Abstract
Background
The physical demands and high rates of musculoskeletal injury among practicing orthopaedic surgeons have been previously recognized in the literature. However, there is a paucity of data regarding musculoskeletal symptoms among resident orthopaedic surgeons. We sought to answer the following questions: (1) are there significant levels of musculoskeletal symptoms among resident orthopaedic surgeons?; (2) do residents attribute these symptoms to their work as surgeons?; and (3) is our survey instrument reliable enough for use in future investigations?
Methods
We developed an online, cross-sectional survey based on the previously validated Nordic Musculoskeletal Questionnaire and distributed it to 39 resident orthopaedic surgeons at our institution in 2011, with 82% responding. Fifteen participants repeated the survey to assess agreement and reliability between repeated administrations of the survey.
Results
Significant levels of musculoskeletal symptoms were found in the resident surgeons, with the most common self-reported symptoms reported in the neck (59%), lower back (55%), upper back (35%), and shoulders (34%). Large proportions of these symptoms were self-reportedly attributed to the residents' work as a surgeon. Intrarater reliability revealed moderate to almost perfect agreement in nearly all repeated survey items.
Conclusions
Given that there are similar rates of musculoskeletal symptoms among our resident orthopedists and practicing orthopedists, more attention needs to be paid to the ergonomic and physical environments in which we are training the next generation of surgeons, especially when considering the extensive societal investment in training for these specialists.
Introduction
Orthopaedic surgeons are exposed to a particularly hazardous day-to-day working environment with risks of exposure to infection, radiation, smoke, chemicals, excessive noise, emotional and physiological disturbances, and musculoskeletal injuries1. When the primary focus is appropriately placed on the patient, it is easy to overlook these very real physical threats. In 1995, Mirbod found higher rates of subjective physical injuries in orthopedists as compared to general surgeons, with the most commonly injured areas reported as the back, neck, shoulders, arms, and hands2. In 2011, Auerbach and colleagues conducted a survey of spine surgeons and reported a similarly high incidence of low-back, neck, shoulder, wrist, and hand pain3. Additionally, Auerbach found that the incidence of cervical and lumbar disk herniation with radiculopathy, lateral epicondylitis, and carpal tunnel syndrome was higher in those surveyed than in the general population3. Barbar-Craig and colleagues found that 72% of Ear Nose and Throat (ENT) surgeons in the United Kindom (UK) have either back pain or neck pain and that 53% attributed their symptoms directly to their work as a surgeon4. The literature has also found a high prevalence of back and neck pain among ophthalmologists; Sivak-Callcott5 identified that the use of loupes and headlamps were potentially contributing sources of pain5-7. A 2004 survey conducted by Esser and colleagues found 16 of 17 Mayo Clinic surgeons performing Mohs surgery had musculoskeletal symptoms caused by or made worse by performing surgery, with the most common complaints being stiffness in the neck, shoulders, and lower back8.
Orthopaedic surgeons spend much of their working hours in ergonomically challenging postures9. These awkward postures have been identified as risk factors for musculoskeletal injury in the dental profession10,11. Similar flexed neck and elevated arm positions are required to perform surgery, with additional extremes of motion, contorted body positioning, and prolonged standing seen in surgeons. Given the extensive societal investment in medical school, residency, and fellowship training, the societal costs for injury to surgeons is immense. Despite this, to date, there is a paucity of data on the rates of musculoskeletal symptoms among resident orthopaedic surgeons. Furthermore no reliable means to assess and track these data exists. This is required in order to plan or follow the results of ergonomic education programs.
We sought to answer the following questions: (1) are there significant levels of musculoskeletal symptoms among resident orthopaedic surgeons?; (2) do residents attribute these symptoms to their work as surgeons?; and (3) is our survey instrument reliable enough for use in future investigations?
Methods
Subjects
As a sample of convenience, the study population consisted of all 39 orthopaedic surgery residents at our institution for the 2011-2012 academic year.
