Rintje Agricola

Cam impingement causes osteoarthritis of the hip: a nationwide prospective cohort study (CHECK)

Objective To determine the association between cam impingement, which is hip incongruity by a non-spherical femoral head and development of osteoarthritis. Methods A nationwide prospective cohort study of 1002 early symptomatic osteoarthritis patients (CHECK), of which standardised anteroposterior pelvic radiographs were obtained at baseline and at 2 and 5 years follow-up. Asphericity of the femoral head was measured by the α angle. Clinically, decreased internal hip rotation (≤20°) is suggestive of cam impingement. The strength of association between those parameters at baseline and development of incident osteoarthritis (K&L grade  2) or end-stage osteoarthritis (K&L grades 3, 4, or total hip replacement) within 5 years was expressed in OR using generalised estimating equations. Results At baseline, 76% of the included hips had no radiographic signs of osteoarthritis and 24% doubtful osteoarthritis. Within 5 years, 2.76% developed end-stage osteoarthritis. A moderate (α angle >60°) and severe (α angle >83°) cam-type deformity resulted in adjusted OR of 3.67 (95% CI 1.68 to 8.01) and 9.66 (95% CI 4.72 to 19.78), respectively, for end-stage osteoarthritis. The combination of severe cam-type deformity and decreased internal rotation at baseline resulted in an even more pronounced adjusted OR, and in a positive predictive value of 52.6% for end-stage osteoarthritis. For incident osteoarthritis, only a moderate cam-type deformity was predictive OR=2.42 (95% CI 1.15 to 5.06). Conclusions Individuals with both severe cam-type deformity and reduced internal rotation are strongly predisposed to fast progression to end-stage osteoarthritis. As cam impingement might be a modifiable risk factor, early recognition of this condition is important.

The Development of Cam-Type Deformity in Adolescent and Young Male Soccer Players

Background: Cam impingement is a well-recognized cause of hip pain and might cause osteoarthritis of the hip. Clinically, cam impingement is mostly observed in young, active male patients, but only a few studies have focused on the manifestation of cam-type deformities during skeletal development. Purpose: To determine the age of onset and prevalence of cam-type deformities in young male soccer players versus controls. Study Design: Cross-sectional study; Level of evidence, 3. Methods: In this study, 89 elite preprofessional soccer players and 92 controls aged 12 to 19 years were included. In the soccer players, range of motion and impingement tests were performed. Both an anteroposterior (AP) pelvic radiograph and a frog-leg lateral radiograph of the hip were obtained according to a standardized protocol. Controls with both an AP pelvic and a frog-leg lateral radiograph and no hip disorders were obtained from radiology databases. The α angle was automatically determined in all radiographs, using a threshold value of 60° to define a cam-type deformity. Further, all radiographs were scored using a 3-point scoring system. The anterosuperior head-neck junction was classified as (1) normal, (2) flattened, or (3) having a prominence. Differences in prevalence were tested using logistic regression. Differences in range of motion were calculated using generalized estimating equations. Results: An α angle >60° was already found at the age of 12 years in some soccer players and controls. A cam-type deformity defined by α angle tended to be more prevalent in soccer players (26%) than in controls (17%; P = .31). In 13% of soccer players, a prominence was visible on radiographs and was first seen at the age of 13 years. The anterosuperior flattening (56% vs 18%, P = .0001) and prominence (13% vs 0%, P < .03) were more prevalent in soccer players than in controls. Conclusion: Cam-type deformities were recognizable and present from the age of 13 years and were more prevalent in soccer players than in their nonathletic peers. Cam-type deformity develops during adolescence and is likely to be influenced by high-impact sports practice.

A Cam Deformity Is Gradually Acquired During Skeletal Maturation in Adolescent and Young Male Soccer Players A Prospective Study With Minimum 2-Year Follow-up

Background: A cam deformity is a major risk factor for hip osteoarthritis, and its formation is thought to be influenced by high-impact sporting activities during growth. Purpose: To (1) prospectively study whether a cam deformity can evolve over time in adolescents and whether its formation only occurs during skeletal maturation and (2) examine whether clinical or radiographic features can predict the formation of a cam deformity. Study Design: Cohort study (prognosis); Level of evidence, 2. Methods: Preprofessional soccer players (N = 63; mean age, 14.43 years; range, 12-19 years) participated both at baseline and follow-up (mean follow-up, 2.4 ± 0.06 years). At both time points, standardized anteroposterior and frog-leg lateral radiographs were obtained. For each hip, the α angle was measured, and the anterosuperior head-neck junction was classified by a 3-point visual system as normal, flattened, or having a prominence. Differences between baseline and follow-up values for the α angle and the prevalence of each visual hip classification were calculated. Additionally, the amount of internal hip rotation, growth plate extension into the neck, and neck shaft angle were determined. Results: Overall, there was a significant increase in the prevalence of a cam deformity during follow-up. In boys aged 12 and 13 years at baseline, the prevalence of a flattened head-neck junction increased significantly during follow-up (13.6% to 50.0%; P = .002). In all hips with an open growth plate at baseline, the prevalence of a prominence increased from 2.1% to 17.7% (P = .002). After closure of the proximal femoral growth plate, there was no significant increase in the prevalence or increase in severity of a cam deformity. The α angle increased significantly from 59.4° at baseline to 61.3° at follow-up (P = .018). The amount of growth plate extension was significantly associated with the α angle and hip classification (P = .001). A small neck shaft angle and limited internal rotation were associated with cam deformities and could also significantly predict the formation of cam deformities (α angle >60°) at follow-up. Conclusion: In youth soccer players, cam deformities gradually develop during skeletal maturation and are probably stable from the time of growth plate closure. The formation of a cam deformity might be prevented by adjusting athletic activities during a small period of skeletal growth, which will have a major effect on the prevalence of hip osteoarthritis.

