Dupuytrens disease is a fibrosing condition of the palmar aponeurosis and its extensions within the digits. Normal fascial fibres running longitudinally in the subcutaneous tissues of the palm become thickened and form the characteristic nodules and cords pathognomonic of Dupuytrens disease. A wide variety of surgical interventions exist, of these the partial fasciectomy remains the most conventional and widely used technique. Minimally invasive surgical treatments such as needle fasciotomy are, however, becoming increasingly popular. Dupuytrens disease remains a challenging condition to treat as recurrence is universally found with all surgical interventions. Although recurrence may be related to the severity of the disease, there are currently no research tools other than clinical examination to examine changes in the diseased tissue postoperatively and predict likelihood of long-term success. Magnetic Resonance Imaging (MRI) may be of value for the study of Dupuytren disease, at present its use has been greatly underexplored. We wished to carry out a pilot study in order to examine the possibility of using 3.0 Tesla MRI to study Dupuytren tissue and then furthermore to examine the potential changes post-operatively following percutaneous fasciotomy. Five patients set to undergo percutaneous needle fasciotomy were recruited and consented for the study. All patients underwent MRI scanning of the affected hand pre-operatively and at two weeks post-operatively. Scanning was carried out in the 3.0 Tesla research MRI scanner at Aberdeen Royal Infirmary. Patients were placed prone in the MRI scanner with the hand outstretched above the head in the so-called “Superman” position. A specially designed wrist and hand coil was used. Under the expertise of radiographers and physicists, image capture encompassed four novel scanning sequences in order to make a volumetric three-dimensional image sample of the affected hand. MIPAV software (Bethesda, Maryland) was used for image analysis. Scanning revealed well defined anatomy. The Dupuytren cord arose from the palmar aponeurosis tissue which is deep to the palmar skin and subcutaneous tissue. It was distinctly different to deep structures such as the flexor tendons and intrinsic hand muscles which appeared with a uniform low and high signal respectively. The Dupuytren tissue had a heterogeneous signal on both T1 and T2 images. On T1 the tissue signal appeared high to intermediate, similar to that of bone and muscle, but low areas of signal were observed diffusely in an irregular fashion throughout. On T2 the tissue had a low signal throughout with some focal areas of high signal. Dupuytren tissue was mapped using MIPAV software for pre- and post-operative comparisons. Signal intensity, surface area and volume of the cords and fasciotomy sites were explored. Our initial results suggest MRI can be used to study Dupuytren tissue. Such a research tool may be of use to study the natural history of Dupuytren disease and furthermore, the response to medical and surgical interventions

Aim. The aim of this study was to compare the diagnostic accuracy of the Magnetic Resonance Imaging with that of Stress views of the ankle in testing the integrity of the lateral ankle ligaments. Arthroscopic diagnosis was used as the gold standard. Methods. This was a prospective study involving 45 patients who had previous trauma to the ankle and reported symptoms of ankle instability. Our patients were recreational athletes or military patients. These patients had MRI evaluation prior to arthroscopic evaluation and treatment of the ankle. The diagnosis regarding the integrity of the Calcaneofibular ligament (CFL) and the Anterior Talo-fibular ligament (ATFL), as obtained from the MRI was compared against the assessment of integrity from the stress views. These were compared against the assessment made by direct visualisation of the ligaments during arthroscopy. The sensitivity, specificity, negative (NPV) and positive predictive values (PPV) and accuracy were then calculated. Results. The sensitivity and specificity of the MRI and the stress views were poor for diagnosis of ATFL tears. However, the stress views had better sensitivity (93.7%) and specificity (96.5%), for the CFL, as compared with those of the Magnetic Resonance scans (sensitivity 50% and specificity of 86.2%). There was a difference between the diagnostic accuracy of the two methods of investigation with respect to integrity of the CFL but not of that of the ATFL. The PPV and the NPV for the ATFL was comparable using the MRI and the stress radiographs, the stress radiographs had a better predictive values for the calcaneo-fibular ligament, PPV of 93.7% and NPV of 96.5%. Conclusion. The results of this study suggest that routine pre-operative Magnetic Resonance Imaging is not beneficial or cost effective in diagnosing lateral ligament

