Orthopedics

Feature Article 

Kyphoplasty for the Treatment of Kümmell's Disease

Huilin Yang, MD, PhD; Minfeng Gan, MD; Jun Zou, MD; Xin Mei, MD; Xiaofeng Shen, MD; Genlin Wang, MD, PhD; Liang Chen, MD, PhD

  • Orthopedics. 2010;33(7)
  • Posted July 1, 2010

Abstract

The peripheral cortex of a vertebral body affected by Kümmell’s disease is not always intact, resulting in high risk for cement leakage. This study used modified techniques to avoid cement extravasation and dislodgment and investigated the feasibility and efficacy of kyphoplasty for treatment of Kümmell’s disease.

Between May 2006 and May 2008, 21 consecutive patients with Kümmell’s disease underwent kyphoplasty with modified techniques. Each patient was assessed preoperatively with standard examinations and imaged with dynamic radiographs, 3-dimensional computed tomography scans, and magnetic resonance imaging. A visual analog scale (VAS) and the Oswestry Disability Index were used to measure pain and disability pre- and postoperatively and at 6- and 12-month follow-up. One patient had cement leakage into the disk space but no clinical symptoms. There were no cases of cement dislodgment at follow-up. Comparison of the pre- vs postoperative VAS scores revealed significant differences (P<.05), whereas VAS scores at 6- vs 12-month follow-up were similar. The Oswestry Disability Index scores varied from 62.3%±15.1% preoperatively to 35.2%±12.1% postoperatively (P<.05). This improvement in scores was still present at 6- and 12-month follow-up. At 6- and 12-month follow-up, maintenance of height restoration and kyphotic deformity correction was found.

Kyphoplasty may be a relatively safe and effective method for treatment of Kümmell’s disease when modified techniques are used to prevent cement leakage and dislodgment.

The German surgeon Hermann Kümmell described a clinical scenario in which individuals sustained a “trivial” spinal trauma, were essentially asymptomatic for weeks to months, and then developed a symptomatic, progressive, angular kyphosis.1,2 Shortly thereafter, the eponym Kümmell’s disease was coined in his honor to refer to avascular necrosis of the vertebral body. More recently, multiple synonymous terms have been used to describe this pathology, including posttraumatic vertebral osteonecrosis; vertebral pseudarthrosis; intervertebral vacuum, cleft, or gas; delayed vertebral collapse; and vertebral compression fracture nonunion.3-8

The incidence of this condition is difficult to report accurately because of the multiple synonymous terms used to describe it. Regardless of terminology, the true incidence is high (7%-37%), especially among the elderly population.4,5 Patients with Kümmell’s disease suffer from severe back pain, but no effective treatment of Kümmell’s disease has been established to date.

Several investigations have demonstrated that vertebroplasty and kyphoplasty can alleviate the pain caused by Kümmell’s disease and stabilize the compromised vertebral body.3,9-12 Vertebroplasty and kyphoplasty are minimally invasive procedures for the treatment of vertebral compression fracture due to osteoporosis or tumors. Kyphoplasty was developed from vertebroplasty. An inflatable balloon tamp is used to create a cavity in the fractured vertebral body, after which polymethylmethacrylate (PMMA) is injected into the cavity. Compared with vertebroplasty, kyphoplasty is more effective at reducing kyphosis and restoring the height of the vertebral body. The risk of cement extravasation is theoretically reduced because the cement can be injected under lower pressure.

However, the peripheral walls of vertebral bodies with Kümmell’s disease are not always intact, potentially resulting in a higher incidence of bone cement leakage during cement augmentation. In addition, not all authors have investigated methods for reducing the risk of cement leakage. Wagner and Baskurt13 and Tsai et al14 showed that cement dislodgment is likely to occur after augmentation with cement during treatment of osteoporotic vertebral fractures with intervertebral cleft and anterior cortical defect. To minimize the risk of cement extrusion and avoid cement dislodgment, we used kyphoplasty with certain technical modifications to treat patients with Kümmell’s disease at our institution. For patients with damage to the anterior wall of the vertebral body, small amounts of middle- or late-stage bone cement in the dough phase were used to fill the defect first. Late-stage bone cement in the paste…

Abstract

The peripheral cortex of a vertebral body affected by Kümmell’s disease is not always intact, resulting in high risk for cement leakage. This study used modified techniques to avoid cement extravasation and dislodgment and investigated the feasibility and efficacy of kyphoplasty for treatment of Kümmell’s disease.

