Radiological signs of femoroacetabular impingement are linked to pelvic version in asymptomatic subjects

INTRODUCTION

With the recent interest in hip-spine relationship, the link between femoroacetabular impingement (FAI) and the lumbar-pelvic-femoral complex (LPFC) appears decisive. The objectives of this study were (1) to compare the pelvic version, as well as (2) all the parameters of the LPFC between two populations of healthy subjects, comparing those with radiological signs of FAI to those without and finally, (3) to evaluate the LPFC parameters according to the type of FAI.

HYPOTHESIS

Asymptomatic subjects with radiological signs of FAI had superior pelvic anteversion.

MATERIALS AND METHOD

This retrospective study was based on a prospective cohort of 118 voluntary asymptomatic patients including 62 men (52.5%) with a mean age of 25.6 years±4.4 (19-39). The following parameters: pelvic version (PV), pelvic incidence (PI), lumbar lordosis (LL), sacral slope (SS), hip flexion, intrinsic (IER) and extrinsic (EER) extension reserve were measured using EOS imaging™ in the reference standing position and the lunge position. The radiological signs of FAI (cam, pincer, mixed) were identified on these acquisitions then separated into 2 groups. The first was the group presenting with one or more images of FAI (FAI+) and the second group with no images of FAI (FAI-).

RESULTS

There were 143 hips in the FAI+ group compared to 93 hips in the FAI- group. There were 36.4% cams and 45% pincers. With an average of 9.08°±7.81 (-11.0; 27.0) versus 12.33°±8.94 (-5.0; 55.0), the PV was significantly lower (p=0.022) in the FAI+ group compared to the FAI- group. A post-hoc power analysis on the primary outcome (PV) confirmed sufficient power (1-β=0.809). Compared to the FAI- group, the cam group presented a significantly lower IER and EER (respectively p=0.014 and p=0.047). The comparative analysis between the FAI- and pincer groups found a significant difference in PI (p=0.001), PV (p<0.001), IER (p=0.017) and hip flexion (p<0.001), SS in lunge position (p=0.031) and EER (p=0.039).

CONCLUSION

Asymptomatic subjects with radiographic signs of FAI present with weak pelvic version when standing. This pelvic hyper-anteversion is mainly found in the event of a radiological pincer sign.

LEVEL OF EVIDENCE

III, retrospective comparative study.

Midterm results after arthroscopic femoral neck osteoplasty combined with labral debridement for cam type femoroacetabular impingement in active adults

INTRODUCTION

Arthroscopic labral procedures are frequently undertaken in patients with femoroacetabular impingement (FAI). The role of arthroscopic femoral neck osteoplasty is well established, but less is known about labral procedures. This study evaluates the midterm efficacy and feasibility of arthroscopic osteoplasty with concomitant labral debridement for cam impingement in active adults.

METHODS

The present study was conducted according to the STROBE Statement. All 108 patients who underwent primary hip arthroscopy for cam type FAI combined with labral debridement were considered. Axial and anteroposterior plain radiographs of the pelvis were obtained preoperatively to identify the cam deformity and assess the presence of osteoarthritis, the lateral centre-edge angle, and the alpha angle. The ROM (flexion, extension, abduction, adduction, and intra/extra rotation) was evaluated. The following PROMs were administered: visual analogic scale (VAS), Tegner Activity Scale, non-arthritic hip score (NAHS), the international Hip Outcome Tool (iHOT-33) overall score, and related subscales: symptoms and functional limitations, sports and recreational activities, job-related concerns, and social, emotional, and lifestyle concerns.

RESULTS

At a mean of 2.0 ± 1.1 months, all 108 patients returned to their daily activities with no limitation. At a mean of 2.6 ± 1.4 months, all 108 patients were able to return to sport with no limitation. At 11.9 ± 2.1-month follow-up, no differences were reported in the range of motion compared to baseline: flexion (P = 0.3), extension (P = 0.09), abduction (P = 0.1), adduction (P = 0.3), internal rotation (P = 0.4), and external rotation (P = 0.6). At 72.8 ± 21.7-month follow-up, the mean VAS score was 1.7 ± 3.0, Tegner Activity Scale 3.5 ± 1.4, NAHS 92.1 ± 21.5, iHOT33 83.3 ± 27.2. At a mean of 21.7 ± 15.5 months following the index procedure, 14 of 108 patients had undergone total hip arthroplasty. No further revisions or complications were reported.

