Patients risk for mortality at 90 days after proximal femur fracture - a retrospective study in a tertiary care hospital

BACKGROUND

Despite improving the management of proximal femur fractures (PFF) with legal requirements of timing the surgery within 24 h, mortality rates in these patients remain still high. The objective of our study was to analyze potential cofactors which might influence the mortality rate within 90 days after surgery in PFF to avoid adverse events, loss of quality of life and high rates of mortality.

METHODS

In this retrospective, single-center study all patients with PFF aged 65 years and older were included. We recorded gender, age, type of fracture, surgery and anesthesia, time, comorbidities and medication as well as complications and mortality rate at 90 days. Separate logistic regression models were used to assess which parameters were associated with patients' mortality. The mortality rate was neither associated with timing, time and type of surgery nor time and type of anesthesia, but with higher age (OR 1.08 per year; 95% CI 1.034-1.128), lower BMI (OR 0.915 per kg/m2; 95% CI 0.857-0.978), higher CCI (OR 1.170 per point; 95% CI 1.018-1.345), dementia (OR 2.805; 95% CI 1.616-4.869), non-surgical complications (OR 2.276; 95% CI 1.269-4.083) and if mobilization was impossible (OR 10.493; 95% CI 3.612-30.479).

RESULTS

We analyzed a total of 734 patients (age ≥ 65 years) who had a PFF in 2019 and 2020 and received surgery. 129 patients (17.6%) died until 90 days at an median age of 89.7 years (range 65-101 years).

CONCLUSION

The proportion of patients who died until 90 days after surgery is still high. It is less extend influenced by surgical and anaesthesiologic factors than by patient-related factors like age or lower BMI. Physicians should be aware of the importance of avoiding adverse events and the importance of patients' mobilization to reduce mortality and improve patients' outcome.

Girdlestone resection arthroplasty for femoral neck fractures has poorer outcomes than hemiarthroplasty in frail patients with increased risk for arthroplasty-related complications: a retrospective case study of 21 patients

BACKGROUND AND PURPOSE

Hemiarthroplasty (HA) is the usual treatment for displaced femoral neck fractures (FNF) in elderly patients. Patients may be unsuitable for HA due to secondary conditions such as systemic infections or severe neurological conditions, which is why Girdlestone resection arthroplasty (GRA) may be an option. We aimed to determine (1) patient survival in matched patient groups treated with either GRA or HA and (2) functional outcomes.

PATIENTS AND METHODS

21 patients treated with GRA for FNF in a German university hospital were retrospectively reviewed (2015-2019). After matching for age and comorbidities, a control group of 42 HA patients was established. Patient survival was determined by a Kaplan-Meier analysis. The mean follow-up (FU) was 1.5 (0-4.4) years. Function at FU was documented using the modified Harris Hip Score (mHHS) and the National Hip Fracture Database (NHFD) mobility score.

RESULTS

The 1-month-mortality was 19% in the GRA group and 12% in the HA group; the 1-year mortality was 71% and 49%, respectively (P = 0.01). The mHHS at FU was lower in the GRA group than in the HA group (22 [range 0-50] vs. 46 [11-80]). 82% of patients in the GRA group were bedridden post-surgery as opposed to 19% in the HA group.

CONCLUSION

Patients with HA after FNF had higher survival and better functional outcomes when compared with GRA in matched patient groups. Considering this, GRA for FNF should be selected restrictively.

Treatment of Severe Acetabular Defects With an Antiprotrusio Cage and Trabecular Metal Augments - Clinical and Radiographic Results After a Mean Follow-Up of 6.6 Years

BACKGROUND

Large acetabular bone defects present a serious challenge in revision total hip arthroplasty. The off-label use of antiprotrusio cages in combination with tantalum augments is a promising treatment option in these difficult situations.

METHODS

Between 2008 and 2013, 100 consecutive patients underwent acetabular cup revision with a cage-augment combination in Paprosky 2 and 3 defect types (including pelvic discontinuities). There were 59 patients available for follow-up. The primary endpoint was the explantation of the cage-and-augment construct. The secondary endpoint was acetabular cup revision for any reason. Also, radiographic and functional outcomes (Western Ontario and McMaster Universities Osteoarthritis Index, Harris Hip Score) were evaluated. Implant survival rates were determined using a Kaplan-Meier analysis. The significance level was set at P < .05.

RESULTS

Explantation-free survivorship of the "Cage-and-Augment" system was 91.9% after a mean follow-up of 6.2 years (range, 0 to 12.8). All 6 explantations were due to periprosthetic joint infection (PJI). The overall revision-free implant survival rate was 85.7%, including 6 additional liner revisions due to instability. In addition, 6 early PJI occurred, which were successfully treated with debridement, irrigation, and implant retention. We did observe one patient who had radiographic loosening of the construct without necessity for treatment.

CONCLUSION

The combination of an antiprotrusio cage with tantalum augments is a promising technique in treating large acetabular defects. A major risk of PJI and instability due to large bone and soft tissue defects needs special attention.

When are patients with osteoarthritis referred for surgery?

Current treatment strategies in hip and knee osteoarthritis (OA) involve a combined approach that includes not only modification of risk factors and conservative treatment but also joint-preserving surgical therapy in the early stages, or joint replacement in late OA. With the recent development of new etiological concepts (i.e. hip dysplasia and femoroacetabular impingement as major risk factors for hip OA), treatment alternatives for joint preservation could be extended significantly. Satisfactory results of osteotomies and other reconstructive procedures around hip and knee joints can only be expected in early OA (Kellgren/Lawrence grade 0-II). If patients with advanced radiographic OA grades III-IV do not respond to conservative treatment over at least 3 months and express a relevant burden of disease, joint replacement might be considered. Prior to surgery, potential contraindications must be excluded, patient expectations need to be discussed, and modifiable risk factors, which may negatively influence the outcome, should be optimized.

[Hip dysplasia: What influence do age, arthrosis and concomitant diseases have on the treatment result?]

Pelvic osteotomies are an established treatment for symptomatic adult hip dysplasia with a promising long-term outcome. Results depend not only on the achieved acetabular reorientation but also on patient-factors like preoperative joint condition (degree of osteoarthritis and joint congruency) and age. Additionally, the diagnosis and appropriate therapy of impingement-associated hip deformities is essential in order to achieve good mid- and long-term outcomes. The influence of chondrolabral pathology on the outcome of pelvic osteotomies is not yet defined. Symptomatic patients with residual dysplasia after previous pelvic or acetabular osteotomies can benefit from an additional osteotomy, although results can be worse in comparison to prior unoperated joints. Obesity can make surgery more demanding and increases the complication profile of PAO, although it has no influence on the postoperative outcome. Regarding the overall prognosis after an osteotomy, the consideration of combined risk factors is superior to the concentration on individual factors alone.

Dual-Mobility Cups in Primary Total Hip Arthroplasty

Dual-mobility cups (DMCs) were introduced in France more than 40 years ago and are increasingly used not only in hip revision but also primary hip arthroplasty. Due to a simulated large-head articulation and increased jumping distance, DMCs can contribute to a high range of motion in the hip joint and reduce the risk of instability. Numerous studies have reported low dislocation rates and high survival rates in the mid-term follow-up. Nevertheless, long-term data, especially on primary hip replacement, remain limited, and the effect of recent designs and material innovations is still unclear. Therefore, primary DMCs are mainly proposed in patients at high risk for dislocation (i.e. pelvitrochanteric insufficiency, compromised spinopelvic mobility, neuromuscular disorders, obesity and femoral neck fractures). Based on a review of recently published studies referring to these indications, the current study discusses the advantages and disadvantages of DMCs.

