OSTEOARTHRITIS
BACKGROUND
Osteoarthritis (OA) is the single most common disease of the joints; as such, it is one of the most impor-tant causes of morbidity in the United States. Loss of articular cartilage in the synovial joint is the primary pathologic lesion. This loss can be due to repetitive load-bearing stress or intrinsic properties of either the cartilage or bone or in the body's ability to repair these structures. Joints commonly involved include the first carpometacarpal joint, hip, knee, and spine. Risk factors include age, obesity, and female sex. Secondary OA can occur after major trauma to the joint; repetitive stress; prior inflammatory joint disease; metabolic disease, including ochronosis, hemochromatosis, and Wilson disease; and endocrine disease, including acromegaly, diabetes, and hyperparathyroidism.
HISTORY AND PHYSICAL EXAMINATION
Patients are usually older than 55 years. Typical complaints include a deep ache in the affected joint that is exacerbated by activity. Stiffness is common, especially after inactivity, but usually resolves with use. There are no systemic symptoms. Although OA is not considered an inflammatory arthritis, inflammation does play a significant role in the development of asso-ciated pain and swelling.
Physical examination reveals limitation of motion secondary to pain. Localized tenderness and soft tissue swelling may be present. Motion of the joint may produce bony crepitus. As the disease progresses, there may be gross deformities of the joint, with loss of motion.
Hip OA may be experienced as groin pain. On examination, internal rotation is often the first motion to become painful and restricted.
Knee OA may result in stiff knees that are more painful with prolonged sitting, walking, and climbing stairs.
First carpometacarpal OA often results in stiffness and pain in the joint. On examination, the "grind test," in which the joint is compressed, is positive.
DIAGNOSTIC EVALUATION
Radiographic examination reveals narrowing of joint spaces (Figs. 25-1 and 25-2). Subchondral cysts, bone sclerosis, and osteophytes may be present. In primary OA, laboratory values are normal. Specific lab tests may be useful to diagnose causes of secondary OA. Synovial fluid usually reveals a mononuclear leukocytosis; this test may be useful to exclude other diagnoses, including a septic joint.
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Figure 25-1 • X-ray appearance of osteoarthritis of the knee. Reproduced with permission from Duckworth T. Lecture Notes on Orthopaedics and Fractures. 3rd ed. Cambridge, MA: Blackwell Science, 1995. |
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Figure 25-2 • X-ray appearance of osteoarthritic hip. Reproduced with permission from Duckworth T. Lecture Notes on Orthopaedics and Fractures. 3rd ed. Cambridge, MA: Blackwell Science, 1995. |
It is important to note that radiographic findings of osteoarthritis are not always correlated with symptoms. A patient with significant OA on x-ray may be symptom-free. The reciprocal is also true: a patient with minimal x-ray findings of OA may have significant symptoms. The patient with OA must be treated, not the film.
TREATMENT
Therapy for osteoarthritis should be based on the severity of the symptoms. In general, exercises to stretch and strengthen the muscles surrounding the
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joint are critical. Joints face an enormous amount of daily stress. Descending stairs, for example, results in the knee bearing five to six times the body weight load. Weak or tight muscles result in excessive forces being placed through the joint itself, rather than being relieved by the muscles.
No pharmacologic interventions can reverse the lesions of osteoarthritis, but nonsteroidal anti-inflammatory agents, as well as analgesics (e.g., acetaminophen), can provide symptomatic relief for pain.
Nutritional supplements such as glucosamine and chondroitin sulfate have received much attention for the prevention and treatment of osteoarthritis. Their usage remains controversial. However, because of their low side-effect profile (in contrast with nonsteroidal anti-inflammatory drugs), their use has become more widespread. Superficial joints, such as those of the fingers and toes, may benefit from topical analgesics.
Intra-articular corticosteroids can be extremely effective for pain. The number of corticosteroid injections that can be performed per joint remains controversial. Some physicians advocate a total of three corticosteroid injections in the life of a joint, whereas others argue that three injections per year are safe.
Hyaluronic acid injections may also be of benefit. These injections are approved by the U.S. Food and Drug Administration for knee OA, and they are being used with increasing frequency, off-label, for hip OA. Some studies are also investigating their use for ankle, shoulder, and elbow OA.
Surgical treatment should be reserved for patients with debilitating pain or compromised quality of life after nonsurgical options are exhausted. In patients with mild disease, particularly younger patients who want to remain more active, osteotomy may produce significant pain relief. In the knee, an osteotomy is not an option if the patient is unable to flex the knee past 90 degrees or if he or she has more than 15 to 20 degrees of valgus deformity.
