Aims

Despite numerous studies on periprosthetic joint infections (PJI), there are no robust data on the risk factors and timing of metachronous infections. This study was performed to answer the following questions: 1) Is there any difference of manifestation time of metachronous PJIs between different localizations of multiple artificial joints? 2) Can we identify any specific risk factor for metachronous PJIs for different localizations of multiple artificial joints?

Aim

The prevalence of unexpected positive cultures (UPC) in aseptic revision surgery of the joint with a prior septic revision procedure in the same joint remain unknown. The purpose of this study was to determine the prevalence of UPC in aseptic revisions performed in patients with a previous septic revision in the same joint. As secondary outcome measure, we explore possible risk factors associated with UPC and the re-revision rates.

Arthrofibrosis is a relatively frequent complication after total knee arthroplasty. Although stiffness after total hip arthroplasty (THA), because of formation of heterotopic ossification or other causes, is not uncommon, to the authors’ best knowledge, arthrofibrosis after THA has not been described. The aim of this study is to describe the arthrofibrosis of the hip after primary total hip arthroplasty using an established clinical and histological classification of arthrofibrosis.

We retrospectively examined all patients who were histologically confirmed to have arthrofibrosis after primary THA during revision surgery by examination of tissue samples in our clinic. Arthrofibrosis was diagnosed according to the histopathological SLIM-consensus classification, which defines seven different SLIM types of the periimplant synovial membrane. The SLIM type V determines the diagnosis of endoprosthesis-associated arthrofibrosis.

The study population consists of 66 patients who were revised due to arthrofibrosis after primary THA. All patients had a limitation in range of motion prior to revision with a mean flexion of 90° (range from 40 to 125), mean internal rotation of 10° (range from 0 to 40) and mean external rotation of 20° (range from 0 to 50). All patients had histological SLIM type V arthrofibrosis, corresponding to endoprosthesis-associated arthrofibrosis. Histological examination revealed that seven patients (10.6%) had particle-induced and 59 patients (89.4%) had non-particle-induced arthrofibrosis.

This is the first decription of endoprosthetic-associated arthrofibrosis after primary THA on the basis of a well-established histological classification. Our study results could enable new therapeutic and diagnostic opportunities in patients with such an arthrofibrosis. Surgeons should keep arthrofibrosis as a possible cause for stiffness and pain after primary total hip arthroplasty in mind. Level of evidence Diagnostic study, Level of Evidence IV

Thorsten Gehrke and Lara Althaus contributed equally to the writing of this manuscript.

Revision total hip arthroplasty (THA) is a challenging procedure and the removal of well-fixed femoral stems can be compounded by several pitfalls. In such cases, several removal techniques have been presented in the literature. The most commonly used techniques are the transfemoral osteotomy presented by Wagner and the extended trochanteric osteotomy (ETO) described by Younger et al. Both techniques allow the surgeon to have better intraoperative exposure of the fixation surfaces of the solid femoral stems. However, the complication rates such as non-union should not be underestimated. Therefore, it is always a good decision to avoid an ETO if alternative techniques exist. The endofemoral surgical technique is an alternative method for the removal of well-fixed cemented and cementless femoral stems. Tips and tricks of the endofemoral technique for the removal of well-fixed femoral stems are presented.

Ceramic bearings are currently the most widely used alternative to metal-on-polyethylene bearings in total hip arthroplasty (THA). A workgroup at International Consensus Meeting (ICM) analyzed the potential link between the type of bearing surface and the subsequent periprosthetic joint infection (PJI), and found a higher incidence of PJI when using a metal-on-metal (MoM) bearing surface. A potential reason is that the failure of a MoM bearing surface can result in adverse local tissue reactions (ALTR), which might provide a favorable environment for bacterial proliferation.

In the last few years, several observational studies including national registries, showed that metal-on-polyethylene (MoP) bearing surfaces are associated with a higher rate of infection following total hip arthroplasty (THA) compared to ceramic bearings, in particular with the use of ceramic-on-ceramic bearing (CoC) surfaces.

