Abstract
Aims
The primary aim of this study was to determine the ten-year outcome following surgical treatment for femoroacetabular impingement (FAI). We assessed whether the evolution of practice from open to arthroscopic techniques influenced outcomes and tested whether any patient, radiological, or surgical factors were associated with outcome.
Methods
Prospectively collected data of a consecutive single-surgeon cohort, operated for FAI between January 2005 and January 2015, were retrospectively studied. The cohort comprised 393 hips (365 patients; 71% male (n = 278)), with a mean age of 34.5 years (SD 10.0). Over the study period, techniques evolved from open surgical dislocation (n = 94) to a combined arthroscopy-Hueter technique (HA + Hueter; n = 61) to a pure arthroscopic technique (HA; n = 238). Outcome measures of interest included modes of failures, complications, reoperation, and patient-reported outcome measures (PROMs). Demographic, radiological, and surgical factors were tested for possible association with outcome.
Results
At a mean follow-up of 7.5 years (SD 2.5), there were 43 failures in 38 hips (9.7%), with 35 hips (8.9%) having one failure mode, one hip (0.25%) having two failure modes, and two hips (0.5%) having three failure modes. The five- and ten-year hip joint preservation rates were 94.1% (SD 1.2%; 95% confidence interval (CI) 91.8 to 96.4) and 90.4% (SD 1.7%; 95% CI 87.1 to 93.7), respectively. Inferior survivorship was detected in the surgical dislocation group. Age at surgery, Tönnis grade, cartilage damage, and absence of rim-trimming were associated with improved preservation rates. Only Tönnis grade was an independent predictor of hip preservation. All PROMs improved postoperatively. Factors associated with improvement in PROMs included higher lateral centre-edge and α angles, and lower retroversion index and BMI.
Conclusion
FAI surgery provides lasting improvement in function and a joint preservation rate of 90.4% at ten years. The evolution of practice was not associated with inferior outcome. Since degree of arthritis is the primary predictor of outcome, improved awareness and screening may lead to prompt intervention and better outcomes.
Cite this article: Bone Jt Open 2022;3(10):804–814.
Take home message
Femoroacetabular impingement (FAI) surgery provides a lasting improvement in functional scores and an acceptable joint preservation rate of 90.4% at ten years.
The evolution of practice over the years and transition to arthroscopic techniques was not associated with inferior outcome.
Since degree of arthritis is the primary predictor of outcome, improving the awareness and screening for FAI, and using more sensitive imaging modalities, may lead to earlier intervention and better outcome.
Introduction
Femoroacetabular impingement (FAI) is a well-recognized cause of hip pain and an established cause of early osteoarthritis (OA).1-5 When nonoperative measures fail to improve symptoms, surgical management is the treatment of choice aiming to preserve the native hip, alleviate symptoms, and perhaps reverse or halt the degenerative process.6,7
FAI surgical treatment has significantly evolved over the last two decades. Surgical dislocation was favoured initially, with very good early and mid-term results,8-11 and some recent long-term data.12 Surgical dislocation advanced our understanding of FAI and its pathomechanisms, allowing for the evolution of arthroscopic techniques, which are now the most common treatment modality for FAI, with surgical dislocation now reserved for more complex and combined deformities. Although excellent arthroscopic short-term outcome results have been described in the literature (between two and five years),13-17 longer-term data,18,19 as well as outcome data on how arthroscopic compares to open treatment of FAI,20 is limited.
The primary aim of this study was to determine the ten-year outcome of FAI treatment surgery, including the ten-year hip preservation rate and patient-reported outcome measures (PROMs). The secondary outcomes were to assess whether the evolution of practice from open to arthroscopic techniques was associated with differing outcomes and determine any patient, radiological, or surgical factors associated with long-term outcome.
Methods
This is a single-centre, single-surgeon, retrospective, institutional review board-approved cohort study. Our prospective hip preservation surgery database was queried to identify hips with a minimum five-year follow-up. Between 2005 and 2015, 412 hips that underwent surgical FAI treatment were reviewed. All patients had failed nonoperative treatment for at least six months. Exclusion criteria included previous hip surgery (n = 2), the presence of features of residual paediatric disease (e.g. slipped capital femoral epiphysis and Perthes’ disease) (n = 15), and the concomitant presence of symptomatic dysplasia requiring a periacetabular osteotomy (n = 2). The morphological type associated with FAI was classified by the lead surgeon (PEB) at the time of surgery and divided into three groups (cam, pincer, or mixed) using previously defined characteristics.21,22 The resulting 393 hips (365 patients) formed the study cohort.