[Strategies for cup revision]

Hip arthroplasty revision management can range from simple procedures using standard implants to complex surgical interventions requiring the combined use of revision cups, metal augments, bone grafts, and antiprotrusio cages. The adequate restoration of biomechanics and function of the hip joint with reconstruction of the original center of rotation can be challenging. We present an overview of various available techniques with the associated implant and anchoring strategies and the respective clinical results depending on the acetabular defect situation.

Patients with Small Acetabular Cartilage Defects Caused by Femoroacetabular Impingement Do Not Benefit from Microfracture

OBJECTIVE

According to current recommendations, large cartilage defects of the hip over 2 cm2 are suggested to undergo autologous chondrocyte transplantation (ACT), while small defects should be treated with microfracture. We investigated if patients with small chondral defects of the hip joint (≤100 mm2) actually benefit from microfracture.

DESIGN

In this retrospective multicenter cohort study 40 patients with focal acetabular cartilage defects smaller than 100 mm2 and of ICRS grade ≥2 caused by femoroacetabular impingement were included. Twenty-six unrandomized patients underwent microfracture besides treatment of the underlying pathology; in 14 patients cartilage lesions were left untreated during arthroscopy. Over a mean follow-up of 28.8 months patient-reported outcome was determined using the iHOT33 (international hip outcome tool) and the VAS (visual analog scale) for pain.

RESULTS

The untreated group showed a statistically significant improvement of the iHOT33 after 12 (p = 0.005), 24 (p = 0.019), and 36 months (p = 0.002) compared to the preoperative score, whereas iHOT33 in the microfracture group did not reveal statistically significant changes over time. There was no significant difference between both groups on any time point. Regarding pain both groups did not show a significant improvement over time in the VAS.

CONCLUSION

The subjective outcome of patients with small cartilage defects of the hip (≤100 mm2) improves 12 months after arthroscopic FAIS surgery without any cartilage treatment. However, no improvement could be seen after microfracture. Therefore, a reserved surgical treatment for small cartilage defects of the hip under preservation of the subchondral bone is recommended especially if a simultaneous impingement correction is performed.

Ultrasonic bone cement removal efficiency in total joint arthroplasty revision: A computer tomographic-based cadaver study

Polymethylmethacrylate (PMMA) removal during septic total joint arthroplasty revision is associated with a high fracture and perforation risk. Ultrasonic cement removal is considered a bone-preserving technique. Currently, there is still a lack of sound data on efficacy as it is difficult to detect smaller residues with reasonable technical effort. However, incomplete removal is associated with the risk of biofilm coverage of the residue. Therefore, the study aimed to investigate the efficiency of ultrasonic-based PMMA removal in a human cadaver model. The femoral components of a total hip and a total knee prosthesis were implanted in two cadaver femoral canals by 3rd generation cement fixation technique. Implants were then removed. Cement mantle extraction was performed with the OSCAR-3-System ultrasonic system (Orthofix®). Quantitative analysis of cement residues was carried out with dual-energy and microcomputer tomography. With a 20 µm resolution, in vitro microcomputer tomography visualized tiniest PMMA residues. For clinical use, dual-energy computer tomography tissue decomposition with 0.75 mm resolution is suitable. With ultrasound, more than 99% of PMMA was removed. Seven hundred thirty-four residues with a mean volume of 0.40 ± 4.95 mm³ were identified with only 4 exceeding 1 cm in length in at least one axis. Ultrasonic cement removal of PMMA was almost complete and can therefore be considered a highly effective technique. For the first time, PMMA residues in the sub-millimetre range were detected by computer tomography. Clinical implications of the small remaining PMMA fraction on the eradication rate of periprosthetic joint infection warrants further investigations.

The incidence of adverse local tissue reaction due to head taper corrosion after total hip arthroplasty using V40 taper and 36 mm CoCr head

AIMS

Head-taper corrosion is a cause of failure in total hip arthroplasty (THA). Recent reports have described an increasing number of V40 taper failures with adverse local tissue reaction (ALTR). However, the real incidence of V40 taper damage and its cause remain unknown. The aim of this study was to evaluate the long-term incidence of ALTR in a consecutive series of THAs using a V40 taper and identify potentially related factors.

METHODS

Between January 2006 and June 2007, a total of 121 patients underwent THA using either an uncemented (Accolade I, made of Ti₁₂Mo₆Zr₂Fe; Stryker, USA) or a cemented (ABG II, made of cobalt-chrome-molybdenum (CoCrMo); Stryker) femoral component, both with a V40 taper (Stryker). Uncemented acetabular components (Trident; Stryker) with crosslinked polyethylene liners and CoCr femoral heads of 36 mm diameter were used in all patients. At a mean folllow-up of 10.8 years (SD 1.1), 94 patients (79%) were eligible for follow-up (six patients had already undergone a revision, 15 had died, and six were lost to follow-up). A total of 85 THAs in 80 patients (mean age 61 years (24 to 75); 47 (56%) were female) underwent clinical and radiological evaluation, including the measurement of whole blood levels of cobalt and chrome. Metal artifact reduction sequence MRI scans of the hip were performed in 71 patients.

RESULTS

A total of 20 ALTRs were identified on MRI, with an incidence of 26%. Patients with ALTR had significantly higher median Co levels compared with those without ALTR (2.96 μg/l (interquartile range (IQR) 1.35 to 4.98) vs 1.44 μg/l (IQR 0.79 to 2.5); p = 0.019). Radiological evidence of osteolysis was also significantly associated with ALTR (p = 0.014). Median Cr levels were not significantly higher in those with ALTR compared with those without one (0.97 μg/l (IQR 0.72 to 1.9) v 0.67 μg/l (IQR 0.5 to 1.19; p = 0.080). BMI, sex, age, type of femoral component, head length, the inclination of the acetabular component, and heterotopic ossification formation showed no significant relationship with ALTR.

CONCLUSION

Due to the high incidence of local ALTR in our cohort after more than ten years postoperatively, we recommend regular follow-up investigation even in asymptomatic patients with V40 taper and metal heads. As cobalt levels correlate with ALTR occurrence, routine metal ion screening and consecutive MRI investigation upon elevation could be discussed. Cite this article: Bone Joint J 2022;104-B(7):852-858.

Cementation of a dual mobility cup in a well-fixed acetabular component- a reliable option in revision total hip arthroplasty?

BACKGROUND

The "cup-in-cup" technique allows for revision of failed total hip arthroplasty (THA) when the cementless cup is well fixed. Furthermore, it can be used for liner wear or mechanical failure where liner replacement may be impossible or impractical. Recently, the "cup-in-cup" technique in combination with dual mobility cups (DMC) has drawn increased attention. Our aim was to report on the clinical and radiographic outcomes following this surgery.

METHODS

From 2015 to 2020, 33 patients treated with the DMC- "cup in cup" technique were retrospectively reviewed. Fourteen patients had died while 19 were available for the final follow-up (FU), of which 15 underwent both a radiograph and a FU visit, 2 underwent a radiograph only and 2 underwent a telephone interview only. Patient-related outcome measures included the HHS and the WOMAC. Radiographs were assessed for implant loosening and positioning. Primary endpoint was revision of any cause and secondary endpoint was loosening of the DMC at the latest FU. The survival analysis was conducted using the Kaplan-Meier method.

