Cost-Effectiveness and Clinical Outcomes of Lateral Lumbar Interbody Fusion With Tricalcium Phosphate and Iliac Bone Graft Compared With Posterior Lumbar Interbody Fusion With Local Bone Graft in Single-Level Lumbar Spinal Fusion Surgery in Thailand.

BACKGROUND: Nowadays, minimally invasive lateral lumbar interbody fusion (LLIF) is used to treat degenerative lumbar spine disease. Many studies have proven that LLIF results in less soft tissue destruction and rapid recovery compared with open posterior lumbar interbody fusion (PLIF). Our recent cost-utility study demonstrated that LLIF was not cost-effective according to the Thai willingness-to-pay threshold, primarily due to the utilization of an expensive bone substitute: bone morphogenetic protein 2. Therefore, this study was designed to use less expensive tricalcium phosphate combined with iliac bone graft (TCP + IBG) as a bone substitute and compare cost-utility analysis and clinical outcomes of PLIF in Thailand. METHODS: All clinical and radiographic outcomes of patients who underwent single-level LLIF using TCP + IBG and PLIF were retrospectively collected. Preoperative and 2-year follow-up quality of life from EuroQol-5 Dimensions-5 Levels and health care cost were reviewed. A cost-utility analysis was conducted using a Markov model with a lifetime horizon and a societal perspective. RESULTS: All enrolled patients were categorized into an LLIF group (n = 30) and a PLIF group (n = 50). All radiographic results (lumbar lordosis, foraminal height, and disc height) were improved at 2 years of follow-up in both groups (P < 0.001); however, the LLIF group had a dramatic significant improvement in all radiographic parameters compared with the PLIF group (P < 0.05). The fusion rate for LLIF (83.3%) and PLIF (84%) was similar and had no statistical significance. All health-related quality of life (Oswestry Disability Index, utility, and EuroQol Visual Analog Scale) significantly improved compared with preoperative scores (P < 0.001), but there were no significant differences between the LLIF and PLIF groups (P > 0.05). The total lifetime cost of LLIF was less than that of PLIF (15,355 vs 16,500 USD). Compared with PLIF, LLIF was cost-effective according to the Thai willingness-to-pay threshold, with a net monetary benefit of 539.76 USD. CONCLUSION: LLIF with TCP + IBG demonstrated excellent radiographic and comparable clinical health-related outcomes compared with PLIF. In economic evaluation, the total lifetime cost was lower in LLIF with TCP + IBG than in PLIF. Furthermore, LLIF with TCP + IBG was cost-effective compared with PLIF according to the context of Thailand. CLINICAL RELEVANCE: LLIF with less expensive TCP + IBG as bone graft results in better clinical and radiographic outcomes, less lifetime cost, and cost-effectiveness compared with PLIF. This suggests that LLIF with TCP + IBG could be utilized in lower- and middle-income countries for treating patients with degenerative disc disease.

Vertical Relationship Ratio (VRR): A High Reliability and Accuracy Radiographic Measurement for Basilar Invagination in Rheumatoid Arthritis.

BACKGROUND Previous radiographic measurements for diagnosis of a basilar invagination or impression (BI) in rheumatoid arthritis (RA) were used as reference values based on anatomical reference distances. Due to the obscured anatomical landmarks, our group proposed a new radiographic measurement based on anatomic ratios to identify BI. MATERIAL AND METHODS The vertical relationship ratio (VRR) was developed and evaluated. The VRR is the relationship between the distance obtained with the modified Ranawat method and the C3 vertebral body height. VRR was used to assess its ability to distinguish BI in 3 patient groups (28 RA with BI, 37 RA without BI, and 56 non-RA patients). The intra- and inter-observer reliability, the sensitivities, and specificities of all measurements were analyzed. The cutoff value of VRR measurement was calculated by using the receiver operating characteristic (ROC) curve. RESULTS The VRR measurement showed excellent intra- and inter-observer reliabilities. The VRR could significantly distinguish RA patients with BI from RA patients without BI. The mean VRR of RA patients with BI (1.82±0.20) was less than for the non-RA patients (2.26±0.19) and the RA patients without BI (2.24±0.19). The cutoff value of VRR from the ROC curve was below 2.025. Its sensitivity was 92.85%, specificity was 97.85%, positive predictive value was 92.86%, and negative predictive value was 97.84%. CONCLUSIONS VRR has excellent intra-/inter-observer reliability and can distinguished BI in RA patients. We recommend using VRR in preference to the other available methods for assessment and screening BI in rheumatoid arthritis.

Prediction of Callus Subsidence in Distraction Osteogenesis Using Callus Formation Scoring System: Preliminary Study.

OBJECTIVE: To develop the scoring system which describes both quality and quantity of callus formation to predict the callus subsidence. METHODS: Forty-seven bony segments with an average lengthening of 5.17 ± 2.83 cm were included. The score was calculated based on the amount of callus classified in five patterns and the summation with the density of the callus classified in four patterns; the total score was 9. Bony subsidence >10% or >10° angulation were considered significant. We analyzed all of the data to find the most appropriate score that would prevent callus subsidence <10% and prevented angulation of the regeneration bone <10 degrees. Data was analyzed by using the receiver operating characteristic (ROC) curve. An area under the curve of 0.9-1 indicated an excellent test, 0.8-0.9 indicated a good test, 0.7-0.8 indicated a fair test, 0.6-0.7 indicated a poor test, and 0.5-0.6 indicated a fail test. The appropriate score for Ilizarov removal was selected from the highest sensitivity and specificity. RESULTS: Twenty-two tibia segments and 25 femur segments were included. The mean of bone lengthening was 5.17 ± 2.83 cm (range, 1.6-13.5 cm) and the mean of percentage lengthening was 16.58% ± 10.03% (range, 4.63%-56.84%). The mean distraction period was 5 months. The average months of follow-up for measurement of bony subsidence was 4.2 months. Mean subsidence was 21.06% (1.54%-57.44%). The mean of callus subsidence was 1.29 ± 1.17 cm (range, 0.03-4.72 cm). There were 32 segments (68%) with callus subsidence greater than 10% and 15 segments (32%) with subsidence less than 10%. The callus subsidence ranged from 0.3 mm to 4.72 cm, with 68% of bony fragments having significant subsidence. Type 5 callus diameter was statistically significant (P < 0.0001) in preventing callus subsidence compared to the other types. Type 4 callus density was statistically significant in preventing callus subsidence compared to the other types (P < 0.0001). The ROC curve with area under the curve 0.961 and sensitivity 0.933 showed that a callus scoring system score >7.5 was effective in preventing significant callus subsidence. When using score 8 as a result from the ROC curve, 73.3% of bony fragment subsidence was <10% with sensitivity 93.3 and specificity 83.2. CONCLUSION: Callus diameter 81%-100% and callus density type 4 could prevent significant callus subsidence. Based on the results of the present study we suggest using callus score > 8 to determine the time of Ilizarov removal.