Junichi Arima

Effect of partial release of the posterior cruciate ligament in total knee arthroplasty

Appropriate tension of the posterior cruciate ligament, which often is tight in deep flexion, is difficult to achieve after posterior cruciate ligament retaining total knee arthroplasty. Kinematics and maximum flexion after partial release of the posterior cruciate ligament were evaluated in this study. A partial release improved the maximum flexion angle and maintained anteroposterior stability without causing undesirable changes in kinematics, whereas full resection of the posterior cruciate ligament caused unfavorable anteroposterior instability. Partial posterior cruciate ligament release eliminated excessive rollback movement caused by a tight posterior cruciate ligament and also shifted the point of articular surface contact anteriorly. These results indicate that partial release of the posterior cruciate ligament may improve knee function in patients with a tight posterior cruciate ligament after total knee arthroplasty.

A Case of Recurrent Cervical Spondylolisthesis following Cervical Laminoplasty

We report a case of recurrent cervical spondylolisthesis following cervical laminoplasty. A 77-year-old woman with progressive quadriplegia due to cervical spondylotic myelopathy (CSM) without spondylolisthesis was treated with C3 to 5 French-door laminoplasty. At 15 months postoperatively, anterior slippage of the C4 vertebral body in flexion was prominent. At 20 months postoperatively, slippage had worsened, and C4 to 5 posterior fixation with a lateral mass screw and rod system was performed. At 8 months after C4 to 5 fixation, anterior slippage of the C3 and C5 vertebral bodies was noted, and occipitocervical– upper thoracic posterior fusion was performed. In this case, after laminoplasty, atrophy of the cervical extensor muscles progressed in a time-dependent manner. Therefore, we suggest that progressive atrophy of the cervical extensor muscles might cause isolated neck extensor myopathy with flexible dropped head syndrome, leading to recurrent cervical spondylolisthesis.

Long-Term Outcome of Patients Undergoing Microscopic Lumbar Spinous Process-Splitting Laminectomy

Microscopic lumbar spinous process–splitting laminectomy (LSPSL) has been previously reported as the least invasive surgery for patients with lumbar spinal canal stenosis (LSS). An 18-mm diameter tubular retractor was inserted between the split spinous processes and complete microscopic laminectomy performed in single-level decompressions. A cervical retractor was used to open the caudal parts of the individual halves of the spinous process through a single incision in multi-level decompressions. In this study, we examined long-term outcomes of patients undergoing microscopic LSPSL. Overall, 119 patients with a follow-up longer than 24 months were included in the study. All patients were divided into two groups: 1) the slip group, which included patients with spondylolisthesis-type LSS, and 2) the nonslip group, which included patients with spondylosis-type LSS. The clinical outcomes were evaluated using the Japanese Orthopedic Association score and improvement rate. The slip and instability rates were measured using radiographic imaging findings of the sagittal plane in patients in the slip group. Computed tomography was used to assess bony union of the split spinous process. Magnetic resonance imaging was used to evaluate signal changes of the multifidus muscle at different levels of LSPSL decompression. After LSPSL, pre-operative symptoms were improved with a significant difference in the Japanese Orthopedic Association score. The overall improvement rate was 62.2%; however, it was 48.6% in patients older than 79 years. No significant difference was seen in the slip or instability rate before and after LSPSL. The bony union rate of the split spinous process at the site between the process and the vertebral arch was 79.5%. Post-operative magnetic resonance imaging findings demonstrated a slight amount of fat infiltration in the multifidus muscles after LSPSL. In conclusion, the long-term outcome of patients undergoing LSPSL is satisfactory for a minimally invasive decompression surgery.