Prevalence and characteristics of cam-type femoroacetabular deformity in 100 hips with symptomatic acetabular dysplasia: a case control study

Influence of acetabular and femoral morphology on pelvic tilt

Aims

The aim of this study was to investigate whether anterior pelvic plane-pelvic tilt (APP-PT) is associated with distinct hip pathomorphologies. We asked: is there a difference in APP-PT between young symptomatic patients being evaluated for joint preservation surgery and an asymptomatic control group? Does APP-PT vary among distinct acetabular and femoral pathomorphologies? And does APP-PT differ in symptomatic hips based on demographic factors?

Methods

This was an institutional review board-approved, single-centre, retrospective, case-control, comparative study, which included 388 symptomatic hips in 357 patients who presented to our tertiary centre for joint preservation between January 2011 and December 2015. Their mean age was 26 years (SD 2; 23 to 29) and 50% were female. They were allocated to 12 different morphological subgroups. The study group was compared with a control group of 20 asymptomatic hips in 20 patients. APP-PT was assessed in all patients based on supine anteroposterior pelvic radiographs using validated HipRecon software. Values in the two groups were compared using an independent-samples t-test. Multiple regression analysis was performed to examine the influences of diagnoses and demographic factors on APP-PT. The minimal clinically important difference (MCID) for APP-PT was defined as > 1 SD.

Results

There were no significant differences in APP-PT between the control group and the overall group (1.1° (SD 3.0°; -4.9° to 5.9°) vs 1.8° (SD 3.4°; -6.9° to 13.2°); p = 0.323). Acetabular retroversion and overcoverage groups showed higher mean APP-PTs compared with the control group (p = 0.001 and p = 0.014) and were the only diagnoses with a significant influence on APP-PT in the stepwise multiple regression analysis. All differences were below the MCID. The age, sex, height, weight, and BMI showed no influence on APP-PT.

Conclusion

APP-PT showed no radiologically significant variation across different pathomorphologies of the hip in patients being assessed for joint-preserving surgery.

Hip Pain and Movement Dysfunction Associated With Nonarthritic Hip Joint Pain: A Revision

The Academy of Orthopaedic Physical Therapy (AOPT), formerly the Orthopaedic Section of the American Physical Therapy Association (APTA), has an ongoing effort to create evidence-based practice guidelines for orthopaedic physical therapy management of patients with musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability, and Health (ICF). This is an update to the 2014 Clinical Practice Guideline (CPG) for Hip Pain and Movement Dysfunction Associated with Nonarthritic Hip Joint Pain. The goals of the revision were to provide a concise summary of the contemporary evidence since publication of the original guideline and to develop new recommendations or revise previously published recommendations to support evidence-based practice. This current CPG covers pathoanatomical features, clinical course, prognosis, diagnosis, examination, and physical therapy interventions in the management of nonarthritic hip joint pain. J Orthop Sports Phys Ther 2023;53(7):CPG1-CPG70. doi:10.2519/jospt.2023.0302.

Central acetabular osteophytes (CAO) are more prevalent in the borderline developmental dysplastic hip (BDDH) patients: a propensity-score matched CT study

Background

The acetabular fossa often showing the first signs of degeneration, Central acetabular osteophytes (CAO) have been increasingly recognized during hip arthroscopy. The purpose of this study was to investigate the condition of CAO in BDDH hips and compare cotyloid fossa size between the BDDH and the non-BDDH hips on CT images.

Methods

We performed a retrospective analysis of prospectively collected data of hip CT images of FAI or labral injury patients. A 1:2 propensity-score matched observational study comparing the linear length of cotyloid fossa was analyzed. Cotyloid fossa width (CFW) and cotyloid notch width (CNW) were measured on axial images, cotyloid fossa height (CFH) and cotyloid fossa depth (CFD) were measured on coronal images. Within the CAO patients, we performed central acetabular decompression (CAD) and then observed the morphology change in fossa.

Results

Propensity-score matching yielded 61 BDDH hips and 122 non-BDDH hips. BDDH hips had a higher prevalence of CAO and a decreased linear length of cotyloid fossa (CFW, CFH and CNW). In the BDDH group, 33 hips underwent CAD, postoperative CFW, CFH and CNW were significantly increased (p < .001 for all), and had no statistical difference compared with the non-BDDH hips (p = .193, p = .132, p = .421, respectively).

Conclusion

BDDH hips had a significantly higher prevalence of CAO than adequate acetabular coverage hips. After the procedure of CAD, BDDH hips were found to have acetabular parameters (CFW, CFH, CNW) and were restored to that of the control hips.

The prevalence and risk factors of pubic bone marrow edema in femoroacetabular impingement and hip dysplasia

Femoroacetabular impingement syndrome (FAIS) has been associated with osteitis pubis; however, it is still unclear whether hip dysplasia is associated with osteitis pubis. This study aimed to investigate (i) the incidence of pubic bone marrow edema (BME) on magnetic resonance imaging in symptomatic patients with FAIS, borderline developmental dysplasia of the hip (BDDH) and developmental dysplasia of the hip (DDH) undergoing hip arthroscopic surgery with labral preservation and (ii) the demographic and radiographic factors associated with pubic BME. A total of 259 symptomatic patients undergoing hip arthroscopic surgery between July 2016 and April 2019 were retrospectively reviewed and divided into three groups: FAIS (180 patients), BDDH (29 patients) and DDH (50 patients). Diffuse changes in the pubic bone adjacent to the pubic symphysis were labeled pubic BME, and the prevalence of their occurrence was examined. Multivariate logistic regression analysis was performed to identify factors involved in pubic BME, and odds ratios (ORs) for relevant factors were calculated. There was no significant difference in the prevalence of pubic BME among the three groups (20 [11.1%] of 180 FAIS patients, 6 [20.6%] of 29 BDDH patients and 7 [14%] of 50 DDH patients, P = 0.325). Multivariate logistic regression analysis showed that acetabular coverage was not associated with pubic BME, whereas younger age and greater alpha angle were still independent associated factors [age ≤26 years (OR, 65.7) and alpha angle ≥73.5° (OR, 4.79)]. Determining the possible association of osteitis pubis with cam impingement in dysplastic hips may provide insights toward a more accurate understanding of its pathophysiology.

Statistical shape modeling of the hip and the association with hip osteoarthritis: a systematic review

OBJECTIVE

To summarize available evidence on the association between hip shape as quantified by statistical shape modeling (SSM) and the incidence or progression of hip osteoarthritis.

DESIGN

We conducted a systematic search of five electronic databases, based on a registered protocol (available: PROSPERO CRD42020145411). Articles presenting original data on the longitudinal relationship between radiographic hip shape (quantified by SSM) and hip OA were eligible. Quantitative meta-analysis was precluded because of the use of different SSM models across studies. We used the Newcastle-Ottawa Scale (NOS) for risk of bias assessment.

RESULTS

Nine studies (6,483 hips analyzed with SSM) were included in this review. The SSM models used to describe hip shape ranged from 16 points on the femoral head to 85 points on the proximal femur and hemipelvis. Multiple hip shape features and combinations thereof were associated with incident or progressive hip OA. Shape variants that seemed to be consistently associated with hip OA across studies were acetabular dysplasia, cam morphology, and deviations in acetabular version (either excessive anteversion or retroversion).

CONCLUSIONS

Various radiographic, SSM-defined hip shape features are associated with hip OA. Some hip shape features only seem to increase the risk for hip OA when combined together. The heterogeneity of the used SSM models across studies precludes the estimation of pooled effect sizes. Further studies using the same SSM model and definition of hip OA are needed to allow for the comparison of outcomes across studies, and to validate the found associations.

Arthroscopic labral repair for femoroacetabular impingement: A systematic review

BACKGROUND

The present systematic review investigated return to sport, patient reported outcome measures (PROMs), complications and subsequent progression to total hip arthroplasty (THA) in patients undergoing arthroscopic labral repair for FAI.

MATERIAL AND METHODS

Following the PRISMA statement, the literature search was performed in February 2021. The outcomes of interest were: rate of return to sport, modified Harris Hip Score (mHHS), the subscales Activities of Daily Living and Sport-Specific Subscale of the Hip Outcome Score (HOS-ADL and HOS-SSS, respectively). Complications, revision surgeries and progression to total hip arthroplasty were recorded.

