[Anterior femoroacetabular impingement after healed femoral neck fractures]

What is the Fate of Undisplaced Femoral Neck Fractures Treated With Cannulated Screws?

BACKGROUND

We aimed to report implant survival in Garden type I and II femoral neck fractures treated with cannulated screws in elderly patients.

METHODS

We retrospectively studied 232 consecutive unilateral Garden I and II patients (232 fractures) treated with cannulated screws. Mean age was 81 years (range, 65 to 100), and a body mass index of 25 (range, 15.8 to 38.3). No between-group differences were found in demographic variables and/or baseline measurements (P > .05). Mean follow-up was 36 months (range, 1 to 171). Two observers measured baseline radiographic variables with good-to-excellent interobserver reliability. The posterior tilt angle, measured on a cross-table lateral x-ray, was used to classify the cohort into <20° (n = 183) and ≥20° (n = 49). The cumulative incidence with competing risk analysis was used to predict association between posterior tilt and subsequent conversion to arthroplasty. Patient survival was calculated with the Kaplan-Meier estimate.

RESULTS

Implant survival was 86.3% (95% confidence interval (CI) 80 to 90) at 12 months and 77.3% (95% CI 64 to 86) at 70 months. The 12-month cumulative incidence failure was 12.6% (95% CI 8 to 17). After controlling for confounders, posterior tilt ≥20° had higher risk of subsequent arthroplasty when compared to posterior tilt <20° (38.8 [95% CI 25 to 52] versus 5% [95% CI 2.8 to 9], subhazard ratio 8.3, 95% CI 3.8 to 18), without any other radiologic or demographic factor being associated with failure. Patient survival was 88.2% (95% CI 83 to 91.7) at 12 months, 79.5% (95% CI 73 to 84) at 24 months, and 57% (95% CI 48 to 65) at 70 months.

CONCLUSION

Cannulated screws were a reliable treatment for Garden I and II fractures, except when there was posterior tilt ≥20°, where arthroplasty should be considered.

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.

[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.

A Simple Percutaneous Technique to Reduce Valgus-Impacted Femoral Neck Fractures

The mainstream surgery for valgus-impacted femoral neck fractures (FNFs) is closed reduction and internal fixation under fluoroscopy. However, femoral neck shortening and anterior femoroacetabular impingement are common complications in healed valgus-impacted FNFs after in situ fixation. Some methods have been reported to prevent complications, but these techniques require the use of a transfixing guide wire that passes through the femoral head, which may cause articular cartilage damage. We introduce a simple reduction technique using one Steinmann pin (S-pin) for valgus-impacted FNFs without any interference of the femur head. A S-pin was placed percutaneously at the inferomedial margin of the fracture, and reduction was achieved by applying manual valgus force along the fracture line. By restoring the anatomical alignment, we confirmed the maximum contact area of the fracture and connection of the medial cortical buttress, so the risk of nonunion was also minimized.

Age and sex-related distribution of alpha angles and the prevalence of the cam morphology of the hip in Asians do not differ from those of other ethnicities

PURPOSE

This study was performed to evaluate the effects of age on the alpha angle and the incidence of asymptomatic cam morphology.

METHODS

The radiographs of asymptomatic individuals between ages 8 and 22 were retrospectively collected. A total of 1417 individuals were included and grouped according to age: 8-12 (Group A), 13-18 (Group B), and 19-22 (Group C) years. Radiographic measurements of the alpha angles of the right hip were obtained from anteroposterior (AP) and frog-leg lateral (FL) radiographs. The correlations among alpha angles, the presence of cam morphology, and age were determined.

RESULTS

The mean alpha angles of the three groups were statistically different (p < 0.001, each). The alpha angles on both radiographs were positively correlated with age. Intra-group analysis revealed that this correlation was only evident on the FL images of males in Group B. The presence of a radiographic cam morphology also positively correlated with age (p < 0.001 in both AP and FL images). The cam morphology on AP radiographs was 0 in Group A, 17(3.0%) in Group B, and 21(4.8%) in Group C; that on FL radiographs was 2(0.3%) in Group A, 45(7.9%) in Group B, and 103(23.6%) in Group C. Intra-group analysis revealed that the correlation was only significant in males in Group B.

CONCLUSIONS

Higher alpha angles and the presence of cam morphology were positively correlated with age, particularly in males at or before the time of skeletal maturation. The prevalence of cam morphology did not differ from those in other ethnicities.

LEVEL OF EVIDENCE

IV.

Basics in hip chondrolabral lesions and state of the art

Chondrolabral complex is a weak point along an histological transition zone. Most cartilage and labral lesions in the femoroacetabular impingement syndrome are located in this area. Different classifications are used to evaluate the severity and predict the prognosis of chondrolabral complex injuries. Acetabular Labrum Articular Disruption (ALAD) and Multicenter Arthroscopy of the Hip Outcomes Research Network (MAHORN) classifications are commonly used with a prognosis and treatment implication. Treatment of chondrolabral lesions detected on magnetic resonance imaging (MRI), should only be considered when clinical symptoms are presented. A wide range of treatment options include debridement with or without microfracture, repair or regenerate therapies. The future of hip joint preservation should be directed towards to the development of the treatment of chondrolabral injuries.

