To investigate the scope of application of biological reconstruction of the ipsilateral proximal femoral osteotomy segment after periacetabular tumor resection defect. Methods Anatomical measurements of the proximal femur were performed on 13 male fresh frozen cadavers. A total of 6 indices, including the diameter of the femoral head, the distance from the apex of the femoral head to the base of the femoral neck, the distance from the apex of the femoral trochanter to the osteotomy, the vertical distance between the apex of the femoral trochanter and the medial edge of the femoral neck, the length from the apex of the femoral head to the midpoint of the osteotomy line under the lesser trochanter, and the anterior and posterior widths of the trochanter, were measured in 5 pairs of proximal femoral osteotomy segments after interception. The data from 13 proximal femoral osteotomies were pooled and analyzed in a uniform manner, and the Mann-Whitney U test was used to compare the right and left sides of each parameter. Spearmen’s correlation was applied to analyze the degree of correlation between each parameter and body length.
Results: There was no statistical difference between the left and right side of each measured parameter (P>0.05). The median (interquartile spacing) of each measurement parameter was 49 mm (48-52.7 mm), 62.4 mm (60-27.2 mm), 83.5 mm (75-87 mm), 58.5 mm (54.5-60.9 mm), 102 mm (96-105.2 mm), and 48 mm (46.5-51 mm), respectively. All parameters were positively correlated with body length (P<0.05)< i="">.
CONCLUSION: The ipsilateral proximal femoral osteotomy segment can biologically reconstruct the post-tumor resection pelvic defect within a certain range. However, the size of the post-tumor resection defect and the width and height of the thick ridge of the proximal femoral osteotomy segment must be evaluated.
The pelvic reconstruction after resection of pelvic malignant tumors has been a challenge for clinical treatment because of the large postoperative defect, the proximity to pelvic viscera, blood vessels and nerves, and the high rate of postoperative complications. There are many methods of reconstruction after pelvic malignant tumor resection, including femoral-iliac and femoral-sciatic fusion, in vitro inactivation and reimplantation of pelvic tumor bone resection, large allograft bone graft reconstruction, saddle-type prosthesis and group-matched pelvic prosthesis. Recently, Biau et al [1] reported ipsilateral proximal femoral osteotomy segment biologic reconstruction and application of common artificial hip replacement for periacetabular malignancy, but the anatomical measurements of its osteotomy segment have not been reported. In this study, an anatomical study of the proximal femoral osteotomy segment was conducted to investigate the applicability of this reconstruction method.
I. Gross anatomy and sampling method
Thirteen fresh frozen cadavers were collected for anatomical and quantitative analysis by the Department of Anatomy and Research, Nanjing University. The median height was 169.8 cm (interquartile spacing, 168 to 175.7 cm). These proximal femoral specimens had no history of trauma, deformity, or disease. All cadavers were preserved frozen and thawed the night before autopsy.5 Measurements were taken after applying a pendulum saw to complete osteotomized segments of the proximal femur.8 Measurements were taken in situ after dissection and exposure of the proximal femoral specimens. The osteotomy lines are shown in Figure 1. The first osteotomy line is flat on the lower edge of the lesser trochanter and perpendicular to the longitudinal axis of the femur. The second osteotomy line was located at the mid and middle 1/3 points of the first osteotomy line up to the top of the greater trochanter.
For in situ measurements, the first Kirschner pin is placed at the junction point of the external and external 1/3 of the first osteotomy line, and the second Kirschner pin is placed at the end of the second osteotomy line at the apex of the greater trochanter (Figure 2). Both the in situ and post-osteotomy measurements were performed after the osteotomy and measurements were performed with the Kirschner pin positioned as described above, enabling the selection of the starting and ending points of the measurements. Measurements were performed by the same investigator with no inter-measurer error. Intra-measurer agreement was good (κ=0.93). This study was approved by the ethics committee of Nanjing University.
II. Measurement parameters
The measurement parameters were the diameter of the femoral head (Diameter of Femoral Head, DFH), the distance between Apex of Femoral Head and Bottom Line of Femoral Neck (DAB), the distance from the apex of the femoral trochanter to the osteotomy Distance between Apex of Greater Trochanter and Osteotomy Line under Lesser Trochanter (DAO), Distance of Apex of Greater Trochanter perpendicular to medial edge of Femoral Neck (DAO), Distance of Apex of Trochanter perpendicular to Medial Edge of Femoral Neck, DAM), Length between Apex of Greater Trochanter and Midpoint of Osteotomy Line under Lesser Trochanter Osteotomy Line under Lesser Trochanter, LAM), and the width of Greater Trochanter Anterior to Posterior (WG). All measurements were calculated in millimeters.
