Abstract
Background:
Periacetabular osteotomy (PAO) is an established treatment for symptomatic developmental dysplasia of the hip (DDH) and femoroacetabular impingement (FAI; principally acetabular retroversion) in adults who are commonly of reproductive age.
Purpose:
To describe the effect of PAO on patient-reported sexual function (SF) using data from the UK Non-Arthroplasty Hip Registry (NAHR).
Study Design:
Cohort study: Level of evidence, 3.
Methods:
Adult patients who underwent isolated PAO between January 2012 and July 2022 were extracted from the NAHR. The EuroQol-5 Dimensions (EQ-5D) and International Hip Outcome Tool 12 (iHOT-12) questionnaires were collected preoperatively and at 6 and 12 months postoperatively. This included responses to 2 questions from the iHOT-12 questionnaire relevant to SF: (1) “Are questions about SF relevant to you?” and (2) “How much trouble do you have with sexual activity because of your hip?” (0 = severe; 100 = none).
Results:
A total of 773 patients (median age, 29 years (IQR, 23-37), 92.5% female) who underwent PAO for DDH (n = 703; 90.9%) or FAI (n = 70; 9.1%) were identified after exclusions. Of iHOT-12 respondents, 88.2% indicated that SF was relevant to them. Baseline median iHOT-12 SF scores were 33 (IQR, 18-53) for female and 73 (IQR, 36-90) for male patients. Female iHOT-12 SF improved by a mean of +19.9 points (95% CI, 16.5-23.2) at 6 months (P < .0001), with continued improvement to +26.4 points (95% CI, 23.0-29.8) at 12 months (P < .0001) versus preoperative SF scores. At 12 months, median iHOT-12 SF scores were 70 (IQR, 40-90) and 89 (IQR, 70-99) for female and male patients, respectively. Preoperative SF scores were significantly lower (P = .001) in patients who underwent PAO for indication of FAI (female median score 22; IQR, 10-38) compared with DDH (female median score: 34; IQR, 18-54); however, both indications saw significant improvement in SF scores at 12 months. iHOT-12 SF scores improved for 77.1% and worsened for 19.1% of female respondents with DDH. A strong positive association was seen between health-related quality of life (EQ-5D) and SF scores, and there was significant improvement in SF across studied ages.
Conclusion:
PAO was associated with significant improvement in patient-reported SF for the majority of patients. Some patients may have trouble with sexual activity even 1 year after PAO for DDH, with almost 20% reporting poorer SF compared with preoperative baseline.
Periacetabular osteotomy (PAO) is a well-established treatment for symptomatic developmental dysplasia of the hip (DDH) and acetabular retroversion leading to femoroacetabular impingement (FAI) in adults who do not respond to nonoperative treatment and is associated with excellent postoperative outcomes. 6 The Bernese PAO allows for extensive reorientation of the acetabulum and permits patients to mobilize early postoperatively due to an intact posterior column of the hemipelvis4,19; it also benefits from negligibly affecting the dimensions of the true pelvis, thus minimizing the effect on the birth canal from a childbearing perspective. 21
Although the efficacy of PAO for DDH and FAI due to acetabular retroversion is well-documented,6,8,13 there is scarce evidence regarding the effect of PAO on patient-reported sexual function (SF), which may be impaired due to a combination of pain, instability, and reduced range of movement with or without impingement. These are important associations to understand, as the majority of patients receiving PAO are women of reproductive age for whom SF and pregnancy are relevant considerations. 18 Understanding how SF changes after PAO allows for informed expectations on the part of the patient and surgical team regarding the degree of any improvement.
The UK Non-Arthroplasty Hip Registry (NAHR) was conceptualized by the British Hip Society in 2011 and has been collecting data in the United Kingdom for any nonarthroplasty and nonacute trauma procedures performed around the hip since 2012. This study used data from the NAHR to (1) assess the effect of PAO on patient-reported SF in adults with symptomatic DDH or FAI due to acetabular retroversion and (2) determine if outcomes vary by sex, age, and the pathology for which the PAO was performed.