Cam impingement of the hip—a risk factor for hip osteoarthritis

Femoroacetabular impingement (FAI) is characterized by abnormal contact between the proximal femur and the acetabulum. Two subtypes have been described: pincer impingement, caused by an overcovered acetabulum; and cam impingement, which occurs as a result of an aspherical femoral head (cam abnormality). A strong correlation exists between cam impingement and the subsequent development of hip osteoarthritis (OA). Major cam abnormalities confer a high risk of OA. However, the association between cam abnormalities and the pathology of OA has been difficult to compare between studies, as different methods have been used to define the abnormality. Cam abnormalities are acquired during skeletal growth and could be influenced by high impact sporting activities. Preventative treatments aiming to reduce the incidence of cam abnormalities and subsequent OA could, therefore, be developed. In this Perspective, we discuss the current understanding of FAI, focusing on cam abnormalities and their association with OA.

Cam impingement: defining the presence of a cam deformity by the alpha angle: data from the CHECK cohort and Chingford cohort.

INTRODUCTION Cam impingement is characterized by abnormal contact between the proximal femur and acetabulum caused by a non-spherical femoral head, known as a cam deformity. A cam deformity is usually quantified by the alpha angle; greater alpha angles substantially increase the risk for osteoarthritis (OA). However, there is no consensus on which alpha angle threshold to use to define the presence of a cam deformity. AIM To determine alpha angle thresholds that define the presence of a cam deformity and a pathological cam deformity based on development of OA. METHODS Data from both the prospective CHECK cohort of 1002 individuals (45-65 years) and the prospective population-based Chingford cohort of 1003 women (45-64 years) with respective follow-up times of 5 and 19 years were combined. The alpha angle was measured at baseline on anteroposterior radiographs, from which a threshold for the presence of a cam deformity was determined based on its distribution. Further, a pathological alpha angle threshold was determined based on the highest discriminative ability for development of end-stage OA at follow-up. RESULTS A definite bimodal distribution of the alpha angle was found in both cohorts with a normal distribution up to 60°, indicating a clear distinction between normal and abnormal alpha angles. A pathological threshold of 78° resulted in the maximum area under the ROC curve. CONCLUSION Epidemiological data of two large cohorts shows a bimodal distribution of the alpha angle. Alpha angle thresholds of 60° to define the presence of a cam deformity and 78° for a pathological cam deformity are proposed.

Which factors differentiate athletes with hip/groin pain from those without? A systematic review with meta-analysis

Background Hip and groin injuries are common in many sports. Understanding the factors differentiating athletes with hip/groin pain from those without these injuries could facilitate management and prevention. Objective Conduct a systematic review and meta-analysis of the literature on factors differentiating athletes with and without hip/groin pain. Methods The review was registered as PROSPERO CRD42014007416 and a comprehensive, systematic search was conducted in June 2014. Inclusion criteria were: cross-sectional, cohort or case–control study designs of n>10 that examined outcome measures differentiating athletes with and without hip/groin pain. Two authors independently screened search results, assessed study quality, and performed data extraction. Methodological heterogeneity was determined and data pooled for meta-analysis when appropriate. A best evidence synthesis was performed on the remaining outcome measures. Results Of 2251 titles identified, 17 articles were included of which 10 were high quality. Sixty two different outcome measures were examined, 8 underwent meta-analysis. Pooled data showed strong evidence that athletes with hip/groin pain demonstrated: pain and lower strength on the adductor squeeze test, reduced range of motion in hip internal rotation and bent knee fall out; however, hip external rotation range was equivalent to controls. Strong evidence was found that lower patient-reported outcome (PRO) scores, altered trunk muscle function, and moderate evidence of bone oedema and secondary cleft sign were associated with hip/groin pain. Conclusions PROs, pain and reduced strength on the adductor squeeze test, reduced range of motion in internal rotation and bent knee fall out are the outcome measures that best differentiate athletes with hip/groin pain from those without this pain.

