What could be causing left knee pain with numbness and tingling, without back pain?

Left Knee Pain with Numbness and Tingling Without Back Pain

The most likely causes are peripheral nerve pathology (particularly saphenous neuritis), peripheral arterial disease affecting tibial arteries, or referred pain from hip pathology—despite the absence of back pain, lumbar spine pathology must still be excluded before attributing symptoms solely to knee structures. 1

Critical First Step: Rule Out Referred Pain

Even without back pain, you must evaluate for:

• Lumbar spine pathology – can present with knee symptoms alone, particularly when radiographs are unremarkable 1
• Hip pathology – commonly refers pain to the knee and should be evaluated if knee imaging is normal 1
• Perform thorough clinical examination of lumbar spine and hip before knee-focused imaging 1, 2

This is a common pitfall: overlooking referred pain from hip or lumbar spine before attributing symptoms solely to knee pathology 1, 2

Primary Differential Diagnoses for Numbness/Tingling

Saphenous Neuritis (Most Likely Nerve Cause)

• Characterized by allodynia along the course of the saphenous nerve at the medial knee 3
• Can imitate medial meniscal tear or osteoarthritis 3
• Often has indolent, protracted course and may coexist with other knee pathology 3
• Diagnosis confirmed by relief after local anesthetic injection of the affected area 3
• Palpation of the saphenous nerve should be part of every routine knee examination 3

Peripheral Arterial Disease

• Occlusive disease in tibial arteries produces calf pain or, more rarely, foot pain and numbness 4
• Exercise-induced symptoms that resolve with rest suggest vascular claudication 4
• Look for diminished pulses in femoral, popliteal, posterior tibial, and dorsalis pedis arteries 4
• Femoral bruits may indicate systemic atherosclerosis 4

Other Structural Knee Pathology with Nerve Involvement

• Popliteal (Baker's) cysts can cause posterior knee pain and may compress nerves 1
• Tumors and ganglion cysts can cause knee pain, swelling, and nerve compression 1

Diagnostic Approach

Physical Examination Priorities

• Palpate the saphenous nerve distribution along medial knee 3
• Check all lower extremity pulses bilaterally 4
• Assess for femoral bruits 4
• Examine hip range of motion and perform hip provocation tests 1
• Perform lumbar spine examination including straight leg raise 1

Imaging Strategy

• Initial radiographs reserved for chronic knee pain, suspected fracture, or degenerative changes 5
• MRI only when surgery considered, pain persists despite conservative treatment, or radiographs normal but symptoms persist 5
• If knee imaging unremarkable and clinical evidence suggests spinal origin, image lumbar spine 1
• Consider hip imaging if knee evaluation is normal 1

Diagnostic Injection

• Local anesthetic injection at site of maximal tenderness along saphenous nerve confirms saphenous neuritis if symptoms relieved 3

Treatment Algorithm

For Saphenous Neuritis

1. Initial non-surgical symptomatic care 3
2. Diagnostic/therapeutic injections of local anesthetic 3
3. Treat any associated knee pathology 3
4. Surgical decompression and neurectomy for recalcitrant cases 3

For Peripheral Arterial Disease

• Comprehensive risk factor modification and antiplatelet therapy 4
• Consider revascularization if significant disability present and anatomy favorable 4

Conservative Management for Structural Knee Pathology

• Exercise therapy, weight loss if overweight, education, and self-management programs 6
• First-line for most knee conditions including osteoarthritis 6

Key Clinical Pitfalls

• Not all structural abnormalities are symptomatic – particularly in patients over 45 years 1
• Premature MRI should be avoided – approximately 20% of chronic knee pain patients undergo MRI without recent radiographs 1
• Saphenous neuritis frequently unrecognized, confusing clinical picture and compromising treatment results 3
• Radiographs may be initially normal in subchondral insufficiency fractures 1