Age-Associated Pathology and Functional Outcomes After Hip Arthroscopy in Female Patients: Analysis With 2-Year Follow-up

Abstract

Background:

Previous research has demonstrated a statistically significant relationship between hip arthroscopy outcomes and age.

Purpose:

To investigate the link, if any, between hip arthroscopy outcomes and intraoperative pathology as well as with patient age and sex.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Of 272 female patients aged ≥14 years undergoing primary hip arthroscopy for femoroacetabular impingement between August 2010 and September 2017, and with 2-year patient-reported outcome scores, a total of 194 (71.3%) were included for final analysis. These patients were separated into 3 age-based cohorts: <30 years (n = 44), 30 to 45 years (n = 74), and >45 years (n = 76). Their data were then analyzed and compared with respect to patient characteristic information, intraoperative pathology, and functional outcome scores for statistical significance, which was set at P < .05.

Results:

When an analysis of variance was conducted for the 3 age groups at 2-year follow-up, there was a statistically significant difference for modified Hip Harris Score (P = .0003; <30 years, 88.26 ± 13.1 [mean ± SD]; 30-45 years, 82.68 ± 18.0; >45 years, 75.03 ± 19.5). The results of an analysis of variance comparing 2-year Non-arthritic Hip Score were also statistically significant (P = .0002; <30 years, 89.9 ± 13.7; 30-45 years, 85.8 ± 15.8; >45 years, 78.1 ± 17.2). Results of logistic regression demonstrated that the odds of a cam-type lesion decreased by 0.971 for every additional year in age among female patients. The odds of achieving the patient-acceptable symptomatic state decreased by a factor of 0.96 for each additional year in age (P < .0004).

Conclusion:

Surgical treatment of femoroacetabular impingement in females led to improved functional outcomes at 2 years of follow-up, although older female patients did worse after hip arthroscopy as compared with their younger counterparts. There may be an age-dependent decrease in incidence of cam-type lesions in female patients.

Keywords

female athletes hip arthroscopy femoroacetabular impingement

The use of hip arthroscopy to treat femoroacetabular impingement (FAI) has increased tremendously in recent years.² As with all rapidly expanding procedures with broadening indications, it is imperative to understand the outcomes of hip arthroscopy and how they differ among various populations.²² Several recent reviews have indicated that while the majority of current literature consists of low-level evidence, functional and radiographic outcomes improve after hip arthroscopy for FAI.^10,18 Two recent randomized controlled trials demonstrated improvement in functional outcomes for surgical management as compared with nonoperative therapy.^8,19 Previous research also showed a statistically significant relationship between hip arthroscopy outcomes and age. In a study by Frank et al,⁴ female patients aged >45 years had significantly worse outcomes than those aged 30 to 45 years and those aged <30 years.

To date, there has been no study examining the age-associated differences in patient-reported outcome scores and intraoperative pathology among female patients. The purpose of this study was to retrospectively analyze prospectively collected data for age-based associations in patient-reported outcomes as well as intraoperative pathologies among female patients. The hypothesis was that functional outcome scores would decrease as a function of age while observed intraoperative pathologies worsened.

Methods

Study Participants

Between August 2010 and September 2017, a total of 272 female patients scheduled for arthroscopic hip surgery were identified using the senior author’s (T.Y.’s) clinical database. This single-institution, institutional review board–approved study included all female patients aged ≥14 years who were intended for primary hip arthroscopy for FAI.

Patients with a clinical history of pain localized to the hip were given a diagnosis of FAI based on a combination of physical examination and radiographic findings. Hip arthroscopy was not considered until patients had attempted at least 6 months of nonoperative treatment, during which they also attempted at least 6 weeks of physical therapy. In the clinical setting, provocative testing was performed with the anterior impingement test and Patrick test. As part of the workup, supine anteroposterior and 45° and 90° Dunn view radiographs of the pelvis were obtained for all patients. Magnetic resonance imaging or magnetic resonance arthrography was used to evaluate chondral pathology or labral tears in all patients.