Between May 2006 and May 2008, 21 consecutive patients with Kümmell’s disease underwent kyphoplasty with modified techniques. Each patient was assessed preoperatively with standard examinations and imaged with dynamic radiographs, 3-dimensional computed tomography scans, and magnetic resonance imaging. A visual analog scale (VAS) and the Oswestry Disability Index were used to measure pain and disability pre- and postoperatively and at 6- and 12-month follow-up. One patient had cement leakage into the disk space but no clinical symptoms. There were no cases of cement dislodgment at follow-up. Comparison of the pre- vs postoperative VAS scores revealed significant differences (P<.05), whereas VAS scores at 6- vs 12-month follow-up were similar. The Oswestry Disability Index scores varied from 62.3%±15.1% preoperatively to 35.2%±12.1% postoperatively (P<.05). This improvement in scores was still present at 6- and 12-month follow-up. At 6- and 12-month follow-up, maintenance of height restoration and kyphotic deformity correction was found.

Kyphoplasty may be a relatively safe and effective method for treatment of Kümmell’s disease when modified techniques are used to prevent cement leakage and dislodgment.

The German surgeon Hermann Kümmell described a clinical scenario in which individuals sustained a “trivial” spinal trauma, were essentially asymptomatic for weeks to months, and then developed a symptomatic, progressive, angular kyphosis.1,2 Shortly thereafter, the eponym Kümmell’s disease was coined in his honor to refer to avascular necrosis of the vertebral body. More recently, multiple synonymous terms have been used to describe this pathology, including posttraumatic vertebral osteonecrosis; vertebral pseudarthrosis; intervertebral vacuum, cleft, or gas; delayed vertebral collapse; and vertebral compression fracture nonunion.3-8

The incidence of this condition is difficult to report accurately because of the multiple synonymous terms used to describe it. Regardless of terminology, the true incidence is high (7%-37%), especially among the elderly population.4,5 Patients with Kümmell’s disease suffer from severe back pain, but no effective treatment of Kümmell’s disease has been established to date.

Several investigations have demonstrated that vertebroplasty and kyphoplasty can alleviate the pain caused by Kümmell’s disease and stabilize the compromised vertebral body.3,9-12 Vertebroplasty and kyphoplasty are minimally invasive procedures for the treatment of vertebral compression fracture due to osteoporosis or tumors. Kyphoplasty was developed from vertebroplasty. An inflatable balloon tamp is used to create a cavity in the fractured vertebral body, after which polymethylmethacrylate (PMMA) is injected into the cavity. Compared with vertebroplasty, kyphoplasty is more effective at reducing kyphosis and restoring the height of the vertebral body. The risk of cement extravasation is theoretically reduced because the cement can be injected under lower pressure.

However, the peripheral walls of vertebral bodies with Kümmell’s disease are not always intact, potentially resulting in a higher incidence of bone cement leakage during cement augmentation. In addition, not all authors have investigated methods for reducing the risk of cement leakage. Wagner and Baskurt13 and Tsai et al14 showed that cement dislodgment is likely to occur after augmentation with cement during treatment of osteoporotic vertebral fractures with intervertebral cleft and anterior cortical defect. To minimize the risk of cement extrusion and avoid cement dislodgment, we used kyphoplasty with certain technical modifications to treat patients with Kümmell’s disease at our institution. For patients with damage to the anterior wall of the vertebral body, small amounts of middle- or late-stage bone cement in the dough phase were used to fill the defect first. Late-stage bone cement in the paste phase or early-stage bone cement in the dough phase was then applied to allow the filling to diffuse evenly. For patients with damage to the posterior or lateral wall of the vertebral body, continuous fluoroscopic monitoring was used throughout the bone cement-filling process.

Materials and Methods

This study was a single-cohort observational study using prospectively collected data to examine pre- and postoperative outcomes and radiographic measures in 21 consecutive patients with Kümmell’s disease.

From May 2006 to May 2008, 21 patients (16 women and 5 men) were diagnosed with Kümmell’s disease at our institution. All patients underwent radiographic, computed tomography (CT), and magnetic resonance imaging (MRI). The following MRI sequences were used: (1) sagittal T2-weighted images, (2) sagittal T1-weighted spin-echo images, and (3) sagittal short-inversion-time inversion recovery (STIR) images. Computed tomography images showed intravertebral vacuums and identified the location of defects in vertebral body walls. On T2-weighted images and STIR images on sagittal MRI, all patients exhibited high-signal intensity that was suggestive of fluid collection. All patients had severe back pain. The duration of their symptoms ranged from 2 weeks to 1 year. Mean patient age was 66 years (range, 60-81 years). The locations and numbers of the treated vertebrae were as follows: T11 (n=5), T12 (n=7), L1 (n=5), and L2 (n=4).

