The impact of over-distraction on adjacent segment pathology and cage subsidence in anterior cervical discectomy and fusion

Over-distraction has been shown to be a risk factor for cage subsidence and postoperative neck pain after anterior cervical discectomy and fusion (ACDF). Biomechanical studies have demonstrated increased adjacent segment intradiscal pressure after ACDF. The purpose of this study is to determine if over-distraction of the index disc has an effect on adjacent segment pathology. A consecutive series of 145 patients who received primary ACDF for cervical degenerative pathologies from January 2010 to December 2017 were retrospectively reviewed. The patients were divided into: (1) Over-distraction group (postoperative-preoperative index disc height ≥ 2 mm), and (2) No-distraction group (postoperative-preoperative index disc height < 2 mm). Outcome measures included radiographic parameters, Japanese Orthopaedic Association (JOA) score, and incidences of cage subsidence, radiological and clinical adjacent segment pathologies (RASP and CASP) were compared between the two groups preoperatively, postoperatively, and at the final follow-up. The two groups were comparable with respect to age, follow-up length, JOA score, incidence of CASP, and radiographic parameters. The Over-distraction group (83 patients; 115 levels) had smaller preoperative index disc height (4.5 vs. 5.2 mm, p < 0.001), but taller postoperative index disc height (7.7 vs. 6.6 mm, p < 0.001) than No-distraction group (62 patients; 90 levels) Furthermore, significantly higher incidences of cage subsidence (47% vs. 31%, p = 0.04) and RASP (any progression: 48% vs. 15%, p < 0.001; progress ≥ 2 grades: 25% vs. 7%, p = 0.001) were observed in the Over-distraction group. The multivariate analysis indicated that over-distraction and multilevel fusion were independent risk factors for RASP. There were no clinical outcome differences between the Over-distraction group and the No-distraction group in ACDF. Over-distraction of the index level of ≥ 2 mm should be avoided because it significantly increases the incidences of RASP and cage subsidence.

The surgical outcome of multilevel anterior cervical discectomy and fusion in myelopathic elderly and younger patients

The elderly population has an increased risk of degenerative cervical myelopathy due to multilevel disease, causing motor and sensory dysfunctions and a poor quality of life. Multilevel anterior cervical discectomy and fusion (ACDF) is an alternative surgical treatment option, but has a perceived higher risk of complications. The goal of this study is to report the outcome. We retrospectively reviewed patients from 2006 to 2019 undergoing multilevel ACDF for degenerative cervical myelopathy and compared outcomes and complications between elder patients (aged 70 and above) and younger patients (below 70). The patients' comorbidities, and postoperative complications, radiographic parameters such as C2-C7 Cobb angle, C2-C7 sagittal vertical axis, inter-body height of surgical levels and fusion rate were recorded. Japanese Orthopaedic Association (JOA) score and modified Odom's score were collected. Included were 18 elderly (mean age 74, range 70-87) and 45 young patients (mean age 56, range 43-65) with a follow-up of 43.8 and 55.5 months respectively. Three-level ACDF was the most common. The ratios of ASA class III patients were 94.4% and 48.9% (p < 0.001). The Charlson comorbidity indexes were 4.3 ± 1.03 and 2.1 ± 1.11 (p < 0.001). The average lengths of hospital stays were 4.9 and 4.6 days. Eleven patients (61.1%) in the elderly group experienced at least one short-term complication, compared with 16 patients (35.6%) in the younger group (p < 0.05). The middle-term complications were comparable (22.2% and 20.0%). The JOA score, recovery rate and modified Odom score showed comparable result between groups. Despite its extensiveness, multilevel ACDF is feasible for the elder patients with good clinical outcome and fusion rate. When compared to younger cohort, there is a trend of lower preoperative JOA score and recovery rate. The short-term complication rate is higher in the elderly group.

