Femoral Neck Stress Fractures and Imaging Features of Femoroacetabular Impingement

Increased Risk of Femoral Neck Stress Fractures in Patients With Cam or Pincer Morphology

Previous studies suggest a relationship between femoroacetabular impingement (FAI) and femoral neck stress fractures (FNSF), due to pathologic biomechanics in the setting of femoral head abutment (cam morphology) and/or acetabular overcoverage (pincer morphology). The purpose of this study is to evaluate the association between cam or pincer morphology and FNSF, compared to a control group of patients without hip pain. A retrospective review of the electronic medical record at a single institution was queried for patients with FNSF over a 10-year time period from January 2011-2021. These patients were compared to a control group with diagnostic radiographs and a chief complaint that was not hip pain presenting to the institution's emergency department. Hip morphology was evaluated radiographically. A multivariate logistic regression was used to investigate an association between FNSF and cam or pincer morphology. Eighty-three patients with FNSF and a mean age of 38.6 years were compared to 55 healthy controls with a mean age of 35.8 years. Patients in the FNSF group were more often female, white, and had lower BMI. These patients were also more likely to have associated cam morphology (p = 0.010). Binary logistic regression demonstrated a statistically significant independent association between both cam (OR 5.2, p = 0.01) and pincer (OR 4.6, p = 0.022) morphology with FNSF when controlling for demographic variables. Black race and higher BMI were protective factors for FNSF (OR 0.09, OR 0.84, p < 0.01). In summary, radiographic cam morphology, superolateral acetabular overcoverage, female sex, and lower BMI are risk factors for sustaining FNSF, while the black race was found to be protective.

Cephalomedullary Nail Fixation for Prophylactic Treatment of Incomplete Femoral Neck Stress Fractures in Athletes

Background

The traditional management of femoral neck stress fractures (FNSFs)-such as cannulated screw fixation-requires a period of protected weightbearing and does not provide fixed angle stability.

Purpose

To report the technique and outcomes of a single surgeon's case series of prophylactic fixation of incomplete FNSFs using cephalomedullary nailing (CMN) followed by immediate weightbearing.

Study Design

Case series; Level of evidence, 4.

Methods

A retrospective review of 17 FNSFs treated using CMN by a single surgeon over 7 years was conducted. descriptive, injury, and treatment-related data were collected. Perioperative complications and recovery courses were included for each case. Descriptive statistics were used to summarize the characteristics, clinical presentation, diagnostic imaging findings, treatment details, and follow-up outcomes of the study population.

Results

There were no perioperative complications across the 17 injuries. The mean intraoperative blood loss was 67 mL (range, 20-150 mL). In all 17 cases, immediate full weightbearing was recommended. All patients were able to initiate a return to running by 6 weeks postoperatively. Time until completion of narcotic use was noted for 15 cases, with narcotic medications no longer required at 2 weeks for 12 injuries (71%), at 6 weeks for 2 injuries (12%), and at 3 months for 1 injury (5.9%). Patients had a mean of 12.4 months of follow-up (range, 6-48 months). At the final follow-up, 5 cases (29%) had persistent pain-1 from gluteus medius tendinosis and 4 from painful distal interlocking screws. Two patients underwent the removal of symptomatic hardware.

Conclusion

This study demonstrated that prophylactic fixation of FNSFs with CMN in endurance athletes is a safe and effective construct that permits early return to baseline impact activity because of the inherent stability of the construct, with a favorable complication profile-although with a 30% rate of persistent pain from the surgical site.

Uncommon Twist: Femoral Neck Stress Fracture in a High-Performance Athlete With an Incidental Diagnosis of Femoroacetabular Impingement

Femoral neck stress fractures (FNSFs) are rare but significant injuries, often leading to delayed diagnosis due to nonspecific symptomatology. This case report presents a 30-year-old professional surfer who experienced acute groin pain during a half marathon, ultimately diagnosed with a left intertrochanteric line femur stress fracture and with femoroacetabular impingement (FAI) in the opposite hip. Despite being physically fit, his presentation challenges the prevailing notion that FNSFs predominantly occur in military personnel or the elderly. The patient underwent surgical left hip osteosynthesis without complications. This case highlights the importance of early suspicion of FNSFs in young, active individuals and emphasizes the need for comprehensive evaluation to prevent complications like osteonecrosis and malunion. It underscores the value of a broad differential diagnosis and timely intervention in optimizing outcomes, especially in the context of rising high-impact sports participation.

