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

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.

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.

Association of affected and non-affected side ability with postoperative outcomes in patients undergoing total hip arthroplasty

BACKGROUND

Although several reports have examined the association between preoperative function and postoperative outcomes in patients undergoing total hip arthroplasty (THA), it is unclear whether the ability of the affected or non-affected side particularly impacts on outcomes. We aimed to investigate the association between affected and non-affected side ability and walking independence.

METHODS

We prospectively enrolled 721 consecutive patients who underwent THA. Preoperatively, quadriceps isometric strength (QIS) and one-leg standing time (OLST) were measured. The endpoints were walking independence within 3, 5, 7, 10, and 14 days postoperatively. The associations between preoperative abilities and outcomes were examined using multivariate Cox hazard model, and the area under the curves (AUCs) for outcomes were compared.

RESULTS

We analysed 540 patients after excluding patients who met the exclusion criteria. Both affected and non-affected QIS predicted walking independence within 3 (p = 0.006 and 0.001, respectively), 5, 7, 10, and 14 (both p < 0.001) days postoperatively. For OLST, only the affected side did not predict walking independence within 3 days postoperatively (p = 0.154 and 0.012, respectively), and both sides did at days 5 (p = 0.019 and <0.001, respectively), 7, 10, and 14 (both p < 0.001). The AUCs of the non-affected side ability for walking independence were significantly greater than those of the affected side on postoperative days 3 (0.66 vs. 0.73; p = 0.021) and 5 (0.67 vs. 0.71; p = 0.040), with no significant difference after day 7.

CONCLUSIONS

Both sides abilities were associated with walking independence after THA, but non-affected side was found to be particularly crucial for early walking independence.

Failure of a Highly Cross-Linked Polyethylene Liner After Spine Fusion

A 73-year-old woman, 11 years after total hip arthroplasty and 2 years after a multilevel lumbar spine fusion, presented with a 2-month history of anterior hip and gluteal pain. She was diagnosed with an acetabular liner fracture that occurred through the high wall, likely related to repetitive impingement on the neck of the femoral implant, as notable burnishing was observed on the explanted femoral head. The acetabulum was successfully revised to a dual-mobility articulation. Spinal fusion after total hip arthroplasty can alter the acetabular implant position and was seen in our patient whose previously functional high-walled liner failed. Surgeons may consider alternative techniques, including a change in acetabular implant's anteversion to mitigate the need for a high-walled liner or the use of a dual-mobility bearing.

Improvement of Coxarthrosis Due to Realignment of Pelvic Retroversion Following Spinal Corrective Surgery: A Case Report

CASE

A 70-year-old woman presented with severe trunk deformity, gait disturbance, and bilateral hip pain. Radiography and magnetic resonance imaging revealed severe spinal kyphosis, bilateral osteoarthritis of the hip joints, and lumbar canal stenosis. A 2-stage corrective surgery for the treatment of spinal kyphosis was performed. Subsequently, the spinopelvic alignment changed remarkably. The spinal symptoms and radiographic parameters improved postoperatively, and bilateral hip pain and range of motion also showed improvement.

CONCLUSION

Corrective surgery for the treatment of degenerative spinal kyphosis affected the spinopelvic alignment, and the symptoms of simultaneous coxarthrosis also improved after the corrective surgery.

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.

Total hip arthroplasty has higher complication rates in stiff spine patients: a systematic review and network meta-analysis

BACKGROUND

Ankylosing spondylitis (AS) and spinal fusion (SF) classified as stiff spines have been associated with the increased rate of complications following total hip arthroplasty (THA). However, the differences between the two cohorts have inconsistent evidence.

METHODS

We searched for studies comparing complications among stiff spine patients, including SF and AS, who underwent THA in PubMed/MEDLINE, Embase, Cochrane CENTRAL, Web of Science, and Scopus until March 2021. Studies detailing rates of mechanical complications, aseptic loosening, dislocation, infection, and revisions were included. We performed network meta-analyses using frequentist random-effects models to compare differences between cohorts. We used P-score to rank the better exposure with the lowest complications.

RESULTS

Fourteen studies were included in the final analysis. A total of 740,042 patients were included in the systematic review and network meta-analysis. Mechanical complications were highest among SF patients (OR 2.33, 95% CI 1.86, 2.92, p < 0.05), followed by AS patients (OR 1.18, 95% CI 0.87, 1.61, p = 0.82) compared to controls. Long Spinal Fusions had the highest aseptic loosening (OR 2.33, 95% CI 1.83, 2.95, p < 0.05), dislocations (OR 3.25, 95% CI 2.58, 4.10, p < 0.05), infections (OR 2.14, 95% CI 1.73, 2.65, p < 0.05), and revisions (OR 5.25, 95% CI 2.23, 12.32, p < 0.05) compared to AS and controls. Our results suggested that SF with longer constructs may be associated with higher complications in THA patients.

CONCLUSIONS

THAs following SFs have higher mechanical complications, aseptic loosening, dislocations, and infections, especially with longer constructs. AS patients may have fewer complications compared to this cohort.

Postoperative acetabular component position in revision hip arthroplasty: a comparison of the anterior and posterior approaches

BACKGROUND

While previously considered unsuitable for revision total hip arthroplasty (rTHA), the direct anterior approach (DAA) can be extended to allow for safe acetabular component revision. In primary hip arthroplasty, the DAA and its associated fluoroscopy, has been shown to produce more acceptable component positioning. However, there is little data comparing the DAA to the posterior approach (PA) for rTHA. We hypothesised that, the DAA with intraoperative fluoroscopy would allow for more precise acetabular component positioning when compared to those performed using a PA.

METHODS

50 consecutive patients (25 DAA and 25 PA) undergoing rTHA were included. Radiographic analysis of postoperative acetabular component position was then performed. Univariate and multivariate analyses was performed to assess the contribution of approach on cup positioning inside classically defined "safe zones".

RESULTS

Baseline patient characteristics were similar. The PA was associated with more cups placed outside the Lewinnek (48% vs. 12%, p = 0.005) and the Danoff (52% vs. 28%, p = 0.083) "safe zones" when compared to the DAA. Multivariate analysis revealed that operative approach was the only patient or surgical factor associated with component position outside of the "safe zones" (Lewinnek [OR = 13.6; 95% CI, 2.12-87.9, p = 0.006] and Danoff [OR = 7.7; 95% CI, 1.48-40.1, p = 0.015]).

CONCLUSION

Our results suggest that the DAA allows for more reproducible and precise cup placement in RTHA. The safe-zone paradigm remains a useful index of accurate cup positioning and the DAA, with use of intraoperative fluoroscopy, offers more consistent acetabular component positioning when compared to the PA.

Does Prior Lumbar Fusion Influence Dislocation Risk in Hip Arthroplasty Performed for Femoral Neck Fracture?

