Biomechanical and clinical outcomes of 3D-printed versus modular hemipelvic prostheses for limb-salvage reconstruction following periacetabular tumor resection: a mid-term retrospective cohort study.

BACKGROUND: Debates persist over optimal pelvic girdle reconstruction after acetabular tumor resection, with surgeons grappling between modular and 3D-printed hemipelvic endoprostheses. We hypothesize superior outcomes with 3D-printed versions, yet scarce comparative research exists. This study fills the gap, examining biomechanics and clinical results retrospectively. METHODS: From February 2017 to June 2021, we retrospectively assessed 32 patients undergoing en bloc resection for malignant periacetabular tumors at a single institution. PRIMARY OUTCOME: limb function. SECONDARY OUTCOMES: implant precision, hip joint rotation center restoration, prosthesis-bone osteointegration, and complications. Biomechanical characteristics were evaluated through finite element analysis on pelvic defect models. RESULTS: In the 3D-printed group, stress distribution mirrored a normal pelvis, contrasting the modular group with elevated overall stress, unstable transitions, and higher stress peaks. The 3D-printed group exhibited superior functional scores (MSTS: 24.3 ± 1.8 vs. 21.8 ± 2.0, p < 0.05; HHS: 79.8 ± 5.2 vs. 75.3 ± 3.5, p < 0.05). Prosthetic-bone interface osteointegration, measured by T-SMART, favored 3D-printed prostheses, but surgery time (426.2 ± 67.0 vs. 301.7 ± 48.6 min, p < 0.05) and blood loss (2121.1 ± 686.8 vs. 1600.0 ± 505.0 ml, p < 0.05) were higher. CONCLUSIONS: The 3D-printed hemipelvic endoprosthesis offers precise pelvic ring defect matching, superior stress transmission, and function compared to modular endoprostheses. However, complexity, fabrication expertise, and challenging surgical implantation result in prolonged operation times and increased blood loss. A nuanced consideration of functional outcomes, complexity, and patient conditions is crucial for informed treatment decisions. LEVEL OF EVIDENCE: Level III, therapeutic study (Retrospective comparative study).

Effective Management of Sacral Stress Fractures in Gastric Cancer: Iliosacral Screw Fixation Following a Type 3 Hemipelvectomy.

Metastatic pelvic tumors pose a significant challenge in oncologic orthopedics due to their complex management and the high potential for postoperative complications. This case study discusses a 75-year-old male with a sacral stress fracture following a type 3 internal hemipelvectomy for a metastatic lesion from gastric cancer in the left pubic bone. Initial conservative treatments failed to yield satisfactory improvement, leading to surgical intervention. Open reduction and internal fixation with an iliosacral screw, despite complications, significantly alleviated pain and improved mobility. This case underscores the difficulty in diagnosing sacral stress fractures versus metastatic lesions and highlights the effectiveness of iliosacral screw fixation in managing postoperative sacral stress fractures. It emphasizes the procedure's role in providing early pain relief and enhancing daily activity levels. Additionally, it points out the importance of addressing altered bone metabolism in the postoperative care of patients with metastatic pelvic tumors. This contributes to the literature by stressing the incidence of sacral stress fractures as a critical, though often overlooked, complication and demonstrating the benefits of iliosacral screw fixation in such scenarios for better recovery and quality of life.

Rehabilitation and functional outcomes for thoraco-omphalo-ischiopagus conjoined twins five years after separation: A case report.

Conjoined twins are identical twins joined in utero and are a rare phenomenon. This report discusses a case of female thoraco-omphalo-ischiopagus tripus conjoined twins. The twins were separated at age two, and once medically stable, spent one month in inpatient rehabilitation to improve their sitting balance and gross motor skills. This was followed by outpatient physical therapy. The twins initially had customized ZipZac seats, which they were able to wheel independently. After six months of therapy, the girls began walking with posterior walkers and prostheses. The hemipelvectomy prosthesis included a customized thoracolumbosacral orthosis component and was directly attached to a non-articulated pylon. A manual-locking hip joint was added to accommodate sitting. An articulated ankle-foot orthosis was used for the intact leg. Care of formerly conjoined twins requires comprehensive care from a multidisciplinary team involving, but not limited to, a physiatrist, orthopaedic surgeon, physical therapist, and orthotist/prosthetist. Complex congenital limb deficiencies are often a major undertaking for the rehabilitation team as continuous treatment and management are needed throughout the patient's lifetime due to growth, development, and evolving physical demands. Anatomic variations must be examined on a case-by-case basis but often include limb deficiencies, orthopedic abnormalities, and organ comorbidities.

Internal hemipelvectomy: A single institution's learning curve and longitudinal experience.

BACKGROUND AND OBJECTIVES: Wide margin resection for pelvic tumors via internal hemipelvectomy is among the most technically challenging procedures in orthopedic oncology. As such, surgeon experience and technique invariably affect patient outcomes. The aim of this clinical study was to assess how an individual surgeon's experiences and advancements in technology and techniques in the treatment of internal hemipelvectomy have impacted patient outcomes at our institution. METHODS: This study retrospectively examined a single tertiary academic institution's consecutive longitudinal experience with internal hemipelvectomy for primary sarcoma or pelvic metastases over a 26-year period between the years 1994 and 2020. Outcomes were assessed using two separate techniques. The first stratified patients into cohorts based on the date of surgery with three distinct "eras" ("early," "middle," and "modern"), which reflect the implementation of new techniques, including three-dimensional (3D) computer navigation and cutting guide technology into our clinical practice. The second method of cohort selection grouped patients based on each surgeon's case experience with internal hemipelvectomy ("inexperienced," "developing," and "experienced"). Primary endpoints included margin status, complication profiles, and long-term oncologic outcomes. Whole group multivariate analysis was used to evaluate variables predicting blood loss, operative time, tumor-free survival, and mortality. RESULTS: A total of 72 patients who underwent internal hemipelvectomy were identified. Of these patients, 24 had surgery between 1994 and 2007 (early), 28 between 2007 and 2015 (middle), and 20 between 2016 and 2020 (modern). Twenty-eight patients had surgery while the surgeon was still inexperienced, 24 while developing, and 20 when experienced. Evaluation by era demonstrated that a greater proportion of patients were indicated for surgery for oligometastatic disease in the modern era (0% vs. 14.3% vs. 35%, p = 0.022). Fewer modern cases utilized freehand resection (100% vs. 75% vs. 55%, p = 0.012), while instead opting for more frequent utilization of computer navigation (0% vs. 25% vs. 20%, p = 0.012), and customized 3D-printed cutting guides (0% vs. 0% vs. 25%, p = 0.002). Similarly, there was a decline in the rate of massive blood loss observed (72.2% vs. 30.8% vs. 35%, p = 0.016), and interdisciplinary collaboration with a general surgeon for pelvic dissection became more common (4.2% vs. 32.1% vs. 85%, p < 0.001). Local recurrence was less prevalent in patients treated in middle and modern eras (50% vs. 15.4% vs. 25%, p = 0.045). When stratifying by case experience, surgeries performed by experienced surgeons were less frequently complicated by massive blood loss (66.7% vs. 40% vs. 20%, p = 0.007) and more often involved a general surgeon for pelvic dissection (17.9% vs. 37.5% vs. 65%, p = 0.004). Whole group multivariate analysis demonstrated that the use of patient-specific instrumentation (PSI) predicted lower intraoperative blood loss (p = 0.040). However, surgeon experience had no significant effect on operative time (p = 0.125), tumor-free survival (p = 0.501), or overall patient survival (p = 0.735). CONCLUSION: While our institution continues to utilize neoadjuvant and adjuvant therapies following current guideline-based care, we have noticed changing trends from early to modern periods. With the advent of new technologies, we have seen a decline in freehand resections for hemipelvectomy procedures, and a transition to utilizing more 3D navigation and customized 3D cutting guides. Furthermore, we have employed the use of an interdisciplinary team approach more regularly for these complicated cases. Although our results do not demonstrate a significant change in perioperative outcomes over the years, our institution's willingness to treat more complex cases likely obscures the benefits of surgeon experience and recent technological advances for patient outcomes.

