Femoral Head-neck Junction Research Articles

Dynamic Hip Examination for Assessment of Impingement During Hip Arthroscopy

Arthroscopic procedures for treatment of hip pathology are growing exponentially as a result of continued improvements in the understanding of intra- and extra-articular hip anatomy and technological advancements in instrumentation. Nevertheless, it has been reported that the main cause of revision hip arthroscopy is related to a suboptimal intrasurgical management of the abnormal morphology in femoroacetabular impingement (FAI). Under-resection, over-resection, and in some cases combined under-resection and over-resection at different locations of the cam lesion at the femoral head-neck junction may lead to poor outcomes as a result of residual impingement or the iatrogenic creation of structural instability. Thus, an intraoperative assessment technique capable of revealing in real time the effect of the resection is vital for a successful procedure. Therefore, we present a technical note describing our preferred method to dynamically assess overall hip range of motion, motion at risk, and evaluation of the osteoplasty after surgical correction of FAI.

Remplissage of the Femoral Head-Neck Junction in Revision Hip Arthroscopy: A Technique to Correct Excessive Cam Resection

Femoroacetabular impingement (FAI) is an increasingly recognized cause of hip pain. This pathology often involves abnormal femoral neck shape (cam-type FAI), acetabular over coverage (pincer-type FAI), or mixed pathology. Surgical treatment of this entity includes labral repair and femoral head-neck osteochondroplasty. A mindful arthroscopic technique is of paramount importance, because maintaining the integrity of the labrum and a corresponding neck volume has been reported to be vital in maintaining the hip suction seal. Arthroscopic resection of the cam deformity must be performed with care to ensure appropriate femoral offset and maintenance of appropriate femoroacetabular contact. Although the most common cause of failure after hip arthroscopy is incomplete resection of a cam lesion, a previously unrecognized complication is excessive cam resection that can also lead to excessive femoral offset and loss of the suction seal. The purpose of this technical note is to describe the technique for arthroscopic recognition of excessive cam decompression leading to loss of the suction seal and a surgical treatment approach using the “remplissage” technique.

Retrospective Analysis of Idiopathic Hip Osteoarthritis Based on Anteroposterior Pelvic Radiograph; Hip Osteoarthritis Caused by Femoroacetabular Impingement

Background: Femoroacetabular Impingement (FAI) means pathological impact between the femoral head-neck junction and the acetabular rim. Objectives: The aim of this retrospective study was to analyze Femoroacetabular Impingement (FAI) signs, which can lead to idiopathic hip osteoarthritis, from preoperative radiographs of patients indicated for total hip replacement as compared to radiographs of patients without this indication. Methods: We examined the preoperative anteroposterior (AP) pelvic radiograph, the pincer and cam FAI signs of patients between 45 and 60 years, who had undergone total hip replacement. We examined in the same group, the operated side and the non-operated hips with osteoarthritis (patients group). In the control group we examined the pelvic radiograph of patients without symptoms between 45 and 60 years old (control, group). Results: In the patient group (215 patients, 313 hips) we noted the signs of FAI in 88% while in the control group (112 patients 224 hips) these signs were found in 8.8% of cases. Conclusions: In 88% of primary osteoarthritis cases we found FAI morphology on the AP pelvic radiograph, similarly to those found in the bibliography, and we considered naming primary osteoarthritis, secondary osteoarthritis caused by FAI. In the majority of cases, early diagnosis with simple, cheap and easily accessible AP pelvic radiograph with low dose of radiationmay also be warranted

What is the Prevalence of Radiographic Hip Findings Associated With Femoroacetabular Impingement in Asymptomatic Asian Volunteers?

