ABSTRACT

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.

INTRODUCTION

The concept of hip-spine syndrome was introduced in 1983 by Offierski and MacNab and was used to describe patients with coexisting hip arthrosis and lumbar spine disorders [1]. Pathology of the lumbar spine and hip can often have overlapping symptoms which can present a diagnostic and therapeutic dilemma for clinicians [2]. A majority of the literature on hip-spine syndrome is described in the setting of hip arthroplasty [3–5], but there has been a recent interest in its influence on hip arthroscopy [6–9].

It has been established that spinopelvic motion can influence acetabular position, and stiffness in the lumbar spine forces the hip to make up for that lack of motion to allow for daily activities such as sitting [10–13]. The literature on the influence of hip-spine syndrome on hip arthroscopy outcomes has mainly evaluated patients with low back pain, radicular symptoms or prior lumbar surgery [6–8, 14, 15]. More recently, Heaps et al. [16] reported that patients with lumbosacral transitional vertebrae (LSTV) had less benefit after hip arthroscopy as demonstrated by lower patient-reported outcome scores (PROs) 24–35 months postoperative compared to patients without LSTV. In their paper they proposed the importance of lumbosacral motion loss on outcomes in hip arthroscopy due to the possibility of residual FAI even after surgical correction. Conversely, Luo et al. [17] performed a large retrospective cohort study which was unable to establish inferior outcomes in patients with LSTV compared to controls. Given the evidence that spine pathology causing decreased lumbar mobility can potentially compromise outcomes after hip arthroscopy, normal anatomic variants that limit spinopelvic motion may have similar effects.

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). It was hypothesized that (i) patients with LM would demonstrate favorable PROs at minimum 1-year follow-up and (ii) clinical results would be inferior to those of a propensity-matched control group of NM patients.

MATERIALS AND METHODS Patient selection

Data were prospectively collected and retrospectively reviewed on consecutive patients who underwent primary hip arthroscopy between November 2019 and March 2020 in the setting of FAIS. Patients were included in the analysis if they had preoperative and minimum 1-year follow-up PROs for the modified Harris Hip Score (mHHS) [18], the Nonarthritic Hip Score (NAHS) [19], the International Hip Outcome Tool-12 (iHOT-12) [20] and the Visual Analog Scale (VAS) for pain [21]. Patients were excluded from analysis if they had a previous diagnosed ipsilateral hip or lumbar spine condition (e.g. avascular necrosis, slipped capital femoral epiphysis or Legg–Calvé–Perthes disease) or were not diagnosed with FAIS. As per established literature, patients were defined as having limited lumbopelvic motion if they had a seated to standing change in sacral slope ≤ 10° [22].

Participation in the (X.X.X.) registry

Some data may have been reported in other studies from this institution; however, this study provides a unique analysis. An institutional review board has approved all data collection.

Radiographic evaluation

Radiographic imaging, including the standing and supine anteroposterior pelvis, modified 45° Dunn and false-profile view, was acquired and reviewed before surgery [23–26]. These images were evaluated using the General Electric Healthcare’s Picture Archiving and Communication System. The anteroposterior supine view was used to assess the level of osteoarthritis as graded with the Tönnis system [27] and the lateral center-edge angle of Wiberg [28] as modified by Ogata et al. [29]. The standing and seated lateral spinal views were used to measure the sacral slope. Sacral slope was defined as the angle subtended by a line parallel to the superior endplate of S1 relative to the horizontal plane (Fig. 1). Limited spinal mobility was defined by less than a 10° change in sacral slope from the standing to seated positions [22, 30–32]. In addition, proximal femoral angle was measured in both the standing and seated positions according to previously described methods [33]. The proximal femoral angle was measured between a vertical line and the line defined by the anterior cortex of the most visible femur. Flexion of the hip joint was calculated by adding the change in position of the proximal femur to the change in position of the pelvis (using the sacral slope angle) by subtracting the sitting position values from standing position values [13]. The institution’s radiographic measurements have demonstrated good interobserver reliability in previously published studies [34–36]. A magnetic resonance arthrography was also obtained from each patient to evaluate for a labral tear and to diagnose other intra-articular and extra-articular pathologies.

Fig. 1.

Sacral slope measurements (yellow lines) on standing (A) and seated (B) x-rays.

