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Joel A. Finkelstein and Carolyn E. Schwartz

The purpose of this article is to review the current state of outcome measurement in spine surgery, with an emphasis on patient-reported outcome measures (PROMs). The commonly used generic and disease-specific outcome measures used in spinal surgery and research will be discussed. The authors will introduce the concepts of response shift and appraisal processes, which may affect the face validity of PROMs, as well as their interpretation over time. It is not uncommon for there to be a discrepancy between the observed and expected outcome, which is not wholly explainable by objective measures. Current work on understanding how appraisal affects outcome measurement will be discussed, and future directions will be suggested to facilitate the continued evolution of PROMs.

There has been an evolution in the way clinicians measure outcomes following spinal surgery. In moving from purely physical, objective measures to a growing emphasis on the patient’s perspective, spine surgery outcomes are better able to integrate the impact at multiple levels of relevant change. Appraisal concepts and methods are gaining traction as ways to understand the cognitive processes underlying PROMs over time. Measurement of appraisal is a valuable adjunct to the current spine outcome tools.

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Zachary Tan, Stewart McLachlin, Cari Whyne and Joel Finkelstein


The cortical bone trajectory (CBT) technique for pedicle screw placement has gained popularity among spinal surgeons. It has been shown biomechanically to provide better fixation and improved pullout strength compared to a traditional pedicle screw trajectory. The CBT technique also allows for a less invasive approach for fusion and may have lower incidence of adjacent-level disease. A limitation of the current CBT technique is a lack of readily identifiable and reproducible visual landmarks to guide freehand CBT screw placement in comparison to the well-defined identifiable landmarks for traditional pedicle screw insertion. The goal of this study was to validate a safe and intuitive freehand technique for placement of CBT screws based on optimization of virtual CBT screw placement using anatomical landmarks in the lumbar spine. The authors hypothesized that virtual identification of anatomical landmarks on 3D models of the lumbar spine generated from CT scans would translate to a safe intraoperative freehand technique.


Customized, open-source medical imaging and visualization software (3D Slicer) was used in this study to develop a workflow for virtual simulation of lumbar CBT screw insertion. First, in an ex vivo study, 20 anonymous CT image series of normal and degenerative lumbar spines and virtual screw insertion were conducted to place CBT screws bilaterally in the L1–5 vertebrae for each image volume. The optimal safe CBT trajectory was created by maximizing both the screw length and the cortical bone contact with the screw. Easily identifiable anatomical surface landmarks for the start point and trajectory that best allowed the reproducible idealized screw position were determined. An in vivo validation of the determined landmarks from the ex vivo study was then performed in 10 patients. Placement of virtual “test” cortical bone trajectory screws was simulated with the surgeon blinded to the real-time image-guided navigation, and the placement was evaluated. The surgeon then placed the definitive screw using image guidance.


From the ex vivo study, the optimized technique and landmarks were similar in the L1–4 vertebrae, whereas the L5 optimized technique was distinct. The in vivo validation yielded ideal, safe, and unsafe screws in 62%, 16%, and 22% of cases, respectively. A common reason for the nonidealized trajectories was the obscuration of patient anatomy secondary to severe degenerative changes.


CBT screws were placed ideally or safely 78% of the time in a virtual simulation model. A 22% rate of unsafe freehand trajectories suggests that the CBT technique requires use of image-guided navigation or x-ray guidance and that reliable freehand CBT screw insertion based on anatomical landmarks is not reliably feasible in the lumbar spine.

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Payam Mousavi, Sandra Roth, Joel Finkelstein, Gordon Cheung and Cari Whyne


The goal of this study was to quantify volumetrically cement fill and leakage in patients with osteoporotic and metastatic vertebral lesions undergoing percutaneous vertebroplasty and to establish whether these factors have any clinical significance at follow up.


Digital computerized tomography data were retrospectively collected from all cases at the authors' institution in which percutaneous vertebroplasty was performed for osteoporosis or metastatic disease. Patient selection was based on the consensus of a multidisciplinary team consisting of an orthopedic surgeon, an oncologist, and a neuroradiologist. A semiautomated thresholding technique was used to measure vertebral body volume, the volume of cement injected directly into the vertebra, and the volume of cement leakage. Pain-related scores were collected at four early stages of treatment, and all clinical complications were recorded.

