Loose Hip Research Articles

Клинико-экономический анализ эффективности использования индивидуальных и серийных имплантатов при эндопротезировании тазобедренного и коленного суставов.

One of the pressing issues of modern medicine is the need to improve the results of surgical treatment of patients with stage III osteoarthritis of large joints (according to the classification of N. S. Kosinskaya), as well as with loosening of the components of hip and knee joints through the use of techniques that have high clinical and economic efficiency and including the use of computer modeling and additive 3D printing technologies. Purpose of the study: to conduct a clinical and economic analysis of the effectiveness of using individual and serial components of endoprostheses in the surgical treatment of patients with stage III hip osteoarthritis (according to N. S. Kosinskaya’s classification), as well as with loosening of hip and knee joint implants. Methods: clinical-radiological, computed tomographic, biomechanical, statistical, analytical, sociological. The study included 348 patients who were divided into 10 groups depending on the individual and serial components of implants used in their treatment. Results. The effectiveness of surgical treatment of stage III hip osteoarthritis using individual acetabular implants in primary hip replacement, assessed using QALYs, was 0.79, and the CER (“cost-effectiveness”) indicator was 350,424.7. Moreover, the use of only serial imlants in a similar operation led to a decrease in CER to 262,977.2 and QALY to 0.63. Higher QALYs have also been observed with the use of additive technologies in revision hip arthroplasty. The effectiveness of surgical treatment using individual implants for type IIIa acetabular defect was 0.77 (CER – 341,110), for type IIIb – 0.6 (CER – 496,754.3). When using serial components of a revision hip joint implants for type IIIa acetabular defect, the QALY was 0.4 (CER – 540,462.5), for type IIIb – 0.4 (CER – 653,500.5). The best QALYs (0.15) and CER (1,348,892) were also obtained with the use of individual acetabular implants made of bone cement in hip replacement for periprosthetic infection in comparison with standard spacers (QALY – 0.07; CER – 2,845 801). The effectiveness of surgical treatment of patients with bone defects of type 2B and 3 according to AORI using individual implants during revision knee arthroplasty was 0.83 (CER – 494,236.8), using serial designs – 0.44 (CER – 939,489, 4). Conclusions. The use of individual implants in total replacement in patients with stage III hip osteoarthritis (according to N. S. Kosinskaya’s classification), as well as loosening of hip and knee implants, made it possible to achieve higher rates of effectiveness of surgical treatment in comparison with implantation of only serial structures. The use of additive 3D printing technologies in all cases, except knee joint replacement for bone defects of types 2B and 3 according to AORI, led to increased costs for treating patients. As a result of the clinical and economic analysis, it was revealed that the use of individual implants made using 3D printing in revision hip arthroplasty for IIIa and IIIb defects of the acetabulum, septic loosening of the components of a previously installed implants, as well as in re-replacement of the knee joint in the presence of AORI type 2B and 3 bone defects achieves the best cost-effectiveness ratio (CER) and is “strongly preferable” to implantation of serial constructs only.

Postcranial skeleton of Goodwin's brush-tailed mouse (Calomyscus elburzensis Goodwin, 1939) (Rodentia: Calomyscidae): Shape, size, function, and locomotor adaptation.

Goodwin's brush-tailed mouse (Calomyscus elburzensis Goodwin, 1939) is a poorly known small rodent that occupies rocky habitats in Iran, Turkmenistan, Afghanistan, Pakistan, Azerbaijan, and Syria. Herein, a detailed description of the shape, size, and function of the postcranial skeleton of this species is presented for the first time. Trapping was carried out in eastern Iran between the years 2013 and 2015. Skeletal parts of 24 adult male specimens were removed using the papain digestion protocol, and several postcranial morphological characteristics and measurements were examined. We attempted to achieve a morpho-functional characterization of Goodwin's brush-tailed mouse and to match morphological specializations with previous information on the ecology, behavior, and phylogenetic inferences of this rodent. Goodwin's brush-tailed mouse has extended transverse processes and long zygapophyses in the first five caudal vertebrae along with a good innervation of the caudal vertebrae, which has resulted in a well-developed basal musculature of the tail. It has extended forelimb, long ilium, and short post-acetabular part of the innominate bone, loose hip joint with high degree of lateral movement of the hindlimb, and long distal elements of the hindlimb. These features have resulted in fast terrestrial movements in open microhabitats, including climbing and jumping. Although superficial scratching of the ground is observed, the species is incapable of digging burrows. Evaluation of postcranial morphological characteristics and character states further indicated the basal radiation of the genus Calomyscus among other Muroidea. Findings constitute a source of information for morpho-functional and phylogenetic comparisons between Calomyscidae and other mouse-like muroids.

