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. 2022 Mar 24;10(3):23259671221085272.
doi: 10.1177/23259671221085272. eCollection 2022 Mar.

Effects of Leg Length, Sex, Laterality, and the Intermediate Femoral Cutaneous Nerve on Infrapatellar Innervation

Kenneth S Johnson  1 , Joanna Rowe  1 , Kanwalgeet Hans  1 , Victoria Gordon  1 , Adam L Lewis  1 , Clayton Marolt  1 , Gilbert M Willett  2 , Charles Orth  3 , Sarah Keim-Janssen  4 , Anthony Olinger  5
Affiliations

Effects of Leg Length, Sex, Laterality, and the Intermediate Femoral Cutaneous Nerve on Infrapatellar Innervation

Kenneth S Johnson et al. Orthop J Sports Med. .

Abstract

Background: An iatrogenic injury to the infrapatellar branch of the saphenous nerve (IPBSN) is a common precipitant of postoperative knee pain and hypoesthesia.

Purpose: To locate potential safe zones for incision by observing the patterns and pathway of the IPBSN while examining the relationship of its location to sex, laterality, and leg length.

Study design: Descriptive laboratory study.

Methods: A total of 107 extended knees from 55 formalin-embalmed cadaveric specimens were dissected. The nerve was measured from palpable landmarks: the patella at the medial (point A) and lateral (point B) borders of the patellar ligament, the medial border of the patellar ligament at the patellar apex (point C) and tibial plateau (point D), the medial epicondyle (point E), and the anterior border of the medial collateral ligament at the tibial plateau (point F). The safe zone was defined as 2 SDs from the mean.

Results: Findings indicated significant correlations between leg length and height (r P = 0.832; P < .001) as well as between leg length and vertical measurements (≥45°) from points A and B to the IPBSN (r P range, 0.193-0.285; P range, .004-.049). Male specimens had a more inferior maximum distance from point A to the intersection of the IPBSN and the medial border of the patellar ligament compared with female specimens (6.17 vs 5.28 cm, respectively; P = .049). Right knees had a more posterior IPBSN from point F compared with left knees (-0.98 vs-0.02 cm, respectively; P = .048). The majority of knees (62.6%; n = 67) had a nerve emerging that penetrated the sartorius muscle. Additionally, 32.7% (n = 35) had redundant innervation, and 25.2% (n = 27) had contribution from the intermediate femoral cutaneous nerve (IFCN).

Conclusion: We identified no safe zone. Significant innervation redundancy with a substantial contribution to the infrapatellar area from the IFCN was noted and contributed to the expansion of the danger zone.

Clinical relevance: The location of incision and placement of arthroscopic ports might not be as crucial in postoperative pain management as an appreciation of the variance in infrapatellar innervation. The IFCN is a common contributor. Its damage could explain pain refractory to SN blocks and therefore influence anesthetic and analgesic decisions.

Keywords: anatomy; anesthesia/pain management; general sports trauma; injury prevention; knee; lower extremity; peripheral nerve injuries.

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Conflict of interest statement

The authors have declared that there are no conflicts of interest in the authorship and publication of this contribution. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

Figures

Figure 1.
Figure 1.
Landmarks (red) and distances (green) utilized to identify the position of the infrapatellar branch of the saphenous nerve (IPBSN) in (A) anterior and (B) anteromedial views. Point A: patella at the medial border of the patellar ligament. Point B: patella at the lateral border of the patellar ligament. Point C: medial border of the patellar ligament at the patellar apex. Point D: medial border of the patellar ligament at the tibial plateau. Point E: medial epicondyle. Point F: anterior border of the medial collateral ligament at the tibial plateau. Distances A1 to A5 were from point A to the IPBSN at 0°, 30°, 45°, 60°, and the intersection of the IPBSN and the patellar ligament, respectively; distance B1 was from point B to the intersection of the IPBSN and the lateral border of the patellar ligament; and distances C1-F1 were the horizontal distances from points C-F to the IPBSN.
Figure 2.
Figure 2.
In specimens with multiple branches of the infrapatellar branch of the saphenous nerve (IPBSN), the minimum (most superior) and maximum (most inferior) distances were documented from all points of reference. Shown are the minimum and maximum distances for distance A3 (green).
Figure 3.
Figure 3.
Emergence and frequency of the infrapatellar branch of the saphenous nerve (IPBSN) relative to the sartorius muscle (SM). F, femur; G, gracilis; P, patella; PA, pes anserinus; PL, patellar ligament; RF, rectus femoris; ST, semitendinosus; T, tibia; V, vastus medialis.
Figure 4.
Figure 4.
Minimum and maximum mean location (dark gray), ±1 SD (medium gray), and ±2 SDs (light gray) indicating the danger zone of the infrapatellar branch of the saphenous nerve (IPBSN) in relation to points A and B.
See this image and copyright information in PMC

References

    1. Ackmann T, Von Düring M, Teske W, Ackermann O, Muller P, Von Schulze Pellengahr C. Anatomy of the infrapatellar branch in relation to skin incisions and as the basis to treat neuropathic pain by percutaneous cryodenervation. Pain Physician. 2014;17(3):E339–E348. - PubMed
    1. Arthornthurasook A, Gaew-Im K. Study of the infrapatellar nerve. Am J Sports Med. 1988;16(1):57–59. - PubMed
    1. Cohen SB, Flato R, Wascher J, et al. Incidence and characterization of hypoesthesia in the distribution of the infrapatellar branch of the saphenous nerve after anterior cruciate ligament reconstruction: a prospective study of patient-reported numbness. J Knee Surg. 2018;31(6):585–590. - PubMed
    1. Ebraheim NA, Mekhail AO. The infrapatellar branch of the saphenous nerve: an anatomic study. J Orthop Trauma. 1997;11(3):195–199. - PubMed
    1. Fleiss JL. The Design and Analysis of Clinical Experiments. John Wiley & Sons; 1986.

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