Modification of pelvic orientation after total hip replacement in primary osteoarthritis

Poorer clinical outcomes after THA in patients with a spinal scoliotic deformity: a case-control study of 268 patients assessed with PROMS

INTRODUCTION

Spinal deformities can lead to specific complications after total hip arthroplasty (THA), such as functional leg length discrepancy due to a fixed pelvic obliquity, as well as an increased risk of prosthetic instability due to a lack of adaptive pelvic mobility, but these issues were not investigated in large comparative series. Therefore a retrospective case-control study was done aiming: 1) to analyze the impact of a preoperative scoliotic deformity on the functional outcomes of patients who underwent THA with a minimum 1-year follow-up, 2) to measure the prevalence of scoliosis in both the case and control groups 3) to screen other factors that may be correlated with poorer clinical outcomes in patients who underwent THA, including age, gender, Body Mass index (BMI), American Society of Anesthesiologists (ASA) score, primary THA etiology and postoperative complication occurrence.

HYPOTHESIS

The presence of scoliosis would have a negative impact on THA outcomes as assessed by PROMs.

MATERIALS AND METHODS

A case-control study was conducted using prospectively collected data including 268 patients who underwent THA between January 2009 and December 2021 through a direct anterior approach by the same senior surgeon. Cases were identified based on a 1-year follow-up modified Harris Hip score (mHHS) lower than 81 while controls were defined as patients with an excellent 1-year follow-up mHHS score (equal to or higher than 81). Three controls were randomly matched with each case based on the surgery period. To assess the impact of a concurrent scoliosis on clinical outcomes, a mathematical univariate and multivariate logistic model was used, including other confounding factors (age, gender, ASA score, BMI, Complication occurrence, etiology), to calculate the adjusted odds-ratio.

RESULTS

In the multivariate analysis, scoliosis was found to be a significant risk factor, with a three-fold higher adjusted odds-ratio of lower mHHS score (adjOR = 3.1; 95 CI:1.4-7, [p < 0.01]). The mean mHHS score was significantly lower in the scoliosis group compared to the non-scoliosis group (77 vs. 84 [p = 0.01]) as well as the mean Oxford Hip Score (36 vs. 43 [p < 0.001]). Among the other assessed risk factors, only the occurence of a postoperative complication was associated with an increased odds ratio of poorer mHHS scores (adjOR = 7.1; 95 CI: 2.78-18.24, [p < 0.001]). The prevalence of scoliosis in our practice was 19%.

DISCUSSION

Given the prevalence of 19% found in our study, we recommend screening for scoliosis in all patients scheduled for THA. Our results indicate that patients who had scoliosis experienced lower PROMs scores compared to those who had not. Surgeons should consider delivering this information to patients who have scoliosis undergoing THA to mitigate patient dissatisfaction.

LEVEL OF EVIDENCE

III; retrospective case-control study.

Dual-mobility with modular components for primary total hip arthroplasty in bilateral bony ankylosis of the hips: A case report

INTRODUCTION AND IMPORTANCE

Primary total hip arthroplasty (THA) is a procedure performed in the United States for a variety of indications, with operation rates slated to increase over 275 % by 2040 when compared to 2014 (Thilak et al., 2015). Dual-mobility (DM) implants have gained popularity in the United States since gaining approval in the early 2010s (Heckmann et al., 2020). It has been well reported that DM implants decrease the risk of dislocation after primary and revision THA (Vielpeau et al., 2011; Donovan et al., 2022; Heifner et al., 2023; Foissey et al., 2023; Schmidt et al., 2020; Neri et al., 2019).

CASE PRESENTATION

We present the case of a 33-year-old male with a suspected ankylosing spondylitis (AS) diagnosis and bilateral bony ankylosis of the hips who underwent staged THA with modular dual-mobility (MDM) implants. At one year post-operatively, the patient is walking without the use of an assistive device and reports a VAS pain score of 0 at rest and 2 with activity and HHS of 90.

CLINICAL DISCUSSION

Implant selection is important in this patient population due to the increased risk of dislocation. Contemporary reports reveal MDM implants have demonstrated a substantial reduction in dislocation risk compared to fixed-bearing implants in patients with a high risk of dislocation. We opted to place the acetabular component inside the safe zone to improve stability and use the dual-mobility prosthesis to achieve our desired range of motion.

CONCLUSION

The improved stability of DM implants allows for a greater range of acetabular positions in patients who have a highly unpredictable functional outcome at the time of surgery. Our preliminary results contribute to the growing list of indications for MDM total hip arthroplasty.

Ankylosing spondylitis in patients undergoing total hip arthroplasty increases the risk of medical and implant-related complications: a case control analysis

INTRODUCTION

Ankylosing spondylitis (AS) is an inflammatory spondyloarthropathy, often involving the spine and sacroiliac joints. Total hip arthroplasty (THA) has been shown to be effective in improving pain and function in patients with AS with hip involvement. However, extraskeletal manifestations and altered mechanics in those with AS leads to increased complications. Thus, the aims of this study were to assess the effects that AS has on medical and implant complications, falls, length of stay, and readmissions following THA.

METHODS

A retrospective review of the Mariner private insurance claims database was conducted from 2010 to 2020. All cases of THA and those with AS were identified using Current Procedural Terminology, and International Classification of Disease 9th and 10th revision codes. Patients who underwent THA with a diagnosis of AS were matched to non-AS patients 1:5 based on demographic and comorbidity profiles. 90-day medical complications, falls, and readmission rates, as well as 2-year implant complications were compared between cohorts.

RESULTS

A total of 6509 AS patients were matched to 32,489 control patients. The AS group had significantly higher rates of myocardial infarction, cerebrovascular accident, deep vein thrombosis, pulmonary embolism, urinary tract infection, wound complications, acute kidney injury, pneumonia, sepsis, transfusions, and falls when compared to the control group. The AS group had significantly higher rates of prosthetic joint infection, dislocation, mechanical loosening, and periprosthetic fracture (all p < 0.0001). Likewise, mean length of stay and readmissions were significantly greater in the AS group.

CONCLUSIONS

Ankylosing spondylitis in patients undergoing THA is associated with significant risk of medical and implant complications, as well as fall risk, length of stay, and readmission rates. These findings may allow orthopaedic surgeons to be more attentive in identifying those patients at risk and allow for more educated patient counseling and perioperative planning.

