Which nerve causes right hip and upper leg pain?

Hip and Upper Leg Pain: Nerve Etiologies

Multiple nerves can cause right hip and upper leg pain, with the femoral nerve, lateral femoral cutaneous nerve (LFCN), obturator nerve, and sciatic nerve being the primary culprits depending on the specific pain distribution and associated symptoms. 1, 2

Primary Nerve Causes by Pain Distribution

Anterior Hip and Thigh Pain

• Femoral nerve compression or injury causes anterior hip and thigh pain with weakness in knee extension and hip flexion, as this nerve's primary function involves these movements 2
• Femoral neuropathy can result from hip positioning that extends beyond normal comfortable range (hyperlordosis) or excessive hip flexion beyond 90 degrees 1, 3
• The femoral nerve arises from L2-L4 nerve roots and descends through the pelvis before emerging in the lower limb 2
• Femoral neurostenalgia (compressive neuropathy) can present as debilitating hip pain that may persist despite other orthopedic interventions 4

Lateral Thigh Pain (Without Weakness)

• Lateral femoral cutaneous nerve (LFCN) compression causes meralgia paresthetica, presenting as burning pain, dysesthesia, or numbness over the lateral thigh without motor weakness 3, 5
• Hip flexion beyond 90 degrees and sitting cross-legged increase LFCN compression risk by creating tension and pressure at the inguinal ligament 3
• The LFCN passes through an "aponeuroticofascial tunnel" near the anterior superior iliac spine, where entrapment commonly occurs 5
• In 36% of cases, there is no posterior branch of the LFCN, explaining why symptoms are often limited to the anterior lateral thigh region 5

Medial Thigh Pain

• Obturator nerve injury causes medial thigh pain with weakness in thigh adduction and sensory changes over a small area of the medial thigh 2
• The obturator nerve also arises from L2-L4 nerve roots and shares similar pelvic anatomy with the femoral nerve 2

Posterior Hip and Leg Pain

• Sciatic nerve compression causes pain radiating down the leg below the knee, representing the most common symptom of lumbar radiculopathy 6
• Stretching the hamstring muscle group beyond comfortable range may increase sciatic neuropathy risk, as the sciatic nerve crosses both hip and knee joints 1, 6
• Limiting hip flexion to 90 degrees may reduce sciatic neuropathy risk in certain positions 1

High-Risk Positions That Exacerbate Nerve Compression

Femoral Nerve

• Hip extension beyond normal comfortable range (hyperlordosis) in supine position may increase femoral neuropathy risk, though evidence remains equivocal with 40% agreement among consultants and 51% undecided 1
• Hip flexion beyond 90 degrees, particularly in lithotomy position, shows mixed evidence with 40% of consultants agreeing this reduces risk while 44% believe any degree of hip flexion poses no increased risk 1

Lateral Femoral Cutaneous Nerve

• Hip flexion beyond 90 degrees increases LFCN tension and compression symptoms 3
• Sitting cross-legged on the floor creates both hip flexion and external rotation, stretching the nerve and increasing pressure at the inguinal ligament 3
• Prolonged sitting on hard surfaces without padding increases direct pressure on the anterior superior iliac spine region 3

Sciatic Nerve

• Vertical leg extension with maximum external rotation of thighs in lithotomy position can cause sciatic neuropathy 1
• Hip flexion of 90 degrees in sitting position has been associated with sciatic nerve injury 1
• Positions stretching the hamstring muscle group beyond comfortable preoperative range should be avoided 1, 3

Diagnostic Approach

Clinical Localization

• Anterior thigh pain with knee extension weakness suggests femoral nerve involvement 2
• Lateral thigh burning/numbness without weakness indicates LFCN compression (meralgia paresthetica) 3, 5
• Medial thigh pain with adduction weakness points to obturator nerve pathology 2
• Posterior leg pain radiating below the knee indicates sciatic nerve compromise 6

Confirmatory Testing

• Electrodiagnostic studies confirm the clinical diagnosis of plexopathy and localize the specific nerve involvement 1
• MRI of the lumbosacral plexus requires specialized sequences including orthogonal views through oblique planes with T1-weighted, T2-weighted, and fat-saturated sequences 1
• MR neurography with high-resolution T2-weighted sequences optimally visualizes peripheral nerve pathology 1

Prevention Strategies

Position Modifications

• Maintain hip flexion within comfortable limits, generally not exceeding 90 degrees, to reduce multiple nerve compression risks 1, 3
• Avoid hip extension beyond the range comfortable during preoperative assessment 1
• Implement periodic position changes during prolonged sitting to prevent constant nerve pressure 3

Protective Padding

• Use specific padding to prevent peroneal nerve contact with hard surfaces at the fibular head, with 94% of consultants and 91% of ASA members agreeing this decreases peroneal neuropathy risk 1
• Apply appropriate padding when sitting on hard surfaces to reduce direct pressure on the anterior superior iliac spine region for LFCN protection 3
• Caution: Inappropriate padding (too tight) may paradoxically increase peripheral neuropathy risk 1

Common Pitfalls

• Anatomical variation: The LFCN was not found at surgery in 8.8% of cases due to anatomical variations including early bifurcation, epifascial position, or exit through an iliac bone canal 7
• Coexisting pathology: Nerve entrapment can coexist with other musculoskeletal hip conditions, making diagnosis challenging 8
• Delayed diagnosis: Femoral neurostenalgia may be missed for years despite multiple orthopedic interventions if not specifically considered 4
• Incomplete examination: In 36% of cases, the LFCN lacks a posterior branch, so absence of posterior lateral thigh symptoms does not exclude the diagnosis 5