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Andrei F. Joaquim, Wellington K. Hsu and Alpesh A. Patel

Cervical surgery is one of the most common surgical spinal procedures performed around the world. The authors performed a systematic review of the literature reporting the outcomes of cervical spine surgery in high-level athletes in order to better understand the nuances of cervical spine pathology in this population.

A search of the MEDLINE database using the search terms “cervical spine” AND “surgery” AND “athletes” yielded 54 abstracts. After exclusion of publications that did not meet the criteria for inclusion, a total of 8 papers reporting the outcome of cervical spine surgery in professional or elite athletes treated for symptoms secondary to cervical spine pathology (focusing in degenerative conditions) remained for analysis. Five of these involved the management of cervical disc herniation, 3 were specifically about traumatic neurapraxia.

The majority of the patients included in this review were American football players. Anterior cervical discectomy and fusion (ACDF) was commonly performed in high-level athletes for the treatment of cervical disc herniation. Most of the studies suggested that return to play is safe for athletes who are asymptomatic after ACDF for cervical radiculopathy due to disc herniation. Surgical treatment may provide a higher rate of return to play for these athletes than nonsurgical treatment. Return to play after cervical spinal cord contusion may be possible in asymptomatic patients. Cervical cord signal changes on MRI may not be an absolute contraindication for return to play in neurologically intact patients, according to some authors. Cervical contusions secondary to cervical stenosis may be associated with a worse outcome and a higher recurrence rate than those those secondary to disc herniation. The evidence is low (Level IV) and individualized treatment must be recommended.

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Danielle S. Chun, Kevin C. Baker and Wellington K. Hsu

OBJECT

Failed solid bony fusion, or pseudarthrosis, is a well-known complication of lumbar arthrodesis. Recent advances in radiographic technology, biologics, instrumentation, surgical technique, and understanding of the local biology have all aided in the prevention and treatment of pseudarthrosis. Here, the current literature on the diagnosis and management of lumbar pseudarthroses is reviewed.

METHODS

A systematic literature review was conducted using the MEDLINE and Embase databases in order to search for the current radiographie diagnosis and surgical treatment methods published in the literature (1985 to present). Inclusion criteria included: 1) published in English; 2) level of evidence I–III; 3) diagnosis of degenerative lumbar spine conditions and/or history of lumbar spine fusion surgery; and 4) comparative studies of 2 different surgical techniques or comparative studies of imaging modality versus surgical exploration.

RESULTS

Seven studies met the inclusion criteria for current radiographie imaging used to diagnose lumbar pseudarthrosis. Plain radiographs and thin-cut CT scans were the most common method for radiographie diagnosis. PET has been shown to be a valid imaging modality for monitoring in vivo active bone formation. Eight studies compared the surgical techniques for managing and preventing failed lumbar fusion. The success rates for the treatment of pseudarthrosis are enhanced with the use of rigid instrumentation.

CONCLUSIONS

Spinal fusion rates have improved secondary to advances in biologies, instrumentation, surgical techniques, and understanding of local biology. Treatment of lumbar pseudarthrosis includes a variety of surgical options such as replacing loose instrumentation, use of more potent biologies, and interbody fusion techniques. Prevention and recognition are important tenets in the algorithm for the management of spinal pseudarthrosis.

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Joseph J. Schreiber, Paul A. Anderson and Wellington K. Hsu

Assessing local bone quality on CT scans with Hounsfield unit (HU) quantification is being used with increasing frequency. Correlations between HU and bone mineral density have been established, and normative data have been defined throughout the spine. Recent investigations have explored the utility of HU values in assessing fracture risk, implant stability, and spinal fusion success. The information provided by a simple HU measurement can alert the treating physician to decreased bone quality, which can be useful in both medically and surgically managing these patients.

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Paul M. Arnold, Zoher Ghogawala and Candan Tamerler

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Barrett S. Boody, Surabhi Bhatt, Aditya S. Mazmudar, Wellington K. Hsu, Nan E. Rothrock and Alpesh A. Patel

OBJECTIVE

The Patient-Reported Outcomes Measurement Information System (PROMIS), which is funded by the National Institutes of Health, is a set of adaptive, responsive assessment tools that measures patient-reported health status. PROMIS measures have not been validated for surgical patients with cervical spine disorders. The objective of this project is to evaluate the validity (e.g., convergent validity, known-groups validity, responsiveness to change) of PROMIS computer adaptive tests (CATs) for pain behavior, pain interference, and physical function in patients undergoing cervical spine surgery.

