Prevalence of femoroacetabular impingement in asymptomatic contralateral hips in patients with unilateral idiopathic osteoarthritis

The prevalence of femoroacetabular impingement as an aetiologic factor for end-stage degenerative osteoarthritis of the hip joint: analysis of 1,000 cases

OBJECTIVE

The main purpose of the present study was to determine the prevalence of FAI among patients who underwent total hip arthroplasty (THA) with the diagnosis of end-stage osteoarthritis (OA) of the hip joint in a tertiary referral centre.

DESIGN

A retrospective search of the institutional archive database for patients who had undergone THA between the years 2005 and 2010 was conducted with the analysis of the recorded radiographic images. A total of 1,004 patients including 690 (68.7%) females and 314 (31.3%) males were identified. All radiographs were reviewed by 3 of the authors. Intra- and interobserver consistencies were calculated. The prevalence of femeroacetabular impingement (FAI) as a predisposing diagnosis resulting in end-stage degenerative joint disease treated with THA was determined.

RESULTS

The most common diagnosis was developmental dysplasia of the hip (DDH). The predisposing aetiologic factor leading to end-stage degenerative hip disease treated with THA was undetermined for 26 patients (2.6%). The number of patients who were diagnosed as cam-type FAI by all of the observers was 83, whereas it was 16 for pincer-type FAI. Interobserver agreement was very high in the evaluation of the stated ethiologies of hip osteoarthritis. The contingency coefficient for the diagnosis of FAI was 0.71 between observers.

CONCLUSIONS

Our study may be a reference for further investigations to develop a better understanding of the underlying pathological factors in patients undergoing THA due to end-stage OA of the hip joint.

Hip arthroscopy results in improved patient reported outcomes compared to non-operative management of waitlisted patients

Hip arthroscopy (HA) is an established treatment option to address intra-articular pathology of the hip. However, some clinicians encourage non-operative management (NOM). Non-operative management may include active measures such as physiotherapy and intra-articular steroid injections, or NOM may involve so called watchful waiting with no active intervention. These approaches, along with surgery have been detailed recently in the Warwick Agreement, a Consensus Statement regarding diagnosis and treatment of Femoroacetabular Impingement Syndrome The aim of this study is to compare the change in clinical outcome scores of waitlisted patients with intra-articular hip pathology who receive no active treatment with matched controls that have undergone HA. Patients less than 60 years of age were identified from a HA waiting list in a single hospital in the Australian public hospital system. Patient reported outcomes (PRO) were collected whilst patients waited for surgery. During this waiting period no specific treatment was offered. A separate group of patients who had previously undergone HA were matched based on age, sex, body mass index and baseline non-arthritic hip scores (NAHS). The groups were compared using the NAHS as the primary outcome measures. Modified Harris Hip Scores were also collected and compared. Thirty-six patients were included in each group, with a mean follow up of 19 months (12–36). There were no significant differences in age, sex, BMI and NAHS between groups at baseline. At final follow up, mean NAHS scores after HA were significantly higher than scores after NOM, 82.1 (36.4–100.0) versus 48.9 (11.3–78.8), respectively (P < 0.001) with a large effect size for mean change in scores between groups (d = 1.77, 95% CI 1.21–2.30). Mean mHHS after HA were significantly higher than scores after NOM, 84.3 (15.4–100.0) versus 48.1 (21.0–66.0) respectively (P < 0.001), with a large effect size for mean change in scores between groups (d = 1.92, 95% CI 1.34–2.46). HA may lead to significant improvements in PRO when compared to non-operative management of waitlisted patients with intra-articular pathology of the hip at 18 months follow-up.

Does Femoroacetabular Impingement Contribute to the Development of Hip Osteoarthritis? A Systematic Review

Femoroacetabular impingement (FAI) has been linked to specific patterns of cartilage damage. The goal of this systematic review is to answer the following questions: (1) Does FAI contribute to the development and progression of hip osteoarthritis (OA)? (2) If FAI does contribute to the development and progression of hip OA, does CAM-type or pincer-type impingement play a greater role? A search of the electronic databases, MEDLINE and EMBASE, was performed to identify relevant studies performed between January 1, 2000 and January 1, 2015 that link the pathophysiology of OA to FAI. Methodological quality of included studies was assessed by 2 reviewers using the Methodological Index for Non-Randomized Studies criteria. An intraclass correlation coefficient with 95% confidence intervals was used to determine agreement between reviewers on quality scores. Overall 35 studies were identified that met inclusion criteria. Certain morphologic features of CAM-type FAI, particularly elevated alpha angle, do seem to predispose select patients to radiographic progression of hip OA. In comparison with pincer-type impingement, the association between CAM-type impingement and hip OA is better understood. Long-term surgical outcome studies will further delineate the role of FAI in the development and progression of hip OA.