Introduction. In degenerative lumbar spine, it seems possible that foraminal stenosis is over-diagnosed as axial scanning is not performed in the plane of the exiting nerve root. We carried out a two-part study to determine the true incidence of foraminal stenosis. Patients and Methods. Initially we performed a retrospective analysis of radiology reports of conventional Magnetic Resonance Imaging in 100 cases of definite spinal stenosis to determine the incidence of reported ‘foraminal stenosis’. Subsiquently we performed a prospective study of MRI including fine slice T2 and T2 STIR coronal sequences in 100 patients with suspected stenosis. Three surgeons and one radiologist independently compared the diagnoses on conventional axial and sagittal sequences with the coronal scans. Results. The retrospective analysis found that ‘foraminal stenosis’ was reported by radiologists in 46% using conventional axial and sagittal sequences. In the prospective study of 100 patients suspected of having stenosis, spinal stenosis was reported in 40; degenerative spondylolisthesis in 14; posterolateral disc herniation in 14; normal report in 13; far lateral disc herniation in 7; isthmic (lytic) spondylolisthesis in 6; and degenerative scoliosis in 6. Conventional sequences diagnosed lateral recess stenosis reliably, but also suggested foraminal stenosis in 43%. However, coronal sequences clearly showed no foraminal nerve compression at all. In degenerative spondylolisthesis conventional scans suggested foraminal stenosis in 10 of 14 cases. Coronal imaging again showed no foraminal stenosis. Excellent correlation was found in normal spines and in disc herniation. Foraminal nerve compression was confirmed by conventional and coronal imaging only in isthmic spondylolisthesis, degenerative scoliosis and far lateral disc herniation. Conclusion. The addition of coronal MRI proves that foraminal stenosis is over-diagnosed. True foraminal stenosis definitely exists in isthmic spondylolisthesis, degenerative scoliosis and far lateral disc herniation, but we question its existence in spinal stenosis and degenerative spondylolisthesis

Abstract

MRI has been little utilised in the post-operative assessment of joint replacement due to the problem of artifact. With modern machines and sequencing, artifact can be minimised in small joints with titanium prostheses. Twenty four consecutive patients implanted with a Buechel-Pappas Total Ankle Replacement underwent MRI examination at an average of 583 days post surgery to determine its usefulness as an adjunct to x-ray and bone scan in assessing prosthetic integrity and the source of post-operative symptoms.

The purpose of the study was to evaluate the use of modified MRI techniques in the assessment of bone-implant interface, soft tissue changes, bone oedema and extent of osteolysis in setting of total ankle joint replacement and propose a descriptive classification to document the changes.

We found MRI was extremely useful in identifying abnormalities in structures apart from the prosthesis such as occult degeneration in the subtalar joint and ligament pathology. Despite the new techniques, artifact remains a problem when assessing the bone prosthesis interface although adjacent bone oedema is well seen.

MRI has a role in the identification of pathology in the tissues surrounding a TAJR especially with unexplained pain in an otherwise well functioning prosthesis. It's role in the assessment of prosthetic integrity remains qualitative but further work will be required to correlate MRI findings with clinical examination.

Introduction:

Unicompartmental knee arthroplasty (UKA) is a well established method for treatment of single compartment arthritis. However, a subset of patients still present with continued pain after their procedure in the setting of a normal radiographic examination. We propose the use of magnetic resonance imaging (MRI) as a useful modality in determining the etiology of symptoms in symptomatic unicompartmental knee arthroplasties.

Aim

This study aims to determine the value of MRI in children with hip pain which remained unexplained following routine investigations including ultrasound examination.

Osteophytes are bony spurs on normal bone that develop as an adaptive reparative process due to excessive stress at/near a joint. As osteophytes develop from normal bone, they are not always well depicted in common imaging techniques (e.g. CT, MRI). This creates a challenge for preoperative planning and image-guided surgical methods that are commonly incorporated in the clinical routine of orthopaedic surgery.

The study examined the accuracy of osteophyte detection in clinical CT and MRI scans of varying types of joints.

The investigation was performed on fresh-frozen ex-vivo human resected joints identified as having a high potential for presentation of osteophytes. The specimens underwent varying imaging protocols for CT scanning and clinical protocols for MRI. After dissection of the joint, the specimens were subjected to structured 3D light scanning to establish a reference model of the anatomy. Scans from the imaging protocols were segmented and their 3D models were co-registered to the light scanner models. The quality of the osteophyte images were evaluated by determining the Root Mean Square (RMS) error between the segmented osteophyte models and the light scan model.