BACKGROUND

Immobility of the lumbar spine predicts instability following elective total hip arthroplasty (THA). The purpose of this study is to determine how prior lumbar fusion (LF) influenced dislocation rates and revision rates for patients undergoing THA or hemiarthroplasty (HA) for femoral neck fracture (FNF).

METHODS

A retrospective cohort analysis was conducted utilizing the PearlDiver database from 2010 to 2018. Patients who underwent arthroplasty for FNF were identified based on history of LF and whether they underwent THA or HA. Univariate and multivariate analyses were performed.

RESULTS

A total of 328 patients with prior LF and FNF who underwent THA were at increased risk for 1-year dislocation (odds ratio [OR] 2.19, P < .001) and 2-year revision (OR 2.22, P < .001) compared to 14,217 patients without LF. The 461 patients with prior LF and FNF who underwent HA were at increased risk for dislocation (OR 2.22, P < .001) compared to 42,327 patients without LF. Patients with prior LF and FNF who underwent THA had higher rates of revision than patients with prior LF who underwent HA for FNF (OR 2.11, P < .001). In patients with prior LF and FNF, THA was associated with significantly increased risk for dislocation (OR 3.07, P < .001) and revision (OR 2.53, P < .001) compared to THA performed for osteoarthritis.

CONCLUSION

Patients with prior LF who sustained an FNF and underwent THA or HA were at increased risk for early dislocation and revision compared to those without prior LF. This risk of dislocation and revision is even greater than that observed in patients with prior LF who underwent THA for osteoarthritis.

LEVEL OF EVIDENCE

Level III.

Return to Sports and Minimum 2-Year Outcomes of Hip Arthroscopy in Elite Athletes With and Without Coexisting Low Back Pain: A Propensity-Matched Comparison

BACKGROUND

Patient-reported outcomes (PROs) and return to sports (RTS) after hip arthroscopy for femoroacetabular impingement syndrome (FAIS) have not been established in elite athletes with coexisting low back pain (LBP).

PURPOSE

(1) To report minimum 2-year PROs and RTS rates after primary hip arthroscopy for FAIS in elite athletes with coexisting LBP and (2) to compare clinical results with a propensity-matched control group of elite athletes without back pain.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Data were reviewed for elite athletes (college and professional) who underwent hip arthroscopy for FAIS and had coexisting LBP between October 2009 and October 2018. Inclusion criteria were preoperative and minimum 2-year follow-up for the modified Harris Hip Score, Nonarthritic Hip Score, Hip Outcome Score-Sports Specific Subscale (HOS-SSS), and visual analog scale for pain. Exclusion criteria were Tönnis grade >1, hip dysplasia (lateral center-edge angle <18°), and previous ipsilateral hip or spine surgery or conditions. Rates of achieving the minimal clinically importance difference (MCID), patient acceptable symptomatic state (PASS), and maximum outcome improvement satisfaction threshold were recorded in addition to RTS. For the subanalysis, the elite athlete study group was propensity matched to an elite athlete control group without back pain.

RESULTS

A total of 48 elite athletes with LBP who underwent primary hip arthroscopy met inclusion criteria, and follow-up was available for 42 (87.5%) at 53.2 ± 31.6 months (mean ± SD). Elite athletes with coexisting LBP demonstrated significant improvements in all recorded PROs and achieved the MCID and PASS for the HOS-SSS at rates of 82.5% and 67.5%, respectively. They also returned to sports at a high rate (75.8%), and 79% of them did not report LBP postoperatively. PROs, rates of achieving the MCID and PASS for the HOS-SSS, and RTS rates were similar between the study group and propensity-matched control group.

CONCLUSION

Elite athletes with coexisting LBP who undergo primary hip arthroscopy for FAIS may expect favorable PROs, rates of achieving the MCID and PASS for the HOS-SSS, and RTS rates at minimum 2-year follow-up. These results were comparable to those of a propensity-matched control group of elite athletes without back pain. In athletes with hip-spine syndrome, successful treatment of their hip pathology may help resolve their back pain.

Pelvic position, lying on a traction table, during THA by direct anterior approach. Comparison with the standing position and influence on the acetabular cup anteversion

INTRODUCTION

The placement of prostheses for a total hip arthroplasty (THA) is essential to limit complications and optimize functional results. In a recent study of more than 100 THA placed through a direct anterior approach using a traction table, we found that the mean anteversion of the cup was greater (30°) than recommended (20°). To explain this phenomenon, we considered that the anterior pelvic plane (APP), defined by the plane passing through the anterior-superior iliac spines and the pubic symphysis, which serves as a landmark for the placement and calculation of the anteversion of the cup, was not horizontal when the patient was lying on the traction table. This concept has not been evaluated so we conducted a prospective study to: 1) measure the position of the pelvis on a traction table; 2) compare to the standing position, 3) assess its impact on the anteversion of the cup.

HYPOTHESIS

The standing pelvic version is identical to the supine pelvic version on the traction table.

MATERIAL AND METHODS

A prospective 3-month monocentric study was conducted. All patients operated on for a THA by a direct anterior approach, on a traction table, were included. The position of the pelvis was assessed by measuring the tilt of the APP on lateral pelvic X-rays, while on the traction table and while standing. The impact of the position of the pelvis on the positioning of the cup, as well as the anteversion, were measured using the EOS imaging system. The anatomic anteversion of the cup was measured in relation to the APP.

RESULTS

Fifty-eight patients were included (32 women, 26 men) with an average age of 67 years. The tilt of the supine APP was 6°±8.3 [range of -10.5 to 31.0] (indicating a retroverted pelvis on the traction table). The difference between the tilt of the standing and lying APP (within 90°) was not significant (standing was on average 4.5° [range of -11.0 to 27.0] versus lying on the table, was on average 6° [range of -10.5 to 31.0] (p=0.75). A strong correlation was observed between the tilt of the supine APP and the anatomic anteversion of the cup (p<0.001). Thus, the more retroverted the pelvis was on the traction table, the lower the anatomic anteversion of the acetabular cup.

CONCLUSION

The supine pelvis on the traction table is not always horizontal and its position on the traction table is similar to its standing position, within 90 degrees. The analysis of the positioning of the preoperative pelvis appears to be essential in the planning of a THA through direct anterior approach using a traction table.

LEVEL OF EVIDENCE

IV; Prospective Cohort Study.

Rapidly destructive osteoarthritis and total hip arthroplasty: A new technique for acetabular reconstruction in the setting of extensive bone loss

We report the case of a 58-year-old woman who presented with rapidly destructive osteoarthritis (RDO) of the hip that had been causing her severe pain and disability. By the time of presentation to our institution, she had a significant leg length discrepancy resulting from extensive destruction of the posterior acetabular wall, posterior column, and femoral head with a superiorly migrated femoral shaft. She underwent structural acetabular allograft augmentation of the pelvis re-enforced with a locking plate, concomitant total hip replacement with dual mobility implants, and extensive soft tissue releases to restore length to the extremity.

