Risk Analysis of Restrictive Factors for Fast-Track Knee Arthroplasty-A Retrospective Study of 1,224 Patients.

INTRODUCTION: With the implementation of a fast-track principle as an interdisciplinary and multimodal concept, an accelerated convalescence and reduction of postoperative complications and a reduction of hospital stay can be achieved. This has been shown not only to increase patient satisfaction but in reduction of hospital cost as well. However, the concept cannot be successfully implemented in all patients. Patients who require an extended length of stay (LOS) after surgery can profit from optimizations of postoperative care and rehabilitation as well. Therefore, early identification of such patients is desirable. This case control study aimed to identify patient characteristics and patient-independent factors that may affect fast-track programs and lead to extended length of stay in knee arthroplasty. MATERIALS AND METHODS: From October 2007 to May 2013, 1224 patients were treated at the University Hospital Halle (Saale) with a total knee arthroplasty (TKA). A maximum stay of seven days was defined as the target of the "fast-track arthroplasty" concept. There were 164 patients (13%) that did not reach this timeframe and were assigned to the case group (n=164). Each case group patient was compared to a patient with an inpatient stay of seven days or less who was operated on the same day and by the same surgeon. These patients formed the control group (n=164). In addition to causes for extended LOS, metadata (age, sex, body mass index [BMI]), chronic nicotine and alcohol abuse, American Society of Anesthesiology (ASA) score, blood transfusion necessity, and comorbidities were determined. The statistical analysis included two sample t-tests, a chi-square test, and logistic regression analyses. Additionally, 95% confidence intervals were calculated (p<0.05). RESULTS: Gender distribution in both groups showed no differences (case group: 40.2% male, 59.8% female vs. control group: 32.3% male, 67.7% female). The ø age in the case group was 69.6 ± 8.7 years, significantly higher than that of the control group with 66.5 ± 9.4 years (p=0.002). Another difference between the groups was seen in the need for red blood cell transfusion (case group 51.2%, control group 39.6%, p=0.03). The need for postoperative antibiotic therapy was associated with a 3.741-fold risk of prolonged hospital stay. ASA score and BMI were identical in both groups. For the patients with positive nicotine abuse, the regression analysis showed a 2.465-fold risk of prolonged length of stay. Alcohol abuse did not appear to play a role in length of stay in our patient cohort. For pre-existing conditions, patients from the case group were more likely to have a cardiac burden than those from the control group (p=0.03). The most common causes of prolonged LOS were elevated CRP followed by effusion and delayed wound healing. CONCLUSION: The study shows that especially patient age, the presence of cardiac secondary diseases, nicotine consumption, and patient-independent factors like blood loss could have a negative influence on convalescence. Despite constant cost reductions in the healthcare system, the concept of "fast track arthroplasty" should always be adapted to the specifics of each individual patient in view of increasing patient age or critically questioned already preoperatively.

[Periprosthetic infection after total hip replacement : Risk factors for an early infection after primary implantation]. / Periprothetischer Infekt nach Hüftprothesenimplantation : Risikofaktoren für die Entwicklung einer Frühinfektion nach Primärimplantation.

BACKGROUND: Periprosthetic infection is one of the most serious complications in primary arthroplasty. The infection rates reported in the current literature range from 0.36 to 2.23%. OBJECTIVES: The aim of this retrospective case-control study was to determine preoperative risk factors for the occurrence of early periprosthetic infection after primary hip arthroplasty. MATERIALS AND METHODS: The influence of patient age, gender, body mass index (BMI), C­reactive protein, preoperative leukocyte count and morbidity level (American Society of Anaesthesiologists score) on the occurrence of periprosthetic early infection of the hip joint was examined, and their correlation was investigated. RESULTS: Of the 1383 patients followed up, 25 were diagnosed with early infection. With an increase in BMI of 1 kg/m2, the risk of periprosthetic early infection increased by 12.1% (p < 0.001). In addition, using the receiver operating characteristic (ROC) curve, a BMI ≥ 29 kg/m2 is identified as a significant cut-off for the increased likelihood of periprosthetic hip infection. Using the ROC curve, a preoperative CrP value > 5 mg/l can be validated as a cut-off value for an increased risk of early infection. Using binary logistic regression, no influence of CrP > 5 mg/l on the development of early infection was statistically proven (p = 0.065). CONCLUSIONS: Patients with a BMI ≥ 29 kg/m2 should be informed about the increased risk of periprosthetic early infection after hip prosthesis implantation and a risk assessment should be performed. Furthermore, the determination of the preoperative CrP value should be considered standard.

