Abstract
Healthcare providers and physical therapist involved in the management of patients with musculoskeletal disorders, the inclusion of an imaging modality would enhance and improve medical diagnosis of such conditions. Based on current evidence, the implementation of physical therapy is highly recommend before the inclusion of an imaging modality. In such cases, physical therapist would require a robust, comprehensive, and feasible diagnostic imaging modality. In the US, there is an increase in demand for physical therapist which enables them to practice in over 45 states. The privilege of imaging referral or inclusion of imaging modalities as an adjunct to screening would improve healthcare delivery and also provide efficient and effective interventions associated with the diagnosis. This paper focus on the various diagnostic modalities available for hip osteoarthritis. Based on current evidence, radiographs, computed tomography, magnetic resonance imaging, and ultrasound have been found to be feasible, effective, and efficient imaging diagnostic modalities among healthcare providers. However, the use of these modalities among physical therapist is unclear. This paper provides an insight on the various imaging diagnostic technique of hip OA in association with physical therapist.
Introduction
Osteoarthritis (OA) is a common and prevailing health disorder among the aging population which is associated with many economic challenges in most industrialized nations. OA is considered as a chronic health condition which worsen overs time. The morbidity of hip OA has increased significantly owing to obesity and sedentary lifestyle. Based on current evidence, many surgical interventions and symptom-related strategies have been implemented for patients with hip OA. The most conventional modality is hip replacement for this heterogeneous and complex disease. Most researchers and healthcare providers consider OA as a multi-factorial conditions which is associated with the breakdown of hyaline cartilage. The most conventional imaging diagnostic approaches for hip OA include radiograph or MRI. The imaging modalities reveal the hyaline cartilage breakdown over articulating joints. Based on current evidence, imaging of the hip for osteoarthritis is easy and advantageous. Some of the key factors include near distance to the ilium, sacrum, lumbar spine, soft tissues, and assorted muscles. Most healthcare professionals and researchers recommend the use of multiple images to assess for proper diagnosis. The first approach for proper assessment and diagnosis should include the capture of a wide view of the entire ilium, sacrum, and hip. The second approach would include imaging of specific suspected regions based on initial diagnosis followed by the inspection of the suspected region that is dysfunctional (Blum, Raymond, & Teixeira. 2015).
Conventional Radiographs
Radiographs are considered as one of the most conventional and common imaging modalities for hip OA due to high degree of accuracy, low cost, fast results, and ease of operation. On the contrary, researchers support and recommend magnetic resonance imaging (MRI) over radiographs since it provides a high resolution of neighbouring tissues along with the details of the articular cartilage (Kim, et al. 2015). The diagnosis of hip OA is also based on multiple criteria based on guideline recommendations which may include internal rotation of the hip, multiple clinical prediction rules, hip pain in specific areas, stiffness in morning for over 60 minutes, and pain in hip after specific activities (Pereira, et al. 2016). Researchers still prefer imaging techniques for the diagnosis of hip OA due to its high sensitivity and accuracy. However, imaging techniques may not have high specificity (Abu-Rajab, et al. 2015).
Computed tomography (CT)
CT is considered as a valuable tool in the assessment, diagnosis, and characterization of OA, especially in specific cases wherein the image of the osseous changes are required. CT is also useful in the assessment of detailed pre-surgical requirement. Based on current evidence and improvised imaging techniques, Helical multidetector (MD) CT systems are known to produce high quality images particularly of the isotropic voxels and multiplanar reconstructions in specified planes (Miller, et al. 2016). CT is known to produce better images with respect to cortical bone and soft tissue calcifications in comparison to MRI. CT has played a key role in the assessment of OA of the spine including joints and tissues. CT is also known to have a few disadvantages including high dose radiation and low soft-tissue contrast. Hip joints and visualizations of intrinsic joint structures including cartilage is possible with the help of CT arthrography which is an alternate and feasible imaging modality (Llopis, Fernandez, & Cerezal. 2012). The concept of CT arthrography is beneficial and acceptable in specific cases wherein MRI is contraindicated or MRI facilities are unavailable (Llopis, Fernandez, & Cerezal. 2012). Researchers also state that CT arthrography helps in providing excellent images of the articular surface of the hip for easy assessment of hip OA. Based on current evidence, the use of CT arthrography is related to the penetration of contrast medium into the cartilage surface to provide contrast and high spatial resolution images to differentiate between the contrast medium, cartilage, and joint morphology. However, CR is associated with a few limitations such as insensitivity to changes within the layers of the cartilage, surface alterations, and the invasive nature of the technique (Llopis, Fernandez, & Cerezal. 2012).