Five pairs of proximal femoral osteotomies were measured after complete sampling. In situ measurements of DAB, DAO, DAM, and LAM are shown in Figure 2-A. In situ measurements of DFH and WG are shown in Figure 2-B. All measurements were done by the same observer. The results of the two groups of measurements were pooled and analyzed.
III. Statistical methods
Various measured parameters were expressed by median (interquartile spacing). The values of each parameter of the proximal femur on the right and left sides were mixed together to calculate the median, interquartile spacing, maximum and minimum values. The Mann-Whitney U test was applied for the left-right side comparison analysis of each parameter. spearmen’s correlation was used to analyze the degree of correlation between each parameter and body length. spss 13.0 software package (SPSS, Chicago, IL, USA) was used for statistical analysis of the results. p<0.05 was considered statistically significant. < p="">
IV. RESULTS
There was no statistically significant comparison between the left and right side of the proximal femoral osteotomy segment for each parameter (Table 1) (p>0.05). DFH, DAB, DAO, DAM, LAM and WG were positively correlated with length (p<0.05)< i="">(Table 2).
Among these six parameters, three parameters, DAM, WG, and LAM, were very important.DAM indicates the height of the proximal femoral osteotomy segment to accommodate the artificial acetabular cup. In this study, the median (interquartile spacing), maximum, and minimum values of DAM were 58.5 mm (54.5-60.9 mm), 63.7 mm, and 41 mm, respectively, and when compared with the data from Lithakon’s artificial acetabular cups, all 13 pairs of proximal femoral osteotomies had this height to accommodate the artificial acetabular cups. The maximum and minimum values of LAM were 102 mm (96-105.2 mm), 109 mm, and 87 mm, respectively.
In preoperative planning, the length of the LAM should be equal to or greater than the length of the pelvic defect after resection of malignant tumors under strict surgical boundaries. wg represents the width of the osteotomy to fit the acetabular cup of different external diameters. Its median (interquartile spacing), maximum and minimum values were 48 mm (46.5-51 mm), 52.5 mm and 45 mm, respectively. comparing with the data of artificial acetabular cups provided by Litacom and Trilogy titanium wire acetabular cups provided by Zimmer, less than half of the patients were suitable for this reconstructive surgical treatment.
Data on artificial acetabular cups from other companies such as Stryer or DePuy were not available for this study. Therefore, a comparison of the osteotomy segment data with their artificial acetabular cups was not performed. However, in most artificial acetabular cups, the height is approximately equal to half of the outer diameter. In comparison with the measured data of this study, the outer diameter of the artificial acetabular cup should be less than 52.5 mm (the maximum value of WG).
V. DISCUSSION
Reconstruction of pelvic defects after resection of malignant tumors around the acetabulum is a difficult and challenging task in bone tumor treatment. Orthopedic oncologists dedicated to the treatment of pelvic tumors have proposed several approaches to pelvic reconstruction. These include sitiofemoral fusion or pseudarthrosis, iliofemoral fusion or pseudarthrosis; autologous tumor segment bone high-temperature inactivation reimplantation; large allograft bone graft reconstruction; allograft bone prosthesis composite reconstruction; custom prosthesis reconstruction; saddle-type prosthesis reconstruction; general prosthesis reconstruction with bone cement without biological reconstruction; custom prosthesis with hip displacement or saddle-type prosthesis; hip lift and grouped hemi-pelvic prosthesis. Each type of reconstruction has its advantages and disadvantages and is not completely applicable to all patients.
In addition, the biologic reconstruction of the pelvic defect with an ipsilateral proximal femoral osteotomy segment combined with a plain artificial hip replacement for periacetabular malignancy proposed by Puget and Utheza and recently reported by Biau et al. may be an important option. This method of pelvic reconstruction consists of ipsilateral proximal femoral osteotomy, followed by reversal of the osteotomized segment in the pelvic defect after malignant tumor resection, fixation of the osteotomized segment to the pubic bone and iliac bone with a reconstruction plate, acetabular reconstruction in the thick part of the osteotomized segment, and simultaneous replacement with a normal artificial hip prosthesis. The advantage of this method is that it provides the basis for biological reconstruction by fusing the osteotomized segment with the pubic bone and iliac bone after surgery, and avoids complications such as rejection, fracture of the allograft bone and long-term bone discontinuity between the allograft and the host bone due to the application of large pieces of allograft bone. However, anatomical studies of proximal femoral osteotomy segments have not been reported in the literature.
In this study, measurements of the proximal femoral osteotomy segment were analyzed to investigate the applicability of this reconstruction method.
