Healing of joint capsule after hip arthroscopy using interportal capsulotomy and capsular closure influences clinical outcomes

Age and Preoperative Anterior Hip Capsule Thickness May Affect Capsule Healing in Patients With Femoroacetabular Impingement Syndrome Undergoing Arthroscopic Surgery Without Capsule Repair

Background

The capacity of an unrepaired joint capsule to heal after primary hip arthroscopic surgery in patients with femoroacetabular impingement syndrome (FAIS) remains uncertain. The factors that may contribute to nonhealing of the joint capsule are yet to be elucidated.

Purpose

To report the healing rate of the unrepaired joint capsule after primary hip arthroscopic surgery and to identify factors that may contribute to nonhealing.

Study Design

Case-control study; Level of evidence, 3.

Methods

Data collected between August 2015 and October 2023 were reviewed. Patients with FAIS aged 18 to 65 years who underwent hip arthroscopic surgery without capsule repair and had a minimum 6-month follow-up were included. Patient demographic data were collected including age at the time of surgery, sex, body mass index, laterality of the affected hip, follow-up duration, FAIS type, and intraoperative procedures. Capsule thickness was measured on preoperative magnetic resonance imaging. The status of capsule healing was evaluated on magnetic resonance imaging at least 6 months after surgery. The correlation between an unhealed capsule and various clinical factors was also evaluated.

Results

A total of 64 patients (66 hips) were included for analysis (48 hips in the healed group and 18 hips in the unhealed group). Age (44.50 ± 11.36 vs 38.44 ± 10.52 years, respectively; P = .045) and preoperative anterior capsule thickness (3.02 ± 0.87 vs 3.64 ± 1.01 mm, respectively; P = .025) were significantly different between the unhealed and healed groups. Other patient characteristics did not significantly differ between the groups. Higher age (ρ = -0.247; P = .045) and thinner anterior capsule (ρ = 0.276; P = .025) were associated with unhealed capsules. Receiver operating characteristic curve analysis showed that the optimal cut-off value for anterior capsule thickness to discriminate between healed and unhealed capsules was 3.35 mm, with a sensitivity and specificity of 0.667 and 0.667, respectively. The optimal cut-off value for age was 43 years, with a sensitivity and specificity of 0.667 and 0.604, respectively.

Conclusion

At a minimum 6-month follow-up, 27.2% of patients with FAIS who underwent primary arthroscopic surgery had unhealed anterior hip capsules. Both higher age and lower preoperative anterior hip capsule thickness may affect capsule healing in patients with FAIS who undergo primary arthroscopic surgery without capsule repair.

Arthroscopic Management of Femoroacetabular Impingement: Current Concepts

Background: Femoroacetabular impingement (FAI) is a common cause of hip pain and dysfunction, especially in young and active individuals, and it may require surgical management for associated labral tears and cartilage damage. The management of FAI has advanced radically over the last few years, and hip arthroscopy has gained a leading role. However, despite the increasing number of published research and technological advancements, a comprehensive systematic review summarising current evidence is still missing. Methods: All the clinical studies investigating the arthroscopic management of FAI were accessed. Only studies with a minimum of six months of follow-up were considered. The 2020 PRISMA guidelines were followed. In December 2024, PubMed, Web of Science, and Embase were accessed without time constraints. Results: The present systematic review included 258 clinical investigations (57,803 patients). The mean length of follow-up was 34.2 ± 22.7 months. The mean age was 34.7 ± 5.3, and the mean BMI was 25.1 ± 2.0 kg/m2. Conclusions: The present systematic review updates current evidence on patients who have undergone arthroscopic surgery for FAI, updating and discussing current progress in managing labral injuries and patient selection, emphasising outcomes and pitfalls. Progress in surgery and improvement in eligibility criteria, as well as current controversies and prospects, were also discussed.

Female Sex, Capsular Laxity, and Heightened Beighton Test Score, Femoral Torsion Angle, Neck-Shaft Angle Decrease Whereas Hip Inflammatory Disease and Capsular Repair Increase Hip Capsular Thickness: A Systematic Review

PURPOSE

To systematically review factors affecting hip capsule thickness.

METHODS

The review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The terms "hip," "arthroscopy," "capsule," "capsular," and "thickness" were used to search the PubMed, Ovid [MEDLINE], Cochrane Database, and EMBASE databases from inception to January 15, 2024.

