PMC8324369_01
Timeline from CCLD to the diagnosis of PT injury. After postoperative recovery for five days, sheep were given unrestricted mobility in a dry lot for 74 days and received comprehensive orthopedic exams at day 87 after CCLD.
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PMC8324369_02_CRIVEM2021-2628791.001.jpg
fig1
Upon recovery, sheep were housed in groups of two to three in 8 ft.x10 ft. indoor pens bedded in straw for five days then moved to a large dry lot with free mobility (Figure 1).
Normal antemortem stifle flexion compared to that of a sheep with an injured peroneus tertius. Damage to the PT in six out of eight sheep that underwent CCLD for use in a gene therapy study was suspected based on clinical signs (b) when compared to healthy unaffected sheep (a).
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fig2
This anatomy results in coordinated movement in unison between the hock and stifle joints when the PT is intact (Figure 2(a)). Extension was possible in the hock joint while the stifle was simultaneously held in flexion (Figure 2(b)).
PMC8324369_02
Timeline from CCLD to the diagnosis of PT injury. After postoperative recovery for five days, sheep were given unrestricted mobility in a dry lot for 74 days and received comprehensive orthopedic exams at day 87 after CCLD.
CRIVEM2021-2628791.001.jpg
PMC8324369_02_CRIVEM2021-2628791.001.jpg
fig1
Upon recovery, sheep were housed in groups of two to three in 8 ft.x10 ft. indoor pens bedded in straw for five days then moved to a large dry lot with free mobility (Figure 1).
Normal antemortem stifle flexion compared to that of a sheep with an injured peroneus tertius. Damage to the PT in six out of eight sheep that underwent CCLD for use in a gene therapy study was suspected based on clinical signs (b) when compared to healthy unaffected sheep (a).
CRIVEM2021-2628791.002.jpg
PMC8324369_02_CRIVEM2021-2628791.002.jpg
fig2
This anatomy results in coordinated movement in unison between the hock and stifle joints when the PT is intact (Figure 2(a)). Extension was possible in the hock joint while the stifle was simultaneously held in flexion (Figure 2(b)).
After CCLD, sheep were subjected to oblique angle forced exercise by treadmill for the exacerbation of osteoarthritis as part of a novel gene therapy study.
CRIVEM2021-2628791.003.jpg
PMC8324369_02_CRIVEM2021-2628791.003.jpg
fig3
Gross changes in the peroneus tertius. Damage to the PT in six out of eight sheep that underwent CCLD was confirmed via postmortem dissection when compared to healthy unaffected sheep ((a) intact and (b) disrupted). Gross structural changes can also be seen when comparing an intact proximal PT tendon (c) to a damaged proximal PT tendon (d). This may lead to variable joint stability between test subjects.
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PMC8324369_02_CRIVEM2021-2628791.004.jpg
fig4
PT muscle and tendons (Figures 4(a) and 4(c)) were grossly compared to affected sheep (Figures 4(b) and 4(d)) to determine the location and extent of the tissue damage. Proximal and distal PT tendons were transected where they entered the stifle joint capsule and hock, respectively, and percent change in muscle belly length was measured between affected and intact PT muscles. Soft tissue evaluation during pelvic limb dissection revealed that the PT tendons were approximately 40 to 50% smaller in diameter and had a tan color in the AL (Figures 4(c) and 4(d)). While the muscle belly and tendon remained intact, the proximal PT tendon was stretched or displaced distally approximately 15 to 20% of the original length such that the PT muscle belly of the AL was only 80 to 85% the length of an unaffected PT (Figures 4(a) and 4(b)).