| Table 1. Cohort characteristics by tendon status | ||||
|---|---|---|---|---|
| Overall (N = 1,678) | None (N = 1,434) | Tendinosis (N = 190) | Tear (N = 54) | |
| Age at earliest hip imaging, years | ||||
| Median (Q1–Q3) | 30.0 (20.0–39.0) | 28.5 (20.0–38.0) | 39.0 (29.0–46.0) | 41.5 (35.0–48.0) |
| Sex | ||||
| F | 1,050 (62.6%) | 864 (60.3%) | 144 (75.8%) | 42 (77.8%) |
| M | 628 (37.4%) | 570 (39.7%) | 46 (24.2%) | 12 (22.2%) |
| Operated side | ||||
| Left | 778 (46.4%) | 672 (46.9%) | 86 (45.3%) | 20 (37.0%) |
| Right | 900 (53.6%) | 762 (53.1%) | 104 (54.7%) | 34 (63.0%) |
| Procedure | ||||
| Arthroscopy | 1,511 (90.0%) | 1,288 (89.8%) | 173 (91.1%) | 50 (92.6%) |
| PAO + Arthroscopy | 166 (9.9%) | 146 (10.2%) | 16 (8.4%) | 4 (7.4%) |
| Open Procedure or Other | 1 (0.1%) | 0 (0.0%) | 1 (0.5%) | 0 (0.0%) |
| Hip dysplasia on imaging | ||||
| Normal | 1,297 (77.3%) | 1,104 (77.0%) | 150 (78.9%) | 43 (79.6%) |
| Borderline | 246 (14.7%) | 211 (14.7%) | 27 (14.2%) | 8 (14.8%) |
| Dysplastic | 135 (8.0%) | 119 (8.3%) | 13 (6.8%) | 3 (5.6%) |
| FAI on imaging | ||||
| Normal | 360 (21.5%) | 301 (21.0%) | 47 (24.7%) | 12 (22.2%) |
| Cam | 1,271 (75.7%) | 1,093 (76.2%) | 140 (73.7%) | 38 (70.4%) |
| Pincer | 12 (0.7%) | 10 (0.7%) | 1 (0.5%) | 1 (1.9%) |
| Mixed | 35 (2.1%) | 30 (2.1%) | 2 (1.1%) | 3 (5.6%) |
| Labral tear | ||||
| Yes | 1,620 (96.5%) | 1,379 (96.2%) | 188 (98.9%) | 53 (98.1%) |
| Acetabular chondral defect | ||||
| Yes | 318 (19.0%) | 252 (17.6%) | 44 (23.2%) | 22 (40.7%) |
| Femoral chondral defect | ||||
| Yes | 169 (10.1%) | 136 (9.5%) | 22 (11.6%) | 11 (20.4%) |
| Trochanteric bursitis | ||||
| Yes | 138 (8.2%) | 92 (6.4%) | 31 (16.3%) | 15 (27.8%) |
| Missing, n | 1 | 1 | 0 | 0 |
| Values are n (%) unless otherwise indicated. Percentages use nonmissing observations within each column. F = female; M = male; PAO = periacetabular osteotomy; FAI = femoroacetabular impingement. Tear includes partial and complete tears. | ||||
Gluteal tendon pathology, hip dysplasia, and femoroacetabular impingement
Preliminary descriptive report
Study overview
The dataset contains 1,678 surgical hip records representing 1,674 distinct hips from 1,377 patients, with surgeries from October 2017 through April 2026. Both hips are represented for 297 patients.
Age refers to the earliest available imaging of the corresponding hip, ranges from 11 to 64 years, and may differ between hips within the same patient. All descriptive summaries are based on surgical hip records; patients with multiple records contribute more than once.
Statistical analysis
Categorical variables are summarized as counts and percentages, and continuous variables as medians and interquartile ranges. Tendon pathology was analyzed as an ordered outcome (none, tendinosis, partial tear, complete tear) and as any pathology versus none. Unadjusted associations were evaluated using patient-clustered score tests, with trend tests for imaging-defined dysplasia and overall tests for other findings. Comparisons were also stratified by age and sex. Opposite-hip pathology was summarized by index-hip findings, with confidence intervals obtained by resampling patients. All tests were two-sided; exploratory P values were not adjusted for multiple comparisons.