RESULTS

The initial search identified 1,735 studies. Twenty-three studies were included in the systematic review. Eight reported the relationship between sex and capsule thickness. Seven reported that capsule thickness was significantly lower in women. Of the 4 studies reporting the relationship between capsular laxity and capsule thickness or Beighton test score (BTS), 4 studies showed the association of lower capsule thickness in patients with capsular laxity or BTS ≥4. Of the 6 studies reporting the relationship between arthroscopic surgery and capsular thickness, 2 showed significantly greater capsule thickness after capsulotomy with repair and 2 found significantly decreased postoperative capsule thickness without repair. One study illustrated that anterior capsule thickness was significantly smaller in patients with femoral torsion angle >20°. One study showed that neck-shaft angle was negatively corelated with anterior capsule thickness. Of the 3 studies that examined lateral central edge angle, 2 reported that lower angle correlated with thinner capsule thickness; one study reported the opposite result. Hip inflammatory disease was associated with thicker hip capsule.

CONCLUSIONS

Female sex, capsular laxity, BTS ≥4, greater femoral torsion angle, and greater neck-shaft angle were associated with a thinner hip capsule. Hip inflammatory disease and capsule repair after arthroscopic surgery were associated with a thicker capsule.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I-IV studies.

No Significant Differences in Clinical Outcomes Were Observed Between Healed and Unhealed Hip Joint Capsules in Femoroacetabular Impingement Syndrome After Arthroscopy

PURPOSE

To explore the healing status of interportal capsulotomies without repair after arthroscopy in patients with femoroacetabular impingement syndrome (FAIS) and to examine its correlation with clinical outcomes, including the relationship with age and sex subgroups.

METHODS

Data collected between August 2015 and January 2022 were reviewed. Patients with FAIS aged 18 to 65 years who underwent hip arthroscopy with interportal capsulotomies without repair with a minimum 2-year follow-up were included. Patients with a lateral center-edge angle of less than 25°, Tönnis grade greater than 1, Perthes disease, slipped upper femoral epiphysis, avascular necrosis, prior ipsilateral hip injury or surgery, and absence of magnetic resonance imaging at final follow-up were excluded. Patients were divided into healed and unhealed capsule groups according to magnetic resonance imaging evaluation. The primary patient-reported outcome (PRO) was the modified Harris Hip Score (mHHS). The secondary PROs were the Hip Outcome Score-Activities of Daily Living subscale, Hip Outcome Score-Sport Specific subscale, University of California at Los Angeles score, and visual analog scale pain score at final follow-up. The percentages of patients achieving the minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) for the PROs were also calculated.

RESULTS

The cohort comprised 69 patients (72 hips), with 28 hips (38.89%) in the unhealed capsule group and 44 hips (61.11%) in the healed capsule group. The cohort comprised 32 male and 37 female patients, and the mean age of the patients was 44.15 years. Within each group, there were significant preoperative-to-postoperative increases in the mHHS, Hip Outcome Score-Activities of Daily Living, Hip Outcome Score-Sport Specific subscale, and University of California at Los Angeles score and decreases in the visual analog scale pain score (all P < .001). There were no significant differences between the healed and unhealed groups in the PROs and the achievement rates of the MCID and PASS (all P > .05). In addition, compared with the healed group, the unhealed group showed worse mHHS values in patients older than 40 years (P = .003) and female patients (P = .036) on subgroup analysis by age and sex, respectively.

CONCLUSIONS

At a minimum 2-year follow-up, 38.89% of patients with FAIS who underwent arthroscopic surgery with interportal capsulotomy without repair had unhealed hip capsules. There were no significant differences in PROs or achievement rates of the MCID and PASS between the healed and unhealed groups. Subgroup analysis showed that age older than 40 years and female sex may be associated with worse efficacy in patients with unhealed capsules.

LEVEL OF EVIDENCE

Level III, retrospective case-control study.

Routine Capsular Closure Outperforms Incomplete Capsular Closure Following Hip Arthroscopy: A Meta-Analysis and Expected-Value Decision Analysis

PURPOSE

To determine the optimal treatment decision for capsular management after primary hip arthroscopy for femoroacetabular impingement syndrome.

