Lateral-PLIF for spinal arthrodesis: concept, technique, results, complications, and outcomes

BACKGROUND

Posterior lumbar interbody fusion (PLIF) surgery represents an effective option to treat degenerative conditions in the lumbar spine. To reduce the drawbacks of the classical technique, we developed a variant, so-called Lateral-PLIF, which we then evaluated through a prospective consecutive series of patients.

METHODS

All adult patients treated at our institute with single or double level Lateral-PLIF for lumbar degenerative disease from January to December 2017 were prospectively collected. Exclusion criteria were patients < 18 years of age, traumatic patients, active infection, or malignancy, as well as unavailability of clinical and/or radiological follow-up data. The technique consists of insert the cages bilaterally through the transition zone between the central canal and the intervertebral foramen, just above the lateral recess. Pre- and postoperative (2 years) questionnaires and phone interviews (4 years) assessed pain and functional outcomes. Data related to the surgical procedure, postoperative complications, and radiological findings (1 year) were collected.

RESULTS

One hundred four patients were selected for the final analysis. The median age was 58 years and primary symptoms were mechanical back pain (100, 96.1%) and/or radicular pain (73, 70.2%). We found a high fusion rate (95%). A statistically significant improvement in functional outcome was also noted (ODI p < 0.001, Roland-Morris score p < 0.001). Walking distance increased from 812 m ± 543 m to 3443 m ± 712 m (p < 0.001). Complications included dural tear (6.7%), infection/wound dehiscence (4.8%), and instrument failure (1.9%) but no neurological deterioration.

CONCLUSIONS

Lateral-PLIF is a safe and effective technique for lumbar interbody fusion and may be considered for further comparative study validation with other techniques before extensive use to treat lumbar degenerative disease.

Vertebral body spread in thoracolumbar burst fractures can predict posterior construct failure

BACKGROUND CONTEXT

The load sharing classification (LSC) laid foundations for a scoring system able to indicate which thoracolumbar fractures, after short-segment posterior-only fixations, would need longer instrumentations or additional anterior supports.

PURPOSE

We analyzed surgically treated thoracolumbar fractures, quantifying the vertebral body's fragment displacement with the aim of identifying a new parameter that could predict the posterior-only construct failure.

STUDY DESIGN

This is a retrospective cohort study from a single institution.

PATIENT SAMPLE

One hundred twenty-one consecutive patients were surgically treated for thoracolumbar burst fractures.

OUTCOME MEASURES

Grade of kyphosis correction (GKC) expressed radiological outcome; Oswestry Disability Index and visual analog scale were considered.

METHODS

One hundred twenty-one consecutive patients who underwent posterior fixation for unstable thoracolumbar burst fractures were retrospectively evaluated clinically and radiologically. Supplementary anterior fixations were performed in 34 cases with posterior instrumentation failure, determined on clinic-radiological evidence or symptomatic loss of kyphosis correction. Segmental kyphosis angle and GKC were calculated according to the Cobb method. The displacement of fracture fragments was obtained from the mean of the adjacent end plate areas subtracted from the area enclosed by the maximum contour of vertebral fragmentation. The "spread" was derived from the ratio between this subtraction and the mean of the adjacent end plate areas. Analysis of variance, Mann-Whitney, and receiver operating characteristic were performed for statistical analysis. The authors report no conflict of interest concerning the materials or methods used in the present study or the findings specified in this paper. No funds or grants have been received for the present study.

RESULTS

The spread revealed to be a helpful quantitative measurement of vertebral body fragment displacement, easily reproducible with the current computed tomography (CT) imaging technologies. There were no failures of posterior fixations with preoperative spreads <42% and losses of correction (LOC)<10°, whereas spreads >62.7% required supplementary anterior supports whenever LOC>10° were recorded. Most of the patients in a "gray zone," with spreads between 42% and 62.7%, needed additional anterior supports because of clinical-radiological evidence of impending mechanical failures, which developed independently from the GKC. Preoperative kyphosis (p<.001), load sharing score (p=.002), and spread (p<.001) significantly affected the final surgical treatment (posterior or circumferential).

CONCLUSIONS

Twenty-two years after the LSC, both improvements in spinal stabilization systems and software imaging innovations have modified surgical concepts and approach on spinal trauma care. Spread was found to be an additional tool that could help in predicting the posterior construct failure, providing an objective preoperative indicator, easily reproducible with the modern viewers for CT images.

Releasing the circumferential fixation of the medial meniscus does not affect its kinematics

BACKGROUND

Meniscal functioning depends on the fixation between the meniscal horns and the surrounding tissues. It is unknown, however, whether the integration between the outer circumference of the medial meniscus and the knee capsule/medial collateral ligament also influences the biomechanical behavior of the meniscus. Therefore, we aimed to determine whether detaching and resuturing the circumferential fixation of the medial meniscus influence its kinematic pattern.

METHODS

Human cadaveric knee joints were flexed (0°-30°-60°-90°) in a knee loading rig, in neutral orientation and under internal and external tibial torques. Roentgen stereophotogrammetric analysis was used to determine the motion of the meniscus in anteroposterior (AP) and mediolateral (ML) directions. Three fixation conditions were evaluated: (I) intact, (II) detached and (III) resutured.

RESULTS

Detaching and resuturing the circumferential fixation did not alter the meniscal motion pattern in either the AP or ML direction. Applying an additional internal tibial torque caused the medial meniscus to move slightly anteriorly, and an external torque caused a little posterior translation with respect to the neutral situation. These patterns did not change when the circumferential fixation condition was altered.

CONCLUSIONS

This study demonstrated that the motion pattern of the medial meniscus is independent of its fixation to the knee capsule and medial collateral ligament.

CLINICAL RELEVANCE

The outcomes of this study can be deployed to design the fixation strategy of a permanent meniscus prosthesis. As peripheral fixation is a complicated step during meniscal replacement, the surgical procedure is considerably simplified when non-resorbable implants do not require circumferential fixation.