Surgical Site Infection in Spine Surgery: Who Is at Risk?

STUDY DESIGN: Retrospective literature review of spine surgical site infection (SSI). OBJECTIVE: To perform a review of SSI risk factors and more specifically, categorize them into patient and surgical factors. METHODS: A review of published literature on SSI risk factors in adult spine surgery was performed. We included studies that reported risk factors for SSI in adult spinal surgery. Excluded are pediatric patient populations, systematic reviews, and meta-analyses. Overall, we identified 72 cohort studies, 1 controlled-cohort study, 1 matched-cohort study, 1 matched-paired cohort study, 12 case-controlled studies (CCS), 6 case series, and 1 cross-sectional study. RESULTS: Patient-associated risk factors-diabetes mellitus, obesity (body mass index >35 kg/m2), subcutaneous fat thickness, multiple medical comorbidities, current smoker, and malnutrition were associated with SSI. Surgical associated factors-preoperative radiation/postoperative blood transfusion, combined anterior/posterior approach, surgical invasiveness, or levels of instrumentation were associated with increased SSI. There is mixed evidence of age, duration of surgery, surgical team, intraoperative blood loss, dural tear, and urinary tract infection/urinary catheter in association with SSI. CONCLUSION: SSIs are associated with many risk factors that can be patient or surgically related. Our review was able to identify important modifiable and nonmodifiable risk factors that can be essential in surgical planning and discussion with patients.

Prophylaxis of surgical site infection in adult spine surgery: A systematic review.

INTRODUCTION: Surgical site infection (SSI) remains a significant source of morbidity in spine surgery, with reported rates varying from 0.7 to 16%. OBJECTIVE: To systematically review and evaluate the evidence for strategies for prophylaxis of SSI in adult spine surgery in the last twenty years. METHODS: Two independent systematic searches were conducted, at two international spine centers, encompassing PubMed, ClinicalTrials.gov, Cochrane Database, EBSCO Medline, ScienceDirect, Ovid Medline, EMBASE (Ovid), and MEDLINE. References were combined and screened, then distilled to 69 independent studies for final review. RESULTS: 11 randomized controlled trials (RCTs), 51 case-controlled studies (CCS), and 7 case series were identified. Wide variation exists in surgical indications, approaches, procedures, and even definitions of SSI. Intra-wound vancomycin powder was the most widely studied intervention (19 studies, 1 RCT). Multiple studies examined perioperative antibiotic protocols, closed-suction drainage, povidone-iodine solution irrigation, and 2-octyl-cyanoacrylate skin closure. 18 interventions were examined by a single study only. There is limited evidence for the efficacy of intra-wound vancomycin. There is strong evidence that closed-suction drainage does not affect SSI rates, while there is moderate evidence for the efficacy of povidone-iodine irrigation and that single-dose preoperative antibiotics is as effective as multiple doses. Few conclusions can be drawn about other interventions given the paucity and poor quality of studies. CONCLUSIONS: While a small body of evidence underscores a select few interventions for SSI prophylaxis in adult spine surgery, most proposed measures have not been investigated beyond a single study. Further high level evidence is required to justify SSI preventative treatments.

Occiput to C1-2 Fractures: Assessment, Bracing, and Reconstructive Techniques.

The craniocervical junction is a transitional segment from the cranium to the cervical spine with a unique architecture that accommodates a high degree of motion and requires considerable contributions from surrounding ligamentous structures for stability. The assessment, immobilization, and management of upper cervical spine injuries requires consideration of the complex architecture that exists and the movement that occurs in the craniocervical junction. Early diagnosis and stabilization of upper cervical spine injuries is crucial because devastating complications may occur in patients with an upper cervical spine injury. Several clinical and radiographic findings should elicit suspicion for occipitocervical dissociation, which is a highly unstable injury that requires surgical management via occipitocervical fusion. In general, the management of C1 fractures is based on the status of the transverse atlantal ligament. Isolated atlantoaxial dislocations are rare injuries and commonly are observed as translation injuries rather than rotation injuries in adults. The management of type II dens fractures is challenging and controversial, particularly in elderly patients; therefore, multiple factors must be considered in the management of type II dens fractures. Although many hangman fractures can be managed nonsurgically, atypical hangman fractures must be observed closely, and unstable or displaced hangman fractures are reduced and managed surgically.