Femoral Neck Stress Fracture of a Male, Healthy Marathon Runner - Case Report and Literature Review

In the present report, a case of a healthy, 38-year-old male recreational marathon runner who presented in the emergency department is discussed. He was diagnosed with a stress fracture of the femoral neck and treated surgically using a dynamic hip screw (DHS). One year after surgery, the patient was able to return to most of his previous sports activities. In the present report, the existing literature on the subject is exhibited and the points of interest in terms of incidence, risk factors, diagnosis, classification, treatment, and long-term outcome are analyzed. We suggest operative treatment of stress fractures of the femoral neck even in cases of complete undisplaced ones. This way, the risk of a displacement is counteracted, and patients can quickly return to daily activities without having to withstand long-term immobilization.

Multiple stress fractures of unilateral femur: A case report

BACKGROUND

Stress fractures of the femoral neck are not common in clinical practice, and simultaneous stress fractures of the femoral neck and proximal femur of the unilateral femur are even more rare. We introduce a case of this type of fracture that was treated in our department, analyze the causes, and review similar stress fractures reported in the literature to provide references for the diagnosis and treatment of such conditions.

CASE SUMMARY

A 62-year-old female, with a free medical history, was admitted to the hospital mainly due to pain in the right hip and worsening pain in the right thigh. The patient had no obvious history of trauma. X-ray and computed tomography showed fracture of the femoral neck and proximal femur. The patient had undergone surgery 1 year prior to address a fracture of the left proximal femur that had occurred in a traffic accident. Our first consideration was stress fracture of the femoral neck; however, simultaneous stress fractures of the femoral neck and proximal femur of the unilateral femur were seen. The femoral neck stress fracture was a tension fracture, with obvious displacement and varus deformity of the hip. Considering that the patient was an elderly female, we performed total hip arthroplasty. Follow-up X-rays showed that the stress fracture of the proximal femur had mostly healed after 3 mo.

CONCLUSION

Muscle fatigue and hip varus deformity provide an anatomical basis for the occurrence of femoral neck stress fractures.

Femoral Neck Stress Fractures: An Updated Review

Femoral neck stress fractures represent a relatively rare spectrum of injuries that most commonly affect military recruits and endurance athletes. If unrecognized and if proper treatment is not initiated, this condition carries potentially devastating consequences. Patients will typically present with an insidious onset, atraumatic hip, and groin pain that is relieved with rest. The condition may be initially misdiagnosed because radiographs are often normal. Magnetic resonance imaging has demonstrated superior specificity, sensitivity, and accuracy compared with other diagnostic modalities in identifying and classifying stress fractures of the femoral neck. Treatment algorithms are based on the MRI fracture morphology and presence of an intra-articular effusion. Nonsurgical management consists of a period of non-weight-bearing followed by gradual return to activity. Surgical management consists of prophylactic fracture fixation with cannulated screws to prevent fracture progression. If left untreated, patients may progress to a complete displaced femoral neck fracture, which can be associated with complications that include nonunion, osteonecrosis of the femoral head, and long-term disability. These poor outcomes emphasize the importance of early diagnosis and treatment of incomplete femoral neck stress fractures.

