Use of Tantalum Trabecular Metal Cones for Management of Nonunion of the Distal Femur with Segmental Bone Defects: Technique and Case Series.

INTRODUCTION: Segmental bone loss in the distal femur presents a challenge for reconstruction regardless of etiology. Use of tantalum trabecular metal cones with intramedullary fixation and autologous bone graft may be used as a salvage technique in difficult situations where other options have either been exhausted or are unavailable. CASE REPORT: Surgical planning and technique for this approach to reconstruction are described. A retrospective review of five cases with >1 year of follow-up was performed to provide radiographic and clinical outcomes. All five patients had satisfactory outcomes with clinical union and retention of implants at final follow-up (average >4 years). CONCLUSIONS: Use of tantalum metal cones for reconstruction of distal femur nonunion with segmental bone defects can be a successful technique in a complex group of patients.

Patient Characteristics and Surgical Start Time Affect Length of Stay Following Anterior Total Hip Arthroplasty.

BACKGROUND: Currently, no consensus exists for selection criteria of appropriate candidates for outpatient total hip arthroplasty (THA). This study evaluates patient characteristics associated with same-day discharge, examined surgical start time's effect on rates of same-day discharge, and compares readmission and reoperation rates between groups. METHODS: All patients who underwent a THA by one surgeon at a single quaternary care hospital between February 2016 and May 2018 were captured. All patients were given the option for same-day discharge. Patient characteristics and perioperative variables were analyzed. RESULTS: A total of 429 patients met inclusion criteria, 153 (36%) were discharged on the day of surgery. In a multivariate analysis, age (P = .000), multiple comorbidities (P = .004), and start time remained statistically significant (P = .000). Patients with start times prior to 9 AM had odds ratio of 11.56 of being discharged same day when compared to those with start times after 12 PM. Patients discharged the day of surgery were less likely to have a 90-day emergency room visit (P = .010), a readmission within 30 days (P = .001) or 90 days (P = .000), or a reoperation (0 vs 14, P = .003). CONCLUSION: Same-day discharge following THA is safe and feasible. Patient's age and number of comorbidities should be considered when developing selection criteria for same-day discharge programs. Patients selected for same-day discharge should receive earlier operating room start times.

Using Double-Contrast CT Arthrography to Confirm Suspected Dissociation of a Cemented Polyethylene Liner in the Setting of Revision Total Hip Arthroplasty: A Case Report.

CASE: A 67-year-old woman who underwent a re-revision of a total hip arthroplasty with a cemented polyethylene liner fell 14 months after surgery. The patient had symptoms of pain and weakness; however, clinical, laboratory, and radiographic evaluation did not disclose fracture, infection, osteolysis, or component migration. Liner dissociation was suspected, and a double-contrast computed tomography (CT) arthrogram confirmed failure at the cement-liner interface. She underwent additional revision surgery and was doing well at the 3-year follow-up. CONCLUSION: Double-contrast CT arthrography confirmed failure at the cement-liner interface and is an effective diagnostic tool in identifying suspected dissociations of cemented polyethylene liners.

Polymerase Chain Reaction-Electrospray-Time-of-Flight Mass Spectrometry Versus Culture for Bacterial Detection in Septic Arthritis and Osteoarthritis.

BACKGROUND: Preliminary studies have identified known bacterial pathogens in the knees of patients with osteoarthritis (OA) before arthroplasty. AIMS: The current study was designed to determine the incidence and types of bacteria present in the synovial fluid of native knee joints from adult patients with diagnoses of septic arthritis and OA. PATIENTS AND METHODS: Patients were enrolled between October 2010 and January 2013. Synovial fluid samples from the affected knee were collected and evaluated with both traditional microbial culture and polymerase chain reaction-electrospray ionization-time-of-flight mass spectrometry (molecular diagnostics [MDx]) to prospectively characterize the microbial content. Patients were grouped by diagnosis into one of two cohorts, those with clinical suspicion of septic arthritis (n = 44) and those undergoing primary arthroplasty of the knee for OA (n = 21). In all cases where discrepant culture and MDx results were obtained, we performed species-specific 16S rRNA fluorescence in situ hybridization (FISH) as a confirmatory test. RESULTS: MDx testing identified bacteria in 50% of the suspected septic arthritis cases and 29% of the arthroplasty cases, whereas culture detected bacteria in only 16% of the former and 0% of the latter group. The overall difference in detection rates for culture and MDx was very highly significant, p-value = 2.384 × 10-7. All of the culture-positive cases were typed as Staphylococcus aureus. Two of the septic arthritis cases were polymicrobial as was one of the OA cases by MDx. FISH testing of the specimens with discordant results supported the MDx findings in 91% (19/21) of the cases, including one case where culture detected S. aureus and MDx detected Streptococcus agalactiae. CONCLUSIONS: MDx were more sensitive than culture, as confirmed by FISH. FISH only identifies bacteria that are embedded or infiltrated within the tissue and is thus not susceptible to contamination. Not all suspected cases of septic arthritis contain bacteria, but a significant percent of patients with OA, and no signs of infection, have FISH-confirmed bacterial biofilms present in the knee.