Pelvic incidence affects postoperative dislocation rate in total hip arthropalsty patients with spinal fusion

PURPOSE

The purpose of this study was to compare the clinical outcome of total hip arthroplasty (THA) with and without spinal fusion (SF), and to evaluate the radiographic characteristics of patients with dislocation after THA.

METHODS

A case-controlled study of 53 patients (67 hips) who underwent both THA and SF was performed. The control group was matched to the SF group by age, gender and body mass index, and 106 patients (134 hips) were selected. Hip function was evaluated using the Japanese Orthopaedic Association (JOA) hip score. In addition, the incidence rates of postoperative complications were determined. Radiograph evaluation included lateral inclination and anteversion of the acetabular component. We also analysed sacral slope (SS), pelvic tilt (PT), and pelvic incidence (PI).

RESULTS

The JOA hip score at final follow up was significantly poorer in the SF group compared to the control group. There were 5 cases of dislocations in the SF group and none in the control group. The anteversion of acetabular cup, PT, and PI were significantly higher in the SF group compare to the control group. In particular, the PI of patients with anterior dislocation were significantly higher compare to those of patients without dislocation.

CONCLUSIONS

Our study showed that SF is a risk factor for a poorer clinical outcome and postoperative dislocation of THA. In addition, the abnormal value of PI may be a risk factor to predict dislocation after THA with SF.

Relieved Low Back Pain after Total Hip Arthroplasty in Patients with Both Hip Osteoarthritis and Lumbar Degenerative Disease

Objective

To investigate the relief of low back pain after hip arthroplasty in patients with hip joint and spinal degenerative diseases, and to discuss the effects of unilateral and bilateral hip surgery on the relief of low back pain.

Methods

In this retrospective study, we followed 153 patients (69 males and 84 females, age: 43–88 years) who had undergone total hip arthroplasty (THA) via a posterolateral approach and also suffered from lumbar degenerative diseases in the period of 2009 to 2019. The inclusion criteria were: (i) patients who had been diagnosed with severe hip degenerative disease and also been diagnosed with lumbar degenerative disease; (ii) patients who had undergone THA surgery; and (iii) patients who were retrospectively recruited. The exclusion criteria were: (i) patients who had undergone lumbar fusion or internal fixation surgery; or (ii) patients who had vascular claudication, history of major trauma, diabetic polyneuropathy, lumbar and pelvic infections, tumor diseases; (iii) or patients who had undergone THA because of femoral neck fracture or ankylosing spondylitis. The improvement of hip joint function and the relief of low back pain (LBP) were studied, and the effect of unilateral and bilateral THA on the relief of LBP were discussed. Hip pain and function were evaluated by the Harris Hip Score (HHS), LBP was evaluated by Visual Analog Scale (VAS), and lumbar function was evaluated by the Japanese Orthopaedic Association (JOA) scoring system.

Results

The average follow‐up time was 44.3 months (24–108 months). All patients recovered smoothly without complications. The LBP VAS of 153 patients decreased from 4.13 ± 1.37 preoperatively to 1.90 ± 1.44 postoperatively. The average HHS increased from 45.33 ± 13.23 preoperatively to 86.44 ± 7.59 postoperatively at the latest follow‐up. According to Japanese Orthopaedic Association scoring system, the proportion of patients with good response to treatment in these 153 patients reached 93.46%. LBP VAS decreased from 4.18 ± 1.38 preoperatively to 1.95 ± 1.49 postoperatively in unilateral group and from 3.94 ± 1.32 preoperatively to 1.73 ± 1.23 postoperatively in bilateral group, respectively. There were only nine patients with persistent or aggravated LBP after operation. Among them, six patients underwent subsequent lumbar surgery (five patients had pain relieved after reoperation and one patient had not) and the other three patients chose conservative treatment for pain.

Conclusion

THA can relieve LBP while relieving hip pain and restoring hip function in patients with both hip and lumbar degenerative disease, thus possibly avoiding further spinal surgery.

Limited lumbopelvic mobility does not influence short-term outcomes after primary hip arthroscopy: a propensity-matched controlled study

There is a paucity of literature investigating the effect of lumbopelvic mobility on patient-reported outcome scores (PROs) after primary hip arthroscopy. The purpose of this study was (i) to report minimum 1-year PROs in patients with limited lumbopelvic mobility (LM) who underwent primary hip arthroscopy for femoroacetabular impingement syndrome (FAIS) and (ii) to compare clinical results with a propensity-matched control group of patients with normal lumbopelvic mobility (NM). Data were reviewed for surgeries performed between November 2019 and March 2020. Patients were considered eligible if they received a primary hip arthroscopy for FAIS in the setting of LM (seated to standing change in sacral slope ≤ 10°). LM patients were propensity-matched to a control group of patients with normal lumbopelvic motion (seated to standing change in sacral slope > 10°) for comparison. A total of 17 LM and 34 propensity-matched NM patients were included in the study. LM patients showed significant improvement in all outcome measures and achieved the minimum clinically important difference (MCID) and patient acceptable symptomatic state (PASS) at high rates for modified Harris Hip Score (MCID: 94% and PASS: 82%) and International Hip Outcome Tool-12 (iHOT-12; MCID: 94% and iHOT-12: 76%). When LM patients were compared to a propensity-matched control group of NM patients, they demonstrated similar postoperative PROs and rates of achieving MCID/PASS. LM patients who undergo primary hip arthroscopy may expect favorable short-term PROs at minimum 1-year follow-up. These results were comparable to a control group of NM patients.

Association of Lumbar Degenerative Disease and Revision Rate following Total Knee Arthroplasty

Recently, a variety of studies have analyzed the potential correlation between lumbar degenerative disease (LDD) and inferior clinical outcomes after total hip arthroplasty. However, there has been limited data concerning the role of LDD as a risk factor for failure after total knee arthroplasty (TKA). The aim of our study was to determine: (1) what is the association of LDDs with TKA failure (all-cause revision) within 2 years of index arthroplasty and (2) if patients with LDD and lumbar fusion are at increased risk of TKA revision within 2 years compared with LDD patients without fusion. Data were collected from the Humana insurance database using the PearlDiver database from 2007 to 2017. To assess aim 1, patients were stratified into two groups based on a prior history of LDD (International Classification of Diseases [ICD]-9 or -10 diagnostic codes). To analyze aim 2, patients within the LDD cohort were stratified based on the presence of lumbar fusion (lumbar fusion Current Procedural Terminology code). All-cause revision rate was 3.4% among LDD patients versus 2.4% of patients with non-LDD (p < 0.001) at 2 years. Following multivariate analysis, LDD patients were at increased risk of all-cause revision surgery at 2 years (odds ratio [OR]: 1.361; 95% confidence interval [CI]: 1.238-1.498; p < 0.001) as well as aseptic loosening (OR: 1.533; 95% CI: 1.328-1.768; p < 0.001), periprosthetic joint infection (OR: 1.245; 95% CI: 1.129-1.373; p < 0.001), and periprosthetic fracture (OR: 1.521; 95% CI: 1.229-1.884; p < 0.001). Among LDD patients, patients who have a lumbar fusion had an all-cause revision rate of 5.0%, compared with 3.2% among LDD with no lumbar fusion patients at 2 years (p = 0.021). Following multivariate analysis, lumbar fusion patients were at increased risk of all-cause revision surgery (OR: 1.402; 95% CI: 1.362-1.445; p = 0.028), aseptic loosening (OR: 1.432; 95% CI: 1.376-1.489; p = 0.042), and periprosthetic fracture (OR: 1.302; 95% CI: 1.218-1.392; p = 0.037). Based on these findings, TKA candidates with preoperative LDD should be counseled that TKA outcome may be impaired by the coexistence of lumbar spine degenerative disease. This is Level III therapeutic study.