The mean RMS errors for CT and MRI scanning were 1.169mm and 1.419mm, respectively. Comparing the different CT parameters, significance was achieved with scanning at 120kVp and 1.25mm slice thickness to depict osteophytes; significance was also apparent at a lower voltage (100kVp).

Preliminary results demonstrate that osteophyte detection may be dependent on the degree of calcification of the osteophyte. They also illustrate that while some imaging parameters were more favourable than others, a more accurate osteophyte depiction may result from the combination of both MRI and CT scanning.

There is a difference of opinion regarding the usefulness of MR Imaging as a diagnostic tool for triangular fibrocartilage complex (TFCC) tears in the wrist. Our aim was to determine the accuracy of direct magnetic resonance arthrography (MRA) in the diagnosis of triangular fibrocartilage complex (TFCC) tears of the wrist in a district general hospital setting.

In a retrospective review of 21 patients who presented with complains of wrist pain and following a clinical examination, all had direct MR arthrography of the wrist in our hospital in a 1.5Tesla scanner. All had a diagnostic arthroscopy within 2-4 months of the MR scan. All patients had chronic ulnar sided wrist pain, although only two had a definite history of trauma. The findings of each diagnostic method were compared, with arthroscopy considered the gold standard.

Twenty-one patients were studied (10 male: 11 female), mean age 42 years (range 27-71) years). Seventeen TFCC tears were diagnosed on arthroscopy. For the diagnosis of TFCC tears MRA had a sensitivity, specificity and accuracy of 67%.

Our results echoed the opinion of some of the previous investigators with an unacceptable sensitivity or specificity for a diagnostic tool. MR arthrography needs to be further refined as a technique before it can be considered to be accurate enough to replace wrist arthroscopy for the diagnosis of TFCC tears. Other centres have reported better accuracy, using more advanced MRI technology. Until this iswidely available at all levels of healthcare the results of MRI for the diagnosis of TFCC tears should be interpreted with caution.

Glenohumeral arthritis is associated with eccentric posterior glenoid wear and subsequent retroversion. Total shoulder arthroplasty provides a reliable and robust solution for this pattern of arthritis but success may be tempered by malposition of the glenoid component, resulting in pain, functional impairment, prosthetic loosening and ultimately failure. Correction of glenoid retroversion through anterior eccentric reaming, prior to glenoid component implantation, is performed to restore normal joint biomechanics and maximise implant longevity.

The aim of this study was to assess whether magnetic resonance imaging (MRI) or plain axillary radiography (XR) most accurately assessed glenoid version and hence provided the optimal modality for pre-operative templating.

Glenoid version was assessed in pre-operative shoulder MRIs and axillary radiographs (XR) by two independent observers in forty-eight consecutive patients undergoing total shoulder arthroplasty.

The mean glenoid version measured on magnetic resonance imaging was −14.3 degrees and −21.6 degrees on axillary radiographs (mean difference −7.36, p=<0.001). Glenoid retroversion was overestimated in 73% of XRs. Intra-observer and inter-observer reliability coefficients for MRI were 0.96 and 0.9 respectively. Intra-observer and inter-observer reliability coefficients for XR were 0.8 and 0.71 respectively.

Axillary radiographs significantly overestimate glenoid retroversion and are less precise than shoulder magnetic resonance, which provides excellent intra- and inter-observer reliability. MRI is a useful pre-operative osseous imaging modality for total shoulder arthroplasty as it offers a more precise method of determining glenoid version, in addition to the standard assessment rotator cuff integrity.

Introduction

Current techniques in total knee arthroplasty aim to restore the coronal mechanical axis to neutral. Preoperative planning has historically been based on long-leg standing films (LLSF) which allow surgeons to plan bony resection and soft tissue releases. However, LSSF can be prone to error if malrotated. Recently, patient-specific guides (PSG) utilizing supine magnetic resonance imaging (sMRI) have become an accepted technique for preoperative planning. In this study we sought to compare the degree of coronal deformity using LLSF and sMRI.

The use of peritumoral oedema on magnetic resonance (MR) imaging to predict soft tissue tumour grade is controversial. The clinical significance of oedema visualised on MR scans is poorly defined in the literature. We undertook this study to ascertain a diagnostic relationship between peritumoral oedema surrounding soft tissue sarcomas and the histological grade of the tumour.