METHODS

The legacy outcome measures Neck Disability Index (NDI) and SF-12 were used as comparisons with PROMIS measures. PROMIS CATs, NDI-10, and SF-12 measures were administered prospectively to 59 consecutive tertiary hospital patients who were treated surgically for degenerative cervical spine disorders. A subscore of NDI-5 was calculated from NDI-10 by eliminating the lifting, headaches, pain intensity, reading, and driving sections and multiplying the final score by 4. Assessments were administered preoperatively (baseline) and postoperatively at 6 weeks and 3 months. Patients presenting for revision surgery, tumor, infection, or trauma were excluded. Participants completed the measures in Assessment Center, an online data collection tool accessed by using a secure login and password on a tablet computer. Subgroup analysis was also performed based on a primary diagnosis of either cervical radiculopathy or cervical myelopathy.

RESULTS

Convergent validity for PROMIS CATs was supported with multiple statistically significant correlations with the existing legacy measures, NDI and SF-12, at baseline. Furthermore, PROMIS CATs demonstrated known-group validity and identified clinically significant improvements in all measures after surgical intervention. In the cervical radiculopathy and myelopathic cohorts, the PROMIS measures demonstrated similar responsiveness to the SF-12 and NDI scores in the patients who self-identified as having postoperative clinical improvement. PROMIS CATs required a mean total of 3.2 minutes for PROMIS pain behavior (mean ± SD 0.9 ± 0.5 minutes), pain interference (1.2 ± 1.9 minutes), and physical function (1.1 ± 1.4 minutes) and compared favorably with 3.4 minutes for NDI and 4.1 minutes for SF-12.

CONCLUSIONS

This study verifies that PROMIS CATs demonstrate convergent and known-groups validity and comparable responsiveness to change as existing legacy measures. The PROMIS measures required less time for completion than legacy measures. The validity and efficiency of the PROMIS measures in surgical patients with cervical spine disorders suggest an improvement over legacy measures and an opportunity for incorporation into clinical practice.

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Marco C. Mendoza, Kevin A. Sonn, Abhishek S. Kannan, Sharath S. Bellary, Sean M. Mitchell, Gurmit Singh, Christian Park, Chawon Yun, Stuart R. Stock, Erin L. Hsu and Wellington K. Hsu

OBJECTIVE

This study aims to quantify the impact of vancomycin powder application on new bone formation and spine fusion rates in a rat posterolateral arthrodesis model.

METHODS

Thirty-six female Sprague-Dawley rats underwent a posterolateral lumbar spinal fusion (PLF) at the L-4 and L-5 vertebrae. Fusion was elicited via implantation of an absorbable collagen sponge containing 3 µg rhBMP-2. Rats were divided into 3 groups: no vancomycin (control), standard-dose vancomycin, and high-dose vancomycin, based on what was applied to the fusion bed. Clinical studies typically describe the application of 1 g vancomycin into the surgical wound. Presuming an average individual patient weight of 70 kg, a weight-based equivalent dose of vancomycin powder was applied subfascially in the PLF model constituting a “standard-dose” treatment group (14.3 mg/kg, n = 12). To determine whether there is a critical threshold beyond which vancomycin increases the risk of pseudarthrosis, a 10-fold higher dose was administered to a “high-dose” treatment group (143 mg/kg, n = 12). No vancomycin powder was applied to the surgical site in the control group (n = 12). Fusion was evaluated with plain radiographs at 4 and 8 weeks after surgery. The spines were harvested after the 8-week radiographs were obtained and evaluated using manual palpation, microCT analysis, and histological analysis.

RESULTS

Radiographs demonstrated equivalent bridging bone formation in all groups. No significant differences in fusion scores were seen in the standard-dose (mean 2.25) or high-dose (2.13) treatment groups relative to untreated control animals (1.78). Similarly, fusion rates did not differ significantly different between vancomycin-treated animals (100% for both groups) and control animals (92%). Quantification of new bone formation via microCT imaging revealed no significant between-groups differences in the volume of newly regenerated bone (control vs standard-dose vancomycin, p = 0.57; control vs high-dose vancomycin, p = 0.53).

CONCLUSIONS

This is the first in vivo study to specifically address the development of pseudarthrosis after intrawound application of vancomycin during fusion surgery. Our results demonstrate that vancomycin powder does not inhibit fusion rates at a dose that is the weight-percentage equivalent of what is routinely used by surgeons. Moreover, bone formation and fusion rates were not reduced even after administration of a vancomycin dose that is 10-fold higher than that which is typically administered clinically. Our findings suggest that if there is a critical threshold above which vancomycin inhibits bone healing, such a dose is out of the range which might be considered reasonable for clinical use.