Over the study period, three different surgical FAI techniques were performed, reflecting the worldwide evolution of practice over the same time period: surgical dislocation, hip arthroscopy combined with Hueter approach (HA+ Hueter),23,24 and hip arthroscopy alone (HA). The mean age was 34.5 years (standard deviation (SD) 10.0) and the majority were male (n = 278; 71%) (Table I). Overall, 94 hips were operated upon with an open surgical hip dislocation (n = 94), 61 hips underwent HA + Hueter, and the remaining 238 hips underwent HA. There were 284 hips with cam morphology, 22 hips with pincer morphology (18 global over-coverage and four acetabular isolated retroversion), and 87 hips with combined FAI (cam-pincer morphology with 60 global over-coverage and 27 isolated acetabular retroversion).
Table I.
Patient demographic details and morphological findings of the whole cohort, subdivided by surgical technique.
| Parameter | Cohort | Surgical dislocation | HA + Hueter | HA | p-value |
|---|---|---|---|---|---|
| Hips, n | 393 | 94 | 61 | 238 | |
| Mean age, yrs (SD) | 34.5 (10.0) | 32.4 (9.4) | 40.2 (7.9) | 33.9 (10 | < 0.001* |
| Male, n (%) | 278 (71) | 86 (91) | 44 (72) | 148 (63) | < 0.001† |
| Mean BMI, kg/m2 (SD) | 26.5 (4.6) | 26.7 (4.5) | 29.1 (5.3) | 25.8 (4.3) | 0.003* |
| Mean follow-up, yrs (SD) | 7.5 (2.5) | 9.5 (3) | 8.8 (1.6) | 6.3 (1.5) | < 0.001* |
| Morphology, n (%) | < 0.001† | ||||
| Cam | 284 (72.3) | 64 (67) | 32 (52) | 188 (79) | |
| Pincer | 22 (5.6) | 9 (9) | 1 (2) | 12 (5) | |
| Mixed | 87 (22.1) | 22 (23) | 28 (46) | 37 (16) | |
| Radiological findings | |||||
| Mean LCEA, ° (SD) | 38.4 (16.4) | 48.6 (19.3) | 39.3 (15.6) | 33.8 (13.1) | < 0.001* |
| Mean Tönnis angle, ° (SD) | -0.9 (11) | -5.9 (9.8) | -2.7 (12.3) | 1.6 (10.8) | < 0.001* |
| Mean α angle, ° (SD) | 58.6 (12.4) | 63.1 (14.7 | 59.3 (10.2) | 56.5 (11.4) | < 0.001* |
| Mean extrusion index (SD) | 16.6 (9.6) | 10.5 (10) | 15.7 (9.7) | 19.4 (8 | < 0.001* |
| Mean retroversion index (SD) | 14 (17.5) | 5.9 (14.4) | 15.9 (19.4) | 16.8 (17.2) | < 0.001* |
| Mean joint space < 2 mm, n (%) | 42 (11) | 4 (4) | 5 (8) | 33 (14) | 0.016† |
| Tönnis OA grade, n (%) | 0.001† | ||||
| 0 | 121(30.8) | 23(24) | 12 (20) | 86 (36) | |
| 1 | 232 (59) | 59(62) | 40 (65) | 133 (56) | |
| 2 | 30 (7.6) | 12(13) | 9 (15) | 9 (4) |
-
*
Kruskal-Wallis test.
-
†
Chi-squared test.
-
HA, hip arthroscopy; LCEA, lateral centre-edge angle; OA, osteoarthritis; SD, standard deviation.
