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Primary total hip arthroplasty after infection.

Only a few of the more than 200,000 total hip arthroplasties performed annually in the United States are done after an infection of the hip joint or the proximal aspect of the femur.nnAlthough some infections produce severe early destruction of the hip joint, most patients, if treated promptly, regain good hip function and do not present again until much later in life, when secondary degenerative changes have occurred1. It is therefore necessary to be aware of the possibility of a previous infection and to inquire about it specifically.nnThe first recurrence of bone infection may be delayed for many decades. Gallie2 reported a case of femoral osteomyelitis in a ten-year-old girl that did not recur until after nearly eighty years. The risk that a previous infection of the hip region poses to a hip prosthesis is multifactorial. The type of infection (osteomyelitis or septic arthritis), the level of activity of the infection (active or quiescent), the time since the infection (recent or historical), the organism (pyogenic, tuberculous, or fungal), and the reconstruction technique all contribute to the outcome.nn### OsteomyelitisnnEver since Staphylococcus aureus was first isolated from osteomyelitis by Pasteur3 in the late nineteenth century, it has remained the predominant infecting organism, implicated in approximately 90% of infections where an organism is isolated (range, 88% [140 of 159] to 95% [392 of 411])4,5. The infecting organisms in the remaining cases are largely Staphylococcus epidermidis and streptococci.nnMore recently, there has been a shift in the prevalence of certain causative organisms, with fewer infections caused by Staphylococcus aureus . There has also been a significant increase (from eight of sixty-five cases to eight of nineteen cases; p < 0.001) in the proportion of cases that are subacute and that have a greater tendency …

The use of bone cement for the localized, controlled release of the antibiotics vancomycin, linezolid, or fusidic acid: effect of additives on drug release rates and mechanical strength

Bone cement containing antibiotics is commonly used to treat orthopedic related infections. However, effective treatment (especially of resistant bacteria, methacillin-resistant Staphylococcus aureus (MRSA)) is compromised by very low levels of drug release so that typically less than 10% of loaded drug is released over a 6-week period. The objective of this study was to investigate the effect of incorporation of water soluble excipients (polyethylene glycol, sodium chloride, or dextran) into antibiotic-loaded cement on mechanical strength and drug release properties. Poly(methyl methylacrylate) cement implants containing various amounts of drug (vancomycin, linezolid or fusidic acid (all MRSA active)) and excipients were cast in the form of beads or films and characterized using differential scanning calorimetry. Mechanical strength as assessed by Young’s modulus was determined by thermo-mechanical analysis. Drug release was measured by incubation in phosphate buffered saline with analysis by HPLC methods. The inclusion of sodium chloride up to 20% w/w caused only minor reductions in Young’s modulus. Vancomycin and linezolid released very slowly from unmodified bone cement beads (less than 3% released by 4xa0weeks) whereas fusidic acid released more quickly (approximately 8% released by 4xa0weeks). The inclusion of sodium chloride or dextran in bone cement resulted in major increases in the release rate of vancomycin, linezolid and fusidic acid. These studies support the inclusion of sodium chloride and dextran in bone cement to increase the release rate of vancomycin, linezolid, or fusidic acid without compromising the mechanical strength of the composite material.

Role and results of tapered fluted modular titanium stems in revision total hip arthroplasty

Tapered, fluted, modular, titanium stems have a long history in Europe and are increasing in popularity in North America. We have reviewed the results at our institution looking at stem survival and clinical outcomes. Radiological outcomes and quality of life assessments have been performed and compared to cylindrical non-modular cobalt chromium stems. Survival at five years was 94%. This fell to 85% at ten years due to stem breakage with older designs. Review of radiology showed maintenance or improvement of bone stock in 87% of cases. Outcome scores were superior in tapered stems despite worse pre-operative femoral deficiency. Tapered stems have proved to be a useful alternative in revision total hip arthroplasty across the spectrum of femoral bone deficiency.

