The suprascapular nerve is an ideal target for nerve blockade to alleviate shoulder pain given its widespread innervation to the shoulder girdle. Many techniques have been described. To widen the availability of this treatment we investigate whether an anatomical landmark technique can be easily learned by novice injectors to provide efficacious blockade.

Five injectors were recruited with varying experience; from the novice medical student to an orthopaedic consultant. Five torsos (10 shoulders) were used. A single page of written instruction and illustration of the Dangoisse landmark technique was provided prior to injection of a Thiel embalmed cadaver bilaterally. A pre-mixed injectate with blue dye was used. Cadavers were dissected and the presence or absence of dye staining reported by 3 observers and a consensus agreement reached.

Dissection demonstrated diffuse staining in the suprascapular fossa. 90% of shoulders were found to have adequate staining of the suprascapular nerve directly, or its distal branches, in a manner which would provide adequate anaesthesia. The inter-observer agreement was good (k = 0.73) for staining at the supraspinous fossa and excellent (k=0.87) for staining distally. The technique was easily performed by novice injectors with a 100% success rate.

We demonstrate that this technique is reproducible by a range of clinicians to effectively provide anaesthesia of the SScN. The main risks are ineffective block (10% in this series) and of intravascular injection. Within a resource strained healthcare environment greater uptake of this technique is likely to be of benefit to a wider array of patients.

Fracture repair occurs by two broad mechanisms: direct healing, and indirect healing with callus formation. The effects of bisphosphonates on fracture repair have been assessed only in models of indirect fracture healing.

A rodent model of rigid compression plate fixation of a standardised tibial osteotomy was used. Ten skeletally mature Sprague–Dawley rats received daily subcutaneous injections of 1 µg/kg ibandronate (IBAN) and ten control rats received saline (control). Three weeks later a tibial osteotomy was rigidly fixed with compression plating. Six weeks later the animals were killed. Fracture repair was assessed with mechanical testing, radiographs and histology.

The mean stress at failure in a four-point bending test was significantly lower in the IBAN group compared with controls (8.69 Nmm^-2 (sd 7.63) vs 24.65 Nmm^-2 (sd 6.15); p = 0.017). On contact radiographs of the extricated tibiae the mean bone density assessment at the osteotomy site was lower in the IBAN group than in controls (3.7 mmAl (sd 0.75) vs 4.6 mmAl (sd 0.57); p = 0.01). In addition, histological analysis revealed progression to fracture union in the controls but impaired fracture healing in the IBAN group, with predominantly cartilage-like and undifferentiated mesenchymal tissue (p = 0.007).

Bisphosphonate treatment in a therapeutic dose, as used for risk reduction in fragility fractures, had an inhibitory effect on direct fracture healing. We propose that bisphosphonate therapy not be commenced until after the fracture has united if the fracture has been rigidly fixed and is undergoing direct osteonal healing.

Cite this article: Bone Joint J 2013;95-B:1263–8.

Objectives

Small animal models of fracture repair primarily investigate indirect fracture healing via external callus formation. We present the first described rat model of direct fracture healing.