METHODS

An expected-value decision analysis was performed, (1) Organizing the decision problem, (2) determining outcome probabilities, (3) determining outcome utilities, (4) performing fold-back analyses, (5) performing sensitivity analyses. A decision tree was constructed (complete capsule closure vs incomplete closure) and a meta-analysis was conducted. Utilizing the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) framework, a systematic review was conducted to determine outcome probabilities. The protocol for this systematic review and meta-analysis was registered with PROSPERO (ID CRD42023458012). Sixty-five patients with hip pain were evaluated for demographics, Hip Activity Level (HAL) and surgical outcome preferences. Statistical fold-back analysis was calculated to determine the optimal treatment strategy. One-way sensitivity analysis evaluated the impact of varying outcome likelihoods in decision-making.

RESULTS

Fold-back analysis showed the expected value for hip capsule complete closure was 8.60; the expected value for incomplete closure was 8.06. One-way sensitivity analysis of moderate complication shows that incomplete closure is favored when moderate complication probability following hip arthroscopy exceeds 16%. Meta-analysis of 17 studies and 3191 hips revealed the probability of a well outcome was greater for complete capsule closure 90.3% (95% CI 88.9%-92.0%) compared to capsule incomplete closure 83.2% (95% CI 80.9%-85.3%) (p < .000001). Fifty of sixty-five surveyed participants [mean age = 42.9 (SD 11.9), female = 66%] met inclusion criteria.

CONCLUSIONS

The current meta-analysis and expected-value decision analysis demonstrated hip capsule complete closure as the superior capsular management technique based on greater expected value than incomplete capsular closure. This study demonstrated increased proportion of well outcomes with decreased rates of moderate (requiring revision hip arthroscopy) and major (requiring early conversion to Total Hip Arthroplasty [THA]) complications.

LEVEL OF EVIDENCE

III, meta-analysis of Level I-III studies with high heterogeneity.

Hip Rotation and Femoral Anteversion and Its Influence on Traction Force of the Pulled Limb in Hip Arthroscopy

Background

Several variables may affect the traction force during hip arthroscopy. Specifically, the degree of hip joint rotation may influence the magnitude of traction force during hip arthroscopy. However, there is currently limited research available on this particular issue.

Purpose

To quantify the traction force applied to the pulled limb in various traction states and rotational positions. Additionally, the study aimed to investigate potential correlations between femoral anteversion, BMI, anesthesia methods, and the traction force required for hip dislocation.

Hypothesis

It was hypothesized that traction force in different traction states and rotational positions would be different and that femoral anteversion, body mass index (BMI), and anesthesia methods may influence the traction force needed.

Study Design

Cross-sectional study; Level of evidence, 4.

Methods

Patients who attended the sports medicine clinic of our department and underwent arthroscopic surgery for the diagnosis of femoroacetabular impingement between June and December 2022 were retrospectively evaluated. The traction force at the following 6 key timepoints was measured-initial traction, traction to the operable width, after joint puncture, after capsulotomy, at 20 minutes after capsulotomy, and at 40 minutes after capsulotomy. In each state, the hip was rotated to the internal rotational position, external rotational position, and neutral position. The traction force at different states and positions was recorded and analyzed. The differences in traction force between the different joint capsular physical states and rotational positions were tested by analysis of variance and the Tukey method. The Pearson test was used to analyze the correlation between BMI and femoral anteversion in different groups.

Results

A total of 41 patients were included in this study. The traction force increased after reaching the operable width and decreased significantly after capsulotomy (P < .05). Thereafter, the traction force decreased gradually over time (P < .05). Traction force in the external and internal rotational positions was significantly greater than that in the neutral position, across all states of traction (P < .05). Furthermore, the difference in traction force between the internal and neutral positions, as well as the difference in traction force between the external and neutral positions, was found to be significantly greater than the difference in traction force between the internal and external rotational positions in all traction states (P < .05). The difference between the traction forces in different rotational positions of the hip joint exhibited a negative correlation with femoral anteversion (Pearson correlation coefficient of neutral-internal in states 3, 4, and 5 was -0.33, -0.31, -0.31, respectively; P < .05) and a positive correlation with BMI (Pearson correlation coefficient of external-neutral in states 4 and 6 was 0.33 and 0.36, respectively; P < .05).

