Femoroacetabular impingement as a factor in the development of nonunion of the femoral neck: a report of three cases

Persistent femoral neck non-union despite valgus intertrochanteric osteotomy: Relevance for secondary cam-type impingement

Valgus intertrochanteric osteotomy is a well-established treatment in delayed union of femoral neck fractures as it converts shear forces into compression forces. Non-union of the femoral neck fracture may persist following valgus intertrochanteric osteotomy, and secondary femoroacetabular impingement (FAI) may be a contributing factor.

Case

We report one case of persistent femoral neck non-union after treatment by valgus intertrochanteric osteotomy with concomitant secondary cam-type impingement from fracture callus as a possible cause for ongoing insufficient healing. Healing was achieved following surgical hip dislocation with corrective osteochondroplasty of the femoral head-neck junction. Two-year follow-up shows good clinical and radiological outcomes.

Conclusion

In ongoing non-healing of femoral neck fractures following valgus intertrochanteric osteotomy, secondary cam impingement from fracture callus must be excluded.

Low-dose prophylaxis protocol for heterotopic ossification after hip preservation surgery in a sport participants cohort

BACKGROUND

Heterotopic ossification (HO) is a well-known complication of arthroscopic and open surgical treatment of femoroacetabular impingement (FAI). Incidence of heterotopic ossification has been reported in the literature between 0% and 44% after hip arthroscopy and between 18.2% and 25% after anterior mini-open surgery. Currently, pharmacological prophylaxis with NSAIDs and selective COX-2 inhibitors are commonly used and their effectiveness is well documented in literature.

HYPOTHESIS

We hypothesized that the low-dose prophylaxis protocol with selective cox-2 inhibitors decreases the risk of heterotopic ossification in open or arthroscopic hip preservation surgery in athletes.

METHODS

This study is an analysis of prospectively gathered data on 98 sport participant patients who underwent arthroscopic or anterior mini-open treatment for FAI between April 2008 and April 2018. All the patients received postoperative oral prophylaxis with 60 mg etoricoxib once daily for two weeks. Post-operative X-rays were performed at 1, 3, and 12 months after surgery and reviewed by two orthopedic surgeons blinded to the type and side of surgery. HO were graded according to the Brooker classification. Descriptive statistics was used to analyze demographic data. Bivariate analysis was performed to analyze the association of HO with each of the following variables: type of surgery, physical activity, time of evolution of symptoms, age at surgery, and sex. Finally, a regression model analysis was performed to determine the presence of confounding effects between variables.

RESULTS

The study cohort was composed of 54 patients in the arthroscopic treatment group and 44 patients in the anterior mini-open group. HO was identified in 6 (13.6%) patients in the mini-open group. No HO was identified in the arthroscopic group. In the bivariate analysis, "type of surgery" was the only variable that showed a statistically significant association with HO (p = 0.007).

CONCLUSION

Results of this study suggest that anterior mini-open treatment was characterized by a higher risk of HO development compared to hip arthroscopy for femoroacetabular impingement treatment regardless of pharmacological prophylaxis. The treatment regimen of 60 mg etoricoxib daily for two weeks was an effective prophylaxis for HO formation in sport participant patients compared with data available in the literature.

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.

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.

Pauwels Osteotomy for Femoral Neck Nonunion in Two Adult Siblings with Osteogenesis Imperfecta

This is a retrospective review of two adult siblings with osteogenesis imperfecta (OI) type III (according to Sillence classification), who sustained a spontaneous femoral neck fracture and subsequent nonunion. The diagnosis of OI in these two patients was made based on clinical, radiological and genetic findings. The fracture was most likely caused by femoroacetabular impingement secondary to OI induced acetabular protrusio. A valgus osteotomy according to Pauwels'principles and fixation of the osteotomy and nonunion with a locking plate resulted in healing despite compromised bone quality and limited bone stock. Long-term follow up (4.5 years and 6.5 years, respectively) is provided.

When treating this difficult problem, improving the mechanobiological environment and decreasing the femoroacetabular impingement by a Pauwels type osteotomy should be considered.

Femoroacetabular impingement inducing non-union of a femoral neck fracture: a case report

INTRODUCTION

We describe a case in which femoroacetabular impingement (FAI) was identified as the cause of non-union of a femoral neck fracture and the subsequent treatment strategy.