Fig. 1.

Sacral slope measurements (yellow lines) on standing (A) and seated (B) x-rays.

Surgical indications and procedures

Surgery was recommended by the senior author (Y.Y.Y.) for patients with diagnosis of FAIS. These patients also presented with hip pain for at least 3 months with no relief from conservative treatment including physical therapy, injections, nonsteroidal anti-inflammatory drugs and activity modification [37].

All arthroscopies were performed by one orthopedic surgeon (Y.Y.Y.). In the operating room, patients received general anesthesia and were placed in a modified supine position on a traction table [38]. The surgeon accessed the joint through the anterolateral, mid-anterior and distal anterolateral portals [39]. An interportal capsulotomy was then performed and a diagnostic arthroscopy was carried out to assess the hip pathology. The Domb and Villar systems were used to classify the ligamentum teres [40, 41]. The Seldes system was used to grade the labral pathology [41]. Cartilage damage on the acetabulum and femoral head were classified by the Outerbridge system [43]. The acetabular labrum articular disruption (ALAD) was used to grade the chondrolabral junction [44].

Procedures varied based on each patient’s hip pathology. Labral tears were either repaired, selectively debrided or reconstructed [45, 46]. Fluoroscopic guidance and a 5.5-mm burr were used to perform a femoroplasty, acetabuloplasty or subspine decompression to treat cam morphology, pincer morphology or subspine impingement, respectively [47]. Repair or plication of the capsule was performed based on the patient’s range of motion, ligamentous laxity and acetabular coverage [48, 49].

Surgical outcome tools

Patients were assessed preoperatively, 3 months postoperatively and annually thereafter. Outcome scores were computed from questionnaires completed during clinic visits, over the telephone or over encrypted email. Questionnaires included the mHHS [18], the NAHS [19], the International Hip Outcome Tool-12 (iHOT-12) [50] and the VAS for pain [21]. mHHS, NAHS and iHOT-12 were measured on a scale of 0 to 100. VAS was measured on a scale of 0 to 10. The threshold for achievement of the minimal clinically important difference was calculated for mHHS, NAHS and iHOT-12 [51]. The patient acceptable symptomatic state (PASS) thresholds were calculated for mHHS and iHOT-12 based on previously published literature [52]. The rates of achievement of the maximum outcome improvement satisfaction thresholds were also recorded based on thresholds set by previously published literature [53].

Propensity score matching and statistical analysis

To allow for adequate sample size for analysis, patients were divided into two groups: patients with change in seated to sanding sacral slopes ≤ 10° (LM) and those with changes > 10° (NM). Patients were then matched according to age, sex and body mass index (BMI). The propensity score matching was done in a 2:1 ratio without replacement and to the nearest Euclidean distance. The matched cohorts excluded any patients who fell outside a caliper of 0.2 times the standard deviation of the logit propensity scores. Data were summarized using mean and standard deviation or proportion where appropriate. Normality and equality of variance were measured with the Shapiro–Wilk test and the F-test, respectively. The two-tailed t-test of its nonparametric equivalent was used for continuous data, while the Fisher exact test or chi-square test was used to compare categorical data. A threshold P value of 0.05 was used to determine statistical significance. Based on the assumption that a mean difference of nine points in follow-up mHHS between groups is clinically important, an a priori power analysis was used to determine that in a 1:2 matching ratio, 16 study cases and 31 control cases were necessary to achieve at least 80% power [54]. All analyses were conducted in Microsoft Excel with the Real Statistics Add-in package (Microsoft Corporation; Redmond, WA).

RESULTS

Demographic data for all patients are provided in Table I. Sixty-six patients (66 hips) were eligible, of which 54 patients had adequate follow-up (81.8%). Of the 54 patients with adequate follow-up data, 51 were matched into two groups based on spinal mobility: 34 (66.7%) patients were classified as normal spinal mobility and 17 (33.3%) patients had limited spinal mobility. Three patients in the study group (limited mobility) were male (17.6%) and 14 were female (82.4%), while 12 patients in the control group (normal mobility) were male (35.3%) and 22 were female (64.7%).

Table I.

