Quantitative Assessment of the Anatomical Footprint of the C1 Pedicle Relative to the Lateral Mass: A Guide for C1 Lateral Mass Fixation

Study Design: Anatomic study. Objectives: To determine the relationship of the anatomical footprint of the C1 pedicle relative to the lateral mass (LM). Methods: Anatomic measurements were made on fresh frozen human cadaveric C1 specimens: pedicle width/height, LM width/height (minimum/maximum), LM depth, distance between LM’s medial aspect and pedicle’s medial border, distance between LM’s lateral aspect to pedicle’s lateral border, distance between pedicle’s inferior aspect and LM’s inferior border, distance between arch’s midline and pedicle’s medial border. The percentage of LM medial to the pedicle and the distance from the center of the LM to the pedicle’s medial wall were calculated. Results: A total of 42 LM were analyzed. The C1 pedicle’s lateral aspect was nearly confluent with the LM’s lateral border. Average pedicle width was 9.0 ± 1.1 mm, and average pedicle height was 5.0 ± 1.1 mm. Average LM width and depth were 17.0 ± 1.6 and 17.2 ± 1.6 mm, respectively. There was 6.9 ± 1.5 mm of bone medial to the medial C1 pedicle, which constituted 41% ± 9% of the LM’s width. The distance from C1 arch’s midline to the medial pedicle was 13.5 ± 2.0 mm. The LM’s center was 1.6 ± 1 mm lateral to the medial pedicle wall. There was on average 3.5 ± 0.6 mm of the LM inferior to the pedicle inferior border. Conclusions: The center of the lateral mass is 1.6 ± 1 mm lateral to the medial wall of the C1 pedicle and approximately 15 mm from the midline. There is 6.9 ± 1.5 mm of bone medial to the medial C1 pedicle. Thus, the medial aspect of C1 pedicle may be used as an anatomic reference for locating the center of the C1 LM for screw fixation

Intervertebral disk-like biphasic scaffold—demineralized bone matrix cylinder and poly(polycaprolactone triol malate)—for interbody spine fusion

Interbody fusion is an established procedure to preserve disk height and anterior fusion, but fusion with autografts, allografts, and metallic cages has its endogenous shortcomings. The objective of this study is to investigate whether a biphasic scaffold model, the native demineralized bone matrix cylinder in conjunction with degradable biomaterial poly(polycaprolactone triol malate), can be employed as a biological graft for interbody fusion. The poly(polycaprolactone triol malate) was synthesized by polycondensing malic acid and polycaprolactone and then the concentric sheet of poly(polycaprolactone triol malate) was fabricated into the demineralized bone matrix cylinder derived from rabbit femurs. Rabbit chondrocytes were loaded onto the three-dimensional constructs with 1-day in vitro culture and implanted into the subcutaneous dorsal pocket of nude mice. The chondrocytes/scaffold constructs are approximately two folds bigger than the scaffold-alone constructs after 12 weeks of implantation. X-ray and micro-computed tomography imaging showed endochondral bone formation in the chondrocytes/scaffold constructs as early as 4 weeks and showed that the bone intensity increased over time. Histological staining confirmed the above observation. By week 8, lamellar bone tissues were formed inside the demineralized bone matrix cylinder. In addition, the compression biomechanical test showed that the chondrocytes/scaffold constructs produced a significant higher compressive strength compared to the scaffold group. These results demonstrated that the inner-phase poly(polycaprolactone triol malate) degraded over time and was replaced by new bone in an in vivo environment

Quantitative Assessment of the Anatomical Footprint of the C1 Pedicle Relative to the Lateral Mass: A Guide for C1 Lateral Mass Fixation.

Study designAnatomic study.ObjectivesTo determine the relationship of the anatomical footprint of the C1 pedicle relative to the lateral mass (LM).MethodsAnatomic measurements were made on fresh frozen human cadaveric C1 specimens: pedicle width/height, LM width/height (minimum/maximum), LM depth, distance between LM's medial aspect and pedicle's medial border, distance between LM's lateral aspect to pedicle's lateral border, distance between pedicle's inferior aspect and LM's inferior border, distance between arch's midline and pedicle's medial border. The percentage of LM medial to the pedicle and the distance from the center of the LM to the pedicle's medial wall were calculated.ResultsA total of 42 LM were analyzed. The C1 pedicle's lateral aspect was nearly confluent with the LM's lateral border. Average pedicle width was 9.0 ± 1.1 mm, and average pedicle height was 5.0 ± 1.1 mm. Average LM width and depth were 17.0 ± 1.6 and 17.2 ± 1.6 mm, respectively. There was 6.9 ± 1.5 mm of bone medial to the medial C1 pedicle, which constituted 41% ± 9% of the LM's width. The distance from C1 arch's midline to the medial pedicle was 13.5 ± 2.0 mm. The LM's center was 1.6 ± 1 mm lateral to the medial pedicle wall. There was on average 3.5 ± 0.6 mm of the LM inferior to the pedicle inferior border.ConclusionsThe center of the lateral mass is 1.6 ± 1 mm lateral to the medial wall of the C1 pedicle and approximately 15 mm from the midline. There is 6.9 ± 1.5 mm of bone medial to the medial C1 pedicle. Thus, the medial aspect of C1 pedicle may be used as an anatomic reference for locating the center of the C1 LM for screw fixation

Evaluation of complications and neurological deficits with three-column spine reconstructions for complex spinal deformity: a retrospective Scoli-RISK-1 study

OBJECT: To evaluate the risk factors for complications, including new neurological deficits, in the largest cohort of adult spinal deformity patients to date. METHODS: Scoli-RISK-1 inclusion criteria were used to identify eligible patients from five centers, treated from June 1, 2009 to June 1, 2011. Records were reviewed for patient demographics, surgical data, and reports of perioperative complications. Neurological deficits were recorded as pre-existing or as new neurological deficits. Patients undergoing a three column osteotomies (3CO) were compared to those not (PSF). Between group comparisons were performed using independent samples t-tests and Chi-square analyses. RESULTS: Two hundred and seven patients were identified, with 75 PSF and 132. 3CO patients were older (58.9 vs 49.4, p<0.0001), had higher BMI (29.0 vs 25.8, p=0.034), had smaller preoperative coronal Cobb measurements (33.8 vs 56.3, p<0.001), had more preoperative sagittal malalignment (116.6 vs 54.5mm, p<0.001), and had similar sagittal Cobb measurements (45.8 vs 57.7, p=0.113). Operative times were similar (393 vs 423 min, p=0.112), though 3CO sustained higher EBL (2120 vs 1700mL, p=0.013). Rates of new neurologic deficits were similar (PSF:6.7% vs 3CO:9.8%, p=0.435) and rates of any perioperative medical complication were similar (PSF:45.3% vs 3CO:34.8%, p=0.136). VCR patients were more likely to sustain medical complications than PSO (73.7% vs 46.9%, p=0.031), though new neurologic deficits were similar (15.8% vs 8.8%, p=0.348). Regression analysis did not reveal significant predictors of neurologic injury nor complication from collected data. CONCLUSIONS: Despite higher EBL, rates of all complications (49.3%) and new neurologic deficits (8.7%) did not vary for complex reconstruction patients, whether a 3-CO is performed or not. VCR patients sustained more medical complications without an increase in new neurologic deficits. Prospective study of patient factors, provider factors, and refined surgical data are needed to define and optimize risk factors for complication and neurologic deficits