INTRODUCTION. Progressive polyethylene wear is associated with the occurrence of osteolysis, which can lead to component loosening and subsequent revision. Massive wear of the polyethylene liner may result in the penetration of the femoral head through the metal shell. Although metallosis after total hip arthroplasty has been well documented in the literature, extensive metallosis with polyethylene wear-through has been only sparsely described. The purpose of the present study was to assess clinical findings and the results of revision total hip arthroplasty in these cases. METHODS. We evaluated seven hips in five patients who underwent revision total hip arthroplasty because of metallosis with polyethylene wear-through. The average age of the patients at the time of hip revision was 70.1 years. There were granulomatous cysts surrounding the hip joint and osteolysis in the greater trochanter or in the acetabulum. Eroded metal shells with worn-through polyethylene were exchanged. Kerboull-type acetabular reinforcement device were used in five hips and GAP cup in two. Distal interlocking femoral stems were used in four hips and extensively porous-coated stems in two. All cases with osteolysis were in addition treated with bulk or morselized allograft bone. The mean duration of follow-up was 3 years. RESULTS. At the time of final follow-up evaluation, none of the hips showed osteolysis. Stable fixation of femoral and acetabular components was achieved in all cases. Bulk allograft bone was resorbed in two cases, but in all other cases grafted bones were united and improve bone stock. CONCLUSIONS. Metallosis with polyethylene wear-through caused severe synovitis and massive osteolysis. Although debridement of the surrounding metallic stained tissue could not be completely done, the clinical result of revision surgery was favorable

Introduction

There is no doubt that the future of limb lengthening lies with internal lengthening. Complication rates are reduced and patient satisfaction is increased. The evolution of internal lengthening peaked with the dual direction, easily inserted and externally controlled PRECICE Nail. It has excelled in performance in accuracy and satisfaction. Its versatility increased with smaller sizes and increased excursion. A field safety notice was issued was issued in October 2021 by the parent company NuVasive. The advice was monitoring of current cases and a hold on implantation until after a review of process. At the National Orthopaedic Hospital Cappagh we elected to remove all implanted nails and assess the nail integrity and physiological changes associated with implantation.

Recent reports about the excellent clinical results of unicondylar knee arthroplasty (UKA; also known as unicompartmental knee arthroplasty), by the minimally invasive approach, have encouraged the adoption of the surgical technique. However, friction between metallic prosthetic components resulting from polyethylene wear may result in the development of metallosis and the use of metal implants has become a huge issue in the worlds recently. Here, we report a case in which a patient underwent UKA and developed metallosis in soft tissues and bone adjacent to an implanted artificial joint three years postoperatively.

Purpose

Complete wear-out of Polyethylene (PE) liner results in severe metallosis following articulation of the artificial head with the acetabular metal shell. We postulated that an adverse response can be led to surrounding bone tissue and new implant after revision surgery because the amount of PE wear particle is substantial and the metal particles are infiltrated in this catastrophic condition. We evaluated clinical characteristics and the survival rate of revision total hip arthroplasty (THA) performed in patients with severe metallosis following failure of PE liner.

INTRODUCTION

The risk of dislocation in large diameter metal on metal hip replacement is significantly lower than in standard THR. This is due to the increased primary arc, increased jump distance and possibly a suction effect. Our unit has performed over 1500 of these cases with an overall revision rate of <1%. We report a case series of dislocations in 5 large diameter metal on metal hips undertaken at our unit.

