Are cam and pincer deformities as common as dysplasia in Japanese patients with hip pain?

Trends in hip preservation surgery in Japan from 2014 to 2019 with a focus on hip arthroscopic surgery

Secondary hip osteoarthritis due to hip dysplasia is common among Japanese populations. This study aimed to investigate the number of hip preservation surgeries performed in Japan and assess trends, by age and sex, from 2014 to 2019, focusing on hip arthroscopic surgery, based on the National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB). We downloaded the files 'Number of calculations by division, sex, and age group' under 'operation (code K)' from 2014 to 2019 from the NDB Open Data Japan database. Data on hip preservation surgeries were extracted, including the number for each surgical procedure and its incidence per year, calculated as the number of surgeries performed for each 10-year age group and by sex, regarding hip arthroscopic surgery. Overall, 14 891 hip preservation surgeries were performed in Japan over the study period, with pelvic osteotomy being the most common procedure. Although the incidence of hip preservation surgeries decreased from 2014 to 2019, there was a specific 1.54-fold higher incidence in hip arthroscopic procedures in 2019 compared to 2014. Hip arthroscopic labral repair was performed more frequently than synovectomy. The highest incidence of hip arthroscopic surgery was in the 40- to 49-years age group, with no difference in incidence between sexes (P = 0.951). In Japan, pelvic osteotomy was performed more often as a hip preservation surgery than hip arthroscopic surgery. Although hip arthroscopic surgery was developed in Japan, its use has not increased from 2017 to 2019.

[Hip dysplasia: What influence do age, arthrosis and concomitant diseases have on the treatment result?]

Pelvic osteotomies are an established treatment for symptomatic adult hip dysplasia with a promising long-term outcome. Results depend not only on the achieved acetabular reorientation but also on patient-factors like preoperative joint condition (degree of osteoarthritis and joint congruency) and age. Additionally, the diagnosis and appropriate therapy of impingement-associated hip deformities is essential in order to achieve good mid- and long-term outcomes. The influence of chondrolabral pathology on the outcome of pelvic osteotomies is not yet defined. Symptomatic patients with residual dysplasia after previous pelvic or acetabular osteotomies can benefit from an additional osteotomy, although results can be worse in comparison to prior unoperated joints. Obesity can make surgery more demanding and increases the complication profile of PAO, although it has no influence on the postoperative outcome. Regarding the overall prognosis after an osteotomy, the consideration of combined risk factors is superior to the concentration on individual factors alone.

Prevalence of femoro-acetabular impingement in non-arthritic patients with hip pain: a meta-analysis

PURPOSE

As the prevalence of femoro-acetabular impingement syndrome (FAIS) in symptomatic patients who lack evidence of hip osteoarthritis (OA) remains to be described, the purpose of this study was to calculate the prevalence of FAIS in this patient population.

METHODS

Libraries of PubMed, Embase, and Ovid were systematically reviewed for all studies between 2009 and 2019, investigating femoro-acetabular impingement and hip pain. Level I-IV studies delineating patients with hip pain who do not have OA (Tonnis or Outerbridge grades < three) were included. Demographics, outcomes, radiographic parameters, and criteria were entered into a meta-analysis to calculate the incidence of FAIS in non-arthritic symptomatic hips.

RESULTS

In total, 2264 patients (2758 hips) were included in the pooled analysis. Weighted mean age was 31 years. The incidence of FAIS in patients with no evidence of osteoarthritis but who complain of hip pain is 61% (47.3-74.4%). In total, 1483 hips were diagnosed with FAIS. Of the studies that described the rates of all three of the various subtypes of FAIS in their reports, 37% had a combined-type, 38% had a cam-type, and 25% had a pincer-type FAIS.

CONCLUSION

Femoroacetabular impingement should be suspected in 47 to 74% of patients with hip pain and without arthritis. Physicians must maintain a high index of suspicion for FAIS in young patients presenting with hip pain, as FAIS is a common and treatable condition that, if left alone, may lead to hip degeneration.

Population-based prevalence of femoroacetabular impingement in Japan

OBJECTIVES

The prevalence of femoroacetabular impingement (FAI) was evaluated using a Japanese population-based cohort of participants aged ≥50 years.

