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Orthopaedic Proceedings
Vol. 102-B, Issue SUPP_7 | Pages 66 - 66
1 Jul 2020
Tat J Chong J Powell T Martineau PA
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Anterior shoulder instability is associated with osseous defects of the glenoid and/or humeral head (Hill-Sachs lesions). These defects can contribute to the pathology of instability by engaging together. There is a need to continue to develop methods to preoperatively identify engaging Hill-Sachs lesions for determining appropriate surgical management.

The objective was to created a working moveable 3D CT model that allows the user to move the shoulder joint into various positions to assess the relationship between the Hill-Sachs lesion and the anterior glenoid rim. This technique was applied to a cohort series of 14 patients with recurrent anterior dislocation: 4 patients had undergone osteoarticular allografting of Hill-Sachs lesions and 10 control patients had undergone CT scanning to quantify bone loss but had no treatment to address bony pathology. A biomechanical analysis was performed to rotate each 3D model using local coordinate systems through a functional range using an open-source 3D animation program, Blender (Amsterdam, Netherlands). A Hill-Sachs lesion was considered “dynamically” engaging if the angle between the lesion's long axis and anterior glenoid was parallel.

In the classical vulnerable position of the shoulder (abduction=90, external rotation=0–135), none of the Hill-Sachs lesions aligned with the anterior glenoid in any of our patients (Figure 1). Therefore, we considered there to be a “low risk” of engagement in these critical positions, as the non-parallel orientation represents a lack of true articular arc mismatch and is unlikely to produce joint instability. We then expanded our search and simulated shoulder positions throughout a physiological range of motion for all groups and found that 100% of the allograft patients and 70% of the controls had positions producing alignment and were “high risk” of engagement (p = 0.18) (Table 1). We also found that the allograft group had a greater number of positions that would engage (mean 4 ± 1 positions of engagement) compared to our controls (mean 2 ± 2 positions of engagement, p = 0.06).

We developed a 3D animated paradigm to dynamically and non-invasively visualize a patient's anatomy and determine the clinical significance of a Hill-Sachs lesion using open source software and CT images. The technique demonstrated in this series of patients showed multiple shoulder positions that align the Hill-Sachs and glenoid axes that do not necessarily meet the traditional definition of engagement. Identifying all shoulder positions at risk of “engaging”, in a broader physiological range, may have critical implications towards selecting the appropriate surgical management of bony defects. We do not claim to doubt the classic conceptual definition of engagement, but we merely introduce a technique that accounts for the dynamic component of shoulder motion, and in doing so, avoid limitations of a static criteria assumed traditional definition (like size and location of lesion). Further investigations are planned and will help to further validate the clinical utility of this method.

For any figures or tables, please contact the authors directly.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_20 | Pages 39 - 39
1 Nov 2016
Vallières M Freeman C Zaki A Turcotte R Hickeson M Skamene S Jeyaseelan K Hathout L Serban M Xing S Powell T Goulding K Seuntjens J Levesque I El Naqa I
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This is quite an innovative study that should lead to a multicentre validation trial. We have developed an FDG-PET/MRI texture-based model for the prediction of lung metastases (LM) in newly diagnosed patients with soft-tissue sarcomas (STSs) using retrospective analysis. In this work, we assess the model performance using a new prospective STS cohort. We also investigate whether incorporating hypoxia and perfusion biomarkers derived from FMISO-PET and DCE-MRI scans can further enhance the predictive power of the model.

A total of 66 patients with histologically confirmed STSs were used in this study and divided into two groups: a retrospective cohort of 51 patients (19 LM) used for training the model, and a prospective cohort of 15 patients (two patients with LM, one patient with bone metastases and suspicious lung nodules) for testing the model. In the training phase, a model of four texture features characterising tumour sub-region size and intensity heterogeneities was developed for LM prediction from pre-treatment FDG-PET and MRI scans (T1-weighted, T2-weighted with fat saturation) of the retrospective cohort, using imbalance-adjusted bootstrap statistical resampling and logistic regression multivariable modeling. In the testing phase, this multivariable model was applied to predict the distant metastasis status of the prospective cohort. The predictive power of the obtained model response was assessed using the area under the receiver-operating characteristic curve (AUC). In the exploratory phase of the study, we extracted two heterogeneity metrics from the prospective cohort: the area under the intensity-volume histogram of pre-treatment DCE-MRI volume transfer constant parametric maps and FMISO-PET hypoxia maps (AU-IVH-Ktrans, AU-IVH-FMISO). The impact of the addition of these two individual metrics to the texture-based model response obtained in the testing phase was first investigated using Spearman's correlation (rs), and lastly using logistic regression and leave-one-out cross-validation (LOO-CV) to account for overfitting bias.

First, the texture-based model reached an AUC of 0.94, a sensitivity of 1, a specificity of 0.83 and an accuracy of 0.87 when tested in the prospective cohort. In the exploratory phase, the addition of AU-IVH-FMISO did not improve predictive power, yielding a correlation of rs = −0.42 (p = 0.12) with lung metastases, and a relative change in validation AUC of 0% in comparison with the texture-based model response alone in LOO-CV experiments. In contrast, the addition of AU-IVH-Ktrans improved predictive power, yielding a correlation of rs = −0.54 (p = 0.04) with lung metastases, and a change in validation AUC of +10%.

