An intraoperatively moulded PMMA prostheses like spacer for two-stage revision of infected total knee arthroplasty

We report a series of 16 consecutive total knee arthroplasty (TKA) revision procedures for deep infection, treated with a newly developed intraoperatively moulded PMMA cement-prostheses-like spacer (CPLS). The standard treatment consisted of a two-stage protocol with initial explantation of the infected components combined with radical debridement, followed by implantation of a temporary cement spacer and final reimplantation of a new TKA. A sterilizeable Teflon tapered aluminium mould was developed for production of a custom made CPLS during the intervention. Stable implantation of the CPLS was achieved with a second cementation, allowing for correct alignment and ligament balancing. The spacer remained 3.5 months on average until reimplantation of a TKA occurred. At time of reimplantation, patients had an average KSS score of 84.44 points with an average flexion capacity of 102°. There was no recurrent infection during the study period of minimum 2 years. With this new technique, a low friction articulation with good stability, high comfort and a better range of motion compared to handcrafted spacers was achieved. The use of this spacer is a time sparing, cheap and convenient option in 2-stage TKA revision.     

Measurements of in vivo intra-articular gentamicin levels from antibiotic loaded articulating spacers in revision total knee replacement

Previous in vitro studies have found high levels of antibiotic release in the days immediately following implantation of antibiotic loaded articulating spacers. However there are relatively few data describing the elution profile beyond this immediate period. This study was designed to measure if gentamicin levels continue to be clinically therapeutic after an extended period following in vivo implantation. Twelve patients received a gentamicin loaded articulating spacer between a 1st and 2nd stage revision total knee arthroplasty. At the 2nd stage procedure synovial fluid and blood samples were collected and assayed for the presence of gentamicin. The second stage revision occurred at a median of 99 days following spacer insertion. The median intra-articular gentamicin levels were 0.46 mg/L (0.24 to 2.36 mg/L) which would be considered therapeutic. There were no cases of reinfection. In this study, preformed articulating spacers containing gentamicin provided therapeutic concentrations in the synovial fluid surrounding the joint throughout the period of implantation. These data confirm the observations from in vitro studies, where a prolonged elution profile was observed for such spacers.     

Clinical outcomes of two-stage total knee arthroplasty using articulating cement spacer in patients with infected arthritic knee: A comparison with arthroscopic surgery

BackgroundThe aim of this study was to compare the functional outcomes and recurrence rate of infection between patients who underwent arthroscopic surgery and two-stage total knee arthroplasty (TKA) for infected arthritic knees.MethodsA retrospective analysis was conducted on 52 patients (52 knees) with advanced knee joint arthritis who underwent arthroscopic surgery or two-stage TKA using articulating cement spacer (ACS) for knee joint infection between January 2009 and November 2013. Of the 52 patients (52 knees), 38 and 14 patients underwent arthroscopic surgery (AS group) and two-stage TKA using ACS (ACS-TKA group), respectively. Patient-reported outcomes (Knee Injury and Osteoarthritis Outcome Score (KOOS) and EuroQol-Visual Analog Scales (EQ-VAS)); range of motion; and recurrence rate of infection were evaluated.ResultsRecurrence of infection was observed in 7/38 patients who underwent arthroscopic surgery, all of whom received two-stage TKA using ACS. Regarding the functional outcomes of the ACS-TKA group obtained before conversion to TKA and those of the AS group obtained six months after arthroscopic surgery, the former group had better outcomes for KOOS pain, KOOS activities of daily living, KOOS quality of life, and EQ-VAS. Regarding the functional outcomes of the ACS-TKA group obtained during the last follow-up and after conversion to TKA and those of the AS group who underwent TKA after arthroscopic surgery, no significant between-group differences were observed. The infection recurrence rate was higher in the AS than in the ACS-TKA group.ConclusionsConsidering infection control and functional outcomes, two-stage TKA using ACS can be an effective alternative treatment for patients with infected arthritic knees.     

