A Surgical Procedure for Resecting the Mouse Rib: A Model for Large-Scale Long Bone Repair

Summary

The overall goal of this procedure is to successfully resect a portion of bone from the rib of a mouse. The procedure was developed as a model to study large-scale long bone repair.

Abstract

This protocol introduces researchers to a new model for large-scale bone repair utilizing the mouse rib. The procedure details the following: preparation of the animal for surgery, opening the thoracic body wall, exposing the desired rib from the surrounding intercostal muscles, excising the desired section of rib without inducing a pneumothorax, and closing the incisions. Compared to the bones of the appendicular skeleton, the ribs are highly accessible. In addition, no internal or external fixator is necessary since the adjacent ribs provide a natural fixation. The surgery uses commercially available supplies, is straightforward to learn, and well-tolerated by the animal. The procedure can be carried out with or without removing the surrounding periosteum, and therefore the contribution of the periosteum to repair can be assessed. Results indicate that if the periosteum is retained, robust repair occurs in 1 - 2 months. We expect that use of this protocol will stimulate research into rib repair and that the findings will facilitate the development of new ways to stimulate bone repair in other locations around the body.

Introduction

Debilitating skeletal injury, chronic osteoarthritis, and the severe problems associated with reconstructive surgery impact economic productivity, family well-being, and quality of life. While small breaks and lesions can heal fairly well, humans are not capable of repairing large defects and therefore must rely on reconstructive procedures to restore structure and function. Reconstruction may involve allogeneic or heterogeneic grafts, morcellized bone, implanted scaffolds, or distraction osteogenesis. Unfortunately, not only are there persistant morbidity factors associated with these treatments but the original strength of the repaired bone is rarely attained. ....

Protocol

NOTE: All procedures are in accordance with an animal protocol approved by the Institutional Animal Care and Use Committee (IACUC) at the University of Southern California.

1. Preparation for Surgery

1. Lay out the necessary surgical tools and supplies (sterilized, items 1 - 18 in Materials list) and arrange a dissecting microscope and a fiber optics trans-illuminator in a hood or on a downdraft table.
2. Place a sexually mature mouse (20 - 30 g, 1 - 3 months old) in an induction chamber with 4% isoflurane to induce anesthesia.
3. Confirm anesthesia with a paw and/or tail pinch test.
4. Apply o....

Results

Animals typically recover quickly from this procedure, the incision heals well, and the animals exhibit normal behavior. The procedure uses commercially available supplies and after practice, can be completed in under 1 hr. Before using this procedure to generate experimental data, it is important to analyze the resection at the day 0 time point to determine if any large bone fragments might remain within the resection zone. One way to assess proper procedure is to assess the animals by X-ray or microCT imaging postopera.......

Discussion

When first learning this protocol, determining where to locate the initial incision can be challenging. However, practice on euthanized mice helps the surgeon learn where to place the initial incision and expose the desired rib to be resected. Working on cadavers also improves the fine-motor skills required to remove the rib portion with or without the periosteum. In addition, someone new to this procedure might find manipulating the fine tools and thin sutures to be difficult. While tying off, excess pulling on the sutu.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Medium sized micro-dissection scissors (Vannas-Tübingen Spring Scissors 5 mm)	Fine Science Tools	15003-08
Fine micro-dissection scissors (Vannas Spring Scissors - 2mm Cutting Edge)	Fine Science Tools	15000-04	curved tip is beneficial
Micro-scalpel 5.0 mm	Fine Science Tools	10315-12	other fine scalpels can be substituted
Dumont 55 forceps	Fine Science Tools	11295-51
Retractor	Fine Science Tools	17004-05	adjustability is convenient
Micro-needle holders	Fine Science Tools	12060-01
9.0 nylon sutures (Ethilon), taper point best	Ethicon	2819G or similar	taper point best but reverse cutting is also good
7.0 prolene sutures (Prolene)	Ethicon	8700H or similar	6-0 can be used too, needle point can vary
Large forceps (Adson Forceps)	Fine Science Tools	11006-12	other brands are fine
Lubricant Eye Ointment (Akwa Tears)	Akorn	17478-062-35
Suture glue (GLUture Topical Tissue Adhesive)	Abbot	32046-01	has excellent working time
Shaver	Wahl	9918-6171 or similar
Clamp lamp	Zoo Med	LF-5
Infrared Bulb, 75W	Zoo Med	RS-75
RC2 Rodent Anesthesia System	VetEquip	922100
IsoFlo (Isoflurane)	Abbot	05260-05
Buprenorphine (Buprenex)	Reckitt Benckiser	12496-0757-1
Betadine	Purdue Frederick	67618015017
Flavored Gelatin, raspberry	Jell-O	B000E1FYL0	made up firm, to the consistency of 'jigglers'