Hip Int 2014 ; 24 ( 1): 32- 38
DOI: 10.5301/hipint.5000083
ORIGINAL ARTICLE
The influence of triple pelvic osteotomy on birth canal size Ondrˇ ej Schwarz, Jirˇ í Chomiak, Pavel Dungl, Michal Burian Department of Orthopaedics, First Faculty of Medicine, Charles University in Prague and Hospital Bulovka, Prague - Czech Republic
Introduction: The aim of this study was to investigate the influence of triple pelvic osteotomy on the internal pelvic dimensions and thus on the potential for normal vaginal delivery. Methods: Data were acquired by processing fixed anatomical specimens of 19 female pelves with maintained sacrotuberous and sacrospinous ligaments after unilateral and bilateral osteotomy, respectively. The specimens were measured and x-ray images and photographs were taken. Results: The dimensions in the plane of the pelvic inlet and the plane of the greatest pelvic dimension after unilateral osteotomy increased in 51%, remained unchanged in 34% and in 15% of cases they decreased. The most critical locations for the passage of fetus decreased in average from 0.016 cm in distantia interspinalis in the plane of the least pelvic dimension to 0.695 cm in distantia intertuberositas in the plane of the pelvic outlet. After bilateral osteotomy are decreases more significant from 0.226 cm (2.05%) to 1.00 cm (9.51%). Decreases we observed in the monitored dimensions were not so big in comparison to other published studies. Conclusion: Results of this study confirm our hypothesis that unilateral triple pelvic osteotomy does not significantly narrow the bony birth canal and so it does not impede the ability to deliver per vias naturales in female patients with this surgical procedure in anamnesis. After bilateral triple osteotomy we would rather recommend Caesarean section. Keywords: Triple pelvic osteotomy, Birth canal, Pelvic dimensions, Caesarean section Accepted: July 1, 2013
INTRODUCTION The consequences of developmental dysplasia of the hip (DDH) can influence the manner of delivery. This influence may be primary, i.e. pelvic deformity caused by abnormal development, or secondary, when alteration of the birth canal occurs as a result of surgical procedures conducted during childhood and adolescence increasing the risk to mother and fetus. There are many surgical procedures that can improve biomechanics and increase the load-bearing area of the hip joint (1-6, 11, 13-16). One of the treatment methods for residual dysplasia of the hip is triple pelvic osteotomy (TPO), which is based on osteotomy of the ilium, the ischium and the pubis and a subsequent change in the 32
position of the acetabular fragment. In our department we have been using the Steel triple pelvic osteotomy (4) with our own modifications (1-3) for a long time (Fig. 1 a-d). We chose the triple pelvic osteotomy for this investigation because the pelvis is interrupted in the plane of the least pelvic dimension and in the plane of the pelvic outlet, thus the possibility exists for the formation of an obstacle during the passage of the fetus in the course of spontaneous vaginal delivery. Very few articles have been published concerning this matter and their results are heterogeneous (7-10). We decided to investigate how triple pelvic osteotomy changes and influences internal and external pelvic dimensions and whether female patients undergoing this surgical procedure should be advised against normal vaginal delivery.
© 2014 Wichtig Publishing - ISSN 1120-7000
Schwarz et al
references (7, 10, 17). The Hospital’s Ethics Committee approved the study. Soft tissues including muscles and tendons were removed from the pelves; the sacrospinous ligament, sacrotuberous ligament and sacroiliac ligament (structures important for the stability of the pelvis) were maintained, as well as the hip joint capsule with proximal parts of the femur and the 5th lumbar vertebra. a
b
c
d Fig. 1 - The scheme of triple pelvic osteotomy in our modification with a detailed view on the place of osteotomy of the ischium and the pubic with the resection of bone segment of 0.5 cm: a) resected fragments; b) rotation and tilting of acetabular segment; c) graft and osteotomy fixation with Kirschner wires (adopted with permission from Ortopedie (1)); d) cadaverous pelvis with resected fragments from the ischium and the pubic bone.
Our hypothesis is that our modification of the Steel triple pelvic osteotomy does not impede spontaneous vaginal delivery.
