Ultrasound scanning helped surgeons to locate the buried metal work: A case series

Abstract

Removal of metalwork in children can be a challenging procedure, particularly if the metalwork is deeply buried and not palpable.

This article proposes a surgical tip to help locate the position of metalwork just before the operation using an ultrasound machine and methylene blue dye.

The technique involves using the ultrasound machine to locate the position of metalwork and marking the tract by injection of methylene blue dye just before prepping and draping the skin. This allows the operation to be performed through a smaller wound with less trauma to the soft tissues and avoids radiation exposure to the patient and theatre personnel. Our experience in a case series of 5 patients have found this a useful technique for removing threaded wires following a Salters osteotomy, where the wires can end up being buried beneath the iliac apophysis. It could however, be used to aid removal of any metal work where difficulty finding it is anticipated. Study expanded to include case series of patients rather than just one example. We have tracked a further 4 patients who have had the same technique used to include them in the paper. Reviewer 2 wanted further examples.

1. Introduction

Metalwork that has been inserted for fracture management or as part of an elective corrective procedure often needs removal in children.

For certain procedures, image intensifier may be the most adequate modality for locating metalwork but this is often a requirement for a number of routine orthopaedic operations and may not be readily available. There is also the added risk of exposure to radiation and requires a radiographer to be present.

Removal of metal work in children who have grown can be particularly challenging as the previous incison may no longer be optimally positioned and bone overgrowth around the metal may have occurred, requiring a relatively large skin incision and with increased trauma of the soft tissues.

The authors propose a novel technique of locating the metalwork using an ultrasound scan machine and methylene blue dye; both of which are readily available.

This technique is has been used for a series of 5 patients to good effect. We have used an example case to illustrate this technique. This method has been used to remove threaded wires inserted during Salter pelvic innominate osteotomy for developmental dysplasia of the hip (DDH). Salter osteotomy is performed in DDH in children between the ages of 18 months to six years.¹ Wires are used to stabilise the osteotomy and graft.¹ The wires are removed once the osteotomy and graft have united.

2. Technique using the case example

A series of patients aged between two and five years have had the threaded wires removed using this technique. All patients except one were female. All patients had unilateral DDH with no other co-morbidities. There were no complications from using this technique and the wires were found and removed easily. In this case example, a three-year-old girl required Salter osteotomy for DDH. Threaded wires were used to control the osteotomy and graft site. The osteotomy healed successfully and the wires needed removal (Fig. 1a). The usual technique for removal of wires involves skin incision through the old scar and soft tissue dissection with removal of any bony overgrowth until the wires can be palpated. This can be time consuming, require a sizeable incision and traumatise the local soft tissues.

Fig. 1.

1a) AP pelvis radiograph showing healed Salter osteotomy in a three old girl with the threaded wires in situ.

1b) Ultrasound image of threaded pin in situ.

Our technique involves locating the threaded wires using the ultrasound scan machine (Fig. 1b) and injecting the tract in line with the wires with 1–2 ml of methylene blue dye Methylthioninium chloride Proveblue 5 mg/ml diluted with an appropriate concentration of bupivicaine. Care is taken to inject the dye into deep tissue so as to not tattoo the skin and to inject in line with the scar so that the scar could be excised if necessary. The patient is then prepped and draped as standard for removing metalwork from the pelvis. The skin incision is made centred on the injection site of methylene blue dye and the soft tissues are dissected to locate the site of the dye (Fig. 2a). Further dissection is performed in line with the dye tract (Fig. 2b) until the wires are exposed (Fig. 2c). The wires can then be removed.

Fig. 2.

2a) Intra-operative clinical photograph: Superficial dissection following incision to locate the methylene blue dye.

2b) Intra-operative clinical photograph: Deeper dissection following the methylene blue dye tract.

2c) Intra-operative clinical photograph: Wires exposed after following the methylene blue tract.

If methylene blue is not available or its use needs to be avoided then injection of just the local anaesthetic (with adrenaline if appropriate) in line with the wire can be performed. Followed by dissection down to the wire following the injection tract.

3. Discussion

Removal of metalwork in children can be a technically challenging procedure. Scars can migrate as children grow relative to the site of placement of the metalwork. The metalwork may not be easily palpable and a relatively large incision and soft tissue dissection may be required.

Ultrasonography has multiple uses in orthopaedic surgery. It can be used in the detection of foreign bodies in soft tissues as well as implant materials in bone.² K-wires are usually easily detectable by palpation. However, some are impalpable, particularly in obese patients. Localising them requires the use of intraoperative fluoroscopy. Using ultrasonography has the benefit of avoiding radiation for the patient and theatre personnel. Using theatre fluoroscopy also requires a radiographer to be present (unless the operating surgeon is trained to use the mini C arm). This is an extra resource that adds to the cost of the procedure.

The use of methylene blue dye is a safe and effective method of identifying abnormal parathyroid glands and is also used as an effective and cheap marker for sentinel lymph node localisation in patients with breast cancer.³ This technique uses a small amount of methylene blue dye with local anaesthetic. The dye marks the track to the metal work, making it easily identifiable and the local anaesthetic gives pre-emptive analgesia.

4. Conclusion

The technique outlined above of using ultrasonography and methylene blue offers a method of limiting the skin incision and soft tissue dissection required for removing metalwork such as buried wires. This can make the procedure more efficient, saving theatre time and avoid the use of ionising radiation. Our experience in a series of 5 patients has shown that this technique is safe to use and increases the proficiency of locating and removing metalwork.

Ethical considerations

Parental consent for using this technique for this procedure and for use of imaging for the case report was done pre-operatively according to Trust protocols.

Declaration of competing interest

The authors declare that there is no conflict of interest.

Appendix A. Supplementary data

The following is the Supplementary data to this article: