A PD-1highCD4+ T Cell Population With a Cytotoxic Phenotype is Associated With Interstitial Lung Disease in Systemic Sclerosis

OBJECTIVE

T cells contribute to tissue injury in systemic sclerosis (SSc), yet the specific T cell subsets expanded in patients with SSc remain incompletely defined. Here we evaluated specific phenotypes and functions of peripheral helper T (Tph) and follicular helper T (Tfh) cells, which have been implicated in autoantibody production, and assessed their associations with clinical features in a well-characterized cohort of patients with SSc.

METHODS

Mass cytometry of T cells from peripheral blood mononuclear cells of patients with SSc and controls were evaluated using t-distributed stochastic neighbor embedding visualization, biaxial gating, and marker expression levels. Findings were validated with flow cytometry and in vitro assays.

RESULTS

The frequencies of PD-1highCXCR5+ Tfh cells and PD-1highCXCR5- Tph cells were similar in patients with SSc and controls. t-distributed stochastic neighbor embedding visualization (tSNE) revealed distinct populations within the PD-1highCXCR5- cells distinguished by expression of HLA-DR and inducible costimulator (ICOS). Among PD-1highCXCR5- cells, only the HLA-DR+ICOS- cell population was expanded in patients with SSc. Cytometric and RNA sequencing analyses indicated that these cells expressed cytotoxic rather than B cell helper features. HLA-DR+ICOS- PD-1highCXCR5- cells were less potent in inducing B cell plasmablast differentiation and antibody production than comparator T helper cell populations. HLA-DR+ICOS-PD-1highCXCR5- cells were significantly associated with the presence and severity of interstitial lung disease among patients with SSc.

CONCLUSION

Among PD-1highCXCR5- T cells, a subset of HLA-DR+ICOS- cells with cytotoxic features is specifically expanded in patients with SSc and is significantly associated with interstitial lung disease severity. This potential cytotoxicity appearing in the CD4 T cell population can be evaluated as a prognostic disease biomarker in patients with SSc.

Deconstruction of rheumatoid arthritis synovium defines inflammatory subtypes

Rheumatoid arthritis is a prototypical autoimmune disease that causes joint inflammation and destruction1. There is currently no cure for rheumatoid arthritis, and the effectiveness of treatments varies across patients, suggesting an undefined pathogenic diversity1,2. Here, to deconstruct the cell states and pathways that characterize this pathogenic heterogeneity, we profiled the full spectrum of cells in inflamed synovium from patients with rheumatoid arthritis. We used multi-modal single-cell RNA-sequencing and surface protein data coupled with histology of synovial tissue from 79 donors to build single-cell atlas of rheumatoid arthritis synovial tissue that includes more than 314,000 cells. We stratified tissues into six groups, referred to as cell-type abundance phenotypes (CTAPs), each characterized by selectively enriched cell states. These CTAPs demonstrate the diversity of synovial inflammation in rheumatoid arthritis, ranging from samples enriched for T and B cells to those largely lacking lymphocytes. Disease-relevant cell states, cytokines, risk genes, histology and serology metrics are associated with particular CTAPs. CTAPs are dynamic and can predict treatment response, highlighting the clinical utility of classifying rheumatoid arthritis synovial phenotypes. This comprehensive atlas and molecular, tissue-based stratification of rheumatoid arthritis synovial tissue reveal new insights into rheumatoid arthritis pathology and heterogeneity that could inform novel targeted treatments.

Clonally expanded CD38hi cytotoxic CD8 T cells define the T cell infiltrate in checkpoint inhibitor-associated arthritis