METHODS

Radiographs (n = 854) of bilateral hips of 427 participants (279 women, 148 men) were used for the analysis. The prevalence of cam type, pincer type, and mixed type FAI as well as osteoarthritis was evaluated. The association of FAI and osteoarthritis (OA), and pain were also evaluated.

RESULTS

The prevalence of cam type and pincer type FAI were 4.2% and 20.3%, respectively. Mixed type FAI was 0.7%. OA was found in 4.0% of patients, and 17 hips (2.0%) with any FAI also had OA. A significant relationship between cam type FAI and OA was found, whereas no significant relationship between pincer type FAI and OA was seen. Sixty (7.0%) of all the hips were reported to be painful, and 14 of those painful hips (1.6%) had FAI. No significant relationship between FAI and hip pain was found.

CONCLUSION

We reported the first population-based prevalence of FAI in Japan. Radiological FAI was common, and pincer type was more common than cam type. The anatomical abnormalities associated with FAI, although often asymptomatic, are risk factors for OA.

The relationship between radiographic findings and patient-reported outcomes in adult hip dysplasia patients: A hospital cross-sectional study

INTRODUCTION

This study aimed to clarify the relationship of individual radiographic parameters and features with the patient-reported outcome measurements (PROMs) of patients with developmental dysplasia of the hip (DDH) in a hospital-referred cross-sectional analysis.

METHODS

This cross-sectional study included 108 Japanese DDH patients (female, n = 88; male, n = 20; mean age, 43.4 years). We recorded the CE angle, angle of Sharp, ARO, ADR, AHI, crossover sign, pistol grip deformity, and femoral head-neck ratio, which were measured on the AP view, and the α-angle, which was measured on the Lauenstein view. We also recorded cyst formation and osteophytes on either view. We used the Japanese Orthopaedic Association hip disease evaluation questionnaire (JHEQ) to assess the PROMs. The PROMs of patients with and without cysts or osteophytes and those of patients with or without cam or pincer deformity were compared. The relationships between specific PROMs and radiographic features were evaluated with a linear regression analysis and independent associations between PROMs and radiographic features were assessed with a multiple regression analysis using various independent variables.

RESULTS

The JHEQ movement and mental values in patients with cyst formation were significantly lower in comparison to those in patients without cyst formation. The JHEQ subscale values did not differ according to the presence or absence of osteophytes, cam deformity or pincer deformity. The CE angle was found to be associated with the JHEQ movement score in the linear regression analysis. To identify radiographic features that were independently associated with each of the JHEQ subscale scores, we performed a multiple regression analysis with age, body mass index, sex and the number of affected hip joints (bilateral or unilateral) included as independent variables. The CE angle was found to be independently associated with JHEQ movement.

CONCLUSION

The CE angle was independently associated with the JHEQ movement value.

The Prevalence of Cam and Pincer Morphology and Its Association With Development of Hip Osteoarthritis

Synopsis Our understanding of femoroacetabular impingement syndrome is slowly improving. The number of studies on all aspects (etiology, prevalence, pathophysiology, natural history, treatment, and preventive measures) of femoroacetabular impingement syndrome has grown exponentially over the past few years. This commentary provides the latest updates on the prevalence of cam and pincer hip morphology and its relationship with development of hip osteoarthritis (OA). Cam and pincer morphology is highly prevalent in the general population and in this paper is presented for different subgroups based on age, sex, ethnicity, and athletic activity. Methodological issues in determining prevalence of abnormal hip morphology are also discussed. Cam morphology has been associated with development of hip OA, but the association between pincer morphology and hip OA is much less clear. Results from reviewed studies, as well as remaining gaps in literature on this topic, are critically discussed and put into perspective for the clinician. J Orthop Sports Phys Ther 2018;48(4):230-238. doi:10.2519/jospt.2018.7816.

Prevalence of asymptomatic femoroacetabular impingement in Turkey; cross sectional study

OBJECTIVES

Femoroacetabular impingement (FAI) is one of the causes of hip pain in young-adult patients. The purpose of our study is to determine the prevalence of radiological FAI findings in asymptomatic population in Turkey.