One hundred and ten consecutive soft tissue tumours were extracted from the New Zealand Bone and Soft Tissue Tumour Registry. Key inclusion criteria were tumours deep to fascia, measuring more than 5cm in any dimension. Both benign and malignant sarcomas were included. MR scans and histology were reviewed, separately and in random order by a single author. Histology was graded as benign, low or high grade (based on the American Joint Committee on Cancer grading system).

Peritumoral oedema was defined as the increased signal intensity, on T2 or STIR images, immediately surrounding a discrete lesion. It was measured on two or more planes with the largest value used in diagnostic calculations. Oedema greater than or equal to 20mm was defined as a positive test result. Twenty five random scans were double read to ensure inter-observer reliability

Data was obtained for 83 tumours, 36 benign and 47 malignant (34 high grade and 13 low grade). The tumours in all groups were matched for size. The mean peritumoral oedema was 10.5mm for benign tumours, 20.6mm for low grade sarcomas (p<0.1), 28.1mm for high grade tumours (p<0.01) and 26.1mm if all malignant tumours were included as a single group (p<0.01). Using peritumoral oedema as a diagnostic test for tumour grade resulted in a specificity of 72%. The highest diagnostic ability was found when comparing benign to high grade tumours which yielded sensitivity of 59% and a positive likelihood ratio of 2.1. This data suggests a high false negative rate and that the test adds little to the diagnostic process.

To our knowledge this is the first study which assesses the diagnostic accuracy of peritumoral oedema to predict the histological grade of soft tissue sarcomas. Our results show a statistically significant difference, in surrounding peritumoral oedema, exists when comparing benign to high grade sarcomas and to all malignant tumours. This relationship is not apparent for low grade tumours. As a diagnostic test, using only peritumoral oedema to predict histological grade is unreliable.

A new surgical hybrid technique involving the combination of autologous bone plug(s) and autologous chondrocyte implantation (AOsP-ACI) was used and evaluated as a treatment option in 15 patients for repair of large osteochondral defects in knee (N=12) and hip joints (N=3). Autologous Osplugs were used to contour the articular surface and the autologous chondrocytes were injected underneath a biological membrane covering the plug. The average size of the osteochondral defects treated was 4.5cm. 2. The average depth of the bone defect was 26mm. The patients had a significant improvement in their clinical symptoms at 12 months with significant increase in the Lysholm Score and Harris Hip Score (p = 0.031). The repaired tissue was evaluated using Magnetic Resonance Imaging, Computerised Tomography, arthroscopy, histology and immunohistochemistry (for expression of type I and II collagen). Magnetic Resonance Imaging, Computerised Tomography and histology at 12 months revealed that the bone plug became well integrated with the host bone and repair cartilage. Arthroscopic examination at 12 months revealed good lateral integration of the AOsP-ACI with the surrounding cartilage. Immunohistochemistry revealed mixed fibro-hyaline cartilage. We conclude that the hybrid AOsP-ACI technique provides a promising surgical approach for the treatment of patients with large osteochondral defects. This study highlights the use of this procedure in two different weightbearing joints and demonstrates good early results which are encouraging. The long term results need to be evaluated

Abstract. Introduction. A spotlight has been placed upon virtual assessment of patients during the coronavirus pandemic. This has been particularly prevalent in the assessment of acute knee injuries. In this study we aim to assess the accuracy of telephone triage, confirmed by Magnetic Resonance Imaging (MRI) in the diagnosis of acute knee injuries. Methods. Case records of patients triaged by telephone in the acute knee clinic at Leeds General Infirmary were analysed. Provisional diagnoses made following telephone triage were compared to radiological diagnoses made on subsequent MRI scans. Diagnostic accuracy was compared between those patients assessed virtually and those assessed in face-to-face clinics. Results. 1160 patients were referred to the acute knee injury clinic during the study period. 587 of these were triaged telephonically. MRI scans were requested for 107 (18%) virtually reviewed patients. Of these patients, 92 (79%) had an MRI scan requested after making a provisional diagnosis over the phone. Of the MRI requests made after virtual consultation, there was a 75% diagnostic accuracy of the pre-imaging diagnosis. Of the patients seen in face-to-face appointments, a diagnostic accuracy of 73% was observed. Conclusion. Virtual assessment can provide an efficient and cost-effective establishment of diagnosis of acute knee injuries whilst reducing hospital attendance. A combination of virtual and in-person clinics may allow quicker access to specialist opinion and therefore reduce patient waiting times

