Abstract
Aims
Body exhaust suits or surgical helmet systems (colloquially, ‘space suits’) are frequently used in many forms of arthroplasty, with the aim of providing personal protection to surgeons and, perhaps, reducing periprosthetic joint infections, although this has not consistently been borne out in systematic reviews and registry studies. To date, no large-scale study has investigated whether this is applicable to shoulder arthroplasty. We used the New Zealand Joint Registry to assess whether the use of surgical helmet systems was associated with lower all-cause revision or revision for deep infection in primary shoulder arthroplasties.
Methods
We analyzed 16,000 shoulder arthroplasties (hemiarthroplasties, anatomical, and reverse geometry prostheses) recorded on the New Zealand Joint Registry from its inception in 2000 to the present day. We assessed patient factors including age, BMI, sex, and American Society of Anesthesiologists (ASA) grade, as well as whether or not the operation took place in a laminar flow operating theatre.
Results
A total of 2,728 operations (17%) took place using surgical helmet systems. Patient cohorts were broadly similar in terms of indication for surgery (osteoarthritis, rheumatoid arthritis, fractures) and medical comorbidities (age and sex). There were 842 revisions (5% of cases) with just 98 for deep infection (0.6% of all cases or 11.6% of the revisions). There were no differences in all-cause revisions or revision for deep infection between the surgical helmet systems and conventional gowns (p = 0.893 and p = 0.911, respectively).
Conclusion
We found no evidence that wearing a surgical helmet system reduces the incidence of periprosthetic joint infection in any kind of primary shoulder arthroplasty. We acknowledge the limitations of this registry study and accept that there may be other benefits in terms of personal protection, comfort, or visibility. However, given their financial and ecological footprint, they should be used judiciously in shoulder surgery.
Cite this article: Bone Jt Open 2024;5(10):894–897.
Take home message
There is currently insufficient evidence to recommend the routine use of surgical helmet systems (‘space suits’) in primary shoulder arthroplasty as a means of reducing deep infection.
Introduction
The role of body exhaust systems (BES), now known as surgical helmet systems (SHS), or colloquially, ‘space suits’, in the reduction of periprosthetic joint infections (PJI) is controversial.
Sir John Charnley pioneered BES as part of his strategy to reduce contamination in the operating theatre and they are commonly used in upper and lower limb joint arthroplasty today.1 Modern SHS use a combination of a loose-fitting hood and an impermeable ‘toga’ to reduce bacterial shedding from the surgeon onto the surgical field and thus, theoretically, reduce the incidence of PJI.2
Conflicting evidence exists, however, regarding their efficacy. Some registry data suggest that modern SHS may reduce rates of infections or revision in over 19,000 total knee arthroplasties (TKAs).3 On the contrary, in an earlier registry study of over 65,000 knees, SHS did not reduce the risk of deep infections,4 a finding which is also supported by a systematic review and meta-analysis of nearly 4,000 patients.5
In some experimental studies, SHS are paradoxically hypothesized to be worse,6-8 possibly due to contamination of the surgical field by the exhaust, although the variations in make and model of the suit may also be a contributing factor,9 as may the donning technique.10 To date, no large-scale studies have been conducted regarding their use in shoulder arthroplasty. We set out to investigate if the use of SHS was associated with reduced PJI in shoulder arthroplasty. We used data submitted to the New Zealand Joint Registry over a 20-year period. Our null hypothesis was that wearing a SHS would not reduce PJI or revision for infection following primary shoulder arthroplasty.
Methods
The New Zealand Joint Registry was established in 1999; submission of every arthroplasty performed in New Zealand is now a compulsory requirement for annual accreditation with the New Zealand Orthopaedic Association. Among other things, the registry records whether or not the surgical team wore conventional gowns or SHS. It also records patient factors including age, BMI, sex, and American Society of Anesthesiologists (ASA) grade,11 as well as whether the operation took place in a laminar flow operating theatre. In revision cases, the primary indication for surgery is recorded (e.g. loosening, infection, malposition). Reports are published annually and are publicly available on the registry website.12
Implant survival is measured by revisions per 100 component years (as defined by time from surgery to either revision or death), so one revision per 100 component years = 1% revision at one year or 10% at ten years. The advantage of this system is that it allows comparison between components irrespective of how long ago they were implanted.
All primary shoulder arthroplasties (hemiarthroplasty (HA), anatomical total shoulder arthroplasty (aTSA), or reverse total shoulder arthroplasty (rTSA)) ever recorded on the New Zealand Joint Registry (i.e. from January 2000 to December 2023) were eligible for this study. We identified all joint arthroplasties that resulted in a revision procedure for infection; rate of infection was recorded as a percentage of all shoulder joint arthroplasties undertaken during the study period. Patient demographic data are shown in Table I.
Table I.
