Polymethylmethacrylate Reconstruction Research Articles

Giant Cell Tumor: A Case Series of Seven Patients with GCT at Atypical Sites.

Giant cell tumor (GCT) represents 5% of all primary bone tumors and 20% of biopsy analyzed benign tumors. More than half of these lesions occur in the 3rd and 4th decades of life. There is no absolute treatment method selection. Techniques ranging from intralesional curettage to wide resection can be used. Goal is to eradicate the tumor, preserve limb function, and prevent local recurrence and distant metastasis. We are presenting seven cases of GCT at five different and rare sites involving tibia, calcaneum, metatarsal, proximal humerus, and clavicle with tumor being limited to bone in all seven cases not involving the soft tissue. There were three male patients and four female patients. Six patients underwent intralesional curettage using high-speed burr and curette, along with adjuvant irrigation with hydrogen peroxide and normal saline followed by polymethyl methacrylate reconstruction. One patient with GCT clavicle underwent wide resection. In all seven cases, we were able to able to remove the tumor completely. Six patients had a gradual and complete recovery with return to near normal activity within 6 month-1 year after surgery. One patient with proximal humerus GCT had a recurrence which got resolved with injection denosumab. All patients have been followed up for a minimum duration of 2 years. Intervention in the early stages can avoid radical procedures such as wide local excision or amputation. We recommend aggressive surgical approach with close follow-up to detect recurrence if any, at an early stage.

Treatment of Spinal Metastases with Epidural Cord Compression through Corpectomy and Reconstruction via the Traditional Open Approach versus the Mini-Open Approach: A Multicenter Retrospective Study.

Patients with metastatic epidural spinal cord compression (MESCC) often need surgical intervention due to pain, neurological deficits, and spinal instability. Spinal disease is commonly treated via the minimally invasive mini-open approach. However, few studies have evaluated MESCC treatment via mini-open approach. The present study compared the traditional open approach versus the mini-open approach for thoracolumbar MESCC. A cohort of 209 consecutive patients who were diagnosed with thoracolumbar metastases and underwent corpectomy and polymethylmethacrylate reconstruction from 2010 to 2016 was retrospectively identified. Traditional open surgery was performed in 113 patients (open group; mean age 57.7 years), while 96 patients underwent mini-open surgery (mini-open group; mean age 54.3 years). Patients were followed up for 24 months or until death. The baseline characteristics of both groups were similar. The most common origin of the primary lesion was the lung (37.3%), hematological system (22.0%), and kidney (15.8%). Surgery effectively achieved pain relief, restored neurological function, and improved quality of life in both groups. The mini-open group was superior to the open group regarding estimated blood loss, blood transfusion, hospital stay, complications, and pain score. While the mini-open group had a longer operation time than the open group, the two groups had similar improvements in the Frankel grade and Karnofsky functional score. The 30-day mortality rate tended to be higher in the open group (5.3%) than the mini-open group (2.1%) without significance. The 24-month survival rate was similar in both groups (26.5% versus 26.0%). In conclusion, surgery improved pain, function, and quality of life in patients with MESCC. The mini-open approach resulted in less estimated blood loos, less blood transfusion, and shorter hospitalization than the traditional open approach, while both methods had similar mortality and morbidity rates. Thus, the mini-open approach may be more beneficial than the traditional approach for MESCC.

A Preliminary Report on the Use of Antibiotic-Impregnated Methyl Methacrylate in Salvage Cranioplasty

In the setting of recurrent infection and multiple failed reconstruction attempts, the choice of the ideal reconstructive material for salvage cranioplasty remains a source of controversy in the literature. The purpose of this study is to establish the safety and utility of antibiotic-impregnated polymethyl methacrylate (PMMA) for salvage cranioplasty.A prospectively maintained database of all patients who underwent salvage cranioplasty using vancomycin and tobramycin-impregnated methyl methacrylate from January 2011 to July 2013 was reviewed. Vancomycin and tobramycin were mixed in PMMA, which was then applied to a rigidly fixed titanium mesh for reconstruction. Patients' demographics, indications, and outcomes of this technique were evaluated.Nine patients (mean age: 47 years) underwent vancomycin and tobramycin-impregnated PMMA reconstruction with a mean follow-up of 9.3 months (range 3.5-23 months). On average, these patients underwent 4 procedures (range: 1-15), which included repeat craniotomy, debridement for infection, and failed reconstructions over the course of 3.6 years (range: 7 months to 14 years) before salvage cranioplasty. All patients required salvage cranioplasty due to infection, with the most common bacteria isolated in culture being Propionibacterium acnes (n = 3), multiresistant coagulase-negative Staphylococcus (n = 3), methicillin-resistant Staphylococcus aureus (n = 2), and Enterobacter (n = 2). The average size of the craniectomy defect was 130 cm(2), and there were no incidences of postoperative infection, postoperative complications, or need for revisions.To conclude, in short-term follow-up, vancomycin and tobramycin-impregnated PMMA reconstruction appears safe and effective in salvage cranioplasty. Our early report represents a proof of concept--the true test is whether these short-term successes translate to stable long-term results.