Introduction. Gram-negative prosthetic joint infections (GN-PJI) present unique challenges in management due to their distinct pathogenesis of biofilm formation on implant surfaces. The purpose of this study is to establish a clinically representative GN-PJI model that can reliably recapitulate biofilm formation on titanium implant surface in vivo. We hypothesized that biofilm formation on an implant surface will affect its ability to osseointegrate. Methods. The model was developed using 3D-printed titanium hip implants, to replace the femoral head of male Sprague-Dawley rats. GN-PJI was induced using two bioluminescent Pseudomonas aeruginosa strains: a reference strain (PA14-lux) and a mutant biofilm-defective strain (ΔflgK-lux). Infection was monitored in real-time using the in vivo imaging system (IVIS) and Magnetic Resonance Imaging (MRI). Bacterial loads on implant surface and in periprosthetic tissues were quantified utilizing viable-colony-count. Field-emission scanning-electron-microscopy of the explanted implants was used to visualize the biofilm formation at the bone-implant-interface. The implant stability, as an outcome, was directly assessed by quantifying the osseointegration in vitro using microCT scan, and indirectly assessed by identifying the gait pattern changes using DigiGait. TM. system in vivo. Results. Localized infection was established within the hip joint and was followed by IVIS in real-time. There was a quantitative and qualitative difference in the bacterial load and biofilm formation between PA14-lux and ΔflgK-lux. This difference in the ability to persist in the model between the two strains was reflected in the gait pattern and implant osseointegration. Conclusions. We developed a novel uncemented hip hemiarthroplasty, GN-PJI rat model. To date, the proposed in vivo biofilm-based model is the most clinically representative for GN-PJI since animals can bear weight on the implant and poor osseointegration correlates with biofilm formation. In addition, localized PJI was detected by various modalities. Clinical Relevance. The proposed in vivo GN-PJI model will allow for more reliable testing of novel biofilm-targeting therapeutics

Gram-negative prosthetic joint infections (GN-PJI) present unique challenges in management due to their distinct pathogenesis of biofilm formation on implant surfaces. To date, there are no animal models that can fully recapitulate how a biofilm is challenged in vivo in the setting of GN-PJI. The purpose of this study is to establish a clinically representative GN-PJI in vivo model that can reliably depict biofilm formation on titanium implant surface. We hypothesized that the biofilm formation on the implant surface would affect the ability of the implant to be osseointegrated. The model was developed using a 3D-printed, medical-grade titanium (Ti-6Al-4V), monoblock, cementless hemiarthroplasty hip implant. This implant was used to replace the femoral head of a Sprague-Dawley rat using a posterior surgical approach. To induce PJI, two bioluminescent Pseudomonas aeruginosa (PA) strains were utilized: a reference strain (PA14-lux) and a mutant strain that is defective in biofilm formation (DflgK-lux). PJI development and biofilm formation was quantitatively assessed in vivo using the in vivo imaging system (IVIS), and in vitro using the viable colony count of the bacterial load on implant surface. Magnetic Resonance Imaging (MRI) was acquired to assess the involvement of periprosthetic tissue in vivo, and the field emission scanning electron microscopy (FE-SEM) of the explanted implants was used to visualize the biofilm formation at the bone-implant interface. The implant stability, as an outcome, was directly assessed by quantifying the osseointegration using microCT scans of the extracted femurs with retained implants in vitro, and indirectly assessed by identifying the gait pattern changes using DigiGaitTM system in vivo. A localized prosthetic infection was reliably established within the hip joint and was followed by IVIS in real-time. There was a quantitative and qualitative difference in the bacterial load and biofilm formation between PA14 and DflgK. This difference in the ability to persist in the model between the two strains was reflected on the gait pattern and implant osseointegration. We developed a novel uncemented hip hemiarthroplasty GN-PJI rat model. This model is clinically representative since animals can bear weight on the implant. PJI was detected by various modalities. In addition, biofilm formation correlated with implant function and stability. In conclusion, the proposed in vivo GN-PJI model will allow for more reliable testing of novel biofilm-targeting therapetics