Synovial Calprotectin for Diagnosing Periprosthetic Joint Infection in Loose Hip and Knee Arthroplasties: A Prospective Cohort Study.

Synovial calprotectin has been demonstrated as a promising biomarker for periprosthetic joint infections (PJI) in painful total hip (THA) and knee arthroplasties (TKA). However, its diagnostic utility has not been evaluated explicitly in cases with marked loosening or migration of the implant. Concerns have already been raised in cases with metallosis and severe periprosthetic osteolysis because wear-induced inflammation may yield false positive results. The purpose of this study was to evaluate calprotectin for the diagnosis of PJI in cases that preoperatively demonstrate moderate to severe periprosthetic osteolysis or implant migration as signs for implant loosening in THA and TKA. Thirty-three patients were included in this prospective study between February of 2019 and November of 2021. The extent of osteolysis was classified according to Engh et al., Paprosky et al., and the modern Knee Society Radiographic Evaluation and Scoring System. Synovial white blood cell count (WBC), percentage of polymorphonuclear neutrophils (PMC), serum C-reactive protein (CRP) and synovial calprotectin using a lateral-flow-assay were tested against the European Bone and Joint Infection Society (EBJIS) definition for PJI. Statistic quality criteria were calculated and compared using a binary classification test. Ten patients were classified as confirmed infections according to the EBJIS definition (7 THA and 5 TKA). The calprotectin assay yielded a sensitivity of 0.60, a specificity of 0.61, a positive predictive value of 0.40, and a negative predictive value of 0.78. The calprotectin assay resulted in nine false positive and four false negative cases. No correlation between the extent of osteolysis and false classification by means of the calprotectin assay was observed. The diagnostic accuracy of synovial calprotectin is impaired if moderate to severe signs of implant loosening are present. If PJI is unlikely, the calprotectin LFT can be applied as a further exclusion tool as the negative predictive value remains relatively high.

Prosthetic Hip Loosening Due to Brucellar Infection: Case Report and Literature Review

Context:Brucellosis is actually considered to be the commonest zoonotic infection worldwide; conversely prosthetic infection due to brucella is extremely rare. Although diagnostic is easily achieved, management of such situations is extremely challenging.AimsTo report the case of prosthetic hip loosening due to brucellar infection, discuss management manners and to summarize data about 19 cases reported in the literature.MethodsWe report the case of a 73-year-old woman with brucellar prosthetic hip loosening treated with 2-stage exchange of the prosthesis and prolonged double antibiotherapyResultsAt two years follow up the patient is pain free with total functional recovery and no clinical and radiographic signs of prosthetic looseningConclusionsBrucella should be evocated as a cause of total joint arthroplasty infection especially in patients from endemic regions and with occupational exposure. Antibiotic treatment alone can be followed if there are no signs of implant loosening. Tow stage revision should be considered in other cases.

Periprosthetic fracture around a loose hip or knee arthroplasty

The number of people having total hip or knee replacement is growing at a steady rate; additionally total joint arthroplasty is being performed more frequently in younger patients with higher demands than has been previously observed. These factors working in concert generate an increased risk of periprosthetic fractures. The growing incidence of these injuries creates an impetus for orthopaedic surgeons to be more comfortable with their treatment. Periprosthetic fractures around loose hip or knee arthroplasty components represent a unique and challenging clinical problem, requiring a skill set drawing from advanced techniques in orthopaedic traumatology and revision arthroplasty. This review outlines the principles in tackling these difficult cases including fracture reduction maneuvers, provisional fixation, revision instrumentation, implant choices, and supplemental fixation around revision components. The primary objective of this study was to supply practical tips and tricks to supplement the knowledge of orthopaedic traumatologists and adult reconstruction surgeons so that they are able to effectively treat these complex injuries successfully.

