The relationship between bone strain index, bone mass, microarchitecture and mechanical behavior in human vertebrae: an ex vivo study

The aim of this study was to determine whether the Bone Strain Index (BSI), a recent DXA-based bone index, is related to bone mechanical behavior, microarchitecture and finally, to determine whether BSI improves the prediction of bone strength and the predictive role of BMD in clinical practice.

PURPOSE

Bone Strain Index (BSI) is a new DXA-based bone index that represents the finite element analysis of the bone deformation under load. The current study aimed to assess whether the BSI is associated with 3D microarchitecture and the mechanical behavior of human lumbar vertebrae.

METHODS

Lumbar vertebrae (L3) were harvested fresh from 31 human donors. The anteroposterior BMC (g) and aBMD (g/cm2) of the vertebral body were measured using DXA, and then the BSI was automatically derived. The trabecular bone volume (Tb.BV/TV), trabecular thickness (Tb.Th), degree of anisotropy (DA), and structure model index (SMI) were measured using µCT with a 35-µm isotropic voxel size. Quasi-static uniaxial compressive testing was performed on L3 vertebral bodies under displacement control to assess failure load and stiffness.

RESULTS

The BSI was significantly correlated with failure load and stiffness (r = -0.60 and -0.59; p < 0.0001), aBMD and BMC (r = -0.93 and -0.86; p < 0.0001); Tb.BV/TV and SMI (r = -0.58 and 0.51; p = 0.001 and 0.004 respectively). After adjustment for aBMD, the association between BSI and stiffness, BSI and SMI remained significant (r = -0.51; p = 0.004 and r = -0.39; p = 0.03 respectively, partial correlations) and the relation between BSI and failure load was close to significance (r = -0.35; p = 0.06).

CONCLUSION

The BSI was significantly correlated with the microarchitecture and mechanical behavior of L3 vertebrae, and these associations remained statistically significant regardless of aBMD.

The use of dual mobility cups in revision total hip arthroplasty for failed large head metal-on-metal bearings

PURPOSE

Revision of failed large head metal-on-metal (MoM) total hip arthroplasty (THA) is a challenging procedure particularly to reconstruct acetabular bone defect due to osteolysis and to achieve hip stability due to soft tissue damages, both potentially caused by adverse reaction to metal debris (ARMD). This study aimed to evaluate the outcome of dual mobility cup (DMC) constructs in revision THA for failed large head MoM bearings with a special attention to the occurrence of dislocation or re-revision.

METHODS

Between 2015 and 2019, 57 patients (64 THAs, 41 men, mean age = 65 ± 10 years) underwent revision for MoM THA with the use of DMC were prospectively included in our total joint registry. Mean time to revision was 11 ± 2.5 years. The causes for revision were adverse reaction to metal debris (ARMD) in 49 THAs (76%), painful hip with elevated blood cobalt-chromium ions in seven (11%), and acetabular aseptic loosening in eight (13%). The revision was complete in 22 THAs (34%) and acetabular only in 42 (66%). Clinical and radiographic outcomes, complications, and re-revisions were evaluated at most recent follow-up.

RESULTS

At mean follow-up of six ± 1.5 years, the pre- to postoperative Harris Hip Score improved from 74 ± 19 to 92 ± 4 (p = 0.004). Complications occurred in 11 cases (17%): five dislocations (8%), three periprosthetic infections (5%), two aseptic loosening of the acetabular component (3%), and two periprosthetic fractures (3%). Re-revision was required in six cases (9%).

CONCLUSION

The use of DMC is a reliable option to prevent instability and ensure a stable acetabular reconstruction in revision THA for failed large head MoM bearings. However, dislocation after revision remains a concern, particularly in cases of severe soft tissue damage related to ARMD.

Inhibiting Lysyl Oxidases prevents pathologic cartilage calcification

Lysyl oxidases (LOX(L)) are enzymes that catalyze the formation of cross-links in collagen and elastin fibers during physiologic calcification of bone. However, it remains unknown whether they may promote pathologic calcification of articular cartilage, an important hallmark of debilitating arthropathies. Here, we have studied the possible roles of LOX(L) in cartilage calcification, related and not related to their cross-linking activity. We first demonstrated that inhibition of LOX(L) by β-aminoproprionitrile (BAPN) significantly reduced calcification in murine and human chondrocytes, and in joint of meniscectomized mice. These BAPN's effects on calcification were accounted for by different LOX(L) roles. Firstly, reduced LOX(L)-mediated extracellular matrix cross-links downregulated Anx5, Pit1 and Pit2 calcification genes. Secondly, BAPN reduced collagen fibrotic markers Col1 and Col3. Additionally, LOX(L) inhibition blocked chondrocytes hypertrophic differentiation (Runx2 and COL10), pro-inflammatory IL-6 release and reactive oxygen species (ROS) production, all triggers of chondrocyte calcification. Through unbiased transcriptomic analysis we confirmed a positive correlation between LOX(L) genes and genes for calcification, hypertrophy and extracellular matrix catabolism. This association was conserved throughout species (mouse, human) and tissues that can undergo pathologic calcification (kidney, arteries, skin). Overall, LOX(L) play a critical role in the process of chondrocyte calcification and may be therapeutic targets to treat cartilage calcification in arthropathies.

A new ex vivo human model of osteoarthritis cartilage calcification

OBJECTIVE

Cartilage pathologic calcification is a hallmark of osteoarthritis (OA). Here, we aimed to describe a new ex vivo human model to study the progression of cartilage calcification.

METHOD

Cartilage explants (n = 11), as well as primary chondrocytes (n = 3), were obtained from OA patients undergoing knee replacement. Explants and chondrocytes were cultured in control (NT) or calcification (CM) medium (supplemented with ascorbic acid and β-glycerophosphate). Calcification was evaluated by micro-CT scan at day 0 and 21 in explants, and by Alizarin red staining in chondrocyte monolayers. Raman spectrometry allowed characterization of the crystal type. Interleukin-6 (IL-6) secretion in explant and cell supernatants was measured by ELISA. Finally, matrix degradation was evaluated by Safranin-O staining of explant sections and by glycosaminoglycans (GAG) release in supernatants.

RESULTS

Micro-CT scan showed calcifications in all explants at baseline (day 0), which in the CM group increased significantly in number and size after 21 days compared with the NT group. Raman spectrometry revealed that crystals were exclusively basic calcium phosphate crystals (carbonated hydroxyapatite) both in NT and CM. IL-6 secretion was significantly increased in calcifying conditions. Finally, CM significantly increased cartilage catabolism as assessed by decreased Safranin-O staining of tissue explants and increased GAG release in supernatants. CM effects (enhanced calcification, IL-6 secretion and proteoglycans turn-over) were recapitulated in vitro in OA chondrocytes.

CONCLUSIONS

We have described a new ex vivo human model of cartilage calcification that can summurize the triad of events seen during osteoarthritis progression, i.e. calcification, inflammation, and cartilage degradation. This model will allow the identification of new anti-calcification compounds.

Elevated secretion of pro-collagen I-alpha and vascular endothelial growth factor as biomarkers of acetabular labrum degeneration and calcification in hip osteoarthritis: An explant study

Background

Hip osteoarthritis (OA) involves structural degeneration of different joint compartments, including femoral head cartilage, periarticular ligaments and the acetabular labrum. However, the molecular mechanisms underlying labrum degeneration in hip OA remain poorly understood.

Aim

To assess secretion of putative biomarkers for OA from explanted human labrum tissues under basal and inflammatory conditions and to determine whether these could differentiate between OA and calcification status compared to fracture controls.

Methods

Intact labrum specimens were collected from patients undergoing joint arthroplasty for primary hip OA (n ​= ​15, mean age 70) or non-OA femoral neck fracture (n ​= ​5, mean age 64). Tissues were dissected in equal-sized samples and explanted for one week. To mimic activation of inflammatory signaling by endogenous damage-associated molecular patterns (DAMP) tissue were stimulated with a toll-like receptor 4 (TLR4) agonist (1 ​μg/mL LPS). The involvement of transforming growth factor-beta (TGF-beta) signaling was evaluated by treatment with a TGF-beta type 1 receptor inhibitor (10 ​μM SB-505124). Secretion of aggrecan (ACAN), pro-collagen-I alpha (Pro-Col-Iα), cartilage oligomeric matrix protein (COMP), interleukin-6 (IL-6) and vascular endothelial growth factor (VEGF) was assessed by enzyme-linked immunosorbent assay (ELISA). Labrum calcification was evaluated by 3D whole mount fluorescent microscopy of ethyl cinnamate-based optically cleared tissues stained with Alcian blue/Alizarin red.

