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Cubital tunnel decompression with medial epicondylectomy

    Overview

    Learn the Cubital tunnel decompression with medial epicondylectomy surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Cubital tunnel decompression with medial epicondylectomy surgical procedure.
    Cubital tunnel syndrome is the second commonest upper limb peripheral nerve entrapment. The syndrome is a complex pathophysiological spectrum with nerve compression and nerve tension both playing important roles. Decompression of the nerve may create scar tether points, reduce neural glide and increase tension during normal functional elbow range of motion. Creation of instability renders the nerve vulnerable to further irritation and compression against the posterior and medial aspect of the medial epicondyle during movement. Transposition of the nerve has been proposed as a solution to both compression and tension by decompressing the nerve and then rerouting it in a more anterior plan such that the course is shorter and there is no tension during elbow flexion.
    I use this procedure in approximately 1:5 of my primary surgery cases and in all my revision cases. Frequently when a nerve has been transposed and has secondary compression points I will relocate the nerve after performing a neurolysis and medial epicondylectomy. These are specific steps to the procedure that cannot be omitted or the results will not be predictable.

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    Indications

    Indications:
    Surgical treatment of cubital tunnel syndrome should be offered to patients with established motor dysfunction or sensory disturbance that is longstanding (3-6 months) without improvement through conservative measures. Medial epicondylectomy should be performed for primary cubital tunnel syndrome where the nerve is unstable following primary decompression or where the nerve has adverse tension during deep elbow flexion and for revision surgery to eliminate subluxation or secondary tether points and to reduce intraneural tension.
    Transposition of the nerve has been proposed as a solution to both compression and tension by decompressing the nerve and then rerouting it in a more anterior plan such that the course is shorter and there is no tension during elbow flexion. However transposition causes extensive longitudinal scar, can result in impaired vascularity and creates numerous secondary tether points along the course of the nerve.
    Results of transposition are mixed which may reflect the tendency to transpose in revision surgery where reliable outcome cannot be predicted. Medial epicondylectomy is a procedure that leaves the nerve in situ but it removes some of the medial epicondyle to allow the nerve to move anteriorly without compression against bone and so alleviates nerve tension. The is a significant learning curve with this procedure and many surgeons worry about destabilising the elbow by damaging the medial ligaments, creating a raw bone surface causing nerve adhesions or interfering with long flexor function. Performed correctly these risks are insignificant. I use the medial epicondylectomy for all primary cases where there is abnormal tension and where the nerve is unstable following decompression.
    Symptoms and examination:
    Patients report tingling or numbness typically in the ring and small finger and not extending to the forearm. They will frequently report that the symptoms are worse when performing tasks where the elbow is held flexed for long periods or when there is repeated elbow flexion from lifting. Typical provoking activities include using a telephone, reading a book or driving. Symptoms are often worse at night causing nocturnal waking with numbness in the fingers. Patients often notice loss of fine motor movement and co-ordination in the dominant hand and weakness of grip.
    On examination there may be noticeable wasting of the ulnar nerve innervated intrinsic muscles within the hand with loss of bulk especially obvious in the first web space. In severe cases there may be mild clawed posture of the hand typified by MCPJ hyperextension and IPJ flexion. When there is motor involvement there will be reduced power of the flexor digitorum profundus to the small and ring fingers. Sensory loss can be rapidly screened using the “10-10s” test where the patient is asked to rate sensation to light tough in each of the fingers using 10 as normal and 0 as complete numbness. Quantitative sensory assessments can be performed using West or Semmes-Weinstein monofilament pressure threshold detection and innervation density can be assessed using static and moving 2 point discrimination. These should assess the hand as well as the medial arm. Typically medial arm involvement may suggest a more proximal compression at the thoracic outlet level.
    Provocation of symptoms can be achieved through elbow flexion for 1 minute. The onset of tingling or numbness in the ulnar digits is usually diagnostic. Direct compression of the nerve at the cubital tunnel posterior to the medial epicondyle is another way of reproducing symptoms. Tinel’s sign should be assessed starting distally at the hand and working upwards across Guyon’s canal to the forearm and then across the elbow segment to the infraclavicular plexus following the course of the nerve. The reproduction of tingling symptoms during gentle tapping over the nerve can highlight potential areas of compression and also identify other causes of the symptoms such as intrinsic peripheral nerve sheath tumours. Thoracic outlet syndrome and distal compression at Guyon’s canal should be excluded.
    Special tests include Froment’s sign which demonstrates recruitment of the median nerve innervated flexor pollicis longus (FPL) during examination of first webspace grip. Weak adductor pollicis and first dorsal interosseus function is compensated for using FPL. Jeanne’s sign is positive when there is compensatory hyperextension at the MCPJ of the thumb during Froment’s test due to loss of the flexion moment of the intrinsic muscles that should be acting at this joint. Wartenburg’s sign is small finger escape with ulnar deviation due to loss of the palmar interosseus function at the 4th webspace.
    Stability of the ulnar nerve through a full range of active and passive elbow flexion is required to determine whether the nerve subluxes around the medial epicondyle during flexion. Surgical decompression in these cases typically results in further instability and the need for an adjunctive procedure such as medial epicondylectomy can usually be predicted in such cases.
    Revision cases require a more in depth clinical assessment including the sensation in the medial cutaneous nerve of arm and forearm to identify possible sites of injury and neuroma formation, nerve stability and possible secondary sites of compression.
    Investigation:
    Neurophysiological assessment with motor and sensory conduction velocities can detect slowing of conduction across the elbow segment in cases of cubital tunnel syndrome. Comparison can be made with other nerves in the upper limb to exclude concomitant compression neuropathies or peripheral neuropathy. Electromyography can detect denervation changes in the ulnar innervated muscles as a result of motor axon death from longstanding or severe compression. Neurophysiology is essential in equivocal cases and is particularly good at excluding proximal pathology at the brachial plexus, medial cord, thoracic outlet or root level. In revision cases comparison should be made with previous neurophysiology and whether there was any post surgery improvement, even temporary.
    Imaging studies are useful to exclude other pathologies. MRI is useful in the cervical spine or plexus to determine whether symptoms may be contributed to by a spondyloradiculopathy or a thoracic outlet compression. Ultrasound is a useful dynamic investigation to determine site of compression, nerve instability of screen the nerve at other sites to exclude intrinsic pathology such as peripheral nerve sheath tumours. Ultrasound can demonstrate pre-stenotic dilatation of a compressed nerve as well as abnormal motion or thinning during elbow motion indicative of subluxation or abnormal tension.
    Non-operative management:
    Conservative strategies include avoidance of repeated elbow flexion tasks, night elbow extension splints and steroid injection at the cubital tunnel mouth. Splints are poorly tolerated by patients. Steroid injection may be beneficial but should only be undertaken by specialists familiar with the anatomy of the ulnar nerve at the elbow. The nerve lies in a subcutaneous position in deep elbow flexion and is fairly immobile in this position and the risk of inadvertent intraneural injection is high.
    Alternative operative management and contraindications:
    Surgery aims to release any compression points and minimise the risk of secondary complications from nerve subluxation. Decompression may be achieved using mini-open techniques which are designed to address the primary compression site whilst minimising the risk of creating nerve instability. A more extensive decompression can be performed using endoscopic nerve surgery with a light source, long retractors and long scissors. This technique allows proximal and distal compression points to be addressed but does not address tension and there is a learning curve with potentially higher rates of inadvertent iatrogenous injury to the ulnar nerve or the cutaneous branches to the arm and forearm. standard open decompression is the most common surgical procedure but can render the nerve unstable. Unstable nerves can be managed with transposition, designed to shorten the course of the nerve and alleviate tension. Transposition may be subcutaneous or sub-muscular. Both of these techniques carry a risk of creating secondary compression or tether points along the course of the ulnar nerve.

