Portal Placement and Biomechanical Performance of Endoscopic Proximal Hamstring Repair

Abstract

Background: Proximal hamstring tendon avulsions are debilitating and commonly cause pain, weakness, and functional limitations. Open surgical repair has been the standard, but improved endoscopic techniques have enabled proximal hamstring fixation with decreased risk of infection and numbness, without the morbidity of a large incision. Purpose/Hypothesis: The purpose was to (1) describe pertinent anatomy surrounding the proximal hamstring origin in relation to 4 endoscopic portal sites and (2) test for biomechanical differences between open and endoscopic repair. It was hypothesized that (1) endoscopic proximal hamstring repair is efficacious with respect to commonly used portals and (2) there is no biomechanical difference between open and endoscopic techniques. Study Design: Descriptive and controlled laboratory study. Methods: Proximal hamstring ruptures were simulated endoscopically in 10 fresh-frozen human cadaveric pelvis specimens. Endoscopic repair was then completed on 1 limb from each specimen through 4 portals. After repair, each specimen was dissected in layers and measurements from portal tracts to pertinent anatomy were obtained. Open repair was performed on all contralateral limbs, followed by cyclical biomechanical tensile testing to failure of both the open and endoscopically repaired hamstring tendons to assess failure load and local tissue strain. Results: On average, no portal tract was closer than 2.0 cm to the sciatic nerve or inferior gluteal neurovascular bundle. Anatomic landmarks were identified that could improve the reproducibility and safety of the procedure. Biomechanical testing revealed no differences between the open and endoscopic repair techniques for any measured parameter. Conclusion: This study supports the safety and efficacy of endoscopic proximal hamstring repair through anatomic and biomechanical analyses and helps establish reproducible and recognizable landmarks that define a safe working zone. Clinical Relevance: This study maps the anatomic landscape of the proximal hamstring as encountered endoscopically and demonstrates equivalent biomechanical strength of endoscopic proximal hamstring repair, supporting this technique’s safety and efficacy.

The safe zones for endoscopic proximal hamstring repair: a cadaveric assessment of standard portal placement and their relationship to major neurovascular structures

“…A recently published study of endoscopic proximal hamstring repair and portal sites concluded that major neurovascular structures were safely out of the way of all portal site trajectories, with a minimum of 2.4 cm (range 1.3-5.4 cm) to the sciatic nerve and 2.55 cm (range 0.7-6.8 cm) to the posterior femoral cutaneous nerve. 18 The apparent discrepancies with our current study are likely to be related to several factors. Portal marking and placement in our study was performed identically to that originally described and illustrated by Dierckman and Guanche 12 with medial and lateral portals created "2 cm medial and lateral to the palpable ischial tuberosity" and an inferior portal created "4 cm distal to the tip of the ischium and equidistant from the medial and lateral portals".…”

“…Moreover, a recent cadaveric study of paired pelvic specimens found no biomechanical difference between open and endoscopically repaired proximal hamstring tendons in terms of ultimate load, strain, or displacement at failure. 18 Our data show that of the 3 standard endoscopic portals, the standard lateral portal is indeed the most dangerous, with direct injury to the sciatic nerve in 37% (11/30). Furthermore, more vertical insertion of a pin through a standard lateral portal placed the sciatic and PFC nerves at greatest risk, with direct injury to the sciatic nerve seen in 60% (6/10) of cases whereas no direct injury to the sciatic or PFC nerves was seen with any orientation of pin through a standard medial or inferior portal.…”

“…Portal marking and placement in our study was performed identically to that originally described and illustrated by Dierckman and Guanche 12 with medial and lateral portals created "2 cm medial and lateral to the palpable ischial tuberosity" and an inferior portal created "4 cm distal to the tip of the ischium and equidistant from the medial and lateral portals". 12 The study by Ryan et al 18 instead used four unique portal sites (inferolateral, medial, superolateral, accessory superior) which are different from those used in our study. Secondly, anatomical measurements in their study were made based on the trajectory of each portal site after creating and repairing open and endoscopic proximal hamstring injuries, which we did not perform in our study.…”

Endoscopic Repair of Proximal Hamstring Insertion With Sciatic Nerve Neurolysis

“…The ischium landmark is outlined on the skin and the central portal is created on the gluteal fold in line with the ischium, as seen on Figure 3 A. Fluoroscopic guidance is used to guide the blunt trocar towards the ischium, to protect the sciatic nerve, which lies approximately 1 to 2 cm lateral to the hamstring origin on the ischium. 14 The lateral portal is created with aid of a spinal needle and direct visualization. A bursectomy with an arthroscopic shaver is made to clear the underlying structures, and a diagnostic endoscopic evaluation is performed, identifying the ischial tuberosity, remaining tendon fibers, and sciatic nerve, as seen in Video 1 .…”

“…On regular basis, a medial portal and an accessory portal are created with the same technique as the lateral one with direct visualization, as seen in Figure 3 B. It’s important to keep in mind that the posterior femoral cutaneous nerve divides just above the ischial tuberosity, and the inferior gluteal nerve and artery travel 5 cm proximal to the ischium. 14 The number of anchors is determined according to the tear pattern; fewer than 2 anchors are not recommended. For this case, two 5.5-mm triple-loaded HEALICOIL anchors (Smith & Nephew) were introduced, using its awl and tap.…”