Midterm outcomes of total hip arthroplasty after internal hemipelvectomy and iliofemoral arthrodesis.

BACKGROUND AND OBJECTIVES: Recent studies have reported acceptable outcomes after arthrodesis takedown and conversion to total hip arthroplasty (THA); however, there are no reports on outcomes after oncologic resection, which are inherently complex and may portend poorer outcomes. The purpose of this study was to examine the surgical and functional outcomes of patients who underwent prior hemipelvectomy for tumor resection and were later converted to THA. METHODS: All patients who had prior iliofemoral arthrodesis after oncologic resection that were later converted to THA at a single institution were examined. Charts were reviewed for demographic information, operative information, functional outcomes, and complications/reoperations. RESULTS: All three patients in this study were males who underwent internal hemipelvectomies for chondrosarcoma. Patients were converted to THA at a mean of 26 years after arthrodesis. Mean follow-up after conversion to THA was 7.4 years. During this follow-up period, two of the three patients required revision surgery. At last follow-up, the mean Harris Hip Score was 81 and the mean Mayo Hip Score was 67, and all patients were ambulatory without significant pain. CONCLUSIONS: Overall, patients who undergo iliofemoral arthrodesis after oncologic hemipelvectomy and are later converted to THA can expect to have a reasonable outcome, despite a high rate of complications and revision surgery.

Targeted Muscle Reinnervation to Reduce Postoperative Pain in Patients Undergoing Hindquarter Resections.

BACKGROUND/AIM: Pre-emptive targeted muscle reinnervation (TMR) at the time of amputation results in less phantom limb pain (PLP) compared with untreated amputee controls. There is limited literature describing the technique in patients undergoing hindquarter amputation despite up to 90% of these patients reporting PLP and 50% presenting with painful neuroma. The purpose of the current study was to describe the motor nerves accessible through a primary hind-quarter amputation to be used for TMR and review pain outcomes in clinical case correlates of patients with TMR. PATIENTS AND METHODS: Six limbs were obtained from three fresh adult cadavers and proximal sensory and motor nerves were dissected. A review of patients undergoing hindquarter amputation with TMR was conducted. RESULTS: Transfers for the sciatic, femoral, and obturator nerves were identified in cadavers. In reviews of patients, they were taking narcotic and neuro-leptic pain medication for a mean of 23 days and 168 days. At most recent follow-up, no patient reported debilitating phantom pain nor pain associated with neuromas. CONCLUSION: Given the positive preliminary results in our study group as well as the accessible neuroanatomy, pre-emptive TMR should be considered at the time of surgery to limit PLP and dependence on pain medications.

Pelvis reconstruction by proximal femur upshifting and total hip arthroplasty after radical resection of an adolescent patient pelvic Ewing's sarcoma, a case report, and literature review.

INTRODUCTION AND IMPORTANCE: Pelvis reconstruction after tumor resection poses a challenge, especially in younger patients where preserving the patient's function and mobility is paramount. CASE PRESENTATION: A 16 years old female presented in March 2019 with vague right iliac area pain, diagnosed as pelvic Ewing's sarcoma after imaging studies (MRI and MSCT scan) and obtaining an incisional biopsy. After initial chemotherapy cycles, the tumor decreased in size, and surgical intervention in two stages was performed. The first stage was in October 2019 and consisted of pelvic resection type I and II according to Enneking and Dunham classification, proximal femur upshifting to compensate for the pelvic bone defect, and a cement spacer to fill the space of the resected proximal femur. The second stage was performed after two months and consisted of implanting a total hip arthroplasty using Megaprostheses and a cementless dual mobility acetabular cup. No local recurrence or distant metastases were detected during follow-ups. At the final follow up after 36 months, the patient showed acceptable functional outcomes (HHS score 83, and MSTS score 23 (76.7 %) points), and the radiographs showed proper implant positioning and stability. CLINICAL DISCUSSION: Treating pelvic Ewing's sarcoma requires a multidisciplinary team. After surgical resection, the pelvic reconstruction options include using allografts or autografts, femur upshifting, and hemipelvis prostheses, which should be chosen considering patients and tumor characteristics as well as surgical team efficiency. CONCLUSION: Reconstructing the pelvic defect after bone tumor resection by proximal femoral upshifting is a valid biological option with acceptable outcomes.