Inclusion criteria consisted of evidence of FAI, including a lateral center-edge angle >40°, alpha angle ≥60° (on any radiographic view), acetabular retroversion (ie, crossover sign, posterior wall sign, ischial spine sign), and focal chondrolabral delamination on magnetic resonance imaging or arthrography. For the purposes of this study, acetabular retroversion refers to focal proximal retroversion, not acetabular retroversion associated with hip dysplasia. Hip arthroscopy was contraindicated in patients with evidence of hip osteoarthritis, which included Tönnis grade >1 or hip dysplasia indicated by lateral center-edge angle <20°. Patients were excluded if they were <14 years old or had 1 of the following: connective tissue disorders, rheumatologic disorders, previous hip surgery, revision hip arthroscopic surgery, history of traumatic fracture, and <2 years of follow-up.

Characteristic information was recorded, including sex, age, and body mass index (BMI). All surgical procedures were performed by the senior author, a sports medicine fellowship–trained orthopaedic surgeon (T.Y.). We separated patients into 3 age cohorts based on the work of Frank et al⁴: <30, 30 to 45, and >45 years.

Surgical Technique and Postoperative Rehabilitation

All hip arthroscopy procedures were performed with the patient under general anesthesia through standard midanterior and anterolateral portals. After portals were established, the senior author (T.Y.) used an interportal capsulotomy to conduct a diagnostic survey. All labral tears at the chondrolabral junction were repaired using suture anchors. Superficial, complex, or irreparable labral tears were debrided. Shaving chondroplasty was used to stabilize chondral borders for Outerbridge grade I to III lesions. Microfracture or minimal abrasion arthroplasty was used for focal Outerbridge grade IV chondral lesions. However, none of the patients in this cohort underwent microfracture. Osteochondroplasty was used to treat pincer and/or cam pathology, and the senior author used dynamic examination to ensure sufficient resection. Capsular repair was conducted at the conclusion of surgery.

After surgery, all patients were given a hip brace to limit external rotation and extension. Additionally, patients were asked to avoid foot-flat weightbearing on the operative side and given assistive crutches for use during the first month after surgery. All patients were discharged with a 3-day supply of cephalexin (500 mg, 4 times daily) for infection prophylaxis and prescribed celecoxib (200 mg/d) for 14 days for heterotopic ossification prevention and aspirin (81 mg/d) for 7 days for deep venous thrombosis prophylaxis.

Functional Outcome and Statistical Analysis

All patients included for analysis had a modified Hip Harris Score (mHHS) and a Non-arthritic Hip Score (NAHS) to assess pre- and postoperative function (minimum 2-year follow-up). To eliminate any risk of possible confounding associated with gluteal tendinopathy, the senior author (T.Y.) reviewed all magnetic resonance imaging scans. Statistical analysis was conducted with Prism version 8.3 (GraphPad). P < .05 indicated statistical significance. We used analysis of variance (ANOVA) to compare functional outcome scores among the 3 age cohorts, as these data were normally distributed per D’Agostino and Pearson tests for normality; chi-square tests for categorical variables; and simple logistic regression to analyze the Patient Acceptable Symptomatic State (PASS; ie, a dichotomous variable).

Results

Of the initial 272 patients screened for potential eligibility, 194 (71.3%) female patients were included for final analysis in this study. Five patients were excluded as revision cases, 39 on the basis of incomplete demographic or operative data, and 34 for incomplete outcome data.

Included patients were 41.5 ± 13.1 years old (mean ± SD) and had a BMI of 25.2 ± 5.0 kg/m². Additionally, these patients were separated into 3 age groups: <30 years (n = 44), 30 to 45 years (n = 74), and >45 years (n = 76) (Table 1). BMIs for these 3 groups were 23.0 ± 3.8, 24.8 ± 5.0, and 26.9 ± 5.1 kg/m², respectively (P < .0001). Results of a post hoc Tukey analysis for these BMIs are presented in Table 2.

