1150 Kyphoplasties Over 7 Years: Indications, Techniques, and Intraoperative Complications

By Nicholas McArthur, MD; Christian Kasperk, MD; Martin Baier, MD; Michael Tanner, MD; Bernd Gritzbach, MD; Oliver Schoierer, MD; Wolfram Rothfischer, MD; Gerhard Krohmer, MD; Jochen Hillmeier, MD; Hans-Jürgen Kock, MD; Peter Jürgen Meeder, MD; Franz-Xaver Huber, MD
ORTHOPEDICS 2009; 32:90

Abstract

In our cohort of 555 patients with a total of 1150 vertebral fractures treated with kyphoplasty we performed a 30-day postoperative analysis of cement leakage, neurological symptoms, pulmonary embolism, and infections. In our department, 22% of kyphoplasties were performed with calcium phosphate cement and the remainder with polymethylmethacrylate. All patients were initially assessed by an interdisciplinary kyphoplasty colloquium, composed of consultants in traumatology, radiology, and endocrinology. Indications included fresh traumatic vertebral fractures; painful sintered osteoporotic vertebrae; osteolysis and painful vertebral body collapse caused by multiple myelomas; and lymphomas and pathological fractures due to metastases of malignant tumors (prostate cancer, breast cancer, ovarian cancer, and malignant melanoma) or benign vertebral tumors (hemangioma).

Contraindications included patients with instability of the posterior wall and/or pedicles, an infection of the fractured vertebra, a severe hemorrhagic diathesis, known allergies to the cements, pregnancy, and ASA score of 4. The standard postoperative computed tomography scan of the kyphoplasty-treated vertebrae revealed a dorsal cement leakage in 38 vertebrae representing 3.3% of all levels. A permanent monoparesis of the left leg, 2 cases of temporary neurological deficits, 2 cases of hemorrhage, and 1 asymptomatic pulmonary embolism were observed as postoperative complications. We observed no complications relating to polymethylmethacrylate described in the literature. By careful interdisciplinary indication setting and a standardized treatment model, kyphoplasty presents a safe and effective procedure for the treatment of various vertebral fractures.

Balloon kyphoplasty has only recently been considered as an established operative procedure. The first successful application of a similar procedure ie, vertebroplasty was performed in France by Galivert und Deramond in 1987 on a patient who sustained a vertebral fracture due to osteolysis caused by a multiple myeloma.^1,2 In contrast to vertebroplasty, kyphoplasty restores vertebral body height and spinal alignment in the sagittal plane, by first creating a void in the fractured vertebra with the help of an inflatable balloon and then filling this void with an injection of polymethylmethacrylate or absorbable calcium phosphate.^3-10 The aim of balloon kyphoplasty is pain relief, stabilization, and height restoration of fractured vertebrae.^4,6-8,10,11

 

Cement leakage through the vertebral body boundaries is the most frequently described complication and is rarely related to clinical manifestations.¹² Nevertheless such manifestations include paraplegia and pulmonary embolism.^13,14 Other complications include local or systemic reactions to the cement.^15,16

In our consecutive series of 555 patients, we performed a 30-day postoperative analysis of cement leakage, neurological symptoms, allergic reactions, pulmonary embolism, and infections. Our indication for kyphoplasty was applied to vertebral fractures with various causalities including osteoporosis, multiple myeloma, and traumatic fractures. No literature exists that describes postoperative complications of >1000 kyphoplasties at the same center. We have therefore conducted a retrospective study at our institution of all 1150 kyphoplasties we performed over the past 7 years.

Materials and Methods

Patient Cohort

Five hundred fifty-five patients with a total of 1150 vertebral fractures between December 2001 and April 2008 were treated with kyphoplasty at our institution. The indication for each patient was determined by an interdisciplinary kyphoplasty colloquium, which was composed of senior consultants in internal medicine, traumatology, and radiology.

Indications include: fresh traumatic vertebral fractures, painful sintered osteoporotic vertebrae, osteolysis and painful vertebral body collapse caused by multiple myelomas and lymphomas, and pathological fractures due to metastases of malignant tumors (prostate cancer, breast cancer, ovarian cancer and malignant melanoma) or benign vertebral tumors (hemangioma).

We treated all levels between the fifth thoracic and the fifth lumbar vertebrae.

In a fresh vertebral fracture with a stable posterior wall the patient was initially mobilized under the care of a physiotherapist and adequate pain treatment. Four weeks later we evaluated the progress of any further loss of vertebral height with conventional radiographs. Simultaneously, the course of the localized pain symptoms of the patient was also assessed. If the patient expressed only little or no improvement of pain, the case was referred to our kyphoplasty colloquium for further evaluation. Kyphoplasty was then normally performed within 2 weeks of the indication setting.

Fresh fractures with a posterior wall instability were stabilized with an internal fixator.

Contraindications included patients with instability of the posterior wall and/or pedicles, an infection of the fractured vertebra, a severe hemorrhagic diathesis, known allergies to the cement, pregnancy, and ASA score of 4.