Degenerative cervical myelopathy presenting as subjective lower limb weakness could be a trap towards misdiagnosis

When patients presenting with subjective lower limb weakness (SLLW) are encountered, it is natural to suspect a lumbar pathology and proceed with related clinical examination, investigations and management. However, SLLW could be a sign of degenerative cervical myelopathy (DCM) due to an evolving cord compression. In such circumstances, if symptoms are not correlated to myelopathy at the earliest, there could be potential complications over time. In this study, we intend to analyse the outcomes after surgical management of the cervical or thoracic cord compression in patients with SLLW. Retrospectively, patients who presented to our center during the years 2010–2016 with sole complaint of bilateral SLLW but radiologically diagnosed to have a solitary cervical or thoracic stenosis, or tandem spinal stenosis and underwent surgical decompression procedures were selected. Their clinical presentation was categorised into three types, myelopathy was graded using Nurick’s grading and JOA scoring; in addition, their lower limb functional status was assessed using the lower extremity functional scale (LEFS). Functional recovery following surgery was assessed at 6 weeks, 3 months, 6 months, one year, and two years. Selected patients (n = 24; Age, 56.4 ± 10.1 years; range 32–78 years) had SLLW for a period of 6.4 ± 3.2 months (range 2–13 months). Their preoperative JOA score was 11.3 ± 1.8 (range 7–15), and LEFS was 34.4 ± 7.7 (range 20–46). Radiological evidence of a solitary cervical lesion and tandem spinal stenosis was found in 6 and 18 patients respectively. Patients gradually recovered after surgical decompression with LEFS 59.8 ± 2.7 (range 56–65) at 1 year and JOA score 13.6 ± 2.7 (range − 17 to 100) at 2 years. The recovery rate at final follow up was 47.5%. Our results indicate the importance of clinically suspecting SLLW as an early non-specific sign of DCM to avoid misdiagnosis, especially in patients without conventional upper motor neuron signs. In such cases, surgical management of the cord compression resulted in significant functional recovery and halted the progression towards permanent disability.

RELIABILITY OF THE MICHIGAN STATE UNIVERSITY (MSU) CLASSIFICATION OF LUMBAR DISC HERNIATION

Objective:

The Michigan State University (MSU) classification of lumbar disc herniation (LDH) is periodically used by various authors to classify disc herniation. We assessed the reliability of this classification system among orthopedic residents at our institute.

Methods:

Fifty T2 axial-cut magnetic resonance images (MRI) corresponding to the level of maximal disc herniation from patients diagnosed with a single LDH were selected and distributed to six orthopedic residents. All six residents gave a specific rating for each image based on the MSU classification; in addition, three residents gave ratings on two different occasions. The degree of agreement among residents was analyzed by calculating inter-observer and intra-observer reliability using the Kappa statistic.

Results:

The inter-observer reliability among the six residents calculated as the Fleiss’ Kappa was 0.422, which indicates moderate reliability. The intra-observer reliability of three selected residents calculated by Cohen's Kappa was 0.750, 0.772, and 0.859, which indicates substantial to almost perfect reliability. Variations in ratings were frequent in images portraying a broad-based disc herniation with spinal canal stenosis.

Conclusion:

Our findings demonstrate moderate homogeneity of ratings given by residents; however, test-retest results proved the ratings to be consistent. Level of Evidence II, Diagnostic studies - investigating a diagnostic examination.

Factors related to post surgical neurologic improvement for cervical spine infection

BACKGROUND

Cervical spine infections are uncommon but potentially dangerous, having the highest rate of neurological compromise and resulting disability. However, the factors related to surgical success is multiple yet unclear.

METHODS

We retrospectively reviewed the medical records of 27 patients (16 men and 11 women) with cervical spine infection who underwent surgical treatment at Chang Gung Memorial Hospital, Linkou branch, between 2001 and 2014. The neurological status, by Frankel classification, was recorded preoperatively and at discharge. Group X had neurologic improvement of at least 1 grade, group Y had unchanged neurologic status, and group Z showed deterioration. We recorded the patient demographic data, presenting symptoms and signs, interval from admission to surgery, surgical procedure, laboratory data, perioperative antibiotic course, pathogens identified, coexisting medical disease, concomitant nonspinal infection, and clinical outcomes. We intended to evaluate the different characteristics of patients who improved neurologically after treatment.