The Natural History of Osteoarthritis: What Happens to the Other Hip?

BACKGROUND

Idiopathic osteoarthritis (OA) is a common diagnosis leading to hip arthroplasty. Patients undergoing unilateral hip arthroplasty often wonder whether their other hip will follow the same path as the one that was operated on, and if so, when? There also are limited data available to predict from AP radiographs which contralateral hips will have OA develop and which will not.

QUESTIONS/PURPOSES

We sought (1) to determine the incidence of contralateral osteoarthritic degeneration in a group of patients who were treated with unilateral hip arthroplasty; and (2) to identify clinical and radiographic features associated with the development of contralateral OA.

METHODS

Between 1998 and 2010, we performed 398 hip arthroplasties on patients with unilateral primary hip OA, who at the time of surgery did not have any symptoms in the contralateral hip. Of those, 367 (92%) had a minimum 2-year radiographic followup (mean, 11 years; range, 2-17 years). The 31 patients dropped from the study for lack of radiographic followup had comparable preoperative features as the study group. We performed a radiographic analysis on the baseline AP radiographs to see what factors were associated with arthritis progression, and we performed Kaplan-Meier survivorship analysis with contralateral hip pain and contralateral THA as the endpoints.

RESULTS

Kaplan-Meier survival estimates indicated that 10 years after the baseline evaluation, 59% (95% CI, 53%-65%) of the patients remained free of symptoms on the contralateral hip and 81% (95% CI, 75%-85%) remained free of an arthroplasty on the contralateral hip. Sex, age, weight, or BMI were not associated with the development of OA on the contralateral hip with the numbers available. Reduced minimum joint space width (hazard ratio, 0.299; 95% CI, 0.237-0.378), low center-edge angle (hazard ratio, 0.941; 95% CI, 0.915-0.968), low head-to-neck ratio (hazard ratio, 1.555; 95% CI, 1.088-2.223), and the presence of osteophytes (hazard ratio, 1.453; 95% CI, 1.001-2.110) were associated with the development of contralateral OA. In hips with a center-edge angle greater than 25°, a head-to-neck ratio of 1.3 or less increased the chances of development of OA by 86% (hazard ratio, 1.857; 95% CI, 1.235-2.793).

CONCLUSIONS

The variables we studied can easily be assessed from an AP pelvis radiograph so physicians can predict the occurrence of contralateral OA and the need for future hip arthroplasty in their patients needing unilateral arthroplasty. However, the data available might have led us to underestimate the need for contralateral arthroplasty. Future studies with a prospective design should aim at completing the list of radiographic features associated with the development of OA by adding a review of lateral radiographs.

LEVEL OF EVIDENCE

Level IV, prognostic study.

The effect of femoro-acetabular impingement on the kinematics and kinetics of the hip joint

Gait analysis is an objective tool that has been used to assess and monitor treatment for many musculoskeletal conditions. Recently, it has been used to assess the impact of femoro-acetabular impingement (FAI) on the hip and lower limb movements. There have been a fairly limited number of studies published so far reporting unexpected and inconsistent results, which calls for more research to be conducted in this arena. In the light of the limited data available, it has been challenging to reconcile the contradictions in some of these results, and therefore no coherent conclusions could be drawn. In this short article, we attempt to explain some of the abnormal kinematic and kinetic patterns associated with FAI by highlighting similarities between the gait seen in early osteoarthritis (OA) and that of FAI. We also propose an approach for future research in this field and emphasise the importance of quantifying early OA in FAI based on magnetic resonance imaging (MRI) scans and the amount of chondral damage seen during open or arthroscopic surgery.

