The association between lumbar paraspinal muscle functional cross-sectional area on MRI and regional volumetric bone mineral density measured by quantitative computed tomography

Osteosarcopenia is a common condition among elderly and postmenopausal female patients. Site-specific bone mineral density is more predictive of bone-related complications. Few studies have investigated muscle-bone associations. Our results demonstrated that in women, significant positive associations between paraspinal muscles FCSA and vBMD exist at different lumbosacral levels. These regional differences should be considered when interpreting bone-muscle associations in the lumbar spine.

INTRODUCTION

There is increasing evidence between bone and muscle volume associations. Previous studies have demonstrated comorbidity between osteoporosis and sarcopenia. Recent studies showed that sarcopenic subjects had a fourfold higher risk of concomitant osteoporosis compared to non-sarcopenic individuals. Although site-specific bone mineral density (BMD) assessments were reported to be more predictive of bone-related complications after spinal fusions than BMD assessments in general, there are few studies that have investigated level-specific bone-muscle interactions. The aim of this study is to investigate the associations between muscle functional cross-sectional area (FCSA) on magnetic resonance imaging (MRI) and site-specific quantitative computed tomography (QCT) volumetric bone mineral density (vBMD) in the lumbosacral region among spine surgery patients.

METHODS

We retrospectively reviewed a prospective institutional database of posterior lumbar fusion patients. Patients with available MRI undergoing posterior lumbar fusion were included. Muscle measurements and FCSA were conducted and calculated utilizing a manual segmentation and custom-written program at the superior endplate of the L3-L5 vertebrae level. vBMD measurements were performed and calculated utilizing a QCT pro software at L1-L2 levels and bilateral sacral ala. We stratified by sex for all analyses.

RESULTS

A total of 105 patients (mean age 61.5 years and 52.4% females) were included. We found that female patients had statistically significant lower muscle FCSA than male patients. After adjusting for age and body mass index (BMI), there were statistically significant positive associations between L1-L2 and S1 vBMD with L3 psoas FCSA as well as sacral ala vBMD with L3 posterior paraspinal and L5 psoas FCSA. These associations were not found in males.

CONCLUSIONS

Our results demonstrated that in women, significant positive associations between the psoas and posterior paraspinal muscle FCSA and vBMD exist in different lumbosacral levels, which are independent of age and BMI. These regional differences should be considered when interpreting bone and muscle associations in the lumbar spine.

Postoperative decrease of regional volumetric bone mineral density measured by quantitative computed tomography after lumbar fusion surgery in adjacent vertebrae

We investigated the effect of posterior lumbar fusion surgery on the regional volumetric bone mineral density (vBMD) measured by quantitative computed tomography. Surgery negatively affected the regional vBMD in adjacent levels. Interbody fusion was independently associated with vBMD decline and preoperative epidural steroid injections (ESIs) were associated with less postoperative vBMD decline.

INTRODUCTION

Few studies investigate postoperative BMD changes after lumbar fusion surgery utilizing quantitative computed tomography (QCT). Additionally, it remains unclear what preoperative and operative factors contribute to postoperative BMD changes. The purpose of this study is to investigate the effect of lumbar fusion surgery on regional volumetric bone mineral density (vBMD) in adjacent vertebrae and to identify potential modifiers for postoperative BMD change.

METHODS

The data of patients undergoing posterior lumbar fusion with available pre- and postoperative CTs were reviewed. The postoperative changes in vBMD in the vertebrae one or two levels above the upper instrumented vertebra (UIV+1, UIV+2) and one level below the lower instrumented vertebra (LIV+1) were analyzed. As potential contributing factors, history of ESI, and the presence of interbody fusion, as well as various demographic/surgical factors, were included.

RESULTS

A total of 90 patients were included in the study analysis. Mean age (±SD) was 62.1 ± 11.7. Volumetric BMD (±SD) in UIV+1 was 115.4 ± 36.9 mg/cm³ preoperatively. The percent vBMD change in UIV+1 was - 10.5 ± 12.9% (p < 0.001). UIV+2 and LIV+1 vBMD changes showed similar trends. After adjusting with the interval between surgery and the secondary CT, non-Caucasian race, ESI, and interbody fusion were independent contributors to postoperative BMD change in UIV+1.

