Liam R. Harris

Umbilical Cord Tissue Offers the Greatest Number of Harvestable Mesenchymal Stem Cells for Research and Clinical Application: A Literature Review of Different Harvest Sites

PURPOSE Recent years have seen dramatic increases in the techniques used to harvest and isolate human mesenchymal stem cells. As the potential therapeutic aspects of these cells further develop, informative data on the differences in yields between tissue harvest sites and methods will become increasingly valuable. We collected and compared data on cell yields from multiple tissue harvest sites to provide insight into the varying levels of mesenchymal stem cells by tissue and offer primary and alternative tissue types for harvest and clinical application. METHODS The PubMed and Medline databases were searched for articles relating to the harvest, isolation, and quantification of human mesenchymal stem cells. Selected articles were analyzed for relevant data, which were categorized according to tissue site and, if possible, standardized to facilitate comparison between sites. RESULTS Human mesenchymal stem cell levels in tissue varied widely according to tissue site and harvest method. Yields for adipose tissue ranged from 4,737 cells/mL of tissue to 1,550,000 cells/mL of tissue. Yields for bone marrow ranged from 1 to 30 cells/mL to 317,400 cells/mL. Yields for umbilical cord tissue ranged from 10,000 cells/mL to 4,700,000 cells/cm of umbilical cord. Secondary tissue harvest sites such as placental tissue and synovium yielded results ranging from 1,000 cells/mL to 30,000 cells/mL. CONCLUSIONS Variations in allogeneic mesenchymal stem cell harvest levels from human tissues reflect the evolving nature of the field, patient demographic characteristics, and differences in harvest and isolation techniques. At present, Whartons jelly tissue yields the highest concentration of allogeneic mesenchymal stem cells whereas adipose tissue yields the highest levels of autologous mesenchymal stem cells per milliliter of tissue. CLINICAL RELEVANCE This comparison of stem cell levels from the literature offers a primer and guide for harvesting mesenchymal stem cells. Larger mesenchymal stem cell yields are more desirable for research and clinical application.

Fever is common postoperatively following posterior spinal fusion: infection is an uncommon cause.

OBJECTIVE To determine the frequency and clinical significance of postoperative fever in pediatric patients undergoing posterior spinal fusion (PSF). STUDY DESIGN A retrospective chart review was performed for consecutive patients undergoing PSF at a single institution between June 2005 and April 2011, with a minimum of 2-year follow up. Exclusion criteria were previous spine surgery, a combined anterior-posterior approach, and delayed wound closure at the time of surgery. RESULTS Two hundred and seventy-eight patients with an average age of 13 years (1-22 years) met inclusion criteria, with the following diagnoses: adolescent idiopathic scoliosis 43%, neuromuscular/syndromic scoliosis 39%, congenital scoliosis 11%, spondylolisthesis 4%, and Scheuermann kyphosis 3%. Seventy-two percent (201/278) of patients had a maximum temperature (Tmax) >38(°) postoperatively, and 9% (27/278) Tmax >39(°). The percentage of febrile patients trended down following the first postoperative day. Infection rate was 4% (12/278). There was no correlation between Tmax >38(°) or Tmax >39(°), and timing of fever, positive blood or urine cultures, pneumonia, or surgical site infection. CONCLUSION Seventy-two percent of pediatric patients undergoing PSF experienced postoperative fever, and 9% of patients had Tmax>39(°). There was no significant correlation between fever and positive blood culture, urine culture, pneumonia, or surgical site infection. This information may help relieve stress for families and healthcare providers, and obviate routine laboratory evaluation for fever alone.

Sacral Alar Iliac (SAI) Screws Fail 75% Less Frequently Than Iliac Screws in Neuromuscular Scoliosis.

Background: Despite recent popularity of sacral alar iliac (SAI) screws for fusion to the pelvis for neuromuscular scoliosis, there are little data regarding the failure rate of this technique compared with traditional modes of iliac fixation. Theoretical advantages of the SAI screws are obviating the need for a rod to iliac screw connector and a lower implant profile. The purpose of this study is to determine whether SAI screws have fewer failures than iliac screws in neuromuscular scoliosis. Methods: Review of neuromuscular patients treated with posterior spinal fusion with pelvic fixation from 2004 to 2012 with minimum 2-year follow-up was conducted. Medical records and imaging studies were reviewed. Patients were divided into 2 groups based on the type of pelvic fixation (SAI or iliac screws), and implant failures were compared between the groups. Results: A total of 101 patients were reviewed, including 55 patients with iliac screws and 46 patients with SAI screws. Implant failures included: disengagement of the rod to iliac screw connector (10%, 10/101), separation of screw head from screw shaft (4%, 4/101), and set screw disengagement (2%, 2/101). The SAI group had a lower implant failure rate (7%, 3/46) compared with the iliac screw group (24%, 13/55) (P=0.031). Rod to iliac screw connectors failed in 18% (10/55) of patients. There were significantly less surgical revisions in the SAI group (2%, 1/46) for pelvic screw prominence compared with the iliac screw group (11%, 6/55) (P=0.027). Conclusions: SAI screws had a lower rate of implant failure and revision surgery compared with iliac screws. If rod to screw connector failures are excluded, the failure rate of SAI screws of 6.5% (3/46) is similar to that of iliac screws 5.5% (3/55); therefore, the most important advantage of the SAI technique may be obviating the need for a screw to rod connector. Level of Evidence: Level III.