MATERIALS AND METHODS

Retrospective review of a 35-year-old patient, without any risk factors for non-union, who sustained a femoral neck fracture. Pre-existing FAI was identified as the cause for the non-union of the femoral neck fracture, with successful treatment of the non-union according to established arthroscopic treatment of the hip.

RESULTS

After treatment of the FAI, the non-union healed uneventfully within 3 months.

CONCLUSIONS

FAI may be a less common but potential cause of delayed union or non-union in the setting of femoral neck fracture in the young.

Femoral Neck Stress Fractures and Imaging Features of Femoroacetabular Impingement

BACKGROUND

Prior literature has suggested an association between the radiographic signs of femoroacetabular impingement (FAI) and femoral neck stress fractures (FNSF) or femoral neck stress reactions (FNSR). At the time of the writing of this article, no study has described the association of FAI and FNSF/FNSR along with the need for surgical intervention and outcomes.

OBJECTIVE

To determine the prevalence of radiographic features of FAI in patients diagnosed with FNSF.

DESIGN

Retrospective case series.

SETTING

Tertiary care, institutional setting.

PATIENTS

A medical records search program (Stanford Translational Research Integrated Database Environment, Stanford University, California) was used to retrospectively search for patients 18-40 years old with a history of FNSF or FNSR. The records were obtained from the period July 25, 2003, to September 23, 2011.

METHODS

For assessment of risk factors, plain radiographs and magnetic resonance imaging studies were reviewed for features of cam or pincer FAI. Medical records were reviewed to determine whether patients required operative intervention.

MAIN OUTCOME MEASURES

Incidence of abnormal alpha (α) angle, abnormal anterior offset ratio, abnormal femoral head-neck junction, coxa profunda, positive crossover sign, and abnormal lateral center-to-edge angle.

RESULTS

Twenty-one female and 3 male participants (mean age 27 years, range 19-39 years) were identified with magnetic resonance imaging evidence of femoral neck stress injury. Cam morphology was seen in 10 patients (42%). Pincer morphology could be assessed in 18 patients, with coxa profunda in 14 (78%) and acetabular retroversion in 6 (14%). Features of combined pincer and cam impingement were observed in 4 patients (17%). Seven patients (29%) had operative intervention, with 3 (12%) requiring internal fixation of their femoral neck fractures, and all had radiographic evidence of fracture union after surgery. Four patients (17%) had persistent symptoms after healing of their FNSF with conservative treatment and eventually required surgery for FAI, 3 had no pain at final follow-up 1 year post-surgery, and one patient was lost to follow-up.

CONCLUSION

The results of the current study suggest that patients in the general population with femoral neck stress injuries have a higher incidence of bony abnormalities associated with pincer impingement, including coxa profunda and acetabular retroversion, although it is unclear whether pincer FAI is a true risk factor in the development of FNSF.

The evolution and concepts of joint-preserving surgery of the hip

The use of joint-preserving surgery of the hip has been largely abandoned since the introduction of total hip replacement. However, with the modification of such techniques as pelvic osteotomy, and the introduction of intracapsular procedures such as surgical hip dislocation and arthroscopy, previously unexpected options for the surgical treatment of sequelae of childhood conditions, including developmental dysplasia of the hip, slipped upper femoral epiphysis and Perthes’ disease, have become available. Moreover, femoroacetabular impingement has been identified as a significant aetiological factor in the development of osteoarthritis in many hips previously considered to suffer from primary osteoarthritis.

As mechanical causes of degenerative joint disease are now recognised earlier in the disease process, these techniques may be used to decelerate or even prevent progression to osteoarthritis. We review the recent development of these concepts and the associated surgical techniques.

Cite this article: Bone Joint J 2014;96-B:5–18.

Femoroacetabular impingement: current concepts and controversies

The concept of femoroacetabular impingement (FAI) emerged following the observation that FAI can be precipitated by acetabular reorientation and can produce new labral damage. Interest in the association between chondrolabral damage and variations in femoral and acetabular anatomy has established a causal relationship between mechanical aberration in the function of the hip joint and the development of labral and cartilage damage. The accepted definition of FAI is that it is characterized by abnormal mechanical contact between the rim of the acetabulum and the upper femur. Combinations of certain morphologies and movements may lead to FAI.

