Hanssen, Arlen D.

Background: The use of a trabecular metal revision shell with metal augmentation to fill segmental or irregular defects during complex revision hip arthroplasty has been shown to provide good short-term results in prior published series. Longer-term results of the several cup-augment constructs used clinically are not known. The objective of this study was to report, with minimum 5-year radiographic and clinical follow-up, the outcome of these various constructs in revision total hip arthroplasty. Methods: Eighty-four patients (85 hips) underwent revision total hip arthroplasty with use of porous tantalum augments between 2000 and 2007 at a single institution and were retrospectively reviewed. Fifty-seven of the patients (58 hips) had clinical and radiographic follow-up at a minimum of 5 years. At the time of revision, the majority of the hips had acetabular defects classified as Paprosky Type 3A (28 of 58, 48%) or Type 3B (22 of 58, 38%). Eleven (19%) of the hips also had preoperative pelvic discontinuity. All hips were assessed clinically at a minimum of 5 years with use of the Mayo hip score. Postoperative radiographs were reviewed for implant stability, the presence and location of radiolucent lines and healing of the discontinuity if present. Results: In 2 (3%) of the 58 hips, the constructs failed because of aseptic loosening of the acetabular component and re-revision was indicated. Six (10%) of the 58 hips demonstrated a radiolucent line between the trabecular metal shell and bone in DeLee and Charnley zone 3. In 1 hip that underwent re-revision and in 5 of the 6 hips with a zone-3 radiolucency, a pelvic discontinuity was present at the time of the index revision. The mean preoperative Mayo hip score was 35.7, which improved to 61.9 at 3 months and was 61.7 at the minimum 5-year follow-up. Conclusions: With failure defined as aseptic loosening requiring repeat revision surgery, this cohort demonstrated 97% survivorship and maintained satisfactory hip function at the minimum 5 years after the index revision surgery. Six of the 11 hips with preoperative pelvic discontinuity either failed or developed a radiolucency in zone 3 and are considered at risk for future revision. Pelvic discontinuity should prompt consideration of the addition of adjunctive fixation or the use of alternative techniques. Level of Evidence: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Aims The number of revision total knee arthroplasties (TKA) that are performed is expected to increase. However, previous reports of the causes of failure after TKA are limited in that they report the causes at specific institutions, which are often dependent on referral patterns. Our aim was to report the most common indications for re-operations and revisions in a large series of posterior-stabilised TKAs undertaken at a single institution, excluding referrals from elsewhere, which may bias the causes of failure. Patients and Methods A total of 5098 TKAs which were undertaken between 2000 and 2012 were included in the study. Re-operations, revisions with modular component exchange, and revisions with non-modular component replacement or removal were identified from the medical records. The mean follow-up was five years (two to 12). Results The Kaplan-Meier ten-year survival without a re-operation, modular component revision and non-modular component revision was 95.7%, 99.3% and 95.3%, respectively. The most common indications for a re-operation were: post-operative stiffness (58%), delayed wound healing (21%), and patellar clunk (11%). The indications for isolated modular component revision were acute periprosthetic joint infection (PJI) (64%) and instability (36%). The most common indications for non-modular component revision were chronic PJI (52%), aseptic loosening (17%), periprosthetic fracture (10%), and instability (10%). Conclusion Post-operative stiffness remains the most common indication for re-operation after TKA. Infection is the most common indication for modular and non-modular component revision. Aseptic loosening was not an uncommon cause of failure, however, it was much less common than in national registry and non-registry data. Focusing on posterior-stabilised TKAs initially performed at our institution allowed for an accurate assessment of the causes of failure in a contemporary specialty practice. Cite this article: Bone Joint J 2017;99-B:647–52.

ABSTRACT Whole-genome amplification (WGA) is a useful tool for amplification of very small quantities of DNA for many uses, including metagenomic shotgun sequencing for infection diagnosis. Depending on the application, background DNA from WGA kits can be problematic. Three WGA kits were tested for their utility in a metagenomics approach to identify the pathogens in sonicate fluid comprised of biofilms and other materials dislodged from the surfaces of explanted prosthetic joints using sonication. The Illustra V2 Genomiphi, Illustra single cell Genomiphi, and Qiagen REPLI-g single cell kits were used to test identical sonicate fluid samples. Variations in the number of background reads, the genera identified in the background, and the number of reads from known pathogens known to be present in the samples were observed between kits. These results were then compared to those obtained with a library preparation without prior WGA using an NEBNext Ultra II paired-end kit, which requires a very small amount of input DNA. This approach also resulted in the presence of contaminant bacterial DNA and yielded fewer reads from the known pathogens. These findings highlight the impact that WGA kit selection can have on metagenomic analysis of low-biomass samples and the importance of the careful selection and consideration of the implications of using these tools.