Questionnaire
This study was approved for committee review exemption by our Institutional Review Board (IRB). We developed an online, web-based, cross-sectional survey adapted from the previously validated Nordic Musculoskeletal Questionnaire12 (NMQ)using an online survey generator. The survey included two main sections: demographics and symptoms by body part as guided by the NMQ and figure (Figure 1). The first page of the survey was an informed consent page, as required by our IRB. Demographics collected included gender, age, height, weight, postgraduate year, average hours in the operating room per week, handedness, most commonly used eyewear, and most commonly employed operating position.
Figure 1. The Nordic Musculoskeletal Questionnaire figure used in the online survey to guide symptom questions12. Figure used with permission.
The symptom portion of the questionnaire inquired about the nine different anatomic regions used in the NMQ: neck, shoulders, elbows, wrists/hands, upper back, lower back, hips/thighs, knees and ankles/feet12. The survey skipped to the next region if a respondent indicated no issues with a particular body region. If they answered positively, however, further questions followed. These included questions about interference with work over the last year, difficulties over the last week, and characterization of the difficulty (pain, stiffness, weakness, paresthesia, or other), severity (mild, moderate, or severe), whether the symptoms stopped the resident from operating, and whether the resident attributed their symptoms to their work as a surgeon. The first three questions for each anatomic region were directly used from the N
NMQ12. This study was conducted electronically between October 2011 and January 2012, with a total of three contacts (two reminders) made resulting in an 82% response rate (32 of 39 residents responding). Additionally, the online survey was able to track the amount of time required to complete the survey. Of note, one participant did not finish the entire survey and stopped after the elbow line of questioning. Seeing as this participant completed the demographics section and provided valid responses for the first three anatomic regions (neck, shoulders, and elbows) the decision was made to keep his data and calculate all survey percentages as valid percentages, that is, the percentage of participants who completed each question.
Agreement analysis
Fifteen volunteer participants repeated the survey approximately four weeks later to assess agreement and reliability between repeated administrations of the survey. The kappa statistic (k) was chosen to analyze test-retest agreement between repeated administrations of the survey13. The percent observed agreement between repeated survey items (P0) and the kappa statistic (k) were calculated for each survey item. The statistics were then stratified and compiled by question type and reported for each type of question.
Results
The characteristics and demographic data of our study population are summarized in Table 1. The results of the survey were stratified and are shown in Table 2 as the number and valid percentage of participants responding positively (valid percentage excludes non-issued questions given the streamlined nature of the survey). The prevalence rates by anatomic region for the group are demonstrated in Figure 2. The most common symptoms were in the neck (59%, 19/32), lower back (55%, 17/31), upper back (35%, 11/31), and shoulders (34%, 11/32). The most common complaints were characterized as pain and stiffness in the neck and lower back, followed closely by pain and stiffness in the upper back and shoulders. The valid percentages of symptom characterization by anatomic region are displayed in Table 1. Other symptoms from free text responses included: “aching” and “swelling”. The impact on work was found to be quite variable among subjective complaints and is displayed in Table 2. Overall, 4/39 residents indicated that they have had to stop operating because of neck (2), hand (1), or thigh (1) difficulties. Lastly, the symptom severity was predominantly reported as mild with increasingly reported moderate symptoms lower in the body with highest rates of moderate symptoms in the knees, hips/ thighs, and ankles/feet.
Table 1.
Subject Characteristics
| Number of Participants | 32 |
| Men | 24 |
| Women | 8 |
| Age (years) | 29.5 ± 2.5 |
| Year in residency | 2.9 ± 1.5 |
| Height (inches) | 70.1 ± 3.6 |
| Weight (pounds) | 170.8 ± 31.7 |
| BMI | 24.3 ± 3.3 |
| Time spent operating per week (hours) | 33.8 ± 17.0 |
| Operating Position | |
| Standing | 32 |
| Sitting | 0 |
| Corrective eyewear/magnification | |
| None | 15 |
| Glasses | 5 |
| Contacts | 10 |
| Loupes | 2 |
| Dominant Hand | |
| Right | 32 |
| Left | 0 |
| Time taken to complete survey | 00:04:44 ± 00:02:40 |
| [Data are reported as number or mean ± SD] | |
Table 2.
