Safety outcomes and improvement in pain scores after radiologist-performed fluoroscopy-guided interlaminar cervical epidural steroid injection.

INTRODUCTION: Image-guided spine injections are an important tool in the management of patients with a variety of spinal pathologies. Our practice offers radiologist-performed fluoroscopy-guided interlaminar cervical epidural steroid injection (ESI) routinely performed in the outpatient setting. The purpose of this study was to evaluate clinical outcomes and improvement in pain scores after radiologist-performed cervical ESI. METHODS: An institutional database was used to retrospectively identify cervical injections performed between October 2016 and October 2022. All injections were performed at the C7-T1 level utilizing 1.0 mL of 10 mg/mL dexamethasone without epidural anesthetic. The Numerical Rating Scale (NRS) was used to assess pain improvement. Cervical MRI was reviewed to assess pre-injection cervical disease severity. Patient charts were reviewed for any post-injection complications. RESULTS: A total of 251 cervical injections in 186 patients met our inclusion criteria with mean clinical follow up of 28.5 months (range 0.2 - 73.0 months). No patients experienced any major complications after injection. Post-injection pain scores were available for 218 of 251 injections (86.9%) with mean follow-up of 11.8 days (range 6 - 57 days). There was a significant improvement in pain scores from a mean pre-injection NRS score of 5.2/10 to 3.0/10 (p < .0001). 117 patients (53.7%) reported ≥ 50% improvement after injection. Patients who had prior injection were more likely to report ≥ 50% pain improvement after subsequent injection (p = .012). CONCLUSION: Radiologist-performed fluoroscopy-guided interlaminar cervical ESI at the C7-T1 level is a safe and effective tool in the management of patients with cervical pathology.

Performance Outcomes and Return-to-Sport Rate of National Hockey League Athletes Vary After Common Orthopedic Surgical Procedures.

OBJECTIVE: Evaluate performance-based outcomes and return-to-sport rate in National Hockey League (NHL) athletes. DESIGN: Retrospective cohort study. SETTING: Public records. No direct patient care was provided. PARTICIPANTS: National Hockey League athletes who underwent different orthopedic procedures were identified using public records. Three hundred thirty-seven athletes met inclusion criteria. INDEPENDENT VARIABLES: Common orthopedic surgical procedures in NHL athletes. MAIN OUTCOME MEASURES: Return-to-play and preoperative and postoperative performance measures were collected to calculate a position-specific performance score. Short-term and medium-term outcomes were defined as 1 and 2 to 3 seasons after surgery, respectively. RESULTS: Three hundred seven athletes (92.6%) successfully returned to play. The number of games played during the first season after surgery compared with baseline was significantly decreased for hip arthroscopy (HA), noninstability shoulder arthroscopy (ie, shoulder arthroscopy procedure to address pathology other than shoulder instability), knee arthroscopy, and sports hernia repair (P = 0.002, 0.009, 0.03, and 0.01, respectively). The number of games played for seasons 2 and 3 after surgery was significantly decreased for both HA and noninstability shoulder arthroscopy (P = 0.01 and 0.001, respectively). Short-term postoperative performance scores were significantly decreased for HA, noninstability shoulder arthroscopy, and anterior cruciate ligament reconstruction (P = 0.00004, 0.02, and 0.02, respectively) while medium-term scores were significantly decreased for HA only (P = 0.009). CONCLUSIONS: National Hockey League athletes return to play at a high rate after common orthopedic surgeries. However, certain procedures portend poorer performance scores and game participation than others. In particular, HA and noninstability shoulder arthroscopy have the greatest negative effect on NHL careers after surgery.

Evidence-Based Management of Spinal Conditions in the Elite Athlete.

Spinal injuries are common and are a significant burden in the professional athlete population. From single-level disk herniation to career-ending fractures, the consequences of these conditions vary widely. Both contact and noncontact injuries can substantially affect the health and performance of elite athletes competing in a variety of sports. The nature and severity of these injuries have great influence on the prospects for full recovery and successful return to play. Common spinal injuries, management decisions, and return to play prospects are important considerations in the professional athlete population.