Cement leakage was found in 87.9% of vertebrae treated with percutaneous vertebroplasty. In osteoporotic vertebrae it occurred mainly in the disc, whereas in metastatic lesions, it was found in multiple areas. Irrespective of leakage, both patients with osteoporotic and metastatic disease experienced significant immediate pain relief postoperatively.


Although there was no correlation between cement fill or cement leakage and pain relief, there exists a risk of serious complications due to cement leakage.

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Miriam Kim, Paul Nolan and Joel A. Finkelstein

Object. The 11th rib extrapleural—retroperitoneal approach offers an alternative means for access to the thoracolumbar junction. It provides excellent operative exposure without the need to transgress the diaphragm, resulting in less morbidity and reduced risk of pulmonary complications. This approach, however, has been dismissed by many surgeons offering the unsubstantiated criticism that it affords limited access. Thus far, only technical descriptions of the operative procedure are available in the literature, without documentation of the clinical outcomes of these patients.

In the current study the authors describe the 11th rib extrapleural—retroperitoneal approach to the thoracolumbar junction, and they evaluate the associated early and late morbidity in these patients.

Methods. From September 1996 to August 1999, the authors collected prospective data of consecutive patients who underwent surgery for a variety of pathological conditions of the thoracolumbar junction via this approach. In 26 consecutive patients requiring an anterior spinal procedure, lesions located between T-10 and T-11 were studied and followed for a mean period of 17 months (range 1–36 months). There were 13 men and 13 women whose mean age was 47 years (range 16–80 years), with the following pathological entities: trauma (13 cases), neoplasm (six cases), infection (two cases), and deformity (five cases). There were no cases of neurological deterioration. There were no significant pulmonary complications, and only one patient required insertion of a postoperative chest tube.

Conclusions. The 11th rib extrapleural—retroperitoneal approach was successfully used to treat patients with a variety of lesions in the thoracolumbar junction and was associated with little morbidity. The authors believe that previous criticism suggesting that this approach provides only limited access is unsubstantiated.

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Carolyn E. Schwartz, Roland B. Stark, Phumeena Balasuberamaniam, Mopina Shrikumar, Abeer Wasim and Joel A. Finkelstein


Over the past 2 decades, spine outcome research has become more standardized in response to recommendations from Deyo and others. By using the same generic and condition-specific patient-reported outcome (PRO) measures across studies, results are more easily compared. Given the challenges of maintaining high-quality data in clinical research studies, it would be important to evaluate the contribution of each PRO to confirm that it merits the respondent burden. This study aimed to examine the spine PROs’ association with clinically important change and relative responsiveness in explaining variance in patients’ global assessment of change (GAC).


This prospective longitudinal cohort study included adults recruited from 4 active spine surgery practices at a Toronto-based hospital. Patients were diagnosed with a degenerative lumbar spinal condition and underwent spinal decompression and/or fusion surgery. Participants completed the RAND-36 (to generate the physical component score [PCS] and mental component score [MCS]), Oswestry Disability Index (ODI), the numeric rating scale (NRS) for pain, Patient-Reported Outcomes Measurement Information System (PROMIS) pain interference, and a GAC item. Random-effects models were used to investigate the sensitivity of PROs to the GAC and their responsiveness over time (i.e., PRO main effects and PRO-by-time interactions, respectively).


The study sample included 168 patients (mean age 61 years, 50% female) with preoperative and up to 12 months of postoperative data. Random-effects models revealed significant main effects for all PROs. Significant time-by-PRO interactions were detected for the PCS, PROMIS, ODI, and NRS (p < 0.0005 in all cases), but not for the MCS. Further examination revealed different sensitivity of the PROs to the GAC at different times. The NRS, PROMIS, and PCS showed higher sensitivity early after surgery, and the PCS evinced a marked drop in sensitivity to the GAC at about 8 months postsurgery.


All PROs currently included in the spine outcome core measures are associated with patients’ subjective assessment of a clinically important change, and all but the MCS scores are responsive to such change. Based on these findings, the core spine PROs could be reduced to include fewer estimates of pain. The authors suggest replacing the less responsive measures with tools that help to characterize factors that are driving the patients’ subjective assessment of change and that meaningfully address some of the higher levels in the hierarchy of quality-of-life outcomes.