Surgical details
The surgical dislocation technique and mid-term outcomes have been previously published (Figure 1).9,11 Arthroscopic treatment of FAI was initially introduced in 2005, and was combined with a Hueter approach for the femoral osteochondroplasty (FOCP) after addressing the central compartment pathology. Starting in 2009 after further training, the senior surgeon moved to a pure arthroscopic technique, slowly expanding to larger cam deformities. After three years, most of the FAI treatment was performed arthroscopically, with open surgical dislocation being reserved for more complex cases, e.g. those requiring extensive FOCP superior-laterally around the vascular pedicle and/or circumferential rim-trimming for global over-coverage. Arthroscopic surgery was performed in a supine position with a traction table, with a two-portal technique and a small, inter-portal capsulotomy. The central compartment was inspected and treated first, including any labral pathology. Following release of traction, attention was turned to the peripheral compartment were a FOCP was performed. Thus, in 2006, the percentage of arthroscopies and surgical dislocations was close to 50% each, while in 2012, 85% of cases were done only arthroscopically.
Fig. 1
Preoperative, immediate postoperative, and ten-year follow-up anteroposterior radiograph of a patient who underwent open surgical dislocation, labral repair, and femoral osteochondroplasty for the treatment of cam type femoroacetabular impingement.
Surgical details are summarized in Table II. A FOCP was performed in 371 hips (94%). A rim-trim was performed in 74 of the 109 hips with pincer morphology. Whenever possible the labrum was repaired (n = 140; 36%); 62 labral repairs were performed after rim-trim to reattach the labrum (surgical dislocation group). Otherwise, isolated labral-chondral debridement was performed (n = 248; 63%). A total of 47 hips (12%) underwent microfracture for acetabular chondral defects. The treating surgeon avoided labral resection to the bony rim and that labral debridement only involved the intra-articular-facing portion of the labrum at the junction of the acetabular cartilage, thus maximizing preservation of labral tissue.
Table II.
Surgical findings and type of procedure performed for the whole cohort, subdivided by surgical technique.
| Parameter | Cohort | Dislocation | HA + Hueter | HA | p-value* |
|---|---|---|---|---|---|
| Acetabular cartilage damage (Beck), n (%) | 0.265 | ||||
| Normal | 73 (19) | 23 (24) | 7 (11) | 43 (18) | |
| Malcia | 28 (7) | 6 (6) | 5 (8) | 17 (7) | |
| Debonding | 37 (9) | 4 (4) | 7 (11) | 26 (11) | |
| Cleavage | 151 (38) | 32 (34) | 25 (41) | 94 (39) | |
| Defect | 64 (16) | 20 (21) | 8 (13) | 36 (15) | |
| Surgical procedure, n (%) | |||||
| FOCP | 371 (94) | 86 (91) | 60 (98) | 225 (95) | 0.095 |
| Rim-trimming | 74 (19) | 41 (43) | 2 (3) | 31 (13) | < 0.001 |
| Chondrolabral debridement | 248 (63) | 53 (56) | 41 (67) | 154 (65) | 0.008 |
| Labral repair | 140 (36) | 47 (50) | 0 (0) | 93 (39) | < 0.001 |
| Microfracture | 47 (12) | 21 (22) | 3 (5) | 23 (10) | 0.003 |
| Labral reconstruction | 7 (1.8) | 7 (7) | 0 (0) | 0 (0) | < 0.001 |
-
*
Chi-squared test.
-
FOCP, femoral osteochondroplasty; HA, hip arthroscopy.
Radiological details
All patients had standardized preoperative, radiological evaluation as previously described: anteroposterior (AP) pelvis, 90° Dunn view, and cross-table lateral.21 Preoperative radiological analysis was performed on AP supine pelvic radiographs using Hip2Norm, a validated software (University of Bern, Switzerland).25 Several acetabular and femoral parameters were recorded, including lateral centre-edge angle (LCEA), acetabular index, α angle, joint space narrowing, percentage femoral head coverage, extrusion index, retroversion index, crossover sign, joint space width, and Tönnis grade.22,26 All measurements were performed by a hip preservation fellow not directly involved with patient care of this cohort (DF).
Surgical technique comparisons
Differences between the surgical technique groups were detected. In the HA group, there were more female patients, and the mean age and BMI were greater (Table I). Patients who underwent surgical dislocation had greater LCEA and α angle, and lesser acetabular, extrusion, and retroversion indexes (Table I). In addition, patients who underwent HA were more likely to have Tönnis grade 1 compared to the other groups (Table I). A greater proportion of cases in the surgical dislocation group underwent rim-trimming and labral repair. All these factors were therefore accounted for in subsequent multivariate analyses (Table II).