CONCLUSION

Arthroscopic femoral neck osteoplasty with concomitant labral debridement for cam type of FAI in active adults yields the reliable results, with a rate of progression to total hip arthroplasty of 13% (14 of 108) at 3-year follow-up. All patients returned to their daily activities with no limitation 2 months postoperatively. Within 3 months, all patients returned to sport with no limitations. No complication related to the index procedure was reported, and no further arthroscopic procedures were necessary.

Characterizing femoroacetabular impingement in professional Nordic Skiers

OBJECTIVE

Studies have shown a high prevalence of femoroacetabular impingement (FAI) among elite athletes yet there is a paucity of data on FAI in Nordic skiers. The purpose of this study was to determine the prevalence of radiographic FAI in professional Nordic Combined Skiers and Ski jumpers compared to controls and assess functional outcomes including hip range of motion (ROM) and pain in patients with radiographic evidence of FAI compared to those without it.

METHODS

A cohort of elite Nordic Skiers underwent medical history, physical examination, and pelvic radiographs at their visit with a fellowship-trained sports medicine physician. On pelvis radiographs, Alpha angle>55 degrees was deemed cam-positive, and positive crossover signs, Tönnis<0, or LCEA>40 were deemed pincer positive. Further stratification was performed by sex, ski event type, hip pain, presence of cam lesions, and presence of pincer lesions. Spearman correlation matrix was performed to measure the association between radiographic measurements and ROM.

RESULTS

Nineteen Nordic skiers and nineteen age, sex, and BMI matched controls were included in the study. There were no significant differences in age, sex, BMI, and hip pain between groups. While Nordic skiers demonstrated decreased ROM bilaterally on external rotation compared to controls, skiers had larger ROM bilaterally on extension, abduction, adduction compared to controls. Skiers were significantly more likely to have bilateral crossover sign and alpha angles>55 compared to controls. Subgroup analysis showed that Cam positive patients had higher flexion and adduction ROM and pincer positive patients had significantly higher flexion and abduction ROM compared to patients without cam and pincer lesions respectively. Patients with hip pain had significantly lower right hip abduction ROM compared to patients without hip pain. No significant correlations were seen between radiographic measurements and ROM.

CONCLUSION

Similar to other elite 'hip heavy' sport athletes, Nordic skiers gave a notably higher prevalence of radiographic cam and pincer type morphology and significantly higher ROM compared to nonathletic controls. Clinicians evaluating Nordic skiers should be aware of these baseline findings with respect to a possible elevated long-term risk of symptomatic FAI in these athletes as well as other conditions related to radiographic FAI.

Pragmatic pluralism: Mutual tolerance of contested understandings between orthodox and alternative practitioners in autologous stem cell transplantation

High-dose chemotherapy and autologous stem cell transplantation (ASCT) is used to treat some advanced malignancies. It is a traumatic procedure, with a high complication rate and significant mortality. ASCT patients and their carers draw on many sources of information as they seek to understand the procedure and its consequences. Some seek information from beyond orthodox medicine. Alternative beliefs and practices may conflict with conventional understanding of the theory and practice of ASCT, and 'contested understandings' might interfere with patient adherence to the strict and demanding protocols required for successful ASCT.The present study, conducted in Sydney, Australia, examines narrative-style interviews with 10 sequentially recruited ASCT patients and nine of their carers conducted at the time of transplant and three months later. Transcripts were read for instances of mention of alternative advice, and for instances of contested understanding of information relevant to the transplant.Patients and carer pairs expressed closely concordant views about alternative advice. Five pairs were consulting alternative practitioners. Contested understanding was expressed in four domains-understandings of the transplant itself and its underlying theory, of the relationship between the components of the 'transplant', of the nature and role of stem cells, and of beliefs about bodily function and life-style. Contested understandings of the transplant treatment were expressed as predominantly personal interpretations of orthodox informationPatients and carers seemed to recognise that alternative and conventional systems were discordant, yet they were able to separate the two, and adhere to each practice without prejudicing their medical treatment. A single case of late, post-transplant repudiation of Western medicine is discussed to emphasise some of the possible determinants of dissonance when it does occur.

Cam morphology but neither acetabular dysplasia nor pincer morphology is associated with osteophytosis throughout the hip: findings from a cross-sectional study in UK Biobank

OBJECTIVES

To examine whether acetabular dysplasia (AD), cam and/or pincer morphology are associated with radiographic hip osteoarthritis (rHOA) and hip pain in UK Biobank (UKB) and, if so, what distribution of osteophytes is observed.

DESIGN

Participants from UKB with a left hip dual-energy X-ray absorptiometry (DXA) scan had alpha angle (AA), lateral centre-edge angle (LCEA) and joint space narrowing (JSN) derived automatically. Cam and pincer morphology, and AD were defined using AA and LCEA. Osteophytes were measured manually and rHOA grades were calculated from JSN and osteophyte measures. Logistic regression was used to examine the relationships between these hip morphologies and rHOA, osteophytes, JSN, and hip pain.