Symptomatic femoroacetabular impingement: does the offset decrease correlate with cartilage damage? A pilot study

BACKGROUND

Current measures of the reduced head-neck offset such as residual deformity of slipped capital femoral epiphysis (SCFE) including the alpha angle, which measures the femoral head-neck sphericity but does not account for acetabular abnormalities, do not represent the true magnitude of the deformity and the mechanical consequences. The beta angle (angle between the femoral head-neck junction and acetabular rim) accounts for the morphology of both the acetabulum and femur and, thus, may be the more appropriate parameter for assessing SCFE deformity.

QUESTIONS/PURPOSES

We determined (1) whether the beta angle could be reliably measured on MRI; and (2) whether the beta angle correlates with the cartilage status.

METHODS

We recruited 10 adult patients (mean age, 28 years) with symptomatic cam femoroacetabular impingement and 15 asymptomatic volunteers (mean age, 24 years) to have three-dimensional MRI including delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) for cartilage status assessment. Corresponding alpha angles, beta angles, and acetabular dGEMRIC indices were obtained in seven radial reformats to assess the hip in seven regions (anterior to superior and posterior).

RESULTS

We noted high reproducibility for both alpha and beta angle measurements. The dGEMRIC indices correlated with beta angles in the superoinferior and superior regions but not the alpha angles.

CONCLUSIONS

Beta angle measurement in radial MR images is reproducible and appears to correspond to cartilage damage in the superior regions of the hip. The beta angle may be a useful parameter to assess hip deformity in the followup of SCFE although further confirmation is warranted.

Femoroacetabular impingement

Femoroacetabular impingement (FAI) is a common cause of early-onset osteoarthritis of the hip. It can be caused by morphologic abnormalities involving the proximal femur or acetabulum, leading to abnormal abutment of the femoral head-neck against the acetabular rim. This repetitive trauma causes mechanical wear of the labrum and articular cartilage, leading to osteoarthritis of the hip. Magnetic resonance imaging is an accurate noninvasive imaging modality that can detect acetabular labral lesions and adjacent cartilage damage, and is able to detect underlying subtle anatomic variations of the femoral head-neck junction and acetabulum associated with FAI.

Evaluation the treatment outcomes of intracapsular femoral neck fractures with closed or open reduction and internal fixation by screw in 18-50-year-old patients in Isfahan from Nov 2010 to Nov 2011

BACKGROUND

There is conflict of interest in the treatment of intracapsular femoral neck fractures and the outcomes. The aim of this study was evaluation the treatment outcomes of closed and open reduction and internal fixation with screw in 18-50-year-old patients.

MATERIALS AND METHODS

This clinical randomized study was conducted in Ayatollah Kashani Center in Isfahan from Nov 2010 to Nov 2011. In 42 patients selected in a randomized manner, fractures were reduced by closed reduction or open if necessary and C-ARM was controlled in AP and lateral plans. Movement range and femur pain severity were evaluated according to Visual analogue Scale (VAS) score at 3 and 6 months after surgery. Data were analyzed by SPSS 18. Chi-square, t-test, one-way analysis of variance (ANOVA), and descriptive statistics such as frequency distribution, mean, and mean deviation were used.

RESULTS

Forty-two patients with femoral neck fracture were treated by open [31 patients (73.8%)] or closed reduction [11 patients (26.2%)] and also osteosynthesis. Their mean age was 47.3 ± 9.8 years; 29 of them were males and 13 were females. Twelve patients had bad range of motion (ROM) (28.6%), 16 had intermediate ROM (38%), and 14 had good ROM (33.4%). After 6 months, 12 patients (28.6%) had bad ROM, 10 (23.8%) had intermediate ROM, and 20 (47.6%) had good ROM. There were 11 cases of non-union (35.5%) in the open reduction group and 4 in the closed group.

CONCLUSION

This study showed that femoral neck fracture is associated with several complications, especially if open reduction was necessary. So, the surgical method and necessary equipments such as radiolucent bed, C-ARM machine, and implant cannulated screw set should be considered.

Low early failure rates using a surgical dislocation approach in healed Legg-Calvé-Perthes disease

BACKGROUND

Hip deformity secondary to Legg-Calvé Perthes disease (LCPD) may result in femoroacetabular impingement (FAI) and ultimately osteoarthritis. Observations made with the surgical hip dislocation approach have improved our understanding of the pathologic mechanics of FAI. However, owing to concerns about complications related to the vascularity, the role of surgical hip dislocation in the treatment of healed LCPD remains controversial.

