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Microbial Sealants – a new, complementary strategy
to conventional SSI prevention
Author: Kimberly Clark
Surgical site infections (SSI) continue to pose an enormous health and economic burden to patients and hospitals across Europe, challenging orthopaedic surgeons to find new products and techniques that effectively reduce their occurrence. Here we examine the outcome of the UK’s recent national SSI surveillance study and speak with consultant orthopaedic surgeon Andrew Skyrme about a new topical microbial sealant that tackles the problem of commensal flora in a simple but entirely unique way.
Since 1997, the Surgical Site Infection Surveillance Service (SSISS), under the Department of Health, has captured statistical data on more than 130,000 orthopaedic surgeries, tracking the occurrence of surgical site infections (SSI) and enabling National Health Service (NHS) trusts to critically review their infection control practices. March 2005, marked the end of the first year of mandatory surveillance with data assembled on four of the most common orthopaedic procedures: hip and knee arthroplasty, hemi-arthroplasty of the hip, and internal fixation of trochanteric fractures.1 The results of this report have shown that although the occurrence of SSI in arthroplasty procedures is low when compared to higher risk surgeries (e.g. CABG, liver surgery or gut surgery), there is still need for improvement as total infection rates may exceed 1.5%.
As exhibited in previous investigations, the SSISS found that the occurrence of infection is variable between surgical category and dependent on the number of risk factors present in each patient.2,3 Hemiarthroplasty hip replacements, for example, are associated with the highest rate of infection (4.1%) due to the higher average age of these patients and the greater likelihood that they will present with an underlying illness.4 In total hip and total knee arthroplasties (THA and TKA), which make up the majority of orthopaedic surgeries performed, the mean occurrences of SSI are 1.2% and 0.7%, respectively. However, these numbers may underestimate the actual number of infection cases as the study authors point out that current surveillance methodology only counts those infections detected prior to patient discharge. This is likely to have a larger impact on the figures for SSI following knee replacement rather than hip replacement procedures, due to the typically shorter in-hospital stays required for knee arthroplasty. In Germany, for example, comparable data from the national nosocomial infection surveillance system, KISS (Krankenhaus Infektions Surveillance System), exhibited infection rates of 0.9% for primary hip arthroplasties and 1.1% for knee arthroplasties (category HPRO A and KPRO, respectively).5
For many orthopaedic surgeons, however, the more concerning issues regarding SSI are the relatively high occurrence of deep and/or organs space infections and the increasing prevalence of drug-resistant bacteria in joint replacement procedures. According to SSISS survey data, more than one-in-four orthopaedic SSI affect the deeper tissues and/or the joint space, including 27.3% of THA and 24.0% of TKA patients. In such cases, bacteria colonise and adhere to the artificial joint surfaces causing premature loosening of the implant. After successful attachment, the bacteria then develop a fibrous biofilm, making them much more resistant to host immunity and antimicrobial therapy.6 Treatment of these deep infections involves immediate replacement of the prosthesis (which may itself require more than one procedure to complete) and extensive antibiotic treatment,.
The 2004-2005 study also revealed that in almost one-third (31.0%) of those infected, the responsible agent was methicillin-resistant Staphylococcus aureus (MRSA; methicillin-sensitive S. aureus was the causative agent in 17.5% of cases). Although comparable orthopaedic-specific figures are not available for other countries, the prevalence of MRSA is known to be on the rise across Europe and greatest in the UK.7 This bears significant cost implications as the treatment of such infections is far more complex, involving greatly extended hospital stays. There is also growing concern regarding the recent emergence of VRSA (Vancomycin Resistant S. aureus) and VRE (Vancomycin Resistant Enterococci). Vancomycin has been the drug of choice for almost 30 years for the treatment of patients infected with MRSA and a shift towards these new strains would pose significant health and economic threats.
Back to basics
For joint replacement procedures, three attributes are commonly used to establish the risk index of surgery (from the US National Nosocomial Infections Surveillance, CDC).8
- a wound classification of ‘contaminated’ or ‘dirty’;
- a duration of operation greater than the 75th percentile for that surgery; and,
- an American Society of Anaesthesiologists Physical Status (ASA-PS) class III or higher.