METHODS

Trauma patients aged 18-65 years who applied to the emergency service between September 2015 and September 2016 were retrospectively evaluated for this study. After a preliminary study and power analysis, 2152 hips of the 1076 previously asymptomatic patients were evaluated radiologically with pelvis antero-posterior and frog-leg radiographs. On radiographs of these patients; alpha angle, lateral central edge angle (LCEA), Tönnis angle (TA) and collodiaphyseal angle were measured. Alpha angle values higher than 55° were noted as cam type FAI. TA values lower than 0° or LCEA values higher than 39° were noted as pincer type FAI. LCEA values lower than 25° or TA values higher than 10° were noted as acetabular dysplasia.

RESULTS

Mean age of 1076 patients (602 female, 474 male) was 42.1 ± 15.6 years. The assessment showed that 15.9% of the patients had cam type, 10.6% had pincer type, 3.1% had combined type FAI and 9.3% had findings of acetabular dysplasia. The prevalence of asymptomatic FAI is significantly more in males (46%) in comparison to females (17%) in Turkey.

CONCLUSION

Even though FAI is considered to be a pathology associated with hip osteoarthritis; it is very common in asymptomatic population. In this respect, our study showed that prevalence of radiological FAI findings in asymptomatic adult population was 29.6% in Turkey.

The Etiology of Cam-type Femoroacetabular Impingement: A Cadaveric Study

BACKGROUND

There is a dearth of literature examining the causes of cam-type femoroacetabular impingement (FAI) and when such morphology appears. The purpose of the current study was to analyze how the ossific portion of the proximal femur develops over time with respect to standard cam-type FAI parameters.

METHODS

A collection of 193 femurs from cadavers aged 4 to 21 years were evaluated. The age, sex, ethnicity, and status of the proximal femoral physes (open or closed) of each were recorded. Each specimen was digitally photographed in standardized anteroposterior and modified axial positions. From these photographs, the anterior offset, anterior offset ratio (AOR), and α-angle were determined. A cam lesion was defined as an α-angle >55 degrees on the lateral view.

RESULTS

The mean age of the specimens was 17.5±4.2 years. The majority were male (69%) and African American (79%) with closed physes (78%). There were significant differences among discrete age groups with respect to α-angle (P=0.01), anterior offset (P<0.01), and AOR (P<0.01). In addition, younger femurs with open physes had a significantly higher mean α-angle (P<0.01), lower mean anterior offset (P<0.01), and higher mean AOR (P<0.01) compared with older ones with closed physes. Specimens defined as having a cam deformity had a statistically higher α-angle (P<0.01) and lower anterior offset (P<0.01), but there was no difference in AOR values compared with specimens without a cam lesion (P=0.1).

CONCLUSIONS

The apparent decline in α-angles as age increases indicates that the traditional α-angle in younger patients measures a different anatomic parameter (ossified femur excluding the cartilaginous portion) than in older patients (completely ossified femur). This suggests that the bony α-angle is inappropriate in the evaluation of cam lesions in the immature physis. The AOR, rather than the anterior offset, may be more accurate in the evaluation of the growing proximal femur.

CLINICAL RELEVANCE

This study provides novel insight into, and enhances the understanding of, the development of cam-type FAI.

CT-based morphological assessment of the hip joint in Japanese patients: association with radiographic predictors of femoroacetabular impingement

AIMS

Femoroacetabular impingement (FAI) has been highlighted and well documented primarily in Western countries and there are few large studies focused on FAI-related morphological assessment in Asian patients. We chose to investigate this subject.

PATIENTS AND METHODS

We assessed the morphology of the hip and the prevalence of radiographic FAI in Japanese patients by measuring predictors of FAI. We reviewed a total of 1178 hips in 695 men and 483 women with a mean age of 58.2 years (20 to 89) using CT images that had been obtained for reasons unrelated to symptoms from the hip. We measured the lateral centre edge angle, acetabular index, crossover sign, alpha angle and anterior femoral head-neck offset ratio.