RESULTS

6,807 individuals were selected (mean age: 62.7; 3382/3425 males/females). Cam morphology was more prevalent in males than females (15.4% and 1.8% respectively). In males, cam morphology was associated with rHOA [OR 3.20 (95% CI 2.41-4.25)], JSN [1.53 (1.24-1.88)], and acetabular [1.87 (1.48-2.36)], superior [1.94 (1.45-2.57)] and inferior [4.75 (3.44-6.57)] femoral osteophytes, and hip pain [1.48 (1.05-2.09)]. Broadly similar associations were seen in females, but with weaker statistical evidence. Neither pincer morphology nor AD showed any associations with rHOA or hip pain.

CONCLUSIONS

Cam morphology was predominantly seen in males in whom it was associated with rHOA and hip pain. In males and females, cam morphology was associated with inferior femoral head osteophytes more strongly than those at the superior femoral head and acetabulum. Further studies are justified to characterise the biomechanical disturbances associated with cam morphology, underlying the observed osteophyte distribution.

Hip joint space width in an asymptomatic population: Computed tomography analysis according to femoroacetabular impingement morphologies

Background

Although the association between femoroacetabular impingement (FAI) syndrome and hip osteoarthritis (OA) is well established, not all hips exhibiting cam or pincer morphologies (i.e. imaging findings of FAI syndrome) are symptomatic or arthritic. It is difficult to detect which subgroup will wear out, or how does the arthritic process start radiographically. Therefore, we measured in a retrospective study based on computed tomography (CT) analysis, the joint space width (JSW) according to a standard protocol and we investigated its variation according to the presence of a cam and/or pincer morphology. We hypothesized that the radiological presence of a cam and/or pincer hip morphologies, even in asymptomatic subjects, would affect JSW.

Methods

Two hundred pelvic CT scans performed for non-orthopedic etiologies in asymptomatic patients were analyzed using a 3D software. After excluding patients with hip OA or previous hip surgery, 194 pelvic CT scans (388 hips) were retained. We measured for each hip the presence of FAI syndrome imaging findings (cam and pincer morphologies) using the classical parameters of coxometry. In addition, we performed a measurement of articular joint space width according to a standard protocol. We then calculated the mean thickness of 3 defined regions along the femoroacetabular joint: anterior-superior, posterior-inferior, and posterior-superior. Lastly, we compared the JSW across 4 groups: hips with (1) no cam or pincer, (2) pincer, (3) cam, and (4) cam and pincer morphologies using a multivariate analysis. Additionally, a topographic heatmap of JSW was plotted allowing quantitative representation of JSW along the joint.

Results

Increased JSW with peak difference of 0.9 mm (25.7%) was found in hips with cam and pincer morphologies when compared to normal ones (p = 0.002) and to hips with pincer or cam morphologies only.

Conclusion

Positive variations in JSW were associated to the presence of cam and pincer morphologies. This significant increase in JSW could be one of the earliest measurable changes preceding later classical alterations.

Deriving alpha angle from anterior-posterior dual-energy x-ray absorptiometry scans: an automated and validated approach

Introduction: Alpha angle (AA) is a widely used measure of hip shape that is commonly used to define cam morphology, a bulging of the lateral aspect of the femoral head. Cam morphology has shown strong associations with hip osteoarthritis (OA) making the AA a clinically relevant measure. In both clinical practice and research studies, AA tends to be measured manually which can be inconsistent and time-consuming. Objective: We aimed to (i) develop an automated method of deriving AA from anterior-posterior dual-energy x-ray absorptiometry (DXA) scans; and (ii) validate this method against manual measures of AA. Methods: 6,807 individuals with left hip DXAs were selected from UK Biobank. Outline points were manually placed around the femoral head on 1,930 images before training a Random Forest-based algorithm to place the points on a further 4,877 images. An automatic method for calculating AA was written in Python 3 utilising these outline points. An iterative approach was taken to developing and validating the method, testing the automated measures against independent batches of manually measured images in sequential experiments. Results: Over the course of six experimental stages the concordance correlation coefficient, when comparing the automatic AA to manual measures of AA, improved from 0.28 [95% confidence interval 0.13-0.43] for the initial version to 0.88 [0.84-0.92] for the final version. The inter-rater kappa statistic comparing automatic versus manual measures of cam morphology, defined as AA ³≥60°, improved from 0.43 [80% agreement] for the initial version to 0.86 [94% agreement] for the final version. Conclusions: We have developed and validated an automated measure of AA from DXA scans, showing high agreement with manually measuring AA. The proposed method is available to the wider research community from Zenodo.