Experimental evaluation of the biomechanical performances of a PMMA-based knee spacer

Infection of knee prostheses is still one of the major concerns of the reliability over time of these implantable devices. The preferred treatment of this condition has turned out to be the use of a knee spacer in a two-stage reimplantation technique. The advantages of this technique associated with the use of a mobile spacer lies both in the possibility for the patient to move during the interim period, thus decreasing the risk of muscle contracture due to immobilisation, as well as in the ability to release antibiotics directly to the site of infection. The evaluation of the biomechanical properties of new mobile spacers preformed in three different sizes has been carried out subjecting the spacers to i) cyclic tests on a knee simulator for 500,000 walking cycles, ii) constraint tests in medio-lateral, antero-posterior and internal-external directions, iii) fatigue tests on the tibial tray. Particular attention was addressed to the evaluation of the mechanical resistance of the devices, to the quantity of wear debris produced during the tests and to the extent that such debris was influenced by the test parameters and geometrical dimensions of the spacers themselves. Results showed no sign of failure for any of the tested spacers, the constraint and fatigue behaviours were similar to those shown by a total knee prosthesis and the amount of debris turned out to be directly correlated to the size of the devices: in conclusion, the devices showed a good level of mechanical performance and, consequently, a sufficiently high degree of suitability for clinical use.     

Management of posttraumatic extensive bone loss and osteomyelitis using a customized articulating knee spacer

The combination of infection and extensive bone loss presents a challenging reconstructive situation for surgeons performing total knee arthroplasty (TKA). We describe the case of a patient that suffered a grade III open fracture of the tibial plateau and developed a recurrent infection which resulted in loss of the proximal 15 cm of the tibia. Our solution was interim use of custom-made articulating, antibiotic-impregnated spacers followed by a structural tibial allograft and hinged TKA. At 2-year follow-up the patient is infection-free and is able to ambulate without the use of support.     

Custom-made hinged spacers in revision knee surgery for patients with infection,bone loss and instability

Polymethyl methacrylate spacers are commonly used during staged revision knee arthroplasty for infection. In cases with extensive bone loss and ligament instability, such spacers may not preserve limb length, joint stability and motion. We report a retrospective case series of 19 consecutive patients using a custom-made cobalt chrome hinged spacer with antibiotic-loaded cement. The “SMILES spacer” was used at first-stage revision knee arthroplasty for chronic infection associated with a significant bone loss due to failed revision total knee replacement in 11 patients (58%), tumour endoprosthesis in four patients (21%), primary knee replacement in two patients (11%) and infected metalwork following fracture or osteotomy in a further two patients (11%). Mean follow-up was 38 months (range 24–70). In 12 (63%) patients, infection was eradicated, three patients (16%) had persistent infection and four (21%) developed further infection after initially successful second-stage surgery. Above knee amputation for persistent infection was performed in two patients. In this particularly difficult to treat population, the SMILES spacer two-stage technique has demonstrated encouraging results and presents an attractive alternative to arthrodesis or amputation.     

Küntscher nails with static cement spacer: A simple technique in periprosthetic knee infections with massive bone loss and instability

BackgroundTwo-stage revision for periprosthetic knee infection is challenging in cases of massive bone loss and instability. The present study aims to describe our experience with an alternative technique of reinforced cement spacer, usually necessary in these situations, focusing on its advantages and clinical results.MethodsWe retrospectively identified all patients who underwent a two-stage revision for periprosthetic knee infection using two intramedullary Küntscher nails as reinforcement from January 2010 to September 2018. From each medical record, we extracted the type of explanted prosthesis, isolated micro-organism, number of cement spacers before index procedure (and related episodes of spacer dislocation) and final treatment.ResultsTwelve patients were identified, mean age of 64.0 years (range 39–85). In four of them, the reinforced spacer was used twice for persistent infection, with a total of 16 procedures performed and no cases of dislocation. Ten patients were finally treated with reimplantation or arthrodesis with intramedullary nails, whereas an above-knee amputation was necessary for two patients. Infection was eradicated in 10 patients out of 12 (83%) at a mean follow up of 34.3 months (range 10–62).ConclusionsThis technique is an effective alternative to traditional spacers in cases of massive bone loss, producing a mechanically stable joint and preserving adequate tissue tensions. The construct is technically easy to perform and, not less importantly, to remove during stage 2. Further studies, with larger groups, are necessary to determine its validity.     

Gait analysis in patients with a preformed articulated knee spacer

Two-stage revision is one of the most widely accepted procedures to eradicate infection and restore function in infected knee prosthesis; while the use of an articulated spacers is advocated by many as a means to preserve function between stages, no data are available regarding gait parameters after spacer implant. The aim of present study was to assess and compare the gait parameters of patients with articulated knee spacers with a normal reference population and with the sound limb. Computerised gait analysis, was performed 8 to 14 weeks after the infected knee prosthesis had been removed and a preformed, articulated, knee spacer had been implanted, in 10 consecutive patients. Kinematic data show a mean gait velocity reduction of 70% and a decrease of the range of motion of the operated knee of 59%, compared with controls. While ground reaction forces were only slightly reduced, frontal and sagittal moments and calculated powers around the affected knees were near zero or zero. Our findings point out the ability of a preformed articulated spacer to preserve, although reduced, the normal gait parameters and joint range of motion and the capacity of the human body to provide useful postural modifications, even in the absence of the proprioceptive input from a normal knee or from a traditional total knee replacement.     

