Limits...
Preliminary investigations on intradiscal pressures during daily activities: an in vivo study using the merino sheep.

Reitmaier S, Schmidt H, Ihler R, Kocak T, Graf N, Ignatius A, Wilke HJ - PLoS ONE (2013)

Bottom Line: Here, IDPs averaged 3.73 MPa and 1.60 MPa respectively, approximately two to four times higher in the ovine disc compared to human.For activity and rest, average ovine forces were 130 N and 58 N, compared to human forces of 400-600 N and 100 N, respectively.In vivo IDPs were found to be higher in the ovine than in the human disc.

View Article: PubMed Central - PubMed

Affiliation: Institute of Orthopedic Research and Biomechanics, Center of Musculoskeletal Research, University of Ulm, Ulm, Germany. sandra.reitmaier@uni-ulm.de

ABSTRACT

Purpose: Currently, no studies exist, which attest the suitability of the ovine intervertebral disc as a biomechanical in vivo model for preclinical tests of new therapeutic strategies of the human disc. By measuring the intradiscal pressure in vivo, the current study attempts to characterize an essential biomechanical parameter to provide a more comprehensive physiological understanding of the ovine intervertebral disc.

Methods: Intradiscal pressure (IDP) was measured for 24 hours within the discs L2-L3 and L4-L5 via a piezo-resistive pressure sensor in one merino sheep. The data were divided into an activity and a recovery phase and the corresponding average pressures for both phases were determined. Additionally, IDPs for different static and dynamic activities were analyzed and juxtaposed to human data published previously. After sacrificing the sheep, the forces corresponding to the measured IDPs were examined ex vivo in an axial compression test.

Results: The temporal patterns of IDP where pressure decreased during activity and increased during rest were comparable between humans and sheep. However, large differences were observed for different dynamic activities such as standing up or walking. Here, IDPs averaged 3.73 MPa and 1.60 MPa respectively, approximately two to four times higher in the ovine disc compared to human. These IDPs correspond to lower ex vivo derived axial compressive forces for the ovine disc in comparison to the human disc. For activity and rest, average ovine forces were 130 N and 58 N, compared to human forces of 400-600 N and 100 N, respectively.

Conclusions: In vivo IDPs were found to be higher in the ovine than in the human disc. In contrast, axial forces derived ex vivo were markedly lower in comparison to humans. Both should be considered in future preclinical tests of intradiscal therapies using the sheep. The techniques used in the current study may serve as a protocol for measuring IDP in a variety of large animal models.

Show MeSH
Ovine in vivo pressure values in comparison to literature.Intradiscal pressure in L2-L3 and L4-L5 for various static and dynamic activities measured in one sheep. Ovine values represent the median and ranges for six different time points throughout the test duration in comparison to both quadrupedal [30] and human measurements [24–26].
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3722231&req=5

pone-0069610-g004: Ovine in vivo pressure values in comparison to literature.Intradiscal pressure in L2-L3 and L4-L5 for various static and dynamic activities measured in one sheep. Ovine values represent the median and ranges for six different time points throughout the test duration in comparison to both quadrupedal [30] and human measurements [24–26].

Mentions: Except for lying intraoperatively, only negligible differences in IDPs were seen for the two disc levels (Figure 4). In the following, therefore, only the IDPs for the disc of L2-L3 are given. The median and ranges for all recorded IDPs measured in both L2-L3 and L4-L5 during different activities are summarized in Table 1. No significant differences were found between lying during surgery (0.43 MPa, range: 0.41-0.43 MPa) and nocturnal sleeping (0.43 MPa, range: 0.38-0.47 MPa). Relaxed standing yielded an IDP value of approximately 0.70 MPa (range: 0.60-0.91 MPa). In contrast to static activities, dynamic activities caused a substantially higher IDP. The highest values were measured for standing up with ~3.73 MPa (range: 3.34-4.50 MPa) followed by lying down with ~2.25 MPa (range: 2.20–2.31 MPa) and walking with ~1.60 MPa (range: 1.34-3.58 MPa).