Femoroacetabular impingement

The femoroacetabular impingement (FAI) is as condition recently characterized that results from the abnormal anatomic and functional relation between the proximal femur and the acetabular border, associated with repetitive movements, which lead labrum and acetabular cartilage injuries. Such alterations result from anatomical variations such as acetabular retroversion or decrease of the femoroacetabular offset. In addition, FAI may result from acquired conditions as malunited femoral neck fractures, or retroverted acetabulum after pelvic osteotomies. These anomalies lead to pathological femoroacetabular contact, which in turn create impact and shear forces during hip movements. As a result, there is early labrum injury and acetabulum cartilage degeneration. The diagnosis is based on the typical clinical findings and images. Treatment is based on the correction of the anatomic anomalies, labrum debridement or repair, and degenerate articular cartilage removal. However, the natural evolution of the condition, as well as the outcome from long-term treatment, demand a better understanding, mainly in the asymptomatic individuals.

[Femoral neck fractures in young patients]

Femoral neck fractures in young patients are rare but of high clinical relevance due to the complexity of risk factors and complications. Early stabilization and accurate reduction are of high priority. Femoral head-preserving stabilization by dynamic hip screws or threefold screw osteosynthesis are the methods of choice. Postoperative results should be closely controlled in every case in order to be able to treat possible complications in time.

The development and nature of femoral head cam lesions following acetabular fractures

The aim of acetabular fracture fixation is to restore joint congruity with restoration of the articular surface. Poor outcomes are seen where this has not been achieved. Letournel reported a collarette osteophyte seen postoperatively in a proportion of patients, which he suggested was an early precursor to the development of osteoarthritis. This is a retrospective study of patients treated at a tertiary referral unit who developed this lesion. The triangular index was measured in 48 of these patients and then correlated with their clinical findings, Oxford Hip Score and the presence of osteoarthritis. Length of follow-up, fracture classification, and joint congruency were also recorded. Results showed a statistically significant relationship between cam lesion size and the development of osteoarthritis (P = 0.008), cam lesion size and length of follow-up (P = 0.01), and between groin pain and postoperative joint congruency (LR = 0.035). These findings suggest that the appearance of a cam lesion is a poor long-term prognostic marker for the development of osteoarthritis in patients with an acetabular fracture.

Mechanical factors explain development of cam-type deformity

OBJECTIVE

A cam-type deformity drastically increases the risk of hip osteoarthritis (OA). Since this type of skeletal anomaly is more prevalent among young active adults, it is hypothesized that the loading conditions experienced during certain types of vigorous physical activities stimulates formation of cam-type deformity. We further hypothesize that the growth plate shape modulates the influence of mechanical factors on the development of cam-type deformity.

DESIGN

We used finite element (FE) models of the proximal femur with an open growth plate to study whether mechanical factors could explain the development of cam-type deformity in adolescents. Four different loading conditions (representing different types of physical activities) and three different levels of growth plate extension towards the femoral neck were considered. Mechanical stimuli at the tissue level were calculated by means of the osteogenic index (OI) for all loading conditions and growth plate shape variations.

RESULTS

Loading conditions and growth plate shape influence the distribution of OI in hips with an open growth plate, thereby driving the development of cam-type deformity. In particular, specific types of loads experienced during physical activities and a larger growth plate extension towards the femoral neck increase the chance of cam-type deformity.

CONCLUSIONS

Specific loading patterns seem to stimulate the development of cam-type deformity by modifying the distribution of the mechanical stimulus. This is in line with recent clinical studies and reveals mechanobiological mechanisms that trigger the development of cam-type deformity. Avoiding these loading patterns during skeletal growth might be a potential preventative strategy for future hip OA.

Comparative study of the femoroacetabular impingement (FAI) prevalence in male semiprofessional and amateur soccer players

INTRODUCTION

Femoroacetabular impingement (FAI) represents a novel approach to the mechanical etiology of hip osteoarthritis. The cam-type femoroacetabular impingement deformity occurs frequently in young male athletes. The aim of our study was to evaluate the prevalence of FAI in male semiprofessional soccer players using clinical examination and magnetic resonance imaging (MRI), compared to amateur soccer players. In MRI, the α angle of Nötzli is determined for quantifying FAI.

MATERIALS AND METHODS

According to power analysis, a total of 22 asymptomatic semiprofessional soccer players with a median of 23.3 years of age (range 18-30 years) and 22 male amateur soccer players with a median of 22.5 years of age (control group, range 18-29 years) underwent an MRI to measure the hip α angle of Nötzli. The α angle of the kicking legs of the semiprofessional group and the amateur group were analyzed. The study group was moreover evaluated by the Hip Outcome Score (HOS) and a clinical hip examination including range of motion (ROM) and impingement tests.