RESULTS

Data from 210 procedures were retrieved. The mean follow-up was 34.0 (24.0-42.5) months. The mean age of the patients was 32.0 (20.0-47.0) years, while the mean BMI was 20.9 (20.1-21.7) kg/m². 52.8% (111 of 210 patients) were women. At 24-month follow-up, 100% of the patients had returned to sport. At a mean of 34 months follow-up, the mean mHHS increased by 25.5% (P = 0.02), the mean HOS-ADL by 23.0% (P = 0.03), the mean HOS-SSS by 32.8% (P = 0.001). No complications were observed. The rate of revision was 4.3% (9 of 210 procedures). At a mean of 37.9 ± 7.5 months, 1.9% of patients (4/210) underwent THA.

CONCLUSION

Arthroscopic labral refixation for FAI yields reliably positive clinical outcomes, with a low rate of revision and conversion to THA.

Increased range of motion but otherwise similar clinical outcome of arthroscopy over open osteoplasty for femoroacetabular impingement at midterm follow-up: A systematic review

BACKGROUND

A systematic review was conducted comparing patient reported outcomes measures (PROMs), functional scores, and the rate of complications between arthroscopic and open treatment for femoroacetabular impingement (FAI) at mid-term follow-up.

MATERIAL AND METHODS

This systematic review was performed according to the PRISMA guidelines. The literature search was performed in October 2020. All clinical trials treating FAI using open osteoplasty or arthroscopic surgery were considered for inclusion. Only articles reporting >12 months follow-up were included.

RESULTS

Data from 97 articles (9981 procedures) were collected. At a mean 19.2 months follow-up there was no difference between the two cohorts. At a mean follow-up of 38 months, the external rotation was increased in the arthroscopic group (P < 0.0001). The modified Harris Hip Score scored greater in favour of the open osteoplasty group (P = 0.04), as did the Hip Outcome Score - Activities of Daily Living subscale (P = 0.01). At a mean 45.1 months the arthroscopic group presented greater external rotation (P < 0.0001) and SF-12 Mental (P = 0.04). The modified Harris Hip Score was greater in favour of the open osteoplasty group (P = 0.03), as was the HOS-ADL (P = 0.01). Regarding complications, the arthroscopic group experienced lower rates of subsequent revisions (P < 0.0001).

CONCLUSION

Based on the significant reduction of revisions-rate and significant increase in range of motion, arthroscopy treatment for the management of FAI may be recommended.

Editorial Commentary: A Simple Twist of Fate: The Ramifications of Abnormal Femoral Version

The abnormalities of femoral twist or version, whether increased anteversion or retroversion, are frequently overlooked. These skeletal aberrations are responsible for a host of hip problems such as impingement, instability and damage to the labrum and articular cartilage, often resulting in osteoarthritis if left untreated. In addition to the intrinsic hip damage, extra articular problems such as posterior hip impingement, pelvic tendonopathies, problems with gait and sitting as well as spinal decompensation are also very common. It is incumbent upon those who manage hip problems to be aware of the damage caused by femoral version abnormalities and the treatment options available.

Use of a 3D Virtually Reconstructed Patient-Specific Model to Examine the Effect of Acetabular Labral Interference on Hip Range of Motion

Background:

The labrum is likely to influence impingement, which may also depend on acetabular coverage. Simulating impingement using 3-dimensional (3D) computed tomography (CT) is a potential solution to evaluating range of motion (ROM); however, it is based on bony structures rather than on soft tissue.

Purpose:

To examine ROM when the labrum is considered in a 3D dynamic simulation. A particular focus was evaluation of maximum flexion and internal rotation angles before occurrence of impingement, comparing them in cases of cam-type femoroacetabular impingement (FAI) and borderline developmental dysplasia of the hip (BDDH).

Study Design:

Descriptive laboratory study.

Methods:

Magnetic resonance imaging (MRI) and CT scans of 40 hips (20 with cam-type FAI and 20 with BDDH) were reviewed retrospectively. The thickness and width of the labrum were measured on MRI scans. A virtual labrum was reconstructed based on patient-specific sizes measured on MRI scans. The impingement point was identified using 3D dynamic simulation and was compared with the internal rotation angle before and after labral reconstruction.

Results:

The thickness and width of the labrum were significantly larger in BDDH than in FAI (P < .001). In FAI, the maximum internal rotation angles without the labrum were 30.3° at 90° of flexion and 56.9° at 45° of flexion, with these values decreasing to 18.7° and 41.4°, respectively, after labral reconstruction (P < .001). In BDDH, the maximum internal rotation angles were 48.0° at 90° of flexion and 76.7° at 45° of flexion without the labrum, decreasing to 31.1° and 55.3°, respectively, after labral reconstruction (P < .001). The differences in the angles before and after labral reconstruction were larger in BDDH than in FAI (90° of flexion, P = .03; 45° of flexion, P = .01).

Conclusion:

As the labrum was significantly more hypertrophic in BDDH than in FAI, the virtual labral model revealed that the labrum’s interference with the maximum internal rotation angle was also significantly larger in BDDH.

Clinical Relevance:

The labrum has a significant effect on impingement; this is more significant for BDDH than for FAI.

Arthroscopic Management of Subspinous Impingement in Borderline Hip Dysplasia and Outcomes Compared With a Matched Cohort With Nondysplastic Femoroacetabular Impingement

BACKGROUND

Arthroscopic management of femoroacetabular impingement (FAI) in the setting of borderline hip dysplasia is controversial. Recently, there has been increased awareness of a prominent anterior inferior iliac spine (AIIS) resulting in subspinous impingement.

PURPOSE/HYPOTHESIS

The purpose was to report outcomes of arthroscopic subspinous decompression in patients with symptomatic hip impingement and borderline hip dysplasia compared with a matched cohort with nondysplastic FAI. Addressing a prominent subspinous region and cam/pincer lesion in the borderline dysplastic hip may lead to favorable outcomes comparable with those of patients undergoing arthroscopic management of nondysplastic FAI.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients with symptomatic hip impingement, borderline dysplasia (lateral center-edge angle [LCEA], 18°-24°), and prominent AIIS (BDSI group) whose nonoperative management failed and who subsequently underwent arthroscopic subspinous decompression were retrospectively identified. Three-dimensional computed tomography imaging was used to categorize AIIS morphology into type 1, 2, or 3 (Hetsroni classification). Patient-reported outcome (PRO) scores consisting of the modified Harris Hip Score (mHHS), Hip Outcome Score-Activities of Daily Living (HOS-ADL), and Hip Outcome Score-Sport-Specific Subscale (HOS-SSS) were obtained preoperatively and at an average of 44 months postoperatively (range, 23-61 months). Exclusion criteria were Tönnis osteoarthritis grade >1 and a history of previous hip procedures. An age-, sex-, and body mass index-matched cohort of patients without dysplasia (LCEA, >25°) who underwent arthroscopic FAI surgery with a minimum 2-year follow-up were selected to serve as the control group.

RESULTS

Eighteen patients, 19 hips (14 women and 4 men; average age, 28 years) were included. Of the 19 hips in the BDSI group, the average LCEA and alpha angle were 21.8° and 66.2°, respectively; 14 hips were Hestroni type 2, and 5 hips were type 1. There were no postoperative complications or additional procedures performed since the last follow-up. Repeated-measures analysis of variance revealed a significant improvement in all PRO scores from preoperatively to the last follow-up: mHHS, 64.7 to 87.7 (P < .001); HOS-ADL, 62.1 to 92.1 (P < .001); HOS-SSS, 26.5 to 87.1 (P < .001). An analysis of covariance revealed that patients with type 2 AIIS had a significantly higher postoperative mHHS than those with a type 1 morphology (88.3 and 95.6, respectively; P < .01) The BDSI group had a significantly lower preoperative HOS-SSS (26.5; P < .001) in comparison with the control group. However, there was no significant difference in postoperative outcome scores between groups. The BDSI group underwent significantly more microfracture, capsular plication, and ligamentum teres debridement (15.8%; P = .04).

CONCLUSION

Arthroscopic AIIS decompression in patients with coexisting borderline dysplasia and subspinous impingement is a safe and effective method of treatment that produces outcomes comparable with those of a cohort with nondysplastic FAI.

Surgical Outcomes in the Treatment of Concomitant Mild Acetabular Dysplasia and Femoroacetabular Impingement: A Systematic Review

PURPOSE

To analyze the current approaches and clinical outcomes in the surgical management of concomitant mild acetabular dysplasia and femoroacetabular impingement (FAI).

METHODS

Following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) method, the PubMed and Medline databases were searched in March 2019 for studies that reported on surgical outcomes in hips with concomitant mid acetabular dysplasia and FAI. Studies published in English that focused on the surgical outcomes after hip arthroscopy, open surgery, or periacetabular osteotomy of concomitant acetabular dysplasia and FAI, in which the lateral center-edge angle of all subjects was between 15° and 25°, were included. Articles that included subjects with lateral center-edge angle <15°, with a minimum follow-up duration <1 year, had <5 subjects, or were not original articles were excluded.