Outcome measures
All outcomes of interest were prospectively recorded. Length of outcome was determined from the last clinical encountered. Primary outcome was preservation of the hip joint with total hip arthroplasty as end point. Other outcomes included adverse events as defined by Sink et al27 and reoperation. In addition, we determined modes of joint preservation failure (Mode 1, arthritis progression leading to arthroplasty; Mode 2, incorrect diagnosis/procedure; Mode 3, mal-correction; and Mode 4, unintended consequence of the initial surgical intervention).28 Removal of symptomatic screws for trochanteric-sided pain was not considered a complication.
Secondary outcomes of interest included PROMs which were collected preoperatively and at latest follow-up using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC),29 Hip Disability and Osteoarthritis Outcome Score (HOOS), activites of daily living (ADL), sports recreation activities (SRA),30 and the University of California, Los Angeles Activity Score.31 The minimal clinically important difference (MCID) and the patient-acceptable symptom state (PASS) were determined for the HOOS subscales. The MCID values were five points for HOOS-ADL and six points for HOOS-SRA. Furthermore, we determined PASS values as described by Chahal et al32 as 87 for the HOOS-ADL and 75 for the HOOS-SRA.
All outcomes were described for the whole cohort and then compared for the three surgical subgroups. Furthermore, patient, disease, radiological, and surgical factors were tested for possible association with outcome following surgery. Age and BMI were categorized for the survivorship analysis.
Statistical analysis
Data are reported in accordance with STrengthening the Reporting of OBservational studies in Epidemiology guidelines.33 Data were summarized using descriptive statistics including count and percentages for categorical variables. Continuous variables were described using the mean and SD, and categorical variables were presented with total count and percentages. The chi-squared and Fisher’s exact tests were used to test for differences between categorical variables, and the Kruskal-Wallis test was used for continuous variables. A multivariable binary logistic regression model was fitted to assess the impact of patient, disease, radiological, and surgical factors on joint preservation rate and achieving MCID and PASS, while adjusting for potential confounders. The variables included in the multivariable logistic regression model were selected based on the statistically significant results (p < 0.1) of univariate logistic regression model including only one potential predictor. Kaplan-Meier survival curves were used to determine joint preservation rate. A Cox regression analysis was run to determine factors associated with failure. The level of significance was set at p < 0.05. The variables included in the analysis were selected based on the statistically significant results of the univariate analysis. All analysis was performed using SPSS for Mac 9 v. 27 (IBM, USA).
Results
Mode of failure and reoperations
At a mean follow-up of 7.5 years (SD 2.5; ranging from 1.1 (early conversion to arthroplasty) to 14.2), there were 43 failures in 38 hips (9.7%), 35 hips (8.9%) having one failure mode, one hip (0.25%) having two failure modes, and two hips (0.5%) having three failure modes. The most common mode of failure was mode 1 (n = 31; 7.8%), followed by mode 3 (n = 5; 1%), mode 2 (n = 4; 1%), and mode 4 (n = 4; 1%) (Figure 2; Table III). A total of 37 patients (39% of surgical dislocations) underwent removal of screws.
Fig. 2
Reoperations and failures among the cohort and the three surgical groups. GT, greater trochanter; HA, hip arthroscopy; SD, surgical dislocation.
Table III.
Modes of failure and type of related reoperation among the cohort and the three surgical groups.
| Mode of failure | Cohort | Surgical dislocation | HA + Hueter | HA | p-value* |
|---|---|---|---|---|---|
| Mode 1, n | |||||
| Hip arthroplasty | 31 | 14 | 4 | 13 | 0.054 |
| Mode 2, n | |||||
| Hip Scope | 1 | 0 | 0 | 1 (rim-trim) | 0.511 |
| PAO | 3 | 0 | 1 (anteverting) | 2 (1 anteverting, 1 instability) | |
| Mode 3, n | |||||
| Hip scope | 5 | 1 (labral tear) | 1 (residual cam) | 3 (3 labral tears) | 0.952 |
| Mode 4, n | |||||
| Hip scope | 3 | 0 | 1 adhesiolysis | 2 (1 adhesiolysis, 1 loose anchor) | 0.858 |
| GT fracture | 1 | 1 | 0 | 0 |
-
*
Chi-squared test.
-
GT, greater trochanter; HA, hip arthroscopy; PAO, periacetabular osteotomy.