RESULTS

A total of 441 hips (37.4%) had pincer-type deformity (41.7% men, 31.3% women) and 534 (45.3%) had cam-type deformity (54.4% men, 32.3% women). Moreover, 773 hips (65.6%) had at least one parameter that predisposes to FAI (74.0% men, 53.6% women) and 424 hips (36.0%) had two or more parameters (43.6% men, 25.0% women).

CONCLUSION

The prevalence of radiographic FAI was common in Japanese patients who are generally considered to have dysplastic hips. Cite this article: Bone Joint J 2016;98-B:1167-74.

Prevalence of pincer, cam, and combined deformities in Japanese hip joints evaluated with the Japanese Hip Society diagnostic guideline for femoroacetabular impingement: A CT-based study

BACKGROUND

Femoroacetabular impingement (FAI) is thought to be associated with hip osteoarthritis. We investigated the prevalences of radiologic deformities of the pincer, cam, and their combinations in Japanese hip joints using computed tomography (CT) according to the Japanese Hip Society diagnostic guideline for FAI.

METHODS

Multi-slice CT images were evaluated. Pincer deformities were defined as: type 1: center-edge angle (CE) ≥40°; type 2: CE ≥ 30° and acetabular roof obliquity ≤0°; type 3: CE ≥ 25° and retroverted acetabulum. Cam deformities were defined as: type 1: CE ≥ 25°, α-angle ≥55°, and head-neck offset ratio <0.14; type 2: CE ≥ 25°, α-angle ≥55°, and herniation pit positive; type 3: CE ≥ 25°, α-angle ≥55°, and pistol grip deformity positive.

RESULTS

We studied 128 hips. Pincer was detected in 35.9% (type 1, 12.5%; type 2, 18.0%; type 3, 13.3%). Cam was detected in 24.2% (type 1, 23.4%; type 2, 7.8%; type 3, 10.9%). Combined deformities were detected in 10.2%. Type 3 pincer/type 1 cam was the most frequent combined deformity compared with all combined deformities. All of the cam deformities, total combined deformities, and all radiological FAIs appeared significantly more often in men.

CONCLUSIONS

When we used this guideline to diagnose FAI in a Japanese population, radiological FAI was common, and pincer deformities were more common than cam deformities. The most frequent seen pincer, cam, and combined deformities was type 2 pincer, type 1 cam, and the combination of type 3 pincer/type 1 cam, respectively.

What is the Prevalence of Radiographic Hip Findings Associated With Femoroacetabular Impingement in Asymptomatic Asian Volunteers?

BACKGROUND

Morphologic features of the proximal femur reminiscent of those seen in patients with femoroacetabular impingement (FAI) have been reported among asymptomatic individuals in Western populations, but whether this is the case in Asian populations is unknown.

QUESTIONS/PURPOSES

The purpose of this study was to determine the prevalence of radiographic findings in the proximal femur that are consistent with FAI in asymptomatic Korean volunteers.

METHODS

Two hundred asymptomatic volunteers with no prior hip surgery or childhood hip problems underwent three-view plain radiographs (pelvis AP view, Sugioka view, and 45° Dunn view) of both hips. There were 146 hips from male volunteers and 254 hips from female volunteers in the study. The mean age of all participants was 34.7 years (range, 21-49 years). Cam-type morphologic features were defined as the presence of the following on one or more of the three views: pistol-grip morphologic features, an osseous bump at the femoral head-neck junction, flattening of the femoral head-neck offset, or alpha angle greater than 55°. Pincer-type morphologic features were determined by radiographic signs, including crossover sign, deficient posterior wall sign, or lateral center-edge angle greater than 40°.

RESULTS

The prevalence of cam-type morphologic features seen on at least one radiograph was 38% (male, 57%; female, 26%). The prevalence of cam-type features (at least one positive cam-type feature) was 2.0% (male, 6%; female, 0%) on the pelvic AP view, 24% (male, 36%; female, 17%) on the Sugioka view, and 30% (male, 47%; female, 20%) on the 45° Dunn view. The prevalence of pincer-type morphologic features (at least one positive pincer-type feature) was 23% (male, 27%; female, 21%) on the pelvic AP view.

