Surgical Induction of Lumbar Spine Instability in Mouse Model: A Surgical Procedure for the Resection of the Lumbar Spinous Processes and Connected Ligaments in Murine Model

Overview

In this video, we describe the surgical procedure to induce lumbar spine instability in a mouse model by resecting the Lumbar L3 to L5 spinous process along with supraspinous and interspinous ligaments.

Protocol

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.

1. Pre-operation preparation

1. Instrument sterilization: Steam-sterilize surgical instruments in an autoclave (121 °C for 15 min) prior to the surgery. Pack instruments in a metal container and maintain them until they are used in the surgery.
2. Surgery platform setup: Assign a bench area of at least 60 cm x 60 cm for the operation. Clean the surface of area with 75% alcohol and cover with a disposable medical towel. Place a sterile surgical instruments pack, reagents, surgical items onto a disposable medical towel within the upper 1/3 of area. Leave the remaining 2/3 of area clean for surgical operation. Add a hotpad underneath surgical pad for thermal support.
3. Animal preparation
   1. Place the animal (C57BL/6J mice, male, 8-week old) into the induction chamber. Turn on the vaporizer at an induction level of 4% for isoflurane and 4 L/min for oxygen. After the animal is fully anesthetized, maintain the anesthetic with the nose cone and the anesthetic delivery at a level of 1.5% for isoflurane and 0.4 L/min for oxygen during surgery. Monitor the animal for respiration.
   2. Apply chlortetracycline hydrochloride eye ointment to prevent corneal dryness during the surgery.
   3. Shave the surgical area on the dorsal surface from the lower thoracic region to the top of the sacral region using a small animal trimmer. Remove the shaved fur with tissue wipes.
   4. Apply depilatory cream onto the shaved area and leave it there no longer than 3 min. Remove the cream with gauze and flush with 2 mL of 0.9% sterile saline.
   5. Place a custom-made surgical cylindrical pad (Figure 1A) under the abdomen of the mouse to raise up the lumbar spine and facilitate the surgical operation.

2. Exposure of the lumbar third to lumbar fifth (L₃–L₅) spinous processes

1. Use the index finger to touch the subcutaneous spinous processes of the lumbar vertebrae, which are more outward, and compare with thoracic vertebrae and sacral vertebrae to identify the lumbar region.
2. Rinse the skin using 75% alcohol. Perform a 3–4 cm midline skin incision over the lumber region from the mid-thoracic region to the hip using a scalpel blade to expose the fascia.
3. Identify the lumbar spine by the morphology of the posterior fascia inserted onto the tips of the spinous processes. In detail, the third lumbar (L₃) to the first sacral (S₁) fasciae are distinct from other fasciae by their “V” shapes. The last “V” tip connects to the first sacral (S₁) fascia and the first “V” tip corresponds to the L₃ spinous process (Figure 1B).
4. Make the posterior paraspinous muscle incisions along the spinous processes from L₃ to L₅ on both sides laterally with a scalpel blade (Figure 1C). Control the incision depth towards the facets to reduce hemorrhage.
5. Separate the muscle layers using two ophthalmic forceps to expose L₃ to L₅ spinous processes and supraspinous ligaments.

3. Resection of L₃–L₅ spinous processes along with the ligaments

1. Separate individual spinous processes by cutting off interspinous ligaments using Venus shears (Figure 1D).
2. Resect the L₃–L₅ spinous processes along with the interspinous ligaments with Venus shears (Figure 1E).
3. Suture the skin incision with sterile silk braided (suture size 5.0) without reattachment of the paravertebral muscles.
4. Apply Chlortetracycline Hydrochloride Eye Ointment to the surgical site.

Representative Results

Figure 1: Exposure of L3–L5 spinous processes and LSI operation. (A) A custom-made cylindrical pad is placed under the mouse’s abdomen. (B) Exposure of the lumbar fasciae and identification of L3 to S1 spinous processes by “V” shapes. (C) Lateral paraspinous muscle incisions on both sides of L3 to L5 spinous processes. (D) Exposure of individual spinous processes by cutting off interspinous ligaments. (E) Resection of L3–L5 spinous processes with inter- and supra-spinous ligaments.

Materials

Name	Company	Catalog Number	Comments
Chlortetracycline Hydrochloride Eye Ointment	Shanghai General Pharmaceutical Co., Ltd.	H31021931	Prevent eye dry, Prevent wound infection
C57BL/6J male mice	Tian-jiang Pharmaceuticals Company (Jiangsu, CN)	SCXK2018-0004	Animal model
Disposable medical towel	Henan Huayu Medical Devices Co., Ltd.	20160090	Platform for surgical operation
Inhalant anesthesia equipment	MIDMARK	Matrx 3000	Anesthesia
Isoflurane	Shenzhen RWD Life Technology Co., Ltd.	1903715	Anesthesia
Lidocaine hydrochloride	Shandong Hualu Pharmaceutical Co., Ltd.	H37022839	Pain relief
Medical suture needle	Shanghai Pudong Jinhuan Medical Products Co., Ltd.	20S0401J	Suture skin
Ophthalmic forceps	Shanghai Medical Devices (Group) Co., Ltd. Surgical Instruments Factory	JD1050	Clip the skin
Ophthalmic scissors(10cm)	Shanghai Medical Devices (Group) Co., Ltd. Surgical Instruments Factory	Y00030	Skin incision
Silk braided	Shanghai Pudong Jinhuan Medical Products Co., Ltd.	11V0820	Suture skin
Small animal trimmer	Shanghai Feike Electric Co., Ltd.	FC5910	Hair removal
Sterile surgical blades(12#)	Shanghai Pudong Jinhuan Medical Products Co., Ltd.	35T0707	Muscle incision
Veet hair removal cream	RECKITT BENCKISER (India) Ltd	NA	Hair removal
Venus shears	Mingren medical equipment	Length:12.5cm	Clip the muscle and spinous process