What is the appropriate examination for a patient with knee pain and potential kidney disease, considering their age, medical history (including diabetes or hypertension), and impaired renal function?

Examination for Knee Pain in Patients with Kidney Disease

Begin with a thorough physical examination of the knee itself, including inspection for effusion/erythema, palpation of joint lines and ligaments, range of motion testing, and provocative maneuvers, while simultaneously examining the hip for range of motion limitations and groin pain to exclude referred pathology. 1, 2, 3

Essential Physical Examination Components

Knee-Specific Examination

• Inspection: Assess for swelling, erythema, deformity, muscle atrophy, and gait abnormalities 3, 4
• Palpation: Systematically palpate the medial and lateral joint lines, patella, patellar tendon, tibial tubercle, and collateral ligaments to localize tenderness 3, 4, 5
• Range of motion: Document active and passive flexion/extension, noting any mechanical symptoms like catching or locking 3, 4
• Provocative tests: Perform McMurray test for meniscal tears, Lachman and anterior drawer for ACL integrity, and patellar apprehension test for instability 3, 4
• Neurovascular assessment: Check distal pulses, capillary refill, and sensation, particularly important given the increased neuropathy risk in diabetic patients with CKD 6

Critical Examination for Referred Pain Sources

• Hip examination: Test internal/external rotation, flexion, and extension; assess for groin pain or positive impingement signs, as hip pathology commonly refers pain to the knee 1, 2
• Lumbar spine assessment: Evaluate for radiculopathy patterns, straight leg raise, and neurogenic claudication symptoms 1, 2
• Peripheral neuropathy screening: In diabetic patients with CKD, assess light touch, vibratory sensation, and ankle reflexes in a stocking distribution 6

Special Considerations for Patients with Kidney Disease

Diabetic Patients with CKD

• Comprehensive foot and lower extremity examination: Diabetic patients with CKD require regular podiatric assessment given their increased risk of ulcers and amputations 7
• Sensory testing: Document loss of protective sensation using monofilament testing, as peripheral neuropathy affects up to 50% of diabetic patients with CKD 6
• Vascular assessment: Check pedal pulses and assess for peripheral artery disease, though ankle-brachial index may be unreliable due to vessel calcification in CKD 7

Cardiovascular Examination

• Blood pressure measurement: Check both supine and standing blood pressures to assess for orthostatic hypotension, which may indicate autonomic neuropathy in diabetic patients with CKD 6
• Volume status: Assess for edema, jugular venous distension, and signs of fluid overload, as these affect management decisions 7

Laboratory Assessment Alongside Physical Examination

All patients with CKD require yearly measurement of serum creatinine, urinary albumin excretion, and potassium regardless of GFR level. 7

Based on GFR Stage:

• GFR 45-60 mL/min/1.73 m²: Monitor eGFR every 6 months; check electrolytes, bicarbonate, hemoglobin, calcium, phosphorus, and parathyroid hormone at least yearly 7
• GFR 30-44 mL/min/1.73 m²: Monitor eGFR every 3 months; check electrolytes, bicarbonate, calcium, phosphorus, parathyroid hormone, hemoglobin, albumin, and weight every 3-6 months 7
• GFR <30 mL/min/1.73 m²: Requires nephrologist referral 7

Common Pitfalls to Avoid

• Do not skip hip examination: Approximately 20% of patients with knee pain have hip pathology as the source; always examine the hip when knee radiographs are normal 1, 2
• Do not overlook autonomic neuropathy: In diabetic patients with CKD presenting with knee pain, assess for orthostatic hypotension and other autonomic symptoms that may complicate management 6
• Do not assume all pain is mechanical: Patients with advanced CKD may have metabolic bone disease, secondary hyperparathyroidism, or crystal arthropathy contributing to knee pain 7
• Do not forget medication review: Assess all medications for appropriate renal dosing, as many drugs require adjustment based on GFR 7

When to Refer

• Nephrologist referral: Consider when eGFR <30 mL/min/1.73 m², heavy proteinuria, active urine sediment, rapid decline in GFR, or difficult management issues like resistant hypertension or electrolyte disturbances 7
• Orthopedic referral: Indicated for severe pain with instability, inability to bear weight, suspected fracture, or mechanical symptoms suggesting surgical pathology 3, 4
• Podiatry referral: All diabetic patients with CKD should receive regular podiatric assessment 7