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The Bone & Joint Journal
Vol. 103-B, Issue 4 | Pages 725 - 733
1 Apr 2021
Lai MKL Cheung PWH Samartzis D Karppinen J Cheung KMC Cheung JPY

Aims

The aim of this study was to determine the differences in spinal imaging characteristics between subjects with or without lumbar developmental spinal stenosis (DSS) in a population-based cohort.

Methods

This was a radiological analysis of 2,387 participants who underwent L1-S1 MRI. Means and ranges were calculated for age, sex, BMI, and MRI measurements. Anteroposterior (AP) vertebral canal diameters were used to differentiate those with DSS from controls. Other imaging parameters included vertebral body dimensions, spinal canal dimensions, disc degeneration scores, and facet joint orientation. Mann-Whitney U and chi-squared tests were conducted to search for measurement differences between those with DSS and controls. In order to identify possible associations between DSS and MRI parameters, those who were statistically significant in the univariate binary logistic regression were included in a multivariate stepwise logistic regression after adjusting for demographics. Odds ratios (ORs) and 95% confidence intervals (CIs) were reported where appropriate.


The Bone & Joint Journal
Vol. 103-B, Issue 1 | Pages 131 - 140
1 Jan 2021
Lai MKL Cheung PWH Samartzis D Karppinen J Cheung KMC Cheung JPY

Aims

To study the associations of lumbar developmental spinal stenosis (DSS) with low back pain (LBP), radicular leg pain, and disability.

Methods

This was a cross-sectional study of 2,206 subjects along with L1-S1 axial and sagittal MRI. Clinical and radiological information regarding their demographics, workload, smoking habits, anteroposterior (AP) vertebral canal diameter, spondylolisthesis, and MRI changes were evaluated. Mann-Whitney U tests and chi-squared tests were conducted to search for differences between subjects with and without DSS. Associations of LBP and radicular pain reported within one month (30 days) and one year (365 days) of the MRI, with clinical and radiological information, were also investigated by utilizing univariate and multivariate logistic regressions.


The Bone & Joint Journal
Vol. 102-B, Issue 10 | Pages 1375 - 1383
3 Oct 2020
Zhang T Sze KY Peng ZW Cheung KMC Lui YF Wong YW Kwan KYH Cheung JPY

Aims

To investigate metallosis in patients with magnetically controlled growing rods (MCGRs) and characterize the metal particle profile of the tissues surrounding the rod.

Methods

This was a prospective observational study of patients with early onset scoliosis (EOS) treated with MCGRs and undergoing rod exchange who were consecutively recruited between February 2019 and January 2020. Ten patients were recruited (mean age 12 years (SD 1.3); 2 M:8 F). The configurations of the MCGR were studied to reveal the distraction mechanisms, with crucial rod parts being the distractable piston rod and the magnetically driven rotor inside the barrel of the MCGR. Metal-on-metal contact in the form of ring-like wear marks on the piston was found on the distracted portion of the piston immediately outside the barrel opening (BO) through which the piston rod distracts. Biopsies of paraspinal muscles and control tissue samples were taken over and away from the wear marks, respectively. Spectral analyses of the rod alloy and biopsies were performed to reveal the metal constituents and concentrations. Histological analyses of the biopsies were performed with haematoxylin and eosin staining.


The Bone & Joint Journal
Vol. 102-B, Issue 4 | Pages 519 - 523
1 Apr 2020
Kwan KYH Koh HY Blanke KM Cheung KMC

Aims

The purpose of this study was to evaluate the incidence and analyze the trends of surgeon-reported complications following surgery for adolescent idiopathic scoliosis (AIS) over a 13-year period from the Scoliosis Research Society (SRS) Morbidity and Mortality database.

Methods

All patients with AIS between ten and 18 years of age, entered into the SRS Morbidity and Mortality database between 2004 and 2016, were analyzed. All perioperative complications were evaluated for correlations with associated factors. Complication trends were analyzed by comparing the cohorts between 2004 to 2007 and 2013 to 2016.


The Bone & Joint Journal
Vol. 99-B, Issue 10 | Pages 1381 - 1388
1 Oct 2017
Wong YW Samartzis D Cheung KMC Luk K

Aims

To address the natural history of severe post-tuberculous (TB) kyphosis, with focus upon the long-term neurological outcome, occurrence of restrictive lung disease, and the effect on life expectancy.

Patients and Methods

This is a retrospective clinical review of prospectively collected imaging data based at a single institute. A total of 24 patients of Southern Chinese origin who presented with spinal TB with a mean of 113° of kyphosis (65° to 159°) who fulfilled inclusion criteria were reviewed. Plain radiographs were used to assess the degree of spinal deformity. Myelography, CT and MRI were used when available to assess the integrity of the spinal cord and canal. Patient demographics, age of onset of spinal TB and interventions, types of surgical procedure, intra- and post-operative complications, and neurological status were assessed.