2021 Otto Aufranc Award: A simple Hip-Spine Classification for total hip arthroplasty : validation and a large multicentre series

AIMS

Patients with spinal pathology who undergo total hip arthroplasty (THA) have an increased risk of dislocation and revision. The aim of this study was to determine if the use of the Hip-Spine Classification system in these patients would result in a decreased rate of postoperative dislocation in patients with spinal pathology.

METHODS

This prospective, multicentre study evaluated 3,777 consecutive patients undergoing THA by three surgeons, between January 2014 and December 2019. They were categorized using The Hip-Spine Classification system: group 1 with normal spinal alignment; group 2 with a flatback deformity, group 2A with normal spinal mobility, and group 2B with a stiff spine. Flatback deformity was defined by a pelvic incidence minus lumbar lordosis of > 10°, and spinal stiffness was defined by < 10° change in sacral slope from standing to seated. Each category determined a patient-specific component positioning. Survivorship free of dislocation was recorded and spinopelvic measurements were compared for reliability using intraclass correlation coefficient.

RESULTS

A total of 2,081 patients met the inclusion criteria. There were 987 group 1A, 232 group 1B, 715 group 2A, and 147 group 2B patients. A total of 70 patients had a lumbar fusion, most had L4-5 (16; 23%) or L4-S1 (12; 17%) fusions; 51 patients (73%) had one or two levels fused, and 19 (27%) had > three levels fused. Dual mobility (DM) components were used in 166 patients (8%), including all of those in group 2B and with > three level fusions. Survivorship free of dislocation at five years was 99.2% with a 0.8% dislocation rate. The correlation coefficient was 0.83 (95% confidence interval 0.89 to 0.91).

CONCLUSION

This is the largest series in the literature evaluating the relationship between hip-spine pathology and dislocation after THA, and guiding appropriate treatment. The Hip-Spine Classification system allows surgeons to make appropriate evaluations preoperatively, and it guides the use of DM components in patients with spinopelvic pathology in order to reduce the risk of dislocation in these high-risk patients. Cite this article: Bone Joint J 2021;103-B(7 Supple B):17-24.

The Hip-Spine Relationship in Total Hip Arthroplasty: How to Execute the Plan

BACKGROUND

Patients with spinopelvic pathology, including lumbar spine stiffness and sagittal spinal deformity, are at increased risk for postoperative complications, including instability, dislocation, and revision after total hip arthroplasty (THA). Recent evidence has suggested that the Lewinnek safe zone should no longer be considered an appropriate target for all patients, especially those with spinopelvic pathology, as the safe zone is a dynamic rather than static target. There are 2 distinct issues for arthroplasty surgeons to consider: lumbar spinal stiffness and sagittal spinal deformity, each of which has its own management.

METHODS

In order to manage patients with spinopelvic pathology undergoing THA, a basic understanding of spinopelvic parameters, including sagittal balance, sacral slope, and anterior pelvic plane, is essential. Techniques outlined in this manuscript describe a systematic preoperative work-up and intraoperative management of acetabular component positioning according to patient-specific spinopelvic parameters, ensuring optimal component placement and a reduced risk for impingement, instability, and poor postoperative outcomes.

RESULTS

Evaluation of each patient's spinopelvic parameters informs patient classification according to the Hip-Spine Classification for THA. Patient classification is determined by the presence of spinal stiffness and spinal deformity, with corresponding scoring and classification into one of the 4 categories used to determine risk for postoperative dislocation, define patient-specific cup positioning, and create their functional safe zone.

CONCLUSION

A simple 2-step preoperative assessment with measurements of the anterior pelvic plane and the sacral slope on standing and seated lateral X-rays will identify patients at high risk for postoperative dislocation due to spinal deformity and/or stiffness. Accounting for spinopelvic pathology and adhering to the Hip-Spine Classification guidelines for acetabular component positioning can help reduce the burden of instability and revisions in this complex patient population.

Editorial Commentary: Spine Pathology May Compromise the Results of Hip Arthroscopy: Will Hip Arthroscopy Improve Low Back Pain?

Pathology of the lumbar spine and hip commonly occur concurrently. The hip-spine connection has been well documented in the hip arthroplasty literature but until recently has been largely ignored in the setting of hip arthroscopy. Physical examination and diagnostic workup of the lumbosacral junction are warranted to further our understanding of the effects of lumbosacral motion and pathology in patients with concomitant femoroacetabular impingement syndrome. An understanding of this relationship will better allow surgeons to counsel and preoperatively optimize patients undergoing evaluation and treatment of femoroacetabular impingement syndrome. Several studies have reported that patients with a previous lumbar arthrodesis undergoing hip arthroplasty have lower patient-reported outcomes and greater revision rates compared with patients without previous lumbar surgery, and similar to its effect on outcomes after hip arthroplasty, lumbar spine disease can compromise outcomes after hip arthroscopy. On the other side of the coin, hip arthroplasty has been shown to improve low back pain in patients with concomitant hip osteoarthritis. Can the arthroscopic treatment of nonarthritic hip pathology offer a similar result? We won't know unless we look.

Influence of sagittal degenerative spondylolisthesis on anteversion of the acetabular component in total hip arthroplasty

BACKGROUND

Degenerative lumbar spondylolisthesis (DSPL), as opposed to other degenerative spinal conditions, is disregarded in the assessment of hip stability after total hip arthroplasty (THA). This study aimed to determine whether patients with DSPL have different acetabular anteversion compared to patients with normal spine before and following THA.

METHODS

Preoperative and postoperative 6‑month lateral pelvic radiographs in standing and sitting positions from 91 patients who underwent primary THA were retrospectively compared for spinopelvic parameters between patients with DSPL (n = 31) and with normal spine (n = 34).

