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Incomplete tears of the hip abductor insertion can coexist with primary hip osteoarthritis. The aim of this investigation was to test the hypotheses that: (1) the outcome of patients undergoing primary THA using a direct anterior approach would be inferior when hip abductor pathology was present; and (2) in the presence of incomplete tears, the transgluteal approach with hip abductor repair delivers a superior outcome compared to the direct anterior approach.Forty patients underwent MR imaging of the hip abductor insertion prior to THA. The grade of abductor tears was assessed, the approach used for THA was recorded, and pre- and postoperative one-year outcome scores (WOMAC, HHS) were recorded.Twenty patients showed a normal appearance of the hip abductor insertion and THA was performed using the direct anterior approach (group 1). In 20 patients partial tears of the hip abductor insertion were recognized. Eight of them had THA through a direct anterior approach (group 2) and twelve through a transgluteal approach with repair (group 3).All patients improved after surgery. Overall the WOMAC improved from 6.1 to 2.1 points and the HHS from 46 to 87 points. A significantly higher benefit in terms of the HHS was achieved in patients of group 1 (p = 0.045). No significant differences were recorded between group 2 and group 3.Improvement in outcome scores after THA using the direct anterior approach was inferior in the presence of partial hip abductor tears. The repair of partial hip abductor tears was not associated with superior clinical results.

Objectives The pathomorphology of posttraumatic acetabular dysplasia differs fundamentally from the classic developmental dysplasia of the adolescent. The aim of this report is to qualify and quantify the pathomorphologic characteristics of the posttraumatic acetabular dysplasia and to define the requirements for adequate corrective surgery in this type of dysplasia. Design and material Retrospective review of the anteroposterior (AP) radiographs of ten patients with symptomatic posttraumatic acetabular dysplasia. In five cases, false profile views and in five cases computed tomography (CT) scans were also available for investigation. Measurements of distances and angles on radiographs and CT scans were made by pencil and goniometer. Results On the AP radiographs, posttraumatic acetabular dysplasia shows uniformly deformed true pelvis with an angular deformation of the innominate bone averaging 20 degrees in the region of the acetabular fossa that causes the concavity of the pelvic brim to increase in direction of the involved acetabulum and creates both a lateral and a caudal displacement of the acetabulum, averaging twenty-three millimeters and nine millimeters, respectively. The increased width of the inner wall of the acetabulum, measuring an average of eleven millimeters, makes lateralization of the center of the femoral head reach a mean of forty-three millimeters. The acetabular deformity in all cases shows a pronounced lateral deficiency. Ventral deficiency is moderate. All ten posttraumatic dysplastic acetabuli show marked retroversion averaging 27 degrees. In contrast, the contralateral acetabuli shows a mean anteversion of 23 degrees. Conclusions The morphology of this kind of acetabular dysplasia is uniform and differs significantly from that seen in classic developmental dysplasia of the hip. For reconstructive surgery of such a hip, the challenge to abolish the lateralization of the hip joint to restore normal body weight lever arm is imperative. Because acetabular retroversion is a reproductive feature of posttraumatic dysplasia, it is important to avoid further reduction of the posterolateral containment of the femoral head and augmentation of the anterior acetabular wall, increasing the risk of anterior impingement.

Opponents associate minimally invasive total hip replacement (THR) with additional risks, potentially resulting in increased implant failure rates. The purpose was to document complications, quality of implant positioning and five-year survivorship of THR using the AMIS approach and to test the hypothesis that eventual high complication and revision rates would be limited to an early series and be avoided by junior surgeons who get trained by a senior surgeon. A consecutive series of 150 primary THR implanted during the introduction of the AMIS technique in the department was retrospectively analysed for complications, implant positioning and implant survival after a minimum of five years. Survivorship curves of implants were compared between different surgeons and time periods. Due to implant revision for any reason the five-year survival rate was 94.6%, 78.9% for the first 20 and 96.8% for the following 130 AMIS procedures (p = 0.001). The hazard ratio for implant failure was 0.979 indicating a risk reduction of 2% every further case. The five-year implant survivorship of those procedures performed by two junior surgeons was 97.7%. We conclude that adoption of AMIS temporarily exposed patients to a higher risk of implant revisions, which normalised after the first 20 cases and that experience from a single surgeon's learning curve could effectively be taught to junior surgeons.

