Management of chronic knee pain caused by postsurgical or posttraumatic neuroma of the infrapatellar branch of the saphenous nerve

Infrapatellar Branch of the Saphenous Nerve: Therapeutic Approaches to Chronic Knee Pain

PURPOSE OF REVIEW

The infrapatellar branch of the saphenous nerve (IPS) is an under-investigated nerve that can be a source of chronic knee pain. This literature review aims to deliver an up-to-date review of chronic pain transmitted via the IPS along with therapeutic approaches available for pain refractory to conservative measures.

RECENT FINDINGS

Knee pain transmitted via the IPS can arise from several etiologies. Damage to the IPS is often iatrogenic and develops following total knee arthroplasty, anterior cruciate ligament reconstruction, and other knee surgical procedures. Other causes of IPS-derived pain include entrapment of the nerve, neuromas, Schwannomas, and pain from knee osteoarthritis transmitted through the IPS.This article investigated therapeutic approaches to pain derived from the IPS. Common approaches included radiofrequency ablation, neuroma excisions, Schwannoma excision, nerve blocks, surgical exploration, surgical release of an entrapped nerve, cryoablation, and peripheral nerve stimulation. Pain scores, duration of pain relief, adverse events, and secondary outcomes were all included in this review. A subset of the patient population experiences chronic pain deriving from the IPS that is refractory to conservative treatment measures. This review aims to evaluate the etiologies and therapeutic approaches for chronic pain arising from the IPS refractory to conservative treatments.

Percutaneous Electrical Nerve Stimulation (PENS) for Infrapatellar Saphenous Neuralgia Management in a Patient with Myasthenia gravis (MG)

Myasthenia gravis is a neuromuscular transmission disorder characterized by weakness of the cranial and skeletal muscles, however, neuropathies are extremely rare. In this case report we present a case of a 61-year-old man diagnosed Myasthenia gravis who came to our attention due to a 1 week of acute deep pain [NPRS 8/10] in the anterior and medial right knee which occurred during walking [NPRS 8/10] or stair climbing [NPRS 9/10]. A complete medical record and clinical examination based on physical exploration and ultrasound assessment confirmed a infrapatellar saphenous neuralgia. Therapeutic interventions included Percutaneous nerve electrical stimulation combined with pain neuroscience education, neural mobilization of the saphenous nerve and quadriceps resistance exercises. After 4 weeks, pain intensity [NRPS = 1/10], knee functionality [OKS = 41/48] and lower limb functionality [LLFI = 80%] were notably improved, nevertheless, fatigue [RPE = 2/10] was similar than baseline. At 2 months of follow-up, the effect on intensity of pain NRPS [0/10] and functionality OKS [40/48] and LLFI [82%] was maintained, however, no significant clinical changes were detected on perceived fatigue RPE Scale [2/10]. Despite the important methodological limitations of this study, our case report highlights the efficacy of percutaneous electrical nerve stimulation combined with physical agents modalities for pain and functionality of infrapatellar saphenous neuralgia in the context of Myasthenia gravis.

A cohort study on neuropathic pain of the saphenous nerve—factors influencing surgical outcome

Background

Due to its partially superficial course, the saphenous nerve is vulnerable to injury by trauma or surgery potentially leading to painful neuroma formation. Different surgical techniques to treat neuroma have been described, but so far, no one has proven to be superior to the others. The aim of this study was therefore to identify factors influencing the outcome of revision surgery in saphenous nerve neuropathic pain in our department.

Methods

From 2010 to 2020, a total of 29 consecutive patients with neuropathic pain and suspected neuroma of the saphenous nerve underwent revision surgery. A medical chart review was performed to collect patient-, pain-, and treatment-specific factors. Outcomes were registered.

Results

Post revision surgery in neuropathic pain of the saphenous nerve, 16 (55.2%) patients suffered from persisting pain. In multivariable logistic regression models evaluating the risk of persisting pain post saphenous nerve revision surgery, both smoking and preoperative opiate consumption represented independent predictors of higher risk for persisting pain.

Conclusions

Patients with injury to the saphenous nerve should be coached toward smoking cessation. Whenever possible, forgoing opiate treatment might be beneficial.

Level of evidence: Level IV, Risk/Prognostic.