Dry Endoscopic-Assisted Mini-Open Approach With Neuromonitoring for Chronic Hamstring Avulsions and Ischial Tunnel Syndrome  Juan Gómez-Hoyos, M.D., Manoj Reddy, B.S., Hal D. Martin, D.O.  Arthroscopy Techniques  Volume 4, Issue 3, Pages e193-e199 (June 2015) DOI: 10.1016/j.eats.2015.01.007 Copyright © 2015 Arthroscopy Association of North America Terms and Conditions

Fig 1 Dissection of the subgluteal space in a left hip in a cadaver in the prone position through a posterior approach. The gluteus maximus was removed to see the subgluteal space. One should observe the intimate relation between the hamstring origin attachment and the sciatic nerve. (1, conjoined tendon origin [semitendinosus and biceps femoris]; 2, semimembranosus origin [lateral to conjoined tendon; yellow arrow]; 3, sciatic nerve; 4, sacrotuberous ligament; 5, sacrospinous ligament; 6, inferior gluteal artery; 7, piriformis muscle; 8, superior gemellus muscle; 9, obturator internus muscle; 10, inferior gemellus muscle; 11, quadratus femoris muscle [inferior half was removed to see lesser trochanter]; 12, lesser trochanter; 13, vastus lateralis muscle; 14, greater trochanter; 15, gluteus medius muscle.) Arthroscopy Techniques 2015 4, e193-e199DOI: (10.1016/j.eats.2015.01.007) Copyright © 2015 Arthroscopy Association of North America Terms and Conditions

Fig 2 (A) Re-creation of patient symptoms of sciatic irritation by contraction of hamstring against resistance with patient in seated position at 30° of knee flexion and (B) alleviation at 90° of knee flexion. The white lines show the knee flexion angle when performing the test, and the red arrows indicate the vector of force of the patient's leg. Arthroscopy Techniques 2015 4, e193-e199DOI: (10.1016/j.eats.2015.01.007) Copyright © 2015 Arthroscopy Association of North America Terms and Conditions

Fig 3 Axial magnetic resonance image of hip (T2 sequence). One should observe the left ischial tuberosity with increased hamstring tendon size and unattached appearance of the semimembranosus origin next to the sciatic nerve (red arrow) and compare it with the contralateral side (green arrow). (F, femur; GM, gluteus maximus; SN, sciatic nerve.) Arthroscopy Techniques 2015 4, e193-e199DOI: (10.1016/j.eats.2015.01.007) Copyright © 2015 Arthroscopy Association of North America Terms and Conditions

Fig 4 Patient in prone position with left hip and leg draped free. The superolateral mark (X) was made before surgery for corroborating the symptomatic side. The inferomedial mark (dot) was drawn over the most painful spot as described by the patient (at the tip of the ischial tuberosity). Arthroscopy Techniques 2015 4, e193-e199DOI: (10.1016/j.eats.2015.01.007) Copyright © 2015 Arthroscopy Association of North America Terms and Conditions

Fig 5 Neuromonitoring setup. The patient is placed in the prone position. Transcranial motor evoked potentials and spontaneous electromyographic activity are recorded from the gluteus medius, biceps femoris, vastus lateralis, tibialis anterior, and gastrocnemius muscles innervated by the superior gluteal nerve, tibial nerve, femoral nerve, deep peroneal branches of the sciatic nerve, and tibial branches of the sciatic nerve, respectively. Somatosensory evoked potentials to stimulate the superficial and deep peroneal nerves and the posterior tibial nerve are performed. The same muscles monitored for electromyographic activity are used to monitor motor potentials. (A) Stimulation of both the left and right sides is performed. (B) Intraoperative neuromonitoring data. Arthroscopy Techniques 2015 4, e193-e199DOI: (10.1016/j.eats.2015.01.007) Copyright © 2015 Arthroscopy Association of North America Terms and Conditions

Fig 6 Fluoroscopic-guided open approach over the lateral aspect of the ischial tuberosity and the ischiofemoral space on the left side with the patient in the prone position. A radiopaque tool is used to orient the mark on the skin. The incision's orientation (dashed line) travels superolaterally to inferomedially to allow an adequate angle of attack for anchor placement. (IT, ischial tuberosity; LT, lesser trochanter.) Arthroscopy Techniques 2015 4, e193-e199DOI: (10.1016/j.eats.2015.01.007) Copyright © 2015 Arthroscopy Association of North America Terms and Conditions

Fig 7 Direction of muscle fibers versus incision on the left side with the patient in the prone position through a posterior approach. The green dashed line indicates the muscle fibers of the gluteus maximus after subcutaneous dissection. The direction of these fibers differs from the direction of the incision (yellow dashed line). This is an important factor to consider when performing dissection of the muscular fibers to access the subgluteal space. Arthroscopy Techniques 2015 4, e193-e199DOI: (10.1016/j.eats.2015.01.007) Copyright © 2015 Arthroscopy Association of North America Terms and Conditions

Fig 8 Sequence of the mini-open approach for repairing a semimembranosus avulsion under dry endoscopic assistance on the left side with the patient in the prone position through a posterior approach: (A) hamstring origin evaluation, (B) longitudinal cut of the hamstring origin in the middle of the damaged zone, (C) decortication using a burr, (D) footprint drilling under fluoroscopic control, (E) anchor placement at the footprint, and (F) reattachment of the tendon using sutures and final aspect after repair and stability verification. (GM, gluteus maximus; HT, hamstring tendons; IT, ischial tuberosity; LT, lesser trochanter.) Arthroscopy Techniques 2015 4, e193-e199DOI: (10.1016/j.eats.2015.01.007) Copyright © 2015 Arthroscopy Association of North America Terms and Conditions