Patients › Elbow

Pag-release ng Pronator at AIN

Updated Oct 2026

Bakit iminungkahi ang operasyong ito¶

Si Dr Kieran Hirpara, isang upper-limb surgeon sa Mater Private Hospital Rockhampton, ay nagsisimula sa mga opsyon na hindi gaanong invasive na angkop sa iyong kondisyon. Ang operasyong ito ay isang nerve release sa iyong forearm. Pinapagaan nito ang pressure sa isa sa mga pangunahing nerve na dumadaan mula sa iyong siko hanggang sa iyong kamay. Karaniwan namin itong iminumungkahi kapag hindi nagbigay sa iyo ng sapat na ginhawa ang ibang mga paggamot.

Karamihan sa mga tao ay sumusubok muna ng non-operative care. Nangangahulugan ito ng pagpapahinga sa braso, pag-iwas sa mga aktibidad na nagpapalala sa iyong mga sintomas, at pag-inom ng anti-inflammatory medicine. Isinasaalang-alang ang operasyon kapag nagpapatuloy ang mga sintomas sa kabila ng pangangalagang ito. Para sa pronator syndrome, ang operasyon ay isang opsyon kung ang iyong mga sintomas ay tumagal nang higit sa 6 na buwan. Para sa anterior interosseous nerve syndrome, ito ay isang opsyon pagkatapos ng hindi bababa sa 12 buwan na walang palatandaan ng pagbabalik ng lakas ng kalamnan. Maaari rin naming imungkahi ang operasyon nang mas maaga kung ang iyong mga pang-araw-araw na gawain ay nangangailangan ng malakas at paulit-ulit na pagpihit ng forearm at kinukumpirma ng mga pagsusuri na naiipit ang nerve.

Ang layunin ng operasyong ito ay ibsan ang iyong sakit at ibalik ang lakas at paggamit ng iyong kamay. Ang kumpletong ginhawa ay nangyayari sa mga 64 hanggang 71% ng mga tao. Mga 20% ang nakakakuha ng hindi kumpletong ginhawa, at mga 8% ang nangangailangan ng karagdagang operasyon. Pag-uusapan namin ang mga numerong ito kasama mo upang makapagpasya ka kasama namin kung ang operasyon ay tama para sa iyo.

Bago ang operasyon¶

Bibigyan ka ng iyong surgeon ng malinaw na mga tagubilin upang makapaghanda. Kakailanganin mong itigil ang pagkain at pag-inom pitong oras bago ang iyong operasyon. Humihingi kami ng pito sa halip na anim upang maiuna ang iyong operasyon kung mas maaga ang takbo ng listahan sa theatre. Maaaring kailanganin mong itigil ang ilang gamot bago ang operasyon, at sasabihin sa iyo ng iyong surgeon kung alin at kailan. Mag-ayos ng taong maghahatid sa iyo pauwi pagkatapos. Magdala ng listahan ng iyong mga kasalukuyang gamot. Magsuot ng maluwag at komportableng damit sa araw ng operasyon. Maaaring gamitin ang imaging gaya ng X-ray, MRI o ultrasound scan upang maplano ang operasyon. Kung mayroon kang iba pang kondisyong medikal, maaaring kailanganin mo ng mga blood test o pagsusuri kasama ang anaesthetist, ngunit hindi ito kailangan ng karamihan ng tao.

Sa araw ng operasyon¶

Darating ka sa surgical admissions unit ng ospital. Ire-rehistro ka ng mga staff at ihahanda para sa theatre. Pagkatapos ay makikipagkita ka sa anaesthetist, ang doktor na nagbibigay ng gamot na nagpapatulog sa iyo at nagpapanatili sa iyong komportable habang isinasagawa ang operasyon. Ang operasyong ito ay ginagawa sa ilalim ng general anaesthetic. Minsan ay nagdaragdag ng regional nerve block para sa pagbawas ng sakit pagkatapos ng operasyon; tatalakayin ito ng anaesthetist sa iyo sa araw na iyon.

Pagkatapos ay dadalhin ka sa operating theatre, kung saan isasagawa ang operasyon. Kapag tapos na ito, magigising ka sa recovery area. Babantayan ka roon ng mga nurse habang nawawala ang bisa ng anaesthetic. Kapag stable ka na, pupunta ka sa ward o uuwi na, depende sa procedure at sa iyong paggaling.

