Cement spacer loaded with antibiotics for infected implants of the hip joint

Quasi-static analysis of hip cement spacers

The use of temporary hip prosthesis made of orthopedic cement (spacer) in conjunction with antibiotics became a widespread method used for treating prosthetic infections despite the fact that this method makes bone cement (PMMA) more fragile. The necessity to incorporate reinforcement is therefore crucial to strengthen the bone cement. In this study, a validated Finite Element Modelling (FEM) was used to analyze the behavior of spacers. This FEM model uses a non-linear dynamic explicit integration to simulate the mechanical behavior of the spacer under quasi-static loading. In addition to this FEM, Extended Finite Element Method (XFEM) was also used to investigate the fracture behavior of the spacers reinforced with titanium, ceramic and stainless-steel spacer stems. The effect of the material on the performance of the reinforced spacers was also analyzed. The results showed that numerical modelling based on explicit finite element using ABAQUS/Explicit is an effective method to predict the different spacers' mechanical behavior. The simulated crack initiation and propagation were in a good agreement with experimental observations. The FEM models developed in this study can help mechanical designers and engineers to improve the prostheses' quality and durability.

Custom-made, antibiotic-loaded, acrylic cement spacers using a dental silicone template for treatment of infected hip prostheses

PURPOSE

Antibiotic-loaded acrylic cement (ALAC) spacers are useful for treatment of infected prostheses in the course of a two-stage revision. Spacers are handmade or are made using a commercial template, with reportedly good treatment outcomes. This study aimed to confirm the usefulness of custom-made ALAC spacers shaped like bipolar hip prostheses using a dental silicone template for treatment of infected hip prostheses, and described their manufacture.

METHODS

This study evaluated 10 patients who underwent two-stage revision for treatment of infected hip prostheses. Custom-made ALAC spacers were used in all patients. Templates were made with dental silicone. We investigated the following in treatment of the infected hip prostheses: bacterial pathogens; antibiotic-cement mixtures; waiting time to revision; dislocation, breakage, and migration of custom-made ALAC spacers; current hip status; progress during follow-up; presence or absence of recurrence; and walking ability.

RESULTS

Dislocation, breakage, and migration were not observed in custom-made ALAC spacers. All patients recovered after two-stage revision without additional surgery and showed no recurrence during the follow-up period.

CONCLUSION

Custom-made ALAC spacers shaped like bipolar hip prostheses using a template made of dental silicone may be useful for treatment of infected hip prostheses.

Update on new medicinal applications of gentamicin: evidence-based review

Gentamicin (GM) was discovered in 1963 and was introduced into parenteral usage in 1971. Since then, GM has been widely used in medicinal applications. The Food and Drug Administration of the United States approved the routine prescription of GM to treat the following infectious disorders: infection due to Klebsiella pneumoniae, Escherichia coli, Serratia marcescens, Citrobacter spp., Enterobacteriaceae spp., Pseudomonas spp.; Staphylococcus infectious disease; bacterial meningitis; bacterial sepsis of newborns; bacterial septicemia; infection of the eye, bone, skin and/or subcutaneous tissue; infective endocarditis; peritoneal dialysis-associated peritonitis due to Pseudomonas and other gram-negative organisms; peritonitis due to gastrointestinal tract infections; respiratory tract infections; and urinary tract infectious disease. GM is an old antibiotic and is used widely beyond its FDA-labeled indications as follows: actinomycotic infection; Staphylococcus saprophyticus bacteremia with pyelonephritis; appendicitis; cystic fibrosis; diverticulitis; adjunct regimen for febrile neutropenia; female genital infection; uterine infection; postnatal infection; necrotizing enterocolitis in fetus or newborn; osteomyelitis; pelvic inflammatory disease; plague; gonorrhea; tularemia; prophylaxis of post-cholecystectomy infection, transrectal prostate biopsy, and post-tympanostomy-related infection; malignant otitis externa; and intratympanically or transtympanically for Ménière's disease. GM is also used in combination regimens, such as with beta-lactam antibiotics to treat mixed infection and with bacteriophage to treat Staphylococcus aureus infections. It is also added to medical materials, such as GM-loaded cement spacers for osteomyelitis and prosthetic joint-associated infections. Overall, there are many medicinal applications for GM. To reduce the development of GM-resistant bacteria and to maintain its effectiveness, GM should be used only to treat or prevent infections that are proven or strongly suspected as being caused by susceptible bacteria. In the future, we believe that GM will be used more widely in combination therapy and applied to medical materials for clinical applications. A definitive, appropriately powered study of this antibiotic and its clinical applications is now required, especially in terms of its effectiveness, safety, and cost.

