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Dive into the research topics where Otto Chan is active.

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Featured researches published by Otto Chan.


Radiographics | 2008

Accessory muscles: Anatomy, symptoms, and radiologic evaluation

Paul A. Sookur; Ali Naraghi; Robert Bleakney; Rosy Jalan; Otto Chan; Lawrence M. White

A wide array of supernumerary and accessory musculature has been described in the anatomic, surgical, and radiology literature. In the vast majority of cases, accessory muscles are asymptomatic and represent incidental findings at surgery or imaging. In some cases, however, accessory muscles may produce clinical symptoms. These symptoms may be related to a palpable swelling or may be the result of mass effect on neurovascular structures, typically in fibro-osseous tunnels. In cases in which an obvious cause for such symptoms is not evident, recognition and careful evaluation of accessory muscles may aid in diagnosis and treatment.


Disability and Rehabilitation | 2008

High volume image guided injections in chronic Achilles tendinopathy.

Otto Chan; Dominic O'Dowd; Nat Padhiar; Dylan Morrissey; John B. King; Rosy Jalan; Nicola Maffulli; Tom Crisp

Purpose. To determine the effectiveness of high volume image guided injections (HVIGI) for chronic Achilles tendinopathy. Methods. We included in the study 30 consecutive patients (mean age 37.2 years, range 24 – 58 years) with Achilles tendinopathy for a mean of 35.8 months (range 2 – 276 months) who had failed to improve after a three-month programme of eccentric loading of the gastro-soleus complex. Patients were injected with 10 ml of 0.5% Bupivacaine Hydrochloride, 25 mg Hydrocortisone acetate, and up to 40 ml of injectable normal saline. A study-specific questionnaire and the Victorian Institute of Sport Assessment – Achilles tendon (VISA-A) were retrospectively administered to assess short- and long-term pain and functional improvement. Results. Some 21 patients (70%) responded. Patients reported significant short-term improvement at 4 weeks of both pain (mean change 50 mm, [SD 28, p < 0.0001], from a mean of 76 mm [SD 18.2], to a mean of 25 mm [SD 23.3]), and function scores (mean change 51 mm, [SD 31.2, p < 0.0001], from a mean of 78 mm [SD 20.8], to a mean of 27 mm [SD 28.4]). Patients also reported significant long-term improvement in symptoms using the VISA-A questionnaire (mean change 31.2 points, [SD = 28, p < 0.0001], from a mean of 44.8 points [SD 17.7], to a mean of 76.2 points [SD 24.6]) at a mean of 30.3 weeks from the injection. Conclusions. HVIGI significantly reduces pain and improves function in patients with resistant Achilles tendinopathy in the short- and long-term.


Knee Surgery, Sports Traumatology, Arthroscopy | 2012

Acute muscle strain injuries: a proposed new classification system

Otto Chan; Angelo Del Buono; Thomas M. Best; Nicola Maffulli

PurposeTo better define and classify acute muscle strain injuries.MethodsHistorically, acute muscle strains have been classified as grade I, II and III. This system does not accurately reflect the anatomy of the injury and has not been shown to reliably predict prognosis and time for return to sport.ResultsWe describe an imaging (magnetic resonance or ultrasound) nomenclature, which considers the anatomical site, pattern and severity of the lesion in the acute stage. By site of injury, we define muscular injuries as proximal, middle and distal. Anatomically, based on the various muscular structures involved, we distinguish intramuscular, myofascial, myofascial/perifascial and musculotendinous injuries.ConclusionsThis classification system must be applied to a variety of muscle architectures and locations to determine its utility; additional studies are therefore needed prior to its general acceptance.Level of evidenceV.


Disability and Rehabilitation | 2008

Achilles and patellar tendinopathy: Current understanding of pathophysiology and management

Suan Cheng Tan; Otto Chan

Purpose. Achilles and patellar tendinopathy cause significant morbidity in professional and recreational athletes. Both the Achilles and patellar tendons are weight-bearing tendons that lack a true tendon sheath but are surrounded by paratenon. Method. A review of the literature to outline the characteristics of tendinopathy in these two tendons, and to discuss current concepts of pathophysiology, use of imaging in the diagnosis and aid to clinical management strategies in tendinopathy. Results. Achilles and patellar tendinopathy share common histopathology such as intratendinous failed healing response and neoangiogenesis. Conclusion. Achilles and patellar tendinopathy cause much morbidity in the athletic and non athletic population attending sports medicine and rheumatology clinics. Tendinopathy is essentially an ‘overuse’, degenerative condition. Neovascularisation evident on Doppler ultrasound correlates well with pain and poor function. Peritendinous injections and eccentric training decrease neovascularity, relieve pain and improve outcome. Although surgery is the last resort in those patients failing conservative management, it is still unclear how the removal of adhesions and excision of affected tendinopathic areas affects healing and vascularity, or resolves pain.