Structural proximal femoral allografts for failed total hip replacements

There are few medium- and long-term data on the outcome of the use of proximal femoral structural allografts in revision hip arthroplasty. This is a study of a consecutive series of 40 proximal femoral allografts performed for failed total hip replacements using the same technique with a minimum follow-up of five years (mean 8.8 years; range 5 to 11.5 years). In all cases the stem was cemented into both the allograft and the host femur. The proximal femur of the host was resected in 37 cases.nnThere were four early revisions (10%), two for infection, one for nonunion of the allograft-host junction, and one for allograft resorption noted at the time of revision of a failed acetabular reconstruction. Junctional nonunion was seen in three patients (8%), two of whom were managed successfully by bone grafting, and bone grafting and plating respectively. Instability was observed in four (10%). Trochanteric nonunion was seen in 18 patients (46%) and trochanteric escape in ten of these (27%). The mean Harris hip score improved from 39 to 79. Severe resorption involving the full thickness of the allograft was seen in seven patients (17.5%). This progressed rapidly and silently, but has yet to cause failure of any of the reconstructions.nnProfound resorption of the allograft may be related to a combination of factors, including a slow form of immune rejection, stress shielding and resorption due to mechanical disuse with solid cemented distal fixation, and the absence of any masking or protective effect which may be provided by the retention of the bivalved host bone as a vascularised onlay autograft. Although continued surveillance is warranted, the very good medium-term clinical results justify the continued use of structural allografts for failed total hip replacements with severe loss of proximal femoral bone.

Acute Kidney Injury With Tobramycin-Impregnated Bone Cement Spacers in Prosthetic Joint Infections

Background: Antibiotic-impregnated bone cement spacer (ACS) with tobramycin ± vancomycin is commonly used in a 2-stage replacement of infected prosthetic joints. This procedure has been associated with development of acute kidney injury (AKI). Objective: To determine the incidence and risk factors for AKI after implantation of tobramycin-impregnated ACS. Methods: This prospective, observational study evaluated 50 consecutive patients who received tobramycin ACS for first-stage revision of an infected hip or knee arthroplasty from August 2011 to February 2013. AKI was defined as 50% or greater rise in serum creatinine (SCr) from baseline within the first 7 postoperative days (PODs). Results: The incidence of AKI was 20%, with median onset occurring at POD 2 (interquartile range [IQR] = 1-3); patients with AKI had a longer median duration of hospital stay (16 days, IQR = 12-17, vs 10 days, IQR = 8-10; P = 0.03). Serum tobramycin concentrations were significantly higher in the AKI group, peaking on POD 1 (median 1.9 vs 0.9 µg/mL, P = 0.01). Risk factors for nephrotoxicity identified by multivariate analysis were use of bone cement premanufactured with gentamicin (OR = 8.2; 95% CI = 1.1-60; P = 0.04), administration of blood transfusions intraoperatively (OR = 32.5; 95% CI = 2.3-454.3; P = 0.01) and nonsteroidal anti-inflammatory drugs postoperatively (OR = 23.0; 95% CI = 1.3-397.7; P = 0.03). Conclusions: Tobramycin ACS is associated with a high risk of AKI. Measures to minimize AKI risk in the perioperative period include early detection through close monitoring of SCr, avoiding use of premanufactured bone cement containing gentamicin, and avoiding potential nephrotoxins within the first 72 hours postoperatively.

Instructional Course Lectures, The American Academy of Orthopaedic Surgeons - Primary Total Replacement of the Dysplastic Hip*†

Developmental abnormalities following such childhood conditions as congenital dislocation and dysplasia of the hip, Legg-Calve-Perthes disease, and slipped capital femoral epiphysis are the most common cause of secondary osteoarthritis of the hip3,43 and may be a cause of degeneration in a large portion of patients with so-called idiopathic osteoarthritis of the hip43. Despite concerted screening programs, a large number of patients still have the sequelae of dysplasia or dislocation of the hip in adulthood37,117.nnThe severity of hip dysplasia varies widely, ranging from the shallow acetabulum to the completely dislocated and so-called high-riding hip. Osteoarthritis of the hip secondary to hip dysplasia, therefore, presents a broad spectrum of reconstructive challenges. Hips that have mild anatomical abnormalities can be treated with standard primary total hip replacements, but until recently others would have been labeled unreconstructible16. Because patients who have hip dysplasia are often young and active, it is critical to understand the complexities of total hip replacement in this group and to plan any interventions meticulously. To this end, the nature and the extent of the preoperative deformities and abnormalities must be understood, and the problems that have been obstacles to obtaining satisfactory fixation with acceptable long-term function must be addressed. In this paper, we present an overview of the classification and assessment of the dysplastic hip with secondary osteoarthritis and summarize the current knowledge about total hip arthroplasty in patients who have this disorder.nnA thorough understanding of both the clinical and the radiographic anatomy of the dysplastic hip is necessary in order to plan and perform a reconstruction of the hip that will yield satisfactory long-term results. This anatomy may be distorted by the primary disorder and by the effects of previous operations.nnThe anatomical abnormalities that are …