Increased prevalence of femoroacetabular impingement on the elderly with fractures of the proximal femur

Objectives: Femoroacetabular impingement (FAI) has been recently related to several pathologies, besides chondral injury and hip arthritis. We aim to investigate the prevalence of FAI morphology in an elderly cohort hospitalized due to a proximal femur fracture and compare these findings to a control group. We hypothesize that limited medial rotation due to FAI’s morphology could increase stresses to the proximal femur, acting as a facilitating mechanism for fractures in this region. Therefore, a higher prevalence of FAI morphology would be present in the study group. Methods: A retrospective cross-sectional study was performed based on the analysis of radiographic images in AP and lateral views of the fractured hip. Firstly, we have set to measure FAI prevalence in an elderly cohort victimized by fractures of the proximal by measures of the alpha, Tönnis, and lateral center edge angles of a hundred consecutive patients hospitalized for proximal femur fractures. Secondly, we have analyzed the possible relationship between the FAI subtypes and the type of fracture. Finally, we have compared this sample’s data with that of a similar control cohort not affected by fracture. Results: The cohort in this study displayed a higher prevalence of pathological changes in the Tönnis, center-edge, and alpha angles with odds ratios of 3.41, 2.56, and 4.80, respectively (with statistical significance). There was also a significant relationship between cam-type FAI and intertrochanteric fractures, corroborating our initial hypotheses. Conclusions: This study demonstrated that a cohort of older patients affected by fractures of the proximal femur had an increased prevalence of radiographic signs of femoroacetabular impingement. Furthermore, this is the first study demonstrating a statistically significant relationship of cam-type FAI with intertrochanteric fractures, suggesting a possible cause and effect relationship.

[Femoral neck stress fractures and femoroacetabular impingement : A retrospective case study and literature review]

BACKGROUND

Femoroacetabular impingement (FAI) can lead to morphologic damage of both the acetabulum and the femoral neck. Recent reports have found an association between impingement deformities and the development of femoral neck stress fractures. The aim of this study was to report a series of patients with these findings and to update the current evidence on the topic.

MATERIAL AND METHODS

5 patients (6 cases) with atraumatic femoral neck fractures and FAI were identified in the Dresden hip registry from 2015 to 2018. Demographic data, comorbidities, radiographic results and bone metabolism results were described. A literature search was conducted using keywords related to femoral neck stress fractures and FAI syndrome.

RESULTS

The average age of the series was 39 (range: 22-52), 2 patients were female and 3 male. A total of 12 surgical procedures were performed. 4 of the 5 patients showed radiographic features of pincer and/or cam-FAI, whereas 3 patients had a decreased femoral antetorsion (-7° to +7° antetorsion). In 3 patients, magnetic resonance imaging revealed additional signs of avascular necrosis ARCO I. There was a lack of FAI-specific treatment recommendations in the available literature.

DISCUSSION

Radiographic results of the patients evaluated suggested that impingement-associated deformities of the hip may cause femoral neck stress fractures, which is in line with the available literature. This potential coincidence should be integrated in diagnostic algorithms and therapeutic approaches.

Stress Fractures of the Hip and Pelvis

Stress fractures refer to overuse injuries of bone resulting from repetitive mechanical stress. Stress fractures of the hip and pelvic region, while relatively uncommon, have become increasingly recognized in certain populations, particularly long-distance runners and military recruits. The diagnosis of such injuries can be challenging, often hampered by a nonspecific physical examination and limited sensitivity of plain radiography. Early recognition is important to direct appropriate management, lessen time lost from sport, and avoid potential complications. The present article reviews the epidemiology, diagnosis, and management of bone stress injuries of the hip and pelvis, specifically the sacrum, pubic ramus, and femoral neck.

Synovial Inclusion Cyst Mimicking a Femoral Neck Stress Fracture in an Active Duty Servicemember: A Case Report

CASE

A 19-year-old female servicemember with history of ischiopubic rami stress fractures was referred to orthopaedic surgery for magnetic resonance imaging findings concerning for a tension-sided femoral neck stress fracture. However, her history and symptoms were discordant with the diagnosis of stress fracture. The patient was managed with protected weight-bearing for 6 weeks with gradual return to physical activity.

CONCLUSION

Prophylactic surgical fixation is advocated for the management of tension-sided femoral neck stress fractures. However, surgeons should consider a broader differential diagnosis, to include a synovial inclusion cyst, when the clinical presentation is not consistent with a stress fracture.