RESULTS

The mean age at surgery was 78.6 ± 7.1 (63-93) years and the mean surgery duration was 124.4 ± 52.0 (60-245) minutes. Recurrent dislocation (42.4%), periprosthetic fracture (39.4%) and polyethylene wear (6.1%) were the most frequent reasons for surgery. The mean FU duration (n = 19) was 28.5 ± 17.3 (3-64) months. The mean HHS score at FU was 59.4 ± 22.2 (29-91) and the mean WOMAC score was 59.7 ± 25.6 (15.6-93.8). Two cups were revised due to instability and one revision was performed due to periprosthetic joint infection, accounting for an overall cup survival rate of 86.8% after a mean FU of 22.9 ± 18.0 (1.5-64.6) months. The survival rate free of loosening was 90.9% after a mean FU of 22.3 ± 18.5 (1.5-64.7) months.

CONCLUSIONS

We found that the cementation of a DMC in a well-fixed cup is a promising short- to mid-term treatment addressing THA instability especially in elderly and frail patients, who benefit from a reduced operation time. Proper cementation technique, adequate cup positioning as well as selection of a sufficiently large DMC are crucial for treatment success. Longer FUs will be needed in the future in order to further prove the benefit of this technique.

How does former Salter innominate osteotomy in patients with Legg–Calvé–Perthes disease influence acetabular orientation? An MRI-based study

Salter innominate osteotomy (SIO) has been successfully used in the treatment of Legg–Calvé–Perthes disease (LCPD). Recent studies that have raised concerns about acetabular retroversion after SIO have been based on plain radiographs. In order to assess the true acetabular orientation, the present study uses a specific magnetic resonance imaging (MRI) technique. In addition, the association between acetabular morphology and clinical function as well as health-related quality of life was assessed. Twenty-three patients with 24 operated hips who underwent SIO for LCPD between January 2004 and November 2014 were included. Mean age was 8.5 ± 2.2 years at surgery and 18.5 ± 2.9 years at follow-up. MRIs were conducted at 1.5 T using radial sequences. The analysis included the acetabular version, acetabular sector angles (ASAs) and alpha angles. Plain radiographs were used in order to obtain the Stulberg classification. Patient-related outcome measures included the international Hip Outcome Tool and Euroqol-5 dimensions scores. In comparison to the non-operated side, the MRI of previously operated hips showed no difference of version at the center of the femoral head but significantly decreased version just below the roof level. As a marker for posterior acetabular coverage, the ASAs between 9 and 11 o’clock were significantly decreased when compared with non-operated hips. In hips with a mild acetabular retroversion (<15°), the function was significantly decreased when compared with non-retroverted hips. The SIO is an effective tool in order to restore acetabular containment in LCPD. When compared with the non-operated hips, our collective displays only moderate changes of acetabular orientation and coverage.

MRI-based assessment of acetabular version and coverage after previous Pemberton osteotomy in skeletally mature patients

PURPOSE

In hip dysplasia the Pemberton osteotomy can modify the shape of the acetabulum and is indicated for children aged between two and 12 when the triradiate cartilage is still open. However, there have been concerns about acetabular retroversion following this type of osteotomy. The studies, however, have been based on plain radiographs. The aim of our investigation was to assess the 3D acetabular orientation in patients with previous Pemberton osteotomy after skeletal maturation.

METHODS

Ten patients with 12 operated hips were included who received Pemberton osteotomy for hip dysplasia between January 3, 2005 and March 25, 2011. Mean age at surgery and at follow-up were 7.2 years (sd 3.7) and 19.2 years (sd 3.7), respectively. MRIs were conducted with 1.5 T. Besides the measurement of acetabular version, the analysis included alpha angles, acetabular sector angles (ASAs) as well as modified ASAs (cartilage covered area angles). Furthermore, the presence of osteoarthritis (OA) as well as acetabular retroversion was determined on plain radiographs. Patient-related outcome measures included the international Hip Outcome Tool (iHOT) and EuroQol-5-Dimensions (EQ5D) scores.

RESULTS

In comparison with the contralateral native and healthy hips the operated hips showed similar version (19.5° (sd 4.6°) versus 18.6° (sd 7.0°); p = 0.974). Also, there were no differences in terms of femoral head sphericity (alpha angles) and acetabular coverage (ASA angles). Five of 12 Pemberton hips showed signs of beginning OA (Kellgren-Lawrence classification I or II) while none of the non-operated hips did. Patients who received surgery before the age of six years had similar functional and radiological results when compared with patients who were older than six years at surgery. Among all patients, iHOT was 91.9 (sd 10.0) and EQ5D was 90.3 (sd 7.3)).

CONCLUSION

The Pemberton osteotomy provides good long-term radiographic and functional results without compromising acetabular version or coverage.

LEVEL OF EVIDENCE

Level III: retrospective comparative study.

[Femoral neck stress fractures and femoroacetabular impingement : A retrospective case study and literature review]

BACKGROUND

Femoroacetabular impingement (FAI) can lead to morphologic damage of both the acetabulum and the femoral neck. Recent reports have found an association between impingement deformities and the development of femoral neck stress fractures. The aim of this study was to report a series of patients with these findings and to update the current evidence on the topic.

MATERIAL AND METHODS

5 patients (6 cases) with atraumatic femoral neck fractures and FAI were identified in the Dresden hip registry from 2015 to 2018. Demographic data, comorbidities, radiographic results and bone metabolism results were described. A literature search was conducted using keywords related to femoral neck stress fractures and FAI syndrome.

RESULTS

The average age of the series was 39 (range: 22-52), 2 patients were female and 3 male. A total of 12 surgical procedures were performed. 4 of the 5 patients showed radiographic features of pincer and/or cam-FAI, whereas 3 patients had a decreased femoral antetorsion (-7° to +7° antetorsion). In 3 patients, magnetic resonance imaging revealed additional signs of avascular necrosis ARCO I. There was a lack of FAI-specific treatment recommendations in the available literature.

DISCUSSION

Radiographic results of the patients evaluated suggested that impingement-associated deformities of the hip may cause femoral neck stress fractures, which is in line with the available literature. This potential coincidence should be integrated in diagnostic algorithms and therapeutic approaches.

Acetabular- and femoral orientation after periacetabular osteotomy as a predictor for outcome and osteoarthritis

BACKGROUND

Periacetabular osteotomy is a successful treatment for hip dysplasia. The results are influenced, however, by optimal positioning of the acetabular fragment, femoral head morphology and maybe even femoral version as well as combined anteversion have an impact. In order to obtain better insight on fragment placement, postoperative acetabular orientation and femoral morphology were evaluated in a midterm follow-up in regard to functional outcome and osteoarthritis progression.

METHODS

A follow-up examination with 49 prospectively documented patients (66 hips) after periacetabular osteotomy (PAO) was performed after 62.2 ± 18.6 months. Mean age of patients undergoing surgery was 26.7 ± 9.6 years, 40 (82%) of these patients were female. All patients were evaluated with an a.p. pelvic x-ray and an isotropic MRI in order to assess acetabular version, femoral head cover, alpha angle, femoral torsion and combined anteversion. The acetabular version was measured at the femoral head center as well as 0.5 cm below and 0.5 and 1 cm above the femoral head center and in addition seven modified acetabular sector angles were determined. Femoral torsion was assessed in an oblique view of the femoral neck. The combined acetabular and femoral version was calculated as well. To evaluate the clinical outcome the pre- and postoperative WOMAC score as well as postoperative Oxford Hip Score and Global Treatment Outcome were analyzed.

RESULTS

After PAO acetabular version at the femoral head center (31.4 ± 9.6°) was increased, the anterior cover at the 15 o'clock position (34.7 ± 15.4°) was reduced and both correlated significantly with progression of osteoarthritis, although not with the functional outcome. Combined acetabular and femoral torsion had no influence on the progression of osteoarthritis or outcome scores.

