Current Concepts in Diagnosis and Management of Patients Undergoing Total Hip Replacement with Concurrent Disorders of Spinopelvic Anatomy: A Narrative Review

Abstract

Despite the high success rate of primary total hip replacement (THR), a significant early revision rate remains, which is largely attributed to instability and dislocations. Despite the implants being placed according to the safe zone philosophy of Lewinnek, occurrence of THR dislocation is not an uncommon complication. Large diagnostic and computational model studies have shown variability in patients' mobility based on the individual anatomic and functional relationship of the hip-pelvis-spine complex. The absolute and relative position of hip replacement components changes throughout motion of the patient's body. In the case of spinopelvic pathology such as spine stiffness, the system reaches abnormal positional states, as shown with computerized models. The clinical result of such pathologic hip positioning is edge loading, implant impingement, or even joint dislocation. To prevent such complications, surgeons must change the dogma of single correct implant positioning and take into account patients' individualized anatomy and function. It is essential to broaden the standard diagnostics and their anatomical interpretation, and correct the pre-operative surgical planning. The need for correct and personalized implant placement pushes forward the development and adaptation of novel technologies in THR, such as robotics. In this current concepts narrative review, we simplify the spinopelvic biomechanics and pathoanatomy, the relevant anatomical terminology, and the diagnosis and management algorithms most commonly used today.

Keywords: hip spine syndrome; individualized cup placement; spine stiffness; spinopelvic.

Figure 1

Lateral spinopelvic radiographs of a patient without spinal deformity with spine stiffness and anteverted pelvis (“stuck standing”) in (A) standing and (B) sitting positions with the commonly used measurements. APPt = anterior pelvic plane tilt, LL = lumbar lordosis, PI = pelvic incidence, PT = spinopelvic tilt, PFA = pelvic femoral angle, SS = sacral slope. Measured using SurgiMap^® (Nemaris Inc.^TM, New York, NY, USA).

Figure 2

Radiographic assessment of spinopelvic parameters and implant positions at early follow-up after THR. (A) Coronally, acetabular inclination and anteversion, and (B) sagittal parameters of implant positioning and spinopelvic parameters are shown in sitting and (C) standing positions. AI = acetabular anteinclination, APPt = anterior pelvic plane tilt, LL = lumbar lordosis, PI = pelvic incidence, PT = spinopelvic tilt, PFA = pelvic femoral angle, SS = sacral slope. Measured using SurgiMap^® (Nemaris Inc.^TM, NY, US).