Introduction. In revision surgery, detection of periprosthetic joint infection is of prime importance. Valuable preoperative and intraoperative diagnostic tests and tools are necessary. The classical standard procedures are puncture and bacteriology examination, frozen section intraoperative and powerfield micro analysis. Since autumn 2014 a new device for detection of periprosthetic joint infection is available, named Synovasure. It is a fast test for the detection of Alpha defensing, which plays a major role in the antimicrobial defence and only occurs in inflammatory processes. „The alpha-defensin test is an immunoassay that measures the concentration of the alpha-defensin peptide in human synovialfluid. A-Defensin is an antimicrobial peptide that is secreted into the synovial fluid by human cells in response to pathogenic presence” (Deirmengian C et al., CORR 2014). Summarized, the evidence of Alpha defensin indicates infection. It is produced by CD Diagnostics (Wynnewood, PA, USA) and merchandised by Zimmer (Warsaw, IL, USA). We are using Synovasure in daily routine at our department since September 2014. The aim of this conducted study is to present our first clinical experience and to report our results of the first 54 cases. Material and Methods. At our department Synovasure is standardly used in hip and knee revision surgery. Additionally an intraoperative frozen section and a standard bacteriology were performed. The explanted endprosthesis were sent to examination by sonification in order to gain culture of the sonification fluid and were further examined by Multiplex PCR. A pathologist with more than 15 years of experience conducted the frozen section. The results of Synovasure were matched with all above examinations in order to describe specifity and sensitivity of it. Results. A negative Synovasure Test during surgery and a negative PCR were observed in 3 patients, however, the bacterial culture was positive (after 14 days of breeding) as well as the Multiplex PCR. One patient had a negative frozen section and a negative culture but a positive PCR. Another patient with a high CRP level, all clinical signs of infection and a positive Synovasure Test, had 6 negative cultures. This patient suffered from a Metallosis as well, due to a broken PE inlay of the TKA, which supports the previously stated that Metallosis may interfere this new tool. Unfortunately in this patient neither a frozen section nor a PCR are available. One patient, who had explanation due to infection, underwent reimplantation. During surgery the Synovasure Test and the frozen section were negative (Synovial Fluid), but postoperatively a positive culture and a positive histological report for infection were assessed. Furthermore, a total of 5 tests showed an application error and the test did not show any control line. Conclusion. In conclusion Synovasure helps to detect perprosthetic joint infection in an easy and fast manner. It is simple to integrate into daily routine, nevertheless all standardized examinations for infection need to be conducted

Aim. A key of success in the treatment of prosthetic joint infection (PJI) is the proper diagnosis. There is a lack of diagnostic tools able to diagnose a PJI with high accuracy. Alpha-defensin has been proposed as possible solution but the available literature is still limited. This prospective study was carried out in order to determine (1) what is the sensitivity, the specificity, the positive and the negative predictive value of the Alpha-defensin immunoassay test in diagnosing PJI; (2) which clinical features may be responsible for false positive and false negative results?. Method. Preoperative aspiration was performed in patients presenting with a painful hip/knee arthroplasty. Metallosis, other inflammatory comorbidities and previous/concomitant antibiotic therapy were not considered as exclusion criteria. Patients with inadequate amount of synovial fluid for culture were excluded. At time of revision synovial fluid samples were taken in the OR in order to perform Alpha-defensin assay. During surgical debridement tissue samples for cultures were obtained. Prospectively, 156 patients (65 knees and 91 hips) were included. A diagnosis of PJI was confirmed in 29 patients. Results. The sensitivity of the Alpha-defensin immunoassay was 97% (95% CI, 92% – 99%), the specificity was 97% (95% CI, 92% – 99%), the positive predictive value was 88% (95% CI, 81% – 92%) and the negative predictive value was 99% (95% CI, 96% – 99%). Among four false positive patients two had a metallosis and one had a polyethylene wear. The false negative case presented with a draining sinus, and intraoperative cultures were also negative. Conclusions. Alpha-defensin assay may have a significant role in PJI diagnosis. Negative tests may exclude the diagnosis of PJI. Positive tests are very much likely to confirm PJI, but other conditions (metallosis, poly wear) should be excluded

