Incidence of and risk factors for femoral fractures in the gap between hip and knee implants.

PURPOSE: The purpose of this study was to analyse the incidence of interprosthetic femoral fractures and describe risk factors for them. METHODS: Between 2009 and 2015, we selected patients who were carrying two implants (hip and knee) in the same femur. We collected demographic and clinical data and performed a radiological evaluation to analyse the gap between implants-the femoral canal area and total femoral area-in the axial plane. We defined interprosthetic fracture as that corresponding to a Vancouver type C fracture and types 1 and 2 according to the Su classification. RESULTS: We studied 68 patients who had total knee arthroplasty (TKA), and 44 patients who had total hip arthroplasty (THA); 24 patients an intramedullary nail. We found six interprosthetic fractures (8.8 %), all in patients with a non-cemented THA. There was a tendency towards statistical difference (p = 0.08). Patients with an additional implant at the proximal femur were statistically less likely to have an interprosthetic fracture (p = 0.04). In radiological results, we found more interprosthetic fractures in patients who had an increased femoral canal area in the axial plane just distal to the tip of the hip implant. CONCLUSIONS: Identifying risk factors for this specific type of fracture may facilitate their prevention. Better implant stability and the presence of a gap between stems in a lower canal zone appear to hinder the occurrence of interprosthetic fractures.

Signature of microRNA expression during osteogenic differentiation of bone marrow MSCs reveals a putative role of miR-335-5p in osteoarthritis.

BACKGROUND: The aim of this study was to evaluate, the existence of a signature of differentially expressed microRNAs (miRNAs) during osteogenic differentiation of bone marrow MSCs from OA and healthy donors and to describe their possible implication in joint regeneration through modulation of molecular mechanisms involved in homeostatic control in OA pathophysiology. METHODS: Following phenotypic assessment of BM-MSCs obtained from OA diagnosed patients (n = 10) and non-OA (n = 10), total small RNA was isolated after osteogenic induction for 1, 10 and 21 days, miRNA profiles were generated using a commercial expression array of 754 well-characterized miRNAs. MiRNAs, with consistent differential expression were selected for further validation by quantitative reverse-transcription polymerase chain reaction (qRT-PCR) analysis. RESULTS: A total of 246 miRNAs were differentially expressed (fold change ≥ ± 2, P ≤0.05) between OA and non-OA BM-MSC samples; these miRNAs showed variable interactions depending on the cell and differentiation status. Two miRNAs, hsa-miR-210 and hsa-miR-335-5p out of 21 used for validation showed a significant downregulated expression during induced osteogenesis. In particular hsa-miR-335-5p, a critical regulator in bone homeostasis, was further studied. hsa-miR-335-5p downregulation in OA-MSCs, as well as their host coding gene, MEST, were also assessed. CONCLUSIONS: To our knowledge, this study represents the most comprehensive assessment to date of miRNA expression profiling in BM-MSCs from OA patients and their role during osteogenic differentiation. We describe the existence of a correlation between miR-335-5p expression and OA indicating the putative role of this miRNA in OA features. These findings, may contribute to our understanding of the molecular mechanisms involved in MSCs mediated homeostatic control in OA pathophysiology that could be applicable in future therapeutic approaches.

Primary modular total knee replacement in severe and unstable osteoarthritis. Predictive factors for failure.

PURPOSE: Severe cases of osteoarthritis with ligamentous instability require the use of a modular knee arthoplasty. To assess the survival, the complications, the clinical, radiological and functional outcomes, and the quality of life of those patients in whom a Optetrak Condylar Constrained Knee (CCK) had been implanted as a primary implant. To study how the pre-operative conditions (deformity, age, sex …) and the characteristics of the arthroplasty (stems, supplements, constrained component …) could change the survival or the clinical outcomes of the implants. METHODS: We performed an observational retrospective study of 105 CCKs implanted between 1999 and 2005. The mean follow-up was nine years (7, 13). Mean age was 70.5 years. The mortality was 6.9 %. There were 9.3 % of the patients lost during the follow-up. We studied all the medical files of the patients in order to assess the pre-operative, surgical and postoperative conditions. We used the Knee Society Score (KSS), both clinical and functional, to study the functional and clinical situation. We analysed the X-ray using the Knee Society roentgenographic evaluation. The quality of life was studied using the Oxford Knee Score (OKS). Then in order to find predictor conditions, we made statistical multivariable predictive studies attending to the preoperative factors and to the arthroplasty conditions to compare both outcomes and survival (Kaplan-Meier groups curves and Cox Multivariable Models [hazard ratio]). Processing and data analysis was performed using SPSS 15.0. RESULTS: The outcomes did not show differences between all the groups. While the mean result of the clinical KSS was 75.8, the mean functional KSS was 73.1. We did not find a condition associated with worst results of the knees (p > 0.05). The KSS obtained was excellent or good in 74.9 %. The global survival at 24 months was 93.8 % and at 96 months was 90.1 %. There were some conditions associated with poorest survival of the arthroplasties: patients younger than 70 years old, tibial tuberosity osteotomy, use of long stems and new surgery two months after arthoplasty (p < 0.05). The 11.1 % of the arthroplasties required more surgeries (3.3 % were soft tissue surgeries and 7.8 % were revisions). The mean OKS obtained was 34.78. Satisfaction was obtained by 86.2 % of the patients. CONCLUSIONS: All severe and unstable knees obtained similar and overall excellent-good outcomes and survival using the Optetrak CCK. Although we found that there are some factors that could change the survival of the total knee replacement, these did not change the outcomes.