After adjusting for selection bias and various confounding factors, patients treated with ceramic bearings experienced reduced risk of infection and MoP bearing surface is an independent risk factor correlating with higher incidence of PJI. The meta-analysis by Lee et al. comparing MoM with CoC cementless THA confirmed that the MoM is associated with a significantly higher revision rate than CoC group for any reason as well as for PJI. Furthermore, initial in-vitro studies have shown lower bacterial biofilm formation on ceramic bearing surfaces. Summarizing the current literature, ceramic bearings are associated with a lower risk of infection following THA.

Total hip arthroplasty has become one of the most successful orthopaedic procedures with long-term survival rate. An ever-increasing acceptance of the potential longevity of THA systems has contributed to an increasing incidence of THA in younger and more active patients. Nowadays, especially in younger patients, cementless THA is the favored method worldwide.

Since the first cementless THA in late 1970s, many implant designs and modifications have been made. Despite excellent long-term results for traditional straight cementless stems, periprosthetic fractures or gluteal insufficiency are still a concern. For instance, as reported in a meta-analysis by Masonis and Bourne, the incidence of gluteal insufficiency after THA varies between 4% and 22%.

In contrast, the flattened lateral profile of the SP-CL^® anatomical cementless stem can protect the greater trochanter during the use of cancellous bone compressors and can avoid gluteal insufficiency after THA. Another benefit of this stem design is the rotational stability and the natural load transfer due to the anatomical concept. In this context, we report our experiences using the SP-CL^® anatomical cementless stem. The study group consists of 1452 THA cases (850 male, 602 female) with an average age of 62 years (range 25–76 years). After a mean follow-up of 20 months, in seven cases (0.5%) a stem exchange was necessitated. The reason for stem revision was periprosthetic fracture in 4 cases (0.3%) and periprosthetic joint infection in three cases (0.2%). In five patients, hip dislocation and in four patients migration of the stem occurred. However, stem exchange was not required in those cases.

In conclusion, the SP-CL^® anatomical cementless stem has excellent short-term results.

Introduction

Despite several preventive strategies, periprosthetic joint infection (PJI) following total joint arthroplasty (TJA) is still a devastating complication. Early diagnosis and appropriate treatment are crucial to achieve successful infection control, but challenging since there is no test with 100% sensitivity and 100%. Therefore, several national and international guidelines include synovial analysis of joint aspirates as important diagnostic criteria, but cut-off levels for synovial cell count (CC) and polymorphonuclear (granulocyte) percentage (PMN%) are still debatable. The current investigation was performed to analyze the overall accuracy and optimal cut-off of synovial CC and PMN% following total knee (TKA) and total hip arthroplasty (THA).

Femoral revision after cemented total hip arthroplasty (THA) might include technical difficulties, following essential cement removal, which might lead to further loss of bone and consequently inadequate fixation of the subsequent revision stem. Bone loss may occur because of implant loosening or polyethylene wear, and should be addressed at time of revision surgery. Stem revision can be performed with modular cementless reconstruction stems involving the diaphysis for fixation, or alternatively with restoration of the bone stock of the proximal femur with the use of allografts.

Impaction bone grafting (IBG) has been widely used in revision surgery for the acetabulum, and subsequently for the femur in Paprosky defects Type 1 or 2. In combination with a regular length cemented stem, impaction grafting allows for restoration of femoral bone stock through incorporation and remodeling of the proximal femur. Cavitary bone defects affecting the metaphysis and partly the diaphysis leading to a wide femoral canal are ideal indications for this technique. In case of combined segmental-cavitary defects a metal mesh is used to contain the defect which is then filled and impacted with bone grafts. Cancellous allograft bone chips of 2 to 4 mm size are used, and tapered into the canal with rods of increasing diameters. To impact the bone chips into the femoral canal a dummy of the dimensions of the definitive cemented stem is inserted and tapped into the femur to ensure that the chips are firmly impacted. Finally, a standard stem is implanted into the newly created medullary canal using bone cement. To date several studies from Europe have shown favorable results with this technique, with some excellent long-term results reported.