Progressive Cardiomyopathy in a Patient With Elevated Cobalt Ion Levels and Bilateral Metal-on-Metal Hip Arthroplasties.

Systemic cobalt toxicity is a rare complication after metal-on-metal (MOM) total hip arthroplasty. Here we present a case of progressive cardiomyopathy, as evidenced by biopsy and cardiac magnetic resonance imaging (MRI), in a patient with bilateral MOM total hip arthroplasties. To our knowledge, it is one of the first cases in which cardiomyopathy resulting from systemic cobalt disease has been shown on MRI. While there is no guideline to unequivocally diagnose cobalt cardiomyopathy, the constellation of findings, including pathologic, biologic, blood levels, imaging, and surgical, all uniformly indicate a unifying diagnosis. The lack of improvement after removal of the prosthetic device supports a diagnosis of permanent myocardial damage, which is consistent with cardiomyopathy of advanced toxic etiology.

Presence of bacteria in failed anterior cruciate ligament reconstructions.

BACKGROUND: Novel microbial detection technologies have revealed that chronic bacterial biofilms, which are recalcitrant to antibiotic treatment, are common in failed orthopedic procedures. QUESTIONS: Are bacteria present on failed anterior cruciate ligament (ACL) reconstructions? Is there a difference in the presence or nature of bacteria in failed ACL reconstructions relative to a control set of healthy ACL's? METHODS: We used a case-control study design, where we analyzed the bacterial composition of 10 failed ACL reconstructions and compared it to 10 native ACL's harvested during total knee arthroplasty. The IBIS Universal Biosensor was used to determine the nature of bacteria on ACL specimens, and fluorescent in situ hybridization (FISH) was used to visualize bacteria in a subset of cases. RESULTS: Bacteria are present in failed ACL reconstructions. Bacteria are present in ACL's harvested during total knee arthroplasty, but the nature of the species differs significantly between experimental and control sets. Twelve genera were detected in the experimental set (in both allografts and autografts), and in four samples multiple species were detected. In contrast, the control group was characterized by presence of Propionibacterium acnes. CONCLUSIONS: We demonstrate the presence of bacteria on failed ACLs surgeries, and open the door to investigate whether and how bacteria and the associated immune responses could possibly contribute to graft failure. CLINICAL RELEVANCE: If microbial pathogens can be linked to failed grafts, it could provide: (1) markers for early diagnosis of abnormal healing in ACL surgeries, and (2) targets for early treatment to prevent additional reconstruction surgeries.

What role do periodontal pathogens play in osteoarthritis and periprosthetic joint infections of the knee?

Through the use of polymerase chain reaction (PCR)-electron spray ionization (ESI)-time of flight (TOF)-mass spectrometry (MS), we identified multiple periodontal pathogens within joint tissues of individuals undergoing replacement arthroplasties of the knee. The most prevalent of the periodontal pathogens were Treponema denticola and Enterococcus faecalis, the latter of which is commonly associated with apical periodontitis. These findings were unique to periprosthetic joint infections (PJI) of the knee and were never observed for PJIs of other lower extremity joints (hip and ankle) or upper extremity joints (shoulder and elbow). These data were confirmed by multiple independent methodologies including fluorescent in situ hybridization (FISH) which showed the bacteria deeply penetrated inside the diseased tissues, and 454-based deep 16S rDNA sequencing. The site-specificity, the tissue investment, and the identical findings by multiple nucleic-acid-based techniques strongly suggests the presence of infecting bacteria within these diseased anatomic sites. Subsequently, as part of a control program using PCR-ESI-TOF-MS, we again detected these same periodontal pathogens in aspirates from patients with osteoarthritis who were undergoing primary arthroplasty of the knee and thus who had no history of orthopedic implants. This latter finding raises the question of whether hematogenic spread of periodontal pathogens to the knee play a primary or secondary-exacerbatory role in osteoarthritis.

