Faculty Bibliography

Anterior removal of a lumbar total disc replacement implant is often a very technically demanding procedure. The anterior retroperitoneal anatomy is prone to scarring, limiting remobilization and making a direct anterior exposure above the L5-S1 level difficult if not impossible to achieve safely. Anterolateral approach strategies can be more safely achieved at L4-L5 and above, but may require vertebral osteotomy in order to remove a keeled prosthesis. Successful conversion to a fusion with implant removal can be achieved, even when osteotomy is needed for implant removal. This Grand Rounds case presentation involves an unusual late retroperitoneal abscess following two-level TDR with direct extension to one of the implants, and the subsequent nonoperative and operative management. Removal of a well-fixed keeled implant at the L4-L5 level following nonoperative treatment of a surrounding retroperitoneal abscess and conversion to fusion represents close to, if not a 'worst-case' scenario for revision TDR. However, with proper preoperative planning and surgical experience, a safe and successful procedure can be the end result

STUDY DESIGN: Retrospective study of patients enrolled in a prospective randomized Food and Drug Administration trial with single level cervical disc replacement (CDR) with the ProDisc-C (Synthes, Paoli, PA). OBJECTIVE: Evaluate the segmental range of motion (ROM) in the cervical spine pre- and postoperative after CDR. SUMMARY OF BACKGROUND INFORMATION: Each cervical level is believed to have its own biomechanical characteristics, ultimately leading to different sagittal and lateral ROM. Our understanding of the factors that influence motion after CDR continues to change and expand. METHODS: One hundred sixty-four patients with single level ProDisc-C arthroplasty were evaluated radiographically using Medical Metrics (QMATM, Medical Metrics, Inc., Houston, TX). Pre- and postoperative disc height and ROM were measured from standing lateral and flexion-extension radiographs. Of these 164 patients, 44 had a CDR at C6/C7, 96 at C5/C6, 18 at C4/C5, and 6 at C3/C4. The mean follow-up was of 24 months. Statistical analysis evaluated the difference in mean ROM between the groups. RESULTS: Before surgery, C4/C5 had more sagittal ROM compared with C3/C4, C5/C6, and C6/C7 (P < 0.001.) Before surgery, C4/C5 also had more lateral ROM compared with C3/C4, C5/C6, and C6/C7 (P = 0.015). After surgery, there were no significant differences in sagittal and lateral ROM between C3/C4, C4/C5, C5/C6, and C6/C7. The delta (difference between pre- and postoperative) proved that the C4/C5 CDR actually lost sagittal ROM (-2.5 degrees ) compared with the other levels, which gained sagittal ROM, C3/C4 (0.9 degrees ), C5/C6 (1.8 degrees ), and C6/C7 (1.6 degrees ); P = 0.037. There was no significant difference in the delta lateral ROM between the segments: C3/C4, C4/C5, C5/C6, and C6/C7. CONCLUSION: CDR approximates the different segmental sagittal and lateral ROM. Although C4/C5 had negative delta ROM in the sagittal and lateral planes, it provided a satisfactory final ROM. Long-term clinical outcome studies are needed to properly evaluate if these differences could ultimately affect the patients everyday life