Total joint arthroplasty for hip and knee OA has excellent results in patients with more advanced disease. In the hip, a polymethylmethacrylate cemented or cementless prosthesis may be used. A cemented prosthesis has the advantage of allowing the patient full weight bearing and quicker healing immediately after the procedure. Cementless prostheses have the potential advantage of ultimately achieving longer life and durability once they have matured. The disadvantage is that the patient may have greater postoperative pain and must remain toe-touch weight bearing (putting less than 10% of body weight on the affected limb) for at least 6 to 8 weeks. In general, a cemented prosthesis is recommended for an older, less active patient, and a cementless prosthesis is recommended for a younger, more active patient. A hemiarthroplasty in the hip is another option. In contrast to a total joint arthroplasty, which involves replacing the femoral head and the acetabulum, a hemiarthroplasty involves only replacing the femoral head.
The most common surgical approach for a total hip replacement is posterior. After a posterior approach,
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hip precautions include (1) no hip flexion beyond 90 degrees, (2) no hip adduction past neutral, and (3) no hip internal rotation beyond neutral.
In the knee, cemented, cementless, and hybrid prostheses are available. However, cement fixation is by far the most common. After a cemented total knee replacement, patients should expect to gradually return to their activities in 1 to 3 months.
When considering any major surgery, it is vital to consider anticoagulation after the procedure. This is particularly true with total knee and hip replacements. After a total knee replacement, as many as 64% of patients may develop a clot if not anticoagulated. Only 6% to 24% may develop a clot if properly anticoagulated. In the hip, >50% of patients who do not receive adequate anticoagulation may develop a clot. Anticoagulation options include warfarin (keeping the international normalized ratio between 2 and 3), aspirin 325 mg orally twice per day, subcutaneous heparin 5,000 U twice per day, low molecular heparin, and possibly an inferior vena cava filter for patients who are not candidates for anticoagulation.
JOINT PAIN
It is important to distinguish between acute and chronic causes of pain. Critical questions include history of trauma, swelling, decreased range of motion, and problems with weight bearing. Positions or circumstances that alleviate or exacerbate the pain may yield clues to the diagnosis.
On physical examination, a careful assessment for swelling, joint effusion, range of motion, deformity, tenderness, and instability should be made.
KNEE PAIN: COMMON DIAGNOSES
Meniscal Injury
Meniscal injuries are more common in men but can occur in women. Injury to the medial meniscus is more common than injury to the lateral meniscus. Pain is the most common symptom. Patients also may complain of knee locking or clicking. Effusions may be present, and weight bearing may be difficult. Examination usually reveals joint line tenderness. A McMurray test is often positive. In this test (Fig. 25-3), the patient is in the supine position. The examiner flexes the knee while palpating the joint line. Using the ankle as a fulcrum, the leg is externally rotated and a valgus stress is applied as the knee is extended. A palpable or audible click, or recreation of symptoms in the knee, is considered a positive test result. The grinding and distraction test of Apley is also useful (Fig. 25-4). In this test, the patient lies prone with the knee flexed to 90 degrees. Using the ankle as a fulcrum, again, the examiner first internally and externally rotates the leg while compressing the tibia into the table. The examiner then internally and externally rotates the leg while distracting the tibia. If pain is produced while grinding but not while distracting, the meniscus is implicated as the cause of
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pain. If pain is produced during both distraction (when the meniscus is unloaded) and grinding, the ligaments are more likely involved.
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Figure 25-3 • The McMurray test is performed with the leg externally rotated and applying a valgus stress to test the medial meniscus. Reproduced with permission from Gross JM, Fetto J, Rosen E. Musculoskeletal Examination. 2nd ed. Malden, MA: Blackwell, 2002. |
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Figure 25-4 • The grinding/distraction test of Apley. The tibia is compressed first (A), then rotated while compression force is maintained (B). Distraction with rotation tests the collateral ligaments, whereas compression with rotation tests the menisci. Reproduced with permission from Gross JM, Fetto J, Rosen E. Musculoskeletal Examination. 2nd ed. Malden, MA: Blackwell, 2002. |
Magnetic resonance imaging (MRI) is accurate and sensitive for meniscal injury. Not all meniscus lesions require surgery. Conservative therapy is indicated, particularly if the tear is ≤10 mm or partial thickness or if a radial tear is ≤3 mm. However, even larger tears may respond to conservative therapy. If locking is present and significant, surgical intervention should be considered sooner. Surgical options include arthroscopic meniscectomy and meniscus repair. For tears in the vascular region (in the peripheral part of the meniscus), arthroscopic meniscus repair with fixation using the outside-in, inside-out, or all-inside method is recommended.