QUESTIONS/PURPOSES

We present an algorithm to treat deformities associated with healed LCPD and asked (1) whether femoral head-neck osteochondroplasty and other procedures performed with the surgical hip dislocation approach provide short-term clinical improvement; and (2) is the complication rate low enough to be acceptable.

METHODS

We retrospectively reviewed 29 patients (19 males, 10 females; mean age, 17 years; range, 9-35 years) with symptomatic LCPD between 2001 and 2009. All patients underwent a surgical hip dislocation approach and femoral head-neck osteochondroplasty and 26 patients had 37 additional procedures performed. Clinical improvement was assessed using the WOMAC index. The minimum followup was 12 months (mean, 3 years; range, 12-70 months).

RESULTS

WOMAC scores improved at final followup (8 to 4 for pain, 21 to 13 for function, and 4 to 2 for the stiffness subscales). No patients had osteonecrosis, implant failure, deep infection, or nonunion. Three patients underwent THA at 1, 3, and 6 years after their index procedure.

CONCLUSIONS

Using the surgical hip dislocation approach as a tool to dynamically inspect the hip for causes of FAI, we were able to perform a variety of procedures to treat the complex deformities of healed LCPD. In the short term, we found improvement in WOMAC scores with a low complication rate.

Current controversies in hip surgery

An international faculty of orthopaedic surgeons presented their work on the current challenges in hip surgery at the London Hip Meeting which was attended by over 400 delegates. The topics covered included femoroacetabular impingement, thromboembolic phenomena associated with hip surgery, bearing surfaces (including metal-on-metal articulations), outcomes of hip replacement surgery and revision hip replacement. We present a concise report of the current opinions on hip surgery from this meeting with appropriate references to the current literature.

Surgery for femoroacetabular impingement using a minimally invasive anterolateral approach: analysis of 118 cases at 2.2-year follow-up

INTRODUCTION

Treatment of femoroacetabular impingement (FAI) has progressed over time from using long incisions and dislocation to using arthroscopic surgery. Minimally invasive treatment has rarely been evaluated and a minimally invasive, anterolateral approach has not been used up to now for this indication. A prospective, on-going study was performed to evaluate surgical treatment of FAI with a minimally invasive, anterolateral approach.

HYPOTHESIS

Femoral neck, acetabulum and labrum abnormalities can be corrected without significant morbidity using a minimally invasive, anterolateral approach without dislocation.

PATIENTS AND METHODS

Treatment of 120 FAI cases (108 patients, 16 women, 92 men, 12 bilateral cases during one surgical session), average age: 34 years (18.9-63.5 years), was done prospectively and in an uninterrupted series. Two cases were lost to follow-up; 106 patients (118 FAI cases) were evaluated with a follow-up of at least 1 year. Assessments consisted of the Non-Arthritic Hip Score (NAHS), WOMAC, measurement of internal rotation with 90° flexion and the Nötzli alpha angle on an A/P radiograph in 45° of flexion, 45° abduction and 30° external rotation.

RESULTS

Blood loss averaged 1.2g/dl (range 0.5 to 2.7g/dl) and the average operative time was 44.9 minutes (range 30 to 65). With an average follow-up of 2.2 years (range 12 to 54 months), the NAHS changed by 32.5 points (P<0.0001), internal rotation by 19.0° (P<0.0001) and the alpha angle by -24.9° (P<0.0001). Eight surgical revisions were required (6.8%) (four haematomas, two capsular debridement, two additional procedures on the acetabulum) and these had a good outcome; there were no nerve-related or infection-related complications. Four failures (3.5%) were revised by arthroplasty (two patients experienced residual pain and two patients rapidly progressed to osteoarthritis). Eighteen cases progressed by only one Tönnis stage. Brooker stage II and III ossification were observed in 12 cases (10.2%) but these did not affect the functional score and range of motion improvement.

DISCUSSION

This approach, which can be learned and performed quickly, does not require any specific materials and yields a reliable surgical procedure without major complications. This short-term study, where the central cartilaginous compartment was not explored and the labrum was not sutured, comprised a consecutive, non-selected series of patients (independent of age, weight, osteoarthritis stage) and had encouraging results.