Immune checkpoint inhibitor (ICI) therapies used to treat cancer, such as anti-PD-1 antibodies, can induce autoimmune conditions in some individuals. The T cell mechanisms mediating such iatrogenic autoimmunity and their overlap with spontaneous autoimmune diseases remain unclear. Here, we compared T cells from the joints of 20 patients with an inflammatory arthritis induced by ICI therapy (ICI-arthritis) with two archetypal autoimmune arthritides, rheumatoid arthritis (RA) and psoriatic arthritis (PsA). Single-cell transcriptomic and antigen receptor repertoire analyses highlighted clonal expansion of an activated effector CD8 T cell population in the joints and blood of patients with ICI-arthritis. These cells were identified as CD38hiCD127- CD8 T cells and were uniquely enriched in ICI-arthritis joints compared with RA and PsA and also displayed an elevated interferon signature. In vitro, type I interferon induced CD8 T cells to acquire the ICI-associated CD38hi phenotype and enhanced cytotoxic function. In a cohort of patients with advanced melanoma, ICI therapy markedly expanded circulating CD38hiCD127- T cells, which were frequently bound by the therapeutic anti-PD-1 drug. In patients with ICI-arthritis, drug-bound CD8 T cells in circulation showed marked clonal overlap with drug-bound CD8 T cells from synovial fluid. These results suggest that ICI therapy directly targets CD8 T cells in patients who develop ICI-arthritis and induces an autoimmune pathology that is distinct from prototypical spontaneous autoimmune arthritides.

Humoral and cellular immune responses in persons with rheumatoid arthritis after a third dose of mRNA COVID-19 vaccine

OBJECTIVE

Disease-modifying anti-rheumatic drugs (DMARDs) that treat rheumatoid arthritis (RA) may reduce immune responses to COVID-19 vaccination. We compared humoral and cell-mediated immunity before and after a 3rd dose of mRNA COVID vaccine in RA subjects.

METHODS

RA patients that received 2 doses of mRNA vaccine enrolled in an observational study in 2021 before receiving a 3rd dose. Subjects self-reported holding or continuing DMARDs. Blood samples were collected pre- and 4 weeks after the 3rd dose. 50 healthy controls provided blood samples. Humoral response was measured with in-house ELISA assays for anti-Spike IgG (anti-S) and anti-receptor binding domain IgG (anti-RBD). T cell activation was measured after stimulation with SARS-CoV-2 peptide. Spearman's correlations assessed the relationship between anti-S, anti-RBD, and frequencies of activated T cells.

RESULTS

Among 60 subjects, mean age was 63 years and 88% were female. 57% of subjects held at least 1 DMARD around the 3rd dose. 43% (anti-S) and 62% (anti-RBD) had a normal humoral response at week 4, defined as ELISA within 1 standard deviation of the healthy control mean. No differences in antibody levels were observed based on holding DMARDs. Median frequency of activated CD4 T cells was significantly greater post- vs. pre-3rd dose. Changes in antibody levels did not correlate with change in frequency of activated CD4 T cells.

CONCLUSION

Virus-specific IgG levels significantly increased in RA subjects using DMARDs after completing the primary vaccine series, though fewer than two-thirds achieved a humoral response like healthy controls. Humoral and cellular changes were not correlated.

T peripheral helper cells in autoimmune diseases

Pathologic T cell-B cell interactions underlie many autoimmune diseases. The T cells that help B cells in autoimmune diseases vary in phenotype and include T cells that lack typical features of T follicular helper cells, such as expression of CXCR5 and BCL6. A population of PD-1hi CXCR5- T peripheral helper (Tph) cells has now been recognized in multiple autoantibody-associated diseases. Tph cells display a distinctive set of features, merging the ability to provide B cell help with the capacity to migrate to inflamed peripheral tissues. Here, we review the scope of immune-related conditions in which Tph cells have been implicated and provide a perspective on their potential contributions to pathologic B cell activation in autoimmune diseases. We discuss Tph cells as a promising therapeutic strategy in autoimmunity and consider the utility of tracking Tph cells in blood as a biomarker to quantify aberrant T cell-B cell activation in patients with autoimmune diseases.

Importance of Shared Treatment Goal Discussions in Rheumatoid Arthritis-A Cross-Sectional Survey: Patients Report Providers Seldom Discuss Treatment Goals and Outcomes Improve When Goals Are Discussed

Objective

Treat‐to‐target (T2T) and shared decision‐making are valued features of current guidelines for rheumatoid arthritis (RA) management. Although T2T has demonstrated value for improving RA outcomes, implementation remains inconsistent and lacks standardization and procedures for including patient input. We sought to better understand the impact of shared decisions on T2T and how treatment goal discussions between patients and providers impact RA treatment improvement and satisfaction.