    Setup

    The arm is blocked with an axillary regional anaesthesia at the upper arm. The intercostobrachial nerve (lateral sensory branch form the 2ns intercostal nerve) and the medial cutaneous nerve of the arm lie separate from the main axillary neurovascular bundle and a separate subfascial block of local anaesthesia is usually required for adequate sensory block of the medial arm at the upper extent of the surgical incision.
    The arm is prepped from fingertips to axilla and draped for exposure of the whole limb. A sterile tourniquet is applied to the upper arm as high as possible so that it doesn’t interfere with the site of surgery.
    The shoulder is externally rotated and the elbow flexed 45 degrees and placed on a side table with supportive padding under the lateral side of the elbow to lift the arm away from the side table to improve access.
    If the shoulder doesn’t fully externally rotate then consideration should be given to performing the procedure with the arm flexed across the chest or in the patient under general anaesthesia, in the lateral position with a gutter arm support under the upper arm allowing access to the extensor surface of the elbow.
    The limb is exsanguinated using an Esmarch bandage and the tourniquet inflated to 250mmHg (150mmHg above mean arterial pressure).

    Operation – 1

    The course of the ulnar nerve is marked between the medial epicondyle and the olecanon of the medial side of the elbow.

    The two heads of the FCU (anteriorly the humeral head and posteriorly the ulnar head) join to form the FCU muscle at the distal end of the cubital tunnel. The distal exposure is usually more reliable and it is atthis point on convergence of the two heads where I identify the ulnar nerve before tracing proximally and completing the compression at the most compressed point under Osborne’s fascia.