Morphologic features of the proximal femur reminiscent of those seen in patients with femoroacetabular impingement (FAI) have been reported among asymptomatic individuals in Western populations, but whether this is the case in Asian populations is unknown. The purpose of this study was to determine the prevalence of radiographic findings in the proximal femur that are consistent with FAI in asymptomatic Korean volunteers. Two hundred asymptomatic volunteers with no prior hip surgery or childhood hip problems underwent three-view plain radiographs (pelvis AP view, Sugioka view, and 45° Dunn view) of both hips. There were 146 hips from male volunteers and 254 hips from female volunteers in the study. The mean age of all participants was 34.7 years (range, 21-49 years). Cam-type morphologic features were defined as the presence of the following on one or more of the three views: pistol-grip morphologic features, an osseous bump at the femoral head-neck junction, flattening of the femoral head-neck offset, or alpha angle greater than 55°. Pincer-type morphologic features were determined by radiographic signs, including crossover sign, deficient posterior wall sign, or lateral center-edge angle greater than 40°. The prevalence of cam-type morphologic features seen on at least one radiograph was 38% (male, 57%; female, 26%). The prevalence of cam-type features (at least one positive cam-type feature) was 2.0% (male, 6%; female, 0%) on the pelvic AP view, 24% (male, 36%; female, 17%) on the Sugioka view, and 30% (male, 47%; female, 20%) on the 45° Dunn view. The prevalence of pincer-type morphologic features (at least one positive pincer-type feature) was 23% (male, 27%; female, 21%) on the pelvic AP view. The prevalence of FAI-related morphologic features in asymptomatic Asian populations was comparable to the prevalence in Western populations. Considering the high prevalence of radiographic hip findings reminiscent of FAI in asymptomatic Asian populations, it will be important to determine whether FAI-related morphologic features are a cause of hip pain when considering surgery in Asian patients.

Treatment of osteonecrosis of femoral head with modified lightbulb operation: A 10-year follow-up study

Objective: To retrospectively analyze the clinical efficacy of a modified light bulb operation for the treatment of femoral head osteonecrosis. Methods: A total of 38 patients (59 hips) were treated with this procedure between June 2004 and June 2005, and were followed up for over 10 years. They were classified into ARCO stage II (23 hips), stage IIIa (29 hips) and stage IIIb (7 hips); and into the China- Japan Friendship Hospital (CJFH) type C (3 hips), type L1 (7 hips), type L2 (19 hips) and type L3 (30 hips). In the operation, a bone window was made at the femoral head-neck junction. Autologous cancellous bone harvested around the window was mixed with recombinant human bone morphogenetic protein-2 (rh-BMP2), implanted to the subchondral bone and impacted. The cavity was filled with tricalcium phosphate porous bioceramic (Bio- TCP). The Harris hip score was used to evaluate the postoperative improvement of hip function. Excellent, good, fair, and poor results were defined as Harris hip scores of 90-100, 80-89, 70-79 and below 70, respectively. Harris hip scores ＞ 70 were defined as clinical successful. The radiographic follow-up was evaluated by X-ray and CT scan before and 3, 6, 12 months and every year after the treatment. No presences of collapse, crescent sign or narrower joint space were defined as radiographic successful results. Results: Six patients (9 hips) were lost in the follow-up. Of the rest, excellent, good, fair and poor functions were obtained in 30, 6, 5 and 9 hips, respectively. All the failed cases had total hip replacement. The average preoperative Harris hip score of all hips was 60.2 points. The average postoperative Harris hip score was 87.3 points at 10 years after the surgery, with an increase of 27.1 points (p ＜ 0.001). The radiological results were successful in 76% of the hips with preserved spherity of the femoral head and incorporation of the grafts in the femoral heads could be found. Conclusion: (1) The modified lightbulb operation used local cancellous grafts from the femoral head and expanded its volume with Bio-TCP and rhBMP-2. An overall 82% clinical successful rate and 76% radiographic successful rate was achieved with a mean follow-up of 10 years. (2) The operation did not need other autologous grafts to avoid donor site morbidity and was technically easy to perform. Grafts supporting to the lateral column in the necrotic area were found to be the most important determinant to prevent subsequent collapse of the femoral head.

