Knee pain resident survival guide

Knee pain Resident Survival Guide Microchapters
Overview
Causes
Diagnosis
Treatment
Do's
Don'ts

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Tayyaba Ali, M.D.[2]

Synonyms and keywords: Approach to knee stiffness, Approach to knee swelling, Approach to the hot knee joint

Overview

The knee joint has the largest articular space. The knee joint supports two to five times a person's body weight depending on the physical activity. There are both traumatic and non-traumatic conditions that cause knee pain. Lifestyle modification for knee pain includes Rest, Ice, Compression, and Elevation (RICE) for ligament injuries, Exercise, heat treatment, Paracetamol, symptomatic slow-acting drugs for OA (glucosamine, chondroitin, diacerein, and avocado–soya unsaponifiables), Restorative sleep advice and Weight loss. Knee pain should be treated depending on the underlying cause.

Causes

Traumatic and activity-related causes of knee pain

Anterior Knee Pain
Patellar subluxation or dislocation Tibial apophysitis (Osgood-Schlatter lesion) Jumper's knee (patellar tendonitis) Patellofemoral pain syndrome (chondromalacia patellae)
Medial Knee Pain
Medial collateral ligament sprain Medial meniscal tear Pes anserine bursitis Medial plica syndrome
Lateral Knee Pain
Lateral collateral ligament sprain Lateral meniscal tear Iliotibial band tendonitis
Posterior Knee Pain
A popliteal cyst (Baker's cyst) as a result of sport-related injury Posterior cruciate ligament injury

Non-Traumatic causes of knee pain

Unilateral Knee Pain
Septic Arthritis Gout Pseudogout (acute calcium pyrophosphate crystal arthritis)
Bilateral Knee Pain
Osteoarthritis [2] Rheumatoid Arthritis [3] Systemic lupus erythematosus Baker cyst as a result of rheumatoid arthritis and osteoarthritis

Diagnosis

The approach to the diagnosis of knee pain is based on a step-wise testing strategy. Below is an algorithm summarizing the identification and laboratory diagnosis of knee pain.

Seek proper history: Onset of knee pain Have you noticed: ❑ Warmth of joint ❑ Redness of joint ❑ Stiffness of joint ❑ Swelling of joint ❑ Weakness of joint ❑ Numbness or tingling of joint ❑ Discoloration of fingers in the cold ❑ Discomfort on exposure to sunlight ❑ Pain in any other joint

Examine the patient: ❑ HEENT signs: Conjunctival pallor Jaundice ❑ Inspection: Skin changes Color changes Physical abnormality Swelling Scar marks ❑ Palpation: Look for pain on palpation ❑ Range of motion: Perform extension and flexion of both knee joints ❑ Power Check power on flexion and extension ❑ Perform knee maneuvers for examination of knee ligament injuries Medial collateral ligament/Lateral collateral ligament injury: Valgus stress test Varus stress test Anterior collateral ligament injury: Anterior drawer test Lachman test Posterior collateral ligament injury: Posterior drawer test Posterior sag test Meniscal tear: Thessaly test Apley test McMurray test

Initial workup for knee pain: ❑ Complete blood count (CBC) with differential ❑ Erythrocyte sedimentation rate (ESR) ❑ Arthrocentesis and analysis ❑ X-ray knee anteroposterior (AP) view and lateral view ❑ CT scan knee MRI knee DEXA scan Ca++ and Vitamin-D levels

Knee pain associated with trauma

Knee pain not associated with trauma

Significant knee swelling ❑ Anterior cruciate ligament (ACL) tear ❑ Large meniscus tear ❑ Intra-articular fracture ❑ Osteochondral defect ❑ Patellar dislocation ❑ Posterior lateral corner tear ❑ Posterior cruciate ligament (PCL) tear ❑ Patellar tendon tear ❑ Quadriceps tendon tear ❑ Knee (tibiofemoral) dislocation

Limited knee swelling ❑ Small or moderate meniscus tear ❑ Medial collateral ligament (MCL) strain ❑ Lateral collateral ligament (LCL) strain ❑ Patellar subluxation ❑ Partial ACL tear ❑ Partial PCL tear ❑ Patella fracture ❑ Fibular neck or head fracture

Knee joint effusion present

Knee joint effusion absent

Activity related knee pain ❑ Chronic osteochondral defect ❑ Knee osteoarthritis

Not activity related knee pain ❑ Crystal arthropathy ❑ Septic arthritis ❑ Systemic rheumatic disease

According to the focus of knee pain

Anterior knee pain ❑ Tibial tubercle apophysitis (Osgood Schlatter) ❑ Hoffa's fat pad syndrome ❑ Quadriceps and patellar tendinopathy ❑ Prepatellar or infrapatellar bursitis ❑ Plica syndrome

Vague anterior knee pain ❑ Chronic patella dislocation or subluxation ❑ Patellofemoral pain ❑ Chondromalacia patella ❑ Patella stress fracture

Medial knee pain ❑ Degenerative medial meniscal tear ❑ Saphenous nerve entrapment ❑ Pes anserine bursitis

Lateral knee pain ❑ Iliotibial band syndrome ❑ Degenerative lateral meniscal tear