Each of these contributes one point to the risk factor index, which ranges from 0 if no factors are present, to 3 if all factors are present. Yet it is well known that even conditions of a 0 or 1 risk category does not guarantee complete protection. In surgically clean joint replacement operations, the most common source of bacterial contamination is the patient’s own commensal skin flora and no procedure exists to completely sterilise the skin.6 This is evidenced by the fact that of the SSI cases recorded in the SSISS survey, 66.8% of those SSI found in THA patients, and 77.5% of those in TKA patients were classed as having a risk index of 0 or 1. Preoperative planning and high standards of asepsis are therefore crucial to the prevention of SSI.
Across Europe, the techniques used to limit the transmission of bacteria to the surgical wound have largely become standardised with limited variance between hospitals. As a consultant orthopaedic surgeon, Andrew Skyrme explains, “The prevention of surgical infections has long been managed by a set of internationally-accepted prevention techniques. Such procedures include antibiotic prophylaxis, patient washing with antimicrobial soap, hair removal, skin preparation with antiseptic iodine, the use of incise and surgical drapes, and maintenance of normothermia. These procedures are generally effective, eliminating most of the commensal flora found near the surgical site and minimising the likelihood of infection. Occasionally, however, the protection these procedures usually afford becomes compromised through normal surgical routines. Surgical solutions, for example, may wash off during surgery, allowing the wound edges to be recolonised after prepping the skin. In some cases, microabrasions created during the shaving and hair removal process can expedite this as they may preserve bacteria at the wound site. Similarly, patient perspiration may cause surgical and incise drapes to loosen, weakening their protective seal. This is of particular concern when operating on or near parts of the body known to harbour greater amounts of bacteria such as the groin, armpits, or feet.”
A complementary alternative
Despite the efforts of surgical teams to kill or remove bacteria present at the time of surgery, a viable amount often remains on the skin to later migrate to and contaminate the surgical wound. Recently, however, a topical microbial sealant was developed to provide an alternate solution to this problem through an action that complements standard aseptic techniques. Integuseal® Microbial Sealant (Kimberly-Clark) is a cyanoacrylate-based liquid that is designed to immobilise and lock bacteria left behind after normal preoperative cleaning. Unlike iodophors and alcohol-based cleaning products, which attempt to eliminate the pathogenic skin flora, Integuseal is a film-forming barrier intended to protect against the migration of microbial contaminants across the skin. Its novel mechanism of action also means that it does not promote bacterial resistance.
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| Fig 1.a: Integuseal® pre-surgical microbial sealant; demonstration of application. Image courtesy of Kimberly-Clark. |
Cyanoacrylate compounds are nothing new to medicine, having already been used in medical glues and wound closure products. The particular formulation used in Integuseal has been designed to be applied preoperatively, directly before the surgical incision. The product is supplied in a ready to use applicator, which is used to ‘paint’ on the sealant. Upon polymerisation, the lightly tinted, purple liquid bonds to the skin, sealing off spaces where bacteria grow. This breathable layer prevents the migration of bacteria through the duration of surgery (Figure 1). The sealant also covers and protects microabrasions created during hair removal. After surgery, the product is intended to be left on the skin and will come off naturally in 3-7 days as the skin exfoliates.
In vitro tests with Integuseal have shown promising results, demonstrating that mean bacterial recovery on human skin is significantly reduced. Bacterial immobilisation tests were conducted with MRSA, Staphylococcus epidermidis, and Bacillus stearothermophilus (to differentiate response from common skin microbes). Application of the sealant was found to reduce the number of organisms recovered from model skin samples by greater than 99%, with various amounts of bacteria applied (08, 2.0, or 4.0 _l/cm2).9 Separate test cases also demonstrated that the recovery of bacteria from model skin incisions was further reduced with the use of Integuseal when the sealant was used in combination with certain existing surgical skin preparation products.
