Jae-Wan Soh

Risk factors of adjacent segment disease requiring surgery after lumbar spinal fusion: comparison of posterior lumbar interbody fusion and posterolateral fusion.

Study Design. A retrospective study. Objective. To determine the incidence and risk factors of adjacent segment disease (ASD) requiring surgery among patients previously treated with spinal fusion for degenerative lumbar disease and to compare the survivorship of adjacent segment according to various risk factors including comparison of fusion methods: posterior lumbar interbody fusion (PLIF) versus posterolateral fusion (PLF). Summary of Background Data. One of the major issues after lumbar spinal fusion is the development of adjacent segment disease. Biomechanically, PLIF has been reported to be more rigid than PLF, and therefore, patients who undergo PLIF are suspected to experience a higher incidence of ASD than those who underwent PLF. There have been many studies analyzing the risk factors of ASD, but we are not aware of any study comparing PLIF with PLF in incidence of ASD requiring surgery. Methods. A consecutive series of 490 patients who had undergone lumbar spinal fusion of 3 or fewer segments to treat degenerative lumbar disease was identified. The mean age at index operation was 53 years, and the mean follow-up period was 51 months (12–236 mo). The number of patients treated by PLF and PLIF were 103 and 387, respectively. The incidence and prevalence of revision surgery for ASD were calculated by Kaplan-Meier method. For risk factor analysis, we used log-rank test and Cox regression analysis with fusion methods, sex, age, number of fused segments, and presence of laminectomy adjacent to index fusion. Results. After index spinal fusion, 23 patients (4.7%) had undergone additional surgery for ASD. Kaplan-Meier analysis predicted a disease-free survival rate of adjacent segments in 94.2% of patients at 5 years and 89.6% at 10 years after the index operation. In the analysis of risk factors, PLIF was associated with 3.4 times higher incidence of ASD requiring surgery than PLF (P = 0.037). Patients older than 60 years at the time of index operation were 2.5 times more likely to undergo revision operation than those younger than 60 years (P = 0.038). There were no significant differences in survival rates of the adjacent segment according to sex, preoperative diagnosis, number of fused segments, and concomitant laminectomy to adjacent segment. Conclusion. It was predicted that 10% of patients would undergo additional surgery for treating ASD within 10 years after index lumbar fusion. In this study, PLIF showed higher incidence of ASD than did PLF. Patient age greater than 60 years was another independent risk factor. Surgeons should carefully consider these factors at the time of surgical planning of lumbar fusion. Level of Evidence: 3

Risk factor analysis for predicting vertebral body re-collapse after posterior instrumented fusion in thoracolumbar burst fracture

BACKGROUND CONTEXT In the posterior instrumented fusion surgery for thoracolumbar (T-L) burst fracture, early postoperative re-collapse of well-reduced vertebral body fracture could induce critical complications such as correction loss, posttraumatic kyphosis, and metal failure, often leading to revision surgery. Furthermore, re-collapse is quite difficult to predict because of the variety of risk factors, and no widely accepted accurate prediction systems exist. Although load-sharing classification has been known to help to decide the need for additional anterior column support, this radiographic scoring system has several critical limitations. PURPOSE (1) To evaluate risk factors and predictors for postoperative re-collapse in T-L burst fractures. (2) Through the decision-making model, we aimed to predict re-collapse and prevent unnecessary additional anterior spinal surgery. STUDY DESIGN Retrospective comparative study. PATIENT SAMPLE Two-hundred and eight (104 men and 104 women) consecutive patients with T-L burst fracture who underwent posterior instrumented fusion were reviewed retrospectively. Burst fractures caused by high-energy trauma (fall from a height and motor vehicle accident) with a minimum 1-year follow-up were included. The average age at the time of surgery was 45.9 years (range, 15-79). With respect to the involved spinal level, 95 cases (45.6%) involved L1, 51 involved T12, 54 involved L2, and 8 involved T11. Mean fixation segments were 3.5 (range, 2-5). Pedicle screw instrumentation including fractured vertebra had been performed in 129 patients (62.3%). OUTCOME MEASURES Clinical data using self-report measures (visual analog scale score), radiographic measurements (plain radiograph, computed tomography, and magnetic resonance image), and functional measures using the Oswestry Disability Index were evaluated. METHODS Body height loss of fractured vertebra, body wedge angle, and Cobb angle were measured in serial plain radiographs. We assigned patients to the re-collapse group if their body height loss progressed greater than 20% at any follow-up time compared with immediate postoperative body height loss; we assigned the remaining patients to the well-maintained group. The chi-square test and t test of SPSS were used for comparison of differences between two groups and multiple logistic regression analysis for risk factor evaluation. Through the decision tree analysis of statistical package R, a decision-making model was composed, and a cutoff value of revealed risk factors and re-collapse rate of each subgroup were identified. The present study wassupported by the University College of Medicine Research Fund (university to which authors belong). There was no external funding source for this study. The authors have no conflict of interest to declare. RESULTS Re-collapse occurred in 31 of 208 patients (14.9%). In this group, age, the proportion of male gender, preoperative height loss, and preoperative wedge angle were significantly greater than the well-maintained group. Multivariable logistic regression analysis identified two independent risk factors: age (adjusted odds ratio 1.084, p=.002) and body height loss (adjusted odds ratio 1.065, p=.003). According to the decision-making tree, age (>43 years) was the most discriminating variable, andpreoperative body height loss (>54%) was the second. In this model, the re-collapse rate was zero in ages less than 43 years, and among those remaining, nearly 80% patients with greater than 54% of body height loss belonged to the re-collapse group. CONCLUSIONS The independent predictors of re-collapse after posterior instrumented fusion for T-L burst fracture were the age at operation (>43 years old) and preoperative body height loss (>54%). Careful assessment using our decision-making model could help to predict re-collapse and prevent unnecessary additional spinal surgery for anterior column support, especially in young patients.

External Snapping Hip Treated by Effective Designed N-plasty of the Iliotibial Band

Purpose The purpose of this study is to present the effective design of N-plasty of the iliotibial band and surgical results of its use as a treatment for refractory external snapping hip. Materials and Methods We evaluated 17 patients (24 cases) with external snapping hip who underwent N-plasty between October 2013 and May 2016 and who were followed up for at least 12 months. All patients were male and the mean age was 20.8 years. The mean duration of symptoms prior to surgical intervention was 28.5 months with an average follow up of 24.5 months. Surgery was defined as being successful when patients could carry out their daily activities and exercise without a clicking sensation or pain 6 months after surgery until their last follow-up. Failure was defined when either a clicking sensation or pain was present. The visual analog scale (VAS) and modified Harris hip score (mHHS) were measured and compared preoperatively and at last follow-up. Results All patients had complete resolution of pain and snapping. The VAS decreased from 6.77 preoperatively to 0.09 postoperatively and mHHS improved from 69.5 to 97.8 after surgery. Conclusion Modified designed N-plasty is considered to be an excellent treatment method facilitating operation reproducibility with maximum elongation effect of the iliotibial band.

Sciatic Nerve Palsy Caused by Ruptured and Contracted Short External Rotator Muscles after Primary Total Hip Arthroplasty

Although the incidence of sciatic nerve palsy following total hip arthroplasty is low, this complication can cause devastating permanent nerve palsy. The authors experienced a case of sciatic nerve palsy caused by ruptured and contracted external rotator muscles following total hip arthroplasty in a patient suffering from osteonecrosis of the femoral head. We report this unusual case of sciatic nerve palsy with a review of the literature.