Page 763 - Adams and Stashak's Lameness in Horses, 7th Edition

Lameness of the Proximal Limb 729

that the prognosis was relatively lower for Quarter The latest technique being advocated for treatment of
25
horses compared with other breeds. Sandler et al. SCL is placement of a screw across the cyst. In a retro-
VetBooks.ir racing raced after debridement of the SCL. However, imately 75% of horses responded successfully to the
spective study, Santschi et al. demonstrated that approx-
showed that 77% of 150 Thoroughbreds intended for
procedure. Of note in this study is a reduced prognosis
horses in which more than 15 mm of the surface of the
51
joint was involved had a reduced prognosis compared in horses older than 3 years, similar to other studies.
with those with less than 15 mm. Therefore, it appears
49
that the depth of the cyst is of little importance in the Prognosis
prognosis but the percent of joint surface involved is
important (Figure 5.129). Overall, 56%–77% of horses returned to their
An osteochondritis dissecans (OCD) lesion may be intended use with surgery for SCL of the medial femoral
present at the cyst opening and require debridement condyle. A couple of studies have now demonstrated the
at the time of surgery. Smith et al. showed that reduced rate of return to work for horses over 3 years of
25
horses older than 3 years had a dramatically lower age, regardless of treatment, and this should be taken
chance of soundness and return to work than horses into consideration when treatment options are given.
54
3 years and younger. This study also confirmed that The limited work in tibial cysts has shown that in horses
the presence of articular cartilage lesions within the younger than 2 years, 3 out of 4 returned to work. Older
MFT joint remote to the site of the SCL negatively horses with tibial SCLs had reduced work. The progno-
impacted the prognosis. In addition to age and other sis was poor for those with lesions in the caudal aspect
articular lesions, SCL enlargement and damage to of the joint in which access was limited.
25
the menisci and/or meniscal ligament can further
reduce prognosis. FRACTURES
Some have advocated bone grafting to facilitate repair
and filling in the bony defect. However, the prognosis is Etiology
really no different than debridement. Others have
26
advocated the use of some form of bone graft (cancellous Intra‐articular fractures of the stifle usually are due to
bone graft, tricalcium phosphate, or hydroxyapatite) acute trauma from internal forces as it is uncommon to
with an overlay of fibrin, growth factors, and chondro- see these problems in horses with outward signs of exter-
cytes or stem cells to improve the prognosis. 19,33 nal trauma. They likely occur with rotation and may
SCLs of the tibia that occur laterally can be involve an avulsion fracture, usually of the intercondylar
approached with an arthroscope and are typically eminence of the tibia. However, the cruciate ligament
beneath the cranial ligament of the lateral meniscus. insertion is typically lateral to the common site of frac-
They too can be debrided. However, in some lesions, ture, and many fragments do not involve the liga-
48,61
especially those involving the medial tibial condyle of ment. Intra‐articular fractures of the femorotibial
older horses, an extra‐articular approach may be joints are rare, and horses with medial intercondylar
required for debridement. 56 eminence (MICET) fractures commonly have a history
Some surgeons advocate intralesional steroid ther- of acute lameness and traumatic event. It is hypothesized
apy for treating SCLs. Based on the work of von that fractures of the MICET are due to lateral movement
61
Rechenberg et al., in which they showed the presence of of medial femoral condyle against the MICET.
inflammatory mediators within the cyst lining, this
treatment makes sense. However, it is important to Clinical Signs
45
inject corticosteroids into the cystic lining and not just Horses typically present with significant acute lame-
into the depths of the cyst. Cyst injection is best facili- ness, often with significant synovial effusion and joint
tated by an arthroscopic approach so that concurrent capsule swelling. They may or may not be painful on
60
articular cartilage lesions can be debrided if necessary, palpation, and they often show an outward rotation of
and successful injection is often demonstrated by the the distal limb when standing. Horses are typically very
extrusion of fibrinous material from the cyst. However, painful to flexion, both passively and with movement.
injection of the lesion can be done with ultrasound Horses with tibial tuberosity fractures can be painful on
guidance of a needle into the cystic material. In the palpation of the area and are mentioned here because
author’s opinion, this technique is more difficult in concurrent damage to the soft tissues of the femorotibial
assuring that the lining itself is actually being injected. joints has been reported with this fracture. 2
Triamcinolone acetonide (10–30 mg/cyst) or methyl-
prednisolone acetate (40–80 mg/cyst) or both are typi- Diagnosis and Imaging
cally injected into the SCL. These horses are rested
postoperatively and re‐radiographed after 2 months, at Radiographs typically demonstrate the presence of
which time clinical signs often improve and the horses fractures. They can occur on the caudal aspect of the
can be put into light work. medial femoral condyle (Figure 5.130A), 10,21 caudal
Wallis et al. showed that this technique was success- aspect of the medial tibial condyle, intercondylar emi-
ful in 67% of horses and 77% of cysts. There was no nence (Figure 5.130B and C), 37,61 Salter–Harris type III
60
20
significant influence of age, 90% of horses that had uni- fracture of the lateral condyle, Salter–Harris type IV
20
lateral cysts were successful vs. 67% that were affected fracture of the distal femoral physis, or the origin of
bilaterally, and the presence of osteophytes within the the long digital extensor muscle (Figure 5.131) or per-
MFT joint reduced the success to 63% vs. 87% for those oneus tertius muscle 6,24 and as loose fragments within
without. the lateral femorotibial joint. 55