Preliminary investigations on intradiscal pressures during daily activities: an in vivo study using the merino sheep.

Reitmaier S, Schmidt H, Ihler R, Kocak T, Graf N, Ignatius A, Wilke HJ - PLoS ONE (2013)

Ovine in vivo pressure values in comparison to literature.Intradiscal pressure in L2-L3 and L4-L5 for various static and dynamic activities measured in one sheep. Ovine values represent the median and ranges for six different time points throughout the test duration in comparison to both quadrupedal [30] and human measurements [24–26].
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3722231&req=5

pone-0069610-g004: Ovine in vivo pressure values in comparison to literature.Intradiscal pressure in L2-L3 and L4-L5 for various static and dynamic activities measured in one sheep. Ovine values represent the median and ranges for six different time points throughout the test duration in comparison to both quadrupedal [30] and human measurements [24–26].
Mentions: Except for lying intraoperatively, only negligible differences in IDPs were seen for the two disc levels (Figure 4). In the following, therefore, only the IDPs for the disc of L2-L3 are given. The median and ranges for all recorded IDPs measured in both L2-L3 and L4-L5 during different activities are summarized in Table 1. No significant differences were found between lying during surgery (0.43 MPa, range: 0.41-0.43 MPa) and nocturnal sleeping (0.43 MPa, range: 0.38-0.47 MPa). Relaxed standing yielded an IDP value of approximately 0.70 MPa (range: 0.60-0.91 MPa). In contrast to static activities, dynamic activities caused a substantially higher IDP. The highest values were measured for standing up with ~3.73 MPa (range: 3.34-4.50 MPa) followed by lying down with ~2.25 MPa (range: 2.20–2.31 MPa) and walking with ~1.60 MPa (range: 1.34-3.58 MPa).

Bottom Line: Here, IDPs averaged 3.73 MPa and 1.60 MPa respectively, approximately two to four times higher in the ovine disc compared to human.For activity and rest, average ovine forces were 130 N and 58 N, compared to human forces of 400-600 N and 100 N, respectively.In vivo IDPs were found to be higher in the ovine than in the human disc.

View Article: PubMed Central - PubMed

Affiliation: Institute of Orthopedic Research and Biomechanics, Center of Musculoskeletal Research, University of Ulm, Ulm, Germany. sandra.reitmaier@uni-ulm.de

ABSTRACT

Purpose: Currently, no studies exist, which attest the suitability of the ovine intervertebral disc as a biomechanical in vivo model for preclinical tests of new therapeutic strategies of the human disc. By measuring the intradiscal pressure in vivo, the current study attempts to characterize an essential biomechanical parameter to provide a more comprehensive physiological understanding of the ovine intervertebral disc.

Methods: Intradiscal pressure (IDP) was measured for 24 hours within the discs L2-L3 and L4-L5 via a piezo-resistive pressure sensor in one merino sheep. The data were divided into an activity and a recovery phase and the corresponding average pressures for both phases were determined. Additionally, IDPs for different static and dynamic activities were analyzed and juxtaposed to human data published previously. After sacrificing the sheep, the forces corresponding to the measured IDPs were examined ex vivo in an axial compression test.

Results: The temporal patterns of IDP where pressure decreased during activity and increased during rest were comparable between humans and sheep. However, large differences were observed for different dynamic activities such as standing up or walking. Here, IDPs averaged 3.73 MPa and 1.60 MPa respectively, approximately two to four times higher in the ovine disc compared to human. These IDPs correspond to lower ex vivo derived axial compressive forces for the ovine disc in comparison to the human disc. For activity and rest, average ovine forces were 130 N and 58 N, compared to human forces of 400-600 N and 100 N, respectively.

Conclusions: In vivo IDPs were found to be higher in the ovine than in the human disc. In contrast, axial forces derived ex vivo were markedly lower in comparison to humans. Both should be considered in future preclinical tests of intradiscal therapies using the sheep. The techniques used in the current study may serve as a protocol for measuring IDP in a variety of large animal models.

Show MeSH