RESULTS

Compared to control patients in the standing position, patients with DSPL had significantly increased preoperative pelvic tilt (24° in DSPL vs. 8° in controls; p < 0.01), pelvic-femoral angle (194° in DSPL vs. 174° in controls; p < 0.05), decreased lumbar lordosis (35° in DSPL vs. 43° in controls; p < 0.05), increased postoperative pelvic tilt (22° in DSPL vs. 7° in controls; p < 0.01), pelvic-femoral angle (187° in DSPL vs. 179° in controls; p < 0.05), and acetabular anteversion (31° in DSPL vs. 23° in controls; p < 0.05). Preoperative (p = 0.181) and postoperative (p = 0.201) sitting pelvic tilt did not differ. There were positive correlations between preoperative standing pelvic tilt and postoperative standing acetabular anteversion, pelvic-femoral angle, and combined sagittal index (CSI) in DSPL (R² = 0.8416; R² = 0.9180; R² = 0.9459, respectively, p < 0.01) and in controls (R² = 0.6872; R² = 0.6176; R² = 0.7129, respectively, p < 0.01).

CONCLUSION

While the imbalance of seated sagittal plane is usually insignificant and compensable, the mechanism by which DSPL patients achieve a standing posture is different from control patients, with more hip extension and posterior tilt of the pelvis. Special attention should be paid to the risk of impingement caused by the increase of acetabular anteversion in the postoperative standing position.

Editorial Commentary: Lumbosacral Anatomy and Mechanics Influence Femoroacetabular Impingement Syndrome and Surgical Outcomes: The Hip Bone Is Connected to the Back Bone

The hip joint in general and femoroacetabular impingement (FAI) in particular do not exist in a vacuum. Impingement kinematics are very closely tied to the relationship between spinopelvic motion and posture, and that of the hip joint itself. While the relationship of lumbar degenerative disease, fusion, and sagittal balance to hip arthroplasty has been well studied, there is a paucity of data on the analogous relationship of the stiff spine with hip arthroscopy and FAI. While further studies are critical in advancing our understanding of this relationship in this unique population, surgeons still must consider the relationship of lumbosacral motion and posture, including the anatomic variant of lumbosacral transitional vertebrae, when evaluating and treating patients with FAI.

Can Dislocation Rates Be Decreased Using the Anterior Approach in Patients With Lumbar Spondylosis or Lumbar Instrumented Fusion?

BACKGROUND

Although spinopelvic stiffness is known to contribute to instability following total hip arthroplasty (THA), it is unknown whether use of an anterior surgical approach is associated with decreased postoperative instability rates in patients with lumbar spondylosis or fusion.

METHODS

A retrospective review was performed of 1750 patients who underwent primary THA at our institution over an 8-year time period. Radiographic and chart review was performed evaluating for dislocations. Lumbar and pelvic radiographs were used to identify the presence of spondylosis and/or instrumented fusion. Patients were then divided into non-spondylosis and spondylosis or fusion groups to compare dislocation rates by surgical approach.

RESULTS

In total, 54.4% of THA patients had an anterior approach (n = 952) and 54.6% had lumbar spondylosis or instrumented fusion (n = 956). There were 29 dislocations in total (1.7%), with less occurring in anterior approach patients (0.6% vs 2.9%, P < .001). In the patients without lumbar spondylosis, there were less dislocations in the anterior approach group (0.2% vs 1.7%, P = .048). Likewise, in patients with lumbar spondylosis or fusion, there were less dislocations in the anterior approach group (1.0% vs 3.8%, P = .004). Using logistic regression, there was a 4.1× increased risk of dislocation with a posterior approach vs an anterior approach in the spondylosis or fusion group (P = .011).

CONCLUSION

Patients with lumbar spondylosis or fusion have high rates of instability. At our institution, we found that utilization of an anterior surgical approach substantially mitigated this risk.

Do All Rigid and Unbalanced Spines Present the Same Risk of Dislocation After Total Hip Arthroplasty? A Comparison Study Between Patients With Ankylosing Spondylitis and History of Spinal Fusion

BACKGROUND

Spines with ankylosis or with a history of lumbosacral fusions have been collectively classified as rigid and unbalanced, and associated with an increased rate of dislocation after total hip arthroplasty (THA). It remains unknown whether the cause of spinal arthrodesis influences the dislocation rate.

METHODS

A retrospective study was conducted from January 2000 to December 2017, with an institutional review board's approval to identify 2 cohorts with a history of THA: one with ankylosing spondylitis (AS) involving the lumbosacral spine and another cohort with a history of lumbosacral spinal fusion (SF). A chart review was performed to collect demographic and surgical variables. Lumbar lordosis angle (LLA), acetabular anteversion, and inclination angle measurements were taken for each patient. Kaplan-Meier survivorship curves were constructed and multivariable Cox regression was performed for analysis.

RESULTS

The AS and SF cohorts consisted of 142 and 135 patients, respectively. The SF group had a greater mean LLA (34.18°) than the AS group (21°). A total of 16 patients (11.85%) suffered from dislocation after primary elective THA in the SF group, whereas 4 patients (2.82%) in the AS group. After multivariable Cox regression analysis, increasing LLA and hips outside of the Lewinnek safe zone were found to be associated with a higher hazard of dislocation after THA.

CONCLUSION

We found that the degree of lumbar spine curvature is more associated with dislocation after THA than the history of SF itself; specifically, an increase in lumbar lordosis angle of 1º increases the probability of dislocation by 13% among AS and SF patients.

Lumbosacral Transitional Vertebrae Predict Inferior Patient-Reported Outcomes After Hip Arthroscopy

BACKGROUND

While the association between spinal disease and hip arthroplasty outcomes has been well studied, there is less known about the effect of spinal pathology in hip arthroscopy (HA) outcomes. Lumbosacral transitional vertebrae (LSTV) are anatomic variations where caudal vertebrae articulate or fuse with the sacrum or ilium.

HYPOTHESIS

LSTV can lead to inferior outcomes after HA for treatment of femoroacetabular impingement.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

We retrospectively reviewed the prospectively collected Hip Arthroscopy Database at our institution for patients with LSTV who underwent HA between 2010 and 2017. A total of 62 patients with LSTV were identified and then matched to controls. Patient-reported outcome measures (PROMs) were collected, including the modified Harris Hip Score, Hip Outcome Score-Activities of Daily Living, Hip Outcome Score-Sports, and the 33-item International Hip Outcome Tool. They were collected at 4 time points: preoperatively and 5 to 11 months, 12 to 23 months, and 24 to 35 months postoperatively. Longitudinal analysis of the PROMs was done using generalized estimating equation modeling. Additionally, alpha angles were measured from preoperative radiographic data.

