Introduction to Medicine for Engineers

Chapter 8: Process of medicine in arthritis

By Jason Guss

Rheumatologists are presented with a wide variety of patients complaining of pain, inflammation, and other widespread systemic effects. Arthritis is one of the primary diagnoses made by rheumatologists. There are several different types of arthritis, including osteoarthritis (mechanical), rheumatoid, psoriatic, and reactive. These different types of arthritis all have overlapping symptomology that can be misleading to the physician and can make correct diagnosis difficult. This chapter focuses on the process of medicine in arthritis and the correct diagnosis and treatment of mechanical and inflammatory arthritis types.

8.1 Patient history

The process of medicine begins with a detailed medical history of the patient. In musculoskeletal disorders, 80% of the diagnoses come from the patients' history [1]. The initial goal of the history and the physical exam is to identify if the arthritis is mechanical (osteoarthritis) or inflammatory. The history aims to evaluate several aspects of the medical problem. Initially, details of the chief complaint, such as location, duration, onset, pattern of joint involvement, and pain type, will be identified. Identification of joint involvement is important in diagnosis, as symmetry of location is indicative of rheumatoid arthritis (RA), whereas osteoarthritis typically begins on one side of the body. The onset and duration of the injury allows the physician to determine if the problem is a chronic issue or is the result of a single mechanical load. Osteoarthritis presents with more pain following activity and the primary complaint is typically pain. Inflammatory arthritis symptoms, on the other hand, frequently improve with physical activity and are commonly accompanied by morning stiffness and fatigue. The severity of the injury can be partially assessed by quantifying subsequent alterations in lifestyle. There are several health assessment questionnaires (HAQ) that are utilized to quantify the degree of one's symptoms and to measure the treatment outcome.

Next, one needs to learn of the patient's social, familial, and medical history. The social history may detail work and environmental factors that have influenced symptoms, as well as show how the patient's social interactions have been affected by the injury. The family history is another key component in the evaluation of arthritis, as it can show if there is a genetic predisposition to musculoskeletal system injury. Past medical history details previous medical treatment and medical ailments of the patient. It is important for the physician to examine the medical history in detail, as a patient may not disclose a past symptom due to disbelief that it is related to the current ailment.

The last primary component of the history is a review of all the major body systems (circulatory, respiratory, nervous, digestive, etc.). It is important to consider possible systemic disorders that could be related to the patient's complaints.

Fig.8.1. Normal joint, inflammatory arthritis, osteoarthritis

7.2 Diagnosis of a thyroid nodule

The physical examination process helps the physician further evaluate the symptoms. If inflammatory arthritis is suspected based on the history, a more thorough examination of all joints should be conducted. However, if it appears that symptoms are acute and localized only to one primary location, a less comprehensive examination can be conducted, as mechanical arthritis is less systemic. During the physical exam, the physician will have the patient walk across the room so that a description of the gait can be recorded. Viewing the patient in a standing position allows the physician to identify possible abnormalities in the patient's posture, misalignment of the lower extremities, and disposition of the ankles or feet [1]. The physician examines the upper extremities to assess any abnormal contours, joint function, and identify other irregular findings. Joint function is determined by evaluating the range of limb motion, rotation of joints in all directions, and strength. Irregular findings are examined by inspection and palpation to identify any soft-tissue swelling, bursitis, nodules, or other disease manifestations [1]. Swelling can be assessed by holding one set of fingers stationary on a joint while simultaneously squeezing the joint with the other hand in order to detect potential fluid flow in an uncommon area. The lower extremities are assessed in a similar manner in order to evaluate for alignment issues, joint function, and other disease manifestations. During the physical examination, the physician typically assesses extra-articular features as well, as symptoms may present as rheumatoid nodules, nail changes, rashes, ulcers, and neurological abnormalities [1]. The patient's reflexes are also checked in order to assess any adverse neurological involvement related to the disease. Oftentimes, pain presenting in the lower extremities is the result of sciatica (pain related to the agitation of a sciatic nerve) and it is important to separate these symptoms from those caused by arthritis or other related injury. After taking a comprehensive history and physical examination, a physician should have a good indication of the cause of the patient's symptoms.

8.3 Diagnostic procedures

Following the history and medical exam, physicians have a variety of imaging tools and laboratory tests at their disposal to further evaluate the patient. X-ray imaging, which provides a clear picture of bone anatomy, calcification of soft tissues, and joint spacing, is typically the first imaging modality used [1]. Using X-ray imaging, a physician can easily identify a mechanical break in the bone, narrow joint spacing, and other mechanical related issues. Osteoporosis can also be identified with a radiograph based on the apparent density of the bone, but this is significantly more difficult. A limitation of X-ray imaging is that it does not effectively differentiate between the major types of soft tissue, such as muscle, ligaments, cartilage, and others. To identify abnormalities or problems with these tissues, a physician must use other imaging modalities. Magnetic Resonance Imaging (MRI) is a multi-planar imaging technique that is better suited to help identify problems with soft tissue. MRI is capable of identifying tears of muscle, tendons, and ligaments, as well as loss of cartilage and inflammation in the joint space [1]. MRI is often used to examine the patient if the patient's symptoms are suspected to relate to back and neck, as MRI can effectively visualize the nerves in this area. If these imaging modalities prove inconclusive, ultrasound may be used to further evaluate the issue. Because ultrasound reflects off bone, it is more useful for diagnosing soft tissue related problems, as opposed to skeletal. Ultrasound can effectively visualize tendons and check for damage, continuity, tears, and inflammation. Fluid appears black on ultrasound, which makes identifying extra fluid (inflammation) in a joint area somewhat easy for the physician. Ultrasound is also used for guidance of injections/aspirations because of its real time feedback and its ability to distinguish between soft tissues.