Retrospective analysis of mortality and quality of life after hip disarticulation or hemipelvectomy: a report on 15 patients.

BACKGROUND: Hip disarticulation and hemipelvectomy are defined as major ablative amputations of the lower limb. Due to the small number of patients, little is known about the outcome and follow-up. AIMS: We aimed to assess (1) reasons for performed major ablative surgeries such as hip disarticulation and hemipelvectomy in a German center for trauma and orthopedic surgery. (2) In addition, mortality and quality of life after hip disarticulation and hemipelvectomy as well as (3) patient and treatment characteristics should be investigated. METHODS: During a period of twelve years, 15 patients underwent hip disarticulation or hemipelvectomy. Mortality, EQ-5D-3L quality of life by EQ-5D-3L and time-trade-off (TTO), VAS, cause of disarticulation, length of hospital stays, revisions, comorbidities, Charlson comorbidity index (CCI), and ASA score were evaluated retrospective for all patients. RESULTS: The overall mortality rates were 26.7% at 30 days, 60.0% after one year and 66.7% after three years. The five surviving patients reported about moderate problems in the EQ-5D-3L. The average VAS score reached 45 (range 15-65). The mean TTO was 9.8 (range 6-12). Indications for amputation were infection (n = 7), tumor (n = 6), trauma (n = 1) and ischemia (n = 1). CONCLUSION: Hip disarticulation and hemipelvectomy are followed by a high postoperative mortality. Quality of life of the affected patients is impaired in long-term follow-up. Especially amputations performed due to infections show high mortality within one month after surgery despite average young age and low CCI. Surgeons should be aware of this devastating outcome and extraordinary vigilant for these vulnerable patient cohorts.

Custom designed and 3D-printed titanium pelvic implants for acetabular reconstruction after tumour resection.

BACKGROUND: Reconstructive procedure following resection of large pelvic tumours around the hip joint remains a complex challenge. METHODS: This study presents a retrospective case series of patients presenting with benign or malignant pelvic tumour for which an internal hemipelvectomy including the hip joint and subsequent reconstruction with a custom designed 3-dimensional printed titanium pelvic implant (3DPPI) has been performed between August 2013 and January 2018. RESULTS: 15 consecutive patients with a median age of 33.9 years (IQR 26.4-72.2) and a median BMI of 20.7 kg/m2 (IQR 19.0-33.3) were reviewed after median follow-up of 33.8 months (IQR 24.0-78.1). The majority of patients presented with a malignant tumour as their principal diagnosis (n = 13, 86.7%). The median surgical time was 5.5 hours (IQR 4.5-8.5) and median peri-operative blood loss was 5000 ml (IQR 2000-10000). The median MSTS score at follow-up was 63.3% (IQR 51.7-86.7%). The median NRS in rest was 0.0 (IQR 0.0-5.0), the median NRS during activity was 2.0 (IQR 0.5-7.0) and the median HOOS-PS was 76.6% (IQR 67.9-91.0). 4 patients had implant-specific complications (n = 4, 26.6%); 1 hip dislocation (Henderson type 1a), 3 structural complications (type 3a), 1 deep infection (type 4a) and 1 local tumour recurrence (type 5b). At follow-up, 4 out of 15 implants were classified as a failure, resulting in an implant survival rate of 73.3%. CONCLUSIONS: Acceptable peri-operative outcomes, functional results, complication rates and short-term implant survival can be achieved in a cohort of complex patients undergoing 3DPPI reconstruction after hemipelvectomy including the acetabulum.