CONCLUSION

Long-term results after PAO are dependent on good positioning of the acetabular fragment in all 3 planes. Next to a good lateral coverage a balanced horizontal alignment without iatrogenic pincer impingement due to acetabular retroversion, or insufficient coverage of the anterior femoral head is important.

Use of Physical Therapy in Patients With Osteoarthritis in Germany: An Analysis of a Linkage of Claims and Survey Data

OBJECTIVE

To examine the utilization of physical therapy (PT) and predictors for its use in individuals with osteoarthritis (OA) while focusing on sociodemographic and disease-related factors.

METHODS

For this cross-sectional study, 657,807 patients (age 30-79 years) diagnosed with hip, knee, or polyarticular OA were identified in claims data. In 2016, a questionnaire including information on disease status, demography, and socioeconomics was sent to a random sample of 8,995 patients stratified by sex, age, and type of diagnosis. Claims data from 2016 included the utilization and type of PT, as well as the prescribing medical specialist, and were linked to questionnaire data. Multivariable logistic regression was conducted to determine variables associated with the use of PT.

RESULTS

In total, 3,564 (40%) patients completed the questionnaire and agreed to linking questionnaire and claims data (69% female, mean age 66.5 years). In 2016, 50% of the study population received PT at least once, and women received it more frequently than men (53% versus 43%). Most PT was prescribed by orthopedists (45%) and general practitioners (32%). Multivariable logistic regression showed that women, higher household income, having both hip and knee OA, lower functional status, higher disease activity, and individuals living in the eastern, southern, and western states of Germany were associated with an increased utilization of PT.

CONCLUSION

Considering current guideline recommendations and that more than one-third of OA patients with high functional impairment and/or pain did not receive PT in the last 12 months, there is considerable potential for improvement. This is especially true for men and individuals with a low income.

Which disease-related factors influence patients' and physicians' willingness to consider joint replacement in hip and knee OA? Results of a questionnaire survey linked to claims data

Background

A great heterogeneity in total joint replacement (TJR) rates has been reported for osteoarthritis (OA), most likely arising from a gap between patients’ and physicians’ views on the need for TJR. The purpose of this study therefore was to analyze potential cofactors which might influence the desire of patients to undergo TJR and physicians’ willingness to discuss surgery with their patients.

Methods

A total of 8995 patients in Germany with a claims data diagnosis of hip or knee OA or polyarthrosis were asked to complete a questionnaire for this cross-sectional study of sociodemographic factors, indicators of current joint function (WOMAC score), willingness to undergo TJR and whether they had already discussed TJR with a physician. The overall response rate was 40%. Responders with polyarthrosis and individuals without current or chronic symptoms in the corresponding joints, pain in already replaced joints or simultaneous symptomatic hip and knee OA were excluded. We linked the survey results to claims data. Separate logistic regression models were used to assess which parameters were associated with patients’ willingness to undergo TJR and physicians’ discussion of surgery.

Results

We analyzed 478 hip OA and 932 knee OA patients. Just 17% with hip OA and 14% with knee OA were willing to undergo TJR, although 44 and 45% had already discussed surgery with their physicians.

Patients’ willingness was associated with higher WOMAC scores, a deterioration of symptoms over the last 2 years, and previous TJR for another joint. The discussion with a physician was influenced by the impact on personal life and previous arthroplasty. Older age (odds Ratio (OR) 1.2 per 10 years), male sex (OR 0.69 vs female), longer symptom duration (OR 1.08 per 5 years), deterioration of symptoms (OR 2.0 vs no change/improvement), a higher WOMAC score (OR 1.3 per 10% deterioration) and reduced well-being (OR 1.1 per 10% deterioration) were associated with physician discussion in knee OA patients.

Conclusions

The proportion of patients willing to undergo TJR is lower than the proportion in whom physicians discuss surgery. While previous TJR seems to enhance patients’ and surgeons’ willingness, the influence of other cofactors is heterogeneous.

THU0310 CASE–CONTROL SEROPREVALENCE STUDY ON THE ASSOCIATION BETWEEN BARTONELLA INFECTION AND ANTI-NEUTROPHIL CYTOPLASMIC ANTIBODY-ASSOCIATED VASCULITIS

Background:

Bartonellosis is an emerging anthropozoonosis caused by infection with intracellular Gram-negativeBartonellaspecies. It leads to necrotizing granulomas and endothelial damage and causes acute and chronic human diseases, such as cat scratch disease, bacillary angiomatosis and endocarditis. Endocarditis due toBartonella henselaeandB. quintanais reported to produce anti-neutrophil cytoplasmic antibodies (ANCAs) that disappear with effective antimicrobial treatment.

Objectives:

Hypothesizing a role forBartonellainfection in ANCA-associated vasculitis (AAV), which also includes granulomatous and vascular inflammation, we studied the seroprevalence of 5Bartonellaspecies in patients with AAV.

Methods:

The study used plasma samples from patients with granulomatosis with polyangiitis and microscopic polyangiitis that were enrolled in the Rituximab for AAV (RAVE) trial and from healthy controls living in the United States. Western blot assays were used for serological testing of infection withB. quintana,B. henselaeHouston-1,B. elizabethae,B. vinsoniisubsp.berkhoffiiandB. alsatica. The associations of positive serology results and AAV were expressed as odds ratios (OR). Clinical characteristics of seropositive and seronegative patients, assessed by the BVAS/WG instrument, were compared. These comparisons were done for 9 organ systems; in case they showed differences withP<0.10, the corresponding organ system-specific clinical features were also analyzed. Statistical analysis was performed using Fisher’s exact test or Student’s t-test, as appropriate.

Results:

We analyzed blood samples of 187 patients with AAV (collected at start of the trial) and of 127 controls. There were no significant differences between the cases and controls for mean age (P=0.148) and proportion of males (P=0.36).Bartonellaspp. serological testing was positive for 112 (60%) cases and 40 (31%) controls (OR 3.25 [95% CI 2.02–5.22],P<0.001). Significant associations were also found within subsets of PR3-AAV (OR 4.00 [95% CI 2.37–6.76],P<0.001), MPO-AAV (OR 2.18 [95% CI 1.17–4.06],P=0.017), newly-diagnosed (OR 3.89 [95% CI 2.21–6.86],P<0.001) and relapsing disease (OR 2.86 [95% CI 1.65–4.98],P<0.001). Species-specific positive serological testing was found in particular againstB. henselae(cases: 27%, controls: 0.8%; OR 39.93 [95% CI 5.42–293.90];P<0.001). Compared to AAV patients without seropositivity forBartonellaspp., AAV patients testing seropositive forBartonellaspp. had significantly more bloody nasal discharge (P=0.046), sinus involvement (P=0.035) and conjunctivitis/episcleritis (P=0.016).

Conclusion:

This study reveals higher seroprevalence ofBartonella, especiallyB. henselae, in patients with AAV than in healthy controls. Although cross-reactivity ofBartonellawith other microorganisms cannot be excluded, these results may support an etiopathogenic role ofBartonellainfection in AAV that deserves further investigation.

Disclosure of Interests:

Alfred Mahr Consultant of: Celgene, Speakers bureau: Roche, Chugai, Sophie Edouard: None declared, Divi Cornec: None declared, Solange GONZALEZ-CHIAPPE: None declared, Jörg Goronzy: None declared, Philippe Guilpain: None declared, Carol Langford: None declared, Pierre-Yves Lévy: None declared, Peter A. Merkel: None declared, Paul Monach: None declared, E. William St. Clair: None declared, Philip Seo: None declared, Robert Spiera Grant/research support from: Roche-Genetech, GSK, Boehringer Ingelheim, Chemocentryx, Corbus, Forbius, Sanofi, Inflarx, Consultant of: Roche-Genetech, GSK, CSL Behring, Sanofi, Janssen, Chemocentryx, Forbius, Mistubishi Tanabe, Cornelia Weyand: None declared, John H. Stone Grant/research support from: Roche, Consultant of: Roche, Didier Rauolt: None declared, Ulrich Specks: None declared

MRI-based static and functional assessment of complex hip deformities in comparison with CT: a validation study

Objective

This study aimed at investigating the agreement between predefined quantitative parameters of hip morphology derived from magnetic resonance imaging (MRI) and virtual range of motion (ROM) analysis using computed tomography (CT) as standard of reference.