Survival of primary condylar-constrained total knee arthroplasty at a minimum of 7 years.

The purpose of the present study is to retrospectively analyze clinical and radiographic outcomes in primary constrained condylar knee arthroplasty at a minimum follow-up of 7 years. Given the concern for early aseptic loosening in constrained implants, we focused on this outcome. Our cohort consists of 127 constrained condylar knees. The mean age of patients in the study was 68.3 years, with a mean follow-up of 110.7 months. The diagnosis was primary osteoarthritis in 92%. There were four periprosthetic distal femur fractures, with a rate of revision of 0.8%. No implants were revised for aseptic loosening. Kaplan-Meier survivorship analysis with removal of any component as the end point revealed that the 10-year rate of survival of the primary CCK was 97.6% (95% CI, 94%-100%).

Subsidence in two uncemented femoral stems: an in vitro study.

Many aspects of the performance of different implant designs remain as open questions in total hip arthroplasty. Despite the increased survivorship of each hip replacement, the amount of bone removed during surgery remains an important factor because of the potential need for revision surgery. Given that a smaller implant will have less surface area over which to transfer load, constructs that preserve more bone stock may be susceptible to mechanical complications related to the fixation of the implant in the femur. To assess mechanical fixation, this study compared the fiber metal taper and Mayo conservative hip stems in subsidence, frontal plane rotation and failure load. After dual-energy x-ray absorptiometry scans, pairs of cadaveric femurs received implants of each type and were loaded for 10,000 cycles. The subsidence and rotation were measured. Finally, specimens were loaded to failure. The subsidence and rotation after cyclic loading were -0.73 mm and 0.1°, respectively, for the Mayo implants and -0.87 and 0.52°, respectively, for the fiber metal taper implants, but no significant differences between implant types were found. There was also no significant relationship to bone mineral density. A power analysis revealed that 914 specimens would have been required to achieve a power of 0.8.

Modular femoral neck fracture after primary total hip arthroplasty.

The use of modular femoral stems in primary total hip arthroplasty has increased considerably in recent years. These modular components offer the surgeon the ability to independently alter version, offset, and length of the femoral component of a hip arthroplasty. This increases the surgeon's ability to accurately recreate the relevant anatomy but increases the possibilities of corrosion and fracture. Multiple case reports have highlighted fractures of these modular components. We present a case of a fracture of a modular design that has had no previously reported modular neck fractures. The patient was informed that data concerning the case would be submitted, and he consented.

Mechanical effects, antimicrobial efficacy and cytotoxicity of usnic acid as a biofilm prophylaxis in PMMA.

Experiments were performed to test the null hypothesis that the addition of a natural occurring antibiotic would not alter mechanical properties of polymethylmethacrylate (PMMA). Compression and four-point bending tests were used to assess mechanical properties of zirconium dioxide bearing bone cement (Type Zr) and barium sulfate bearing bone cement (Type Ba), mixed with the antibiotic usnic acid ("usnic"), used to create a surface resistant to biofilm formation. Addition of usnic had a statistically significant effect on the material properties. Compressive and bending strengths decreased as usnic was added and Type Zr was stronger than Type Ba although material properties remained above recommended minima. With implications of liver toxicity with large doses of usnic taken as a dietary supplement, cytotoxicity tests using bone cement coupons were performed and showed very little or no toxicity in primary cultures of rabbit skin derived fibroblasts. A simple test of usnic's efficacy as a biofilm prophylaxis in PMMA was also conducted. Bone cement coupons with usnic were tested for their effectiveness against methicillin resistant Staphylococcus aureus. Diminished biofilm formation on usnic-containing coupons indicated that usnic can be an effective anti-microbial agent.

Orthopaedic biofilm infections.