Long-term physical and psychological outcome following traumatic hemipelvectomy.

PURPOSE: First time examination of the physical and psychological long-term outcome following traumatic hemipelvectomy. METHODOLOGY: In this study, all patients suffering from traumatic hemipelvectomy that were treated in a level-A trauma center since 1988 were retrospectively evaluated. The authors aimed to compare the physical and psychological outcome following primary amputation (A) vs. limb-preservation (LP) procedures. The patients were examined with a focus on pain, function, mobility and general health. As part of this examination, various scores were recorded, i.e., Majeed Score, Time up & Go or SF-36. RESULTS: The following work showed 13 patients who had suffered a traumatic hemipelvectomy, 8 of whom survived. Five of these were available for subsequent clinical re-examination; of these, three patients underwent an amputation, while limb preservation was performed on two patients. Mean follow-up of the amputee group was after 12 years compared to 6.5 years following limb preservation. After limb preservation, both patients reported phantom limb pain at the affected leg, despite pain medication. The general state of health was assessed as 82/100 (A) and 45/100 (LP). The Majeed score was 61 (A) vs. 45 (LP). In the clinical examination, three out of five patients (2 LP, 1 A) showed peroneal palsy (PP). In the quality-of-life analysis based on the SF12/36 and the NHP, amputees scored higher than the patients who underwent limb preservation surgery. CONCLUSION: In our small patient cohort, satisfaction, pain and mobility tend to be better following primary amputation compared to limb preserving surgery.

Outcomes and Complications of Pelvic Chondrosarcomas Treated Using Navigation Guidance and Multidisciplinary Approach: Is the Tumor Volume a Prognostic Factor?

(1) Background: Pelvic Chondrosarcomas (CS) have a poor prognosis. The grade is the most important survival predictor; other factors are periacetabular location and Dedifferentiated CS subtype. The aim of the study is to investigate a series of CS of the pelvis, to analyze the prognostic factors that affect outcomes and to demonstrate how the use of intraoperative navigation can reduce the complications without worse outcomes. (2) Methods: Retrospective study on 35 patients (21 M, 14 F), median age at surgery 54 years (IQR 41−65), with pelvic CS, treated with hemipelvectomy under navigation guidance. (3) Results: 30 high-grade CS and 5 low-grade CS; mean follow-up 51.4 months. There was a positive linear correlation between the tumor volume and the presence of local recurrence at follow-up. The mean survival time of patients with larger chondrosarcoma volume was lower, but not significantly so. Lower MSTS score was associated with significantly lower survival time (p < 0.001). (4) Conclusion: in this series overall survival, LR and distant metastasis were comparable with recent literature, while complication rate was lower compared to similar series without the use of navigation. There was a correlation between tumor volume and local recurrence rate but not with the presence of metastasis at follow up.

Internal Hemipelvectomy for primary bone sarcomas using intraoperative patient specific instruments- the next step in limb salvage concept.