LEVEL OF EVIDENCE

Level III, prospective study, no control group.

MR imaging of early hip joint degeneration

MR imaging is one of the most commonly used imaging techniques to evaluate patients with hip pain. Intra-articular abnormalities of the hip joint are better assessed with recent advances in MR imaging technology, such as high-field strength scanners, improved coils, and more signal-to-noise ratio-efficient sequences. This article discusses the causes of early hip joint degeneration and the current use of morphologic and physiologic MR imaging techniques for evaluating the articular cartilage of the hip joint. The article also discusses the role of MR arthrography in clinical cartilage imaging.

Preoperative and postoperative lower-extremity joint and pelvic kinematics during maximal squatting of patients with cam femoro-acetabular impingement

BACKGROUND

Understanding how the function of the lower extremity joints during everyday movements following surgery to treat cam femoro-acetabular impingement is essential to assess whether surgical intervention effectively restores the normal biomechanics of the hip. The purpose of this study was to compare preoperative and postoperative lower-extremity joint and pelvic angular displacements during maximal depth squatting of patients with unilateral symptomatic cam femoro-acetabular impingement.

METHODS

Ten participants were compared with respect to their preoperative and postoperative test results. The participants were between eighteen and fifty years of age and had a positive impingement test and visible cam deformity on anteroposterior and Dunn view radiographs. Postoperative testing for each participant occurred between eight and thirty-two months following surgical intervention. Three-dimensional lower-limb joint and pelvic kinematics of participants were collected during maximal depth squats.

RESULTS

Postoperatively, participants squatted to a greater mean maximal depth than they did preoperatively. Postoperative knee flexion and ankle dorsiflexion angles of the affected extremity at maximal depth were significantly greater than preoperative values. The postoperative sum of all joint angles of the affected limb at maximal squat depth was significantly larger than the preoperative sum. No significant differences were detected between the preoperative and postoperative measurements of the patients with cam impingement with respect to the kinematics of the affected hip at maximal squat depth, the pelvic angular displacements at maximal squat depth, or the overall pelvic range of motion during maximal deep squatting (p > 0.05).

CONCLUSIONS

The squat performance improved postoperatively, likely because of the combined effects of increased knee and ankle angles as well as a greater acetabular opening and thus reduced anterior femoral head coverage, allowing increased posterior pelvic pitch during the descent phase of the squat.

LEVEL OF EVIDENCE

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

Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC), after slipped capital femoral epiphysis

OBJECTIVE

The aim of this study was to assess the glycosaminoglycan (GAG) content in hip joint cartilage in mature hips with a history of slipped capital femoral epiphysis (SCFE) using delayed gadolinium-enhanced MRI of cartilage (dGEMRIC).

METHODS

28 young-adult subjects (32 hips) with a mean age of 23.8 ± 4.0 years (range: 18.1-30.5 years) who were treated for mild or moderate SCFE in adolescence were included into the study. Hip function and clinical symptoms were evaluated with the Harris hip score (HHS) system at the time of MRI. Plain radiographic evaluation included Tonnis grading, measurement of the minimal joint space width (JSW) and alpha-angle measurement. The alpha-angle values were used to classify three sub-groups: group 1=subjects with normal femoral head-neck offset (alpha-angle <50°), group 2=subjects with mild offset decrease (alpha-angle 50°-60°), and group 3=subjects with severe offset decrease (alpha-angle >60°).

RESULTS

There was statistically significant difference noted for the T1(Gd) values, lateral and central, between group 1 and group 3 (p-values=0.038 and 0.041). The T1(Gd) values measured within the lateral portion were slightly lower compared with the T1(Gd) values measured within the central portion that was at a statistically significance level (p-value <0.001). HHS, Tonnis grades and JSW revealed no statistically significant difference.

CONCLUSION

By using dGEMRIC in the mid-term follow-up of SCFE we were able to reveal degenerative changes even in the absence of joint space narrowing that seem to be related to the degree of offset pathology. The dGEMRIC technique may be a potential diagnostic modality in the follow-up evaluation of SCFE.

