Aims

The aim of this study was to analyse the effect of altered viewing perspectives on the measurement of the glenopolar angle (GPA) and the differences between these measurements made on 3D CT reconstructions and anteroposterior (AP) scapular view radiographs.

Objective

To investigate the biomechanical mechanism and report preliminary clinical efficacy of eccentric rotational acetabular osteotomy (ERAO) when conduct treatment for developmental dysplasia of the hip (DDH).

Objective

To investigate the biomechanical basis and report preliminary clinical efficacy of eccentric rotational acetabular osteotomy (ERAO) when treating developmental dysplasia of the hip (DDH).

Implant-related infection (IRI) is closely related to the local immunity of peri-implant tissues. The generation of reactive oxygen species (ROS) in activated macrophages plays a prominent role in the innate immune response. In previous studies, we indicated that implant wear particles promote endotoxin tolerance by decreasing the release of proinflammatory cytokines. However, it is unclear whether ROS are involved in the damage of the local immunity of peri-implant tissues. In the present study, we assessed the mechanism of local immunosuppression using titanium (Ti) particles and/or lipopolysaccharide (LPS) to stimulate RAW 264.7 cells. The results indicate that the Ti particles induced the generation of a moderate amount of ROS through nicotinamide adenine dinucleotide phosphate oxidase-1 (NOX-1), but not through catalase. Pre-exposure to Ti particles inhibited ROS generation and extracellular regulated protein kinase (ERK) activation in LPS-stimulated macrophages. These findings indicate that chronic stimulation by Ti particles may lead to a state of oxidative stress and persistent inflammation, which may result in the attenuation of the immune response of macrophages to bacterial components such as LPS. Eventually, immunosuppression develops in peri-implant tissues, which may be a risk factor for IRI.

Osteotomy in spine and skull base surgery is a highly demanding task that requires very high precision. Compared to conventional surgical tools, laser allows contactless hard tissue removal with fewer traumas to the patient and higher machining accuracy. However, a key issue remains unsolved: how to terminate the ablation while the underlying critical soft tissue is reached?

Our research group has realised a closed-loop control of a CO₂-laser osteotomy system under the guidance of an optical coherence tomography (OCT). The OCT provides three-dimensional information about the microstructures beneath the bone surface with a resolution on micrometre scale and an imaging depth of about 0.5 mm. The OCT and CO₂-laser systems are integrated using a coaxial setup and a registration between their working spaces (mean absolute error 19.6 μm) was performed.

The laser ablation and OCT scan are performed in turn. After correction of image distortions and speckle noise reduction, the position of the critical structure can be segmented in the enhanced OCT scans. The laser parameters for the next round of ablation are foresightedly planned based on the overlying residual bone thickness. After patient motion compensation by tracking artificial landmarks in the OCT scans (accuracy: RMS 27.2 μm), the ablation pattern can be precisely carried out by the CO₂-laser. The system was evaluated by performing laser cochleostomy on native porcine cochlea and mean ablation accuracy of 30 μm has been achieved.

However, for narrow incisions that are only several tens of micrometres wide, very few pixels are visible beneath the incision bottom in the OCT and a robust segmentation of the critical structure is impossible. We are now developing a hybrid control system, which monitors the ablation-induced acoustic emission (AE) as a secondary control mechanism in addition to the OCT.

When a pre-defined “switching” depth is reached, the AE-based control module is activated. Instead of analysing the acquired signals with conventional Fourier transform, a wavelet transform-based approach has been developed, which compares the correlation coefficients of the wavelet spectra of successive laser pulses. At the transition from bone tissue to the underlying soft tissue layer, a significant change in the coefficients can be observed, which is regarded as the signal for terminating the ablation. In order to keep the injury to the soft tissue layer to a minimal level, the laser energy is reduced after the switching. Preliminary experiments revealed that the wavelet-based approach is capable of controlling the ablation using pulses with extremely low energy down to 0.04mJ/pulse, resulting in an injured tissue layer of less than 10 μm.

We expect to achieve the ablation accuracy on tens of micrometre scale using the proposed hybrid control mechanism.

Objective

The objective of this study was to evaluate the rotation and translation of each joint in the hindfoot and compare the load response in healthy feet with that in stage II posterior tibial tendon dysfunction (PTTD) flatfoot by analysing the reconstructive three-dimensional (3D) computed tomography (CT) image data during simulated weight-bearing.