CONCLUSIONS

Posterior lumbar fusion surgery negatively affected the regional vBMDs in adjacent levels. Interbody fusion was independently associated with vBMD decline. Preoperative ESIs were associated with less postoperative vBMD decline, which was most likely a result of a preoperative decrease in vBMD due to ESIs.

Clinical predictors of surgical outcome in cervical spondylotic myelopathy: an analysis of 248 patients

The purpose of this study was to investigate the clinical predictors of surgical outcome in patients with cervical spondylotic myelopathy (CSM). We reviewed a consecutive series of 248 patients (71 women and 177 men) with CSM who had undergone surgery at our institution between January 2000 and October 2010. Their mean age was 59.0 years (16 to 86). Medical records, office notes, and operative reports were reviewed for data collection. Special attention was focused on pre-operative duration and severity as well as post-operative persistence of myelopathic symptoms. Disease severity was graded according to the Nurick classification. Our multivariate logistic regression model indicated that Nurick grade 2 CSM patients have the highest chance of complete symptom resolution (p < 0.001) and improvement to normal gait (p = 0.004) following surgery. Patients who did not improve after surgery had longer duration of myelopathic symptoms than those who did improve post-operatively (17.85 months (1 to 101) vs 11.21 months (1 to 69); p = 0.002). More advanced Nurick grades were not associated with a longer duration of symptoms (p = 0.906). Our data suggest that patients with Nurick grade 2 CSM are most likely to improve from surgery. The duration of myelopathic symptoms does not have an association with disease severity but is an independent prognostic indicator of surgical outcome.

Predictors of functional outcome in elderly patients undergoing posterior lumbar spine surgery

To ascertain the predictors of functional outcome in elderly patients undergoing posterior lumbar spinal decompression and fusion, a modified low back outcome score questionnaire survey in 83 elderly patients (49 men, 34 women) was carried out at our hospital. The average follow-up was 35.8 months (range: 22-57 months). The outcomes were as follows: excellent to good, 83%; fair, 7%; and poor, 10%. Multiple regression analysis revealed that significant predictors of unfavorable outcome included coexistence of other bone and joint degenerative disorders (p < 0.001) and history of heart disease (p < 0.01). Patients who had undergone previous lumbar surgery had significantly lower modified low back outcome score than those without previous lumbar spine surgery (p < 0.05). The modified low back outcome score questionnaire system is a reliable method in elderly patients.

Decompression, fusion, and instrumentation surgery for complex lumbar spinal stenosis

Between 1990 and 1993, 54 consecutive patients were treated with decompression, fusion and instrumentation surgery for complex lumbar spinal stenosis. The mean age of the patients was 60 years. The average followup was 39 months. Clinically, there was one deep wound infection, and three mechanical failures. There were two staged operations. There were three revision surgeries performed for mechanical reasons. Of the 47 patients who completed the questionnaire, 96% of patients were very satisfied or somewhat satisfied with the operation, 98% were satisfied with relief of pain, 94% were satisfied with their ability to walk, 89% were satisfied with their strength, and 94% were satisfied with balance. Survivorship analysis (failure endpoint was revision surgery) revealed that at the end of 4 years, the patient had a 92% chance of not undergoing revision surgery for any reason (mechanical and infectious), and a 94% chance of not undergoing revision surgery for mechanical reasons. Lumbar decompression, fusion, and instrumentation surgery seems to be efficacious in patients with complex lumbar spinal stenosis (associated previous lumbar spine operations with evidence of radiographic instability, radiographic evidence of junctional stenosis after surgery, radiographic evidence of instability, degenerative spondylolisthesis greater than Grade I with instability, if present, and degenerative scoliosis with a curve greater than 20 degrees).