Ano ang kinapapalooban ng operasyon¶

Ito ay isang nerve release sa iyong forearm. Gagawa ang iyong surgeon ng hiwa sa harap ng iyong forearm, malapit sa iyong siko, upang maabot ang nerve. Pinananatiling kasingliit hangga't maaari ang hiwa. Sa pamamagitan nito, hahanapin ng iyong surgeon ang mga bahagi kung saan pinipiga ng masikip na tissue ang nerve at palalayain ang tissue na iyon, upang mapalaya ang nerve sa buong kahabaan nito. Kung may banda ng tissue o kakaibang daluyan ng dugo na dumidiin sa nerve, tinatanggal din iyon.

Isinasara ang hiwa gamit ang mga tahi at tinatakpan ng dressing. Uuwi ka nang nakalagay pa rin ang dressing.

Ang operasyon mismo ay nakatuon at maingat na trabaho sa isang maliit na espasyo. Ang pagpapalaya sa nerve kung saan ito dumadaan sa kalamnan ng forearm ay nangangailangan ng mas malalim na dissection kaysa sa ilang ibang nerve release, kaya naglalaan ng oras ang iyong surgeon upang protektahan ang nerve at ang mga istruktura sa paligid nito.

Pagkatapos ng operasyon¶

Magigising ka sa recovery area na may mga nurse na nagbabantay sa iyo habang nawawala ang bisa ng anaesthetic. Maaaring mabigat o manhid ang pakiramdam ng iyong braso nang ilang sandali. Inaasahan ito, at humuhupa ito habang nawawala ang bisa ng gamot. Bibigyan ka ng pain relief upang mapanatili kang komportable, at nakabalot ang iyong kamay at forearm sa malambot na dressing. Maaari kang gumalaw-galaw sa lalong madaling panahon pagkagising, at dapat may taong sumama sa iyo sa unang 24 oras. Sasabihin sa iyo ng iyong team kung uuwi ka sa araw ring iyon o mananatili ng isang gabi sa ospital. Pananatilihin namin ang dressing sa loob ng humigit-kumulang 10 araw; pakiusap na huwag itong tanggalin bago ang panahong iyon maliban kung sinabi namin sa iyo. Papalitan o tatanggalin namin ito kapag nakita ka na namin.

Paggaling¶

Sa mga unang araw, maaaring masakit at namamaga ang iyong kamay at forearm. Maaaring kumirot ang paligid ng hiwa, at maaaring maninigas ang pakiramdam ng iyong mga daliri. Ang pahinga, ang pagpapanatiling nakataas ng iyong kamay sa isang unan, at ang iyong pain relief ay pawang nakatutulong upang maibsan ito. Karaniwang humuhupa ang hindi komportableng pakiramdam habang lumilipas ang bawat araw.

Uuwi ka na may malambot na dressing sa iyong braso. Pananatilihin namin ito sa loob ng humigit-kumulang 10 araw at papalitan o tatanggalin ito kapag nakita ka namin. Kapag natanggal na ito, magsisimula ang hand therapy. Ang iyong hand therapist, si Ruby Doolan sa Extend Rehabilitation, ang gagabay sa iyong mga ehersisyo at gagawa ng anumang splint na kakailanganin mo. Pinananatiling gumagalaw ng mga ehersisyong ito ang iyong mga daliri at pinipigilan ang paninigas habang kumakalma ang nerve.

Sa bahay, magagawa mo ang karamihan ng magagaan na pang-araw-araw na gawain sa loob ng unang mga dalawang linggo, gamit ang iyong kamay ayon sa kaya ng iyong ginhawa. Iwasan ang mabigat na pagbubuhat, malakas na paghawak, o anumang nagpapahirap sa forearm hanggang payagan ito ng iyong therapist. Matulog sa anumang posisyong komportable; mas gusto ng ilang tao na ipatong ang braso sa mga unan sa tabi nila.

