1

Provisional recommendations

1.1

Current evidence on the safety and efficacy of sinus tarsi implant for mobile flatfoot is inadequate in quality and quantity. Therefore this procedure should only be used with special arrangements for clinical governance, consent and audit or research.

1.2

Clinicians wishing to undertake sinus tarsi implant for mobile flatfoot should take the following actions.

• Inform the clinical governance leads in their Trusts.
• Ensure that patients and/or their parents/carers understand the uncertainty about the procedure’s safety and efficacy in relation to symptom relief, quality of life, and long-term outcomes; that the success of the procedure may be dependent on the aetiology of their flatfoot; that there may be a need for adjunctive or subsequent procedures; and that the implant may need to be removed. Patients and parents/carers should be provided with clear written information. In addition, the use of NICE’s information for patients (‘Understanding NICE guidance’) is recommended (available from www.nice.org.uk/IPGXXXpublicinfo). [[details to be completed at publication]]
• Audit and review clinical outcomes of all patients having sinus tarsi implant for mobile flatfoot (see section 3.1)

1.3

The procedure is likely to be suitable for very few people with mobile flatfoot and should only be carried out in highly selected patients.

NICE encourages further research into sinus tarsi implant for mobile flatfoot. Research studies should define patient selection criteria, address uncertainties about using the procedure in children and in adults, include descriptions of adjunctive procedures, and provide long-term outcome data. Studies comparing outcomes of the procedure with the natural history of mobile flatfoot would be useful. NICE may review the procedure upon publication of further evidence.

2

The procedure

2.1

Indications and current treatments

2.1.1

Flatfoot (also called pes planus or pes planovalgus) is characterised by a ‘fallen’ foot arch.

2.1.2

In people with mobile flatfoot, the foot arch is effaced only on weight bearing. Manipulation can restore it to normal appearance. Most children go through a self-resolving phase of mobile flatfoot during growth. In some children, it can be associated with neuromuscular conditions such as cerebral palsy or gross ligamentous laxity. In adults it may be associated with posterior tibial tendon insufficiency.

2.1.3

The condition is usually asymptomatic, particularly in children, but some people may have foot pain.

2.1.4

Orthotics and physiotherapy are usually used to treat children and young adults. Depending on the cause of the condition, adults may be treated with corticosteroid injections, surgical decompression, tendon augmentation, and calcaneum osteotomy or lengthening (lateral column lengthening).

2.2

Outline of the procedure

2.2.1

The procedure (also known as subtalar arthroerisis) can be performed with the patient under general or local anaesthesia. Exact technique and instrumentation varies. The sinus tarsi (a conical opening on the outer side of the foot between the calcaneum and the talus) is accessed by a lateral incision. A trial implant may be used, with intraoperative imaging and simulated weight bearing, to ensure appropriate placement and degree of correction, before a sized implant is implanted. Adjunctive bone or soft tissue procedures may be carried out.

2.2.2

Postoperative care includes using a compression dressing or plaster cast (particularly with adjunctive procedures); the patient may need modified footwear and/or orthotics.

2.2.3

The implant may need to be removed, particularly in children; exact timing for this varies.

Sections 2.3 and 2.4 describe efficacy and safety outcomes from the published literature that the Committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the overview, available at www.nice.org.uk/IP101overview.

2.3

Efficacy

2.3.1

In a case series of 54 patients (68 feet), 24%, 42%, 27% and 6% of patients (or their parents) reported ‘complete’, ‘75%’, ‘50%’ and ‘25%’ or no resolution of symptoms, respectively (mean follow-up 2 years).

2.3.2

In a case series of 37 patients (65 feet), 60% (22/37) reported pain before and 5% (2/37) after the procedure (mean follow-up 26.5 months). In a case series of 23 patients (28 feet) mean pain score decreased from 3.2 preoperatively to 1.6 postoperatively on a scale from 4 (severe pain) to 1 (no pain) (p < 0.0001) (mean follow-up 44 months).

2.3.3

The Specialist Advisers stated that key efficacy outcomes

include quality of life, pain relief, X-ray angles, gait analysis, normal foot shape and

2.4

Safety

2.4.1

In six case series, less than 1% (2/234), 5% (4/80), 5% (3/65), 7% (3/41), and 39% (11/28) of feet and 10% of patients (exact number not stated) needed implant removal (follow-up 3 months–10 years).

2.4.2

In the case series of 23 patients, one patient had a fractured talus 6 years after implantation.

2.4.3

A case series of 1 patient reported avascular necrosis in one foot following bilateral surgery 10 years after implantation. A different case series of 1 patient reported bilateral intraosseous talus cysts and osteophytes at 2.5-year follow-up. In the case report of 54 patients, 1 had evidence of talus bony sclerosis at 4-year follow-up. A case report of 3 patients (six feet) recorded talus spur formation in one foot 3 months after implantation.

2.4.4

The case series of 54 patients reported implant extrusion in 9% of feet after 1 year and a case series of 49 patients reported fragments in the sinus tarsi (unclear whether bone or implant) in one foot (follow-up not stated).

2.4.5

The Specialist Advisers considered theoretical or anecdotal adverse events to include infection, persistent implant-related pain, implant fracture or extrusion, sural nerve injury, incorrect device positioning or over-sizing, complete loss of subtalar movement, peroneal spasm, silicone synovitis, intraosseous cyst and foreign body granuloma formation.

3

Further information

This guidance requires that clinicians undertaking the procedure make special arrangements for audit. NICE has identified relevant audit criteria and is developing audit support (which is for use at local discretion), which will be available when the guidance is published.

3.2

NICE has published interventional procedures guidance on metatarsophalangeal joint replacement of the hallux (www.nice.org.uk/IPG140).