Decompressive surgery for typical lumbar spinal stenosis

Between 1991 and 1992, 103 consecutive patients (average age, 65 years) underwent decompressive surgery for treatment of typical lumbar spinal stenosis. Clinical results at 1-year followup revealed that four patients had revision surgery. At 2- to 5-years followup, there were no additional revision surgeries. Two patients underwent revision surgery for a deep infection, and two underwent revision surgery for a superficial infection. Outcome results showed that 77 patients completed the questionnaire, 15 were lost to followup and 11 died. Postoperative results showed that 64 of 77 patients had no or mild pain, 72 of 77 patients stated that they were satisfied or somewhat satisfied with their overall results of surgery, and 73 of 77 were satisfied with pain relief. Younger patients had greater improvement in function and a greater reduction in severity scores. However, satisfaction was similar in both groups. Survivorship results (failure was revision surgery) showed at the end of 4 years, a patient had a 95% chance of not having revision surgery. Statistically, there was no association between outcome and cofactors such as scoliosis, spondylolisthesis, number of levels decompressed, discectomy, or smoking. Satisfaction rates for older patients were similar to patients younger than 65 years although physical function scores and severity scores were less.

Correlation between vertebral body rotation and two-dimensional vertebral bone density measurement

The aim of this study was to determine the effect of vertebral rotation, as seen in idiopathic scoliosis, on bone mineral density determination for the lumbar spine. Bone mineral content, biplanar vertebral segment area and calculated bone mineral density of each vertebra from L1 to L4 were obtained for a human cadaveric specimen. The average density for the entire L1-L4 segment was also recorded. This was done with the spine in the midline position as well as in rotation up to a maximum of 60 degrees either side of the midline. The spine was rotated in each direction using 10 degrees increments and two bone density readings were done at each rotation interval. The measured biplanar vertebral segment area increased with increasing rotation from 0 degrees to 50 degrees but decreased after 50 degrees of rotation (r = 0.73, p<0.001). The bone mineral density was significantly negatively correlated with the degree of rotation (r = -0.92, p<0.001). The decrease in measured bone mineral density was nearly 20% when the lumbar spine was rotated from neutral to 60 . This study demonstrates that degree of spinal rotation influences apparent bone mineral density by increasing the apparent vertebral segment area. The measurement change may be as high as 20%. This fact should be considered when investigating scoliotic patients with vertebral segment rotation.

Incidental durotomy in spine surgery

STUDY DESIGN

Retrospective review of a large series of patients who underwent spinal surgery at a single institution during a 10-year period.

OBJECTIVES

To further clarify the frequency of incidental durotomy during spine surgery, its treatment, associated complications, and results of long-term clinical follow-up.

SUMMARY OF BACKGROUND DATA

Incidental durotomy is a relatively common occurrence during spinal surgery. There remains significant concern about it despite reports of good associated clinical outcomes. There have been few large clinical series on the subject.

METHODS

A retrospective review was conducted of clinical and surgical records and radiographic data for consecutive patients who underwent spinal surgery performed by the two senior surgeons from January 1989 through December 1998.

RESULTS

A total of 2144 patients were reviewed, and 74 were found to have dural tears occurring during or before surgery. Incidental durotomy occurred at the time of surgery in 66 patients (3.1% overall incidence). Incidence varied according to the specific procedure performed but was highest in the group that underwent revision surgery. The incidence of clinically significant durotomies occurring during surgery but not identified at the time was 0.28%. All dural tears that occurred during surgery and were recognized (60 of 66) were repaired primarily. Pseudomeningoceles developed in five of the remaining six patients. All six patients had subsequent surgical repair of dural defects because of failure of conservative therapy. A mean follow-up of 22.4 months was available and showed good long-term clinical results for all patients.

CONCLUSIONS

Incidental durotomy, if recognized and treated appropriately, does not lead to long-term sequelae.

Association between findings of provocative discography and vertebral endplate signal changes as seen on MRI

Provocative discography is a controversial diagnostic tool for pathologic discs. Modic has identified vertebral endplate signal changes on magnetic resonance imaging (MRI) that are thought to signify advanced discogenic degeneration. These two distinct diagnostic tools are examined to determine if there is association between them. Fifty-three consecutive patients who underwent both investigations were retrospectively reviewed. In discs that had negative T1 MRI findings, 28.2% of patients had concordant pain and 17.3% had discordant pain. In discs with positive T1 MRI findings, 34.8% of patients had concordant pain and 17.4% had discordant pain. 79.5% and 74.4% of levels with patient concordant pain on discography had no endplate changes on T1- and T2 weighted MR images, respectively (compared with 84.5% and 81.7%, respectively, for levels with no patient pain on discography). Our data showed no significant relationship between these distinct diagnostic tools. Further investigation of their relative roles in this application is recommended.

