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Shunsuke Kanbara, Yasutsugu Yukawa, Keigo Ito, Masaaki Machino and Fumihiko Kato

The lumbar spinous process–splitting laminectomy (LSPSL) procedure was developed as an alternative to lumbar laminectomy. In the LSPSL procedure, the spinous process is evenly split longitudinally and then divided at its base from the posterior arch, leaving the bilateral paravertebral muscle attached to the lateral aspects. This procedure allows for better exposure of intraspinal nerve tissues, comparable to that achieved by conventional laminectomy while minimizing damage to posterior supporting structures. In this study, the authors make some modifications to the original LSPSL procedure (modified LSPSL), in which laminoplasty is performed instead of laminectomy. The purpose of this study was to compare postoperative outcomes in modified LSPSL with those in conventional laminectomy (CL) and to evaluate bone unions between the split spinous process and residual laminae following modified LSPSL.

Forty-seven patients with lumbar spinal stenosis were enrolled in this study. Twenty-six patients underwent modified LSPSL and 21 patients underwent CL. Intraoperative blood loss and surgical duration were evaluated. The Japanese Orthopaedic Association (JOA) scale scores were used to assess parameters before surgery and 12 months after surgery. The recovery rates were also evaluated. Postoperative paravertebral muscle atrophy was assessed using MRI. Bone union rates between the split spinous process and residual laminae were also examined.

The mean surgical time and intraoperative blood loss were 25.7 minutes and 42.4 ml per 1 level in modified LSPSL, respectively, and 22.7 minutes and 29.5 ml in CL, respectively. The recovery rate of the JOA score was 64.2% in modified LSPSL and 68.7% in CL. The degree of paravertebral muscle atrophy was 7.8% in modified LSPSL and 22.2% in CL at 12 months after surgery (p < 0.05). The fusion rates of the spinous process with the arcus vertebrae at 6 and 12 months in modified LSPSL were 56.3% and 81.3%, respectively.

The modified LSPSL procedure was less invasive to the paravertebral muscles and could be a laminoplasty; therefore, the modified LSPSL procedure presents an effective alternative to lumbar laminectomy.

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Kei Ando, Kazuyoshi Kobayashi, Masaaki Machino, Kyotaro Ota, Satoshi Tanaka, Masayoshi Morozumi, Sadayuki Ito, Shunsuke Kanbara, Taro Inoue, Naoki Ishiguro and Shiro Imagama


The objective of this study was to investigate the relationship between morphological changes in thoracic ossification of the posterior longitudinal ligament (T-OPLL) and postoperative neurological recovery after thoracic posterior fusion surgery. Changes of OPLL morphology and postoperative recovery in cases with T-OPLL have not been examined.


In this prospective study, the authors evaluated data from 44 patients (23 male and 21 female) who underwent posterior decompression and fusion surgery with instrumentation for the treatment of T-OPLL at our hospital. The patients’ mean age at surgery was 50.7 years (range 38–68 years). The minimum duration of follow-up was 2 years. The location of thoracic ossification of the ligamentum flavum (T-OLF), T-OLF at the OPLL level, OPLL morphology, fusion range, estimated blood loss, operative time, pre- and postoperative Japanese Orthopaedic Association (JOA) scores, and JOA recovery rate were investigated. Reconstructed sagittal multislice CT images were obtained before and at 3 and 6 months and 1 and 2 years after surgery. The basic fusion area was 3 vertebrae above and below the OPLL lesion. All parameters were compared between patients with and without continuity across the disc space at the OPLL at 3 and 6 months after surgery.


The preoperative morphology of OPLL was discontinuous across the disc space between the rostral and caudal ossification regions on sagittal CT images in all but one of the patients. Postoperatively, these segments became continuous in 42 patients (97.7%; occurring by 6.6 months on average) without progression of OPLL thickness. Patients with continuity at 3 months had significantly lower rates of diabetes mellitus (p < 0.05) and motor palsy in the lower extremities (p < 0.01). The group with continuity also had significantly higher mean postoperative JOA scores at 3 (p < 0.01) and 6 (p < 0.05) months and mean JOA recovery rates at 3 and 6 months (both p < 0.01) after surgery.


Preoperatively, discontinuity of rostral and caudal ossified lesions was found on CT in all patients but one of this group of 44 patients who needed surgery for T-OPLL. Rigid fixation with instrumentation may have allowed these segments to connect at the OPLL. Such OPLL continuity at an early stage after surgery may accelerate spinal cord recovery.