RESULTS

The initial search yielded 748 studies, and 5 studies met the inclusion criteria. All these 5 studies focused on hip arthroscopic treatment for patients with concomitant mild acetabular dysplasia and FAI. Three studies had level III evidence, whereas 2 studies had level IV evidence. The mean patient age range across the studies was 29.8 to 49.6 years, and the female-to-male ratio was 1.14. Improved patient-reported outcomes (Hip Outcome Score-Activities of Daily Living, Hip Outcome Score-Sport, modified Harris Hip Score, Short Form-12 Physical Component Summary, Western Ontario and McMaster Universities Osteoarthritis Index) at a minimum 2-year follow-up were obtained in 4 of the 5 studies. Two of these 4 studies had a comparative cohort of patients with FAI with normal acetabular coverage, and there was no significant difference in the postoperative outcomes and secondary procedure rate between patients with mild acetabular dysplasia and those with normal acetabular coverage.

CONCLUSIONS

This systematic review indicates that improved patient-reported outcomes can be obtained with hip arthroscopy in the treatment of concomitant mild acetabular dysplasia and FAI at a minimum 2-year follow-up.

LEVEL OF EVIDENCE

Level IV, systematic review of Level III and Level IV studies.

Posterior Pelvic Tilt From Supine to Standing in Patients With Symptomatic Developmental Dysplasia of the Hip

Pelvic sagittal inclination (PSI) significantly affects the femoral head coverage by the acetabulum in patients with developmental dysplasia of the hip (DDH), while no reports have quantified PSI in DDH patients in the supine and standing positions. Furthermore, little is known about how PSI changes after periacetabular osteotomies. Herein, PSI in the supine and standing positions was quantified in DDH patients preoperatively and postoperatively. Twenty-five patients with DDH who had undergone periacetabular osteotomies were analyzed. The preoperative PSI and the PSI 2 years after surgery were measured in the supine and standing positions using the image registration technique between radiographs and computed tomographic images. The percentage of patients who showed PSI changes of more than 10° from the supine to the standing position was quantified. PSI changed 8.2 ± 5.0° posteriorly from the supine to the standing position during the preoperative period. Posterior pelvic tilt of more than 10° was found in nine cases (36%). Two years after periacetabular osteotomies, the postural PSI change was 7.1 ± 3.9° posteriorly. When the preoperative and postoperative PSI values were compared, PSI in the standing position did not differ (p = 0.20). Similarly, the amount of PSI change from the supine to standing position was not significantly different (p = 0.26). In conclusion, posterior pelvic tilt in the standing position was found preoperatively in symptomatic DDH patients, and it remained for 2 years after periacetabular osteotomies. This postural change in PSI does not seem to influence the outcome of periacetabular osteotomy. However, during preoperative planning, surgeons should recognize that acetabular anteversion or anterior acetabular coverage differs between the supine and standing positions in some patients with DDH. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:578-587, 2020.

Spinopelvic Characteristics in Acetabular Retroversion: Does Pelvic Tilt Change After Periacetabular Osteotomy?

BACKGROUND

Acetabular retroversion may lead to impingement and pain, which can be treated with an anteverting periacetabular osteotomy (aPAO). Pelvic tilt influences acetabular orientation; as pelvic tilt angle reduces, acetabular version reduces. Thus, acetabular retroversion may be a deformity secondary to abnormal pelvic tilt (functional retroversion) or an anatomic deformity of the acetabulum and the innominate bone (pelvic ring).

PURPOSE

To (1) measure the spinopelvic morphology in patients with acetabular retroversion and (2) assess whether pelvic tilt changes after successful anteverting PAO (aPAO), thus testing whether preoperative pelvic tilt was compensatory.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A consecutive cohort of 48 hips (42 patients; 30 ± 7 years [mean ± SD]) with acetabular retroversion that underwent successful aPAO was studied. Spinopelvic morphology (pelvic tilt, pelvic incidence, anterior pelvic plane, and sacral slope) was measured from computed tomography scans including the sacral end plate in 21 patients, with adequate images. In addition, the change in pelvic tilt with aPAO was measured via the sacrofemoral-pubic angle with supine pelvic radiographs at an interval of 2.5 ± 2 years.

RESULTS

The spinopelvic characteristics included a pelvic tilt of 4° ± 4°, a sacral slope of 39° ± 9°, an anterior pelvic plane angle of 11° ± 5°, and a pelvic incidence of 42° ± 10°. Preoperative pelvic tilt was 4° ± 4° and did not change postoperatively (4° ± 4°) (P = .676).

CONCLUSION

Pelvic tilt in acetabular retroversion was within normal parameters, illustrating "normal" sagittal pelvic balance and values similar to those reported in the literature in healthy subjects. In addition, it did not change after aPAO. Thus, acetabular retroversion was not secondary to a maladaptive pelvic tilt (functional retroversion). Further work is required to assess whether retroversion is a reflection of a pelvic morphological abnormality rather than an isolated acetabular abnormality. Treatment of acetabular retroversion should focus on correcting the deformity rather than attempting to change the functional pelvic position.

The "Outside-In" Lesion of Hip Impingement and the "Inside-Out" Lesion of Hip Dysplasia: Two Distinct Patterns of Acetabular Chondral Injury

BACKGROUND

Femoroacetabular impingement (FAI) and acetabular dysplasia lead to acetabular cartilage damage that commonly results in the chondral flaps seen during hip arthroscopy.

PURPOSE

To compare the acetabular chondral flap morphology seen during hip arthroscopy ("outside-in" vs "inside-out") with clinical and radiographic parameters underlying FAI and hip dysplasia.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients who underwent hip arthroscopy by the senior author between 2013 and 2017 with a finding of Outerbridge grade IV acetabular chondral flap were included. Each procedure was retrospectively reviewed on video and chondral flaps were categorized as inside-out or outside-in. An inside-out designation was made for flaps exhibiting an intact chondrolabral junction with a detached sleeve of chondrolabral tissue from the central acetabulum, and an outside-in designation was made for centrally anchored flaps exhibiting a break in the chondrolabral junction. Radiographic markers of hip impingement/dysplasia were noted for each patient during assignment into 1 of 2 radiographic groups: group 1, lateral center edge angle (LCEA) >20 with FAI, and group 2, LCEA ≤20 with or without cam FAI. Associations between chondral flap morphology and clinical diagnosis were tested using a chi-square test.

RESULTS

Overall, 95 patients (103 hips) were included (group 1, 78 hips; group 2, 25 hips). Among hips in group 2, 24 had concurrent cam FAI. There was a significant relationship between chondral flap type and radiographic diagnosis (P < .001). Among group 1 hips, 78% exhibited outside-in type chondral flaps, 12% exhibited combined outside-in and inside-out flaps, and 10% exhibited inside-out flaps. Group 2 hips showed 72% inside-out type chondral flaps, 16% combined, and 12% outside-in. Hips exhibiting outside-in type flaps were significantly more likely to be in group 1 (positive predictive value [PPV], 91%; negative predictive value [NPV], 69%). Similarly, hips exhibiting inside-out type flaps were significantly more likely to be in group 2 (PPV, 56%; NPV, 95%). Altogether, 90% of group 1 hips exhibited an outside-in lesion and 88% of group 2 hips exhibited an inside-out lesion.

CONCLUSION

Acetabular chondral flap type visualized during hip arthroscopy correlates with radiographic markers of hip impingement and hip instability. Outside-in flaps are highly predictive of FAI, whereas inside-out flaps are highly predictive of acetabular dysplasia.

Age and sex-related distribution of alpha angles and the prevalence of the cam morphology of the hip in Asians do not differ from those of other ethnicities

PURPOSE

This study was performed to evaluate the effects of age on the alpha angle and the incidence of asymptomatic cam morphology.

METHODS

The radiographs of asymptomatic individuals between ages 8 and 22 were retrospectively collected. A total of 1417 individuals were included and grouped according to age: 8-12 (Group A), 13-18 (Group B), and 19-22 (Group C) years. Radiographic measurements of the alpha angles of the right hip were obtained from anteroposterior (AP) and frog-leg lateral (FL) radiographs. The correlations among alpha angles, the presence of cam morphology, and age were determined.