Objectives Sustained intra-articular delivery of pharmacological agents is an attractive modality but requires use of a safe carrier that would not induce cartilage damage or fibrosis. Collagen scaffolds are widely available and could be used intra-articularly, but no investigation has looked at the safety of collagen scaffolds within synovial joints. The aim of this study was to determine the safety of collagen scaffold implantation in a validated in vivo animal model of knee arthrofibrosis. Materials and Methods A total of 96 rabbits were randomly and equally assigned to four different groups: arthrotomy alone; arthrotomy and collagen scaffold placement; contracture surgery; and contracture surgery and collagen scaffold placement. Animals were killed in equal numbers at 72 hours, two weeks, eight weeks, and 24 weeks. Joint contracture was measured, and cartilage and synovial samples underwent histological analysis. Results Animals that underwent arthrotomy had equivalent joint contractures regardless of scaffold implantation (-13.9° versus -10.9°, equivalence limit 15°). Animals that underwent surgery to induce contracture did not demonstrate equivalent joint contractures with (41.8°) or without (53.9°) collagen scaffold implantation. Chondral damage occurred in similar rates with (11 of 48) and without (nine of 48) scaffold implantation. No significant difference in synovitis was noted between groups. Absorption of the collagen scaffold occurred within eight weeks in all animals Conclusion Our data suggest that intra-articular implantation of a collagen sponge does not induce synovitis or cartilage damage. Implantation in a native joint does not seem to induce contracture. Implantation of the collagen sponge in a rabbit knee model of contracture may decrease the severity of the contracture. Cite this article: J. A. Walker, T. J. Ewald, E. Lewallen, A. Van Wijnen, A. D. Hanssen, B. F. Morrey, M. E. Morrey, M. P. Abdel, J. Sanchez-Sotelo. Intra-articular implantation of collagen scaffold carriers is safe in both native and arthrofibrotic rabbit knee joints. Bone Joint Res 2016;6:162–171. DOI: 10.1302/2046-3758.63.BJR-2016-0193.

AimsLoss or absence of proximal femoral bone in revision total hip arthroplasty (THA) remains a significant challenge. While the main indication for the use of proximal femoral replacements (PFRs) is in the treatment of malignant disease, they have a valuable role in revision THA for loosening, fracture and infection in patients with bone loss. Our aim was to determine the clinical outcomes, implant survivorship, and complications of PFRs used in revision THA for indications other than malignancy.Patients and MethodsA retrospective review of 44 patients who underwent revision THA using a PFR between 2000 and 2013 was undertaken. Their mean age was 79 years (53 to 97); 31 (70%) were women. The bone loss was classified as Paprosky IIIB or IV in all patients. The mean follow-up was six years (2 to 12), at which time 22 patients had died and five were lost to follow-up.ResultsThe mean Harris Hip Score improved from 42.8 (25.9 to 82.9) pre-operatively to 68.5 (21.0 to 87.7) post-operatively (p = 0.0009). A total of two PFRs had been revised, one for periprosthetic infection eight years post-operatively and one for aseptic loosening six years post-operatively. The Kaplan-Meier survivorship free of any revision or removal of an implant was 86% at five years and 66% years at ten years. A total of 12 patients (27%) had a complication including six with a dislocation.ConclusionPFRs provide a useful salvage option for patients, particularly the elderly with massive proximal femoral bone loss who require revision THA, with significant clinical improvement. While the survivorship of the implant is good at five years, dislocation continues to be the most common complication. The judicious use of larger femoral heads, dual-mobility constructs, or constrained liners may help to minimise the risk of dislocation. Cite this article: Bone Joint J 2017;99-B:325–9.

