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Medial Patellar Desrnotorny 79
2. Adams SB, Fessler JF: Medial patellar desrnotomy.
COMMENTS In Adams SB, Fessler JF, editors: Atlas of equine
surgery, Philadelphia, 2000, WB Saunders.
In a horse with upward patellar fixation, the limb 3. Jansson N: Treatment for upward fixation of tl1e
is positioned with the stifle and hock held in patella i11 the horse by medial patellar desmotorny
extension with the distal limb held iI1 partial indications and complications. Equine Pract 18:24,
flexion (see Figure 12-1). Release of the limb often 1996.
occurs with a quick and exaggerated flexion (see 4. Walmsley JP: The stifle. In Ross MW, Dyson SJ,
Figure 12-3). Three situations have been editors: Diagnosis and management of lameness in
described.2 Persistent fixation occurs when the the horse, Philadelphia, 2003, WB Saunders.
patella remains fixed for a prolonged period of 5. Bathe AP, O'Hara LK: A retrospective study of the
outcome of medial patellar ligament desmotomy in
time, often requiring assistance or multiple 49 horses, Proc Am Assoc Equine Pract 50:476, 2004.
attempts by the horse to release the patella. Inter- 6. Gibson K, Mcilwraith CW, Parks RD, et al:
mittent fixation occurs when the patella remains Production of patellar lesions by medial patellar
fixed with the limb held in extension behind the desmotomy in normal horses, Vet Surg 18:466,
horse for several seconds and then is released 1989.
during a normal step. Momentary fixation occurs 7. Mcllwraith CW: Osteochondral fragmentation of
•
when the patella temporarily fixes, causing a slight the distal aspect of the patella in horses, Equine Vet
delay in the start of protraction and a slightly J 22:157, 1990.
exaggerated flexion when the limb is released. 8. Riley CB, Yovich JV: Fracture of the apex of the
Conservative therapy should always be patella after medial patellar desmotomy i11 a horse,
Aust Vet J 68:37, 1991.
attempted before surgical correction of upward 9. Dyson SJ: Patellar injuries. In White NA, Moore JN
patellar fixation. Most cases of intermittent up- editors: Current techniques in equine surgery and
ward patellar fixation occur in young horses lameness, Philadelphia, 1998, WB Saunders.
with poor quadriceps condition or i11 l1orses that 10. Wright I: Ligaments associated with joints, Vet Clin
have had a period of extended stall rest. These N Am Equine Pract 11:249, 1995.
horses often respond to an exercise program that 11. Tribnar MA: Medial patellar ligament splitting for
increases the strength of the quadriceps and sur- the treatment of upward fixation of the patella in 7
rounding musculature. Cases that are candidates equids, Vet Surg 31 :462, 2002.
for surgery have intermittent upward patellar fix- 12. Brown M: The effects of an injection of counterir-
ation despite adequate conditioning programs or ritant into the patellar ligament of ponies: applica-
have persistent locking that cannot be manually tion to stifle lameness, J Equin.e Vet Sci 3:149, 1983.
released or recurs after release. 2,4,6• 14 13. van Hoogmoed LM, Agnew DW, Whitcomb MB, et
al: Ultrasonographic and histologic evaluation of
Although most cases of upward patellar medial and middle patellar ligaments in exercised
fixation are primary, upward patellar fixation horses following injections with ethanolamine
can occur secondary to neurologic disease and to oleate and 20/o iodine in almond oil, .AJn J Vet Res
stifle pathology and in horses with coxofemoral 63:738, 2002.
joint luxation.v'"!' If necessary, these conditions 14. Sullins KE: Lameness. Part XII. The stifle. In Stashak
should be ruled out before performing surgery. TS, editor: Adam's lameness in horses, Philadelphia,
Because of possible fragmentation of the distal 2002, Lippincott Williams and Wilkins.
patella and middle patellar ligament desmitis after 15. Black JB: The Western performance horse. In Ross
desmotomy, the amount of postoperative rest has MW, Dyson SJ, editors: Diagnosis and management
been increased. The optimum rest period for of lameness in the horse, Philadelphia, 2003, WB
Saunders.
healing is not known. Current recommendations 16. Walmsley JP: Medial desmotomy for upward fixa-
vary and include 4 to 6 weeks if no signs of lame-
tion of the patella, Equine Vet Educ 6:148, 1994.
ness are present," 2 to 3 months.v" 2 to 5 months,4 17. Clegg PD, Butson RJ: Treatment of coxofemoral
and 4 to 5 months." joint luxation secondary to upward fixation of
the patella in a Shetland pony, Vet Rec 138:134,
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