**1. Introduction**

A chronic proximal hamstring tear is a debilitating muscle injury associated with persistent pain, cramping, functional limitation, and weakness in the ischial (buttock) region, with more than 4–6 weeks of evolution [1]. The delayed diagnosis and the failed conservative treatments often result in a hamstring syndrome caused by the entrapment of the sciatic nerve within the scar formed around the torn hamstring tendon, causing an unrelenting pain that is exacerbated by prolonged sitting [2,3]. Moreover, the distal retraction of the hamstring tendon stumps of several centimeters makes the reinsertion of the entire conjoined tendon (JT) (made up of the long head of biceps femoris (LBF) and semitendinosus tendons (STT)) and the tendon of semimembranous muscle (SMT) extremely difficult [1,2].

In this manuscript, we describe a novel technique using a semitendinosus tendon allograft sutured in a "V inversion" manner, thereby avoiding an excess of tension and length of the new reconstructed hamstring tendons, which could lead to rupture at the suture areas. Moreover, and in order to enhance the repair process and avoid new sciatic entrapment, we assist the surgery with liquid plasma rich in growth factors (PRGF-Endoret) injected intraosseously, intratendinously, and within the suture areas, as well as wrapping the sciatic nerve with a PRGF membrane [4,5].

**Citation:** Ríos Luna, A.;

Fahandezh-Saddi Díaz, H.; Villanueva Martínez, M.; Bueno Horcajadas, Á.; Prado, R.; Anitua, E.; Padilla, S. Reconstruction of Chronic Proximal Hamstring Tear: A Novel Surgical Technique with Semitendinosus Tendon Allograft Assisted with Autologous Plasma Rich in Growth Factors (PRGF). *J. Clin. Med.* **2022**, *11*, 5443. https:// doi.org/10.3390/jcm11185443

Academic Editors: Steffen Rosslenbroich and Chang-Wug Oh

Received: 1 September 2022 Accepted: 14 September 2022 Published: 16 September 2022

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