Results

Whole mount microscopy revealed non-OA fracture controls were non-calcified, whereas six OA labra (40%) were partially calcified or ossified. Basal secretion of Pro-Col-Iα and VEGF was increased four-fold in OA versus non-OA labra. Pro-Col-Iα levels were correlated with those of VEGF (r ​= ​0.65) and COMP (r ​= ​0.54). Stimulation of DAMP signaling through TLR4 affected secretion of IL-6, VEGF, COMP and Pro-Col-Iα, with distinct responses between non-OA and OA tissues. Inhibition of TGF-beta signaling specifically reduced elevated secretion of Pro-Col- Iα and VEGF in calcified OA labrum.

Conclusions

Secretion of the putative OA biomarkers Pro-Col-Iα and VEGF is elevated in degenerated human acetabular labrum and may serve as indicators of OA and calcification status. Secretion of both factors was partially regulated by TGF-beta signaling in calcified OA labrum tissues.The Translational potential of this article:Our findings suggest that a biomarker panel consisting of Pro-Col-Iα/VEGF/COMP may be valuable for assessing subradiographic labrum degeneration and calcification in hip OA. Targeting TGF-beta signaling may offer a means to reduce vascular invasion and fibrosis in acetabular labrum tissue.

Analgesic efficacy of selective tibial nerve block versus partial local infiltration analgesia for posterior pain after total knee arthroplasty: a randomized, controlled, triple-blinded trial

BACKGROUND

The adductor canal block provides pain relief on the anterior aspect of the knee after arthroplasty. Pain on the posterior aspect may be treated either by partial local infiltration analgesia of the posterior capsule or by a tibial nerve block. This randomized, controlled, triple-blinded trial tests the hypothesis that a tibial nerve block would provide superior analgesia compared to posterior capsule infiltration in patients scheduled for total knee arthroplasty under spinal anesthesia with an adductor canal block.

METHODS

Sixty patients were randomized to receive either infiltration of the posterior capsule by the surgeon with ropivacaine 0.2%, 25 mL, or a tibial nerve block with 10 mL of ropivacaine 0.5%. Sham injections were performed to guarantee proper blinding. The primary outcome was intravenous morphine consumption at 24 h. Secondary outcomes included intravenous morphine consumption, pain scores at rest and on movement, and different functional outcomes, measured at up to 48 h. When necessary, longitudinal analyses were performed with a mixed-effects linear model.

RESULTS

The median (interquartile range) of cumulative intravenous morphine consumption at 24 h was 12 mg (4-16) and 8 mg (2-14) in patients having the infiltration or the tibial nerve block respectively (p = 0.20). Our longitudinal model showed a significant interaction between group and time in favor of the tibial nerve block (p = 0.015). No significant differences were present between groups in the other above-mentioned secondary outcomes.

CONCLUSION

A tibial nerve block does not provide superior analgesia when compared to infiltration. However, a tibial nerve block might be associated with a slower increase in morphine consumption over time.

Direct Cementation of Dual Mobility Cups Into the Bony Acetabulum in Primary Total Hip Arthroplasty: Clinical and Radiographic Outcomes at a Minimum 5-Year Follow-Up

BACKGROUND

Cemented dual mobility cups (DMCs) are commonly used in combination with acetabular reinforcement devices. Indeed, according to literature, direct cementation of metal-backed acetabular components into the bony acetabulum remains controversial as this technique is potentially associated with increased rates of aseptic loosening. Therefore, this study aimed to evaluate the clinical and radiographic outcomes of DMC cemented into the bony acetabulum in primary total hip arthroplasty (THA).

METHODS

A total of 49 THA (48 patients, mean age 78 years [range, 51 to 91]) performed with direct cementation of a DMC into the bony acetabulum were prospectively included in our total joint registry and retrospectively reviewed. The clinical outcome was assessed using the Harris hip score (HHS). The radiographic outcome included measurement of component positioning and occurrence and progression of demarcation around the cemented DMC. Complications were reported with a particular attention to cemented fixation failure and aseptic loosening.

RESULTS

At a 7-year mean follow-up (range, 5 to 8), the pre-to postoperative HHS improved from 47 (range, 30 to 58) to 92 points (range, 80 to 98) (P < .01). Nonprogressive and focalized demarcations were observed in 7 THA (14%). Importantly, no progressive demarcation or DMC aseptic loosening was observed.

CONCLUSION

Direct cementation of DMC into the bony acetabulum ensured a stable fixation with no progressive demarcation or aseptic loosening at midterm follow-up. Therefore, this technique can be selectively considered in primary THA, especially in elderly or frail patients to avoid potential mechanical failure of press-fit fixation due to altered bone quality or additional morbidity related to the use of acetabular reinforcement devices.

[Partial knee arthroplasty - Which parameters to consider for the correct indication and to achieve an optimal result?]

Unicompartmental knee arthroplasty (UKA) is considered an excellent alternative to total knee arthroplasty (TKA) in the treatment of unicompartmental femoro-tibial degeneration with superior functional scores, reduced morbidity and fewer complications. However, revision rates are higher, mainly during the early postoperative period. Failures are attributed to incorrect indications, surgical technical errors and to the low threshold to revision. Several clinical and radiological parameters have to be considered for a correct indication. A high surgical volume is mandatory to assure optimal outcome and survivorship.

POS0232 IDENTIFICATION OF THE CORE REGULATORY GENE NETWORKS REGULATING SUBCHONDRAL BONE AND MARROW ADIPOSE TISSUE REMODELING IN HUMAN KNEE OA

Background

Subchondral bone and the marrow adipose tissue (BMAT) contained therein undergo elevated turnover and remodeling during progression of osteoarthritis (OA). BMAT changes, detected as bone marrow lesions (BML) on MRI images, are considered important diagnostic and prognostic imaging biomarkers for OA. However, a comprehensive understanding of the regulatory mechanisms in individual BMAT-resident cell populations that mediate marrow fibrosis and subchondral bone sclerosis is still lacking. Recently generated single-cell transcriptomic atlas of human adipose tissue has opened new avenues for computational bulk tissue cell type deconvolution and dissecting gene regulatory networks.

Objectives

To infer core gene regulatory networks underlying subchondral bone sclerosis and BMAT remodeling in human knee OA.

Methods

We conducted comparative transcriptomics on bulk transcriptomic profiles of human subchondral bone tissue from three independent studies1,2,3 comprising tibial plateaus from non-OA controls (n=20) and BMLs (n=14), non-sclerotic (n=45) and sclerotic (n=45) regions from patients with medial knee OA. Cell type deconvolution (adipocyte/pre-adipocyte/fibroblast/endothelial/macrophage) of differentially expressed genes (DEGs) was performed using single-cell atlases of human brown and white adipose tissue4. Cell type annotated DEGs were functionally annotated using Gene Ontology enrichment. To infer transcription factors (TFs) regulating gene networks we performed ChIP-Seq enrichment analyses and assessed the presence of TF binding sites in the proximal promoter (-500/+100) sequence of DEGs. Tissue explants were stained en bloc with Oil red O and Hoechst to evaluate distribution of neutral lipids and nuclei in BMAT from non-sclerotic and sclerotic regions.

Results

534 upregulated and 363 downregulated DEGs were shared between at least two independent datasets. Cell deconvolution revealed the majority of upregulated DEGs were expressed in fibroblasts (38%), pre-adipocytes (27%) and endothelial cells (22%). Dowregulated DEGs were predominantly expressed by endothelial (31%), adipocyte (25%) and fibroblast (16%) cell populations. We inferred major TF regulatory networks driving upregulated DEGs in pre-adipocytes (PRRX1/SNAI2/TWIST1) and fibroblasts (SP7/SMAD4/RUNX2/DLX5) and loss of PPARG/SOX17/SNAI1-driven gene expression in adipocytes and endothelial cells. Pre-adipocyte genes were functionally enriched for collagen fibril organization, ossification and cell migration. Fibroblast genes associated with biomineral tissue development and negative regulation of angiogenesis. Downregulated DEGs were enriched for triglyceride catabolism and sequestration (adipocytes) and regulation of vascular permeability and endothelial cell differentiation (endothelial). Whole mount staining displayed homogenous distribution of neutral lipids in adipocytes and low cell abundance in BMAT from non-sclerotic tissue. In contrast, BMAT from sclerotic tissue showed heterogeneously distributed and lower neutral lipid content as well as high cell abundance (Figure 1).

Figure 1.

Conclusion

These data provide detailed insight into the cellular and molecular mechanisms underpinning subchondral bone and BMAT remodeling in OA. An expansion of pre-adipocyte populations along altered function of BMAT adipocytes might represent a previously unrecognized mechanism regulating subchondral bone sclerosis. TFs driving core gene regulatory networks might be promising therapeutic targets for knee OA.