Sumusunod ang paggaling sa isang pattern sa halip na sa isang takdang iskedyul. Una, humuhupa ang sakit at pamamaga. Pagkatapos ay bumabalik ang galaw at kapit (grip). Patuloy na bumubuti ang lakas at pakiramdam sa iyong kamay sa loob ng maraming buwan, at ang huling resulta ay dumarating kapag tumigil nang magbago ang iyong sakit at lakas. Bawat isa ay gumagaling sa sarili niyang bilis, kaya maaaring magkaiba ang iyong timeline; gagabayan ka ng iyong surgeon at ng iyong therapist sa prosesong ito.

Ano ang maaaring maging problema¶

Karamihan sa mga pasyente ay gumagaling, ngunit paminsan-minsan ay maaaring magkaroon ng mga problema. Binabantayan kayo nang maigi ng inyong surgeon at ng team upang maagapan ang anumang isyu.

Dahil ang release na ito ay ginagawa nang malalim sa kalamnan ng forearm, mas komplikado ang operasyon kaysa sa ilang ibang nerve release. Nag-iingat nang husto ang inyong surgeon upang protektahan ang nerve at ang tissue sa paligid nito.

Ang nerve na pinalalaya ay malapit sa iba pang mga nerve na nagbibigay ng pakiramdam at galaw sa inyong kamay. Bihira, maaaring mairita ang isa sa mga ito habang isinasagawa ang operasyon. Maaaring mapansin ninyo ang bagong pamamanhid, pangingilig (pins and needles), o panghihina sa bahagi ng inyong kamay o forearm kapag nawala na ang bisa ng nerve block, na inaabot ng mga 24 oras. Inaasahan ang kaunting pamamanhid at panghihina sa unang 24 oras dahil sa block mismo. Kung magpatuloy ito lampas doon, tumawag sa klinika.

Maaari ring magkaproblema ang sugat. Tumawag sa klinika sa mismong araw na iyon kung may lagnat kayo, pamumulang kumakalat mula sa hiwa, o likido o nana na tumutulo mula rito. Ang sakit na patuloy na lumalala sa kabila ng inyong mga gamot sa sakit ay nangangailangan din ng tawag sa mismong araw na iyon.

Kung minsan, may nabubuong matigas at masakit na bukol malapit sa sugat sa mga araw pagkatapos ng operasyon. Ito ay naipong dugo sa ilalim ng balat. Kung lumalaki ito, lalong sumasakit, o mukhang banat at makintab ang balat sa ibabaw nito, tumawag sa klinika.

Kung ang release ay ginawa sa pamamagitan ng maliit na keyhole na hiwa sa halip na open na hiwa, paminsan-minsan ay hindi ito nagtatagal, at maaaring kailanganin ang karagdagang operasyon. Tatalakayin ito ng inyong surgeon kasama ninyo kapag pinaplano ang inyong pangangalaga.

Kadalasang mabagal ang paggaling mula sa operasyon sa nerve, at maaaring patuloy na bumuti ang nerve sa loob ng maraming buwan. Kung gaano ito kahusay gumaling ay nakadepende sa bahagi kung gaano katagal itong naipit bago ang operasyon. Kung matagal nang naroroon ang pressure, maaaring hindi na lubos na bumalik sa dati ang ilang pagbabago sa kamay. Pag-uusapan ninyo ng inyong surgeon kung ano ang maaasahan sa inyong kaso.

Ang complications table sa pahinang ito ay naglilista ng mga tipikal na rate kung nais ninyo ang mga detalye.

Kailan dapat tumawag sa amin¶

Karamihan sa mga problema ay lumilitaw sa unang ilang araw. Ang ilan ay nangangailangan ng mabilis na tawag, at ang ilan ay nangangailangan ng agarang pangangalaga.

Pumunta sa emergency department kung namamaga o masakit ang iyong calf (binti), o kung nahihirapan kang huminga o nagkakaroon ng pananakit ng dibdib. Ang mga ito ay maaaring senyales ng blood clot. Pumunta rin sa emergency department kung ang iyong mga daliri, kamay o hinlalaki ay namutla, lumamig, pumuti, naging asul o nangitim, dahil nagpapahiwatig ito ng problema sa daloy ng dugo.

Tumawag sa klinika sa mismong araw na iyon kung may lagnat ka, pamumulang kumakalat mula sa hiwa, o likido o nana na tumutulo mula rito. Ang sakit na patuloy na lumalala sa kabila ng iyong mga gamot sa sakit ay nangangailangan din ng tawag sa mismong araw na iyon.

