[Early damage to the acetabular cartilage in slipped capital femoral epiphysis. Therapeutic consequences]

Hip Impingement of severe SCFE patients after in situ pinning causes decreased flexion and forced external rotation in flexion on 3D-CT

Introduction

In situ pinning is an accepted treatment for stable slipped capital femoral epiphysis. However, residual deformity of severe slipped capital femoral epiphysis can cause femoroacetabular impingement and forced external rotation.

Purpose/questions

The aim of this study was to evaluate the (1) hip external rotation and internal rotation in flexion, (2) hip impingement location, and (3) impingement frequency in early flexion in severe slipped capital femoral epiphysis patients after in situ pinning using three-dimensional computed tomography.

Patients and methods

A retrospective Institutional Review Board-approved study evaluating 22 patients (26 hips) with severe slipped capital femoral epiphysis (slip angle > 60°) using postoperative three-dimensional computed tomography after in situ pinning was performed. Mean age at slipped capital femoral epiphysis diagnosis was 13 ± 2 years (58% male, four patients bilateral, 23% unstable, 85% chronic). Patients were compared to contralateral asymptomatic hips (15 hips) with unilateral slipped capital femoral epiphysis (control group). Pelvic three-dimensional computed tomography after in situ pinning was used to generate three-dimensional models. Specific software was used to determine range of motion and impingement location (equidistant method). And 22 hips (85%) underwent subsequent surgery.

Results

(1) Severe slipped capital femoral epiphysis patients had significantly (p < 0.001) decreased hip flexion (43 ± 40°) and internal rotation in 90° of flexion (-16 ± 21°, IRF-90°) compared to control group (122 ± 9° and 36 ± 11°). (2) Femoral impingement in maximal flexion was located anterior to anterior-superior (27% on 3 o'clock and 27% on 1 o'clock) of severe slipped capital femoral epiphysis patients and located anterior to anterior-inferior (38% on 3 o'clock and 35% on 4 o'clock) in IRF-90°. (3) However, 21 hips (81%) had flexion < 90° and 22 hips (85%) had < 10° of IRF-90° due to hip impingement and 21 hips (81%) had forced external rotation in 90° of flexion (< 0° of IRF-90°).

Conclusion

After in situ pinning, patient-specific three-dimensional models showed restricted flexion and IRF-90° and forced external rotation in 90° of flexion due to early hip impingement and residual deformity in most of the severe slipped capital femoral epiphysis patients. This could help to plan subsequent hip preservation surgery, such as hip arthroscopy or femoral (derotation) osteotomy.

Limited Hip Flexion and Internal Rotation Resulting From Early Hip Impingement Conflict on Anterior Metaphysis of Patients With Untreated Severe SCFE Using 3D Modelling

INTRODUCTION

Slipped capital femoral epiphysis (SCFE) is the most common hip disorder in adolescent patients that can result in complex 3 dimensional (3D)-deformity and hip preservation surgery (eg, in situ pinning or proximal femoral osteotomy) is often performed. But there is little information about location of impingement.Purpose/Questions: The purpose of this study was to evaluate (1) impingement-free hip flexion and internal rotation (IR), (2) frequency of impingement in early flexion (30 to 60 degrees), and (3) location of acetabular and femoral impingement in IR in 90 degrees of flexion (IRF-90 degrees) and in maximal flexion for patients with untreated severe SCFE using preoperative 3D-computed tomography (CT) for impingement simulation.

METHODS

A retrospective study involving 3D-CT scans of 18 patients (21 hips) with untreated severe SCFE (slip angle>60 degrees) was performed. Preoperative CT scans were used for bone segmentation of preoperative patient-specific 3D models. Three patients (15%) had bilateral SCFE. Mean age was 13±2 (10 to 16) years and 67% were male patients (86% unstable slip, 81% chronic slip). The contralateral hips of 15 patients with unilateral SCFE were evaluated (control group). Validated software was used for 3D impingement simulation (equidistant method).

RESULTS

(1) Impingement-free flexion (46±32 degrees) and IRF-90 degrees (-17±18 degrees) were significantly ( P <0.001) decreased in untreated severe SCFE patients compared with contralateral side (122±9 and 36±11 degrees).(2) Frequency of impingement was significantly ( P <0.001) higher in 30 and 60 degrees flexion (48% and 71%) of patients with severe SCFE compared with control group (0%).(3) Acetabular impingement conflict was located anterior-superior (SCFE patients), mostly 12 o'clock (50%) in IRF-90 degrees (70% on 2 o'clock for maximal flexion). Femoral impingement was located on anterior-superior to anterior-inferior femoral metaphysis (between 2 and 6 o'clock, 40% on 3 o'clock and 40% on 5 o'clock) in IRF-90 degrees and on anterior metaphysis (40% on 3 o'clock) in maximal flexion and frequency was significantly ( P <0.001) different compared with control group.

CONCLUSION

Severe SCFE patients have limited hip flexion and IR due to early hip impingement using patient-specific preoperative 3D models. Because of the large variety of hip motion, individual evaluation is recommended to plan the osseous correction for severe SCFE patients.