Spinopelvic Motion: A Simplified Approach to a Complex Subject

Knowledge of the relationship between the hip and spine is essential in the effort to minimize instability and improve outcomes following total hip arthroplasty (THA). A detailed yet straightforward preoperative imaging workup can provide valuable information on pelvic positioning, which may be helpful for optimum placement of the acetabular cup. For a streamlined preoperative assessment of THA candidates, classification systems with a capacity for providing a more personalized approach to performance of THA have been introduced. Familiarity with these systems and their clinical application is important in the effort to optimize component placement and reduce the risk of instability. Looking ahead, the principles of the hip-spine relationship are being integrated using emerging innovative technologies, promising further streamlining of the evaluation process.

Revealing the Effect of Spinopelvic Alignment on Hip Disorders

Background

Hip osteoarthritis (HOA) is a growing burden and one of the leading causes of hip pain. The relationship between the HOA and the alignment of the spinopelvic region has been intensively studied, however the issue remains controversial. Spinopelvic imbalance, HOA, and dysplasia were investigated in relation to sagittal spinopelvic parameters in this study.

Methods

We collected computerized tomography (CT) topograms of the pelvis or abdomen from 380 patients. In antero-posterior (AP) topograms, Tonnis grading, center-edge angle (CEA) and Sharp's acetabular angle (AA) measurements were performed on each patient. Lateral topograms were used to evaluate the following spinopelvic parameters for each patient: pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), sacral table angle (STA), lumbar lordosis (LL), proximal lumbar lordosis (PLL), distal lumbar lordosis (DLL), and PI-LL difference. Initially, the cohort was divided into two subgroups based on whether or not they had HOA. Then, they were divided into two subgroups based on whether or not they had dysplasia. Ultimately, it was divided in half based on the PI-LL imbalance. Statistical analyses were conducted to determine the likely correlations between the spinopelvic parameters of these subgroups. In addition, the correlations between spinopelvic parameters were investigated.

Results

There were 380 patients evaluated. We found no association between HOA or dysplasia and spinopelvic parameters. In addition, there was no association between PI-LL imbalance and HOA or dysplasia.

Conclusion

There was no difference in constant PI and STA angle, besides other variable parameters, between groups having HOA and dysplasia or not. PI-LL imbalance has no effect on HOA and dysplasia.

Lack of correlation between hip osteoarthritis and anatomical spinopelvic parameters obtained in supine position on MRI

PURPOSE

Hip osteoarthritis (HOA) is known to have a multifactorial pathogenesis. Recent studies suggest that spinopelvic alignment may represent an important additional pathogenic abnormality resulting in HOA. This study aims to assess the correlation between spinopelvic parameters (pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS) and lumbar lordosis (LL)) obtained in the supine position on MRI and HOA, lateral center edge (LCE) angle, and patient reported back pain.

METHODS

Asymptomatic participants from the whole-body MRI cohort (FF4) from the cross-sectional case-control "Cooperative Health Research in the Region of Augsburg" study (KORA) were included. Whole-body MRI was performed in a standardized fashion in each case, on which hip osteoarthritis (HOA), anatomical spinopelvic parameters and lateral center edge angle were measured. Presence of back pain was assessed using a standardized questionnaire. Correlations were estimated by logistic regression models providing odds ratio.

RESULTS

Among 340 subjects (mean age 56.3 ± 9.3 years; 56.5% male), HOA was present in 89.1% (male: 87.0%, female: 91.7%, p = 0.17). The LCE angle was 30.0° ± 5.5 (men: 29.8° ± 5.9; women: 30.1° ± 5.1; p = 0.696). Mean PI was 54.0° ± 11.3°, PT was 13.7° ± 5.9°, SS was 40.3° ± 8.8° (significantly smaller in women p<0.05) and LL was 36.4° ± 9.6° (significantly greater in women p<0.05). None of the spinopelvic parameters correlated significantly with hip osteoarthritis or LCE angle. HOA was not correlated with back pain.

CONCLUSION

Spinopelvic parameters as measured in the supine position on MRI, do not correlate with hip osteoarthritis or lateral center edge angle.

Effect of Pelvic Sagittal Tilt and Axial Rotation on Functional Acetabular Orientation

Accurate and reproducible acetabular component positioning is among the most important technical factors affecting outcomes of total hip arthroplasty. Although several studies have investigated the influence of pelvic tilt and obliquity on functional acetabular anteversion, the effect of pelvic axial rotation has not yet been established. We analyzed a generic simulated pelvis created using preoperative full-body standing and sitting radiographs. A virtual acetabulum was placed in 144 different scenarios of acetabular anteversion and abduction angles. In each scenario, the effects of pelvic tilt and pelvic axial rotation on different combinations of acetabular orientations were assessed. The change in acetabular anteversion was 0.75° for each 1° of pelvic tilt and was most linear in abduction angles of 40°±45°. The change in acetabular anteversion was 0.8° for each 1° of pelvic axial rotation. Surgeons may consider adjusting acetabular anteversion in fixed axial pelvic deformities when the degree of deformity affects functional acetabular positioning, assessed from preoperative standing and sitting weight-bearing radiographs. [Orthopedics. 2023;46(1):e27-e30.].

Does Total Hip Arthroplasty Affect Spinopelvic and Spinal Alignment?: A Prospective Observational Investigation

STUDY DESIGN

A prospective observational study, level of evidence 3.

OBJECTIVES

The study with patients undergoing unilateral total hip arthroplasty (THA) aimed to evaluate the following hypotheses: (1) the spinal sagittal and coronal alignment alters due to THA, (2) the spinopelvic parameter changes after THA, (3) the spinopelvic alignment differs between sagittal balanced and imbalanced patients.

SUMMARY OF BACKGROUND DATA

Surgical correction of spinal sagittal misalignment affects the spinopelvic alignment and pelvic tilt. It is not yet known to what extent THA affects spinopelvic, spinal sagittal, and coronal alignment.