Consensus Recommendations on the Prehospital Care of the Injured Athlete With a Suspected Catastrophic Cervical Spine Injury.

INTRODUCTION: Sports participation is among the leading causes of catastrophic cervical spine injury (CSI) in the United States. Appropriate prehospital care for athletes with suspected CSIs should be available at all levels of sport. The goal of this project was to develop a set of best-practice recommendations appropriate for athletic trainers, emergency responders, sports medicine and emergency physicians, and others engaged in caring for athletes with suspected CSIs. METHODS: A consensus-driven approach (RAND/UCLA method) in combination with a systematic review of the available literature was used to identify key research questions and develop conclusions and recommendations on the prehospital care of the spine-injured athlete. A diverse panel of experts, including members of the National Athletic Trainers' Association, the National Collegiate Athletic Association, and the Sports Institute at UW Medicine participated in 4 Delphi rounds and a 2-day nominal group technique (NGT) meeting. The systematic review involved 2 independent reviewers and 4 rounds of blinded review. RESULTS: The Delphi process identified 8 key questions to be answered by the systematic review. The systematic review comprised 1544 studies, 49 of which were included in the final full-text review. Using the results of the systematic review as a shared evidence base, the NGT meeting created and refined conclusions and recommendations until consensus was achieved. CONCLUSIONS: These conclusions and recommendations represent a pragmatic approach, balancing expert experiences and the available scientific evidence.

Platelet-Rich Plasma, Bone Morphogenetic Protein, and Stem Cell Therapies.

The frequency of use of "biologics," including platelet-rich plasma (PRP), bone morphogenetic protein (BMP), and stem cell therapies in the treatment of orthopaedic conditions has significantly increased over the past few decades. The use of PRP and stem cells has been proposed for a wide variety of conditions including knee and hip osteoarthritis (OA), tendon strains and tendinopathies, muscle strains, and acute and chronic soft-tissue injuries. It has also been proposed for use in the enhancement of healing during surgical treatments. BMP has seen use in promoting fracture union and spinal fusion and has been researched as an adjunct in other procedures as well. The current state of the literature in the use and support of these biologics is outlined here.

Prognosis Following Hip Arthroscopy Varies in Professional Athletes Based on Sport.

PURPOSE: To evaluate return to play (RTP) and performance-based outcomes in professional athletes across 4 major North American team sports following hip arthroscopy. METHODS: Professional athletes of the National Football League, Major League Baseball (MLB), National Basketball Association, and National Hockey League (NHL) who underwent hip arthroscopy were identified using an established protocol of public reports. Sport-specific statistics were collected before and after hip arthroscopy for each athlete, leading to a performance score. RTP was defined as the first regular or postseason game played following surgery. RESULTS: A total of 151 arthroscopic hip procedures were performed on 131 professional athletes. The overall RTP rate after arthroscopic hip surgery was found to be 88.7% (134 of 151 arthroscopic hip surgeries), with no significant difference between sports. The median number of seasons played after hip arthroscopy were 2.7, 2.3, 1.1, and 0.9 for the National Football League, National Basketball Association, MLB, and NHL cohorts, respectively, with no significant difference between sports. MLB and NHL cohorts experienced a decrease in games played in the first season following hip arthroscopy (P = .04, P = .01), whereas NHL players also experienced a decrease in games played in seasons 2 and 3 postoperatively (P = .001). Performance scores decreased in the NHL cohort for all seasons postoperatively (P < .001, P = .003). No other statistically significant differences were found when comparing players of different sports. CONCLUSIONS: Although professional athletes demonstrate a high rate of RTP following hip arthroscopy across the 4 major North American team sports, hockey players demonstrate the worst prognosis following hip arthroscopy, with sustained decreases in games played and performance in the first 3 seasons postoperatively. LEVEL OF EVIDENCE: Level III, retrospective comparative therapeutic trial.