Methods

An anonymous, web‐based questionnaire was presented to United States residents aged 18 years or older with a self‐reported diagnosis of RA by a medical professional with 28 questions regarding socio‐demographics, RA disease activity (DA), diagnosis, treatments, outcomes, and goals. Analyses included descriptive statistics with χ² and rank sum tests for comparisons.

Results

The questionnaire was completed by 907 people (mean age of 58 years; mean 11 years since diagnosis; 90% female). The majority (571; 63%) did not discuss RA treatment goals with providers. Patients engaging in treatment goal discussions with their providers were three times more likely to be satisfied with their treatment plans. Patients discussing treatment goals with their providers were more likely to have improved DA levels and 68% more likely to reach remission.

Conclusion

A majority of patients with RA report having no treatment goal discussion with their providers; however, these discussions are associated with greater DA improvement and treatment satisfaction. Further research should seek understanding of how shared treatment goal discussions relate to successful RA management and explore the development of practical tools to implement them in regular clinic practice as part of a T2T regimen.

Toll-like receptor 2 induces pathogenicity in Th17 cells and reveals a role for IPCEF in regulating Th17 cell migration

Pathogenic Th17 cells drive inflammation in autoimmune disease, yet the molecular programming underlying Th17 cell pathogenicity remains insufficiently understood. Activation of Toll-like receptor 2 (TLR2) increases Th17 cell inflammatory potential, but little is known regarding the mechanistic outcomes of TLR2 signaling in Th17 cells. Here, we demonstrate that TLR2 is comparable to IL-23 in inducing pathogenicity and increasing the migratory capacity of Th17 cells. We perform RNA sequencing of Th17 cells stimulated though the TLR2 pathway and find differential expression of several genes linked with the Th17 genetic program as well as genes not previously associated with pathogenic Th17 cells, including Ipcef1. Enforced expression of Ipcef1 in Th17 cells abolishes the TLR2-dependent increases in migratory capacity and severely impairs the ability of Th17 cells to induce experimental autoimmune encephalomyelitis. This study establishes the importance of the TLR2 signaling pathway in inducing Th17 cell pathogenicity and driving autoimmune inflammation.

Toll-like Receptor 2 in Autoimmune Inflammation

TLR signaling is critical for broad scale immune recognition of pathogens and/or danger molecules. TLRs are particularly important for the activation and the maturation of cells comprising the innate immune response. In recent years it has become apparent that several different TLRs regulate the function of lymphocytes as well, albeit to a lesser degree compared to innate immunity. TLR2 heterodimerizes with either TLR1 or TLR6 to broadly recognize bacterial lipopeptides as well as several danger-associated molecular patterns. In general, TLR2 signaling promotes immune cell activation leading to tissue inflammation, which is advantageous for combating an infection. Conversely, inappropriate or dysfunctional TLR2 signaling leading to an overactive inflammatory response could be detrimental during sterile inflammation and autoimmune disease. This review will highlight and discuss recent research advances linking TLR2 engagement to autoimmune inflammation.

Toll-like Receptor 2 induces pathogenicity in Th17 cells

CD4+ T cells, especially Th17 cells, are instrumental in the development and progression of autoimmune diseases, such as multiple sclerosis (MS), psoriasis, and rheumatoid arthritis. While pathogenic Th17 cells drive inflammation in autoimmunity, the molecular programming underlying their pathogenicity remains insufficiently understood. Furthermore, very little is known regarding the role of the pattern recognition receptor TLR2 in Th17 pathogenicity. We have previously shown that activation of TLR2 with PAM3CSK4 during Th17 differentiation results in increased production of IL-17A and IL-17F and significantly increases the proliferation of Th17 cells in vitro. Herein, we show that TLR2 induces pathogenicity in Th17 cells, similar to what has been shown for IL-23. TLR2 signaling results in increased encephalitogenic migration of Th17 cells, in addition to increased cytokine production. To further investigate the effect of TLR2 activation on Th17 cells, we utilized RNA sequencing and found 390 genes that are upregulated and 355 genes that are downregulated following TLR2 signaling in Th17 cells. Several of these genes we have identified are important regulators that either increase or restrain the inflammatory potential of Th17 cells. We further address the role of TLR2 in Th17-mediated autoimmune disease using experimental autoimmune encephalomyelitis (EAE), a mouse model of MS. We show that encephalitogenic Th17 cells expanded with a TLR2 agonist induced EAE disease to the same extent as those expanded with IL-23. Altogether, this study establishes TLR2 signaling as crucial for induction of pathogenic Th17 cells in autoimmune disease.