MATERIALS AND METHODS

A total of 153 patients undergoing THA were assessed with biplanar stereoradiography in standing position preoperatively and postoperatively. Two independent investigators examined C7-sagittal vertical axis (C7-SVA), pelvic incidence-lumbar lordosis (PI-LL) mismatch, lumbar lordosis (LL), C7-central sacral vertical line, pelvic oblique angle lumbosacral, intra-pelvic oblique angle, pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), anterior plane pelvic tilt (APPT), and pelvic femoral angle (PFA). An analysis of the sagittal misaligned subgroups of C7-SVA and PI-LL on the influence of the spinopelvic alignment was performed.

RESULTS

A significant difference in spinopelvic parameters was detected in the preoperative to postoperative comparison (SS, PT, APPT, and PFA; P <0.000) ( d =-0.394; d =0.609; d =-0.481; d =0.431). The coronal alignment and pelvic obliquity revealed no significant differences. The misaligned groups (C7-SVA; PI-LL) demonstrated significant increases in PI and PT and decreased in LL compared with the groups with normal sagittal alignment. Preoperatively, 66/153 (C7-SVA) and 46/153 (PI-LL) of the THA patients presented sagittal misalignment, respectively.

CONCLUSIONS

The results suggest an effect of THA on sagittal spinal and spinopelvic alignment, with a significant reduction of PT postoperatively and no effect on coronal alignment. Particularly striking are the significant differences in the misaligned groups, which may be classified as risk population and potentially can contribute biomechanically to a higher risk of posterior impingement and anterior THA dislocation. The substantial proportion of sagittal misaligned patients in the THA collective illustrates the crucial need for interdisciplinary collaboration.

Does spinopelvic motion change after total hip arthroplasty?

PURPOSE

Spinopelvic motion plays an important role in functional acetabular cup position after total hip arthroplasty (THA). Sacral slope (SS) has been a useful surrogate for spinopelvic motion. The present study aimed to investigate statistical characteristics of spinopelvic motion before and after THA using changes in SS in supine, standing, and sitting positions.

METHODS

A total of 76 patients (88 hips) were assessed. To classify spinopelvic mobility, defined as a change in SS from standing to sitting position (ΔSS_stand/sit), 10° ≤ ΔSS_stand/sit ≤ 30°, ΔSS_stand/sit < 10°, and ΔSS_stand/sit > 30° were considered normal, stiff, and hypermobile, respectively.

RESULTS

Over ± 7° changes in SS between before and one year after THA were observed in 39 (44.3%) hips in the sitting position, 19 (21.6%) hips in the supine position, seven (7.9%) in the standing position. Percentages of hips with stiff spinopelvic mobility (11.4% vs. 22.7%) and hypermobile spinopelvic mobility (23.9% vs. 12.5%) between before THA and one year after THA were significantly different (p = 0.034 and p = 0.016, McNemar's test). At one year after THA, 40.0% (4/10) of hips with stiff spinopelvic mobility and 57.1% (12/21) of hips with hypermobile spinopelvic mobility shifted to normal spinopelvic mobility.

CONCLUSIONS

Change in SS between before THA and one year after THA had a high inter-subject variability especially in the sitting position. In addition, there was a distinct shift to normal spinopelvic mobility postoperatively in hips with stiff and hypermobile spinopelvic mobility pre-operatively.

Ankylosing Spondylitis Patients Have Lower Risk of Dislocation Following Total Hip Arthroplasty Compared with Patients Undergoing Lumbar Spinal Fusion Surgery

Purpose

Patients undergoing lumbar spinal fusion (LSF) surgery and patients with ankylosing spondylitis (AS) have concomitant pathology of hip and lumbosacral spine. The purpose of our study is to compare the dislocation rate following total hip arthroplasty (THA) between patients with LSF and AS and reveal the differences of lumbar fusion secondary to LSF and AS.

Patients and methods

Fifty-nine patients (73 hips) were included in Group LSF and every patient was matched with two patients in Group AS. Follow-ups were conducted for information of surgical prognosis and dislocation events following THA. Multiple anatomic parameters were measured on preoperative and postoperative radiological images.

Results

The dislocation rate of patients in Group AS (0.68%) was obviously lower than that of patients in Group LSF (4.11%) and the hazard ratio of dislocation events following THA reached 6.1. Considering the low calculated power (1-β, 0.24), we supposed insufficient statistical evidence (p=0.118) could be attributed to small sample size. Postoperative hip flexion range of motion (ROM) in Group AS (102.1°±24.5°) was significantly lower than that in Group LSF (117.4°±14.2°) (p<0.0005). Postoperative flexion ROM of lumbar was also significantly lower in Group AS (p<0.001). There was no significant difference between two groups concerning postoperative acetabular inclination (p=0.988) and anteversion (p=0.25). However, patients in Group AS had a significantly lower sacral slope (p=0.025) and higher pelvic tilt (p<0.0005) than patients in Group LSF after THA.

Conclusion

Patients with AS have a lower risk of dislocation after THA compared with patients undergoing LSF. The lower risk is significantly relevant to severer stiffness and lower mobility along the spine-pelvis--hip axis in AS patients after THA. Acetabular orientation has no significant effect on the difference of dislocation rate between patients with LSF and AS.

Abnormal spinopelvic mobility as a risk factor for acetabular placement error in total hip arthroplasty using optical computer-assisted surgical navigation system

Aims

Navigation devices are designed to improve a surgeon’s accuracy in positioning the acetabular and femoral components in total hip arthroplasty (THA). The purpose of this study was to both evaluate the accuracy of an optical computer-assisted surgery (CAS) navigation system and determine whether preoperative spinopelvic mobility (categorized as hypermobile, normal, or stiff) increased the risk of acetabular component placement error.

Methods

A total of 356 patients undergoing primary THA were prospectively enrolled from November 2016 to March 2018. Clinically relevant error using the CAS system was defined as a difference of > 5° between CAS and 3D radiological reconstruction measurements for acetabular component inclination and anteversion. Univariate and multiple logistic regression analyses were conducted to determine whether hypermobile ([Formula: see text]sacral slope(SS)stand-sit > 30°), or stiff ([Formula: see text]SSstand-sit < 10°) spinopelvic mobility contributed to increased error rates.