RESULTS

The mean alpha angles of the three groups were statistically different (p < 0.001, each). The alpha angles on both radiographs were positively correlated with age. Intra-group analysis revealed that this correlation was only evident on the FL images of males in Group B. The presence of a radiographic cam morphology also positively correlated with age (p < 0.001 in both AP and FL images). The cam morphology on AP radiographs was 0 in Group A, 17(3.0%) in Group B, and 21(4.8%) in Group C; that on FL radiographs was 2(0.3%) in Group A, 45(7.9%) in Group B, and 103(23.6%) in Group C. Intra-group analysis revealed that the correlation was only significant in males in Group B.

CONCLUSIONS

Higher alpha angles and the presence of cam morphology were positively correlated with age, particularly in males at or before the time of skeletal maturation. The prevalence of cam morphology did not differ from those in other ethnicities.

LEVEL OF EVIDENCE

IV.

Hip Arthroscopic Surgery in Borderline Developmental Dysplastic Hips: A Systematic Review

BACKGROUND

It remains controversial whether hip arthroscopic surgery should be applied to patients with a borderline developmental dysplastic hip (BDDH).

PURPOSE

To review the outcomes of hip arthroscopic surgery for a BDDH and which factors influence these outcomes.

STUDY DESIGN

Systematic review.

METHODS

PubMed, Embase, and the Cochrane Library were searched through March 2018 for studies reporting the outcomes of primary hip arthroscopic surgery in patients with a BDDH. Inclusion in the review was based on the definition of a BDDH, patient-reported outcomes, and duration of follow-up. The primary outcome was the modified Harris Hip Score (mHHS). The failure rate, visual analog scale, satisfaction score, and patient-reported outcomes such as the Hip disability and Osteoarthritis Outcome Score were defined as secondary outcomes.

RESULTS

Nine studies with 425 patients who underwent hip arthroscopic surgery were included in this review. The mean follow-up times ranged from 25.4 to 28.8 months across the studies. A significant improvement was obtained in the mHHS, with a mean score of 61.8 preoperatively to 82.8 postoperatively; all other patient-reported outcomes also improved significantly, except the 12-Item Short Form Health Survey mental component summary. The overall failure rate was 14.1%, and the mean reoperation rate was 8.5%. The rate of conversion to total hip arthroplasty ranged from 4.4% to 26.0%, and the rate of conversion to periacetabular osteotomy was 4.0%. Combined defects such as cartilage damage, hip osteoarthritis, ligamentum teres tears, and femoroacetabular impingement could influence the outcomes after arthroscopic surgery in BDDHs.

CONCLUSION

Hip arthroscopic surgery was demonstrated to be a promising approach for BDDHs, but the outcomes could be influenced by multiple risk factors. A higher level of evidence is still needed to support current findings.

Acetabular Retroversion Is a Risk Factor for Less Optimal Outcome After Femoroacetabular Impingement Surgery

BACKGROUND

Patients with acetabular retroversion are at risk of labral tear and hip pain. It is unknown whether femoroacetabular osteoplasty (FAO) without reverse periacetabular osteotomy can be used in these patients. This study evaluated the outcome of mini-open FAO in patients with acetabular retroversion and compared that to patients without acetabular retroversion.

METHODS

Fifty-one patients (29 male, 22 female) with acetabular retroversion who had undergone FAO between 2007 and 2015 were identified. The minimum 2-year clinical and radiological outcome was compared with 550 patients without dysplasia or retroversion who underwent FAO by the same surgeon. The preoperative and postoperative alpha angle, center-edge angle, Tonnis grade, joint space, and presence of labral tear and chondral lesion were determined.

RESULTS

The mean age in the retroversion cohort was 27.4 ± 9.5 years compared to 34.5 ± 11.2 years in the control. The mean follow-up was 4.8 ± 1.5 years for retroversion and 4.1 ± 1.2 years for the control. The mean preoperative Short-Form 36 Health Survey and modified Harris hip score were not different between the cohorts. At the latest follow-up, the mean modified Harris hip score and Short-Form 36 Health Survey were significantly lower in the retroversion group (75.4 and 76.5) compared to the control (83.4 and 85.6). There was a higher percentage of failure among retroversion patients (13.7%) compared to the control (2.5%).

CONCLUSION

Acetabular retroversion resulting in femoroacetabular impingent may be treated by FAO, but the outcome appears to be less optimal compared to patients with femoroacetabular impingent and no evidence of dysplasia and acetabular retroversion. Hip preservation surgeons should be aware of this anatomic variation and possible inferior treatment results after FAO in these patients.

Hip Dysplasia Compromises the Outcome of Femoroacetabular Impingement Surgery

BACKGROUND

The optimal treatment for patients with symptomatic hip dysplasia presenting with labral tear is unknown. Although femoroacetabular osteoplasty (FAO) has excellent outcome for most femoroacetabular impingement patients, the presence of concomitant hip dysplasia has been implicated as an adverse prognostic factor. This study evaluated the outcome of FAO in a group of dysplastic hips and compared the outcome to a cohort of patients without dysplasia.

METHODS

Seventy-three patients (38 males, 35 females) with hip dysplasia who underwent FAO between 2007 and 2015 were identified. The minimum 2-year clinical, functional (modified Harris Hip Score and Short-Form 36 Health Survey), and radiological outcome was compared with 550 patients without dysplasia who underwent FAO by the same surgeon. The preoperative and postoperative alpha angle, Tonnis grade, joint space, and presence of chondral lesion were determined and compared. Conversion to total hip arthroplasty or revision FAO was considered as treatment failure.

RESULTS

The mean age in the dysplasia cohort was 30.7 ± 11.8 years compared to 34.5 ± 11.2 in the nondysplastic group. The mean follow-up was 4.3 years for dysplasia cohort and 4.1 for the nondysplastic group. The mean modified Harris Hip Score and Short-Form 36 Health Survey6 was significantly lower in the dysplastic group at 75.1 and 74.3 compared to 83.4 and 85.6 for the comparison group. There was a higher percentage of failure at 28.8% among dysplasia patients compared to 2.5% in the nondysplastic group.

CONCLUSION

Although labral repair and FAO may be an option for patients with hip dysplasia, the outcome in this population appears to be less optimal compared to femoroacetabular impingement patients with no evidence of dysplasia. Labral repair and osteoplasty should be limited to those with mild and borderline dysplasia.

Normative data on femoral version

Femoral version is reported to vary in relation to age, gender and other patient-specific factors. Differences in femoral version are suspected to contribute to the development of hip pathology. However, normative data on pathologic hips has never been reported. To evaluate the femoral version in a large population of patients with symptomatic hip pathology treated with arthroscopy and report differences within this group based on age, gender, bony morphology and other hip-related factors. A prospectively gathered database of 1449 hips was reviewed. All patients underwent pre-operative MRI with measure of femoral version. The average femoral version of the entire population was 8.4+ 9.2°, range −23 to 63. There no statistically significant differences encountered based on age, gender, bony morphology or other hip-related factors. Across all groups, there was wide variation in the femoral version present. Among younger patients, there was trend to have a greater proportion of retroversion. Significant variation in femoral version exists in patients with symptomatic hip pathology. Although the geometry of the proximal femur is commonly described as anteverted, relative retroversion is also frequently encountered.

Does acetabular coverage influence the clinical outcome of arthroscopically treated cam-type femoroacetabular impingement (FAI)?

Aims

What represents clinically significant acetabular undercoverage in patients with symptomatic cam-type femoroacetabular impingement (FAI) remains controversial. The aim of this study was to examine the influence of the degree of acetabular coverage on the functional outcome of patients treated arthroscopically for cam-type FAI.

Patients and Methods

Between October 2005 and June 2016, 88 patients (97 hips) underwent arthroscopic cam resection and concomitant labral debridement and/or refixation. There were 57 male and 31 female patients with a mean age of 31.0 years (17.0 to 48.5) and a mean body mass index (BMI) of 25.4 kg/m² (18.9 to 34.9). We used the Hip2Norm, an object-oriented-platform program, to perform 3D analysis of hip joint morphology using 2D anteroposterior pelvic radiographs. The lateral centre-edge angle, anterior coverage, posterior coverage, total femoral coverage, and alpha angle were measured for each hip. The presence or absence of crossover sign, posterior wall sign, and the value of acetabular retroversion index were identified automatically by Hip2Norm. Patient-reported outcome scores were collected preoperatively and at final follow-up with the Hip Disability and Osteoarthritis Outcome Score (HOOS).

Results

At a mean follow-up of 2.7 years (1 to 8, sd 1.6), all functional outcome scores significantly improved overall. Radiographically, only preoperative anterior coverage had a negative correlation with the improvement of the HOOS symptom subscale (r = -0.28, p = 0.005). No significant difference in relative change in HOOS subscale scores was found according to the presence or absence of radiographic signs of retroversion.