Background: Total knee arthroplasty (TKA) with a rotating-hinge prosthesis is considered a salvage procedure. While excellent immediate stability is achieved, the historically high failure rate has tempered its use. The goal of this study was to determine clinical outcomes, radiographic results, and survivorship after TKA with contemporary rotating-hinge components. Methods: We identified 408 consecutive TKAs performed with rotating-hinge components for nononcologic indications from 2002 to 2012 at a single academic institution. Two hundred and sixty-four knees (65%) had rotating-hinge TKA components implanted for aseptic etiologies, while 144 knees (35%) were managed with the components in 2-stage reimplantation following infection. Rotating-hinge TKA implants were used for complex primary procedures in 74 knees (18%) and as a revision construct in 334 knees (82%). Clinical outcomes were assessed with the Knee Society scoring system, survivorship analyses, and cumulative incidence of revision. The mean age of the patients at the time of the index arthroplasty was 69 years, and the mean duration of follow-up was 4 years (range, 2 to 12 years). Results: At the most recent follow-up, the mean Knee Society knee score had increased from 51 points preoperatively to 81 points (p < 0.0001), and the mean Knee Society functional score had increased from 26 to 36 points (p < 0.0001). At a mean of 4 years, loosening of components was observed in 13 (3.7%) of 349 knees. At the most recent follow-up, 59 revision procedures and 25 reoperations had been performed. The cumulative incidence of any revision was 9.7% at 2 years and 22.5% at 10 years. The cumulative incidence of revision for aseptic loosening was 1.7% at 2 years and 4.5% at 10 years. Metaphyseal cones were used in 114 knees (28%). Survivorship analysis revealed a trend toward a lower risk of revision (hazard ratio [HR] = 0.69; 95% confidence interval [CI] = 0.39 to 1.22; p = 0.20) and reoperation (HR = 0.51; 95% CI = 0.22 to 1.19; p = 0.12) in patients with metaphyseal cones, despite their use in the most severe of bone defects. Conclusions: Contemporary rotating-hinge TKA implants had a low 10-year cumulative incidence of revision for aseptic loosening of 4.5%. Greater use of metaphyseal fixation has aided this improvement. Patients can expect substantial improvements in clinical outcomes with this revision strategy. Level of Evidence: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Background: Two-stage exchange arthroplasty after a previous, failed 2-stage exchange procedure is fraught with difficulties, and there are no clear guidelines for treatment or prognosis given the heterogeneous group of patients in whom this procedure has been performed. The Musculoskeletal Infection Society (MSIS) staging system was developed in an attempt to stratify patients according to infection type, host status, and local soft-tissue status. The purpose of this study was to report the results of 2-stage exchange arthroplasty following a previous, failed 2-stage exchange protocol for periprosthetic knee infection as well as to identify risk factors for failure. Methods: We retrospectively identified 45 patients who had undergone 2 or more 2-stage exchange arthroplasties for periprosthetic knee infection from 2000 to 2013. Patients were stratified according to the MSIS system, and risk factors for failure were analyzed. The minimum follow-up was 2 years (mean, 6 years; range, 24 to 132 months). Results: At the time of follow-up, twenty-two (49%) of the patients had undergone another revision due to infection and 28 (62%) had undergone another revision for any reason. The infection recurred in 6 (75%) of 8 substantially immunocompromised hosts (MSIS type C) and in 3 (30%) of 10 uncompromised hosts (type A) following the second 2-stage exchange arthroplasty (p = 0.06). The infection recurred in 4 (80%) of 5 patients with compromise of the extremity (MSIS type 3) and 3 (33%) of 9 patients with an uncompromised extremity (type 1) (p = 0.27). Both extremely compromised hosts with an extremely compromised extremity (type C3) had recurrence of the infection whereas 3 (30%) of the 10 uncompromised patients with no or less compromise of the extremity (type A1 or A2) did. Five patients in the failure group underwent a third 2-stage exchange arthroplasty following reinfection, and 3 of them were infection-free at the time of the latest follow-up. Conclusions: Uncompromised hosts (MSIS type A) with an acceptable wound (MSIS type 1 or 2) had a 70% rate of success (7 of 10) after a repeat 2-stage exchange arthroplasty, whereas type-B2 hosts had a 50% success rate (10 of 20). The repeat 2-stage exchange procedure failed in both type-C3 hosts; thus, alternative salvage procedures should be considered for such patients. Level of Evidence: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

ABSTRACT We compared culture results to investigate the influence of antimicrobial-loaded cement on sonicate fluid culture positivity for the diagnosis of prosthetic joint infection. Fifty-four subjects were assessed. The sensitivities of sonicate fluid culture were 77.8% (14 of 18) in subjects with an antimicrobial-loaded cemented prosthesis and 58.3% (21 of 36) in subjects with an antimicrobial-free prosthesis.