CONCLUSION

The prevalence of FAI-related morphologic features in asymptomatic Asian populations was comparable to the prevalence in Western populations. Considering the high prevalence of radiographic hip findings reminiscent of FAI in asymptomatic Asian populations, it will be important to determine whether FAI-related morphologic features are a cause of hip pain when considering surgery in Asian patients.

Ethnic Differences in Bony Hip Morphology in a Cohort of 445 Professional Male Soccer Players

BACKGROUND

Participation in high-impact athletic activities has recently been associated with a higher prevalence of cam deformity. Bony hip morphology has also emerged as an important factor in the development of hip osteoarthritis. However, it is unknown whether bony morphology differs between ethnicities in athletes participating in high-impact sports.

PURPOSE

To investigate whether the prevalence of specific bony hip morphological abnormalities differed between professional male soccer players of diverse ethnic backgrounds.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Professional male soccer players from an entire league attending preparticipation screening were invited to participate in this study. Ethnicity was registered, and standardized radiographs of anteroposterior pelvic and Dunn views were obtained. Cam and pincer deformity, and acetabular dysplasia were quantified using the alpha angle, triangular index, and lateral center-edge angle (LCEA). Regression analyses with generalized estimating equations were used to determine prevalence differences in bony hip morphology.

RESULTS

A total of 445 male soccer players (890 hips; mean age ± SD, 25 ± 4.9 years) participated in the study, representing the following ethnic groups: Arabic (59%), black (24%), Persian (7%), white (6%), East Asian (2%), and other (2%). The prevalence of cam deformity (alpha angle >60°) ranged from 57.5% to 71.7% across 4 of the groups, but East Asians had a significantly lower prevalence (18.8%; P ≤ .032). A large cam deformity (alpha angle >78°) was more prevalent in white (33.3%) compared with black soccer players (17.8%; P = .041) and was absent in East Asian players. Pincer deformity (LCEA >40°) was uncommon (3%) in all ethnicities. The prevalence of acetabular dysplasia (LCEA <20°) ranged from 8.0% to 16.7%, apart from the white group, in which prevalence was only 1.9% (P = .03).

CONCLUSION

The prevalence of a cam deformity and acetabular dysplasia differed between ethnicities in this cohort of professional male soccer players. These findings suggest that there may be ethnic differences in both acetabular morphology and femoral bony response to athletic load.

Prevalence of radiological findings related to femoroacetabular impingement in professional baseball players in Japan

BACKGROUND

Femoroacetabular impingement (FAI) is a known patho-mechanism that causes hip pain and osteoarthritis (OA) and is considered uncommon in Japan, while secondary OA due to hip dysplasia is considered common. However, no studies have specifically targeted athletes in Japan and/or Asia. This study aimed to determine FAI prevalence using radiological findings among baseball players playing on a professional, Japanese team.

METHODS

We retrospectively assessed 63 plain anteroposterior (AP) hip radiographs (126 hips from 47 [74.6%] Asian players and 16 [25.3%] non-Asian players) obtained for medical evaluations. Radiographs were used to measure lateral center-edge (LCE) angle; acetabular roof obliquity (ARO); and the presence of crossover sign (COS), posterior wall sign (PWS), coxa profunda, pistol grip deformity, herniation pits, and labral ossification. Further, the prevalence of radiographic indicators related to FAI was compared between Asian and non-Asian players.

RESULTS

In the 126 hips examined, 10 hips (7.94%) were classified as having hip dysplasia (LCE angles < 20°). Of the remaining 116 hips, eight (6.9%) had LCE angles > 40°, and 24 hips (20.7%) had AROs of <0°, indicating acetabular over-coverage. In Asian players, COS was identified in 47 hips (54.0%), positive PWS in 38 hips (43.7%), positive coxa profunda in 8 hips (9.2%), and pistol grip deformity in 37 hips (42.5%). Further, herniation pits and positive labral ossification were identified in 25 (28.7%) and 11 (12.6%) hips, respectively. A comparative review of COS prevalence (Asians vs. non-Asians) revealed that COS was significantly higher in Asian players. No differences were observed in the mean LCE angle, mean ARO, or other radiographic indicators.