Discussion

Our study demonstrated the anterior coverage as an important modifier influencing the functional outcome of arthroscopically treated cam-type FAI. Cite this article: Bone Joint J 2018;100-B:831-8.

Prevalence and morphological features of acetabular dysplasia with coexisting femoroacetabular impingement-related findings in a Japanese population: a computed tomography-based cross-sectional study

The coexistence of acetabular dysplasia (AD) and femoroacetabular impingement (FAI) has not been well discussed. This study was performed to elucidate the prevalence and morphological features of AD with coexisting FAI-related findings in a Japanese population. Computed tomography images were retrospectively evaluated. AD was classified as definite or borderline. The morphological findings that defined cam deformity were an α angle of ≥55°, head–neck offset ratio (HNOR) of <0.13, pistol grip deformity positivity and herniation pit positivity. The morphological findings that defined pincer deformity were acetabular index of ≤0° and a retroverted acetabulum. In total, 128 hips (male, 64; female, 64) were analyzed. The prevalence of coexistence of AD and FAI-related findings was detected in 23.4% of hips (definite AD and FAI, 7.8%; borderline AD and FAI, 15.6%). The percentages of hips with AD containing cam or pincer deformities among all were 54.3% and 4.3%, respectively. The percentage of AD with coexisting cam and that of AD with coexisting combined deformities was significantly higher in men, respectively. On the other hand, the most major morphological feature of FAI detected in hips with AD was a HNOR of <0.13. The coexistence of AD and FAI-related findings was common in a Japanese population, and 65.2% of hips with AD had some FAI-related findings. In discussing and managing AD, we recommend paying attention to the coexistence with FAI-related findings, especially in men and in borderline AD. In such hips, the most notable parameter as a morphological feature of FAI is a reduced HNOR.

Hip Dysplasia: Prevalence, Associated Findings, and Procedures From Large Multicenter Arthroscopy Study Group

PURPOSE

To report observational findings of patients with acetabular dysplasia undergoing hip arthroscopy.

METHODS

We performed a comparative case series of multicenter registry patients from January 2014 to April 2016 meeting the inclusion criteria of isolated hip arthroscopy, a documented lateral center-edge angle (LCEA), and completion of preoperative patient-reported outcome measures. A retrospective analysis compared range of motion, intra-articular pathology, and procedures of patients with dysplasia (LCEA ≤25°) and patients without dysplasia (LCEA >25°).

RESULTS

Of 1,053 patients meeting the inclusion criteria, 133 (13%) had dysplasia with a mean LCEA of 22.8° (standard deviation, 2.4°) versus 34.6° (standard deviation, 6.3°) for non-dysplasia patients. There were no statistically significant differences in preoperative modified Harris Hip Score, International Hip Outcome Tool-12 score, or visual analog scale score (pain). Cam deformity occurred in 80% of dysplasia patients. There was a significant difference in internal rotation between the dysplasia (21°) and non-dysplasia groups (16°, P < .001). Mean internal rotation (33.5°; standard deviation, 15.6°) of the dysplastic subjects without cam morphology was greater than that of the dysplastic patients with cam morphology (18.5°; standard deviation, 11.6°; P < .001). Hypertrophic labra were found more commonly in dysplastic (33%) than non-dysplastic hips (11%, P < .001). Labral tears in patients with dysplasia were treated by repair (76%), reconstruction (13%), and selective debridement (11%); labral treatments were not significantly different between cohorts. The most common nonlabral procedures included femoroplasty (76%) and synovectomy (73%). There was no significant difference between the dysplasia and non-dysplasia groups regarding capsulotomy types and capsular closure rates (96% and 92%, respectively).

CONCLUSIONS

Dysplasia, typically of borderline to mild severity, comprises a significant incidence of surgical cases (13%) by surgeons performing high-volume hip arthroscopy. Despite having similar preoperative pain and functional profiles to patients without dysplasia, dysplasia patients may have increased flexed-hip internal rotation. Commonly associated cam morphology significantly decreases internal rotation. Arthroscopic labral repair, femoroplasty, and closure of interportal capsulotomy are the most commonly performed procedures.

LEVEL OF EVIDENCE

Level III, therapeutic comparative case series.

Comparison of improved range of motion between cam-type femoroacetabular impingement and borderline developmental dysplasia of the hip -evaluation by virtual osteochondroplasty using computer simulation

Background

While cam resection is essential to achieve a good clinical result with respect to femoroacetabular impingement (FAI), it is unclear whether it should also be performed in cases of borderline developmental dysplasia of the hip (DDH) with a cam deformity. The aim of this study was to evaluate improvements in range of motion (ROM) in cases of cam-type FAI and borderline DDH after virtual osteochondroplasty using a computer impingement simulation.

Methods

Thirty-eight symptomatic hips in 31 patients (11male and 20 female) diagnosed with cam-type FAI or borderline DDH were analyzed. There were divided into a cam-type FAI group (cam-FAI group: 15 hips), borderline DDH without cam group (DDH W/O cam group: 12 hips), and borderline DDH with cam group (DDH W/ cam group: 11 hips). The bony impingement point on the femoral head-neck junction at 90° flexion and maximum internal rotation of the hip joint was identified using ZedHip® software. Virtual osteochondroplasty of the impingement point was then performed in all cases. The maximum flexion angle and maximum internal rotation angle at 90° flexion were measured before and after virtual osteochondroplasty at two resection ranges (i.e., slight and sufficient).

Results

The mean improvement in the internal rotation angle in the DDH W/ cam group after slight resection was significantly greater than that in the DDH W/O cam group (P = 0.046). Furthermore, the mean improvement in the internal rotation angle in the DDH W/ cam and cam-FAI groups after sufficient resection was significantly greater than that in the DDH W/O cam group (DDH W/ cam vs DDH W/O cam: P = 0.002, cam-FAI vs DDH W/O cam: P = 0.043).

Conclusion

Virtual osteochondroplasty resulted in a significant improvement in internal rotation angle in DDH W/ cam group but not in DDH W/O cam group. Thus, borderline DDH cases with cam deformity may be better to consider performing osteochondroplasty.

Do Patients With Borderline Dysplasia Have Inferior Outcomes After Hip Arthroscopic Surgery for Femoroacetabular Impingement Compared With Patients With Normal Acetabular Coverage?

BACKGROUND

The literature contains conflicting reports regarding whether outcomes of hip arthroscopic surgery for patients with borderline dysplasia are inferior to outcomes in patients with normal acetabular coverage.

PURPOSE

To assess differences in the outcomes of hip arthroscopic surgery for femoroacetabular impingement (FAI) in groups of patients with borderline dysplasia and normal coverage.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A registry of consecutive patients who had undergone primary hip arthroscopic surgery with capsular plication for FAI between January 2012 and January 2014 were divided based on the preoperative lateral center-edge angle (LCEA) into 2 distinct groups: (1) borderline dysplasia (LCEA 18°-25°) and (2) normal acetabular coverage (LCEA 25.1°-40°). There were 36 patients in the borderline dysplastic group and 312 patients in the normal coverage group. The primary outcome measure was the Hip Outcome Score-Activities of Daily Living (HOS-ADL) at a minimum of 2 years postoperatively. Secondary outcome measures included the HOS-Sports and modified Harris Hip Score (mHHS).

RESULTS

The mean preoperative LCEA differed significantly between groups (23.4° ± 1.5° for borderline dysplastic, 32.5° ± 3.8° for normal coverage; P < .001). The borderline dysplastic group had a higher percentage of female patients than the normal coverage group (27/36 [75%] vs 177/312 [57%], respectively; P = .048). There were no differences in other preoperative demographics and radiographic parameters. At a minimum 2 years after hip arthroscopic surgery (mean follow-up, 2.6 ± 0.6 years), both groups demonstrated significant improvements in all patient-reported outcome scores ( P < .001 in all cases). There were no significant differences between the borderline dysplastic and normal coverage groups in final outcome scores, score improvements, or percentage of patients experiencing clinically significant improvements. One patient in the borderline dysplastic group (3%) underwent revision hip arthroscopic surgery, and none underwent total hip arthroplasty during the follow-up period. There were no differences between the borderline dysplastic and normal coverage groups with regard to subsequent surgery. Female patients in the borderline dysplastic group had greater improvements in the mean HOS-ADL (25.9 ± 16.3 vs 10.8 ± 18.5, respectively; P = .05) and mHHS (27.9 ± 12.9 vs 8.1 ± 19.0, respectively; P = .005) compared with male patients in the borderline dysplastic group, but male and female patients did not differ in outcomes for the normal coverage group.