Advantages of IBG include the restoration of the bone stock in the proximal femur, the use of standard length cemented stems and preserving the diaphysis for re-revision. As disadvantages of the technique: longer surgical time, increased blood loss and the necessity of a bone bank can be mentioned.

The treatment of extensive bone loss and massive acetabular defects is a challenging procedure, especially in cases with concomitant pelvic discontinuity (PD). Pelvic discontinuity describes the separation of the ilium proximally from the ischio-pubic region distally. The appropriate treatment strategy is to restore a stable continuity between the ischium and the ilium to reconstruct the anatomical hip center. Several treatment options such as antiprotrusio cages, metal augments, reconstruction cages with screw fixation, structural allograft with plating, jumbo cups, oblong cups and custom-made triflange acetabular components have been described as possible treatment options. Cage and/or ring constructs or acetabular allograft are commonly used techniques with unsatisfactory results and high failure rates. More favorable results have been presented with custom triflange acetabular components (CTAC), although the results are still unsatisfactory. Three-dimensional printing technology (3DP) has already become part of the surgical practice. In this context, preliminary clinical and radiological results using a 3D-printed custom acetabular component in the management of extensive acetabular defects are presented. The overall complication rate was 33.3 %. In one out of 15 patients (6.6 %), implant-associated complication occurred revealing an overall implant-associated survival rate of 93.3%. The 3D-printed custom acetabular component suggests a promising future, although the manufacturing process has high costs and the complication rate is still high.

Periprosthetic joint infection (PJI) is one of the most feared complications following total knee arthroplasty (TKA). Despite improved peri-operative antibiotic management and local antibiotic-loaded bone cement PJI is reported in about 0.5–1.9 % of primary knee replacement. In case of revision knee arthroplasty the infection rate even occurs at about 8–10 %. Depending on an acute or late PJI several surgical methods are used to treat the infection. However, suffering of a late PJI, the only surgical procedure remains the exchange of the TKA in combination with a radical debridement and removal of all foreign material.

In order to achieve complete debridement of the joint, the soft tissue must be radically excised. Frequently, the debridement of the posterior capsule causes severe difficulties, therefore it might be necessary to resect the collateral ligaments to be able to reach the posterior parts of the capsule. But this necessitates the use of a higher level of constraint such as a rotating or total hinge and fully cemented long stemmed revision implants. Furthermore, due to the cemented stems, a sufficient amount of antibiotic-loaded cement may be delivered to the bone as topical therapy.

Up to now, several studies have shown excellent functional long-term results for hinge knee prostheses after PJI and a very good infection control rate.

Advantages of the hinge knee prosthesis in cases of PJI are the opportunity for a complete debridement especially while addressing the posterior capsule after resection of the collateral ligaments and for delivering antibiotic-loaded bone cement at the stems of the prosthesis for topic therapy. Disadvantages are the need for a higher level of constraint and a possible higher blood loss due to the radical debridement.

Total joint arthroplasty (TJA) is one of the most successful procedures in orthopaedics. Despite the excellent clinical and functional results, periprosthetic joint infection (PJI) following TJA is a feared complication. For instance, the reported PJI rate after primary total knee arthroplasty is about 0.5–1.9%. In general, prevention of periprosthetic joint and surgical site infections is of utmost importance.

This can be reduced by strict antisepsis, adequate sterilization of the surgical instruments and meticulous surgical technique. An indisputable role in prevention of SSI in TJA has been the use of peri-operative systemic antibiotic prophylaxis. The most common recommended antibiotics for prophylaxis in TJA are cefazolin or cefuroxime. In contrast, routine use of commercial antibiotic-loaded bone cement (ALBC) in primary total joint arthroplasty is still a concern of open debate. The use of antibiotic-loaded bone cement delivers a high concentration of antibiotics locally and can decrease the infection rate, which is supported by several studies in the literature. In this context, we present the pros of routine use of commercial antibiotic-loaded bone cement.

