Background & Aims

The genicular nerves innervating the inferolateral knee joint, are not routinely targeted due to the fear of common peroneal nerve (CPN) injury, and foot drop. (1)There are a few descriptions of these genicular nerve courses and targets. The Inferolateral genicular nerve (ILGN) block can be done at the intersection of a vertical line through Gerdy’s tubercle(GT) and a horizontal line through the tibial tuberosity. (2) Recurrent genicular nerve (RGN) at vertically 1 cm below the inferior edge of Gerdy’s tubercle. (3) Under ultrasound guidance ILGN can be targeted at the insertion of the lateral coronary ligament on the tibia, near the lateral inferior genicular artery. (4)
In this study, we have evaluated the accuracy and safety of these techniques in soft human cadavers, by measuring the nerve-to-needle distance and staining of the nerve after targeting.
To rule out the risk of foot drop, the shortest distance from the target needle to the CPN, and motor branches, was also recorded.

Methods

30 cadaveric knee specimens were studied. Using the envelope method, they were divided into two equal groups. Techniques described in terms of ILGN were studied. In group one, ultrasound scanning was performed using the 5–13 MHz linear probe of the Venue Go R3 machine, and needle was advanced up to the insertion of the lateral coronary ligament on the tibia. In the second group, at the intersection of the vertical line through GT and the horizontal line through the tibial tuberosity, the needle was inserted perpendicular to the skin, to touch the bone. Eosin, 2% W/V, 0.1 ml was injected. Needle was pierced into the periosteum and bone for anchorage. A cruciform incision with no: 11 surgical blade centering the needle was made. The subcutaneous tissue and fat were removed with microdissection scissors, under a loupe microscope. Nerve-to-needle distance was measured using vernier calipers. After dissection, distance from the targeted needle to the common peroneal nerve was documented.

Results

In group 1, the technique targeted the terminal branches of a nerve which was having the course of RGN, (3) in 96.67% of specimens (14/15), with an average nerve-to-needle distance of 2.65mm, with a 1.82 to 3.01 interquartile range (IQR). In group 2, the more proximal trunk of RGN was targeted in 100 % (15/15) specimens, with an average nerve-to-needle distance of 5.03mm, with IQR of 4.62 to 6.14. In 6 out of 30 specimens, a genicular nerve was found to be traversing beneath the lateral collateral ligament and piercing the superior inferolateral capsule, as described by Tran et al., and Kim et al, which they described as the ILGN. (5,6)
The RGN is traversing 6.1 mm perpendicularly down GT when it is joined by the recurrent anterior tibial vessels. Fonkoue et al.,(7) and Kose et al,(8) described this distance as 20mm. By linear regression, it was significantly associated with cadaver length.
The nearest motor branch of CPN was 35 mm, and CPN was 50.8 mm away.

Conclusions

1.The techniques mentioned above were not targeting ILGN, but instead were targeting the recurrent fibular nerve.
2.The RGN emerged from the deep peroneal nerve, as its first branch and went deep to the anterior compartment muscles. It was joined by the anterior tibial recurrent genicular vessels and then ascended between GT and tibial tuberosities. The course was also consistent with the recent studies, describing the RGN course. (3,7,8)
3. If performed under c-arm guidance, targeting at the intersection of the vertical line through GT and the horizontal line through the tibial tuberosity is accurate.
4. Under ultrasound guidance, targeting the insertion of coronary ligament, on the tibia, will block/ ablate only some of the terminal branches, hence pain relief may be partial. Hence one can target down the vertical line from GT, near the anterior tibial recurrent genicular vessel pulsations.
5. In both of these targeting techniques, the risk of foot drop is nearly nil.

References

1.Farrell ME, Staub B, Varzari A. Knee Diagnostic Genicular Nerve Block with Fluoroscopy. InThe Pain Procedure Handbook: A Milestones Approach 2023 Dec 31 (pp. 179-189). Cham: Springer International Publishing.
2.Fonkoué L, Behets C, Kouassi JÉK, Coyette M, Detrembleur C, Thienpont E, et al. Distribution of sensory nerves supplying the knee joint capsule and implications for genicular blockade and radiofrequency ablation: an anatomical study. Surg Radiol Anat. 2019 Dec;41(12):1461–71.
3.Fonkoue L, Behets CW, Steyaert A, Kouassi JEK, Detrembleur C, De Waroux BLP, et al. Accuracy of fluoroscopic-guided genicular nerve blockade: a need for revisiting anatomical landmarks. Reg Anesth Pain Med. 2019 Aug 26;rapm-2019-100451.
4.Ahmed A, Arora D. Ultrasound-Guided Neurolysis of Six Genicular Nerves for Intractable Pain from Knee Osteoarthritis: A Case Series. Pain Pract. 2019 Jan;19(1):16–26.
5.Tran J, Peng PWH, Lam K, Baig E, Agur AMR, Gofeld M. Anatomical Study of the Innervation of Anterior Knee Joint Capsule: Implication for Image-Guided Intervention. Reg Anesth Pain Med. 2018 May 1;43(4):407–14.
6.Kim JH, Shustorovich A, Arel AT, Downie SA, Cohen SP, Kim SY. Genicular Nerve Anatomy and Its Implication for New Procedural Approaches for Knee Joint Denervation: A Cadaveric Study. Pain Med. 2022 Jan 3;23(1):144–51.
7.Fonkoue L, Stoenoiu MS, Behets CW, Steyaert A, Kouassi JEK, Detrembleur C, et al. Validation of a new protocol for ultrasound-guided genicular nerve radiofrequency ablation with accurate anatomical targets: cadaveric study. Reg Anesth Pain Med. 2021 Mar;46(3):210–6.
8.Kose SG, Kose HC, Celikel F, Akkaya OT. Predictive factors associated with successful response to utrasound guided genicular radiofrequency ablation. Korean J Pain. 2022 Oct 1;35(4):447–57.

Presenting Author

Chinchi K

Poster Authors

CHINCHU K

MD

AIIMS NAGPUR

Lead Author

NITESH GONNADE

MD

ALL INDIA INSTITUTE OF MEDICAL SCIENCES, JODHPUR, INDIA

Lead Author

RAVI GAUR

MD,DNB

ALL INDIA INSTITUTE OF MEDICAL SCIENCES, JODHPUR, INDIA

Lead Author

Topics

  • Treatment/Management: Interventional Therapies – Injections/Blocks