Postoperative spinal wound infection: a review of 2,391 consecutive index procedures

Postoperative infection remains a troublesome but not uncommon complication after spinal surgery. Most previous reports, however, are small or involve cases with more than one surgeon often at different institutions. This study represents a single surgeon's 9-year experience with postoperative infection at one institution. The authors describe the features of wound infection after spinal surgery with reference to diagnosis, microbiology, and treatment and they describe a protocol for effective management of postoperative spinal wound infection. The records of the senior author (F.P.C.) during a 9-year period for cases of postoperative wound infection were reviewed. Of 2,391 operative procedures, 46 cases of wound infection were identified, yielding an overall infection rate of 1.9%. Patients' preoperative risk factors, original diagnosis prompting the surgery, onset of infection, presentation, treatment, and outcome were analyzed. The mean age of the 23 men and 23 women was 57.2 years. The preoperative diagnoses included lumbar degenerative scoliosis or spinal stenosis in 28 cases, disk prolapse in 8 cases, metastatic disease in 4 cases, degenerative disk disease in 1 case, and a group of 5 miscellaneous cases. Seventeen (37%) of the patients underwent at least one previous spinal surgery at the same site. Twenty-three patients had a fusion, of whom 22 also had instrumentation. Forty-three (93%) of the patients had significant wound drainage after an average of 15 days (range, 5-80 days). The other three patients were examined approximately 2 years after the surgery. Fourteen of the patients also had pyrexia (temperature >37.5 degrees C) at presentation. Staphylococcus aureus alone was cultured in 29 patients, whereas another six patients had a different single organism. In nine patients, more than one organism was cultured during their hospital stay. Surgical treatment included primary closure in only seven patients, with most undergoing wound drainage and debridement followed by delayed closure. Instruments were removed in the three patients with late presentation who had solid fusion at operation. Viable bone graft and instrumentation were left in situ in all patients who were seen before fusion. All wounds healed without sequelae, except for three that required flap closure. Pseudarthrosis was noted in three patients after more than 1 year of follow-up in this series. Postoperative spinal wound infection is a potentially devastating problem. In this series, infection was more common in patients undergoing fusion with instrumentation and in patients with cancer metastatic to the spine. An aggressive surgical approach, including repeated debridement followed by delayed closure, is justified. Instrumentation may be safely left in situ to provide stability for fusion.

Advances and strategies for spinal cord regeneration

Although a cure for spinal cord injuries does not currently exist, advances have been made in the field of spinal cord regeneration. This article discusses the pathophysiology of spinal cord injury, animal models, and strategies for restoration and regeneration of the spinal cord.

Gene therapy for spine fusion

Gene therapy is a novel therapeutic modality for repair and regeneration of musculoskeletal tissues, including the spine. Various methods for therapeutic gene transfer are presented in this article. Several studies in which gene transfer has been used specifically to enhance spine fusion in animal models are reviewed.

Current concepts in intervertebral disc restoration

A current focus of treatment for degenerative disk disease is the restoration of the intervertebral disk. This article summarizes the structure and function of the intervertebral disk, the pathogenesis of its degeneration, and the clinical relevance of degenerative disk disease. Current literature relating to intervertebral disk replacement and regeneration is reviewed.

The placement of lumbar pedicle screws using computerised stereotactic guidance

Computer-assisted frameless stereotactic image guidance allows precise preoperative planning and intraoperative localisation of the image. It has been developed and tested in the laboratory.

We evaluated the efficacy, clinical results and complications of placement of a pedicle screw in the lumbar spine using this technique. A total of 62 patients (28 men, 34 women) had lumbar decompression and spinal fusion with segmental pedicle screws. Postoperative CT scans were taken of 35 patients to investigate the placement of 330 screws. None showed penetration of the medial or inferior wall of a pedicle. Registration was carried out 66 times. The number of fiducial points used on each registration averaged 5.8 (4 to 7) The mean registration error was 0.75 mm (0.32 to 1.72).