Magnetic resonance imaging
Ultrasound
Ultrasound is the most recognized and conventional imaging modality for hip OA. It is associated with low cost, real time and multiplanar images with no radiation exposure. Unlike, CT, there is no need of contrast administration but it still provides soft tissue images. It can also be used to detect synovial pathology (Rutjes, Nüesch, Sterchi, Jüni. 2010). The most common disadvantage of ultrasound is its operator-dependent use in association with the physical properties that limit its applications in providing images of articular structures and the subchondral bone. In a recent study, ultrasound has been associated with the detection of synovial hypertrophy and joint effusion and production of grey-scale synovitis (Sudula. 2016).
Diagnostic modalities for Leg length discrepancy: Leg length discrepancy (LLD) can be diagnosed by various modalities but there are 3 distinct and conventional radiographic modalities that are most preferred by healthcare providers which include orthoroentogenogram, scanogram, and teleoroentgenogram. All 3 methods have been validated and recommended in most clinical trials, guidelines, and consensus statements. The techniques are known to be efficient and feasible to assess and diagnose patients with LLD (Sabharwal & Kumar. 2008). An orthoroentgenogram comprises of a technique that uses 3 radiographic images of the hip, knee, and ankle joints to prevent magnification error. The process includes placing a large cassette under the patient with the placement based in between the 3 exposures for accurate and clear images (Sabharwal & Kumar. 2008). In a similar pattern, the scanogram is also associated with 3 radiographic exposures which are centered over the ankle joint, knee, and hip. In this case, a calibrated ruler is used wherein the patient remains still and straight which is not observed in the orthoroentgenogram. Similar to the orthoroentgenogram, the conventional length cassette was placed for all 3 exposures (Sabharwal & Kumar. 2008). The teleoroentgenogram is unique and different compared to the previous two modalities. It comprises of a full-length standing AP radiograph which is primarily for the low extremities. The x-ray beam is centred at the knee with a single cassette exposed to both lower limbs. The x-ray beam is placed at 6 feet and directed anteriorly towards the patient (Sabharwal & Kumar. 2008). Other diagnostic modalities that are commonly used to assess LLD include MRI, CT, and Ultrasound which follow the same principles of diagnosis as in hip OA. Based on current evidence, conventional radiographs are the most trusted, recommended, and widely studied imaging modality for the assessment and diagnosis of leg length discrepancy.
Diagnostic Imaging of the Hip OA and Physical Therapy: Physical therapy plays a key role in the management of pain and function in patients with hip OA, Based on current evidence, physical therapy is known to lower pain scores, improve quality of life, improve mobility/function, and physical performance. Physical therapy is also known to improve the psychological status of the patient (Bennell, et al. 2014). However, owing to recent guidelines on the prevention and diagnosis of hip OA, many researchers prefer the use of an imaging diagnostic modality in line with a physical therapy for patients (Boyles, Gorman, Pinto, & Ross. 2011).Diagnostic imaging would not only confirm the presence of a health condition but would also be associated with better health outcomes, increased quality of life, increased patient satisfaction, and better healthcare delivery (Boyles, Gorman, Pinto, & Ross. 2011). Physical therapist play a key role in the management of hip OA and thus the diagnostic imaging of OA would help them in the following: (I) Reading Radiograph for Hip OA: Assess subchondral sclerosi, joint narrowing, and osteophyte formation (II) Reading MRI for Hip OA: Assess osteophyte formation, increased oedema, joint narrowing, and decreased signal frequency of hyaline cartilage (Boyles, Gorman, Pinto, & Ross. 2011). Thus, clinical diagnostic imaging of hip OA and leg length discrepancy is closely related to physical therapy. It should be added as an adjunct to screening, assessment, and management of such conditions.
Conclusion
Based on current evidence, conventional radiography can be considered as the first choice of diagnostic modality by researchers and healthcare professionals for patients suspected with hip OA or leg length discrepancy. It is the only imaging technique that is approved and recommended by the EMA and FDA for assessing patients in clinical trials. However, due to the limitations of radiography, a few researchers prefer MRI-related imaging modalities for OA as well as leg length discrepancy. MRI is highly recommend since it involves the assessment of the knee as a whole organ along with 3-dimensinal images of internal structures. On the other hand, contrast MRI and ultrasound are important imaging techniques which are preferred for the assessment of post-treatment of OA. Thus, imaging modalities as an adjunct in physical therapy would play a critical part in the treatment and management of OA.
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