References

[1]Chou CH, Wu CC, Song IW et al. Arthritis Res Ther. 2013

[2]Kuttapitiy A, Assi L, Laing K et al. Ann Rheum Dis. 2017

[3]Tuerlings M, van Hoolwerff M, Houtman E et al. Arthritis Rheumatol. 2021

[4]Sun W, Dong W, Balaz M et al. Nature. 2020

Disclosure of Interests

None declared

Which femoral neck for a dual mobility cup? A biomechanical evaluation

Purpose

This study aimed to evaluate polyethylene (PE) damage and wear lesions to the chamfer of mobile components under mobile and fixed femoral neck impingement at the third articulation, and to determine which femoral neck characteristics should be considered with a dual mobility cup to limit those lesions.

Methods

Two femoral neck geometries (cylindrical and quadrangular) with two surface finishing roughness (rough and polished), and two head-to-neck ratios (28- and 22.2-mm diameter femoral heads) were evaluated in a hip simulator testing. For each characteristic, six femoral necks were tested with six dual mobility cups under fixed and mobile femoral neck impingement conditions. Chamfer PE damage and volumetric wear were evaluated and compared for each femoral neck characteristic and impingement condition.

Results

Under mobile impingement condition, femoral neck characteristics did not significantly affect PE damage and wear lesions to the chamfer (p = 0.283 to 0.810). However, under fixed impingement condition, significantly higher PE damage and wear lesions to the chamfer were produced by the quadrangular geometry compared to the cylindrical geometry (p = 0.004 to 0.025). In addition, with the quadrangular geometry, rough surface finishing was demonstrated to increase volumetric wear of the chamfer (p = 0.009). No significant influence of head-to-neck ratio was observed on PE damage and wear lesions to the chamfer (p = 0.244 to 0.714).

Discussion

This biomechanical study emphasized that femoral neck characteristics are critical with dual mobility cup and tend to favor a cylindrical geometry particularly whether fixed impingement at the third articulation occurs.

Dual mobility cups associated with proximal femoral replacement in nontumoral indications: Results and complications

INTRODUCTION

Reconstruction of extensive proximal femoral bone loss is a major challenge during total hip arthroplasty (THA). Proximal femoral replacement (PFR), initially used for bone tumors, is an alternative to allograft-prosthetic composite reconstruction. However, PFRs present a high complication rate, particularly related to dislocation. Moreover, dual mobility cups (DMCs) are effective in preventing dislocation, and no study has yet assessed their association with PFRs. Therefore, the aim of this study was to assess the dislocation and complication rates in THA using PFRs with DMCs.

HYPOTHESIS

The use of a DMC decreases the dislocation rate associated with PFRs in nontumoral indications.

METHODS

From 2008 to 2017, 66 PFRs associated with a DMC (40 women, mean age=71 years [26-94]) were included in our total joint registry and retrospectively reviewed. The main indications were complex periprosthetic and pertrochanteric fractures (26 THAs, 40%), aseptic loosening (22 THAs, 33%) and periprosthetic joint infections (18 THAs, 27%). A single design of PFR implant was used (Global Modular Replacement System (GMRS), Stryker, Mahwah, NJ, USA) with an uncemented stem in 54 THAs (82%).

RESULTS

Eighteen complications (27%) were reported at a mean follow-up of 4.6 years [2-10]: 5 dislocations (7.5%), 9 periprosthetic joint infections (13.6%), 2 aseptic loosening (3%) and 2 femur fractures (3%). Overall survivorship at 5 years was 72% (95% CI: 58-82). Survivorship free from dislocation was 94% (95% CI: 85-98) at 1 year. The mean Harris Hip Score was 70±16.4 [26-100] at latest follow-up.

CONCLUSION

The use of DMCs limits the risk of PFR dislocation, in comparison to other series in the literature that used large femoral heads, without compromising implant survivorship. In addition, DMCs make it possible to overcome the potential risks of mechanical failure associated with constrained acetabular components.

LEVEL OF EVIDENCE

IV; retrospective cohort.

Polyethylene wear of dual mobility cups: a comparative analysis based on patient-specific finite element modeling

Purpose

Concerns remain about potential increased wear with dual mobility cups related to the multiple articulations involved in this specific design of implant. This finite element analysis study aimed to compare polyethylene (PE) wear between dual mobility cup and conventional acetabular component, and between the use of conventional ultra-high molecular weight PE (UHMWPE) and highly cross-linked PE (XPLE).

Methods

Patient-specific finite element modeling was developed for 15 patients undergoing primary total hip arthroplasty (THA). Five acetabular components were 3D modeled and compared in THA constructs replicating existing implants: a dual mobility cup with a 22.2-mm-diameter femoral head against UHMWPE or XLPE (DM22PE or DM22XL), a conventional cup with a 22.2-mm-diameter femoral head against UHMWPE (SD22PE) and a conventional cup with a 32-mm-diameter femoral head against UHMWPE or XLPE (SD32PE or SD32XL).

Results

DM22PE produced 4.6 times and 5.1 times more volumetric wear than SD32XL and DM22XL (p < 0.0001, Cohen’s d = 6.97 and 7.11; respectively). However, even if significant, the differences in volumetric wear between DM22XL and SD32XL as well as between DM22PE and SD22PE or SD32PE were small according to their effect size (p < 0.0001, Cohen’s |d|= 0.48 to 0.65) and could be therefore considered as clinically negligible.

Conclusion

When using XLPE instead of UHMWPE, dual mobility cup with a 22.2-mm-diameter femoral head produced a similar amount of volumetric wear than conventional acetabular component with a 32-mm-diameter femoral head against XLPE. Therefore, XLPE is advocated in dual mobility cup to improve its wear performance.

The Relationship Between Postoperative Opioid Analgesia and Sleep Apnea Severity in Patients Undergoing Hip Arthroplasty: A Randomized, Controlled, Triple-Blinded Trial

PURPOSE

Residual postoperative pain after hip arthroplasty is usually treated with oral opioids. While classic opioids are associated with respiratory depression and worsening of sleep apnea, tramadol has been reported to preserve respiratory function. However, this has not been investigated in a prospective trial using respiratory polygraphy. This randomized controlled triple-blinded trial tested the hypothesis that postoperative treatment with oral opioids such as oxycodone would increase sleep apnea severity, measured with a respiratory polygraphy, compared with oral tramadol.

PATIENTS AND METHODS

Sixty patients undergoing hip arthroplasty under spinal anesthesia with 15 mg isobaric bupivacaine 0.5% were randomized to receive postoperative pain treatment with either oral oxycodone (controlled-release 10 mg every 12 hours and immediate-release 5 mg every 4 hours as needed) or oral tramadol (controlled-release 100 mg every 8 hours and immediate-release 50 mg every 4 hours as needed). Respiratory polygraphy was performed on the first postoperative night. The primary outcome was the apnea-hypopnea index in the supine position. Secondary outcomes included the oxygen desaturation index, postoperative pain scores and intravenous morphine consumption.

RESULTS

Mean supine apnea-hypopnea index on postoperative night 1 was 11.3 events.h^-1 (95% confidence interval, 4.8-17.7) in the oxycodone group and 10.7 (4.6-16.8) events.h^-1 in the tramadol group (p=0.89). There were no significant differences between the oxycodone and tramadol groups with respect to any secondary sleep-related or pain-related outcomes.

CONCLUSION

Oral oxycodone did not increase sleep apnea severity measured using respiratory polygraphy compared with oral tramadol on the first postoperative night after hip arthroplasty.

TRIAL REGISTRATION NUMBER

Clinicaltrials.gov - NCT03454217 (date of registration: 05/03/2018).

The analgesic efficacy of iPACK after knee surgery: A systematic review and meta-analysis with trial sequential analysis

STUDY OBJECTIVE

The novel infiltration between the popliteal artery and the capsule of the posterior knee (iPACK) has been described to relieve posterior knee pain after knee surgery. The study objective is to determine whether iPACK provides analgesia after knee surgery when compared with a control group.

DESIGN

Systematic review, meta-analysis and trial sequential analysis.

SETTING

Operating room, postoperative recovery area and ward, up to 24 postoperative hours.

PATIENTS

Patients scheduled for knee surgery under general or spinal anaesthesia.

INTERVENTIONS

We searched five electronic databases for randomized controlled trials comparing iPACK with a control group.