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| Fig 1.b: Environmental SEM of Integuseal® layer on porcine skin model, 150x. Image courtesy of Kimberly-Clark. |
Product trials for the use of Integuseal in orthopaedic and other procedures have been conducted in several European and UK hospitals. Among them was the Eastbourne District General Hospital (East Sussex, UK) where Mr Skyrme is lead consultant orthopaedic surgeon. Describing his trial of the product, Mr. Skyrme explained, “We used the sealant in a range of orthopaedic procedures across the practice spectrum, including primary arthroplasties, revision procedures and several foot surgeries. In terms of usability, the first thing our team noticed about Integuseal was its simple application procedure and the relatively brief period required for it to polymerise. Depending on the area to be covered, application times varied from one to three minutes with drying taking only a further two to five minutes. Once dry, the sealant layer then did not interfere with surgical procedures and the OR staff continued with the application of sterile drapes as usual. Post-operative suturing remained equally unaffected. Interestingly, as an auxiliary benefit Integuseal was found to greatly assist with the binding of surgical and incise drapes. The drying action of the sealant appears to make the drapes more resistant to patient perspiration and loosening, securely fastening them through the duration of the surgery. This was particularly advantageous when working near, or trying to exclude, operatively dirty areas and when applying drapes over areas with more complex contours such as the foot and natal cleft.”
A new tool in the kit
The results achieved with Integuseal in both the pre-clinical in vitro testing and product trials have prompted a strong early uptake of the device in a number of hospitals across Europe taking proactive steps to SSI prevention. Widespread adoption of the new sealant will, however, almost certainly require support from clinical studies as many hospitals maintain a reactive approach to SSI prevention. Infection control practices, however, are constantly evolving in the pursuit of more effective means of protection, often with the most basic and intuitive ideas being the more successful. The use of normothermia, for example, was only proven as an effective technique for SSI prevention in mid-1990’s, yet it is now a widely accepted practice with proven benefits.10
Summarising his experiences with Integuseal and its potential to limit the burdens posed by SSI, Mr Skyrme said, “Given the low-risk nature of the product, its relatively simplistic application, and the current health and economic impacts of SSI in orthopaedic surgeries, its potential benefits should not be overlooked. Data generated from Trusts’ own internal tracking of SSI in orthopaedic procedures will provide a reasonable basis of comparison for ‘before and after’ scenarios in hospitals trialling the sealant. In TKA, THA, and particularly in revision cases, a microbial sealant could significantly decrease the risk of SSI. In future, Integuseal and similar products could become an integral part of routine aseptic and preventative procedure.”
Andrew Skyrme (FRCS, Tr & Orth) is a consultant orthopaedic surgeon at Eastbourne District General Hospital and Uckfield Hospital, specialising in lower limb orthroplasty and foot & ankle surgery.
References
- Health Protection Agency. Mandatory surveillance of surgical site infection in orthopaedic surgery: April 2004 to March 2005. London: Health Protection Agency, October 2005.
- Health Protection Agency. Surgical Site Infection Surveillance in England - Summary of data from October 1997 to December 2003. CDR Weekly, 14(21): 20; May 2004
- Leaper DJ, Van Goor H, Reilly J et al. Surgical site infection – a European Perspective of incidence and economic burden. International Wound Journal1:1–26; 2004
- Ridgeway S, Wilson J, Charlett A et al Infection of the surgical site after arthroplasty of the hip. J. Bone Joint Surg. 87 (6): 844-50; 2005.
- Nationales Referenzzentrum für Surveillance von nosokomialen Infektionen: Modul OP-KISS Referenzdaten. Krankenhaus-Infektions- Surveillance-System (KISS). www.nrz-hygiene.de
- Gallo J, et al. Pathogenesis of prosthesis-related infection. Biomed Papers 147(1), 25-35; 2003
- The European Antimicrobial Resistance Surveillance System. EARSS Annual Report 2004, Sep 2005. ISBN-number: 90-6960-131-1. http://www.rivm.nl/earss
- Centers for Disease Control and Prevention. Draft guidelines for the prevention of surgical site infection, 1998. Federal Registister 1998;63:33168-92.
- Kimberly Clarck internal data
- Kurz A et al. Perioperative Normothermia to Reduce the Incidence of Surgical-Wound Infection and Shorten Hospitalization. N Engl J Med, 334(19): 1209-1216; 1996.