RESULTS

Preoperatively, there was no significant difference between patients with and without LSTV on 3 of the 4 PROMs; however, patients with LSTV did have significantly lower preoperative scores than controls for the Hip Outcome Score-Activities of Daily Living (P = .029). Patients with LSTV reported significantly lower scores on all 4 PROMs at each postoperative time point. Radiographic data showed no significant difference in alpha angles across cohorts. When LSTV were compared by Castellvi type, types 3 and 4 tended to have lower scores than types 1 and 2; however, these comparisons were not significant.

CONCLUSION

The data support our hypothesis that HA has less benefit in patients with LSTV as compared with patients without LSTV. In patients with LSTV, careful evaluation of the anomaly is recommended to help guide surgical counseling and manage expectations.

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.

Patients Who Undergo Primary Lumbar Spine Fusion After Recent but Not Remote Total Hip Arthroplasty Are at Increased Risk for Complications, Revision Surgery, and Prolonged Opioid Use

OBJECTIVE

To evaluate the effect of a recent history of total hip arthroplasty (THA) on primary lumbar spine fusion (LSF) for concurrent hip and spine disease.

METHODS

A total of 98,242 patient records from the PearlDiver Database were evaluated and divided into 3 cohorts: 1) patients with a history of LSF alone, 2) patients with a history of LSF for newly diagnosed lumbar disease after having a remote THA> 2 years previously, and 3) patients with a history of LSF after having recent THA <2 years before LSF who initially presented with concurrent hip and lumbar spine disease and underwent THA before LSF. Postoperative outcomes were assessed with multivariable logistic regression to determine the effect of THA on outcomes after LSF with respect to postoperative complications, LSF revision rates, and opioid use.

RESULTS

Patients who had LSF after a recent THA had increased risk of deep venous thrombosis (adjusted odds ratio [aOR], 1.39; P = 0.0191), neurologic complications (aOR, 1.81; P = 0.0459), prolonged opioid use (aOR, 1.22; P = 0.0032), and revision LSF (12.8%; P = 0.0004 vs. 9.9%; OR, 1.41; P < 0.0001; hazard ratio, 1.69; P < 0.0001). Patients who underwent LSF after a remote history of THA had no significant difference in DVT (4.2% vs. 2.6%, aOR, 1.31; P = 0.2190), neurologic complications (1.0% vs. 0.5%, aOR, 2.02; P = 0.1220), revision surgery (9.6% vs. 9.9%, aOR, 1.06; P = 0.7197), or prolonged opioid use (36.5% vs. 24.4%, aOR, 1.17; P = 0.1120).

CONCLUSIONS

Patients who undergo LSF with a history of THA may be at increased risk of postoperative complications, revision LSF, and prolonged opioid use if their THA was performed for concurrent hip-spine disease in the recent past (<2 years).

Can Flexed-Seated and Single-Leg Standing Radiographs Be Useful in Preoperative Evaluation of Lumbar Mobility in Total Hip Arthroplasty?

BACKGROUND

The purpose of this study is to determine whether simulated radiographs in the "flexed-seated" or "step-up" positions better demonstrate a patient's range of spinopelvic motion between standing and sitting positions than relaxed sitting and standing radiographs.

METHODS

An institutional review board approved cohort of 43 patients with hip osteoarthritis whom underwent full body sitting-standing radiographs from August 2016 to December 2017 at a single institution was reviewed. Subjects underwent single-leg step-up standing and flexed-seated radiographs, and relaxed standing and sitting radiographs. Sacral slope, spinopelvic tilt (SPT), and lumbar lordosis were measured in all radiographs. Alignment parameters were compared between both sets of imaging, and the change in SPT between the imaging modalities was plotted and stratified by pre-existing lumbar pathology.

RESULTS

There were significant differences between the relaxed standing and step-up radiographs and the relaxed and flexed-seated radiographs for sacral slope, SPT, and lumbar lordosis (P < .002 for all), with the exception of SPT in the relaxed and step-up standing postures (P = .110). When transitioning from the standing to sitting position, the mean changes in SPT differed significantly between both sets of radiographs. Most importantly, when plotting changes in SPT between flexed and relaxed sitting postures, patients with fusions and flatback deformity trended toward greater anterior pelvic tilting, a position of greater risk of posterior dislocation.

CONCLUSION

Flexed sitting and single-leg standing imaging may emphasize the compensatory mechanisms of patients with concomitant hip and spine pathology more than relaxed imaging using our measurements. Our method may provide insight into high dislocation risk patients compared to the previously published hip measurement method.

LEVEL OF EVIDENCE

III.

Surgical implications of the hip-spine relationship in total hip arthroplasty

Total hip arthroplasty (THA) is considered the most successful orthopedic surgical procedure of the last century with excellent survivorship up to 20-years. However, instability remains a major issue representing the most common reason for revision after THA. Hip-spine relationship has gained progressive interest between arthroplasty surgeons and its understanding is crucial in order to identify high-risk patients for postoperative dislocation. Spinal deformity and abnormal spinopelvic mobility have been associated with increased risk for instability, dislocation and revision THA. Preoperative workup begins with standing anteroposterior pelvis x-ray and lateral spinopelvic radiographs in the standing and sitting position. Hip-spine stiffness needs to be addressed before THA in consideration of adapting the preoperative planning to the patient's characteristics. Acetabular component should be implanted with different anteversion and inclination angles according to the pattern of hip-spine motion in order to reduce the risk of impingement and consequent dislocation. Different algorithmic approaches have been proposed in case of concomitant hip-spine disease and in case of altered sagittal balance and pelvic mobility. The aim of this review is to investigate and clarify the hip-spine relationships and evaluate the impact on modern total hip arthroplasty.

Surgical Treatment of Patients With Dual Hip and Spinal Degenerative Disease: Effect of Surgical Sequence of Spinal Fusion and Total Hip Arthroplasty on Postoperative Complications

STUDY DESIGN

Retrospective study.

OBJECTIVE

To determine how lumbar spinal fusion-total hip arthroplasty (LSF-THA) operative sequence would affect THA outcomes.

SUMMARY OF BACKGROUND DATA

Outcomes following THA in patients with a history of lumbar spinal degenerative disease and fusion are incompletely understood.

METHODS

The PearlDiver Research Program (http://www.pearldiverinc.com) was used to identify patients undergoing primary THA. Patients were divided into four cohorts: 1) Primary THA without spine pathology, 2) remote LSF prior to hip pathology and THA, and patients with concurrent hip and spinal pathology that had 3) THA following LSF, and 4) THA prior to LSF. Postoperative complications and opioid use were assessed with multivariable logistic regression to determine the effect of spinal degenerative disease and operative sequence.