This technique provides a safe and reliable guide for placement of transpedicular screws in the lumbar spine.

The placement of lumbar pedicle screws using computerised stereotactic guidance

Computer-assisted frameless stereotactic image guidance allows precise preoperative planning and intraoperative localisation of the image. It has been developed and tested in the laboratory. We evaluated the efficacy, clinical results and complications of placement of a pedicle screw in the lumbar spine using this technique. A total of 62 patients (28 men, 34 women) had lumbar decompression and spinal fusion with segmental pedicle screws. Postoperative CT scans were taken of 35 patients to investigate the placement of 330 screws. None showed penetration of the medial or inferior wall of a pedicle. Registration was carried out 66 times. The number of fiducial points used on each registration averaged 5.8 (4 to 7) The mean registration error was 0.75 mm (0.32 to 1.72). This technique provides a safe and reliable guide for placement of transpedicular screws in the lumbar spine.

Rheumatoid arthritis of the cervical spine

There is a high incidence of cervical involvement in patients with rheumatoid disease. Early evaluation of the neck, close follow-up with dynamic radiographs of the cervical spine, and careful neurological assessment are important in the care of these patients. Surgical stabilization should be considered early even in the absence of neurological findings when significant instability is noted since outcome is related to preoperative neurological function. The type of fusion performed is determined by a careful assessment of the location of instability, patient factors, and the experience of the surgeon with various techniques. The type of postoperative immobilization should be decided on an individual basis depending on the quality of fixation achieved at surgery. Patients must be observed closely in the postoperative period for development of early complications and followed-up for the appearance of pseudarthrosis or late instabilities.

Recurrent disk versus scar in the postoperative patient: the role of computed tomography (CT)/diskography and CT/myelography

The purpose of this study was to compare computed tomography (CT)/myelography and CT/diskography images, in a given patient, as a method of distinguishing postoperative fibrosis from recurrent herniated disk material. The study population consisted of 20 patients who had undergone lumbar diskectomy and subsequently developed recurrent radicular pain. All patients underwent CT/myelography and CT/diskography, each procedure performed within 72 h of the other. Comparison of transaxial images from CT/myelography and CT/diskography at a given disk space level yielded the following results: in 12 patients the extradural mass seen via CT/myelography corresponded entirely to the contrast-filled disk fragment seen via CT/diskography (recurrent herniated disk); in three patients the extradural mass seen via CT/myelography was larger than the disk fragment seen via CT/diskography (recurrent herniated disk and fibrosis); and in five patients CT/diskography images appeared normal, but CT/myelography showed an extradural mass (fibrosis). Fifteen patients underwent surgical reexploration with the following results: in three of three patients, the suspicion of recurrent herniated disk and fibrosis by radiologic evaluation was confirmed by surgical reexploration; in nine of 12 patients, solely recurrent herniated disk shown by radiologic criteria was similarly confirmed. The remaining five patients presumed to have fibrosis by radiologic criteria were treated nonoperatively.

Toward the elimination of homologous blood use in elective lumbar spine surgery

Two hundred twenty-four consecutive patients underwent elective posterior lumbar spinal surgery over a 3 1/2-year span at the University of Miami/Jackson Memorial Medical Center. Patients ranged in age from 17 to 87 years, and 58% were male. Fifty-eight patients underwent revision surgery, and 65 patients required fusions, including 35 necessitating internal fixation. One hundred seventy-four patients (78%) were requested to participate in a preoperatively donated autologous blood (PDAB) program. Six of these patients were excluded from participation, and 168 patients banked 425 U of autologous blood. Eighty percent of the patients participating in the PDAB program received some or all of their donated blood. Intraoperative blood salvage was used in 37% of cases. Seven patients received homologous blood: four in addition to salvaged and donated blood, two that were unable to donate blood due to positive hepatitis B serology, and one erroneously. The combined use of PDAB and intraoperative salvage program allowed autologous blood replacement to meet the total transfusion requirements of 96% of the patients who predeposited blood, including 94% of those undergoing spinal fusions. Autologous blood comprised 99% of the total blood replacement used in this series, and 95% of the patients requiring blood transfusions received only autologous blood. Establishment of a protocol judiciously using PDAB in conjunction with intraoperative blood salvage can result in virtual elimination of the need for homologous blood transfusion in elective lumbar spine surgery.