Conjoint Tendon Release in Direct Anterior Total Hip Arthroplasty: No Impact on Patient Outcomes.

The direct anterior (DA) approach for total hip arthroplasty (THA) has become increasingly popular. However, femoral access can be more technically challenging in difficult cases as compared with other approaches. Conjoint tendon release can improve proximal femoral exposure, but its effect on patient function and pain has not been studied. This study evaluated the effect of conjoint tendon release on length of stay (LOS), inpatient pain medication requirements, and functional outcomes of patients undergoing DA THA. The authors retrospectively reviewed charts of all primary DA THAs conducted by a single surgeon between August 2012 and July 2015. Patient demographics, bilateral THA cases, intraoperative conjoint tendon or other soft tissue releases, intraoperative complications, LOS, and inpatient pain medication data were evaluated. One-year functional outcome scores, including the Western Ontario and McMaster Universities Osteoarthritis Index and the Harris Hip Scores, were also reviewed. The authors identified 312 primary DA THAs, with 29 concurrent bilateral THAs. The conjoint tendon was released in 180 cases, whereas a tensor fascia lata (TFL) was released for 29 cases. Mean LOS was 1.3±1.1 days, with patient age (P=.002), bilateral THA (P<.001), TFL release (P=.005), and intraoperative complications (P=.002) predictive of LOS. Mean daily morphine equivalent dose narcotic use was 43.2±48.2 mg, with age being a negative predictor of narcotic use (P=.019). Conjoint tendon release was not predictive of LOS, inpatient pain medication requirements, or outcome scores. Given that conjoint release improves femoral exposure but does not affect LOS or 1-year patient-reported outcomes, intraoperative thresholds for conjoint release should be low. [Orthopedics. 2017; 40(6):e971-e974.].

Influence of graft size on spinal instability with anterior cervical plate fixation following in vitro flexion-distraction injuries.

BACKGROUND CONTEXT: Anterior cervical discectomy and fusion with plating (ACDFP) is commonly used for the treatment of distractive-flexion cervical spine injuries. Despite the prevalence of ACDFP, there is little biomechanical evidence for graft height selection in the unstable trauma scenario. PURPOSE: This study aimed to investigate whether changes in graft height affect the kinematics of instrumented ACDFP C5-C6 motion segments in the context of varying degrees of simulated facet injuries. STUDY DESIGN: In vitro cadaveric biomechanical study was used as study design. METHODS: Seven C5-C6 motion segments were mounted in a custom spine simulator and taken through flexibility testing in axial rotation, lateral flexion, and flexion-extension. Specimens were first tested intact, followed by a standardized injury model (SIM) for a unilateral facet perch at C5-C6. The stability of the ACDFP approach was then examined with three graft heights (computed tomography-measured disc space height, disc space height undersized by 2.5 mm, and disc space height oversized by 2.5 mm) within three increasing unstable injuries (SIM, an added unilateral facet fracture, and a simulated bilateral facet dislocation injury). RESULTS: In all motions, regardless of graft size, ACDFP reduced range of motion (ROM) from the SIM state. For flexion-extension, the oversized graft had a larger decrease in ROM compared with the other graft sizes (p<.05). Between graft sizes and injury states, there were a number of interactions in axial rotation and lateral flexion, where specifically in the most severe injury, the undersized graft had a larger decrease in ROM than the other two sizes (p<.05). CONCLUSIONS: This study found that graft size did affect the kinematic stability of ACDFP in a series of distractive-flexion injuries; the undersized graft resulted in both facet overlap and locking of the uncovertebral joints leading to decreased ROM in lateral bending and axial rotation, whereas an oversized graft provided larger ROM decreases in flexion-extension. As such, a graft that engages the uncovertebral joint may be more advantageous in providing a rigid environment for fusion with ACDFP.

Does patellectomy jeopardize function after TKA?

