgeons. Paper presented at: 62nd Annual Conference and
Expo of the Institute of Industrial Engineers; May 19–23,
2012; Orlando, Fla.
Mirbod SM, Yoshida H, Miyamoto K, Miyashita K, Inaba R,
Iwata H. Subjective complaints in orthopedists and general
surgeons. Int Arch Occup Environ Health 1995;67:179–186.
Knudsen ML, Ludewig PM, Braman JP. Musculoskeletal pain
in resident orthopaedic surgeons: Results of a novel survey.
Iowa Orthop J. 2014;34:190–196.
Welcker K, Kesieme EB, Internullo E, Kranenburg van
Koppen LJ. Ergonomics in thoracoscopic surgery: Results of
a survey among thoracic surgeons. Interact Cardiovasc Thorac
Surg. 2012;15:197–200.
Wolf JS Jr, Marcovich R, Gill IS, et al. Survey of neuromuscular injuries to the patient and surgeon during urologic laparoscopic surgery. Urology 2000;55:831–836.
Jarrett PM. Intraoperative magnification: Who uses it?
Microsurgery 2004;24:420–422.
Yip CH, Chiu TT, Poon AT. The relationship between head
posture and severity and disability of patients with neck pain.
Man Ther. 2008;13:148–154.
Cheung CH, Shum ST, Tang SF, Yau PC, Chiu TT. The correlation between craniovertebral angle, backpack weights, and
disability due to neck pain in adolescents. J Back Musculoskelet
Rehabil. 2010;23:129–136.
López-de-Uralde-Villanueva I, Beltran-Alacreu H, ParisAlemany A, Angulo-Díaz-Parreño S, La Touche R.
Relationships between craniocervical posture and painrelated disability in patients with cervico-craniofacial pain. J
Pain Res. 2015;8:449–458.
Lau KT, Cheung KY, Chan KB, Chan MH, Lo KY, Chiu TT.
Relationships between sagittal postures of thoracic and cervical spine, presence of neck pain, neck pain severity and
disability. Man Ther. 2010;15:457–462.
Silva AG, Punt TD, Johnson MI. Reliability and validity of
head posture assessment by observation and a four-category
scale. Man Ther. 2010;15:490–495.
Harrison DE, Haas JW, Cailliet R, Harrison DD, Holland B,
Janik TJ. Concurrent validity of flexicurve instrument measurements: Sagittal skin contour of the cervical spine compared with lateral cervical radiographic measurements. J
Manipulative Physiol Ther. 2005;28:597–603.
van Niekerk SM, Louw Q, Vaughan C, Grimmer-Somers K,
Schreve K. Photographic measurement of upper-body sitting posture of high school students: A reliability and validity
study. BMC Musculoskelet Disord. 2008;9:113.
Grimmer-Somers K, Milanese S, Louw Q. Measurement of
cervical posture in the sagittal plane. J Manipulative Physiol
Ther. 2008;31:509–517.
Gadotti IC, Armijo-Olivo S, Silveira A, Magee D. Reliability
of the craniocervical posture assessment: Visual and angular measurements using photographs and radiographs. J
Manipulative Physiol Ther. 2013;36:619–625.
Chen YL, Lee YH. A non-invasive protocol for the determination of lumbosacral vertebral angle. Clin Biomech (Bristol,
Avon) 1997;12:185–189.
Sun A, Yeo HG, Kim TU, Hyun JK, Kim JY. Radiologic assessment of forward head posture and its relation to myofascial
pain syndrome. Ann Rehabil Med. 2014;38:821–826.
Harrison DE, Harrison DD, Cailliet R, Troyanovich SJ, Janik
TJ, Holland B. Cobb method or Harrison posterior tangent
1386
Copyright © 2018 American Society of Plastic Surgeons. Unauthorized reproduction of this article is prohibited.
Volume 142, Number 5 • Operating Room Ergonomics
64.
65.
66.
67.
method: Which to choose for lateral cervical radiographic
analysis. Spine (Phila Pa 1976) 2000;25:2072–2078.
Watson DH, Trott PH. Cervical headache: An investigation
of natural head posture and upper cervical flexor muscle
performance. Cephalalgia 1993;13:272–284; discussion 232.
Grimmer KA, Williams MT, Gill TK. The associations between
adolescent head-on-neck posture, backpack weight, and anthropometric features. Spine (Phila Pa 1976) 1999;24:2262–2267.
Ruivo RM, Pezarat-Correia P, Carita AI. Intrarater and interrater reliability of photographic measurement of upper-body
standing posture of adolescents. J Manipulative Physiol Ther.
2015;38:74–80.
Lynch SS, Thigpen CA, Mihalik JP, Prentice WE, Padua D.
The effects of an exercise intervention on forward head and
rounded shoulder postures in elite swimmers. Br J Sports Med.
2010;44:376–381.
68. Kitzmann AS, Fethke NB, Baratz KH, Zimmerman MB,
Hackbarth DJ, Gehrs KM. A survey study of musculoskeletal
disorders among eye care physicians compared with family
medicine physicians. Ophthalmology 2012;119:213–220.
69. Zebis MK, Andersen LL, Pedersen MT, et al. Implementation
of neck/shoulder exercises for pain relief among industrial
workers: A randomized controlled trial. BMC Musculoskelet
Disord. 2011;12:205.
70. Lindegård A, Nordander C, Jacobsson H, Arvidsson I. Opting
to wear prismatic spectacles was associated with reduced
neck pain in dental personnel: A longitudinal cohort study.
BMC Musculoskelet Disord. 2016;17:347.
1387
Copyright © 2018 American Society of Plastic Surgeons. Unauthorized reproduction of this article is prohibited.