Accuracy of plain radiographs to identify wrong positioned free hand pedicle screw in the deformed spine.

BACKGROUND: The accuracy rate of pedicle screws placement in the deformed spine can be easily assessed on computed tomography (CT), while it is difficult to be evaluated in conventional radiography in the posterior-anterior (PA) and lateral projections, even if they are an essential step to identify wrong positioned screws after surgery. Aim of the study is to evaluate the accuracy of plain radiographs compared with CT in identifying wrong positioned pedicle-screws in the deformed spine. METHODS: A total of 1125, pedicle screws implanted with free hand technique in 79 patients surgically treated for scoliosis with intraoperative/postoperative. Plain radiographs and CT of the spine were investigated. The pedicle screws location was evaluated by three independent spine surgeon with more than 10 years' experience, using the method described by Kim in plain radiographs. Other three independent spine surgeon with more than 10 years' experience, unknowing the previous results, evaluate the same pedicle screws using the Rongming Xu criteria in CT scans. When there is a disagreement among the readers is chosen the most common classification. Data were finally compared and analyzed using SPSS® 11.0 software. RESULTS: Comparative analysis of pedicle screws using postoperative CT and plain radiographs showed: 22 true positives, i.e. pedicle-screws considered as out both in plain radiographs and CT scans; 1048 true negatives, i.e. pedicle-screws evaluated as in both in X-ray and CT scans; 9 false positives, i.e. pedicle-screws considered as out in plain radiographs but defined in in CT scans, and 52 false negatives, i.e. pedicle-screws considered as in in plain-radiographs, but defined out in CT. The accuracy of standard radiographs in detecting the placement of pedicle-screws amounts to 94.6%, with a sensitivity of 71% and a specificity of 95.3%. CONCLUSIONS: Even if only 61 pedicle-screws out (5.4%) were not correctly identified in plain radiographs, none dangerous placement (3 cases) is unrecognized, underling that the CT accuracy is higher only to detect screws with a "safe" wrong placement that, according to literature data, not require revision surgery. Intraoperative X-ray, allowing a possible revision of misplaced screws during surgery, must be considered as the gold standard for pedicle screw evaluation. Even if postoperative CT scanning should not be performed as a routine control measure, it still useful in case of clinically suspected screw wrong positioning.

Spinopelvic parameter changes and low back pain improvement due to femoral neck anteversion in patients with severe unilateral primary hip osteoarthritis undergoing total hip replacement.

PURPOSE: The study of the interrelation between hip and spine disorders is gaining increasing importance in the last years, but the link between Hip Osteoarthritis (HOA) and Low Back Pain (LBP) remains still unclear. Aim of the study is to assess the relationship between Femoral Neck Anteversion (FNA), LBP, and spinopelvic parameters in patients undergoing Total Hip Replacement (THR) for unilateral severe primary HOA. MATERIALS AND METHODS: 91 patients were recruited. Inclusion criteria were: grade 5 or 6 unilateral HOA, according to Turmezei, and Harris Hip score (HHS) <60. Exclusion criteria were: secondary hip osteoarthritis (dysplasia of the hip, rheumatoid arthritis, and ankylosing spondylitis); previous surgery of the spine, hip or knee; scoliosis with a Cobb angle greater than 10°; spondylolisthesis; history of spine fractures; previous bone tuberculosis or any spine infections; any contraindications to CT; BMI >30. Patients were divided into two homogeneous Groups according to the presence (Group-A) or not of concomitant LBP (Group-B). All patients underwent preoperatively a hip CT scan to evaluate FNA, Acetabular Anteversion (AA), and Combined Anteversion (CA = FNA + AA). ΔFNA, ΔAA and ΔCA were calculated as the differences between the arthritic hip and the normal hip angles in each Group. Full spinal X-rays in upstanding position were performed before (baseline) and 6 months after THR (follow-up) to calculate spinopelvic parameters. The health-related quality of life (HRQoL) was evaluated at baseline and at follow-up using Visual Analogue Scale (VAS), HHS, Oswestry Disability Index (ODI), Roland-Morris Disability Questionnaire (RM), and Short-Form Health Survey (SF-36). The intra-group and inter-group variability were assessed using, respectively, paired and unpaired t tests. At baseline, the association between HRQoL scores and ΔFNA, ΔAA, and ΔCA was analysed by the Pearson correlation test. RESULTS: At baseline, in Group-A, there was a significant difference between arthritic FNA and normal hip FNA, while no differences were found in AA between the two hips. A close correlation was observed between ΔFNA and Spine-VAS (r = 0.788), ODI (r = 0.824), and RM (r = 0.775). In Group-B, there was not a significant difference in FNA and AA between the two hips. At recruitment, in Group-A patients, we recorded a higher LL, SS, PI, SVA(C7), and a lower PT and T1-SPI compared with Group-B subjects. Six months after THR, in Group-A, an improvement of all clinical scores was recorded, as well as, a significant reduction of SS, LL, T1PA, and SVA(C7) and an increment of PT. In Group-B, at follow-up, an improvement of HHS, Hip-VAS, and SF-36 was recorded, while the changes in spinopelvic parameters were not significant. CONCLUSIONS: Patients with concomitant unilateral HOA and LBP showed a marked anteverted FNA in the arthritic hip and a spinopelvic misalignment. After THR, a relief of both hip and low back pain and a change in spinopelvic parameters is observed.