    The skin is incised for 8 cm in the line of the ulnar nerve along the posterior aspect of the medial epicondyle. This exposure will be sufficient for performing the medial epicondylectomy. In most cases the decision to proceed to epicondylectomy is made intra-operatively. The superficial fat is carefully dissected to avoid injury to the cutaneous nerve branches that typically cross the distal scar a mean of 32mm from the medial epicondyle. Damage to these nerves causes numbness posterior to the scar and painful scar neuromata that result in poor functional outcomes from surgery.

    Meticulous haemostasis using bipolar cautery of cutaneous vessels reduces the rick of wound haematoma.

    The ulnar nerve is identified in the distal part of the wound proximal to the convergence of the two heads of FCU by releasing the deep fascia in the line ofthe surgical incision and gentle spreading of the interval using tenotomy scissors. The fat around the nerve is usually visible at this site and gives a guide to the nerve beneath. Avoid dissection in the fat because the FCU motor branches lie adjacent to the main ulnar nerve trunk in this interval.

    The interval is opened fully allowing visualisation of the ulnar nerve.

    Proximal release of Osborne’s fascia has been completed and now the nerve is visible throughout the cubital tunnel.The decision to perform a medial epicondylectomy was made due to excessive tension in the nerve during deep elbow flexion. The nerve was compressed against the posterior aspect of the medial epicondyle and attempts at lateral glide with gentle digital pressure showed no motion was possible.

    A – Medial intermuscular septum inserting onto medial supracondylar ridge of humerus
    B – Medial epicondyle
    This photograph demonstrates the lower insertion of the medial intermuscular septum onto the medial epicondyle. When the nerve is transposed it may become tethered at the mid humeral level where it obliquely pierces the intermuscular septum and the distal fibrous anterior edge (Arcade of Struthers) causes a tether. In the transposed position the lateral aspect of the ulnar nerve will cross this fibrotic insertion point causing another site of irritation or tether. Even in a medial epicondylectomy where the ulnar nerve anterior translates just a fraction of the distance seen in a formal transposition this ridge can be a problem and it should be excised. At the base of the ridge is a vessel running proximally along the septum. This vessel should be identified and ablated with bipolar diathermy.

    The medial epicondyle is exposed with sharp dissection. First elevate the periosteum at the most posterior aspect and lift anteriorly with the common flexor origin. Release this layer for approximately 1cm. The medial ligaments of the elbow are visible when this layer is elevated and they should not be breached.

    The proximal edge is released together with the insertion of the medial intermuscular septum. This is dissected free so the supracondylar ridge is exposed sufficiently to guide the placement of the osteotome for the osteotomy.

    The posterior and distal elevation of the common flexor origin. The posterior periosteum on the medial epicondyle is thin. It is important to elevate this layer in continuity with the more robust distal tissues where the common flexor origin arises posteriorly as this layer will be used for the closure and muscle reattachment later on.

    Proximal exposure of the medial intermuscular septum insertion.

    Excision of the medial intermuscular septum for 2cm down to the supracondylar ridge.

    Bipolar disthermy cautery of the vessels at the base of the intermuscular septum.

    Using a Mixter (90 degree fine clip) to pass a surgical rubber loop (sloop) beneath the ulnar nerve.

    The sloop enables gentle nerve retraction and acts as a marker so that the operator is aware of the nerve position at all times when working in a narrow field of view with surgical loupe magnification.

    A Ragnell retractor is positioned in the proximal anterior wound edge to aid exposure of the medial supracondylar ridge.

    A 10mm osteotome is used to mark the exit point for the osteotomy. The plane is mid-coronal / mid- sagittal and is designed to remove the medial epicondyle and the retrocondylar groove. The osteome is place distal to proximal for the osteotomy to prevent inadvertent slippage and injury to the ulnar nerve. This first step to check the plane of the osteotomy is critical to prevent too little bone being removed and leaving a ridge or too much and risking an intra articular fracture of the medial humerus.

    The osteotome is now positioned for the osteotomy. The exit point has been already defined proximally. A small mallet is used to take the medial epicondyle away and the assistant gentle retracts the ulnar nerve away from the bone posteriorly and medially during this part of the procedure.

    The osteotomy is mid way through and the operator should again check the alignment and planned exit point superiorly and proximally to ensure that the correct resection is achieved.

    The medial epicondyle is dissected free by using a scalpel to divide any residual soft tissue attachments.

    A fine bone nibbler is used to smooth any remaining ridges and ensure that the surface is smooth.

    The medial epicondylectomy is completed and the nerve is now completely tension free.