STUDY DESIGN: Retrospective case-control review. OBJECTIVE: This retrospective study explored the hypothesis that the perioperative administration of blood products is an identifiable risk factor of increased surgical site infections (SSIs) after thoracic and lumbar spine surgical procedures. SUMMARY OF BACKGROUND DATA: Surgical site infections are a significant cause of postoperative morbidity and mortality. According to the Center for Disease Control's National Nosocomial Infections Surveillance system, which monitors the rate of hospital-acquired infections in the United States, SSIs represent the third most commonly reported type of nosocomial infection, accounting for 14% to 16% of all nosocomial infections. The incidence of SSIs after spinal surgery is influenced by both preoperative and intraoperative risk factors. The relationship between blood products and SSIs has been a matter of debate for more than 2 decades. Several studies have supported the association between the use of blood products and the development of postoperative surgical site infections. METHODS: A retrospective case-control study was performed. We reviewed the charts of all patients who had undergone thoracic and/or lumbar spinal surgery at the NYU Hospital for Joint Diseases between 2002 and 2007. All patients who had developed surgical site infections following spine surgery in this 5-year period were identified. RESULTS: Data for 61 cases and 71 controls were included in this study. The analysis of the preoperative risk factors was performed for the entire population of patients. Body mass index and blood transfusions were found to be statistically significant risk factors for increased surgical site infections for this population. CONCLUSION: Our findings support current theories that blood transfusions may have modulatory effects on the immune system of the recipients. Our specific study in spine patients may contribute to the expanding literature on allogeneic blood transfusions and the risk of nosocomial infections and encourage surgeons to favor a more restrictive policy with regard to transfusions

BACKGROUND CONTEXT: Cervical total disc replacement (TDR) is an emerging technology. However, the factors that influence postoperative range of motion (ROM) and patient satisfaction are not fully understood. PURPOSE: To evaluate the influence of pre- and postoperative disc height on postoperative motion and clinical outcomes. STUDY DESIGN/SETTING: Retrospective review of patients enrolled in prospective randomized Food and Drug Administration (FDA) trial. PATIENT SAMPLE: One hundred sixty-six patients with single-level ProDisc-C arthroplasty performed were evaluated. OUTCOME MEASURES: ROM and clinical outcomes based on Neck Disability Index (NDI) and Visual Analog Scale (VAS) were assessed. METHODS: Preoperative and postoperative disc height and ROM were measured from lateral and flexion-extension radiographs. Student t test and Spearman's rho tests were performed to determine any correlation or 'threshold' effect between the disc height and ROM or clinical outcome. RESULTS: Patients with less than 4mm of preoperative disc height had a mean 1.8 degrees increase in flexion-extension ROM after TDR, whereas patients with greater than 4mm of preoperative disc height had no change (mean, 0 degrees ) in flexion-extension ROM (p=.04). Patients with greater than 5mm of postoperative disc height have significantly higher postoperative flexion-extension ROM (mean, 10.1 degrees ) than those with less than 5mm disc height (mean, 8.3 degrees , p=.014). However, patients with greater than 7mm of postoperative disc height have significantly lower postoperative lateral bending ROM (mean, 4.1 degrees ) than those with less than 7mm disc height (mean, 5.7 degrees , p=.04). It appears that the optimal postoperative disc height is between 5 and 7mm for increased ROM on flexion extension and lateral bending. There was a mean improvement of 30.5 points for NDI, 4.3 points for VAS neck pain score, and 3.9 points for VAS arm pain score (all p<.001). No correlation could be found between clinical outcomes and disc height. Similarly, no threshold effect could be found between any specific disc height and NDI or VAS. CONCLUSION: Patients with greater disc collapse of less than 4mm preoperative disc height benefit more in ROM after TDR. The optimal postoperative disc height range to maximize ROM is between 5 and 7mm. This optimal range did not translate into better clinical outcome at 2-year follow-up