Various laboratory tests are also used by physicians to properly diagnose a patient. After taking the history and physical, the physician will decide which tests they deem important for confirming or ruling out certain pathologies. Due to the vast number of existing blood tests, only several important examples will be discussed here. A main goal of many laboratory tests is to determine if the symptoms are a result of inflammation. The erythrocyte sedimentation rate measure level of inflammation is one test to accomplish this. This test measures the rate of fall of red blood cells, which is useful because blood cells of those suffering from inflammation tend to form stacks and have a higher sedimentation rate [2]. Measuring the C-reactive protein (CRP) is another test to gauge the level of inflammation, as CRP levels rise during inflammatory processes [2]. These tests are non-specific to arthritis and other musculoskeletal problems, however, and positive tests do not confirm that the inflammation is related to a patient's arthritic disease. Autoantibodies are another category of markers that rheumatologists use in diagnosis. Rheumatoid factor is an immunoglobulin that is highly correlated with rheumatoid arthritis (present/elevated in 50-75% of cases), and therefore evaluation of rheumatoid factors can impact the diagnosis [1]. Anti-cyclic citrullinated peptide antibodies (anti-CCP) are also useful in diagnosing RA because these antibodies are found in the serum of patients with RA 40-70% of the time [1]. The measurement of anti-CCP can also serve as an important predictor of RA, as 93% of patients with undifferentiated arthritis who also have anti-CCP are found to later develop RA [1]. Antinuclear antibodies (ANA) are those that target proteins within the cell nucleus [2]. These antibodies are potential markers of autoimmune disease because they can label self-proteins as a target for the body to attack. Physicians also check for anemia because it is common for patients with inflammatory disease to have a low red blood cell count. Aspiration of a joint, in which the physician drains and examines joint fluid, is another diagnostic test at the physician's disposal. Joint aspiration is performed to check cell count, which is related to inflammation, and examine possible infection.

8.4 Treatment options

Assuming a successful diagnosis is made, a physician must then focus on developing a treatment plan for the patient. The treatment plans for mechanical versus inflammatory arthritis can vary wildly. Oftentimes, if the OA is found early enough physical therapy is suggested, as therapy can strengthen nearby tendons, muscles, and ligaments to develop a support system for the weakened/damaged area. Weight loss may also be recommended if the patient is obese because the extra weight increases the load on the joints and can cause excess wear and tear. Similarly, lifestyle modifications may also be recommended if the patient is extremely active or participates in activities that put them at unnecessary risk. Another treatment option is the use of non-steroidal anti-inflammatory drugs (NSAIDs) that will provide pain relief, as well as mild anti-inflammatory effects [1]. Though NSAIDS reduce pain, they often do not improve the patient's outcome. Steroid injections are one of the last options for patients with bad OA and a considerable amount of inflammation before turning to surgical intervention. Cortisone is the steroid most commonly used and is a powerful anti-inflammatory that works to suppress the immune system in the injection area. This reduction of inflammation can also lead to temporary pain relief and improved joint function. If all of these options fail, surgical intervention is typically considered by the physician. With severe osteoarthritis, surgical intervention usually entails a joint replacement, as it is not possible to repair severe cartilage loss.

When upon diagnosis it is determined that the patient has inflammatory arthritis, other courses of treatment are pursued. A low-level anti-inflammatory, such as Advil, is usually tried first, as reduction of symptoms using Advil is preferable to the use of more serious drugs. If treatment with the low level anti-inflammatory is ineffective, Prednisone or another common corticosteroid is used, as these drugs suppress the immune system and can effectively treat autoimmune diseases. The next class of therapeutic drugs which is used if treatment is ineffective is disease modifying anti-rheumatic drugs (DMARD's). DMARD's are capable of reducing the progression of joint damage. Methotrexate is a preferred drug from this class, as it has shown to be effective for many years. Methotrexate alters T cell activation and expression, which limits the autoimmune response that the body mounts [3]. The new class of DMARD's that have emerged in recent years are called biologics. These are genetically engineered proteins that target specific components of the immune system to minimize its response [4]. Some examples of the major biologics prescribed are Adalimumab (Humira), Infliximab (Remicade), and Etanercept (Enbrel). Biologics have been proven very effective and in some patients can eliminate signs of the disease entirely. However, biologics should be avoided if the patient is immune compromised or currently has an infection, as the drugs target the TNF alpha pathway and reduce the immune system, leaving the patient more susceptible to these risks [4].

[1] Stephen A Paget, Allan Gibofsky, John F Beary III. Manual of rheumatology and outpatient orthopedic disorders. Diagnosis and therapy. 4th ed. Eds (Pp 592; 36-95) Philadelphia: Lippincott Williams and Wilkins, 2000. ISBN 0-7817-1576-8.

[2] Pisetsky DS. Laboratory testing in the rheumatic diseases. In: Goldman L, Schafer AI, eds. Goldman's Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 265.

[3] J. A. M. Wessels, T. W. J. Huizinga, H.-J. Guchelaar. Recent insights in the pharmacological actions of methotrexate in the treatment of rheumatoid arthritis. Rheumatology (2008) 47 (3): 249-255; 2007

[4] Keyser FD. Choice of Biologic Therapy for Patients with rheumatoid arthritis: the infection perspective. Curr Rheumatol Rev. Feb 2011; 7(1): 77-87