CONCLUSION

Patients who underwent hip arthroscopic surgery for FAI with capsular plication experienced significant clinical improvements with low rates of subsequent surgery, regardless of whether their acetabulum had borderline dysplasia or normal coverage.

What Are the Results of Surgical Treatment of Hip Dysplasia With Concomitant Cam Deformity?

BACKGROUND

Periacetabular osteotomy (PAO) is a reliable procedure to correct the deficient acetabular coverage in hips with developmental dysplasia. It is unclear how the presence of additional femoral cam-type deformity might influence the clinical and radiographic treatment results of PAO.

QUESTIONS/PURPOSES

(1) Are there differences in clinical scores (WOMAC, EQ-5D) and examination findings (impingement sign) or radiographic measures of acetabular orientation and head sphericity after PAO for isolated acetabular dysplasia when compared with the combined pathology of dysplasia and additional femoral cam deformity? (2) Are these clinical and radiographic findings after combined surgical therapy for additional cam deformity influenced by different pathology-adjusted surgical techniques?

METHODS

From July 2005 to December 2010, 86 patients (106 hips) underwent PAO for hip dysplasia. Surgical and outcome data were prospectively collected and retrospectively reviewed in a comparative observational study. Indications for surgery were a lateral center-edge angle less than 25° and hip pain for at least 6 months. The contraindications for surgery were advanced radiographic osteoarthritis (Kellgren-Lawrence Grade 3), incongruency of joint space, and patient age > 50 years. Depending on preoperative hip ROM, impingement test, and presence of a radiographically visible cam deformity, treatment allocation was performed: Group I: isolated PAO in patients without symptomatic asphericity, Group IIa: PAO with subsequent osteochondroplasty through arthrotomy for patients with symptomatic cam deformity and no labrochondral pathology, and Group IIb: arthroscopically assisted osteochondroplasty and additional labrochondral repair with subsequent PAO when patients had labrochondral lesions in addition to a symptomatic cam deformity. Clinical outcome (impingement test, EQ-5D, WOMAC) as well as radiographic parameters (lateral center-edge angle, crossover sign, alpha angle, osteoarthritis grade) were obtained after a mean followup of 63 ± 18 months (range, 31-102 months) and compared with the baseline data. Eleven patients (13%) were lost to followup. With the numbers available, our study had 80% power to detect a difference between Groups I and II of 10 points on the WOMAC scores.

RESULTS

There was no difference in the increase of WOMAC scores in patients with PAO alone (Group I; preoperative score 74 ± 17 versus postoperative 91 ± 15, p = 0.033) when compared with PAO and concurrent osteochondroplasty (Groups II A and B preoperative 73 ± 19 versus postoperative 90 ± 13 p < 0.001). The mean postoperative alpha angles in Group II (38° ± 6°) improved when compared with preoperative values (56° ± 15°; p < 0.001) and were even lower than native offset alpha angles in Group I (47° ± 11°). Clinical scores as well as postoperative radiographic parameters were not different between patients with conventional osteochondroplasty alone (Group IIA) and patients with arthroscopically assisted cam resection and intraarticular labrochondral repair (Group IIB).

CONCLUSIONS

With the numbers available, we detected no differences in outcome scores and radiographic results between patients who had been treated with PAO alone and patients who underwent combined PAO and offset correction for cam deformity. Although arthroscopically assisted treatment of advanced labrochondral lesions together with osteochondroplasty is possible during PAO and the results were not different in this small study when compared with patients with PAO and osteochondroplasty alone, the type and extent of damage that would indicate additional cartilage surgery over cam resection alone remain unclear.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Femoral Morphology in the Dysplastic Hip: Three-dimensional Characterizations With CT

BACKGROUND

Hip dysplasia represents a spectrum of complex deformities on both sides of the joint. Although many studies have described the acetabular side of the deformity, to our knowledge, little is known about the three-dimensional (3-D) head and neck offset differences of the femora of dysplastic hips. A thorough knowledge of proximal femoral anatomy is important to prevent potential impingement and improve results after acetabular reorientation.

QUESTIONS/PURPOSES

(1) Are there common proximal femoral characteristics in patients with symptomatic hip dysplasia undergoing periacetabular osteotomy (PAO)? (2) Where is the location of maximal femoral head and neck offset deformity in hip dysplasia? (3) Do certain subgroups of dysplastic hips more commonly have cam-type femoral morphology? (4) Is there a relationship between hip ROM as well as impingement testing and 3-D head and neck offset deformity?

METHODS

Using our hip preservation database, 153 hips (148 patients) underwent PAO from October 2013 to July 2015. We identified 103 hips in 100 patients with acetabular dysplasia (lateral center-edge angle [LCEA] < 20°) and who had a Tönnis grade of 0 or 1. Eighty-six patients (86%) underwent preoperative low-dose pelvic CT scans at our institution as part of the preoperative planning for PAO. It is currently our standard to obtain preoperative low-dose pelvic CT scans (0.75-1.25 mSv, equivalent to three to five AP pelvis radiographs) on all patients before they undergo PAO unless a prior CT scan is performed at an outside institution. Hips with a history of a neuromuscular disorder, prior trauma, prior surgery, radiographic evidence of joint degeneration, ischemic necrosis, or Perthes-like deformities were excluded. Fifty hips in 50 patients met inclusion criteria and had CT scans available for review. Hips were analyzed with Dyonics Plan software and characterized with regard to version, neck-shaft angle, femoral head diameter, head and neck offset, femoral neck length, femoral offset, head center height, trochanteric height, and alpha angle. The maximum head and neck offset deformity was assessed using an entire clockface and an alpha angle ≥ 55° defined coexisting cam morphology. Subgroups included severity of lateral dysplasia: mild (LCEA 15°-20°) and moderate/severe (LCEA < 15°). Femoral version subgroups were defined as normal (5°-20°), decreased (≤ 5°), or increased (> 20°). The senior author (JCC) performed all physical examination testing.

RESULTS

The mean LCEA was 14° (±4°), whereas the mean femoral anteversion was 19° (±12°). Eight hips (16%) demonstrated relative femoral retroversion (≤ 5°), whereas 26 (52%) showed excessive femoral anteversion (> 20°). Four hips (8%) had ≥ 35° of femoral anteversion. The mean neck-shaft angle was 136° (±5°). The mean maximum alpha location was 2:00 o'clock (±45 minutes) and the mean maximum alpha angle was 52° (±6°). Minimum head-neck offset ratio was located at 1:30 with a mean of 0.14 (±0.03). An anterior head-neck offset ratio of ≤ 0.17 or an alpha angle ≥ 55° was found in 43 (86%) of hips. Twenty-one dysplastic hips (42%) had an alpha angle ≥ 55°. Mildly dysplastic hips had decreased femoral head and neck offset (9 ± 1) and head and neck offset ratio (0.20 ± 0.03) at 12 o'clock compared with moderate/severe dysplastic hips (10 ± 1 and 0.22 ± 0.03, respectively; p = 0.04 and p = 0.01). With the numbers available, we found that hips with excessive femoral anteversion (> 20°) had no difference in the alpha angle at 3 o'clock (42 ± 7) compared with hips with relative femoral retroversion (≤ 5°; 48 ± 4; p = 0.06). No other differences in femoral morphology were found between hips with mild or moderate/severe dysplasia or in the femoral version subgroups with the numbers available. Anterior impingement test was positive in 76% of hips with an alpha angle ≥ 55° and 83% of the hips with an alpha angle ≤ 55°. No correlation was found between proximal femoral morphology and preoperative ROM.

CONCLUSIONS

In this subset of dysplastic hips, cam deformity of the femoral head and neck was present in 42% of hips with maximal head-neck deformity at 2 o'clock, and 82% had reduced head-neck offset at the 1:30 point. We conclude that cam-type deformities and decreased head-neck offset in developmental dysplasia of the hip are common. Patients should be closely assessed for need of a head and neck osteochondroplasty, especially after acetabular correction. Future prospective studies should evaluate the influence of proximal femoral anatomy on surgical results of PAO for dysplastic hips.

LEVEL OF EVIDENCE

Level IV, prognostic study.

The John Charnley Award: Redefining the Natural History of Osteoarthritis in Patients With Hip Dysplasia and Impingement

BACKGROUND

Structural hip deformities including developmental dysplasia of the hip (DDH) and femoroacetabular impingement (FAI) are thought to predispose patients to degenerative joint changes. However, the natural history of these malformations is not clearly delineated.

QUESTIONS/PURPOSES

(1) Among patients undergoing unilateral THA who have a contralateral hip without any radiographic evidence of hip disease, what is the natural history and progression of osteoarthritis in the native hip based on morphological characteristics? (2) Among patients undergoing unilateral THA who have a contralateral hip without any radiographic evidence of hip disease, what are the radiographic parameters that predict differential rates of degenerative change?