Methods
Approval for this cohort study was granted by the NAHR. We received data for all PAOs recorded in the NAHR between January 1, 2012, and July 1, 2022. Informed consent was obtained from all patients included in the NAHR, including for using their data in service evaluation and research. Patients who underwent concurrent femoral osteotomy as part of the same procedure were excluded, along with cases where an additional unclassified acetabular or femoral procedure was performed (Figure 1). We excluded cases where a previous hip preservation procedure had been recorded within the NAHR on the same hip, where a patient's procedure chronology was ambiguous, or where a patient did not respond to the preoperative questionnaire and ≥1 postoperative questionnaire. The surgical indication was considered to be DDH unless explicitly recorded that the procedure was undertaken to treat FAI caused by acetabular retroversion.

Study flow diagram. EQ-5D, EuroQol-5 Dimensions index; iHOT-12, 12-item International Hip Outcome Tool; NAHR, Non-Athroplasty Hip Registry; PAO, periacetabular osteotomy.
Patient characteristics and information related to diagnosis and surgical procedures are collected using a structured online form. The NAHR invites all patients to complete online questionnaires to capture patient-reported outcome measures, including the EuroQol-5 Dimensions (EQ-5D) index and the 12-item International Hip Outcome Tool (iHOT-12), preoperatively and at 6 months and 1 year postoperatively. The iHOT-12, a shortened version of iHOT-33, assesses nonarthritic hip problems in young, active patients.12,16
A review of the NAHR database indicated that from January 1, 2012, to July 1, 2022, a total of 1403 adults had PAO performed (Figure 1). Of that group, 110 patients (7.8%) were excluded from the study because they underwent concurrent femoral osteotomy, previous hip preservation surgery, and/or unclassified procedures. Of the remaining 1293 patients who had isolated PAOs performed, 520 (40%) were excluded due to incomplete pathway data, missing preoperative iHOT-12 score, and/or missing 6- or 12-month postoperative questionnaires for iHOT-12 or EQ-5D. Thus, 773 (55%) of the 1403 PAO database patients met the inclusion criteria and were the eligible study population and basis of this report.
From the eligible study population, we assessed the response to 2 questions from the preoperative iHOT-12 questionnaire relevant to SF: (1) “Are questions about sexual function relevant to you?” and (2) “How much trouble do you have with sexual activity because of your hip?” Patients were asked to respond with a score between 0 (“severe trouble”) and 100 (“no trouble at all”). Characteristics were then compared between patients who indicated that questions about SF were relevant to them versus those who did not, stratified by sex. This included a comparison of the composite iHOT-12 score (calculated across all iHOT-12 domains) to assess whether differences in patient perception of the relevance of SF may be associated with global hip function.
Subsequent analyses were focused exclusively on those individuals who declared that SF was relevant. In this group, we compared preoperative as well as 6-month and 12-month postoperative iHOT-12 patient SF and the EQ-5D 5 levels (5L) index score, in addition to the score change (Δ) at each follow-up time.
Statistical Analysis
Continuous variables were assessed for normality and means reported accordingly. Between-group comparisons were made using the chi-square test and the Student t test or Wilcoxon rank-sum (Mann-Whitney U) test for categorical and continuous data, depending on whether the data were normally distributed. Within-group comparisons of paired continuous data (pre- vs postoperative score improvement) were performed using the paired t test. We defined the minimal clinically important difference (MCID) for iHOT-12 SF score improvement as half the standard deviation of the preoperative iHOT-12 SF scores. 15 Missing data for body mass index and outcome scores are reported explicitly in results.
Scatterplots with a smoothed mean (derived from a locally estimated scatterplot smoothing model) were used to investigate the relationship between age and sexual outcome, stratified by sex. The Pearson correlation coefficient was used to measure the correlation between the EQ-5D index, overall iHOT-12, and iHOT-12 SF scores. Analyses were performed in STATA (Release 15; Stata Statistical Software) and R Version 4.
Results
An eligible study population of 773 patients who underwent PAO for DDH (n = 703; 90.9%) or FAI (n = 70; 9.1%) were identified from the NAHR database after exclusions (Figure 1).
Patient Characteristics
Demographic data for the eligible study population are summarized in Table 1. The median patient age was 29 years (IQR, 23-37) and 92.5% of patients were female. A majority of these (n = 682; 88.2%) patients, with similar proportions comparing female (88.4%) and male (86.2%) sexes, indicated that questions about SF were relevant them.
