Experimental osteoporosis induced by ovariectomy and vitamin D deficiency does not markedly affect fracture healing in rats

Figures & data

Table 1.  Bone mineral density (BMD) in vivo measured by DXA at different sites before and 2, 3, and 6 weeks after induction of a tibial midshaft fracture on the right side. BMD of the intramedullary nail was measured in vitro and subtracted from the in vivo BMD values of right tibia. The left limb was used as an internal control. Values are mean (SD)

		n^a	Prior to (g/cm2 × 10-2)	n	2 weeks (g/cm2 × 10-2)	n	3 weeks (g/cm2 × 10-2)	n	6 weeks (g/cm2 × 10-2)
Right limb
Callus	Ovx-D			36	24.2 (5.0)	36	24.9 (5.3)	24	25.2 (5.5)
	Sham			28	22.8 (4.8)	30	23.4 (7.1)	18	26.3(8.3)
Tibia	Ovx-D	36	24.9 (1.6) c	35	23.8 (5.6)	35	24.0 (4.0)	24	21.4 (4.7)
	Sham	30	23.9 (2.0)	31	24.8 (4.3)	32	24.8 (5.2)	19	23.1 (5.2)
Femoral neck	Ovx-D			34	36.7 (3.5) b	34	35.5 (3.4) b	23	34.1 (4.2) b
	Sham			26	43.0 (3.8)	28	42.5 (5.1)	18	42.2 (5.0)
Left limb
Tibia	Ovx-D			33	24.8 (1.8)	35	24.4 (1.9)	24	24.3 (1.9)
	Sham			30	24.2 (1.5)	30	24.1 (1.5)	19	24.0 (1.8)
Femoral neck	Ovx-D			36	39.9 (3.6) b	36	38.8 (3.8) b	23	40.6 (2.6) b
	Sham			31	45.1 (4.0)	32	45.3 (4.1)	19	46.5 (3.9)
Vertebra, lower lumbal
	Ovx-D			31	28.8 (3.6) b	36	29.2 (3.7) b	22	29.3 (3.5) b
	Sham			28	40.6 (4.8)	27	40.2 (5.2)	19	39.5 (4.5)

^an is the number of bone specimens studied

^bLower BMD in the Ovx-D group than in the Sham group (p < 0.001)

^{cHigher BMD in the Ovx-D group than in the Sham group (p = 0.03)}

Table 2.  Right-left comparison of bone mineral density (BMD) in vivo 2, 3 and 6 weeks after induction of a tibial midshaft fracture on the right (R) side. BMD of the intramedullary nail was measured in vitro and subtracted from the in vivo BMD values of right tibia. The left limb (L) was used as an internal control. Values are mean (SD)

	Side	n^a	2 weeks (g/cm2 × 10-2)	n	3 weeks (g/cm2 × 10-2)	n	6 weeks (g/cm2 × 10--2)
Ovx-D
Tibia	R	35	23.8 (5.6)	35	24.0 (4.0)	24	21.4 (4.7)
	L	33	24.8 (1.8)	35	24.4 (1.9)	24	24.3 (1.9) c
Femoral	R	34	36.7 (3.5)	34	35.5 (3.4)	23	34.1 (4.2)
neck	L	36	39.9 (3.6) b	36	38.8 (3.8) b	23	40.6 (2.6) b
Sham
Tibia	R	31	24.8 (4.3)	32	24.8 (5.2)	19	23.1 (5.2)
	L	30	24.2 (1.5)	30	24.1 (1.5)	19	24.0 (1.8)
Femoral	R	26	43.0 (3.8)	28	42.5 (5.1)	18	42.1 (5.0)
neck	L	31	45.1 (4.0) e	32	45.3 (4.1) d	19	46.5 (3.9) c

^a n is the number of bone specimens studied

^b Higher BMD in the left limb than in the right limb (p < 0.001)

^c Higher BMD in the left limb than in the right limb (p = 0.005)

^d Higher BMD in the left limb than in the right limb (p = 0.02)

^e Higher BMD in the left limb than in the right limb (p = 0.05)

Table 3.  Comparison of biomechanical properties of callus and long bones in Ovx-D and Sham groups examined in a 3-point cantilever bending test. A standardized fracture was performed in the tibial midshaft on the right side of all animals, and fixed with an intramedullary nail. The nail was removed prior to mechanical testing. The left limb was used as an internal control. Values are mean (SD)