MEASUREMENTS

The primary outcome was rest pain score scores on a visual analogue scale (VAS) of 0-10 at 12 h postoperatively, analysed according to the nature of surgery (total knee arthroplasty vs. anterior cruciate ligament reconstruction) and the use of multimodal analgesia. Secondary outcomes included rest and dynamic pain scores, intravenous morphine-equivalent consumption at 2 h and 24 h, and functional outcomes including ambulation distance and range of motion at discharge.

MAIN RESULTS

Six trials involving 687 patients were included, all of which received total knee arthroplasty only. When compared with a control group, iPACK significantly reduced rest pain scores at 12 h, with a mean difference (95% CI) of -1.0 (-1.5 to -0.5), I² = 93%, p = 0.0003, without subgroup differences for postoperative multimodal analgesia (p = 0.15). Secondary pain outcomes were inconsistently improved with iPACK. Functional outcomes were either similar between groups or had clinically unimportant differences. The overall quality of evidence was moderate.

CONCLUSIONS

There is moderate level evidence that iPACK might provide analgesia for posterior pain after total knee arthroplasty when compared with a control group at 12 h, but was not associated with any other meaningful benefits. Based on these results, there is currently limited evidence supporting the use of iPACK as a complement to adductor canal block for analgesia after total knee arthroplasty.

Total hip arthroplasty through the direct anterior approach with and without the use of a traction table: a matched-control, retrospective, single-surgeon study

BACKGROUND

Hip surgeons performing total hip arthroplasty (THA) through the direct anterior approach (DAA) commonly use a traction table to facilitate exposure. Even though performing THA through DAA without a traction table could be technically more demanding, this technique offers the advantage of intraoperative leg length comparison. Therefore, this study aimed to compare clinical outcomes, complication rates, component positioning, and leg length discrepancy (LLD) after THA through the DAA performed with or without a traction table.

METHODS

A single-surgeon continuous series of 75 patients who underwent DAA THA performed with a traction table was matched for gender, age, and BMI with 75 patients who underwent DAA THA performed without a traction table (male, 62; female, 88, with an average age of 68 years old). Clinical and radiological outcomes, intra- and postoperative complications, and LLD were retrospectively assessed.

RESULTS

No statistically significant difference was detected in surgical time, hospital stay, Harris Hip Score (HHS), complication rates, and implant positioning between the two groups. Leg length restoration was significantly more accurate in the group performed without a traction table (2.4 ± 2 mm vs. 3.7 ± 3.1 mm; p value ≤ 0.05). No LLD > 10 mm was reported in the group performed without a traction table, whereas two cases (2.7%) were reported in those performed with a traction table.

CONCLUSION

Performing THA through DAA without a traction table was associated with a significantly more accurate leg length restoration without a significant increase in the rates of intra- and postoperative complications.

Cementation of a Dual Mobility Cup Into an Existing Well-Fixed Metal Shell: A Reliable Option to Manage Wear-Related Recurrent Dislocation in Patients With High Surgical Risk

BACKGROUND

During revision total hip arthroplasty (THA), the "double-socket" technique has been proposed as a straightforward solution in order to reduce the overall perioperative morbidity in patients with high surgical risk. However, the option of cementing a dual mobility cup into an existing well-fixed metal shell was sparsely reported. Therefore, this study aimed to evaluate the outcome of a "double-socket" technique performed with a cemented dual mobility cup in revision THA for late instability.

METHODS

Twenty-eight revision THAs (28 patients) were performed for wear-related recurrent dislocation using a "double-socket" technique with a cemented dual mobility cup and retrospectively reviewed. The age at revision averaged 82 years (range 74-93). According to the American Society of Anesthesiologists (ASA) physical status classification, 12 patients (43%) were ASA II and 16 patients (57%) were ASA III before revision.

RESULTS

At a mean follow-up of 3.5 years (range 2-5), the mean preoperative to postoperative functional outcome improved significantly (P < .01). The mean operative time was 107 minutes (range 75-140). The mean intraoperative bleeding was 200 mL (range 110-420). No postoperative complication, reoperation, or re-revision was reported. Importantly, no dislocation, dissociation of the cemented dual mobility cup construct, or aseptic loosening of the retained metal shell was observed.

CONCLUSION

The "double-socket" technique with a dual mobility cup cemented into an existing well-fixed and well-positioned metal shell ensured a straightforward and blood-sparing revision technique that was efficient to restore stability and provide a secure acetabular construct in frail patients with high surgical risk and/or older than their natural life expectancy.

Bone and parietal anterior iliac crest reconstruction for trans-iliac hernia after tricortical graft harvesting: An original technique

Tricortical cortico-cancellous bone allografts from the anterior iliac crest are routinely used in revision arthroplasty and to treat non-union. Trans-iliac herniation (TIH) has been reported as an exceptional complication after extensive graft harvesting. The various reconstruction techniques include isolated parietal reconstruction and combined parietal and bone reconstruction using allografts or a spacer to reconstruct the bone defect. No previous study has evaluated a combined reconstruction technique involving both bone reconstruction with a titanium plate and abdominal wall reconstruction with a parietal reinforcement prosthesis. This technical note describes the evaluation of an original combined reconstruction technique used after failure of isolated parietal reconstruction to treat TIH. Through a direct approach to the anterior iliac crest, the bone defect was repaired using a flexible titanium cranio-facial reconstruction plate and the abdominal wall defect using a polypropylene/poliglecaprone parietal reinforcement prosthesis. This original technique was demonstrated to be effective for treating TIH, with no recurrence after 2.5 years of follow-up. In addition, this technique involves no added morbidity related, for instance, to allograft using or spacer migration.

Total Hip Arthroplasty for Periacetabular Metastatic Disease. An Original Technique of Reconstruction According to the Harrington Classification

BACKGROUND

Periacetabular metastatic disease requires complex acetabular reconstruction. The complication rate for these frail patients is high. Various cement-rebar reinforced techniques allowing cemented total hip arthroplasty (THA) have been described. The optimal procedure has not yet been identified.

METHODS

A continuous series of 131 THAs performed in 126 patients with periacetabular metastatic disease was prospectively included in this study. After bone metastasis curettage and cementation, an original technique of acetabular reconstruction was performed using a dual mobility cup cemented into an acetabular reinforcement device (ie, Kerboull cross-plate or Burch-Schneider antiprotrusio cage) according to the Harrington classification. Functional outcome for independent ambulation in the community, pain relief, and occurrence of dislocation or mechanical failure of the acetabular reconstruction were assessed.

RESULTS

At a mean follow-up of 33 ± 17 months, the improvement in the preoperative to postoperative functional outcome and pain relief was significant (P < .001). The dislocation rate was 2%. Two of the 3 cases of dislocation occurred in acetabular reconstructions associated with a proximal femoral arthroplasty. No mechanical failure or aseptic loosening of the acetabular reconstruction was observed.

CONCLUSION

This study emphasized that our original technique combining bone metastasis curettage and cementation, acetabular reinforcement device and cemented dual mobility cup was effective to restore a painless functional independence and ensure a durable acetabular reconstruction able to face to adjuvant radiation therapy and mechanical solicitations for long survivors. In addition, dual mobility cup limited the risk of dislocation in patients undergoing THA for periacetabular metastatic disease.

Bone metastases from lung cancer: A paradigm for multidisciplinary onco-rheumatology management

Bone is the third metastatic site after liver and lungs. Bone metastases occur in one out of three lung cancers and are usually of osteolytic aspect. Osteolytic bone metastases are responsible of long bone and vertebral fractures leading to restricted mobility, surgery and medullar compression that severely alter quality of life and that have a huge medico-economic impact. In the recent years, Bone Metastatic Multidisciplinary Tumour Board (BM²TB) have been developed to optimize bone metastases management for each patient in harmony with oncology program. In this review, we will go through all the different aspects of bone metastases management including diagnosis and evaluation (CT scan, Tc 99m-MDP bone scan, ¹⁸FDG-PET scan and biopsy for molecular diagnosis), systemic bone treatments (zoledronic acid and denosumab) and local treatments (interventional radiology and radiotherapy). Surgical strategies will be discussed elsewhere. Based on the last 2017-Lung Cancer South East French Guidelines, we present a practical decision tree to help the physicians for decision making in order to reach a personalized locomotor strategy for every patient.

Bone, muscle, and metabolic parameters predict survival in patients with synchronous bone metastases from lung cancers

BACKGROUND

Lung adenocarcinoma regularly induces bone metastases that are responsible for impaired quality of life as well as significant morbidity, including bone pain and fractures. We aimed at identifying whether bone and metabolic biomarkers were associated with the prognosis of lung adenocarcinoma patients with synchronous bone metastases.

