|Year : 2015 | Volume
| Issue : 4 | Page : 257-262
Negative pressure wound therapy in orthopaedic post operative infections: Role in implant retention and dead space management
Nanda Kishore Maddineni, Satya Kumar Koduru, Harshavardan Surath, Ananda Rao Venkata Dakshina Murthy, Mettu Rami Reddy, Amarnath Surath
Department of Orthopaedics, NRI Medical College and General Hospital, Amar Orthopaedic Hospital, Guntur, Andhra Pradesh, India
|Date of Web Publication||14-Dec-2015|
Department of Orthopaedics, NRI Medical College and General Hospital, Chinnakakani, Guntur - 522 503, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
Introduction: Postoperative orthopedic infections in the presence of implants require timely and aggressive intervention for eradication of infection. Negative pressure wound therapy (NPWT) is beneficial in wound management and implant retention, ultimately leading to fracture union. Incidentally, the use of NPWT was of great help in reducing dead space, which is responsible for the chronicity of the infection. It results in collapse of the cavity without need for repeated debridement.
Aims and Objectives: This study is done to evaluate the role of negative pressure wound therapy in orthopaedic post operative infections and it's role in implant retention and dead space management.
Materials and Methods: Thirty-four patients who developed postoperative infections are included in the study. After thorough wound lavage NPWT dressing was applied followed by wound closure either by secondary suturing, skin graft or flap cover.
Results: Thirty-four patients were treated during 2012-2014 out of which 22 patients had implants, 2 were treated for dead space, and 10 for both.
Conclusion: NPWT has a definite role in eradicating early postoperative infection in the presence of an implant. The greatest advantage is retention of the implant.
Keywords: Dead space management, early postoperative infections, negative pressure wound therapy (NPWT), retention of implant
|How to cite this article:|
Maddineni NK, Koduru SK, Surath H, Dakshina Murthy AV, Reddy MR, Surath A. Negative pressure wound therapy in orthopaedic post operative infections: Role in implant retention and dead space management. J NTR Univ Health Sci 2015;4:257-62
|How to cite this URL:|
Maddineni NK, Koduru SK, Surath H, Dakshina Murthy AV, Reddy MR, Surath A. Negative pressure wound therapy in orthopaedic post operative infections: Role in implant retention and dead space management. J NTR Univ Health Sci [serial online] 2015 [cited 2020 Jan 25];4:257-62. Available from: http://www.jdrntruhs.org/text.asp?2015/4/4/257/171743
| Introduction|| |
Early postoperative orthopedic infections require aggressive management to retain implants and achieve wound and bone healing. The treatment is aimed at eradicating the infection before it became chronic and almost impossible to treat. Different methods to treat postoperative infection are intravenous antibiotics (based on wound culture), thorough lavage of the wound, local instillation of antibiotics, removal of implant, and use of external fixation device like orthofix/ilizarov ring fixator. ,
Local antibiotic instillation is ineffective against bacteria in biofilm. Substituting the primary implant with external fixation device requires a second surgical procedure and might have patient issues. This study demonstrates that NPWT is a reliable method of treating early postoperative infection.
| Materials and Methods|| |
The study was conducted from 2012 to 2014 on 34 cases of postoperative infections.
- Presence of infections.
- Immediate postoperative infected wounds up to 3 weeks.
- Chronic infected wounds more than 3 weeks.
- Open fracture with contamination (farmyard injuries).
- Chronic osteomyelitis.
The patients were recruited into the study when the following signs were seen in the postoperative period:
- Pyrexia (spiking temperature).
- Erythema around wound edges.
- Discharge from wound.
- Positive inflammatory markers.
Once wound is presumed to be infected, it is completely laid open, a deep tissue swab was taken and sent for bacteriological examination, based on which an antimicrobial therapy started. [Table 1] shows different pathogens isolated from microbial culture and sensitivity studies.  Dead muscles or soft tissue was excised. The wound was thoroughly washed with 3-6L of saline/ringer lactate solution. NPWT dressing applied [Figure 1],[Figure 2],[Figure 3] and [Figure 4] with the following parameters: 
- Negative pressure between 125 and 150 mmHg.
- Intermittent application of suction with 5 min on/3 min off.
- Airtight wound without leaks.
- Uniform negative pressure over the wound surface.
Dressing change was done once in 48 h. Dressing continued until exudation stopped, healthy granulation tissue developed, and inflammatory markers become normal.
Deep wounds with dead space (postoperative spinal instrumentation) were evaluated by volumetric measurement of the wound [Figure 5],[Figure 6],[Figure 7],[Figure 8] and [Figure 9]. This is performed by measuring the amount of saline that is required to fill the cavity serially. The reduction in the volume of liquid needed to fill the wound is a reliable indicator of reduction in wound size.