Bone site	Group	n ^a	Bending moment (Nm)		Energy absorption (J × 10^-2)		Bending stiffness (Nm/degree × 10^-2)		Defiection (degrees)
			Fractured limb	Control	Fractured limb	Control	Fractured limb	Control	Fractured limb	Control
Tibia	Ovx-D	6/11	15.1	42.5	34.8	99.7	58.3	77.2	10.7	22.5
			(4.5) b	(3.8)	(10) b	(8.9)	(27) b	(14)	(3.2) b	(3.7)
	Sham	7/11	15.7	40.2	34.6	94.2	39.3	67.2	14.3	22.9
			(8.0) b	(3.7)	(19) b	(8.9)	(15) b	(7.2)	(4.7) b	(2.2)
Femur	Ovx-D	11/11	61.0	62.3	143	146	114	116	20.4	20.3
			(4.8)	(4.3)	(11)	(10)	(11)	(9.6)	(2.6)	(1.2)
	Sham	11/11	61.3	62.8	144	147	123	120	18.3	19.5
			(9.5)	(11)	(22)	(26)	(19)	(22)	(2.1)	(2.8)
Femoral neck	Ovx-D	11/10	31.1	48.8	72.9	115	52.4	81.8	22.2	22.1
			(5.9)	(15)	(14)	(36)	(4.9) c	(27)	(3.4)	(5.6)
	Sham	11/10	35.9	47.4	84.4	112	62.7	72.7	20.1	23.4
			(7.2)	(8.1)	(17)	(19)	(13)	(16)	(2.2)	(4.4)

^an is the number of animals studied

^b Biomechanical parameters of callus 6 weeks after fracture.

^c Significantly lower bending stiffness in the Ovx-D group than in the Sham group (p = 0.02)

Figure 1. Light microscopic pictures of sections of femoral head with a magnification of 2.5×. Panel A, from an Ovx-D rat, shows substantial loss of trabecular bone and trabecular connectivity compared to panel B, which was taken from a Sham rat.

Figure 2. Trabecular bone volume density (VvTB) in the femoral head was significantly lower in the Ovx-group than in the Sham group, both 3 and 6 weeks after tibial shaft surgery. After 3 weeks, n = 14 in both right and left leg; after 6 weeks, n = 11/12 and 8/9 with respect to Ovx and Sham. * p < 0.001

Table 4.  Histomorphometry on tibial and femoral diaphyses 3 and 6 weeks after induction of tibial midshaft fracture. Values are mean (SD) × 10^-1

			Outer diameter (mm)			Cortical thickness (mm)				Cortical area (mm^2)
	Group	n ^a	Right	n	Left	n	Right	n	Left	n	Right	n	Left
Tibial shaft
3 weeks	Ovx-D	5	24.5 (3.2)	6	25.5 (1.6)	5	5.3 (1.3)	6	5.1 (0.3)	5	35.9 (9.5)	6	38.7 (4.7)
	Sham	7	26.0 (2.1)	7	24.0 (2.9)	7	5.5 (0.5)	7	4.9 (1.0)	7	39.6 (4.5)	7	33.5 (7.7)
6 weeks	Ovx-D	6	23.1 (1.0)	6	22.8 (0.9)	6	5.2 (0.4)	6	4.8 (0.5)	5	3.1 (1.8)	6	30.9 (2.8)
	Sham	5	23.4 (5.6)	5	22.4 (0.9)	5	5.0 (1.1)	5	4.9 (0.5)	5	31.7 (14.0)	4	28.6 (4.6)
Femoral shaft
3 weeks	Ovx-D	6	29.9 (1.1)	7	30.5 (1.7)	7	5.5 (0.5) c	7	5.6 (0.4) b	6	42.6 (3.5) d	7	46.4 (3.6)
	Sham	7	29.9 (1.5)	6	30.5 (1.0)	7	6.2 (0.5)	7	6.2 (0.4)	7	48.0 (4.2)	6	48.2 (3.8)
6 weeks	Ovx-D	6	29.5 (1.5)	6	29.3 (1.9)	6	5.9 (0.2)	6	6.0 (0.2)	6	43.6 (2.4)	6	46.2 (5.0)
	Sham	5	29.4 (1.5)	5	28.9 (1.4)	5	5.9 (0.5)	5	5.7 (0.3)	5	45.6 (4.3)	4	41.7 (2.7)

^a n is the number of animals studied

^b Significant differences (p = 0.01) with respect to Ovx-D

^c Significant differences (p = 0.02) with respect to Ovx-D

^d Significant differences (p = 0.03) with respect to Ovx-D