Influence of methylprednisolone acetate on osteochondral healing in exercised tarsocrural joints of horses

B. G. Carter From the Orthopedic Research Laboratory, Departments of Veterinary Clinical Sciences (Carter, Bertone, Bailey, Palmer) and Veterinary Pathobiology (Weisbrode, Andrews), The Ohio State University, 601 Vernon L. Tharp Street, Columbus, OH 43210.

Search for other papers by B. G. Carter in
Current site
Google Scholar
PubMed
Close
 DVM
,
A. L. Bertone From the Orthopedic Research Laboratory, Departments of Veterinary Clinical Sciences (Carter, Bertone, Bailey, Palmer) and Veterinary Pathobiology (Weisbrode, Andrews), The Ohio State University, 601 Vernon L. Tharp Street, Columbus, OH 43210.

Search for other papers by A. L. Bertone in
Current site
Google Scholar
PubMed
Close
 DVM, PhD
,
S. E. Weisbrode From the Orthopedic Research Laboratory, Departments of Veterinary Clinical Sciences (Carter, Bertone, Bailey, Palmer) and Veterinary Pathobiology (Weisbrode, Andrews), The Ohio State University, 601 Vernon L. Tharp Street, Columbus, OH 43210.

Search for other papers by S. E. Weisbrode in
Current site
Google Scholar
PubMed
Close
 VMD, PhD
,
M. Q. Bailey From the Orthopedic Research Laboratory, Departments of Veterinary Clinical Sciences (Carter, Bertone, Bailey, Palmer) and Veterinary Pathobiology (Weisbrode, Andrews), The Ohio State University, 601 Vernon L. Tharp Street, Columbus, OH 43210.

Search for other papers by M. Q. Bailey in
Current site
Google Scholar
PubMed
Close
 DVM, MS
,
J. M. Andrews From the Orthopedic Research Laboratory, Departments of Veterinary Clinical Sciences (Carter, Bertone, Bailey, Palmer) and Veterinary Pathobiology (Weisbrode, Andrews), The Ohio State University, 601 Vernon L. Tharp Street, Columbus, OH 43210.

Search for other papers by J. M. Andrews in
Current site
Google Scholar
PubMed
Close
 DVM
, and
J. L. Palmer From the Orthopedic Research Laboratory, Departments of Veterinary Clinical Sciences (Carter, Bertone, Bailey, Palmer) and Veterinary Pathobiology (Weisbrode, Andrews), The Ohio State University, 601 Vernon L. Tharp Street, Columbus, OH 43210.

Search for other papers by J. L. Palmer in
Current site
Google Scholar
PubMed
Close
 DVM, MS

Abstract

Objective

To evaluate joint function and healing of surgically created full-thickness articular cartilage defects in exercised horses after intra-articular administration of methylprednisolone acetate (MPA; 120 mg) and sterile saline solution in the contralateral limb.

Design

Experimental investigation.

Sample Population

12 healthy, sound, radiographically normal horses with induced full-thickness osteochondral lesions on the medial and lateral trochlear ridges of the tali.

Procedure

Two 8.4-mm-diameter full-thickness articular cartilage lesions were created in each tarsocrural joint (12 horses [24 tarsocrural joints]); 1 was in a weight-bearing (WB) position and the other in a less weight-bearing (LWB) position. Each horse was maintained on a standardized exercise protocol (stall rest, days 0-6; walking, days 7-12; and treadmill, days 13-42) and evaluated throughout the study for changes in joint circumferences, synovial fluid, radiographs, lameness, and scintigraphy. 6 horses were euthanatized on day 42, and 6 on day 180.

Gross morphometric assessment was performed, using an image analysis system on a projected color slide of the defect. The type of repair tissue, based on gross appearance, was expressed as a percentage of the total defect for each osteochondral defect. Histochemical assessment was performed, using safranin-O staining for proteoglycans and an image analysis system to express the area of stain uptake. Histomorphometric assessment was performed on H&E-stamed sections, using an image analysis system. The repair tissue filling the defect was categorized as to tissue type and expressed as a percentage of the total defect area. Synovial membrane specimens were assessed semiquantitatively on H&E-stained sections for changes in character. Significance was established at P < 0.05.