Thpok suppresses pathogenic cytokine production by Th17 cells in autoimmune disease

CD4+ T cells, including Th17 cells, are instrumental in the development and progression of autoimmune diseases such as multiple sclerosis. While pathogenic Th17 cells drive inflammation in autoimmunity, the molecular programming underlying their pathogenicity remains insufficiently understood. Through RNA-sequencing, we have identified the transcription factor Thpok (Zbtb7b), also known as the CD4 lineage determination factor, as an apparent negative regulator of Th17 pathogenicity. Thpok expression is maintained in peripheral CD4+ T cells and assists in formation of memory CD4+ T cells. Furthermore, Thpok expression in CD4+ T cells represses cytotoxic genes and contributes to the Th17 response during intestinal inflammation. Herein we show Thpok is upregulated in pathogenic Th17 cells both in vitro and in vivo. In addition, we show increased expression of Thpok results in reduced production of IL-17, while conversely, loss of Thpok results in higher inflammatory potential of Th17 cells. Moreover, we have demonstrated that Thpok expression in Th17 cells in vivo functions to inhibit the development of experimental autoimmune encephalomyelitis, a mouse model of multiple sclerosis. Altogether this study establishes Thpok as a suppressor of the autoimmune inflammatory function of Th17 cells.

Adjuvant brachytherapy in the treatment of soft-tissue sarcomas

For many patients with STS, administering adjuvant radiation treatments in the form of interstitial brachytherapy provides an excellent alternative to a protracted course of EBRT. Ideal patients are those with intermediate- or high-grade tumors amenable to en bloc resection. Attractive features of this approach include an untainted pathologic specimen, expeditious completion of treatment, reduction in wound complications, and improved functional outcome. Brachytherapy can permit definitive reirradiation by tightly localizing the high dose radiation exposure. It is also useful in patients who are known to have or be at high risk of metastatic disease, for whom the rapid completion of local treatment allows systemic therapy to begin quickly. Introduction of HDR techniques has shifted the delivery of brachytherapy from inpatient solitary confinement to an outpatient setting. Early reports using HDR brachytherapy for treatment of adult and pediatric STS are quite encouraging. The clinical equivalence between hyperfractionated HDR schedules and traditional LDR techniques is gaining acceptance.

Papillary clear cell adenocarcinoma of the groin arising from endometriosis

A 67-year-old woman presented with rapidly enlarging right anterior thigh mass. Clinical impression was of a primary sarcoma, but the histologic analysis of an incisional biopsy specimen showed adenocarcinoma with clear cell differentiation. Initially thought to be a metastasis, the malignant tumor appears to have arisen from extraabdominal endometriosis of the right groin. This case shows clinical, radiographic, and histologic findings that may help the orthopaedic surgeon recognize an unusual complication of extrapelvic endometriosis.

Dedifferentiated chondrosarcoma with rhabdomyosarcomatous differentiation

Dedifferentiated chondrosarcomas are primary bone tumors characterized by the presence of both low-grade cartilaginous and high-grade sarcomatous components. The high-grade component usually shows histologic features of either malignant fibrous histiocytoma or fibrosarcoma. We are aware of only 10 published cases in which the high-grade component showed rhabdomyosarcomatous differentiation. To further clarify the clinical, radiographic, and pathologic features of this unusual variant, we report three additional cases of dedifferentiated chondrosarcoma with rhabdomyosarcomatous differentiation. The patients included two men and one woman; their mean age was 63 years. Tumors originated in the pelvis (ilium), scapula, and tibia. Two patients presented with radiographic findings typical of dedifferentiated chondrosarcoma, including a geographic, lytic lesion with areas of mineralization suggestive of cartilage in close association with a permeative component. The third patient presented with a primarily lytic, destructive lesion of the right iliac wing. Histologically, the tumors contained lobules of well-differentiated chondrosarcoma associated with a high-grade sarcoma with prominent rhabdomyoblasts. Immunohistochemical stains for actin and desmin were positive in all three tumors, and electron microscopy revealed evidence of skeletal muscle differentiation. All three patients died with metastatic disease, 1, 6, and 12 months postoperatively. This histologic variant of dedifferentiated chondrosarcoma is rare, but it shows radiographic and clinical features similar to "conventional" dedifferentiated chondrosarcoma, including a very poor prognosis.