Bilateral Atypical Tension-sided Femoral Neck Stress Fractures in a Military Recruit

A case report of a Marine Recruit with bilateral atypical tensile-sided femoral neck stress fracture. The patient was treated nonoperatively with protected weightbearing following an established protocol that included close observation with serial exams and advanced imaging. He recovered uneventfully and was able to return to running. He was eventually diagnosed with bilateral femoral acetabular impingement syndrome at the end of his treatment course demonstrating a growing association warranting further investigation.

Epidemiology of proximal femoral fractures

INTRODUCTION

With increasing age, the incidence of proximal femoral fractures increases steadily. Although the different treatments are investigated frequently, little is known about the seasonal variation and predisposing factors. The purpose of this study is to investigate the epidemiology, the impact of femoroacetabular impingement, as well as the presence of osteoarthritis.

METHODS

We performed a retrospective review of all patients with pertrochanteric, lateral and medial femoral neck fractures between 2012 and 2019. Inclusion criteria consisted of patients older than 18 years old who presented with isolated proximal femoral fractures without any congenital or hereditary deformity. For analysis, we assessed the demographics, season at time of accident, Kellgren-Lawrence score and corner edge (CE) angle.

RESULTS

In total, 187 patients were identified at a mean age of 75.1 ± 12.9 years old. Females consisted of 54.5% of this cohort. Most commonly, patients tend to present in winter with pertrochanteric fractures whereas no seasonal variation was found for medial femoral neck fractures. Significant correlations between season and age (regression coefficient -0.050 ± 0.021; p < 0.05) were identified. In medial neck fractures, the Gardner score was lower and Kellgren-Lawrence score higher for both female than males (p < 0.05). Patients with lateral neck fractures were significantly younger at 68.6 ± 12.5 years old (p < 0.05). In pertrochanteric fractures, the Kellgren-Lawrence score was significantly higher at 2.1 ± 0.8 (p < 0.05) with higher CE angle at 43.0 ± 7.6° (p = 0.14).

CONCLUSION

With increasing incidences of proximal femoral fractures, it is essential to recognize potential risk factors. This allows for development of new guidelines and algorithm that can aid in diagnosis, prevention, and education for patients.

Outcomes Following the Urgent Surgical Management of Displaced Femoral Neck Stress Fractures

OBJECTIVES

To review the clinical course, complication rates, and mid-term functional outcomes associated with the treatment of displaced femoral neck stress fractures (FNSFs).

DESIGN

Retrospective Case Series.

SETTING

Military Tertiary Referral Center.

PATIENTS

Twenty-one operatively treated displaced FNSFs between 2002 and 2015.

INTERVENTION

Urgent reduction and fixation was performed. If nonunion developed, an intertrochanteric osteotomy was performed.

MAIN OUTCOME MEASUREMENTS

Nonunion, osteonecrosis (ON) of the femoral head, conversion to arthroplasty, modified Harris Hip Score, pain score, and Hip Outcome Score (HOS).

RESULTS

Two (9.1%) patients developed nonunion. Both united after revision with intertrochanteric osteotomy. ON developed in one patient (4.8%) who was converted to arthroplasty. Average pain score at final follow-up was 2.0 (range 0-5). Average Modified Harris Hip Score was 84 (range 54-100). Average HOS Activities of Daily Living subscale was 80.9 (range 45.6-100). Average HOS Sport subscale was 69.8 (range 27.8-100). Larger displacement on injury films correlated with lower Modified Harris Hip Scores (P = 0.048) and lower HOS Sports Subscale Single Assessment Numeric Evaluation (P = 0.023). The need for an open reduction trended toward being a risk factor for nonunion (P = 0.081).

CONCLUSIONS

This study represents the largest series of patients undergoing urgent surgery for displaced FNSFs. Nonunion and ON is found at a similar rate to what is reported in the young traumatic literature. Pain and outcome scores compare favorably to other hip pathology in young adults. Initial injury severity is variably correlated to final outcome scores.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Bilateral spontaneous simultaneous femoral neck occult fracture in a middle-aged man due to osteoporosis and vitamin D deficiency osteomalacia: A case report and literature review

•

Physicians should take spontaneous femoral neck occult fracture into consideration if they report groin pain or difficulty in walking, even when findings from plain X-ray are normal.