LEVEL OF EVIDENCE

Level III.

Patients With Symptomatic Sequelae of Slipped Capital Femoral Epiphysis Have Advanced Cartilage Wear at the Time of Surgical Intervention

BACKGROUND

Slipped capital femoral epiphysis (SCFE) is a common hip problem in children. The resulting deformity can cause impingement similar to cam-type idiopathic femoroacetabular impingement (FAI). Although there are similarities between FAI and SCFE, deformity patterns, severity, and time of onset of symptoms varies, which may impact management. The purpose of this study was to describe patterns of articular cartilage damage in patients undergoing surgical hip dislocation for sequelae of SCFE in comparison to patients undergoing arthroscopic surgery for primary FAI.

METHODS

Patients were identified who underwent surgical treatment for hip pain due to primary FAI (cam type) or sequelae of SCFE. Clinical data and radiographic measurements were recorded. Cartilage was assessed intraoperatively. Severity was classified using the modified Beck classification, while location was classified into 6 sectors. Statistical analysis was performed to test for differences in demographic and radiographic characteristics between the SCFE and FAI patients. χ2 or Fisher exact tests were used to evaluate trends in patterns of acetabular and femoral cartilage wear between SCFE and FAI groups.

RESULTS

The SCFE group had 28 hips compared with 304 in the FAI group. SCFE patients were younger (19 vs. 32, P<0.001), had higher body mass index (30±5.9 vs. 24±4.8, P<0.001), and were more often male (61% vs. 27%, P<0.001). Deformity severity based on α-angle was higher in the SCFE group [AP 74 vs. 55 (P=0.001) and Dunn 72 vs. 58 (P<0.001)]. There were no significant differences with regards to lateral center edge angle, anterior center edge angle, or Tonnis angle. In both groups the most common locations for cartilage lesions in both groups were the anterior peripheral and superolateral peripheral regions with fewer but more widely distributed femoral head lesions. The SCFE group had higher rates of femoral head and superolateral central cartilage lesions compared with the FAI group. There was no statistical difference between high-grade femoral or acetabular cartilage lesions between groups.

CONCLUSIONS

Patients with SCFE were younger at the time of surgery and presented with more severe deformity based on radiographic α-angle compared to patients with FAI. Our results suggest higher prevalence of femoral head lesions and more diffuse cartilage injury in patients with SCFE. This study can be used to support early surgical intervention in patients with symptomatic sequelae of SCFE due to risk of premature joint damage.

LEVEL OF EVIDENCE

Level III-prognostic study.

Surgical treatment of symptomatic post-slipped capital femoral epiphysis deformity: a comparative study between hip arthroscopy and surgical hip dislocation with or without intertrochanteric osteotomy

PURPOSE

Our primary research question was to investigate the severity of deformity and articular damage as well as outcomes in patients undergoing hip arthroscopy compared with open surgery for the treatment of symptomatic slipped capital femoral epiphysis (SCFE) deformity.

METHODS

Retrospective review of surgical treatment of symptomatic SCFE deformity with a minimum one-year follow-up. Patients were divided into three groups: the arthroscopic group, surgical hip dislocation(SHD) group and SHD with femoral osteotomy (SHD+ITO) group. Deformity severity was quantified. Hip outcome was assessed by the modified Merle d'Aubigné Postel (MDP) scores.

RESULTS

There were more severe slips treated by SHD and SHD+ITO. There was more severe deformity in the SHD+ITO group than the arthroscopy group (p < 0.001). There were more full thickness acetabular cartilage defects in the SHD and the SHD+ITO groups (> 40%) compared with the arthroscopy group (11%; p = 0.03). The SHD+ITO and SHD group had lower MDP scores compared with the arthroscopy group both before and after surgery but no difference was detected in the amount of improvement from surgery across groups (p > 0.05). Moderate and severe SCFEs had worse preoperative scores but improvement was not different compared with mild SCFEs (p > 0.05).

CONCLUSION

Patients undergoing open treatment had more severe SCFE deformity with more extensive articular damage at reconstructive surgery compared with patients undergoing arthroscopy. All groups with SCFE deformity had improved pain and hip function postoperatively.

LEVEL OF EVIDENCE

III.

Association between cam-type femoroacetabular impingement and osteitis pubis in non-athletic population on magnetic resonance imaging

BACKGROUND

Osteitis pubis (OP) is a common source of groin and extra-articular hip pain and is associated with intra-articular hip pathology. In this study, we aimed to determine the prevalence of osteitis pubis on magnetic resonance imaging (MRI) in non-athletic patients with cam-type femoroacetabular impingement (FAI).

METHODS

This retrospective cross-sectional study included 178 subjects: 90 patients with cam-type FAI diagnosed by MRI and 88 subjects used as a control group. Additionally, their MRI data were analyzed for the characteristics of osteitis pubis, with severity graded from minimal to severe on a four-point scale.