Deriving alpha angle from anterior-posterior dual-energy x-ray absorptiometry scans: an automated and validated approach

Introduction: Alpha angle (AA) is a widely used imaging measure of hip shape that is commonly used to define cam morphology, a bulging of the lateral aspect of the femoral head. Cam morphology has shown strong associations with hip osteoarthritis (OA) making the AA a clinically relevant measure. In both clinical practice and research studies, AA tends to be measured manually which can be inconsistent and time-consuming. Objective: We aimed to (i) develop an automated method of deriving AA from anterior-posterior dual-energy x-ray absorptiometry (DXA) scans; and (ii) validate this method against manual measures of AA. Methods: 6,807 individuals with left hip DXAs were selected from UK Biobank. Outline points were manually placed around the femoral head on 1,930 images before training a Random Forest-based algorithm to place the points on a further 4,877 images. An automatic method for calculating AA was written in Python 3 utilising these outline points. An iterative approach was taken to developing and validating the method, testing the automated measures against independent batches of manually measured images in sequential experiments. Results: Over the course of six experimental stages the concordance correlation coefficient, when comparing the automatic AA to manual measures of AA, improved from 0.28 [95% confidence interval 0.13-0.43] for the initial version to 0.88 [0.84-0.92] for the final version. The inter-rater kappa statistic comparing automatic versus manual measures of cam morphology, defined as AA ³≥60°, improved from 0.43 [80% agreement] for the initial version to 0.86 [94% agreement] for the final version. Conclusions: We have developed and validated an automated measure of AA from DXA scans, showing high agreement with manually measuring AA. The proposed method is available to the wider research community from Zenodo.

The prevalence of athletic pubalgia imaging findings on MRI in patients with femoroacetabular impingement

OBJECTIVE

To determine the prevalence of athletic pubalgia imaging findings on MRI in patients with femoroacetabular impingement and assess for correlative risk factors.

MATERIALS AND METHODS

A retrospective search identified 156 hips with femoroacetabular impingement and a control group of 113 without femoroacetabular impingement that had an MRI performed between January 1, 2015, and January 1, 2018. Two fellowship-trained musculoskeletal radiologists reviewed studies for the presence of acute osteitis pubis, chronic osteitis pubis, adductor tendinosis, and tendon tear; rectus abdominis tendinosis and tendon tear; and aponeurotic plate tear. Findings were correlated with various clinical and imaging risk factors. Univariate and multivariate statistical analyses were performed.

RESULTS

Imaging findings of adductor tendinosis (p = 0.02) and chronic osteitis pubis (p = 0.01) were more prevalent in FAI patients than controls. Univariate analyses in FAI patients showed that an alpha angle ≥ 60° had a higher prevalence of aponeurotic plate tears (p = 0.02) and adductor tendinosis (p = 0.049). Multivariate analyses showed that an alpha angle ≥ 60° had a higher prevalence of chronic osteitis pubis (OR = 2.27, p = 0.031), sports participation had a higher prevalence of adductor tendon tears (OR = 4.69, p = 0.013) and chronic osteitis pubis (OR = 2.61, p = 0.0058), and males had a higher prevalence of acute osteitis pubis (OR = 5.17, p = 0.032).

CONCLUSION

Sports participation, alpha angle ≥ 60°, and male sex predict a higher prevalence of athletic pubalgia imaging findings in patients with femoroacetabular impingement.

Biomechanics during cross-body lunging in individuals with and without painful cam and/or pincer morphology

BACKGROUND

Femoroacetabular impingement is a patho-mechanical hip condition that can lead to restrictions in hip motion, particularly in end-range hip flexion, adduction and/or internal rotation. Radiographic evidence of femoroacetabular impingement - cam and/or pincer morphology - is prevalent in the general and athletic populations. There is, however, a lack of studies that have analyzed the performance of sport-specific movements in people possessing these morphologies. Therefore, the purpose of this study was to compare cross-body lunge biomechanics between individuals with and without painful cam and/or pincer morphology.

METHODS

This was an exploratory, cross-sectional study where nine participants with cam and/or pincer morphology and symptoms, thirteen participants with asymptomatic cam and/or pincer morphology, and eleven pain-free controls performed the cross-body lunge during a single session. Trunk, pelvis, hip, knee and ankle kinematics, as well as hip, knee and ankle kinetics and vertical ground reaction forces were examined.