BACKGROUND: During pelvic Sarcoma resections, Surgeons often struggle to obtain negative margins while minimizing collateral damage and maintaining limb function. These complications are usually due to the complex anatomy of the pelvis. Here we present an accurate 3D surgical approach, including pre-operative printing of models and intraoperative patient-specific instruments (PSIs) for optimizing pelvic sarcoma resections. METHODS: This single-center retrospective study (N = 11) presents surgical, functional, and oncological outcomes of patients (average age 14.6 +/- 7.6 years, 4 males) who underwent pelvic sarcoma resections using a 3D surgical approach between 2016 and 2021. All patients were followed up for at least 24 months (mean = 38.9 +/- 30.1 months). RESULTS: Our results show promising surgical, oncological, and functional outcomes. Using a 3D approach, 90.9% had negative margins, and 63.6% did not require reconstruction surgery. The average estimated blood loss was 895.45 ± 540.12 cc, and the average surgery time was 3:38 ± 0.05 hours. Our results revealed no long-term complications. Three patients suffered from short-term complications of superficial wound infections. At 24 month follow up 72.7% of patients displayed no evidence of disease. The average Musculoskeletal Tumor Society (MSTS) score at 12 months was 22.81. CONCLUSION: 3D technology enables improved accuracy in tumor resections, allowing for less invasive procedures and tailored reconstruction surgeries, potentially leading to better outcomes in function and morbidity. We believe that this approach will enhance treatments and ease prognosis for patients diagnosed with pelvic sarcoma and will become the standard of care in the future.

Comparative study of pelvic sarcoma patients undergoing internal and external hemipelvectomy: A meta-analysis study.

Introduction: Malignant and giant pelvic tumors are complex and rare, and hemipelvectomies are complex procedures performed for this malignant lesion. Only a few studies had been conducted on the survival and recurrence of pelvic sarcomas patients undergoing internal or external hemipelvectomy. In the present study, we compared internal with external hemipelvectomy in pelvic sarcomas on clinical outcomes by a meta-analysis. Methods: The survival and recurrence rates of pelvic sarcomas patients were collected from research reports from CNKI, MEDLINE, EMBASE, the Cochrane Database, and Google Scholar until April 2022. The quality of included articles was evaluated by two independent reviewers. Differences between patients undergoing internal and external hemipelvectomy were analyzed based on postoperative survival and recurrence rates. Results: Five articles were included according to selection criteria. There were 183 patients in total from these studies. Our results showed that there was no significant difference between limb salvage surgery and amputation according to survival; however, patients with internal hemipelvectomy had a lower recurrence rate. Conclusions: Internal hemipelvectomy results in a lower recurrence rate and similar survival rate, while not increasing the risk of metastasis and complications. This study provided more pieces of evidence to support internal hemipelvectomy as a favorable treatment of pelvic sarcomas.

Computational evaluation of psoas muscle influence on walking function following internal hemipelvectomy with reconstruction.

An emerging option for internal hemipelvectomy surgery is custom prosthesis reconstruction. This option typically recapitulates the resected pelvic bony anatomy with the goal of maximizing post-surgery walking function while minimizing recovery time. However, the current custom prosthesis design process does not account for the patient's post-surgery prosthesis and bone loading patterns, nor can it predict how different surgical or rehabilitation decisions (e.g., retention or removal of the psoas muscle, strengthening the psoas) will affect prosthesis durability and post-surgery walking function. These factors may contribute to the high observed failure rate for custom pelvic prostheses, discouraging orthopedic oncologists from pursuing this valuable treatment option. One possibility for addressing this problem is to simulate the complex interaction between surgical and rehabilitation decisions, post-surgery walking function, and custom pelvic prosthesis design using patient-specific neuromusculoskeletal models. As a first step toward developing this capability, this study used a personalized neuromusculoskeletal model and direct collocation optimal control to predict the impact of ipsilateral psoas muscle strength on walking function following internal hemipelvectomy with custom prosthesis reconstruction. The influence of the psoas muscle was targeted since retention of this important muscle can be surgically demanding for certain tumors, requiring additional time in the operating room. The post-surgery walking predictions emulated the most common surgical scenario encountered at MD Anderson Cancer Center in Houston. Simulated post-surgery psoas strengths included 0% (removed), 50% (weakened), 100% (maintained), and 150% (strengthened) of the pre-surgery value. However, only the 100% and 150% cases successfully converged to a complete gait cycle. When post-surgery psoas strength was maintained, clinical gait features were predicted, including increased stance width, decreased stride length, and increased lumbar bending towards the operated side. Furthermore, when post-surgery psoas strength was increased, stance width and stride length returned to pre-surgery values. These results suggest that retention and strengthening of the psoas muscle on the operated side may be important for maximizing post-surgery walking function. If future studies can validate this computational approach using post-surgery experimental walking data, the approach may eventually influence surgical, rehabilitation, and custom prosthesis design decisions to meet the unique clinical needs of pelvic sarcoma patients.