BACKGROUND CONTEXT: Vertebral artery (VA) injury can be a catastrophic iatrogenic complication of cervical spine surgery. Although the incidence is rare, it has serious consequences including fistulas, pseudoaneurysm, cerebral ischemia, and death. It is therefore imperative to be familiar with the anatomy and the instrumentation techniques when performing anterior or posterior cervical spine surgeries. PURPOSE: To provide a review of VA injury during common anterior and posterior cervical spine procedures with an evaluation of the surgical anatomy, management, and prevention of this injury. STUDY DESIGN: Comprehensive literature review. METHODS: A systematic review of Medline for articles related to VA injury in cervical spine surgery was conducted up to and including journal articles published in 2007. The literature was then reviewed and summarized. RESULTS: Overall, the risk of VA injury during cervical spine surgery is low. In anterior cervical procedures, lateral dissection puts the VA at the most risk, so sound anatomical knowledge and constant reference to the midline are mandatory during dissection. With the development and rise in popularity of posterior cervical stabilization and instrumentation, recognition of the dangers of posterior drilling and insertion of transarticular screws and pedicle screws is important. Anomalous vertebral anatomy increases the risk of injury and preoperative magnetic resonance imaging and/or computed tomography (CT) scans should be carefully reviewed. When the VA is injured, steps should be taken to control local bleeding. Permanent occlusion or ligation should only be attempted if it is known that the contralateral VA is capable of providing adequate collateral circulation. With the advent of endovascular repair, this treatment option can be considered when a VA injury is encountered. CONCLUSIONS: VA injury during cervical spine surgery is a rare but serious complication. It can be prevented by careful review of preoperative imaging studies, having a sound anatomical knowledge and paying attention to surgical landmarks intraoperatively. When a VA injury occurs, prompt recognition and management are important

Introduction: The gold standard for the treatment of isthmic spondylolisthesis is posterior-lateral fusion. Few studies have evaluated the clinical outcomes of circumference fusion in the treatment if isthmic spondylolisthesis. The purpose of this study was to evaluate the surgical and clinical outcomes of anterior-posterior surgical treatment for low-grade isthmic spondylolisthesis. Methods: Retrospectively, 23 consecutive patients were enrolled that underwent surgical treatment for Isthmic Spondylolisthesis Grade 1 or 2. Basic demographic data was collected. Radiographic data that was collected included Meyerding Scale, disc height, and slip angle. Pre and post surgical clinical surveys which included VAS, ODI, and SF-36 surveys were collected. Results: There were 23 patients. All patients underwent anterior interbody fusion with a femoral ring allograft or iliac crest bone graft in addition to posterior lumbar decompression and fusion with instrumentation. The average slip percentage decreased from 23.2% to 19.0% (P = 0.24), slip angle increased from 9.8 to 17.9 (P < 0.001), and disc height decreased from 1.9 cm to 0.80 cm (P < .001). VAS scores decreased from 7.1 to 2.4 (P < 0.001). ODI scores decreased from 52.5 to 28.1 (P < 0.001). SF-36 scores demonstrated a significant increase in the Physical Component Scale (PCS) from 29.5 to 42.6 (P < 0.001). Conclusion: This study demonstrates that patients with isthmic spondylolisthesis that undergo circumferential fusion have a good clinical outcome. Patients demonstrated an improvement in the ODI and the physical component scores of the SF-36. These results demonstrate that patients improved in their physical functioning due to the surgery alone

BACKGROUND CONTEXT: The golf swing imparts significant stress on the lumbar spine. Not surprisingly, low back pain (LBP) is one of the most common musculoskeletal complaints among golfers. PURPOSE: This article provides a review of lumbar spine forces during the golf swing and other research available on swing biomechanics and muscle activity during trunk rotation. STUDY DESIGN: The role of 'modern' and 'classic' swing styles in golf-associated LBP, as well as LBP causation theories, treatment, and prevention strategies, are reviewed. METHODS: A PubMed literature search was performed using various permutations of the following keywords: lumbar, spine, low, back, therapy, pain, prevention, injuries, golf, swing, trunk, rotation, and biomechanics. Articles were screened and selected for relevance to injuries in golf, swing mechanics, and biomechanics of the trunk and lumbar spine. Articles addressing treatment of LBP with discussions on trunk rotation or golf were also selected. Primary references were included from the initial selection of articles where appropriate. General web searches were performed to identify articles for background information on the sport of golf and postsurgical return to play. RESULTS: Prospective, randomized studies have shown that focus on the transversus abdominus (TA) and multifidi (MF) muscles is a necessary part of physical therapy for LBP. Some studies also suggest that the coaching of a 'classic' golf swing and increasing trunk flexibility may provide additional benefit. CONCLUSIONS: There is a notable lack of studies separating the effects of swing modification from physical rehabilitation, and controlled trials are necessary to identify the true effectiveness of specific swing modifications for reducing LBP in golf. Although the establishment of a commonly used regimen to address all golf-associated LBP would be ideal, it may be more practical to apply basic principles mentioned in this article to the tailoring of a unique regimen for the patient. Guidelines for returning to golf after spine surgery are also discussed