Lipoteichoic acid modulates inflammatory response in macrophages after phagocytosis of titanium particles through Toll-like receptor 2 cascade and inflammasomes.

Toll-like receptor 2 (TLR2) and nucleotide-binding and oligomerization domain-like receptors with a pyrin domain 3 (NLRP3) inflammasomes have been presumed to participate in the pathogenesis of aseptic implant loosening. The aim of this study is to analyze the cellular localization of TLR2 and NLRP3 inflammasomes in the periprosthetic tissue from aseptically loose hip implants as well as the expression of these molecules in macrophages stimulated in vitro with titanium particles (Ti) coated with lipoteichoic acid (LTA). Using immunohistochemistry, immunoreactivity of TLR2 and NLRP3 inflammasomes was found in macrophages within the foreign body granulomatosis. Using RAW264.7 cells, stimulation with Ti increased the messenger RNA (mRNA) levels of TLR2 and TNF-α. Stimulation with LTA-coated Ti enhanced mRNA levels of NLRP3 and IL-1β, whereas reinforced secretion of IL-1β was not detected in spite of marked release of TNF-α. Finally, the same cells with silenced Irak2, an adaptor protein in the TLR2 cascade, suppressed this NLRP3 upregulation. This study suggests that TLR2 and NLRP3 inflammasomes are factors involved in cross-talk mediating the foreign body type response to wear particles. In addition, discrepant behavior in the release between TNF-α and IL-1β release may explain the variable pathomechanisms of aseptic implant loosening without acute inflammatory reactions.

Feasibility of asymmetric flow field-flow fractionation coupled to ICP-MS for the characterization of wear metal particles and metalloproteins in biofluids from hip replacement patients.

Hip replacements are used to improve the quality of life of people with orthopaedic conditions, but the use of metal-on-metal (MoM) arthroplasty has led to poor outcomes for some patients. These problems are related to the generation of micro- to nanosized metal wear particles containing Cr, Co or other elements, but the current analytical methods used to investigate the processes involved do not provide sufficient information to understand the size or composition of the wear particles generated in vivo. In this qualitative feasibility study, asymmetric flow field-flow fractionation (AF(4)) coupled with inductively coupled plasma mass spectrometry (ICP-MS) was used to investigate metal protein binding and the size and composition of wear metal particles present in serum and hip aspirates from MoM hip replacement patients. A well-established HPLC anion exchange chromatography (AEC) separation system coupled to ICP-MS was used to confirm the metal-protein associations in the serum samples. Off-line single particle ICP-MS (spICP-MS) analysis was used to confirm the approximate size distribution indicated by AF(4) of the wear particles in hip aspirates. In the serum samples, AF(4) -ICP-MS suggested that Cr was associated with transferrin (Tf) and Co with albumin (Alb) and an unidentified species; AEC-ICP-MS confirmed these associations and also indicated an association of Cr with Alb. In the hip aspirate sample, AF(4)-ICP-MS suggested that Cr was associated with Alb and Tf and that Co was associated with Alb and two unidentified compounds; AEC analysis confirmed the Cr results and the association of Co with Alb and a second compound. Enzymatic digestion of the hip aspirate sample, followed by separation using AF(4) with detection by UV absorption (280nm), multi-angle light scattering and ICP-MS, suggested that the sizes of the Cr-, Co- and Mo-containing wear particles in a hip aspirate sample were in the range 40-150nm. Off-line spICP-MS was used to confirm these findings for the Co- and Cr-containing nanoparticles. Whilst limited in scope, the results are sufficient to show the interaction of ions with transport proteins and give an indication of particle size, providing useful pathological indices. As such, the methods indicate a new way forward for in vivo investigation of the processes which lead to tissue necrosis and hip loosening in patients with MoM hip replacements.