Brachial plexus injury caused by impalement

Open injuries of the brachial plexus are rare. One such case, that of a 68-year-old impaled on a fence spike, is presented here. Certain principles to guide evaluation and treatment are discussed. Concomitant injury to the pleura or to vascular structures requires immediate attention; the extent and type of plexus damage may be determined from physical findings and the nature of injury. The results of plexus reconstruction are variable and routine exploration may be detrimental. The Brooks classification is reviewed.

Spinal fusions to the pelvis augmented by Cotrel-Dubousset instrumentation for neuromuscular scoliosis

Eighteen patients with spinal deformity secondary to a neuromuscular disorder were treated with posterior fusion using Cotrel-Dubousset instrumentation (CDI) to the pelvis. The mean frontal plane curve was 70 degrees preoperatively and 38 degrees postoperatively. The mean loss of correction was 3 degrees at an average follow-up of 28 months. Pelvic obliquity improved in nine patients from a preoperative mean of 22 degrees to 11 degrees at follow-up. Lumbar lordosis was maintained with preoperative and postoperative means of -36 degrees. Complications included perioperative hardware failure in one case and one late, deep infection. There were no neurologic complications, pseudarthroses, or rod breakage. Posterior spinal fusion with CDI to the pelvis is an effective treatment for patients with neuromuscular scoliosis.

The Van Nes tibial rotationplasty. A functionally viable reconstructive procedure in children who have a tumor of the distal end of the femur

Twelve patients who had a malignant tumor of the distal end of the femur were treated with a Van Nes tibial rotationplasty. The survival rates were comparable with those for above-the-knee amputees and patients who had an endoprosthetic replacement. The results of functional testing showed that these patients performed as well as those who had endoprosthetic replacement and better than those who had above-the-knee amputation. Rotationplasty is therefore a favorable alternative to amputation or endoprosthetic replacement, either as a primary or as a salvage procedure.

Dural laceration occurring with burst fractures and associated laminar fractures

The cases of sixty patients in whom a burst fracture of a thoracic or lumbar vertebral body had been treated with posterior instrumentation and arthrodesis less than two weeks after the injury were retrospectively reviewed. Thirty of the patients had an associated laminar fracture. Eleven of the thirty, all of whom had a lumbar fracture and a preoperative neurological deficit, were noted at operation to have dural laceration. In four of the patients who had dural laceration, neural elements were entrapped between the fragments from the laminar fracture. None of the remaining thirty patients who did not have a laminar fracture had dural laceration (p = 0.0002). Univariate and multivariate statistical analysis revealed no significant association of the dural laceration with the patients' age or sex, or with the radiographic characteristics of the spine. There was a significant association between dural laceration and neurological deficit (p = 0.0001). In our series, the presence of a preoperative neurological deficit in a patient who had a burst fracture and an associated laminar fracture was a sensitive (100 per cent) and specific (74 per cent) predictor of dural laceration. The presence of this fracture pattern and an associated neurological deficit also predicted a risk of dural laceration with entrapped neural elements. This information may influence decisions as to whether an anterior or a posterior surgical approach should be used in such patients.

One-stage bilateral total hip arthroplasty. A prospective study of perioperative morbidity

Controversy exists over the safety of performing one-stage bilateral total hip arthroplasty. A prospective protocol was established in 35 patients to evaluate the perioperative morbidity of one-stage bilateral arthroplasty as compared with unilateral controls. Although there was no increase in the frequency of respiratory morbidity in bilateral procedures, respiratory depression is common with both procedures. The authors believe this is consistent with varying degrees of the adult respiratory distress syndrome and that the term fat embolism syndrome is misleading and should be abandoned.