Clin Orthop Surg.  2011 Dec;3(4):309-314. 10.4055/cios.2011.3.4.309.

Physeal Growth Arrest by Excessive Compression: Histological, Biochemical, and Micro-CT Observations in Rabbits

• Yoo WJ
• Cheon JE
• Lee HR
• Cho TJ
• Choi IH

• KMID: 1097169
• DOI: http://doi.org/10.4055/cios.2011.3.4.309

Abstract

BACKGROUND
Compressive force across the growth plate may cause retardation and even arrest of physeal growth. The purpose of this study was to investigate histologic changes, metabolic changes in terms of glycosaminoglycan (GAG) concentration, and contrast-enhanced micro-computed tomography (CEMCT) findings of physeal cartilage in a rabbit model of physeal damage caused by excessive compression.
METHODS
Compressive forces were applied via external fixators for two weeks to the growth plates of distal femurs and proximal tibiae of right hind-legs in 8-week-old rabbits. Left hind-legs remained intact and were used as controls. Forty-four bone specimens containing growth plates of distal femurs or proximal tibiae were harvested one week (n = 12) and four weeks (n = 32) after surgery, and examined for histologic findings (H&E staining) and GAGs quantification in physeal cartilage. After incubation in an ionic contrast material for 48 hours, specimens were scanned by CEMCT, and the pixel values of physeal cartilage were measured.
RESULTS
CEMCT showed a thin, highly attenuated line parallel to the growth plate in compressed specimens harvested at four weeks after surgery, which was found to be transversely connected trabecular bone. In these specimens, GAG content in physeal cartilage was significantly lower, and CEMCT pixel values of physeal cartilage were significantly higher than in the specimens from the contralateral control side.
CONCLUSIONS
Excessive compressive force applied to growth plates produces altered histologic features and metabolic function in terms of decreased GAG content in physeal cartilage, changes that can be demonstrated by CEMCT.

Keyword

Contrast-enhanced micro-CT; Growth plate; Growth arrest; Rabbit; Glycosaminoglycan

MeSH Terms

Animals
Growth Plate/*growth & development/metabolism/*pathology/radiography
Male
Pressure
Rabbits
X-Ray Microtomography

Figure

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  Fig. 1 Two custom-made external fixators were used to apply compressive force to the growth plate of the distal femur and proximal tibia across the knee joint in the right hind-leg.

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  Fig. 2 Contrast-enhanced micro-computed tomography images showed that a thin, highly attenuated line parallel to the growth plate (arrows) was formed in compressed specimens (RF and RT) harvested at four weeks after surgery. RF: right femur, RT: right tibia, LF: left femur, LT: left tibia.

• 

  Fig. 3 A histologic section of a compressed specimen harvested at four weeks after surgery showed newly formed trabecular bones that were interconnected haphazardly (asterisk) and transversely connected trabecular bone (arrows), the latter of which corresponded with the highly attenuated line observed in the contrast-enhanced micro-computed tomography (A: × 10, B: H&E, × 100).

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