The objective of our study was to prospectively compare the diagnostic performance of MR arthrography and conventional MRI with surgical correlation in the same patient for detecting labrum and articular cartilage defects.Twenty-eight patients (mean age, 31.8 years) underwent MR arthrography, conventional MRI, and subsequent hip surgery, which served as the reference standard. Labrum and cartilage defects were evaluated at MRI by two independent readers. A McNemar test and kappa statistics were used for statistical analysis.At surgery, 31 labral tears were identified. MR arthrography had an advantage over conventional MRI for detecting labral tears at the anterosuperior quadrant (sensitivity of MR arthrography, 81% and 69% for readers 1 and 2, respectively; sensitivity of conventional MRI, 50% for both readers); this difference in performance between MR arthrography and conventional MRI was statistically significant for reader 1 (p = 0.02) but not for reader 2 (p = 0.2). Interobserver agreement for labral tears was higher for MR arthrography (κ = 0.81) than for conventional MRI (κ = 0.63). Surgery showed 31 acetabular cartilage defects and nine femoral cartilage defects. MR arthrography had an advantage over conventional MRI for detecting acetabular cartilage defects (sensitivity of MR arthrography, 71% and 92% for readers 1 and 2, respectively; sensitivity of conventional MRI, 58% and 83%), whereas there was no advantage to using MR arthrography for detecting femoral cartilage defects with statistically significant difference for the acetabular cartilage or femoral cartilage. Interobserver agreement was slightly higher for MR arthrography (κ = 0.50) than for conventional MRI (κ = 0.40) for assessing the acetabular cartilage and was almost identical for the femoral cartilage (κ = 0.62 and 0.63, respectively).MR arthrography was superior to conventional MRI for detecting labral tears and acetabular cartilage defects and showed a higher interobserver agreement. For femoral cartilage lesions, both modalities yielded comparable results.

Introduction: Surgical hip dislocation (SHD) is an accepted standard to treat femoroacetabular impingement (FAI). However, arthroscopic techniques have gained widespread popularity and comparable results are reported. The purpose of this prospective comparative study was to test the hypothesis that, when compared to SHD, hip arthroscopy (HA) results in faster recovery, better short-term outcome, and equivalent morphological corrections. Materials and methods: 38 patients presenting with clinically and morphologically verified isolated FAI were allocated to either HA or SHD. Morphological evaluation consisted of pre- and postoperative X-rays, and arthro-MRI. Demographic data, sport activities, hospital stay, complications, and the time off work were recorded. The subjective hip value, WOMAC, HHS, and hip abductor strength were measured up to 1year. Results: Shorter hospital stay and time off work, less pain at 3months and 1year, higher subjective hip values at 6weeks and 3months, and better WOMAC at 3months were seen after HA. The HHS and the hip abductor strengths were higher in the HA group. However, morphological corrections at the head-neck-junction achieved by HA showed some overcorrection when compared to SHD. Labral refixation was performed less frequent in the HA group. Conclusion: When compared to SHD, HA results in faster recovery and better short-term outcome. However, some overcorrection of the cam deformity and limited frequency of labrum refixation with HA in this study may have a negative impact on long-term outcome

Polyethylene is widely used as a component of implants in medicine. Composites made of high-density polyethylene (HDPE) containing different amounts of amorphous calcium phosphate nanoparticles were investigated concerning their in vitro biomedical performance. The nanoparticles were produced by flame spray synthesis and extruded with HDPE, the latter complying with Food and Drug Administration regulations. Mechanical properties such as Young's modulus and contact angle as well as in vitro biomineralization of the nanocomposites hot-pressed into thin films were evaluated. The deposition of a hydroxyapatite layer occurred upon immersion in simulated body fluid. Additionally, a cell culture study with human mesenchymal stem cells for six weeks allowed a primary assessment of the cytocompatibility. Viability assays (alamarBlue and lactate dehydrogenase detection) proved the absence of cytotoxic effects of the scaffolds. Microscopic images after hematoxylin and eosin staining confirmed typical growth and morphology. A preliminary experiment analyzed the alkaline phosphatase activity after two weeks. These findings motivate further investigations on bioactive HDPE in bone tissue engineering.