Symptom Data Generated from Survey Responses
| Anatomic Region | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Question | Neck n (valid %) | Shoulders n (valid %) | Elbows n (valid %) | Wrists/Hands n (valid %) | Upper Back n (valid %) | Lower Back n (valid %) | Hips/Thighs n (valid %) | Knees n (valid %) | Ankles/Feet n (valid %) |
| Have you at any time during the last 12 months had trouble (ache, pain, discomfort) in your…? | 19 (59.4) | 11 (34.4) | 1 (3.1) | 6 (19.4) | 11 (35.5) | 17 (54.8) | 3 (9.7) | 7 (22.6) | 7 (22.6) |
| Have you at any time during the last 12 months been prevented from doing your normal work (at home or away from home) because of your symptoms? | 3 (15.8) | 1 (9.1) | 1 (16.7) | 2 (18.2) | 2 (11.8) | 1 (33.3) | 1 (14.3) | ||
| Have you had trouble at any time during the last 7 days? | 8 (42.1) | 7 (63.6) | 1 (100) | 5 (45.5) | 6 (35.3) | 3 (100.0) | 5 (71.4) | 5 (71.4) | |
| Symptom characterization: | |||||||||
| Pain | 15 (78.9) | 10 (90.9) | 6 (100.0) | 10 (90.9) | 13 (76.5) | 2 (66.7) | 7 (100.0) | 5 (71.4) | |
| Stiffness | 14 (73.7) | 6 (54.5) | 2 (33.3) | 8 (72.7) | 10 (58.5) | 1 (33.3) | 2 (28.6) | 1 (14.3) | |
| Weakness | 1 (5.3) | 1 (9.1) | 2 (33.3) | 1 (14.3) | |||||
| Paresthesia | 1 (100) | 1 (5.9) | 1 (14.3) | ||||||
| Other | 1 (5.9) | 2 (28.6) | |||||||
| Symptom severity: | |||||||||
| Mild | 15 (78.9) | 9 (81.8) | 1 (100) | 5 (83.3) | 9 (81.8) | 13 (76.5) | 2 (66.7) | 4 (57.1) | 5 (71.4) |
| Moderate | 3 (15.8) | 2 (18.2) | 1 (16.7) | 2 (18.2) | 4 (23.5) | 1 (33.3) | 3 (42.9) | 2 (28.6) | |
| Severe | 1 (5.3) | ||||||||
| Have you ever had to stop operating as a result of your symptoms? | 2 (10.5) | 1 (16.7) | 1 (33.3) | ||||||
| Have you ever lost time from work due to symptoms? | 1 (5.3) | 1 (33.3) | |||||||
| Time lost (in days): | 1 | 14 | |||||||
| Do you attribute your symptoms to your work as a surgeon? | |||||||||
| Yes | 16 (84.2) | 7 (63.6) | 3 (50.0) | 10 (90.9) | 6 (35.3) | 2 (28.6) | 7 (100.0) | ||
| No | 1 (5.3) | 3 (27.3) | 1 (100) | 3 (50.0) | 1 (9.1) | 10 (58.8) | 3 (100.0) | 3 (42.9) | |
| Unsure | 2 (10.5) | 1 (9.1) | 1 (5.9) | 2 (28.6) | |||||
Figure 2. The figure demonstrates the prevalence of subjective complaints reported as percentage prevalence by anatomic region.
Of the subjective complaints, large proportions of these symptoms were attributed by the residents to their work as a surgeon, with 84% of neck, 91% of upper back, 35% of lower back, and 64% of shoulder symptoms being attributed to their work (Figure 3). For those that were unsure, free text responses included: “my work as a surgeon contributes, but may not be the only thing,” “not enough time in surgery to correlate my pain directly with surgery,” “I get stiff while standing in one place for an extended period of time with lead on,” and “not as an initial cause, but work does aggravate my previous injury.”