Cruciate Ligament Injury
The cruciate ligaments stabilize the knee to translational motion. Acute pain in the setting of trauma and subsequent swelling should alert the examiner to this possibility. Typically, a twist or hyperextension trauma causes these lesions. The pain may improve after the initial injury, but chronic pain may develop. The anterior cruciate ligament (ACL) is most commonly torn. Between 30% and 50% of people will report hearing a popping sound at the time of tearing their ACL. The most sensitive diagnostic maneuver for ACL is the Lachman test (Fig. 25-5). In this test, the knee is flexed 20 to 30 degrees and the examiner applies an anteroposterior glide. A few degrees of anteroposterior glide may be normal. It is important to always compare side-to-side findings. A loose end point or excessive glide is a positive finding for an ACL tear.
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Figure 25-5 • The position of the examiner and patient for the Lachman test. It is important that the patient be relaxed for this test. Reproduced with permission from Gross JM, Fetto J, Rosen E. Musculoskeletal Examination. 2nd ed. Malden, MA: Blackwell, 2002. |
The medial collateral ligament is evaluated by applying a valgus stress and comparing glide side-to-side (Fig. 25-6). The posterior cruciate ligament and lateral collateral ligament are likewise evaluated by stressing those ligaments.
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Figure 25-6 • Valgus strain (medial gapping). Reproduced with permission from Gross JM, Fetto J, Rosen E. Musculoskeletal Examination. 2nd ed. Malden, MA: Blackwell, 2002. |
Treatment is typically conservative, focusing on strengthening the surrounding muscles and gradually returning to activity. Depending on the severity of injury, the ACL may be repaired by arthroscopic allograft or autograft. The allograft, taken from a cadaver, has the advantage of not requiring tissue collection of the graft from the patient. Allografts are irradiated to greatly reduce the chance of infection. Autografts are performed by either taking a segment of the patient's hamstrings or patella tendon. The disadvantage of these procedures is primarily the occurrence of increased postoperative wound pain. Both surgical approaches have similar long-term outcomes.
Medial collateral ligament and posterior cruciate ligament injuries are generally treated conservatively unless the ligament is severely torn.
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Patellofemoral Syndrome
Patellofemoral syndrome is common in young adults. The pain is generally anterior. A positive "theatre sign" is characteristic. When positive, the patient has trouble sitting for a long period of time (such as at a theatre) and must extend the knee (placing his or her foot into the aisle) to relieve the discomfort. Pain is also exacerbated by running and ascending/descending stairs. Tenderness is usually present under the patella. The Q-angle, which is the angle formed by a line drawn from the anterior superior iliac spine to the mid patella and transected by a line drawn from the mid patella to the tibial tubercle with the knee in full extension, is usually increased (>17 degrees in women and >14 degrees in men;Fig. 25-7).
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Figure 25-7 • Measurement of the Q-angle. Reproduced with permission from Gross JM, Fetto J, Rosen E. Musculoskeletal Examination. 2nd ed. Malden, MA: Blackwell, 2002. |
The problem is primarily caused by patellar mis-alignment and abnormal tracking. Classically, the patella tracks excessively laterally. Treatment focuses on strengthening the quadriceps, particularly the vastus medialis oblique, and stretching the iliotibial band. Patellar taping or bracing may also be somewhat helpful. Surgical correction is rarely indicated but may be used when conservative care is not sufficient and an identifiable anatomic abnormality is present, such as isolated lateral patellar tilt that may be arthroscopically released.
SHOULDER PAIN: COMMON DIAGNOSES
A variety of structures within the shoulder can be injured or inflamed, but most problems respond to conservative therapy.
Impingement Syndrome
Impingement syndrome includes rotator cuff tendonitis and subacromial bursitis. These two conditions often coexist and are treated in much the same way. To diagnose impingement syndrome, Neer and Hawkins' tests are useful. In the Neer test, the examiner stabilizes the patient's scapula with one hand and internally rotates and flexes the shoulder with the other. As the shoulder is elevated, the greater tuberosity of the humerus abuts the coracoacromial arch, placing pressure on the rotator cuff tendon. Result for this test is considered positive when symptoms are reproduced. The same maneuver but with the shoulder in external rotation often produces less or no pain. In the Hawkins' test, the patient's shoulder is abducted to 90 degrees in the plane of the scapula and the elbow is flexed to 60 to 90 degrees. The shoulder is then placed firmly into internal rotation (Fig. 25-8). When this reproduces pain, the test result is considered positive for impingement syndrome.