Impact of CrossFit-Related Spinal Injuries.

INTRODUCTION: Exercise-related injuries (ERIs) are a common cause of nonfatal emergency department and hospital visits. CrossFit is a high-intensity workout regimen whose popularity has grown rapidly. However, ERIs due to CrossFit remained under investigated. METHODS: All patients who presented to the main hospital at a major academic center complaining of an injury sustained performing CrossFit between June 2010 and June 2016 were identified. Injuries were classified by anatomical location (eg, knee, spine). For patients with spinal injuries, data were collected including age, sex, body mass index (BMI), CrossFit experience level, symptom duration, type of symptoms, type of clinic presentation, cause of injury, objective neurological examination findings, imaging type, number of clinic visits, and treatments prescribed. RESULTS: Four hundred ninety-eight patients with 523 CrossFit-related injuries were identified. Spine injuries were the most common injuries identified, accounting for 20.9%. Among spine injuries, the most common location of injury was the lumbar spine (83.1%). Average symptom duration was 6.4 months ± 15.1, and radicular complaints were the most common symptom (53%). A total of 30 (32%) patients had positive findings on neurologic examination. Six patients (6.7%) required surgical intervention for treatment after failing an average of 9.66 months of conservative treatment. There was no difference in age, sex, BMI, or duration of symptoms of patients requiring surgery with those who did not. CONCLUSIONS: CrossFit is a popular, high-intensity style workout with the potential to injure its participants. Spine injuries were the most common type of injury observed and frequently required surgical intervention.

Intervertebral disc herniation in elite athletes.

Intervertebral disc herniations are a common cause of neck and back pain in athletes. It is thought to be more prevalent in athletes than in the general population due to the consistent pressure placed on the spine and concurrent microtraumas that are unable to heal. Prevention focuses on neck and trunk stability and flexibility, training on proper technique, and rule changes to minimize catastrophic injuries. The evaluation for athletes includes a full neurologic exam and imaging. The imaging modality of choice is MRI, but CT myelography can be a useful alternative. Standard management includes a six week trial of conservative treatment with hiatus from injurious activity and anti-inflammatory medication. If nonoperative management fails, operative treatment has been shown to lead to excellent clinical outcomes in this patient population. Special consideration to prevention needs to be further analyzed. Furthermore, more robust studies on alternative non-operative and operative treatment modalities for this patient population are also needed.

Aryl Hydrocarbon Receptor Antagonists Mitigate the Effects of Dioxin on Critical Cellular Functions in Differentiating Human Osteoblast-Like Cells.

The inhibition of bone healing in humans is a well-established effect associated with cigarette smoking, but the underlying mechanisms are still unclear. Recent work using animal cell lines have implicated the aryl hydrocarbon receptor (AhR) as a mediator of the anti-osteogenic effects of cigarette smoke, but the complexity of cigarette smoke mixtures makes understanding the mechanisms of action a major challenge. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD, dioxin) is a high-affinity AhR ligand that is frequently used to investigate biological processes impacted by AhR activation. Since there are dozens of AhR ligands present in cigarette smoke, we utilized dioxin as a prototype ligand to activate the receptor and explore its effects on pro-osteogenic biomarkers and other factors critical to osteogenesis using a human osteoblast-like cell line. We also explored the capacity for AhR antagonists to protect against dioxin action in this context. We found dioxin to inhibit osteogenic differentiation, whereas co-treatment with various AhR antagonists protected against dioxin action. Dioxin also negatively impacted cell adhesion with a corresponding reduction in the expression of integrin and cadherin proteins, which are known to be involved in this process. Similarly, the dioxin-mediated inhibition of cell migration correlated with reduced expression of the chemokine receptor CXCR4 and its ligand, CXCL12, and co-treatment with antagonists restored migratory capacity. Our results suggest that AhR activation may play a role in the bone regenerative response in humans exposed to AhR activators, such as those present in cigarette smoke. Given the similarity of our results using a human cell line to previous work done in murine cells, animal models may yield data relevant to the human setting. In addition, the AhR may represent a potential therapeutic target for orthopedic patients who smoke cigarettes, or those who are exposed to secondhand smoke or other environmental sources of aryl hydrocarbons.