Computer-Aided Design and Manufacture and Rapid Prototyped Polymethylmethacrylate Reconstruction

This article discusses the application of computer-aided design and rapid prototyping techniques in polymethylmethacrylate reconstruction of craniofacial bone defects. This method avoids the probability of tissue damage due to exothermic reaction during the polymerization process and provides precise implants that exactly fit the defects. A total of 11 patients who have various-sized craniofacial defects underwent polymethylmethacrylate reconstruction. We performed three-dimensional reconstruction and operative design using computer software. According to the design, we determined the shape and size of the implants and made individualized implants for craniofacial bone defects with the rapid prototyping technique. With the application of computer-aided design and a rapid prototyping technique, we could accurately determine the shape, size, and embedding location. Prefabricating the individual implant models is useful in improving the accuracy of treatment. No cases of infection, seroma, extrusion, or contour irregularity occurred as a complication, and all patients were satisfied with the results. During the follow-up period, ranging from 1 to 6 years, all patients remained satisfied, and no complications were sustained. In cases of various-sized cranial defects and complex maxillofacial defects that have enough soft tissue coverage and that do not have contact with a third space, prefabricated methyl methacrylate implants can be used safely. Patients will feel more comfortable if the postoperative shape resembles the original appearance, so the proposed algorithm effectively creates a customized implant.

Potential for thermal damage to articular cartilage by PMMA reconstruction of a bone cavity following tumor excision: A finite element study

Benign, giant cell tumors are often treated by intralesional excision and reconstruction with polymethylmethacrylate (PMMA) bone cement. The exothermic reaction of the in-situ polymerizing PMMA is believed to beneficially kill remaining tumor cells. However, at issue is the extent of this necrotic effect into the surrounding normal bone and the adjacent articular cartilage. Finite element analysis (ABAQUS 6.4-1) was used to determine the extent of possible thermal necrosis around prismatically shaped, PMMA implants (8–24 cc in volume), placed into a peripheral, sagittally symmetric, metaphyseal defect in the proximal tibia. Temperature/exposure time conditions indicating necrotic potential during the exotherm of the polymerizing bone cement were found in regions of the cancellous bone within 3 mm of the superior surface of the PMMA implant. If less than 3 mm of cancellous bone existed between the PMMA implant and the subchondral bone layer, regions of the subchondral bone were also exposed to thermally necrotic conditions. However, as long as there were at least 2 mm of uniform subchondral bone above the PMMA implant, the necrotic regions did not extend into the overlying articular cartilage. This was the case even when the PMMA was in direct contact with the subchondral bone. If the subchondral bone is not of sufficient thickness, or is not continuous, then care should be taken to protect the articular cartilage from thermal damage as a result of the reconstruction of the tumor cavity with PMMA bone cement.

SURGICAL RESECTION PLUS ADJUVANT RADIOTHERAPY IS SUPERIOR TO SURGERY OR RADIOTHERAPY ALONE IN THE PREVENTION OF NEUROLOGICAL DECLINE IN A RAT METASTATIC SPINAL TUMOR MODEL