Patient characteristics.
| Characteristic | Conventional, n (%) | SHS, n (%) | p-value* |
|---|---|---|---|
| Sex | 0.656† | ||
| Female | 8,034 (82.90) | 1,659 (17.10) | |
| Male | 5,282 (83.20) | 1,070 (16.80) | |
| Age, yrs | < 0.001‡ | ||
| < 55 | 858 (87.80) | 119 (12.20) | |
| 55 to 64 | 2,515 (85.00) | 444 (15.00) | |
| 65 to 74 | 5,161 (82.90) | 1,065 (17.10) | |
| ≥ 75 | 4,782 (81.30) | 1,101 (18.70) | |
| ASA grade | < 0.001† | ||
| 1 | 1,000 (86.50) | 156 (13.50) | |
| 2 | 6,808 (81.70) | 1,526 (18.30) | |
| 3 | 4,076 (81.20) | 944 (18.80) | |
| 4 | 123 (82.00) | 27 (18.00) | |
| BMI, kg/m 2 | 0.898‡ | ||
| < 19 | 52 (85.20) | 9 (14.80) | |
| 19 to 24 | 1,121 (86.90) | 169 (13.10) | |
| 25 to 29 | 2,217 (86.00) | 362 (14.00) | |
| 30 to 39 | 2,420 (85.80) | 402 (14.20) | |
| 40+ | 437 (85.70) | 73 (14.30) |
-
*
Directly comparing whether a variable was associated with higher or lower use of surgical helmet system.
-
†
Chi-squared test.
-
‡
One-way analysis of variance.
-
ASA, American Society of Anesthesiologists; SHS, surgical helmet system.
Statistical analysis
The revision rates were summarized as the revision rates per 100 component years and compared using Cox proportional hazards regression (HR). The presenting features were compared between the groups using a chi-squared test or one-way analysis of variance (ANOVA) as appropriate to the variable types. A two-tailed p < 0.05 was considered statistically significant. Our study had approximately 80% power to detect a doubling (or worse) in revision rates between groups. Analyses were conducted using SPSS version 28.0 (IBM, USA).
Results
There were 16,045 primary shoulder arthroplasties registered on the New Zealand Joint Registry during the study period, which recorded information concerning the gowns used. A total of 9,693 patients (60%) were female; 56% of implants (n = 8,967) were reverse geometry TSAs (Table II).
Table II.
Implant types used. In 13 cases (0.08%), the implant type was not recorded.
| Implant type | Conventional, n (%) | SHS, n (%) |
|---|---|---|
| Hemiarthroplasty | 2,018 (88.5) | 261 (11.5) |
| rTSA | 7,350 (82.0) | 1,617 (18.0) |
| aTSA | 3,936 (82.2) | 850 (17.8) |
-
aTSA, anatomical total shoulder arthroplasty; rTSA, reverse geometry total shoulder arthroplasty; SHS, surgical helmet system.
Indications for surgery are shown in Table III. More than one indication can be cited, although the two commonest indications were osteoarthritis (18.7%) and rheumatoid arthritis (18.3%). Rotator cuff tears or massive rotator cuff tears were cited in 26% of cases (n = 4,188).
Table III.
Indications for surgery.
| Indication for surgery | Conventional, n (%) | SHS, n (%) | p-value† |
|---|---|---|---|
| Osteoarthritis | 6,747 (81.30) | 1,550 (18.70) | < 0.001 |
| Rheumatoid arthritis | 748 (81.70) | 167 (18.30) | 0.303 |
| Other inflammatory condition | 146 (83.90) | 28 (16.10) | 0.746 |
| Rotator cuff tear | 3,227 (83.80) | 623 (16.20) | 0.117 |
| Massive rotator cuff tear | 303 (89.60) | 35 (10.40) | < 0.001 |
| Acute fracture | 1,255 (85.50) | 213 (14.50) | 0.008 |
| Old trauma | 763 (84.20) | 143 (15.80) | 0.312 |
| Avascular necrosis | 364 (84.70) | 66 (15.30) | 0.353 |
| Dislocation | 226 (84.60) | 41 (15.40) | 0.469 |
| Tumour | 11 (91.70) | 1 (8.30) | 0.424 |
| Other | 587 (86.70) | 90 (13.30) | 0.009 |
-
*
Directly comparing whether a variable was associated with higher or lower use of surgical helmet system.
-
†
Chi-squared test.
Overall, 37.4% of operations (n = 6,007) took place in laminar flow theatres; 2,728 operations (17%) took place with the staff wearing a SHS. There were 842 revisions (5% of cases) with just 98 for deep infection (0.6% in total or 11.6% of the revisions). Of 13,316 procedures that took place in conventional gowns, 702 resulted in a revision (5.27%), compared to 140 of 2,729 (5.13%) which used a SHS. Of the procedures in conventional gowns, 81 (0.6%) resulted in a revision for deep infection compared to 17 (0.6%) of those conducted using SHSs. There were no statistically significant differences in all-cause revisions or revision for deep infection between the SHS and conventional gowns respectively (HR = 0.99, 95% CI 0.82 to 1.18, p = 0.893) and (HR = 1.03, 95% CI 0.61 to 1.74, p = 0.911).