Results

The paired absolute difference between CAS and postoperative imaging measurements was 2.3° (standard deviation (SD) 2.6°) for inclination and 3.1° (SD 4.2°) for anteversion. Using a target zone of 40° (± 10°) (inclination) and 20° (± 10°) (anteversion), postoperative standing radiographs measured 96% of acetabular components within the target zone for both inclination and anteversion. Multiple logistic regression analysis controlling for BMI and sex revealed that hypermobile spinopelvic mobility significantly increased error rates for anteversion (odds ratio (OR) 2.48, p = 0.009) and inclination (OR 2.44, p = 0.016), whereas stiff spinopelvic mobility increased error rates for anteversion (OR 1.97, p = 0.028). There were no dislocations at a minimum three-year follow-up.

Conclusion

Despite high reliability in acetabular positioning for inclination in a large patient cohort using an optical CAS system, hypermobile and stiff spinopelvic mobility significantly increased the risk of clinically relevant errors. In patients with abnormal spinopelvic mobility, CAS systems should be adjusted for use to avoid acetabular component misalignment and subsequent risk for long-term dislocation. Cite this article: Bone Jt Open 2022;3(6):475–484.

Hip-spine relationship in total hip arthroplasty - Simplifying the concepts

Total hip arthroplasty (THA) has been described as the operation of the century. Despite significant advancement in the field of technology, hip instability remains second most common cause of revision hip surgery after infection. There is garning interest to identify role of hip-spine relationship in order to identify high-risk patients for instability after THA. Acetabular component position varies according to spinal alignment and mobility in order to decrease risk of impingement and instability. Preoperative work up includes standing pelvis anteroposterior radiograph and lateral spino-pelvic radiograph in standing and sitting position. The focus of this review is to develop an algorithm to address the spino-pelvic pathology and guide the treatment on the basis of sagittal movement of the spine-pelvis-hip complex and to minimise the rate of dislocation following THA.

Preoperative spinopelvic hypermobility resolves following total hip arthroplasty

AIMS

Spinopelvic mobility plays an important role in functional acetabular component position following total hip arthroplasty (THA). The primary aim of this study was to determine if spinopelvic hypermobility persists or resolves following THA. Our second aim was to identify patient demographic or radiological factors associated with hypermobility and resolution of hypermobility after THA.

METHODS

This study investigated patients with preoperative posterior hypermobility, defined as a change in sacral slope (SS) from standing to sitting (ΔSS_stand-sit) ≥ 30°. Radiological spinopelvic parameters, including SS, pelvic incidence (PI), lumbar lordosis (LL), PI-LL mismatch, anterior pelvic plane tilt (APPt), and spinopelvic tilt (SPT), were measured on preoperative imaging, and at six weeks and a minimum of one year postoperatively. The severity of bilateral hip osteoarthritis (OA) was graded using Kellgren-Lawrence criteria.

RESULTS

A total of 136 patients were identified as having preoperative spinopelvic hypermobility. At one year after THA, 95% (129/136) of patients were no longer categorized as hypermobile on standing and sitting radiographs (ΔSS_stand-sit < 30°). Mean ΔSS_stand-sit decreased from 36.4° (SD 5.1°) at baseline to 21.4° (SD 6.6°) at one year (p < 0.001). Mean SS_seated increased from baseline (11.4° (SD 8.8°)) to one year after THA by 11.5° (SD 7.4°) (p < 0.001), which correlates to an 8.5° (SD 5.5°) mean decrease in seated functional cup anteversion. Contralateral hip OA was the only radiological predictor of hypermobility persisting at one year after surgery. The overall reoperation rate was 1.5%.

CONCLUSION

Spinopelvic hypermobility was found to resolve in the majority (95%) of patients one year after THA. The increase in SS_seated was clinically significant, suggesting that current target recommendations for the hypermobile patient (decreased anteversion and inclination) should be revisited. Cite this article: Bone Joint J 2021;103-B(12):1766-1773.

Primary Total Hip Arthroplasty in Patients With Ankylosing Spondylitis

BACKGROUND

Ankylosing spondylitis (AS) is a common inflammatory spondyloarthropathy with hip involvement in 40% of patients. With the renewed interest in the hip-spine interplay, this study aimed to define long-term outcomes of primary total hip arthroplasty (THA) in the setting of AS.

METHODS

We identified 309 hips (219 patients) with AS treated with primary THA from 1969 to 2018. Mean age was 49 years, 80% were males, and mean body mass index was 28 kg/m². Cumulative incidences of any revision, reoperation, and dislocation were calculated utilizing a competing risk analysis. Harris Hip Scores and complications were also reported. Mean follow-up was 16 years.

RESULTS

The cumulative incidence of any revision after primary THA was 2.3% at 5 years and 17.5% at 20 years. The most common reasons for revision (n = 73) were aseptic loosening (41%), osteolysis/polyethylene (PE) wear (30%, all with conventional PE), and femoral component fracture (8%). The cumulative incidence of dislocation was 1.9% at 5 years and 2.9% at 20 years. Younger age was associated with increased risk of revision (hazard ratio (HR) = 1.3, P < .01) and reoperation (HR = 1.2, P < .01), but not dislocation (HR = 0.7, P = .1). Twenty-eight hips (9%) experienced a postoperative complication not requiring reoperation. The mean Harris Hip Score improved from 51 to 76 after THA (P < .001).

CONCLUSION

In this series of 309 primary THAs in patients with AS, the 20-year cumulative incidence of any revision after primary THA was 17.5%. Aseptic loosening, osteolysis/PE wear, and femoral component fracture were the most common reasons for revision. Notably, the cumulative incidence of dislocation at 20 years was only 2.9%.

LEVEL OF EVIDENCE

Level IV.

Variability of pelvic axial rotation in patients undergoing total hip arthroplasty

BACKGROUND

Pelvic axial rotation affects the functional orientation of an acetabular component. Every 1° of axial rotation changes functional acetabular anteversion by 1°. There is limited information on pelvic rotation in THA patients, since it is difficult to measure on routine radiographs. Therefore, we used spine-to-ankle biplanar radiography to investigate variability in pelvic rotation in patients before and after THA.