RESULTS

A total of 98 patients and 88 controls were studied. Seventy-two males (80%) and 18 females (20%) were the patient group, whereas 71 males (80.68%) and 17 females (19.32%) were the control group. The mean alpha angle of the patients with FAI was 65.8 ± 3.3° in the right side and 66.2 ± 3.2° in the left side, whereas in the control group, it was 47 ± 5.6° in the right side and 47.8 ± 5.2° in the left side. Alpha angle measurements were significantly higher in the patient group than the control group (p < 0.001). A statistically significant increase in the prevalence of osteitis pubis was found in patients with cam-type FAI (45.56%) compared to control subjects (5.68%) (p < 0.001).

CONCLUSIONS

This study demonstrated that the frequency of osteitis pubis was increased in non-athletic patients with FAI syndrome. Further studies are required to determine whether these findings reflect the clinical symptoms in patients with hip pain.

[The modified Dunn procedure to treat severe slipped capital femoral epiphysis]

The modified Dunn procedure enables restoration of the proximal femoral anatomy and normal hip function in patients with slipped capital femoral epiphysis (SCFE). Surgery is indicated in severe SCFE and in hips with a moderate slip angle and impaired function. To prevent further dislocation of the femoral head, the authors recommend non-weightbearing until surgery, since an accurate evaluation of slip stability is not possible in the clinical setting. Only a well-trained orthopedic surgeon with a high level of expertise in hip preservation surgery should perform this procedure. Precise knowledge of the vascular anatomy of the proximal femur is essential to perform successful surgery with low rates of complications such as avascular necrosis of the femoral head. Surgical hip dislocation with osteotomy of the greater trochanter is the approach used. After arthrotomy, stability of the physis is checked. To prevent rupture of the retinacular vessels in hips with an unstable physis, these heads are prophylactically pinned before dislocation out of the socket. Blood supply to the femoral head as well as intraarticular damage can be judged in the dislocated position of the femoral head. The retinacular flap preserves epiphyseal perfusion while the femoral head is dislocated from the femoral neck. Resection of posteromedial callous formation from the femoral neck as well as removal of the remaining physis from the femoral head prevent stress on the retinacular vessels after reduction of the femoral head (epiphysis) on the neck.

Body Mass Index Affects Proximal Femoral but Not Acetabular Morphology in Adolescents Without Hip Pathology

BACKGROUND

Increased mechanical load secondary to a large body mass index (BMI) may influence bone remodeling. The purpose of this study was to investigate whether BMI is associated with the morphology of the proximal part of the femur and the acetabulum in a cohort of adolescents without a history of hip disorders.

METHODS

We evaluated pelvic computed tomographic (CT) images in 128 adolescents with abdominal pain without a history of hip pathology. There were 44 male patients (34%) and the mean patient age (and standard deviation) was 15 ± 1.95 years. The alpha angle, head-neck offset, epiphysis tilt, epiphyseal angle, and epiphyseal extension were measured to assess femoral morphology. Measurements of acetabular morphology included lateral center-edge angle, acetabular Tönnis angle, and acetabular depth. BMI percentile, specific to age and sex according to Centers for Disease Control and Prevention growth charts, was recorded.

RESULTS

BMI percentile was associated with all measurements of femoral morphology. Each 1-unit increase in BMI percentile was associated with a mean 0.15° increase in alpha angle (p < 0.001) and with a mean 0.03-mm decrease in femoral head-neck offset (p < 0.001). On average, a 1-unit increase in BMI percentile was associated with a 0.0006-unit decrease in epiphyseal extension (p = 0.03), a 0.10° increase in epiphyseal angle (p < 0.001), and a 0.06° decrease in tilt angle (p = 0.02; more posteriorly tilted epiphysis). There was no detected effect of BMI percentile on acetabular morphology including lateral center-edge angle (p = 0.33), Tönnis angle (p = 0.35), and acetabular depth (p = 0.88).

CONCLUSIONS

Higher BMI percentile was associated with increased alpha angle, reduced head-neck offset and epiphyseal extension, and a more posteriorly tilted epiphysis with decreased tilt angle and increased epiphyseal angle. This morphology resembles a mild slipped capital femoral epiphysis deformity and may increase the shear stress across the growth plate, increasing the risk of slipped capital femoral epiphysis development in obese adolescents. BMI percentiles had no association with measurements of acetabular morphology. Further studies will help to clarify whether obese asymptomatic adolescents have higher prevalence of a subclinical slip deformity and whether this morphology increases the risk of slipped capital femoral epiphysis and femoroacetabular impingement development.

Fixation in slipped capital femoral epiphysis avoiding femoral-acetabular impingement

Background

The appropriate treatment in mild slipped capital femoral epiphysis (SCFE) should not only prevent further slipping of the epiphysis but also address potential femoroacetabular impingement by restoring the anatomy of the proximal femur. The aim of this study was to quantify length of the remodeling phase mediated by growth of the femoral neck, after treatment of SCFE with a screw designed to prevent premature closure of the physis and provide stability.

Methods

Between 2001 and 2011, 38 patients with unilateral mild SCFE were treated by fixation in situ using a modified screw which does not cause premature physeal arrest. Twenty-four patients were investigated for clinical and radiological evidence of femoroacetabular impingement immediately after surgery, at 6- and 12-month follow-ups. Statistical analysis was performed comparing measurements of neck length and the α angle of the affected and contralateral side.