PATIENTS AND METHODS

POUMOS is a prospective cohort of patients diagnosed with lung adenocarcinoma and synchronous bone metastases. All patients underwent biopsy of bone metastases to confirm diagnosis, including genotyping of oncogenic drivers such as EGFR and KRAS. Whole-body composition was assessed using DEXA scan. Serum levels of C-reactive protein, HbA1C, calcaemia, sCTX, and DKK1 were also measured.

RESULTS

Sixty four patients, aged (mean ± SD) 65 ± 11 years, were included. Thirty-nine (61%) patients had a good performance status (PS 0-1); 56% had >5 bone lesions, and 41% a weight-bearing bone (femour or tibia) involvement. Median overall survival was 7 months. In multivariate analysis, HbA1c (HR = 1.69 [1.10-2.63] per 0.5% decrease; p = .02), DKK1 (HR = 1.28 [1.01-1.61] per 10 ng/mL increase; p = .04), and hypercalcaemia (HR = 2.83 [1.10-7.30]; p = .03) were independently associated with poorer survival. In the subgroup of patients with DEXA, sarcopenia was also associated with poorer survival (HR = 2.96, 95%CI [1.40-6.27]; p = .005).

CONCLUSIONS

In patients with lung adenocarcinoma and synchronous bone metastases, bone, sarcopenia, and metabolic parameters were predictors of poor overall survival independently of common prognostic factors. We suggest that, in addition to oncological therapy, supportive treatment dedicated to bone metastases, muscle wasting, and energy metabolism are essential to improve prognosis.

The predictive factors of secondary patellar resurfacing in computer-assisted total knee arthroplasty. A prospective cohort study

PURPOSE

The decision to resurface the patella during total knee arthroplasty (TKA) remains controversial. This prospective cohort study aimed to evaluate the outcome and survivorship of the native patella in computer-assisted TKA (CAS TKA) implanted for primary knee osteoarthritis, and to determine the predictive factors of secondary patellar resurfacing (SPR).

METHODS

A prospective cohort of 273 cementless ultra-congruent mobile-bearing CAS TKA implanted without patellar resurfacing was included in our total joint registry. Patients were evaluated with the International Knee Society (IKS) and Hospital for Special Surgery Patellar (HSSP) scores. Radiographic evaluation was focused on the patellofemoral (PF) compartment to assess: the patellar dysplasia (Wiberg classification), PF osteoarthritis (Iwano classification), femoral trochlear dysplasia (femoral sulcus angle), patellar maltracking (patellar tilt and lateralization), and patella height (Blackburne-Peel ratio).

RESULTS

At a six-year median follow-up, the CAS TKA survivorship using SPR as end-point was 95% (range, 91-99%). The IKS and HSSP improved significantly after SPR (p = 0.001 and 0.004, respectively). No significant difference in the IKS and HSSP was detected between TKA with native patella and SPR-TKA at latest follow-up. Importantly, four pre-operative radiographic PF parameters were significantly associated with SPR: higher stages of patellar dysplasia and PF osteoarthritis, and higher sulcus angle and patellar lateralization (hazard ratios = 5.1 to 11.6, p = 0.009 to 0.04).

CONCLUSION

When preserving the native patella, surgeons should be aware of pre-operative PF radiographic parameters that could influence the outcome and survivorship of CAS TKA leading to SPR. Particularly, evidence of PF dysplasia, osteoarthritis and maltracking should be determined pre-operatively to resurface the patella at the time of TKA.

LEVEL OF EVIDENCE

Therapeutic Level II (prospective cohort study).

Highly crosslinked polyethylene: a safe alternative to conventional polyethylene for dual mobility cup mobile component. A biomechanical validation

PURPOSE

Dual mobility cup (DMC) consists of a cobalt-chromium (CoCr) alloy cup articulated with a polyethylene (PE) mobile component capturing the femoral head in force using a snap-fit technique. This biomechanical study was the first to evaluate and compare the generation of cracks in the retentive area of DMC mobile components made of highly crosslinked PE (XLPE) or conventional ultra-high molecular weight PE (UHMWPE).

METHODS

Eighty mobile components designed for a 52-mm diameter Symbol® DMC (Dedienne Santé, Mauguio, France) and a 28-mm diameter femoral head were analyzed. Four groups of 20 mobile components were constituted according to the PE material: raw UHMWPE, sterilized UHMWPE, annealed XLPE and remelted XLPE. Ten mobile components in each group were impacted with a 28-mm diameter CoCr femoral head using a snap-fit technique. The occurrence, location and area of the cracks in the retentive area were investigated using micro-CT (Skyscan 1176®, Bruker, Aarsellar, Belgium) with a 35 μm nominal isotropic voxel size by two observers blinded to the PE material and impaction or not of the mobile components.

RESULTS

Compared to conventional UHMWPE, the femoral head snap-fit did not generate more or wider cracks in the retentive area of annealed or remelted XLPE mobile components.

CONCLUSION

This biomechanical study suggests that XLPE in DMC could be a safe alternative to conventional UHMWPE regarding the generation of cracks in the retentive area related to the femoral head snap-fit.

Vertebral body morphology is associated with incident lumbar vertebral fracture in postmenopausal women. The OFELY study

We investigate the predictive role of vertebral anterior cortical curvature and height heterogeneity in the occurrence of vertebral fractures in postmenopausal women. Women who will fracture had shorter vertebral height, greater heterogeneity of height than those who will not fracture, and their anterior vertebral body edge was less concave.

INTRODUCTION

Vertebral morphology has been demonstrated to be associated with further risk of fracture. The aim of this study was to analyze vertebral anterior cortical curvature (Ct.curv) and vertebral height heterogeneity in postmenopausal women before the occurrence of a vertebral fracture.

METHODS

This case-control study included 29 postmenopausal women who have underwent incident lumbar vertebral fractures (mean age 71 ± 9 years, mean time to fractures 9 ± 4 years), age-matched with 57 controls. From lateral X-rays of lumbar spine radiographs (T12 to L4), the following parameters were measured: (1) the posterior, middle, and anterior vertebral heights; (2) the heterogeneity of heights evaluated by the coefficient of variation of these three variables; (3) antero-posterior width, a 2D estimator of cross-sectional area; and (4) Ct.curv.

RESULTS

Mean vertebral heights were significantly lower among women who fractured than in controls (p < 0.05). The anterior and middle heights were significantly lower at L4 and L3 levels in fracture group (p = 0.02). The heterogeneity of vertebral height was significantly greater in the fracture group (p = 0.003). In addition, fractured patients had a significantly higher Ct.curv on L3 (p = 0.04). After adjustment for bone mineral density (BMD), only the heterogeneity of vertebral height remained significant (p = 0.005).

CONCLUSION

The current case-control study confirmed the association between vertebral height and occurrence of future vertebral fracture in postmenopausal women. The vertebrae with the smallest Ct.curv tended to fracture less often, and the heterogeneity of vertebral heights was associated with future fracture independently of BMD. An additional validation in a prospective study would be needed to confirm these initial results.

Performance of Porous Tantalum vs. Titanium Cup in Total Hip Arthroplasty: Randomized Trial with Minimum 10-Year Follow-Up

Porous tantalum monoblock cups have been proposed to improve survivorship of cementless primary THA. However, there are few direct comparative trials to established implants such as porous-coated titanium cups. 113 patients were randomized into two groups according to the cup: a porous tantalum monoblock cup (TM) or a porous-coated titanium monoblock cup (control). At a mean of 12 years after THA, no implants migrated in both groups. Two TM patients (4%) and 13 control patients (33%) presented with radiolucency around the cup (P<0.001). In the control group, 1 cup (2%) was revised for aseptic loosening. At 12 years post-implantation, porous tantalum monoblock cups demonstrated 100% survivorship, and significantly less radiolucency as compared to porous-coated titanium monoblock cups.

Can Dual Mobility Cups prevent Dislocation in All Situations After Revision Total Hip Arthroplasty?

The outcome of a single design of dual mobility cup was prospectively evaluated in a continuous series of 994 revision THAs with respect to dislocation and intra-prosthetic dislocation (IPD). At a 7.3-year mean follow-up, the dislocation rate was 1.5% and the IPD rate was 0.2%. The 2 IPD occurred in acetabular-only revisions and were related to a poor head-to-neck ratio with early impingement and wear at the polyethylene mobile component chamfer. Dual mobility cups demonstrated a low dislocation rate in revision THA but did not compensate for potential perioperative technical errors. In addition, IPD did not appear to be a concern with respect to the benefit in term of instability prevention though caution is advised in acetabular-only revision associated with a poor head-to-neck ratio.

LEVEL OF EVIDENCE

Therapeutic study-Level IV.