Case Report
Use of a Pre-formed Cement Spacer for Revision THA
Author: Adam Mark Michael Cohen MBBS(Lon) MRCS MSc(Orth Eng)
Specialist Registrar Trauma & Orthopaedics, Eastbourne District General Hospital
Introduction
Revision Total Hip arthroplasty is a demanding sub-speciality of orthopaedic surgery. The development of a deep infection following a Total Hip Replacement is a difficult problem to deal with. Of the many ways in which this situation may be addressed, two stage revision is a popular choice. This involves removal of the whole prosthesis i.e. femoral stem and acetabular cup, and debridement of all infected tissue. A period of antibiotic treatment is also usually commenced in order to attempt eradication of the infection. Other methods which have been used include the use of antibiotic loaded cement beads and cement moulded by the surgeon into a spacer. The principle with use of the spacer is to try to prevent soft tissue contraction in order to make the second stage operation technically easier. This case report describes the use of a pre-moulded antibiotic loaded spacer which has a central steel enforcement rod.
| Figure 1 |
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| Figure 2 |
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| Figure 3 |
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Case Report
A 68 year old female patient presented back to our hospital with a persistent discharge from her hip wound following a routine total hip replacement. The patient has a body mass index in excess of 40. She was initially re-admitted to hospital and underwent re-exploration of the wound. The fascia lata was found to have dehisced and the discharge was arising from the prosthetic hip joint. The patient had had an uncemented Biometric hip arthroplasty 2 weeks prior to the exploration. Microbiological swabs were obtained at the initial exploration, but they produced no growth. The hip joint was washed out but none of the components were changed. The patient was discharged from hospital once the discharge became manageable. She was followed up in the out-patient clinic. Further swabs were obtained at the first out-patient visit. These grew _-haemolytic Group C Streptococcus, sensitive to Erythromycin. At this stage, the patient’s CRP was 158, ESR 68 and WCC 9.4. The patient’s mobility was deteriorating and she was becoming house-bound. She had persistent pain in the right proximal thigh, worse on weight-bearing. Radiographs showed evidence of acetabular loosening (Figure 1 and 2 pre and post acetabular movement).
On the evidence of a probable prosthetic infection, a decision was made with the patient to perform a 2 stage revision arthroplasty.
At surgery, the previous lateral hip wound was reopened and the sinus tract excised. The fascia lata was very adherent to the underlying gluteus medius and vastus lateralis. The Hardinge approach which had been used to perform the Hip Replacement was used to gain access to the joint again. The femoral stem was found to be loose in the metaphyseal region. The acetabular component was completely loose and rotated superiorly within the native acetabulum. Both components were removed. Samples were taken and sent to microbiology. The proximal femoral bone stock was good, but examination of the acetabulum revealed a type IIc (Paprosky classification) defect. All biofilm was removed from the bony surfaces. The femur and acetabulum were pulse lavaged.
A Spacer G XL with a 54 mm head was selected after trialling. The spacer was inserted allowing the implants medial collar to buttress the remaining calcar.
The wound was closed with deep vicryl sutures and interrupted nylon to skin over a redivac drain. The swabs grew Staphlococcus Aureus. The patient was kept on cefuroxime provisionally, and then changed to cefalexin orally as she was allergic to flucloxacillin. She remained on cefalexin for 5 weeks. Her ESR and CRP have gradually come back to within normal limits. Post operative radiographs are shown in figure 3. The patient is now waiting for the second stage of the revision arthroplasty.
Discussion
The development of a periprosthetic infection following total hip arthroplasty is a notoriously difficult problem to address. Generally, the risk of infection following primary THA is quoted as 1%. However, The Scandinavian Arthroplasty registers demonstrates a rate of between 7% and 16%1,2. In 1984, Lidwell et al published an MRC study showing that the use of laminar flow theatres and prophylactic antibiotics could reduce the rate of deep infection3.
Making the diagnosis of a post-operative peri-prosthetic infection may be a great challenge. It is rarely a clear-cut diagnosis and much has been written regarding the most appropriate tests to perform. A recent article by Toms et al aims to update and summarise the diagnostic tests4. Such clinical pointers as delayed wound healing or persistent drainage from the wound site may pre-dispose a patient to a subsequent peri-prosthetic infection. The assessment of ESR and CRP are key indicators of an infection in patients who have no other reason for these tests to be elevated. The diagnosis of periprosthetic infection was straight-forward in this case as both markers were elevated and plain radiographs showed evidence of component movement.
Our patient was morbidly obese and relatively young, and the patient was not keen on antibiotic suppression or girdlestone arthroplasty for treatment. A number of studies have shown that two stage revision arthroplasty consistently provides better results than single stage exchange5,6. The decision to use a cement spacer in this case was to prevent contracture of the soft tissues and theoretically to allow easier mobilisation between stages.
| Figure 4 |
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The Spacer G cement spacer is a preformed stem shaped prosthesis which is specifically designed for implantation at the first stage of a revision arthroplasty for infection (Figure 4). This spacer is manufactured from a cylindrical rod of 316L stainless steel coated with gentamicin bone cement. It allows maintenance of the joint space with the potential for partial weight bearing and hip movement as well as effective release of gentamicin7. The spacer comes in three different sizes with two different stem lengths (standard and extra long) for each head size. The system has the advantage of trialling the appropriate size prior to implantation of the definitive spacer.