FINDINGS

Overall, the groups performed the movement similarly, with most variables statistically similar between groups. However, pelvis sagittal plane excursion throughout the entire cross-body lunge was significantly larger in those with cam and/or pincer morphology and symptoms compared to those with asymptomatic cam and/or pincer morphology (P = .046, effect size = 0.98).

INTERPRETATION

The results of this study show that cross-body lunge performance is similar across individuals with and without painful cam and/or pincer morphology. However, future research should aim to better understand pelvis biomechanics during sporting activities, as pelvis sagittal plane excursion may have important implications in rehabilitation and sport performance.

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.

Increased subchondral bone thickness in hips with cam-type femoroacetabular impingement

OBJECTIVES

Increased thickness of subchondral acetabular bone with associated articular cartilage thinning in hips with femoroacetabular (FAI) cam impingement has been observed on magnetic resonance imaging (MRI). Dynamic attrition by the cam deformity moving into the acetabulum may potentiate trans-articular shear stresses thus causing these subchondral bone changes. We aimed to quantify the hypertrophic changes of subchondral acetabular bone in patients with cam-type FAI.

METHODS

MRI studies were performed on an asymptomatic population of young Swiss army recruits. Subjects underwent clinical examination and completed questionnaires before undergoing an MRI of the hip. Cam deformities were graded and the dimensions of the acetabular subchondral bone quantified. Univariate linear regression was used to determine the association between the presence of cam deformities and the degree of subchondral acetabular sclerosis.

RESULTS

There was a strong association between cam deformities and the thickness, area and shape of subchondral sclerosis. The main increase in hypertrophy was observed in the antero-superior acetabulum where impingement typically occurs. The subchondral sclerosis was 0.66 mm thicker in cam-type deformities than in hips without cam-type deformities (95% CI, 0.38-0.93, p value < 0.001).

CONCLUSIONS

Mechanical stress in the antero-superior acetabular area is elevated in hips with a cam-type deformity. The study supports the concept that cam-type deformity induced stress leads to hypertrophy of subchondral acetabular bone in the area of impingement. This is collocated with the clinically observed cartilage damage caused by the cam mechanism.

Cam-based vibration-counter-balanced laser-induced fluorescence scanner for multiplexed capillary detection

Laser-induced fluorescence (LIF) rotary scanners have been successfully used for multiplexed capillary detection. However, these scanners have a limitation that the capillaries have to be assembled in a circular format, which can be inconvenient for certain applications. A linear LIF scanner works well for flat parallel capillary arrays, but motor accelerations/decelerations (for direction changes) and scanning head vibrations introduce high instrumental noises. The number of capillaries that can be scanned by a linear scanner is limited because of the above constraints. We have constructed a cam-based scanner in an attempt to address these issues. A cam-based scanner eliminates the motor accelerations/decelerations but not the scanning head vibrations. In this work, we attach a second scanning head to the cam on the opposite side of the first scanning head to counter-balance the mechanical vibrations. With this modification, we improve the limit of detection by more than 3 times (from 69 pM to 20 pM fluorescein). We also increase the capillary number capacity by more than 6 times; the total number of capillaries that can be scanned is 426 if 150-μm-o.d. capillaries are used or 320 if 200-μm-o.d. capillaries are used. To demonstrate the utility of this instrument, we assemble a 99-capillary array on one capillary holder and perform capillary electrophoresis of two fluorescent dyes; separations in all capillaries are successfully monitored simultaneously. We also apply it for detecting fluorescently labeled proteins resolved by 24 s-dimension capillaries in a chip-capillary hybrid device; two-dimensional separation results are nicely produced.

A compact pulsatile simulator based on cam-follower mechanism for generating radial pulse waveforms

Background

There exists a growing need for a cost-effective, reliable, and portable pulsation simulator that can generate a wide variety of pulses depending on age and cardiovascular disease. For constructing compact pulsation simulator, this study proposes to use a pneumatic actuator based on cam-follower mechanism controlled by a DC motor. The simulator is intended to generate pulse waveforms for a range of pulse pressures and heart beats that are realistic to human blood pulsations.

Methods

This study first performed in vivo testing of a healthy young man to collect his pulse waveforms using a robotic tonometry system (RTS). Based on the collected data a representative human radial pulse waveform is obtained by conducting a mathematical analysis. This standard pulse waveform is then used to design the cam profile. Upon fabrication of the cam, the pulsatile simulator, consisting of the pulse pressure generating component, pressure and heart rate adjusting units, and the real-time pulse display, is constructed. Using the RTS, a series of testing was performed on the prototype to collect its pulse waveforms by varying the pressure levels and heart rates. Followed by the testing, the pulse waveforms generated by the prototype are compared with the representative, in vivo, pulse waveform.

