Volume 04 / Issue 01 / March 2016 boa.ac.uk Page 48

JTO Peer-Reviewed Articles

Debridement: Defining something we all do

Wasim Khan

single- or two-stage revision procedure. The re-infection rate following a single-stage revision TKR is falling2, and one possible reason for this is the better understanding of, and greater attention to debridement.

Debridement can be divided into superficial and deep3,4,5. Superficial wound debridement can be sub-divided into autolytic (hydrogels and auto-enzymes), enzymatic (streptokinase and collagenase), and biological (maggot therapy). Deep wound debridement is sub-divided into surgical, which includes explantation and sharp dissection, mechanical, curettage and reaming, power lavage and optionally hydrogen peroxide (H2O2), and chemical, such as acetic acid and honey.

It is important to appreciate the soft tissue envelope as failure to do so may lead to poor wound healing and subsequent compromise of deep tissues6,7. It is also important to appreciate that debridement is separate from this and must not be compromised by thoughts of reconstruction. In this article we will concentrate on the role of deep debridement in the management of the infected knee replacement.

Wasim Khan & Rhidian Morgan-Jones

In the modern management of orthopaedic infection, debridement and the ritual of the reproducible steps that go with it are paramount. Debridement is defined in the Oxford Dictionary of the English Language as ‘the removal of damaged tissue or foreign objects from a wound’. It derives from the original French debridement (1835-45), literally to take away the bridle.

Rhidian Morgan-Jones

The ‘ritual of the surgical operation’ was described by Lord Moynihan almost 100 years ago1. All aspects of surgery can be enhanced by ritual or, as we would see it today, a repetition of a defined technique to achieve reproducible outcomes. Debridement of the infected total knee replacement (TKR) is no different.

We strongly believe that the debridement is the most important determinant of successful infected TKR surgery, whether it is performed to retain implants as part of a DAIR (debride, antibiotics and implant retention) procedure, or performed for a

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Deep

Surgical Explantation, sharp dissection

Mechanical Curettage, Reaming, Lavage, H2O2

Chemical Acetic Acid, SurgiHoney

Superficial Autolytic Hydrogels, auto-enzymes

Enyzmatic Streptokinase, Collagenase

Biological Maggot therapy

should be curetted and the deep sinus tract excised. All curetted sinuses will heal if adequately debrided and the source of infection removed. Occasionally, plastic surgical coverage must be planned for when potentially non-viable or necrotic skin is present; a medial gastrocnemius rotational or pedicle flap is generally sufficient.

When dealing with infected arthroplasty, explantation is akin to sequestrectomy and must include all implants and necrotic bone. Flexible osteotomes are best to take down the implant-cement interface, although sharp rigid osteotomes should be available. Sharp dissection

involves a thorough synovectomy and excision of all visible infected membrane or biofilm. Blocking the medullary canals with a swab prevents debrided material from entering them. Ligaments are vascular structures and do not routinely need to de excised. Only when explantation and sharp dissection has been completed can the next stage of debridement begin.

All tissue removed at debridement has the potential for bacteriological sampling. Again a consistent protocol is useful to improve sensitivity and specificity. The authors’ protocol is to obtain the following samples in order: 1- joint aspirate, 2- synovial samples (x2), 3- femoral joint surface tissue, 4- tibial joint surface tissue, 5- tibial canal membrane, 6- femoral canal membrane. A total of 6 to 7 samples are obtained with non-contaminated instruments.

2. Mechanical debridement

Mechanical debridement has several distinct stages. The femoral and tibial joint surfaces and intra-medullary canals are curetted of any residual membrane, avascular bone

and cement residue. The pre-operative radiographs are useful to identify material invisible to the naked eye. The femoral and tibial intra-medullary canals are then carefully power-reamed to remove persistent neo-cortex and membrane in a compartmental debridement as described by Lautenbach9,10,11,12.