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Figure 25-8 • The supraspinatus impingement test (Hawkins' test) being performed. Reproduced with permission from Gross JM, Fetto J, Rosen E. Musculoskeletal Examination. 2nd ed. Malden, MA: Blackwell, 2002. |
The best test for impingement syndrome is to inject 3 to 5 mL of 1% lidocaine into the subacromial space and repeat the Neer and Hawkins' tests. With the lidocaine injected, these maneuvers should be significantly less painful. If so, the patient likely has impingement syndrome.
Impingement syndrome responds well to physical therapy that focuses on scapular stabilization and rotator cuff strengthening exercises. A subacromial corticosteroid injection can also be very effective and help speed recovery.
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Biceps Tendonitis
The biceps tendon crosses the shoulder joint and may become inflamed where it traverses the bicipital groove. This is best identified by tenderness to palpation and a positive Speed test result. In the Speed test, the patient's shoulder is flexed to 90 degrees with the elbow extended. The patient then resists the examiner who applies an inferior force to the patient's arm. Reproduction of pain is consistent with bicipital tendonitis.
Glenohumeral Labral Tear
A labral tear may be identified on physical examination by the O'Brien test. In this test, the patient's shoulder is flexed, adducted, and externally rotated. An inferior force is applied by the examiner. The arm is then placed in internal rotation and an inferior force is again applied (and resisted by the patient). If symptoms are reproduced when the shoulder is internally rotated (thumb facing down) but not in external rotation (thumb facing up), the test is considered positive for a labral tear. An MRI is the best way to evaluate for a labral tear. Not all labral tears require surgery. Conservative care includes physical therapy and, in some cases, an intra-articular corticosteroid injection.
Rotator Cuff Tear
The rotator cuff is a collection of the tendons of the supraspinatus, infraspinatus, subscapularis, and teres minor. The most common tendon to tear is the supraspinatus. On examination, a supraspinatus tear will result in weak abduction, particularly from 0 to 30 degrees. MRI is sensitive and specific for rotator cuff injuries (Fig. 25-9). Surgery is an option if conservative measures fail.
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Figure 25-9 • Magnetic resonance imaging of normal rotator cuff (*) and surrounding structures. H, humerus, G, glenoid. Reproduced with permission from Gross JM, Fetto J, Rosen E. Musculoskeletal Examination. 2nd ed. Malden, MA: Blackwell, 2002. |
BACK PAIN
Back pain is an epidemic in the United States, causing chronic disability in 1% of the population, with a cost of approximately $50 billion annually. Back pain can be divided into acute pain from a muscle strain or spasm and subacute or chronic pain that is more likely a result of intervertebral disc irritation, zygapophysial (facet) joint pain, or sacroiliac joint pain. A radiculitis can also result if a nerve root is irritated. A radiculitis characteristically involves pain radiating into the lower extremity.
FACET JOINT PAIN
The facet joints in the spine are synovial joints (similar to the knee joint). These joints can become arthritic, just like the knee. These joints are a common source of lower back pain. Pain is usually exacerbated by trunk extension and oblique extension. Treatment options include physical therapy, facet joint injections, and radiofrequency neurotomy to essentially sever the medial branches of the dorsal rami that innervate the involved joints.
DISCOGENIC PAIN
The disc is the most common cause of chronic lower back pain in the younger population and is also a common cause of pain in older populations. A herniated disc is not synonymous with discogenic back pain. When discs cause pain, it is because the annulus of the disc has torn internally and the nucleus pulposus (which is full of inflammatory proteins) is irritating the pain receptors in the outer third of the annulus. A painful disc may appear normal on MRI. Reciprocally, a herniated disc may not be the source of back pain. A herniated disc is more commonly associated with nerve root impingement or irritation, which would result in a radiculitis, causing electric, radiating pain into the lower extremity.
Discogenic pain is typically worse with trunk flexion. Prolonged sitting may make the pain worse. Though somewhat controversial, definitive diagnosis is accomplished using provocative discography in which dye is injected under x-ray guidance into the disc. When
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this reproduces the patient's pain at low injection pressures, the disc is considered positive. Postdiscography computed tomography will often reveal the extent of the torn annulus (when present).
