Comparison of post-operative lordosis with the PEEK cage and the cervical plate.

OBJECTIVE: The maintenance of post-operative lordosis has been shown to be a key factor in decreasing adjacent level disc stress. Previous studies of the PEEK (polyether ketone) cage have used intervertebral bony fusion as the primary measure of surgical success; however, little is known about its effects on spinal curvature. Our objective was to compare the PEEK cage to the cervical plate with respect to the maintenance of cervical lordosis at one year. Secondary outcomes included fusion and complication rates. METHODS: We performed a retrospective study of patients who underwent ACDF (anterior cervical discectomy and fusion) by two different methods; 13 patients were treated with the PEEK cage, and 22 with allograft and plating. RESULTS: Patient and treatment characteristics were similar in both groups. Average global lordotic curvature (C2-C7) was increased by 1.7 degrees for the PEEK cage and decreased by 1.6 degrees for the plate after an average follow-up of 12.46 and 14.95 months, respectively. Regional lordosis for the PEEK cage and plate was decreased by 2.5 and 2.1 degrees, respectively for the same time period. These differences did not achieve statistical significance. Bony fusion was observed in all patients. One patient in each group developed persistent mild dysphagia. CONCLUSIONS: The PEEK cage is comparable to the anterior cervical plate in the maintenance of post-operative cervical lordosis.

Comparison of computed tomography 3-dimensional volumetric analysis of ventricular size to visual radiological assessment.

OBJECTIVES: Interpretation of ventricular volume on computed tomography scans of hydrocephalus patients is usually subjective. The objective of this study was to determine whether radiological assessment of interval change correlates better with an objective calculated volume change or with other objective 2-dimensional estimates of ventricle volume change. METHODS/SAMPLE: Ventricular volume, Evans ratio, and frontal and occipital Horn ratio were retrospectively assessed on 95 pairs of scans from patients with a ventriculoperitoneal shunt. To determine ventricle volume, all voxels of cerebrospinal fluid density were isolated on a 3-dimensional reconstructed computed tomography scan. Voxels of fluid density contiguous with one another in the ventricular system were isolated. Radiological assessments of interval change were divided into 5 groups based on reported findings in the radiology report. The 95% mean confidence intervals were developed for changes in the measured parameters, given a particular radiological assessment. Multinomial regression was subsequently performed to determine which parameter was most closely correlated with the radiological assessment. RESULTS: Significant overlap was found in the confidence intervals for objectively calculated volume change between the different categories of radiological assessment. The frontal and occipital Horn ratio had the most consistent correlation with the radiological assessment, followed by the Evans ratio. Objectively calculated volume change correlated poorly with radiological assessment. CONCLUSIONS: Radiological interpretation does not correlate well with objectively calculated volume changes, but correlates better with other parameters that approximate volume and are likely used to visually evaluate interval change. We recommend that ventricle volume be objectively measured to increase consistency between radiological interpretation and actual interval changes.

Traumatic lateral expulsion of the L-4 vertebral body from the spinal column.

Traumatic lateral spondyloptosis is mostly a lateral shearing injury that must be tremendous enough to completely disrupt the strong musculoligamentous and bony structures. This injury has only been described at single levels in the lumbar spine. Lateral expulsion of a vertebral body from the spinal column due to 2-level adjacent spondyloptosis has not been previously reported. This 16-year-old girl was referred to our center for the management of an extremely unusual L2-5 fracture-dislocation. Motor deficits were incomplete and sacral sensation was spared. Three-dimensional reconstructed CT scans revealed a fracture involving the superior L-4 vertebral body and endplate. There was also complete disruption of the L4-5 disc space. The majority of the L-4 vertebral body was expelled to the right of the spinal column, with the collapse of L-3 and a small remnant of the L-4 superior endplate onto L-5. Surgical management involved decompression, reduction, reconstruction of L-4 with a cage, and L1-ilium stabilization and fusion. Only a few attachments of the psoas muscles had to be divided to roll the L-4 vertebral body out posterolaterally, similar to the method of complete en bloc spondylectomy used in oncology. Neurological recovery has thus far included the resumption of normal bladder and bowel function, as well as ambulation with the use of a right leg brace. Perhaps this type of fracture has not been previously described because many patients would be expected to succumb to vascular or visceral injury. The authors believe this is the first case report of double lateral spondyloptosis at adjacent levels, resulting in expulsion of the vertebral body from the spinal column.

Integrity of articular cartilage on T2 mapping associated with meniscal signal change.

OBJECTIVE: The purpose of this study was to investigate the relationship between T2 relaxation values (T2 RVs) within the superficial zone of articular cartilage and different types of meniscal degeneration/tear. MATERIALS AND METHODS: A review of 310 consecutive knee MRIs which included an 8 echo T2 relaxation sequence, in patients referred for standard clinical indications, was performed independently and in blinded fashion by 2 observers. The posterior horns of the medial and lateral menisci were each evaluated and divided into 4 subgroups: Normal (control), Grade I/II meniscal signal, Grade III meniscal signal-simple tear (Grade III-S), and Grade III meniscal signal-complex tear (Grade III-C). After exclusion criteria were applied, the medial meniscal group consisted of 65 controls and 133 patients, while the lateral meniscal group consisted of 143 controls and 55 patients. T2 RVs were measured by an observer blinded to the clinical history and MRI grading. Measurements were obtained over the superficial zone of femoral and tibial articular cartilage adjacent to the center of the posterior horn of each meniscus to ensure consistency between measurements. Analysis of covariance adjusting for age and gender was used to compare T2 RVs between patients and controls. RESULTS: T2 RVs were significantly increased in patients with Grade III-C meniscal tears compared to controls over the medial tibial plateau (MTP; p=0.0001) and lateral tibial plateau (LTP; p=0.0008). T2 RVs were not increased in patients with Grade III-C meniscal tears over the medial femoral condyle (MFC; p=0.11) or lateral femoral condyle (LFC; p=0.99). Grade I/II meniscal signal was not associated with elevated T2 RVs over the MFC (p=0.15), LFC (p=0.69), MTP (p=0.42), or LTP (p=0.50). Grade III-S meniscal signal was not associated with elevated T2 RVs over the MFC (p=0.54), LFC (p=0.43), MTP (p=0.30), or LTP (p=0.38). CONCLUSION: Grade III-C meniscal tears are associated with elevated T2 RVs in adjacent tibial articular cartilage. The results may have an impact on prognostication and treatment in order to delay or prevent the onset of osteoarthritis.