Do dynamic cement-on-cement knee spacers provide better function and activity during two-stage exchange?

BACKGROUND

Implantation of an antibiotic bone cement spacer is used to treat infection of a TKA. Dynamic spacers fashioned with cement-on-cement articulating surfaces potentially facilitate patient mobility and reduce bone loss as compared with their static counterparts, while consisting of a biomaterial not traditionally used for load-bearing articulations. However, their direct impact on patient mobility and wear damage while implanted remains poorly understood.

QUESTIONS/PURPOSES

We characterized patient activity, surface damage, and porous structure of dynamic cement-on-cement spacers.

METHODS

We collected 22 dynamic and 14 static knee antibiotic cement spacers at revision surgeries at times ranging from 0.5 to 13 months from implantation. For these patients, we obtained demographic data and UCLA activity levels. We characterized surface damage using the Hood damage scoring method and used micro-CT analysis to observe the internal structure, cracking, and porosity of the cement.

RESULTS

The average UCLA score was higher for patients with dynamic spacers than for patients with static spacers, with no differences in BMI or age. Burnishing was the only prevalent damage mode on all the bearing surfaces. Micro-CT analysis revealed the internal structure of the spacers was porous and highly inhomogeneous, including heterogeneous dispersion of radiopaque material and cavity defects. The average porosity was 8% (range, 1%-29%) and more than ½ of the spacers had pores greater than 1 mm in diameter.

CONCLUSIONS

Our observations suggest dynamic, cement-on-cement spacers allow for increased patient activity without catastrophic failure. Despite the antibiotic loading and internal structural inhomogeneity, burnishing was the only prevalent damage mode that could be consistently classified with no evidence of fracture or delamination. The porous structure of the spacers varied highly across the surfaces without influencing the material failure.

Mating of a PROSTALAC spacer with an intramedullary nail for reconstruction of an infected interprosthetic femoral shaft fracture: a case report

Reconstruction for concurrent infection of an ipsilateral total hip arthroplasty (THA) and total knee arthroplasty (TKA) is a challenge. We report a 2-stage reconstruction of a THA for chronic infection of both the THA and TKA with severe femoral bone loss secondary to interprosthetic fractures. The reconstruction involved using a custom-made, temporary, antibiotic-impregnated PROSTALAC spacer mated with an intramedullary nail. The acetabulum was then exposed and the necrotic cartilage was removed and curetted. The acetabulum was reamed to accept a PROSTALAC acetabular shell. The shell was cemented into the acetabulum with antibiotic cement. The custom-made spacer was then inserted distally first into the tibia. The distal end of the intramedullary nail was interlocked with a bicortical bolt to minimise nail rotation. Antibiotic-impregnated cement was moulded around the nail and spacer. The proximal end of the spacer was then reduced into the acetabular socket, and the joint was irrigated and the wound closed. A customised abduction brace was fitted, and partial weight bearing was allowed. Sufficient leg length, soft-tissue tension, and range of hip motion were restored, and a total femur and constrained liner was re-implanted 4 months later. Mating of an intramedullary nail with a PROSTALAC spacer is a viable reconstructive option.

Is extended trochanteric osteotomy safe for use in 2-stage revision of periprosthetic hip infection?

To evaluate the safety of using extended trochanteric osteotomy (ETO) in a 2-stage revision of periprosthetic hip infection, we performed a retrospective review of 23 patients using ETO in the revision of infected hip arthroplasty and compared them to 46 patients using ETO in the revision of noninfected hip arthroplasty. Harris Hip Score improved from 36 points preoperatively to 82 points postoperatively. Infection was eradicated in 22 patients (96%). ETO healed in all at a mean of 10.6 weeks. No stem was revised for aseptic loosening. Complications included 2 periprosthetic fractures, 1 peroneal nerve palsy, and 1 dislocation. Postoperative Harris Hip Score, ETO union rate, time to healing of ETO, stem stability, and complication rate did not differ between the 2 groups. Our data suggest that ETO can be safely used in treating periprosthetic hip infection.

Two-stage exchange for infected resurfacing arthroplasty: use of a novel cement spacer technique

Infection after total hip arthroplasty is a devastating complication. A 2-stage reimplantation with antibiotic-impregnated interval spacer is typically recommended. We present a case of infected resurfacing hip arthroplasty treated with a novel cement spacer technique. The aim was to avoid the introduction of the infection into the femoral medullary canal with the use of a conventional stemmed antibiotic cement spacer. Reimplantation was accomplished routinely, and the patient remains infection-free at 9 months.