Femoroacetabular Impingement Is Associated With Sports-Related Posterior Hip Instability in Adolescents

Background: Femoroacetabular impingement (FAI) deformity has been associated with posterior hip instability in adult athletes. Purpose: To determine if FAI deformity is associated with posterior hip instability in adolescents, the femoral head-neck junction or acetabular structure in a cohort of adolescent patients who sustained a low-energy, sports-related posterior hip dislocation was compared with that in a group of healthy age- and sex-matched controls with no history of hip injury or pain. Study Design: Cross-sectional study; Level of evidence, 3. Methods: We identified 12 male patients (mean age, 13.9 years; range, 12-16 years) who sustained a sports-related posterior hip dislocation and underwent a computed tomography (CT) scan after closed reduction. For each patient, 3 age- and sex-matched healthy controls were identified. Femoral head-neck type was assessed by measurement of the alpha angle on the radially oriented CT images at the 12-, 1-, 2-, and 3-o’clock positions. Age, body mass index (BMI), alpha angle at each position, acetabular version, Tönnis angle, and lateral center-edge angle (LCEA) on the involved hip in the dislocation group were compared with those of the matched controls using a mixed-effects model. A logistic regression analysis using a generalized estimating equation was used to compare the percentage of subjects with cam-type FAI deformity (alpha angle >55°) in each group. Results: The dislocation and control groups were similar in age distribution and BMI (P > .05). The mean alpha angles were statistically significantly higher in the dislocation group compared with the control group at the superior (46.3° ± 1.1° vs 42.7° ± 0.6°; P = .0213), superior-anterior (55.5° ± 1.9° vs 46.0° ± 1.3°; P = .0005), and anterior-superior (54.9° ± 1.5° vs 48.9° ± 1.0°; P = .0045) regions. Cam deformity was present in a larger proportion of patients in the dislocation group than in the control group (P < .0035). An alpha angle greater than 55° was present in 16.7% of the dislocation group and 0% of the control group at the 12-o’clock position (P = .1213), 41.7% versus 0% at the 1-o’clock position (P = .0034), 58% versus 6% at the 2-o’clock position (P = .0004), and 25% versus 2.8% at the 3-o’clock position (P = .0929). Acetabular anteversion was lower in the dislocation group (9.6° ± 1.4°) compared with the control group (15.1° ± 0.8°) (P = .0068). Mean acetabular LCEA was within a normal range in both groups. Conclusion: A significantly higher mean alpha angle from the superior to the anterior-superior regions of the femoral head-neck junction and lower acetabular version were found in adolescents who sustained low-energy, sports-related posterior hip dislocations.

Arthroscopic Femoral Osteochondroplasty for Cam-Type Femoroacetabular Impingement: The Trough Technique

Arthroscopic osteochondroplasty has become the most common treatment for cam-type femoroacetabular impingement. However, gauging the appropriate depth and location of the femoral osteochondroplasty remains challenging, given the parallax observed from using a 70° arthroscope across multiple viewing perspectives. Consequently, reliable techniques must use a combination of arthroscopic and fluoroscopic checks and balances to assess the femoral head-neck junction to help guide bony resection. We have developed a technique for osteochondroplasty that has made the process more efficient and reliable in our hands. It involves creating a trough at the apex of the osteochondroplasty and then contouring the proximal and distal regions to re-create normal proximal femoral geometry. This article details our technique for femoral osteochondroplasty, which can be performed alone for isolated cam impingement or in concert with other intra- and extra-articular procedures to address associated hip pathology.

Investigating Clinical Failure of Bone Grafting through a Window at the Femoral Head Neck Junction Surgery for the Treatment of Osteonecrosis of the Femoral Head.

AimsThis study aimed to analyze the clinical factors related to the failure of bone grafting through a window at the femoral head-neck junction.MethodsIn total, 119 patients (158 hips) underwent bone grafting for treatment of avascular necrosis of the femoral head. The patients were classified by their ARCO staging and CJFH classification. All patients were clinically and radiographically followed up every three months during the first year and every six months in the following year. The clinical follow-up comprised determination of pre- and postoperative Harris hip scores, while serial AP, frog lateral radiographs, and CT scan were used for the radiographic follow-up.ResultsThe clinical failure of bone grafting was observed in 40 patients. The clinical failure rates in patients belonging to ARCO stage II period, IIIa, and III (b + c) were 25.9%, 16.2%, and 61.5%, respectively, while those in patients belonging to (C + M + L1) type and L2, L3 type disease groups were 1.7%, 38.9%, and 39%, respectively. The clinical failure rates in patients aged below 40 and those aged 40 and over were 20.5% and 39.0%, respectively (all P < 0.05).ConclusionDisease type, disease stage, and patient age are risk factors for failure of bone graft surgery. Patients belonging to ARCO stage II and IIIa showed a good overall response rate, while patients belonging to ARCO stage IIIb and IIIc and those with necrotic lesions involving the lateral pillar (L2 and L3 type) showed high surgical failure rates.