Figure 3. The figure demonstrates the survey responses to: ‘Do you attribute your symptoms to your work as a surgeon?’ Reported as valid percentages by anatomic region (percent of those reporting symptoms).
The calculated kappa statistic for each repeated type of survey question was positive, indicating the presence of agreement between repeated administrations of the survey across all compiled question types. Using the benchmarks proposed by Landis and Koch14, moderate to almost perfect agreement (k > 0.4) was shown in nearly all repeated survey items (Table 3). The only compiled values that were calculated to show poor to fair agreement (k < 0.4) were: have you had trouble at any time during the last seven days and in characterizing symptoms as pain. Kappa values were undefined for two of the compiled questions due to an initial prevalence or retest prevalence of zero.
Table 3.
Test-Retest Reliability Data Generated from Repeated Survey Administration
| Anatomic Region | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Question | Neck κ (Po) | Shoulders κ (Po) | Elbows κ (Po) | Wrists/Hands κ (Po) | Upper Back κ (Po) | Lower Back κ (Po) | Hips/Thighs κ (Po) | Knees κ (Po) | Ankles/Feet κ (Po) | Compiled † κ (Po) |
| Have you at any time during the last 12 months had trouble (ache, pain, discomfort) in your…? | 0.842 (0.933) |
0.602 (0.800) |
1.0 (1.0) | 0.815 (0.933) |
0.842 (0.933) |
0.737 (0.867) |
1.0 (1.0) | 1.0 (1.0) | 0.634 (0.933) |
0.839 (0.933) |
| Have you at any time during the last 12 months been prevented from doing your normal work (at home or away from home) because of your symptoms? | * (0.900) | 1.0 (1.0) | 0.400 (0.667) |
1.0 (1.0) | * (0.857) | 1.0 (1.0) | 1.0 (1.0) | 1.0 (1.0) | 0.618 (0.914) |
|
| Have you had trouble at any time during the last 7 days? | 0.194 (0.500) |
0.333 (0.667) |
0.400 (0.667) |
* (0.75) | -0.077(0.429) | 1.0 (1.0) | -0.800 (0) |
* (0) | 0.007 (0.514) |
|
| Symptom characterization: | ||||||||||
| Pain | * (0.800) | 1.0 (1.0) | 1.0 (1.0) | * (0.75) | 1.0 (1.0) | 1.0 (1.0) | 1.0 (1.0) | 1.0 (1.0) | 0.356 (0.914) |
|
| Stiffness | * (0.800) | 0.250 (0.667) |
* (0.333) | 1.0 (1.0) | 1.0 (1.0) | 1.0 (1.0) | 0.400 (0.667) |
1.0 (1.0) | 0.595 (0.800) |
|
| Weakness | * (0.800) | * (0.833) | 1.0 (1.0) | 1.0 (1.0) | * (0.857) | 1.0 (1.0) | * (0.667) | 1.0 (1.0) | * (0.886) | |
| Paresthesia | 1.0 (1.0) | 1.0 (1.0) | 0.400 (0.667) |
1.0 (1.0) | * (0.857) | 1.0 (1.0) | 1.0 (1.0) | 1.0 (1.0) | 0.635 (0.943) |
|
| Other | * (0.9) | 1.0 (1.0) | 1.0 (1.0) | 1.0 (1.0) | 1.0 (1.0) | 1.0 (1.0) | 1.0 (1.0) | 1.0 (1.0) | * (0.971) | |
| Symptom severity (mild vs. moderate vs. severe) | 0.348 (0.700) |
0 (0.5) | 1.0 (1.0) | 0.500 (0.75) |
0.696 (0.857) |
1.0 (1.0) | 0.400 (0.667) |
1.0 (1.0) | 0.460 (0.743) |
|
| Have you ever had to stop operating as a result of your symptoms? | 1.0 (1.0) | * (0.833) | 1.0 (1.0) | 1.0 (1.0) | 1.0 (1.0) | 1.0 (1.0) | 1.0 (1.0) | 1.0 (1.0) | 0.785 (0.971) |
|
| Have you ever lost time from work due to symptoms? | 1.0 (1.0) | 1.0 (1.0) | 1.0 (1.0) | 1.0 (1.0) | 1.0 (1.0) | 1.0 (1.0) | 1.0 (1.0) | 1.0 (1.0) | 1.0 (1.0) | |
| Do you attribute your symptoms to your work as a surgeon? (yes vs. no vs. unsure) | 0.615 (0.800) |
0.739 (0.833) |
1.0 (1.0) | 0.500 (0.75) |
* (0.571) | 1.0 (1.0) | 0.400 (0.667) |
1.0 (1.0) | 0.651 (0.771) |
|
Kappa statistic (measure of test-retest agreement between repeated administrations of the survey). Po Percent observed agreement between repeated administrations of the survey.
