The Direct Anterior Approach to Hip Reconstruction

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CHAPTER 14 Role of Fluoroscopic Imaging and Image Guidance

Learning Curve of Fluoroscopy The learning curve of DAA THA has been well docu mented with proficiency improving and the risk of revision decreasing over time. 22,23 Despite its utility, fluoroscopy in the DAA does retain its own learning curve before its precision improves, unlike robotic technology. 24 One study demonstrated that acetabular component accu racy improved yearly from 79.2% to 95.6% over a 3-year period. 25 The learning curve of fluoroscopy is attributed to proper understanding of pelvic tilt, pelvic rotation, visually interpreting acetabular version and inclination, and the effects of parallax and distortion. Once a surgeon is outside of this learning curve, component positioning and hip anatomy restoration results are excellent. Radiation Exposure Using fluoroscopy during a procedure that did not typ ically necessitate its use may concern some due to the risk of radiation exposure for both the patient and the surgeon. McNabb et al 26 evaluated its safety during DAA THAs. The authors used fluoroscopy during the key components of the case, with the exception of reaming the acetabulum and preparation of the femur. For the patients, entrance surface dosing of the sternal notch and pubic symphysis used as surrogates for the thyroid and gonads, respectively, were not detectable in most cases. The total radiation exposure for the patients equated to one-third of that of a standard pelvis radiograph. In addi tion, the surgeons did not experience a detectable sur face dose. Another study further looked at surgeon safety and found that it would take approximately 300,000 to 450,000 DAA THAs to reach the threshold radiation for cataract formation. 27 In general, it has been established that the use of fluoroscopy in anterior hip arthroplasty does not place unnecessary risk on either the patient or the surgeon. Conclusion Fluoroscopy is an invaluable tool that can be easily used by the anterior hip arthroplasty surgeon. Its integration into the DAA THA procedure provides salient infor mation regarding implant position, implant sizing, leg length, offset, and the presence of iatrogenic fracture. P I TFALLS ◆ Malrotation of the pelvis may occur due to traction and/ or manipulation throughout the procedure, which may result in improper assessment of acetabular component version before impaction. ◆ Fluoroscopic “illusions” such as distortion and parallax can negatively affect the interpretation of intraoperative fluoroscopic measures.

Tips and Tricks ◆ The position of the patient’s pelvis on the operating table can shift or rotate throughout the procedure, and that is why it is essential that for each step in which fluoroscopy is being used (ie, LLD, offset, cup, position), the exact AP pelvis image is replicated. ◆ It is important to remember that images are not meant as a substitute for direct visual confirmation when feasible (ie, hip reduction, inspection for interposed soft tis sue, and evaluation of the neck and calcar for fracture). Images and direct visual confirmation complement each other to avoid surprises. Take-Home Points ◆ The use of fluoroscopy in DAA THA does not place unnecessary risk on either the patient or the surgeon. ◆ Fluoroscopy and image guidance in DAA THA decrease the chances of component malposition and postopera tive surprises. REFERENCES 1. Gogia PP, Braatz JH. Validity and reliability of leg length mea surements. J Orthop Sports Phys Ther . 1986;8(4):185-188. doi:10.2519/jospt.1986.8.4.185 2. Tiberi JV, Antoci V, Malchau H, Rubash HE, Freiberg AA, Kwon YM. What is the fate of total hip arthroplasty (THA) ace tabular component orientation when evaluated in the standing position? J Arthroplasty . 2015;30(9):1555-1560. doi:10.1016/j. arth.2015.03.025 3. Mahmood SS, Mukka SS, Crnalic S, Wretenberg P, Sayed-Noor AS. Association between changes in global femoral offset after total hip arthroplasty and function, quality of life, and abductor muscle strength. A prospective cohort study of 222 patients. Acta Orthop . 2016;87(1):36-41. doi:10.3109/17453674.2015.1091955 4. Warnock JM, Karayiannis PN, Gallagher NE, Hill JC, Beverland DE. Are there gender-specific errors in restoration of hip biomechanics that affect outcome following total hip arthroplasty? J Arthroplasty . 2020;35(5):1424-1431. doi:10.1016/j.arth.2019.12.014 5. Innmann MM, Maier MW, Streit MR, et al. Additive influence of hip offset and leg length reconstruction on postoperative improve ment in clinical outcome after total hip arthroplasty. J Arthroplasty . 2018;33(1):156-161. doi:10.1016/j.arth.2017.08.007 6. Meermans G, Malik A, Witt J, Haddad F. Preoperative radio graphic assessment of limb-length discrepancy in total hip arthroplasty. Clin Orthop Relat Res . 2011;469(6):1677-1682. doi:10.1007/s11999-010-1588-x 7. Nakanowatari T, Suzukamo Y, Suga T, Okii A, Fujii G, Izumi SI. True or apparent leg length discrepancy: which is a better pre dictor of short-term functional outcomes after total hip arthro plasty? J Geriatr Phys Ther . 2013;36(4):169-174. doi:10.1519/ JPT.0b013e318282d2f1 8. Sykes A, Hill J, Orr J, et al. Patients’ perception of leg length dis crepancy post total hip arthroplasty. HIP Int . 2015;25(5):452 456. doi:10.5301/hipint.5000276

9. Piyakunmala K, Sangkomkamhang T. Measurement of patient’s perception on limb-length discrepancy compared with weight-bearing orthoroentgenography in total hip arthroplasty: a prospective study. J Arthroplasty . 2018;33(7):2301-2305. doi:10.1016/j.arth.2018.02.024 Copyright © Wolters Kluwer, Inc. Unauthorized reproduction of the content is prohibited. 2024