Survival
The mean time to arthroplasty was 3.9 years (SD 2.0) and was not different between surgical groups (p = 0.477, Kruskal-Wallis test). For the whole cohort, the five- and ten-year hip joint preservation rates were 94.1% (SD 1.2; 95% CI 91.8 to 96.4) and 90.4% (SD 1.7; 95% CI 87.1 to 93.7), respectively (Figure 3). Inferior survivorship was detected in the surgical dislocation group at both five and ten years (Figure 4; Table IV). Age at surgery (below 35 years), Tönnis grade (0), cartilage damage per Beck et al2 (≤ 2) absence of rim-trimming were associated with improved preservation in the univariate analysis (Table V; Figure 5). In the cox regression analysis, only Tönnis grade, was an independent predictor of hip preservation (Table VI).
Fig. 3
Survival analysis for the whole cohort with conversion to arthroplasty as the endpoint.
Fig. 4
Survival analysis, color coded for the three surgical groups. HA, hip arthroscopy only; SD,surgical dislocation.
Table IV.
Five- and ten-year survivorship for the whole cohort and the three different surgical groups.
| Survival | Cohort | Surgical dislocation | HA + Hueter | HA | p-value* |
|---|---|---|---|---|---|
| 5-yr survival (95% CI) | 94.1 (91.8 to 96.4) | 88.3 (80.7 to 95.9) | 96.6 (93.2 to 98.2) | 95.7 (93.2 to 98.2) | 0.048 |
| 10-yr survival (95% CI) | 90.4 (87.1 to 93.7) | 81.6 (72.2 to 91.0) | 93.2 (86.7 to 99.7) | 92.9 (89.2 to 96.6) | 0.018 |
-
*
Log-rank test.
-
CI, confidence interval; HA, hip arthroscopy.
Table V.
Factors associated with hip joint preservation rate and conversion to hip arthroplasty.
| Factor | 10-yr survival, % (SD; 95% CI) | p-value* |
|---|---|---|
| Demographic factors | ||
| Age (yrs) | 0.018 | |
| < 35 | 94.7 (1.8; 91.2 to 98.2) | |
| > 35 | 86.3 (2.8; 80.8 to 91.8) | |
| Sex | 0.640 | |
| Male | 90.8 (2; 86.9 to 94.7) | |
| Female | 89.8 (3.1(83.8 to 95.8) | |
| BMI (kg/m 2 ) | 0.707 | |
| < 30 | 86.6 (3.3; 80.1 to 93.1) | |
| > 30 | 87.2 (5.4; 76.7 to 97.7) | |
| Morphology group | 0.067 | |
| Cam | 90.8 (2.1; 86.7 to 94.9) | |
| Pincer | 69.4 (13.7; 42.6 to 96.2) | |
| Mixed | 91.9 (3.2; 85.7 to 98.1) | |
| Radiological factors | ||
| Tönnis grade | < 0.001 | |
| 0 | 99.1 (0.9; 97.4 to 100) | |
| 1 | 89 (2.4; 84.3 to 93.7) | |
| 2 | 68.4 (9.3; 50.4 to 86.4) | |
| LCEA, ° | 0.532 | |
| < 35 | 92 (2.2; 87.7 to 96.3) | |
| > 35 | 88.7 (2.8; 83.2 to 94.2) | |
| α angle, ° | 0.640 | |
| < 70 | 91.3 (1.9; 87.6 to 95) | |
| > 70 | 88.4 (4.7; 80.9 to 95.9) | |
| Acetabular index, ° | 0.887 | |
| < 0 | 89.1 (2.8; 83.6 to 94.6) | |
| > 0 | 91.7 (2.1; 87.6 to 95.8) | |
| Joint space, mm | 0.246 | |
| < 2 | 84.9 (6.4; 72.4 to 97.4) | |
| > 2 | 90.8 (1.9; 87.1 to 94.5) | |
| Surgical factors | ||
| Cartilage damage; per Beck) | 0.061 | |
| 1 to 2 | 96.4 (2.1; 92.3 to 100) | |
| ≥ 3 | 88.5 (2.2; 84.4 to 92.8) | |
| Rim-trimming | 0.032 | |
| No | 91.4 (1.9; 87.8 to 95) | |
| Yes | 79.2 (6.8; 59.9 to 86.5) | |
| Microfracture | 0.346 | |
| No | 88.4 (2.2; 84.1 to 92.7) | |
| Yes | 95.2 (3.3; 88.7 to 100) | |
| Labral repair | 0.338 | |
| No | 88.9 (2.3; 84.4 to 93.4) | |
| Yes | 87 (5.3; 76.6 to 97.4) |
-
*
Log-rank test.