MATERIALS AND METHODS We used fixed anatomical specimens of the female pelvis. Pelves were obtained from cadavers of donors to the Anatomical Institute. The donors were mainly of advanced years and therefore may have sustained damage or injury to the pelvis with subsequent deformity over the course of their lives. Therefore, we included only non-deformed pelves in the study in order to avoid a decrease in the particular dimension or size below the average stated in the
Measurements made in the following manner Points were marked in coloured ink in order to ensure measuring at the same points. The following points of particular pelvic planes were measured (Fig. 2, a and b) – the pelvic inlet – promontorium, linea terminalis, the upper edge of the pubic symphysis; the plane of the greatest pelvic dimension – S2-3, the centre of the acetabulum, the centre of the symphysis; the plane of the least pelvic dimension – the ischial spine, the lower border of sacrum, the lower border of the symphysis; the pelvic outlet – the tip of the coccyx, the medial border of the ischial tuberosity, the lower border of the symphysis; the obstetrical conjugate (OC) – the distance between the promontory to the most bulging point on the back of the symphysis pubis; and the diagonal conjugate – the distance between the lower border of the symphysis pubic and promontory (17). Statistical analysis one-sided Student´s t-test was performed by Stata statistical software, release 9.2, Stata Corp. LP, College Station, TX. The significance level was set at 0.05. We measured all internal dimensions on particular pelvic planes, external pelvic dimensions, and dimensions used in obstetrics, and x-ray of specimens (anteroposterior view and inlet view). Photographs were also taken. Subsequently, a unilateral triple pelvic osteotomy was performed (with resection of a bone segment of 0.5 cm in the ischium and pubis). We inserted a bone graft, taken from crista iliaca with a base width of approximately 1 cm, into the iliac osteotomy and the osteotomy with the bone graft were fixed with three to four Kirschner wires. Pelvic dimensions were measured again and x-rays and photographs of specimens were taken. The osteotomy of the other side followed. After bilateral osteotomy, there was a problem with the stabilisation of the pelvic ring; therefore, to increase pelvic stabilisation we fixed the osteotomy of the pubis and the ischium with Kirschner wires which is not performed on living patients. X-ray and photographs of the specimens were taken.
© 2014 Wichtig Publishing - ISSN 1120-7000
33
Influence of triple pelvic osteotomy on birth canal size
a
b Fig. 2 - a) and b) Detail of cadaverous specimen with points for measurements marked in color. Pelvic inlet: A-A´ transverse diameter, B-B´ oblique diameter, C-C´ anteroposterior diameter; the plane of the greatest pelvic dimension: D-D´ transverse diameter E, F the beginning of oblique diameter and anteroposterior diameter; the plane of the least pelvic dimension: G-G´ interspinous diameter , I-the beginning of anteroposterior diameter.
In total we processed 19 specimens of female pelves and 38 hip joints. One specimen was removed because the sacrospinous ligament and sacrotuberous ligament failed to be maintained during preparation.
RESULTS After unilateral surgical procedures, pelvic dimensions changed as follows (Tab. I). There was an increase in 51% of all dimensions in the plane of the pelvic inlet and in the plane of the greatest pelvic dimension and 34% dimensions remained unchanged. Only in 15% of cases did they decrease (maximally in 34
0.7 cm in oblique dimension in the plane of the pelvic inlet). In the plane of the least pelvic dimension and the pelvic outlet the particular dimensions changed as follows: 1) anteroposterior dimension in the plane of least pelvic dimensions decreased in eight cases (up to 0.6 cm), increased in one (by 1.3 cm) and in 10 cases remained unchanged. Average change was -0.042 cm, which is 0.38% from average size of the given dimension (p = 0.311); 2) anteroposterior dimension of the pelvic outlet decreased in 10 cases, increased in two and in seven cases remained unchanged. On average, the dimension statistically significantly decreased by 0.132 cm, 1.54% (p = 0.015) (Fig. 3); 3) distance between the ischial spines increased in six cases (up to 1.2 cm), in 11 cases decreased (up to 0.5 cm) and in two cases remained the same with an average change of -0.016 cm, 0.15% (p = 0.445) (Fig. 3); 4) bituberous distance between the inner aspects of the ischial tuberosities remained the same in two cases and in 17 cases decreased (up to 1.4 cm) with an average statistically significant change of -0.695 cm, 6.6% (p
