Abstract
Introduction
There is no consensus regarding the reconstruction method for type 1 resections around the pelvis. Various methods are currently used, such as resection without reconstruction, bone graft (autologous, recycled, allograft) with simple fixation, and pedicle screw-rod fixation with or without bone grafting. We aim to study the outcome of pedicle screw-rod reconstruction without bone grafting in type 1 pelvic resections involving sacroiliac joint to show that pedicle screw-rod construct alone is stable and has low risk of failure.
Material and methods
This is a retrospective review of eight patients who underwent type 1 resection of malignant pelvic tumours and reconstruction with a pedicle screw-rod system between 2011 and 2018. All patients who underwent type 1 resection and reconstruction with pedicle screw without bone grafting were included into this study. We reported their clinical (complication and radiological outcome), oncological (local recurrence and metastasis), and functional outcome based on Musculoskeletal Tumour Society Score (MSTS) and The Toronto Extremity Salvage Score (TESS) at their last follow-up.
Results
Eight patients were recruited into the study. The mean follow-up period was 58.5 months (range: 40 – 121 months). There were three postoperative complications in three different patients: superficial infection, surgical hernia with ipsilateral femoral avascular necrosis (AVN), and femoral nerve injury. At the end of the study period, one patient passed away due to disease progression, one patient was alive with disease, and the rest were disease-free. Mean MSTS score during last follow-up was 77.1% (range: 66.7% – 93.3%), while mean TESS score was 75.6% range (63.3% - 80.2%). There were no cases of implant failure.
Conclusion
Type 1 pelvic reconstruction with a pedicle screw-rod system is stable without a concurrent biological reconstruction, and it is feasible, with few complications, and an excellent functional outcome.
Keywords
Introduction
Pelvis is a common site for bone tumours. 1 Almost 10%–15% of all malignant bone tumours are in the pelvis.2–4 It is also the second most common site for bone metastases after the spine 5 Majority of bone tumours involving pelvis are usually those that metastasized. 6
Due to its late presentation and a complex anatomy, pelvic tumours pose a significant challenge to orthopaedic oncology surgeons. Before 1970s, most of these cases were treated with hindquarter amputation. 7 Over the years, as limb salvage surgery progressed, internal hemipelvectomy gradually replaced amputation (external hemipelvectomy) as the standard treatment method for pelvic tumours. Enneking and Dunham 8 classified pelvic resections into three types, of which resections of the ilium were type I. Resections involving the acetabulum were type II, while those involving ischium and pubic rami were type III. Pelvic resections are associated with multiple complications due to their complicated anatomy in relation to large vessels, nerve plexuses, intestines, urinary bladder, and internal sex organs.5,8–13 Some of these complications are also related to the chosen reconstruction method. 10 The outcome of these surgeries is less favourable due to many factors such as tumour size, local extension of tumour and anatomical complexity, and the proximity of pelvic viscera and major nerves and vessels.1,5,9
Various reconstruction methods are currently employed for type 1 pelvic resections, ranging from no reconstruction to bone graft (vascularised and non-vascularised autograft, allograft, recycled autograft), or bone cement with or without fixation with implant ranging from plate and screws to pedicle screw-rod systems.9–14 Each method has its advantages and disadvantages. The pedicle screw-rod system is usually accompanied by structural bone grafting as a biological reconstruction for added stability and long-term longevity. However, several authors as shown in Table 2 reported complications such as infection, graft failure, and non-union, that were related to the use of bone graft.9,11,15–22
This study aims to determine the outcome of pedicle screw-rod reconstruction without bone grafting for type 1 pelvic resections, to show that the pedicle screw-rod construct alone has a low risk of failure.
Material and methods
This is a retrospective study. We reviewed all patients who underwent internal hemipelvectomy (complete type I pelvic resection) through the sacroiliac joint with reconstruction using a pedicle screw-rod system without bone grafting for malignant pelvic tumours, from November 2011 to September 2020, with a minimum follow up of 3 years from surgery date. The malignant pelvic tumours included in this study were primary and secondary malignant bone tumours. The secondary malignant bone tumours included were ought to be either a localised metastasis or a single bone metastasis which requires a primary wide resection of the pelvis similar to a primary malignant bone tumour. The resections were performed following Enneking’s classification of pelvic bone tumours. 8 We excluded patients who underwent other forms of resections, partial resections, or resections not involving the sacroiliac joint. All the surgeries were carried out by the senior author (single surgeon).
All patients had plain radiographs, magnetic resonance images (MRI), and computed tomography (CT) of the chest and pelvis taken to assess the tumour’s local and systemic extent, after which biopsy was carried out to obtain a histopathological diagnosis and grade the tumour. After reviewing all biomedical images, we planned the surgery.
