What is a Tibial Neuroma After Below-Knee Amputation?
A tibial neuroma after below-knee amputation (BKA) is a painful nerve growth that forms at the cut end of the tibial nerve in the residual limb, representing one of the most common sources of localized stump pain and nerve-specific phantom limb pain in transtibial amputees.
Pathophysiology and Clinical Significance
When the tibial nerve is transected during a BKA, the proximal nerve end attempts to regenerate but becomes disorganized, forming a neuroma—a tangled mass of nerve fibers, scar tissue, and supporting cells. This creates a site of ectopic nerve impulse generation that can produce both localized pain at the neuroma site and contribute to phantom limb pain 1.
Key Clinical Features
- Localized pain with a positive Tinel sign over the neuroma site
- Nerve-specific phantom limb pain corresponding to the tibial nerve distribution (plantar foot sensation)
- Prosthesis intolerance due to pressure or contact with the neuroma
- Strong correlation between symptomatic neuroma presence and phantom limb pain development 2
Epidemiology and Risk Factors
The tibial nerve is the most problematic nerve following transtibial amputation:
- Overall symptomatic neuroma rate after BKA: 14.6% 2
- The tibial nerve and common/superficial peroneal nerves are most frequently symptomatic after BKA 3
- Failure to address the tibial nerve during surgical intervention increases revision surgery risk by 26-fold (OR: 26,95% CI: 1.8-368) 3
- Protective factors: diabetes and obesity appear to reduce symptomatic neuroma formation 2
Diagnostic Approach
Physical examination findings:
- Pinpoint tenderness over the nerve course in the residual limb
- Positive Tinel sign (shooting pain with percussion over the neuroma)
- Pain reproduction with palpation
- Prosthesis intolerance without other mechanical causes
Imaging considerations:
- MRI can identify neuromas in above-knee amputations but visualization is more difficult in BKA due to compact calf muscle anatomy 4
- Neuromas appear ovoid or rounded, heterogeneous, and isointense with muscle on MRI 4
- X-ray is useful to rule out heterotopic ossification, which can coexist with or mimic neuroma pain 5, 6
Clinical Implications for Management
Prevention is Superior to Treatment
The evidence strongly supports primary nerve management at the time of amputation rather than waiting for symptomatic neuromas to develop:
- Traditional traction neurectomy alone has a 2-fold higher risk of heterotopic ossification and symptomatic neuroma formation compared to active nerve surgery techniques 6
- Targeted muscle reinnervation (TMR) of the tibial nerve at the time of BKA prevents symptomatic neuroma formation in the vast majority of cases 3, 7
Treatment Hierarchy When Neuroma is Present
For established symptomatic tibial neuromas:
Surgical intervention with TMR or RPNI is the definitive treatment
Adjunctive therapies for associated phantom limb pain (which occurs in 12.6% and correlates with neuroma presence 2):
Critical Pitfalls to Avoid
- Do not assume all stump pain is neuroma-related: Rule out heterotopic ossification, infection, osteomyelitis, hematoma, and prosthetic fit issues 4, 5
- Do not perform incomplete nerve surgery: Addressing only some nerves while leaving the tibial nerve untreated leads to high failure rates 3
- Do not delay intervention: Symptomatic neuromas rarely resolve spontaneously and significantly impair quality of life 1, 2
- Do not rely solely on imaging: Clinical diagnosis with Tinel sign is more reliable than MRI in BKA patients 4
Optimal Surgical Approach for BKA
The tibial nerve specifically requires:
- TMR to a motor nerve branch in the posterior compartment, OR
- Transposition away from weight-bearing areas with neuroplasty 7
- This should be performed at the time of primary amputation when possible to prevent neuroma formation entirely 3, 6, 7
The tibial neuroma represents a preventable source of significant morbidity that directly impacts prosthetic use, mobility, and quality of life in BKA patients 1, 2, 3.