Methods

Twenty patients (13 females, 7 males, 16–59 years) with hip deformities underwent MRI prior to surgery. Clockwise alpha angle, femoral head and neck diameter, collum caput diaphysis angle, femoral torsion, center-edge angles, acetabular coverage of the femoral head, sourcil angle, and acetabular anteversion were measured. Additionally, tern single and combined movements were simulated using a motion analysis program. The MRI findings were compared with the corresponding results obtained by CT. Correlation of MRI with CT was assessed using different statistical methods (intraclass correlation coefficient, Bland–Altmann plot, two one-sided t test), and linear regression analysis was performed.

Results

The results showed near-perfect intraclass correlation coefficients (ICCs) for anteversion (0.95), acetabular sector angles (0.98–0.99), sourcil angle (0.95), and acetabular coverage (anterior 0.96, posterior 0.99). Intermethod correlation for femoral parameters showed almost perfect agreement except for the alpha angle (0.73–0.97). No significant proportional bias was detected for traditional acetabular and femoral parameters. ROM analysis was performed for 370 movements in 37 hips. For 78.4% (290/370) of the movements analysed, neither CT nor MRI detected impingement across the physiological ROM. For 18.6% (69/370) of the movements, impingement was detected by both CT and MRI, while 2.2% (8/370) of the movements with impingement in CT showed no impingement in MRI, and 0.8% (3/370) of the movements with impingement in MRI had no corresponding result in CT.

Conclusion

Finally, it was concluded that MRI-based assessment of hip morphology and virtual ROM analysis is feasible and can be performed with good intermethod agreement in comparison to the gold standard (CT). Therefore, MRI appears to be substantially equivalent to CT for use in virtual ROM analysis and so may reasonably be used in place of CT for this purpose.

[Complication profile and revision concepts for megaprosthetic reconstruction following tumour resection at the hip]

BACKGROUND

Tumourous destruction of the periacetabular region and the proximal femur is a typical consequence of either primary malignant bone tumour manifestation or skeletal metastatic diseases. Pathological fractures of the proximal femur and periacetabular regions due to primary manifestation or metastatic disorders are frequent.

OBJECTIVES

Presentation of the most common complications of tumour endoprostheses at the hip and a description of management strategies, including therapeutic recommendations and concepts for complication avoidance.

MATERIALS AND METHODS

The current knowledge and our own experience of complication management with the use of megaprostheses around the hip are presented.

RESULTS

Compared to elective/primary total hip arthroplasty, megaprosthetic reconstructions following tumour resections have an increased rate of postoperative deep infections, dislocations, incidence of pathological and periprosthetic fractures and of deep vein thrombosis. The postoperative mortality and local tumour recurrence along with deep infections represent the most serious complications.

CONCLUSIONS

In comparison to primary arthroplasty, the risk of failure and complications following tumour-endoprosthetic replacement is increased. Precise surgical planning and careful selection and preoperative preparation of suitable patients should be performed in close interdisciplinary cooperation with final decision-making on an interdisciplinary tumour board. Wide resection and advanced reconstruction, as well as complicated palliative stabilization due to malignant bone tumour growth around the hip joint should be performed in musculoskeletal tumour centres with profound expertise in osteosynthetic and endoprosthetic reconstruction and consecutive complication management of the pelvis and the proximal femur.

Biomechanical comparison of bi- and tricortical k-wire fixation in tension band wiring osteosynthesis

Background

Patients with a simple transversal fracture of the olecranon are often treated with a tension band wiring (TBW), because it is known as a biomechanically appropriate and cost-effective procedure. Nevertheless, the technique is in detail more challenging than thought, resulting in a considerable high rate of implant-related complications like k-wire loosening and soft tissue irritation. In the literature, a distinction is generally only made between transcortical (bi-) and intramedullary (mono-) fixation of the wires. There is the additional possibility to fix the proximal bent end of k-wire in the cortex of the bone and thus create a tricortical fixation. The present study investigates the effectiveness of bi- and tricortical k-wire fixation in a biomechanical approach.

Methods

TBW of the olecranon was performed at 10 cadaver ulnas from six donors in a usual manner and divided into two groups: In group 1, the k-wire was inserted by bicortical fixation (BC), and in group 2, a tricortical fixation (TC) was chosen. Failure behavior and maximum pullout strength were assessed and evaluated by using a Zwick machine. The statistical evaluation was descriptive and with a paired t test for the evaluation of significances between the two techniques.

Results

The average age of the used donors was 81.5 ± 11.5 (62–92) years. Three donors were female, and three were male. Ten k-wires were examined in BC group and 10 in the TC group. The mean bone density of the used proximal ulnas was on average 579 ± 186 (336–899) HU. The maximum pullout strength was 263 ± 106 (125–429) N in the BC group and increased significantly in the TC group to 325 ± 102 (144–466) N [p = .005].

Conclusion

This study confirms for the first time biomechanical superiority of tricortical k-wire fixation in the olecranon when using a TBW and may justify the clinical use of this method.

[Utilization of individual out-of-pocket health services (IGeL) in persons with osteoarthritis in Germany : Results of a survey from the PROCLAIR study]

BACKGROUND

Little is known about the utilization of individual health services performed by a physician (IGeL) and the services and supplements provided outside a doctor's office (MuPaP) for osteoarthritis patients.

OBJECTIVES

The aims of this study are to analyze the use of osteoarthritis-specific IGeL and MuPaP as well as predictors for their utilization.

MATERIALS AND METHODS

For this cross-sectional study, claims data was used to identify all persons with hip, knee, or polyarticular osteoarthritis in 2014 (n = 657,807). A random sample (n = 8995) was sent a questionnaire about their usage of IGeL and MuPaP. Furthermore, the type of physicians conducting or recommending services was evaluated. Applying multivariable logistic regression, predictors associated with the utilization of IGeL, MuPaP, and overall individual health services were analyzed.

RESULTS

After validating the data and osteoarthritis diagnosis, 2363 persons were enrolled (mean age: 65.5 years, 72% female). In the last 12 months, 39% of patients had used at least one IGeL (MuPaP: 76%), with 86% being primarily performed by orthopedists (MuPaP: 88% patient self-motivated). Knee osteoarthritis was associated with increased utilization of IGeL. Having female gender, higher income, residence in Western Germany, higher disease burden, and lower satisfaction with the healthcare system were influences on the use of overall individual health services.

CONCLUSIONS

Since patients with high disease burden in particular tend to use these therapies with varying treatment success, detailed information, especially about the risks and existing evidence, should be a prerequisite for trustworthy doctor-patient relationships.

Is MRI an adequate replacement for CT scans in the three-dimensional assessment of acetabular morphology?

BACKGROUND

Appropriate three-dimensional imaging of the hip joint is a substantial prerequisite for planning and performing surgical correction of deformities. Although surgeons still use computed tomography (CT), modern and fast acquisition techniques of volumetric imaging using magnetic resonance imaging (MRI) for pelvic measurements enable similar resolution.

PURPOSE

This study was designed to determine if already described measures of acetabular morphology are comparable in both techniques and if assessment can be performed with equal intra-observer and inter-observer reliability.