When healthy granulation tissue was formed and C-reactive protein levels were within normal limits, secondary procedures, such as suturing/grafting/flap cover, were performed [Figure 10] and [Figure 11]. The end point of the study was when the patient retained the implant with eradication of infection and went on to bone union [Figure 12].
| Results|| |
This study comprises of 34 patients who had a total of 110 NPWT applications. Average number of NPWT applications in our study is 3.2 per case (maximum 5 dressing and minimum 2 dressings). Males patients comprised of 76% and females comprised 24% in our study sample. The site of post-operative wound is shown in [Table 2].
The average exudate collected was 35 mL (minimal 20 mL and maximum 50 mL). Secondary procedures are shown in Chart 1.
Average hospital stay was 26 days (maximum 37 days and minimum 18 days). In our series, we were able to retain the implants in all cases without resorting to secondary procedure on bone. Average time of fracture healing is shown in [Table 3], excluding spine surgeries. The radiological union could not be assessed objectively in spinal fusion. In patients who underwent spine fusion pain relief and return to activity was presumed to be evidence of fusion.
| Discussion|| |
Surgical site infection after implant surgery for fracture is a dreaded complication. The worst case scenario is early removal of implant causing nonunion compounded by osteomyelitis. The development of infected nonunion will result in increased antibiotic use, repeated debridement, and prolonged hospital stay.  Hence, procedures that help retain the primary implant and bring about bone union will go a long way in reducing morbidity.
Biofilm (glycocalyx) is a composed of extracellular matrix that is a combination of exopolysaccharides and glycoproteins. Antibiotics are mostly effective against rapidly dividing bacteria in planktonic form. In biofilm colonies, the bacteria are mostly sessile, existing in a dormant state, and hence not effected by antibiotics. Phagocytes also have reduced efficiency in ingesting sessile bacteria.  Studies have shown that titanium implants inhibit bacterial adherence and biofilm formation. Research is focused on developing nanomaterials to alter the surface properties of implants, so that they repel bacterial adherence. ,
The debris and slime seen in infected wound is produced by bacteria with in biofilm colonies. The negative pressure applied is marginally higher than that used for management of chronic wounds, that is, 125-150 mmHg. The higher negative pressure will help clear the bacterial slime and exudates from the wound more rapidly. Despite the advantage of rapid granulation tissue formation, NPWT has not been frequently used in implant-related infection. In majority of the articles, it has been used to manage infection after spinal instrumentation  and arthroplasty.  A question that arises at this stage is whether NPWT can be used prophylactically over incision at risk. Incisional negative pressure wound therapy (i.e. NPWT) is applied to prevent complications such as seroma, hematoma, blister, and infections. A detailed meta-analysis by Michel et al. drew the following conclusion.  The mechanism by which incisional NPWT works is by increase in blood flow up to 5 times in the incised area as shown by Timmer's et al.  Out of all the abovementioned wound complications, infection is the most modulated. Whether the increased blood supply as a result of NPWT application or application of dressing in the operative room results in reduced wound exposure and hence reduction in infection rate is yet to be established. At this stage, it is logical to assume that high-risk surgical site, such as tibial plateau and pilon and calcaneal fractures, will do better with incisional NPWT. However, cost constraints prevent the use of NPWT on all incision sites. When infection is suspected prompt application of NPWT dressing will prevent the bacteria from gaining the foothold and forming biofilm colonies.
A newer version of NPWT wherein intermittent instillation of antibiotic along with NPWT has been devised by Kinetics Concepts Incorporated, San Antonio, Texas (KCI) is known as VAC-instill system. We have no experience with this modality. ,
In the present study, 34 cases of orthopedic surgical site infections were treated by NPWT. The dressings are sourced from the readily available materials and are cost-effective.  NPWT resulted in rapid growth of granulation tissue and reduction in exudation. The wound was rendered suitable for secondary procedure in average time of 8 days (minimum 6 days and maximum of 12 days). None of the cases in our series required removal of metal and all cases went on to fracture union. NPWT in cases of postoperative infections prevents a second surgical procedure so performing it is well worth the effort. In addition to being cost-effective, the patient is spared the stress of a second surgery.
| Conclusion|| |
The use of NPWT in early orthopedic surgical site infection will prevent implant removal and facilitate rapid formation of granulation tissue. It will render the wound environment suitable for soft tissue reconstruction, ultimately leading to fracture union.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12]
[Table 1], [Table 2], [Table 3]