Bernese periacetabular osteotomy. : Indications, technique and results 30years after the first description

The Bernese periacetabular osteotomy (PAO) is asurgical technique for the treatment of (1)hip dysplasia and (2)femoroacetabular impingement due to acetabular retroversion. The aim of the surgery is to prevent secondary osteoarthritis by improvement of the hip biomechanics. In contrast to other pelvic osteotomies, the posterior column remains intact with this technique. This improves the inherent stability of the acetabular fragment and thereby facilitates postoperative rehabilitation. The birth canal remains unchanged. Through ashortened ilioinguinal incision, four osteotomies and one controlled fracture around the acetabulum are performed. The direction of acetabular reorientation differs for both indications while the sequence of the osteotomies remains the same. This surgical approach allows for aconcomitant osteochondroplasty in the case of anaspherical femoral head-neck junction. The complication rate is relatively low despite the complexity of the procedure. The key point for asuccessful long term outcome is an optimal reorientation of the acetabulum for both indications. With an optimal reorientation and aspherical femoral head, the cumulative survivorship of the hip after 10years is 80-90 %. For the very first 75patients, the cumulative 20-year survivorship was 60 %. The preliminary evaluation of the same series at a30-year follow-up still showed asurvivorship of approximately 30 %. The PAO has become the standard procedure for the surgical therapy of hip dysplasia in adolescents and adults.

A Vessel-Preserving Surgical Hip Dislocation Through a Modified Posterior Approach: Assessment of Femoral Head Vascularity Using Gadolinium-Enhanced MRI.

Surgical hip dislocation allows circumferential access to the femoral head and acetabulum and is utilized in the treatment of intra-articular hip disorders. Surgical hip dislocation is currently performed with a trochanteric osteotomy that reliably preserves the femoral head arterial supply; however, trochanteric nonunion or painful hardware requiring removal may occur. In a cadaveric model, using gadolinium-enhanced magnetic resonance imaging (MRI) and gross dissection, we evaluated whether modifications to the posterior approach preserve the femoral head arterial supply after a posterior surgical hip dislocation. In eight fresh-frozen pelvic specimens, a surgical hip dislocation was performed through the posterolateral approach with modifications in the tenotomy of the short external rotators and a capsulotomy designed to preserve the medial femoral circumflex artery (MFCA). Modifications included tenotomies of the quadratus femoris, conjoined tendon of the short external rotators, and obturator externus made 2.5 cm medial to their insertion on the greater trochanter and a T-type capsulotomy originating below the cut edge of the obturator externus tendon and continuing circumferentially along the acetabular rim. After hip dislocation, the MFCA was cannulated and MRI scans were acquired before and after gadolinium enhancement for evaluation of femoral head perfusion, with the contralateral hip, which was left intact, used as a control. Anatomic gross dissection was performed after the injection of polyurethane in the MFCA and confirmed MFCA vessel integrity. Quantitative MRI showed that the operatively treated hip retained a mean perfusion (and standard deviation) of 95.6% ± 9.7% in the femoral head and 94.7% ± 21.5% in the femoral head-neck junction compared with the control hip (p = 0.66 and p = 0.85, respectively). Dissection after polyurethane injection confirmed that the superior retinacular and inferior retinacular arteries entering the femoral head were intact in all specimens. In a cadaveric model using gadolinium-enhanced MRI, we found that standardized modifications to the posterior approach, specifically with regard to the location of the short external rotator tenotomy and capsulotomy, successfully preserved the femoral head arterial supply after posterior surgical hip dislocation. While further research is necessary before these modifications can be recommended for widespread clinical use, the results of this study suggest the extracapsular vascular anatomy can be safely preserved during posterior surgical hip dislocation.

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

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. 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. 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. 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. II.

High prevalence of cam deformity in dysplastic hips: A three-dimensional CT study.