Patient characteristics and demographic factorsa

. Spinal mobility .  .  . Limited . Normal . P value . Number of hips 17 34  Sex   0.192 Male 3 (18) 12 (35)  Female 14 (82) 22 (65)  Follow-up time, months 12.54 ± 0.68 (12.00–14.40) 12.25 ± 0.37 (12.00–13.19) 0.167 Age at surgery, years 39.85 ± 17.22 (12.72–76.41) 31.98 ± 13.82 (14.75–70.92) 0.127 BMI, kg/m2 25.50 ± 4.45 (20.44–33.89) 25.63 ± 5.41 (18.79–38.07) 0.976  . Spinal mobility .  .  . Limited . Normal . P value . Number of hips 17 34  Sex   0.192 Male 3 (18) 12 (35)  Female 14 (82) 22 (65)  Follow-up time, months 12.54 ± 0.68 (12.00–14.40) 12.25 ± 0.37 (12.00–13.19) 0.167 Age at surgery, years 39.85 ± 17.22 (12.72–76.41) 31.98 ± 13.82 (14.75–70.92) 0.127 BMI, kg/m2 25.50 ± 4.45 (20.44–33.89) 25.63 ± 5.41 (18.79–38.07) 0.976 Table I.

Patient characteristics and demographic factorsa

. Spinal mobility .  .  . Limited . Normal . P value . Number of hips 17 34  Sex   0.192 Male 3 (18) 12 (35)  Female 14 (82) 22 (65)  Follow-up time, months 12.54 ± 0.68 (12.00–14.40) 12.25 ± 0.37 (12.00–13.19) 0.167 Age at surgery, years 39.85 ± 17.22 (12.72–76.41) 31.98 ± 13.82 (14.75–70.92) 0.127 BMI, kg/m2 25.50 ± 4.45 (20.44–33.89) 25.63 ± 5.41 (18.79–38.07) 0.976  . Spinal mobility .  .  . Limited . Normal . P value . Number of hips 17 34  Sex   0.192 Male 3 (18) 12 (35)  Female 14 (82) 22 (65)  Follow-up time, months 12.54 ± 0.68 (12.00–14.40) 12.25 ± 0.37 (12.00–13.19) 0.167 Age at surgery, years 39.85 ± 17.22 (12.72–76.41) 31.98 ± 13.82 (14.75–70.92) 0.127 BMI, kg/m2 25.50 ± 4.45 (20.44–33.89) 25.63 ± 5.41 (18.79–38.07) 0.976 

There were significant differences for several radiographic measurements between the two groups. The sitting sacral slope for the study group was significantly higher than the control group (P < 0.001). The sacral slope deltas were also statistically significant (P < 0.001). Additionally, the standing proximal femoral angles were significantly lower in the study group (P = 0.033). The femoroacetabular flexion angle was significantly higher in the study group (P < 0.001). Complete radiographic data can be found in Table II.

Table II.

Radiographic measurementsa

. Spinal mobility .  .  . Limited . Normal . P value . Sacral slope    Sitting 30.62 ± 8.94 19.35 ± 9.70 <0.001 Standing 36.25 ± 9.40 41.80 ± 11.54 0.093 Delta 5.64 ± 2.19 22.46 ± 9.58 <0.001 Proximal femoral angle Sitting 88.43 ± 2.82 88.84 ± 3.70 0.792 Standing 4.29 ± 2.19 6.34 ± 4.48 0.033 Femoroacetabular flexion angle 78.5 ± 5.84 60.05 ± 11.51 <0.001  . Spinal mobility .  .  . Limited . Normal . P value . Sacral slope    Sitting 30.62 ± 8.94 19.35 ± 9.70 <0.001 Standing 36.25 ± 9.40 41.80 ± 11.54 0.093 Delta 5.64 ± 2.19 22.46 ± 9.58 <0.001 Proximal femoral angle Sitting 88.43 ± 2.82 88.84 ± 3.70 0.792 Standing 4.29 ± 2.19 6.34 ± 4.48 0.033 Femoroacetabular flexion angle 78.5 ± 5.84 60.05 ± 11.51 <0.001 Table II.