Staged custom, intramedullary antibiotic spacers for severe segmental bone loss in infected total hip arthroplasty

Introduction. Total hip arthroplasty (THA) infections with severe bone loss pose significant reconstructive challenges. We present our experience with two-stage hip reimplantation using an intramedullary, antibiotic-impregnated nail. Methods. Three patients with infected THA with severe proximal femoral bone loss (Mallory type IIIB or greater) were treated using a custom antibiotic spacer. Clinical outcomes and any complications were recorded. Average followup was 49 months from final reimplantation. Results. Mean age at spacer placement (stage 1) was 53 years. The mean Harris Hip Score at final followup was 80. Two patients had asymptomatic heterotopic ossification, and one patient had a 2 cm leg-length discrepancy. Conclusions. A custom intramedullary nail antibiotic spacer is a reliable option in the staged management of the infected THA with severe proximal femoral bone loss. Benefits of this technique include limb salvage with maintenance of leg length, soft tissue tension, and functional status.

Antibiotic-impregnated cement spacer versus antibiotic irrigating metal spacer for infection management after THA

We prospectively compared the effects of an antibiotic-impregnated cement spacer and an antibiotic irrigating metal spacer in the treatment of infections after total hip arthroplasty (THA) to determine a better method for 2-stage revision of infected THA. We used a uniform protocol of a 3-month spacer interval and specific local and systemic antibiotic therapies. The clinical outcome was determined by assessing operation time, blood loss during spacer implantation, hospital stay and time in bed, and joint function. The patients were followed for a mean 61.4 months (range, 24-94 months). Antibiotic-impregnated cement spacers had a higher rate of infection control than antibiotic irrigating metal spacers (96.2% vs 76%, respectively; P<.01), with no recurrence of infections or implant loosening. Patients receiving antibiotic-impregnated cement spacers had a shorter operation time (2.42±0.65 vs 3.34±0.36 hours metal spacers; P<.01), less blood loss (1085.48±279.49 vs 1964.78±469.23 mL metal spacers; P<.01), a shorter hospital stay (24.53±4.72 days vs 51.36±3.46 days metal spacers; P<.01), and better function before the second step of the 2-stage revision (Harris Hip Score, 88.16±6.94 vs 79.54±6.48 metal spacers; P<.05), and they were free from long-term irrigation. Compared with the antibiotic irrigating metal spacer, the antibiotic-impregnated cement spacer is characterized by higher infection control rate, better joint function recovery before the second operation, shorter operation time, and less blood loss, with no continuous irrigation required.

Preformed gentamicin spacers in two-stage revision hip arthroplasty: functional results and complications

Two-stage revisions with antibiotic-loaded spacers have gained popularity for treating infected hip-joint arthroplasties. The aim of this prospective study was to assess patient functionality between stages and treatment impact on duration of hospital stay and to describe related complications. Sixty-one consecutive patients with infected hip arthroplasties underwent two-stage revision with preformed spacer implantation. Mean Harris Hip and Merle d'Aubigné scores between the two stages were 39.9 and 7.6, respectively. Forty-six patients (75.4%) were able to leave hospital between stages. Spacer dislocation occurred in 16.4%. No cases of spacer breakage were noted. Preformed cement spacers provide acceptable functional outcome between revision hip arthroplasty stages and facilitate the surgical procedure without increasing mechanical complication rates.

Infection in total hip replacement: meta-analysis

While total hip arthroplasty has progressed to become one of the most successful surgical procedures ever developed, infection remains a serious complication. We have conducted a review of the literature pertaining to management of deep infection in total hip arthroplasty, specifically focusing on clinically relevant articles published in the last five years. A search was conducted using MEDLINE and PubMed, as well as a review of the Cochrane database, using the terms "total hip arthroplasty", "total hip replacement" and "infection". References for all selected articles were cross-checked. While the so-called two-stage revision is generally considered to be the gold standard for management, numerous studies now report outcomes for implant retention and reassessing one-stage revision strategies. There are encouraging reports for complex reconstruction options in patients with associated severe bone stock loss. The duration of antibiotic therapy remains controversial. There is concern about increasing bacterial resistance especially with the widespread use of vancomycin and ertapenem (carbapenem).