Cam deformity could lead to suboptimal articulation by causing secondary femoroacetabular impingement after periacetabular osteotomy; however, the inherent femoral head-neck morphology in dysplastic hips and the effect of an additional osteoarthritic deformity have not been well described. We compared femoral head-neck morphology using three-dimensional imaging of normal and dysplastic hips in pre/early (Tönnis grade 0 and 1) and advanced stage osteoarthritis (Tönnis grade 2). Using computed tomography, we measured the circumferential α-angle and head-neck offset ratio in 68 dysplastic hips and 24 normal hips. Locations of the head-neck junction were represented by the clock position. In the pre/early group, the α-angle was significantly larger at the anterosuperior and inferior aspects (1, 2, and 5-7 o'clock) and head-neck offset ratio was smaller at the anterosuperior aspect (2 o'clock) than in the control group. The α-angle was significantly larger at the anterior aspects (1-4 o'clock) in the advanced group than in the pre/early group. The maximum α-angle was most commonly found at 2 o'clock (60%, 41/68 hips) in dysplastic hips. The prevalence of cam deformity (maximum α-angle >55°) was 4.2% (1/24 hips) in the control group, 22% (11/50 hips) in the pre/early group, and 50% (9/18 hips) in the advanced group. Cam deformity, inherent in the pre/early group, was found with relatively high frequency. The higher prevalence in the advanced group reflected degeneration-modified changes. When performing periacetabular osteotomy, preoperative radiographic assessments should include the femoral head-neck junction to prevent secondary femoroacetabular impingement, especially in patients with advanced stage osteoarthritis. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1613-1619, 2016.

Patient-specific assessment of dysmorphism of the femoral head-neck junction: a statistical shape model approach.

Objective quantification of anatomical variations about the femur head-neck junction in pre-operative planning for surgical intervention in femoro-acetabular impingement is problematic, as no clear definition of average normal anatomy for a specific subject exists. We have defined the normal-equivalent of a subject's anatomy by using a statistical shape model and geometric shape optimization for finding correspondences, while excluding the femoral head-neck junction during the fitting procedure. The presented technique was evaluated on a cohort of 20 patients. Difference in α-angle measurement between the actual morphology and the predicted normal-equivalent, averaged 1.3° (SD 1.7°) in the control group versus 8° (SD 7.3°) in the patient group (p < 0.05). Defining normal equivalent anatomy is effective in quantifying anatomical dysmorphism of the femoral head-neck junction and as such can improve presurgical analysis of patients diagnosed with femoro-acetabular impingement. Copyright © 2016 John Wiley & Sons, Ltd.

Influence of geometry and materials on the axial and torsional strength of the head–neck taper junction in modular hip replacements: A finite element study

The assembly force is important in establishing the mechanical environment at the head–neck taper junction of modular hip replacements. Previous experimental results of the assembled taper junctions with different material combinations (Co–28Cr–6Mo and Ti–6Al–4V) reported similar axial strengths (pull-off loads), but lower torsional strengths (twist-off moments) for the CoCr/CoCr junction. However, mechanics of the junction and the strength behaviour have not been understood yet. A three dimensional finite element model of an isolated femoral head–neck junction was developed to explore the assembly and disassembly procedures, particularly the axial and torsional strengths for different material combinations and geometries. Under the same assembly load, the contacting length between the CoCr head and titanium neck was greater than that of in CoCr/CoCr. The contact length in the titanium neck was more sensitive to the assembly force when compared to the CoCr neck. For instance, with increasing the assembly force from 1890 to 3700N, the contact length increased by 88% for CoCr/Ti and 59% for CoCr/CoCr junctions. The torsional strength of the junction was related to the lateral deformation of the neck material due to the applied moment. The angular mismatch existing between the head and neck components was found to play the main role in the torsional strength of the junction. The smaller mismatch angle the higher torsional strength. It is suggested to consider reducing the mismatch angle, particularly in CoCr/CoCr junctions, and ensure a sufficiently high assembly force is applied by impaction for this combination.

MRI for the preoperative evaluation of femoroacetabular impingement.