RESULTS

In the semiprofessional group, 19 soccer players had a right kicking leg and 1 soccer player had a left kicking leg. 2 soccer players kicked with two feet. In the semi-professional group, the mean value of the α angle of the kicking leg (57.3 ± 8.2°) was significantly higher than in the amateur group (51.7 ± 4.8°, P = 0.008). In the semi-professional group, 15 (62.5 %) of 24 kicking legs had an increased α angle >55°, while 5 (27.3 %) kicking legs of the amateur group had an α angle >55°. Five semi professional soccer players had findings in clinical examination, whereof 4 had an increased α angle >55°. No participant of the amateur group showed pathological results in the clinical examination (P = 0.0484). Overall, semiprofessional soccer players had a higher proportion of an increased α angle than the amateur group.

CONCLUSIONS

Semiprofessional players have a higher prevalence of an increased α angle in the kicking leg than the amateur group at the same age. The kicking leg is predisposed for FAI.

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.

Validity and test-retest reliability of manual goniometers for measuring passive hip range of motion in femoroacetabular impingement patients

Background

The aims of this study were to evaluate the construct validity (known group), concurrent validity (criterion based) and test-retest (intra-rater) reliability of manual goniometers to measure passive hip range of motion (ROM) in femoroacetabular impingement patients and healthy controls.

Methods

Passive hip flexion, abduction, adduction, internal and external rotation ROMs were simultaneously measured with a conventional goniometer and an electromagnetic tracking system (ETS) on two different testing sessions. A total of 15 patients and 15 sex- and age-matched healthy controls participated in the study.

Results

The goniometer provided greater hip ROM values compared to the ETS (range 2.0-18.9 degrees; P < 0.001); good concurrent validity was only achieved for hip abduction and internal rotation, with intraclass correlation coefficients (ICC) of 0.94 and 0.88, respectively. Both devices detected lower hip abduction ROM in patients compared to controls (P < 0.01). Test-retest reliability was good with ICCs higher 0.90, except for hip adduction (0.82-0.84). Reliability estimates did not differ between the goniometer and the ETS.

Conclusions

The present study suggests that goniometer-based assessments considerably overestimate hip joint ROM by measuring intersegmental angles (e.g., thigh flexion on trunk for hip flexion) rather than true hip ROM. It is likely that uncontrolled pelvic rotation and tilt due to difficulties in placing the goniometer properly and in performing the anatomically correct ROM contribute to the overrating of the arc of these motions. Nevertheless, conventional manual goniometers can be used with confidence for longitudinal assessments in the clinic.

[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.

ARTHROSCOPIC TREATMENT OF FEMOROACETABULAR IMPINGEMENT

OBJECTIVE

The purpose of this study is to evaluate the short-term follow-up results of arthroscopic treatment of femoroacetabular impingement. Our hypothesis is that arthroscopic treatment results are favorable.

METHODS

Between August 2003 and August 2007, 28 hips had femoroacetabular impingement treated by hip arthroscopy. The mean age was 34 years, with mean follow-up period of 27 months. Clinical results were graded with the modified Harris hip score, which was measured pre- and postoperatively. Patients had also their internal rotation analyzed. These parameters were calculated by using Wilcoxon's t test for analysis of nonparametric paired samples performed.

RESULTS

The mean preoperative Harris Hip Score was 54.2, improving to 94.8 postoperatively (p<0,001). The mean increase was 37.5 points. We had 4 good results (15%) and 24 excellent results (85%). Preoperatively, the patients had a mean internal rotation of 17°, and, postoperatively, 36°. The average internal rotation increase was 19° (p<0,001).

CONCLUSIONS

The arthroscopic treatment of femoroacetabular impingement presents satisfactory results.

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: 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.

Range of motion in anterior femoroacetabular impingement

The range of motion of normal hips and hips with femoroacetabular impingement relative to some specific anatomic reference landmarks is unknown. We therefore described: (1) the range of motion pattern relative to landmarks; (2) the location of the impingement zones in normal and impinging hips; and (3) the influence of surgical débridement on the range of motion. We used a previously developed and validated noninvasive 3-D CT-based method for kinematic hip analysis to compare the range of motion pattern, the location of impingement, and the effect of virtual surgical reconstruction in 28 hips with anterior femoroacetabular impingement and a control group of 33 normal hips. Hips with femoroacetabular impingement had decreased flexion, internal rotation, and abduction. Internal rotation decreased with increasing flexion and adduction. The calculated impingement zones were localized in the anterosuperior quadrant of the acetabulum and were similar in the two groups and in impingement subgroups. The average improvement of internal rotation was 5.4 degrees for pincer hips, 8.5 degrees for cam hips, and 15.7 degrees for mixed impingement. This method helps the surgeon quantify the severity of impingement and choose the appropriate treatment option; it provides a basis for future image-guided surgical reconstruction in femoroacetabular impingement with less invasive techniques.

[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.