//

Removal of subungual exostosis

    Overview

    Learn the Removal of subungual exostosis surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Removal of subungual exostosis surgical procedure.
    Subungual exostosis is an uncommon osteocartilagenous bone tumour that affects the distal phalanx of the toes or fingers, most commonly the hallux. The exostoses are sometimes referred to as a Turret exostoses. The condition is thought to include a true exostosis, characterised by a fibro-cartilaginous cap, and an osteochondroma, with a hyaline cartilage cap.
    A bony growth under the nail of the hallux was first described by Dupuytren in 1817, and has become popularly known as Dupuytrens exostosis. The cause of the growth is unclear, and various aetiologies including trauma, infection, hereditary and tumour have been put forward. There is also debate as to whether subungual exostoses and osteochondromas are the same entity. Exostoses are derived from fibrous tissue with a fibrocartilaginous cap, whereas osteochondromas arise from enchondral ossification with a hyaline cartilage cap. Subungual exostoses have been linked to a reproducible gene translocation, suggesting this is likely to be a neoplastic process as opposed to reactive. Subungual exostoses have also been reported as part of multiple hereditary exostoses
    The differential diagnosis of Subungual exostoses include, other rarer primary bone tumours such as osteosarcoma, Ewings sarcoma, chondrosarcoma, peri-ungual fibroma(Koenens’tumour), onychomatricoma, squamous cell carcinoma, NORA lesions (BPOP:Bizarre parostial osteochondromatous proliferations), lymphoma, pyogenic granuloma, glomus tumour, fungal nail infections (onchomycosis), trauma, mucoid/epidermoid cyst and chronic paronychia.
    55% of patients are under 18 yrs at presentation, 80% of exostoses occur in the hallux and 30% report a history of trauma. Patients present variably with pain, onychodystrophy or a noticeable mass. The incidence of malignant transformation is exceedingly small although recurrence has been described.

    Indications

    INDICATION
    Surgical excision is indicated, in patients presenting with pain, related to the exostosis, a lump that interferes with footwear, occasionally recurrent infections from onychodystrophy, with a confirmed exostosis on radiography, despite appropriate non operative management. Progressive growth of the exostosis should trigger further 3 dimensional imaging to exclude more sinister pathology prior to excision.
    SYMPTOMS & EXAMINATION
    80 percent of patients present with pain, a significant number will present with a dysplastic nail (onychodysplasia), 10% with a palpable lump under the toenail, and a small number with recurrent paronychial infections. Patients report exacerbation of symptoms in firmer shoes with smaller toe-boxes. The majority of subungual exostoses occur in the hallux(80%), though occasionally they are seen in the 5th toe.
    Examination reveals a fullness or visible swelling over the dorsum of the distal phalanx of the toe. There is often a visible abnormality of the toenail, ranging from the subtle, to marked dysplasia of the nail, as it grows over the exostosis. If the nail itself is not thickened when compared to conditions such as fungal nail infection. There maybe evidence of chronic infection if the dysplastic nail and mass effect irritate the lateral nail fold.)
    IMAGING
    An AP, lateral and oblique radiograph should be performed, if a subungual exostosis is suspected. The bony portion of the exostosis is usually seen arising from the dorsal surface of the distal phalanx, usually appearing smaller than clinical examination would suggest on account of the unseen cartilage cap. Evidence of osseous erosion, peri-lesional calcification or sunray spicules are atypical and might suggest sarcomatous change, which should be further investigated with MRI and CT.
    ALTERNATIVE OPERATIVE TREATMENT
    Various approaches have been described including partial excision of the toenail and incision through the nail bed, lateral approach, and excision with currettes, burrs osteotomes and power-saw.
    NON-OPERATIVE MANAGEMENT
    Non operative management for smaller, less symptomatic exostoses include podiatric management of the toenail and foot wear modification incorporating a deeper wider toe box.
    CONTRAINDICATIONS
    Contraindications include, ischaemia, peripheral vascular disease, relative contraindications include active infection

    Setup

    WHO check prior to administration of anaesthetic
    local ring block with or without a general anaesthetic.
    supine feet postioned at the end of the operating table.
    skin prepared with alcoholic iodine followed by alcoholic chlorhexidine.
    tourniquet: ankle or toe

    Operation

    Pre-operative lateral X-ray showing significant subungal exostosis

    Local anaesthetic ring block is performed, here around the base of the hallux.A 15ml mixture of ( 1% lidocaine and 5mg/ml levobupivacaine) local anaesthetic is infiltrated circumfrentially. The prominent lump and dysplastic nail can be clearly seen

    Skin preparation is performed with alcoholic iodine and chlorhexidine.Care is taken to prepare all of the skin of the foot and ankle including each web space. Preparation is completed up to the proximal calf.