Predictive factors for failure after total knee replacement revision.

PURPOSE: We used the Optetrak Condylar Constrained (CCK) implant, a modular and constrained knee implant as replacement for a failed primary arthroplasty, to assess the survivorship, the complications, the clinical, radiological, and functional situation, and the quality of life of those patients in whom a CCK had been implanted in recent years in order to find predictive pre-operative conditions of survival and clinical outcomes. METHODS: We performed a retrospective study of 125 CCK implanted between 1999 and 2005. The mean follow-up was nine years (range, seven to 13). Mean age was 73.6 years. A total of 78% of the revised TKA were cemented and 66% were CR. We assessed the pre-operative, the operative and the postoperative conditions studying the medical files of all the patients. In order to study the functional and clinical situation we used the Hospital for Special Surgery (HSS) score and the Knee Society score (KSS), both clinical and functional. We analysed all the X-rays using the Knee Society Roentgenographic evaluation. The quality of life was studied using the Oxford knee score (OKS). RESULTS: The mean results of the KSS clinical and the KSS functional were 68.24 and 63.85, respectively. There were not any conditions associated with poor results of the knees (p > 0.05). The global survival at 24 months was 92.7%, at 60 months 87.8% and at 96 months it was 87.8%. There were some conditions associated with poor survival of the knees, e.g. patients were younger than 70 years old, rheumatic diseases, kidney faliure, tibial tuberosity osteotomy, PS primary arthroplasty, revision before five years and septic loosening. CONCLUSIONS: Based on these results there are some pre-operative factors that change the survival of the total knee replacement revision.

Cerclage wire fixation of trochanteric osteotomies in complex hip revision: our experience and comparison with cable-plate fixation.

INTRODUCTION: Osteotomy of the greater trochanter is a commonly used procedure in complex revision hip arthroplasty in order to achieve a wide exposure to the femoral stem and acetabular components. There is no clinical evidence in favour of a specific fixation method. The aim of this study was to compare cable-plate with figure-of-eight cerclage wire fixation in patients requiring a trochanteric "slide" osteotomy. MATERIAL AND METHODS: In a retrospective study, 51 greater trochanteric "slide" osteotomies in complex acetabular revision arthroplasties were included. Patients were divided into 2 groups: 28 hips were fixed with 1 of 2 cable-plate systems (Dall-Miles staple, Stryker or Cable-Ready plate, Zimmer) and 23 with a figure-of-eight cerclage wire.Consolidation, osteolysis, migration of greater trochanter, bursitis of the trochanteric area, Trendelenburg gait and removal of osteosynthesis material were studied at 6 months follow-up. RESULTS: Both groups showed good union rates. The lysis rate was similar with 32% in the cable-plate group versus 29% in the cerclage wire group (p = 0.084). 43% of the hips with cable-plate and 22% of the cerclage wire had trochanteric migration (p = 0.297). Pain at the greater trochanter was less frequent in the cerclage wire group (9%) as compared to the cable-plate group (43%) (p = 0.007). Implant removal was more frequent in the cable-plate group (4 vs. 0 patients). Trendelenburg gait was found in 3 patients in the cerclage wire group as compared to 10 in the cable-plate group (p = 0.054). CONCLUSIONS: The cerclage wiring had superior clinical outcomes with similar radiographic results. The authors recommend the use of figure-of-eight cerclage wire when fixing a greater trochanteric "slide" osteotomy in complex revision hip arthroplasty.

Influence of Mesenchymal Stem Cell Sources on Their Regenerative Capacities on Different Surfaces.