Periosteal turndown flap for posterior occipitocervical fusion: a technique review

PurposeRecently, several authors have proposed techniques for improving the fusion rate in pediatric posterior occipitocervical fusion including a variety of implants and the use of bone morphogenetic protein. A technique by Koop et al. using a periosteal flap for occipitocervical arthrodesis was described in 1984.MethodsA straight incision is made about the posterior neck to expose the occipitocervical region from the inion superiorly to the lowest cervical vertebrae to be fused inferiorly. The occiput is exposed superficial to the periosteum, which is then reflected and elevated from the occiput. The attachment is preserved at the caudal base of the flap and reflected over the intended area of fusion. When possible, fixation is then performed with cables, wires, screws, hooks, or plates.Case exampleA 6-year-old male with an occiput to C2 distraction injury underwent posterior spinal fusion from occiput to C3 using sublaminar wires, periosteal turndown flap, and autologous iliac crest bone graft.ConclusionIn small children with traumatic upper cervical spine instability, the periosteal turndown technique may be used as a safe adjunct for occipitocervical fusions.

Accessory Navicular is Associated With Wider and More Prominent Navicular Bone in Pediatric Patients by Radiographic Measurement.

Background: Accessory navicular (AN) is a common anatomic variant that is known to cause medial foot pain. Surgery may be required for excision if conservative measures fail. Often, the medial border of the navicular is excised in addition to the AN during surgery. The purpose of this radiographic study is to determine if the presence of an AN is associated with a wider or more prominent navicular in pediatric patients compared with normal controls. Methods: This study included pediatric patients who received an initial plain anteroposterior foot radiograph between January 1, 2004 and December 31, 2012 and were between the ages of 10 and 20 years. Feet with an AN were compared with those without, while controlling for age. Male and female patients were analyzed independently. Feet with fractures, deformities, or previous surgeries were excluded. Radiographic measurements included the navicular width and the protrusion of the navicular bone medially. Results: A total of 592 feet were included. An AN was identified in 73 feet. Male patients were analyzed separately from females. Cases with 1 AN bone had similar-sized native navicular bones in the contralateral normal foot compared with controls with 2 normal feet (P>0.05). The presence of an AN was associated with a larger navicular width (male: P=0.02, female: P=0.02) and a larger medial protrusion percent (male: P<0.01, female: P<0.01). Age was controlled for. Conclusion: On radiographic examination, feet with an AN had wider native navicular bones that protruded more medially than feet without an AN. Level of Evidence: Level IV—diagnostic.

Methicillin-resistant Staphylococcus aureus Swab Results Did Not Change Treatment or Outcome in Pediatric Spinal Fusion Patients.

Introduction: The aim of this study was to investigate whether preoperative methicillin-resistant Staphylococcus aureus (MRSA) swab results were predictive of surgical site infections (SSIs) in pediatric patients who have undergone spinal fusion. Methods: We conducted a retrospective chart review of patients who underwent posterior spinal fusion between 2004 and 2014 to determine preoperative MRSA colonization status and SSI rates and organisms. Before October 1, 2012, we administered vancomycin to the patients for infection prophylaxis; beginning October 1, 2012, patients received ceftazidime and Ancef (cefazolin for injection; GlaxoSmithKline). We added powdered vancomycin to all bone grafts. Results: A total of 1,200 patients met inclusion criteria. Of the patients, 2.3% (n = 28 of 1,200) were positive for MRSA, and an SSI developed in 3.1% (n = 37 of 1,200). No significant difference in infection rates was found between patients whose MRSA swab was positive and negative (positive swab = 1 SSI, negative swab = 36 SSIs; P = 0.88). Three SSIs were caused by MRSA. Conclusion: The results of a preoperative MRSA nasal swab had no correlation with SSI rates. Level of Evidence: Level III

Removal of Infected Posterior Spinal Implants: Be Prepared to Transfuse

STUDY DESIGN Single-center retrospective review of spinal deformity patients undergoing removal of infected posterior spinal fusion implants over a 10-year period. OBJECTIVE To evaluate the intraoperative blood loss and perioperative complications of implant removal in posterior spinal fusions. SUMMARY OF BACKGROUND DATA To our knowledge, no studies examine blood loss or complications associated with removal of infected spinal implants in spinal deformity. METHODS A retrospective review of 28 consecutive cases of infected posterior spinal fusion implant removal from 2003 to 2012 was performed. Exclusion criteria were patients with ≤6 levels of instrumentation, a partial removal of implants or a bleeding disorder. RESULTS The average estimated blood loss was 465 mL (range 100-1,505 mL). Average estimated blood volume was 3,814 mL (range 1,840-9,264 mL). The average percentage of estimated blood loss was 14.2% (range 1.9%-43.5%). On postoperative labs obtained at the conclusion of the procedure, there was an average loss in hematocrit of 6.6 from preoperative values. Seventy-one percent of patients (20/28) received a blood transfusion; 39% (11/28) of these received a transfusion intraoperatively and 54% (15/28) received a transfusion postoperatively. Forty-six percent of patients (13/28) experienced an associated medical complication in the postoperative period. Among these 13, there were 16 total complications, with the most common being seizures (4/16), pneumonia (2/16), and sepsis (2/16). Average hospital stay was 14 days (range 4-52). CONCLUSION Seventy-one percent of patients undergoing removal of infected spinal implants received a blood transfusion. We recommend having blood products available when removing posterior spinal instrumentation >6 levels. Patients and families should be counseled on the high risk of complications and expected hospital stay in these cases. LEVEL OF EVIDENCE Level III.