Constriction of the fetlock annular ligament: relationship between clinical and histopathological findings

Abstract

Stenosis or constriction of the fetlock annular ligament (FAL) has been diagnosed in 92 limbs of 85 horses, which have been subsequently submitted to FAL desmotomy. A previous clinical examination, including radiographic and ultrasonographic imaging, as well as synovial fluid analysis when needed, allowed a new classification of the constriction based on clinical findings: Type 1 (primary stenosis of FAL usually associated with synovial effusion of the tendon sheath); Type 2a (stenosis of the FAL secondary to tendinitis of the superficial or deep digital flexor tendon); Type 2b (stenosis of the FAL following a previously healed tendinitis with secondary thickening of the synovial membrane of the tendon sheath and subcutaneous tissue); Type 3 (stenosis of the FAL secondary to septic tenosynovitis). Type 1 included 40 cases (42 limbs); Type 2a 21 cases (26 limbs); Type 2b 17 cases (17 limbs) and Type 3 7 cases (7 limbs). In 29 cases a sample of the FAL was taken during surgery and subrnitted for histological examination. A further classification was made, based on histological findings, and samples were divided into 3 different groups. In group A the FAL, the synovial membrane and subcutaneous tissue appeared thickened, with irregular distribution of collagen fibres, increased number of desmocytes, lack of reticular fibres, and moderate angiogenesis. Most of the cases that were clinically classified as Type 1 , Type 2a and Type 2b were included in group A. Group B was characterised by similar findings, but by the additional presence of inflammatory cells like lymphocytes and granulocytes. A small number of cases clinically classified as Type 1 and Type 2awere included into group B. In group C, a marked infiltration of inflammatory cells (lymphocytes and neutrophils) and, in more recent cases, the presence of fibrin were the dominant feature. All cases classified in Group C were clinically assigned to Type 3. The histologic examination supported the diagnosis of ,,desmitis" rn cases belonging to the groups B and C, wheras cases included in group A showed only thickening of the FAL without signs of inflammation. keywords: annular ligament, constriction, desmitis, fetlock, horse Striktur des Fesselbeinringbandes: Beziehung zwischen klinischen und histopathologischen Befunden Eine Stenose oder Striktur des Fesselringbandes (RB) wurde in 92 Gliedmaßen von 85 Pferden diagnostiziert. Diese Pferde wurden anschließend einer Desmotomie des Ringbandes untezogen. Eine vorausgehende klinische Untersuchung, die eine Röntgenund Ultraschalluntersuchung und falls notwendig eine Prüfung der Synovialflüssigkeit mit einschloß, erlaubte eine neue Klassifizierung der Striktur, die auf klinischen Befunden beruht: Typ 1 (primäre Stenose des RB, gewöhnlich begleitet von vermehrter Synovialfüllung der Sehnenscheide); Typ 2a (Stenose des RB sekundär nach Tendinitis der oberflächlichen oder tiefen Beugesehne); Typ 2b (Stenose des RB nach zuvor ausgeheilter Tendinitis mit sekundärer Verdickung der Synovialmembran der Sehnenscheide und des Unte...

Retrospective study of palmar/plantar annular ligament injury in 71 horses: 2001–2006

“…Histology of sections of the PAL acquired at surgery at the AHT have confirmed previous observations (van den Berg et al 1995;Torre et al 1998) that active inflammation is rarely present in this condition (S. Dyson, unpublished data). Abnormalities of the PAL include: irregular collagen bundle alignment, varying amounts of fibroplasia, vascular hypertrophy, lack of reticular fibres and variable lymphocyte/granulocyte infiltration.…”

“…It is characterised by constriction of an enlarged DFTS and its contents by a relatively normal PAL, resulting in restriction of the free movement of the flexor tendons within the fetlock canal. An increase in volume within the DFTS may be due to injury of the flexor tendons, manica flexoria or tenosynovitis (Dik et al 1995;Torre et al 1998;Wilderjans et al 2003;Smith and Wright 2006). Its classical presentation is persistent lameness associated with a characteristic concave notch at the level of the PAL (Gerring and Webbon 1984;Schramme and Smith 2003), with the DFTS bulging proximally.…”

Equine non‐septic tenosynovitis: A systematic literature review of site‐specific pathological lesions, outcomes and surgical complications

“…94 Five of 85 (6%) studies examined multiple tendon sheaths within the same publication, including digital flexor, carpal flexor, tarsal flexor and carpal extensor sheaths. 12,76,[96][97][98] There were 2449 structures affected by non-septic tenosynovitis [1][2][3][4][5][6][8][9][10][11][12][15][16][17][18]21,23,24,26,27,[29][30][31]33,36, : 1393/2449 (57%) included the digital flexor sheath, 1,2,6,8,9,[15][16][17][18][29][30][31]33,[39][40][41][42][43][45][46]…”

“…[1][2][3][4]6,8,9,[15][16][17][18]21,23,27,[29][30][31]33,95 There were 75/1303 (0.6%) horses diagnosed with bilateral digital flexor sheath tenosynovitis. 1,2,4,21,27,29,31,41,42,46,50,51,56 It is not known how many of these bilateral cases were forelimb versus hindlimb cases. 5,10,26,[61][62][63][64][65][66][67][68][69][70]99 There were 286/639 (45%) horses diagnosed with bilateral carpal flexor tenosynovitis.…”

“…313/1350 (23%), 1,2,4,16,27,30,44,[46][47][48]50,56,95 lesions of the superficial digital flexor tendon: 160/1350 (12%), 1,6,16,27,[29][30][31]42,47,48,51,53,95 and adhesions: 158/1, 350 (12%). [1][2][3][4]6,17,18,21,23,27,29,30,36,42,47,49,51,58 Other deep digital flexor tendon pathological lesions reported included tendonitis: 14/1350 (1%) 6,15,16,18,30,31,36,41,…”