Worldwide, most spine imaging is either “inappropriate” or “probably inappropriate”. The Choosing Wisely recommendation is “Do not perform imaging for lower back pain unless red flags are present.” There is currently no detailed breakdown of lower back pain diagnostic imaging performed in New Brunswick (NB) to inform future directions. A registry of spine imaging performed in NB from 2011-2019 inclusive (n=410,000) was transferred to the secure platform of the NB Institute for Data, Training and Research (NB-IRDT). The pseudonymized data included linkable institute identifiers derived from an obfuscated Medicare number, as well as information on type of imaging, location of imaging, and date of imaging. The transferred data did not include the radiology report or the test requisition. We included all lumbar, thoracic, and complete spine images. We excluded imaging related to the cervical spine, surgical or other procedures, out-of-province patients and imaging of patients under 19 years. We verified categories of X-ray, Computed Tomography (CT), and Magnetic Resonance Imaging (MRI). Red flags were identified by ICD-10 code-related criteria set out by the Canadian Institute for Health Information. We derived annual age- and sex-standardized rates of spine imaging per 100,000 population and examined regional variations in these rates in NB's two Regional Health Authorities (RHA-A and RHA-B). Age- and sex-standardized rates were derived for individuals with/without red flag conditions and by type of imaging. Healthcare utilization trends were reflected in hospital admissions and physician visits 2 years pre- and post-imaging. Rurality and socioeconomic status were derived using patients’ residences and income quintiles, respectively. Overall spine imaging rates in NB decreased between 2012 and 2019 by about 20% to 7,885 images per 100,000 people per year. This value may be higher than the Canadian average. Females had 23% higher average imaging rate than males. RHA-A had a 45% higher imaging rate than RHA-B. Imaging for red flag conditions accounted for about 20% of all imaging. X-rays imaging accounted for 67% and 75% of all imaging for RHA-A and RHA-B respectively. The proportions were 20% and 8% for CT and 13% and 17% for MRI. Two-year hospitalization rates and rates of physician visits were higher post-imaging. Females had higher age-standardized hospitalization and physician-visit rates, but the magnitude of increase was higher for males. Individuals with red flag conditions were associated with increased physician visits, regardless of the actual reason for the visit. Imaging rates were higher for rural than urban patients by about 26%. Individuals in the lowest income quintiles had higher imaging rates than those in the highest income quintiles. Physicians in RHA-A consistently ordered more images than their counterparts at RHA-B. We linked spine imaging data with population demographic data to look for variations in lumbar spine imaging patterns. In NB, as in other jurisdictions, imaging tests of the spine are occurring in large numbers. We determined that patterns of imaging far exceed the numbers expected for ‘red flag’ situations. Our findings will inform a focused approach in groups of interest. Implementing high value care recommendations pre-imaging ought to replace low-value routine imaging

Spinal stenosis is a condition resulting in the compression of the neural elements due to narrowing of the spinal canal. Anatomical factors including enlargement of the facet joints, thickening of the ligaments, and bulging or collapse of the intervertebral discs contribute to the compression. Decompression surgery alleviates spinal stenosis through a laminectomy involving the resection of bone and ligament. Spinal decompression surgery requires appropriate planning and variable strategies depending on the specific situation. Given the potential for neural complications, there exist significant barriers to residents and fellows obtaining adequate experience performing spinal decompression in the operating room. Virtual teaching tools exist for learning instrumentation which can enhance the quality of orthopaedic training, building competency and procedural understanding. However, virtual simulation tools are lacking for decompression surgery. The aim of this work was to develop an open-source 3D virtual simulator as a teaching tool to improve orthopaedic training in spinal decompression. A custom step-wise spinal decompression simulator workflow was built using 3D Slicer, an open-source software development platform for medical image visualization and processing. The procedural steps include multimodal patient-specific loading and fusion of Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) data, bone threshold-based segmentation, soft tissue segmentation, surgical planning, and a laminectomy and spinal decompression simulation. Fusion of CT and MRI elements was achieved using Fiducial-Based Registration which aligned the scans based on manually placed points allowing for the identification of the relative position of soft and hard tissues. Soft tissue segmentation of the spinal cord, the cerebrospinal fluid, the cauda equina, and the ligamentum flavum was performed using Simple Region Growing Segmentation (with manual adjustment allowed) involving the selection of structures on T1 and/or T2-weighted scans. A high-fidelity 3D model of the bony and soft tissue anatomy was generated with the resulting surgical exposure defined by labeled vertebrae simulating the central surgical incision. Bone and soft tissue resecting tools were developed by customizing manual 3D segmentation tools. Simulating a laminectomy was enabled through bone and ligamentum flavum resection at the site of compression. Elimination of the stenosis enabled decompression of the neural elements simulated by interpolation of the undeformed anatomy above and below the site of compression using Fill Between Slices to reestablish pre-compression neural tissue anatomy. The completed workflow allows patient specific simulation of decompression procedures by staff surgeons, fellows and residents. Qualitatively, good visualization was achieved of merged soft tissue and bony anatomy. Procedural accuracy, the design of resecting tools, and modeling of the impact of bone and ligament removal was found to adequately encompass important challenges in decompression surgery. This software development project has resulted in a well-characterized freely accessible tool for simulating spinal decompression surgery. Future work will integrate and evaluate the simulator within existing orthopaedic resident competency-based curriculum and fellowship training instruction. Best practices for effectively teaching decompression in tight areas of spinal stenosis using virtual simulation will also be investigated in future work