Compiled statistics across anatomic regions by question type.
Kappa statistic undefined due to an initial prevalence or retest prevalence of zero.
Discussion
The physical demands and high rates of musculoskeletal injury among practicing orthopaedic surgeons have been previously recognized in the literature1-3. This study identifies that musculoskeletal symptoms are similarly high in resident orthopaedic surgeons and that these symptoms were primarily attributed by the subjects to their work as a surgeon. In addition, this study identifies this survey instrument to be reliable for potential use in future investigations. The items with less than acceptable agreement were those where true change would be expected over the timeframe of retesting.
The study has several limitations. First, our sample may not be representative of other residency programs. Our study contains a relatively small sample size of 39 residents at one institution. While small, the high participation rate in this study (82%) reduces bias toward response by only those experiencing symptoms. Another limitation is the self-reported nature of the data which is consistent with all surveys. While subjective reports are not alone diagnostic of musculoskeletal pathology, subjective complaints remain the most common manifestation of musculoskeletal occupational injury. Occupational research has commonly used the prevalence of subjective symptoms to assess musculoskeletal disorders within a given population.
Significant levels of musculoskeletal symptoms were found in our resident surgeons, with the most frequently encountered symptoms reported in the lower back (54.8%), neck (59.4%), shoulders (34.4%), and upper back (35.5%). Furthermore, our survey results are comparable to previously documented rates of musculoskeletal complaints in similar populations. Mirbod reported the prevalence of subjective complaints among practicing orthopedists highest in the lower back (50.0%), neck (38.9%), shoulders (31.5%), and upper back (24.1%)2. Auerbach found similar rates in practicing spine surgeons: lower back (62.2%), neck (59.4%), and shoulders (48.5%)3. Given that our study population are in the very early stages of their careers and are relatively young, these reportedly high rates of musculoskeletal pain are a concerning finding.
The residents attributed a large proportion of their somatic findings to their work as a surgeon. Specifically, 84% of neck, 91% of upper back, 35% of lower back, and 64% of shoulder symptoms were directly attributed to their work. Comparatively, Barbar-Craig and colleagues found that 53% of ENT surgeons in the UK attributed their back and neck pain symptoms directly to their work as a surgeon4. Our survey also looked at the impact that these symptoms have had on the normal work of our residents and on their ability to operate. Even in this relatively young cohort, over 10% of our respondents had missed time in the operating room because of their musculoskeletal difficulties. This raises concern about the long-term consequences of these early symptoms.
Our survey is a reliable instrument to gauge the prevalence of musculoskeletal complaints among surgeons. It is based on a previously validated survey and is adapted into an easy to use, and streamlined, online format. The only items from our survey that had poor to fair agreement between repeated administrations of the survey were items that one would expect to fluctuate over the course of a four-week period of time (i.e., findings in the last seven days). Furthermore, the survey takes less than five minutes on average to complete, which is acceptable for the busy life of a surgeon.