MATERIAL AND METHODS

Thirty-two hips (16 patients) were examined with a pelvic CT and a MRI with 3-T. Pelvic orientation was standardized by each observer in coronal, axial, and sagittal planes. Acetabular version as well as seven acetabular sector angles were measured by two observers twice with a minimum of four weeks between sessions.

RESULTS

Inter-rater reliability showed excellent results for intra- and inter-rater reliability for CT (0.977-0.999) and MRI (0.969-0.998) measuring acetabular version and sector angles. Evaluating the reliability of CT and MRI for each observer revealed excellent results (0.972-0.998). Evaluating the Bland-Altman plots for intra-observer reliability showed an equal distribution of angles, within acceptable 95% limits of agreement. The same results were observed for inter-observer reliability evaluating CT and MRI as well as inter-method reliability.

CONCLUSION

Modern MRI scans are equally applicable to assess the bony pelvis as CT scans. In addition, MRI would enable the examination of soft tissues such as chondrolabral structures and muscle in the same examination. Since hip-preserving surgery is mostly conducted in younger patients, the reduction of radiation exposure is a benefit.

Prevalence and treatment of hip and knee osteoarthritis in people aged 60 years or older in Germany: an analysis based on health insurance claims data

Objective

Osteoarthritis (OA) is highly prevalent throughout the world, especially in the elderly population, and is strongly associated with patients’ frailty. However, little is known about the prevalence and treatment of OA in elderly patients in routine clinical care in Germany.

Materials and methods

As a part of Linking Patient-Reported Outcomes with CLAIms Data for Health Services Research in Rheumatology (PROCLAIR), a cross-sectional study using claims data from a large Germany statutory health insurance (BARMER) was conducted. We included people aged 60 years or older and assessed the prevalence of OA of the hip or knee, defined as having outpatient diagnoses (ICD: M16 or M17) in at least two quarters of 2014. The use of conservative treatment, including analgesics and physical therapy, and total joint replacement was studied. Analyses were stratified by age, sex, comorbidities, and level of care dependency defined by social law.

Results

A total of 595,754 patients (mean age: 74.9 years; 69.8% female) were diagnosed with OA (21.8%), with the highest prevalence in those between 80 and 89 years (31.0%) and in females compared to males (23.9% vs 18.3%). Prevalence decreased with increasing level of care dependency from 30.5% in patients with a low level (0/1) to 18.7% in the highest level of care dependency. A total of 63.4% of the patients with OA received analgesics, with higher use with increasing age. Physical therapy was prescribed to 43.1% of the patients, but use decreased with age. In all, 5.3% of the patients received total joint replacement in 2014.

Conclusion

The lower frequency of coded OA with increasing level of care dependency may reflect underdiagnosis, and patients with many other medical problems seem to be at risk for inadequate recognition and treatment of their OA.

Prospective randomized controlled trial in the treatment of lateral epicondylitis with a new dynamic wrist orthosis

BACKGROUND

In the treatment of lateral epicondylitis (LE), the role of a new dynamic wrist orthosis is unclear.

PATIENTS AND METHODS

Patients suffering from a LE longer than 3 months were multicentrically and prospectively randomized into a physiotherapeutic group (PT group) and in a physiotherapy group plus wrist orthosis (PT + O group). Physiotherapy consisted of daily eccentric strengthening exercises under initial professional supervision. Inclusion criteria were a Placzek score greater than 4. Exclusion criteria were previous surgery, rheumatic arthritis, elbow instability, radicular symptoms, higher-grade extensor tendon rupture, or cervical osteoarthritis. The clinical evaluation was performed after 12 weeks and 12 months. The Patient-Rated Tennis Elbow Evaluation (PRTEE) scale, Placzek Score, the pain rating (VAS), range of motion and the Subjective Elbow Score were evaluated.

RESULTS

Of the initially 61 patients, 31 were followed up after 12 weeks and 22 after 12 months. Twenty-nine patients (43%) were male, the mean age was 46, and 44 patients (66%) had the right elbow involved. At 12 weeks, there was a pain reduction on the VAS in both groups (PT + O: 6.5-3.7 [p = .001]; PT: 4.7-4.1 [p = .468]), albeit it was only significant for the PT + O group. At 12 months, reduction was significant in both groups (PT + O: 1.1 [p = .000]; PT: 1.3 [p = .000]). The painless maximum hand strength in kg improved in both groups significant after 3 and 12 months. The Placzek score was reduced from 8.25 to 3.5 [p = .001] after 12 weeks for the PT + O group and from 8.1 to 3.8 [p = .000] in the PT group, as well as after 12 months in the PT + O group to 0 [p = .000] and in the PT group to 2.0 [p = .000]. The PRTEE improved in both groups after 12 weeks (PT + O: 52.8--31.3 [p = .002]; PT: 48.6-37.6 [p = .185]) and 12 months (PT + O: 16.15 [p = .000]; PT: 16.6 [p = .000]), although the reduction at 12 weeks was not significant for the PT group.

CONCLUSION

The elbow orthosis appears to accelerate the healing process with respect to the PRTEE and pain on the VAS (12 weeks follow-up), although there is an adjustment after 12 months in both groups and a significant improvement of symptoms is achieved in all endpoints.

[Total hip arthroplasty in overweight osteoarthritis patients]

BACKGROUND

An increasing number of patients scheduled for total hip arthroplasty (THA) are obese and exhibit a different risk profile from that of patients of normal weight.

OBJECTIVES

To provide an overview of the impact of obesity on the outcome of primary THA.

MATERIALS AND METHODS

Literature review and discussion of own epidemiological data.

RESULTS

Obese patients can expect as much functional improvement as non-obese patients after THA. However, peri- and postoperative complication (e.g., periprosthetic infection and dislocation) rates are reported to be increased in obese THA patients.

CONCLUSIONS

The knowledge of obesity-associated risks is the prerequiste for successful THA in obese patients.

Subtalar dislocations

Subtalar dislocations make up 1-2% of all dislocations, about 75% of them being medial dislocations. Treatment consists of early reduction under adequate sedation. In cases of soft tissue interposition or locked dislocations, open reduction is warranted. More than 60% of subtalar dislocations are associated with additional fractures, therefore a postreduction CT is recommended. Complications include avascular necrosis of the talus, infection, posttraumatic arthritis, chronic subtalar instability, and complex regional pain syndrome with delayed reduction. The prognosis of purely ligamentous injuries is excellent after early reduction. Negative prognostic factors include lateral and open dislocations, total talar dislocations, and associated fractures.

[Arthroplasty for osteoarthritis secondary to hip dysplasia: Problem-oriented treatment strategies]

BACKGROUND

Because of anatomical variations total hip arthroplasty (THA) can be demanding in patients with osteoarthritis secondary to hip dysplasia.

OBJECTIVES

Depending on the degree of bony deformation, hip dislocation and soft tissue alteration numerous treatment strategies are available. This review describes current approaches that address frequent deformities.

MATERIALS AND METHODS

Review of relevant clinical studies, meta-analyses, and presentation of our own approach.

RESULTS

Pre-operative planning (based on a thorough clinical and radiographic examination) is essential. Acetabular reconstruction close to the primary acetabulum should always be intended. Roof augmentation and/or cup medialization can support stable bony implant fixation. Subtrochanteric shortening osteotomy of the femur is a demanding but reliable technique that avoids nerve damage in cases where inappropriate lengthening would be necessary (i.e., high riding dislocation).

CONCLUSIONS

Although the post-operative complication rate is elevated after THA for dysplastic hips compared with primary osteoarthritis, the overall functional results and implant survival are comparable.

