A Mini-Invasive Internal Fixation Technique for Studying Immobilization-Induced Knee Flexion Contracture in Rats

Summary

Here, we present a protocol to describe a minimally invasive technique for knee joint immobilization in a rat model. This reproducible protocol, basing on muscle-gap separation modus and the mini-incision skill, is suitable for studying the underlying molecular mechanism of acquired joint contracture.

Abstract

Joint contracture, resulting from a prolonged joint immobilization, is a common complication in orthopedics. Currently, utilizing an internal fixation to restrict knee joint mobility is a widely accepted model to generate experimental contracture. However, implanting application will inevitably cause surgical trauma to the animals. Aiming to develop a less invasive approach, we combined a muscle-gap separation modus with a previously reported mini-incision skill during the surgical procedure: Two mini skin incisions were made on the lateral thigh and leg, followed by performing muscle-gap separation to expose the bone surface. The rat knee joint was gradually immobilized by a preconstructed internal fixation at approximately 135° knee flexion without interfering essential nerves or blood vessels. As expected, this simple technique permits rapid postoperative rehabilitation in animals. The correct position of the internal fixation was confirmed by an x-ray or micro-CT scanning analysis. The range of motion was significantly restricted in the immobilized knee joint than that observed in the contralateral knee joint demonstrating the effectiveness of this model. Besides, histological analysis revealed the development of fibrous deposition and adhesion in the posterior-superior knee joint capsule over time. Thus, this mini-invasive model may be suitable for mimicking the development of immobilized knee joint contracture.

Introduction

Joint contractures are defined as a restriction in the passive range of motion (ROM) of a diarthrodial joint^1,2. The current therapies aiming to prevent and treat joint contracture have achieved some success^3,4. However, the underlying molecular mechanism of acquired joint contracture remains largely unknown⁵. The etiology of joint contractures in different social communities is highly diverse and includes genetic factors, posttraumatic states, chronic diseases, and prolonged immobility⁶. It is widely acc....

Protocol

All procedures were carried out in accordance with the Guide for the Care and Use of Laboratory Animals and were approved by The Third Affiliated Hospital of Sun Yat-sen University institutional animal care and use committee (permission number: 02-165-01). All the animal experiments were performed according to the ARRIVE guidelines.

1. Preoperative preparation

NOTE: Figure 1 shows the design of the surgical procedure.

1. Rigidly immobilize the knee joint with a plastic plate and two metal screws at approximately 135° flexion.
   NOTE: Perform the surgery at the prox....

Results

We observed that rats received minimally invasive surgery can return to the regular diet just one day postoperatively. In particular, the surgical incision has scarred without exudate (Figure 5a). The swelling of the ankle and metacarpophalangeal joints in the operative hindlimb has almost wholly disappeared two days postoperatively (Figure 5b) when compared with the contralateral side (Figure 5c). N.......

Discussion

This study aimed to elucidate a step-by-step knee joint immobilization method using a mini-invasive technique that permits rapid postoperative rehabilitation in animals after surgery. Conventionally, the muscle-gap separation approach is thought to be a minimally invasive technique in orthopedic surgery. As expected, we found that rats can return to a normal diet and activities just one day postoperatively, which was consistent with the previous study. Moreover, no artery or nerve injury occurred after the surgery, evide.......

Materials

Name	Company	Catalog Number	Comments
Anerdian	Shanghai Likang Ltd.	310173	antibacterial
Buprenorphine	Shanghai Shyndec Pharmaceutical Ltd.	/	analgesia
Carprofen	MCE	HY-B1227	analgesia
Cross screwdriver	STANLEY	PH0*125mm	tighten the screws
Electric drill	WEGO	185	drill hole(with stainless steel drill 0.9mm;1.0mm)
Microsurgical instruments	RWD	/	Orthopaedic surgical instruments for animals
Neomycin	Sigma	N6386	antibacterial
Sodium pentobarbital	Sigma	P3761	anaesthetize
Stainless Steel screws	WEGO	m1.4*8; m1.2*6	screw(part of internal fixation)
Syringe	WEGO	3151474	use for plastic plate(part of internal fixation)
μ-CT	ALOKA	Latheta LCT-200	in vivo CT scan