The optimal management of spinal column metastatic disease is controversial. Furthermore, the literature lacks an accurate animal model to study the efficacy of surgical treatment options for spinal column metastases. We compared the efficacy of surgery, radiotherapy, or surgery plus adjuvant radiotherapy in a rat model of metastatic epidural spinal cord compression. Thirty-two Fischer 344 rats underwent a transabdominal approach for implantation of a CRL-1666 breast adenocarcinoma cell line within the vertebral body of L6. Animals were randomly assigned to receive one of four treatments (n = 8 per group) 7 days after tumor implantation: 1) control: no treatment; 2) external beam radiation therapy (XRT) (total 20 Gy in 400-cGy daily fractions); 3) surgery: L6 vertebral corpectomy, tumor resection, and polymethyl methacrylate reconstruction; and 4) surgery + XRT: corpectomy and tumor resection followed by XRT (total 20 Gy in 400-cGy daily fractions) 72 hours after surgery. Hind-limb function was tested daily after treatment using the Basso-Beattie-Bresnahan (BBB) scale (range, 1-21). All animals (n = 32) demonstrated normal hind-limb function (BBB score, 21) on posttreatment Day 1. The XRT, surgery, and surgery + XRT groups all experienced a delay in onset of paresis versus the control group. Compared to the XRT group, the surgery group demonstrated greater median BBB scores on Days 3 (21 versus 20, P = 0.02) through 9 (12 versus 8, P = 0.002) after treatment. Compared with the surgery group, the surgery + XRT group demonstrated even greater median BBB scores on Days 6 (21 versus 19, P = 0.0008) through 11 (16 versus 8, P = 0.0001) after treatment. Median time to loss of ambulation (BBB <or= 7) was greatest in the surgery + XRT group (15 d) when compared with the surgery (12 d, P = 0.001), XRT (9 d, P = 0.001), or control groups (7 d, P = 0.0005). In a rat model of metastatic epidural spinal cord compression, decompressive surgery followed by radiotherapy yielded the greatest efficacy in the prevention of neurological decline when compared with surgery or radiotherapy alone. Radiotherapy alone attenuated neurological decline but was the least efficacious treatment in this model. These results support this animal model as an effective platform to investigate novel interventions for metastatic spine tumors.

Titanium Cage-assisted Polymethylmethacrylate Reconstruction for Cervical Spinal Metastasis: Technical Note

Reconstruction and stabilization of the cervical spine after vertebrectomy is an important goal in the surgical management of spinal metastasis. The authors describe their reconstruction technique using a titanium cage-Silastic tube construct injected with polymethylmethacrylate (PMMA) augmented by an anterior cervical plate. The surgical results using this technique are reviewed. Six patients ranging from 43 to 70 years of age underwent resection of metastatic tumor in the cervical spine followed by cage-assisted PMMA reconstruction of the anterior spinal column. The following reconstruction technique was performed. A Silastic tube is incised longitudinally and placed circumferentially around a titanium cage with the opening facing anteriorly. The cage-Silastic tube construct is carefully tapped into the corpectomy defect and filled with PMMA. The final construct is then augmented with anterior cervical plate fixation. Two patients required additional posterior stabilization with lateral mass screws and rods. All patients achieved immediate stabilization, restoration of vertebral body height and normal lordosis, and preservation of the ability to walk independently. Five patients experienced significant palliation of biomechanical neck pain. There were no complications of neurological worsening, postoperative hematoma, wound infection, subsidence, graft dislodgement, or construct failure during a follow-up period of 1 to 19 months (mean, 6.8 mo). Titanium cage-assisted PMMA reconstruction augmented with an anterior cervical plate is an effective means of reconstruction after tumor resection in patients with cervical spinal metastasis. The Silastic tube holds the PMMA within the cage and protects the spinal cord from potential thermal injury.

Anterior Stabilization of the Upper Thoracic Spine via an “Interaortocaval Subinnominate Window”

Because of the limitations imposed by the thoracic cage and the paravertebral structures, anterior access to T3 remains a challenge, particularly for the application of anterior fixation devices. Specifically, the appropriate trajectory for the correct placement of T3 screws requires significant caudal access; this may necessitate the addition of a high-level thoracotomy to the traditional combined neck exposure/sternotomy approach to the cervicothoracic junction (ie, the "trap door" exposure). The authors describe a technique for the placement of the T3 screws of a T1-T3 spinal titanium alloy plate via an "interaortocaval subinnominate window" in a patient who underwent a T2 vertebrectomy and polymethylmethacrylate reconstruction. The case history, imaging studies, illustrations, and intraoperative photographs are presented. This novel technique allows for the optimal placement of anterior fixation devices in the upper thoracic spine without the need to extend the caudal exposure with an anterolateral thoracotomy.