In a retrospective cohort study we compared the clinical outcome and complications, including dysphagia, following anterior cervical fusion for the treatment of cervical spondylosis using either a zero-profile (Zero-P; Synthes) implant or an anterior cervical plate and cage. A total of 83 patients underwent fusion using a Zero-P and 107 patients underwent fusion using a plate and cage. The mean follow-up was 18.6 months (sd 4.2) in the Zero-P group and 19.3 months (sd 4.1) in the plate and cage group. All patients in both groups had significant symptomatic and neurological improvement. There were no significant differences between the groups in the Neck Disability Index (NDI) and visual analogue scores at final follow-up. The cervical alignment improved in both groups. There was a higher incidence of dysphagia in the plate and cage group on the day after surgery and at two months post-operatively. All patients achieved fusion and no graft migration or nonunion was observed.

When compared with the traditional anterior cervical plate and cage, the Zero-P implant is a safe and convenient procedure giving good results in patients with symptomatic cervical spondylosis with a reduced incidence of dysphagia post-operatively.

Cite this article: Bone Joint J 2013;95-B:543–7.

Introduction

To introduce a new classification method and analyze related risk factor about lateral wall perforation associated with lower cervical pedicle screw and free-hand insertion technique.

Study Design

Retrospective review.

Introduction

How translation of different parts of spine responds to selective thoracic fusion has not been well investigated. Furthermore, how posterior pedicle-screw-only constructs affect spontaneous lumbar curve correction (SLCC) remains unknown. In a retrospective study, we aimed to investigate the balance change after selective thoracic fusion in Lenke 1C type adolescent idiopathic scoliosis (AIS) treated with posterior pedicle-screw-only constructs.

Progressive arthritis can occur in association with massive tears of the rotator cuff. Altered joint kinematics are commonly proposed as the principle causative factor but this does not explain the absence of arthropathy in some patients. We have investigated the role of the ANKH gene in patients with cuff tear arthropathy. The transmembrane protein ANKH promotes intracellular to extracellular inorganic pyrophosphate channelling which regulates calcium pyrophosphate dihydrate and hydroxyapatite crystal deposition. Genomic DNA was prepared from peripheral blood leucocytes from 20 patients with cuff tear arthropathy diagnosed clinically and radiologically and 24 healthy matched controls. All 12 exons and exon-intron boundaries from the ANKH gene were PCR amplified and sequenced with BigDye version 3.1 terminator kit (ABI), and analysed using ABI PRISM ® 3100 Genetic Analyser. We have identified 5 single nucleotide polymorphisms (SNPs) including 4 that have previously been identified in patients with chondrocalcinosis. These are in exon 2 (GCC†’GCT 294), intron 2 (G†’A +8), exon 8 (GCA†’GCG 963) and intron 8 (T†’G +15). We also identified an A†’G variant in 3′-UTR, 30 base pairs after the stop codon which has not been reported before in crystal deposition diseases, and is also not seen in any of the healthy controls. Further elucidation is necessary to demonstrate a causal relationship between these ANKH mutations and cuff tear arthropathy, which will add to our understanding of pathogenic mechanisms in this condition.

Cuff Tear Arthropathy is characterised by massive rotator cuff tears, glenohumeral joint destruction and joint effusions containing basic calcium phosphate and calcium pyrophosphate dihydrate crystals. We have investigated the role of the ANKH gene in patients with cuff tear arthropathy and the effect of mutations on protein function. The transmembrane protein ANKH transports inorganic pyrophosphate (PPi) from the intracellular to extracellular space. Control of the extracellular levels of PPi is crucial in preventing calcium crystal formation. Genomic DNA was prepared from peripheral blood leucocytes from 22 patients with cuff tear arthropathy diagnosed clinically and radiologically. All 12 exons and exon-intron boundaries from the ANKH gene were PCR amplified and sequenced with BigDye version 3.1 terminator kit (ABI), and analysed using ABI PRISM ® 3100 Genetic Analyser. ANKH complementary DNA (cDNA) was ligated with mammalian expression vector pcDNA3 and site directed mutagenesis was used to make the ANKH mutation detected in the cases. Human articular chondrocytes were transfected with the cDNA variants and PPi concentrations measured. A G-to-A single nucleotide polymorphism in the 3′ untranslated region (3′UTR) of ANKH was identified. The G/A genotype was seen more frequently in the cases (45%) when compared to controls (20%) (p= 0.0008). We observed altered levels of extracellular PPi in human chondrocytes transfected with ANKH cDNA with the 3′ UTR variant when compared with control cells and normal ANKH cDNA. Cuff Tear Arthropathy appears to be heritable via a G-to-A transition in the 3′UTR of ANKH that alters extracellular PPi concentrations in chondrocyte cells. This supports a hypothesis of a primary crystal mediated arthropathy in patients with Cuff Tear Arthropathy.