Athletic performance and career longevity following anterior cruciate ligament reconstruction in the National Basketball Association.

PURPOSE: To identify the impact of anterior cruciate ligament (ACL) reconstruction on performance and career longevity for National Basketball Association (NBA) players. METHODS: Seventy-nine players (80 knees) with acute ACL tears in the NBA between the 1984-2014 seasons, and 112 age, height, weight, and performance-matched controls were identified. Pre- and post-injury performance outcomes including seasons played, games played, games started, minutes per game, points per game, field goals, 3-point shots, rebounds, assists, steals, blocks, turnovers, personal fouls, usage percentage and player efficiency ratings were compared between cases and controls using independent samples t tests and Fisher's exact tests. RESULTS: Sixty-eight of seventy-nine players (86.1 %) returned to play in the NBA following ACL reconstruction. Mean length of post-operative play was 1.84 years shorter than matched controls (P = 0.001). There was a significantly higher rate of attrition from professional basketball for players with a history of ACL reconstruction (P = 0.014). In the first full season following surgery, players started in 15.5 fewer games (P = 0.001), they played in 17.3 fewer games (P < 0.001), and had combined player efficiency ratings 2.35 points lower (P = 0.001) when compared to matched controls. Over the length of their careers, players competed in 22.2 fewer games per season (P = 0.009). CONCLUSIONS: There is a high rate of return to sport in the NBA following ACL reconstruction, although playing time, games played, player efficiency ratings and career lengths are significantly impacted in the post-operative period. These data should be used to manage patients' expectations regarding their abilities to return to elite levels of athletic performance.

The role of intense athletic activity on structural lumbar abnormalities in adolescent patients with symptomatic low back pain.

PURPOSE: To determine if adolescent athletics increases the risk of structural abnormalities in the lumbar spine. METHODS: A retrospective review of patients (ages 10-18) between 2004 and 2012 was performed. Pediatric patients with symptomatic low back pain, a lumbar spine MRI, and reported weekly athletic activity were included. Patients were stratified to an "athlete" and "non-athlete" group. Lumbar magnetic resonance and plain radiographic imaging was randomized, blinded, and evaluated by two authors for a Pfirrmann grade, herniated disc, and/or pars fracture. RESULTS: A total of 114 patients met the inclusion criteria and were stratified into 66 athletes and 48 non-athletes. Athletes were more likely to have abnormal findings compared to non-athletes (67 vs. 40 %, respectively, p = 0.01). Specifically, the prevalence of a spondylolysis with or without a slip was higher in athletes vs. non-athletes (32 vs. 2 %, respectively, p = 0.0003); however, there was no difference in the average Pfirrmann grade (1.19 vs. 1.14, p = 0.41), percentage of patients with at least one degenerative disc (39 vs. 31 %, p = 0.41), or disc herniation (27 vs. 33 %, p = 0.43). Body mass index, smoking history, and pelvic incidence (51.5° vs. 48.7°, respectively, p = 0.41) were similar between the groups. CONCLUSION: Adolescents with low back pain have a higher-than-expected prevalence of structural pathology regardless of athletic activity. Independent of pelvic incidence, adolescent athletes with low back pain had a higher prevalence of spondylolysis compared to adolescent non-athletes with back pain, but there was no difference in associated disc degenerative changes or herniation.

Cervical spine surgery in professional athletes: a systematic review.

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.

The effect of rhBMP-2 in a novel, non-instrumented extremity nonunion model.