Although it was not necessary for the patient in this case report, it may be necessary to add PMMA bone cement to the metaphyseal region to reduce the risk of rotation of the implant within the femoral canal. Rotation of the spacer within the femoral canal could increase the risk of spacer dislocation.
In conclusion, this case study shows that the Spacer G cement spacer may be used effectively in morbidly obese patients. The Spacer G is helpful in maintaining a joint space prior to the second stage of revision arthroplasty for infection and elutes gentamicin at effective levels throughout the treatment period.
References
- Puolakka TJ, Pajamaki KJ, Halonen PJ, et al. The Finnish Arthroplasty Register: report of the hip register. Acta Orthop Scand 2001;72:433-41.
- Lucht U. The Danish Hip Arthroplasty Register. Acta Orthop Scand 2000;71:4330 -9.
- Lidwell OM, Lowbury EJL, Whyte W, et al. Infection and sepsis after operations for total hip or knee-joint replacement: influence of ultra-clean air, prophylactic antibiotics and other factors. J Hygiene 1984;93:505-29
- Elson RA. Exchange arthroplasty for infection: perspectives from the United Kingdom. Orthop Clin North Am 1993:24:761-7
- Garvin KL, Fitzgerald RH Jr, Salvati EA, et al. Reconstruction of the infected total hip and knee arthroplasty with gentamicin-impregnated Palacos bone cement, lnstr Course Lect 1993:42:293-302.
- A D Toms, D Davidson, B A Masri, C P Duncan. The management of peri- prosthetic infection in total joint arthroplasty. Journal of Bone and Joint Surgery. (British volume). London: Feb 2006.Vol.88, Iss. 2; pg. 149, 7 pgs
- E. Bertazzoni Minelli, A. Benini, B.Magnan , P. Bartolozzi. Release of Gentamicin and vancomycin from temporary human hip spacers in two stage revision of infected arthroplasty. Journal of antimicrobial chemotherapy 2004: 53:329-334
Introduction
Shoulder arthroplasty for degenerative diseases has been shown to lead to significant pain relief and improved joint motion 1,2,3. Although it is unknown how many shoulder hemiarthroplasties or total shoulder replacements (TSR) are performed in the UK, the amount of shoulder arthroplasty surgery being performed for osteoarthritis and fractures is increasing. As the number of procedures increases each year, the numbers of complications are therefore likely to rise.
The complexity of revision shoulder surgery remains a technical challenge for even an experienced shoulder surgeon. Revision surgery of failed prosthetic shoulder arthroplasty is rarely required. The indications to revise a shoulder arthroplasty are when a patient complains of shoulder pain, loss of shoulder function or when there is an obvious cause of failure. Critical to the success of revision surgery are the soft tissues, particularly the deltoid and the rotator cuff 4 and the remaining bone stock for component implantation.
The Indications for Revision Surgery
Various complications can necessitate revision surgery. The causes of failure can be surgeon derived : poor choice of an implant for the underlying shoulder condition or lack of surgical experience which can lead to the improper, non-anatomic placement of the shoulder components. Malposition of a primary prosthesis causes pain and stiffness. The stem or glenoid may not be in an anatomically acceptable position and can lead to accelerated failure of the prosthesis. The head may be too big, or the stem too proud which can overstuff the joint and lead to prosthetic instability, a stiff shoulder or even a rotator cuff dehiscence.
Complications of Primary Shoulder Arthroplasty
The commonest early complication following shoulder arthroplasty is accelerated glenoid erosion and painful arthritis which may develop following hemiarthroplasty-only shoulder surgery. In these cases a conversion to a total shoulder arthroplasty by simply replacing the glenoid with a compatible glenoid component is highly effective 5. If this is not possible then a full revision including the stem can be performed.