While there are various physical stresses and hazards applied to physicians in general, orthopaedic surgery is one of the most physically taxing of the medical specialties. Prolonged working hours in ergonomically challenging postures have been identified as risk factors in other professions10,11. The high prevalence of musculoskeletal complaints among our residents could also be due to poor ergonomics in the operating room. While it is hopeful that as these residents advance in their careers they will learn how to operate with more appropriate body positions and to perform their tasks more ergonomically, earlier education in orthopaedic ergonomics may reduce these rates and limit lifetime exposure to hazardous body positions. The general surgery literature is replete with evidence acknowledging that laparoscopic surgery is associated with higher rates of pain and musculoskeletal disorders15-20. Nguyen and colleagues16 attributed their findings of pain with laparoscopic surgery to the static positions of the neck and trunk and associated frequent movements of the upper extremities. Arthroscopic surgery is no different in this regard, with the additional physical burden of maintaining proper patient extremity position throughout the operation. The intense psychological and emotional challenges of surgical training, coupled with the focus on the safety and health of the patient, and a lack of education regarding surgical ergonomics creates an environment that may contribute to these high rates of body pain.
Our data show that there is a similar incidence of body pain in trainees as in practicing orthopaedic surgeons despite the younger age of trainees. Consequently, we believe more attention needs to be paid to the ergonomic and physical environments in which we are training surgeons, especially when considering the extensive societal investment in medical, residency, and fellowship training for these specialists. The ideal time to foster a knowledge and awareness of ergonomics with a focus on the prevention of musculoskeletal injury is in residency. We believe training programs should work towards the adoption of ergonomic education programs in an effort to reduce occupational musculoskeletal injuries. Our survey can be used as a tool to monitor the progress of implemented ergonomics programs and to help decide which of the implemented measures are most beneficial for our future surgeons. Furthermore, programs should be encouraged to track progress objectively, by means of a survey such as ours or by other means to ensure that the changes being made can be defended by evidence.
Conflict of Interest Statement
One or more of the authors (PML) has received funding from the Journal of Orthopaedic & Sports Physical Therapy for their work as an Associate Editor Honorarium. One or more of the authors (JPB) has received funding from the Journal of Bone and Joint Surgery for their work as an Associate Editor for the JBJS Shoulder and Elbow Newsletter. The institution of one or more of the authors (PML) has active and pending grants from the National Institutes of Health and the Minnesota Medical Foundation for unrelated works.
Ethical Review Committee Statement
As a symptom survey, this study was approved for committee review exemption by the University of Minnesota Institutional Review Board.
References
- 1.Lester JD, Hsu S, Ahmad CS. Occupational hazards facing orthopedic surgeons. Am J Orthop. 2012;41(3):132–139. [PubMed] [Google Scholar]
- 2.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(3):179–186. doi: 10.1007/BF00626350. [DOI] [PubMed] [Google Scholar]
- 3.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. 2011;36(26):1715–1721. doi: 10.1097/BRS.0b013e31821cd140. [DOI] [PubMed] [Google Scholar]