BACKGROUND: The patella provides important mechanical leverage to the knee extensor mechanism. Patellectomy does not exclude the development of tibiofemoral arthrosis. QUESTIONS/PURPOSES: We asked whether (1) TKA provides improvements in clinical outcome scores in patellectomized knees and (2) the scores of TKA in patellectomized knees are comparable to those in knees with intact patellae. METHODS: We evaluated 50 patients (52 primary TKAs) with patellectomized knees and a control group of 52 patients (52 primary TKAs) with intact patellae matched for age, sex, implant, and surgical year between 1984 and 2009. We compared the preoperative and latest postoperative SF-12, WOMAC, and Knee Society score (KSS). Minimum followup was 24 months (mean, 69 months; range, 24-204 months). RESULTS: The mean WOMAC score in the control group improved from 41.8 (range, 7.5-72.4) preoperatively to 69.1 (range, 17.0-100.0) postoperatively, while that in the patellectomized group improved from 35.8 (range, 5.2-62.2) to 61.3 (range, 17.5-96.2). The mean KSS improved from 80.4 (range, 4.0-143.0) preoperatively to 161.4 (range, 69.0-200.0) postoperatively in the control group and from 76.9 (range, 5-134) to 136.8 (range, 7-199) in the patellectomized group. Mean postoperative WOMAC scores were comparable between the two groups, while the mean KSS was lower in the patellectomized group. The mean SF-12 scores were not different after TKA or between groups. CONCLUSIONS: Despite the mechanical disadvantage to the knee extensor mechanism rendered by a previous patellectomy, TKA for tibiofemoral arthrosis in these patients relieved pain and restored function, but function was on average lower than that in patients with intact patellae. LEVEL OF EVIDENCE: Level III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Hemithyroidectomy is the preferred initial operative approach for an indeterminate fine needle aspiration biopsy diagnosis.

BACKGROUND: Fine needle aspiration biopsy represents the critical initial diagnostic test used for evaluation of thyroid nodules. Our objectives were to determine the cytological distribution, the utility of clinicopathologic characteristics for predicting malignancy and the true proportion of cancer among individuals who presented with indeterminate cytology and had undergone thyroid surgery for suspicion of cancer. METHODS: We retrospectively reviewed 1040 consecutive primary thyroid operations carried out over an 8-year period at a tertiary care endocrine referral centre. Follicular neoplasm (FN), Hürthle cell neoplasm (HN), neoplasms suspicious for but not diagnostic of papillary carcinoma (IP) and neoplasms with cellular atypia (IA) were reviewed. RESULTS: In all, 380 individuals presented with cytologically indeterminate thyroid nodules. Of these, 252 (66%) patients had FN, 47 (12%) HN, 44 (12%) IP, 26 (7%) IA and 11 (4%) had mixed diagnoses. Biopsied lesions were found to be malignant on pathological evaluation in 102 (27%) patients: 49 (19%) with FN, 11 (23%) HN, 28 (64%) IP and 9 (35%) with IA. Hemithyroidectomy was adequate definitive treatment in 196 of 225 (87%) patients with FN and 39 of 42 (93%) with HN. Significant associations with a cancer diagnosis were identified for smaller tumour size in patients with FN (p = 0.004) and right thyroid lobe location in patients with IP (p = 0.012), although these factors were nonsignificant in the corrected analyses for multiple comparisons. CONCLUSION: In a review of the experience at a Canadian centre, 4 operations were carried out to identify each cancer, and hemithyroidectomy was the optimal initial and definitive surgical approach for most patients.

Gender differences in thyroid cancer: a critical review.