The presence of obesity has negative influence on the progress of osteoarthritis and increases the risk of undergoing a primary THA at an earlier age. However, the correlation of BMI and the risk for postoperative complications, revision surgery and infection rate is still controversial. In the largest cohort to this date, we used the German insurance claims database to evaluate the correlation of BMI and the risk of postoperative complications, mortality and revision rates following primary THA.

Using nationwide billing data of the German health-care insurance for inpatient hospital treatment, we identified patients over the age of 20 years who had undergone either THA or short-stem THA between January 2012 and December 2014. BMI was classified into four groups (< 30 kg/m², 30 to 34.9 kg/m², 35 to 39.9 kg/m², > 40 kg/m²). In all patients, the 90-day complication, mortality and revision rates were calculated. Furthermore, all complications and revisions were determined at a latest follow-up of 1 year. We used multivariable logistic regression to model the odds of complications as a function of BMI groups. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were calculated.

A total of 131,576 total hip arthroplasties in 124,368 patients were included for final analysis. BMI had a significant effect on risk adjusted 1-year overall complications, 1-year revision surgery and 90-day surgical complications. The adjusted odd ratios increased significantly with BMI category. Especially morbidly obese patients with a BMI >40 kg/m² had a threefold higher risk for deep infection and a two-fold higher risk for the overall complication and revision rates as compared to patients with a BMI <30 kg/m².

Obesity plays an important role in patients undergoing primary THA, especially patients with a BMI beyond 40 kg/m² have a markedly higher risk for revision surgery and overall complication rates. This study aims to increase awareness among physicians in order to improve risk stratifications and to better educate patients with regard to obesity and postoperative expectations prior to undergoing elective total hip arthroplasty.

Aim

Alpha-defensin was recently introduced as a new biomarker having a very high accuracy to rule out periprosthetic joint infection (PJI). A new rapid lateral flow version of the Alpha-defensin test was developed and introduced to detect high levels of Alpha-defensin in synovial fluid quickly and with ease. We conducted a single-centre prospective clinical study to compare the results of the Alpha-defensin rapid test* against the conventional diagnostics according to MSIS criteria.

The treatment of extensive bone loss and massive acetabular defects is a challenging procedure, especially the concomitant pelvic discontinuity (PD) can be compounded by several challenges and pitfalls. The appropriate treatment strategy is to restore a stable continuity between the ischium and the ilium and to reconstruct the anatomical hip center. Antiprotrusio cages, metal augments, reconstruction cages with screw fixation, structural allograft with plating, jumbo cups, oblong cups and custom-made triflange acetabular components have been reported as possible treatment options. Nevertheless, the survivorship following acetabular revision with extensive bone loss is still unsatisfactory. The innovation of three-dimensional printing (3DP) has become already revolutionary in engineering and product design. Nowadays, the technology is becoming part of surgical practice and suitable for the production of precise and bespoke implants. The technique of a 3D-printed custom acetabular component in the management of extensive acetabular defect is presented.

Revision total hip arthroplasty (THA) is a challenging procedure, especially in cases with well-fixed implants. In such cases, several removal techniques have been presented in the current literature, while the most commonly used techniques are the transfemoral osteotomy or the extended trochanteric osteotomy (ETO). Those techniques allow the surgeon to have a better intra-operative exposure of the fixation surfaces of the solid femoral stems. However, the complication rates such as non-union are not unremarkable. Therefore, it is always a good decision to avoid an ETO if alternative techniques exist. The endofemoral surgical technique is an alternative method for the removal of well-fixed cemented and uncemented femoral stems.

