The Majority of Total Hip Arthroplasty Patients With a Stiff Spine Do Not Have an Instrumented Fusion

Abstract

Background: Total hip arthroplasty (THA) patients with limited lumbar flexion (LF) have increased rates of dislocation. An instrumented spinal fusion is a well-recognized cause whose risk increases with increasing number of levels fused. However, many patients without an instrumented fusion (IF) also exhibit abnormal spinopelvic mobility. The purpose of this study was to understand the proportion of THA patients without an IF that have a stiff spine (SS) and behave as if they are surgically fused. Methods: A retrospective analysis was performed on 6340 primary THA patients, all of whom had preoperative spinopelvic measurements. Any IF of the lumbar spine was observed on the lateral standing radiograph and recorded. SS was classified by LF 20 , and the percentage of patients with an IF and limited LF was determined. Results: Three hundred fifty-six (6%) patients had a SS, and only 67 (19%) had an IF. Of the entire 6340 patients, 207 (3%) had an IF. Of these 207, only 67 (32%) had a SS. Conclusions: The vast majority (81%) of THA patients with a SS do not have an IF. We recommend preoperative spinopelvic assessment of all patients undergoing THA, as only a minority of those with limited LF have an IF and may otherwise be overlooked. Lumbar degenerative disc disease is common in THA patients, limits the available LF in the same way an IF might and potentially increases the risk of dislocation in this subset of patients. Level of Evidence: III.

Applying the hip-spine relationship in total hip arthroplasty

“…Alternatively, lumbar spine stiffness resulting from degenerative disc disease, lumbar flatback deformity, or lumbar fusion decreases overall motion, and is present in around 6% of THA patients. 15,16 During relaxed sitting, a stiff lumbar spine does not straighten its lordosis and the pelvis does not tilt posteriorly. Further, some patients with stiff lumbar spines have even demonstrated more anterior pelvic tilting with flexed sitting (i.e.…”

Assessing Pelvic Tilt in Patients Undergoing Total Hip Arthroplasty Using Sensor Technology

“…Abnormal spinopelvic mobility is increasingly being recognized as a contributing factor to postoperative complications such as impingement and dislocation after total hip arthroplasty (THA). Recent studies have demonstrated the significance of the hip-spine relationship and how it affects the dynamic spine-pelvic-hip kinetic chain during movement [ [1] , [2] , [3] , [4] , [5] , [6] , [7] ]. Pathologic alterations to this coordinated motion as a result of spinopelvic stiffness have implications on functional acetabular cup positioning [ [8] , [9] , [10] , [11] ].…”

“…Assessing pelvic tilt changes with static based radiographs is important for determining optimized acetabular component positioning and orientation [ [15] , [16] , [17] , [18] ]. Posterior pelvic tilt with standing as occuring with sagittal spinal imbalance, for instance, increases functional inclination and anteversion of a cup relative to the supine position, and a posterior rotation that is large enough would take a well-positioned cup out of the LSZ [ [1] , [2] , [3] , [4] , 19 ]. Conversely, an anterior pelvic tilt when standing will decrease functional inclination and anteversion of a cup relative to supine [ [1] , [2] , [3] , [4] , 19 ].…”

“…Posterior pelvic tilt with standing as occuring with sagittal spinal imbalance, for instance, increases functional inclination and anteversion of a cup relative to the supine position, and a posterior rotation that is large enough would take a well-positioned cup out of the LSZ [ [1] , [2] , [3] , [4] , 19 ]. Conversely, an anterior pelvic tilt when standing will decrease functional inclination and anteversion of a cup relative to supine [ [1] , [2] , [3] , [4] , 19 ]. Such functional cup malorientation has been theorized to initiate a cascade of events including subluxation, edge-loading, and impingement, leading to accelerated wear, aseptic loosening, and dislocation ultimately resulting in the need for revision THA.…”

How much change in pelvic sagittal tilt can result in hip dislocation due to prosthetic impingement? A computer simulation study

“…SPT changes with spinal pathologies as well as spinal surgeries, but there is limited evidence regarding the magnitude of SPT change that can increase the risk for postoperative THA dislocation. The criteria that is known is the spinal stiffness (SPT change less than 10°) that can increase the risk of dislocation 17‐19 . The risk has been assessed by lateral lumbosacral radiographs in standing and sitting positions or advanced functional imaging techniques, such as bi‐planer radiography (EOS; EOS imaging).…”