The relationship between the frequency of football practice during skeletal growth and the presence of a cam deformity in adult elite football players

Background/aim Cam deformity (CD) is likely a bony adaptation in response to high-impact sports practice during skeletal growth. We ascertained whether a dose–response relationship exists between the frequency of football practice during skeletal growth and the presence of a CD in adulthood, and if the age at which a football player starts playing football is associated with the presence of a CD in adulthood. Methods Prevalence of a CD (α angle>60°) and a pathological CD (α angle>78°) was studied using standardised anteroposterior (AP) and frog-leg lateral (FLL) radiographs that were obtained during seasonal screening. The age of starting to play football with a low frequency (LF; ≤3 times/week) and high frequency (HF; ≥4 times/week) was retrospectively assessed. The differences in prevalence of a CD per hip, in either view, between groups were calculated by logistic regression with generalised estimating equations. Results 63 players (mean(±SD) age 23.1(±4.2) years) participated, yielding 126 hips for analysis. The prevalence of a CD in the FLL was 40% (n=82) in players who started playing HF football from the age of 12 years or above, and 64% (n=44) in those playing HF football before the age of 12 years (p=0.042). This was also true for a pathological CD (12% vs 30%, p=0.038). The AP views revealed no difference. Conclusions Our results indicate a probable dose–response relationship between the frequency of football practice during skeletal growth and the development of a CD, which should be confirmed in future prospective studies.

Mechanical factors explain development of cam-type deformity.

OBJECTIVE A cam-type deformity drastically increases the risk of hip osteoarthritis (OA). Since this type of skeletal anomaly is more prevalent among young active adults, it is hypothesized that the loading conditions experienced during certain types of vigorous physical activities stimulates formation of cam-type deformity. We further hypothesize that the growth plate shape modulates the influence of mechanical factors on the development of cam-type deformity. DESIGN We used finite element (FE) models of the proximal femur with an open growth plate to study whether mechanical factors could explain the development of cam-type deformity in adolescents. Four different loading conditions (representing different types of physical activities) and three different levels of growth plate extension towards the femoral neck were considered. Mechanical stimuli at the tissue level were calculated by means of the osteogenic index (OI) for all loading conditions and growth plate shape variations. RESULTS Loading conditions and growth plate shape influence the distribution of OI in hips with an open growth plate, thereby driving the development of cam-type deformity. In particular, specific types of loads experienced during physical activities and a larger growth plate extension towards the femoral neck increase the chance of cam-type deformity. CONCLUSIONS Specific loading patterns seem to stimulate the development of cam-type deformity by modifying the distribution of the mechanical stimulus. This is in line with recent clinical studies and reveals mechanobiological mechanisms that trigger the development of cam-type deformity. Avoiding these loading patterns during skeletal growth might be a potential preventative strategy for future hip OA.

Hip Range of Motion Is Lower in Professional Soccer Players With Hip and Groin Symptoms or Previous Injuries, Independent of Cam Deformities

Background: Soccer (football) players often have hip and groin symptoms (HGS), and a previous groin injury is a risk factor for a relapse. Decreased hip range of motion (HROM) has been related to both hip and groin pain and the presence of a cam deformity. How these factors interact is unknown. Purpose: The first aim was to study whether HGS are associated with HROM. The second aim was to study the association of the presence of a cam deformity with HROM. Additionally, the influence of a cam deformity on the relationship between HGS and HROM was examined. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Seasonal screening data of 2 professional soccer clubs were used. Variables for HGS were current hip or groin pain, the Copenhagen Hip and Groin Outcome Score (HAGOS), and previous hip- and groin-related time-loss injuries (HGTIs). HROM was determined for hip internal rotation (IR), external rotation, and total rotation (TR) in the supine position and for the bent knee fall out (BKFO) test. A cam deformity was defined by an alpha angle >60° on standardized anteroposterior pelvic and frog-leg lateral radiographs. Results: Sixty players (mean [±SD] age, 23.1 ± 4.2 years) were included. All were noninjured at the time of screening. Current hip or groin pain was not associated with HROM. Hips of players in the lowest HAGOS interquartile range (thus most affected by complaints; n = 12) showed less IR (23.9° ± 8.7° vs 28.9° ± 7.8°, respectively; P = .036) and TR (58.2° ± 13.5° vs 65.6° ± 11.8°, respectively; P = .047) than those in the highest interquartile range (n = 29). No such differences were found for BKFO (P = .417). Hips of players with a previous HGTI showed less IR (21.1° ± 6.8° vs 28.3° ± 8.9°, respectively; P < .001) and TR (56.0° ± 8.2° vs 64.5° ± 13.6°, respectively; P < .001) than those without a previous HGTI. This was independent of the presence of a cam deformity. BKFO did not differ between groups (P = .983). Hips with a cam deformity showed less but nonsignificant IR (25.5° ± 10.3° vs 29.0° ± 7.1°, respectively; P = .066) and TR (P = .062) and higher but nonsignificant BKFO values (17.1 cm ± 3.4 cm vs 14.2 cm ± 4.6 cm, respectively; P = .078) than those without a cam deformity. Conclusion: Decreased HROM in professional soccer players is associated with more hip- and groin-related symptoms and with previous injuries, independent of the presence of a cam deformity.

Cam Deformity and Acetabular Dysplasia as Risk Factors for Hip Osteoarthritis

Cam deformity and acetabular dysplasia have been recognized as relevant risk factors for hip osteoarthritis (OA) in a few prospective studies with limited sample sizes. To date, however, no evidence is available from prospective studies regarding whether the magnitude of these associations differs according to sex, body mass index (BMI), and age.