RESULTS

The mean age of our cohort was 56.6 years. Anterior cervical discectomy and fusion was the most commonly performed surgical procedure (74.1%). The Frankel neurological status improved in 70.4% (group X, n = 19) and unchanged in 29.6% (group Y, n = 8). No patients worsened. Motor weakness was most common (96.3%) neurological deficit, followed by sensory abnormalities (37.0%), and bowel/urine incontinence (33.3%). The main difference in presentation between group X and group Y was neck pain (100% vs. 75.0%; p = .02), not fever. Group X had a shorter preoperative antibiotic course (p = .004), interval from admission to operation (p = .02), and hospital stay (p = .01).

CONCLUSION

Clinicians should be more suspicious in patients who present with neck pain and any neurological involvement even in those without fever while establishing early diagnosis. Earlier operative treatment in group X result in better neurologic recovery and shorter hospital stay due to disease improvement.

Revalidating Pfirrmann's Magnetic Resonance Image-Based Grading of Lumbar Nerve Root Compromise by Calculating Reliability among Orthopaedic Residents

Background

Intervertebral disc herniations lead to subsequent compromise of the nerve root. The root can either have a mere contact with the disc material or be pushed aside or compressed. This was earlier graded by Pfirrmann and colleagues. We intend to revalidate this grading system by performing a reliability analysis among orthopaedic residents.

Methods

Fifty axial cut magnetic resonance (MR) images of the affected lumbar disc level that belonged to different patients (age, 37.8 ± 10.4 years; 33 males and 17 females) were chosen and given to five orthopaedic residents for grading according to the Pfirrmann's MR image-based grading of lumbar nerve root compromise. Responses were received in the form of categorical variables and reliability was assessed.

Results

On doing percentage statistics, we found that 14 images had 100% agreement, 22 had 80% agreement and 14 had 60% agreement. We inferred an overall agreement of 80% ± 15.1%. In addition, interrater reliability was determined by calculating the Fleiss' kappa, which was found to be 0.521, signifying moderate agreement. Intrarater reliability was determined by calculating Cohen's kappa, which was found to be 0.696, signifying substantial agreement.

Conclusions

Our residents took only a short time to learn and reproduce this grading system as ratings that proved to be moderately reliable. Even though the value of kappa was slightly lower, reliability was similar to that of the original authors. We think that this grading system can be adopted in day-to-day practice by framing appropriate rules to interpret MR images where the nerve roots are not visible.

Limits of Calcaneal Lengthening for Treating Planovalgus Foot Deformity in Children With Cerebral Palsy

BACKGROUND

Calcaneal lengthening is used to correct symptomatic planovalgus foot deformity, but outcomes have been less satisfactory in children with cerebral palsy. This study aimed to define limits of calcaneal lengthening by analyzing the risk factors for undercorrection of deformity.

METHODS

We retrospectively reviewed 20 cases of children with cerebral palsy who underwent calcaneal lengthening of 30 planovalgus feet at a mean age of 11.9 years. Foot deformities were evaluated by the anteroposterior talo-first metatarsal angle (normal, 10 ± 7.0 degrees), lateral talo-first metatarsal angle (normal, 13 ± 7.5 degrees), and lateral calcaneal pitch angle (normal, 17 ± 6.0 degrees) on standing foot radiographs. Among these parameters, a corrected foot was defined as 2 or 3 parameters being corrected to within a normal range, and an undercorrected foot was only 1 or no parameter being corrected to within a normal range. Factors were compared between the corrected group and undercorrected group for significant predictors, and cutoff values of predictors were calculated for use as a clinical guideline.