Tumawag sa klinika kung hindi mo maramdaman ang iyong braso, kamay o mga daliri, o hindi mo maigalaw ang mga ito, kapag nawala na ang bisa ng nerve block. Inaabot ng mga 24 oras bago mawala ang bisa ng block, at inaasahan ang pamamanhid at panghihina sa panahong iyon. Kung magpatuloy ito lampas doon, tumawag sa amin.

Kung hindi mo makontak ang klinika sa labas ng oras ng opisina o sa weekend, pumunta sa pinakamalapit na emergency department.

Evidence & references

This is the clinical evidence summary written for health professionals. It is technical, and it lists the research this page was built from. You do not need to read it to understand your treatment or to make a decision about it.

Overview¶

Surgical decompression can be considered for pronator syndrome when activities of daily living require frequent strong pronation and electromyography confirms compression [1].
Other medical causes should be considered in anterior interosseous nerve syndrome with pure motor loss [1].
Pronator syndrome can be successfully treated nonoperatively or surgically when the correct diagnosis is made [2].
Cases of brachial plexus neuritis-induced anterior interosseous nerve palsy should be managed conservatively [3].
Surgical decompression may be performed for specific instances of direct trauma causing anterior interosseous nerve palsy [3].
Patients presenting with paresis in incomplete anterior interosseous nerve syndrome should be observed, as most will improve spontaneously without surgery [5].
Bilateral pronator syndrome can be caused by an anomalous tendinous origin of the ulnar belly of the pronator teres muscle [6].
Damage to the innervation of the pronator quadratus muscle risks impairment of the initiation of hand pronation [7].
A patient with a very large neurilemmoma of the anterior interosseous nerve had no complaints and full flexion of the interphalangeal joint of the thumb and distal interphalangeal joint of the index finger one year after surgery [8].
Supercharged end-to-side anterior interosseous nerve to ulnar motor nerve transfer followed by multimodal hand therapy provides measurable improvements in neurophysiology and function [9].
Engagement in hand therapy and outcomes for supercharged end-to-side anterior interosseous nerve to ulnar motor nerve transfer appear to be mediated by comorbid physical and psychosocial health [9].
Median nerve compression neuropathy by the lacertus fibrosus represents a subgroup of median nerve neuropathies where the lacertus fibrosus is the sole cause of compression [10].
Patients who underwent cubital tunnel release and anterior interosseous nerve supercharge end-to-side transfer together had a significantly smaller cubital tunnel volume and cross-sectional area [11].
Compression of the median nerve at the elbow is a pathology that is often unrecognized and can be isolated or associated with carpal tunnel syndrome [12].
A patient with a nerve tumour causing anterior interosseous nerve palsy was able to return to work 3 months after surgery with increased pinch force and active interphalangeal joint motion of the thumb [4].

Anatomy & Pathophysiology¶

AIN Anatomy and Compression Sites¶

Near its site of origin, the anterior interosseous nerve is vulnerable to compression from tendinous attachments or accessory muscles [13].
Specific structures that can compress the AIN include tendinous origins of the deep head of pronator teres and of flexor digitorum superficialis to the middle finger [13].
Accessory structures described as causes of AIN compression include the attachment of flexor digitorum superficialis to flexor pollicis longus, an accessory head of the flexor pollicis longus muscle (Gantzer's muscle), a tendinous origin of the muscle variant palmaris profundus, and a double lacertus fibrosis [13].
Fractures at or around the elbow joint, direct injury to the nerve, and compression from plaster casts are recognized causes of anterior interosseous nerve syndrome [13].
Vascular causes of anterior interosseous nerve syndrome have been described by Spinner [13].
The AIN bifurcated at 3 cm (average) distal to the intercondylar line of the humerus in a report by Gunther and DiPasquale [15].
Constrictions associated with AIN palsy occur in the median nerve trunk of the upper arm, a location where the cause cannot be explained by a mechanical factor alone [15].
Structural factors, including nerve fascicles, must be considered before the onset of AIN palsy when constrictions occur in the median nerve trunk of the upper arm [15].
In patients with nontraumatic AIN palsy, the relationship between hemangiomas and intraneural topography matched the AIN in specific cases, suggesting the hemangioma as the cause of the palsy [15].
Intraepineurial constriction of nerve fascicles can be seen in pronator syndrome, similar to findings in AIN syndrome [15].