Correction to: The High Flex Total Knee Arthroplasty-Higher Incidence of Aseptic Loosening and No Benefit in Comparison to Conventional Total Knee Arthroplasty: Minimum 16-Years Follow-Up Results.

[This corrects the article DOI: 10.1007/s43465-020-00276-3.].

Correction to: The High Flex Total Knee Arthroplasty-Higher Incidence of Aseptic Loosening and No Benefit in Comparison to Conventional Total Knee Arthroplasty: Minimum 16-Years Follow-Up Results.

[This corrects the article DOI: 10.1007/s43465-020-00276-3.].

Retrospective Clinical and Radiological Outcomes of Total Hip Arthroplasty in 51 Patients After a Mean 8.2 Years Using the Nanos® Short-stem Prosthesis.

INTRODUCTION: Over the past several years, femoral short-stem hip implants have become more popular as a treatment option in the field of primary hip arthroplasty for younger and more active patients. Current data on clinical outcomes and the implant survival rates in patients with short-stem implants cover a maximum of five to six years. The aim of this study was to assess the survival rates, as well as clinical and functional outcomes, in total hip arthroplasty (THA) using the Nanos® short-stem implant (Smith & Nephew, Marl, Germany) over a follow-up period exceeding 5 y. MATERIALS AND METHODS: This single-center retrospective study included the first 100 patients who were treated at the Department of Orthopedics at the University Hospital Halle (Saale) between January 2008 and February 2009. Ultimately, the complete data of 51 patients (54 hips) were reviewed. The follow-up period was from May to November 2017. We evaluated patient satisfaction regarding pain and function using a grading system. The Harris Hip Score and Forgotten Joint Score were obtained to evaluate functional outcome after THA. Postoperative radiographic evaluation included the measurement of leg-length discrepancy, changes in the shaft axis, femoral offset and horizontal or vertical center of rotation. Potential postoperative shaft angulation or axial shaft migration was also determined. Radiographic images were checked for radiolucent lines and heterotopic ossification using the classification systems outlined by Green and Brooker. RESULTS: The average follow-up was 97.8 months (8.2 y). The mean patient age at follow-up was 68 y and the body mass index was 28.2 kg/m2. The mean Harris hip score at follow-up was 92.0 and the Forgotten Joint Score was 91.7 %. Survey results showed that patient satisfaction and pain perception were rated very good. No significant change in leg length was observed (mean: 0.1 mm shortening). Overall, a rather varus stem positioning was detected postoperatively (mean: 3.1°). The femoral offset was slightly reduced on average in the entire patient group (mean: -1.8 mm). In the horizontal plane, lateralization of the center of rotation was detected overall (mean: 0.7 mm). In the vertical plane, cranialization was noted (mean: 1.4 mm). The CCD angle did not change. There was no further stem migration postoperatively. Radiolucent lines occurred in 10 cases in Gruen zones 1 and 7. Heterotopic ossification occurred in stages 1 to 3 according to the Brooker classification system. We found no cases of aseptic loosening or other reasons for revision. CONCLUSION: The outcomes after a mean follow-up of 97.8 months (8.2 y) showed that high levels of patient satisfaction and functional outcome can be achieved with the use of a short-stem endoprosthesis. Sufficient restoration of the patient's individual anatomy paired with high survival rates makes this short-stem prosthesis a reliable implant in total hip arthroplasty.