Prosthetic Instability & Rotator Cuff Tears
Shoulder instability is another early complication that can arise from a non-anatomically positioned glenoid or humeral implant, using an incorrect head size or the malposition of a modular head component on the stem. The stem may be anteverted or the overall humeral component may be implanted to high. Any form of instability following a TSR will lead to glenoid wear in the direction of the instability and early glenoid loosening and failure. With a modular prosthesis the head can be appropriately exchanged, but if the stem is malpositioned a full revision will need to be performed along with the glenoid if necessary.
Acute subscapularis tears may arise due to improper intra-operative surgical releases or closure of the subscapularis tendon. Aggressive post-operative rehabilitation with physiotherapy may also cause an acute rupture of the subscapularis repair. The subscapularis can be torn by overstuffing the joint with a large head which creates tension on the rotator cuff by increasing the lateral offset. A deficient subscapularis causes anterior instability 6 and may require primary repair. If it is irreparable then a pectoralis tendon transfer can be performed.
The function of the rotator cuff is to stabilize the humeral head within the glenoid. Large rotator cuff dehiscence or tears can lead to antero-superior instability. This is not always a symptomatic complication in patients. It can become symptomatic if a patient has had the glenoid replaced and the instability causes superior wear and subsequent loosening. If there is a minimal amount of glenoid wear then the rotator cuff may be repaired or tendon grafts performed if it is irreparable. A latissimus dorsi tendon transfer can be fashioned if the posterior aspect of the rotator cuff is deficient. In the presence of severe rotator cuff insufficiency and a well fixed humeral stem the glenoid component can be removed, leaving the shoulder to function as a hemiarthroplasty. Another treatment option is to revise the shoulder to a reverse prosthesis. The reverse prosthesis has a unique lowered and medialised centre of rotation which increases the moment arm for the deltoid. This biomechanical concept overcomes the problem of the superior migration of the humeral head with rotator cuff deficiency.
Posterior instability may arise if there was significant posterior wear on the glenoid that was not addressed by replacing the glenoid at the time of the primary surgery. In this instance the glenoid will need to be eccentrically reamed anteriorly and replaced, followed by adequate releases of the anterior capsule. In excessively retroverted glenoids or if the version cannot be corrected by eccentric reaming, then a bone graft procedure can augment the posterior glenoid. Excessive glenoid and/or humeral retroversion of a primary TSR also creates posterior prosthetic instability and requires a full component revision. A lax posterior capsule may require plication and any associated rotator cuff tears need repairing. Soft-tissue repair does not always create stability following instability after shoulder arthroplasty. Unfortunately for most patients, component revision is a necessary part of the revision surgery and associated with limited success rates.
Prosthetic Loosening
Although the shoulder is not a weight bearing joint, high loads are still imparted upon it during active ranges of motion. An incorrectly positioned implant, rotator cuff tears or prosthetic instability all affect the gleno-humeral joint reaction forces. Too little muscle tension caused by a small prosthetic head, or too much tension caused by a large prosthetic head, leads to an abnormal humeral head translation and eccentric loading on the glenoid fossa 7,8. This will create increased contact stresses on the articular surfaces of the implant and lead to glenoid wear.
Humeral or glenoid loosening are responsible for one-third of all complications associated with TSR 9. Prosthetic loosening can occur from osteolysis due to polyethylene wear or peri-prosthetic fractures and infection. Glenoid loosening is much more common than humeral aseptic loosening 10. In symptomatic patients it is reasonable to revise the glenoid component. However, if there is inadequate glenoid bone stock to support a glenoid component then this can be bone grafted without a glenoid replacement, with quite satisfactory results for pain relief 4. In the infrequent patients who continue to complain of pain, the glenoid may then be resurfaced with an implant up to a year later.
Humeral stem loosening is rare following either cemented hemiarthroplasty or TSA. It is higher when smooth un-textured stems are used as a press fit rather than being cemented. This is now of historical value, as there are new press-fit textured stems designed for bone in-growth. Removing a cemented stem in the revision setting can be technically demanding but it is almost always possible.
Periprosthetic Fractures & Infection
Post-operative peri-prosthetic fractures which are associated with a loose stem require revision to a long-stemmed implant, and can be used with strut cortical allografts.
Deep infection is most predictably treated by extensive debridement, removal of the prosthesis and parenteral antibiotics followed with six weeks of oral antibiotic therapy (depending on the clinical scenario and the virulence of the organism(s)). A delayed second stage revision may then be possible.