The Accuracy of Single Photon Emission Computed Tomography/Computed Tomography Arthrography in Evaluating Aseptic Loosening of Hip and Knee Prostheses

Aseptic loosening represents the most common complication associated with hip and knee arthroplasty and is a common indication for surgical revision in the post-arthroplasty population. The optimal imaging methodology in evaluating clinical suspected loosening is not well-defined. Our study retrospectively evaluated nuclear medicine arthrography with hybrid single photon emission computed tomography/computed tomography (SPECT/CT) in 38 patients (21 hip, 17 knee) compared with reference standards of surgical evaluation, spontaneous resolution of symptoms without revision, or a minimum of 1year clinical and radiographic follow-up. Our study demonstrated a sensitivity of 100%, specificity of 96.0%, PPV of 92.9%, NPV of 100%, and accuracy of 97.4% with this imaging technique suggesting utility of nuclear medicine arthrography with SPECT/CT in the clinical evaluation of suspected aseptic loosening.

Waterjet cutting of periprosthetic interface tissue in loosened hip prostheses: An in vitro feasibility study

Waterjet cutting technology is considered a promising technology to be used for minimally invasive removal of interface tissue surrounding aseptically loose hip prostheses. The goal of this study was to investigate the feasibility of waterjet cutting of interface tissue membrane. Waterjets with 0.2 mm and 0.6 mm diameter, a stand-off distance of 5 mm, and a traverse speed of 0.5 mm/s were used to cut interface tissue samples in half. The water flow through the nozzle was controlled by means of a valve. By changing the flow, the resulting waterjet pressure was regulated. Tissue sample thickness and the required waterjet pressures were measured. Mean thickness of the samples tested within the 0.2 mm nozzle group was 2.3 mm (SD 0.7 mm) and within the 0.6 mm nozzle group 2.6 mm (SD 0.9 mm). The required waterjet pressure to cut samples was between 10 and 12 MPa for the 0.2 mm nozzle and between 5 and 10 MPa for the 0.6 mm nozzle. Cutting bone or bone cement requires about 3 times higher waterjet pressure (30–50 MPa, depending on used nozzle diameter) and therefore we consider waterjet cutting as a safe technique to be used for minimally invasive interface tissue removal.

Mechanical properties of human bone–implant interface tissue in aseptically loose hip implants

The main cause of failure in total hip replacement is aseptic loosening which is associated with the formation of a periprosthetic fibrous (interface) tissue. Despite important applications for finite element modeling of loose implants, the mechanical properties of the bone–implant interface tissue have never been measured in humans. In this study, we performed unconfined compression tests to characterize the mechanical properties of the interface tissue and to determine the parameters of various hyperelastic material models which were fitted to the measurements. Human interface tissues were retrieved during 21 elective revision surgeries from aseptically loosened cemented (N=10) and uncemented hip implants (N=11). Specimens were tested at a fixed deformation rate of 0.1mm/min up to a maximum force of 10N. Elastic moduli for low and high strain regions of the stress–strain curves were determined. Interface tissue from aseptically loose cemented prostheses shows higher elastic moduli (mean=1.85MPa, 95% C.I.=1.76–1.95MPa) in the high strain region as compared to that of the interface tissue from the cementless group (mean=1.65MPa, 95% C.I.=1.43–1.88MPa). The 5-terms Mooney–Rivlin model (W=C1[I1−3]+C2[I2−3]+C3[I1−3][I2−3]+C4[I1−3]2+C5[I2−3]2) described the stress–strain behavior the best. Large variations in the mechanical behavior were observed both between specimens from the same patient as between those of different patients. The material model parameters were therefore estimated for the mean data as well as for the curves with the highest and lowest strain at the maximum load. The model parameters found for the mean data were C1=−0.0074MPa, C2=0.0019MPa, C3=0MPa, C4=−0.0032MPa and C5=0MPa in the cemented group and C1=−0.0137MPa, C2=0.0069MPa, C3=0.0026MPa, C4=−0.0094MPa and C5=0MPa in the cementless group. The results of this study can be used in finite element computer.

Percutaneous bone cement refixation of aseptically loose hip prostheses: the effect of interface tissue removal on injected cement volumes.