Radiographic measurementsa

. Spinal mobility .  .  . Limited . Normal . P value . Sacral slope    Sitting 30.62 ± 8.94 19.35 ± 9.70 <0.001 Standing 36.25 ± 9.40 41.80 ± 11.54 0.093 Delta 5.64 ± 2.19 22.46 ± 9.58 <0.001 Proximal femoral angle Sitting 88.43 ± 2.82 88.84 ± 3.70 0.792 Standing 4.29 ± 2.19 6.34 ± 4.48 0.033 Femoroacetabular flexion angle 78.5 ± 5.84 60.05 ± 11.51 <0.001  . Spinal mobility .  .  . Limited . Normal . P value . Sacral slope    Sitting 30.62 ± 8.94 19.35 ± 9.70 <0.001 Standing 36.25 ± 9.40 41.80 ± 11.54 0.093 Delta 5.64 ± 2.19 22.46 ± 9.58 <0.001 Proximal femoral angle Sitting 88.43 ± 2.82 88.84 ± 3.70 0.792 Standing 4.29 ± 2.19 6.34 ± 4.48 0.033 Femoroacetabular flexion angle 78.5 ± 5.84 60.05 ± 11.51 <0.001 

Intraoperative findings are presented in Table III. The distribution of Seldes-defined labral tear types was not significantly different between groups (P = 0.684), nor was the distribution of ALAD (P = 0.898). There was no significant difference in acetabular (P = 0.898) or femoral head (P = 0.204) Outerbridge lesions between the study and control groups. There was no significant difference between groups with respect to the distribution of ligamentum teres tear (P = 0.227).

. Spinal mobility .  .  . Limited . Normal . P value . Seldes type (labral tear)   0.684 I 7 (41) 17 (50)  II 2 (12) 2 (6)  I and II 8 (47) 14 (41)  ALAD   0.898 0 0 1 (3)  1 9 (53) 14 (41)  2 5 (29) 11 (32)  3 1 (6) 3 (9)  4 2 (12) 5 (15)  Outerbridge: acetabulum   0.898 0 0 1 (3)  1 9 (53) 14 (41)  2 5 (29) 11 (32)  3 1 (6) 3 (9)  4 2 (12) 5 (15)  Outerbridge: femoral head   0.204 0 15 (88) 33 (97)  1 0 0  2 1 (6) 0  3 1 (6) 0  4 0 1 (3)  Ligamentum teres tear percentile   0.227 0 5 (29) 16 (47)  1 5 (29) 11 (32)  2 5 (29) 5 (15)  3 2 (12) 2 (6)   . Spinal mobility .  .  . Limited . Normal . P value . Seldes type (labral tear)   0.684 I 7 (41) 17 (50)  II 2 (12) 2 (6)  I and II 8 (47) 14 (41)  ALAD   0.898 0 0 1 (3)  1 9 (53) 14 (41)  2 5 (29) 11 (32)  3 1 (6) 3 (9)  4 2 (12) 5 (15)  Outerbridge: acetabulum   0.898 0 0 1 (3)  1 9 (53) 14 (41)  2 5 (29) 11 (32)  3 1 (6) 3 (9)  4 2 (12) 5 (15)  Outerbridge: femoral head   0.204 0 15 (88) 33 (97)  1 0 0  2 1 (6) 0  3 1 (6) 0  4 0 1 (3)  Ligamentum teres tear percentile   0.227 0 5 (29) 16 (47)  1 5 (29) 11 (32)  2 5 (29) 5 (15)  3 2 (12) 2 (6)   . Spinal mobility .  .  . Limited . Normal . P value . Seldes type (labral tear)   0.684 I 7 (41) 17 (50)  II 2 (12) 2 (6)  I and II 8 (47) 14 (41)  ALAD   0.898 0 0 1 (3)  1 9 (53) 14 (41)  2 5 (29) 11 (32)  3 1 (6) 3 (9)  4 2 (12) 5 (15)  Outerbridge: acetabulum   0.898 0 0 1 (3)  1 9 (53) 14 (41)  2 5 (29) 11 (32)  3 1 (6) 3 (9)  4 2 (12) 5 (15)  Outerbridge: femoral head   0.204 0 15 (88) 33 (97)  1 0 0  2 1 (6) 0  3 1 (6) 0  4 0 1 (3)  Ligamentum teres tear percentile   0.227 0 5 (29) 16 (47)  1 5 (29) 11 (32)  2 5 (29) 5 (15)  3 2 (12) 2 (6)   . Spinal mobility .  .  . Limited . Normal . P value . Seldes type (labral tear)   0.684 I 7 (41) 17 (50)  II 2 (12) 2 (6)  I and II 8 (47) 14 (41)  ALAD   0.898 0 0 1 (3)  1 9 (53) 14 (41)  2 5 (29) 11 (32)  3 1 (6) 3 (9)  4 2 (12) 5 (15)  Outerbridge: acetabulum   0.898 0 0 1 (3)  1 9 (53) 14 (41)  2 5 (29) 11 (32)  3 1 (6) 3 (9)  4 2 (12) 5 (15)  Outerbridge: femoral head   0.204 0 15 (88) 33 (97)  1 0 0  2 1 (6) 0  3 1 (6) 0  4 0 1 (3)  Ligamentum teres tear percentile   0.227 0 5 (29) 16 (47)  1 5 (29) 11 (32)  2 5 (29) 5 (15)  3 2 (12) 2 (6)   Surgical procedures

