Posterior and Anterior interosseous nerve neurectomies of the wrist

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This is a detailed step by step instruction through a neurectomy of the posterior interosseous nerve (PIN) and anterior interosseous nerve (AIN) undertaken to reduce pain perception within the wrist joint.
The procedure is usually carried out following a successful trial of local anaesthetic injection around the nerve used to predict post-operative pain relief. The two nerves are transected at a level just proximal to the dorsal radio-ulna joint where both nerves can be accessed via the dorsal wrist approach.
The operation is simple to perform and commonly performed in certain situations such as wrist arthritis, dorsal wrist pain of unknown origin and wrist instability. Usually a more formalised operation is performed such as partial wrist fusion, ligament reconstruction etc. however in some cases the patient may want to retain their current range of movement or not want to undergo such a large operation and therefore opt for a denervation of the wrist.
The denervation will not stop progression of the underlying pathology but may make it more tolerable. In some cases where the initial operation has failed to relieve all the pain, a wrist denervation may be a useful secondary procedure to improve patient symptoms.
Complications are rare and 60-90% of patients show improvements in pain scores with around 50% having increased grip strength compared to a per-operative level.
The operation is performed as a daycase procedure and the patient can gently mobilise the hand straight after discharge. The outcome of the surgery is complete after 3-4 months post-operation. The PIN is a continuation of the radial nerve. It innervates the extensor muscles of the forearm but by the time it reaches the site of the operation the only innervation distal to this point is the pseudo-ganglion supplying the dorsal wrist capsule and ligaments of the wrist.
The AIN is a branch from the median nerve innervates the radial half of flexor digitorum profundus and the flexor pollicis longus proximal to the operative site and the pronator quadrates and volar wrist capsule and ligaments distal to the site of surgery. The posterior interosseous artery (PIA) and anterior interosseous artery (AIA) which run with their respective nerves are branches from the common interosseous artery, a branch of the ulnar artery at the level of pronator teres. The PIA and AIA anastomose distally and contribute to the dorsal carpal arch.
Author – Mr Mark Brewster
Royal Orthopaedic Hospital, Birmingham

Indications
This procedure is indicated for wrist pain which is not responding to simple analgesia or splintage where a larger procedure is not deemed appropriate or acceptable by the patient.
Best outcomes are achieved when a local anaesthetic injection delivered in the clinic setting has been shown to improve the pain.
The procedure can be performed to reduce wrist pain as an alternative to more major surgery in wrist arthritis, dorsal wrist pain of unknown pathology and wrist instability. It may also be used in addition to these operations or as an additional procedure following a poor result and continued pain of the other procedures.
The denervation will not stop progression of the underlying pathology but may make it more tolerable.
A denervation of PIN and AIN is usually employed when:
Interventions, operative or non-operative, have failed and there is no other clear intervention to further reduce the pain.
The cause of then wrist pain is unknown but all treatable pathologies have been ruled out.
Patient declines certain larger operations due to the level of risk associated, restriction in range of movement or length of recovery time associated.
Surgeon will not undertake larger procedures due to risk to patient.
Symptoms
Wrist pain improved by local anaesthetic injection around nerve (as discussed in examination).
Examination
The examination related to this procedure is to ascertain the location of the pain and likely cause. If the location of the pain from palpation and movement of the wrist is localised and based on the overall history and assessment the denervation is being considered, then part of the examination/treatment is a local anaesthetic injection. This is to provide prognostic advise and assist in obtaining informed consent for the surgical procedure.
The patient is injected with a long acting anaesthetic around the two nerves. This injection is placed around 2cm proximal to the proximal aspect of the head of the ulna, in the gap between the radius and ulna occupied by the interosseous membrane (IOM). A 5ml syringe is used with a 23 gauge hypodermic needle entering perpendicular to the skin. The needle is inserted until the resistance of the IOM is felt. Around 1ml of the plain local anaesthetic is then injected deep and then 1ml superficial to the IOM. The patient is then sat back in the waiting room and then reviewed after 10mins. At this point the wrist is re-examined. If the pain level has improved significantly a decision to go ahead with surgery may be taken. If the examination is equivocal the patient can either be re-examined after a further 10mins or asked to go home as use the wrist normally and record any benefit perceived to discuss at the next appointment.
Although used for prognostic purposes, some papers suggest when research the correlation between results of the local anaesthetic injection and the surgery are poor. It is however the only preoperative assessment we have.
Investigations
Investigations are related to the underlying diagnosis and apart from the local anaesthetic injection mentioned, no further investigations are required as long as other pathologies which may cause wrist pain (nerve pain, chronic regional pain syndrome, inflammatory arthritis) are ruled out and/or treated.
Non-operative Management
Non-operative management for wrist pain depends on the underlying pathology and will usually include, analgesia, activity modification, wrist splinting, physiotherapy with grip strengthening and steroid and local anaesthetic injections.
Alternative operative Management
As this procedure is a purely pain relief procedure used in addition to or instead of other interventions the only other alternative operative intervention in such patients would be a more radical wrist denervation as described by A. Wilhelm in 1966.
Contraindications
The single relative contraindication to this procedure is the failure of the test injection of local anaesthetic to improve any pain symptoms in the wrist however this can be disputed.