Results

Mean α angle immediately after pinning was 56.2 ± 10.6° on the anteroposterior view and 91.4 ± 8.2° on the lateral view. These measurements significantly improved at 6 months post-op to 48.9 ± 5.4° on the anteroposterior view and 51.2 ± 6.5° on the lateral view (p < 0.0001). At 12 months from surgery, AP view α angle was 43.0 ± 2.8° (p < 0.0001) and lateral view was 44.2 ± 4.1° (p < 0.0001). We observed a similar growth rate and speed of the femoral neck of both the affected and unaffected sides during the first year of treatment. The clinical results in all patients were rated as excellent.

Conclusion

Our data supports the use of a surgical technique that allows residual growth of the femoral neck following mild SCFE and permits restoration of the anatomy of the proximal femur while avoiding development of femoroacetabular impingement following mild SCFE.

Imaging of impingement syndromes around the hip joint

Impingement syndromes are increasingly recognised as significant causes of hip pain and dysfunction. A broad spectrum of intraarticular and extraarticular conditions has been implicated in their pathophysiology. Physical examination is often inconclusive as clinical findings may be unclear or misleading, often simulating other disorders. With current improvements in imaging techniques and better understanding of hip impingement related pathomechanisms, these entities can be accurately diagnosed. In addition, preoperative imaging has allowed for targeted treatment planning. This article provides an overview of the various types of hip impingement, including femoroacetabular impingement, ischiofemoral impingement, snapping hip syndrome, greater trochanteric-pelvic and subspine impingement. Current literature data regarding their pathogenesis, clinical manifestation and imaging work-up are discussed.

Modified Dunn Procedure is Superior to In Situ Pinning for Short-term Clinical and Radiographic Improvement in Severe Stable SCFE

BACKGROUND

In situ pinning is the conventional treatment for a stable slipped capital femoral epiphysis (SCFE). However, with a severe stable SCFE the residual deformity may lead to femoroacetabular impingement and articular cartilage damage. A modified Dunn subcapital realignment procedure has been developed to allow for correction at the level of the deformity while preserving the blood supply to the femoral head.

QUESTIONS/PURPOSES

We compared children with severe stable SCFE treated with the modified Dunn procedure or in situ pinning in terms of (1) proximal femoral radiographic deformity; (2) Heyman and Herndon clinical outcome; (3) complication rate; and (4) number of reoperations performed after the initial procedure.

METHODS

In this nonmatched retrospective study, 15 patients treated with the modified Dunn procedure (between 2007 and 2012) and 15 treated with in situ pinning (between 2001 and 2009) for severe but stable SCFE were followed for a mean of 2.5 years (range, 1-6 years). During the period in question, the decision regarding which procedure to use was based on the on-call surgeon's discretion; six surgeons performed in situ pinning and three surgeons performed the modified Dunn procedure. A total of 15 other patients were treated for the same diagnosis during the study period but were lost to followup before 1 year; of those, 12 were in the in situ pinning group. Radiographs were reviewed to measure the AP and lateral alpha angles, femoral head-neck offset, and Southwick angle preoperatively and at the latest clinical visit. The Heyman and Herndon clinical outcome, complications, and subsequent hip surgeries were recorded.

RESULTS

At latest followup, the median AP alpha angle (52°, range 41°-59° versus 76°, interquartile range [IQR]: 68°-88°; p = 0.0017), median lateral alpha angle (44°, IQR: 40°-51° versus 87°, IQR: 74°-96°; p < 0.001), median head-neck offset (7 mm, IQR: 5-9 mm versus -5, IQR: -11 to -4 mm; p < 0.001), and median Southwick angle (16°, IQR: 6°-23° versus 58°, IQR: 47°-66°; p < 0.001) revealed better deformity correction with the modified Dunn procedure compared with in situ pinning. Nine patients had good or excellent results in the modified Dunn group compared with four of 15 in the in situ pinning group (p = 0.0343; odds ratio, 5.86; 95% CI, 1.13-40.43). With the numbers available, there were no differences in the numbers of complications in each group (five versus three complications in the in situ and modified Dunn groups, respectively; p = 0.66), but there were more reoperations in the in situ pinning group (three versus seven; p = 0.0230).

CONCLUSIONS

The modified Dunn procedure results in better morphologic features of the femur, a higher rate of good and excellent Heyman and Herndon clinical outcome, a lower reoperation rate, and a similar occurrence of complications when compared with in situ pinning for treatment of severe stable SCFE.

LEVEL OF EVIDENCE

Level III, therapeutic study.

The cam-type deformity--what is it: SCFE, osteophyte, or a new disease?

Cam-type deformity of the proximal femur is a risk factor for the development of cam-type femoroacetabular impingement and a prearthrotic condition of the hip. The etiology of cam-type deformity remains unclear. There are a number of causes of cam-type deformity including sequellae of slipped capital femoral epiphysis, Legg-Calvé-Perthes disease or Perthes-like deformities, postinfectious, and traumatic. However, the majority of cam-type deformities arise without any apparent preexisting hip disease. These "idiopathic" cam-type deformities likely represent a majority of cases, and show clear racial and sex differences, as well as developmental and genetic influences. Idiopathic cam-type deformity also seems to be a distinct entity from residual or silent slipped capital femoral epiphysis, as well as osteoarthritis-induced osteophytes. In this paper we examine the different pathogenetic aspects of the proximal femur that contribute to cam-type deformity and/or symptomatic cam-type femoroacetabular impingement.