-
CI, confidence interval; LCEA, lateral centre-edge angle; SD, standard deviation.
Fig. 5
Survival analysis, colour-coded for the factors associated with survival and a) age, b) Tönnis grade, c) cartilage damage per Beck, and d) rim-trimming as a part of surgery.
Table VI.
Cox regression analysis of factors associated with hip joint preservation rate. Significant factors (p < 0.1) in the Kaplan-Meier survival analysis were included in the analysis.
| Factor | β co-efficient (95% CI) | p-value* |
|---|---|---|
| Age | 0.58 (0.23 to 1.44) | 0.236 |
| Tönnis grade | 9.31 (1.19 to 72.52) | 0.033 |
| Beck cartilage damage | 0.32 (0.09 to 1.1) | 0.067 |
| Rim-trimming | 0.58 (0.20 to 1.75) | 0.336 |
| FAI group morphology | 0.8 (0.3 to 2.6) | 0.293 |
| Surgical group | 0.38 (0.47 to 7.3) | 0.237 |
-
*
Cox regression analysis.
-
CI, confidence interval; FAI, femoroacetabular impingement.
PROMs
PROMs were available for 274 hips (70%) preoperatively and 218 hips (56%) postoperatively. There was a significant improvement for all PROMs (Table VII). Complete pre- and postoperative PROMs were available for 218 hips (56%); there was no difference between those with PROMs available or not between the three treatment groups (p = 0.099, chi-squared test). MCID for HOOS-ADL and HOOS-SRA was achieved for 65% (118/181) and 71% of cases (129/181), respectively. PASS for HOOS-ADL was achieved in 47% of cases (106/224) and PASS for HOOS-SRA was achieved in 46% of cases (100/219). There were significant differences between groups regarding the improvements of the PROMs with better improvement in the surgical dislocation group for HOOS-SRA (p = 0.027, Kruskal-Wallis test), and UCLA (p = 0.003, Kruskal-Wallis test). Patients who achieved MCID for HOOS-ADL had higher LCEA (38.6 (SD 14.6) vs 33.7 (SD 12.3); p = 0.022, Mann-Whitney U test) and lower retroversion index (16.7 (SD 15.6) vs 11.8 (SD 16.5); p = 0.024, Mann-Whitney U test) compared to those who did not achieve MCID for HOOS-ADL. Patients who achieved PASS for HOOS-ADL had lower BMI (25.0 (SD 3.8) vs 27.6 (SD 5.2); p = 0.001, Mann-Whitney U test) and higher preoperative α angles (58.5 (SD 13.1) vs 55.4 (SD 11.9); p = 0.031, Mann-Whitney U test) compared to those who did not achieve PASS for HOOS-ADL.
Table VII.
Patient-reported outcome measures.
| PROM | Cohort | Surgical dislocation | HA + Hueter | HA | p-value |
|---|---|---|---|---|---|
| WOMAC (SD) | |||||
| Preoperative | 60 (21) | 58 (19) | 62 (20) | 61 (21) | 0.572* |
| Postoperative | 75 (21) | 77 (20) | 71 (24) | 75 (21) | 0.424* |
| Change | 19 (26) | 30 (33) | 13 (22) | 17 (24) | 0.115* |
| HOOS-ADL (SD) | |||||
| Preoperative | 65 (23) | 64 (20) | 65 (20) | 66 (24) | 0.590* |
| Postoperative | 78 (21) | 81 (19) | 74 (24) | 78 (22) | 0.426* |
| Change | 17 (26) | 24 (28) | 14 (23) | 15 (25) | 0.306* |
| MCID, % | 65 | 77 | 64 | 62 | 0.251† |
| PASS, % | 47 | 50 | 39 | 49 | 0.495† |
| HOOS-SRA (SD) | |||||
| Preoperative | 43 (26) | 36 (23) | 49 (23) | 43 (27) | 0.033* |
| Postoperative | 63 (27) | 67 (26) | 61 (28) | 63 (28) | 0.571* |
| Change | 22 (31) | 36 (31) | 14 (29) | 21 (30) | 0.027* |
| MCID, % | 71 | 86 | 67 | 68 | 0.108† |
| PASS, % | 46 | 48 | 37 | 48 | 0.432† |
| UCLA (SD) | |||||
| Preoperative | 6.9 (2.6) | 6.9 (2.6) | 6.6 (2.8) | 6.9 (2.6) | 0.783* |
| Postoperative | 7.2 (2.4) | 7.6 (2.2) | 7.1 (2.5) | 7.1 (2.5) | 0.559* |
| Change | 0.9 (3.8) | 2.5 (4.5) | 1.9 (4.3) | 0.1 (3) | 0.003* |
-
*
Kruskal-Wallis test.