CONCLUSIONS

Radiological indicators related to FAI were identified in 76.6% (72/94 hips) of the Asian professional baseball players; this prevalence was considerably higher than that reported for general Asian populations. We consider that elite Asian athletes may frequently show morphological deformities related to FAI.

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.

Hip range-of-motion (ROM) is less than normal after rotational acetabular osteotomy for developmental dysplasia of the hip: A simulated ROM analysis

The optimal reorientation of the acetabulum for developmental dysplasia of the hip (DDH) is unknown in terms of hip range-of-motion (ROM). The simulated ROMs of 52 DDHs after rotational acetabular osteotomy (RAO) with several patterns of femoral head coverage and those of 73 normal hips were analyzed using computer models reconstructed from CT images. After RAO with a lateral center edge angle (LCEA) of 30° and an anterior center edge angle (ACEA) of 55° producing coverage similar to that of normal hips, the maximal flexion and maximal internal rotation at 110° flexion with 20° adduction were significantly smaller than those of the normal group. To achieve ROMs after RAO similar to those of the normal group, an LCEA of 30° with an ACEA of 45°, an LCEA of 25° with an ACEA of 45° to 50°, and an LCEA of 20° with an ACEA of 50° could be preferred angles to target, even though they provided smaller coverage than that of normal hips. After RAO producing femoral head coverage similar to that of normal hips, the maximal flexion and the maximal internal rotation at 110° flexion with 20° adduction were significantly smaller than those of the normal group.

Clinical and Radiographic Predictors for Worsened Clinical Outcomes After Hip Arthroscopic Labral Preservation and Capsular Closure in Developmental Dysplasia of the Hip

BACKGROUND

Patients with developmental dysplasia of the hip (DDH) have a greater risk of acetabular labral tearing and joint instability, which predispose them to developing osteoarthritis. The arthroscopic management of DDH, however, remains controversial.

HYPOTHESIS

Specific clinical characteristics and radiographic parameters correlate with and predict a worsened clinical outcome after hip arthroscopic surgery for DDH.

STUDY DESIGN

Case control study; Level of evidence, 3.

METHODS

Of patients with DDH who underwent an arthroscopic procedure between March 2009 and June 2011, there were 28 hips in 28 patients (6 male and 22 female) that met the inclusion criteria. The mean patient age was 28.4 years. Clinical and radiographic follow-up evaluations up to a minimum of 2 years after surgery were performed for all patients. Failure of the procedure was defined as conversion to subsequent surgery or having a Tönnis osteoarthritis grade of 2 and modified Harris Hip Score (mHHS) that remained <85, and success was defined as patients who did not need subsequent surgery and had an mHHS >85. Univariate analysis and Cox hazard proportional analysis were performed on the 2 subpopulations.

RESULTS

There were 9 patients in the failure group (including 3 hips with T nnis grade 2) and 19 patients in the success group. In 22 of 28 patients, the mean mHHS significantly improved from 61.6 ± 18.8 (range, 12.0-85.0) preoperatively to 94.3 ± 7.0 (range, 73.7-100.0) at final follow-up, and the mean Non-Arthritic Hip Score (NAHS) improved from 56.2 ± 13.9 (range, 35.0-81.3) preoperatively to 92.7 ± 9.5 (range, 65.0-100.0) at final follow-up (P < .001, Wilcoxon signed-rank test). Univariate analysis showed that a broken Shenton line was significantly more prevalent in the failure group compared with the success group (8/9 [89%] vs 3/19 [16%] patients, respectively; P < .001). High-grade cartilage delamination (Multicenter Arthroscopy of the Hip Outcomes Research Network [MAHORN] grades 3-5) was significantly higher in the failure group than in the success group (8/9 [89%] vs 3/19 [16%] patients, respectively; P < .001). The median femoral neck-shaft (FNS) angle in the failure group was significantly higher than that in the success group (139° vs 134°, respectively; P = .01). Further, Cox hazard proportional analysis of the failure group showed that the predictors for a poor clinical outcome were the presence of a broken Shenton line, FNS angle >140°, center-edge (CE) angle <19°, body mass index (BMI) >23 kg/m(2), acetabular cartilage damage (MAHORN grades 3-5), and cartilage damage of the femoral head (International Cartilage Repair Society grades 2-4). The most important predictors for a poor clinical outcome at the time of surgery were a broken Shenton line and an FNS angle >140°.