    Bone wax is compressed against the exposed cancellous bone surface to reduce bleeding. A McDonalds is used to remove any excess wax and ensure that the cavities are completely filled.

    Smoothing the medial epicondylectomy site.

    Operation – 2

    The completed resection and bone wax cover.

    The posterior periosteal flap is grasped longitudinally with a 2’0 vicryl suture to reduce the risk of suture pull out.

    The suture is then passed through the common flexor origin in a similar fashion and a mattress suture technique is used to replace the common flexor origin back over the epicondylectomy site to obliterate the retrocondylar groove and provide a soft tissue bed for the ulnar nerve. At least three interrupted mattress sutures are required for the repair.

    The sutures are tightended and the common flexor origin reattachment is completed.

    The nerve is seen lying free in the anterior translated position without tension. It is important to confirm that there is no lateral impingement from the medial intermuscular septum remnant.

    Progressive elbow flexion confirms that the nerve is free and not subluxing over any bone prominence.

    In deep elbow flexion the nerve is still mobile and tension free.

    Interrupted absorbable 3’0 sutures placed in the superficial fascia.

    Subcuticular repair with a running 4’0 monacril absorbable suture.

    The completed closure. The wound can be supported with steristrips and then an occlusive dressing. A buly wool and crepe dressing should be placed from mid forearm to mid arm level.

    Post Operative

    The arm should be placed in a sling until the regional block has completely worn off. The arm should be elevated when possible to reduce wound swelling and pain.
    The bulky dressing is reduced after 1 week and the dressing changed.
    Gentle mobilisation is commenced. Lifting should be avoided for four weeks and strenuous activity for six to eight weeks.
    A clinical review at this stage should confirm symptom resolution and return of full range of elbow motion and strength.

    Recommended Reading

    The results of cubital tunnel release and medial epicondylectomy are predictable, however it must be pointed out that there is a learning curver and there are pitfalls for the unwary including insufficient bone resection, leaving bone ridges, poor repair of the soft tissue over the exposed bone and excessive bone resection or soft tissue dissection around the medial ligaments of the elbow. Patient reported outcomes can be recorded with the PRUNE score, however it must be noted that validation for this procedure is not complete and it is the authors experience that the gripping and holding tasks take longer to normalise than for simple decompression, perhaps reflecting the elevation of the common flexor origin as part of the procedure.
    References and literature review:
    Natural History and Conservative Management of Cubital Tunnel Syndrome. (2007). Natural History and Conservative Management of Cubital Tunnel Syndrome, 23(3), 311–318. http://doi.org/10.1016/j.hcl.2007.05.002
    Splinting is effective in cubital tunnel compression however may not be well tolerated by patients. Steroir d injections have lower efficacy than seen in other peripheral nerve compressions such as carpal tunnel syndrome.
    Kim KW, Lee HJ, Rhee SH, Baek GH. Minimal Epicondylectomy Improves Neurologic Deficits in Moderate to Severe Cubital Tunnel Syndrome 2012, 470(5), 1405–1413. http://doi.org/10.1007/s11999-012-2263-1
    This is a small case series reporting improved motor and sensory function in a cohort of patients treated by minimal medial epicondylectomy. The aim of reducing the size of the epicondylectomy is to reduce the attendant complications of this procedure including elbow instability and fracture of the medial condyle of the humerus.
    O’Grady EE, Vanat Q, Power DM, Tan S. A systematic review of medial epicondylectomy as a surgical treatment for cubital tunnel syndrome. J Hand Surg Eur 2017, Nov;42(9):941-945. doi: 10.1177/1753193417724351. Epub 2017 Aug 31.
    This review examines 21 case series and 886 medial epicondylectomy procedure with 79% of cases having improved outcome using McGowan’s criteria. The comparative data for simple decompression is limited with no difference observed in one series. Comparison with transposition shows no difference in 2 series and improved function with medial epicondylectomy in 3 publications.
    MacDermid JC, Grewal R. Development and validation of the patient-rated ulnar nerve evaluation. BMC Musculskeletal Disorders 2013, 14:146
    This paper evaluates a novel patient rated score (PRUNE Score) in the assessment of cubital tunnel syndrome. The use of a disease specific patient reported outcome measure (PROM) is to be recommended for studies in this area. Previous outcome measures for cubital tunnel syndrome have detailed intrinsic wasting, weakness or paralysis and there is significant intra- and inter-observer error. Indeed the literature on cubital tunnel is littered with modifications to previous scoring systems that make meta-analysis impossible.The PRUNE score needs to be validated in simple decompression versus medial epicondylectomy as it may have different responsiveness with different surgical procedures.

    Reference

    • orthoracle.com

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