Results

The radial Augmentation Index analysis results show that the percent error between the simulator data and human pulse profiles is sufficiently small, indicating that the first two peak pressures agree well. Moreover, the phase analysis results show that the phase delay errors between the pulse waveforms of the prototype and the representative waveform are adequately small, confirming that the prototype simulator is capable of simulating realistic human pulse waveforms.

Conclusions

This study demonstrated that a very accurate radial pressure waveform can be reproduced using the cam-based simulator. It can be concluded that the same testing and design methods can be used to generate pulse waveforms for other age groups or any target pulse waveforms. Such a simulator can make a contribution to the research efforts, such as development of wearable pressure sensors, standardization of pulse diagnosis in oriental medicine, and training medical professionals for pulse diagnosis techniques.

Correlation of alpha angle between various radiographic projections and radial magnetic resonance imaging for cam deformity in femoral head-neck junction

PURPOSE

Radial magnetic resonance imaging (MRI) along the axis of the femoral head neck is the gold standard for detection of cam deformity of the proximal femur. This study was performed to identify which plain radiographic projection was best correlated with radial MRI.

METHODS

Five different plain radiographic projections and 18 slices of radial MRI were applied to 35 consecutive hips with groin pain and positive impingement sign. Alpha angles were measured to detect the asphericity of the femoral head-neck junction in all images. Radiographs were taken in anteroposterior pelvis, cross-table lateral, 90° Dunn, 45° Dunn and modified 45° Dunn views. Pearson's correlation coefficients were determined to assess the association between the alpha angle obtained from radial MRI and each radiographic technique. The sensitivity, specificity, positive and positive predictive values and accuracy of plain radiographic alpha angle measurements were assessed using a threshold alpha angle value of 50.5° for cam deformity.

RESULTS

Pearson's correlation coefficients in the alpha angle values between MRI and plain radiographic projections were 0.45, 0.70, 0.62, 0.81 and 0.69 for the anteroposterior pelvis, cross-table lateral, 90° Dunn, 45° Dunn and modified 45° Dunn views, respectively. In terms of sensitivity and accuracy, the 45° Dunn view had the greatest values.

CONCLUSIONS

Alpha angle of the 45° Dunn view was best correlated with that of radial MRI. The 45° Dunn view had better sensitivity and accuracy than other radiographic projections. The 45° Dunn view may be preferable for screening of cam deformity.

LEVEL OF EVIDENCE

II.

Is the hip capsule thicker in diseased hips?

Objectives

The purpose of this study was to compare the thickness of the hip capsule in patients with surgical hip disease, either with cam-femoroacetabular impingement (FAI) or non-FAI hip pathology, with that of asymptomatic control hips.

Methods

A total of 56 hips in 55 patients underwent a 3Tesla MRI of the hip. These included 40 patients with 41 hips with arthroscopically proven hip disease (16 with cam-FAI; nine men, seven women; mean age 39 years, 22 to 58) and 25 with non-FAI chondrolabral pathology (four men, 21 women; mean age 40 years, 18 to 63) as well as 15 asymptomatic volunteers, whose hips served as controls (ten men, five women; mean age 62 years, 33 to 77). The maximal capsule thickness was measured anteriorly and superiorly, and compared within and between the three groups with a gender subanalysis using student’s t-test. The correlation between alpha angle and capsule thickness was determined using Pearson’s correlation coefficient.

Results

Superiorly, the hip capsule was significantly greater in cam- (p = 0.028) and non-FAI (p = 0.048) surgical groups compared with the asymptomatic group. Within groups, the superior capsule thickness was significantly greater than the anterior in cam- (p < 0.001) and non-FAI (p < 0.001) surgical groups, but not in the control group. There was no significant correlation between the alpha angle and capsule thickness. There were no gender differences identified in the thickness of the hip capsule.

Conclusion

The thickness of the capsule does not differ between cam- and non-FAI diseased hips, and thus may not be specific for a particular aetiology of hip disease. The capsule is, however, thicker in diseased surgical hips compared with asymptomatic control hips.

Cite this article: K. S. Rakhra, A. A. Bonura, R. Nairn, M. E. Schweitzer, N. M. Kolanko, P. E. Beaule. Is the hip capsule thicker in diseased hips? Bone Joint Res 2016;5:586–593. DOI: 10.1302/2046-3758.511.2000495.

Capsular release around the intercondylar notch increases the extension gap in posterior-stabilized rotating-platform total knee arthroplasty

BACKGROUND

In posterior-stabilized (PS) total knee arthroplasty (TKA), various post-cam designs can be used. A larger cam of the femoral component may tighten the extension gap. Few studies have investigated the relationship between capsular release around the intercondylar notch and the extension gap. The aim of this study was to assess the effect of capsular release around the intercondylar notch on the extension gap.