Conclusion

Our findings show that the traction force decreased after joint puncture and capsulotomy and decreased over time during surgery. External or internal rotation increased the traction force. Patients with higher femoral anteversion or lower BMI may need lower traction force. These data may help in minimizing traction forces to help prevent complications due to traction during hip arthroscopy.

Characterizations of Capsule Closure in Hip Arthroscopy Are Infrequently and Incompletely Reported: A Systematic Review

Purpose

To review the recent literature to provide an updated characterization of capsule closure techniques in hip arthroscopy and to determine if the characteristics of closure impacted clinical outcomes.

Methods

In keeping with the Preferred Reporting in Systematic Reviews and Meta Analyses (PRISMA) guidelines, a systematic review was performed with the following eligibility criteria: patients over 18 years of age who underwent primary hip arthroscopy with reporting of patient reported outcome measures or revision/failure, and a sufficiently detailed description of capsule closure. The GRADE framework evaluated study quality, and ROBINS-I evaluated the risk of bias.

Results

Across 18 studies (N = 3277) an interportal capsulotomy was reported in 12 studies (1972/3277) cases, and a T-type capsulotomy was reported in six studies (1305/3277) cases). Six studies reported using #2 suture. Nonabsorbable suture was reported in six studies, and absorbable suture in six studies. The rate of failure was 10.5% across five studies (N = 1133) and the rate of revision was 4.4% across 13 studies (N = 2957).

Conclusions

Capsule closure is commonly performed with #2 high strength suture-the T-type using two to three sutures in the vertical limb and two to three in the transverse limb, and the interportal type using two to three sutures. Compared to earlier reports, there is a trend for increased utilization of T-type capsulotomy. Although there is a growing body of investigations into the efficacy of routine capsule closure following hip arthroscopy, our results demonstrate infrequent and inconsistent reporting of capsule closure characteristics.

Level of Evidence

Level IV, systematic review of Level I-IV studies.

Eighty-One Percent of Unrepaired Interportal Capsulotomies Showed Healed Capsules on Magnetic Resonance Imaging 5 Years After Primary Hip Arthroscopy

Purpose

To evaluate whether unrepaired interportal capsulotomy presents with capsular defect on magnetic resonance imaging (MRI) 5 years after primary hip arthroscopy and to determine its effect on functional results and findings of osteoarthritis on radiographs or MRI scans.

Methods

Patients with femoroacetabular impingement (without arthritis or dysplasia) were retrospectively reviewed after arthroscopic labral repair or debridement and femoroplasty through interportal capsulotomy without closure. Patients were assessed preoperatively and at a minimum of 5 years postoperatively using patient-reported outcomes (Hip Outcome Score-Activities of Daily Living scale, modified Harris Hip Score, and visual analog scale pain score), radiographic measures, and MRI scans.

Results

Forty patients (42 hips) were deemed eligible for the study and were evaluated. Of the hips, 81% had healed capsules, whereas 8 (19%) had capsular defects on the latest MRI scan. There were 3 hips with subchondral edema in the defect group compared with 1 in the healed-capsule group (P = .01) on the latest MRI scan, which was not present on preoperative MRI (still positive on multivariate analysis when the preoperative alpha angle was also taken into consideration). Functional results did not differ between the groups (P > .05).

Conclusions

In this study, 81% of interportal capsulotomies healed without repair at 5 years after primary hip arthroscopy.

Clinical Relevance

Understanding the prevalence and implications of unhealed capsulotomies could encourage surgeons to be meticulous in capsular closure.

Predicting Outcomes in Hip Arthroscopy for Femoroacetabular Impingement Syndrome

PURPOSE OF REVIEW

Arthroscopic treatment of femoroacetabular impingement syndrome (FAIS) continues to rise in incidence, and thus there is an increased focus on factors that predict patient outcomes. The factors that impact the outcomes of arthroscopic FAIS treatment are complex. The purpose of this review is to outline the current literature concerning predictors of patient outcomes for arthroscopic treatment of FAIS.

RECENT FINDINGS

Multiple studies have shown that various patient demographics, joint parameters, and surgical techniques are all correlated with postoperative outcomes after arthroscopic FAIS surgery, as measured by both validated patient-reported outcome (PRO) scores and rates of revision surgery including hip arthroplasty. To accurately predict patient outcomes for arthroscopic FAIS surgery, consideration should be directed toward preoperative patient-specific factors and intraoperative technical factors. The future of accurately selecting patient predictors for outcomes will only improve with increased data, improved techniques, and technological advancement.