Success rates,characteristics, and costs of articulating antibiotic spacers for total knee periprosthetic joint infection

Background

The optimal type, characteristics, and success rates of articulating antibiotic spacers used during total knee arthroplasty (TKA) periprosthetic joint infection (PJI) have not been well defined in a single series. We sought to (1) determine the success rate for three unique spacer constructs and (2) evaluate any microbiological, surgical, or patient characteristics that would influence the success rate.

Two-stage TKA for tuberculosis septic arthritis of the knee masquerading as pigmented villonodular synovitis: A case report

A 25-year-old female presented with left knee pain following arthroscopic synovectomy for presumed pigmented villonodular synovitis (PVNS). Radiographs and magnetic resonance imaging demonstrated tricompartmental arthritic changes. She underwent a two-stage procedure first involving antibiotic spacer implantation, followed 1 week later by spacer removal and definitive total knee arthroplasty (TKA) once initial intraoperative culture results were negative. Subsequent cultures confirmed tuberculosis septic arthritis. Repeat evaluation 1 year postoperatively showed no complications and patient satisfaction with left knee function. This is a unique case report in the United States describing 1-year outcomes following staged TKA for tuberculosis septic arthritis masquerading as PVNS.     

How I do it — Second stage revision total knee arthroplasty

BackgroundInfection is a potentially devastating complication following primary total knee arthroplasty, and the traditional gold-standard treatment for chronic prosthetic joint infection has been in the form of a two-stage revision total knee arthroplasty. This involves a first stage – removal of all implants and infected material, with implantation of a temporary spacer – followed by a second stage which includes reimplantation with a definitive prosthesis.IndicationsAlthough the outcomes of single-stage and two-stage revision arthroplasty surgeries are similar, there are certain indications such as atypical or more virulent organisms, patient factors and soft tissue factors that would favour a two-stage approach.Surgical techniqueThe second stage revision procedure consists of explantation of the spacer with a debridement and synovectomy. Further samples are sent for microbiological analysis. Once the surgical field is clean and lavaged, the definitive prosthesis is implanted.ConclusionsA second stage revision total knee arthroplasty is a reliable procedure for the treatment of chronic prosthetic joint infection. There is a significant re-revision rate, predominantly due to recurrent deep infection.     

Knee arthrodesis with a press-fit modular intramedullary nail without bone-on-bone fusion after an infected revision TKA

IntroductionKnee arthrodesis can be an effective treatment after an infected revision Total Knee Arthroplasty (TKA). The main hypothesis of this study is that a two-stage arthrodesis of the knee using a press-fit, modular intramedullary nail and antibiotic loaded cement, to fill the residual gap between the bone surfaces, prevents an excessive limb shortening, providing satisfactory clinical and functional results even without direct bone-on-bone fusion.Material and methodsThe study included 22 patients who underwent knee arthrodesis between 2004 and 2009 because of recurrent infection following revision-TKA (R-TKA). Clinical and functional evaluations were performed using the Visual Analogue Scale (VAS) and the Lequesne Algofunctional Score. A postoperative clinical and radiographical evaluation of the residual limb-length discrepancy was conducted by three independent observers.ResultsVAS and LAS results showed a significant improvement with respect to the preoperative condition. The mean leg length discrepancy was less than 1 cm. There were three recurrent infections that needed further surgical treatment.DiscussionThis study demonstrated that reinfection after Revision of total knee Arthroplasty can be effectively treated with arthrodesis using a modular intramedullary nail, along with an antibiotic loaded cement spacer and that satisfactory results can be obtained without direct bone-on-bone fusion.     