Pronator Syndrome Anatomy and Pathology¶

The pronator quadratus muscle is of importance for the initiation of hand pronation [7].
Damage to the innervation of the pronator quadratus muscle risks impairment of hand pronation initiation [7].
Median nerve compression at the elbow by the lacertus fibrosus is a pathology that can be isolated or associated with carpal tunnel syndrome [12].
Median nerve compression at the elbow by the lacertus fibrosus is a pathology often unrecognized where loss of muscle strength in the median nerve territory should evoke the diagnosis [17].
Patients representing a subgroup of median nerve neuropathies may have the lacertus fibrosus as the sole cause of compression [10].
Ultrasound examination findings may not lead to a diagnosis of pronator syndrome (LS) because median nerve compression in the forearm is often mild and may not produce positive US findings [16].

Clinical Presentation and Diagnostic Features¶

Anterior interosseous nerve syndrome is characterized by weakness of pinch between the thumb and index finger [13].
In AIN syndrome, the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger are hyperextended in the pinch position [13].
Weakness of the pronator quadratus muscle can be tested with the forearm flexed to neutralize 75% of pronator teres action [13].
Patients with AIN syndrome may complain of vague pain in the proximal forearm aggravated by exercise [13].
Pronator syndrome in violinists and anterior interosseous nerve syndrome with pure motor loss are distinct clinical observations [1].
If activities of daily living require frequent strong pronation and electromyography confirms compression, surgical decompression can be considered for pronator syndrome [1].
Other medical causes should be considered in AIN syndrome rather than immediate surgical decompression based solely on activity demands [1].

Elbow Anatomy Context¶

The flexor-pronator mass consists of the pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris, and flexor digitorum superficialis [23].
The medial epicondyle forms the attachment site for the origins of the flexor pronator mass [22].
The ligament of Struthers is a variant anatomy arising from the supracondylar process to attach to the medial epicondyle and is a potential site of median nerve compression [23].
The normal range of forearm pronation and supination is 75° and 85° respectively [19].
The normal range of forearm pronosupination is 80 to 85 degrees in each direction [28].
A functional arc for forearm rotation is 50 degrees [28].

Classification¶

Pronator syndrome is characterized by pain in the proximal forearm that is aggravated by exercise [13].
In anterior interosseous nerve syndrome, the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger are hyperextended during pinch [13].
Anterior interosseous nerve syndrome can be caused by compression from tendinous attachments or accessory muscles near the site of nerve origin [13].
Tendinous origins of the deep head of pronator teres and flexor digitorum superficialis to the middle finger are described causes of anterior interosseous nerve compression [13].
Accessory structures causing anterior interosseous nerve compression include the attachment of flexor digitorum superficialis to flexor pollicis longus [13].
An accessory head of the flexor pollicis longus muscle (Gantzer's muscle) is a described cause of anterior interosseous nerve compression [13].
A tendinous origin of the muscle variant palmaris profundus is a described cause of anterior interosseous nerve compression [13].
A double lacertus fibrosis is a described cause of anterior interosseous nerve compression [13].
Fractures at or around the elbow joint and direct injury to the nerve are causes of anterior interosseous nerve syndrome [13].
Compression from plaster casts is a recognized cause of anterior interosseous nerve syndrome [13].
Vascular causes have been described for anterior interosseous nerve syndrome [13].
Pronator syndrome can be caused by an anomalous tendinous origin of the ulnar belly of the pronator teres muscle [6].
Median nerve compression at the elbow by the lacertus fibrosus is a pathology that is often unrecognized [12].
Median nerve compression at the elbow by the lacertus fibrosus can be isolated or associated with carpal tunnel syndrome [12].
Patients with median nerve compression at the elbow by the lacertus fibrosus represent a subgroup of median nerve neuropathies where the lacertus fibrosus is the sole cause of compression [10].
Loss of muscle strength in the median nerve territory should prompt consideration of median nerve compression at the elbow [17].
Nontraumatic anterior interosseous nerve palsy can be associated with palsy of the pronator teres, flexor carpi radialis, and/or palmaris longus muscles [15].
Intraepineurial constriction of nerve fascicles can be observed in pronator syndrome [15].
The cause of hourglass constrictions associated with anterior interosseous nerve palsy in the median nerve trunk of the upper arm cannot be explained by a mechanical factor alone [15].
Structural factors, including nerve fascicles, must be considered before the onset of anterior interosseous nerve palsy when hourglass constrictions are present in the upper arm median nerve trunk [15].
The anterior interosseous nerve bifurcates at an average of 3 cm distal to the intercondylar line of the humerus [15].
Clinical signs and symptoms of spontaneous anterior interosseous nerve palsy with hourglass-like fascicular constriction are similar to those described for isolated neuritis [14].
Ultrasound examination findings may not lead to a diagnosis of pronator syndrome because median nerve compression in the forearm is often mild [16].