RESULTS

Seventeen planovalgus feet were corrected satisfactorily by calcaneal lengthening, while the other 13 feet were undercorrected. Undercorrected feet had a greater preoperative anteroposterior talonavicular angle (33.7 vs 22.8 degrees, P = .001) and a smaller lateral calcaneal pitch (-1.7 vs 5.6 degrees, P = .03). A talonavicular angle of more than 24 degrees and calcaneal pitch less than -5 degrees were identified as cutoff values using a receiver operating characteristic curve. The predicted probability of undercorrection was 100% (9/9 feet) for 2 positive predictors, 50% (8/16 feet) for 1 positive predictor, and 0 (0/5 feet) for zero predictors.

CONCLUSION

A talonavicular lateral subluxation of more than 24 degrees on the anteroposterior radiograph and a calcaneal pitch angle less than -5 degrees on the lateral radiograph were 2 independent predictors that could be used to identify a planovalgus deformity that would be beyond the corrective capacity of calcaneal lengthening to restore normal alignment. Level of Evidence Retrospective case control study, level III.

Assessment of Anteroposterior Subpedicular Approach and Oblique Scotty Dog Subpedicular Approach for Selective Nerve Root Block

Background

The technique used to administer a selective nerve root block (SNRB) varies depending on individual expertise. Both the anteroposterior (AP) subpedicular approach and oblique Scotty dog subpedicular approach are widely practiced. However, the literature does not provide a clear consensus regarding which approach is more suitable. Hence, we decided to analyse the procedural parameters and clinical outcomes following SNRBs using these two approaches.

Methods

Patients diagnosed with a single lumbar herniated intervertebral disc (HIVD) refractory to conservative management but not willing for immediate surgery were selected for a prospective nonrandomized comparative study. An SNRB was administered as a therapeutic alternative using the AP subpedicular approach in one group (n = 25; mean age, 45 ± 5.4 years) and the oblique Scotty dog subpedicular approach in the other group (n = 22; mean age, 43.8 ± 4.7 years). Results were compared in terms of the duration of the procedure, the number of C-arm exposures, accuracy, pain relief, functional outcome and the duration of relief.

Results

Our results suggest that the oblique Scotty dog subpedicular approach took a significantly longer duration (p = 0.02) and a greater number of C-arm exposures (p = 0.001). But, its accuracy of needle placement was 95.5% compared to only 72% using the AP subpedicular approach (p = 0.03). There was no significant difference in terms of clinical outcomes between these approaches.

Conclusions

The AP subpedicular approach was simple and facile, but the oblique Scotty dog subpedicular approach was more accurate. However, a brief window period of pain relief was achieved irrespective of the approaching technique used.

Retrospective radiological outcome analysis following teriparatide use in elderly patients undergoing multilevel instrumented lumbar fusion surgery

Elderly patients with chronic nonresolving symptoms due to degenerative spine pathologies are prone to have poor surgical outcomes and hardware-related complications, especially following multilevel instrumented lumbar fusion surgeries. With intention of analyzing if teriparatide can be an effective adjunct therapy to surgical management, radiological outcomes are studied. Sixty-two elderly patients were divided into 2 similar groups. Group 1 (n = 30; mean age = 69.83 years; fusion levels = 137; screws = 269) had taken teriparatide (20 mcg SC injection, once daily) for a duration of 7.4 ± 2.4 months following surgery and Group 2 (n = 32; mean age = 70.38 years; fusion levels = 144; screws = 283) did not take teriparatide. Radiological evaluation was done to determine the state of postero lateral fusion mass and to investigate the incidence of pedicle screw loosening at 1-year follow-up. Unilateral or bilateral bridging bone formation across the transverse process of adjacent vertebras showing continuous trabeculation suggestive of solid fusion was obtained in 66.7% patients in the teriparatide group and 50% patients in the control group (P = 0.20). 13.4% of the total no. of screws showed signs of loosening in the teriparatide group, compared to 24.4% in the control group (P = 0.001). Percentage of patients achieving solid fusion following teriparatide use was found to be more than that of the control group. This difference may have clinical importance but was not statistically significant. However, teriparatide use was more significantly influential in reducing the incidence of subsequent pedicle screw loosening.