STUDY DESIGN: Retrospective study of patients enrolled in prospective randomized Food and Drug Administration trial. OBJECTIVE: To evaluate the influence of pre- and postoperative disc height on postoperative motion and clinical outcomes. SUMMARY OF BACKGROUND DATA: Our understanding of the factors that influence motion and ultimately patient satisfaction after lumbar disc replacement continues to evolve. METHODS: Forty-two patients with a single level ProDisc-L at either the L4/5 or L5-S1 were selected. Pre- and postoperative disc height and range of motion (ROM) were measured from standing lateral and flexion-extension radiographs. Oswestry Disability Index and visual analog scale were also collected. Student t test and Spearman rho tests were performed to determine if there was any correlation or 'threshold' effect between the disc height and ROM or clinical outcome. RESULTS: The mean anterior and posterior disc height significantly increased from 10.8 mm to 17.6 mm and 4.4 mm to 7.9 mm, respectively (P < 0.01). The mean ROM decreased from 7.0 degrees to 5.7 degrees (P = 0.21). Patients with less than 9 mm of preoperative anterior disc height had an increase in their ROM (2.2 degrees) compared with a loss of ROM (-2.2 degrees) in patients with more than 9 mm of preoperative disc height (P = 0.02). Patients with between 16 mm and 18 mm of postoperative anterior disc height have greater ROM (7.5 degrees) than those above or below this range (3.6 degrees and 3.6 degrees respectively, P < 0.05). There was no correlation or threshold effect between clinical outcomes and disc height. CONCLUSION: Patients with greater disc collapse benefit more in ROM from a total disc replacement. The optimal range to maximize ROM for postoperative anterior disc height is 16 mm to 18 mm. This optimal range did not translate into better clinical outcome at 2 years follow-up

STUDY DESIGN: Retrospective outcome data analysis. OBJECTIVE: To evaluate if there is a significant difference between the midline rectus (MR) and the paramedian lateral rectus (PLR) approaches with regard to implant position for lumbar disc arthroplasty. To establish that a less than optimal implant position may influence clinical outcome. SUMMARY OF BACKGROUND DATA: Little is known about the impact of varying surgical approaches on lumbar artificial disc implant position and clinical outcome. METHODS: Fifty-seven patients were obtained from one center participating Food and Drug Administration study for the evaluation of the lumbar Prodisc-L. Two different surgical access techniques were compared; the MR and left PLR. Two independent evaluators calculated the postoperative radiographical displacement from the midline in the coronal and sagittal planes for each of the surgical techniques. Pre- and postoperative clinical outcomes were evaluated to determine which surgical access technique was associated with better outcomes and if there was a clinical correlation with technical accuracy. RESULTS: The PLR approach was associated with greater malalignment of the prosthesis in both the coronal and sagittal planes compared with the MR approach. However, the difference was significant only in the sagittal plane (P = 0.021). There was no significant difference in clinical outcome for either approach (P = 0.34). Patients with >or=5 mm prosthetic displacement from the midvertebral point had significantly worse Owestry disability index scores than patients with <3 mm malalignment in both the coronal and sagittal planes regardless of the surgical approach employed. CONCLUSION: The finding of a statistically significant more anteriorly displaced position in the sagittal plane of the total disc arthroplasty using the PLR approach may indicate a need to change to the MR approach. This study also demonstrates that patients with >or=5 mm prosthetic deviation from midline in either the coronal or sagittal planes had diminished clinical outcomes regardless of the approach used