All patients with multiple myelomas and metastatic carcinomas were treated pre- and postoperatively by oncologists. Multiple myeloma patients often received an autologous stem cell transplantation prior to kyphoplasty.

Operative Technique

Following administration of general anesthesia, the patient was placed on a carbon fiber radiolucent C-Arm table (Figure 1). Extra padding was placed beneath the head, chest, pelvis and extremities. The procedure was performed under an intravenous dose of 1.5 g Cefuroxime (Fresenius Kabi Deutschland GmbH, Bad Homburg, Germany). The position of the fractured vertebrae was then localized with the aid of fluoroscopy. After disinfection and draping, the pedicels of the fractured vertebrae were then displayed under fluoroscopy using the C-Arm.

Kyphoplasty was performed according to the procedure described by DaFonseca et al³ and Voggenreiter et al.¹⁷ Two types of bone cement were used, KyphX HV-R (Kyphon Inc, Sunnyvale, California) and Calcibone (Biomet Merck, Berlin, Germany).

A number of precautions were taken to reduce cement extravasation as one of the most common kyphoplasty complications. These included a thorough analysis of the CT scans, especially of the posterior wall; exact placement of the balloons and removal only immediately prior to cement delivery; injection of the cement at the correct viscosity; and continuous fluoroscopic monitoring during cement delivery to rapidly spot any form of extravasation.

Postoperative Management

During the first 24 hours following kyphoplasty circulation, motor and sensory functions of the extremities were monitored every 2 hours. Besides the conventional radiographs in 2 planes, a CT scan of the area of interest was also used to establish any cement leakage (Figure 2). After the first postoperative day patients were mobilized under the supervision of physiotherapists. Clinical and radiological follow-up are conducted at 1, 3, 6, and 12 months postoperatively and then once yearly or sooner if necessary.

Results

The data of 555 patients with 1150 kyphoplasty treated vertebrae were analyzed retrospectively (Table 1) (Figures 3, 4).

Standard postoperative CT of the kyphoplasty treated vertebrae revealed a dorsal cement leakage in a total of 38 vertebrae (3.3%). In 1 case the cement leakage filled 50% of the spinal canal leading to motor deficits of both legs. The neurological deficits diminished following surgical removal of the cement (Figure 5). Two patients had postoperative bleeding requiring a surgical revision. In 1 case an epidural bleeding at level L1 led to neurological motor deficits of the right leg, which diminished after decompression of the spinal cord by laminectomy. The other patient reported severe postoperative pain together with severe swelling due to a subcutaneous hematoma in the area of the surgical incision. Following surgical evacuation of the hematoma the patient reported no further complications. In both cases, a preoperative intake of thrombocyte aggregation inhibitors was not identified.

Pulmonary embolism was detected in an anteroposterior radiograph of the thoracic spine in 1 patient. One patient, however, sustained a permanent monoparesis of the left leg following a misguided puncture of the spinal cord with the Jamshidi needle. This was the seventh patient treated with kyphoplasty at our institution. An apparent infection in the area of the incision was not detected in any of our patients. Furthermore our patients showed no local or systemic reactions with polymethylmethacrylate or calcium phosphate cements (Table 2).

Discussion

The yearly incidence of osteoporotic vertebral fractures alone is estimated at 700,000 in the United States and 1.4 million in Europe.^18,19 Conservative treatment strategies include analgesics, physiotherapy, or even immobilization. Thus far the functional results following conservative therapy have been unsatisfying.^20,21 Furthermore kyphoplasty presents not only a minimally invasive procedure for the treatment of osteoporotic fractures but can also be used to stabilize osteolytic tumors or fresh vertebral traumatic fractures.^22-24

Indication for kyphoplasty was always determined for each patient after consultation with our interdisciplinary kyphoplasty colloquium.²⁵ A detailed patient history, thorough clinical examination, neurological assessment and a comprehensive radiological diagnostic with CT and MRI are obligatory prerequisites for determining the indication for kyphoplasty. Additionally, measures depending on the etiology of the vertebral fractures were also taken pre- and postoperatively to optimize the overall treatment of the patient ie, patients with osteoporosis received calcium, vitamin D, and bisphosphonates; tumor patients received consultation from a specialized oncologist.^25,26

Conventional radiographs of the thoracic and lumbar spine in 2 planes are the standard preoperative diagnostic. These radiographs however do not allow for a clear differentiation between fresh, old, or even tumor-related vertebral fractures.^3,27 Oblique angle radiographs allowing assessment of the intervertebral foramina and facette joints or spotfilm radiographs of fractured vertebrae are not regarded as helpful. The CT is required for the exact assessment of the posterior vertebral wall and the MRI is not only needed to differentiate between fresh and old vertebral fractures, but also allows us to detect the involvement of any possible tumor presence, spinal cord compression, or hematomas in the spinal canal with a high degree of sensitivity.^3,8,10

We only perform kyphoplasty under general anesthesia on a radiolucent carbon fiber table.³ General anesthesia ensures immobilization of the patient during the procedure and also permits further surgical treatment if necessary.^3,27,28 The bilateral transpedicular approach is standard³ as it has a greater advantage in the reduction of kyphosis, and the loss of reduction was less than the unilateral approach for the treatment of osteoporotic vertebral compression fractures.²⁹ Chung et al also suspected that the bilateral approach reduced the chance of violating the medial pedicle wall.