•

In a patient with spontaneous femoral neck occult fracture, diagnosing and treating the underlying etiology of osteoporosis and osteomalacia are essential for improving prognosis.

•

This is the first report of a case of bilateral spontaneous simultaneous occult fracture of the femoral neck caused by osteoporosis and osteomalacia in a middle aged man.

Introduction

Bilateral stress fracture of the femoral neck is very rarely seen in healthy young patients who are neither athletes nor military recruits.

Presentation of case

The present report describes a 51-year-old male patient, not an athlete and with no previous history of disease, who developed bilateral stress fracture of the femoral neck without displacement.

Discussion

Simultaneous bilateral femoral neck fracture is a rare injury. In the present case, two factors predisposed to bilateral occult fracture of the femoral neck. The first was osteoporosis due to the patient’s smoking and alcohol abuse. The second was vitamin D deficiency osteomalacia associated with inadequate sun exposure.

Conclusion

All patients who present with spontaneous hip pain should be evaluated for osteoporosis and osteomalacia and assessed for underlying occult fracture if they report groin pain or difficulty in walking, even when findings from plain X-ray are normal, to improve prognosis in this rare and serious condition.

Management and treatment of femoral neck stress fractures in recreational runners: a report of four cases and review of the literature

Femoral neck stress fractures (FNSFs) in healthy young subjects are uncommon and most prevalent among long-distance runners and military recruits. Women seem to be at higher risk of developing stress fractures because of possible eating disorders followed by amenorrhea and osteoporosis. This case report describes four young and middle-aged, active female recreational runners who developed stress fractures of the femoral neck. In three of them, with a clinical history of persistent pain in the groin region, which worsened during training, early diagnosis by MRI was considered essential in detecting the fractures. The patients were clinically, metabolically and radiographically evaluated; they were then treated and followed-up at our institution. Only one case was treated conservatively, while the others underwent surgical internal fixation using a screw-plate (DHS®). All of them returned to sport physical activity after a recovery period. Regarding the challenging management of FNSFs, our report highlights the importance of groin pain, especially in athletic females, an early diagnosis by MRI, and a proper classification of these injuries for a correct choice of treatment in order to prevent further dislocation and avoid avascular necrosis of the femoral head. (www.actabiomedica.it)

Management and treatment of femoral neck stress fractures in recreational runners: a report of four cases and review of the literature

Femoral neck stress fractures (FNSFs) in healthy young subjects are uncommon and most prevalent among long-distance runners and military recruits. Women seem to be at higher risk of developing stress fractures because of possible eating disorders followed by amenorrhea and osteoporosis. This case report describes four young and middle-aged, active female recreational runners who developed stress fractures of the femoral neck. In three of them, with a clinical history of persistent pain in the groin region, which worsened during training, early diagnosis by MRI was considered essential in detecting the fractures. The patients were clinically, metabolically and radiographically evaluated; they were then treated and followed-up at our institution. Only one case was treated conservatively, while the others underwent surgical internal fixation using a screw-plate (DHS®). All of them returned to sport physical activity after a recovery period. Regarding the challenging management of FNSFs, our report highlights the importance of groin pain, especially in athletic females, an early diagnosis by MRI, and a proper classification of these injuries for a correct choice of treatment in order to prevent further dislocation and avoid avascular necrosis of the femoral head.

Management and treatment of femoral neck stress fractures in recreational runners: a report of four cases and review of the literature

Femoral neck stress fractures (FNSFs) in healthy young subjects are uncommon and most prevalent among long-distance runners and military recruits. Women seem to be at higher risk of developing stress fractures because of possible eating disorders followed by amenorrhea and osteoporosis. This case report describes four young and middle-aged, active female recreational runners who developed stress fractures of the femoral neck. In three of them, with a clinical history of persistent pain in the groin region, which worsened during training, early diagnosis by MRI was considered essential in detecting the fractures. The patients were clinically, metabolically and radiographically evaluated; they were then treated and followed-up at our institution. Only one case was treated conservatively, while the others underwent surgical internal fixation using a screw-plate (DHS®). All of them returned to sport physical activity after a recovery period. Regarding the challenging management of FNSFs, our report highlights the importance of groin pain, especially in athletic females, an early diagnosis by MRI, and a proper classification of these injuries for a correct choice of treatment in order to prevent further dislocation and avoid avascular necrosis of the femoral head.