Purpose: The objective of this study was to evaluate the rate, associated risk factors and outcome of insufficiency femoral neck fractures following arthroscopic femoral neck osteochondroplasty for femoroacetabular impingement. Methods: Between 2005 and 2009, a consecutive series of 376 arthroscopic femoral osteochondroplasties for femoroacetabular impingement were performed and analysed. Seven postoperative fractures were found and comprise the fracture group. The amount of femoral head-neck bone resected as assessed on follow-up cross table lateral views, as well as age, gender, height, weight and BMI, was compared between the fracture group and the entire collective. Subjective outcome was recorded using the WOMAC score. Results: Seven fractures (1.9%) were identified. All occurred in males at an average of 4.4weeks postoperatively and were considered insufficiency fractures. The fracture group had a significantly higher mean age (p=0.01) and height (p=0.013). Within the fracture group, alpha angles were lower (p=0.009) and resection depth ratios were higher (p

Background: A fracture is the most serious complication of surgical resection of the femoral head-neck junction in the treatment of cam-type femoroacetabular impingement (FAI). Purpose: To investigate the influence of resection length, width, and depth on postoperative fracture risk in activities of daily living. Study Design: Descriptive laboratory study. Methods: The femoral anatomy used for the finite element model was based upon a publicly available standardized model. For descriptive validation, the fracture location was compared with radiographs of patients who had suffered from a femoral neck fracture after surgical treatment of FAI in our institution. Additionally, a 2-part quantitative validation against previously published experimental data was performed. To simulate surgery, round resections were made in which length and width were varied at 10%, 20%, and 30%. The fracture loads were compared with published in vivo loads measured during activities of daily living with telemetric hip implants. Results: Validation showed that the model predicted fracture locations comparable with clinical cases and fracture loads within published experimental values. Femoral fracture loads were 325% more sensitive to resection deepening and 70% more sensitive to widening than lengthening. Conclusion: Although resection depth is the most important determinant of bone resistance, it should be considered in combination with resection length and width. Even a resection depth as low as 10% may lead to a fracture in case of stumbling. Clinical Relevance: We show that for resection depths of 20% or less and resection length of less than 35% of the femoral neck, normal activities of daily living are safe. Resection widths typically achieved in practice did not induce fractures during activities of daily living. Patients who have undergone surgical resection should be counseled on how to try to avoid stumbling.

Outcome after advancement of the vastus lateralis muscle for irreparable disruption of the hip abductor mechanism was evaluated in 9 patients. Seven to 10 cm defects were bridged without complications. After a mean follow-up of 33 months (range: 12-60 months), the majority of patients reported a 69% satisfaction and a reduction of both pain medication and gait assists. Six out of 9 patients would undergo the same treatment again and one was undecided. On physical examination hip function was significantly improved but still poor. A significant loss of quadriceps muscle strength was the only donor site morbidity encountered. Overall, very modest but relevant improvement of hip function can be achieved with this procedure without relevant donor site morbidity and complications.

Introduction: Compared to rigid arthroscopic optics, a flexible camera system offers theoretically significant advantages: It has the potential to adapt to the naturally curved surface of joints, to move within the joint without stress to the cartilage or capsule and thereby to reduce the number of portals needed. Former studies evaluated flexible fiberoptic systems which were insufficient regarding image resolution. This is the first report on a new flexible videoendoscope with the so called "chip-on-the-tip" technology used in human joints. Methods: With a plasma sterilized 3.9 diameter flexible video endoscopy system Visera ENF V, OLYMPUS commonly used in diagnostic rhino-laryngoscopy, we performed preliminary testing in cadaveric knee joints. After successful feasibility testing we utilized the tool in two qualitative diagnostic knee and five hip arthroscopies in combination with conventional rigid 30° and 70° arthroscopes STORZ. Results: Qualitative evaluation showed superior visualisation of the posterior aspects of the knee joint as insertion of the posterior medial and lateral meniscal horn, tibial insertion of the posterior cruciate ligament and the posterolateral capsulo-ligamentous corner with acceptable image resolution and clarity compared to the rigid arthroscope. In the hip, it was possible to pass around the femoral neck, avoiding additional portals. There seemed to be virtually no risk for cartilage damage at all. Difficulties of the system were scope handling, navigation and orientation within the joint as well as potential damage to the tool itself. Conclusion: This is to our knowledge the first report on flexible videoarthroscopy. Some of the expectations were met, such as to reach virtually every corner the joint with minimal risk for the cartilage or other joint structures and with acceptable image quality. However, there are many significant disadvantages which question the routine use of such a videoendoscopic system with its present technical features.