Clinical Presentation¶

AIN syndrome is characterized by weakness of pinch between the thumb and index finger [13].
Patients with AIN syndrome may complain of vague pain in the proximal forearm that is aggravated by exercise [13].
Pronator syndrome is associated with activities of daily living that require frequent strong pronation [1].
Electromyography findings are used to confirm the presence of compression in pronator syndrome [1].
Brachial plexus neuritis-induced anterior interosseous nerve palsy presents with clinical signs and symptoms similar to those described for isolated neuritis [14].
Nontraumatic AIN palsy may be accompanied by palsy of the pronator teres, flexor carpi radialis, and/or palmaris longus muscles [15].
Clinical findings in nontraumatic AIN palsy may be unassociated with high median nerve injury [15].
Ultrasound examination findings for median nerve compression in the forearm may not lead to a diagnosis of pronator syndrome because the compression is often mild [16].

Investigations¶

Clinical Presentation and Physical Examination¶

In anterior interosseous nerve syndrome, the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger are hyperextended in the pinch position [13].
Patients with anterior interosseous nerve syndrome may complain of vague pain in the proximal forearm that is aggravated by exercise [13].
Median nerve compression at the elbow is a pathology that is often unrecognized, where loss of muscle strength in the median nerve territory should evoke the diagnosis [17].
Median nerve compression at the elbow can be isolated or associated with carpal tunnel syndrome [12].
Patients with nontraumatic anterior interosseous nerve palsy may present with palsy of the pronator teres, flexor carpi radialis, and/or palmaris longus muscles [15].

Electrodiagnostic Studies¶

Electromyography findings can confirm the presence of compression in pronator syndrome [1].
Electromyography/nerve conduction velocity studies should be performed if any question about neurologic dysfunction exists [36].

Imaging¶

Ultrasonographic examination can be challenging for diagnosing median nerve compression in the forearm, as findings may not lead to diagnosis because compression is often mild and may not produce positive US findings [16].
Plain radiographs remain the hallmark and the best screening test for elbow evaluation [19].
CT is helpful when assessing for malunion architecture and the location and pattern of osteophytes and/or loose bodies [36].
MRI can be used to evaluate ligaments and tendons, but it is rarely indicated for elbow stiffness [36].
MRI may be most helpful in evaluating associated injuries including partial or complete tears of the medial collateral ligament in valgus extension overload syndrome [38].

Treatment¶

Non-Operative Management¶

Patients presenting with paresis of the anterior interosseous nerve should be observed, as most will improve spontaneously without surgery [5].
When the correct diagnosis is made, pronator syndrome can be successfully treated nonoperatively [2].

Operative Management¶

Surgical decompression can be considered for pronator syndrome if activities of daily living require frequent strong pronation and electromyography confirms the presence of compression [1].
When the correct diagnosis is made, pronator syndrome can be successfully treated surgically if necessary [2].
One year after surgery for a very large neurilemmoma of the anterior interosseous nerve, the patient had no complaints and full flexion of the interphalangeal joint of the thumb and distal interphalangeal joint of the index finger [8].
Engagement in hand therapy and outcomes after supercharged end-to-side anterior interosseous nerve to ulnar motor nerve transfer appear to be mediated by comorbid physical and psychosocial health [9].

