Hiromitsu Takano

Finite Element Analysis of Osteoporotic Vertebrae with First Lumbar (L1) Vertebral Compression Fracture

The aim of this work is to assess the biomechanical response or load transfer response between osteoporotic (with first lumbar (L1) vertebral compression fracture) and healthy vertebrae in five vertebral physiological motions namely as compression, flexion, extension, lateral bending and axial rotation. For this purpose, an image-basedheterogeneous three-dimensional patient-specific of lumbar and thoracic spinal unit (T12-L2) finite element models for healthy and osteoporotic subjects were created. The finite element analysis have shown that one of the most significant effects of osteoporosis is the tendency to produce higher stress and strain in the cancellous region of the vertebral body. The maximum stress and strain was 4.53 fold (compression) and 5.43 fold (axial rotation) higher for the osteoporotic than the healthy subject, respectively, under the similar loading activity. Uneven stress distribution patterns also have been detected in the osteoporotic vertebrae rather than the healthy vertebrae. All of these characteristicsare reflected by a reduced structural strength and bone mass which might lead to an increased risk of fracture. These results strengthen the paradigm of a strong relationship between osteoporosis and its high susceptibility to fracture.

Surgical treatment for lumbar hyperlordosis after resection of a spinal lipoma associated with spina bifida: A case report

Rationale: A hyperlordosis deformity of the lumbar spine is relatively rare, and surgical treatment has not been comprehensively addressed. In this case report, we describe the clinical presentation, surgical treatment, and medium-term follow-up of a patient presenting with a progressive lumbar hyperlordosis deformity after resection of a spinal lipoma associated with spina bifida. Patient concerns: The patient was a 20-year-old woman presenting with a progressive hyperlordosis deformity of the lumbar spine associated with significant back pain (visual analog pain score of 89/100 mm), but with no neurological symptoms. Diagnoses: The lumbar lordosis (LL), measured on standing lateral view radiographs, was 114°, with a sagittal vertical axis (SVA) of −100 mm. The patient had undergone excision of a lipoma, associated with spina bifida of the lumbar spine, at 7 months of age. She was first evaluated at our hospital at 18 years of age for progressive spinal deformity and lumbago. Interventions: An in situ fusion, from T5 to S1, using pedicle screws with bone graft obtained from the iliac crest, was performed. Outcomes: Postoperatively, the LL decreased to 93°, and the SVA decreased to −50 mm. The decision to not correct the hyperlordosis deformity fully was intentional. Seven years and 1 month postsurgery, the patient had no limitations in standing and walking and reported a pain score of 8/100 mm; there was no evidence of a loss of correction. Lessons: Lumbar hyperlordosis after resection of a spinal lipoma associated with spina bifida is rare. Posterior fixation provided an effective treatment in this case. As the lumbar hyperlordosis deformity is often high, correction can be difficult. In this case, although the correction and fusion were performed in situ, there was no progression of either the deformity or the lumbago. Early detection remains an essential component of effective treatment, allowing correction when the spinal deformity is easily reversible.

Biomechanical Effects of Implant Materials on Posterior Lumbar Interbody Fusion: Comparison of Polyetheretherketone and Titanium Spacers Using Finite Element Analysis and Considering Bone Density

Few biomechanical data exist regarding whether the polyetheretherketone (PEEK) spacer or titanium spacer is better for posterior lumbar interbody fusion (PLIF). This study evaluated the biomechanical influence that these types of spacers with different levels of hardness exert on the vertebra by using finite element analysis including bone strength distribution. To evaluate the risk of spacer subsidence for PLIF, we built a finite element model of the lumbar spine using computed tomography data of osteoporosis patients. Then, we simulated PLIF in L3/4 and built models with the hardness of the interbody spacer set as PEEK and titanium. Bones around the spacer were subjected to different load conditions. Then, fracture elements and some stress states of the two modalities were compared. In both models of PLIF simulation, fracture elements and stress were concentrated in the bones around the spacer. Fracture elements and stress values of the model simulating the PEEK spacer were significantly smaller compared to those of the titanium simulation model. For PLIF of osteoporotic vertebrae, this suggested that the PEEK spacer is in a mechanical environment less susceptible to subsidence caused by microfractures of bone tissue and bone remodeling-related fusion aspects. Therefore, PEEK spacers are bio-mechanically more useful.

Spontaneous improvement of cervical kyphosis in eosinophilic granuloma: a case report

We describe the case of a spontaneous improvement of the cervical kyphosis in eosinophilic granuloma with long-term follow-up. A collapse of the C5 vertebral body was confirmed by cervical spine radiography and computed tomography. The patient wore a sterno-occipitalmandibular immobilizer brace for 6 months, and remodeling of the vertebral body was confirmed 18 months after onset. Seven years have passed since the onset of symptoms, and the patient’s cervical spine has maintained normal alignment. Management of eosinophilic granuloma of the pediatric cervical spine is still controversial. Conservative treatment suffices as adequate management of cervical eosinophilic granuloma, even with kyphotic deformity.

Postoperative paraplegia caused by spinal cord compression secondary to drains and back muscles in a sumo wrestler with ossification of the posterior longitudinal ligament of the thoracic spine: A case report

This report describes a rare case of paraplegia immediately after posterior decompression and instrumented fusion surgery (PDF) for the ossification of posterior longitudinal ligament of the thoracic spine (T-OPLL). The principal causes of paralysis following posterior decompression and instrumented fusion surgery (PDF) for the ossification of the posterior longitudinal ligament of the thoracic spine (T-OPLL) are progressive kyphosis and epidural hematoma [1e6]. This paper presents a very rare case with postoperative paraplegia, detected at the time of the patients awakening from anesthesia. Our extensive searching failed to reveal any reported case where paraplegia arose due to compression by a pair of drains and a lump of back muscles.