RESULTS

Between 2007 and 2017, 85,595 patients underwent primary THA, of whom 93.6% had THA without lumbar spine degenerative disease, 0.7% had a history of remote LSF, and those with concurrent hip and spine pathology, 1.6% had THA prior to LSF, and 2.4% had THA following LSF. Patients with hip and lumbar spine pathology who underwent THA prior to LSF had significantly higher rates of dislocation (aOR = 2.46, P < 0.0001), infection (aOR = 2.65, P < 0.0001), revision surgery (aOR = 1.91, P < 0.0001), and postoperative opioid use at 1 month (aOR: 1.63, P < 0.001), 3 months (aOR = 1.80, P < 0.001), 6 months (aOR: 2.69, P < 0.001), and 12 months (aOR = 3.28, P < 0.001) compared with those treated with THA following LSF.

CONCLUSION

Patients with degenerative hip and lumbar spine pathology who undergo THA prior to LSF have a significantly increased risk of postoperative dislocation, infection, revision surgery, and prolonged opioid use compared with THA after LSF. Surgeons should consider the surgical sequence of THA and LSF on outcomes for patients with this dual pathology. Shared decision making between patients, spine surgeons, and arthroplasty surgeons is necessary to optimize outcomes in patients with concomitant hip and spine pathology.

LEVEL OF EVIDENCE

3.

The Influence of Lumbosacral Spine Pathology on Minimum 2-Year Outcome After Hip Arthroscopy: A Nested Case-Control Analysis

BACKGROUND

Previous literature has examined the association between lumbosacral pathology and hip pathomechanics. However, the effect of lumbosacral pathologies and previous lumbosacral surgery on achieving meaningful outcomes after hip arthroscopy for femoroacetabular impingement syndrome (FAIS) has yet to be studied conclusively.

PURPOSE

To determine whether a history of lumbosacral spine pathology has an influence on achieving minimal clinically important differences (MCIDs) after hip arthroscopy for FAIS.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients undergoing hip arthroscopy for FAIS by a single, fellowship-trained orthopaedic surgeon between January 2012 and April 2017 with minimum 2-year follow-up were retrospectively reviewed. Patients with a history of lumbosacral spine pathology (eg, lumbosacral fusion, disc or vertebral pathology, or history of lumbosacral fractures) were matched 1:2 by age, body mass index, and sex to patients without spine pathology. Clinical outcomes including the Hip Outcome Score-activities of daily living subscale (HOS-ADL), HOS-sports subscale (HOS-SS), modified Harris Hip Score (mHHS), international Hip Outcome Tool-12 (iHOT-12), visual analog scale (VAS) pain, and VAS satisfaction were compared between the groups using an independent t test. The threshold of every outcome score for achieving MCID was calculated separately for each group and frequencies were compared.

RESULTS

A total of 83 of 108 eligible patients with lumbosacral pathology were identified and matched to 166 patients without any spine pathology. When compared with the non-spine pathology group, the lumbosacral pathology group had significantly lower 2-year postoperative outcome score averages across all reported outcome tools (all P < .001). There were significant differences in the proportion achieving the threshold for HOS-ADL (60.6% vs 80.0%; P = .004), HOS-SS (57.6% vs 82.1%; P < .001), mHHS (66.7% vs 81.7%; P = .025), and iHOT-12 (54.8% vs 87.6%; P < .001) scores for MCID when comparing the lumbosacral and nonlumbosacral pathology groups.

CONCLUSION

Patients with a history of lumbosacral pathology achieved significantly lower short-term meaningful clinical outcomes after undergoing hip arthroscopy for FAIS when compared with patients without spine pathology. The present study findings have implications for preoperative patient screening, shared decision-making processes/expectation management, and rehabilitation strategies.

How much does lumbar fusion change sagittal pelvic tilt in individuals receiving total hip arthroplasty?

Background

This study primarily aims to examine the effect of lumbar fusion on changes in sagittal pelvic tilt (SPT) in total hip arthroplasty (THA) patients.

Methods

We reviewed 19 hip osteoarthritic patients undergoing THA with or without lumbar fusion. The gender, age, primary disease, Deyo comorbidity score, and year of surgery were sorted and matched. All patients were followed up for at least 12 months. They were compared in terms of the SPT angle, Harris hip score (HHS) and complications.

Results

On average, the patients receiving lumbar fusion had a − 3.9 (95% CI − 7.7 to − 1.5) degrees of SPT before THA and − 2.7 (95% CI − 6.5 to 1.1) degrees postoperatively, and the THA patients without lumbar fusion averaged 2.5 (95% CI − 0.1 to 5.0) degrees and 4.2 (95% CI 2.0 to 6.4) degrees, respectively. In the lumbar fusion patients, the mean SPT was − 3.9 (95% CI − 9.9 to 2.0) degrees with L5S1 fusion and − 4.0(95% CI − 10.0 to 2.1) degrees without L5S1 fusion on the standing radiograph before THA (t = 0.01, P = 0.99). The mean SPT was − 1.2 (95% CI − 4.9 to 2.6) degrees with one- and two-segment fusion and − 10.0 (95% CI − 18.5 to 1.5) degrees with three- and four-segment fusion before THA (t = 2.60, P = 0.02). There was no statistically significant difference in cup inclination and cup anteversion after THA between the lumbar fusion and control groups. These patients in the two groups achieved a similar HHS 12 months after THA despite the fact that they had different SPT and HHS before THA.

Conclusion

Lumbar fusion appears to increase the posterior SPT by approximately 6 degrees in the patients undergoing THA. Lumbar fusion of more than two segments is a predictor of more posterior SPT changes, but fusion of L5S1 is not.

Timing of Lumbar Spinal Fusion Affects Total Hip Arthroplasty Outcomes

Many patients are affected by concurrent disease of the hip and spine, undergoing both total hip arthroplasty (THA) and lumbar spinal fusion (LSF). Recent literature demonstrates increased prosthetic dislocation rates in patients with THA done after LSF. Evidence is lacking on which surgery to do first to minimize complications. The purpose of this study was to evaluate the effect of timing between the two procedures on postoperative outcomes.

A Geometric Model to Determine Patient-Specific Cup Anteversion Based on Pelvic Motion in Total Hip Arthroplasty

Introduction

Cup position is critical to stability in total hip arthroplasty and is affected by pelvis motion during positions of daily life. The purpose of this study was to explicitly define the relationship between sagittal pelvic motion and resultant cup functional anteversion and create a tool to guide the surgeon to a patient-specific intra-operative anteversion.

Materials and Methods

10,560 combinations of inclination, anteversion, and pelvic tilt were generated using a geometric model. Resultant functional anteversion was calculated for each iteration and variables were correlated. An electronic mobile tool was created that compares inputted patient-specific values to population-based averages to determine pelvic positions and dynamics that may lead to instability.

Results

A third-degree polynomial equation was used to describe the relationship between variables. The freely downloadable mobile tool uses input from pre-operative plain radiographic measurements to provide the surgeon a quantitative correction to intra-operative cup anteversion based on differences in functional anteversion compared to population-based averages.

Conclusion

This study provides a geometric relationship between planned cup position, pelvic position and motion, and the resultant functional anteversion. This mathematical model was applied to an electronic tool that seeks to determine an individualized intra-operative cup anteversion based on measured patient-specific pelvic dynamics.