We reported the clinical outcome, which consisted of associated complications, oncological outcome (local recurrence and metastasis), and functional outcomes. The functional outcome was assessed using the Musculoskeletal Tumour Society Score (MSTS Score) 23 and Toronto Extremity Salvage Score (TESS).24,25 Data obtained were analysed with the Excel sheet software programme (Microsoft® Office Excel 2013).
Surgical procedure
All surgeries were conducted under general anaesthesia. Bowel preparation was carried out the day before surgery. Prophylactic antibiotics were delivered at the time of induction of anaesthesia. Our institution’s common antibiotics for pelvic resections are intravenous Vancomycin and Metronidazole. The skin incision was made along the iliac crest from the posterior superior iliac spine to the anterior superior iliac spine, followed by dissection carried along with the iliac bone’s inner and outer tables. The patient was placed in the floppy lateral position on the operating table. The tumour was then exposed with a muscle cuff (iliacus in the internal table and the gluteus medius and minimus in the outer table). Subsequently, en-bloc resection was performed through the sacroiliac joint posteriorly and an osteotomy through a major sciatic notch anteriorly in the supra-acetabulum area (sparing the acetabulum) after isolating major blood vessels and nerves and protecting of pelvic viscera. Pelvic ring reconstruction was performed by inserting two polyaxial pedicle screws into the sacrum (intrapelvic fixation) and two polyaxial screws into the remaining pelvic bone after resection, at the supra-acetabular region along the iliopectineal and ilio-ischial lines. These screws were then connected with a rod to complete the pelvic ring, as shown in Figure 1. Shows an example of a 52 years old lady with Malignant GCT of the left illium. (a) Plain radiograph shows rarefraction with irregularity within the left iliac bone. (b) CT scan shows destructive lesion within the left iliac bone sparing the left sacroiliac joint. (c) MRI shows heterogenous changes within the left illium. (d) Shows intraoperative picture of the pedicle screw rod reconstruction. (e) Shows postoperative pedicle screw reconstruction of the left pelvis.
Results
Patient data.
All patients were diagnosed with malignant tumours. Five patients were diagnosed with primary bone tumours, two had primary soft tissue sarcoma (STS) involving the iliac bone, and one had secondary metastatic disease. Among the primary bone tumours, two were cases of Ewing’s sarcoma (both received neoadjuvant chemotherapy and postoperative adjuvant chemotherapy and radiotherapy), while the other three were one case each of chondrosarcoma (treated with just surgical resection), malignant giant cell tumour (GCT), and pleomorphic sarcoma of the bone, out of which the latter two received postoperative radiation. For those with primary soft tissue sarcomas, one had low-grade myofibroblastic sarcoma eroding iliac bone while the other one had fibrosarcoma. Both patients received postoperative radiotherapy. The sole case of metastasis was secondary from uterine leiomyosarcoma, in which there was metastasis to the left iliac bone at the time of operation and lung metastasis. Lung metastasis was also present among patients with Ewing’s sarcoma and malignant GCT. The lung metastasis in the patient with Ewing’s resolved with chemotherapy, while the ones in the malignant GCT patient were observed and remained stable at last review.
Three patients developed postoperative complications. The first patient had superficial infection treated with debridement and intravenous antibiotics. The second patient developed a surgical hernia and ipsilateral femoral head avascular necrosis (AVN) due to partial erosion of the hip from one pedicle screw (iatrogenic). He was treated conservatively due to his age and comorbidities. The third patient had partial femoral nerve injury attributed to its proximity to the tumour. There were no cases of implant failures at last review.
The oncological outcome was as follows; one patient died due to primary disease progression, one was alive with disease, and the remaining patients were free of disease. The patient with chondrosarcoma developed soft tissue recurrence 2 years after the primary resection, and it was excised with clear margins.
The functional outcome at final follow up showed a mean MSTS score of 23.6 ± 3.0 (77.1% ± 21.9) {range (20 – 28/66.7% – 93.3%)}; and a mean TESS score of 75.6% {range (63.3% - 80.2%)}.
Discussion
With advances in diagnostic tools, therapeutic measures of chemotherapy, radiotherapy, and surgical techniques, internal hemipelvectomy has become the treatment of choice. 10 Nevertheless, extensive resection surgeries performed to obtain tumour free margins usually result in structural defects, thus compromising the integrity of the pelvic ring.15,26
Ogura et al. emphasised the importance of reconstruction after pelvic resection around the sacroiliac joint to restore the pelvic ring, which is essential for the pelvis and spinal column’s stability. 9 These objectives could be achieved with a reconstruction that provides stability, hence preventing superior migration and collapse of the remaining hemipelvis. 12 In contrast, Beadel et al. 13 and Puri 14 reported excellent results with type 1 resections without reconstruction, and their outcomes were compatible with those who underwent reconstruction. However, we favour reconstruction as we feel that it would prevent the superior migration of the pelvis, which is encountered in cases where no reconstruction is done and leads to limb length discrepancy. Our study is unique as we only used the pedicle screw and rod system for reconstruction and did not augment it with biological reconstruction (structural bone graft). The advantage of this technique is a shorter operating time, no donor site morbidity from fibular autograft, lower risk of infection and lower cost due to no usage of additional bone grafting (autografts or allografts). The advantage of using a structural bone graft as a biological form of reconstruction is that once it incorporates, it has a lower failure rate. However, we feel that this additional surgical procedure is unnecessary as the pedicle screw and rod reconstruction can be a permanently stable form of reconstruction. We could also avoid complications associated with the use of structural bone graft. The most dreaded complication in a pelvic reconstruction involving biological reconstruction is deep infection, as once it is established, the graft usually must be removed.