Descriptive findings
Gluteal tendon pathology was recorded in 244 (14.5%) of the surgical hip records: 190 had tendinosis, 47 had a partial tear, and 7 had a complete tear.
Cohort characteristics
Table 1 summarizes demographics and imaging findings by tendon status. Partial and complete tears are combined in the tear group.
Tendon findings by imaging diagnosis
Table 2 shows the frequency of tendon pathology within each imaging-based dysplasia and FAI category. These are unadjusted comparisons.
| Table 2. Tendon pathology by imaging diagnosis | |||||
|---|---|---|---|---|---|
| Records, n | None | Tendinosis | Partial tear | Complete tear | |
| Hip dysplasia on imaging — Trend: ordinal P = 0.428; any pathology P = 0.432 | |||||
| Normal | 1,297 | 1,104 (85.1%) | 150 (11.6%) | 38 (2.9%) | 5 (0.4%) |
| Borderline | 246 | 211 (85.8%) | 27 (11.0%) | 6 (2.4%) | 2 (0.8%) |
| Dysplastic | 135 | 119 (88.1%) | 13 (9.6%) | 3 (2.2%) | 0 (0.0%) |
| FAI on imaging — Overall: ordinal P = 0.763; any pathology P = 0.759 | |||||
| Normal | 360 | 301 (83.6%) | 47 (13.1%) | 12 (3.3%) | 0 (0.0%) |
| Cam | 1,271 | 1,093 (86.0%) | 140 (11.0%) | 31 (2.4%) | 7 (0.6%) |
| Pincer | 12 | 10 (83.3%) | 1 (8.3%) | 1 (8.3%) | 0 (0.0%) |
| Mixed | 35 | 30 (85.7%) | 2 (5.7%) | 3 (8.6%) | 0 (0.0%) |
| Values are n (row %). Ordinal tests use the ordering: none, tendinosis, partial tear, complete tear. Binary tests compare any pathology with none. Both assess an ordered trend for dysplasia and an overall association for FAI, using asymptotic score tests that account for repeated records within patients. Tests are unadjusted for age or sex; P values are exploratory. | |||||
- Tendon-pathology severity and prevalence were similar across imaging-defined dysplasia and FAI categories, with no statistically significant associations.
Tendon findings by postoperative diagnosis
- Table 3 summarizes tendon-pathology severity by postoperative diagnosis.
- “Not documented” means the condition was not listed in the recorded postoperative diagnosis; it does not necessarily indicate normal anatomy.
| Table 3. Tendon pathology by postoperative diagnosis | |||||
|---|---|---|---|---|---|
| Records, n | None | Tendinosis | Partial tear | Complete tear | |
| Postoperative hip dysplasia — Overall: ordinal P = 0.189; any pathology P = 0.205 | |||||
| Not documented | 1,511 | 1,286 (85.1%) | 174 (11.5%) | 45 (3.0%) | 6 (0.4%) |
| Documented | 167 | 148 (88.6%) | 16 (9.6%) | 2 (1.2%) | 1 (0.6%) |
| Postoperative FAI — Overall: ordinal P = 0.394; any pathology P = 0.356 | |||||
| Not documented | 31 | 29 (93.5%) | 1 (3.2%) | 1 (3.2%) | 0 (0.0%) |
| Cam | 838 | 712 (85.0%) | 94 (11.2%) | 28 (3.3%) | 4 (0.5%) |
| Pincer | 48 | 42 (87.5%) | 5 (10.4%) | 1 (2.1%) | 0 (0.0%) |
| Mixed | 761 | 651 (85.5%) | 90 (11.8%) | 17 (2.2%) | 3 (0.4%) |
| Values are n (row %). Ordinal tests use the ordering: none, tendinosis, partial tear, complete tear. Binary tests compare any pathology with none. P values are from overall asymptotic score tests accounting for repeated records within patients. Tests are unadjusted for age or sex; P values are exploratory. 'Not documented' does not necessarily indicate normal anatomy. | |||||
- These comparisons describe unadjusted associations within the surgical cohort.
- Small diagnostic groups limit the precision of comparisons.
Tendon findings by age and sex
- We repeated the comparisons separately by sex and by age group (<20, 20–39, and ≥40 years).
- Bars show tendon-pathology composition; labels indicate record counts. P values assess associations within each stratum and are exploratory.