Femoroacetabular impingement (FAI) refers to a condition characterized by impingement of the femoral head–neck junction against the acetabular rim, often due to underlying osseous and/or soft tissue morphological abnormalities. It is a common cause of hip pain and limited range of motion in young and middle-aged adults. Hip preservation surgery aims to correct the morphological variants seen in FAI, thereby relieving pain and improving function, and potentially preventing early osteoarthritis. The purpose of this article is to review the mechanisms of chondral and labral injury in FAI to facilitate an understanding of patterns of chondrolabral injury seen on MRI. Preoperative MRI evaluation of FAI should include assessment of osseous morphologic abnormalities, labral tears, cartilage status, and other associated compensatory injuries of the pelvis. As advanced chondral wear is the major relative contraindication for hip preservation surgery, MRI is useful in the selection of patients likely to benefit from surgery.Teaching points • The most common anatomical osseous abnormalities predisposing to FAI include cam and pincer lesions.• Morphological abnormalities, labral lesions, and cartilage status should be assessed.• In cam impingement, chondral wear most commonly occurs anterosuperiorly.• Pre-existing advanced osteoarthritis is the strongest predictor of poor outcomes after FAI surgery.• Injury to muscles and tendons or other pelvic structures can coexist with FAI.

Creating and Closing the T-Capsulotomy for Improved Visualization During Arthroscopic Treatment of Femoroacetabular Impingement

Treatment of femoroacetabular impingement through an arthroscopic approach has gained widespread popularity in recent years. Although outcomes are generally favorable, one of the most common reasons for failure is incomplete resection of cam lesions of the femoral neck. As a result, the T-capsulotomy has been introduced as a method for improving access to the femoral head-neck junction, which is not always visible through a standard interportal capsulotomy. The T-capsulotomy has the benefits of improving arthroscopic visualization of the femoral neck, reducing overall fluoroscopy exposure for the patient and surgeon, and facilitating capsular plication. We present a reliable and efficient method for creating and repairing the T-capsulotomy. We routinely perform this technique in patients with cam lesions that are too large or too distal to safely visualize and decompress through an interportal capsulotomy.

Prevalence, topographic and morphometric features of femoral cam-type deformity: changes in relation to age and gender.

Femoroacetabular impingement (FAI) syndrome is a frequent cause of pain and in recent years considered to be a precursor of premature hip osteoarthritis. The structural abnormalities which characterize FAI syndrome, such as the cam-type deformity, are associated with morphological alterations that may lead to hip osteoarthritis. The aim of this study was to determine the prevalence and topographic and morphometric features of the cam deformity in a series of 326 femur specimens obtained from a Mexican population, as well as changes in prevalence in relation to age and gender. The specimens were subdivided into groups according to gender and age. A standardized photograph of the proximal femur of each specimen was taken, and the photograph was used to determine the alpha angle using a computer program; the location of the lesion was determined by quadrant and the morphometric characteristics were determined by direct observation. The overall prevalence of cam deformities in the femur specimens was 29.8% (97/326), with a prevalence by gender of 35.2% (64/182) in men and 22.9% (33/144) in women. The mean alpha angle was 54.6°±8.5° in all of the osteological specimens and 65.6°±7.5° in those specimens exhibiting a cam deformity. Cam deformities were found topographically in the anterior-superior quadrant of the femoral head-neck junction in 86.6% (84/97) of the femurs. Deformities were found in 28.2% of the right femurs and 31.3% of the left femurs. The prevalence of cam deformity was higher in the femur specimens of young men and in those of middle-aged and older women. There were no significant differences in this deformity in relation to the alpha angle according to age and gender.

Slipped Capital Femoral Epiphysis: Long-Term Outcome and Remodelling after in Situ Fixation