Posterior knee pain ❑ Popliteal artery aneurysm ❑ Popliteal artery entrapment ❑ Popliteal (Baker's) cyst ❑ Popliteus tendinopathy

Treatment

Life style modification for the knee pain depending on the condition Rest, Ice, Compression, and Elevation (RICE) for ligament injuries Exercise Heat treatment Paracetamol Symptomatic slow-acting drugs for OA (glucosamine, chondroitin, diacerein, and avocado–soya unsaponifiables) Restorative sleep advice Weight loss Treat the underlying causes

Knee pain due to septic arthritis IV antibiotics and joint drainage ❑ Gram-positive cocci: vancomycin ❑ Gram-negative rod: third-generation cephalosporin ❑ Negative microscopy: vancomycin (+ third-generation cephalosporin if immunocompromised)

Knee pain due to osteoarthritis ❑ Nonpharmacologic treatment (eg, exercise, weight loss) ❑ NSAIDS as needed (alternate: acetaminophen) ❑ If symtoms persist: Topical agents (eg, NSAIDs, capsaicin) Intra-articular glucocorticoids Intra-articular hyaluronic acid ❑ If significant impairment: Surgery (if possible) Chronic pain management (nonsurgical candidates)

Knee pain due to crystal arthropathy Gout ❑ Acute attack: NSAIDs Glucocorticoids Colchicine ❑ Recurrent attacks (Tophi, renal uric acid stones): Allopurinol Pseudogout Intra-articular glucocorticoids Nonsteroidal anti-inflammatory drugs Colchicine

Knee pain due to rheumatoid arthritis ❑ Methotrexate ❑ Persistent symptoms for >6 months: Step-up therapy: Add biologic agent (eg. TNF inhibitor) Parallel therapy: Add another nonbiologic agent (eg. sulfasalazine, hydroxychloroquine, leflunomide) ❑ Inadequate response: Switch to alternate TNF inhibitor & continue methotrexate

Knee pain due to systemic lupus erythematosis General treatment: Hydroxychloroquine Severe disease: Preferred regimen: Hydroxychloroquine and IV methylprednisolone Alternative regimen: (1) Hydroxychloroquine and oral prednisone (2) Mycophenolate (3) IV cyclophosphamide (4) IV Rituximab Less severe (mild and moderate) disease: Preferred regimen: (1) Hydroxychloroquine (2) Prednisone Alternative regimen: (1) Azathioprine (2) Methotrexate Chronic pain management: Moderate pain: Preferred regimen: Dextropropoxyphene Alternative regimen: Co-codamol (Acetaminophene + opioid)/; Acetaminophen/codeine Moderate to severe chronic pain: (1) Hydrocodone (2) Oxycodone Alternative regimen: (1) MS Contin (2) Methadone (3) Fentanyl

Do's

• US is an excellent and easily performed imaging study in the detection of knee joint effusions. However, because of its technical limitations, ultrasound (US) may only evaluate the outer bone surface and has a limited role in the detection of occult knee fractures.
• In patients with chronic knee pain, referred pain from the hip must be considered, especially if the knee radiographs are unremarkable and there is clinical evidence or concern for hip pathology.
• When an intra-articular abnormality is suspected, CT arthrography may be used instead of MRI to evaluate the menisci and articular cartilage.
• When initial radiographs are normal or reveal a joint effusion but pain persists, the next indicated study is usually MRI without IV contrast, which is more sensitive than radiography.
• Ultrasound (US) is not often useful as a screening test or a comprehensive examination. It may be appropriate to confirm a suspected effusion and to guide a potential aspiration. The US is as accurate in diagnosing a popliteal cyst and detecting cyst rupture when compared to MRI.
• Radiographs of the knee are usually appropriate for the initial imaging of chronic knee pain in patients greater than or equal to 5 years of age.
• Knee radiographs may be appropriate for the initial imaging of patients 5 years of age or older for the evaluation of a fall or acute twisting trauma to the knee when there is no focal tenderness, no effusion, and they are able to walk.
• Knee radiographs are usually appropriate as the initial imaging study of patients 5 years of age or older for the evaluation of a fall or acute twisting trauma to the knee when at least one of the following is present: focal tenderness, effusion, inability to bear weight.
• MRI knee without IV contrast is usually appropriate as the next imaging study, after radiographs did not show a fracture, of adults or skeletally mature children, for the evaluation of suspected occult knee fractures or internal derangement after a fall or acute twisting trauma to the knee.
• MRI knee without IV contrast is usually appropriate as the next imaging study after radiographs did not show a fracture, of skeletally immature children, for the evaluation of suspected occult knee fractures or internal derangement after a fall or acute twisting trauma to the knee.

Don'ts

• With negative radiographs, MR arthrography is not routinely used as the next imaging study for the evaluation of suspected occult knee fractures or internal derangement.
• With negative radiographs, MRA is not routinely used as the next imaging study for the evaluation of suspected occult knee fractures or internal derangement.
• Ultrasound (US) is not used as the next best imaging study to evaluate for radiographically occult fractures and/or internal derangement.
• Radionuclide bone scan is usually not indicated to evaluate patients with signs of a prior (chronic) osseous knee injury.
• Joint aspiration is usually not indicated to evaluate patients with signs of the prior (chronic) osseous knee injury.