Durability and strength of Steinmann pin augmentation in cemented tibial defects.

It has been argued that Steinmann pin augmentation does not improve the biomechanics of polymethylmethacrylate reconstruction for massive defects of bone. The current authors investigated whether pin augmentation of polymethylmethacrylate in the reconstruction of noncontained defects of bone improved the biomechanical properties of the reconstruction as compared with polymethylmethacrylate alone when minimal or large bone porosity is present. Large noncontained defects were created in 10 pairs of human tibias. In Group 1, five left tibias had reconstruction with polymethylmethacrylate augmented with three, 5-mm diameter by 10-mm deep holes into lateral condyle cancellous bone. Right tibias had identical reconstruction with three, 3/16-inch threaded pins placed into the medullary canal. In Group 2, three, 10-mm diameter by 10-mm deep holes were created in both pairs. The left tibia had polymethylmethacrylate reconstruction and the right tibia had polymethylmethacrylate and pin augmentation. Specimens were subjected to 2000 compressive cycles then loaded to failure. In Group 1, cycles and load to failure were significantly lower in reconstructions without pins compared with reconstructions with pins. No significant difference was observed between reconstruction techniques in Group 2. In reconstructions without pins, large diameter holes had significantly better cyclical durability. Pins improved survival compared with no pins.

Coaxial double-lumen methylmethacrylate reconstruction in the anterior cervical and upper thoracic spine after tumor resection.

A unique method of anterior spinal reconstruction after decompressive surgery was used to prevent methylmethacrylate-dural contact in cancer patients who underwent corpectomy. The purpose of this study was to assess the efficacy and stability of polymethylmethacrylate (PMMA) anterior surgical constructs in conjunction with anterior cervical plate stabilization (ACPS) in these patients. Approximately 700 patients underwent spinal surgery at The University of Texas M. D. Anderson Cancer Center over a 4-year period. The authors conducted a retrospective outcome study for 29 of these patients who underwent anterior cervical or upper thoracic tumor resections while in the supine position. These patients were all treated using the coaxial, double-lumen, PMMA technique for anterior spinal reconstruction with subsequent ACPS. No postoperative external orthoses were used. Twenty-seven patients (93%) harbored metastatic spinal lesions and two (7%) harbored primary tumors. At 1 month postsurgery, significant improvement was seen in spinal axial pain (p<0.001), radiculopathy (p<0.001), gait (p = 0.008), and Frankel grade (p = 0.002). A total of nine patients (31%) underwent combined anterior-posterior 360 degrees stabilization. Twenty-one patients (72%) experienced no complications. Complications related to instrumentation failure occurred in only two patients (7%). There were no cases in which the patients' status worsened, and there were no neurological complications or infections. The median Kaplan-Meier survival estimate for patients with spinal metastases was 9.5 months. At the end of the study, 13 patients (45%) had died and 16 (55%) were alive. Postoperative magnetic resonance images consistently demonstrated that the dura and PMMA in all patients remained separated. The anterior, coaxial, double-lumen, PMMA reconstruction technique provides a simple means of spinal cord protection in patients in the supine position while undergoing surgery and offers excellent results in cancer patients who have undergone cervical vertebrectomy.

Gelfoam as a Barrier to Prevent Polymethylmethacrylate-Induced Thermal Injury of the Spinal Cord

Gelatin sponge (Gelfoam; Upjohn, Kalamazoo, MI, U.S.A.) is commonly used as an interpositional barrier to shield the spinal cord from thermal injury during vertebral reconstruction with polymethylmethacrylate bone cement. The aim of this study was to record epidural and intradural temperatures during polymethylmethacrylate reconstruction of vertebral corpectomy defects. Three surgical techniques (subtotal corpectomy, total corpectomy with insertion of a Gelfoam barrier, and total corpectomy with no barrier) were compared in vivo and in vitro in a porcine model. As expected, total corpectomy defects cemented without a Gelfoam barrier produced the highest epidural temperatures in vivo (52.8 degrees C) and in vitro (58 +/- 2 degrees C). The Gelfoam barrier provided some protection against heat transfer, but peak temperatures and absolute temperature increases were significantly higher than in defects with an intact posterior cortex (p < 0.05). These results indicate that an intact posterior cortex provides the best protection against heat transfer, whereas the use of a Gelfoam barrier appears to provide only partial protection against thermal injury.