Late Distal Ureteral Stricture in Internal Hemipelvectomy Without Bone Reconstruction: A Case Report.

We report the case of a patient with Ewing sarcoma involving the right pelvis in a 14-year-old girl who had multicycles of neo-adjuvant chemotherapy and preoperative radiation therapy. She underwent an internal hemipelvectomy type I resection, according to Enneking and Dunham's classification without bony reconstruction. There was no intra- and perioperative complication. The patient has good function and needs no gait aids. She can walk with equinus foot compensated for leg shortening 5 centimeters and without a shoe-lift. There is no sign of disease relapse. However, she developed late ureteral stricture at 8-year postoperatively and was successfully treated with a ureteral stent.

Reconstruction of Type I-II Internal Hemipelvectomy in a Patient With Pelvic Myxoid Chondrosarcoma: A Case Report.

Pelvic chondrosarcomas are a major clinical challenge since the only therapeutic approach available is surgical resection. Reconstruction after partial resection of the pelvis including the acetabulum or the hip joint is a laborious and rigorous surgical procedure. Numerous complications are associated with different reparative methods. Moreover, due to the anatomical complexities of the area, adequate surgical margins are difficult to achieve in many cases, which are closely related to the advent of local recurrence of the tumor. Several techniques for hip function restoration and skeletal reconstruction have been reported. The purpose of this report is to describe a novel pelvic reconstruction technique for PI-II resection that required a custom-designed implant. We present the case of a 61-year-old female patient with chronic pain in the gluteal region. The pelvis's magnetic resonance imaging (MRI) showed an osteolytic tumor in the right iliac wing that compromises the acetabular roof. The diagnosis was a grade 2 central chondrosarcoma. Surgery included the reconstruction of the acetabulum by inserting two Schanz pins coated with hydroxyapatite, one in the iliopubic corridor and the other in the ischium. A supporting "pyramid" was built, unitizing both Schanz with cement, onto which an acetabular cage was inserted. The procedure was completed with a conventional total hip prosthesis. The patient presented an acute prosthesis infection, which positively responded to prompt surgical lavage and antibiotic treatment. After 10 months of follow-up, the patient remains free of infection, with weight-bearing as tolerated, without pain, and with excellent hip motion. No tumor recurrence has occurred. Medialization of the construct has occurred as expected, with no evidence of implant loosening. The technique used in this patient is novel, could be considered cost-effective, and has allowed the reconstruction of a functional hip. For resections of the acetabular area and preservation of the ischium and pelvic zones, this technique may be an acceptable option.

Combined and Modified Gibson and Ilioinguinal Approaches in Type II + III Internal Hemipelvectomy for Periacetabular Tumors.

Background: The routine iliofemoral approach and its modifications in type II+III resection require extensive skin incision and massive periacetabular muscle detachment, leading to prolonged hospital stay, increased complication incidence, and impaired lower limb function. Under the management of an enhanced recovery after surgery (ERAS) protocol, a combined and modified Gibson and ilioinguinal (MGMII) approach was used to avoid unnecessary soft tissue trauma during tumor resection and therefore advantageous to patients' return to normal life. Methods: Twenty-five patients with type II + III (including type II) periacetabular tumors who underwent reconstruction with 3D printed customized endoprostheses at our center between January 2017 and March 2019 were included in this study. There were 13 cases using MGMII approach and 12 cases using iliofemoral approach. The operation duration and blood loss were assessed by chart review. The surgical margin was evaluated by the histopathological studies. The reconstruction accuracy, the abductor muscle strength, the 1993 version of the Musculoskeletal Tumor Society (MSTS-93), the Harris Hip scores (HHS), and the limp score were evaluated. Complications were recorded after reviewing the patients' records. Results: The operative duration and blood loss in MGMII group were shorter than those in the iliofemoral group, but the postoperative hemoglobin was slightly higher than that in the iliofemoral group. The MGMII group had stronger postoperative hip abductors, better functional restoration, and relatively fewer patients with higher limp scores. No complication was observed in the MGMII group. In the iliofemoral group, three patients encountered wound healing delay, and one patient suffered deep infection. Conclusions: The MGMII approach can better expose the posterior column of the acetabulum, especially the ischial tuberosity, which is beneficial for avoiding tumor rupture during resection. The MGMII approach also helps to preserve residual muscle function, such as the origin of the gluteus medius, while ensuring the extent of resection.