METHODS

In 156 patients undergoing primary unilateral THA, we measured preoperative, 6 weeks and 1 year postoperative pelvic rotation in both standing and sitting positions using a biplanar radiography system. Patients with fixed pelvic rotation had a similar magnitude and direction of pelvic rotation in all standing or sitting images. We further identified patients with position-independent or position-dependent fixed pelvic rotation.

RESULTS

Pelvic rotation was common in THA patients, with 82 patients (53% of 156 patients) having at least 1 image with > 7° of rotational deformity. 12 patients (8% of 156 patients) had fixed rotation, 6 patients (4%) had position-independent fixed axial rotation and 6 patients (4%) had position-dependent fixed axial rotation.

CONCLUSIONS

It may be important to recognise whether a THA patient has a fixed pelvic axial rotational deformity, where 1 hip is consistently forward or backward in functional imaging. Fixed rotation will increase or decrease the functional anteversion of an acetabular component depending on THA side. Further research might better characterise associations and predictors of fixed axial rotation and its impact on patient outcomes after THA.

Sagittal spinal-pelvic alignment in patients with Crowe type IV developmental dysplasia of the hip

BACKGROUND

The impact of high dislocated dysplastic hips on spinal-pelvic alignment has not been well described. This study aims to evaluate compensatory spinal radiographic changes and presence of back pain in patients with Crowe type IV developmental dysplasia of the hip (DDH).

METHODS

An observational study was conducted from July 2016 to December 2017, and 49 consecutive patients with Crowe IV DDH were enrolled. Forty-nine sex- and age-matched asymptomatic healthy adults were recruited as the controls. The sacral slope (SS), lumbar lordosis (LL), spino-sacral angle (SSA), C7 tilt (C7T), and sagittal vertical axis (SVA [C7]) were measured on lateral whole spine radiographs. The presence of low back pain and visual analogue scale (VAS) scores were recorded.

RESULTS

The patients with Crowe IV DDH showed significantly greater SS (47.5 ± 7.5° vs. 40.4 ± 6.7°, p < 0.05), LL (- 63.7 ± 9.2° vs. - 53.3 ± 11.5°, P < 0.05), SSA (141.8° ± 7.2° vs. 130.6 ± 7.9°, p < 0.05), C7T (93.9 ± 3.6° vs. 91.1 ± 3.7°, P < 0.05), and lower SVA(C7) (- 16 mm[- 95-45] vs. 6.4 mm[- 52-47], p < 0.05) compared to the controls. The patients with bilateral Crowe IV DDH also exhibited larger SS, LL, SSA, and C7T and a smaller SVA (C7) than those with unilateral Crowe IV DDH. Sixty-three percent of the patients with Crowe IV DDH reported low back pain.

CONCLUSION

The patients with Crowe IV DDH exhibited abnormal spinal-pelvic alignment characterized by anterior pelvic tilt, lumbar hyperlordosis, and a backward-leaning trunk. Bilateral Crowe IV DDH had a greater impact on spinal-pelvic alignment than unilateral Crowe IV DDH.

Avaliação dos parâmetros radiográficos do alinhamento sagital e espinopélvico em pacientes com osteoartrite submetidos à artroplastia total do quadril

Objective  To evaluate radiographic parameters of sagittal and spinopelvic alignment in patients with hip osteoarthritis (OA) undergoing primary total hip arthroplasty (THA) to define the primary surgical approach in individuals with concomitant spinal and hip joint disease.

Methods  Longitudinal, prospective, comparative study with 27 patients undergoing THA and 43 subjects without OA.

Results  An association between hip and spine degenerative disease in patients with OA was noted. After THA, radiographic parameters of pelvic tilt angle, sagittal vertical axis (EVS) and seventh cervical vertebra/sacrofemoral distance (C7/DSF) ratio were similar to values from volunteers without joint disease. Global coronal alignment (ACG), sagittal alignment, spinopelvic T1 and T9 tilts (IT1EP and IT9EP), sacral tilt (IS), pelvic version (VP), pelvic type and lumbopelvic complex (CLP) did not change after THA.

Conclusion  Among the sagittal and spinopelvic alignment parameters evaluated, the pelvic tilt angle, the EVS, and the C7/DSF ratio were corrected after THA and can guide the surgeon in the decision-making process for patients with concomitant spinal and hip joint disease. Spinal deformity may compensate for hip changes.

Revision Total Hip Arthroplasty in Patients With Ankylosing Spondylitis: Long-Term Results

BACKGROUND

Ankylosing spondylitis (AS) is a common inflammatory spondyloarthropathy with hip involvement in 40% of patients. With the recent interest in the hip-spine interplay, the purpose of this study was to define the long-term outcomes of revision total hip arthroplasty (THA) in the setting of AS.

METHODS

174 hips in patients with AS treated with revision THA from 1969 to 2016 were identified. Mean age at revision THA was 53 years and 76% were male. Cumulative incidences of any re-revision, reoperation, and dislocation were calculated using a competing risk analysis. Mean follow-up was 13 years.

RESULTS

The cumulative incidence of any re-revision after index revision THA was 7% at 5 years and 36% at 20 years. Cumulative incidence of any reoperation was 9% at 5 years and 38% at 20 years. Cumulative incidence of dislocation was 6% at 5 years and 8% at 20 years. Revision THAs performed with contemporary implants (2000-2016) had a lower but statistically nonsignificant cumulative incidence of any re-revision when compared with historical implants (before 2000) at 5 years (5% vs 8%), 10 years (11% vs 18%), and 15 years (11% vs 38%) (hazard ratio, 0.47; 95% confidence interval, 0.17-1.33; P = .016).

CONCLUSION

In this large series of 174 revision THAs in patients with AS, the cumulative incidence of dislocation was 8% at 20 years. The 20-year cumulative incidence of any re-revision was 36%, which is similar to reported rates in patients with comparable demographic features without AS.

LEVEL OF EVIDENCE

Level IV.

[Hip-spine syndrome-current developments and state of the evidence]

The movements between the spine, pelvis and hip joints are coordinated to allow for a physiological balance of the upper body and the pelvis during sitting and standing. Degenerative changes or spondylodesis of the spine result in decreased pelvic mobility and can lead to increased rates of instability in the presence of total hip arthroplasty (THA). To reduce the risk of THA dislocation several authors have recently recommended functional radiographs of the spine and pelvis, as well as individual safe zones for THA components. The aim of this article is to summarize the current body of knowledge regarding the influence of spinopelvic alignment on THA and provide recommendations for everyday clinical practice.