The High Flex Total Knee Arthroplasty-Higher Incidence of Aseptic Loosening and No Benefit in Comparison to Conventional Total Knee Arthroplasty: Minimum 16-Years Follow-Up Results.

PURPOSE: This prospective randomized study compares the clinical and radiographic long-term results at least 16 years after total knee arthroplasty (TKA) between a mobile-bearing high flex and a fixed-bearing posterior-stabilized knee. METHODS: In 2000, we included 60 patients who underwent a TKA. Patients were divided into two groups. At the time of the follow-up after a minimum of 16 years (16.5 years ± 0.6), 16 patients had died for causes unrelated to the operation, 15 were lost to the follow-up. Five patients of the high flex group had a revision. The final evaluation included the hospital for special surgery score (HSS) and radiographs. Using the X-rays and the Knee Society Roentgenographic Evaluation and Scoring System, radiolucent lines and the maximal knee flexion were determined. RESULTS: No significant differences between the two groups were found. The mean HSS score of LPS group patients was 87.9 (± 10.6) points and that of the high flex group was 93.1 (± 7.4) points. Five patients of the high flex group had undergone a reoperation. One knee was revised for painful mid-flexion instability and the others for symptomatic aseptic loosening of the components. CONCLUSION: The long-term follow-up does not show any clear benefits and even a higher incidence of implant loosening using the mobile-bearing high-flex knee.

Risk analysis of restrictive factors for fast-track hip arthroplasty - a retrospective study of 1138 patients.

Fast track programs have been introduced to reduce perioperative complication rates and to quickly reintegrate the patient into everyday life. The aim of this retrospective case-control study was to identify patient characteristics and patient-independent factors that influence fast track programs in hip arthroplasty. A total of 1138 patients were examined. A hospital stay of more than seven days was used to define the case group. In addition to the causes for the longer hospitalisation, age, sex, BMI, chronic nicotine and alcohol abuse, ASA score, surgical duration, anaemia and blood transfusion as well as concomitant diseases were assessed. The statistical analysis included two-sample t-test, chi-square test and logistic regression analyses. An 95% confidence interval was calculated (p<0.05). 16.9% of patients could not leave the hospital on the seventh day. The main causes were delayed wound healing (69.4%), increased CRP (43.0%>100 mg/l), and internal complications (19.7%). At a mean of 69.2 ± 10.7 years, the age of the case group was significantly higher than that of the control group, which had a mean of 63.3 ± 10.3 years (p<0.001). Cardiac comorbidities (p<0.001), BMI (p=0.023), and alcohol consumption (p<0.001) increased the risk for longer hospitalisation. Significant patient-independent factors were duration of the surgery (p<0.001) and transfusion (p<0.001). Successful application of fast-track hip arthroplasty is possible for every patient. However, longer hospi- talisation and delayed discharge must be taken into account for patients with advanced age, cardiac comorbidities, alcohol consumption, and high BMI.

Superior clinical results and higher satisfaction after customized compared with conventional TKA.

Investigation of functional outcome and patient`s satisfaction after implantation of a customized versus conventional TKA. In 31 consecutively enrolled patients with primary gonarthrosis, 33 customized TKA (custTKA) and in 31 patients, a conventional TKA (convTKA) was implanted. Perioperative and postoperative management were identical. Radio- graphic evaluation, ROM, KSS (Knee society score) and WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) were performed and patients satisfaction was evaluated after 3 and 12 months. Groups were comparable for age, sex, body mass index and extension/flexion. After 92 days average flexion in the convTKA group was significantly higher (119 vs. 113 degrees; unpaired t-test). At 375 days, mean flexion in both groups was 120 degrees. There was a significant higher number of outliers of neutral mechanical axis for convTKA patients (11 vs. 3; Chi-squared test). After 92 days there was no difference for KSS (convTKA: 160, custTKA: 167) but significant better results for WOMAC (19 vs. 40) in the custTKA group (unpaired t-test, p= 0.02). In addition, significantly better KSS (181 vs. 156) and WOMAC (99 vs. 42) were found for the custTKA group at 375 days (unpaired t-test, p= 0.002 and 0.001). Patients with the custTKA implant reported significant higher fulfillment of their expectations regarding function and knee strength. In the present study, the patients with a custTKA implant showed significantly superior short-term clinical results and fulfillment of their expectations regarding knee function.