Slipped capital femoral epiphysis: what's new?

Slipped capital femoral epiphysis (SCFE) is a common hip disorder among adolescents, whereby the epiphysis is displaced posteriorly and inferiorly to the metaphysis. Treatment modalities aim to stabilize the epiphysis, prevent further slippage, and avoid complications associated with long-term morbidity, such as osteonecrosis and chondrolysis. Controversy exists with SCFE regarding prophylactic fixation of the contralateral, painless, normal hip, the role of femoroacetabular impingement with SCFE, and whether in situ fixation is the best treatment method for SCFE. This article presents and discusses the latest diagnostic and treatment modalities for SCFE.

Slipped capital femoral epiphysis: prevalence, pathogenesis, and natural history

BACKGROUND

Obesity is a risk factor for developing slipped capital femoral epiphysis (SCFE). The long-term outcome after SCFE treatment depends on the severity of residual hip deformity and the occurrence of complications, mainly avascular necrosis (AVN). Femoroacetabular impingement (FAI) is associated with SCFE-related deformity and dysfunction in both short and long term.

QUESTIONS/PURPOSES

We examined obesity prevention, early diagnosis, reducing AVN and hip deformity as strategies to reduce SCFE prevalence, and the long-term outcomes after treatment.

METHODS

A search of the literature using the PubMed database for the key concepts SCFE and treatment, natural history, obesity, and prevalence identified 218, 15, 26, and 49 abstracts, respectively. WHERE ARE WE NOW?: A correlation between rising childhood obesity and increasing incidence of SCFE has been recently reported. Residual abnormal morphology of the proximal femur is currently believed to be the mechanical cause of FAI and early articular cartilage damage in SCFE. WHERE DO WE NEED TO GO?: Reducing the increasing prevalence rate of SCFE is important. Treatment of SCFE should aim to reduce AVN rates and residual deformities that lead to FAI to improve the long-term functional and clinical outcomes. HOW DO WE GET THERE?: Implementing public health policies to reduce childhood obesity should allow for SCFE prevalence to drop. Clinical trials will evaluate whether restoring the femoral head-neck offset to avoid FAI along with SCFE fixation allows for cartilage damage prevention and lower rates of osteoarthritis. The recently described surgical hip dislocation approach is a promising technique that allows anatomic reduction with potential lower AVN rates in the treatment of SCFE.

Imaging of sports-related hip and groin injuries

A normally functioning hip joint is imperative for athletes who use their lower extremities with running, jumping, or kicking activities. Sports-related injuries of the hip and groin are far less frequent than injuries to the more distal aspect of the extremity, accounting for less than 10% of lower extremity injuries. Despite the lower incidence, hip and groin injuries can lead to significant clinical and diagnostic challenges related to the complex anatomy and biomechanical considerations of this region. Loads up to 8 times normal body weight have been documented in the joint in common daily activities, such as jogging, with significantly greater force expected during competitive athletics. Additionally, treatment for hip and groin injuries can obviate the participation of medical and surgical specialties, with a multidisciplinary approach frequently required. Delay in diagnosis and triage of these injuries may cause loss of time from competition and, potentially, early onset of degenerative changes. Magnetic resonance imaging (MRI) of the hip has proven to be the gold standard for the diagnosis of sports-related hip and groin injuries in the setting of negative radiographs. With its exquisite soft tissue contrast, multiplanar capabilities, and lack of ionizing radiation, MRI is unmatched in the noninvasive diagnosis of intra-articular and extra-articular pathology, as well as intraosseous processes. This review focuses on MRI of common athletic injuries of the hip and groin, including acetabular labral tears, femoral acetabular impingement syndrome, muscle injuries around the hip and groin (including athletic pubalgia), and athletic osseous injuries.

The asymptomatic contralateral hip in unilateral slipped capital femoral epiphysis: morbidity of prophylactic fixation

Prophylactic contralateral fixation in unilateral slipped capital femoral epiphysis (SCFE) remains a controversial issue. In this study, 66 patients treated for unilateral SCFE (July 1997-April 2009) were screened for complications with need for surgical reintervention in the asymptomatic contralateral hip. Except for one patient, prophylactic fixation was performed in all cases. Major complications such as avascular necrosis were not seen; minor complications such as wound revision occurred in 4.6% (three of 65). In 16.9% (11/65) secondary loss of fixation with need for second fixation occurred. As the need for second fixation arose mostly bilaterally (10.7%, 7/65), only four patients (6.2%) required an additional surgical procedure for second fixation. Children who needed second fixation were significantly younger (11.8 years) than those who did not (13.1 years, P=0.013). In conclusion, this retrospective analysis shows that prophylactic contralateral fixation in SCFE is a safe procedure with no major complications and an acceptable rate of minor complications. When Kirschner wires are used for prophylactic pinning, there is a possibility of secondary loss of fixation due to length growth at the level of the physis. To avoid the need for secondary fixation, screw epiphysiodesis might be considered.