METHODS

Forty-eight patients (54 knees) who underwent PS rotating-platform TKA (PFC Sigma RP-F) were enrolled retrospectively. We measured the extension gap with and without a femoral trial using a knee balancer, applying a joint distraction force of 44lb. When an intraoperative flexion contracture of >5° persisted, we performed a capsular release approximately 10mm cranial to the intercondylar notch. After full knee extension was achieved, the extension gap was measured again.

RESULTS

Thirty knees required capsular release. With a trial, the medial and lateral differences between the extension gaps before and after capsular release were 1.7mm (p<0.0001) and 2.3mm (p<0.0001), respectively. Without a trial, the gaps were enlarged by 0.4mm (p=0.0452) and 0.6mm (p=0.0215), respectively. Twenty-four knees did not require release. No significant differences were noted in the range of motion at one-year follow-up between the two cohorts.

CONCLUSIONS

With PS rotating-platform TKA, capsular release around the intercondylar notch is found to increase the extension gap and may prevent postoperative flexion contracture.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

The wavy Mutation Maps to the Inositol 1,4,5-Trisphosphate 3-Kinase 2 (IP3K2) Gene of Drosophila and Interacts with IP3R to Affect Wing Development

Inositol 1,4,5-trisphosphate (IP3) regulates a host of biological processes from egg activation to cell death. When IP3-specific receptors (IP3Rs) bind to IP3, they release calcium from the ER into the cytoplasm, triggering a variety of cell type- and developmental stage-specific responses. Alternatively, inositol polyphosphate kinases can phosphorylate IP3; this limits IP3R activation by reducing IP3 levels, and also generates new signaling molecules altogether. These divergent pathways draw from the same IP3 pool yet cause very different cellular responses. Therefore, controlling the relative rates of IP3R activation vs. phosphorylation of IP3 is essential for proper cell functioning. Establishing a model system that sensitively reports the net output of IP3 signaling is crucial for identifying the controlling genes. Here we report that mutant alleles of wavy (wy), a classic locus of the fruit fly Drosophila melanogaster, map to IP3 3-kinase 2 (IP3K2), a member of the inositol polyphosphate kinase gene family. Mutations in wy disrupt wing structure in a highly specific pattern. RNAi experiments using GAL4 and GAL80(ts) indicated that IP3K2 function is required in the wing discs of early pupae for normal wing development. Gradations in the severity of the wy phenotype provide high-resolution readouts of IP3K2 function and of overall IP3 signaling, giving this system strong potential as a model for further study of the IP3 signaling network. In proof of concept, a dominant modifier screen revealed that mutations in IP3R strongly suppress the wy phenotype, suggesting that the wy phenotype results from reduced IP4 levels, and/or excessive IP3R signaling.

Cyclical loading causes injury in and around the porcine proximal femoral physeal plate: proposed cause of the development of cam deformity in young athletes

Background

The repetitive load to which the adolescent athlete’s body is exposed during training and competition affects bone growth. In previous studies, abnormalities of the spine and extremities of adolescent athletes have been described on radiographs and this also applies to the hip. The cam deformity of the hip is an extension of the physeal plate and develops during the adolescent athlete’s growth. Studies of the porcine spine have shown that the vertebral endplates, apophyseal rings and intervertebral discs are susceptible to both static and repetitive loads. The proximal physeal plate of the porcine femur is susceptible to static loads, but no studies have been performed on its susceptibility to repetitive loads. The purpose of this study was to investigate the susceptibility of the proximal porcine femur to repetitive loads.

Methods

Descriptive laboratory study. Seven proximal femurs from four young (5 months) pigs were loaded repetitively (50,000 cycles) using a previously developed model. Three were loaded vertically, three antero-superiorly and one was used as a control. All femurs were examined macroscopically, histologically and with MRI after loading.

Results

No macroscopic injuries were detected on any of the femurs after loading. Fluid redistribution was seen in all femurs on MRI compared with the unloaded control. Injuries were seen in all loaded femurs on microscopic examination of histological samples. Injuries, perpendicularly to the physeal plate and fractures adjacent to the plate, were seen in the vertically loaded specimens. In the antero-superiorly loaded specimen, the injury in the growth plate was parallel to the plate.

Conclusion

Repeated loading of the young porcine hip leads to histological injuries in and adjacent to the physeal plate. These injuries are likely to cause growth disturbances in the proximal femur. We propose that such injuries may be induced in adolescent athletes and offer a plausible explanation for the development of the cam deformity.