[Psychoeducation in knee arthroplasty patients : Additional pain management]. / Psychoedukation bei Patienten mit Knieendoprothese : Erweitertes Schmerzmanagement.

Approximately 20-30% of patients remain dissatisfied with their treatment outcome after primary knee arthroplasty. Particularly frequent pain with limited flexibility contrives to reduce the quality of life of affected patients. Psychotherapeutic methods for pain processing after knee arthroplasty have hardly been investigated to date. The current study is dedicated to researching the effect of pain psychoeducation on treatment outcome after primary knee arthroplasty in the sense of additional pain management.

Multiple asystole events in a patient undergoing total knee arthroplasty - a case report.

BACKGROUND: Unexpected cardiac arrest in patients during surgery is associated with high mortality. Reasons are often multifactorial and unclear. CASE PRESENTATION: This case report describes a patient who developed reversible asystole during knee surgery under general anaesthesia. All diagnostic cardiac examinations were unremarkable. After surgery, the patient showed no further symptoms. CONCLUSION: To prevent cardiac arrest due to non-cardiac reasons, patients with a high risk for asystole caused by vasovagal reflex or by pain need to be identified. Preoperative conditions such as hypovolemia need to be improved prior to surgery, and additional monitoring should be used. Further investigations to determine the influence of non-cardiac disease and long-term medication are necessary.

Comparative Results of Percutaneous Calcaneal Osteotomy in Correction of Hindfoot Deformities.

BACKGROUND:: Calcaneal osteotomies are often required in the correction of hindfoot deformities. The traditional open techniques, which include a lateral or oblique incision, are occasionally associated with wound healing problems and neurovascular injury. METHODS:: A total of 122 consecutive patients who underwent a calcaneal osteotomy for hindfoot realignment treatment were included. Fifty-eight patients were operated using an open incision technique and 64 patients (66 feet) using a percutaneous technique. Clinical and radiologic assessments were performed preoperatively, at 6 weeks, and 1 year postoperatively. RESULTS:: The American Orthopaedic Foot & Ankle Society scale scores and visual analog scale pain scores improved in both groups postoperatively. The difference between the groups was not significant. The results of the radiologic measurements pre- and postoperatively were not significantly different. No pseudarthrosis occurred in either group. The comparison of both groups showed a significantly lower risk for wound healing problems in the percutaneous group. The hospitalization time was significantly shorter in the percutaneous group. CONCLUSION:: Because of the excellent results with the percutaneous calcaneal osteotomy, the authors feel encouraged to establish this procedure as a standard technique for calcaneus osteotomy, especially patients at high risk for wound healing problems. LEVEL OF EVIDENCE:: Level III, comparative series.

Impact of the body mass index on perioperative immunological disturbances in patients with hip and knee arthroplasty.

BACKGROUND: Obesity increases the risk for knee and hip joint implantation and negatively contributes to wound healing. In this study, in 52 patients undergoing hip and knee arthroplasty the amount of peripheral immune effector cells pre- and post-operative, as well as the expression of certain soluble factors affecting the functions of immune effector cells were investigated. METHODS: The peripheral immune cells and the expression of the soluble factors were determined by flow cytometry and correlated to each other in dependency of the BMI, the sex, and the kind of arthroplasty. RESULTS: The pre-operative amounts of peripheral NK cells and cytotoxic T cells significantly decreased with increasing BMI. Furthermore, the expression of the immunomodulatory adipokine leptin nicely correlated to the BMI. These effects were stronger in males than in females. Furthermore, the correlation of the activation marker sTNF-R and peripheral T cells strongly decreased with increasing BMI. While IL-6, CD40L, and MPO were significantly induced after surgery, there were no correlations to the BMI. CONCLUSIONS: The known wound-healing problems in obese patients and the osteoarthritis per se can be linked to the BMI. While obese patients exerted reduced peripheral NK cells and cytotoxic T cells (CTLs), IL-6 showed no involvement. However, the adipokine leptin strongly increased with the BMI strengthening its role as immunomodulatory molecule negatively interfering the functions of immune effector cells.