Anatomical Considerations in Treatment¶

Tendinous origins of the deep head of pronator teres and of flexor digitorum superficialis to the middle finger are described as causes of anterior interosseous nerve compression [13].
Accessory structures described as causes of anterior interosseous nerve compression include the attachment of flexor digitorum superficialis to flexor pollicis longus, an accessory head of the flexor pollicis longus muscle (Gantzer's muscle), a tendinous origin of the muscle variant palmaris profundus, and a double lacertus fibrosis [13].
Compression from plaster casts has been recognized as a cause of anterior interosseous nerve syndrome [13].
The median nerve compression neuropathy by the lacertus fibrosus represents a subgroup of median nerve neuropathies where the lacertus fibrosus is the sole cause of compression [10].

Complications¶

Surgical decompression of the pronator quadratus muscle risks damage to its innervation, which is important for the initiation of hand pronation [7].
Compression of the anterior interosseous nerve can result from tendinous attachments or accessory muscles, including the deep head of pronator teres and flexor digitorum superficialis to the middle finger [13].
Accessory structures that can cause anterior interosseous nerve compression include the attachment of flexor digitorum superficialis to flexor pollicis longus, an accessory head of the flexor pollicis longus muscle (Gantzer's muscle), a tendinous origin of the palmaris profundus muscle variant, and a double lacertus fibrosis [13].
The cause of hourglass constrictions associated with anterior interosseous nerve palsy in the median nerve trunk of the upper arm cannot be explained by a mechanical factor alone and requires consideration of structural factors including nerve fascicles [15].

Recovery¶

Cases of brachial plexus neuritis-induced anterior interosseus nerve palsy should be managed conservatively [3].
Surgical decompression for pronator syndrome can be considered if activities of daily living require frequent strong pronation and electromyography confirms the presence of compression [1].
When the correct diagnosis is made, pronator syndrome can be successfully treated nonoperatively or surgically, if necessary [2].

Key Evidence¶

[L5] If the activities of daily living of a patient require frequent strong pronation, and if the electromyography findings confirm the presence of compression, surgical decompression can be considered against the background of pronator syndrome, whereas other medical causes should be considered in AIN syndrome. [1] (10.1177/17531934221080018)
[L5] When the correct diagnosis is made, pronator syndrome can be successfully treated nonoperatively or surgically, if necessary. [2] (10.1016/s0278-5919(05)70267-2)
[L5] Cases of brachial plexus neuritis-induced anterior interosseus nerve palsy should be managed conservatively, while surgical decompression may be performed for specific instances of direct trauma. [3] (10.1016/s0363-5023(97)80025-1)
[L5] The patient was able to return to work 3 months after surgery with increased pinch force and active interphalangeal joint motion of the thumb. [4] (10.1177/1753193412454801)
[L4] Patients presenting with paresis should be observed, as most will improve spontaneously without surgery. [5] (10.1016/s0363-5023(85)80240-9)
[L5] We report the case of a patient with bilateral pronator syndrome caused by an anomalous tendinous origin of the ulnar belly of the pronator teres muscle. [6] (10.1016/0363-5023(93)90373-b)
[L5] This risks damage of the innervation of this muscle of importance for initiation of hand pronation. [7] (10.1016/j.jhsb.2005.06.017)
[L5] One year later, the patient has no complaints and has full flexion of the interphalangeal joint of the thumb and D.I.P. joint of the index finger. [8] (10.1016/0266-7681(91)90141-a)
[L4] SETS AIN to ulnar motor nerve followed by multimodal hand therapy provides measurable improvements in neurophysiology and function, although engagement in hand therapy and outcomes appear to be mediated by comorbid physical and psychosocial health. [9] (10.1016/j.jht.2020.03.021)
[L4] The authors conclude that these patients represent a subgroup of median nerve neuropathies where the lacertus fibrosus is the sole cause of compression. [10] (10.1016/s0363-5023(86)80015-6)
[L4] Patients who underwent CuTR and AIN-SETS together had a significantly smaller cubital tunnel volume (CTV) and cross-sectional area (CSA). [11] (10.1016/j.otsr.2024.103982)
[L4] La compression du nerf médian au coude est une pathologie souvent méconnue qui peut être isolée ou associée à un syndrome du canal carpien. [12] (10.1016/j.hansur.2018.10.219)
[L5] [13] (10.1016/s0266-7681(05)80231-1)
[L4] The clinical signs and symptoms of these patients were similar to those described for isolated neuritis. [14] (10.1016/s0363-5023(96)80114-6)
[L4] [15] (10.1053/jhsu.2003.50021)
[L5] US examination can be challenging and its findings may not lead to diagnosis of LS, as median nerve compression in the forearm is often mild and may not produce positive US findings. [16] (10.1177/17531934251370272)
[L4] La compression du nerf médian au coude est une pathologie souvent méconnue où une perte de la force musculaire dans le territoire du nerf médian doit faire évoquer le diagnostic. [17] (10.1016/j.hansur.2019.10.044)