Fungaemia caused by Fusarium proliferatum in a patient without definite immunodeficiency

Recent literature has shown the growing importance of opportunistic fungal infections due to Fusarium spp. However, disseminated fusariosis remains rare in patients without neutropenia. We report a case of fungaemia in a 78-year-old French woman without definite immunodeficiency. Fusarium proliferatum grew from both central and peripheral blood cultures. Fever was the only clinical sign of the infection. An appropriate antifungal therapy with voriconazole led to the recovery of the patient. An environmental investigation was undertaken but failed to find a reservoir of Fusarium spores. A contaminated central venous catheter might have been the source of fungaemia.

Acetabular reconstruction using a Kerboull cross-plate, structural allograft and cemented dual-mobility cup in revision THA at a minimum 5-year follow-up

The current study aimed to evaluate the outcome of a continuous and prospective series of 61 revision THAs with AAOS grade III and IV acetabular bone defect reconstruction using a Kerboull cross-plate, structural allograft and cemented dual mobility cup (Saturne, Amplitude, Valence, France). At a 7.5-year mean follow-up, no instability was reported after revision. In addition, no failure of the acetabular reconstruction was observed in 98% of the patients with complete allograft osseointegration and no evidence of mechanical rupture of the Kerboull cross-plate and/or loosening of the cemented dual mobility cup. In conclusion, such reconstruction technique demonstrated excellent results at mid-term follow-up in terms of prevention of instability after revision, restoration of the acetabular bone stock, and stable cemented fixation of the dual mobility cup.

The role of bone intrinsic properties measured by infrared spectroscopy in whole lumbar vertebra mechanics: organic rather than inorganic bone matrix?

Whole bone strength is determined by bone mass, microarchitecture and intrinsic properties of the bone matrix. However, few studies have directly investigated the contribution of bone tissue material properties to whole bone strength in humans. This study assessed the role of bone matrix composition on whole lumbar vertebra mechanics. We obtained 17 fresh frozen human lumbar spines (8 W, 9 M, aged 76±11years). L3 bone mass was measured by DXA and microarchitecture by μ-CT with a 35 μm-isotropic resolution. Microarchitectural parameters were directly measured: Tb.BV/TV, SMI, Tb.Th, DA, Ct.Th, Ct.Po and radius of anterior cortical curvature. Failure load (N), stiffness (N/mm) and work to failure (N.mm) were extracted from quasi-static uniaxial compressive testing performed on L3 vertebral bodies. FTIRM analysis was performed on 2 μm-thick sections from L2 trabecular cores, with a Perkin-Elmer GXII Auto-image Microscope equipped with a wide band detector. Twenty measurements per sample were performed at 30∗100 μm of spatial resolution. Each spectrum was collected at 4 cm(-1) resolution and 50 scans in transmission mode. Mineral and collagen maturity, and mineralization and crystallinity index were measured. There was no association between the bone matrix characteristics and bone mass or microarchitecture. Mineral maturity, mineralization and crystallinity index were not related to whole vertebra mechanics. However, collagen maturity was positively correlated with whole vertebra failure load and stiffness (r=0.64, p=0.005 and r=0.54, p=0.025, respectively). The collagen maturity (3rd step) in combination with bone mass (i.e., BMC, 1st step) and microarchitecture (i.e., Tb.Th, 2nd step) improved the prediction of whole vertebra mechanical properties in forward stepwise multiple regression models, together explaining 71% of the variability in whole vertebra stiffness (p=0.001). In conclusion, we demonstrated a substantial contribution of collagen maturity, but not mineralization parameters, to whole bone strength of human lumbar vertebrae that was independent of bone mass and microarchitecture.

The predictive value of trabecular bone score (TBS) on whole lumbar vertebrae mechanics: an ex vivo study

We investigated the association of trabecular bone score (TBS) with microarchitecture and mechanical behavior of human lumbar vertebrae. We found that TBS reflects vertebral trabecular microarchitecture and is an independent predictor of vertebral mechanics. However, the addition of TBS to areal BMD (aBMD) did not significantly improve prediction of vertebral strength.

INTRODUCTION

The trabecular bone score (TBS) is a gray-level measure of texture using a modified experimental variogram which can be extracted from dual-energy X-ray absorptiometry (DXA) images. The current study aimed to confirm whether TBS is associated with trabecular microarchitecture and mechanics of human lumbar vertebrae, and if its combination with BMD improves prediction of fracture risk.

METHODS

Lumbar vertebrae (L3) were harvested fresh from 16 donors. The anteroposterior and lateral bone mineral content (BMC) and areal BMD (aBMD) of the vertebral body were measured using DXA; then, the TBS was extracted using TBS iNsight software (Medimaps SA, France). The trabecular bone volume (Tb.BV/tissue volume, TV), trabecular thickness (Tb.Th), degree of anisotropy, and structure model index (SMI) were measured using microcomputed tomography. Quasi-static uniaxial compressive testing was performed on L3 vertebral bodies to assess failure load and stiffness.

RESULTS

The TBS was significantly correlated to Tb.BV/TV and SMI (r = 0.58 and -0.62; p = 0.02, 0.01), but not related to BMC and BMD. TBS was significantly correlated with stiffness (r = 0.64; p = 0.007), independently of bone mass. Using stepwise multiple regression models, we failed to demonstrate that the combination of BMD and TBS was better at explaining mechanical behavior than either variable alone. However, the combination TBS, Tb.Th, and BMC did perform better than each parameter alone, explaining 79% of the variability in stiffness.

CONCLUSIONS

In our study, TBS was associated with microarchitecture parameters and with vertebral mechanical behavior, but TBS did not improve prediction of vertebral biomechanical properties in addition to aBMD.

Cementation of a dual-mobility acetabular component into a well-fixed metal shell during revision total hip arthroplasty: a biomechanical validation

Cementation of polyethylene (PE) liners into well-fixed metal shells has become a popular option during revision total hip arthroplasty (THA) particularly for older and frail patients. Although dramatic results were reported with dual-mobility acetabular components to manage hip instability during revision THA, no study evaluated the fixation strength of the cementation of dual-mobility components into well-fixed metal shells. Eight dual-mobility and eight all-PE components were cemented into a metal shell with a uniform 2- to 3-mm cement mantle. The cemented fixation strength was evaluated using lever-out and torsion testing. The interface at which failure occurred was determined. Lever-out testing showed that dual-mobility components failed at significantly higher maximum moment than the all-PE components. No direct comparison could be performed with torsion testing due to early failure of the all-PE component itself before failure of the cement fixation. However, the maximum moments measured were dramatically higher than the in vivo frictional moments classically reported in THA. In addition, failure was always observed at the metal shell/cement interface whenever it did occur. In conclusion, a dual-mobility acetabular component cemented into a well-fixed metal shell could constitute a biomechanically acceptable alternative to acetabular shell removal or PE liner cementation while simultaneously preventing instability of the THA revision. Clinical studies are warranted.

The John Insall award: no benefit of minimally invasive TKA on gait and strength outcomes: a randomized controlled trial

BACKGROUND

While some clinical reports suggest minimally invasive surgical (MIS) techniques improve recovery and reduce pain in the first months after TKA, it is unclear whether it improves gait and thigh muscle strength.

QUESTIONS/PURPOSES

We hypothesized TKA performed through a mini-subvastus approach would improve subjective and objective and subjective function compared to a standard medial parapatellar approach 2 months after surgery.

METHODS

We randomized 40 patients into two groups using either the mini-subvastus approach or standard medial parapatellar approach. Patients were evaluated preoperatively and 2 months after surgery. We assessed subjective functional outcome and quality of life (QOL) using routine questionnaires (SF-12, Knee Society Score [KSS], Knee Injury and Osteoarthritis Outcome Score [KOOS], UCLA activity, patient milestone diary of activities). We determined isometric strength of the thigh muscles and assessed gait with a three-dimensional (3-D) analysis during level walking and stair climbing.

RESULTS

We observed improvements from preoperatively to 2 months postoperatively in functional scores, QOL, and knee kinematic and kinetic gait parameters during level and stair walking. Isometric quadriceps strength increased in both groups, although remaining lower when compared to sound limbs. We found no differences between the groups in KSS, SF-12, KOOS, UCLA activity, patient milestone diary of activities, isometric quadriceps strength, or 3-D gait parameters, except a marginally higher speed of stair ascent in the MIS group.

CONCLUSIONS

Our observations suggest an MIS approach does not confer a substantial advantage in early function after TKA.

LEVEL OF EVIDENCE

Level I, therapeutic study. See Instructions to Authors for a complete description of levels of evidence.