Assessment of early cartilage degeneration after slipped capital femoral epiphysis using T2 and T2* mapping

BACKGROUND

T2 and T2* mapping are novel tools to assess cartilage quality.

PURPOSE

To evaluate hip cartilage quality in the long-term follow-up of patients with slipped capital femoral epiphysis (SCFE) with T2 and T2* mapping.

MATERIAL AND METHODS

Thirty-three patients (19 men, 14 women, mean age 24 ± 6.0 years, range 18-51 years) with a history of SCFE in 41 hips and 10 healthy controls (seven men, mean age 22 ± 4 years) were included. Follow-up period was 12 ± 6 (range 4-39 years) years. Coronal T2 and T2* mapping were performed on a 1.5 T scanner. T2 and T2* values of the hip articular cartilage were determined in the medial, central, and lateral portion of the hip within the weight bearing zone. Clinical symptoms including pain were assessed with the Harris hip score. Statistical analysis was performed using Mann-Whitney U test and Spearman rank sum test.

RESULTS

In hips after SCFE T2 (central portion: 25.71 ms ± 4.84 ms vs. 29.71 ms ± 7.04 ms, p<0.05) and T2* (central portion: 20.76 ms ± 3.17 ms vs. 23.06 ms ± 2.68 ms, P<0.01) of cartilage were significantly lower, compared to controls. The differences were most apparent in the lateral portion of the hip articular cartilage. Abnormal cartilage T2 and T2* were not associated with hip pain or impaired hip function. SCFE was unilateral in 23 cases (70%). In the patients' unaffected hips without SCFE, areas of significantly reduced T2 (central portion: 26.07 ms ± 4.27 ms, P<0.05) and T2* (lateral portion: 23.23 ms ± 2.45 vs. 25.11 ms ± 3.01 ms, P<0.05) were noted.

CONCLUSION

T2 and T2* mapping of the hip in patients after SCFE are significantly different from healthy controls and may offer additional information about cartilage quality.

In situ pinning with arthroscopic osteoplasty for mild SCFE: A preliminary technical report

BACKGROUND

There is emerging evidence that even mild slipped capital femoral epiphysis leads to early articular damage. Therefore, we have begun treating patients with mild slips and signs of impingement with in situ pinning and immediate arthroscopic osteoplasty. DESCRIPTION OF TECHNIQUES: Surgery was performed using the fracture table. After in situ pinning and diagnostic arthroscopy, peripheral compartment access was obtained and head-neck osteoplasty was completed.

METHODS

Between March 2008 and August 2009, three male patients (age range, 11-15 years; BMI, 22-31 kg/m(2)) presented with slip angles between 15º and 30º. All were ambulatory without assistance but had 2 to 12 weeks of hip and/or knee pain, limited motion and a positive impingement test. Postoperatively, patients were assessed at 6 weeks; 3 and 6 months; then every 6 months for the first two years. Hip motion, epiphyseal-metaphyseal offsets and alpha angles were determined. Patients completed the UCLA activity scale at latest followup that ranged from 6 to 23 months.

RESULTS

Arthroscopic evaluation revealed labral fraying, acetabular chondromalacia, and a prominent metaphyseal ridge. At last followup, each was pain-free and had returned to unrestricted activities. Hip motion improved in all and none demonstrated clinical impingement. Radiographs showed normalized epiphyseal-metaphyseal offsets and alpha angles.

CONCLUSIONS

In situ pinning with arthroscopic osteoplasty can limit impingement after mild slipped capital femoral epiphysis. Due to limited followup, we are unable to say whether this protocol reduces subsequent articular damage. Although we recommend performing these procedures concomitantly, they can be performed in a staged fashion, especially since hip arthroscopy following an epiphyseal slip can be challenging.

Prognostic significance of stability in slipped upper femoral epiphysis: a systematic review and meta-analysis

OBJECTIVE

To examine associations of major complications after surgical treatment of slipped upper femoral epiphysis (SUFE) with condition- and treatment-related risk factors.

STUDY DESIGN

This systematic review and meta-analysis of observational studies used an electronic literature search of Embase and Medline supplemented by a manual search of bibliographies. The studies enrolled children and adolescents with SUFE, defined stable and unstable disease, and reported at least 3 primary endpoints: avascular necrosis (AVN), chondrolysis, and reoperation. Random-effects meta-regression analysis was performed when possible.

RESULTS

The weighted risk for AVN, derived from intercept-only meta-regression, was estimated as 5.3% (95% confidence interval [CI], 3.4%-7.2%). Patients with unstable slips had a 9.4-fold greater risk of developing AVN. Instability proved to be an independent predictor for AVN. The weighted risk of chondrolysis was 0.8% (95% CI, 0.2%-1.4%), associated with unstable slips and osteotomies. The risk of reoperation was estimated at 5.5% (95% CI, 1.7%-9.3%). Loss of fixation was the primary reason for reoperation.