Journal of Science and Medicine in Sport | 2010

The short-term effects of high volume image guided injections in resistant non-insertional Achilles tendinopathy

Joel Humphrey; Otto Chan; Tom Crisp; Nat Padhiar; Dylan Morrissey; Richard Twycross-Lewis; John B. King; Nicola Maffulli

We investigated neovascularisation, tendon thickness and clinical function in chronic resistant Achilles tendinopathy following high volume image guided injections (HVIGI). The subjects involved 11 athletes (mean age 43.5 years+/-11.6, range 22-59) with resistant tendinopathy of the main body of the Achilles tendon for a mean of 51.4 months (+/-55.56, range 4-144) who failed to improve with an eccentric loading program (mean 11.8 months+/-2.6, range 8-16). The morphological features, neovascularisation and maximal tendon thickness were assessed with power Doppler ultrasound. Clinical function was measured with the Victorian Institute of Sports Assessment-Achilles tendon (VISA-A) questionnaire. All the tendinopathic Achilles tendons were injected with 10 mL of 0.5% bupivacaine hydrochloride, 25 mg of hydrocortisone acetate, and 40 mL of 0.9% NaCl saline solution under real time ultrasound guidance. All outcome measures were recorded at baseline and after a short-term follow-up (mean 2.9 weeks, range 2-4). The results showed a statistically significant difference between baseline and 3-week follow-up in all the outcome measures after HVIGI. The grade of neovascularisation reduced (3-1.1, p=0.003), the maximal tendon diameter decreased (8.7-7.6 mm, p<0.001), and the VISA-A scores improved (46.3-84.1, p<0.001). In conclusion, HVIGI for resistant tendinopathy of the main body of the Achilles tendon is effective to improve symptoms, reduce neovascularisation, and decrease maximal tendon thickness at short-term follow-up.


Manual Therapy | 2010

Site of maximum neovascularisation correlates with the site of pain in recalcitrant mid-tendon Achilles tendinopathy

Kiran Divani; Otto Chan; Nat Padhiar; Richard Twycross-Lewis; Nicola Maffulli; Tom Crisp; Dylan Morrissey

BACKGROUND Neovascularisation is associated with pain in Achilles tendinopathy (AT). The anatomical relationship between ultrasound (US)-defined indicators of tendinopathy and clinically determined pain sites has not been investigated. PURPOSE To measure the spatial correlation between the sites of maximum palpated tenderness, site of patient-indicated pain, maximum US-determined neovascularisation and maximum antero-posterior tendon thickness in patients with chronic recalcitrant AT (CRAT). METHODS A custom-designed measuring apparatus and clinical examination were used to measure the sites of maximum tenderness and subjectively defined pain on 29 tendons from patients diagnosed with mid-tendon CRAT. All tendons had been previously non-responsive to eccentric loading. Maximal neovascularisation and tendon thickness were measured by US scanning in conjunction with the measuring device. RESULTS A significant association exists between clinically determined pain and neovascularisation (r = 0.85, p < 0.001), patient reported pain (r = 0.91, p < 0.001), maximal tendon thickness (r = 0.91, p < 0.001), maximal thickness and maximal neovascularisation (r = 0.86, p < 0.001). CONCLUSION Sites of subjectively defined pain, clinically palpated tenderness, tendon thickness and neovascularisation are anatomically associated. Palpation can be reliably used as a clinical guide when planning interventions in patients with CRAT.


International Journal of Sports Medicine | 2012

Doppler Ultrasound Signal in Achilles Tendinopathy Reduces Immediately After Activity

Peter Malliaras; Otto Chan; G Simran; P Martinez de Albornoz; Dylan Morrissey; Nicola Maffulli

BACKGROUND A relationship has been identified between vascularization on Doppler ultrasound (Doppler signal) and Achilles tendon pain. Doppler signal may increase minutes after prolonged activity, but the immediate effect is unknown. The aim of the study was to investigate the immediate effect of short term activity on Achilles tendon Doppler signal. Achilles tendinopathy patients (7 patients, 10 tendons) and asymptomatic controls (6 controls, 12 tendons) performed 2 activity tasks; a 2 minute continuous step task and one minute continuous calf raise task. Doppler signal was measured at rest and within a minute after each activity. The presence of Doppler signal was quantified using both semi quantitative (modified Ohberg scale; 0=no signal, 5 = > 90% of pathological area contains Doppler signal) and quantitative methods (pixel number). Doppler signal was present in 90% of symptomatic individuals and in none of the asymptomatic controls. The modified Ohberg scale and pixel number reduced significantly after both activity tasks and heart rate increased significantly (p < 0.05). Doppler signal in Achilles tendinopathy may decrease immediately after activities that load the calf muscle and increase heart rate, suggesting that this activity should be avoided prior to imaging to avoid false negative results.