-
†
Chi-squared test.
-
ADL, activities of daily living; HA, hip arthroscopy; HOOS, Hip Disability and Osteoarthritis Outcome Score; MCID, minimal clinically important difference; PASS, patient-acceptable symptom state; PROM, patient-reported outcome measure; SD, standard deviation; SRA, sports recreation activities; UCLA, University of California, Los Angeles Activity Score; WOMAC, Western Ontario and McMaster Universities Arthritis Index.
Discussion
FAI is a recognized cause of hip pain and a precursor of hip OA.1,3-5,34 However, contrary to dysplasia, where long-term outcome following acetabular osteotomy has been well-described, the medium- and long-term chances of hip preservation among hips suffering from FAI are still limited.18,35 The main finding of this study is that the ten-year hip preservation rate following surgical FAI treatment was 90.4%. This is a very promising finding, emphasizing the value of FAI procedures and is in line with other studies that have primarily focused on reporting outcome of FAI treatment using a single technique (Table VIII).
Table VIII.
Review of the literature on long-term survival and its predictors after femoroacetabular impingement surgery.
| Study | Surgical technique | 10-yr hip preservation rate, % | Factors influencing survival |
|---|---|---|---|
| Current study | Surgical dislocation, HA + Hueter, and HA | 90.4 | Surgical technique, age, Tönnis grade, rim-trimming |
| Steppacher et al12,36 | Surgical dislocation | 89 | Age, BMI, LCEA, posterior acetabular coverage |
| Menge et al18 | HA | 66 | Age, joint space < 2 mm, microfracture |
| Byrd and Jones35 | HA (but not FAI as diagnosis) | 72 | Preoperative OA, avascular necrosis |
| Ceylan et al37 | HA + Hueter | 90.92 | Age, BMI, duration of symptoms, acetabular dysplasia and retroversion, higher α angle, cartilage damage, and labral resection. |
-
FAI, femoroacetabular impingement; HA, hip arthroscopy; LCEA, lateral centre-edge angle; OA, osteoarthritis.
The diagnosis and treatment of FAI has undergone significant evolution over recent years and continues to evolve. This is demonstrated by the dramatic increase in the use of arthroscopic techniques for the treatment, and the description of new treatment options.38,39 Changing surgical techniques should always be done cautiously, so that patient safety and effectiveness are not compromised.40 As there has been an evolution of practice in our centre, like others around the world, it was prudent to examine this, and it is reassuring to report that outcome was very good across the three surgical techniques. Hips that underwent HA and HA + Hueter had better chances of joint preservation at ten years (92.9% and 93.2%), compared to the surgical dislocation group (81.6%). A lower ten-year preservation rate in the surgical dislocation group is likely to due to selection bias, as patients in the surgical dislocation group had different demographic characteristics, more complex morphologies, and a greater incidence of radiological joint degeneration, all of which are now recognized hallmarks associated with inferior outcome.41-44 This is further reflected by more severe intra-articular cartilaginous damage,45,46 and the need to perform microfracture (22%), compared to the other groups. Perhaps equally importantly, a higher percentage of cases underwent acetabular rim-trimming in the surgical dislocation group, which may be associated with inferior survivorship, a finding consistent with Steppacher et al.11 The possible negative association of rim-trim with long-term outcome requires further study and could not be independently tested in this cohort. These results are partly in line with the systematic review of Nwachukwu et al47 comparing open to arthroscopic techniques, which reported found comparable survivorships at four years between open (93%) and arthroscopic (90.5%) techniques. Some studies have concluded that the open technique allows a degree of correction that is difficult to reproduce arthroscopically, and that this possible under-correction may be responsible for a more rapid arthritic progress described.48-50
As we have gained a better understanding of what represents abnormal bony morphology, treatment principles have evolved. Acetabular rim-trimming has been shown to negatively influence outcome in the setting of retroversion.51 It is thus plausible that reoperations which took place secondary to mode 2 failures were due to the lack of appreciation that a periacetabular osteotomy would be more suitable for the treatment of acetabular retroversion compared to isolated arthroscopic management. In our study, age, Tönnis grade, and cartilage damage were correlated with the survival of the native hip joint. The importance of these factors has been previously described in the literature,41-44 further emphasizing the importance of timely identifications of hips at risk and prompt treatment. Surprisingly, other demographics, and radiological (< 2 mm joint-space narrowing) and surgical findings (labral repair), had no influence on the survival. The value of assessing for joint narrowing preoperatively and repairing the labrum when possible have been illustrated and form part of our current algorithm.16,18,36,40,44,52