The use of the knee joint-line balancer to control patella position in revision total knee arthroplasty

In revision total knee arthroplasty (TKA), control of the patellar height and the joint line is difficult. Therefore, we developed an adjustable flexion-extension spacer, the Knee Joint-line Balancer (KJB(R)). This device simulates femur component sizes, polyethylene sizes, the joint-line level, and distal femur wedges. The goal of this study is to evaluate the use of an adjustable knee spacer to control patellar height and joint-line during revision total knee surgery. The subjects of the study were the first 10 consecutive patients who had undergone revision of a primary TKA where the KJB was used. A reference group composed of the last 10 patients treated without the use of the KJB was also evaluated. The joint-line position and the patellar height were determined before and after revision TKA. The method described by Figgie et al. was used. The patellar height in the reference group averaged 7.7 mm. Seven of 10 patients had a patella baja, and two of these patients had patellar impingement. One patient needed a proximalisation of the tuberositas. The patellar height in the KJB group averaged 14.6 mm after revision, with only one patient having a patella baja. This new device, adjustable kneespacer for revision TKA ("the KJB"), seems to provide better control of the patellar position in total knee revision.     

Development of a reinforced PMMA-based hip spacer adapted to patients’ needs

Two-stage reimplantation using an interval hip prosthesis (spacer) of antibiotic-impregnated bone cement has become a well-accepted method to eradicate infection and prevent limb shortening. However, custom made as well as prefabricated spacers share a weakness of limited strength and hence several fractures of spacers have been observed, even for partial weight bearing. The purpose of this study was therefore to improve the strength of the custom made spacer, used at the Orthopaedic Department of the Saarland University Hospital (Germany). As the material strength of bone cement is limited, several reinforced spacers with a metal core consisting of titanium grade two have been developed and investigated. Loading procedure was close to the ISO 7206/4, though small adaptation was made. An inserted rod of titanium grade two increased the collapse load up to 1000–1300 N, but considering a maximum expected load of about three times the body weight, still below the required value. A “full-stem” reinforced spacer, i.e. spacer with a titanium endoskeleton and a minimum of 2–3 mm PMMA-coating in order to assure drug release, provides a mobile and functional joint through the treatment course. Those with 8 mm thickness of titanium endoskeleton endured up to one million load cycles in a load range of 300–2300 N. To give further support for individual cases a meaningful S–N curve for this device was determined.     

How I do it: 1st stage revision TKA

This article covers the key steps and decisions that we make when performing a 1st-stage revision Total Knee Arthroplasty (TKA) at the Avon Orthopaedic Centre and includes more detailed technique and tips regarding how we make our spacers.The first stage of a two-stage protocol should be done in a stable patient with information about the organism, and with the option of plastic surgery flap coverage if required. It should ideally be performed in the unit that is going to perform the second stage, and the operation note should document the soft-tissues, bone loss and extensor mechanism issues that will influence planning for the second stage. Nothing will make up for a bad debridement, so we focus on this as the key step for infection clearance. Infection clearance is equivalent between mobile and static spacers, but patients generally prefer having the better mobility and function of a mobile spacer. We recommend a mobile spacer, unless there is compromise to ligaments or extensor mechanism, or if bone loss is large. Whichever spacer you use, it should aim to: deliver appropriate antibiotics; allow stability, pain relief and some function and weight-bearing prior to the second stage. Doing a good technical job with the spacer is important because you do not want complications with the spacer to cause harm or necessitate a return to theatre or re-operation sooner than planned. Ideally the second stage should be performed when the surgeon & MDT team deem it appropriate clinically and when the patient is fit and ready for further surgery.     

Systematic review: The safety of intra-articular corticosteroid injection prior to total knee arthroplasty

BackgroundUp to 30% of patients undergoing total knee arthroplasty (TKA) have received intra-articular corticosteroid injections prior to surgery. Debate exists as to whether such injections increase the rate of post-operative infection. Given that deep infection is a disastrous complication, a systematic review of the literature was undertaken to evaluate the safety of intra-articular corticosteroid injections given prior to TKA. Other features of corticosteroid use are also discussed including mechanism of action and optimal dosage.MethodsUsing PRISMA guidelines, EMBASE, CINAHL and MEDLINE databases were searched using the search terms ‘total knee arthroplasty’, ‘replacement’, ‘corticosteroid’, ‘steroid’, ‘infection’, ‘safety’, and relevant articles critically appraised. The Newcastle-Ottawa Scale was used to assess for bias.ResultsNo level one or two studies were available for review. Two retrospective case control studies and two cohort studies (level three evidence) which specifically evaluated the risk of infected TKA in association with pre-operative steroid injection were reviewed: three showed that prior steroid injection was not associated with increased infection rates; one article showed that prior steroid injection was associated with a significantly increased risk of deep infection post-TKA.ConclusionClinicians commonly administer steroid injections to patients who are candidates for TKA but may be unaware of the potential long term complications. The included studies were underpowered and at risk of selection bias and only one study demonstrated an increased risk of infection post-operatively. We recommend that further research is required to evaluate the safety of steroid injection prior to TKA.Level of evidence: III     

