The effect of surgically implanted metallic bullet fragments on the intervertebral disc using a canine model☆.

PURPOSE: To characterize the gross, histologic, and systemic changes caused by implantation of metal fragments commonly used in commercial bullets into the intervertebral disc. BACKGROUND CONTEXT: Long-term complications of retained bullet fragments in the spine have been documented in the literature; however, the impact of different metal projectiles on the intervertebral disc has not been described. This study was performed to assess the local effects of the metallic bullet fragments on the intervertebral disc and their systemic effects regarding metal ion concentrations in serum and solid organs. STUDY DESIGN: Animal Model Study. METHODS: Funding for this project was provided by the Cervical Spine Research Society in the amount of $10,000. Copper, lead, and aluminum alloys from commercially available bullets were surgically implanted into sequential intervertebral discs in the lumbar spine of six canines. Kirschner wire implantation and a sham operation were performed as controls. Radiographs were performed to confirm the location of the bullets. Animals were sacrificed at 4, 6, and 9 months postimplantation. Whole blood, plasma, cerebrospinal fluid, kidney tissue, and liver tissue samples were analyzed for copper and lead concentrations. Histologic and gross samples were examined at the time of sacrifice. RESULTS: Significant tissue reactions were noted in the discs exposed to copper and lead. Copper resulted in significantly more severe disc degeneration than either the lead or aluminum alloy. In the short interval follow-up of this study, no statistically significant trend was observed in whole blood, plasma, cerebrospinal fluid, and tissue levels. CONCLUSION: This study demonstrates that the canine intervertebral disc is differentially susceptible to metallic fragments depending on the composition. Trends were noted for increasing levels of lead and copper in liver tissue samples although statistical significance could not be reached due to short time interval and small sample size. The metallic composition of retained fragments can be a determining factor in deciding on surgical intervention.

Hypothermia in patients with chronic spinal cord injury.

DESIGN: Retrospective analysis of medical records. BACKGROUND/OBJECTIVES: To determine frequency and degree of hypothermic episodes in patients with chronic spinal cord injury (SCI). SETTING: Veterans Administration Medical Center. METHODS: Research involved analysis of body temperature records of 50 chronic patients with tetraplegia. All patients were men with a length of injury of 19 +/- 6 years. Mean age was 53 +/- 15 (SD) years. Data were derived from the computerized patient record database system of the Veterans Administration Medical Center. Results were classified into 3 groups: (a) hypothermia (< 95 degrees F), (b) subnormal temperature (< 97.7 degrees F), and normal temperatures (97.7 degrees F to 98.4 degrees F). Body temperature was recorded during hospitalization (minimum duration of 30 days) using an oral probe twice a day. Ambient temperature was controlled by a central air-conditioning system and maintained at 72 degrees F to 74 degrees F. RESULTS: A total of 867 measurements of body temperature were evaluated; normal temperature was recorded 298 times (35%), subnormal temperature was recorded 544 times (63%), and hypothermia was recorded 25 times (3%). There were 15 patients with 30 hypothermic episodes; subnormal temperature was found in all 50 patients from 1 to 47 times. Regression analysis of age and duration of SCI showed a nonsignificant relationship with body temperature. CONCLUSIONS: Our data suggest that patients with tetraplegia after SCI have significant dysfunction of thermoregulation associated with frequent episodes of subnormal body temperature in a normal ambient environment. Further studies are needed to evaluate possible consequences of low temperatures on the general health of patients and to develop preventive interventions.

Thromboprophylaxis in medical and surgical patients undergoing physical medicine and rehabilitation: consensus recommendations.

Venous thromboembolism (deep venous thrombosis with or without its major complication, pulmonary embolism) commonly occurs in patients undergoing rehabilitative therapy for various surgical or traumatic conditions and in patients with incapacitating medical illnesses. Thromboprophylaxis utilizes medications that interfere with the coagulation process and mechanical measures such as graded elastic stockings and intermittent pneumatic compression. To obtain a range of expert opinion on the optimal use of the numerous antithrombotic modalities now available, a consortium comprising clinical directors at a number of rehabilitative centers in south Florida met to review the literature on thromboprophylaxis in rehabilitation patients and to discuss the strategies followed at their respective facilities. The consortium then assembled a set of recommendations based on available evidence-based literature and established consensus on acceptable forms of thromboprophylaxis in each clinical condition in rehabilitation associated with an increased risk of venous thromboembolism.

Prevention and treatment of heterotopic ossification after spinal cord injury.

BACKGROUND/OBJECTIVES: Heterotopic ossification (HO) is a frequent, irreversible complication after spinal cord injury (SCI). The objective of this article is to explain the etiology of HO; present new advances in prevention, diagnosis, and management of this complication; and provide a suggested algorithm for clinical management. ETIOLOGY: Although still hypothetical, trauma and overexpression of bone morphogenic protein(s) in traumatized soft tissue appear to play important roles as initiating factors of HO. PREVENTION: Preventive use of nonsteroidal antiinflammatory agents (NSAIDs) reduces the incidence of HO by a magnitude of 2 to 3. MANAGEMENT: Early determination of serum creatine phosphokinase may have a diagnostic value in predicting the onset and severity of HO, and an NSAID may be added to etidronate therapy in the initial inflammatory phase of HO formation until C-reactive protein levels return to normal range. Surgery is indicated in a subset of patients, and a regimen that includes radiation therapy may prevent postoperative recurrence. CONCLUSION: Significant progress has been made in the early prevention and management of HO. Further studies are needed to elucidate the etiology.