DOI: 10.5301/hipint.5000083
ORIGINAL ARTICLE
The influence of triple pelvic osteotomy on birth canal size Ondrˇ ej Schwarz, Jirˇ í Chomiak, Pavel Dungl, Michal Burian Department of Orthopaedics, First Faculty of Medicine, Charles University in Prague and Hospital Bulovka, Prague - Czech Republic
Introduction: The aim of this study was to investigate the influence of triple pelvic osteotomy on the internal pelvic dimensions and thus on the potential for normal vaginal delivery. Methods: Data were acquired by processing fixed anatomical specimens of 19 female pelves with maintained sacrotuberous and sacrospinous ligaments after unilateral and bilateral osteotomy, respectively. The specimens were measured and x-ray images and photographs were taken. Results: The dimensions in the plane of the pelvic inlet and the plane of the greatest pelvic dimension after unilateral osteotomy increased in 51%, remained unchanged in 34% and in 15% of cases they decreased. The most critical locations for the passage of fetus decreased in average from 0.016 cm in distantia interspinalis in the plane of the least pelvic dimension to 0.695 cm in distantia intertuberositas in the plane of the pelvic outlet. After bilateral osteotomy are decreases more significant from 0.226 cm (2.05%) to 1.00 cm (9.51%). Decreases we observed in the monitored dimensions were not so big in comparison to other published studies. Conclusion: Results of this study confirm our hypothesis that unilateral triple pelvic osteotomy does not significantly narrow the bony birth canal and so it does not impede the ability to deliver per vias naturales in female patients with this surgical procedure in anamnesis. After bilateral triple osteotomy we would rather recommend Caesarean section. Keywords: Triple pelvic osteotomy, Birth canal, Pelvic dimensions, Caesarean section Accepted: July 1, 2013
INTRODUCTION The consequences of developmental dysplasia of the hip (DDH) can influence the manner of delivery. This influence may be primary, i.e. pelvic deformity caused by abnormal development, or secondary, when alteration of the birth canal occurs as a result of surgical procedures conducted during childhood and adolescence increasing the risk to mother and fetus. There are many surgical procedures that can improve biomechanics and increase the load-bearing area of the hip joint (1-6, 11, 13-16). One of the treatment methods for residual dysplasia of the hip is triple pelvic osteotomy (TPO), which is based on osteotomy of the ilium, the ischium and the pubis and a subsequent change in the 32
position of the acetabular fragment. In our department we have been using the Steel triple pelvic osteotomy (4) with our own modifications (1-3) for a long time (Fig. 1 a-d). We chose the triple pelvic osteotomy for this investigation because the pelvis is interrupted in the plane of the least pelvic dimension and in the plane of the pelvic outlet, thus the possibility exists for the formation of an obstacle during the passage of the fetus in the course of spontaneous vaginal delivery. Very few articles have been published concerning this matter and their results are heterogeneous (7-10). We decided to investigate how triple pelvic osteotomy changes and influences internal and external pelvic dimensions and whether female patients undergoing this surgical procedure should be advised against normal vaginal delivery.
© 2014 Wichtig Publishing - ISSN 1120-7000
Schwarz et al
references (7, 10, 17). The Hospital’s Ethics Committee approved the study. Soft tissues including muscles and tendons were removed from the pelves; the sacrospinous ligament, sacrotuberous ligament and sacroiliac ligament (structures important for the stability of the pelvis) were maintained, as well as the hip joint capsule with proximal parts of the femur and the 5th lumbar vertebra. a
b
c
d Fig. 1 - The scheme of triple pelvic osteotomy in our modification with a detailed view on the place of osteotomy of the ischium and the pubic with the resection of bone segment of 0.5 cm: a) resected fragments; b) rotation and tilting of acetabular segment; c) graft and osteotomy fixation with Kirschner wires (adopted with permission from Ortopedie (1)); d) cadaverous pelvis with resected fragments from the ischium and the pubic bone.
Our hypothesis is that our modification of the Steel triple pelvic osteotomy does not impede spontaneous vaginal delivery.