Table 1

Patient Characteristics by Age Group^a

	Patients, No. (%) or Mean ± SD
	<30 y (n = 44)	30-45 y (n = 74)	>45 y (n = 76)	P Value
Age, y	25.2 ± 3.9	37.1 ± 4.8	55.2 ± 6.8	<.001
Sex: female	44 (100)	74 (100)	76 (100)
Body mass index, kg/m²	23.0 ± 3.8	24.8 ± 5.0	26.9 ± 5.1	<.001
Hip: right	30 (68)	36 (49)	51 (67)	.033
Preoperative angle
Lateral center edge	35.8 ± 5.7	36.0 ± 6.3	37.5 ± 7.7	.389
Alpha angle	59.8 ± 8.5	59.5 ± 7.5	58.5 ± 8.7	.331
Outerbridge grade				.022
0	16 (36)	13 (17)	18 (24)
1	27 (61)	53 (72)	44 (58)
>1	1 (3)	8 (11)	14 (18)
Tönnis grade				<.001
0	42 (95)	60 (81)	38 (50)
1	2 (5)	14 (19)	38 (50)

Bold indicates P < .05.

Table 2

Analysis of Variance of BMI and Chi-square Analysis of Laterality by Patient Age Group^a

	No. Hips		BMI, Mean ± SD
Tukey Multiple Comparison	Group 1	Group 2	Group 1	Group 2	Mean Difference	P Value
Group 1 vs 2
<30 vs 30-45 y	44	74	23.0 ± 3.8	24.8 ± 5.0	1.7	.081
<30 vs >45 y	44	76	23.0 ± 3.8	26.9 ± 5.1	3.9	.003
30-45 vs >45 y	74	76	24.8 ± 5.0	26.9 ± 5.1	2.1	.023
Multiple Chi-square	Right Hips, No. (%)				% Difference
Group 1 vs 2
<30 vs 30-45 y	30 (68)	36 (49)			19	.039
<30 vs >45 y	30 (68)	51 (67)			1	.903
30-45 vs >45 y	36 (49)	51 (67)			18	.022

Bold indicates P < .05. BMI, body mass index.

This study compared cohorts with a series of chi-square tests to determine individual significance with respect to laterality. As demonstrated in Table 2, there were statistically significant differences in laterality among groups, with a higher percentage of right hips in the >45-year-old cohort relative to the 30- to 45-year-old cohort as well as in the <30-year-old cohort relative to the 30- to 45-year-old cohort (P = .022 and P = .039, respectively).

As shown in Table 1, there were no statistically significant differences among age groups with respect to preoperative lateral center-edge angle or alpha angle. There were, however, statistically significant differences among groups with respect to Tönnis and Outerbridge grades, with a trend toward greater degradation among the older cohorts (P < .001 and P = .022, respectively).

As shown in Table 3, there were no statistically significant differences among groups with respect to rates of labral repair or debridement, with 1 exception. Patients aged >45 years received labral repair significantly less frequently (82%) than their 30- to 45-year-old counterparts (95%; P = .013). The difference in labral repairs between patients >45 years old (82%) and those <30 years old (89%) did not achieve similar statistical significance.

Table 3

Chi-square Analysis of Labral Repair and Labral Debridement by Patient Age Group^a

	Group 1	Group 2
Multiple Chi-square	Labral Repair, No. (%)		% Difference	P Value
Group 1 vs 2
<30 vs 30-45 y	39 (89)	70 (95)	6	.291
<30 vs >45 y	39 (89)	62 (82)	8	.314
30-45 vs >45 y	70 (95)	62 (82)	14	.013
	Labral Debridement
Group 1 vs 2
<30 vs 30-45 y	5 (11)	6 (8)	3	.746
<30 vs >45 y	5 (11)	14 (18)	7	.438
30-45 vs >45 y	6 (8)	14 (18)	10	.093

Bold indicates P < .05.

More than 99% of all patients (n = 192) had demonstrable labral tears intraoperatively; 162 (84%) had chondral delamination; 148 (76%) had a cam-type lesion; and 182 (94%) had a pincer-type lesion. As shown in Table 4, there was no statistically significant difference in frequency of operative pathology among the 3 age cohorts with respect to labral tears, chondral delamination, pincer lesions, or subspine impingement (P > .05). There was, however, a statistically significant difference in incidence of cam-type lesions among the 3 groups. A total of 39 women (89%) aged <30 years had cam-type lesions, as compared with 58 (78%) aged 30 to 45 years and 51 (67%) aged >45 years (P = .024). Results of a series of chi-square tests (Table 5) demonstrated statistical significance by comparing the proportion of women aged <30 years and >45 years with cam-type lesions (P = .009). Additionally, results of logistic regression (Figure 1) indicated that the odds of a cam-type lesion decreased by 0.971 for every additional year in age among female patients (P = .024).