Our results demonstrate that texture-based models extracted from pre-treatment FDG-PET and MRI anatomical scans could be successfully used to predict distant metastases in STS cancer. Our results also suggest that the addition of perfusion heterogeneity metrics may contribute to improving model prediction performance.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XV | Pages 3 - 3
1 Apr 2012
Guyver P Powell T Fern ED Norton M
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Introduction

Femoroacetabular impingement (FAI) is a relatively recent recognised condition and a potential cause of anterior hip pain in the young military adult population. Both Cam and Pincer type FAI may lead to inflammation, labral tears, and or damage to the smooth articular cartilage of the acetabulum leading potentially to early osteoarthritis of the hip. Open Surgical hip dislocation using the Ganz Trochanteric Flip approach is an accepted technique allowing osteoplasty of the femoral neck and acetabular rim combined with labral repair if required. We present our results of this technique used in military personnel.

Methods

All Military personnel who underwent FAI surgery in our unit since August 2006 were included in the study. Functional outcome was measured using the Oxford hip and McCarthy non-arthritic hip scores pre and post-operatively. Results: 13 hips in 11 patients with an average age of 36 years (21–45) underwent surgical hip dislocation for treatment of FAI. Average time of downgrading prior to surgery was 9.3(3-18) months. 6 out of the 11 patients have been upgraded to P2. Average time to upgrading was 6.8(3-17) months. There were no infections, dislocations, or neurovascular complications. Mean Oxford Hip Score improved from 22.8(range 8–38) to 39.5(11–48) and mean McCarthy hip score from 49.6(33.75–80) to 79.2(36.25–100) with an average follow up of 19.4 months (range 4– 42 months).


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_III | Pages 299 - 299
1 Sep 2005
Hurson C Powell T O’Connell M Ennis R Eustace S
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Introduction and Aims: The aim of this study was to evaluate the role of Whole Body MR (WBMR) in the staging of Musculo Skeletal (MSK) tumors, on a premise that a single study might present an alternative to the traditional imaging.

Method: Forty-two patients were referred for MR evaluation for primary bone or soft tissue sarcomas. These studies were done between October 2001 and April 2003. Each patient had a WBMR, Localised MR, CXR and CT Thorax, and bone scan.

Results: In 42 patients screened, 32 had a primary malignant musculo skeletal tumor. There were 14 primary bone tumors and 18 soft tissue sarcomas. Of the 32 patients concordance between WBMR imaging and the other staging modalities was identified in 27 patients. Discordance was identified in five patients. Two lesions were identified on WBMR and not seen on other imaging modalities. Two lesions not identified by WBMR, subsequently seen on CT thorax. One lesion was not seen on WBMR but seen on localised MR. Eight of the 32 patients had pulmonary metastases. In these patients concordance between the WBMR and CT Thorax was identified in five of eight patients and discordance was identified in three of eight patients where nodules were identified on CT Thorax and not on WBMR. Four patients were noted to have osseous metastases, all seen on WBMR. One bone scan failed to pick up metastasis seen on WBMR. One patient was identified as having a soft tissue metastasis on Whole Body MR, which was not identified on the conventional CT Thorax.

Case studies:

Case 1: Metastatic Leiomyosarcoma

Case 2: Metastatic Ewings sarcoma

Case 3: Metastatic Epithelioid sarcoma

Conclusion: Whole body MR Scanning techniques allow whole body imaging in as little as eight minutes. It is a useful technique in staging and assessing total tumor burden, but still should be performed in conjunction with a CT Thorax.


Orthopaedic Proceedings
Vol. 85-B, Issue SUPP_II | Pages 136 - 136
1 Feb 2003
O’Grady P Powell T Synnott K Khan D Eustace S O’Rourke K
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Aims: To investigate the prevalence and significance of a high-intensity zone in a group of patients asymptomatic for low back pain.

Methods: A prospective observational study of the prevalence of abnormal MR imaging in normal volunteers without a significant history of back pain. All volunteers underwent physical examination, psychometric testing, plain radiograph, magnetic resonance imaging, and dexa scanning. Films were blindly assessed for the prevalence of degenerative disc disease, osteoporosis, high intensity zone, disc prolapse and spinal stenosis.

Results: Following history, clinical examination and psychometric testing 13 of 63 (20%) patients were excluded from the study on the basis of previous back injury, leg pain or abnormal clinical findings. 50 volunteers were eligible for inclusion in the study. The presence of a high-intensity zone or annular disruption was determined by standardised criteria on T2-wieghted magnetic resonance images. The prevalence of a high-intensity zone in the patient population was 12 of 50 patients (24%). 32% of all disc prolapses were at the L4/5 level, 33% were at L5/S1 and 17% were at L3/4 the remainder were at various other levels.

Conclusions: The presence of a high-intensity zone does not reliably indicate the presence of symptomatic internal disc disruption. Magnetic resonance imaging is accurate in determining nuclear anatomy, however positive findings do not always correlate with history and clinical findings. The presence of abnormal imaging in asymptomatic patients reinforces the need for a detailed history and clinical examination in the evaluation of the lumbar spine.