The Variable Emergence of the Infrapatellar Branch of the Saphenous Nerve

Abstract

The infrapatellar branch of the saphenous nerve (IPBSN) is a cutaneous nerve of the lower limb, which arises distal to the adductor canal. High variability in the emergence, course, branching, termination, and morphometrics of the IPBSN poses an increased risk of injury to the nerve during surgical interventions on the anteromedial aspect of the knee. The aim of this study was to describe the anatomical characteristics of the IPBSN. This study utilized cadaveric ( = 100) and ultrasonography ( = 30) assessments, and meta-analysis. In the cadaveric study, the presence of IPBSN and its emergence mode in relation to the sartorius muscle (SaM) was determined (type A-anterior; type B-posterior; type C-penetrating the SaM). Ultrasonography examinations were conducted on healthy volunteers to determine the presence and mode of the emergence of the nerve. Finally, from electronic databases searching, all studies reporting the IPBSN emergence data were pooled into a meta-analysis. The mean distance between the medial border of the patellar ligament (MBPL) and the IPBSN at the level of the patellar apex (PA) was also analyzed in the cadaveric, ultrasonography, and meta-analysis portions of the study. Six studies ( = 336 limbs), including the present cadaveric study, were pooled into the meta-analysis of emergence. The most prevalent IPBSN emergence mode was type C (42.9%) followed by type B (41.9%) and type A (15.4%). In the ultrasonography assessment, type A was found to be the most common (82.8%). The mean distance between the MBPL and the IPBSN at the level of the PA was 4.89 ± 0.22 cm, and 5.57 ± 0.91 cm, for the cadaveric and meta-analysis studies combined, and the ultrasonography assessment, respectively. This multimodality study shows that the most common type of IPBSN emergence is type C. The horizontal distance between the MBPL and the IPBSN at the level of the PA is usually between 4.5 and 5.6 cm. Understanding the anatomy of IPBSN emergence is crucial for orthopedic surgeons to minimize the risks of iatrogenic nerve injury during surgical procedures in the region.

Risk of iatrogenic injury to the infrapatellar branch of the saphenous nerve during hamstring tendon harvesting: A meta‐analysis

“…Regardless of the type and length of the incision, the location of the incision also plays an important role in preventing IPBSN iatrogenic injury. In our recent meta‐analysis we found that the horizontal distance between the medial border of the patellar ligament and the IPBSN at the level of the patellar apex, is usually between 45 and 56 mm. Thus, an incision should be performed maximally 45 mm from the medial border of the patellar ligament to minimize the risk of iatrogenic injury to the IPBSN …”

“…Thus, an incision should be performed maximally 45 mm from the medial border of the patellar ligament to minimize the risk of iatrogenic injury to the IPBSN. 31 This meta-analysis was primarily limited by the variability of the methods used in the included studies. First, most of the studies did not report whether the incision was made based on a reported safe area or angle for autogenous tendon harvesting, such as the one described by Boon et al, 32 or if it was modified according to the size and body mass index of the patients.…”

Injury to the infrapatellar branch of the saphenous nerve during tendon graft harvesting for knee ligament reconstruction: An ultrasound simulation study

“…We suggest that this is probably because USG cannot visualize the tiny terminal branches of the IPBSN, injury to which could also lead to postoperative sensory complications. Therefore, we encourage surgeons to remember the safe zones for incision, reported as 3.0 to 4.5 cm from the medial border of the patellar ligament at the level of the apex of the patella (Henry et al, ).…”

“…Additionally, the type of emergence of the IPBSN was assessed and classified as: (A) anterior to the on the antero-medial aspect of the knee. SC, subcutaneous tissue; TB, proximal tibia sartorius muscle, (B) posterior to the sartorius muscle, or (C) within (penetrating) the sartorius muscle (Henry et al, 2016). All assessments were performed twice.…”

“…The infrapatellar branch of the saphenous nerve (IPBSN) usually originates at the level of the knee joint and provides sensory innervation to the skin over the knee, the patellar ligament, and the skin medial to the knee (Papastergiou et al, ). Its anatomy can vary not only from person to person, but also from knee to knee in the same individual (Henry et al, ). Furthermore, it rarely exists as a solitary nerve, but rather as a plexus (Kalthur et al, ).…”