Juxta-articular osteoid osteoma

Osteoid osteomas that arise at the end of a long bone, within the insertion of the joint capsule (juxta-articular, intra-articular), may cause misleading clinical, radiographic, and histologic findings, resulting in unnecessary diagnostic tests and a delay in definitive treatment. To clarify optimum diagnostic procedures, we reviewed 20 cases of juxta-articular osteoid osteomas and found a mean delay from presentation to correct diagnosis of 24 months. Plain radiographs were either negative or showed only secondary changes. A periosteal reaction and proliferative synovitis with chronic inflammation was common, which could be misinterpreted as rheumatoid arthritis. Optimum diagnostic procedures were a bone scan followed by plain tomograms and an excisional biopsy of the nidus.

Ki-67 and grading of malignant fibrous histiocytomas

Although generally considered to be of high grade, malignant fibrous histiocytomas (MFH) show a range of histologic appearances and a diverse biologic behavior. More precise grading of this type of sarcoma is desirable. The rate of cell proliferation may reflect clinical behavior. A more sensitive measure of cell proliferation is the expression of the Ki-67 antigen. Frozen sections were prepared from 29 cases of MFH. Sections were immunohistochemically stained for Ki-67, and the results were quantitated by image analysis (CAS 100). The Spearman rank correlation test was used to compare the extent of the Ki-67 staining with the conventional histologic grade, nuclear grade, number of mitoses, extent of necrosis, and overall cellularity. There was a significant correlation between the extent of Ki-67 staining and the nuclear grade (cc = 0.56; P = 0.002) and overall histologic grade (correlation coefficient = 0.58; P = 0.001), but there was no significant, independent correlation between Ki-67 and prognosis.

Vancomycin vs tobramycin elution from polymethylmethacrylate: an in vitro study

We fabricated batches of cement containing 0.5 gm, 1.0 gm, and 2.0 gm vancomycin and one with 1.0 gm tobramycin and shaped them into cylinders. They were immersed into 0.5 L of normal saline and the fluid volume was changed daily. Samples of fluid were obtained on days 1, 2, 3, 5, 7, 14, and 28. All fluid samples had antibiotic assays performed to quantitate the amount of elution for vancomycin or tobramycin. Vancomycin elution from PMMA occurred under our study conditions in similar quantities to that measured for tobramycin controls. Vancomycin-loaded PMMA cement may have a clinical role in the treatment of musculoskeletal sepsis caused by gram-positive bacteria, particularly if organisms resistant to the usual antibiotic agents are identified.

Expandable breast implant reconstruction of Tikhoff-Linberg shoulder deformity

Expanding breast implants were used in two patients to reconstruct shoulder contour following a Tikhoff-Linberg resection for cancer. In the first patient, one implant alone was used, and in the second patient, two implants in separate but adjacent pockets. The resulting double contour is more pleasing than that after a single implant, and there also appears to be more flexibility with shoulder motion. This method is suggested as an excellent means of reconstructing the contour of the shoulder area following resection for cancer.

Fibrous tumors of bone

Benign and malignant fibrous tumors of bone are some of the most common tumors encountered by the orthopedic surgeon. Fibrous dysplasia, fibrous cortical defect, non-ossifying fibroma, benign fibrous histiocytoma and osteofibrous dysplasia are benign tumors best treated conservatively or by intralesional/marginal excision. Desmoplastic fibromas are locally aggressive and require a wide margin for surgical cure. Malignant fibrous histiocytoma and fibrosarcoma of bone are malignant bone tumors and must be treated with wide/radical margins and for malignant fibrous histiocytoma adjunctive chemotherapy.