Do spacer blocks accurately estimate deformity correction and gap balance in total knee arthroplasty? A prospective study with computer navigation

BackgroundSpacer blocks are used commonly in knee arthroplasty to estimate gaps and ligament balance. Their use continues along with modern technology despite dearth of literature regarding their accuracy and reliability. This prospective study aims to determine the difference in values of gap and balance measurements between spacers and trials in computer assisted TKA.Methods50 patients with moderate varus deformity of <20° undergoing primary TKA were recruited for this prospective study. After navigation assisted cuts and requisite ligament release, gaps and balance were recorded in extension and 90° flexion with spacer block followed by implant trials.ResultsThere were 33 females and 17 males with average BMI of 28.2 ± 5kg/m². The average preoperative flexion deformity was 6.5° ± 4.4° and varus deformity was 8.2° ± 3.8°. Average difference of deformity in sagittal plane in extension between spacer and trial was 6.2° which was statistically significant (p = 0.001) implying that knee achieves more extension with spacer blocks as compared to trials because the blocks do not have posterior offset of the condyles. However, there was no difference between values of soft tissue balance and coronal plane correction between spacer blocks and trials in extension and 90° flexion (p > 0.05).ConclusionSpacer blocks do not estimate extension space accurately with knee achieving 6.2 more flexion with trials as compared to spacer blocks when assessed for sagittal plane correction in extension. Spacer blocks should pass in easily in extension to avoid any flexion deformity when the actual trials are inserted.     

Short-course antibiotics for prosthetic joint infections treated with prosthesis retention

The purpose of the present study was to evaluate the significance of shortening the antibiotic treatment duration in prosthetic joint infections (PJI) treated with debridement, antibiotics and implant retention (DAIR). In April 2006 we shortened the total antibiotic treatment duration in total knee arthroplasty (TKA) PJIs from 6 months to 3 months and in total hip arthroplasty (THA) PJIs from 3 months to 2 months. All patients with TKA or THA PJI treated with DAIR between February 2001 and August 2009 were reviewed retrospectively. There were 132 patients treated with DAIR, of whom 86 (65%) completed the antibiotic therapy and were therefore eligible for comparison concerning the length of antibiotic treatment. There were 32 (37%) THA and 54 (63%) TKA PJIs in the comparison. The treatment succeeded in 34 (89.5%) patients treated with longer antibiotic treatment and in 42 (87.5%) of those treated with shorter antibiotic treatment (p 0.78). Our conclusion is that if the patient completes the antibiotic therapy, treatment duration of 3 months in TKA PJIs and 2 months in THA PJIs is as good as longer antibiotic treatment of 6 months or 3 months, respectively, in patients treated with DAIR.     

Complications after spacer implantation in the treatment of hip joint infections

The aim of this retrospective study was to identify and evaluate complications after hip spacer implantation other than reinfection and/or infection persistence.Between 1999 and 2008, 88 hip spacer implantations in 82 patients have been performed. There were 43 male and 39 female patients at a mean age of 70 [43 - 89] years. The mean spacer implantation time was 90 [14-1460] days. The mean follow-up was 54 [7-96] months. The most common identified organisms were S. aureus and S. epidermidis. In most cases, the spacers were impregnated with 1 g gentamicin and 4 g vancomycin / 80 g bone cement.The overall complication rate was 58.5 % (48/82 cases). A spacer dislocation occurred in 15 cases (17 %). Spacer fractures could be noticed in 9 cases (10.2 %). Femoral fractures occurred in 12 cases (13.6 %). After prosthesis reimplantation, 16 patients suffered from a prosthesis dislocation (23 %). 2 patients (2.4 %) showed allergic reactions against the intravenous antibiotic therapy. An acute renal failure occurred in 5 cases (6 %). No cases of hepatic failure or ototoxicity could be observed in our collective. General complications (consisting mostly of draining sinus, pneumonia, cardiopulmonary decompensation, lower urinary tract infections) occurred in 38 patients (46.3 %).Despite the retrospective study design and the limited possibility of interpreting these findings and their causes, this rate indicates that patients suffering from late hip joint infections and being treated with a two-stage protocol are prone to having complications. Orthopaedic surgeons should be aware of these complications and their treatment options and focus on the early diagnosis for prevention of further complications. Between stages, an interdisciplinary cooperation with other facilities (internal medicine, microbiologists) should be aimed for patients with several comorbidities for optimizing their general medical condition.