The femoral head-neck contour varies as a function of physeal development

OBJECTIVES

The purpose of this study was to investigate whether the femoral head-neck contour, characterised by the alpha angle, varies with the stage of physeal maturation using MRI evaluation of an asymptomatic paediatric population.

METHODS

Paediatric volunteers with asymptomatic hips were recruited to undergo MRI of both hips. Femoral head physes were graded from 1 (completely open) to 6 (completely fused). The femoral head-neck contour was evaluated using the alpha angle, measured at the 3:00 (anterior) and 1:30 (anterosuperior) positions and correlated with physeal grade, with gender sub-analysis performed.

RESULTS

A total of 43 asymptomatic paediatric volunteers (26 male, 17 female) with mean age 13.0 years (eight to 18) were included with review of bilateral hip MRIs. Correlation between the physeal grade and alpha angle was moderate in males at both the 3:00 (r = 0.477, p < 0.001) and 1:30 (r = 0.509, p < 0.001) positions, whereas there was no significant correlation in females. A significant difference was found between the alpha angles of all the physeal grades (3:00, p = 0.030, 1:30, p = 0.005), but only in males, with the angle increasing with higher grades. For physeal grading, the inter-reader reliability was substantial (intraclass correlation coefficient (ICC) = 0.694), and the intra-reader reliability was also substantial (ICC = 0.788).

CONCLUSION

The femoral head-neck contour varies and correlates with the stage of physeal development, but only in males, with the alpha angle increasing with progressive physeal maturation. This suggests that gender differences exist in the natural physiological growth, development or remodelling of femoral head-neck junction. In males, pre-physeal fusion may be a critical period of vulnerability for development of morphologic abnormalities of the femoral head-neck junction. Cite this article: Bone Joint Res 2015;4:17-22.

Current concepts in management of femoroacetabular impingement

Femoroacetabular impingement (FAI) is an increasingly recognized condition, which is believed to contribute to degenerative changes of the hip. This correlation has led to a great deal of interested in diagnosis and treatment of FAI. FAI can be divided into two groups: cam and pincer type impingement. FAI can lead to chondral and labral pathologies, that if left untreated, can progress rapidly to osteoarthritis. The diagnosis of FAI involves a detailed history, physical exam, and radiographs of the pelvis. Surgical treatment is indicated in anatomic variants known to cause FAI. The primary goal of surgical treatment is to increase joint clearance and decrease destructive forces being transmitted through the joint. Treatment has been evolving rapidly over the past decade and includes three primary techniques: open surgical dislocation, mini-open, and arthroscopic surgery. Open surgical dislocation is a technique for dislocating the femoral head from the acetabulum with a low risk of avascular necrosis in order to reshape the neck or acetabular rim to improve joint clearance. Mini-open treatment is performed using the distal portion of an anterior approach to the hip to visualize and to correct acetabular and femoral head and neck junction deformities. This does not involve frank dislocation. Recently, arthroscopic treatment has gained popularity. This however does have a steep learning curve and is best done by an experienced surgeon. Short- to mid-term results have shown relatively equal success with all techniques in patients with no or only mild evidence of degenerative changes. Additionally, all techniques have demonstrated low rates of complications.

Femoroacetabular impingement: a review of diagnosis and management

Hip pain in adults has traditionally been associated with osteoarthritis in the joint. However, many young patients with hip pain do get referred to orthopaedic surgeons without arthritis. Subtle bony and soft tissues abnormalities can present with hip pain in the active young adult. These abnormalities can lead to premature arthritis. With the improvements in clinical examination for hip impingement, radiological imaging using magnetic resonance arthrography (MRA) and or computed tomograms (CT) Scans, these lesions are being detected early. Though the cause of primary osteoarthritis is unknown, it is suggested that femoro-acetabular impingement (FAI) may be responsible for the progression of the disease in these patients. FAI is a pathological condition leading to abutment between the proximal femur and the acetabular rim. Two different mechanisms are described, although a combination of both is seen in clinical practice. Cam impingement is a result of reduced anterior femoral head neck offset. Pincer lesion is caused by abnormalities on the acetabular side. FAI due to either mechanism can lead to chondral lesions and labral pathology. Patients present with groin pain and investigated with radiographs, CT and MRA. Surgery is the treatment of choice. Open or arthroscopic exploration of the hip is undertaken with bony resection to improve the femoral head neck junction with resection or repair of the damaged labrum. This may involve femoral osteochondroplasty for the cam lesion and acetabular rim resection for pincer lesion. There is no difference in outcome between open and arthroscopic surgery for FAI.