There was a statistically significant difference in procedure time between SHS and conventional gowns (115.6 mins vs 113.5 mins, p = 0.009, one-way ANOVA); however, this difference of approximately two minutes is unlikely to be clinically significant, and does not necessarily account for the additional time taken for gowning prior to knife to skin.
Discussion
We did not find any evidence from the New Zealand Joint Registry that wearing a SHS reduces the incidence of PJI in any kind of primary shoulder arthroplasty. To our knowledge, this is the largest ever study of its kind on this topic.
In keeping with other observations the number of TSAs is increasing, as is the ratio of reverse geometry TSAs compared to anatomical TSAs.13 Mercifully, our study found that revisions for deep infections are rare (0.6%).
Other benefits of SHSs were considered to be outside the scope of this paper. Of late, focus has turned increasingly towards their role in safeguarding the surgeon from exposure to fluids or aerosols coming from the patient. Interestingly, the leading manufacturers currently recommend SHSs as personal protective equipment (PPE) and no longer include claims about infection prevention in their marketing.14,15 There may be other, more subjective indications such as surgeon comfort or visibility which may play a role in personal decision-making.
SHS also have drawbacks. Not only is there the purchase cost but there are ongoing financial and environmental costs associated with maintenance and consumables, which are frequently incinerated. The headsets themselves are frequently colonized by pathogens, such as Cutibacterium acnes and Staphylococcus epidermidis (although the significance of this is unknown).16
In recent years, there has been an insurgence of interest in advanced navigation techniques or augmented reality in shoulder arthroplasty surgery.17,18 Such systems often require the surgical team to wear a headset intraoperatively which may preclude the use of space suits.
Our study has some limitations. Level 1 evidence for infection prevention in shoulder arthroplasty is difficult to gather due to the low numbers of surgeries worldwide and low rate of PJI (just 0.6% of cases in this study). Registry studies represent a reasonable alternative, but they are not without their problems. Most presciently, although the New Zealand Joint Registry records basic demographic data, including age, sex, BMI, and ASA grade, this is not an exhaustive list of comorbidities. It is conceivable that surgeons who consider individual patients to be high-risk (e.g. those with diabetes, immunosuppression, and/or previous infections) selectively choose to wear a SHS as a countermeasure, introducing a possible source of selection bias.
Additionally, it is possible that some revision arthroplasties were not recorded, or that infection was not cited as an indication for revision at the time (even if this transpired to be the case subsequently). Furthermore, we were unable to draw any conclusions about the brand of SHS garments used, or the donning techniques of the individual users.
In conclusion there is currently insufficient evidence to recommend the routine use of SHS in primary shoulder arthroplasty as a means of reducing PJI. Given their cost and environmental footprint, they should be used judiciously.
References
1. Charnley J . Postoperative infection after total hip replacement with special reference to air contamination in the operating room . Clin Orthop Relat Res . 1972 ; 87 : 167 – 187 . Crossref PubMed Google Scholar
2. Ghazavi MT . Role of body exhaust system in reducing peri-prosthetic joint infection, literature review . Shafa Ortho J . 2016 ; 3 ( 4 ). Crossref Google Scholar
3. Rahardja R , Morris AJ , Hooper GJ , Grae N , Frampton CM , Young SW . Surgical helmet systems are associated with a lower rate of prosthetic joint infection after total knee arthroplasty: combined results from the New Zealand Joint Registry and Surgical Site Infection Improvement Programme . J Arthroplasty . 2022 ; 37 ( 5 ): 930 – 935 . Crossref PubMed Google Scholar
4. Tayton ER , Frampton C , Hooper GJ , Young SW . The impact of patient and surgical factors on the rate of infection after primary total knee arthroplasty: an analysis of 64,566 joints from the New Zealand Joint Registry . Bone Joint J . 2016 ; 98-B ( 3 ): 334 – 340 . Crossref PubMed Google Scholar
5. Young SW , Zhu M , Shirley OC , Wu Q , Spangehl MJ . Do “surgical helmet systems” or “body exhaust suits” affect contamination and deep infection rates in arthroplasty? A systematic review . J Arthroplasty . 2016 ; 31 ( 1 ): 225 – 233 . Crossref PubMed Google Scholar