Preoperative arterial embolization and wound complications after resection of malignant bone tumor in the pelvis: a nationwide database study.

BACKGROUND: Massive intraoperative blood loss is common in pelvic malignant bone tumor surgery, and preoperative arterial embolization may be used in selected cases. Preoperative arterial embolization reportedly increases wound complications in pelvic fracture surgery, but little evidence is available regarding pelvic bone tumor surgery. METHODS: Using a Japanese nationwide database (Diagnosis Procedure Combination database), we searched for patients who underwent pelvic malignant bone tumor surgery between July 2010 and March 2018. The primary endpoint was wound complications, defined as any wound requiring re-operation, negative pressure wound therapy or both. Univariate analyses (the chi-squared test for categorical variables, the unpaired t-test for continuous variables) and multivariate logistic regression analyses were performed to examine the association between preoperative arterial embolization and wound complications. RESULTS: Among the 266 eligible patients, 43 (16%, 43/266) underwent embolization and 69 (26%, 69/266) developed wound complications. In the univariate analyses, preoperative arterial embolization (P < 0.001), duration of anesthesia (P < 0.001), the volume of blood transfusion (P < 0.001) and duration of indwelling drain tube (P < 0.001) were associated with wound complications. In the multivariate logistic regression analysis, preoperative arterial embolization was significantly associated with wound complications (odds ratio, 3.92; 95% confidence interval, 1.80-8.56; P = 0.001). CONCLUSIONS: Preoperative arterial embolization may be associated with increased wound complications after pelvic malignant tumor surgery.

Pelvic Endoprosthesis after Hemipelvectomy Using a 3D-Printed Osteotomy Guide for Infiltrative Osteoma in a Cat.

With the development of 3D printing and surgical techniques, various defect reconstruction methods after tumor resection have been applied not only in humans but also in veterinary medicine. This report describes a case of reconstruction after hemipelvectomy for an osteoma in a cat using a 3D-printed pelvic endoprosthesis and micro total hip replacement (mTHR). A 5-year-old spayed female Turkish Angora cat was referred for a 1-month history of constipation and intermittent weight-bearing lameness in the left hindlimb. An osteoma in the pelvis measuring 4.5 × 3 × 5.4 cm was identified based on diagnostic examinations. A left mid-to-caudal partial and right caudal partial hemipelvectomy, and a left femoral head and neck osteotomy, were planned to remove the mass. Reconstruction of the bone defect using 3D-printed metal endoprosthesis and mTHR in the left hindlimb was intended. During right caudal partial hemipelvectomy, right femoral head and neck osteotomy was performed because there was infiltration in the medial wall of the acetabulum. Histopathological examination confirmed the diagnosis of an osteoma. Two weeks post-surgery, surgical debridement and femoral stem removal were performed because of delayed wound healing and sciatic neurapraxia, leading to femoral stem dislocation from the cup. The delayed wound healing and sciatic neurapraxia were appropriately addressed. The cat regained normal weight and defecation 4 weeks post-operatively. Two years post-surgery, the patient recovered with an almost normal gait. Hemipelvectomy with 3D-printed endoprosthesis provides a safe surgical option with favorable outcomes for neoplasms in the pelvis of cats.