METHODS

We identified every patient 55 years of age or younger at our institution who received unilateral primary THA from 1980 to 1989 (n = 722 patients). Preoperative radiographs were reviewed on the contralateral hip and only hips with Tönnis Grade 0 degenerative change that had minimum 10-year radiographic followup were included. A total of 172 patients met all eligibility criteria with the following structural diagnoses: 48 DDH, 74 FAI, and 40 normal morphology, and an additional 6% (10 of the 172 patients) met all eligibility criteria but were lost to followup before the 10-year minimum. Mean age at the time of study inclusion was 47 years (range, 18-55 years), and 56% (91 of 162) of the patients in this study were female. Mean followup was 20 years (range, 10-35 years). Radiographic metrics, in conjunction with the review of two experienced arthroplasty surgeons, determined the structural hip diagnosis as DDH, FAI, or normal morphology. Every available followup AP radiograph was reviewed to determine progression from Tönnis Grade 0 to 3 until the time of last followup or operative intervention with THA. Survivorship was analyzed by Kaplan-Meier methodology, hazard ratios, and multistate modeling. Thirty-five patients eventually underwent THA: 16 (33%) DDH, 13 (18%) FAI, and six (15%) normal morphology.

RESULTS

Degenerative change was most rapid in patients with DDH followed by FAI and normal morphology. Among patients who recently developed Tönnis 1 degenerative change, the probability of undergoing THA in 10 years based on hip morphology was approximately one in three for DDH and one in five for both FAI and normal morphology hips, whereas the approximate probability at 20 years was two in three for DDH and one in two for both FAI and normal morphology hips. The likelihood of radiographic degeneration was increased in patients with the following findings: femoral head lateralization > 8 mm, femoral head extrusion index > 0.20, acetabular depth-to-width index < 0.30, lateral center-edge angle < 25°, and Tönnis angle > 8°.

CONCLUSIONS

Degenerative change occurred earliest in patients with DDH, whereas the natural history of patients with FAI was quite similar to structurally normal hips. However, patients with cam deformities and concomitant acetabular dysplasia developed osteoarthritis more rapidly. Although the results of this study cannot be directly correlated to highly active patients with FAI, these findings suggest that correction of FAI to a normal morphology may only minimally impact the natural history, especially if intervention takes place beyond Tönnis 0. Analysis of radiographic parameters showed that incremental changes toward dysplastic morphology increase the risk of degenerative change.

LEVEL OF EVIDENCE

Level III, prognostic study.

Editorial Commentary: No 2 Hips Are the Same-Femoroacetabular Impingement May Be More Proximal in Patients With Developmental Dysplasia

Every hip is unique. The area of cam impingement is more proximal in patients with borderline developmental dysplasia of the hip. It is important to recognize this to ensure successful treatment.

Pelvic posture and kinematics in femoroacetabular impingement: a systematic review

BACKGROUND

Pelvic posture and kinematics influence acetabular orientation and are therefore expected to be involved in the pathomechanics of femoroacetabular impingement (FAI). This systematic review aims to determine whether FAI patients show pelvic postures or patterns of motion contributing to impingement or, conversely, develop compensatory postures and patterns of motion preventing it.

MATERIALS AND METHODS

PubMed/MEDLINE, Embase, Google Scholar and the Cochrane Library were systematically searched to find all the studies that measured pelvic positional and/or kinematic data in humans (patients or cadaveric specimens) affected by FAI.

RESULTS

Twelve items were selected and grouped according to the main field of investigation. No quantitative data synthesis was allowed due to methodological heterogeneity. Pelvic posture and kinematics seem to play a relevant role in FAI. The patients, especially if symptomatic, show a paradoxical lack of pelvic back tilt in standing hip flexions, i.e., in squatting, that enhances femoroacetabular engagement. Such an aberrant pattern might depend on a lower pelvic incidence. On the contrary, active hip flexion in decubitus elicits a compensatory, more pronounced back tilt to facilitate hip flexion without impingement. Stair climbing shows a compensatory pattern of augmented pelvic axial rotation and augmented peak forward tilt to reduce painful hip motions, namely internal rotation and extension.

CONCLUSION

In FAI patients, pelvic posture and kinematics are sometimes an expression of compensatory mechanisms developed to reduce pain and discomfort, and sometimes an expression of paradoxical responses that further enhance the impingement pathomechanism.

LEVEL OF EVIDENCE

IV.

The Distribution of Impingement Region in Cam-Type Femoroacetabular Impingement and Borderline Dysplasia of the Hip With or Without Cam Deformity: A Computer Simulation Study

PURPOSE

To identify the distribution of the impingement region in cam-type femoroacetabular impingement (FAI) or patients with borderline developmental dysplasia of the hip (DDH) using computer simulation analysis.

METHODS

A total of 51 painful hip joints from 42 consecutive cases diagnosed as cam-type FAI (center edge [CE] angle ≥ 25°, alpha angle ≥ 55°) or borderline DDH (CE angle ≥ 20° and < 25°) with or without a cam deformity (alpha angle ≥ 55° or < 55°) were enrolled. ZedHip (Lexi, Tokyo, Japan) 3-dimensional computer simulation was used to identify impingement points. Computed tomography data were used for 3-dimensional modeling and impingement simulation. The maximum flexion angle and maximum internal rotation angle at 90° were evaluated. The impingement point was identified at a position of maximum internal rotation and 90° of flexion. Six impingement regions were defined. Differences in the distribution of the impingement region were evaluated between groups.

RESULTS

There were significant differences in range of motion at maximum flexion and internal rotation among the 3 groups (P < .0001). There was no significant difference in the distribution of the impingement point in the cam-type FAI group (P = .71); similarly, there was no significant difference in the borderline DDH with a cam deformity group (P = .071). On the other hand, in terms of proximal or distal sites, there was a significant difference between the borderline DDH with and without a cam deformity group (P < .001).

CONCLUSIONS

The impingement region in cases of cam-type FAI was variable. The coexistence of a cam deformity affected the distribution of the impingement region in cases of borderline DDH; the region tended to be distributed across proximal rather than distal regions. The site of cam osteochondroplasty should be based on the identified impingement point, particularly in cases of cam-type FAI and borderline DDH with a cam deformity.

LEVEL OF EVIDENCE

Level IV, case control study.

Femoral Morphology in Patients Undergoing Periacetabular Osteotomy for Classic or Borderline Acetabular Dysplasia: Are Cam Deformities Common?

BACKGROUND

The primary purpose of our study was to determine the prevalence of Cam deformity in patients with symptomatic acetabular dysplasia (SAD) who underwent periacetabular osteotomy (PAO).

METHODS

We retrospectively reviewed 164 SAD PAO patients from 2 institutions. Preoperative anteroposterior and frog-lateral radiographs were analyzed for lateral center edge angle (LCEA), retroversion, alpha angles, and anterior femoral head-neck offset. Hips were classified as dysplastic (LCEA <20°, group A, n = 142) and borderline dysplastic (LCEA 20°-25°, group B, n = 22). There were 128 females and 36 males with an average age of 29 years (range 13-56).

RESULTS

The overall prevalence of Cam deformity was 10% (17 of 164) in SAD patients. There was no difference in the prevalence of Cam deformity between the groups (P > .99).

CONCLUSION

Prevalence of Cam deformities in our series of SAD patients having undergone PAO is less than prior reports. Careful radiographic measurement should be performed to avoid overtreating these hips with unnecessary osteochondroplasty procedures.

High prevalence of cam deformity in dysplastic hips: A three-dimensional CT study

Cam deformity could lead to suboptimal articulation by causing secondary femoroacetabular impingement after periacetabular osteotomy; however, the inherent femoral head-neck morphology in dysplastic hips and the effect of an additional osteoarthritic deformity have not been well described. We compared femoral head-neck morphology using three-dimensional imaging of normal and dysplastic hips in pre/early (Tönnis grade 0 and 1) and advanced stage osteoarthritis (Tönnis grade 2). Using computed tomography, we measured the circumferential α-angle and head-neck offset ratio in 68 dysplastic hips and 24 normal hips. Locations of the head-neck junction were represented by the clock position. In the pre/early group, the α-angle was significantly larger at the anterosuperior and inferior aspects (1, 2, and 5-7 o'clock) and head-neck offset ratio was smaller at the anterosuperior aspect (2 o'clock) than in the control group. The α-angle was significantly larger at the anterior aspects (1-4 o'clock) in the advanced group than in the pre/early group. The maximum α-angle was most commonly found at 2 o'clock (60%, 41/68 hips) in dysplastic hips. The prevalence of cam deformity (maximum α-angle >55°) was 4.2% (1/24 hips) in the control group, 22% (11/50 hips) in the pre/early group, and 50% (9/18 hips) in the advanced group. Cam deformity, inherent in the pre/early group, was found with relatively high frequency. The higher prevalence in the advanced group reflected degeneration-modified changes. When performing periacetabular osteotomy, preoperative radiographic assessments should include the femoral head-neck junction to prevent secondary femoroacetabular impingement, especially in patients with advanced stage osteoarthritis. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1613-1619, 2016.