Comparison of Patient Characteristics Based on Response to Questions Regarding Relevance of Sexual Function (N = 773) a
Data are presented as median (IQR) or n (%), unless otherwise indicated. BMI, body mass index; DDH, developmental dysplasia of the hip; FAI, femoroacetabular impingement; iHOT-12, 12-item International Hip Outcome Tool; PAO, periacetabular osteotomy.
Additional data indicate number and percentage of nonmissing data points for BMI by group.
Values present the number and proportion (row percentage) of cases for each indication of PAO.
Values given are the overall total iHOT-12 derived from all composite domains, not sexual function specific.
For both sexes, individuals reporting that SF was relevant were significantly older. Female median age for patients indicating SF was relevant was 30 (IQR, 24-37) versus 22 (IQR, 19-30) for women indicating that SF was not relevant (P < .0001) (Table 1) and had statistically similar global hip function indicated by preoperative overall iHOT-12 scores (“overall” iHOT-12 score refers to total composite score derived across all domains, not SF specific) compared with those reporting that SF was not relevant: female median preoperative iHOT-12 overall score for patients indicating that SF was relevant was 27 (IQR, 16-38) versus 29 (IQR, 16-40) for women indicating SF was not relevant (P = .46). Among female and male patients indicating preoperatively that questions about SF were relevant, the proportion returning iHOT-12 SF scores was 80.8% preoperatively, 66.6% at 6 months, and 65.7% at 12 months.
SF Scores Related to Sex
Both sexes saw significant improvement in SF after PAO (Table 2). Male patients reported significantly higher iHOT-12 SF scores than female patients preoperatively, at 6-month, and at 12-month follow-up (Student t test; all P < .001). In fact, the median male preoperative iHOT-12 SF score (73; IQR, 36 to 90) was higher than the median female iHOT-12 SF score at 12 months (70; IQR, 40 to 90). Female iHOT-12 SF improved by a mean of +19.9 points (95% CI, 16.5 to 23.2) at 6 months (paired t test; P < .0001), with continued improvement to +26.4 points (95% CI, 23.0 to 29.8) at 12 months (paired t test; P < .0001) versus preoperative SF scores. The available sample size of male patients returning functional scores was considerably smaller; SF significantly improved after 6 months with a mean score gain of +13.5 (95% CI, 1.1 to 25.9) (paired t test; P = .03); however, significance was lost at 12 months (mean score gain: +11.8 (95% CI, –0.9 to 24.6) (paired t test; P = .07). Among female patients, 64.3% improved by greater than or equal to the MCID for iHOT-12 SF compared with 35.5% of men.
Comparison of Sexual Function and EQ-5D Index Outcomes by Patient Sex (n = 682) a
Data are based on those patients with data who indicated that questions regarding sexual function were relevant to them (n = 682). P values shown are for between-group comparison by sex and derived from the Wilcoxon rank-sum test (nonparametric continuous data), Student t test (parametric continuous data), or chi-square test (categorical data for MCID). EQ-5D, EuroQol-5 Dimensions; iHOT-12, 12-item International Hip Outcome Tool; MCID, minimal clinically important difference.
MCID was defined as half of the SD of the preoperative iHOT-12 sexual function score for the study cohort (14.2).
SF endpoints in female patients were compared by the indication for PAO (Table 3). Female patients who underwent PAO for FAI had significantly poorer preoperative iHOT-12 SF (median score, 22; IQR, 10-38) compared with those undertaken for DDH (median score, 34; IQR, 18-54) (Wilcoxon rank-sum test; P = .001). Postoperative SF scores were also lower for the FAI group; however, this did not reach statistical significance. There was significant improvement in SF versus preoperative scores at 6 months, maintained at 12 months for both indications in female patients: 12-month iHOT-12 SF gain for DDH was +25.9 (95% CI, 22.3-29.4; P < .0001) and for FAI was +33.1 (95% CI, 20.2-46.0; P < .0001). Similar proportions of patients achieved the MCID for iHOT-12 SF improvement at 12 months in both pathology groups.