Between the two groups, there were no significant differences in labral treatment (P = 0.392) or capsular treatment (P = 0.250). There were also no significant differences in treatments for FAI morphology or cartilage damage, including acetabuloplasty (P = 0.610), femoroplasty (P = 0.475) and acetabular microfracture (P = 0.207). Data for surgical procedures can be found in Table IV.

. Spinal mobility .  .  . Limited . Normal . P value . Labral treatment   0.392 Repair 15 (88) 30 (88)  Selective debridement 1 (6) 0  Reconstruction 1 (6) 2 (6)  Capsular treatment   0.250 Repair 17 (100) 29 (85)  Unrepaired capsulotomy 0 5 (15)  Acetabuloplasty 16 (94) 33 (97) 0.610 Femoroplasty 17 (100) 33 (97) 0.475 Microfracture acetabulum 0 3 (9) 0.207  . Spinal mobility .  .  . Limited . Normal . P value . Labral treatment   0.392 Repair 15 (88) 30 (88)  Selective debridement 1 (6) 0  Reconstruction 1 (6) 2 (6)  Capsular treatment   0.250 Repair 17 (100) 29 (85)  Unrepaired capsulotomy 0 5 (15)  Acetabuloplasty 16 (94) 33 (97) 0.610 Femoroplasty 17 (100) 33 (97) 0.475 Microfracture acetabulum 0 3 (9) 0.207  . Spinal mobility .  .  . Limited . Normal . P value . Labral treatment   0.392 Repair 15 (88) 30 (88)  Selective debridement 1 (6) 0  Reconstruction 1 (6) 2 (6)  Capsular treatment   0.250 Repair 17 (100) 29 (85)  Unrepaired capsulotomy 0 5 (15)  Acetabuloplasty 16 (94) 33 (97) 0.610 Femoroplasty 17 (100) 33 (97) 0.475 Microfracture acetabulum 0 3 (9) 0.207  . Spinal mobility .  .  . Limited . Normal . P value . Labral treatment   0.392 Repair 15 (88) 30 (88)  Selective debridement 1 (6) 0  Reconstruction 1 (6) 2 (6)  Capsular treatment   0.250 Repair 17 (100) 29 (85)  Unrepaired capsulotomy 0 5 (15)  Acetabuloplasty 16 (94) 33 (97) 0.610 Femoroplasty 17 (100) 33 (97) 0.475 Microfracture acetabulum 0 3 (9) 0.207  Patient-reported outcomes and clinical outcome thresholds

For all PROs, both groups improved significantly in preoperative scores to 1-year postoperative scores. There were no significant differences between groups in any preoperative or postoperative score or delta value. Complete PRO data can be found in Table V. Clinical outcome thresholds were also assessed, in which there were also no significant differences between groups in rates of achievement of these thresholds. These rates can be found in Table VI.

Table V.