Intraneural lipoma of the sciatic nerve

A large, well-encapsulated intraneural lipoma occurred within the sciatic nerve of a 34-year-old woman. In a review of the literature, significant differences were noted between the well-encapsulated and the diffusely infiltrative lipofibromatous hamartoma types of intraneural lipomas. The average age at the time of appearance of the well-encapsulated type is 45 years, with female predominance, while the infiltrative type arises in a younger age group (average age, eight years) with no sexual predominance. To avoid a recurrence, total excision is recommended in cases of the well-encapsulated type. Attempts to excise the diffusely infiltrative type are likely to fail.

Fast axonal transport in amyotrophic lateral sclerosis: an intra-axonal organelle traffic analysis

Fast transport of intra-axonal organelles was studied in motor nerve from amyotrophic lateral sclerosis (ALS) patients. Organelle traffic in ALS nerves demonstrated a significant increase in anterograde mean speed, while retrograde mean speed was decreased compared with that of controls. Retrograde traffic density (organelles per unit time) was also significantly decreased in the ALS specimens. Anterograde transport machinery is therefore intact and may be responding to the increased physiologic demand of larger motor units. Diminished retrograde speed and organelle traffic density are consistent with a defect in retrograde transport and could impair communication between axon terminals and perikarya.

Periosteal Ewing's sarcoma

Ewing's sarcoma is a small cell malignant tumor that usually arises in the medullary cavity of bone. Less frequently, it originates in soft tissue and may secondarily invade underlying bone. The origin of Ewing's sarcoma in a periosteal location without extension into either the bone or adjacent soft tissue has not been clearly documented. Other malignant tumors of bone (e.g., osteosarcoma) appear to have a somewhat better prognosis when confined between periosteum and bone. The case of a patient with a periosteal Ewing's sarcoma who received a radical excision and postoperative chemotherapy and who is without evidence of disease with over 2 years follow-up is reported.

Digital subtraction angiography for preoperative evaluation of extremity tumors

A retrospective study was undertaken to evaluate the role of digital subtraction angiography (DSA) in the surgical planning of musculoskeletal neoplasms. Thirteen patients with primary bone and soft-tissue tumors were examined by CT and DSA. Three patients also had conventional angiography. DSA yielded surgically useful information in 10 patients, comparable to that expected from conventional angiography. DSA was most helpful in demonstrating the presence or absence of major vessel involvement by tumor when this could not be ascertained definitely on CT. Demonstration of mass extent by CT was accurate in 11 patients. Results of this study suggest that the combination of CT and DSA is useful in the preoperative evaluation of selected extremity tumors and should diminish the need for conventional angiography.

A ten-year follow-up of one hundred consecutive Müller curved-stem total hip-replacement arthroplasties

One hundred consecutive Müller curved-stem total hip replacements were reviewed ten years after operation. Twenty patients with twenty-two arthroplasties had died within the ten-year period without having a revision, and twenty-five arthroplasties had been revised for various reasons. Of the remaining fifty-three arthroplasties, thirty-five were classified as good or excellent, with Harris hip scores of 80 points or higher, and eighteen were classified as poor or fair, with scores lower than 80 points. Follow-up radiographs, made for all but six of the fifty-three hips at ten years, showed a 23 per cent incidence of migration of the acetabular component and a 28 per cent incidence of migration of the femoral component. In addition, there was a 15 per cent incidence of bone resorption in the proximal end of the femur without migration of the femoral component and a 4 per cent incidence of osteolytic defects about the femoral component, also without migration. Combining the radiographically loose replacement (migration) with the clinically loose ones (revised), the over-all incidence of aseptic loosening was 29 per cent for the acetabular component and 40 per cent for the femoral component. There was a positive correlation between the incidence of loosening of the femoral component and younger age, heavier weight, male sex, unilateral hip disease, a wide femoral canal, and varus position of the femoral component, whereas the incidence of loosening of the acetabular component was increased only in association with older age. The rate of loosening of the femoral component appeared to be higher during the early follow-up period and to decrease with time, while the rate of loosening of the acetabular component appeared to be lower during the early follow-up period but to increase with time.