Sexual Function Outcomes by Indication for PAO in Female Patients (n = 632) a
Data are based on female patients who indicated that questions regarding sexual function were relevant (n = 632), stratified by PAO diagnosis (male patients were not analyzed because of low n). Change (Δ) at 6 and 12 months requires pre- and postoperative response. DDH, developmental dysplasia of the hip; EQ-5D, EuroQol-5 Dimensions; FAI, femoroacetabular impingement; iHOT-12, 12-item International Hip Outcome Tool; MCID, minimal clinically important difference; PAO, periacetabular osteotomy.
MCID was defined as half of the SD of preoperative iHOT-12 sexual function score for the study cohort (14.2). P values shown are for between-group comparison by sex and derived from the Wilcoxon rank-sum test (nonparametric continuous data), Student test (parametric continuous data), or chi-square test (categorical data for MCID).
Analysis of SF After PAO for DDH by Sex
iHOT-12 SF score improvement was compared for all PAOs for DDH where pre- and postoperative scores were returned and presented as a histogram (Figure 2). SF scores improved for 77.1% (246 of 319) and worsened for 19.1% (61 of 319) of female respondents with DDH; scores improved for 62.1% (18 of 29) and worsened for 24.1% (7 of 29) of male patients with DDH; the rest remained unchanged.

Change in iHOT-12 sexual function score at 6 months after PAO for DDH by sex. Patients who improved or worsened are shaded blue and red, respectively. Data for patients with FAI are not shown because of low n. DDH, developmental dysplasia of the hip; iHOT-12, 12-item International Hip Outcome Tool; PAO, periacetabular osteotomy.
SF Outcomes by Patient Age and Sex
Improvement in SF scores was plotted against age for both sexes (Figure 3). For women, there was significant and consistent improvement in SF scores across all studied ages. A similar pattern was seen for male patients; however, there was a distinct reduction in postoperative SF scores for male patients >40 years, although this was based on very few data points, as only 13 male patients over this age had a PAO.

Scatterplot matrix showing iHOT-12 sexual function scores by patient sex and age preoperatively and at 12 months, with score change at 12 months by patient age. A smoothed mean is shown derived from a locally estimated scatterplot smoothing model including 95% CI. The underlying data points are also shown with reduced opacity.
A strong positive correlation was seen between iHOT-12 SF scores and both EQ-5D index and overall iHOT-12 scores preoperatively, overall iHOT-12 scores at 12 months, and overall iHOT-12 score improvement at 12 months (Figure 4).

EQ-5D and iHOT-12 sexual function scatterplot matrix showing EQ-5D and iHOT-12 sexual function score correlation preoperatively and at 12 months, with score change at 12 months. The underlying data points are shown along with a linear trend line. The annotation indicates the calculated Pearson correlation coefficient with 95% CI and corresponding P value.
Discussion
This study demonstrated that SF was relevant to the vast majority (90%) of both female and male patients who underwent PAO for DDH and for FAI due to acetabular retroversion. PAO was associated with significant improvement in early patient-reported SF (mean change in iHOT-12 SF at 6-months vs preoperatively: female, +19.9 [95% CI, 16.5 to 23.2]; male, 13.5 [95% CI, 1.1 to 25.9]), and the improvements were maintained up to 12 months postoperatively (mean change in iHOT-12 SF at 12 months vs preoperatively: female, +26.4 [95% CI, 23.0 to 29.8]; male, +11.8 [95% CI, –0.9 to 24.6]). While significant improvement occurred for the majority of patients, some patients may have trouble with sexual activity even 1 year after PAO for DDH, with 19% and 24% of female and male patients respectively reporting poorer SF compared with preoperative baseline.
SF was strongly influenced by sex. However, improvement was seen for both sexes and across all studied age ranges. Preoperative SF varied by preoperative diagnosis, with significantly poorer function in female patients with FAI compared with DDH: the median preoperative iHOT-12 SF score before PAO for DDH was 35 (IQR, 19-60) and before PAO for FAI was 23 (IQR, 10-34)); however, both groups gained significant improvement in SF after surgery with approximately two-thirds of patients in both diagnosis groups achieving the MCID for iHOT-12 SF at 12 months. Furthermore, there was a strong correlation between SF and health-related quality of life captured by EQ-5D. The findings of our study are relevant to health care professionals treating such patients, the majority of whom are of reproductive age and can expect significant improvement in SF after PAO.