BACKGROUND: Pre-clinical models of bony nonunion typically employ critical-length defects. However, these models may not accurately reflect clinical practice since many nonunions are diagnosed without bone loss. We developed a non-displaced rat ulna fracture model in order to examine the efficacy of recombinant human bone morphogenetic protein-2 (rhBMP-2) with an absorbable collagen sponge (ACS) for nonunion treatment. METHODS: Transverse diaphyseal ulna fractures were created in 24 Sprague-Dawley rats. Eight animals (Group 1: Nonunion) received no further intervention. The remaining 16 animals were treated with 5 µg rhBMP-2/ACS at 8 weeks after the original intervention (Group 2: Nonunion + BMP) or at the time of initial injury (Group 3: Fresh fracture + BMP). RESULTS: In Group 1, 7 of 8 fractures demonstrated gross motion and a persistent radiographic gap (12.5% healing rate). In Groups 2 and 3, fractures healed at a rate of 75% (6 of 8 in each group) as determined by manual and radiographic evaluation. Biomechanical testing for torque load-to-failure and torsional stiffness demonstrated no significant difference between healed specimens treated with rhBMP-2. CONCLUSIONS: To our knowledge, this is the first description of a physiologic, non-stabilized, non-defect fracture nonunion model in a rodent. Furthermore, unlike previous nonunion models, the healing rates after treatment with rhBMP-2 are comparable to that of clinical data, suggesting that this model may provide an environment more representative of nonunions in humans.

Outcomes of Lumbar Discectomy in Elite Athletes: The Need for High-level Evidence.

BACKGROUND: Although lumbar discectomy for treatment of lumbar disc herniation in the general population generally improves patients' pain, function, and validated outcomes scores, results of treatment in elite athletes may differ because of the unique performance demands required of competitive athletes. QUESTIONS/PURPOSES: We performed a systematic review to answer the following questions: (1) What proportion of athletes return to play after lumbar discectomy, and what is the effect of sport? (2) What is the expected recovery time after lumbar discectomy in elite athletes? (3) What is the expected career length and performance of elite athletes after lumbar discectomy? METHODS: We performed a systematic literature review of articles of lumbar discectomy in the elite athlete population through the MEDLINE and EMBASE databases from 1947 to 2013. Elite athletes were defined as professional, Olympic, or National Collegiate Athletic Association Division I collegiate level. A hand search of the references of all key articles was performed to ensure inclusion of all relevant studies. Information regarding study design, types of athletes, level of sport, recovery time, return to sport, length of career after surgery, and career performance after surgery was extracted. Ten articles met the inclusion and exclusion criteria for this review. These articles consisted of levels III and IV data and were graded based on the Methodological Index for Non-Randomized Studies (MINORS) scale. RESULTS: Overall, the studies included in this review found that 75% to 100% of athletes were able to return to elite competition after operative treatment. In general, a higher proportion of baseball players returned to elite competition compared with other athletes. The reported recovery period after lumbar discectomy ranged from 2.8 to 8.7 months. The average career length after lumbar discectomy ranged from 2.6 to 4.8 years. Elite athletes reached an average of 64.4% to 103.6% of baseline preoperative statistics after lumbar discectomy with variable performance based on sport. CONCLUSIONS: A high proportion of elite athletes undergoing lumbar discectomy return to play with variable performance scores on return. Future prospective studies are needed to compare the recovery time, career longevity, and performance for athletes undergoing lumbar discectomy versus nonoperative treatment for lumbar disc herniation.

Lumbar pseudarthrosis: a review of current diagnosis and treatment.

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.

Biologics in spine arthrodesis.