Table 4

Intraoperative Pathology by Age Group^a

	Patients, No. (%)
	<30 y (n = 44)	30-45 y (n = 74)	>45 y (n = 76)	P Value
Labral tear	43 (98)	74 (100)	75 (99)	.473
Chondral delamination	38 (86)	64 (86)	60 (79)	.39
Cam-type lesion	39 (89)	58 (78)	51 (67)	.024
Pincer-type lesion	42 (95)	71 (96)	69 (91)	.371
Subspine impingement	8 (18)	14 (19)	12 (16)	.873
Combined-type lesion	38 (86)	56 (76)	50 (66)	.043

Bold indicates P < .05.

Table 5

Chi-square Analysis of Cam-type Lesions by Patient Age Group^a

	Cam-type Lesions, No. (%)
Multiple Chi-square	Group 1	Group 2	% Difference	P Value
Group 1 vs 2
<30 vs 30-45 y	39 (89)	58 (78)	11	.159
<30 vs >45 y	39 (89)	51 (67)	22	.009
30-45 vs >45 y	58 (78)	51 (67)	11	.121

Bold indicates P < .05.

When analyzing subgroups by ANOVA for statistical significance with respect to baseline mHHS, we found no overall significant difference among groups (P = .164), with baseline values of 47.97 ± 17.4, 47.20 ± 13.9, and 43.20 ± 15.6 for age groups <30, 30 to 45, and >45 years, respectively. When the baseline NAHS scores were similarly analyzed by ANOVA for statistical significance, there was no overall statistical significance among groups (P = .502). Baseline NAHS values were 49.65 ± 13.8, 49.25 ± 13.7, and 46.94 ± 15.2 for age groups <30, 30 to 45, and >45 years.

Significant differences (P = .0003) were found per an ANOVA for all 3 age groups at 2-year follow-up for mHHS scores (88.3 ± 13.1, <30 years; 82.7 ± 18.0, 30 to 45 years; 75.0 ± 19.5, >45 years). The results of post hoc Tukey analysis are presented in Table 6. There was a significant difference between the <30- and >45-year-old cohorts, as the 2 groups had a mean difference of 13.3 (P < .001). There was also a statistically significant difference between the 30- to 45-year-old group and the >45-year-old group, with a mean difference of 7.7 (P = .023). There was no significant difference between the <30-year-old and 30- to 45-year-old cohorts with respect to final mHHS scores (P = .223).

As seen in Table 6, the results of an ANOVA comparing 2-year NAHS scores were also statistically significant (P = .0002). Based on a post hoc Tukey analysis, similar relationships were found among groups for the NAHS as for the mHHS. The <30- and >45-year-old cohorts were significantly different, with a mean difference of 11.8 (P < .001). There was also a statistically significant difference between the 30- to 45-year-old group and the >45-year-old group, with a mean difference of 7.7 (P = .009). There was no statistical significance between the <30- and 30- to 45-year-old cohorts with respect to final NAHS scores (P = .384).

Table 6

Analysis of Variance for Follow-up mHHS and NAHS by Patient Age Group^a

	Hips, No.		mHHS at 2 y, Mean ± SD
Tukey Multiple Comparison	Group 1	Group 2	Group 1	Group 2	Mean Difference	P Value
Group 1 vs 2
<30 vs 30-45 y	44	74	88.3 ± 13.1	82.7 ± 18.0	5.6	.223
<30 vs >45 y	44	76	88.3 ± 13.1	75.0 ± 19.5	13.3	<.001
30-45 vs >45 y	74	76	82.7 ± 18.0	75.0 ± 19.5	7.7	.023
			NAHS at 2 y
Group 1 vs 2
<30 vs 30-45 y	44	74	89.9 ± 13.7	85.8 ± 15.8	4.1	.384
<30 vs >45 y	44	76	89.9 ± 13.7	78.1 ± 17.2	11.8	<.001
30-45 vs >45 y	74	76	85.8 ± 15.8	78.1 ± 17.2	7.7	.009

P values represent those of post hoc Tukey analysis. Bold indicates P < .05. mHHS, modified Hip Harris Score; NAHS, Non-arthritic Hip Score.