The Impact of Spinopelvic Mobility on Arthroplasty: Implications for Hip and Spine Surgeons

Spinopelvic mobility represents the complex interaction of hip, pelvis, and spine. Understanding this interaction is relevant for both arthroplasty and spine surgeons, as a predicted increasing number of patients will suffer from hip and spinal pathologies simultaneously. We conducted a comprehensive literature review, defined the nomenclature, summarized the various classifications of spinopelvic mobility, and outlined the corresponding treatment algorithms. In addition, we developed a step-by-step workup for spinopelvic mobility and total hip arthroplasty (THA). Normal spinopelvic mobility changes from standing to sitting; the hip flexes, and the posterior pelvic tilt increases with a concomitant increase in acetabular anteversion and decreasing lumbar lordosis. Most classifications are based on a division of spinopelvic mobility based on ΔSS (sacral slope) into stiff, normal, and hypermobile, and a categorization of the sagittal spinal balance regarding pelvic incidence (PI) and lumbar lordosis (LL) mismatch (PI–LL = ± 10° balanced versus PI–LL > 10° unbalanced) and corresponding adjustment of the acetabular component implantation. When performing THA, patients with suspected pathologic spinopelvic mobility should be identified by medical history and examination, and a radiological evaluation (a.p. pelvis standing and lateral femur to L1 or C7 (if EOS (EOS imaging, Paris, France) is available), respectively, for standing and sitting radiographs) of spinopelvic parameters should be conducted in order to classify the patient and determine the appropriate treatment strategy. Spine surgeons, before planned spinal fusion in the presence of osteoarthritis of the hip, should consider a hip flexion contracture and inform the patient of an increased risk of complications with existing or planned THA.

The Influence of Pelvic Tilt on the Anteversion Angle of the Acetabular Prosthesis

The concept of the "safe area" of the acetabular prosthesis has a long history and has been recognized by many scholars. It is generally believed that postoperative hip dislocation rate is low, when the acetabular anteversion angle is placed in the range of 15° ± 10°. Despite this, hip dislocation is a common complication after total hip arthroplasty. In recent years, more and more scholars have paid attention to the influence of pelvic tilt on the acetabular anteversion angle. The concept of acetabular anteversion changes as the pelvic tilt changes, and is challenging the traditional acetabular prosthesis "safe area." This study summarized the potential influencing factors of pelvic tilt and discussed the influence of the phenomenon on the anteversion angle of total hip arthroplasty (THA) acetabular prosthesis based on the literature review. We conclude that from the supine position to standing, followed by sitting, the pelvis tends to move backward. Pelvic sagittal activity, lumbar disease (ankylosing spondylitis), lumbar fusion (lumbar fusion, spine-pelvic fusion), and other factors related to the tilt are THA risk factors for postoperative dislocation and revision. With the change of body position, the degree of acetabular anteversion is directly related to the degree of pelvic tilt. The acetabular anteversion varies greatly, which leads to increased hip prosthesis wear and even hip dislocation. The lateral X-ray of the spine and pelvis is recommended in supine, standing, and sitting positions before THA. In addition, the pelvic tilt should be regarded as a reference of the acetabular prosthesis in the preoperative planning of THA.

Risk factors for increased sagittal pelvic motion causing unfavourable orientation of the acetabular component in patients undergoing total hip arthroplasty

Aims

It is important to consider sagittal pelvic rotation when introducing the acetabular component at total hip arthroplasty (THA). The purpose of this study was to identify patients who are at risk of unfavourable pelvic mobility, which could result in poor outcomes after THA.

Patients and Methods

A consecutive series of 4042 patients undergoing THA had lateral functional radiographs and a low-dose CT scan to measure supine pelvic tilt, pelvic incidence, standing pelvic tilt, flexed-seated pelvic tilt, standing lumbar lordotic angle, flexed-seated lumbar lordotic angle, and lumbar flexion. Changes in pelvic tilt from supine-to-standing positions and supine-to-flexed-seated positions were determined. A change in pelvic tilt of 13° between positions was deemed unfavourable as it alters functional anteversion by 10° and effectively places the acetabular component outside the safe zone of orientation.

Results

For both men and women, the degree of lumbar flexion was a significant predictor of risk in hip flexion (p < 0.0001) with increased odds of unfavourable pelvic mobility in those with lumbar flexion of < 20° (men, odds ratio (OR) 6.74, 95% confidence interval (CI) 3.83 to 11.89; women, OR 2.97, 95% CI 1.87 to 4.71). In women, age and standing pelvic tilt were significant predictors of risk in hip extension (p = 0.0082 and p < 0.0001, respectively). The risk of unfavourable pelvic mobility was higher in those aged > 75 years (OR 2.28, 95% CI 1.56 to 3.32) and those with standing pelvic tilt of < -10° for extension risk (OR 7.10, 95% CI 4.10 to 10.29). In men, only standing pelvic tilt was significant (p < 0.0001) for hip extension with an increased risk of unfavourable pelvic mobility (OR 8.68, 95% CI 5.19 to 14.51).

Conclusion

Patients found to have unfavourable pelvic mobility had limited lumbar flexion and more posterior standing pelvic tilt in both men and women, as well as increasing age in women. We recommend that patients undergo preoperative functional radiographic screening to determine specific parameters that can affect the functional orientation of the acetabular component. Cite this article: Bone Joint J 2018;100-B:845–52.