Kyphoplasty

Our kyphoplasty procedure has been described elsewhere.15-17 The procedure involved bilateral insertion of KyphX Inflatable Bone Tamps (Kyphon Inc, Sunnyvale, California) into the compromised vertebral body. The balloons were first inflated to elevate the endplates, reduce the fracture, and create a cavity. They were then deflated and withdrawn, and PMMA was placed in the cavity in the treated vertebral body. For patients with damage to the anterior wall of the vertebral body, small amounts of middle- or late-stage bone cement in the dough phase were first used to block the defect to protect against anterior leakage of bone cement. After the filling had solidified, late-stage bone cement in the paste phase or early-stage bone cement in the dough phase was applied to allow the filling to diffuse evenly. For patients with damage to the posterior or lateral wall of the vertebral body, continuous fluoroscopic monitoring was performed throughout the bone cement-filling process. The filling process was stopped as soon as the bone cement reached the lateral margin or when one-fourth of the distance to the posterior wall of the vertebral body was left (Figures 1-7).

Figure 1: Intervertebral cleft of T12 Figure 2: Lateral wall defect

Figure 1: Preoperative sagittal CT scan showing the intervertebral cleft of T12 and anterior and posterior wall defects. Figure 2: Preoperative coronal CT scan showing a lateral wall defect.


Figure 3A: No cement leakage occurred Figure 3B: No cement leakage occurred

Figure 3: Postoperative radiographs showing that no cement leakage occurred (A, B).


Figure 4: Intervertebral cleft at L1 Figure 5: Lateral wall defect

Figure 4: Preoperative sagittal CT scan showing an intervertebral cleft at L1 and an anterior wall defect. Figure 5: Preoperative coronal CT scan showing a lateral wall defect.


Figure 6: No cement leakage Figure 7: No cement dislodgement occurred

Figure 6: Postoperative radiograph showing that no cement leakage occurred. Figure 7: Twelve-month follow-up radiograph showing that no cement dislodgement occurred.

Assessment of Clinical Outcomes, Radiographic Parameters, and Cement Leakage

Clinical outcomes and radiographic parameters were evaluated pre- and postoperatively and at 6- and 12-month follow-up. We assessed clinical outcomes with the visual analog scale (VAS) pain score (range, 1-10) and the Oswestry Disability Index. Vertebral body height measurements (anterior and midline) were obtained from standing lateral radiographs for compromised and adjacent uncompromised control vertebrae. For each patient and each radiograph, the normal height of the compromised vertebra was estimated from the mean of the measured heights of the closest uncompromised vertebrae cephalad and caudad to the treated level. Height was expressed as a percent of the normal adjacent control vertebral height: (height of compromised vertebrae/mean height of adjacent control vertebrae)×100. The kyphotic angle was calculated from the standing lateral radiographs using Cobb’s methods. The measurement was taken from the superior endplate of the vertebra 1 level above the treated vertebra to the inferior endplate of the vertebra 1 level below the treated vertebrae.

The occurrence of cement leakage out of the vertebral body was determined by fluoroscopy at the time of kyphoplasty. Postoperative radiographs were also reviewed for cement leakage. The presence and position of leakage were recorded and correlated with clinical symptoms.

Statistical Analysis

Comparison of VAS scores, Oswestry Disability Index scores, the height of the compromised vertebral body, and the kyphotic angle between preoperative measurements and at each follow-up were performed with the paired Student t test. A P value <.05 was considered to be significant. All statistical analyses were performed using SPSS 13.0 software (SPSS, Inc, Chicago, Illinois).

Results

All patients tolerated kyphoplasty well. Nineteen patients returned for their 12-month follow-up visit.

Clinical Outcomes

The mean VAS score improved significantly from pre- to postoperatively, decreasing from 8.9±2.1 to 2.9±1.1 (P<.05). Scores were maintained at 3.1±1.9 at 6 months postoperatively and increased slightly, but not significantly, after 1 year to 3.3±2.1. The Oswestry Disability Index score varied from 62.3%±15.1% preoperatively to 35.2%±12.1% postoperatively (P<.05). Improvement was maintained at the 6- and 12-month follow-up visits (Table 1).

Table 1: Mean VAS and ODI Improvements

Table 2: Mean Restoration of Anterior and Midline Height of Vertebrae and Kyphotic Angle

Radiographic Outcome

After kyphoplasty, the anterior height of the vertebrae was restored from 63.5%±8.9% to 84.4%±11.2%, the midline height of vertebrae increased from 72.1%±9.8% to 81.3%±10.1%, and the kyphotic angle decreased from 16.8°±7.1° to 7.8°±6.1°. At 6- and 12-month follow-ups, maintenance of the height restoration and kyphotic deformity correction was observed (Table 2).

Cement Leakage

Cement extravasation was seen at 1 level in 1 patient in whom the cement had entered the disk space. As soon as the leakage was seen under fluoroscopy, the cement injection was stopped. No clinical symptoms were identified after kyphoplasty that might have resulted from the extravasation. There were no instances of cement dislodgment at follow-up.

