Kümmell's Disease: Clarifying the Mechanisms and Patients' Inclusion Criteria.

The three major causes of vertebral body collapse include infection, malignant neoplasia, and trauma and it may be difficult to distinguish between them, particularly in the presence of severe osteoporosis. In 1891, however, Dr Hermann Kümmell, further added another possibility of vertebral body crush; the delayed posttraumatic collapse. As originally described, this rare clinical entity includes patients, who after a trivial trauma and an asymptomatic clinical course they develop a progressive vertebral body collapse and a painful kyphosis. Although more than a century has passed from its initial description, only few cases have been reported in the literature, whereas the main pathologic eliciting event is still under investigation. As a consequence, great controversy exists regarding the discrete features of the clinical course, its radiographic appearance and the histopathological findings. To explain the time lag between the initial trauma and the occurrence of the vertebral collapse, the hypothesis of ischemic necrosis was advanced. Equation of Kümmell's disease with vertebral osteonecrosis, however, has wrongly led many authors to report cases of Kümmell's disease, even in the absence of history of spinal trauma. On the other hand, high coincidence of vertebral osteonecrosis and the pathognomonic radiographic finding of intravertebral vacuum cleft, has further added to the confusion. In this review we present an overview of the literature on Kümmell's disease, focusing on the different proposed eliciting mechanisms. We also highlight controversial subjects on clinical course, diagnosis and treatment of this entity, in an attempt to further clarify patients' inclusion criteria.

Kümmell's disease: pathophysiology, diagnosis, treatment and the role of nuclear medicine. Rationale according to our experience.

Kümmell's disease (KD) is a rare clinical entity and includes patients, who after a trivial trauma and an asymptomatic period, develop a progressive vertebral body collapse and a painful kyphosis. The main pathologic eliciting event still remains unclear. Vertebral body collapse can be the result of infection, malignant neoplasia or trauma. It may be difficult to distinguish among them, particularly in osteoporosis. To explain the time lag between initial trauma and vertebral collapse, the hypothesis of ischemic necrosis was suggested. Many authors considering KD as a case of mere vertebral osteonecrosis have wrongly reported cases of osteonecrosis without a spinal trauma, as KD. The fact that intravertebral vacuum cleft often coexists with vertebral osteonecrosis further added to confusion. Various imaging modalities including bone scan support the diagnosis of KD. It is described that bone single photon emission tomography (SPET) or SPET/computed tomography scintigraphy using dynamic and static, acquisition can identify the chronicity of the lesions.

In vitro study of biomechanical behavior of anterior and transforaminal lumbar interbody instrumentation techniques.

OBJECTIVE: To study the biomechanical behavior of lumbar interbody instrumentation techniques using titanium cages as either transforaminal lumbar interbody fusion (TLIF) or anterior lumbar interbody fusion (ALIF), with and without posterior pedicle fixation. METHODS: Six fresh-frozen lumbar spines (L1-L5) were loaded with pure moments of +/-7.5 Nm in unconstrained flexion-extension, lateral bending, and axial rotation. Specimen were tested intact, after implantation of an ALIF or TLIF cage "stand-alone" in L2-L3 or L3-L4, and after additional posterior pedicle screw fixation. RESULTS: In all loading directions, the range of motion (ROM) of the segments instrumented with cage and pedicle screw fixation was below the ROM of the intact lumbar specimen for both instrumentation techniques. A significant difference was found between the TLIF cage and the ALIF cage with posterior pedicle screw fixation for the ROM in flexion-extension and axial rotation (P < 0.05). Without pedicle screw fixation, the TLIF cage showed a significantly increased ROM and neutral zone compared with an ALIF cage "stand-alone" in two of the three loading directions (P < 0.05). CONCLUSION: With pedicle screw fixation, the ALIF cage provides a higher segmental stability than the TLIF cage in flexion-extension and axial rotation, but the absolute biomechanical differences are minor. The different cage design and approach show only minor differences of segmental stability when combined with posterior pedicle screw fixation.

Patient attitudes toward granting consent to participate in perioperative randomized clinical trials.

STUDY OBJECTIVE: To determine the factors that affect patients' decisions to provide informed consent to participate in perioperative clinical trials. DESIGN: Survey instrument (questionnaire). SETTING: Urban, tertiary-care, university-affiliated hospital. MEASUREMENTS AND MAIN RESULTS: Of 52 patients who had been asked to participate in a randomized control trial (RCT), 43 agreed to be participate in our survey. Almost all consenters (97%), but only 62% of nonconsenters agreed to answer the survey questions (p = 0.002). No significant difference in gender, ethnic background, marital status, or education level was found between groups who were or were not willing to participate. Univariate correlates of agreement to participate in RCTs included older age (>60 yrs;p = 0.02), a reassuring attitude conveyed by study personnel (p = 0.02), and trust in study personnel (p = 0.02). Those who declined participation in clinical trials more frequently indicated that the study made them feel like a "guinea pig" (p = 0.02). CONCLUSION: Patient age and personal attitudes predict the likelihood of participation in perioperative clinical trials. Neither gender nor race affected willingness to participate. Further work in larger groups is needed to identify predictors of consent and techniques to increase willing participation.