The Bone & Joint Journal
Vol. 97-B, Issue 7 | Pages 973 - 981
1 Jul 2015
Fong DYT Cheung KMC Wong YW Cheung WY Fu ICY Kuong EE Mak KC To M Samartzis D Luk KDK

Randomised controlled trials (RCTs) that assessed the efficacy of bracing for adolescent idiopathic scoliosis have suffered from small sample sizes, low compliance and lack of willingness to participate. The aim of this study was to assess the feasibility of a comprehensive cohort study for evaluating both the efficacy and the effectiveness of bracing in patients with adolescent idiopathic scoliosis. Patients with curves at greater risk of progression were invited to join a randomised controlled trial. Those who declined were given the option to remain in the study and to choose whether they wished to be braced or observed. Of 87 eligible patients (5 boys and 63 girls) identified over one year, 68 (78%) with mean age of 12.5 years (10 to 15) consented to participate, with a mean follow-up of 168 weeks (0 to 290). Of these, 19 (28%) accepted randomisation. Of those who declined randomisation, 18 (37%) chose a brace. Patients who were more satisfied with their image were more likely to choose bracing (Odds Ratio 4.1; 95% confidence interval 1.1 to 15.0; p = 0.035). This comprehensive cohort study design facilitates the assessment of both efficacy and effectiveness of bracing in patients with adolescent idiopathic scoliosis, which is not feasible in a conventional randomised controlled trial.

Cite this article: Bone Joint J 2015; 97-B:973–81


Orthopaedic Proceedings
Vol. 96-B, Issue SUPP_15 | Pages 10 - 10
1 Oct 2014
Cheung KMC Cheung JPY Kwan K Ferguson J Nnadi C Alanay A Yazici M Demirkiran G Helenius IJ Akbarnia B
Full Access

The magnetically controlled growing rod (MCGR) system allows growth maintenance without the risk of anaesthesia, implant and wound complications associated with repeated surgeries. This is a medium-term report of the complications of MCGR from a multicentre study.

Twenty-six patients from 6 spine institutes that are part of a multicentre study with prospectively collected data of minimum 24 months follow-up were assessed. Pre-operative, immediate post-operative and most recent spine radiographs were reviewed to measure the Cobb angle and the rod lengthening distance. The causes and any associated risk factors for re-operations were examined.

Eleven patients required re-operation within the follow-up period, with a mean time to re-operation of 17 months after the initial surgery. Five were due to failure of rod distractions; 3 were due to failure of proximal foundation implants; 2 were due to rod breakage; and one case of superficial wound infection with failure of proximal fixation. Proximal junctional kyphosis occurred in 5 patients. Three had proximal anchor dislodgement and all five constructs were revised.

This is the largest series with the longest follow-up to date. Our series show that the perception that using MCGR may reduce the frequency of re-operations may not be entirely true. This is the first report to examine the need for re-operation after MCGR implantation, and highlights the inherent risks of any surgical treatment in this group of patients despite the advantages of this new implant. Longer-term studies and comparisons with traditional growing rods are required.


The Bone & Joint Journal
Vol. 95-B, Issue 7 | Pages 972 - 976
1 Jul 2013
Chang KC Samartzis D Fuego SM Dhatt SS Wong YW Cheung WY Luk KDK Cheung KMC

Transarticular screw fixation with autograft is an established procedure for the surgical treatment of atlantoaxial instability. Removal of the posterior arch of C1 may affect the rate of fusion. This study assessed the rate of atlantoaxial fusion using transarticular screws with or without removal of the posterior arch of C1. We reviewed 30 consecutive patients who underwent atlantoaxial fusion with a minimum follow-up of two years. In 25 patients (group A) the posterior arch of C1 was not excised (group A) and in five it was (group B). Fusion was assessed on static and dynamic radiographs. In selected patients CT imaging was also used to assess fusion and the position of the screws. There were 15 men and 15 women with a mean age of 51.2 years (23 to 77) and a mean follow-up of 7.7 years (2 to 11.6). Stable union with a solid fusion or a stable fibrous union was achieved in 29 patients (97%). In Group A, 20 patients (80%) achieved a solid fusion, four (16%) a stable fibrous union and one (4%) a nonunion. In Group B, stable union was achieved in all patients, three having a solid fusion and two a stable fibrous union. There was no statistically significant difference between the status of fusion in the two groups. Complications were noted in 12 patients (40%); these were mainly related to the screws, and included malpositioning and breakage. The presence of an intact or removed posterior arch of C1 did not affect the rate of fusion in patients with atlantoaxial instability undergoing C1/C2 fusion using transarticular screws and autograft.

Cite this article: Bone Joint J 2013;95-B:972–6.


The Bone & Joint Journal
Vol. 95-B, Issue 2 | Pages 206 - 209
1 Feb 2013
Samartzis D Modi HN Cheung KMC Luk KDK

Ankylosing spondylitis (AS) is a progressive multisystem chronic inflammatory disorder. The hallmark of this pathological process is a progressive fusion of the zygapophyseal joints and disc spaces of the axial skeleton, leading to a rigid kyphotic deformity and positive sagittal balance. The ankylosed spine is unable to accommodate normal mechanical forces, rendering it brittle and susceptible to injury. Traumatic hyperextension injury of the cervical spine leading to atlantoaxial subluxation (AAS) in AS patients can often be fatal. We report a non-traumatic mechanism of injury in AS progressing to AAS attributable to persistent hyperextension, which resulted in fatal migration of C2 through the foramen magnum.

Cite this article: Bone Joint J 2013;95-B:206–9.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXVII | Pages 39 - 39
1 Jun 2012
Fan Y Cheung KMC Chan D Cheung W Cheah KSE Sham P Luk KDK Song Y
Full Access

Introduction

The cause of adolescent idiopathic scoliosis (AIS) is still not known. Although several candidate gene studies and linkage analyses have been done, no causal relationship has yet been established. To our knowledge, we report the first case-control based genome-wide association study (GWAS) for this trait.

Methods

The study was undertaken in a set of 196 cases with a specific AIS phenotype (based on Lenke's classification) in southern China, and in 401 controls without radiological evidence of scoliosis.