The delay to the second stage implantation can lead to soft tissue contractures of the rotator cuff which can compromise the result of the eventual revision surgery. The use of a humeral cement-antibiotic spacer can help keep an adequate tension within the soft tissue envelope prior to the second stage. The success of revision shoulder arthroplasty is often unpredictable, with 60% of revisions offering satisfactory pain relief and restoration of function. Certainly the results are more successful than excision arthroplasty in active younger patients 11.
Revision Surgery
It is important to identify the exact cause of a failed shoulder arthroplasty, plan the appropriate treatment and also ensure that the expectations of the patient are realistic. Revising a painful shoulder replacement may alleviate the pain but leave the patient with reduced motion or strength. The surgeon must ensure that a patient will be able to comply with the postoperative rehabilitation program to gain a successful outcome. It is not always possible to identify a cause for implant failure until the time of revision surgery when multiple abnormalities are found and will need to be addressed in order to achieve a satisfactory outcome.
Prior to revision surgery a thorough work-up of the patient is usually required. The patient’s general health and fitness must be suitable as revision surgery is often longer and technically more demanding. Plain radiographs which help identify the areas of loosening and the component type in-situ. This enables the surgeon to order the appropriate extraction devices and compatible prosthetic components from the implant company. CT films tell us about the component versions and the amount of glenoid bone stock available for revision. An MRI may tell us about the state of the rotator cuff. If infection is suspected then appropriate blood tests are arranged and a gleno-humeral aspiration is performed for microbiological confirmation.
The Use of Custom-made Implants
The use of custom made implants in shoulder surgery is rare. They are used whenever a great deal of bony resection/debridement needs to be performed or has been previously performed. Examples of this include replacements following tumor excision or in the second stage replacement of an infected joint replacement. If a standard humeral replacement is performed where there is a significant amount of bone loss, then inferior instability will occur as the humeral length is shortened. This leads to a shortened deltoid length and reduced moment arm which will significantly reduce the shoulder function and range of motion. Similar consequences may occur in arthroplasty surgery for acute fractures and re-revisions of previous revision surgery. In these cases custom built humeral prosthesis may be required.
Custom-made prostheses are produced using computer-aided design and technology. The surgeon provides a plan of what exactly is required for the surgery to an appropriate company. Scaled plain radiographs, CT or MRI scans are sent to the manufacturer. The manufacturing company then sends a proposal with a radiographic template overlay which matches the scale of the original X-rays for the surgeon to study. If satisfactory, the implant is then supplied in a sterile condition with the custom instrumentation. Occasionally, the custom prosthesis may undergo further necessary designs to suite a particular case. An example would allow the placement of distal locking screws into a custom humeral stem for added distal fixation in the presence of significant proximal bone loss.
The rheumatoid population poses as a technically difficult group of arthroplasty patients. As a result of their disease they often have small and quite deformed bone morphology requiring the use of custom made implants 12. Figgie et al. used a short-stem humeral component and a metal-backed custom-fit glenoid component with an offset keel to provide maximum coverage of the glenoid surface. Twenty-three patients with inflammatory arthritis and rotator cuff deficiency had undergone 27 custom-fit total shoulder arthroplasties. The five year results have been quite encouraging with decreased incidence of glenoid radiolucency 13.
Advances in adjuvant chemotherapy and radiation therapy, has allowed surgeons to use shoulder preserving implant surgery for malignant tumors, thus drastically reducing the number of amputations. Limb sparing operations are now a viable option in carefully selected patients with malignant bone tumors. Custom made mega-prostheses are used in tumor units for aggressive benign and malignant tumours of the proximal humerus with satisfactory results. The most common tumours are osteosarcomas, followed by giant cell tumours and chondrosarcomas.
Myalhivan et al. reported satisfactory results using 57 custom made implants and 43 patients were continuously disease free at an average follow-up of 5.5 years (range 2–14.5 years). Five patients required revision replacements. The most common complications were proximal subluxation and aseptic loosening. Functional outcome was satisfactory in 78% of cases 14.
The Use of Modular Components
Custom made implants are not necessary in revision surgery where there is less bone loss. This is due to the advent of more modular implants which give the surgeon more flexibility in revision surgery. The humeral stems can come in increasing lengths to help increase the distal fixation in the presence of proximal bone loss which may or may not be used with cement. Modular heads have different heights, as well as diameters and offset, which can help with soft tissue balancing in revision surgery (e.g. Bio-modular BIOMET, Nottingham BIOMET, Global Advantage DEPUY).