Acetabular retroversion in military recruits with femoral neck stress fractures

Acetabular retroversion (AR) alters load distribution across the hip and is more prevalent in pathologic conditions involving the hip. We hypothesized the abnormal orientation and mechanical changes may predispose certain individuals to stress injuries of the femoral neck. We retrospectively reviewed the anteroposterior (AP) pelvic radiographs of 54 patients (108 hips) treated for a femoral neck stress fracture (FNSF) and compared these radiographs with those for a control group of patients with normal pelvic radiographs. We determined presence of a crossover sign (COS), femoral neck abnormalities, and neck shaft angle. The prevalence of a positive COS was greater in patients with stress fractures than in the control subjects (31 of 54 [57%] versus 17 of 54 [31%], respectively) and higher than for control subjects reported in the literature. Thirteen patients had radiographic changes of the femoral neck consistent with femoroacetabular impingement (FAI). These radiographic abnormalities were seen more commonly in retroverted hips. A greater incidence of AR was noted in patients with FNSF. Potential implications include more aggressive screening of military recruits with AR and the new onset of hip pain. Finally, we present an algorithm we use to diagnose and treat these relatively rare FNSFs.

LEVEL OF EVIDENCE

Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

The etiology of osteoarthritis of the hip: an integrated mechanical concept

The etiology of osteoarthritis of the hip has long been considered secondary (eg, to congenital or developmental deformities) or primary (presuming some underlying abnormality of articular cartilage). Recent information supports a hypothesis that so-called primary osteoarthritis is also secondary to subtle developmental abnormalities and the mechanism in these cases is femoroacetabular impingement rather than excessive contact stress. The most frequent location for femoroacetabular impingement is the anterosuperior rim area and the most critical motion is internal rotation of the hip in 90 degrees flexion. Two types of femoroacetabular impingement have been identified. Cam-type femoroacetabular impingement, more prevalent in young male patients, is caused by an offset pathomorphology between head and neck and produces an outside-in delamination of the acetabulum. Pincer-type femoroacetabular impingement, more prevalent in middle-aged women, is produced by a more linear impact between a local (retroversion of the acetabulum) or general overcoverage (coxa profunda/protrusio) of the acetabulum. The damage pattern is more restricted to the rim and the process of joint degeneration is slower. Most hips, however, show a mixed femoroacetabular impingement pattern with cam predominance. Surgical attempts to restore normal anatomy to avoid femoroacetabular impingement should be performed in the early stage before major cartilage damage is present.

LEVEL OF EVIDENCE

Level V, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Treatment of femoro-acetabular impingement: preliminary results of labral refixation. Surgical technique

BACKGROUND

Recent advances in the understanding of the anatomy and function of the acetabular labrum suggest that it is important for normal joint function. We found no available data regarding whether labral refixation after treatment of femoro-acetabular impingement affects the clinical and radiographic results.

METHODS

We retrospectively reviewed the clinical and radiographic results of fifty-two patients (sixty hips) with femoro-acetabular impingement who underwent arthrotomy and surgical dislocation of the hip to allow trimming of the acetabular rim and femoral osteochondroplasty. In the first twenty-five hips, the torn labrum was resected (Group 1); in the next thirty-five hips, the intact portion of the labrum was reattached to the acetabular rim (Group 2). At one and two years postoperatively, the Merle d'Aubigné clinical score and the Tönnis arthrosis classification system were used to compare the two groups.

RESULTS

At one year postoperatively, both groups showed a significant improvement in their clinical scores (mainly pain reduction) compared with their preoperative values (p = 0.0003 for Group 1 and p < 0.0001 for Group 2). At two years postoperatively, 28% of the hips in Group 1 (labral resection) had an excellent result, 48% had a good result, 20% had a moderate result, and 4% had a poor result. In contrast, in Group 2 (labral reattachment), 80% of the hips had an excellent result, 14% had a good result, and 6% had a moderate result. Comparison of the clinical scores between the two groups revealed significantly better outcomes for Group 2 at one year (p = 0.0001) and at two years (p = 0.01). Radiographic signs of osteoarthritis were significantly more prevalent in Group 1 than in Group 2 at one year (p = 0.02) and at two years (p = 0.009).

CONCLUSIONS

Patients treated with labral refixation recovered earlier and had superior clinical and radiographic results when compared with patients who had undergone resection of a torn labrum. Although the results must be considered preliminary, we now recommend refixation of the intact portion of the labrum after trimming of the acetabular rim during surgical treatment of femoro-acetabular impingement.