In this study, 6 parameters were measured in 13 pairs of proximal femoral osteotomy segments, and there was no statistical difference between the left and right sides of the 6 parameters (P>0.05). Three of these parameters were very important in this study. The DAM and WG represent the width and height of the osteotomy segment to accommodate the artificial acetabular cup, respectively, and the LAM represents the length of the osteotomy segment required to reconstruct the pelvic defect after periacetabular malignancy resection. All 6 measured parameters were positively correlated with body length (P<0.05)< i="">. The length of the proximal femoral osteotomy segment and the width and height of the osteotomy segment’s ramus increased with S height, and the likelihood of applying this reconstruction method increased in patients with taller stature.
Reconstruction is required to restore anatomic longitudinal weight-bearing function after resection of periacetabular malignancy. Without reconstruction, patients will lose most of their mobility while causing bilateral lower extremity inequality. Therefore, reconstruction of the pelvic defect after tumor resection has been a major concern for bone oncologists. The boundary of tumor resection is another important element. For malignant tumors with clear diagnosis, adequate surgical borders can reduce the chance of tumor recurrence and metastasis. The more adequate the border, the lower the chance of tumor recurrence and metastasis. However, the more extensive the border achieved during pelvic tumor resection, the greater the defect.
The length from the apex of the femoral head to the midpoint of the inferior osteotomy line of the lesser trochanter (LAM) is a very important parameter in the application of ipsilateral proximal femoral osteotomy segments for the biologic reconstruction of pelvic defects and in the application of common artificial hip prostheses for the treatment of periacetabular tumor defects. In the present study, the median (interquartile spacing), maximum and minimum values of LAM were 102 mm (96-105.2 mm), 109 mm and 87 mm, respectively.These results suggest that the length of the defect or the length of the ipsilateral proximal femoral osteotomy segment was approximately 10 cm in half of the patients in the present study. Preoperatively, the surgical border of the tumor should be precisely determined and the complete imaging data should be evaluated in detail. The size of the proximal femoral osteotomy segment should be equal to or larger than the size of the periacetabular defect after tumor resection.
A normal artificial acetabular cup is mounted on the turned osteotomy segment, which requires the osteotomy segment to be wide and high enough to accommodate the acetabular cup. The ridge of the osteotomy segment provides the width space to accommodate the appropriate diameter acetabular cup. In this study, the median (interquartile spacing), maximum, and minimum values of WG were 48 mm (46.5-51 mm), 52.5 mm, and 45 mm, respectively, and less than half of the patients could be reconstructed using this method when compared with the data from Lidacom and Zimmer, China. However, data on the diameter and height of artificial acetabular cups from other companies, such as Stryker and Depuy, were not available in this study.
In the study by Biau et al, they reported that the median diameter of their applied acetabular cup was 40 mm (range, 40-48 mm). They suggested that the limited space in the greater trochanteric region does not allow for the application of larger acetabular cups and that the majority of cases with reconstruction failure occur with smaller diameter cups. Another problem is that when an acetabular file is applied to the turned osteotomy segment for new acetabular contouring, the anterior-posterior diameter may decrease even more at the femoral neck site as the new acetabular fossa deepens. Furthermore, the edges of the osteotomy segment may be damaged and destroyed by the acetabular file. Therefore, the actual width of the ridge of the osteotomy segment may be less than the width of the ridge on the osteotomy segment at the time of measurement. In this case, only an acetabular cup with a smaller outer diameter can be applied.
Another option is to apply a locking reconstruction plate when fixing the osteotomy segment, which increases the width and height of the osteotomy segment while fixing it anteriorly and posteriorly, facilitating cement attachment and the application of larger acetabular cups or reinforcement rings. In this study, DAM represents the height of the thick ridge of the osteotomy segment, which is the height to accommodate the artificial acetabular cup. The median (interquartile spacing), maximum and minimum values were 58.5 mm (54.5-60.9 mm), 63.7 mm and 41 mm, respectively, which were found to be sufficient to accommodate the artificial acetabular cups when compared with those provided by Lidacom and Zimmer in China. As for the other companies’ artificial acetabular cups, the height of the proximal femoral osteotomy segment does not affect the placement of the cup since most of the artificial cups are half the outer diameter.
The application of ipsilateral proximal femoral osteotomy segment to biologically reconstruct the pelvic defect after resection of malignant tumors may be a treatment option. However, due to the size of the post-tumor resection pelvic defect, the length of the osteotomy segment that can provide bone reconstruction, and the width and height of the osteotomy segment ridge, this reconstruction method may be suitable for only a subset of patients. An accurate preoperative assessment of the size of the post-tumor resection periacetabular defect, as well as the length of the osteotomy segment and the width and height of the osteotomy ridge, is crucial to the application of this reconstruction method.