In primary treatment of slipped capital femoral epiphysis (SCFE) in situ fixation reliably prevents slip progression. The aim of this study was to examine the long-term outcome of SCFE-patients treated by transfixation with Kirschner wires with a special focus on the remodelling process of the hips under this fixation method. 30 patients with stable SCFE (mean initial slip angle: 29°, mean follow-up: 10 years), who were treated with bilateral transfixation by Kirschner wires, were recruited for this study. At most recent follow-up patients were clinically and radiologically (X-ray and MRI) examined. Medical records were reviewed for previous follow-up time points. Range of motion: At most recent follow-up the mean range of motion was: extension/flexion: 0/0/121, abduction/adduction: 44/0/31, external rotation/internal rotation: 39/0/24. Nearly all dimensions of motion significantly improved during the postoperative course.Head-shaft angle: We saw a significant reduction of the mean head-shaft angle from 29° preoperatively to 11° at most recent follow-up (p<0.0001). Harris Hip Score (HHS): 24 patients had an excellent, 3 a good, 2 a fair and 1 a poor outcome defined by HHS. Remodelling: At most recent follow-up 25 patients achieved complete remodelling. The remodelling process took place especially during the first postoperative year.Angle alpha: The mean angle alpha of the affected hips at most recent follow-up was 62°. Transfixation with Kirschner wires leads to very good clinical, functional and radiologic results with a low complication rate. Furthermore the femoral head-neck junction retains enough plasticity for an active remodelling process.

Quantitative 3D analysis of bone in hip osteoarthritis using clinical computed tomography.

ObjectiveTo assess the relationship between proximal femoral cortical bone thickness and radiological hip osteoarthritis using quantitative 3D analysis of clinical computed tomography (CT) data.MethodsImage analysis was performed on clinical CT imaging data from 203 female volunteers with a technique called cortical bone mapping (CBM). Colour thickness maps were created for each proximal femur. Statistical parametric mapping was performed to identify statistically significant differences in cortical bone thickness that corresponded with the severity of radiological hip osteoarthritis. Kellgren and Lawrence (K&L) grade, minimum joint space width (JSW) and a novel CT-based osteophyte score were also blindly assessed from the CT data.ResultsFor each increase in K&L grade, cortical thickness increased by up to 25 % in distinct areas of the superolateral femoral head–neck junction and superior subchondral bone plate. For increasing severity of CT osteophytes, the increase in cortical thickness was more circumferential, involving a wider portion of the head–neck junction, with up to a 7 % increase in cortical thickness per increment in score. Results were not significant for minimum JSW.ConclusionsThese findings indicate that quantitative 3D analysis of the proximal femur can identify changes in cortical bone thickness relevant to structural hip osteoarthritis.Key Points• CT is being increasingly used to assess bony involvement in osteoarthritis• CBM provides accurate and reliable quantitative analysis of cortical bone thickness• Cortical bone is thicker at the superior femoral head–neck with worse osteoarthritis• Regions of increased thickness co-locate with impingement and osteophyte formation• Quantitative 3D bone analysis could enable clinical disease prediction and therapy developmentElectronic supplementary materialThe online version of this article (doi:10.1007/s00330-015-4048-x) contains supplementary material, which is available to authorized users.

Hip kinematics and kinetics in persons with and without cam femoroacetabular impingement during a deep squat task

BackgroundPrevious studies have indicated that hip and pelvis kinematics may be altered during functional tasks in persons with femoroacetabular impingement. The purpose of this study was to compare hip and pelvis kinematics and kinetics during a deep squat task between persons with cam femoroacetabular impingement and pain-free controls. MethodsFifteen persons with cam femoroacetabular impingement and 15 persons without cam femoroacetabular impingement performed a deep squat task. Peak hip flexion, abduction, and internal rotation, and mean hip extensor, adductor, and external rotator moments were quantified. Independent t-tests (α<0.05) were used to evaluate between group differences. FindingsCompared to the control group, persons with cam femoroacetabular impingement demonstrated decreased peak hip internal rotation (15.2° (SD 9.5°) vs. 9.4° (SD 7.8°); P=0.041) and decreased mean hip extensor moments (0.56 (SD 0.12) Nm/kg vs. 0.45 (SD 0.15) Nm/kg; P=0.018). In addition persons in the cam femoroacetabular impingement group demonstrated decreased posterior pelvis tilt during squat descent compared to the control group, resulting in a more anteriorly tilted pelvis at the time peak hip flexion (12.5° (SD 17.1°) vs. 23.0° (SD 12.4°); P=0.024). InterpretationThe decreased hip internal rotation observed in persons with cam femoroacetabular impingement may be the result of bony impingement. Furthermore, the decrease in posterior pelvis tilt may contribute to impingement by further approximating the femoral head–neck junction with the acetabulum. Additionally, decreased hip extensor moments suggest that diminished hip extensor muscle activity may contribute to decreased posterior pelvis tilt.