Femoral Neck Stress Fractures in Sport: A Current Concepts Review

Femoral neck stress fractures (FNSFs) account for 3% of all sport-related stress fractures. The commonest causative sports are marathon and long-distance running.

The main types of FNSF are compression-sided, tension-sided and displaced. The most common reported symptom is exercise-related groin pain. Radiographs form the first line of investigation, with MRI the second-line investigation.

The management of FNSFs is guided by the location and displacement of the fracture. Delay in diagnosis is common and increases the likelihood of fracture displacement. Sporting outcomes are considerably worse for displaced fractures. Education programmes and treatment protocols can reduce the rates of displaced FNSFs.

This article aims to provide a current concepts review on the topic of FNSFs in sport, assess the current evidence on the epidemiology and pathophysiology of these injuries, detail the current recommendations for their imaging and management, and review the recorded sporting outcomes for FNSFs in the existing literature.

From this study, we conclude that although FNSFs are a rare injury, they should be considered in all athletes presenting with exercise-related hip pain, because delay in diagnosis and subsequent fracture displacement can significantly impair future return to sport. However, when detected early, FNSFs show promising results in terms of return-to-sport rates and times.

Bilateral Femoral Neck Stress Fracture Presented with Unilateral Symptoms in a Shipman Laborer: A Case Report

Femoral neck stress fracture occured commonly in athlete and military recruit populations, some of them are bilateral. Bilateral femoral neck stress fracture that associated with other occupation is very uncommon. We report a bilateral femoral neck stress fracture case that presented with unilateral symptoms in a male shipman laborer. The patient was successfully treated conservatively. Stress fracture sometimes occur associated with an unexpected specific occupation. Consideration of bilateral involvement is highly important in managing stress fracture.

High-Risk Stress Fractures: Diagnosis and Management

Stress fractures are common overuse injuries in athletes. They occur during periods of increased training without adequate rest, disrupting normal bone reparative mechanisms. There are a host of intrinsic and extrinsic factors, including biochemical and biomechanical, that put athletes at risk. In most stress fractures, the diagnosis is primarily clinical, with imaging indicated at times, and management focused on symptom-free relative rest with advancement of activity as tolerated. Overall, stress fractures in athletes have an excellent prognosis for return to sport, with little risk of complication. There is a subset of injuries that have a greater risk of fracture progression, delayed healing, and nonunion and are generally more challenging to treat with nonoperative care. Specific locations of high-risk stress fracture include the femoral neck (tension side), patella, anterior tibia, medial malleolus, talus, tarsal navicular, proximal fifth metatarsal, and great toe sesamoids. These sites share a characteristic region of high tensile load and low blood flow. High-risk stress fractures require a more aggressive approach to evaluation, with imaging often necessary, to confirm early and accurate diagnosis and initiate immediate treatment. Treatment consists of nonweight-bearing immobilization, often with a prolonged period away from sport, and a more methodic and careful reintroduction to athletic activity. These stress fractures may require surgical intervention. A high index of suspicion is essential to avoid delayed diagnosis and optimize outcomes in this subset of stress fractures.

Bone Stress Injuries in Runners

Bone stress injuries (BSIs) are common running injuries and may occur at a rate of 20% annually. Both biological and biomechanical risk factors contribute to BSI. Evaluation of a runner with suspected BSI includes completing an appropriate history and physical examination. MRI grading classification for BSI has been proposed and may guide return to play. Management includes activity modification, optimizing nutrition, and addressing risk factors, including the female athlete triad. BSI prevention strategies include screening for risk factors during preparticipation evaluations, optimizing nutrition (including adequate caloric intake, calcium, and vitamin D), and promoting ball sports during childhood and adolescence.

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.