Spine fusion is a tool used in the treatment of spine trauma, tumors, and degenerative disorders. Poor outcomes related to failure of fusion, however, have directed the interests of practitioners and scientists to spinal biologics that may impact fusion at the cellular level. These biologics are used to achieve successful arthrodesis in the treatment of symptomatic deformity or instability. Historically, autologous bone grafting, including iliac crest bong graft harvesting, had represented the gold standard in spinal arthrodesis. However, due to concerns over potential harvest site complications, supply limitations, and associated morbidity, surgeons have turned to other bone graft options known for their osteogenic, osteoinductive, and/or osteoconductive properties. Current bone graft selection includes autograft, allograft, demineralized bone matrix, ceramics, mesenchymal stem cells, and recombinant human bone morphogenetic protein. Each pose their respective advantages and disadvantages and are the focus of ongoing research investigating the safety and efficacy of their use in the setting of spinal fusion. Rh-BMP2 has been plagued by issues of widespread off-label use, controversial indications, and a wide range of adverse effects. The risks associated with high concentrations of exogenous growth factors have led to investigational efforts into nanotechnology and its application in spinal arthrodesis through the binding of endogenous growth factors. Bone graft selection remains critical to successful fusion and favorable patient outcomes, and orthopaedic surgeons must be educated on the utility and limitations of various biologics in the setting of spine arthrodesis.

Surgical Site Infections in Spinal Surgery.

Surgical site infections (SSIs) are a potentially devastating complication of spine surgery. SSIs are defined by the Centers for Disease Control and Prevention as occurring within 30 days of surgery or within 12 months of placement of foreign bodies, such as spinal instrumentation. SSIs are commonly categorized by the depth of surgical tissue involvement (ie, superficial, deep incisional, or organ and surrounding space). Postoperative infections result in increased costs and postoperative morbidity. Because continued research has improved the evaluation and management of spinal infections, spine surgeons must be aware of these modalities. The controversies in evaluation and management of SSIs in spine surgery will be reviewed.

Vertebral Osteomyelitis and Spinal Epidural Abscess: An Evidence-based Review.

Spinal infections have historically been associated with significant morbidity and mortality. Current treatment protocols have improved patient outcomes through prompt and accurate infection identification, medical treatment, and surgical interventions. Medical and surgical management, however, remains controversial because of a paucity of high-level evidence to guide decision making. Despite this, an awareness of presenting symptoms, pertinent risk factors, and common imaging findings are critical for treating spine infections. The purpose of this article is to review the recent literature and present the latest evidence-based recommendations for the most commonly encountered primary spinal infections: vertebral osteomyelitis and epidural abscess.

Factors influencing arthrodesis rates in a rabbit posterolateral spine model with iliac crest autograft.

PURPOSE: The rabbit posterolateral intertransverse spine arthrodesis model has been widely used to evaluate spinal biologics. However, to date, the validity and reproducibility of performance of iliac crest bone graft, the most common and critical control group, has not been firmly established. We evaluated original research publications that utilized this model, identified which experimental conditions affected fusion rates, and developed an algorithm to predict fusion rates for future study designs. METHODS: A MEDLINE search was performed for publications through December, 2011 that utilized this model to evaluate fusion rates elicited by iliac crest autograft. All study parameters were recorded, and logistic regression analyses were performed to determine the effects of these variables on fusion rates as determined by either manual palpation or radiographs. RESULTS: Seventy studies with 959 rabbits in 102 groups met the inclusion criteria. Excluding studies that measured fusion at 4 or fewer weeks or intentionally tried to decrease the fusion rate, the overall fusion rate for autograft was 58.3 ± 16.3 % (mean ± SD) as determined by manual palpation and 66.4 ± 17.8 % by plain radiographs. Regression analysis demonstrated a difference between these outcome measures with a trend towards significance (p = 0.09). Longer time points and larger volumes of autograft resulted in significantly greater reported fusion rates (p < 0.0001 and p < 0.05, respectively). Neither strain, age, weight, nor vertebral level significantly affected fusion rates. CONCLUSIONS: Although experimental conditions varied across studies, time point evaluation and autograft volume significantly affected fusion rates. Despite some variability demonstrated across certain studies, we demonstrated that when the time point and volume of autograft were controlled for, the iliac crest control group of the rabbit posterolateral spinal arthrodesis model is both reliable and predictably affected by different experimental conditions.

Use of computed tomography for assessing bone mineral density.

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.