CONCLUSION

Patients with a broken Shenton line, FNS angle >140°, CE angle <19°, or BMI >23 kg/m(2) at the time of surgery are not good candidates for the arthroscopic management of DDH.

Arthroscopy of the hip for patients with mild to moderate developmental dysplasia of the hip and femoroacetabular impingement

The purpose of this study was to determine patient-reported outcomes of patients with mild to moderate developmental dysplasia of the hip (DDH) and femoroacetabular impingement (FAI) undergoing arthroscopy of the hip in the treatment of chondrolabral pathology. A total of 28 patients with a centre-edge angle between 15° and 19° were identified from an institutional database. Their mean age was 34 years (18 to 53), with 12 female and 16 male patients. All underwent labral treatment and concomitant correction of FAI. There were nine reoperations, with two patients requiring revision arthroscopy, two requiring periacetabular osteotomy and five needing total hip arthroplasty.

Patients who required further major surgery were more likely to be older, male, and to have more severe DDH with a larger alpha angle and decreased joint space.

At a mean follow-up of 42 months (24 to 89), the mean modified Harris hip score improved from 59 (20 to 98) to 82 (45 to 100; p < 0.001). The mean Western Ontario and McMaster Universities Osteoarthritis Index score improved from 30 (1 to 61) to 16 (0 to 43; p < 0.001). Median patient satisfaction was 9.0/10 (1 to 10). Patients reported excellent improvement in function following arthroscopy of the hip.

This study shows that with proper patient selection, arthroscopy of the hip can be successful in the young patient with mild to moderate DDH and FAI.

Cite this article: Bone Joint J 2015;97-B:1316–21.

Femoroacetabular Impingement: Prevalent and Often Asymptomatic in Older Men: The Osteoporotic Fractures in Men Study

BACKGROUND

The epidemiology of femoroacetabular impingement (FAI) is important but incompletely understood, because most reports arise from symptomatic populations. Investigating the prevalence of FAI in a community-based cohort could help us better understand its epidemiology and in particular the degree to which it might or might not be associated with hip pain.

QUESTIONS/PURPOSES

The purposes of this study were (1) to evaluate the proportion of older (≥65 years of age) men with morphologic abnormalities consistent with FAI; and (2) to assess the association of the morphologic abnormalities with prevalent radiographic hip osteoarthritis (OA) and hip pain.

METHODS

Anteroposterior radiographs were obtained in 4140 subjects (mean age±SD, 77±5 years) from the Osteoporotic Fractures in Men study. We assessed each hip for cam, pincer, and mixed FAI types using validated radiographic definitions. Both intra- and interobserver reproducibility were >0.9. Radiographic hip OA was assessed by an expert reader (intraobserver reproducibility, 0.7-0.8) using validated methods, and summary grades of 2 or greater (on a scale from 0 to 4) were used to define radiographic hip OA. Covariates including hip pain in the last 30 days were collected by questionnaires that were answered by all patients included in this report. Logistic regressions with generalized estimating equations were performed to evaluate the association of radiographic features of FAI and arthrosis.

RESULTS

Pincer, cam, or mixed types of radiographic FAI had a prevalence of 57% (1748 of 3053), 29% (886 of 3053), and 14% (419 of 3053), respectively, in this group of older men. Both pincer and mixed types of FAI were associated with arthrosis but not with hip pain (odds ratio [OR], 1.63; 95% confidence interval [CI], 1.25-2.13; p<0.001 for pincer and OR, 2.49; 95% CI, 1.65-3.76; p<0.001 for mixed type). Patients with hips characterized by cam-type FAI had slightly reduced hip pain without the presence of arthrosis compared with hips without FAI (OR, 0.82; 95% CI, 0.68-0.99; p=0.037). A center-edge angle>39° and a caput-collum-diaphyseal angle<125° were associated with arthrosis (OR, 1.53; 95% CI, 1.22-1.94; p<0.001 and OR, 2.09; 95% CI, 1.24-3.51; p=0.006, respectively), but not with hip pain (OR, 0.89; 95% CI, 0.77-1.03; p<0.108 and OR, 0.99; 95% CI, 0.67-1.45; p=0.945, respectively). An impingement angle<70° was associated with less hip pain compared with hips with an impingement angle≥70° (OR, 0.76; 95% CI, 0.61-0.95; p=0.015).