Pelvic incidence and hip disorders

Background and purpose - The role of pelvic incidence in hip disorders is unclear. Therefore, we undertook a literature review to evaluate the evidence on that role. Methods - A search was carried out on MEDLINE, SCOPUS, CENTRAL, and CINAHL databases. Quantitative analysis was based on comparison with a reference population of asymptomatic subjects. Results - The search resulted in 326 records: 15 studies were analyzed qualitatively and 13 quantitatively. The estimates of pelvic incidence varied more than 10 degrees from 47 (SD 3.7) to 59 (SD 14). 2 studies concluded that higher pelvic incidence might contribute to the development of coxarthrosis while 1 study reported the opposite findings. In 2 studies, lower pelvic incidence was associated with a mixed type of femoroacetabular impingement. We formed a reference population from asymptomatic groups used or cited in the selected studies. The reference comprised 777 persons with pooled average pelvic incidence of 53 (SD 10) degrees. The estimate showed a relatively narrow 95% CI of 52 to 54 degrees. The 95% CIs of only 4 studies did not overlap the CIs of reference: 2 studies on coxarthrosis, 1 on mixed femoroacetabular impingement, and 1 on ankylosing spondylitis Interpretation - We found no strong evidence that pelvic incidence plays any substantial role in hip disorders. Lower pelvic incidence may be associated with the mixed type of femoroacetabular impingement and hip problems amongst patients with ankylosing spondylitis. The evidence on association between pelvic incidence and coxarthrosis remained inconclusive.

Reproducibility of length measurements of the lower limb by using EOS™

BACKGROUND

Lower-limb discrepancy following total hip arthroplasty is the third-most common reason for patient dissatisfaction in orthopaedic surgery. Therefore, accurate planning and evaluation methods are mandatory. The main aim of this study was to evaluate the reliability of the EOS™ system by establishing and comparing the reproducibility of lower-limb automatic and manual 3D measurements. We hypothesized that the reproducibility of the lower-limb measurements is similar regardless of the method used and with an agreement higher than 0.95 for the length parameters.

MATERIALS AND METHODS

This study utilized an EOS radiological database of 112 patients. Two independent observers performed two rounds of lower-limb measurements twice, either in manual 3D or automatic 3D mode. The intra- and inter-observer reproducibility was evaluated by the calculation of the intra-class coefficient for each measurement method. The methods were then compared.

RESULTS

The intra- and inter-observer reproducibility for length measurements found with the manual and automatic 3D methods was always > 0.98. There was no significant difference in the reproducibility between the two measurement modes, with the exception of the offset, hip-knee-shaft, and neck-shaft angles.

CONCLUSION

Our results indicate a very good reproducibility of EOS™ length measurement, regardless of the method used. Automated 3D mode is preferred for the collection of angular and offset measurements. Furthermore, manual mode measurements are not affected by surgical history. Level of evidence IV.

Ankylosing Spondylitis Increases Perioperative and Postoperative Complications After Total Hip Arthroplasty

BACKGROUND

Ankylosing spondylitis (AS) is a chronic autoimmune spondyloarthropathy that primarily affects the axial spine and hips. Progressive disease leads to pronounced spinal kyphosis, positive sagittal balance, and altered biomechanics. The purpose of this study is to determine the complication profile of patients with AS undergoing total hip arthroplasty (THA).

METHODS

The Medicare sample was searched from 2005 to 2012 yielding 1006 patients with AS who subsequently underwent THA. Risk ratios (RRs) with 95% confidence intervals (CIs) were calculated for 90-day, 2-year, and the final postoperative follow-up for complications including hip dislocation, periprosthetic fracture, wound complication, revision THA, and postoperative infection.

RESULTS

Compared to controls, AS patients had an RR of 2.50 (CI, 1.04-5.99) of THA component breakage at 90-days post-operatively and 1.99 (CI, 1.10-3.59) at 2-years. The RR of periprosthetic hip dislocation was elevated at 90 days (1.44; CI, 0.93-2.22) and significantly increased at 2-years (1.67; CI, 1.25-2.23) and overall follow-up (1.49; CI, 1.14-1.93). Similarly, the RR for THA revision was elevated at 90-days (1.46; CI, 0.97-2.18) and significantly increased at 2-years (1.69; CI, 1.33-2.14) and overall follow-up (1.51; CI, 1.23-1.85).

CONCLUSION

Patients with AS are at increased risk for complications after THA. Altered biomechanics from a rigid, kyphotic spine place increased demand on the hip joints. The elevated perioperative and postoperative risks should be discussed preoperatively, and these patients may require increased preoperative medical optimization as well as possible changes in component selection and position to compensate for altered spinopelvic biomechanics.

The Impact of Lumbar Spine Disease and Deformity on Total Hip Arthroplasty Outcomes

Concomitant spine and hip disease in patients undergoing total hip arthroplasty (THA) presents a management challenge. Degenerative lumbar spine conditions are known to decrease lumbar lordosis and limit lumbar flexion and extension, leading to altered pelvic mechanics and increased demand for hip motion. In this study, the effect of lumbar spine disease on complications after primary THA was assessed. The Medicare database was searched from 2005 to 2012 using International Classification of Diseases, Ninth Revision, procedure codes for primary THA and diagnosis codes for preoperative diagnoses of lumbosacral spondylosis, lumbar disk herniation, acquired spondylolisthesis, and degenerative disk disease. The control group consisted of all patients without a lumbar spine diagnosis who underwent THA. The risk ratios for prosthetic hip dislocation, revision THA, periprosthetic fracture, and infection were significantly higher for all 4 lumbar diseases at all time points relative to controls. The average complication risk ratios at 90 days were 1.59 for lumbosacral spondylosis, 1.62 for disk herniation, 1.65 for spondylolisthesis, and 1.53 for degenerative disk disease. The average complication risk ratios at 2 years were 1.66 for lumbosacral spondylosis, 1.73 for disk herniation, 1.65 for spondylolisthesis, and 1.59 for degenerative disk disease. Prosthetic hip dislocation was the most common complication at 2 years in all 4 spinal disease cohorts, with risk ratios ranging from 1.76 to 2.00. This study shows a significant increase in the risk of complications following THA in patients with lumbar spine disease. [Orthopedics. 2017; 40(3):e520-e525.].

Comparison of Three-Dimensional Planning-Assisted and Conventional Acetabular Cup Positioning in Total Hip Arthroplasty: A Randomized Controlled Trial

BACKGROUND

Malpositioning of the acetabular cup during total hip arthroplasty increases the risk of dislocation, edge-loading, squeaking, early wear, and loosening. We hypothesized that the use of three-dimensional (3-D) visualization tools to identify the planned cup position relative to the acetabular edge intraoperatively would increase the accuracy of cup orientation. The purpose of this study was to compare 3-D planning-assisted implantation and freehand insertion of the acetabular cup.

