2.1 The EXOGEN ultrasound bone healing system (Smith & Nephew), referred to in this document as EXOGEN, delivers low-intensity pulsed ultrasound waves with the aim of stimulating bone healing. It is thought that healing is promoted by stimulating the production of growth factors and proteins that increase the removal of old bone, increase the production of new bone and increase the rate at which fibrous matrix at a fracture site is converted to mineralised bone. Long bone fractures are suitable for treatment if the fracture is stable and well-aligned. EXOGEN is not indicated for use in fractures of the skull or vertebrae, or in children or adolescents because of their skeletal immaturity.
2.2 The EXOGEN system is a single hand-held device with 2 treatment options: EXOGEN 150 and EXOGEN 250. These are equivalent to the former versions EXOGEN Express and EXOGEN 4000+ respectively. The device has a visual treatment-tracking calendar and treatment history log aimed at improving compliance. EXOGEN controls the number of treatments performed using an SD card. The device operates on a low lithium battery and has a battery door and charger. The device also has a smartphone app, EXOGEN Connects, which enables adherence by providing information such as treatment reminders, information on fracture healing and videos on how to use EXOGEN. The phone app has not been assessed as part of the evaluation. 
2.3 The EXOGEN device consists of a main operating unit with a permanently connected transducer and a separate fixture strap. The strap is placed around the fractured bone, coupling gel is applied to the transducer head (to aid conduction of ultrasound) and the transducer is secured directly over the fracture site by a fixture on the strap. The ultrasound signal emitted by the device is derived from a combination of defined electrical signal parameters and the proprietary transducer design, which generate an acoustic wave pattern specific to EXOGEN. If the patient's limb is immobilised in a cast then a hole is cut in the cast to allow access of the transducer to the skin. The device is programmed to deliver ultrasound in 20‑minute sessions and these are self-administered by the patient each day. It is intended to be used in the patient's home.
2.4 The cost of the EXOGEN 4000+ stated in the sponsor's submission was £2,562.50 (excluding VAT) and the cost of the EXOGEN Express device was £999.38 (excluding VAT).
2.5 The claimed benefits of EXOGEN for long bone fractures with non-union or delayed healing presented in the case for adoption by the sponsor are:
reduced healing time compared with surgery
avoidance of surgery and achievement of comparable clinical outcomes
quicker return to weight bearing and normal daily living compared with surgery
improved treatment accessibility with a therapy that can be self-administered in a home environment
reduced need for high-cost surgical intervention
reduced cost because of a reduction in outpatient care, quicker recovery and return to work and normal living.
2.6 Long bone fractures are usually treated immediately by closed or open reduction (realignment of the bone ends, which can involve surgery). The affected limb is immobilised using a cast or by internal or external fixation. X‑rays are used to verify alignment of the bone. Progress towards fracture healing is usually assessed by X‑ray demonstration of bridging of the gap between the fractured bone ends with new bone cortex.
2.7 Patients with delayed fracture healing at 3 months do not usually have surgery at this time unless the fracture is complex (for example, an unstable or misaligned fracture or an inter-fragment gap of more than 10 mm). Surgery may take place between 3 and 9 months after fracture, but clinical practice varies and decisions about the timing of surgery are made on an individual patient basis. If surgery is considered necessary, it usually involves internal or external fixation and bone grafting (with harvesting from the patient's iliac crest).