Instructional Course Lectures, The American Academy of Orthopaedic Surgeons - Femoral Bone Loss in Total Hip Arthroplasty: Classification and Preoperative Planning*†

A single comprehensive classification system that can adequately describe all types of bone loss associated with hip arthroplasty should become a standard for reporting purposes. There is a need for a critical appraisal of the classification systems currently in use and, through a consensus, for development of a system that will permit comparison between the reported results of different techniques. Although no one classification system is ideal, the one proposed by the AAOS Committee on the Hip is the most comprehensive and the most consistently used. It addresses not only revision total hip arthroplasty but also primary hip replacement. It also addresses other conditions related to problems with the bone stock, such as those resulting from a previous hip arthrodesis on the acetabular side and femoral stenosis and malalignment on the femoral side. The only drawback to this classification system is its complexity; however, the problem of acetabular and femoral bone loss is of sufficient complexity and variety that a simple classification system, although ideal, cannot be comprehensive. Regardless of the absence of a common language and a comprehensive classification system that is applicable to all types of reconstructions, it is clear that femoral bone loss is a problem that will continue to challenge orthopaedic surgeons. It is only by careful and methodical analysis of patients who have femoral bone loss and by meticulous attention being paid to detail in preoperative evaluation and investigation, surgical planning, and the recording of outcomes that we will be able to improve our treatment of this difficult problem.

Trunnion corrosion: what surgeons need to know in 2018

Aims To present a surgically relevant update of trunnionosis. Materials and Methods Systematic review performed April 2017. Results Trunnionosis accounts for approximately 2% of the revision total hip arthroplasty (THA) burden. Thinner (reduced flexural rigidity) and shorter trunnions (reduced contact area at the taper junction) may contribute to mechanically assisted corrosion, exacerbated by high offset implants. The contribution of large heads and mixed metallurgy is discussed. Conclusion Identifying causative risk factors is challenging due to the multifactorial nature of this problem.

Revision for adverse local tissue reaction following metal-on-polyethylene total hip arthroplasty is associated with a high risk of early major complications

Aims Fretting and corrosion at the modular head/neck junction, known as trunnionosis, in total hip arthroplasty (THA) is a cause of adverse reaction to metal debris (ARMD). We describe the outcome of revision of metal‐on‐polyethylene (MoP) THA for ARMD due to trunnionosis with emphasis on the risk of major complications. Patients and Methods A total of 36 patients with a MoP THA who underwent revision for ARMD due to trunnionosis were identified. Three were excluded as their revision had been to another metal head. The remaining 33 were revised to a ceramic head with a titanium sleeve. We describe the presentation, revision findings, and risk of complications in these patients. Results The patients presented with pain, swelling, stiffness, or instability and an inflammatory mass was confirmed radiologically. Macroscopic material deposition on the trunnion was seen in all patients, associated with ARMD. Following revision, six (18.2%) dislocated, requiring further revision in four. Three (9.1%) developed a deep infection and six (18.2%) had significant persistent pain without an obvious cause. One developed a femoral artery thrombosis after excision of an iliofemoral pseudotumor, requiring a thrombectomy. Conclusion The risk of serious complications following revision MoP THA for ARMD associated with trunnionosis is high. In the presence of extensive tissue damage, a constrained liner or dual mobility construct is recommended in these patients.

Total hip arthroplasty in patients with neuromuscular imbalance

Patients with neuromuscular imbalance who require total hip arthroplasty (THA) present particular technical problems due to altered anatomy, abnormal bone stock, muscular imbalance and problems of rehabilitation. In this systematic review, we studied articles dealing with THA in patients with neuromuscular imbalance, published before April 2017. We recorded the demographics of the patients and the type of neuromuscular pathology, the indication for surgery, surgical approach, concomitant soft‐tissue releases, the type of implant and bearing, pain and functional outcome as well as complications and survival. Recent advances in THA technology allow for successful outcomes in these patients. Our review suggests excellent benefits for pain relief and good functional outcome might be expected with a modest risk of complication.