Despite the prophylactic use of antibiotics and hygienic strategies, surgical site infection following total joint arthroplasty (TJA) is still a severe and unsolved complication. Since antibiotic-loaded bone cement (ALBC) was introduced by Buchholz in the 1970s, the use of ALBC has been increasingly used for the prevention and treatment of periprosthetic infection (PPI). However, the routine use of ALBC during primary TJA remains controversial. Recent clinical studies have found that ALBC is effective in reducing the risk of PJI following primary TJA. Although ALBC having the advantage of reducing the risk of PJI, the main disadvantages are the possible development of toxicity, antibiotic resistance, allergic reaction, and possible reduction of the mechanical properties of bone cement. Nevertheless, a recent published article demonstrated, that the use of high dose dual-antibiotic impregnated cement reduce significantly the rate of surgical site infections compared to standard low dose single ALBC in the setting of a hip fracture treating with hemiarthroplasty. Furthermore, Sanz-Ruiz et al. presented that the use of ALBC in TJA has favorable cost-efficiency profile. In this context, reasons why surgeons should use antibiotic-loaded bone cement during primary TJA are demonstrated.

The method of choice in the management of chronic infections is the exchange arthroplasty. The exchange arthroplasty can be performed either in a one- or in a two-stage setting, whereas the two-stage exchange arthroplasty is still considered the “gold standard” worldwide. The current literature and guidelines for PJI treatment deliver no clear evidence that a two-stage exchange procedure has a clearly higher success rate than the one-stage procedure. Since the first implantation of mixing antibiotics into bone cement in 1970s, the ENDO-Klinik followed until today in over 85% of all infected cases the one-stage exchange arthroplasty for the management of PJI. The main requirement is the known germ with known susceptibility based on microbiological diagnostics. Proper bone stock for cemented, in some cases, uncemented reconstruction, and the possibility of primary wound closure are also clear assumptions. The one-stage exchange arthroplasty delivers diverse advantages. For instance, the need for only one operation, shorter hospitalization, reduced systemic antibiotics and lower overall cost. A well-defined pre-operative planning regime is absolutely mandatory.

Objectives

Mechanical wear and corrosion at the head-stem junction of total hip arthroplasties (THAs) (trunnionosis) have been implicated in their early revision, most commonly in metal-on-metal (MOM) hips. We can isolate the role of the head-stem junction as the predominant source of metal release by investigating non-MOM hips; this can help to identify clinically significant volumes of material loss and corrosion from these surfaces.

Femoral revision in cemented THA might include some technical difficulties, based on loss of bone stock and cement removal, which might lead to further loss of bone stock, inadequate fixation, cortical perforation or consequent fractures. Femoral impaction grafting, in combination with a primary cemented stem, allows for femoral bone restoration due to incorporation and remodeling of the allograft bone by the host skeleton. Historically, it has been first performed and described in Exeter in 1987, utilizing a cemented tapered polished stem in combination with morselised fresh frozen bone grafts. The technique was refined by the development of designated instruments, which have been implemented by the Nijmegen group from Holland.

Indications might include all femoral revisions with bone stock loss, while the ENDO-Klinik experience is mainly based on revision of cemented stems. Cavitary bone defects affecting meta- and diaphysis leading to a wide or so called “drain pipe” femora, are optimal indications for this technique, especially in young patients. Contraindications are mainly: septical revisions, extensive circumferential cortical bone loss and noncompliance of the patient.

Generally the technique creates a new endosteal surface to host the cemented stem by reconstruction of the cavitary defects with impacted morselised bone graft. This achieves primary stability and restoration of the bone stock. It has been shown, that fresh frozen allograft shows superior mechanical stability than freeze-dried allografts. Incorporation of these grafts has been described in 89%.

