Maximum Isometric Tetanic Force Measurement of the Tibialis Anterior Muscle in the Rat

Summary

Evaluation of motor recovery remains the benchmark outcome measure in experimental peripheral nerve studies. The isometric tetanic force measurement of the tibialis anterior muscle in the rat is an invaluable tool to assess functional outcomes after reconstruction of sciatic nerve defects. The methods and nuances are detailed in this article.

Abstract

Traumatic nerve injuries result in substantial functional loss and segmental nerve defects often necessitate the use of autologous interposition nerve grafts. Due to their limited availability and associated donor side morbidity, many studies in the field of nerve regeneration focus on alternative techniques to bridge a segmental nerve gap. In order to investigate the outcomes of surgical or pharmacological experimental treatment options, the rat sciatic nerve model is often used as a bioassay. There are a variety of outcome measurements used in rat models to determine the extent of nerve regeneration. The maximum output force of the target muscle remains the most relevant outcome for clinical translation of experimental therapies. Isometric force measurement of tetanic muscle contraction has previously been described as a reproducible and valid technique for evaluating motor recovery after nerve injury or repair in both rat and rabbit models. In this video, we will provide a step-by-step instruction of this invaluable procedure for assessment of functional recovery of the tibialis anterior muscle in a rat sciatic nerve defect model using optimized parameters. We will describe the necessary pre-surgical preparations in addition to the surgical approach and dissection of the common peroneal nerve and tibialis anterior muscle tendon. The isometric tetanic force measurement technique will be detailed. Determining the optimal muscle length and stimulus pulse frequency is explained and measuring the maximum tetanic muscle contraction is demonstrated.

Introduction

Loss of motor function following traumatic peripheral nerve injury has a significant impact on the quality of life and socioeconomic status of patients^1,2,3. The prognosis of this patient population remains poor due to minimal improvements in surgical techniques over the years⁴. Direct end-to-end tension-free epineural repair forms the gold standard surgical reconstruction. However, in cases with extended nerve gaps interposition of an autologous nerve graft has proven to be superior^5,6. The as....

Protocol

All animal procedures were performed with approval of the Institutional Animal Care and Use Committee (IACUC A334818).

1. Calibration of the force transducer

1. Ensure that the computer is properly connected to the USB-6009 multifunctional I/O data acquisition (DAQ) device, which in turn should be connected to the force transducer.
   NOTE: Other rat strains and species may require a different load-cell force transducer as higher forces are to be expected ⁴⁴

Discussion

This protocol describes a previously validated method for acquiring accurate maximum ITF measurements of the TA muscle in the rat model³². The recovery of maximum strength after experimental nerve reconstruction treatments is of primary interest in the clinical setting as it proves that the nerve not only regenerated, but also made working connections with the target muscle. The ITF can be used in a small nerve gap model, such as the rat sciatic nerve model³², and with a fe.......

Materials

Name	Company	Catalog Number	Comments
0.9% Sodium Chloride	Baxter Healthcare Corporation, Deerfield, IL, USA	G130203
1 mm Kirshner wires	Pfizer Howmedica, Rutherford, NJ	N/A
Adson Tissue Forceps	ASSI, Westbury, NY, USA	MTK-6801226
Bipolar electrode cables	Grass Instrument, Quincy, MA	N/A
Bipolar stimulator device	Grass SD9, Grass Instrument, Quincy, MA	N/A
Cotton-tip Applicators	Cardinal Health, Waukegan, IL, USA	C15055-006
Curved Mosquito forceps	ASSI, Westbury, NY, USA	MTK-1201112
Force Transducer MDB-2.5	Transducer Techniques, Temecula, CA	N/A
Gauze Sponges 4x4	Covidien, Mansfield, MA, USA	2733
Ground cable	Grass Instrument, Quincy, MA	N/A
Isoflurane chamber	N/A	N/A	Custom-made
Ketamine	Ketalar, Par Pharmaceutical, Chestnut, NJ	42023-115-10
LabView Software	National Instruments, Austin, TX
Loop	N/A	N/A	Custom-made
Microsurgical curved forceps	ASSI, Westbury, NY, USA	JFA-5B
Microsurgical scissors	ASSI, Westbury, NY, USA	SAS-15R-8-18
Microsurgical straight forceps	ASSI, Westbury, NY, USA	JF-3
Retractor	ASSI, Westbury, NY, USA	AG-124426
Scalpel Blade No. 15	Bard-Parker, Aspen Surgical, Caledonia, MI, USA	371115
Slim Body Skin Stapler	Covidien, Mansfield, MA, USA	8886803512
Subminiature electrode	Harvard Apparatus, Holliston, MA	N/A
Surgical Nerve Stimulator	Checkpoint Surgical LCC, Cleveland, OH, USA	9094
Terrell Isoflurane	Piramal Critical Care Inc., Bethlehem, PA, USA	H961J19A
Testing platform	N/A	N/A	Custom-made
Tetontomy Scissors	ASSI, Westbury, NY, USA	ASIM-187
Traceable Big-Digit Timer/Stopwatch	Fisher Scientific, Waltham, MA, USA	S407992
USB-6009 multifunctional I/O data acquisition (DAQ) device	National Instruments, Austin, TX	779026-01
Vacuum Base Holder	Noga Engineering & Technology Ltd., Shlomi, Isreal	N/A	Attached clamp is custom-made
Weight (10 g)	Denver Instruments, Denver, CO, USA	820010.4
Weight (20 g)	Denver Instruments, Denver, CO, USA	820020.4
Weight (50 g)	Denver Instruments, Denver, CO, USA	820050.4
Xylazine	Xylamed, Bimeda MTC Animal Health, Cambridge, Canada	1XYL002