References¶

[1] Two clinical observations: pronator syndrome in violinists and anterior interosseous nerve syndrome with pure motor loss. Journal of Hand Surgery (European Volume). 2022. DOI: 10.1177/17531934221080018

[2] PRONATOR SYNDROME. Clinics in Sports Medicine. 2001. DOI: 10.1016/s0278-5919(05)70267-2

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[4] Nerve tumour as a rare cause of anterior interosseous nerve palsy. Journal of Hand Surgery (European Volume). 2012. DOI: 10.1177/1753193412454801

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[8] A Very Large Neurilemmoma of the Anterior Interosseous Nerve. Journal of Hand Surgery. 1991. DOI: 10.1016/0266-7681(91)90141-a

[9] Postoperative management and rehabilitation after the supercharged end-to-side anterior interosseous nerve to ulnar motor nerve transfer: A report of 3 cases. Journal of Hand Therapy. 2021. DOI: 10.1016/j.jht.2020.03.021

[10] Median nerve compression neuropathy by the lacertus fibrosus: Report of three cases. The Journal of Hand Surgery. 1986. DOI: 10.1016/s0363-5023(86)80015-6

[11] Morphological characteristics of the cubital tunnel as indication for anterior interosseous nerve supercharge end-to-side transfer in treating advanced cubital tunnel syndrome. Orthopaedics & Traumatology: Surgery & Research. 2025. DOI: 10.1016/j.otsr.2024.103982

[12] Diagnostic et traitement chirurgical de la compression du nerf médian au coude par section isolée du lacertus fibrosus. À propos de 13 cas. Hand Surgery and Rehabilitation. 2018. DOI: 10.1016/j.hansur.2018.10.219

[13] An Anomaly of the Median Artery Associated with the Anterior Interosseous Nerve Syndrome. Journal of Hand Surgery. 1992. DOI: 10.1016/s0266-7681(05)80231-1

[14] Spontaneous anterior interosseous nerve palsy with hourglass-like fascicular constriction within the main trunk of the median nerve. The Journal of Hand Surgery. 1996. DOI: 10.1016/s0363-5023(96)80114-6

[15] Fascicular torsion in the median nerve within the distal third of the upper arm: Three cases of nontraumatic anterior interosseous nerve palsy. The Journal of Hand Surgery. 2003. DOI: 10.1053/jhsu.2003.50021

[16] Re: Fang J, Zhang LQ, Tang JB. Incidence of local tenderness at the lacertus fibrosus in healthy people. Journal of Hand Surgery (European Volume). 2025. DOI: 10.1177/17531934251370272

[17] Compression du nerf médian au coude par le lacertus fibrosus : à propos de 34 cas. Hand Surgery and Rehabilitation. 2019. DOI: 10.1016/j.hansur.2019.10.044

[19] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. Anatomy, Biomechanics, Physical Examination, and Imaging of the Elbow > Summary and Conclusions.

[22] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. Anatomy, Biomechanics, Physical Examination, and Imaging of the Elbow > Anatomy > Bony Anatomy.

[23] Miller S Review Of Orthopaedics. SECTION 16 PATELLAR TRACKING IN TOTAL KNEE ARTHROPLASTY > TABLE 2.3 Shoulder Spaces.

[28] Miller S Review Of Orthopaedics. ELBOW.

[36] Aaos Comprehensive Orthopaedic Review 3. Elbow Stiffness* > IV. Evaluation.

[38] Aaos Comprehensive Orthopaedic Review 3. Elbow Injuries in the Athlete* > III. Valgus Extension Overload Syndrome and Posterior Impingement.

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