It has long been known that the incidence of thyroid cancer in women is significantly higher than that in men. The objective of this article is to review gender differences in thyroid cancer, as well as epidemiological, clinical and experimental research on the role of sex hormones, their receptors and other molecular factors in this well-established thyroid cancer gender discrepancy. Although more common in women, thyroid cancer typically presents at a more advanced stage and with a worse disease prognosis in men. Clinical evidence on the impact of estrogen and other sex hormones on thyroid cancer has remained inconclusive, although numerous experimental studies have suggested that these hormones and their receptors may play a role in tumorigenesis and tumor progression. Studies of thyroid cancer cell lines suggest that an imbalance between the two estrogen receptor (ER) isoforms, α and ß, may be responsible for the cell proliferation seen with estrogen treatment. Expression studies on thyroid tumors indicate that they express ER and possibly progesterone receptors and androgen receptors, but there is conflicting evidence as to whether or not there is a difference in receptor status between thyroid cancers, benign thyroid lesions and normal thyroid tissue. There have been few studies evaluating the ERα/ERß profiles in thyroid tumors and normal thyroid tissue. Our understanding of the underlying basis for sex differences in thyroid cancer has improved over the last few decades, but the relationship between gender and thyroid cancer risk has remained elusive. Areas for future research include ERα/ERß profiling of normal and neoplastic thyroid tissue, association between ER status and tumor dedifferentiation, and evaluation of the signaling pathways by which estrogen and other sex steroids exert their effects on thyroid cancer cells. Sex steroid receptors, and then downstream signaling pathways, represent promising future therapeutic targets for thyroid cancer treatment, and further study is required.

Altered vasodilator role of nitric oxide synthase in the pancreas, heart and brain of rats with spontaneous type 2 diabetes.

Type 2 diabetes is associated with altered regional blood flow and expression of nitric oxide synthase (NOS). We examined the functional role of constitutive and inducible NOS synthase (cNOS and iNOS, respectively) on regional blood flow in thiobutabarbital-anesthetized Zucker diabetic fatty (ZDF) and control rats via the radioactive microspheres technique. Blood flow was measured at baseline (1 h after surgery), after i.v. administration of 1400W (N-3-aminomethyl-benzyl-acetamidine, selective iNOS inhibitor, 3 mg/kg), and again after i.v. N(G)-nitro-l-arginine methyl ester (L-NAME, non-selective NOS inhibitor, 8 mg/kg). Both groups had similar baseline mean arterial pressure, cardiac output and total peripheral resistance, but the ZDF rats had lower heart rate relative to the control rats (272 versus 305 beats/min). Whereas 1400W did not alter mean arterial pressure or blood flow in either group, L-NAME markedly increased mean arterial pressure and total peripheral resistance, and reduced cardiac output, heart rate, blood flow and arterial conductance in all organs/tissues of both the control and ZDF rats. L-NAME caused greater vasoconstriction in the heart (1.5-times the constriction in control rats) and brain (1.5-times) of the ZDF rats, but less in the pancreas (0.6-times). Thus, cNOS had greater vasodilator control of the heart and brain, but less in the pancreas of the ZDF than control rats. iNOS has negligible influence on blood flow in both groups of rats.

Inducible nitric oxide synthase depresses cardiac contractile function in Zucker diabetic fatty rats.

Cardiac contractile dysfunction is a common occurrence in type 2 diabetes. The aim was to examine if inducible nitric oxide synthase (iNOS) causes cardiac dysfunction in Zucker diabetic fatty (ZDF) rats, a model of type 2 diabetes. ZDF and Zucker lean control rats (20 week old) were studied at 6 h after recovery from halothane anaesthesia and surgery that involved insertions of catheters into the iliac arteries, iliac veins and the left ventricle via the right carotid artery. Protein expression and activity of iNOS in the hearts were measured by immunostaining and arginine-citrulline conversion assay, respectively. Both groups had similar baseline left ventricular developed pressure and maximum rate of rise of left ventricular pressure (+dP/dt), but heart rate and rate pressure product were lower in the ZDF than control rats. Dobutamine dose-dependently increased left ventricular developed pressure, +dP/dt, heart rate and rate pressure product in both groups, but the responses were less in the diabetic than control rats. The activity and protein expression of iNOS and nitrotyrosine were higher in the hearts of the diabetic than control rats. Selective inhibition of iNOS by 1400 W (N-3-aminomethyl-benzyl-acetamidine) did not alter responses to dobutamine in the control rats, but augmented the effects of dobutamine on left ventricular developed pressure and rate pressure product in the diabetic rats. The results indicate that activation of iNOS contributed to left ventricular contractile dysfunction in the ZDF rats, and this was partially reversed by selective inhibition of the activity of iNOS.