Certain prostheses have separate modular humeral bodies and necks which can add extra lengths and even build in different versions on to the fixed stem (Promos Shoulder PLUS Orthopedics, right). This build up of modular components can increase the height of the humeral prosthesis in the presence of bone loss. The ability to remove a modular head from a well fixed fracture stem and change it to a more appropriate head in the setting of a post-arthroplasty traumatic irreparable cuff tear is quite helpful and less invasive. (exchange of a global Fx head to a global advantage CTA head, DEPUY).
Reverse Type Implants
The DELTA Shoulder System (DEPUY, below) was initially developed to restore a stable and pain free joint with improved functional outcome in patients with torn rotator cuffs. The deltoid lever arm is increased by moving the centre of rotation medially and distally so that the deltoid muscle can then efficiently stabilize the articulating surfaces together. Thus, the normal relationship between the scapula and humeral components are reversed. The main uses for these reverse prosthesis are for rotator cuff arthropathy and irreparable rotator cuff tears with glenohumeral instability. The use of this implant is contra-indicated in patients with deltoid dysfunction.
The DELTA Shoulder System comprises of a complete range of modular components. There are different sized hydroxyapatite coated or non-coated stems and long revision stems. There are also different modular proximal stem sections that can accommodate standard and lateralised polyethylene liners. Recently the use of this highly modular implant has been extended to include the management of comminuted proximal humeral fractures 15,16, salvage revision surgery and even proximal humeral tumor 17,18.
The use of the reverse prosthesis in the primary management of proximal humeral fractures is quite debatable at the present time. It is thought that the inferior results from tuberosity malunion or displaced non-unions that occur with conventional hemiathroplasty surgery can be avoided with the use of the reverse prosthesis.The reverse prosthesis can be used when revising a failed conventional hemiarthroplasty in the presence of a massive rotator cuff tear or if the tuberosities have re displaced following fracture surgery.
If revision surgery is performed for failed total shoulder prosthesis then the remaining glenoid bone stock must be appropriate for the implantation of the glenosphere baseplate.
The Anatomical Shoulder Inverse/Reverse system (Zimmer) allows the surgeon to revise a primary hemiarthroplasty or total shoulder arthroplasty into an inverse/reverse shoulder without the need of removing a well fixed cemented or press-fit stem. The Trabecular Metal Reverse Shoulder System (Zimmer) allows the same option but with trabecular stem biological ingrowth potential.
The results are less predictable and the complication and revision rates are higher in patients undergoing revision surgery with the DELTA (Depuy) prosthesis when compared to those patients undergoing a primary DELTA (Depuy) procedure for a rotator cuff tear arthropathy (19). It has been suggested that the reverse total prosthesis should be reserved for the treatment of very disabling shoulder arthropathy with a massive rotator cuff rupture, and it should be used exclusively in patients who are over seventy years old with low functional demands 20.
The current climate for shoulder arthroplasty surgery is exciting and varied, offering the surgeon a wide range of implants to meet his/her every need. Revision shoulder surgery or complex primary surgery is a major undertaking for both the patient and surgeon. With the new development of modularity and interchangeable parts for implanted stems the future does hold bright for revision surgery.
References
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- Mayilvahanan N, Paraskumar M, Sivaseelam A,Natarajan S. Custom mega-prosthetic replacement for proximal humeral tumours. International Orthopaedics.2006;30(3):158-162.
- Sirveaux F, Roch O, Raphoz A et al. Hemiarthroplasty versus inversed prosthesis in the treatment of proximal humerus fractures: a prospective randomized study in the elderly. Presented at the 17th Congress of the European Society for surgery of the Shoulder and Elbow (ESSE-SECEC) Hedelberg, Germany, 2003.
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- Boileau P, Watkinson D, Hatzidakis AM, Hovorka I. Neer Award 2005:The Grammont reverse shoulder prosthesis:results in cuff tear arthritis, fracture sequelae and revision arthroplasty. JSES.2006;15(5):527-40.
- Guery J, Favard L, Sirveaux F, Oudet D, Mole D, Walch G.Reverse total shoulder arthroplasty.Survivorship analysis of eighty replacements followed for five to ten years. J Bone Joint Surg Am. 2006 Aug;88(8):1742-7.
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