CONCLUSIONS

FAI is common in older men and represents more of an anatomic variant rather than a symptomatic disease. This finding should raise questions on how age, activities, and this anatomic variant each contribute to result in symptomatic disease.

LEVEL OF EVIDENCE

Level III, prognostic study.

Prevalence of radiological femoroacetabular impingement in Japanese hip joints: detailed investigation with computed tomography

BACKGROUND

Femoroacetabular impingement (FAI) has been highlighted as a new etiology for osteoarthritis of the hip, and its prevalence has been reported in the past decade. In the present study, we performed a detailed investigation of the anatomical parameters related to FAI and calculated the prevalence of FAI-related findings in asymptomatic Japanese hip joints using computed tomography.

METHODS

We evaluated high-resolution reconstructed multislice computed tomography images in patients who had undergone computed tomography imaging in our institution for conditions unrelated to hip disorders. The examined parameters were as follows: center-edge (CE) angle; acetabular index; acetabular anteversion (five slices in the axial plane); and asphericity angle of the femoral head (AAFH) (six slices in multiple radial planes). The AAFH in the oblique axial slice through the center of the femoral neck is the so-called α-angle. We then examined the accurate prevalence of FAI-related findings in Japan.

RESULTS

We investigated a total of 103 hips. The mean age of the subjects was 59.4 years. The mean CE angle was 31.1° and the mean acetabular index was 7.0°. The mean acetabular anteversion was 20.3° at the level of the hip center, and decreased as the slice level neared the superior margin of the femoral head. The mean AAFH ranged from 40.6° to 49.2° in the radial planes. The AAFH was largest at 60° rotated slice from the oblique axial slice through the center of the femoral neck. The prevalence of FAI-related findings in these Japanese hip joints was assessed as follows. An AAFH of >50° in any slice was detected in 51.5 % of the hips, and acetabular anteversion was negative for all images in 16.5 % of the hips, meaning that a total of 56.3 % of the images met the criteria for radiological FAI.

CONCLUSIONS

With consideration of our results, we emphasize that "anatomical or radiological FAI" is not uncommon in Japanese hips. Therefore, the diagnosis of FAI should be performed with the clinical findings taken into account.

Inclusion and Exclusion Criteria in the Diagnosis of Femoroacetabular Impingement

PURPOSE

The purpose of this study was to clarify the criteria for femoroacetabular impingement (FAI) by way of a systematic review of FAI-related articles, as well as to define more appropriate inclusion or exclusion criteria in the diagnosis of FAI.

METHODS

A systematic review of FAI-related articles was performed using Web of Science. Thirty-two articles met the inclusion and exclusion criteria. In these articles we investigated radiographic findings for the diagnosis of FAI and the prevalence of each FAI-related finding.

RESULTS

The crossover sign was used in 22 articles (69%); acetabular index, 9 articles (28%); posterior wall sign, 7 articles (22%); and prominence of the ischial spine sign, 3 articles (7%). Regarding acetabular coverage, the lateral center-edge (LCE) angle was described in 13 articles (41%), in which an LCE angle either of more than 40° or of more than 30° combined with an acetabular index of less than 0° was considered an inclusion criterion for pincer impingement. Meanwhile, the alpha angle was used in 28 articles (88%), in which 50° or 55° was recommended as a positive finding of cam impingement.

CONCLUSIONS

Common findings of pincer or cam deformity were used to select FAI patients with sufficient coverage of the acetabulum with an LCE angle of more than 25°. Patients with an LCE angle of less than 25° or those with local acetabular deficiency regardless of having a normal LCE angle should be excluded from the FAI criteria, even if the FAI-related findings are positive.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I through IV studies.