Treatment of periprosthetic hip infection caused by resistant microorganisms using 2-stage reimplantation protocol

To determine the effectiveness of staged reimplantation for the treatment of periprosthetic hip infection caused by resistant microorganisms, we performed a retrospective case-control study on 37 consecutive patients who had a culture-proven periprosthetic hip infection treated using a 2-stage reimplantation protocol. Twenty-four patients infected by resistant microorganisms were compared with 13 patients infected by nonresistant microorganisms. The second-stage reimplantation procedure was possible in 34 (92%) of the 37 patients, but the remaining 3 required permanent resection because of persistent infection. At a mean follow-up of 4.4 years, there were 4 recurrent infections and 1 aseptic cup loosening. Overall treatment failure rate was 22%. All failures occurred only in the resistant microorganism group and none in the nonresistant microorganism group (33% vs 0%; P = .032). Current 2-stage reimplantation protocol showed a high rate of treatment failure in our patients with a periprosthetic hip infection caused by resistant microorganisms.

Antibiotics-impregnated cement spacers in the first step of two-stage revision for infected totally replaced hip joints: report of ten trial cases

BACKGROUND

Periprosthetic infection is one of the serious complications after total hip arthroplasty (THA). This study analyzed the perioperative and postoperative status of patients who underwent antibiotics-impregnated cement spacer technique in the first step of the two-stage revision.

METHODS

Ten joints of the nine patients (mean age, 65 years; seven women, two men) received two-stage revision as a result of infection that appeared after primary THAs in seven joints, aseptic revision in one, and recurrent type in two. An antibiotics-impregnated cement spacer made by a mold system was applied in the femoral side of all joints. An acetabular spacer was made by hand using a cup gauge in eight joints with extensive tissue loss.

RESULTS

The change of leg length after the first stage was -2.2 mm, and range of hip flexion was 72 degrees on average, respectively. Patients could walk with crutches after the first stage, except one patient with simultaneous infections of both hips and one with fracture of the cement spacer. One fracture of femoral cement spacer, and one dislocation of femoral spacer accompanied by fracture of acetabular cement spacer and curable recurrent infection, were found. In all cases of the second-stage procedure, the acetabular side was reconstructed with allogeneic bone graft with cross plate and that of the femur was by impaction bone grafting method. In the latest follow-up, reconstructed implants were stable. Seven patients could walk without any supportive devices and two could walk with the support of a T-cane.

CONCLUSIONS

An antibiotics-impregnated cement spacer in the first step of the two-stage revision was effective not only to compensate tissue loss after removal of the implants and to minimize discrepancy of leg length, but also to contribute to improvement of perioperative and postoperative daily activities of the patient's life as well as treatment of the infection.

Revision of late periprosthetic infections of total hip endoprostheses: pros and cons of different concepts

Many concepts have been devised for the treatment of late periprosthetic infections of total hip prostheses. A two-stage revision with a temporary antibiotic-impregnated cement spacer and a cemented prosthesis appears to be the most preferred procedure although, in recent times, there seems to be a trend towards cementless implants and a shorter period of antibiotic treatment. Because of the differences in procedure, not only between studies but also within studies, it cannot be decided which period of parenteral antibiotic treatment and which spacer period is the most suitable. The fact that comparable rates of success can be achieved with different treatment regimens emphasises the importance of surgical removal of all foreign materials and the radical debridement of all infected and ischaemic tissues and the contribution of these crucial procedures to the successful treatment of late periprosthetic infections.

Mechanical behaviour of standardized, endoskeleton-including hip spacers implanted into composite femurs

Two-stage reconstruction using an antibiotic loaded cement spacer is the preferred treatment method of late hip joint infections. Hip spacers maintain stability of the joint and length of the limb during treatment period. However, as the material strength of bone cement (PMMA) is limited, spacer fractures led to serious complications in the past. This study investigated the load capacity of custom made hip spacers, developed at the 'Klinik für Orthopädie und Orthopädische Chirurgie' (Universitätsklinikum des Saarlandes, Homburg/Saar, Germany), and implanted into composite femurs. In a quasi-static test, non-reinforced spacers tolerated hip joint loads of about 3000 N, whereas reinforced spacers with titanium-grade-two endoskeletons doubled this load up to 6000 N. Even for cyclic loading, endoskeleton-including hip spacers tolerated loads of >4500 N with 500,000 load cycles. Thus, an endoskeleton-including spacer should provide a mobile and functional joint through the treatment course. A generated FE-model was used to determine the fracture stresses and allows for further sensitivity analysis.