A prospective randomized radiographic and dual-energy X-ray absorptiometric study of migration and bone remodeling after implantation of two modern short-stemmed femoral prostheses.

BACKGROUND: The aim of this prospective randomized study was to analyze migration and strain transmission of the Metha™ and Nanos™ femoral prostheses. MATERIALS AND METHODS: Between 1 January 2011 and 2 April 2013, 50 patients were randomized to receive short-stemmed femoral prostheses. Metha™ stems were implanted in 24 patients (12 female, 12 male; mean age 58.7 years; mean body mass index [BMI] 27.4) and Nanos™ stems in 26 patients (10 female, 16 male; mean age 59.7 years; mean BMI 27.1). Longitudinal stem migration, varus-valgus alignment, changes of center of rotation (COR), femoral offset and caput-collum-diaphyseal angle, leg length discrepancy, periprosthetic radiolucent lines incidence, and dual-energy X-ray absorptiometry (DEXA) scans were analysed after an average of 98 and 381 days. RESULTS: There was no significant change of varus-valgus alignment or clinically relevant migration of the Metha™ or Nanos™ prostheses during postoperative follow-up. After 12.3 months, the DEXA scans showed small but significant differences of bone mineral density in Gruen zones 1 (minus ~8 %) and 6 (plus ~9 %) for the Metha™ and in Gruen zone 1 (minus ~14 %) for the Nanos™ (paired t test). Visual analog scale (VAS) and Harris Hip Score (HHS) improved significantly for both implants (Nanos™/Metha™ 12.3 months postoperatively HSS 96.5/96.2; VAS 0.7/0.8, respectively). COR or offset did not change significantly after surgery. CONCLUSIONS: Neither implant showed signs of impaired osseointegration. DEXA demonstrated proximally located load transfer with only moderate proximal stress shielding. LEVEL OF EVIDENCE: II.

Use of hyaluronidase for pharmacokinetic increase in bioavailability of intracutaneously applied substances.

Endogenous hyaluronidases in the human body have physiological and pathophysiological significance due to their enzymatic activity during the cleavage of hyaluronan. The potential of therapeutic use of testicular and recombinant hyaluronidase has been increasingly acknowledged and developed in recent years. Most relevant in practice is the co-application of hyaluronidase and other active substances in order to enhance their bioavailability within the tissue.

Articular cartilage chondrocytes express aromatase and use enzymes involved in estrogen metabolism.