Discussion

Kümmell’s disease has been referred to as vertebral pseudarthrosis, vertebral compression fracture nonunion, and intravertebral cleft. Dynamic motion of this intravertebral mobility is the cause of severe back pain.18 In addition, clefts predict failure of medical management no matter how long the patient is observed or braced. Therefore, stability of the vertebral body is the most important goal for treatment of Kümmell’s disease. A complete corpectomy with a fibular strut or cage replacement is 1 option for treatment of Kümmell’s disease; pedicle screws with posterolateral fusion may be another. However, patients with Kümmell’s disease are generally middle-aged or elderly and may have hypertension, diabetes mellitus, chronic obstructive pulmonary disease, or other comorbidities. Moreover, patients with Kümmell’s disease always suffer from osteoporosis and may not be able to tolerate the operations discussed here or potential failure of an implant. All of the patients in our investigation had osteoporosis and at least 1 other disease. We therefore opted not to perform these operations for their Kümmell’s disease unless the patients had cord compression or radicular symptoms.

Vertebroplasty and kyphoplasty can also stabilize the fractured vertebral body and alleviate pain.15,19 Therefore, these treatments are now extensively used to treat fractures due to osteoporosis or neoplasms. Although several reports have demonstrated that either vertebroplasty or balloon kyphoplasty can provide stability and pain relief for the treatment of Kümmell’s disease,3,9-12 the peripheral walls (especially the anterior and posterior walls) of affected vertebral bodies are not always intact. Cement may leak into the prevertebral tissues from the cleft of the anterior wall and may even burn the adjacent great vessels during vertebroplasty or kyphoplasty. This would result in a catastrophic complication. Additionally, cement dislodgment may occur under weight bearing because of an anterior cortical defect.13,14 If the posterior wall is disrupted, displacement of the bony fragment may be further aggravated during vertebroplasty or kyphoplasty, and the cement may leak into the spinal canal. The bony fragment or the cement could injure the spinal cord and nerve root.

Many reports have proven that the risk of cement leakage during kyphoplasty is lower than for vertebroplasty.20-22 In our opinion, kyphoplasty may be more suitable for treatment of Kümmell’s disease for several reasons: the balloon tamp is inserted into the vertebral body to create a cavity, after which the cement can be injected under lower pressure and high viscosity; when the balloon tamp creates the cavity, the compressed cancellous bone can cover the clefts to some extent; and if the involved ligaments are structurally intact, distention of the vertebral body can tauten the ligaments, while the intact anterior and posterior longitudinal ligaments and paravertebral soft tissue can help to prevent cement leakage and related complications.

To reduce the risk of cement leakage in our investigation, we used modified techniques during kyphoplasty.16,17 Preoperative CT scanning was performed to identify areas in the walls of the vertebral bodies that were not intact. For patients with anterior wall defects, small amounts of middle- or late-stage bone cement in the dough phase were used initially to cover the defect, thus helping to prevent cement extravasation. After the cement had hardened, late-stage bone cement in the paste phase or early-stage bone cement in the dough phase was placed. Krause et al23 reported that doughy cement on an unclean surface resulted in low interface strength compared to a low-viscosity cement made to penetrate a cleaned bone surface. In our investigation, the late-stage bone cement in the paste phase or early-stage bone cement in the dough phase might have mechanically interlocked with the cancellous bone because of the interdigitation of the polymethylmethacrylate. This is likely to have helped avoid cement dislodgment under weight bearing. For patients with lateral or posterior wall defects, continuous fluoroscopic monitoring was performed during the injection, and injection was stopped immediately when the cement approached the lateral margin or posterior wall of the vertebral body.

All patients in our investigation were treated with kyphoplasty and modified techniques. The pain caused by Kümmell’s disease was alleviated immediately after kyphoplasty. Height restoration and correction of the kyphotic deformity were found. Only 1 patient was identified in whom cement had leaked into the disk space, and no clinical symptoms were reported. At follow-up, no instances of cement dislodgment were found.

References

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Authors

Drs Yang, Gan, Zou, Mei, Wang, and Chen are from the Department of Orthopedics, The First Affiliated Hospital of Soochow University, and Dr Shen is from Suzhou Hospital of Traditional Chinese Medicine, Suzhou, JiangSu, China.

Drs Yang, Gan, Zou, Mei, Shen, Wang, and Chen have no relevant financial relationships to disclose.

Correspondence should be addressed to: Minfeng Gan, MD, Department of Orthopedics, The First Affiliated Hospital of Soochow University, 188 ShiZi St, Suzhou, JiangSu, 215006, China (spineganmf@126.com).

doi: 10.3928/01477447-20100526-07

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