Disability and Rehabilitation | 2008

Pennation angle of the soleus in patients with unilateral Achilles tendinopathy.

Nat Padhiar; Hisham Al-Sayeagh; Otto Chan; John B. King; Nicola Maffulli

We measured the ultrasound scans of 23 (21 males, two females) physically active subjects (mean age: 40 years; range: 20 – 58) with unilateral Achilles tendinopathy to determine the pennation angle in the soleus muscles of the affected and non-affected limb. All scans were performed by one radiologist. The pennation angle was lower on the affected side in 15 patients, and higher on the non-affected side in eight patients. There was a significant difference in the angle of pennation of the soleus muscle on the affected side (15.9°) compared with that on the non-affected one (17.3°; p = 0.01). Patients with symptomatic Achilles tendinopathy are more likely to have decreased pennation angle of the soleus muscle on the affected side. This may have implications for appropriate management of Achilles tendinopathy.


Clinical Journal of Sport Medicine | 2014

Early signs of osteoarthritis in professional ballet dancers: a preliminary study.

Manuela Angioi; Gayle D. Maffulli; Moira McCormack; Dylan Morrissey; Otto Chan; Nicola Maffulli

Objective:To investigate a cohort of professional ballet dancers for evidence of early signs of osteoarthritis (OA). Design:One radiologist and 1 orthopedic surgeon specialized in musculoskeletal disorders analyzed magnetic resonance imaging scans independently. Setting:University Teaching Hospital. Participants:Fifteen professional ballet dancers (4 males and 11 females; age range, 19-36 years) experiencing chronic pain in the hip, knee, spine, ankle, or foot joints. Main Outcome Measures:Presence of osteophytes, subchondral sclerosis, joint space narrowing, cysts, and bone marrow changes; the Kellgren and Lawrence scale was used to quantify the knee OA. Results:In the knee, there was thinning and irregularity of the articular cartilage over the medial femoral condyle and bone marrow changes within the lateral femoral condyle. In the hip, there was a loss of joint space and a frayed labrum with deep recess. The first metatarsophalangeal joint showed evidence of osteophytic development. Conclusions:Early signs of OA, in different joints, were present in a small but highly selected cohort of professional ballet dancers. In future, prospective studies among a number of ballet companies should control for medical and natural history alongside the visual analysis of images and plain radiographs to confirm these preliminary results.


British Journal of Sports Medicine | 2015

Acute tear of the fascia cruris at the attachment to the Achilles tendon: a new diagnosis

Nick Webborn; Dylan Morrissey; Kasthuri Sarvananthan; Otto Chan

Background The fascia cruris encloses the posterior structures of the calf and connects to the paratenon and the Achilles tendon. We describe the clinical presentation, ultrasound imaging characteristics and the time to the recovery of tears of the fascia cruris at the attachment to the Achilles tendon. Methods Retrospective review of 11 tears of the fascia cruris in the different legs as separate events in 9 patients (6 male and 3 female, mean age 35.52 years, range 11–48) identified using diagnostic ultrasound, after presenting with Achillodynia. Results 11 participants presented at a mean of 4.5 weeks (range 0.5–12) after onset of symptoms. The left Achilles was more commonly injured than the right (7 : 4) and the lateral side more than the medial (6 : 4) with one case with medial and lateral presentation. Clinically, there was swelling and tenderness over the medial or lateral border in the mid to upper portion of the Achilles. 7 of the 11 (63.6%) had functional overpronation. Ultrasound appearances of a tear were identified as hypoechoic area extending from the medial or lateral border of the Achilles extending along the anatomical plane of the fascia cruris. Average return to activity was 5.2 weeks (range 1–22). Participants presenting later had longer recovery but all participants returned to full activity (r=0.4). Conclusions This is the first description of the clinical details and sonographic findings of a tear to the fascia cruris at its attachment to the Achilles tendon. This needs to be considered as a cause of Achillodynia in athletes as recognition will affect the management.

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Dylan Morrissey

Queen Mary University of London

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Nat Padhiar

Queen Mary University of London

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Sarah Morton

Queen Mary University of London

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John B. King

Queen Mary University of London

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Nicola Maffulli

Queen Mary University of London

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Tina Parkes

Queen Mary University of London

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Xavier Valle

University of Barcelona

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