Among the 3 age groups, there was no statistically significant difference in frequency of patients who met the minimally clinically important difference (MCID; P = .203). Of patients aged <30 years, 42 (95%) met the MCID for the mHHS, previously defined as an improvement of +8 points.¹⁴ Of patients in the 30- to 45-year-old cohort, 69 (93%) met the MCID, as compared with 66 (87%) among those >45 years old.

Conversely, we found a significant difference when analyzing the proportions of patients who met the PASS at 2-year follow-up, defined as an mHHS of 74 (P = .0007).¹⁴ Of patients aged <30 years, 38 (86%) achieved the PASS, as compared with 56 (76%) aged 30 to 45 years and 42 (55%) aged >45 years. The results of a series of chi-square analyses (Table 7) demonstrated a statistically significant difference in the proportion of patients achieving the PASS between the >30- and >45-year-old cohorts as well as between the 30- to 45-year-old and >45-year-old cohorts (P = .0005 and P = .009, respectively).

Table 7

Chi-square Analysis of Patients Achieving PASS by Age Group^a

	Patients Achieving PASS, No. (%)
Multiple Chi-Square	Group 1	Group 2	% Difference	P Value
Group 1 vs 2
<30 vs 30-45 y	38 (86)	56 (76)	10	.163
<30 vs >45 y	38 (86)	42 (55)	31	<.001
30-45 vs >45 y	56 (76)	42 (55)	21	.009

Bold indicates P < .05. PASS, Patient Acceptable Symptomatic State.

Finally, results of logistic regression demonstrated the significance of age with respect to achieving the PASS (Figure 2). This regression determined that the odds of achieving the PASS decreased by a factor of 0.96 for each additional year in age (P < .0004).

There was no significant difference among rates of gluteal tendinopathy among the cohorts, with 2 (5%), 5 (7%), and 8 (11%) among those aged <30, 30 to 45, and >45 years, respectively (P = .714).

Discussion

The 3 primary findings of the current study include the following: hip arthroscopy outcomes in female patients were generally good, with 91.2% achieving the MCID, which was not age dependent; there was an age-dependent decrease in meeting the PASS among female patients as age increased; and there was an age-dependent decrease in intraoperative cam-type lesions in female patients as age increased. Additional findings include significantly lower mHHS and NAHS scores in the oldest age group at 2-year follow-up.

The results of the present study are similar to those previously published in the orthopaedic literature, which found that hip arthroscopy for FAI outcomes are generally good, regardless of sex.^5,18 These results also support a small but growing body of literature that suggests that hip arthroscopy outcomes among younger female patients are superior to those of older female patients.

Frank et al⁴ had similar results in their analysis of 75 female patients. They demonstrated that hip arthroscopy functional outcome scores—namely, the Hip Outcome Score activities of daily living subscale, Hip Outcome Score sport-specific subscale, and mHHS—decreased as patient age increased. The current study’s cohort of 194 female patients displayed similar trends with the mHHS and NAHS.

Significantly fewer patients in the older subgroups achieved the PASS as compared with the younger cohort. McCormick et al¹⁶ reported that age was a predictor of patient-reported outcomes after hip arthroscopy for the treatment of labral tears. They found that patients aged <40 years achieved good to excellent results at a higher rate than patients aged >40 years. While this study is not directly comparable, as the age groups are different and the authors did not conduct a sex-based analysis, it does provide supporting evidence that older patients are less likely to have superior outcomes after hip arthroscopy. However, there remains some controversy in the literature with regard to the effects of age differences on outcomes. Domb et al³ found no statistical differences in hip arthroscopy outcomes between patients aged <30 and >50 years. Several reviews, while not directly comparing age cohorts as in the study performed by Domb et al, found significant improvements in functional outcomes in older populations.^9,20

Our study did demonstrate that older patients had higher rates of degenerative changes in their joints (significantly higher percentage with Tönnis grade 1 hips), which is consistent with previous literature and can explain their inferior outcomes relative to younger patients. Similarly, this older cohort underwent labral debridement at a somewhat higher rate than that of their younger counterparts. This supports our hypothesis that with increasing age, there may be increasing intra-articular pathology and degeneration that can lead to poorer results.¹⁷