Revision of Mueller total hip arthroplasties

Experience with 65 revisions of Mueller total hip arthroplasties and a minimum of two years follow-up on 32 revised total hips showed that the results appear to be poor in a significant number (22%) of patients: 18% required additional surgery. Revision of total hip arthroplasties with recementing of one or both components carries a significant risk of intraoperative and postoperative complications. Since the introduction of femoral components with improved metallurgic properties, no stem failures have occurred. Varus position of the femoral stem predisposes for stem loosening. Aspiration arthrography is of limited value in the evaluation of a painful total hip. In cases of femoral component loosening with gross cystic changes on the roentgenograms, early revision is recommended as fracture of the femoral shaft may ensue. Late loosening of the acetabular cup as yet appears to be an uncommon cause of total hip arthroplasty failure. Attention to the details of surgical technique and more research on material selection in primary total hip replacement are important.

Cutaneous complications of orthopedic implants. A two-year prospective study

In a two-year prospective study of cutaneous problems in orthopedic implant recipients, cutaneous eruptions of unknown cause that bore good temporal relationships with implant surgery occurred in 19 patients. Two clinical patterns were observed. A transient "exanthematic" dermatitis was seen in six patients; in two of them, it recurred after each surgical implant procedure. A persistent reaction was seen in 13 patients. Metal sensitivity was found in two patients and considered to be relevant. Allergic cutaneous complications of orthopedic implants are rare. However, in an implant recipient in whom a cutaneous problem develops, the likelihood of the cutaneous problem being allergic in nature is slightly greater if the implant is of the static type, if there is a history of metal sensitivity, if the cutaneous eruption shows a predilection for the anatomic zone of the implant, and if the eruption is eczematous and has developed late and persisted.

Osteosarcoma of the hand

Two cases of osteogenic sarcoma in the hand are reported, with a discussion of the literature.

Patella alta and chondromalacia

The Insall-Salvati method of determining the position of the patella by radiography was employed in fifty-one patients with chondromalacia patellae that had been proved at arthrotomy. There was no definite relationship between chondromalacia patellae and patella alta. There was, however, a highly significant statistical difference between the ratio of the length of the patella to that of the patellar tendon in normal men and women.

Mechanical strength of acrylic bone cements impregnated with antibiotics

Admixing of several antibiotic powders which were insoluble in methyl methacrylate did not decrease the compressive and diametral tensile strengths of two acrylic bone cements when tested after setting for 1 day and after leaching 40 days in water at 37 degrees C. When antibiotics were added as water solutions, the included water resulted in a significant decrease in these bulk mechanical properties. Storage in water for 40 days caused surface irregularities only on specimens of the set antibiotic admixtures. Approximately 0.5% of the admixed dosage of these water-soluble antibiotics could be leached from the set cements. The observed surface channels, presumably left by the loss of antibiotic, suggest further study of surface-sensitive mechanical properties may be needed. The bulk mechanical strengths presented here are conclusive only for the particular combinations of antibiotics and cements investigated, and should not be generalized at this time to any or all antibiotic admixtures or other mechanical properties.

Antibiotic-impregnated acrylic bone cement

In vitro and in vivo experiments were performed to study the antibacterial and mechanical properties of Simplex and Palacos acrylic bone cements utilized for the production of acrylic cement-antibiotic composites. Acrylic cement without antibiotic had no bacteriostatic effect on Staphylococcus aureus, Escherichia coli, and Pseudomonas. Oxacillin, cefazolin, and gentamicin are stable in acrylic cement and are released in a microbiologically active form. The three antibiotics diffused from the Palacos in larger amounts daily and for a significantly longer time than from the Simplex. Mechanical tests demonstrated that admixture of antibiotics and acrylic cement had no influence on the compressive and diametral tension strengths of the cement. Bacteriostatic concentrations of oxacillin in wound hematomas were measured for fourteen days after implantation of an oxacillin-Simplex composite in dogs. High bactericidal concentrations of the antibiotic were measured in the surrounding bone for twenty-one days after implantation.