Ultrasound had high accuracy in measuring hip joint capsule thickness

BACKGROUND

The hip joint capsule is an essential component of hip joint function and stability, and its thickness is closely associated with certain medical conditions, surgical outcomes, and rehabilitation treatments. Currently, in clinical practice, hip joint capsule thickness is predominantly measured using magnetic resonance imaging (MRI), with limited utilization of ultrasound examinations for this purpose.

METHODS

We retrospectively evaluated patients who visited our Sports Medicine Department between February 2017 and March 2023 and underwent both hip joint MRI and ultrasound imaging on the same side. All patients had undergone preoperative hip joint MRI and ultrasound examinations, with the time gap between the two examinations not exceeding three months. Measurements of hip joint capsule thickness were taken on both MRI and ultrasound images for the same patients to analyze their consistency. Additionally, we measured the alpha angle, lateral center-edge angle, acetabular anteversion angle, and femoral anteversion angle of the patients' hip joints and analyzed their correlation with hip joint capsule thickness measure by ultrasound.

RESULTS

A total of 307 patients were included in this study, with hip joint capsule thickness measured by MRI and ultrasound being 5.0 ± 1.2 mm and 5.0 ± 1.5 mm, respectively. The Bland-Altman analysis demonstrates good agreement or consistency. The paired t-test resulted in a p-value of 0.708, indicating no significant statistical difference between the two methods. The correlation analysis between acetabular anteversion angle and ultrasound-measured capsule thickness yielded a p-value of 0.043, indicating acetabular anteversion angle and capsular thickness may have negative correlation.

CONCLUSIONS

The measurements of joint capsule thickness obtained through ultrasound and MRI showed good consistency, suggesting that ultrasound can be used in clinical practice as a replacement for MRI in measuring hip joint capsule thickness. There was a significant correlation between acetabular anteversion angle and hip joint capsule thickness, indicating potential for further research in this area.

Hip Arthroscopic Surgery With Chondrolabral Refixation, Osteochondroplasty, and Routine Capsular Closure for Femoroacetabular Impingement Syndrome: Clinical Outcomes at a Minimum 10-Year Follow-up

BACKGROUND

Hip arthroscopic surgery for femoroacetabular impingement syndrome (FAIS) has proven to be an effective surgical intervention, with high rates of return to sport and work as well as favorable outcomes at short- and midterm follow-up. However, limited data exist on outcomes at long-term follow-up.

PURPOSE

To evaluate patient-reported outcomes (PROs) at a minimum 10-year follow-up after primary hip arthroscopic surgery including labral repair, femoral osteochondroplasty, acetabular osteochondroplasty, and capsular closure for FAIS.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients who underwent primary hip arthroscopic surgery for FAIS between June 2012 and January 2013 were identified. PROs were collected preoperatively and at a minimum of 10 years postoperatively, including the Hip Outcome Score-Activities of Daily Living (HOS-ADL), Hip Outcome Score-Sports Subscale (HOS-SS), modified Harris Hip Score (mHHS), International Hip Outcome Tool-12 (iHOT-12), and visual analog scale (VAS) for pain and satisfaction. Unique minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) thresholds were calculated, and their rates of achievement were analyzed. An alpha level of <.05 was used to determine statistical significance.

RESULTS

A total of 94 patients (55 female; mean age, 34.3 ± 12.4 years) were analyzed with a mean follow-up of 10.1 ± 0.3 years (range, 10.0-10.7 years). Patients demonstrated significant 10-year improvement across all PRO measures (P < .001). MCID and PASS thresholds were calculated as follows: HOS-ADL (10.4 and 85.3, respectively), HOS-SS (14.6 and 60.2, respectively), mHHS (8.8 and 76.0, respectively), VAS pain (14.6 and 27.5, respectively), and iHOT-12 (PASS: 71.4). The majority of patients achieved the MCID and PASS for each PRO measure: HOS-ADL (73.4% and 70.9%, respectively), HOS-SS (78.5% and 77.2%, respectively), mHHS (81.0% and 70.9%, respectively), VAS pain (88.6% and 70.9%, respectively), and iHOT-12 (PASS: 73.4%). Overall, 9 patients (9.6%) underwent subsequent revision hip arthroscopic surgery at a mean 4.9 ± 3.7 years (range, 1.1-10.1 years) postoperatively, and 6 patients (6.4%) underwent conversion to total hip arthroplasty at a mean 4.1 ± 3.1 years (range, 0.9-9.3 years) postoperatively.