INTRODUCTION: Sex hormones, especially estrogens, have been implicated in articular cartilage metabolism and the pathogenesis of postmenopausal osteoarthritis. The conversion by aromatase (CYP19A1) of androstenedione into estrone (E1) and of testosterone into 17ß-estradiol (E2) plays a key role in the endogenous synthesis of estrogens in tissue. METHODS: We analyzed the expression of aromatase (CYP19A1) in immortalized C-28/I2 and T/C-28a2 chondrocytes, as well as in cultured primary human articular chondrocytes and human articular cartilage tissue, by means of RT-PCR, Western blotting and immunohistochemistry. By means of quantitative RT-PCR and enzyme-linked immunosorbent assay, we also determined whether the aromatase inhibitor letrozole influences estrogen metabolism of cultured chondrocytes in immortalized C-28/I2 chondrocytes. RESULTS: Aromatase mRNA was detected in both immortalized chondrocyte cell lines, in cultured primary human chondrocytes, and in human articular cartilage tissue. By means of Western blot analysis, aromatase was detected at the protein level in articular cartilage taken from various patients of both sexes and different ages. Cultured primary human articular chondrocytes, C-28/I2 and T/C-28a2, and human articular cartilage tissue reacted with antibodies for aromatase. Incubation of C-28/I2 chondrocytes with 10⁻¹¹ M to 10⁻7M letrozole as an aromatase inhibitor revealed significantly increased amounts of the mRNAs of the enzyme cytochrome P4501A1 (CYP1A1), which is involved in the catagen estrogen metabolism, and of the estrogen receptors ER-α and ER-ß. Concomitantly, synthesis of estrone (E1) was significantly downregulated after incubation with letrozole. CONCLUSIONS: We demonstrate that human articular cartilage expresses aromatase at the mRNA and protein levels. Blocking of estrone synthesis by the aromatase inhibitor letrozole is counteracted by an increase in ER-α and ER-ß. In addition, CYP1A1, an enzyme involved in catabolic estrogen metabolism, is upregulated. This suggests that articular chondrocytes use ERs functionally. The role of endogenous synthesized estrogens in articular cartilage health remains to be elucidated.

High flex total knee arthroplasty--a prospective, randomized study with results after 10 years.

This prospective randomized study compares the long term results between total knee arthroplasty with a mobile bearing high flex and a fixed bearing posterior stabilized knee (LPS) in 39 patients. The Hospital for Special Surgery score (HSS) was calculated and radiographs in AP and lateral view were analyzed after a minimum follow-up of 10 years. No significant differences between the two groups were found. The mean HSS-score was 90.67 (+/- 5.75) for LPS group patients and 90.83 (+/- 8.57) points for the high flex group patients. Three patients in the high flex group had undergone a reoperation on their knee. One knee was revised for painful mid-flexion instability and the others for symptomatic aseptic loosening of the tibial prosthesis. Based on these and other findings, the use of a high flex knee system may be seriously re-considered. Further studies are required to evaluate possible long-term adverse effects of high flex knee systems.

Calcaneocuboid distraction arthrodesis with allogenic bone grafting for correction of pes planovalgus.

Calcaneocuboid distraction arthrodesis is regarded as an excellent and reliable surgical procedure for correction of pes planovalgus. Despite a potentially high complication rate, the use of an autologous iliac crest graft is regarded as the method of choice. In a prospective trial the results in 12 feet after calcaneocuboid distraction arthrodesis for pes planovalgus correction with allogenic bone graft were investigated. The mean age was 64 (52-81) years. An angle-stable plate was generally used for fixation of the arthrodesis. Successful bone healing was diagnosed clinically if local pain was absent during weight bearing, forefoot manipulation and palpation. The AOFAS score improved from 58.9 (+/- 6) points preoperatively to 89.8 (+/- 6.3) points 12 months postoperatively and the Visual Analogue Pain Scale (VAS) from 5.1 (+/- 1.4) to 0.7 (+/- 1) 12 months postoperatively. On radiological analysis, the lateral and dorsoplantar talometatarsal axis, hindfoot axis, the navicular floor distance and talonavicular coverage angle improved considerably. Bone fusion was observed in 11 of 12 cases postoperatively. In conclusion, the use of an allogenic graft for calcaneocuboid distraction arthrodesis did not result in a higher pseudarthrosis rate compared with results reported after use of an autologous iliac crest graft. Fixation with an angle-stable plate is recommended.

A prospective dual-energy X-ray absorptiometry study of bone remodeling after implantation of the Nanos short-stemmed prosthesis.