CONCLUSIONS

Current evidence indicates that unstable slips are at a significantly higher risk for AVN than stable slips, regardless of the attempted surgical approach. Little clinical information is available regarding chondrolysis and reoperation in relation to the stability of the physis.

MRI morphometry, cartilage damage and impaired function in the follow-up after slipped capital femoral epiphysis

OBJECTIVE

To assess rotation deficits, asphericity of the femoral head and localisation of cartilage damage in the follow-up after slipped capital femoral epiphysis (SCFE).

MATERIALS AND METHODS

Magnetic resonance imaging studies were obtained in adult patients with a history of SCFE. A total of 35 hips after SCFE in 26 patients (mean age 24.1 +/- 6.5, mean follow-up 11.9 +/- 6.1 years) were evaluated. The control group comprised 20 healthy hips from 10 young adults with an average age of 23.9 +/- 3.7 years. The MR protocol included a T1-weighted sequence with a 3D volumetric interpolated breath-hold sequence and a radial 2D proton density-weighted sequence around the femoral neck. Images were evaluated for alpha angle and cartilage damage in five positions around the femoral head. Hip function was evaluated at the time of MRI and correlated with MRI results. Mann-Whitney U test and Spearman's correlation coefficient were used for statistical analysis.

RESULTS

In the hips after SCFE alpha angles were significantly increased in the anterosuperior (74.1 degrees +/- 18.8 degrees ) and superior (72.5 degrees +/- 21.5 degrees ) positions and decreased in the posterior position (25.0 degrees +/- 7.2 degrees ). Cartilage damage was dominant in the anterosuperior and superior positions. Impaired rotation significantly correlated with increased anterosuperior, superior and posterosuperior alpha angles.

CONCLUSION

The data support an anterosuperior and superior cam-type deformity of the femoral head-neck junction in the follow-up after SCFE. MRI after SCFE can be used to assess anterosuperior and superior alpha angles, since the anterior alpha angle by itself may underestimate asphericity and is not associated with rotation deficits.

[Femoroacetabular impingement: radiographic diagnosis--what the radiologist should know]

OBJECTIVE

The purpose of this article is to show the important radiographic criteria that indicate the two types of femoroacetabular impingement: pincer and cam impingement. In addition, potential pitfalls in pelvic imaging concerning femoroacetabular impingement are shown.

CONCLUSION

Femoroacetabular impingement is a major cause for early "primary" osteoarthritis of the hip. It can easily be recognized on conventional radiographs of the pelvis and the proximal femur.

The role of pre-treatment MRI in established cases of slipped capital femoral epiphysis

BACKGROUND

Slipped capital femoral epiphysis (SCFE) often results in functional impairment and premature osteoarthritis despite surgical treatment. Treatment decisions are commonly based on the clinical history and radiographic appearance. This study assesses the pre-treatment features of SCFE and correlates them to the clinical history to: (1) define the underlying pathological mechanisms; (2) correlate the morphological hip abnormalities with the clinical classifications; (3) identify specific magnetic resonance imaging (MRI) features that could carry prognostic implications for treatment approach and outcome.

METHODS

Clinical history and pre- and posttreatment radiographs and pre-treatment MRIs of 14 patients with 15 affected hips were reviewed. Alignment, impingement, fulcrum formation, remodelling, osteopenia, synovitis, joint effusion, bone marrow and soft tissue oedema and status of the physis and the periosteal sleeve were assessed and related to the clinical history, in particular history of trauma, duration of clinical symptoms and ability to bear weight.

RESULTS

Bone marrow oedema around the growth plate and joint effusion occurred in all patients. Synovitis occurred in 13/15 patients. 6 patients had a fall before presenting with SCFE. 5/6 had periarticular soft tissue oedema, complete disruption of the physis and partial periosteal sleeve disruption. 9 patients had no fall prior to presentation, physis and periost were intact in 7/9; periarticular oedema was not seen. 14/15 showed evidence of chronic remodelling. Despite an acute clinical history remodelling was present. A fulcrum-like alignment, impingement of the epiphysis on the metaphysis with a small area of physical contact, was seen in 8 patients, 6/8 had a prior fall. There was no case of avascular necrosis. Spontaneous reduction of SCFE occurred in 1 case, the only case without chronic remodelling. With MRI as gold standard radiographs underestimate the severity of SCFE.

CONCLUSION

Synovitis, periphyseal oedema and joint effusion are regular features of SCFE. The clinical history and findings are unreliable for the classification of SCFE. Radiographs underestimate the severity of SCFE. SCFE is often a Salter Harris I injury due to a fall with considerable periarticular soft tissue trauma and a potentially unstable alignment of epi- and metaphysis. This can lead to spontaneous reduction prior to surgery, MRI can potentially identify unstable, reducible slips. If the mode of surgical treatment depends on the particular nature of the SCFE then MRI contributes to surgical decision-making.

LEVEL OF EVIDENCE

Level 4, case series.