Effect of surgical experience on imageless computer-assisted femoral component positioning in hip resurfacing--a preclinical study

Background

The clinical outcome of hip resurfacing (HR) as a demanding surgical technique associated with a substantial learning curve depends on the position of the femoral component. The aim of the study was to investigate the effects of the level of surgical experience on computer-assisted imageless navigation concerning precision of femoral component positioning, notching, and oversizing rate, as well as operative time.

Methods

Three surgeons with different levels of experience in both HR and computer-assisted surgery (CAS) prepared the femoral heads of 54 synthetic femurs using the Durom^TM Hip Resurfacing (Zimmer, Warsaw, IN, USA) system. Each surgeon prepared a total of 18 proximal femurs using the Navitrack® system (ORTHOsoft Inc., Montreal, Canada) or the conventional free-hand Durom^TM K-wire positioning jig. The differences between planned and postoperative stem shaft angle (SSA) and anteversion angle in standardized x-rays were measured and the operative time, not including the time for calibrating the CAS-system, was documented. Notching was evaluated by the three surgeons in a randomized manner. Oversizing was determined by the difference of the preoperative determined cap and the cap size advised by the CAS-system.

Results

CAS significantly reduced the overall mean deviation between planned and postoperative SSA in comparison with the conventional procedure (mean ± SD, 1 ± 1.7° vs. 7.4 ± 4.4°, P <0.01) regardless of the surgeon’s level of experience. The incidence of either varus or valgus SSA deviations exceeding 5° were 1/27 for CAS and 15/27 for the conventional method, respectively (P <0.001), corresponding to a reduction by 97%. Using CAS, the rate of notching was reduced by 100%.

Conclusions

The accuracy of femoral HR component orientation is significantly increased by use of CAS regardless of the surgeon’s level of experience in our preclinical study. Thus, imageless computer-assisted navigation can be a valuable tool to improve implant positioning in HR for surgeons at any stage of their learning curve.

[Avoidance, diagnostics and therapy of nerve lesions after total hip arthroplasty]

Nerve palsy following total hip arthroplasty is a rare complication. Developmental dysplasia of the hip, previous fracture treatment and medical comorbidities are characteristic risk factors. By accurate preparation of the patient and a careful operative technique nerve palsy can be avoided in most cases. Nerve palsy following poor patient positioning during the perioperative period should be avoided by close cooperation with anesthesiologists.In cases of postoperative nerve palsy correct diagnostics should be carried out immediately. Further treatment options should be considered to minimize the damage. For patients with definite nerve palsy, devices such as a foot drop splint are often necessary and should be carried out as soon as possible.

Selective induction of rheumatoid factors by superantigens and human helper T cells

Production of autoantibodies specific for the Fc region of autologous IgG, called rheumatoid factors (RF), is a characteristic finding in patients with rheumatoid arthritis (RA). To study the requirements regulating the synthesis of these autoantibodies, we have cloned human helper T cells and co-cultured them with purified B cells. To mimic cognate T-B cell interaction, we have used bacterial superantigens that function by cross-linking HLA molecules on the B cell with selected T cell receptor (TCR) molecules expressing a particular polymorphism of the V beta gene segment. Data presented here demonstrate that the staphylococcal enterotoxin D (SE D), but not other bacterial superantigens, exhibits an ability to induce IgM, IgG, and especially RF production, in B cells from RA patients and normal individuals. Comparison with the polyclonal antibody production in B cell cultures driven by anti-CD3-stimulated T cell clones confirmed that SE D shifted the repertoire of secreted antibodies toward immunoglobulins with Fc binding specificity, suggesting that SE D preferentially stimulates RF+ B lymphocytes. B cells with the potential to secrete RF were highly frequent in RA patients, requiring as few as 150 peripheral B cells/culture to detect RF in the culture supernatants. SE D-induced RF synthesis was strictly dependent on the presence of selected CD4+T helper cells and required a direct membrane contact between B cells and T helper cells. Here, we propose a model that SE D selectively induces RF production depending on the availability of SE D responsive T cells in the TCR repertoire of the responder.

[Nodular panniculitis: a manifestation of Lyme borreliosis?]

Infection with Borrelia burgdorferi can induce various skin manifestations. The type of skin manifestation and the histopathological picture depend on the stage of infection and vary from local inflammatory infiltrates to chronic atrophic skin disease. Involvement of subcutaneous tissue has been observed only very rarely. We report on two patients suffering from nodular panniculitis (Pfeifer-Weber-Christian) and present evidence that the disease was caused by Borrelia burgdorferi. In one of the cases Borrelia burgdorferi was repeatedly isolated from skin and subcutaneous tissue biopsies in spite of repeated high-dose therapy with ceftriaxone, Doxycycline and cefotaxime.

Immunosuppression by anti-CD4 treatment in vivo. Persistence of secondary antiviral immune responses

Elimination of CD4+ helper T cells by treatment with monoclonal antibodies (mcAb) in vivo has been used as a new mode of immunosuppression in organ transplantation and autoimmune diseases. To explore the potential risks of this therapeutic approach we have studied antiviral responses in mice depleted of CD4+ T cells. Depletion of CD4+ T cells in vivo completely suppressed the generation of a primary virus-specific cytotoxic response. Injection of high doses of recombinant interleukin-2 (rIL-2) given after virus immunization restored the responsiveness of helper cell-depleted mice to virus-expressing target cells, suggesting a crucial role of IL-2 in antiviral defense mechanisms. In contrast to primary responses, memory cytolytic responses to viral antigens persisted despite depletion of greater than 90% of CD4+ helper T cells. The generation of such memory cytotoxic responses was dependent upon help provided by CD4+ lymphocytes surviving the antibody therapy. After antibody treatment, frequencies of virus-specific helper cells were minimal in primed mice, excluding insufficient helper cell elimination as the reason for the persistence of memory responses. Data presented here suggest that there exist distinct helper pathways in primary and secondary cytolytic antiviral responses that might represent several subsets of helper T cells as well as differences in helper signals required by distinct effector cells.

Immunosuppression by anti-CD4 treatment in vivo. Cellular and humoral responses to alloantigens

Antibody-mediated elimination of CD4+ lymphocytes in vivo has been successfully used to suppress the humoral response to foreign antigens and to induce long-term tolerance. However, secondary humoral responses, as well as secondary cytolytic responses specific for viral antigens, could not be prevented, providing evidence for functional heterogeneity within the helper cell compartment. Data presented here support the notion that helper cell requirements for cellular responses to alloantigens are unique and do not involve CD4+ T lymphocytes. While the administration of anti-CD4 mcAb failed to suppress allospecific CTL responses, the formation of alloantibodies was initially inhibited in parallel to the deficiency in CD4+ helper cells. After regeneration of CD4+ T cells, the animals regained the ability to produce specific IgG alloantibodies. The dichotomy of helper pathways in humoral and cellular alloreactive responses challenges the concept of a single CD4+ helper cell population. Insights into the functional heterogeneity of helper cells for primary, secondary, and allospecific responses might open new avenues for selective manipulation of helper subpopulations.

Enhanced cell-mediated protection against fatal Escherichia coli septicemia induced by treatment with recombinant IL-2

Administration of rIL-2 to BALB/c mice induces a rapid, cell-mediated response that is sufficient to protect mice from a lethal i.p. dose of Escherichia coli. Mice were protected from septic death if IL-2 was administered i.p. within 1 h after the bacterial challenge. Optimal protection was provided by treating the lethally challenged mice with rIL-2 at 1 and 5 h or 1, 5, and 10 h after the bacterial challenge and was dose-dependent (greater than or equal to 5.0 x 10(5) U/kg). Furthermore, treatment of mice with anti-IL-2R antibody abolished the protective effect induced by rIL-2 administration. These data suggest that the rIL-2-induced protection against septic death in mice is mediated by a cell type expressing a functional IL-2R. One potentially important therapeutic application of rIL-2 may be to modulate the course of sepsis once the host has been exposed to potentially lethal microbial pathogens.