Determinants of the mechanical behavior of human lumbar vertebrae after simulated mild fracture

The ability of a vertebra to carry load after an initial deformation and the determinants of this postfracture load-bearing capacity are critical but poorly understood. This study aimed to determine the mechanical behavior of vertebrae after simulated mild fracture and to identify the determinants of this postfracture behavior. Twenty-one human L(3) vertebrae were analyzed for bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA) and for microarchitecture by micro-computed tomography (µCT). Mechanical testing was performed in two phases: initial compression of vertebra to 25% deformity, followed, after 30 minutes of relaxation, by a similar test to failure to determine postfracture behavior. We assessed (1) initial and postfracture mechanical parameters, (2) changes in mechanical parameters, (3) postfracture elastic behavior by recovery of vertebral height after relaxation, and (4) postfracture plastic behavior by residual strength and stiffness. Postfracture failure load and stiffness were 11% ± 19% and 53% ± 18% lower than initial values (p = .021 and p < .0001, respectively), with 29% to 69% of the variation in the postfracture mechanical behavior explained by the initial values. Both initial and postfracture mechanical behaviors were significantly correlated with bone mass and microarchitecture. Vertebral deformation recovery averaged 31% ± 7% and was associated with trabecular and cortical thickness (r = 0.47 and r = 0.64; p = .03 and p = .002, respectively). Residual strength and stiffness were independent of bone mass and initial mechanical behavior but were related to trabecular and cortical microarchitecture (|r| = 0.50 to 0.58; p = .02 to .006). In summary, we found marked variation in the postfracture load-bearing capacity following simulated mild vertebral fractures. Bone microarchitecture, but not bone mass, was associated with postfracture mechanical behavior of vertebrae.

Association genetics of carbon isotope discrimination, height and foliar nitrogen in a natural population of Pinus taeda L

Loblolly pine, Pinus taeda L., is one of the most widely planted, commercially and ecologically important tree species in North America. We took an association genetics approach, using an unimproved population of 380 clonally replicated unrelated trees, to test 3,938 single nucleotide polymorphisms (SNPs) in as many genes for association with phenotypic variation in carbon isotope discrimination, foliar nitrogen concentration and total tree height after two growing seasons. Best linear unbiased prediction (BLUP) was used with a spatial adjustment to remove environmental variation from phenotypic data derived from a common garden experiment. After correction for multiple testing, a total of 14 SNPs were associated with the traits of carbon isotope discrimination (n = 7), height (n = 1) and foliar nitrogen concentration (n = 6) using 380 clones. Tails of the population phenotypic distribution were compared for allele frequency differences, revealing 10 SNPs with allele frequency in at least one tail significantly different from the overall population. Eight associated SNPs were in sequences similar to known genes, such as an AP2 transcription factor related to carbon isotope discrimination and glutamate decarboxylase associated with foliar nitrogen concentration, and others were from unknown genes without homologs in Arabidopsis.

Cementless total hip arthroplasty in Paget's disease of bone: a retrospective review

Paget's disease of bone (PDB) is a localised chronic osteopathy leading to bone deformities, bone hypervascularity, structural weakness and altered joint biomechanics. The pelvis and upper femur are frequently involved, resulting in disabling hip disease, and total hip arthroplasty (THA) may be required. We performed a retrospective study on the management and the outcome of 39 uncemented hydroxyapatite fully-coated THA in patients with PDB of the hip. The follow-up averaged 79.4 months (range 24-194). Functional scores improved significantly and, using the Harris hip score, 84% of patients had an excellent clinical outcome at the latest follow-up. Despite one case of an uncemented acetabular component with probable loosening, no implant revision had been required at our latest follow-up. Signs of implant loosening were found to be significantly more frequent in patients with active disease. For this reason, we advocate the use of pre-operative medication with bisphosphonates to reduce disease activity. Another benefit of this treatment is the significant decrease of intra-operative blood loss. Provided the control of disease activity in the pre-operative period with bisphosphonates is achieved, good outcome of cementless THAs can be expected. Bisphosphonates reduced the risk of implant loosening and excessive intra-operative blood loss.

Role of trabecular microarchitecture and its heterogeneity parameters in the mechanical behavior of ex vivo human L3 vertebrae

Low bone mineral density (BMD) is a strong risk factor for vertebral fracture risk in osteoporosis. However, many fractures occur in people with moderately decreased or normal BMD. Our aim was to assess the contributions of trabecular microarchitecture and its heterogeneity to the mechanical behavior of human lumbar vertebrae. Twenty-one human L(3) vertebrae were analyzed for BMD by dual-energy X-ray absorptiometry (DXA) and microarchitecture by high-resolution peripheral quantitative computed tomography (HR-pQCT) and then tested in axial compression. Microarchitecture heterogeneity was assessed using two vertically oriented virtual biopsies--one anterior (Ant) and one posterior (Post)--each divided into three zones (superior, middle, and inferior) and using the whole vertebral trabecular volume for the intraindividual distribution of trabecular separation (Tb.Sp*SD). Heterogeneity parameters were defined as (1) ratios of anterior to posterior microarchitectural parameters and (2) the coefficient of variation of microarchitectural parameters from the superior, middle, and inferior zones. BMD alone explained up to 44% of the variability in vertebral mechanical behavior, bone volume fraction (BV/TV) up to 53%, and trabecular architecture up to 66%. Importantly, bone mass (BMD or BV/TV) in combination with microarchitecture and its heterogeneity improved the prediction of vertebral mechanical behavior, together explaining up to 86% of the variability in vertebral failure load. In conclusion, our data indicate that regional variation of microarchitecture assessment expressed by heterogeneity parameters may enhance prediction of vertebral fracture risk.

Repair of insertional achilles tendinosis with a bone-quadriceps tendon graft

BACKGROUND

While conservative treatment may be successful in most cases, partial rupture at the calcaneal insertion point is a significant concern with insertional Achilles tendinopathy. We report on the outcomes of a surgical technique for Achilles tendon augmentation using a bone-tendon graft harvested from the knee extensor system.

MATERIALS AND METHODS

Our retrospective case series includes 25 surgical procedures performed in 24 patients, 19 males and five females, with a mean age of 47 (range, 30 to 59) years, 18 of whom were athletes. The mean followup period was 52 (range, 12 to 156) months. All patients underwent MRI examination prior to surgery which showed partial Achilles tendon rupture. The Achilles tendon was debrided through a posterolateral approach. The bone-quadriceps tendon graft was harvested, then the bone plug of the graft was inserted into a blind tunnel drilled into the calcaneus and fixed with an interference screw. The fibers of the quadriceps tendon were sutured to the residual part of the Achilles tendon with the foot at an angle of 90 degrees.

RESULTS

Patients were able to resume their sporting activity after an average of 6.7 months. At last followup examination, physical activity was scored 5.2 on the 10-point Tegner Scale; the mean AOFAS score was 98.4. MRI examination showed good graft integration 1 year postoperatively.

CONCLUSION

The bone-quadriceps tendon grafting technique was a good alternative for the insertional Achilles lesions with partial detachment which we felt required augmentation.

Bonding of microfluidic devices fabricated in polycarbonate

A simple method for bonding polycarbonate, based on controlled exposure of the pieces to vapours of solvents, yields a tight seal and unmodified geometry of the channels.

Arthrodesis of the subtalar and talonavicular joints through a medial surgical approach: a series of 15 cases

INTRODUCTION

We report a series of 15 double-hindfoot (subtalar and talonavicular joint) arthrodeses through a single medial approach on 14 patients. Mean age at surgery was 59.3 years. The chosen surgical technique was always identical using a medial approach and performed by a single surgeon. The average follow-up was 20.6 months.

METHOD

The mean Kitaoka score increased from 44 to 75, axis of the hindfoot decreased from 21 degrees to 11 degrees in valgus, arch foot angle decreased from 142 degrees to 134.4 degrees . Two failures have led to a secondary complementary arthrodesis of the talocrural joint.

RESULTS

Throughout our study, subtalar and talonavicular arthrodesis in the treatment of painful valgus deformities of the hindfoot reveals to be a valuable and safe alternative. The chosen fixation method combined with a good articular surface avivement through medial approach guarantee a long-term fusion. Moreover, resort to a medial approach significantly reduces wound complications.

CONCLUSION

This medial approach procedure permits the fusion without developing non-union and provides a significant correction of the fixed deformities.