A recent paradigm shift in microbiology affects orthopaedic surgery and most other medical and dental disciplines because more than 65% of bacterial infections treated by clinicians in the developed world are now known to be caused by organisms growing in biofilms. These slime-enclosed communities of bacteria are inherently resistant to host defenses and to conventional antibacterial therapy, and these device-related and other chronic bacterial infections are unaffected by the vaccines and antibiotics that have virtually eliminated acute infections caused by planktonic (floating) bacteria. We examine the lessons that can be learned, within this biofilm paradigm, by the study of problems (e.g. non-culturability) shared by all biofilm infections and by the study of new therapeutic options aimed specifically at sessile bacteria in biofilms. Orthopaedic surgery has deduced some of the therapeutic strategies based on assiduous attention to patient outcomes, but much can still be learned by attention to modern research in related disciplines in medicine and dentistry. These perceptions will lead to practical improvements in the detection, management, and treatment of infections in orthopaedic surgery.

Autogenous osteochondral transfer in the femoral head after osteonecrosis.

Osteonecrosis of the femoral head is a major problem, especially in younger patients. Most of them need a total hip replacement. This article presents a case of a successful autologous osteochondral transfer.

Arthrodesis of the knee with a long intramedullary nail following the failure of a total knee arthroplasty as the result of infection. Surgical technique.

BACKGROUND: Knee arthrodesis can be an effective treatment option for relieving pain and restoring some function after the failure of a total knee arthroplasty as the result of infection. The purpose of the present study was to review the outcome of a staged approach for arthrodesis of the knee with a long intramedullary nail after the failure of a total knee arthroplasty as the result of infection. METHODS: We reviewed the results for twelve patients who underwent knee arthrodesis after the removal of a prosthesis because of infection. The study group included seven women and five men who had an average age of sixty-eight years at the time of the arthrodesis. All patients were managed with a staged protocol. Implant removal, débridement, and insertion of antibiotic cement spacers was followed by the administration of systemic antibiotics. Provided that clinical and laboratory data suggested eradication of the infection, arthrodesis of the affected knee with use of a long intramedullary nail was carried out. Clinical and laboratory evaluation and radiographic analysis were performed after an average duration of follow-up of 4.1 years. RESULTS: Solid union was achieved in ten of the twelve knees. The average time to union was 5.5 months. One patient had an above-the-knee amputation because of recurrence of infection. In another patient, nail breakage occurred three years following implantation. The average limb-length discrepancy was 5.5 cm. The mean Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score improved from 41 to 64 points. None of the seven patients who underwent arthrodesis with a technique involving convex-to-concave reamers had a complication, and the average time to union for these seven patients was shorter than that for the remaining five patients (4.3 compared with 7.4 months). CONCLUSIONS: We believe that obtaining large surfaces of bleeding contact bone during arthrodesis following staged treatment of an infection at the site of a failed total knee arthroplasty contributes to stability and enhances bone-healing. Staged arthrodesis with use of a long intramedullary nail and convex-to-concave preparation of bone ends provided a painless functional gait with low complication and reoperation rates in this challenging group of patients.

Using intraoperative pelvic landmarks for acetabular component placement in total hip arthroplasty.

Dislocation after total hip arthroplasty is frequently due to acetabular malpositioning. Positioning of the acetabular component using anatomical landmarks may reduce the incidence of dislocation from improper acetabular orientation. The pelvis provides 3 bony landmarks (ilium, superior pubic ramus, and superior acetabulum), which, when used to define a plane, allows cup orientation in abduction and version. Landmarks evaluated in 24 cadaveric acetabuli allowed slightly increased abduction and anteversion of the cup, compared with native acetabuli. Six hundred seventeen primary total hip arthroplasties were performed between 1996 and 2003 using this technique. Mean cup abduction was 44.4 degrees with 13.2 degrees of anteversion. This technique allows satisfactory reproducible cup orientation based on individual pelvic morphology. Review of patient outcome data suggest high patient satisfaction and lower dislocation rate without additional equipment, time, or cost.

Revision total hip arthroplasty with a custom cementless stem with distal cross-locking screws. Early results in femora with large proximal segmental deficiencies.

