Treatment of proximal hamstring tendinopathy-related sciatic nerve entrapment: presentation of an ultrasound-guided "Intratissue Percutaneous Electrolysis" application

Abstract

Background: Proximal Hamstring Tendinopathy-related Sciatic Nerve Entrapment (PHTrSNE) is a neuropathy caused by fibrosis interposed between the semimembranosus tendon and the sciatic nerve, at the level of the ischial tuberosity.

Methods: Ultrasound-guided Intratissue Percutaneous Electrolysis (US-guided EPI) involves galvanic current transfer within the treatment target tissue (fibrosis) via a needle 0.30 to 0.33 mm in diameter. The galvanic current in a saline solution instantly develops the chemical process of electrolysis, which in turn induces electrochemical ablation of fibrosis. In this article, the interventional procedure is presented in detail, and both the strengths and limits of the technique are discussed.

Results: US-guided EPI eliminates the fibrotic accumulation that causes PHTrSNE, without the semimembranosus tendon or the sciatic nerve being directly involved during the procedure. The technique is however of limited use in cases of compression neuropathy.

Conclusion: US-guided EPI is a technique that is quick to perform, minimally invasive and does not force the patient to suspend their activities (work or sports) to make the treatment effective. This, coupled to the fact that the technique is generally well-tolerated by patients, supports use of US-guided EPI in the treatment of PHTrSNE.

Keywords: ablation techniques; entrapment neuropathies; tendon injuries; ultrasonography.

Figures

Figure 1

Transversal ultrasound section of the proximal semimembranosus tendon (asterisked) on the ischial tuberosity (IT). The sciatic nerve (indicated by the arrow) is easily recognizable lateral to the tendon. GM=gluteus maximus. Q=quadratus femoris.

Figure 2

Proximal hamstring tendinopathy-related sciatic nerve entrapment. Between the sciatic nerve (indicated by arrow) and the tendon of the semimembranosus (SM) a fibrotic accumulation is interposed (hyper-echoic area visible within the dashed box) which makes it difficult to distinguish the anatomical limits of the structures. IT=ischial tuberosity.

Figure 3

Ultrasound-guided insertion of the needle. Being the needle inserted perpendicular to the skin, it is displayed through movement of surrounding tissues.

Figure 4

Schematic diagram of the Ultrasound-guided Intratissue Percutaneous Electrolysis intervention. The medial edge of the sciatic nerve and associated vessels is represented by the vertical dashed line A. The lateral limit of the semimembranosus tendon is represented by the vertical dashed line B. The needle is inserted into the area bounded by line 1 (perpendicular to the axis joining lines A and B) and by line 2 (tangent to the superior-lateral point of the semimembranosus tendon). In this way, the technique can be performed safely, without structures other than the fibrosis being involved in the intervention.