No abstract

BackgroundOsteotomies including pedicle subtraction (PSO) and/or Smith-Peterson (SPO) are used to facilitate surgical correction of adult spinal deformity (ASD), but are associated with complications including instrumentation failure and rod fracture (RF). The purpose of this study was to determine incidence and risk factors for RF, including a clinically significant subset (CSRF), after osteotomy for ASD.MethodsA retrospective review of clinical records was conducted on consecutive ASD patients treated with posterolateral instrumented fusion and osteotomy. Seventy-five patients (50 female; average age, 59) met strict inclusion/exclusion criteria and follow-up of ≥1 year. Data was extracted pertaining to the following variables: patient demographics; details of surgical intervention; instrumentation; and postoperative outcomes. Patients were divided into two subgroups: 1) rod fracture (RF) and 2) non-RF. The RF subgroup was further divided into CSRF and non-CSRF. Odds ratios (OR) were calculated to evaluate the association between risk factors and RF. The χ2-test was used to define P-values for categorical variables, and T-test was applied for continuous variables, P-values ≤0.05 were considered significant.ResultsIncidence rates of RF were: for entire population, 9.3 % (95 % Cl: 2.7 %; 15.9 %); for PSO, 16.2 % (95 % Cl: 4.3; 28.1); and for SPO, 2.6 % (95 % Cl: 0 %; 7.7 %); the OR of PSO versus SPO was 7.2 (95 % Cl: 0.8; 62.7, P = 0.1). CSRF incidence was 5.3 % (95 % CI: 0.2 %; 10.4 %). Significant risk of RF was revealed for following factors: fusion construct crossing both thoracolumbar and lumbosacral junctions (OR = 9.1, P = 0.05), sagittal rod contour >60° (OR = 10.0, P = 0.04); the presence of dominos and/or parallel connectors at date of rod fracture (OR = 10.0, P = 0.01); and pseudarthrosis at ≥1 year follow-up (OR = 28.9, P < 0.001). Statistically significant risk of CSRF was revealed for fusion to pelvis (P = 0.05) and pseudarthrosis at ≥1 year follow-up (OR = 50.3, CI: 4.2; 598.8, P < 0.01).ConclusionsThe risk of RF after posterolateral instrumented correction of ASD with osteotomy had statistically significant association with the following factors: pseudarthrosis at ≥1 year follow-up; sagittal rod contour >60°; presence of dominos and/or parallel connectors at date of fracture; and fusion construct crossing both thoracolumbar and lumbosacral junctions. Statistically significant risk for the CSRF subset was fusion to the pelvis and pseudarthrosis at ≥1 year follow-up.

This review did not reveal any methods for the prediction of progression in AIS that could be recommended for clinical use as diagnostic criteria.

Object Axial lumbar interbody fusion (AxiaLIF) is a novel minimally invasive approach for fusion of L4–5 and L5–S1. This technique uses the presacral space for percutaneous access to the anterior sacrum. The AxiaLIF procedure has the potential to decrease patient recovery time, length of hospital stay, and overall occurrence of surgical complications. It can be used alone or in combination with minimally invasive or traditional open fusion procedures. The purpose of this study was to evaluate complications of the AxiaLIF procedure at the authors' institutions. Methods Patients who underwent AxiaLIF surgery between October 2005 and June 2009 at the authors' institutions were identified. The authors retrospectively reviewed these patients' charts, including operative reports and postoperative medical records, to determine what complications were encountered. Results A total of 68 patients underwent AxiaLIF surgery, with an average follow-up time of 34 months. Sixteen patients (23.5%) experienced a total of 18 complications (26.5%); this group included 8 men and 8 women (mean age 52.1 years). These complications included pseudarthrosis (8.8%), superficial infection (5.9%), sacral fracture (2.9%), pelvic hematoma (2.9%), failure of wound closure (1.5%), transient nerve root irritation (1.5%), and rectal perforation (2.9%). Conclusions The complication rate associated with AxiaLIF in the present study was relatively low (26.5%). The most common complications were superficial infection and pseudarthrosis. There were 2 cases of rectal perforation associated with AxiaLIF; one case was found intraoperatively and the other presented 4 days postoperatively. Both patients underwent emergency repair by a general surgeon and had no long-term sequelae as a result of the rectal injuries. It is important for surgeons to be aware of the potential for these complications. Many of these complications can probably be avoided with proper patient selection and operative planning. Preoperative MR imaging, a detailed patient physical examination and history, full bowel preparation, and the use of live fluoroscopy can all help to prevent complications with AxiaLIF surgery.

A prospective, randomized study was performed in an ovine model to compare the efficacy of an anorganic bovine-derived hydroxyapatite matrix combined with a synthetic 15 amino acid residue (ABM/P-15) in facilitating lumbar interbody fusion when compared with autogenous bone harvested from the iliac crest. P-15 is a biomimetic to the cell-binding site of Type-I collagen for bone-forming cells. When combined with ABM, it creates the necessary scaffold to initiate cell invasion, binding, and subsequent osteogenesis. In this study, six adult ewes underwent anterior-lateral interbody fusion at L3/L4 and L4/L5 using PEEK interbody rings filled with autogenous bone at one level and ABM/P-15 at the other level and no additional instrumentation. Clinical CT scans were obtained at 3 and 6 months; micro-CT scans and histomorphometry analyses were performed after euthanization at 6 months. Clinical CT scan analysis showed that all autograft and ABM/P-15 treated levels had radiographically fused outside of the rings at the 3-month study time point. Although the clinical CT scans of the autograft treatment group showed significantly better fusion within the PEEK rings than ABM/P-15 at 3 months, micro-CT scans, clinical CT scans, and histomorphometric analyses showed there were no statistical differences between the two treatment groups at 6 months. Thus, ABM/P-15 was as successful as autogenous bone graft in producing lumbar spinal fusion in an ovine model, and it should be further evaluated in clinical studies.