Technical steps include: removal of failed stem and all cement, reconstruction of segmental bone defects with metal mesh (if necessary), preparation of fresh frozen femoral head allografts with bone mill, optimal bone chip diameter 2 – 5 mm, larger chips for the calcar area (6 – 8 mm), insertion of an intramedullary plug including central wire, 2 cm distal to the stem tip, introduction of bone chips from proximal to distal, impaction started by distal impactors over central wire, then progressively larger impactors proximal, insertion of a stem “dummy” as proximal impactor and space filler, removal of central wire, retrograde insertion of low viscosity cement (0.5 Gentamycin) with small nozzle syringe, including pressurization, insertion of standard cemented stem. The cement mantle is of importance, as it acts as the distributor of force between the stem and bone graft and seals the stem. A cement mantle of at least 2 mm has shown favorable results. Originally the technique is described with a polished stem. We use standard brushed stems with comparable results. Postoperative care includes usually touch down weight bearing for 6–8 weeks, followed by 4–6 weeks of gradually increased weightbearing with a total of 12 weeks on crutches.

Survivorship with a defined endpoint as any femoral revision after 10 year follow up has been reported by the Exeter group being over 90%. While survivorship for revision related to aseptic loosening being above 98%. Within the last years various other authors and institutions reported similar excellent survivorships, above 90%. In addition a long term follow up by the Swedish arthroplasty registry in more than 1180 patients reported a cumulative survival rate of 94% after 15 years.

Impaction grafting might technically be more challenging and more time consuming than cement free distal fixation techniques. It, however, enables a reliable restoration of bone stock which might become important in further revision scenarios in younger patients.

Periprosthetic fractures involving the femoral meta/diaphysis can be treated in various fashions. The overall incidence of those fractures after primary total knee arthroplasties (TKA) ranges from 0.3 to 2.5%, however, can increase above 30% in revision TKA, especially in older patients with poorer bone quality. Various classifications suggest treatment algorithms. However, they are not followed consequently. Revision arthroplasty becomes always necessary if the implant becomes loose. Next, it should be considered in case of an unhappy TKA prior to the fracture rather than going for an osteosynthesis. Coverage of the associated segmental bone loss in combination with proximal fixation, can be achieved in either cemented or non-cemented techniques, with or without the combination of osteosynthetic fracture stabilization. Severe destruction of the metaphyseal bone, often does not allow adequate implant fixation for the revision implant and often does not allow proper anatomic alignment. In addition the destruction might include loss of integrity of the collaterals. Consequently standard or even revision implants might not be appropriate. Although first reports about partial distal femoral replacement are available since the 1960´s, larger case series or technical reports are rare within the literature and limited to some specialised centers. Most series are reported by oncologic centers, with necessary larger osseous resections of the distal femur.

The implantation of any mega prosthesis system requires meticulous planning, especially to calculate the appropriate leg length of the implant and resulting leg length. After implant and maybe cement removal, non-structural bone might be resected. Trial insertion is important due to the variation of overall muscle tension and recreation of the former joint line. So far very few companies offer yet such a complete, modular system which might also be expanded to a total femur solution. Furthermore it should allow the implantation of either a cemented or uncemented diaphyseal fixation. In general, the fracture should be well bridged with a longer stem in place. At least 3 cm to 5 cm of intact diaphysis away to the fracture site is required for stable fixation for both cemented and cementless stems. Application of allograft struts and cables maximises the biomechanical integrity of the fracture zone to promote fracture repair and implant fixation. Modular bridging systems do allow centimeter wise adaption distally, to the knee joint. Consequently in modern systems fully hinged or rotational hinge knee systems can be coupled, and adjusted accordingly to the patellar tracking and joint line. Fixation of the tibial component can be achieved in uncemented and cemented techniques. We still prefer the latter.

Although a reliable and relatively quick technique, frequent complications for all mega systems have been described. These usually include infections, rotational alignment and loosening of the femoral fixation or subsequent proximal femoral fractures. Infections usually can be related to large soft tissue compromise or extensive exposure or longer procedure times. Thus implantation of such reconstruction systems should be reserved to specialised centers, with adequate facilities experience, in order to minimise complications rates and optimise patients function postoperative.