Radiological evidence of femoroacetabular impingement in mild slipped capital femoral epiphysis: a mean follow-up of 14.4 years after pinning in situ

Conventional treatment of mild slipped capital femoral epiphysis consists of fixation in situ with wires or screws. Recent contributions to the literature suggest that even a mild slip may lead to early damage of the acetabular labrum and adjacent cartilage by abutment of a prominent femoral metaphysis. It has been suggested that the appropriate treatment in mild slipped capital femoral epiphysis should not only prevent further slipping of the epiphysis, but also address potential femoroacetabular impingement by restoring the anatomy of the proximal femur. Between October 1984 and December 1995 we treated 16 patients for unilateral mild slipped capital femoral epiphysis by fixation in situ with Kirschner wires. In this study we have reviewed these patients for clinical and radiological evidence of femoroacetabular impingement. There was little clinical indication of impingement but radiological evaluation assessing the femoral head-neck ratio and measuring the Nötzli alpha angle on the anteroposterior and cross-table radiographs showed significant alterations in the proximal femur. None of the affected hips had a normal head-neck ratio and the mean alpha angle was 86 degrees (55 degrees to 99 degrees ) and 55 degrees (40 degrees to 94 degrees ) on the anteroposterior and lateral cross-table radiographs, respectively. While our clinical data favours conventional treatment, our radiological findings are in support of restoring the anatomy of the proximal femur to avoid or delay the development of femoroacetabular impingement following mild slipped capital femoral epiphysis.

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.

Femoroacetabular impingement

Evidence is emerging that subtle morphologic abnormalities around the hip, resulting in femoroacetabular impingement, may be a contributing factor in some instances to osteoarthritis in the young patient. The morphologic abnormalities result in abnormal contact between the femoral neck/head and the acetabular margin, causing tearing of the labrum and avulsion of the underlying cartilage region, continued deterioration, and eventual onset of arthritis. Nonsurgical treatment typically fails to control symptoms. Surgical management involves dislocation of the hip (while preserving the blood supply to the femoral head) and femoroacetabular osteoplasty. Encouraging results have been reported following femoroacetabular osteoplasty and arthroscopic treatment of femoroacetabular impingement.

Femoroacetabular impingement: radiographic diagnosis--what the radiologist should know

OBJECTIVE

The purpose of this article is to show the important radiographic criteria that indicate the two types of femoroacetabular impingement: pincer and cam impingement. In addition, potential pitfalls in pelvic imaging concerning femoroacetabular impingement are shown.

CONCLUSION

Femoroacetabular impingement is a major cause for early "primary" osteoarthritis of the hip. It can easily be recognized on conventional radiographs of the pelvis and the proximal femur.

[Femoroacetabular impingement: trigger for the development of coxarthrosis]

Femoroacetabular impingement (FAI) is frequent; the estimated prevalence ranges between 10 and 15%. Our 10-years experience strongly suggests that FAI leads to osteoarthritis. Isolated acetabular or femoral abnormalities are rare, even though in women acetabular and in men femoral abnormalities predominate. Normal radiographs do not exclude the presence of FAI. Symptoms are related to the degree of deformity and occur earlier in the presence of activities requiring high levels of motion. The majority of patients with FAI are under the age of 40 years. In contrast to impingement in total hip replacement, the natural hip is under much higher constraint, not allowing to escape from impingement-induced shear forces by subluxation or complete dislocation. FAI-induced shear forces due to an aspherical femoral head/neck (cam type) are therefore high, causing outside-in damage with cleavage lesions of the acetabular cartilage by forced flexion and internal rotation. The cartilage of the femoral head remains initially intact, which cannot be explained by the classic concept of osteoarthritis. After the femoral head has migrated into the acetabular cartilage defect, vertical forces contribute to the further course of osteoarthritis. Tears between the labrum and cartilage, as seen by MRI, are not avulsions of the labrum from the cartilage but rather outside-in avulsions of the cartilage from the labrum. In acetabular overcoverage (pincer type) the labrum is the first structure to fail and acetabular cartilage damage develops thereafter. The treatment of FAI in patients under the age of 40 years is aimed at joint preservation. The clinical result is worse in the presence of significant cartilage damage. Therefore, early appreciation of FAI and timely therapeutic intervention as well as professional and athletic adjustment are important if osteoarthritis is to be prevented.

[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.

[Slipped capital femoral epiphysis and overweight]

The slipped capital femoral epiphysis (SCFE) is defined as a nontraumatic epiphyseal separation and slipping of the proximal femoral epiphysis, which usually occurs during the adolescent growth spurt. Slipping of the upper femoral epiphysis may be classified as acute, chronic, and acute on chronic. The etiology of the disease is still not fully understood but seems to be multifactorial. The typical SCFE during puberty has to be differentiated from the atypical form, which may be associated with an endocrinological disorder or with its therapy. The typical SCFE may be found in male patients, with increased height and weight. It is likely that the growth rate is slightly accelerated before slippage. Obesity is often associated with a decreased femoral anteversion accounting for abnormal mechanical shear forces at the growth plate. SCFE is treated surgically. Surgical methods are administered according to the degree of disease. Because of possible alterations of blood supply to the femoral head, acute SCFE is an emergency. Following SCFE, complications such as chondrolysis and avascular necrosis are feared.