Current gold-standard strategies for bone regeneration do not achieve the optimal recovery of bone biomechanical properties. To bypass these limitations, tissue engineering techniques based on hybrid materials made up of osteoprogenitor cells-such as mesenchymal stem cells (MSCs)-and bioactive ceramic scaffolds-such as calcium phosphate-based (CaPs) bioceramics-seem promising. The biological properties of MSCs are influenced by the tissue source. This study aims to define the optimal MSC source and construct (i.e., the MSC-CaP combination) for clinical application in bone regeneration. A previous iTRAQ analysis generated the hypothesis that anatomical proximity to bone has a direct effect on MSC phenotype. MSCs were isolated from adipose tissue, bone marrow, and dental pulp, then cultured both on a plastic surface and on CaPs (hydroxyapatite and ß-tricalcium phosphate), to compare their biological features. On plastic, MSCs isolated from dental pulp (DPSCs) presented the highest proliferation capacity and the greatest osteogenic potential. On both CaPs, DPSCs demonstrated the greatest capacity to colonise the bioceramics. Furthermore, the results demonstrated a trend that DPSCs had the most robust increase in ALP activity. Regarding CaPs, ß-tricalcium phosphate obtained the best viability results, while hydroxyapatite had the highest ALP activity values. Therefore, we propose DPSCs as suitable MSCs for cell-based bone regeneration strategies.

Differential Expression of HOX Genes in Mesenchymal Stem Cells from Osteoarthritic Patients Is Independent of Their Promoter Methylation.

Skeletogenesis, remodeling, and maintenance in adult tissues are regulated by sequential activation of genes coding for specific transcription factors. The conserved Homeobox genes (HOX, in humans) are involved in several skeletal pathologies. Osteoarthritis (OA) is characterized by homeostatic alterations of cartilage and bone synthesis, resulting in cartilage destruction and increased bone formation. We postulate that alterations in HOX expression in Mesenchymal Stem cells (MSCs) are likely one of the causes explaining the homeostatic alterations in OA and that this altered expression could be the result of epigenetic regulation. The expression of HOX genes in osteoarthritic-derived MSCs was screened using PCR arrays. Epigenetic regulation of HOX was analyzed measuring the degree of DNA methylation in their promoters. We demonstrate the downregulated expression of HOXA9 and HOXC8 in OA-MSCs. However, their expression does not correlate with promoter methylation status, suggesting that other epigenetic mechanisms could be implicated in the regulation of HOX expression. Studies on the role of these genes under active differentiation conditions need to be addressed for a better knowledge of the mechanisms regulating the expression of HOX, to allow a better understanding of OA pathology and to define possible biomarkers for therapeutic treatment.

Reconstruction of bone defects with impacted allograft in femoral stem revision surgery.

A retrospective clinical review was done on 54 revision hip patients. Radiological analysis examined the Gross and AAOS classifications, stem position, cement mantles, allograft and evolution (subsidence, resorption and remodelling). The Harris Hip score was used for clinical assessment. We used bone bank allograft and a polished non-collared stem LD. The follow-up period was 60.5 months (19.4-152.4), and the average age 68.5 (range: 22-85). There were 21 females and 33 males. The surgical approach was: lateral (5.56%) posterior (91.4%); trochanteric osteotomy: 25.9%; associated acetabular revision: 59.3%; previous operations: 1.9. The preoperative Harris score was 35 (28-40) and rose to 81 (50-99) postoperatively. The stem alignment was neutral (44.44%), varus (38.89%) and valgus (16.67%). The femur/stem diameter relationship was 1.8 (1.2-2.7). There were no changes in stem alignment in 94.4%. An adequate cement mantle was: proximal zone (61.1%), medium zone (27.8%) and distal zone (16.7%). The rate of any subsidence was 38.9% (progressive: 12.96%). The rate of complications was 40.7% and included periprosthetic fracture: 14.8%; superficial infection: 1.9%; deep late infection: 1.9%; dislocation: 3.7%; heterotopic ossification: 13%. The rate of new stem revision was 16.6%. The clinical and radiological success rate was 77.78%. A greater incidence of revisions has been found in stem malalignment, progressive subsidence, a Harris increase of <20 points, allograft resorption, small diameter stems and inadequate cement mantle. We recommend hard impaction and a cement mantle of at least 2 mm. Non-progressive subsidence does not increase stem loosening. The technique has been useful in recovering bone stock in a severely defective femur and achieves a stable reconstruction. The level of evidence was therapeutic study level III-2 (retrospective cohort study; see the instructions to the authors for a complete description of the levels of evidence).