MATERIALS AND METHODS We used fixed anatomical specimens of the female pelvis. Pelves were obtained from cadavers of donors to the Anatomical Institute. The donors were mainly of advanced years and therefore may have sustained damage or injury to the pelvis with subsequent deformity over the course of their lives. Therefore, we included only non-deformed pelves in the study in order to avoid a decrease in the particular dimension or size below the average stated in the
Measurements made in the following manner Points were marked in coloured ink in order to ensure measuring at the same points. The following points of particular pelvic planes were measured (Fig. 2, a and b) – the pelvic inlet – promontorium, linea terminalis, the upper edge of the pubic symphysis; the plane of the greatest pelvic dimension – S2-3, the centre of the acetabulum, the centre of the symphysis; the plane of the least pelvic dimension – the ischial spine, the lower border of sacrum, the lower border of the symphysis; the pelvic outlet – the tip of the coccyx, the medial border of the ischial tuberosity, the lower border of the symphysis; the obstetrical conjugate (OC) – the distance between the promontory to the most bulging point on the back of the symphysis pubis; and the diagonal conjugate – the distance between the lower border of the symphysis pubic and promontory (17). Statistical analysis one-sided Student´s t-test was performed by Stata statistical software, release 9.2, Stata Corp. LP, College Station, TX. The significance level was set at 0.05. We measured all internal dimensions on particular pelvic planes, external pelvic dimensions, and dimensions used in obstetrics, and x-ray of specimens (anteroposterior view and inlet view). Photographs were also taken. Subsequently, a unilateral triple pelvic osteotomy was performed (with resection of a bone segment of 0.5 cm in the ischium and pubis). We inserted a bone graft, taken from crista iliaca with a base width of approximately 1 cm, into the iliac osteotomy and the osteotomy with the bone graft were fixed with three to four Kirschner wires. Pelvic dimensions were measured again and x-rays and photographs of specimens were taken. The osteotomy of the other side followed. After bilateral osteotomy, there was a problem with the stabilisation of the pelvic ring; therefore, to increase pelvic stabilisation we fixed the osteotomy of the pubis and the ischium with Kirschner wires which is not performed on living patients. X-ray and photographs of the specimens were taken.
© 2014 Wichtig Publishing - ISSN 1120-7000
33
Influence of triple pelvic osteotomy on birth canal size
a
b Fig. 2 - a) and b) Detail of cadaverous specimen with points for measurements marked in color. Pelvic inlet: A-A´ transverse diameter, B-B´ oblique diameter, C-C´ anteroposterior diameter; the plane of the greatest pelvic dimension: D-D´ transverse diameter E, F the beginning of oblique diameter and anteroposterior diameter; the plane of the least pelvic dimension: G-G´ interspinous diameter , I-the beginning of anteroposterior diameter.
In total we processed 19 specimens of female pelves and 38 hip joints. One specimen was removed because the sacrospinous ligament and sacrotuberous ligament failed to be maintained during preparation.
RESULTS After unilateral surgical procedures, pelvic dimensions changed as follows (Tab. I). There was an increase in 51% of all dimensions in the plane of the pelvic inlet and in the plane of the greatest pelvic dimension and 34% dimensions remained unchanged. Only in 15% of cases did they decrease (maximally in 34
0.7 cm in oblique dimension in the plane of the pelvic inlet). In the plane of the least pelvic dimension and the pelvic outlet the particular dimensions changed as follows: 1) anteroposterior dimension in the plane of least pelvic dimensions decreased in eight cases (up to 0.6 cm), increased in one (by 1.3 cm) and in 10 cases remained unchanged. Average change was -0.042 cm, which is 0.38% from average size of the given dimension (p = 0.311); 2) anteroposterior dimension of the pelvic outlet decreased in 10 cases, increased in two and in seven cases remained unchanged. On average, the dimension statistically significantly decreased by 0.132 cm, 1.54% (p = 0.015) (Fig. 3); 3) distance between the ischial spines increased in six cases (up to 1.2 cm), in 11 cases decreased (up to 0.5 cm) and in two cases remained the same with an average change of -0.016 cm, 0.15% (p = 0.445) (Fig. 3); 4) bituberous distance between the inner aspects of the ischial tuberosities remained the same in two cases and in 17 cases decreased (up to 1.4 cm) with an average statistically significant change of -0.695 cm, 6.6% (p