Significance of Sexual Position
Depending on an individual's preferred sexual position, such activity may place range of motion–dependent or position-dependent demands upon the hip joint, which may provoke symptoms. The distinctive pathological mechanisms likely contributing to impaired SF in patients with FAI (impingement) versus DDH (undercoverage and instability) may partly explain the significant differences in pre- and postoperative SF observed in our study between these diagnoses. Sexual positions, particularly for women, may require hip movements involving the extremes of flexion and/or abduction—positions that may be impeded in association with femoroacetabular impingement and instability respectively. 10
Previous research in total hip replacement has identified the 12 most common sexual positions for men and women, across which substantial excursions of the hip joint throughout its normal range of movement are required. 2 Morehouse et al 14 used these positions as the basis for a sex-specific modeling study to assess the degree to which hip instability or impingement may be provoked in patients who have previously undergone hip arthroscopy to treat FAI. Instability risk was defined as >0° of hip extension, >30° external rotation, or >30° abduction. Impingement risk was defined as >90° hip flexion, >10° internal rotation, and >10° adduction. The authors found that return to sexual activity may cause impingement or instability risk in all but 4 of the studied positions for men and women. If these findings are also extrapolated to a preoperative context, it is unsurprising that normal SF may be challenging for adults with hip pathology. In our study, we noted that male patients have significantly better SF scores at all stages of follow-up. Interestingly, male mean preoperative iHOT-12 score for SF (73) was higher than the 12-month mean postoperative score for female patients (70), suggesting that the limitation of SF is more marked in women. This would also explain why the change in scores was smaller for the male population as compared with their female counterparts (Table 2).
Pregnancy and Childbirth Considerations
In addition to sexual activity, pregnancy and childbirth considerations are of crucial relevance to this patient cohort, in particular, any association between pelvic osteotomy and complications. 14 While other variations of pelvic osteotomy have been shown to cause dimensional changes to the birth canal, 11 Trousdale et al, 21 in a magnetic resonance imaging study, found little change in anteroposterior or transverse dimensions of the birth canal after the Bernese PAO. Bartosiak et al 1 studied 38 pregnancies in 31 patients (mean age, 26.5 years) who had previously undergone PAO surgery, finding no difference in the rate of complications, preterm delivery, or birth weight compared with the population mean. However, the authors noted that this group's delivery via caesarean section was more likely.
Effect of Acetabular Retroversion of SF After PAO
Valenzuela et al 22 surveyed 88 female patients who had undergone PAO, exploring the presence of hip pain and changes in the frequency, positions, and satisfaction of sexual activity, 89% were either satisfied or very satisfied with surgery. Of these patients, 40%, 46%, and 25% of patients reported changes in the frequency, positions, and satisfaction of sexual intercourse, respectively. Sixteen women went on to have 24 pregnancies (15 vaginal deliveries, 8 caesarean sections) and were additionally asked about hip pain during pregnancy and after childbirth, type of delivery, and complications during childbirth. Less than 5-mm medialization of the hip center after correction was associated with pain (in 7 of 7 patients) and decreased range of motion (in 8 of 9 patients) during sexual activity. Acetabular retroversion was found in 16 patients postoperatively, and 15 of them had hip pain after periacetabular osteotomy. None of the patients who reported an increased frequency of sexual intercourse had retroversion. Their study corroborates our finding of significantly poorer SF in association with FAI (retroversion) compared with DDH.
Pre- and postoperative SF remain an underexplored topic in patients with young adult hip pathology. Contributing to this, discussions concerning SF in the outpatient setting may be uncomfortable owing to differences in societal and cultural customs between patients and health care professionals. 3 Our study, along with previous research in total hip arthroplasty, confirms that patients consider these issues important (88% in our cohort) and wish to discuss them.9,20,23 Further underpinning this, our study also supports that SF is integral to health-related quality of life, as shown by a strong correlation with the EQ-5D 5L index score.
Strengths of this Study
A key strength of our study is the comparatively large number of patients studied and that our patient sample is drawn from a national sample (21 unique hospitals, 16 unique surgeons) rather than an individual specialist center. Drawn from registry data, findings are therefore more likely to be generalizable and reflective of national results. While there are multiple clinical studies supporting PAO for the treatment of DDH and FAI, studies specifically reporting SF outcomes are limited. Klit et al performed a cross-sectional survey of 68 PAOs (52 patients) and found, similar to our study, that women who underwent PAO reported a statistically significant improvement in SF at 9 to 12 years follow-up. 9 In contrast, male patients demonstrated a nonsignificant trend toward improvement. Notably, their study population only included hips, which had not required conversion to a total hip arthroplasty by the time of the study. Thus, the generalizability of their findings may be limited at longer follow-up times. In contrast, although retrospective, our study benefits from prospective data collection across a national cohort rather than a single center.
