Pediatrik tetik parmak nedeni olarak, tendonun miksoid dejenerasyonu

Pediatrik tetik parmak klinik uygulamada nadiren gorulur ve goruldugunde cogunlukla tetik basparmak olarak ortaya cikar. Tetik parmak tanisiyla ameliyat edilen 12 yasindaki bir cocugun sol el ucuncu parmaginin yuzeysel fleksor tendonundaki nodul icerisinde miksoid dejenerasyon tespit edildi. Bu dejenerasyon cerrahi olarak cikartildiktan sonra hastanin agrisinin ve takilmasinin gectigi goruldu. Bu olguyu sunma amacimiz, vakamizda oldugu gibi tendonun miksoid dejenerasyonu ve tumorler gibi nadir gorulen patolojilerin, cogu cerrahi gerektiren, cocuk tetik parmak nedeni olabilecegini hatirlatmaktir.


INTRODUCTION
Pediatric trigger finger (TF) is a rare condition, which is ten times less common than pediatric trigger thumb [1,2].The cause is unknown but anatomic variations are claimed to be responsible and although those exist from birth, the entity occurs in the following years [3].If there is no anatomic pre-disposing factor, rarer conditions that increase the contents of the sheath can cause pediatric TF.These include inflammatory synovitis of rheumatoid arthritis, post traumatic calcific tendonitis or deposition of muccopolysaccharide in Hurler's syndrome, etc. [1,2].We report an unusual cause of pediatric TF myxoid degeneration of the tendon.

CASE
A twelve year-old male patient with triggering of the third finger on left side for one year admitted to our outpatients clinic.He had no accompanying dis-eases or history of trauma.The triggering occurred especially in the morning and decreased during the day time.It caused pain and relieved spontaneously.
In the examination, the finger was locked in flexion and while extending there were two clicks.A painful nodule was palpated on the volar aspect of third metacarpophalangeal joint.
In the operation, the A1 pulley seemed normal, after dividing it decussating of superficial flexor tendon proximal to A1 pulley and a wider ulnar slip were seen.The ulnar slip was three times wider than the radial one (Figure 1).After a longitudinal incision a yellowish mass was seen in the deeper part of the tendon and it was excised (Figure 1).There were no triggering after this point and the operation ended.
Pathological examination of the mass revealed myxoid degeneration of the tendon which is unusual as a cause pediatric TF (Figure 2).The patient is free of pain and triggering after the operation.

DISCUSSION
Trigger thumbs constitute 90% of pediatric trigger digits [2].It is a rare condition which usually occurs in children aged <8 years [4] and affects less than 0.05% of children [2].Unlike pediatric trigger thumb it usually does not resolve with time and requires surgery.It is still controversial regarding the congenital versus acquired nature of pediatric trigger thumbs and the rate of spontaneous resolution [4].
Many factors are listed as the cause; anatomical abnormalities, thickened tendons and tendon sheaths, trauma (partial laceration of FDS tendon), tumors and lesions within the flexor apparatus, viral infections, some metabolic disorders such as type 1 diabetes mellitus and mucopolysaccharidosis, inflammatory diseases such as juvenile rheumatoid arthritis [1,3,4].Reported abnormalities included a more proximal than normal decussation of the FDS, a slip of FDS that inserted into the FDP tendon, nodules in the tendon, and a stenotic A-3 pulley [1,2] .
We present a case with an unexpected cause; myxoid degeneration of the tendon.We believe that the degeneration of the tendon is a result of proximal decussation of flexor digitorum superficialis tendon.Although some authors recommended conservative treatment and reported spontaneous recovery [2,5], unlike the adult TF, surgical treatment of pediatric TF may need a more extensile approach thorough a Bruner incision [1,6].In our case there was not any need for extensile approach as triggering relieved after excision of the mass and pulley release.
Despite pediatric TF is about one tenth as common as trigger thumb, it needs a thorough understanding and assessment as it may have a wide range of etiology with most of them requiring surgery.

Figure 1 .Figure 2 .
Figure 1.Radial part of FDS tendon is in normal size but the ulnar part of the tendon is enlarged and contains a lipoid mass which later shown to be myxoid degeneration of the tendon