To quantify whether injected cement volumes differed between two groups of patients who underwent experimental minimally invasive percutaneous cement injection procedures to stabilize aseptically loose hip prostheses. One patient group was preoperatively treated using gene-directed enzyme prodrug therapy to remove fibrous interface tissue, while the other group received no preoperative treatment. It was hypothesized that cement penetration may have been inhibited by the presence of fibrous interface tissue in periprosthetic lesions. We analyzed 17 patients (14 female, 3 male, ages 72-91, ASA categories 2-4) who were treated at our institution. Osteolytic lesions and injected cement were manually delineated using 3D CT image segmentation, and the deposition of injected cement was quantified. Patients who underwent preoperative gene-directed enzyme therapy to remove fibrous tissue exhibited larger injected cement volumes than those who did not. The observed median increase in injected cement volume was 6.8 ml. Higher cement leakage volumes were also observed for this group. We conclude that prior removal of periprosthetic fibrous interface tissue may enable better cement flow and penetration. This might lead to better refixation of aseptically loosened prostheses.

Characterization of macrophage polarizing cytokines in the aseptic loosening of total hip replacements.

Aseptic loosening of hip replacements is driven by the macrophage reaction to wear particles. The extent of particle-induced macrophage activation is dependent on the state of macrophage polarization, which is dictated by the local cytokine microenvironment. The aim of the study was to characterize cytokine microenvironment surrounding failed, loose hip replacements with an emphasis on identification of cytokines that regulate macrophage polarization. Using qRT-PCR, the expression of interferon gamma (IFN-γ), interleukin-4 (IL-4), granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-13, and IL-17A was low and similar to the expression in control synovial tissues of patients undergoing primary hip replacement. Using immunostaining, no definite source of IFN-γ or IL-4 could be identified. IL-17A positive cells, identified as mast cells by double staining, were detected but their number was significantly reduced in interface tissues compared to the controls. Significant up-regulation of IL-10, M-CSF, IL-8, CCL2-4, CXCL9-10, CCL22, TRAP, cathepsin K, and down regulation of OPG was seen in the interface tissues, while expression of TNF-α, IL-1β, and CD206 were similar between the conditions. It is concluded that at the time of the revision surgery the peri-implant macrophage phenotype has both M1 and M2 characteristics and that the phenotype is regulated by other local and systemic factors than traditional macrophage polarizing cytokines.

Substance P enhanced titanium particles-induced RANKL expression in fibroblasts from periprosthetic membrane

Aseptic loosening remains the primary cause of failure in total joint arthroplasty. Implant-derived particles are thought to be a main cause of osteolysis that leads to the failure. Substance P (SP) immunoreactive nerve fibers have been detected in the periprosthetic membrane of aseptic loose hip prostheses. We isolated fibroblasts from periprosthetic membrane. Fibroblasts were examined by real-time RT-PCR and enzyme-linked immunosorbent assay for expression of the receptor activator of nuclear factor kappa B ligand (RANKL), osteoprotegerin (OPG), cyclooxygenase (COX)-1, and COX-2. Experiments were performed in the presence and absence of titanium particles, SP and NS-398 (a selective COX-2 inhibitor). Titanium particles or SP stimulated RANKL and COX-2 expression in fibroblasts, whereas NS-398 inhibited RANKL production, suggesting a COX-2-mediated event. Moreover, SP enhanced COX-2 and RANKL expression by titanium particles-stimulated fibroblasts. Thus, SP and titanium particles acted synergistically to increase RANKL expression.

Lubricin and smooth muscle α-actin-containing myofibroblasts in the pseudomembranes around loose hip and knee prostheses

The objective was to evaluate the presence and distribution of the lubricating and anti-adhesion glycoprotein lubricin and cells containing the contractile isoform smooth muscle α-actin (SMA) in pseudomembranes around loose hip prostheses. Periprosthetic tissue was obtained at revision arthroplasty of eight aseptic, loose hip implants, and for comparison three loose knee prostheses. Immunohistochemical analysis was performed in 3 zones: zone 1, within 300μm of the edge of the implant–tissue interface; zone 2, between zones 1 and 3; zone 3, within 300μm of the resected/trimmed edge. The presence of lubricin was extensive in all samples: (1) as a discrete layer at the implant–tissue interface; (2) within the extracellular matrix (ECM); (3) intracellularly. There was significantly more high grade (>50%) lubricin surface staining at the implant–tissue interface compared with the resected edge. While there was also a significant effect of location of high grade ECM lubricin staining, there was no significant effect of implant type (i.e. hip versus knee). All but two hip pseudomembrane samples showed the presence of many SMA-containing cells. There was a significant effect of location on the number of SMA-expressing cells, but not of implant type. These findings might explain why the management of loose prosthesis is so challenging.