Limitations
We acknowledge several limitations. Principally, our study relied on a single question from the iHOT-12 questionnaire to measure patient-reported SF, which were the only data available to us; more robust and validated instruments exist but were not available for this study. 17 As frequently seen in registry-based studies, there was a noticeable reduction in postoperative patient responses with time.5-7 At 12 months, 45.4% of female cases and 38% of male cases were missing either preoperative or postoperative iHOT-12 SF scores (Table 2), which may have led to bias in our results. The observed female 12-month SF mean iHOT-12 (70) exceeded that which would be expected based upon the observed mean improvement of 26.4 points from baseline scores—this may reflect a bias introduced by incomplete follow-up data, possibly related to patients with lower preoperative scores being less likely to complete their 12-month assessments. All patients were contacted several times to complete score questionnaires and may not have responded either because of incorrect contact information or a lack of engagement with the process. We attempted to mitigate this by including in our study cohort only those patients who engaged at any stage with postoperative follow-up. Pre- and postoperative radiographic data were not collected routinely, which could help identify the extent to which improvement in retroversion and acetabular coverage were associated with SF. Additionally, the amount of any chondral damage before undertaking PAO was unknown. Finally, data regarding pregnancy and childbirth are not collected by the NAHR, and further population-level studies are required to assess any effect on childbirth in women.
Conclusion
In conclusion, SF outcomes represent an important consideration for patients who undergo PAO surgery. Significant improvement in SF can be expected for the majority of patients irrespective of age, sex, or pathology (DDH vs FAI), and these improvements correlate strongly with patient-reported health-related quality of life. Notwithstanding these improvements, some patients may have trouble with sexual activity even 1 year after PAO for DDH, with 19% and 24% of female and male patients respectively reporting poorer SF compared with preoperative baseline. Our study also suggests that the limitation in SF predominantly affects the female population with male patients maintaining a higher score at all stages of follow-up.
Footnotes
Final revision submitted January 20, 2025; accepted February 17, 2025.
One or more of the authors has declared the following potential conflict of interest or source of funding: This study was supported by a grant from Orthopaedic Research UK (reference No. 541) (R.J.H.). Data were provided by the UK Non-Arthroplasty Hip Registry. The views expressed represent those of the authors and do not necessarily reflect those of any of the above-mentioned organizations, who do not vouch for how the information is presented. The study sponsor had no role in the design, analysis, or preparation of this manuscript for publication. A.J. has received institutional grants from the National Institute for Health and Care research (NIHR), Health Data Research UK, Versus Arthritis, Healthcare Quality Improvement Partnership, Royal College of Physicians, Tommy's, and Health Foundation; is chair of the data monitoring committee of NIHR Health Technology Assessment (HTA) at the University of Leicester and chair of the trial steering committee of NIHR HTA at Newcastle University, a steering committee member of the Nuffield Foundation at the University of Keele and a data monitoring committee member at Warwick Clinical Trials Unit; and has served as a subpanel member of the NIHR Programme Grants for Applied Research, a subcommittee member of Versus Arthritis Health, co-chair of the research expert group of Versus Arthritis Health, and expert panel member of the Nuffield Foundation Oliver Bird Fund. V.K. is an educational consultant for Smith & Nephew, Arthrex, and Stryker; is a board member of Société Internationale de Chirurgie Orthopédique et de Traumatologie, British Hip Society, European Society for Sports Traumatology, Knee Surgery and Arthroscopy, and British Orthopaedic Association; and is associate editor-in-chief for Journal of the International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine. A.M. has received payment or honoraria for lectures, presentations, speaker bureaus, manuscript writing, or educational events for Smith & Nephew, Schuelke, and Pfizer and has served as the treasurer of the British Hip Society. 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.
Ethical approval for this study was obtained from NAHR Research Committee (NAHR/2022/07).