Patient-reported outcomes after propensity score matchinga

. Spinal mobility .  .  . Limited . Normal . P value . mHHS    Preoperative 58.00 ± 11.78 (40–83) 62.39 ± 15.86 (34–100) 0.318 1 year 85.35 ± 16.76 (40–100) 84.03 ± 16.49 (43–100) 0.835 P value <0.001 <0.001  Delta 27.35 ± 17.24 (−14–52) 21.64 ± 15.85 (−22–46) 0.244 NAHS    Preoperative 59.78 ± 12.63 (40–81.25) 63.36 ± 14.53 (32.5–92.5) 0.391 1 year 87.06 ± 13.12 (52.5–100) 85.15 ± 14.71 (45–100) 0.744 P value <0.001 <0.001  Delta 27.28 ± 13.33 (−7.5–47.5) 21.79 ± 14.42 (−5–61.25) 0.195 VAS    Preoperative 4.69 ± 3.24 (0–8.52) 5.12 ± 2.19 (0–9.1) 0.622 1 year 1.91 ± 1.87 (0–5) 2.09 ± 2.19 (0–7) 0.961 P value 0.002 <0.001  Delta −2.78 ± 3.04 (−8.41–3.39) −3.04 ± 3.04 (−9.1–4.23) 0.776 iHOT-12    Preoperative 30.79 ± 16.12 (7.42–53.58) 35.06 ± 14.45 (12.62–59.73) 0.343 1 year 74.46 ± 23.54 (17.45–100) 74.50 ± 22.91 (17.31–100) 0.929 P value <0.001 <0.001  Delta 43.66 ± 24.83 (0.09–91.60) 39.44 ± 23.05 (−4.84–81.44) 0.550  . Spinal mobility .  .  . Limited . Normal . P value . mHHS    Preoperative 58.00 ± 11.78 (40–83) 62.39 ± 15.86 (34–100) 0.318 1 year 85.35 ± 16.76 (40–100) 84.03 ± 16.49 (43–100) 0.835 P value <0.001 <0.001  Delta 27.35 ± 17.24 (−14–52) 21.64 ± 15.85 (−22–46) 0.244 NAHS    Preoperative 59.78 ± 12.63 (40–81.25) 63.36 ± 14.53 (32.5–92.5) 0.391 1 year 87.06 ± 13.12 (52.5–100) 85.15 ± 14.71 (45–100) 0.744 P value <0.001 <0.001  Delta 27.28 ± 13.33 (−7.5–47.5) 21.79 ± 14.42 (−5–61.25) 0.195 VAS    Preoperative 4.69 ± 3.24 (0–8.52) 5.12 ± 2.19 (0–9.1) 0.622 1 year 1.91 ± 1.87 (0–5) 2.09 ± 2.19 (0–7) 0.961 P value 0.002 <0.001  Delta −2.78 ± 3.04 (−8.41–3.39) −3.04 ± 3.04 (−9.1–4.23) 0.776 iHOT-12    Preoperative 30.79 ± 16.12 (7.42–53.58) 35.06 ± 14.45 (12.62–59.73) 0.343 1 year 74.46 ± 23.54 (17.45–100) 74.50 ± 22.91 (17.31–100) 0.929 P value <0.001 <0.001  Delta 43.66 ± 24.83 (0.09–91.60) 39.44 ± 23.05 (−4.84–81.44) 0.550 Table V.

Patient-reported outcomes after propensity score matchinga

. Spinal mobility .  .  . Limited . Normal . P value . mHHS    Preoperative 58.00 ± 11.78 (40–83) 62.39 ± 15.86 (34–100) 0.318 1 year 85.35 ± 16.76 (40–100) 84.03 ± 16.49 (43–100) 0.835 P value <0.001 <0.001  Delta 27.35 ± 17.24 (−14–52) 21.64 ± 15.85 (−22–46) 0.244 NAHS    Preoperative 59.78 ± 12.63 (40–81.25) 63.36 ± 14.53 (32.5–92.5) 0.391 1 year 87.06 ± 13.12 (52.5–100) 85.15 ± 14.71 (45–100) 0.744 P value <0.001 <0.001  Delta 27.28 ± 13.33 (−7.5–47.5) 21.79 ± 14.42 (−5–61.25) 0.195 VAS    Preoperative 4.69 ± 3.24 (0–8.52) 5.12 ± 2.19 (0–9.1) 0.622 1 year 1.91 ± 1.87 (0–5) 2.09 ± 2.19 (0–7) 0.961 P value 0.002 <0.001  Delta −2.78 ± 3.04 (−8.41–3.39) −3.04 ± 3.04 (−9.1–4.23) 0.776 iHOT-12    Preoperative 30.79 ± 16.12 (7.42–53.58) 35.06 ± 14.4