By sex
By age
- Tests account for repeated records within patients. Sex-stratified comparisons are not adjusted for age, and age-stratified comparisons are not adjusted for sex.
- Small groups and sparse events limit interpretation of stratum-specific P values. A category with no records is labeled n = 0.
Findings in the opposite hip
- Among patients with both hips represented, we examined tendon pathology in the opposite hip according to dysplasia and tendon tears in the index hip.
- Each hip served as the index hip in turn. We retained the earliest surgical record per hip and accounted for paired observations within patients.
- Dysplasia denotes the imaging category “Dysplastic”; borderline hips are included among hips without definite dysplasia.
| Tendon pathology in the opposite hip | ||||
|---|---|---|---|---|
| Overall association: P = 0.152 | ||||
| Index-hip findings | Index hips, n | Patients, n | Opposite-hip pathology, n (%) | 95% CI |
| Neither | 538 | 285 | 74 (13.8%) | 10.5–17.3% |
| Dysplasia only | 45 | 35 | 4 (8.9%) | 2.0–18.8% |
| Tear only | 11 | 9 | 6 (54.5%) | 11.1–87.5% |
| Dysplasia and tear | 0 | 0 | — | Not estimable |
| Tear includes partial and complete tears. 'Neither' means neither definite dysplasia nor a tear; tendinosis may still be present in the index hip. Patients may contribute to more than one row. Confidence intervals use 2,000 patient-level bootstrap samples. The overall P value accounts for patient clustering and is exploratory. Intervals are not reported when bootstrap estimation is degenerate or too few resamples contain the group. | ||||
- Opposite-hip tendon pathology was more frequent when the index hip had a tear (54.5% versus 13.8% with neither dysplasia nor a tear), but this estimate was based on few patients and was imprecise.
- No index hips had both dysplasia and a tear, so their combined association with opposite-hip pathology could not be assessed
Chondral defects and tendon pathology
- We compared tendon findings between hips with and without acetabular or femoral chondral defects.
- Comparisons are unadjusted and account for repeated records within patients.
| Tendon pathology by chondral-defect status | |||||
|---|---|---|---|---|---|
| Records, n | None | Tendinosis | Partial tear | Complete tear | |
| Acetabular chondral defect — Ordinal P = 0.002; any pathology P = 0.002 | |||||
| Absent | 1,360 | 1,182 (86.9%) | 146 (10.7%) | 27 (2.0%) | 5 (0.4%) |
| Present | 318 | 252 (79.2%) | 44 (13.8%) | 20 (6.3%) | 2 (0.6%) |
| Femoral chondral defect — Ordinal P = 0.070; any pathology P = 0.083 | |||||
| Absent | 1,509 | 1,298 (86.0%) | 168 (11.1%) | 38 (2.5%) | 5 (0.3%) |
| Present | 169 | 136 (80.5%) | 22 (13.0%) | 9 (5.3%) | 2 (1.2%) |
| Values are n (row %). Ordinal tests use the ordering: none, tendinosis, partial tear, complete tear. Binary tests compare any pathology with none. P values account for repeated records within patients but are unadjusted for age, sex, or multiple comparisons. Records missing the relevant finding are excluded. | |||||
- Acetabular chondral defects were associated with more frequent and more severe tendon pathology (ordinal and binary P = 0.002).
Trochanteric bursitis and tendon pathology
We compared tendon findings between hips with and without trochanteric bursitis, accounting for repeated records within patients.
| Tendon pathology by trochanteric-bursitis status | |||||
|---|---|---|---|---|---|
| Ordinal P <0.001; any pathology P <0.001 | |||||
| Bursitis | Records, n | None | Tendinosis | Partial tear | Complete tear |
| Absent | 1,539 | 1,341 (87.1%) | 159 (10.3%) | 35 (2.3%) | 4 (0.3%) |
| Present | 138 | 92 (66.7%) | 31 (22.5%) | 12 (8.7%) | 3 (2.2%) |
| Values are n (row %). Ordinal tests use the ordering: none, tendinosis, partial tear, complete tear. Binary tests compare any pathology with none. P values account for repeated records within patients but are unadjusted for age, sex, or multiple comparisons. Records missing bursitis status are excluded. | |||||
- Trochanteric bursitis was associated with more frequent and more severe tendon pathology (ordinal and binary P < 0.001). Any pathology occurred in 33.3% of hips with bursitis versus 12.9% without bursitis.