On stabilization of loosened hip stems via cement injection into osteolytic cavities

BackgroundCement injection into osteolytic areas around the cement mantle is a technique for refixation of loose hip implants for patients who cannot undergo standard revision surgery. Preliminary clinical results show the improvement in walking distance, patients' independence and pain relief. MethodsIn this study, we use a detailed finite element model to analyze whether cement injection into osteolytic areas contributes to the overall implant stability. We study the effect of various factors, like location and size of osteolytic areas, interface conditions and bone stiffness on bone–cement relative motion. FindingsPresented results demonstrate that the procedure is most effective for the osteolytic areas located in the proximal region of the femur, while factors like a thin layer of residual fibrous tissue around the injected cement, that was not removed during the surgery, combined with reduced bone stiffness reduce the efficiency of the procedure. InterpretationCement injection is able to stabilize loosened hip prostheses. However, it is important to remove the fibrous tissue layer completely, as even a thin layer will negatively influence stabilization. We will focus our research efforts on developing fibrous tissue removal techniques in order to optimize this minimally invasive treatment.

Partial Hip Resurfacing for an Osteochondral Defect of the Femoral Head: A Case Report.

Hip resurfacing is a well-accepted surgical procedure for arthritic conditions of the hip, with good results reported in several series1-3. Hemiresurfacing procedures isolated to the femoral head have not had favorable results in many series4-6. Recently, a contoured articular prosthetic device (HemiCAP; Arthrosurface, Franklin, Massachusetts) has been released for use in the shoulder, knee, and hip to address full-thickness localized osteochondral defects as an alternative to osteochondral grafting. A recent study7 has suggested that this device might be biomechanically disadvantageous with certain in vivo applications. To the best of our knowledge, there have been only two case reports about this device used in the hip7,8. We present the case of a twenty-four-year-old patient referred with right hip pain and mechanical symptoms, who we treated with open surgical dislocation, removal of osteochondral loose bodies, femoral osteochondroplasty, and partial femoral hip resurfacing with the HemiCAP device. We obtained institutional review board approval for this retrospective report. The patient was informed that data concerning the case would be submitted for publication, and he provided consent. A twenty-four-year-old man with a history of Legg-Calve-Perthes disease (diagnosed at the age of six years) was referred to our young adult hip service with symptoms of right groin pain and intermittent “catching” and “clunking” of the hip. At the time, he was a student, but was doing construction work during the summer. He described a history of osteochondritis dissecans of both elbow joints, which had been treated surgically ten years earlier to remove loose bodies. He was otherwise fit and healthy. He denied any previous surgery to the right hip. Symptoms were localized to the right groin and had been progressive for six years. He complained of pain up to 8 of 10 as …

Voxel classification and graph cuts for automated segmentation of pathological periprosthetic hip anatomy

Automated patient-specific image-based segmentation of tissues surrounding aseptically loose hip prostheses is desired. For this we present an automated segmentation pipeline that labels periprosthetic tissues in computed tomography (CT). The intended application of this pipeline is in pre-operative planning. Individual voxels were classified based on a set of automatically extracted image features. Minimum-cost graph cuts were computed on the classification results. The graph-cut step enabled us to enforce geometrical containment constraints, such as cortical bone sheathing the femur's interior. The solution's novelty lies in the combination of voxel classification with multilabel graph cuts and in the way label costs were defined to enforce containment constraints. The segmentation pipeline was tested on a set of twelve manually segmented clinical CT volumes. The distribution of healthy tissue and bone cement was automatically determined with sensitivities greater than 82% and pathological fibrous interface tissue with a sensitivity exceeding 73%. Specificity exceeded 96% for all tissues. The addition of a graph-cut step improved segmentation compared to voxel classification alone. The pipeline described in this paper represents a practical approach to segmenting multitissue regions from CT.