Hydrosurgical debridement is performed next with high-pressure fluid, commonly sterile saline. All joint surfaces and canals are lavaged under power using the appropriate nozzle attachments. Lavage of the soft tissues, joint surfaces and the intra-medullary canals must be performed in a sequential manner. Most surgeons prefer saline but other solutions with added chemicals or antibiotics can be used according to preference. The volume of pulse lavage fluid used is less important than where and how the operative field is lavaged. Pulse lavage has a tidal effect of washing loose debris away from the operating field but more importantly lavage under power makes any infected membrane adherent to bone oedematous. Oedematous membrane is easier to both see and to debride with a further cycle of curettage and reaming. Mechanical

1. Surgical debridement

An adequate debridement of an infected knee requires an extensile approach which accommodates previous skin incisions. As a general rule, previous incisions are used if adequate, and extended proximally and distally as needed. The senior author favours a Tibial Crest Osteotomy to improve access to both explant and debride all corners, whilst protecting the extensor mechanism8. Broad scars should be excised in a mobile joint but caution is required in the stiff and tethered knee. Sinuses in the line of incision should be excised. Isolated sinuses elsewhere

Journal of Trauma and Orthopaedics: Volume 04, Issue 01, pages 48-50Title: Debridement: Defining something we all do

Authors: Wasim Khan & Rhidian Morgan-Jones

© 2016 British Orthopaedic Association

Table 1: Methods of debridement

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JTO Peer-Reviewed Articles

debridement and prior to chemical debridement, allowing the biofilm and organisms to be presented for a chemical onslaught.

3. Chemical debridement

Chemical debridement is the final part of deep debridement and seeks to create a hostile chemical environment that further degrades residual biofilm, as well as killing and preventing further bacterial growth. Although several options are available, the senior author prefers 3% Acetic Acid14,15 which lowers the environmental pH and has activity against both

Gram negative and positive microorganisms. Generally a 10 to 20 minute acetic acid soak before reimplantion is sufficient. Another option is SurgiHoney™16,17 which works by a local osmolar effect but also produces hydrogen peroxide. SurgiHoney™ also has the potential to be used as an antibacterial coating after re-implantation. Other potential chemical debridement agents include alcoholic betadine, chlorhexidine and hypochlorite.

Conclusion

Debridement is as much a formal part of any revision as is the reconstruction of bone loss and soft tissue balance. By having defined stages which include surgical, mechanical and chemical debridement, a throrough and reproducible debridement is possible. It is important to understand that achieving adequate clearance of infection in a single pass may not be possible and this underpins the concept of repeated cyclical debridement. Finally, debridement should be seen as separate from reconstruction, which should not be prejudiced by inadequate debridement.

debridement should be seen as cyclical with a minimum of two, and possibly three cycles required to achieve adequate mechanical debridement (Figure 1).

Hydrogen peroxide is used for the mechanical effect of oxygen release producing effervescent cleaning and theoretical biofilm degradation and cell wall penetration13. Controversy remains over the risk of air embolus whilst using hydrogen peroxide, although this risk is mitigated by the use of a tourniquet. If hydrogen peroxide is used the authors recommend its use after the cyclical mechanical

Debridement is the most important step in a sequence of events, but all the other components of management including a multidisciplinary approach, optimisation of the patient’s medical comorbidities, appropriate antibiotic sampling and therapy, and definitive implantation are all also essential to ensure a good result.

Wasim Khan is a Post CCT Orthopaedic Fellow with an interest in Knee Surgery and Research.

Rhidian Morgan-Jones is an orthopaedic Consultant and Honorary Lecturer at the University Hospital Llandough, Cardiff. He specialises in revision knee replacement and infection.

Correspondence:

Email: wasimkhan@doctors.org.uk Email: rhidianmj@hotmail.com

References:

References can be found online at www.boa.ac.uk/publications/JTO or by scanning the QR Code.

Figure 1: Cyclical debridement

We strongly believe that the debridement is the most important determinant of successful infected tKr surgery, Whether it is performed to retain implants as part of a dair (debride, antibiotics and implant retention) procedure, or performed for a single- or tWo-stage revision procedure.

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