Surgical FAI treatment is associated with improvement of most PROMs.8,14,15,17,19,24,53-55 The degree of improvement in PROMs for our patients at last follow-up was consistent with the short- to mid-term literature.56 It is therefore reassuring concerning the long-term maintenance of improvement in quality of life that one can expect following FAI treatment. We found a significantly greater improvement in the surgical dislocation group compared to the other two groups for all PROMs except HOOS-ADL. This difference may be due to disparities between groups and does not appear to be previously documented.47 However, it was difficult to compare the different techniques due to a lack of homogeneity of the scores in the different studies.53 In our study, we observed that the lower BMI, higher LCEA and α angle, and lower Tönnis grade were all correlated with improvement in PROMs. It is postulated that the higher the preoperative α angle, the greater the gain in mobility and improvement of adverse mechanics. The lesser improvement in PROMs in patients with more advanced Tönnis grades was also reported by Larson et al,16 who observed lower postoperative modified Harris Hip Scores57 with higher Tönnis grade and cartilage damage on MRI. Steppacher et al12 also observed a correlation between postoperative outcomes and LCEA, as well as BMI and age.
This study has several limitations. First, it is a retrospective design where patient selection biases are present. However, a prospectively collected database was used, which allows for accurate capture of all pertinent data used for analysis. Second, this is a single-surgeon series and thus suffers from certain operator-dependent biases such diagnosis at the time of surgery. However, all radiological assessments were repeated using a validated tool and clearly identified cam and/or pincer to be present in all hips; hence, all cases satisfied diagnostic radiological criteria. Additionally, the type of procedure performed was similarly determined by the surgeon. Finally, comprehensive PROM data were only captured in 56% of patients, which may lead to selection biases of reported results.
In conclusion, regardless of whether open or arthroscopic surgical technique is used, FAI surgery provides a lasting improvement in functional scores and an acceptable joint preservation rate of 90.4% at ten years. The evolution of practice over the years and transition to arthroscopic techniques was not associated with inferior outcome. Since the degree of OA is the primary predictor of outcome, improving the awareness and screening for FAI and using more sensitive imaging modalities may lead to earlier intervention and better outcome.58
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Author contributions
G. Grammatopoulos: Conceptualization, Methodology, Formal analysis, Writing – original draft, Writing – review & editing.
P. Laboudie: Conceptualization, Methodology, Investigation, Data curation, Formal analysis, Project administration, Writing – original draft, Writing – review & editing.
D. Fischman: Conceptualization, Formal analysis, Methodology, Writing – review & editing.
R. Ojaghi: Conceptualization, Formal analysis, Writing – review & editing.
A. Finless: Conceptualization, Methodology, Writing – review & editing.
P. E. Beaulé: Conceptualization, Methodology, Investigation, Data curation, Formal analysis, Writing – original draft, Writing – review & editing.
Funding statement
The authors received no financial or material support for the research, authorship, and/or publication of this article.
ICMJE COI statement
Each author certifies that he or she has no commercial associations that might pose a conflict of interest in connection with the submitted article.
Acknowledgements
The authors would like to acknoledge Johanna Dobransky for her administrative support in completing the data collection.
Ethical review statement
This research has been approved by the Ottawa Health Science Research Ethics Board prior to data collection and we have complied with ethical principles regarding research with human participants.
Open access funding
The authors confirm that the open access fee was self-funded.
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