A modified oblique incision in hamstring tendon graft harvesting during ACL reconstruction

Abstract

Background: During anterior cruciate ligament (ACL) reconstruction, different methods of harvesting hamstring tendon may lead to different degrees of injury to the inferior patellar branch of the saphenous nerve (IPBSN). Most of recent studies in the literature suggest that the classic oblique incision (COI) can reduce the incidence of IPBSN injury. We proposed a modified oblique incision (MOI) and compared it with the COI in terms of the resulting levels of injury and sensory loss and the clinical outcome.

Methods: Patients with ACL injury admitted to our hospital from April 2015 to July 2019 were randomly selected and included in our study. Thirty patients underwent the COI to harvest hamstring tendons, and the other 32 patients underwent the MOI. The pin prick test was performed to detect the sensation loss at 2 weeks, 6 months, and 1 year after the operation. Digital photos of the region of hypoesthesia area were taken, and then, a computer software (Adobe Photoshop CS6, 13.0.1) was used to calculate the area of the hypoesthesia. The length of the incision and knee joint functional score were also recorded.

Results: At the final follow-up, the incidence of IPBSN injury in COI and MOI were 33.3% and 9.4%, and the areas of paresthesia were 26.4±2.4 cm² and 9.8±3.4 cm² respectively. There was no significant difference in the incision length or knee functional score between the two groups.

Conclusion: The MOI can significantly reduce the risk of injury to the IPBSN, reduce the area of hypoesthesia, and lead to high subjective satisfaction. Therefore, compared with the COI, the MOI is a better method of harvesting hamstring tendons in ACL reconstruction.

Keywords: Anterior cruciate ligament; Hamstring tendon; Inferior patellar branch of saphenous nerve.

Fig. 1

COI—the incision is centered at and located three fingerbreadths below the joint line, 1-cm medial to the tibial tubercle, and 1- to 3-cm distal to the tubercle

Fig. 2

Triangle zone—the medial and inferior low risk zone of the IPBSN is a triangle that a vertical line is projected downward from the medial edge of the tibial plateau and a horizontal line from the tibial tuberosity to the medial side of the knee. The zone is located distally from 50% of the vertical line and medially from 66% of the horizontal line. MOI—the incision midpoint was median point of the bottom edge of the triangle, through this midpoint and the oblique angle with the bottom edge was 51° and extended posteriorly and anteriorly

Fig. 3

The paresthesia area of a patient at 1-year follow-up was measured by a computer software (Adobe Photoshop CS6, 13.0.1)