Enhanced cell-mediated protection against fatal Escherichia coli septicemia induced by treatment with recombinant IL-2

Administration of rIL-2 to BALB/c mice induces a rapid, cell-mediated response that is sufficient to protect mice from a lethal i.p. dose of Escherichia coli. Mice were protected from septic death if IL-2 was administered i.p. within 1 h after the bacterial challenge. Optimal protection was provided by treating the lethally challenged mice with rIL-2 at 1 and 5 h or 1, 5, and 10 h after the bacterial challenge and was dose-dependent (greater than or equal to 5.0 x 10(5) U/kg). Furthermore, treatment of mice with anti-IL-2R antibody abolished the protective effect induced by rIL-2 administration. These data suggest that the rIL-2-induced protection against septic death in mice is mediated by a cell type expressing a functional IL-2R. One potentially important therapeutic application of rIL-2 may be to modulate the course of sepsis once the host has been exposed to potentially lethal microbial pathogens.

Triggering of T-lymphocytes via either T3-Ti or T11 surface structures opens a voltage-insensitive plasma membrane calcium-permeable channel: requirement for interleukin-2 gene function

Stimulation of human T-lymphocytes via either the surface T3-Ti antigen-major histocompatibility complex receptor complex or the T11 molecule results in clonal proliferation through a calcium-dependent mechanism. To investigate this signal transduction, plasma membrane calcium-permeable channels were characterized in T-lymphocytes by means of whole cell or single channel patch-clamp recordings. Stimulation of T-lymphocytes via either structure results in opening of an identical set of voltage-insensitive plasma membrane Ca2+-permeable channels through the action of a diffusible second messenger. Previous work with excised inside-out patches suggests that inositol 1,4,5-trisphosphate is the activating second messenger of the voltage-insensitive T-cell Ca2+-permeable channel. Since there is a significant increase in phosphoinositide turnover after stimulation via either the T3-Ti or T11 pathway, it is suggested that triggering of either structure opens a common set of channels through this mechanism. Furthermore, currents flowing through Ca2+-permeable channels are apparently autoregulated, as inward conductance is abolished by elevation of Ca2+ concentration in the bathing solution. In particular, the steady-state rise in interleukin-2 (T-cell growth factor) mRNA is dependent on the rise of [Ca2+]i resulting from ion movement across this channel.

Administration in vivo of recombinant interleukin 2 protects mice against septic death

Administration in vivo of recombinant interleukin 2 (rIL-2) to mice induces a polyclonal IgM response. When co-administered with a specific antigen, rIL-2 can enhance concentrations of murine IgM antibodies specific for the antigen by fivefold within 7 d of initial treatment. IgM antibodies that are induced after injection of rIL-2 include antibodies specific for J5, a cell wall core lipopolysaccharide (LPS) antigen that is shared by the different members of the Enterobactericeae family. We report here that mice pretreated with rIL-2 or immunized with J5 antigen 7 d before bacterial challenge were protected from septic death that is caused by intraperitoneal challenges with Escherichia coli. Optimal protection was provided by a combined J5 antigen and rIL-2 treatment. Acquisition of the rIL-2 and J5 antigen-induced protection against lethal bacterial infection coincided temporally with maximal serum IgM titers that also contained IgM antibodies specific for the J5 antigen. In passive immunization experiments, the affinity-purified IgM fraction in sera of rIL-2-treated animals was identified as necessary and sufficient for protection. The IgM-depleted serum had no protective effect. The nonspecific augmentation of host-defense mechanisms without the induction of endotoxin manifestations makes rIL-2 a potential candidate to any alternative LPS-containing vaccines for the prevention of bacterial infections by gram-negative organisms since the core LPS antigen is shared among gram-negative bacteria.

Heterogeneity of signal requirements in T cell activation within a panel of human proliferative T cell clones

Activation of T lymphocytes is initiated by receptor ligand interactions at the cell surface leading to the transduction of intracellular signals followed by the de novo synthesis and expression of T cell activation markers (including receptors for interleukin 2 (IL 2) and transferrin), production of lymphokines, and T cell proliferation. This requisite first step for activation of T lymphocytes can be mimicked in certain situations with a variety of stimuli. These include antibodies to certain integral membrane proteins, phorbol esters, and plant lectins that act as mitogens. In this paper, we report that at least two classes of human T cell clones can be distinguished based upon signal requirements necessary to induce proliferation. Although all clones analyzed expressed IL 2 receptors and secreted IL 2 after non-antigenic activation, one subset of clones did not proliferate in response to the same non-antigenic signals. In that subset, complete activation leading to proliferation required interaction of the T cell with specific antigen. The ability to subset these T cell clones into two groups did not correlate with phenotypic differences, source of the clone, nor with magnitude of intracellular calcium mobilization. By studying the stimulation requirements of these two subsets of human T cell clones through the use of specific antigen or antigen-independent stimuli, it was possible to demonstrate that different stimuli varied in their ability to induce steps of T cell activation. Analysis of reactivity of these clones to suboptimal stimulation allowed the definition of intermediate stages of T cell activation. Such intermediate stages might reflect a diversity of intracellular signaling pathways or a complexity of regulatory mechanisms distal to the events that allow intracellular calcium mobilization. Thus for the first time, it has been possible to study ordered events of T cell activation in non-transformed, antigen-dependent human T lymphocytes. The data presented in this paper suggest that T cell activation is not an all or nothing phenomenon, and there is an ordered sequence of events that can be differentiated based upon signal requirements at the T cell membrane.

Heterogeneity of signal requirements in T cell activation within a panel of human proliferative T cell clones

Activation of T lymphocytes is initiated by receptor ligand interactions at the cell surface leading to the transduction of intracellular signals followed by the de novo synthesis and expression of T cell activation markers (including receptors for interleukin 2 (IL 2) and transferrin), production of lymphokines, and T cell proliferation. This requisite first step for activation of T lymphocytes can be mimicked in certain situations with a variety of stimuli. These include antibodies to certain integral membrane proteins, phorbol esters, and plant lectins that act as mitogens. In this paper, we report that at least two classes of human T cell clones can be distinguished based upon signal requirements necessary to induce proliferation. Although all clones analyzed expressed IL 2 receptors and secreted IL 2 after non-antigenic activation, one subset of clones did not proliferate in response to the same non-antigenic signals. In that subset, complete activation leading to proliferation required interaction of the T cell with specific antigen. The ability to subset these T cell clones into two groups did not correlate with phenotypic differences, source of the clone, nor with magnitude of intracellular calcium mobilization. By studying the stimulation requirements of these two subsets of human T cell clones through the use of specific antigen or antigen-independent stimuli, it was possible to demonstrate that different stimuli varied in their ability to induce steps of T cell activation. Analysis of reactivity of these clones to suboptimal stimulation allowed the definition of intermediate stages of T cell activation. Such intermediate stages might reflect a diversity of intracellular signaling pathways or a complexity of regulatory mechanisms distal to the events that allow intracellular calcium mobilization. Thus for the first time, it has been possible to study ordered events of T cell activation in non-transformed, antigen-dependent human T lymphocytes. The data presented in this paper suggest that T cell activation is not an all or nothing phenomenon, and there is an ordered sequence of events that can be differentiated based upon signal requirements at the T cell membrane.