MRI of lower extremity impingement and friction syndromes in children

Although generally more common in adults, lower extremity impingement and friction syndromes are also observed in the pediatric age group. Encompassing femoroacetabular impingement, iliopsoas impingement, subspine impingement, and ischiofemoral impingement around the hip; patellar tendon-lateral femoral condyle friction syndrome; iliotibial band friction syndrome; and medial synovial plica syndrome in the knee as well as talocalcaneal impingement on the hindfoot, these syndromes frequently cause pain and may mimic other, and occasionally more ominous, conditions in children. Magnetic resonance imaging (MRI) plays a key role in the diagnosis of musculoskeletal impingement and friction syndromes. Iliopsoas, subspine, and ischiofemoral impingements have been recently described, while some features of femoroacetabular and talocalcaneal impingements have recently gained increased relevance in the pediatric population. Fellowship-trained pediatric radiologists and radiologists with imaging workloads of exclusively or overwhelmingly pediatric patients (particularly those without a structured musculoskeletal imaging program as part of their imaging training) specifically need to be aware of these rare syndromes that mostly have quite characteristic imaging findings. This review highlights MRI features of lower extremity impingement and friction syndromes in children and provides updated pertinent pathophysiologic and clinical data.

Prevalence of cam hip shape morphology: a systematic review

OBJECTIVE

Cam hip shape morphology is a recognised cause of femoroacetabular impingement (FAI) and is associated with hip osteoarthritis. Our aim was to systematically review the available epidemiological evidence assessing the prevalence of cam hip shape morphology in the general population and any studied subgroups including subjects with and without hip pain.

DESIGN

All studies that reported the prevalence of cam morphology, measured by alpha angles, in subjects aged 18 and over, irrespective of study population or presence of hip symptoms were considered for inclusion. We searched AMED, MEDLINE, EMBASE, CINAHL and CENTRAL in October 2015. Two authors independently identified eligible studies and assessed risk of bias. We planned to pool data of studies considered clinically homogenous.

RESULTS

Thirty studies met inclusion criteria. None of the included studies were truly population-based: three included non-representative subgroups of the general population, 19 included differing clinical populations, while eight included professional athletes. All studies were judged to be at high risk of bias. Due to substantial clinical heterogeneity meta analysis was not possible. Across all studies, the prevalence estimates of cam morphology ranged from 5 to 75% of participants affected. We were unable to demonstrate a higher prevalence in selected subgroups such as athletes or those with hip pain.

CONCLUSIONS

There is currently insufficient high quality data to determine the true prevalence of cam morphology in the general population or selected subgroups. Well-designed population-based epidemiological studies that use homogenous case definitions are required to determine the prevalence of cam morphology and its relationship to hip pain.

Outcomes After Arthroscopic Treatment of Femoroacetabular Impingement for Patients With Borderline Hip Dysplasia

BACKGROUND

The outcomes of hip arthroscopy in the treatment of dysplasia are variable. Historically, arthroscopic treatment of severe dysplasia (lateral center-edge angle [LCEA] <18°) resulted in poor outcomes and iatrogenic instability. However, in milder forms of dysplasia, favorable outcomes have been reported.

PURPOSE

To compare outcomes after hip arthroscopy for femoroacetabular impingement (FAI) in borderline dysplastic (BD) patients compared with a control group of nondysplastic patients.

STUDY DESIGN

Cohort study; Level of evidence, 3 METHODS: Between March 2009 and July 2012, a BD group (LCEA, 18°-25°) of 46 patients (55 hips) was identified. An age- and sex-matched control group of 131 patients (152 hips) was also identified (LCEA, 25°-40°). Patient-reported outcome scores, including the modified Harris Hip Score (mHHS), the Hip Outcome Score-Activities of Daily Living (HOS-ADL) and Sport-Specific Subscale (HOS-SSS), and the International Hip Outcome Tool (iHOT-33), were collected preoperatively and at 1 and 2 years postoperatively.

RESULTS

The mean LCEA was 22.4° ± 2.0° (range, 18.4°-24.9°) in the BD group and 31.0° ± 3.1° (range, 25.4°-38.7°) in the control group (P < .001). The mean preoperative alpha angle was 66.3° ± 9.9° in the BD group and 61.7° ± 13.0° in the control group (P = .151). Cam decompression was performed in 98.2% and 99.3% of cases in the BD and control groups, respectively; labral repair was performed in 69.1% and 75.3% of the BD and control groups, respectively, with 100% of patients having a complete capsular closure performed in both groups. At a mean follow-up of 31.3 ± 7.6 months (range, 23.1-67.3 months) in unrevised patients and 21.6 ± 13.3 months (range, 4.7-40.6 months) in revised patients, there was significant improvement (P < .001) in all patient-reported outcome scores in both groups. Multiple regression analysis did not identify any significant differences between groups. Importantly, female sex did not appear to be a predictor for inferior outcomes. Two patients (4.3%) in the BD group and 6 patients (4.6%) in the control group required revision arthroscopy during the study period.

CONCLUSION

Favorable outcomes can be expected after the treatment of impingement in patients with borderline dysplasia when labral refixation and capsular closure are performed, with comparable outcomes to nondysplastic patients. Further follow-up in larger cohorts is necessary to prove the durability and safety of hip arthroscopy in this challenging group and to further explore potential sex-related differences in outcome.

REHABILITATION AFTER HIP ARTHROSCOPY AND LABRAL REPAIR IN A HIGH SCHOOL FOOTBALL ATHLETE: A 3.6 YEAR FOLLOW-UP WITH INSIGHT INTO POTENTIAL RISK FACTORS

BACKGROUND

Hip arthroscopy is a common surgical technique for the correction of intraarticular pathology. While surgical success is often determined by anatomical correction, post-operative rehabilitation serves an essential role in restoring pre-morbid activity levels. A paucity of long-term post-operative rehabilitation outcomes exists in the literature lending uncertainty to the long-standing efficacy of interventions and associated risk for future injury.

CASE DESCRIPTION

This case report describes the progress of a male subject 3.6 years after left hip arthroscopy with labral repair. Detailed clinical measures and insight into potential risk factors are presented as a follow-up to a previously published case report.

OUTCOME

A 3.6-year follow-up assessment revealed potential risk factors that may have predisposed the subject to future pathology. The most profound finding was the subject's complaint of contralateral right hip pain and examination findings suggesting intraarticular pathology. His left surgical hip presented with no reported problems or significant findings. The examination also revealed an anterior tilted pelvis, muscle length deficits, and hip muscle weakness which may have contributed to his right hip pain or may be risk factors for future pathology in both hips. It appeared that these impairments affected his gait and performance on functional tests.

DISCUSSION

This case report describes the 3.6 year follow-up for a young adult male subject after unilateral left hip arthroscopy and acetabular labral repair. The re-examination findings and risk factors identified at the follow-up may provide insight into the need for long-term surveillance among post-surgical individuals. Detailed reporting of the long-term effects of a post-operative program after hip arthroscopy is non-existent in the literature and the current findings suggest the potential need for mitigating risk in the non-surgical hip. Future longitudinal studies are needed to develop a consensus on the best interventions for these patients.

LEVEL OF EVIDENCE

4-Case Report.

Surgical treatment for young adult hip dysplasia: joint-preserving options

Developmental dysplasia of the hip (DDH) is a spectrum of disorders that results in anatomic abnormalities leading to increased contact stress in the joint and, eventually, secondary osteoarthritis. However, many patients with DDH become symptomatic before the severe degenerative changes of the hip because of abnormal hip biomechanics, mild hip instability, impingement, or associated intra-articular pathology. Early diagnosis and appropriate treatment for DDH are of the utmost importance. With the modification of techniques like pelvic osteotomy and capsular arthroplasty, and the introduction of intracapsular procedures such as arthroscopy and femoral head-neck junction osteochondroplasty, many young patients with symptomatic hip dysplasia may benefit from joint preservation procedures. We review the current development of these concepts and the associated surgical techniques.