BACKGROUND: Revision total hip arthroplasty in the setting of a large proximal segmental femoral deficiency and/or discontinuity between the proximal and distal parts of the femur remains a challenging problem. We describe the use of a cementless stem with distal cross-locking screws to provide stability of the femoral implant in this situation. METHODS: Seventeen custom fully porous and hydroxyapatite-coated titanium femoral stems with distal cross-locking titanium screws were implanted in sixteen patients during revision total hip arthroplasty. Preoperatively, all of the patients had Paprosky grade-IIIB or IV femoral deficiencies. At the time of follow-up, the Harris hip scores were calculated and radiographs were made. A successful result was defined as a postoperative increase in the Harris hip score of >20 points, a radiographically stable implant, and no additional femoral reconstruction. RESULTS: At the time of final follow-up, at a mean of 5.3 years postoperatively, the result was successful in sixteen of the seventeen hips, the mean Harris hip score had improved from 35 to 76 points, and all implants were clinically and radiographically stable. There were no postoperative infections or hip dislocations. CONCLUSIONS: The use of a custom femoral stem with distal cross-locking screws can provide at least intermediate-term clinical and radiographic stability in patients with Paprosky grade-IIIB or IV femoral deficiencies. Longer follow-up will be required to determine the longevity of these implants.

Arthrodesis of the knee with a long intramedullary nail following the failure of a total knee arthroplasty as the result of infection.

BACKGROUND: Knee arthrodesis can be an effective treatment option for relieving pain and restoring some function after the failure of a total knee arthroplasty as the result of infection. The purpose of the present study was to review the outcome of a staged approach for arthrodesis of the knee with a long intramedullary nail after the failure of a total knee arthroplasty as the result of infection. METHODS: We reviewed the results for twelve patients who underwent knee arthrodesis after the removal of a prosthesis because of infection. The study group included seven women and five men who had an average age of sixty-eight years at the time of the arthrodesis. All patients were managed with a staged protocol. Implant removal, débridement, and insertion of antibiotic cement spacers was followed by the administration of systemic antibiotics. Provided that clinical and laboratory data suggested eradication of the infection, arthrodesis of the affected knee with use of a long intramedullary nail was carried out. Clinical and laboratory evaluation and radiographic analysis were performed after an average duration of follow-up of 4.1 years. RESULTS: Solid union was achieved in ten of the twelve knees. The average time to union was 5.5 months. One patient had an above-the-knee amputation because of recurrence of infection. In another patient, nail breakage occurred three years following implantation. The average limb-length discrepancy was 5.5 cm. The mean Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score improved from 41 to 64 points. None of the seven patients who underwent arthrodesis with a technique involving convex-to-concave reamers had a complication, and the average time to union for these seven patients was shorter than that for the remaining five patients (4.3 compared with 7.4 months). CONCLUSIONS: We believe that obtaining large surfaces of bleeding contact bone during arthrodesis following staged treatment of an infection at the site of a failed total knee arthroplasty contributes to stability and enhances bone-healing. Staged arthrodesis with use of a long intramedullary nail and convex-to-concave preparation of bone ends provided a painless functional gait with low complication and reoperation rates in this challenging group of patients.

Molecular and imaging techniques for bacterial biofilms in joint arthroplasty infections.

Biofilm formation on surfaces is an ancient and integral strategy for bacterial survival. Billions of years of adaptation provide microbes with the ability to colonize any surface, including those used in orthopaedic surgery. Although remarkable progress has been made in the treatment of orthopaedic diseases with implanted prostheses, infection rates remain between 1% and 2%, and are higher for revision surgeries. The chronic nature of implant infections, their nonresponsiveness to antibiotics, and their frequent culture negativity can be explained by the biofilm paradigm of infectious disease. However, the role of biofilms in orthopaedic implant infections and aseptic loosening is controversial. To address these issues, we developed molecular diagnostic and confocal imaging techniques to identify and characterize biofilms associated with infected implants. We designed PCR and reverse transcription (RT)-PCR-based assays that can be used to detect bacterial infections associated with culture-negative joint effusions that distinguish between physiologically active Staphylococcus aureus and Staphylococcus epidermidis. Using clinical isolates of Pseudomonas aeruginosa, we constructed a series of reporter strains expressing colored fluorescent proteins to observe biofilms growing on 316L stainless steel and titanium orthopaedic screws. Three-dimensional structures of Pseudomonas aeruginosa and staphylococci biofilms growing on the screws were documented using confocal microscopy. The application of these tools for clinical diagnosis and biofilm research in animal and in vitro models is discussed.