The aim of this study was to analyze the bone remodeling around the Nanos stem (Smith & Nephew, Marl, Germany) after primary total hip arthroplasty for coxarthrosis. In 25 patients (15 male, 10 female, mean age 59.9 years) with the diagnosis of coxarthrosis, a DEXA scan was performed immediately after surgery, 97 days (SD 6.1 days) and 368 days (SD 6.2 days) after implantation of a Nanos prosthesis. Plain radiographs were analyzed digitally for radiolucent lines, varus-valgus femoral stem alignment, measurement of stem migration and changes in varus-valgus femoral stem alignment. The position of the center of rotation (COR) and the offset were assessed pre- and postoperatively. Harris Hip Score was used to evaluate the clinical outcome. The DEXA scan showed a significant and relevant increase in BMD (Bone Mineral Density) in Gruen-Zone 6 (12%) and a decrease in Zone 1 (15%), 2 (5%) and 7 (12%), which was interpreted as reflecting a distal load transfer in the metaphysis of the femur. There was no clinically relevant migration or tilting of the Nanos stem. Radiolucent lines were noted in 12 cases, mainly at the polished tip area of the prosthesis; this was not regarded as a sign of impaired osseointegration. There was no significant difference between the position of the COR and the pre- and postoperative offset. The absence of stem migration, angulation, or relevant radiolucent lines is seen as evidence for an unimpaired osseointegration of the Nanos stem approximately 12 months after implantation. It is concluded that the Nanos prosthesis can reduce loss of BMD of the proximal femur composed with conventional stems or other short-stemmed implants.

Subsidence in two uncemented femoral stems: an in vitro study.

Many aspects of the performance of different implant designs remain as open questions in total hip arthroplasty. Despite the increased survivorship of each hip replacement, the amount of bone removed during surgery remains an important factor because of the potential need for revision surgery. Given that a smaller implant will have less surface area over which to transfer load, constructs that preserve more bone stock may be susceptible to mechanical complications related to the fixation of the implant in the femur. To assess mechanical fixation, this study compared the fiber metal taper and Mayo conservative hip stems in subsidence, frontal plane rotation and failure load. After dual-energy x-ray absorptiometry scans, pairs of cadaveric femurs received implants of each type and were loaded for 10,000 cycles. The subsidence and rotation were measured. Finally, specimens were loaded to failure. The subsidence and rotation after cyclic loading were -0.73 mm and 0.1°, respectively, for the Mayo implants and -0.87 and 0.52°, respectively, for the fiber metal taper implants, but no significant differences between implant types were found. There was also no significant relationship to bone mineral density. A power analysis revealed that 914 specimens would have been required to achieve a power of 0.8.

Comparison of noncross-linked and cross-linked hyaluronic acid with regard to efficacy of the proliferative activity of cutaneous fibroblasts and keratinocytes in vitro.

BACKGROUND: Intradermal application of hyaluronic acid (HA) in varying chain length and cross-linking density is used routinely for hydrodynamic volume replacement of the extracellular matrix to reduce the clinical effects of aging. OBJECTIVES: In vitro data show that via receptors of the hyaladherin group hyaluronic acid has additionally direct or indirect effects on cells. In the case of native noncross-linked HA, it has been proved that the proliferative and metabolic activity of cutaneous fibroblasts can be increased. The aim of this study was to investigate whether these effects can be proved also for cross-linked HA and how these effects can be quantified for different preparations. MATERIALS AND METHODS: The effect on proliferative activity in cultures of native cutaneous fibroblasts and keratinocytes was investigated for noncross-linked HA, for noncross-linked HA with added glycerol, for HA that was stabilized in the carboxyl and hydroxyl groups per inner esterification, and for HA that was chemically cross-linked by 1,4-butanediol-diglycidylether, mixed in small particles in a biphasic compound with native HA, each in different concentrations (0.1, 1.0 and 10.0 mg/mL). RESULTS: HA that was stabilized in the carboxyl and hydroxyl groups per inner esterification induces the strongest proliferative effect on both cell types. Native noncross-linked HA and chemically cross-linked HA show a rather modest proliferative effect and on fibroblasts only, whereas noncross-linked HA with added glycerol in high concentrations provokes a rather antiproliferative effect. CONCLUSIONS: The data show that HA does induce direct effects on cells depending on type and density of the cross-linkage. The practical relevance in terms of a metabolic filler effect needs to be verified in clinical studies.