Antifungal penetration into normal rabbit nucleus pulposus.

STUDY DESIGN: A rabbit model was used to assess the penetration into the nucleus pulposus of 3 commonly used antifungal medications: amphotericin B, amphotericin B lipid complex, and fluconazole. OBJECTIVES: The purpose of this study was to quantitate the penetration of antifungal medications into the normal rabbit nucleus pulposus. SUMMARY OF BACKGROUND DATA: Fungal infections of the spine are rarely, if ever, treated with medical management alone. Although antibiotic penetration into the nucleus pulposus has been studied extensively, no previous studies have attempted to quantitate the penetration of antifungals into the nucleus pulposus. METHODS: Twenty-four rabbits were given 2 doses of 1 of the antifungal medications studied. One hour after completion of the second dose, the animal was killed and the thoracolumbar spine was excised en bloc. Specimens of nucleus pulposus and serum were obtained and sent to an outside laboratory for analysis. Gas chromatography was used to determine the fluconazole tissue levels, and a bioassay was used to measure amphotericin B tissue levels. RESULTS: Three animals in the amphotericin B group died either after the first or second dose of medication was administered. Although amphotericin B and amphotericin B lipid complex did not show adequate penetration into the nucleus pulposus in 12 out of 12 animals, fluconazole reached therapeutic tissue levels in 5 out of 7 animals. CONCLUSIONS: Fluconazole showed superior penetration into the nucleus pulposus in an uninfected rabbit model when compared to amphotericin B and amphotericin B lipid complex. These findings were found to be statistically significant (P = 0.021), and they suggest that fluconazole may be a better choice for empiric therapy of fungal spine infections while cultures and sensitivities are pending.

C-reactive protein and erythrocyte sedimentation rate in patients with heterotopic ossification after spinal cord injury.

BACKGROUND/OBJECTIVE: Formation of heterotopic ossification (HO) in soft tissue after spinal cord injury (SCI) is associated with various degrees of inflammation. Recent studies have shown that inhibition of inflammatory reaction with nonsteroidal anti-inflammatory drugs is an effective prevention of HO after SCI. The goal of this study was to monitor the activity of the most widely used indicators of acute inflammation--namely, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)--in patients with HO. METHODS: In a retrospective study, the results of 37 patients with HO were evaluated. There were 25 patients with tetraplegia and 12 with paraplegia. The age (mean +/- SD) of the patients was 28 +/- 8 years (range = 19-46 years). The patients were admitted to the rehabilitation center 2 to 5 weeks after SCI. HO was confirmed by bone scintigraphy. Blood samples were obtained from the patients at the time of diagnosis of HO and during the therapy. ESR was measured with the Westergren method, and serum CRP was determined by enzyme-linked immunosorbent assay. RESULTS: In the acute stage of HO, both tests were elevated in all patients. In the later stages when clinical signs and symptoms of inflammation were resolving, both tests showed a gradual decline. When clinical signs and symptoms of inflammation (fever, acute soft tissue swelling, and erythema) were not present, the concentration of CRP was normal in 91.2% of patients, whereas only 17.6% of patients had normal ESR. Mean serum concentrations of CRP were 8.9 +/- 5.6 mg/L in the inflammatory phase and 0.9 +/- 0.6 mg/L in the noninflammatory phase. CONCLUSION: The data indicate that serum CRP is a useful and more specific test than is ESR for monitoring the inflammatory activity of HO after SCI. The normalization of CRP was seen during the first 3 to 4 weeks of etidronate therapy, indicating a resolution of acute-phase inflammatory reaction.

The value of serum creatine kinase in early diagnosis of heterotopic ossification.

BACKGROUND: Heterotopic ossification (HO) is a complication of spinal cord injury (SCI) characterized by formation of ectopic bone. Early diagnosis is critical, but available diagnostic methods have drawbacks. Serum creatine kinase may be a marker for the development and severity of HO. PARTICIPANTS: 18 SCI patients with diagnosed HO based on clinical findings and bone scintigraphy. METHODS: Serum creatine kinase levels were taken at the time of diagnosis of HO and during subsequent etidronate therapy. RESULTS: Of the 14 patients with normal creatine kinase values, 13 had no evidence of HO on follow-up radiographic examination. Of the 4 patients with elevated creatine kinase, all developed radiographic signs of HO. CONCLUSION: Elevated serum creatine kinase may be associated with a more aggressive course of HO as well as resistance to etidronate therapy. Further studies are needed to determine whether creatine kinase may serve as a marker for early, active HO.