Purpose of the study: The efficacy of a new oestrogeneration biomaterial should be demonstrated by in vivo grafts in animal models. Critical filling of bone defects in the rat could be useful as a model before beginning studies in large animals such as the sheep, goat or dog. Creation of a critical defect in the rat femur has been described, but not standardized, leading to difficult comparison between series. In this work, we wanted to establish a detailed standardisable surgical protocol for the creation of a 6 mm femur defect in the rat.

Material and methods: We compared three anaesthesia protocols using 18 mal Wistar rats aged 21 weeks. We developed a surgical procedure enabling study of the advantages of the different commonly used surgical devices either in research or clinic to achieve osteosynthesis and a 6 mm bone defect. We also compared two types of fixation plates (and screws) available on the marker: a 1.2 mm thick titanium plate used for hand surgery and a 1.5 mm steel plate (veterinary medicine). Our postoperative clinical and radiographic follow-up was designed to validate our operative protocol and evaluate osteoregeneration.

Results: We demonstrated first that the use of multimodal anaesthesia radically improved the clinical outcome in the animals. We then demonstrated that the 1.2 mm titanium plates recommended in other studies were too fragile in our model and that the steel 1.5 mm veterinary plates were more adapted. We finally demonstrated the superiority of surgical devises to create a defect and for osteosynthesis. We described a postoperative protocol offering satisfactory evaluation, clinically and radiographically.

Discussion: This work is the first describing this protocol in detail. Improvements in feasibility and cost will make a readily exploitable model for other laboratories. The follow-up on this work should be aimed at improving the quality and pertinence of the analysis methods for the assessment of bone regeneration.

Conclusion: We propose a mode for the critical defect in rat femur bone as a reliable model for the study of osteogenic capacities of new biomaterials.

Purpose of the study: There is no satisfactory surgical solution for symptomatic osteoarthritis of the elbow joint with preserved functional motion if arthroplasty is not indicated (age, functional demand). The same is true for resistant epicondylalgia. The joint denervation techniques applied for the wrist and proximal inter-phalangeal joints have demonstrated their efficacy. We conducted an anatomic study of elbow innervation as a preliminary step to the development of a standardized surgical procedure for complete denervation of the elbow compartment.

Material and methods: The study was conducted on 15 right and left unprepared fresh cadaver specimens. A standardized dissection method was used. The terminal branches of the brachial plexus were dissected proximally to distally under magnification, from the root of the arm to the mid third of the forearm.

Results: Innervation of the medial compartment arose: anteriorly, from one of the two capsuloperiosteal branches arising from the medial nerve; in the epitrochleo-olecraneal gutter, from capsular branches issuing from the trunk of the radial nerve at the root of the arm and running with the ulnar nerve. The innervation of the lateral compartment arose: anteriorly, from an inconstant capsular branch issuing from the musculo-cutaneous nerve arising 4 to 7 cm downstream from the joint space and running between the bones. In the other cases, this zone was innervated by a nerve branch coming from the dorsal cutaneous nerve of the forearm issuing from the radial nerve. This branch innervated the apex of the laeral epicondyle in all cases. The posterior part of the lateral compartment was constantly innervated by a branch arising from the radial nerve in the proximal part of the arm, running between the deep hed of the triceps and the vastus lateralis, giving rise of nerves innervating the joint and terminating in the body of the anconeus muscle.

Discussion: Our study enabled the description of new sources of elbow innervation not reported by Wilhelm.

Conclusion: This systematization study of elbow joint innervation is a preliminary step to the development of a complete procedure for unicompartmental lateral or medial denervation of the elbow joint. The fields of application are the treatment of symptomatic osteoarthritis of the elbow joint in patients with preserved joint motion and resistant epicondylalgia.