6. Nakajima D , Tateiwa T , Masaoka T , Takahashi Y , Shishido T , Yamamoto K . Does modern space suit reduce intraoperative contamination in total joint replacement? An experimental study . Eur J Orthop Surg Traumatol . 2017 ; 27 ( 8 ): 1139 – 1143 . Crossref PubMed Google Scholar
7. Pasquarella C , Pitzurra O , Herren T , Poletti L , Savino A . Lack of influence of body exhaust gowns on aerobic bacterial surface counts in a mixed-ventilation operating theatre. A study of 62 hip arthroplasties . J Hosp Infect . 2003 ; 54 ( 1 ): 2 – 9 . Crossref PubMed Google Scholar
8. Vijaysegaran P , Knibbs LD , Morawska L , Crawford RW . Surgical space suits increase particle and microbiological emission rates in a simulated surgical environment . J Arthroplasty . 2018 ; 33 ( 5 ): 1524 – 1529 . Crossref PubMed Google Scholar
9. Ling F , Halabi S , Jones C . Comparison of air exhausts for surgical body suits (space suits) and the potential for periprosthetic joint infection . J Hosp Infect . 2018 ; 99 ( 3 ): 279 – 283 . Crossref PubMed Google Scholar
10. McAleese T , Ó Doinn T , Broderick JM , Farrington R , Prior A-R , Quinlan JF . Surgical helmet systems in total joint arthroplasty: assessment of hood sterility and donning technique . Arthroplasty . 2023 ; 5 ( 1 ): 53 . Crossref PubMed Google Scholar
11. Saklad M . Grading of patients for surgical procedures . Anesthesiol . 1941 ; 2 ( 3 ): 281 – 284 . Google Scholar
12. No authors listed . New Zealand Orthopaedic Association . 2024 . https://www.nzoa.org.nz/nzoa-joint-registry ( date last accessed 13 September 2024 ). Google Scholar
13. Best MJ , Aziz KT , Wilckens JH , McFarland EG , Srikumaran U . Increasing incidence of primary reverse and anatomic total shoulder arthroplasty in the United States . J Shoulder Elbow Surg . 2021 ; 30 ( 5 ): 1159 – 1166 . Crossref PubMed Google Scholar
14. No authors listed . Flyte Hood Information for Healthcare Professionals . Stryker . https://www.stryker.com/us/en/orthopaedic-instruments/products/flyte-personal-protection-system.html ( date last accessed 13 September 2024 ). Google Scholar
15. No authors listed . ViVi Surgical Helmet System . Zimmer Biomet . https://www.zimmerbiomet.com/en/products-and-solutions/specialties/surgical/vivi-surgical-helmet-system.html ( date last accessed 13 September 2024 ). Google Scholar
16. Tarabichi S , Chisari E , Van Nest DS , Krueger CA , Parvizi J . Surgical helmets used during total joint arthroplasty harbor common pathogens: a cautionary note . J Arthroplasty . 2022 ; 37 ( 8 ): 1636 – 1639 . Crossref PubMed Google Scholar
17. Rossi SMP , Mancino F , Sangaletti R , Perticarini L , Lucenti L , Benazzo F . Augmented reality in orthopedic surgery and its application in total joint arthroplasty: a systematic review . Applied Sciences . 2022 ; 12 ( 10 ): 5278 . Crossref Google Scholar
18. Tanzer M , Laverdière C , Barimani B , Hart A . Augmented reality in arthroplasty: an overview of clinical applications, benefits, and limitations . J Am Acad Orthop Surg . 2022 ; 30 ( 10 ): e760 – e768 . Crossref PubMed Google Scholar
Author contributions
A. Stoneham: Data curation, Project administration, Writing – original draft, Writing – review & editing
P. Poon: Conceptualization, Supervision, Writing – review & editing
M. Hirner: Writing – review & editing
C. Frampton: Data curation, Formal analysis, Writing – review & editing
R. Gao: Supervision, Writing – review & editing
Funding statement
The authors received no financial or material support for the research, authorship, and/or publication of this article.
ICMJE COI statement
R. Gao reports payments or honoraria for educational events from LimaCorporate, unrelated to this study. M. Hirner reports speaker payments or honoraria from Zimmer Biomet and Arthrex, unrelated to this study. P. Poon reports royalties, consulting fees, and speaker payments or honoraria from Enovis (Lima), also unrelated to this study.
Data sharing
The data that support the findings for this study are available to other researchers upon request to: research@waitematadhb.govt.nz.
Acknowledgements
We would like to acknowledge the great work done by the Wishbone Orthopaedic Research Foundation of New Zealand.
Ethical review statement
The New Zealand Joint Registry has national ethical approval. Patients undergoing joint arthroplasty provide consent to collection and use of their data.
Open access funding
The open access fee for this article was provided by the North Shore Hospital Orthopaedic Department.
© 2024 Stoneham et al. This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives (CC BY-NC-ND 4.0) licence, which permits the copying and redistribution of the work only, and provided the original author and source are credited. See https://creativecommons.org/licenses/by-nc-nd/4.0/