Pre-operative preparations and Equipment
The operation can be performed under general or regional anaesthetic. The surgery take around 15-20mins to perform and a bloodless field is achieved using an upper arm tourniquet set to 250mmHg with the arm resting on an arm board.
Loupe magnification is used.
Simple equipment including a West self retainer, tenotomy scissors, Ragnell retractors and bipolar diathermy are all that is required.

The procedure is performed as a daycare and therefore the patient is discharged with advice to gentle mobilise the fingers and wrist within the bulky bandage over the next week.
The patient is then reviewed in the outpatient department at 1 week for a wound check and to start physiotherapy if required. There are no restrictions to therapy and it may be better tolerated than preoperatively if the neurectomy has been effective in pain reduction.
if the wound is healthy and as the sutures are dissolvable the patient is advised to remove the dressing at 2 weeks and wash the skin as normal with the sutures expected to fall out at 2-3 weeks post surgery.
A final review at 4 months is then planned and the outcomes of the surgery assessed. The published papers suggest that it is still possible for some improvement of symptoms up to 18 months following the surgery.

This is a relatively safe procedure. Theoretical complications of tendon injury, median nerve injury, haematoma, infection and scar pain are possible but extremely rare. The most likely complication is that the procedure offers little or no lasting pain relief.
Please see the below references and summaries for more information on denervation procedures.
Storey PA, Lindau T, Jansen V, Woodbridge S, Bainbridge LC, Burke FD. Wrist denervation in isolation: a prospective outcome study with patient selection by wrist blockade. Hand Surg. 2011;16(3):251-7.
This team from the Pulvertaft unit in Derby, UK, reviewed 37 patients post PIN and AIN denervations. Patients included all had pre-operative good response to local anaesthetic blockade. At a mean of 18 months activity pain scores had decreased by 60% and 30 of the 37 patients reported a continuing improvement in the pain relief.

Weinstein LP, Berger RA. Analgesic benefit, functional outcome, and patient satisfaction after partial wrist denervation.J Hand Surg Am. 2002 Sep;27(5):833-9.
19 patients (20 wrists) with isolated AIN and PIN neurectomy were reviewed at a mean of 2.5 years. 80% reported less pain, 45% had normal or increased grip strength, and 73% of those employed had returned to work. Three patients underwent additional procedures (2 arthrodesis, 1 radial styloidectomy). Failures occurred within 12 months and there were no complications.
85% reported satisfaction with this procedure and 90% would choose the same treatment again.
Van de Pol GJ1, Koudstaal MJ, Schuurman AH, Bleys RL.Innervation of the wrist joint and surgical perspectives of denervation.J Hand Surg Am. 2006 Jan;31(1):28-34.
18 wrists were anatomical and histologically reviewed. They found the nerve innervation to the wrist capsule and periosteal network was from the AIN, PIN and lateral antebrachial cutaneous nerve. The palmar cutaneous branch of the median nerve, the deep branch of the ulnar nerve, the superficial branch of the radial nerve, and the dorsal branch of the ulnar nerve also supplied the capsule.
With this review the authors suggested a volar and dorsal incision for complete wrist denervation disconnecting the periosteum from the capsule to transect most relevant nerves.
A further paper comparing anatomy to Wilhelm’s 1966 denervation suggested that the branches from the deep branch of the ulna nerve would continue to innervate the wrist after a ‘complete Wilhelm’s denervation’.
19 patients (20 wrists) with isolated AIN and PIN neurectomy were reviewed at a mean of 2.5 years. 80% reported less pain, 45% had normal or increased grip strength, and 73% of those employed had returned to work. Three patients underwent additional procedures (2 arthrodesis, 1 radial styloidectomy). Failures occurred within 12 months and there were no complications.
85% reported satisfaction with this procedure and 90% would choose the same treatment again.
18 wrists were anatomical and histologically reviewed. They found the nerve innervation to the wrist capsule and periosteal network was from the AIN, PIN and lateral antebrachial cutaneous nerve. The palmar cutaneous branch of the median nerve, the deep branch of the ulnar nerve, the superficial branch of the radial nerve, and the dorsal branch of the ulnar nerve also supplied the capsule.