Chronic Achilles tendon rupture reconstruction using a modified flexor hallucis longus transfer

The purpose of this study was to report the management and outcome of 11 patients presenting with chronic Achilles tendon (AT) rupture treated by a modified flexor hallucis longus (FHL) transfer. Seven patients presented with a neglected AT rupture, one with a chronic AT rupture associated with Achilles tendinosis and three with an AT re-rupture. AT defect after fibrosis debridement averaged 7.4 cm. In addition to FHL transfer, we performed an augmentation using the two remaining fibrous scar stumps of the ruptured AT. Functional assessment was performed using the AOFAS score and isokinetic evaluation was performed to assess ankle plantarflexion torque deficit. Follow-up averaged 79 months. Functional outcome was excellent with a significant improvement of the AOFAS score at latest follow-up. No re-rupture nor major complication, particularly of wound healing, was observed. All patients presented with a loss of active range of motion of the hallux interphalangeal joint without functional weakness during athletic or daily life activities. Isokinetic testing at 30 degrees/second and 120 degrees/second revealed a significant average decrease of 28 ± 11% and 36 ± 4.1%, respectively, in plantarflexion peak torque. Although strength deficit persisted at latest follow-up, functional improvement was significant without morbidity due to FHL harvesting. For patients with chronic AT rupture with a rupture gap of at least 5 cm, surgical repair using FHL transfer with fibrous AT stump reinforcement achieved excellent outcomes.

Efficacy and Safety of Fludarabine and Cyclophosphamide Combined Therapy in Patients with Refractory/Recurrent B-Cell Chronic Lymphocytic Leukaemia (B-CLL)—Polish Multicentre Study

The aim of this study was to investigate the efficacy of a combination of fludarabine (F) and cyclophosphamide (C) in the treatment of patients with refractory/recurrent B-cell chronic lymphocytic leukaemia (B-CLL). Between November 1999 and December 2001, 63 patients with B-CLL (median age 60 years) received a regimen that consisted of F 25 mg/m2 and C 250 mg/m2, days 1-3, intravenously, every 4 weeks, for a maximum of 6 courses, Response and toxicity were assessed according to current criteria (NCI-WG and WHO). Complete and partial remissions were achieved in 17.5% and 55.6% of patients, respectively; 19% of patients had stable disease and 7.9% of patients showed disease progression. The median follow-up was 16.5 (range 1.5-32) months. The median duration of progression-free survival (PFS) has not been reached among patients treated with FC regimen as second-line therapy. The median PFS was 13 (range 8-26) months in the 19 responding patients treated with FC regimen as third-line therapy. The most frequent side-effects were neutropenia (45%), thrombocytopenia (42%) and infections (57%). We conclude that the combination of fludarabine and cyclophosphamide demonstrated significant efficacy in pretreated, advanced B-CLL patients, with tolerable toxicity.

Interaction of genes controlling two allotypes in chickens

This paper presents the results of the investigations of the newly detected antigen of chicken blood serum, called K2. It was established that the K2 antigen which was identified with isoimmune serum was a beta-globulin with the molecular weight over 200 000. The results of the genetic analysis based on sire-dam-offspring combinations seemed to indicate that the antigen under examination was controlled by a gene hypostatic to the gene controlling the previously described K1 allotype.

Repeat revision of anterior cruciate ligament reconstruction: a retrospective review of management and outcome of 10 patients with an average 3-year follow-up

BACKGROUND

To the authors' knowledge, no previous published study has focused on management and outcome of repeat revision of anterior cruciate ligament reconstruction in terms of functional result and meniscus and articular cartilage status.

HYPOTHESIS

Repeat revision of anterior cruciate ligament reconstruction improves knee stability, but with inferior results for functional outcome compared with primary anterior cruciate ligament reconstruction. Meniscal tears and subsequent articular cartilage degeneration are more prevalent with successive revisions due to recurrent laxity.

STUDY DESIGN

Case series; Level of evidence, 4.

MATERIALS AND METHODS

Between February 2003 and November 2006, a consecutive series of 10 patients with an average age at 30 years (range, 17-48) were operated on for a repeat revision of anterior cruciate ligament reconstruction (2 revisions after a primary reconstruction) with arthroscopic procedures. A clinical and a radiographic evaluation were performed to assess anterior cruciate ligament reconstruction failures, outcome of revisions, and causes of failures. Meniscal tears and articular cartilage lesions were analyzed.

RESULTS

The average follow-up of the second revision was 38 months (range, 12-61). At latest follow-up, final International Knee Documentation Committee assessment was excellent or good in 7 cases. Postoperatively, only 2 patients recovered to the same sports activity level they had before their first anterior cruciate ligament reconstruction. Four had a lower level, and 4 discontinued sports activity. The postoperative average side-to-side KT-1000 arthrometer maximum manual difference was 1.3 +/- 1.9 mm. Nine patients had meniscal tears and 7 had articular cartilage lesions. Meniscal tears, meniscectomies, and articular cartilage degeneration increased after the second revision (P = .016, P = .0098, and P = .0197, respectively). Severe articular cartilage degeneration (International Cartilage Repair Society grade III and IV lesions) was found in patients with bad functional outcome (final International Knee Documentation Committee assessment C or D) (P = .0472). Incidence of articular cartilage degeneration was found to be more prevalent in cases of meniscal tears and partial meniscectomy at the same tibiofemoral compartment (P = .0157). Index anterior cruciate ligament reconstruction and first revision failures were caused by recurrent trauma (60% and 70%, respectively) or a surgical technical error with tunnel malpositioning (40% and 10%, respectively).

CONCLUSION

Outcome of repeat revision of anterior cruciate ligament reconstruction was excellent or good in 70% of the cases, although decreased after the second revision, in relation to the occurrence of meniscal tears and articular cartilage lesions. Meniscal and articular cartilage lesions were more frequent and more severe with recurrent laxity. The cause of failures was mainly recurrent trauma, followed by surgical technical errors.

Hospital outbreak of vancomycin-resistant enterococci caused by a single clone of Enterococcus raffinosus and several clones of Enterococcus faecium

A mixed outbreak caused by vancomycin-resistant Enterococcus raffinosus and Enterococcus faecium carrying the vanA gene was analysed. The outbreak occurred in a large hospital in Poland and affected 27 patients, most of whom were colonised, in three wards, including the haematology unit. The E. raffinosus isolates had a high-level multiresistant phenotype and were initially misidentified as Enterococcus avium; their unambiguous identification was provided by multilocus sequence analysis. The molecular investigation demonstrated the clonal character of the E. raffinosus outbreak and the polyclonal structure of the E. faecium isolates. All of the isolates carried the same Tn1546-like element containing an IS1251-like insertion sequence, located on a c. 50-kb conjugative plasmid. One of the E. faecium clones, found previously to be endemic in the hospital, was probably the source of the plasmid. The results of the study suggest that difficulties in identification may have led to an underestimate of the importance of E. raffinosus in vancomycin-resistant enterococci (VRE) control strategies.

Better efficacy of methotrexate given by intramuscular injection than orally in patients with rheumatoid arthritis

OBJECTIVE

To compare the clinical efficacy of methotrexate and tolerance to the drug in patients with rheumatoid arthritis who were switched from intramuscular to oral administration because of a shortage of the intramuscular preparation.

METHODS

143 patients were switched from intramuscular to oral methotrexate. Of these, 47 were switched back to the intramuscular form. A multiple choice questionnaire was sent by mail to evaluate clinical and biological criteria of efficacy and tolerance.

RESULTS

When methotrexate was first switched from intramuscular to oral administration, increased disease activity, exacerbation of morning pain and hand stiffness, duration of morning stiffness, increased joint pain, and increased joint swelling were observed. There was a greater frequency of gastrointestinal symptoms, but without a significant increase in liver abnormalities. When intramuscular methotrexate became available again, 47 of the 143 patients were switched back and were followed for at least three months. On average, disease manifestations were improved and side effects reduced by the switch.

CONCLUSIONS

Methotrexate given intramuscularly had improved clinical efficacy with fewer side effects than given orally. Intramuscular methotrexate administration should be considered when rheumatoid arthritis remains active in spite of high dose oral methotrexate.

Rheumatoid arthritis after 9 years of human immunodeficiency virus infection: possible contribution of tritherapy

Infection by human immunodeficiency virus (HIV) may affect joints in different ways. It usually increases the severity of reactive arthritis. Conversely, when rheumatoid arthritis (RA) is seen in association with HIV infection, remission of RA has been observed in some cases. We describe a patient who developed 3 successive forms of joint manifestations: early HIV related arthralgias followed by drug related arthritis, and more recently by typical RA. The first signs of joint manifestations started one year after HIV seroconversion and resolved when antiviral treatment with AZT was started. The second episode ended when lamivudine dosage was reduced. Finally, after 9 years of infection, the diagnosis of seropositive RA was made in this HLA-DR1 positive patient. The symptoms started when the immune status reached normal CD4 T cell levels, in response to antiviral tritherapy. This observation indicates the complex effect of HIV on joint inflammation.