According to a recent study by Wilke et al, which simulated daily stresses and strains of a kyphoplasty treated vertebrae, no significant difference in biomechanical vertebral stability could be shown between the 2 types of cement used, polymethylmethacrylate and calcium phosphate.³⁰ A microscopical assessment of the kyphoplasty treated vertebrae, however, revealed cracks in the calcium phosphate within the vertebrae. This study only dealt with the use of kyphoplasty in healthy vertebrae, thus making it impossible to make use of this knowledge in the treatment of osteoporotic or tumor infested vertebrae. In our department 22% of kyphoplasties were performed with calcium phosphate cement and the remainder with polymethylmethacrylate.

We observed no local or systemic allergic reactions, rapid falls in blood pressure, or toxic effects described in the literature even though they would be expected in such a large patient collective.¹⁵ A 5-year follow-up describing the osseointegration of polymethylmethacrylate in vertebrae has yet to be published, thus making the application of a metabolizable bone cements in younger patients reasonable.³¹

The 2 cases of postoperative hemorrhage resulted from an unknown regular intake of aspirin intake (ASS 100 HEXAL; HEXAL AG, Holzkirchen, Germany). The intake of any form of anticoagulation must clearly be determined while taking a patient´s history.

The most commonly described complication of kyphoplasty is the extravertebral cement leakage through fracture fissures or the vertebral vein system.^9,32-34 Such a leakage into the spinal canal can in rare occasions result in minor neurological deficits or even paraplegia.^13,14 The case, which resulted in a dorsal cement extravasation requiring surgical revision, can be attributed to the fact that only a preoperative MRI, but inadvertently no CT scan, was taken of the fractured vertebrae. This patient had a multiple myeloma, and a significant posterior wall instability in the MRI was overlooked, which ultimately led to this complication. This oversight explains why we view a CT scan as a mandatory standard preoperative diagnostic. This isolated case led to this serious complication. It has also shown us that an MRI alone is not adequate enough for the assessment of vertebral fracture morphology.

An asymptomatic pulmonary embolism was an incidental finding on 1 of the anteroposterior radiographs of the thoracic spine. Oxygen saturation was always monitored during intraoperatively and immediately postoperatively. Patients were further clinically monitored for signs of pulmonary embolism eg, syncope, dyspnea, and shock. We observed no patients with postoperative clinical symptoms of pulmonary embolism. If any other pulmonary emboli were present in our patient cohort, they were also asymptomatic.

The case that led to a permanent monoparesis of the left leg following a misguided puncture of the spinal cord with the Jamshidi needle, was the seventh to be treated with kyphoplasty at our institution. This was undoubtedly due to a technical error of the surgeon, who had little experience with this procedure. We recommend that kyphoplasty always be performed under the supervision of a surgeon who has substantial experience with the procedure.

Few reports exist of polymethylmethacrylate reactions related to kyphoplasty. A study from Nussbaum et al has described anaphylactic reactions to polymethylmethacrylate in vertebroplasty leading to cardiac and/or respiratory arrest and death. The deaths normally occurred after kyphoplasty of multiple levels (>8).¹⁶ Another study from Garfin et al described 1 patient with whom has had transient fever and hypoxia after placement of polymethylmethacrylate in a liquid form.¹³ We observed none of these reactions in our patient cohort.

Higher intraoperative mortality rates attributable to the use of polymethylmethacrylate cement have been reported (0.14%) during hip hemiarthroplasty.³⁵

The small amounts of polymethylmethacrylate in our study of 4 to 13 mL used in kyphoplasty appear less likely to lead to such reactions. Further studies are necessary to verify this assumption.

Conclusions

By careful interdisciplinary indication setting and a standardized treatment model, kyphoplasty presents a safe and effective procedure for the treatment of a vast spectrum of vertebral fractures.

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Authors

Drs McArthur, Tanner, Gritzbach, Schoierer, Rothfischer, Krohmer, Meeder, and Huber are from the Surgical Clinic, Division of Traumatology and Reconstructive Surgery, Dr Kasperk is from Abteilung Innere Medizin I, University of Heidelberg, Dr Hillmeier is from Abteilung für Unfall- und orthopädische Chirurgie, Limburg, and Dr Kock is from Klinik für Unfall- und Wiederherstellungschirurgie, Bad Homburg, Germany; and Dr Baier is from Överläkare Ortopedi, Karlshamn, Sweden.

Drs McArthur, Baier, Tanner, Gritzbach, Schoierer, Rothfischer, Krohmer, Kock, and Huber have no relevant financial relationships to disclose. Drs Kasperk, Hillmeier, and Meeder have acted as advisors for Medtronic Inc.

Correspondence should be addressed to: Franz-Xaver Huber, MD, Surgical Clinic, Division of Traumatology and Reconstructive Surgery, University of Heidelberg, Im Neuenheimer Feld 110, D-69120 Heidelberg, Germany.