METHODS

This was a prospective randomized controlled study of two groups of twenty-eight patients each. In the first group, cup positioning was guided by 3-D views of the cup within the acetabulum obtained during 3-D preoperative planning. In the control group, the cup was placed freehand. All of the patients were operated on by the same surgeon, through a minimally invasive direct anterior approach with the patient in the supine position. Cup anteversion and abduction angles were measured on 3-D computed tomography (CT) reconstructions. The main evaluation criterion was the percentage of outliers according to the Lewinnek safe zone.

RESULTS

Operative time did not differ between the two groups. The cup anteversion was more accurate in the 3-D planning group (mean difference from the planned angle [and standard deviation], -2.7° ± 5.4°) compared with the freehand-placement group (6.6° ± 9.5°). According to the Lewinnek safe zone, overall, the percentage of outliers was lower in the 3-D planning group (21%; six patients) than in the control group (46%; thirteen patients). According to the Callanan safe zone, the percentage of outliers was also lower in the 3-D planning group (25% versus 64%). Although cup abduction was also restored with greater accuracy in the 3-D planning group, on the basis of the Lewinnek safe zone, the percentage of abduction outliers was comparable between groups, with fewer high-abduction values, but more low-abduction values, in the 3-D planning group.

CONCLUSIONS

Preoperative 3-D planning increased the accuracy of anteversion restoration and reduced the percentage of outliers without increasing the operative time. In this study, the same advantage could not be demonstrated for abduction.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

The Impact of Lumbar Spine Disease and Deformity on Total Hip Arthroplasty Outcomes

Concurrent spine and hip disease is common. Spinal deformities can restrict lumbar range of motion and lumbar lordosis, leading to pelvic obliquity and increased pelvic tilt. A comprehensive preoperative workup and component templating ensure appropriate compensation for altered pelvic parameters for implantation of components according to functional positioning. Pelvic obliquity from scoliosis must be measured to calculate appropriate leg length. Cup positioning should be templated on standing radiograph to limit impingement from cup malposition. In spinal deformity, the optimal position of the cup that accommodates pelvic parameters and limits impingement may lie outside the classic parameters of the safe zone.

Total Hip Prostheses in Standing, Sitting and Squatting Positions: An Overview of Our 8 Years Practice Using the EOS Imaging Technology

More total hip arthroplasty (THA) is performed worldwide and especially in younger and more active patients compared to earlier decades. One of the focuses of THA research in the future will be on optimizing the radiological follow-up of these patients using 2D and 3D measurements of implants position while reducing the radiation dose delivered.

Low-dose EOS^® imaging is an innovative slot-scanning radiograph system providing valuable information in patient functional positions (standing, sitting and even squatting positions). EOS has been proven accurate and reliable without significant inconvenience caused by the metallic artifacts of implants. The ability to obtain precise data on implant orientation according to the patient posture opens new perspectives for a comprehensive analysis of the pelvic frontal and sagittal balance and its potential impact on implants function and failures.

We report our 8 years experience on our first 300 THA patients using this technology routinely for pre and post op evaluation. Our results will be compared and confronted with the actual literature about this innovative technology. We shall especially emphasize our experience about patients with abnormal posture and the evolution of the subject over time, because the phenomenon of an aging spine is frequently associated with the process of aging hips.

Characteristics of sagittal spine-pelvis-leg alignment in patients with severe hip osteoarthritis

PURPOSE

The interaction between the sagittal alignment of the spine and pelvis and the compensatory mechanism in patients suffering from spinal disorders has been well documented. However, in patients with hip osteoarthritis (HOA), few studies have explored how the hip joint pathology could affect the sagittal alignment of the hip, pelvis and spine, and no reports have investigated whether these changes are involved in the pathogenesis of low back pain in these patients. The aims of this case-control study were to investigate the sagittal spine-pelvis-leg alignment in patients suffering from severe HOA and to understand whether the alignment was related to the occurrence of low back pain and the health-related quality of life in these patients.

METHODS

Fifty-eight patients with severe HOA and 64 asymptomatic controls were studied. Digital lateral X-rays of the spine, pelvis and proximal femur were obtained with the patients placed in upright positions. The following radiographic parameters were measured to examine the sagittal alignment of the pelvis, hip and spine: pelvic incidence (PI), pelvic tilting (PT), sacral slope (SS), pelvic femoral angle (PFA), femoral inclination (FI), lumbar lordosis (LL), spino-sacral angle (SSA), C7 tilt (C7T) and T1 spinal-pelvic inclination (T1-SPI). The global balance patterns of spinal-pelvic alignment were classified as normal balance, slight unbalance and severe unbalance according to the relative position of the C7 plumb line to the sacrum and femoral heads. Short Form-36 questionnaire was carried out in the patients. Comparisons were carried out between the patients with HOA and the controls and between the HOA patients with or without low back pain. Correlation analysis was used to measure relationships between the HOA patients' parameters.

RESULTS

There were no significant differences in the age and gender distribution between the HOA patients and control. Compared with the controls, the patients with HOA showed significantly higher SS and lower PT, similar PI in the pelvis, significantly smaller C7T, larger T1-SPI but comparable LL and SSA in the spine, and significantly smaller PFA but larger FI in the hip joint. In addition, the patients with HOA had a significantly greater incidence of severe unbalanced spinal-pelvic alignment than did the controls (22.4 vs 3.1 %, respectively). In patients with HOA, the PFA was significantly correlated with SS, SSA and FI but not with PI, LL or C7T; while the physical component score of short form-36 was significantly correlated with T1-SPI, C7T and FI. A comparison between the HOA patients with or without low back pain, however, showed no significant differences in the radiographic parameters, global sagittal balance patterns and Short Form-36.

CONCLUSIONS

The sagittal morphology of the pelvis in patients with severe HOA was normal and might not be involved in the development and progression of this disorder. Although the whole spine was involved in compensating for the flexed hip joint, the poor ability resulted in severely unbalanced spinal-pelvic alignment in these patients. The forward inclined spine and retroverted femur would contribute to the poor physical activities in these patients. However, the abnormal sagittal spine-pelvis-leg alignment in patients with severe HOA might not be involved in the pathogenesis of low back pain.