Previous literature regarding FAI has documented that female patients have a decreased incidence of cam-type lesions relative to male patients.^6,7,20 However, to our knowledge, there are no previous studies in the orthopaedic literature documenting the age-dependent decreasing incidence of cam-type lesions among female patients. In terms of intraoperative pathology, the results of this study indicate that among this cohort of 194 female patients, cam-type lesions (76%) were less common than pincer-type lesions (94%). In addition, there was a significant decrease in incidence of cam-type lesions as age increased, with an 11% decrease in cam lesions for each progresively older cohort. This corresponded to a decreased odds of 0.971 for each year of increasing age. The reason for this decreased incidence is not exactly clear, although there are some plausible explanations. Patients with cam lesions may be more symptomatic because of increased bony contact between the deformed femoral neck and acetabulum, resulting in an earlier presentation. Conversely, the symptoms that cause older patients to seek treatment may be caused primarily by articular cartilage and labral degeneration and not by bony deformity. Despite the increased focus on hip arthroscopy in the literature, there is a relative dearth of research regarding the outcomes of this surgery in the female population. This cohort of 194 female patients represents one of the largest studies focusing on outcomes after surgical treatment of FAI in female patients. Malviya et al¹⁵ reported that the female patients included in their prospective cohort had a significantly lower average quality of life after hip arthroscopy than male patients, although it is worth noting that male patients also had significantly higher preoperative quality-of-life scores. Additionally, the female patients in their population actually had a greater improvement in quality of life than their male counterparts, which confounds the results. This is significant given that female sex, as demonstrated in several studies, is a predictor of increased recovery time after hip arthroscopy.^12,21

The current study found that age may negatively affect the mHHS and NAHS of female patients and the number of patients who reach the PASS. Interestingly, cam-type lesions were fewer in older female patients as compared with their younger counterparts. Surgeons and patients should use this information to better inform the shared decision-making process.

Limitations and Areas for Future Research

This study is not without its limitations. First, it is a retrospective analysis of prospectively collected data. It also may be limited by responder bias. In addition, the follow-up period of 2 years is relatively short, although this study did show similar improvements in functional outcomes as previous studies in similar time frames. Although one of the strengths of the study is the large cohort of female patients, some patients were lost to follow-up or began seeing other surgeons for treatment of hip-related issues.

Patients in the >45-year-old group had a higher incidence of Tönnis grade 1 changes and labral debridement. While it is to be expected that there will be increased articular cartilage and labral degeneration with advancing age, it is important to recognize that some of our significant results from comparison of the 3 age groups may have confounding limitations.

Another limitation comes from the significant difference in BMI among age groups. BMI has been shown to negatively affect hip arthroscopy outcomes for FAI. However, the absolute mean difference, 3.89 kg/m², was small and well within the limit (±5 kg/m²) used by several previous matched-cohort studies in hip arthroscopy.^1,11,13

Areas of future research should continue to focus on sex-specific reporting on any treatment of FAI while controlling for age. Although there have been 2 recent randomized controlled trials, neither analyzed the results for subgroups of sex or age.^8,19

Conclusion

Surgical treatment of FAI in female patients led to improved functional outcomes at 2 years of follow-up, although older female patients did worse after hip arthroscopy as compared with their younger counterparts. There may be an age-dependent decrease in incidence of cam-type lesions in female patients.

Footnotes

Acknowledgements

The authors thank Crist Chee for all of his invaluable help collecting data with the Sports Division.

Submitted February 19, 2020; accepted June 18, 2020.

One or more of the authors has declared the following potential conflict of interest or source of funding: T.Y. has received consulting fees from Arthrex, speaking fees and travel payments from Smith & Nephew, and hospitality payments from DePuy Orthopaedics. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

References

Ashberg

Perets

, et al. Do femoral head osteochondral lesions predict a poor outcome in hip arthroscopy patients? A matched control study with minimum 5-year follow-up. Arthroscopy. 2019;35(2):419-431.

Bonazza

Homcha

Liu

Leslie

Dhawan

Surgical trends in arthroscopic hip surgery using a large national database. Arthroscopy. 2018;34(6):1825-1830.

Domb

Linder

Finley

, et al. Outcomes of hip arthroscopy in patients aged 50 years or older compared with a matched-pair control of patients aged 30 years or younger. Arthroscopy. 2015;31(2):231-238.