Shows comparison between this studies and the various studies published in the literature.
Abbreviations: Double barrel vascularised fibular graft (DBVFG); Alive with disease (AWD); Disease free (DF); Not Available (NA); Malignant fibrous histiocytoma (MFH); Malignant peripheral nerve sheath tumour (MPNST).
Several complications were reported after pelvic resections, including infections and wound healing problems, bleeding, thrombosis, nerve and visceral injuries, and implants' failure (Table 2). Our series' complication rate was 37.5%, which was lower than other studies (40–60%).5,9,11,12,14 The low complication rate was probably due to multiple factors including relatively simple reconstruction, shorter operating time, and no additional bone grafting procedures.
Our series' infection rate was only 12.5% (one out of eight patients), and it was a superficial infection. This was far less compared to other reported studies1,5,9–12,14 (22.2–30%). This was probably because we did not use any biological material like bone or foreign material like cement or polypropylene mesh, thus decreasing the possibility of infections. In our series, we had one case of a partial femoral nerve injury and one case of erosion of a hip due to the pedicle screw’s misplacement. There were no cases of visceral injuries, as reported in other studies.11,16
One patient (12.5%) passed away 3 months after surgery due to primary disease progression (due to lung metastasis). Our mortality rate was lower compared to other studies.5,9–12,14 Local recurrence developed in one patient with chondrosarcoma 5 months after resection. It was a soft tissue recurrence that was treated with wide excision. Our recurrence rate was also far lesser than those reported in other studies5,9,10,12,16 However, the rate of local recurrence and mortality depends mainly on the biological aggressiveness of the primary tumour and systemic extent of disease at presentation.
We did not experience any implant failure in our series. However, Lin P et al. 12 reported 22.7% implant failure, and their series used the pedicle screw-rod reconstruction augmented with either strut fibula graft or cementation. Similarly, other series which also utilised pedicle screw-rod systems for stabilisation, such as Zhou YJ 11 Ogura K et al. 9 Sabourin, 19 and Nishida J 17 also reported no implant failures. However, in these series, the reconstruction was augmented with bone graft as a form of biological reconstruction. It contrasts our series, where we only used pedicle screws and rods. Based on our series (Table 1), the longest survivor was 121 months (10 years) and the patient was disease free in his last follow up. The second longest survivors were four patients with a duration of 69–78 months (5.75 - 6.5 years) and all of them were disease free except one who passed away due to advanced disease. Based on this, majority of our construct (62.5%) can safely last a minimum of 5 years and up to 10 years without implant failure. This longevity is adequate to confer patients with stability for daily usage after completion of primary treatment.
We are of the opinion that the advantage of using just a pedicle screw-rod system alone compared to a combined implant and biological reconstruction is that shortens the operating time as there is one less procedure to be carried out, there is no donor site morbidity (the standard biological reconstruction done is fibula autograft), and a lower infection rate as biological material is not inserted into the operative site. Compared to biological reconstruction alone, implants give immediate stability, early weight-bearing, and a lesser possibility of early failure. However, biological reconstructions do have the advantage of longevity compared to implant reconstruction alone, provided they incorporate well to the host bone.
Our study’s mean MSTS score at final follow-up was 77.1%, which is compatible with other studies with type 1 pelvic resections reconstructed with pedicle screw-rod reconstruction (57% - 94.6%).9,11,12,17–19 The high scores might be attributed to early rehabilitation in these patients due to stable reconstruction and lower mechanical complications. The series with biological reconstructions reported a mixed functional outcome (MSTS) ranging from 51% to 75.4%.15,16,20 This is probably due to delay in full weight-bearing, as biological forms of reconstruction usually take time to incorporate into the host bone and become stable.
The limitation of this study is the small number of cases. This is due to rarity of the disease as established in previous studies. Hence, we only included patients of complete type I pelvic resections. Due to the rarity of the cases, it is not feasible to create a control group for this study. Furthermore, we were unable to compare the preoperative and the postoperative functional scores as this is a retrospective study, and the preoperative functional scores were not documented.
Conclusion
In conclusion, a pedicle screw-rod system without grafting is a reliable option of reconstruction in pelvic resections around the sacroiliac joint due to fewer complication rates, early rehabilitation, its feasibility, and the affordability of implants.
Footnotes
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