    An ankle tourniquet is used in order to aid visualisation and a bloodless surgical field. We tend to use a sterile eschmark bandage wrapped around the ankle which provides adequate pressure over a broad area for the duration of this relatively quick operation.

    The end of the hallux is positioned to point upwards, so that the surgeon can position themselves at the end of the operating table and ensures optimal visualisation of the tip of the toe. Observing the toe from end on here, the exostosis can be seen arising from the lateral aspect of the distal phalanx of the hallux. The overlying nail has deformed and looks dysplastic, more formally described as onychodysplasia.

    The surgical approach is marked using a sterile marker pen. A horizontal line is drawn midway between the plantar surface of the hallux and the nail dorsally extending to the level of the distal nail fold medially and laterally.

    The incision is made along the planned plane, the incision is made down to bone maintaining thick skin flaps, and avoiding undermining the skin edges.

    The incision is continued down to the cortical bone of the tuft of the distal phalanx. Gentle retratction using skin hooks helps expose the distal phalanx for deeper dissection whilst minimising trauma to the skin edges.

    Once cortical bone is exposed along the length of the incision, dissection is progressed dorsally. The aim is to produce a full thickness dorsal skin flap, which is achieved by sharp dissection incising the soft tissues and periosteum away from the dorsal cortical bone, it is important to avoid damage to the nailbed, or more proximally the germinal matrix.

    Dissection progresses along the dorsal cortical bone until the distal extent of the subungual exostosis is encountered. The exostosis is usually quite distinct given the dorsal projection and the sheen of the fibrocartilage cap.

    Dissection is now progressed proximally, the subungual exostosis projects into the nail bed which is stretched and tents over it.The nail bed is at risk of injury during this part of the dissection, and it can be helpful to use a pair of dissection scissors to gently tease open the plane between the nail bed and the exostosis, whilst an assistant elevates the dorsal flap with a small retractor.

    Once the exostosis has been circumferentially exposed, identify the base of the exostosis. Select a margin 1-2mm plantar to this to ensure adequate resection.I select a margin 1-2mm plantar to this to ensure adequate resection.

    The exostosis can be excised with an osteotome, rongeurs, a burr, we prefer a small power saw which gives a controlled resection plane.The aim is to remove the exostosis with an underlying margin of normal bone to reduce recurrence. The plane between the exostosis and cortical bone is usually well demarcated.

    The saw is passed with short, controlled probing cuts taking care not to pass out of the exostosis superiorly and damage the nail bed.

    Once the saw cut is completed the exostosis is gently teased from the surrounding soft tissue using a periosteal elevator and removed.

    The exostosis is removed using forceps and inspected.

    The excised exostosis is inspected to ensure the whole cartilaginous cap has been excised, and the specimen sent for histological analysis.The dorsal aspect of the distal pahalanx inspected for residual fragments or prominent margins, which can be trimmed with a rongeur or rasp.

    If the exostosis is incompletely excised or if there is residual prominence a further plane of bone can be removed with a second saw cut.

    The dorsal flap is reduced and the distal phlanx palpated to assess for any residual prominence that night need to be pared down.

    The dorsal flap is replaced, and deep absorbable sutures are inserted to oppose the deep layer.

    Interrupted mattress sutures are used to close the skin.

    4 or 5 sutures are usually sufficent to close the wound, in this paediatric patient, absorbable sutures were used.

    Local anaesthetic infiltration.A top up ring block with longer acting local anaesthetic can be administered at the end of the procedure to aid post-operative analgesia. 10ml of 5mg/ml levobupivicaine.

    A dry adhesive absorbant dressing is applied directly over the incision.

    Post Operative

    The procedure is performed as a day case.
    Regular non-opioid oral analgesia 48 hours.
    Patients are encouraged to adhere to strict, regular elevation of the operated foot for 72 hours, and weight-bare in a flat surgical sandal for 2 weeks.
    The foot is kept dry for 2 weeks.
    The outer compression bandages are removed at 72 hours by the patient, leaving the underlying adhesive dressing.
    Review in outpatients clinic at 2 weeks for removal of dressings and sutures, confirmation of histological analysis.
    From 2 weeks patients can return to normal shoes and begin gentle low impact sports, swimming and driving.

    Recommended Reading

    Reference

    • orthoracle.com

    Tags:

    You might be interested in

    Dark mode powered by Night Eye