Knee dislocation is a rare injury in high energy trauma, but it is even rarer in low energy injuries. We present, to our knowledge, the only case in the world literature of knee dislocation following a cricketing injury. The patient was a 46 year old recreational fast bowler who, whilst bowling, slipped on the pitch on the follow through. He sustained an anteromedial knee dislocation which was reduced under intravenous sedation. He also sustained a neuropraxia of the common peroneal nerve with grade 2 weakness of ankle and toe dorsiflexion. Magnetic Resonance Imaging (MRI) confirmed a complete rupture of anterior cruciate ligament (ACL), lateral collateral ligament (LCL) and postero-lateral corner (PLC). Patient underwent surgical reconstruction and repair of his PLC along with repair of LCL with combination of anchor sutures and metal staple within 72 hours of the injury. He was treated in a cast brace. The ACL insufficiency was treated conservatively. Patient made an uneventful recovery and follow up at 3 months revealed a full range of knee movements with asymptomatic ACL laxity

Studies have shown that the trees minor plays an important role after total (TSA) and reverse (RSA) shoulder arthroplasty, as well as in maintenance of function in the setting of infraspinatus wasting. In this regard, teres minor hypertrophy has been described as a compensatory change in response to this infraspinatus wasting, and has been suggested that this compensatory hypertrophy may mitigate the loss of infraspinatus function in the patient with a large rotator cuff tear. The purpose of this study was to determine the prevalence of teres minor hypertrophy in a cohort of patients undergoing rotator cuff repair, and to determine its prognostic effect, if any, on outcomes after surgical repair. Over a 3 year period, all rotator cuff repairs performed in a single practice by 3 ASES member surgeons were collected. Inclusion criteria included both preoperative and postoperative validated outcomes measures (minimum 2 year), and preoperative Magnetic Resonance Imaging (MRI) scanning. 144 patients met all criteria. MRIs were evaluated for rotator cuff tear tendon involvement, tear size, and Goutallier changes of each muscle. In addition, occupational ratios were determined for the supraspinatus, infraspinatus, and teres minor muscles. Patients were divided into 2 groups, based upon whether they had teres minor hypertrophy or not, based on a previously established definition. A 2 way ANOVA was used to determine the effect of teres minor hypertrophy(tear size by hypertrophy) and Goutallier. Teres minor hypertrophy was a relatively common finding in this cohort of rotator cuff patients, with 51% of all shoulders demonstrating hypertrophy. Interestingly, in patients without an infraspinatus tear, teres minor hypertrophy was still present in 19/40 (48%) of patients. Teres minor hypertrophy had a significant, negative effect ASES scores after rotator cuff repair in patients with and without infraspinatus tearing, infraspinatus atrophy, and fatty infiltrative changes (P<0.05). In general, the presence of teres minor hypertrophy showed 10–15% less improvement (Figure 1) than when no hypertrophy was present, and this was consistent across all tear sizes, independent of Goutallier changes. Teres minor hypertrophy is a common finding in the setting of rotator cuff tearing, including in the absence of infraspinatus tearing. Contrary to previous publications, the presence of teres minor hypertrophy in patients with rotator cuff repair does not appear to be protective as a compensatory mechanism. While further study is necessary to determine the mechanism or implication of teres minor hypertrophy in setting of rotator cuff repair, our results show it is not a positive of outcomes following rotator cuff repair