Does Compensatory Anterior Pelvic Tilt Decrease After Bilateral Periacetabular Osteotomy?

BACKGROUND

The kinetic link among the lumbar spine, pelvic tilt, and the hip has been hypothesized, but this relationship requires further study in acetabular dysplasia. Anecdotal reports suggest that patients may compensate for acetabular dysplasia with an involuntary increase in anterior pelvic tilt; it is not known if this relationship is affected by acetabular reorientation.

QUESTIONS/PURPOSES

(1) Does compensatory pelvic tilt decrease on preoperatively obtained standing AP pelvis radiographs compared with those obtained at a minimum of 6 months after bilateral periacetabular osteotomy (PAO)? (2) Does a modified surrogate measurement of pelvic tilt, the pubic symphysis to sacroiliac (PS-SI) index, correlate with a physical synthetic bones model in which pelvic tilt can be directly measured? (3) Can the PS-SI index demonstrate high interrater reliability?

METHODS

We assessed the surgical records of one surgeon, who participates in the longitudinally maintained Academic Network of Conservational Hip Outcomes Research (ANCHOR) registry, for patients who had undergone the second side of a staged bilateral PAO between 2007 and 2016; there were 113 such patients. Of those, 70 (62%) were lost to followup within 6 months of the second PAO or did not have adequate imaging studies, and another three (3%) were excluded for prespecified reasons, leaving 40 (35%) for evaluation in this retrospective study. Standing preoperative and most recent postoperative AP pelvis radiographs were used to measure the Tönnis angle, anterior wall index, posterior wall index, lateral center-edge angle, pubis symphysis-to-sacrococcygeal junction distance, and the PS-SI index. The most recent radiographs were obtained at a mean of 16 ± 6 months after the second PAO. We chose 6 months as the minimum because at this time point, the majority of patients have reached their maximum clinical improvement and are no longer limited by postoperative muscle dysfunction. Statistical analysis was performed using the intraclass correlation coefficient (ICC) for interrater reliability and paired t-tests for assessing change in measurements from pre- to postoperative. Additionally, a model was created using a physical synthetic bones model in which pelvic tilt could be directly measured. This model was secured through bilateral acetabuli on a mount and rotated through 5° increases in pelvic tilt. AP pelvis radiographs were obtained at each point, the PS-SI index was measured, and a regression analysis performed to evaluate for trend.

RESULTS

Overall, 37 of 40 patients (93%) had a decrease in pelvic tilt, as measured by the PS-SI index. The mean amount of pelvic tilt as measured by the PS-SI index decreased after surgery when comparing the preoperative with latest radiographs on this parameter (97 ± 14 mm versus 89 ± 13 mm, mean difference 8 ± 9 mm; 95% confidence interval, -11 to -5; range 17 increase to 24 decrease, p < 0.001). A linear relationship between pelvic tilt and PS-SI index (PS-SI index = 5.0° + 3.6° tilt, R = 0.99) was identified in the synthetic bones validation model. Finally, the interrater reliability was found to be excellent for the PS-SI index preoperatively (ICC = 0.986) and postoperatively (ICC = 0.988).

CONCLUSIONS

We found a modest reduction in anterior pelvic tilt after bilateral PAO. This finding suggests that acetabular reorientation affects pelvic position. In clinical practice, patients with acetabular dysplasia may compensate with dynamic and reversible changes in pelvic tilt. The PS-SI index is a reproducible tool to measure the height of the pelvic inlet as an assessment of pelvic tilt. In the future, clinical studies should evaluate the clinical implications of these radiographic findings, including the assessment of back pain, which although multifactorial may be influenced by pelvic tilt.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Total Hip Arthroplasty Patients With Fixed Spinopelvic Alignment Are at Higher Risk of Hip Dislocation

BACKGROUND

Sitting radiographs have been used as a pre-operative tool to plan patient-specific total hip arthroplasty (THA) component position that would improve hip stability. Previous work has demonstrated that spinal mobility may impact functional acetabular position when seated. We sought to determine whether patients who dislocate following THA have different sitting spinopelvic alignment or acetabular component orientation compared to patients who did not dislocate.

METHODS

A consecutive series of 1000 patients underwent post-operative low-dose biplanar spine-to-ankle lateral radiographs in standing and sitting positions 1 year following THA. Twelve patients (1% of all patients) experienced hip dislocation. Patients were categorized as having normal lumbar spines (without radiographic arthrosis) or as having lumbar multi-level degenerative disc disease. Measurements of spinopelvic alignment parameters (including sacral slope, lumbar lordosis, and proximal femur angles) and acetabular component orientation in sitting position (functional inclination and functional anteversion) were performed.

RESULTS

Patients who dislocated had significantly less spine flexion, less change in pelvic tilt, and more hip flexion from standing to sitting positions compared to patients with normal spines. In sitting position, dislocators had acetabular components with less functional inclination and less functional anteversion.

CONCLUSION

This study demonstrates that patients with fixed spinopelvic alignment from standing to sitting position are at higher risk of hip dislocation. Imaging patients from standing to sitting position using this technique can provide valuable information on whether a patient has fixed spinopelvic alignment with postural changes and is therefore at higher risk of dislocation.

The Impact of Spino-Pelvic Alignment on Total Hip Arthroplasty Outcomes: A Critical Analysis of Current Evidence

BACKGROUND

In this review, we (1) evaluated the effect of adult spine deformity (ASD) and its surgical correction on patients who had a total hip arthroplasty (THA); (2) evaluated the outcomes of THA in patients who have had previous spinal fusion; and (3) we presented an algorithm on how to surgically address patients who simultaneously require THA and ASD correction.

METHODS

A comprehensive literature search was conducted. Our final analysis included 14 studies. Overall, there were 3 studies that reported on the impact of ASD on THA outcomes, 6 studies reported on the effect of ASD correction on THA outcomes, and 5 studies reported on the effect of spinal fusion on THA outcomes.

RESULTS

Patients with concurrent ASD and THA are at increased risk of THA dislocations and revisions with studies reporting a compiled 2.9% dislocation rate in 1167 patients. Patients who underwent ASD correction demonstrated a post-operative reduction of acetabular anteversion (mean reduction range 4.96°-11.2°, P < .001) and tilt (mean -7° ± 10°, P < .001). In THA patients with concurrent lumbosacral fusion, dislocation rates ranged between 3% at 1 year and 7.5% at 2 years compared to 0.4%-2.1% dislocation rates in matching cohorts (P < .001).

CONCLUSION

Spine balance can alter THA outcomes, but the exact mechanism is yet to be elucidated. We aimed at bridging the gap between hip and spine surgeons with an up-to-date analysis of the best available evidence and presented an algorithm for approaching patients who may simultaneously need ASD correction and THA.