Frank

Lee

Bush-Joseph

Salata

Mather

III Nho

SJ.

Outcomes for hip arthroscopy according to sex and age: a comparative matched-group analysis. J Bone Joint Surg Am. 2016;98(10):797-804.

Frank

Ukwuani

Allison

Clapp

Nho

SJ.

High rate of return to yoga for athletes after hip arthroscopy for femoroacetabular impingement syndrome. Sports Health. 2018;10(5):434-440.

Ganz

Leunig

Leunig-Ganz

Harris

WH.

The etiology of osteoarthritis of the hip: an integrated mechanical concept. Clin Orthop Relat Res. 2008;466(2):264-272.

Ganz

Parvizi

Beck

Leunig

Nötzli

Siebenrock

KA.

Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop Relat Res. 2003;417:112-120.

Griffin

Dickenson

Wall

PDH

, et al. Hip arthroscopy versus best conservative care for the treatment of femoroacetabular impingement syndrome (UK FASHIoN): a multicentre randomised controlled trial. Lancet. 2018;391(10136):2225-2235.

Griffin

Kinnard

Formby

McCabe

Anderson

TD.

Outcomes of hip arthroscopy in the older adult: a systematic review of the literature. Am J Sports Med. 2017;45(8):1928-1936.

10.

Khan

Habib

de Sa

, et al. Arthroscopy up to date: hip femoroacetabular impingement. Arthroscopy. 2016;32(1):177-189.

11.

Kuhns

Hannon

Makhni

, et al. A comparison of clinical outcomes after unilateral or bilateral hip arthroscopic surgery: age- and sex-matched cohort study. Am J Sports Med. 2017;45(13):3044-3051.

12.

Lee

Klika

Bershadsky

Krebs

Barsoum

WK.

Factors affecting recovery after arthroscopic labral debridement of the hip. Arthroscopy. 2010;26(3):328-334.

13.

Levy

Cvetanovich

Kuhns

Greenberg

Alter

Nho

SJ.

Hip arthroscopy for atypical posterior hip pain: a comparative matched-pair analysis. Am J Sports Med. 2017;45(7):1627-1632.

14.

Levy

Kuhns

Chahal

Philippon

Kelly

Nho

SJ.

Hip arthroscopy outcomes with respect to patient acceptable symptomatic state and minimal clinically important difference. Arthroscopy. 2016;32(9):1877-1886.

15.

Malviya

Stafford

Villar

RN.

Impact of arthroscopy of the hip for femoroacetabular impingement on quality of life at a mean follow-up of 3.2 years. J Bone Joint Surg Br. 2012;94(4):466-470.

16.

McCormick

Nwachukwu

Alpaugh

Martin

SD.

Predictors of hip arthroscopy outcomes for labral tears at minimum 2-year follow-up: the influence of age and arthritis. Arthroscopy. 2012;28(10):1359-1364.

17.

Menge

Briggs

Dornan

McNamara

Philippon

MJ.

Survivorship and outcomes 10 years following hip arthroscopy for femoroacetabular impingement. J Bone Joint Surg Am. 2017;99(12):997-1004.

18.

Minkara

Westermann

Rosneck

Lynch

TS.

Systematic review and meta-analysis of outcomes after hip arthroscopy in femoroacetabular impingement. Am J Sports Med. 2019;47(2):488-500.

19.

Palmer

AJR

Ayyar Gupta

Fernquest

, et al. Arthroscopic hip surgery compared with physiotherapy and activity modification for the treatment of symptomatic femoroacetabular impingement: multicentre randomised controlled trial. BMJ. 2019;364:i185.

20.

Perets

Chaharbakhshi

, et al. Hip arthroscopy in patients ages 50 years or older: minimum 5-year outcomes, survivorship, and risk factors for conversion to total hip replacement. Arthroscopy. 2018;34(11):3001-3009.

21.

Philippon

Ejnisman

Ellis

Briggs

KK.

Outcomes 2 to 5 years following hip arthroscopy for femoroacetabular impingement in the patient aged 11 to 16 years. Arthroscopy. 2012;28(9):1255-1261.

22.

Ross

Larson

Bedi

Indications for hip arthroscopy. Sports Health. 2017;9(5):402-413.