CONCLUSION

Patients who underwent primary hip arthroscopic surgery for FAIS utilizing contemporary methods of labral repair, acetabular and/or femoral osteochondroplasty, and capsular closure commonly experienced sustained clinical improvement and reported high levels of satisfaction at a minimum 10-year follow-up with low rates of reoperation.

Femoral Anteversion Is Associated With a Thinner Anterior Capsule in Patients With Femoroacetabular Impingement Syndrome

PURPOSE

To measure femoral torsion on computed tomography images in patients with femoroacetabular impingement syndrome and explore whether femoral torsion was significantly correlated with anterior capsular thickness.

METHODS

Prospectively collected data of surgical patients were retrospectively reviewed. Only patients aged 16 to 55 years who underwent primary hip surgery were included in this study. Patients with a history of revision hip surgery, previous knee surgery, hip dysplasia, hip synovitis, and/or incomplete radiographs and medical records were excluded from the study. Femoral torsion was measured via computed tomography imaging using transcondylar slices of the knee. Anterior capsular thickness was measured using oblique-sagittal sequences on a 3.0-T magnetic resonance imaging system. The association between anterior capsular thickness and related variables, including femoral torsion, was assessed via multiple linear regression. The patients were then divided into 2 groups to further confirm the effect of femoral torsion on capsular thickness: Patients in the study group had hips with moderate (20°-25°) or severe (>25°) antetorsion, whereas patients in the control group had hips with normal torsion (5°-20°) or retrotorsion (<5°). Anterior capsular thickness was also compared between the 2 groups.

RESULTS

A total of 156 patients (89 female patients [57.1%] and 67 male patients [42.9%]) were finally included in the study. The mean age and body mass index of the included patients were 35.8 ± 11.2 years and 22.7 ± 3.5, respectively. The mean femoral torsion for the entire study population was 15.9° ± 8.9°. Multivariable regression analysis showed that femoral torsion (P < .001) and sex (P = .002) were significantly correlated with anterior capsular thickness. Propensity-score matching yielded 50 hips in the study group and 50 hips in the control group on femoral torsion subanalysis. The results showed that anterior capsular thickness was significantly smaller in the study group than in the control group (3.8 ± 0.5 mm vs 4.7 ± 0.7 mm, P < .001).

CONCLUSIONS

Femoral torsion is significantly inversely correlated with anterior capsular thickness.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Femoral neck-shaft angle can predict the anterior capsular thickness in patients with femoracetabular impingement syndrome

PURPOSE

To measure the femoral neck-shaft angle (NSA) on computed tomography (CT) images in femoracetabular impingement syndrome (FAIS) patients and explore its relationship with the anterior capsular thickness (ACT).

METHODS

A retrospective review of prospectively collected data from 2022 was performed. Inclusion criteria included: primary hip surgery, 18 to 55 years of age, and CT imaging of the hips. Exclusion criteria included: revision hip surgery, mild or borderline hip dysplasia, hip synovitis, and incomplete radiographs and medical records. NSA was measured on CT imaging. ACT was measured using magnetic resonance imaging (MRI). Multiple linear regression was performed to assess the association between ACT and related variables, including age, sex, body mass index (BMI), lateral center-edge angle (LCEA), alpha angle, Beighton test score (BTS), and NSA.

RESULTS

A total of 150 patients were included. The mean age, BMI, and NSA were 35.8 ± 11.2 years, 22.8 ± 3.5, and 129.4° ± 7.7°, respectively. Eighty-five (56.7%) patients were females. Multivariable regression analysis revealed that NSA (P = 0.002) and sex (P = 0.001) were significantly negatively correlated with ACT. Age, BMI, LCEA angle, alpha angle, and BTS were not correlated with ACT.

CONCLUSIONS

This study confirmed that NSA significantly predicts ACT. A decrease in the NSA by 1° increases the ACT by 0.24 mm.

LEVEL OF EVIDENCE

Level III.