surgical management of non septic carpal tenosynovitis

SURGICAL MANAGEMENT OF NON SEPTIC CARPAL TENOSYNOVITIS
Ian Wright MA VetMB DEO DECVS MRCVS
Newmarket Equine Hospital, Newmarket, United Kingdom
The presentation is based on the author’s experiences with the diagnostic and surgical
tenoscopy of the carpal sheath of the digital flexor tendons (carpal sheath). This has expanded
the list of differential diagnoses associated with tenosynovitis of the carpal sheath and, when
correlated with the diagnostic imaging has led to the development of good levels of nonsurgical/pre-operative assessment of clinical cases. Endoscopic evaluation and understanding
of tissue damage also permit rational intervention. Findings have been published in a recent
series of papers 1,2,3,4 and the data will be updated to include cases detailed in Table 1. The
majority (91/105) involved Thoroughbred horses in race training.
Lesion
Horses
Osteochondromata
37
Torn radial head DDFT
24
Intrathecal disruption of the ALSDF
14
Fractured accessory carpal bone
11
Torn DDFT
3
Torn SDFT
2
Combination injuries
6
Ruptured sheath wall
1
Torn carpal retinaculum
1
Infection
5
Neoplasia
1
Table 1: Endoscopic surgery of the carpal sheath of the digital flexor tendons in 105 horses
(2005-2013)
Caudal distal radial osteochondromata are a common developmental anomaly in young
racing Thoroughbreds but are also identified in other horses. The most plausible aetiology is
aberrant translocation of physeal chondrocytes. The majority occur in the mediolateral middle
one third of the metaphysis. Lesion morphology is viable. Clinical signs result from
impingement on the deep digital flexor tendon (Figure 1) and subsequent synovitis; both are
unrelated to the size of the osteochondroma. Tenoscopic removal of the osteochondroma and
torn tendon tissue carries a good prognosis for working soundness including return to training
and racing. Recurrence is rare.
Figure
1A:
Tenoscopic
appearance of an osteochondroma
(O)
Figure 1B: Laceration (arrows)
of deep digital flexor tendon
(DDFT) caused by, but distal to,
the osteochondroma shown in A
R = Radius
Tears of the radial head of the deep digital flexor appeared to be avulsions from the
principal (conjoined humeral and ulnar) tendon. Lameness is usually mild to moderate.
Distension of the carpal sheath is consistent but of variable degree. Ultrasonographic
predictability is good (Figure 2). Tenoscopic removal of the torn and extruded tissue carries a
good prognosis for training and racing.
A
B
Figure 2: Transverse ultrasonograph (A) and tenoscopy (B) of a torn (arrows) radial
head (RH) of the DDF (DDF).
R = caudal surface of radius; DDFT = deep digital flexor tendon
Tearing of the accessory ligament of the superficial digital flexor (ALSDF) can be
intrathecal with respect of the carpal sheath and frequently results in intrasynovial
haemorrhage. Tears are usually in the caudal portion of the ALSDF and commonly extend to
the median neurovascular bundle. They can be identified by multi-modal ultrasonography
which also assesses proximity to the median artery (Figure 3).
A
B
Figure 3A: Transverse ultrasonograph
illustrating an intrathecal tear of the
ALSDF (arrows).
ALSDF = Accessory ligament of
superficial digital flexor
DDFT= deep digital flexor tendon
SDFT = Superficial digital flexor
tendon
Figure 3B: Tenoscopic appearance
of the torn ALSDF (arrows) seen in
A. DDFT = deep digital flexor
tendon
Tenoscopically, most are identified medially adjacent to the cranial margin of the deep
digital flexor tendon but some are identified caudally between the deep and superficial digital
flexor tendons protruding through the common mesotenon or medial to the superficial digital
flexor tendon. Tears can be extensive and frequently involve the full lateromedial thickness of
the ligament. In most cases ligament disruption extends beyond the zone of extruded torn
fibrils with further recoiled ligament exposed as tissue is removed. Tenoscopic removal of torn
tissue must be performed judiciously to avoid traumatising the median artery and nerve.
Current results suggest a guarded prognosis for racing but a more favourable outlook for other
pursuits.
Complete displaced frontal plane fractures of the accessory carpal bone frequently
communicate with the carpal sheath. Comminuted fragments can displace distally within the
sheath or abaxially to an extrathecal location. The fracture margins and/or fragments
commonly traumatised the lateral margin of the deep digital flexor tendon. This can be
detected ultrasonographically. Fractures are partially reduced by carpal extension but this
results in protrusion of fragments and/or sharp margins into the deep digital flexor tendon
(Figure 4). Tenoscopic removal of these and debridement of lacerated tendon are considered
contributory to cases management.
A
B
C
Figure 4: Tenoscopic images of a longstanding frontal plane fracture of the accessory carpal
bone.
(A with carpus flexed and (B extended illustrating closure of the fracture gap (arrows) and
protrusion of the palmar fragment (F) to lacerate the deep digital flexor tendon (DDFT).
C) Tenoscopic appearance following removal of the protruding portion of the fragment (F) and
debridement of the DDFT
References
Minshall GJ, and Wright IM: Tenosynovitis of the carpal sheath of the digital flexor tendons
with tears of the radial head of the deep digital flexor. Observations in 11 horses. Equine Vet J
2012; 44: 76-80
Wright IM, and Minshall GJ: Clinical radiological and ultrasonographic features, treatment and
outcome in 22 horses with caudal distal and radial ostechondromata. Equine Vet J 2012; 44:
319-324
Minshall GJ, and Wright IM: Diagnosis and treatment of intrathecal tears of the accessory
ligament of the superficial digital flexor. Equine Vet J 2014; early review
DOI: 10.1111/evj.12240
Minshall GJ, and Wright IM: Frontal plane fractures of the accessory carpal bone and
implications for the carpal sheath of the digital flexor tendons. Equine Vet J 2014; early review
DOI: 10.1111/evj.12203

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