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

In Japan, osteoarthritis (OA) of the hip secondary to acetabular dysplasia is very common, and there are few data concerning the pathogeneses and incidence of femoroacetabular impingement (FAI). We have attempted to clarify the radiological prevalence of painful FAI in a cohort of Japanese patients and to investigate the radiological findings. We identified 176 symptomatic patients (202 hips) with Tönnis grade 0 or 1 osteoarthritis, whom we prospectively studied between August 2011 and July 2012. There were 61 men (65 hips) and 115 women (137 hips) with a mean age of 51.8 years (11 to 83). Radiological analyses included the α-angle, centre–edge angle, cross-over sign, pistol grip deformity and femoral head neck ratio. Of the 202 hips, 79 (39.1%) had acetabular dysplasia, while 80 hips (39.6%) had no known aetiology. We found evidence of FAI in 60 hips (29.7%). Radiological FAI findings associated with cam deformity were the most common. There was a significant relationship between the pistol grip deformity and both the α-angle (p < 0.001) and femoral head–neck ratio (p = 0.024). Radiological evidence of symptomatic FAI was not uncommon in these Japanese patients.

Cite this article: Bone Joint J 2013;96-B:172–6.

Spectrum of radiographic femoroacetabular impingement morphology in adolescents and young adults: an EOS-based double-cohort study

BACKGROUND

Symptomatic femoroacetabular impingement is a known prearthritic condition. Impingement morphology is poorly defined in the adolescent population. The purpose of this study was to document the prevalence of radiographic impingement morphology in adolescents with no symptomatic hip problems.

METHODS

Ninety anteroposterior images of the hip in forty-five consecutive adolescents with scoliosis met the inclusion criteria. Sex distribution was equal. The second cohort (ninety hips) was an age-matched group with no scoliosis. None had symptomatic hip problems. Images were analyzed for coxa profunda, protrusio acetabuli, Tönnis angle, anteroposterior alpha angle, center-edge angle, acetabular crossover, ischial spine sign, and neck-shaft angle.

RESULTS

Of the 180 hips, 92.8% demonstrated at least one parameter suggesting impingement morphology, whereas 52.2% showed at least two signs. Evidence of coxa profunda was seen in 81.7% of the hips, while a negative Tönnis angle was seen in 31.1% and a center-edge angle indicative of acetabular overcoverage was seen in 15%. An acetabular crossover sign was detected in 27.2% of the hips, while an abnormal anteroposterior alpha angle was found in 5.6% of the hips in male patients and 6.7% of the hips in female patients. Statistical analysis revealed that abnormal alpha angles (p = 0.029), crossover signs (p = 0.029), and ischial spine signs (p = 0.026) were more common in the cohort without scoliosis, and coxa profunda was more common in females (p = 0.034).

CONCLUSIONS

There was a high prevalence of radiographic impingement morphology beyond the spectrum of normal in this double-cohort study of adolescents. Femoroacetabular impingement remains a dynamic problem, and we caution against relying only on the use of hard-set static radiographic parameters when evaluating femoroacetabular impingement. This study raises the important question of what morphologic characteristics should be defined as abnormal, when at least one finding of impingement morphology is noted in such a large segment of the population. On the basis of the normative data obtained, reference values for radiographic parameters of femoroacetabular impingement morphology should be redefined. Normal values for a Tönnis angle were between -8° and 14°, the upper limit of the center-edge angle was 44°, and the normal values for femoral neck-shaft angle were between 121° and 144°. Surgical indications should be tailored to physical examination findings and not radiographic findings alone.

The pathoanatomy and arthroscopic management of femoroacetabular impingement

Femoroacetabular impingement (FAI) causes pain and chondrolabral damage via mechanical overload during movement of the hip. It is caused by many different types of pathoanatomy, including the cam 'bump', decreased head-neck offset, acetabular retroversion, global acetabular overcoverage, prominent anterior-inferior iliac spine, slipped capital femoral epiphysis, and the sequelae of childhood Perthes' disease. Both evolutionary and developmental factors may cause FAI. Prevalence studies show that anatomic variations that cause FAI are common in the asymptomatic population. Young athletes may be predisposed to FAI because of the stress on the physis during development. Other factors, including the soft tissues, may also influence symptoms and chondrolabral damage. FAI and the resultant chondrolabral pathology are often treated arthroscopically. Although the results are favourable, morphologies can be complex, patient expectations are high and the surgery is challenging. The long-term outcomes of hip arthroscopy are still forthcoming and it is unknown if treatment of FAI will prevent arthrosis.