Treatment includes physical therapy that focuses on extension-based lumbar stabilization and stretching and strengthening the surrounding muscles. Fusion is reserved for patients for whom more conservative measures have failed.
NEOPLASM
Metastatic cancer must always be included in the differential diagnosis of back pain. Cancer pain in the back tends to be worse at night, and may wake the patient up from sleep. X-rays, bone scan, and MRI all may be used as part of the workup, depending on the index of suspicion. Though much less common, primary bone tumors in the spine can also occur.
INFECTION
Osteomyelitis of the spine most commonly occurs in debilitated patients or intravenous drug abusers and is usually associated with some type of systemic infection. Patients will usually have tenderness at the site and with movement. Pain is typically constant, and signs of systemic infection are present. The sedimentation rate is often elevated. Plain films may be negative initially, MRI is usually diagnostic, and a tagged white cell scan may light up the affected area.
HIP FRACTURE
Hip fracture is the most common fracture causing hospital admission. Approximately 300,000 hip fractures occur each year in the United States. The generally advanced age of patients with this problem leads to a staggering 50% 1-year mortality rate after injury. Hip fractures are twice as common in women. Three general types of fracture occur: fractures of the femoral neck, intertrochanteric fractures, and subtrochanteric fractures (Fig. 25-10).The first two are by far the most common and usually occur in older adults as a result of a relatively low-impact type of injury.
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Figure 25-10 • Diagram of common points of femoral fracture. Reproduced with permission from Uzelac A, Davis RW. Blueprints Radiology. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins, 2006. |
The typical history involves an older adult patient who falls and has subsequent hip, groin, or knee pain. Weight bearing is often difficult. On examination, patients with femoral neck fractures may have a shortened and externally rotated extremity. Hip motion may be painful. Diagnosis is usually confirmed with plain radiograph films (Fig. 25-11). MRI should be obtained if x-rays appear normal but clinical evidence is suggestive
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of possible fracture (x-rays may miss up to 67% of acute hip fractures, according to one study).
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Figure 25-11 • Hip fracture. Intertrochanteric fracture in the right hip of an 83-year-old woman who fell after getting out of bed. Courtesy of Cedars-Sinai Medical Center, Los Angeles, CA. |
Treatment is based on comorbidities and degree of fracture (Tables 25-1 and 25-2). If the acetabulum is involved in the fracture, total hip replacement must be considered.
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TABLE 25-1 Garden Classification and Treatment |
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TABLE 25-2 Jensen Classification of Intertrochanteric Fractures |
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Both stable and unstable intertrochanteric fractures are typically treated with open reduction and internal fixation using the sliding screw hip implant. Fracture healing time after surgery is approximately 12 weeks.
It is critical to properly anticoagulate patients after a hip fracture. Failure to do so may lead to a lower-extremity deep venous thrombosis and/or fatal pulmonary embolism in 40% to 83% of patients. These numbers are greatly reduced (to 4% to 38%) in patients who receive appropriate anticoagulation. High-risk patients, or patients who are not candidates for anticoagulation, may require an inferior vena cava filter.
SEPTIC JOINT CONSIDERATIONS
A septic joint requires appropriate, prompt attention. Clinical signs and symptoms of a septic joint include fevers, chills, and a hot, red, swollen joint. A low index of suspicion should be used for septic joint, because failure to diagnose and treat this condition quickly may result in destruction of the joint. If suspected, the joint should be aspirated and the fluid sent for analysis. Blood tests should also be performed. If clinical suspicion is high, treatment should be started before lab results have been obtained. Treatment includes intravenous and/or oral antibiotic treatment.
Laboratory studies should include a complete blood cell count with differential and erythrocyte sedimentation rate. If positive, complete blood cell count may show increased white blood cell count (>12,000/mL) with a left shift. Erythrocyte sedimentation rate is typically elevated (>40 mm/h). Other laboratory tests may include a Lyme test and blood cultures.
If suspected, a urethral or cervical culture may be obtained to evaluate for Neisseria gonorrhoeae. The fluid aspirate should be sent for Gram stain, culture, cell count, and crystal analysis. Table 25-3 presents results analysis.
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TABLE 25-3 Synovial Fluid Classification |
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Corticosteroid injection should NOT be administered if sepsis is suspected.
If infection is confirmed, drainage in combination with continued intravenous antibiotics is the treatment of choice. Drainage may be attempted by percutaneous aspiration; however, surgical drainage is often required if percutaneous aspiration is not adequate.
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KEY POINTS