- 4.Barbar-Craig H, Banfield G, Knight J. Prevalence of back and neck pain amongst ENT consultants: national survey. J Laryngol Otol. 2003;117(12):979–982. doi: 10.1258/002221503322683885. [DOI] [PubMed] [Google Scholar]
- 5.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. Ophthal Plast Reconstr Surg. 2011;27(1):28–32. doi: 10.1097/IOP.0b013e3181e99cc8. [DOI] [PubMed] [Google Scholar]
- 6.Chatterjee A, Ryan WG, Rosen ES. Back pain in ophthalmologists. Eye. 1994;8(Pt 4):473–474. doi: 10.1038/eye.1994.112. [DOI] [PubMed] [Google Scholar]
- 7.Dhimitri KC, McGwin G Jr, McNeal SF, Lee P, Morse PA, Patterson M, Wertz FD, Marx JL. Symptoms of musculoskeletal disorders in ophthl- mologists. Am J Ophthalmol. 2005;139(1):179–181. doi: 10.1016/j.ajo.2004.06.091. [DOI] [PubMed] [Google Scholar]
- 8.Esser AC, Koshy JG, Randle HW. Ergonomics in office-based surgery: a survey-guided observational study. Dermatol Surg. 2007;33(11):1304–1314. doi: 10.1111/j.1524-4725.2007.33281.x. [DOI] [PubMed] [Google Scholar]
- 9.Kant IJ, de Jong LC, van Rijssen-Moll M, Borm PJ. A survey of static and dynamic work postures of operating room staff. Int Arch Occup Environ Health. 1992;63(6):423–428. doi: 10.1007/BF00386939. [DOI] [PubMed] [Google Scholar]
- 10.Alexopoulos EC, Stathi IC, Charizani F. Prevalence of musculoskeletal disorders in dentists. BMC Musculoskeletal Disord. 2004;5:16. doi: 10.1186/1471-2474-5-16. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Burke FJ, Main JR, Freeman R. The practice of dentistry: an assessment of reasons for premature retirement. Br Dent J. 1997;182(7):250–254. doi: 10.1038/sj.bdj.4809361. [DOI] [PubMed] [Google Scholar]
- 12.Kuorinka I, Jonsson B, Kilbom A, Vinterberg H, Biering-Sørensen F, Andersson G, Jørgensen K. Standardised Nordic questionnaires for the analysis of musculoskeletal symptoms. Appl Ergon. 1987;18(3):233–237. doi: 10.1016/0003-6870(87)90010-x. [DOI] [PubMed] [Google Scholar]
- 13.Hoehler FK. Bias and prevalence effects on kappa viewed in terms of sensitivity and specificity. J Clin Epidemiol. 2000;53(5):499–503. doi: 10.1016/s0895-4356(99)00174-2. [DOI] [PubMed] [Google Scholar]
- 14.Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics. 1977;33(1):159–174. [PubMed] [Google Scholar]
- 15.Berguer R, Forkey DL, Smith WD. Ergonomic problems associated with laparoscopic surgery. Surg Endosc. 1999;13(5):466–468. doi: 10.1007/pl00009635. [DOI] [PubMed] [Google Scholar]
- 16.Berguer R, Rab GT, Abu-Ghaida H, Alarcon A, Chung J. A comparison of surgeons' posture during laparoscopic and open surgical procedures. Surg Endosc. 1997;11(2):139–142. doi: 10.1007/s004649900316. [DOI] [PubMed] [Google Scholar]
- 17.Nguyen NT, Ho HS, Smith WD, Philipps C, Lewis C, De Vera RM, Berguer R. An ergonomic evaluation of surgeons' axial skeletal and upper extremity movements during laparoscopic and open surgery. Am J Surg. 2001;182(6):720–724. doi: 10.1016/s0002-9610(01)00801-7. [DOI] [PubMed] [Google Scholar]
- 18.Park A, Lee G, Seagull FJ, Meenaghan N, Dexter D. Patients benefit while surgeons suffer: an impending epidemic. J Am Coll Surg. 2010;210(3):306–313. doi: 10.1016/j.jamcollsurg.2009.10.017. [DOI] [PubMed] [Google Scholar]
- 19.Stomberg MW, Tronstad SE, Hedberg K, Bengtsson J, Jonsson P, Johansen L, Lindvall B. Work-related musculoskeletal disorders when performing laparoscopic surgery. Surg Laparosc Endosc Percutan Tech. 2010;20(1):49–53. doi: 10.1097/SLE.0b013e3181cded54. [DOI] [PubMed] [Google Scholar]
- 20.van Veelen MA, Kazemier G, Koopman J, Goossens RH, Meijer DW. Assessment of the ergonomically optimal operating surface height for laparoscopic surgery. J Laparoendosc Adv Surg Tech A. 2002;12(1):47–52. doi: 10.1089/109264202753486920. [DOI] [PubMed] [Google Scholar]