Results

Joint circumference was significantly increased in the saline, compared with the MPA-treated, limbs on days 7, 12, and 42. Synovial fluid WBC counts were significantly increased in the MPA-treated limbs on day 42. Gross osteochondral defects had a greater percentage of mature repair tissue in saline-treated joints (30.8% LWB, 23% WB), compared with MPA-treated joints (0% LWB, 0% WB) at 42 days. Histomorphometric assessment of the repair tissue indicated significant differences with regard to the quality of repair in the saline-treated (34.% fibrous tissue LWB, 19.4% fibrous tissue WB) versus MPA-treated (2.5% fibrous tissue in LWB and WB) joints at 42 days. Microscopically, the percentage of fibrocartilage in the LWB (MPA, 23.7%; saline, 24.8%) was significantly greater than that in the WB (MPA, 14.6%; saline, 15.4%) site at day 180. The MPA-treated limbs had greater villous hyperplasia, edema, and extent of inflammation within the synovial membrane than did saline-treated limbs (days 42 and 180).

Conclusion

MPA inhibits the development and maturation of repair tissue at 42 days and incites potential long-term (180 days) detrimental synovial membrane inflammation. Furthermore, a single dose of MPA does not cause long-term detrimental effects (180 days) in quality of repair tissue. (Am J Vet Res 1996;57:914–922)

Abstract

Objective

To evaluate joint function and healing of surgically created full-thickness articular cartilage defects in exercised horses after intra-articular administration of methylprednisolone acetate (MPA; 120 mg) and sterile saline solution in the contralateral limb.

Design

Experimental investigation.

Sample Population

12 healthy, sound, radiographically normal horses with induced full-thickness osteochondral lesions on the medial and lateral trochlear ridges of the tali.

Procedure

Two 8.4-mm-diameter full-thickness articular cartilage lesions were created in each tarsocrural joint (12 horses [24 tarsocrural joints]); 1 was in a weight-bearing (WB) position and the other in a less weight-bearing (LWB) position. Each horse was maintained on a standardized exercise protocol (stall rest, days 0-6; walking, days 7-12; and treadmill, days 13-42) and evaluated throughout the study for changes in joint circumferences, synovial fluid, radiographs, lameness, and scintigraphy. 6 horses were euthanatized on day 42, and 6 on day 180.

Gross morphometric assessment was performed, using an image analysis system on a projected color slide of the defect. The type of repair tissue, based on gross appearance, was expressed as a percentage of the total defect for each osteochondral defect. Histochemical assessment was performed, using safranin-O staining for proteoglycans and an image analysis system to express the area of stain uptake. Histomorphometric assessment was performed on H&E-stamed sections, using an image analysis system. The repair tissue filling the defect was categorized as to tissue type and expressed as a percentage of the total defect area. Synovial membrane specimens were assessed semiquantitatively on H&E-stained sections for changes in character. Significance was established at P < 0.05.

Results

Joint circumference was significantly increased in the saline, compared with the MPA-treated, limbs on days 7, 12, and 42. Synovial fluid WBC counts were significantly increased in the MPA-treated limbs on day 42. Gross osteochondral defects had a greater percentage of mature repair tissue in saline-treated joints (30.8% LWB, 23% WB), compared with MPA-treated joints (0% LWB, 0% WB) at 42 days. Histomorphometric assessment of the repair tissue indicated significant differences with regard to the quality of repair in the saline-treated (34.% fibrous tissue LWB, 19.4% fibrous tissue WB) versus MPA-treated (2.5% fibrous tissue in LWB and WB) joints at 42 days. Microscopically, the percentage of fibrocartilage in the LWB (MPA, 23.7%; saline, 24.8%) was significantly greater than that in the WB (MPA, 14.6%; saline, 15.4%) site at day 180. The MPA-treated limbs had greater villous hyperplasia, edema, and extent of inflammation within the synovial membrane than did saline-treated limbs (days 42 and 180).

Conclusion

MPA inhibits the development and maturation of repair tissue at 42 days and incites potential long-term (180 days) detrimental synovial membrane inflammation. Furthermore, a single dose of MPA does not cause long-term detrimental effects (180 days) in quality of repair tissue. (Am J Vet Res 1996;57:914–922)

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 3925 3913 243
PDF Downloads 54 49 0
Advertisement