Treatment of Interprosthetic Fractures of the Femur

The treatment of interprosthetic femoral fractures is challenging because of several factors. Poor bone stock, advanced age, potential prosthetic instability, and limited fracture fixation options both proximally and distally can complicate standard femur fracture treatment procedures. The purpose of this report was to describe our experience treating interprosthetic femoral fractures, providing an emphasis on treatment principles and specific intraoperative management. All patients with fractures occurring between ipsilateral hip and knee prostheses between 2004 and 2010 were identified from a comprehensive database and included in this study. Patients had been treated using principles adapted from two isolated periprosthetic fracture classification systems, the Vancouver and Su classifications. The electronic medical record (including inpatient medical records, operative notes, outpatient medical records, and all radiographs) was reviewed for each patient and demographic and treatment-related variables as well as complications and outcomes were recorded. Thirteen consecutive patients with interprosthetic fractures were included. Four fractures occurred around a clearly loose prosthesis, which were subsequently treated with long-stemmed revisions. The remaining 12 fractures were treated with a locked-plate construct. Two of nine patients (22.2%) died before fracture union. Follow-up averaged 28 months ± 4 months, with fracture union achieved at an average of 4.7 months ± 0.3 months. All patients returned to their self-reported preoperative ambulatory status except one who developed a loose hip prosthesis at 3-year follow-up after fracture union. The principles for treatment of isolated periprosthetic fractures are useful to guide the fixation of interprosthetic fractures. Locked plating is an effective method for the treatment of interprosthetic femoral fractures. Bypassing the adjacent prosthesis by a minimum of two femoral diameters is a necessary technique to prevent a stress riser.

Teriparatide in the Treatment of a Loose Hip Prosthesis

To the Editor: The complexity of surgical and medical problems associated with reimplantation of a loose hip prosthesis does not always render this procedure acceptable. In addition, certain drugs may enhance the quality of bone around the prosthesis1,2. We treated a patient with teriparatide following loosening of his hip prosthesis, which was implanted for the second time; further surgery was no longer an option. The patient had osteoarthritis and had an uncemented prosthesis when he was 56 years of age; by the age of 61 years he required a reimplant, as a result of aseptic loosening. At the age of 74 years, he began to develop increasing pain and progressive loss of power. He had a history of dilated cardiomyopathy, and in view of this a surgical solution was ruled out. By the age of 77 years, he was treated with clodronate (100 mg intramuscularly weekly) and oral calcium (1.5 g daily) for 1 year. At age 78, radiographic imaging showed extensive loosening of the bone around the cup and a marked reduction in cortical thickness. Although he was already using a cane, he was advised to use 2 canes to allow partial weight-bearing. He was subsequently prescribed teriparatide (20 μg daily for … [↵][1]Address correspondence to Dr. D. Sarti, Via Mario Conti 53, San Lazzaro di Savena, Bologna, 40068, Italy. E-mail: danielesarti1978{at}gmail.com [1]: #xref-corresp-1-1

Senescence in cells in aseptic loosening after total hip replacement

Particle-induced osteolysis is a major cause of aseptic loosening after total joint replacement. The purpose of the current study was to evaluate cellular senescence of macrophages and giant cells in patients with aseptic hip loosening by determination of SA-β-Gal (SA-β-galactosidase), a reliable and frequently used indicator of cellular senescence. The level of senescence in capsule and interface membranes was significantly higher in patients with aseptic loosening in comparison to specimens from patients without aseptic loosening. Using Spearman’s rank correlation, we found that the expression of SA-β-Gal in giant cells (p=0.002) and macrophages (p=0.050) in the interface membranes correlates significantly with the degree of polyethylene debris. We speculate that the induction of DNA damage by wear particles is responsible for premature senescence. Consequently, we conclude that the form of senescence observed in this study is a “stress-induced senescence”.