Controversy has existed for decades over the role of fretting-corrosion in modular CoCr heads used with stems of CoCr vs Ti6Al4V. Since retrieval data on taper performance remains scant, we report here an18-year survivorship of a Ti6Al4V: CoCr combination (APR design; Intermedics Inc). Unique to this study were the threaded profiles present on both stem and head tapers (Fig. 1). This female patient was revised for pain, osteolysis and recurrent hip dislocation at 17 years, 10 months. A prior MPE hip replacement performed for her severely dysplastic right hip had lasted 11 years. At this 2nd revision, the 28 mm CoCr head was found dislocated posteriorly and superiorly. Metallosis was evident in the tissues. The polyethylene liner showed extensive rim damage on both anterior and posterior aspects. The neck of her APR Revision stem (Intermedics Inc) had worn through the polyethylene rim and impinged on the metal cage. The cage was found loose, the liner had disassociated, and the peri-trochanteric areas were compromised by massive osteolysis. The femoral stem and head were removed together without disassembly. The femoral stem and acetabular construct were replaced by an ARCOS revision system using 36 mm head with a Freedom cup (cemented to Max-Ti cage; Biomet Inc.). The complete femoral neck and head were bi-valved assembled in horizontal plane for direct imaging by interferometry and SEM (Fig. 1a). After sectioning the head separated from the stem. Quantitative imaging used 1 to 5 regions with 6-replicate measurements per region and differentiation into contact and non-contact zones (Fig. 1b). Visual corrosion mapping (3) was recorded digitally in 4 anatomical views (Figs 1b–f). The thread profile on contact zone inside the head (Fig. 2a) had a pitch of approximately 40 μm and a peak-to-valley depth of 4 μm overall (Fig. 2b profile section of thread: PV = 2 μm). The thread profile on stem trunnion (Fig. 3a) had a pitch of approximately 125 μm and a peak-to-valley depth of 3.5 μm overall (Fig. 2b profile section of thread: PV = 1 μm). Thus the stem trunnion thread was much coarser than the head. Overall corrosion grading was judged very mild. Overall we were satisfied that this Ti6Al4V: CoCr combination taper junction with threaded interfaces had performed very well for 18 years. Nevertheless, our visual grading was subject to opinion and thus unrewarding. The continuing project will quantify the contacting and non-contacting regions of head and stem (Fig. 1b)

The modern generation of hip resurfacing arthroplasties was developed in the early 1990's with one of the original designs being the McMinn Resurfacing Total Hip System. This was a hybrid metal on metal prosthesis, with a smooth hydroxyapetite coated press fit mono block cobalt chrome shell with a cemented femoral component. Although no longer produced in this form, lessons may be learned from this original series of components. With metal on metal resurfacing arthroplasty now facing criticisms and concerns with regard function, bone preservation capability and soft tissue issues such as ‘pseudotumors’, it is the aim of this long-term study to assess the outcome and survival of an original series of resurfacing arthroplasties. 27 resurfacing arthroplasties were performed in 25 consecutive patients between June 1994 and November 1996. 16 right hips and 11 left were performed in 14 female patients and 11 male patients. The average age at the time of surgery was 50.5 years (SD 7.9, range 30-63). All surgeries were performed by a single surgeon using a posterior lateral approach. Following the initial early care, each patient received bi-annual follow up along with open access to the clinic with any concerns or complications. A retrospective review of the case notes was conducted and outcome scores retrieved from a prospectively updated database. Radiographs were analyzed and a Kaplan Meier survival chart was constructed for the group. At latest review 3 patients have died (5yrs, 8yrs and 13.8yrs) and 1 patient has been lost to follow up (5yrs). 7 resurfacings have required revision, all due to acetabular loosening, at a mean follow up of 7 years 11months (SD 2.03years, range 4-10). Metallosis was documented in 4 of the revision cases, however no extensive soft tissue inflammation or ‘pseudotumor’ identified. The mean follow up of the remaining 16 hips is 12years and 10months (SD 12.8months, Range 10.4yrs-14.0 years). The Kaplan Meier survival at a minimum follow up of 10 years is 75.8% (95% CI 0.67-0.95). Mean Oxford hip scores at latest follow up was 20.6 (SD 8.8, range 12-38). There was no significant difference between cup inclination angles for the surviving cohort and those who required a revision procedure with mean cup inclinations of 52.5 (SD 5.5, range 45-60) and 58 degrees respectively (SD 9.1, range 50-70)(p=0.255). This original series of hip resurfacings, with up to 14 years follow up, shows a survival of 76% at the minimum follow up of 10 years. All failures were due to loosening of the smooth backed acetabulum, which with a modern porous coating, failure may have been avoided or delayed. Despite high inclinations angles no soft tissue reactions were identified within this series. No femoral failures were identified suggesting unlike much literature focus, long-term failure may not be related to the femoral head or neck

Aims

The aim of this study was to analyze the prevalence of culture-negative periprosthetic joint infections (PJIs) when adequate methods of culture are used, and to evaluate the outcome in patients who were treated with antibiotics for a culture-negative PJI compared with those in whom antibiotics were withheld.