Treatment of femoro-acetabular impingement: preliminary results of labral refixation

BACKGROUND

Recent advances in the understanding of the anatomy and function of the acetabular labrum suggest that it is important for normal joint function. We found no available data regarding whether labral refixation after treatment of femoro-acetabular impingement affects the clinical and radiographic results.

METHODS

We retrospectively reviewed the clinical and radiographic results of fifty-two patients (sixty hips) with femoro-acetabular impingement who underwent arthrotomy and surgical dislocation of the hip to allow trimming of the acetabular rim and femoral osteochondroplasty. In the first twenty-five hips, the torn labrum was resected (Group 1); in the next thirty-five hips, the intact portion of the labrum was reattached to the acetabular rim (Group 2). At one and two years postoperatively, the Merle d'Aubigné clinical score and the Tönnis arthrosis classification system were used to compare the two groups.

RESULTS

At one year postoperatively, both groups showed a significant improvement in their clinical scores (mainly pain reduction) compared with their preoperative values (p = 0.0003 for Group 1 and p < 0.0001 for Group 2). At two years postoperatively, 28% of the hips in Group 1 (labral resection) had an excellent result, 48% had a good result, 20% had a moderate result, and 4% had a poor result. In contrast, in Group 2 (labral reattachment), 80% of the hips had an excellent result, 14% had a good result, and 6% had a moderate result. Comparison of the clinical scores between the two groups revealed significantly better outcomes for Group 2 at one year (p = 0.0001) and at two years (p = 0.01). Radiographic signs of osteoarthritis were significantly more prevalent in Group 1 than in Group 2 at one year (p = 0.02) and at two years (p = 0.009).

CONCLUSIONS

Patients treated with labral refixation recovered earlier and had superior clinical and radiographic results when compared with patients who had undergone resection of a torn labrum. Although the results must be considered preliminary, we now recommend refixation of the intact portion of the labrum after trimming of the acetabular rim during surgical treatment of femoro-acetabular impingement.

MR imaging of femoroacetabular impingement

FAI is a common cause of OA of the hip. It can be caused by decreased offset of the femoral head and neck, resulting in abutment of the femoral neck against the acetabular rim (cam impingement) and abutment of this area into the well-constrained socket (pincer impingement)within normal range of motion [15]. This repetitive mechanical trauma to the hip joint causes mechanical wear of the labrum and articular cartilage; left untreated, it causes pain, labral tears, and chondral injuries leading to progressive OA of the hip. The identification of FAI as a cause of OA allows appropriate therapy early and thus delays or prevents end-stage arthritis.MR imaging and MR arthrography are accurate noninvasive imaging modalities able to demonstrate acetabular labral disease and adjacent cartilage damage as well as the subchondral cysts and synovial herniation pits associated with impingement. In addition, MR imaging is able to detect underlying subtle anatomic variations of the femoral head-neck junction and acetabulum associated with FAI.

[Anterior femoroacetabular impingement after healed femoral neck fractures]

OBJECTIVES

To describe anterior femoroacetabular Impingement (AFAI) as a cause of persistent painful loss of motion and progressive joint-destruction in patients with a healed femoral neck fracture, and to evaluate results after its surgical treatment.

METHODS

Eleven patients with groin pain elicited by motion and exertion following a healed femoral neck fracture were diagnosed clinically, by conventional radiographs and radial Arthro MRI with AFAI. During surgical subluxation or dislocation of the hip joint the impingement was visually verified and eliminated by re-shaping the anterior contour of the head-neck-junction.

RESULTS

All patients presented a flat contour of the anterior head-neck-junction causing a cam-type impingement with subsequent damage of the anterior-superior acetabular cartilage adjacent to the rim. These chondral changes result from the repetitive compression and shear forces between the flattened head-neck junction and the acetabular cartilage in flexion and internal rotation. At five year follow-up a clear improvement of the symptoms was observed without any signs of progressive joint destruction.

CONCLUSION

When chronic pain after a healed femoral neck fracture without necrosis of the femoral head occurs, the possibility of an AFAI caused by retrotorsion of the proximal fragment should be taken into consideration. The symptoms of AFAI can be relieved by surgical correction of the femoral head-neck-offset. The existing damage of the acetabular cartilage originated by the impingement at the time of surgery can hardly be improved. Therefore anatomical fracture reduction should be performed in order to prevent the development of osteoarthritis. Pre-existing deformities of the joint should be treated at the time of operative fracture treatment.