To evaluate the frequency of the supraacetabular fossa (SAF) (pseudodefect of acetabular cartilage) at magnetic resonance (MR) arthrography of the hip and to compare the MR findings with those from arthroscopy.All patients gave written permission for anonymized use of their medical data for scientific purposes before the imaging examination. The study was submitted to the institutional review board, and the need to obtain additional approval was waived. A medical student, a radiology fellow, and two senior radiologists reviewed 1002 consecutive MR arthrograms for the presence of an accessory bony fossa in the roof of the acetabulum, or SAF. SAF was classified into two types: type 1, which was filled with contrast material on MR arthrograms, and type 2, which was filled with cartilage. The width of the SAF was measured on coronal and sagittal MR images. MR arthrograms showing SAF were evaluated for subchondral reactions. Findings at MR arthrography were compared with those from arthroscopy in four hip joints with SAF type 1 and 13 with SAF type 2.Sixteen of the 1002 hip joints (1.6%; four female and 12 male patients; mean age, 20.1 years) had SAF type 1 (mean width, 5.2 × 4.5 mm). Eighty-nine hip joints (8.9%; 43 female and 46 male patients; mean age, 37.8 years) had SAF type 2 (mean width, 5.1 × 4.7 mm). No subchondral changes were found around the SAF. No cartilage defect was seen at the site of the SAF at arthroscopy.The high frequency of SAF on MR arthrograms (10.5%), the absence of subchondral reaction, and the absence of cartilage defects at arthroscopy indicate that the SAF of the acetabulum likely represents a variant.

Influence of femoral torsion on femoroacetabular impingement and other hip conditions is not well documented and its assessment by imaging methods during clinical work-up is not routinely performed. We studied whether physical examination could reliably measure or at least screen for gross anomalies of femoral torsion or if appropriate imaging should routinely be performed. Assessing femoral torsion of 45 volunteers using the “trochanteric prominence angle test” and magnetic resonance imaging (MRI), inter- and intra-observer reliability ranged from poor to moderate and agreement with MRI values was only fair. Considering a 5° to 10° difference of femoral torsion as clinically relevant, physical examination failed to match MRI values within ±10° in more than 50%. Arbitrarily defining thresholds for pathological femoral torsion, the “trochanteric prominence angle test” could not recognise torsions outside the >30°/20°/ Physical assessment of femoral torsion using the “trochanteric prominence angle test” does not allow reliable measurement or screening for gross anomalies. We therefore integrate an adapted MRI protocol allowing measurement of femoral torsion within our clinical work up.

Background: A history of illicit injecting drug use makes indication of total hip arthroplasty (THA) in patients with end stage hip osteoarthritis difficult, as the risk of infection with colonized strains is multiplied if the patient continues to inject or inhale illicit drugs. Methods: A retrospective survivorship analysis of a consecutive series of 27 THA in patients with a history of illicit drug use was performed. Follow-up evaluation consisted of (1) a WOMAC score, (2) a standardized interview including queries on drug habits and eventual additional medico-surgical treatments of the affected hip, (3) a clinical examination in order to complete a Harris Hip Score, (4) radiological examination and (5) blood tests (blood sedimentation rates and C-reactive protein). Defined endpoints were death, implant revised or awaiting revision for deep infection or any other reason and lost to follow-up or follow-up after at least 2years. Results: Overall, 5- and 10-year implant survival rates with failure for any reason were 61% (CI: 41;81) and 52.3% (CI: 29;76) and for septic reasons 70.6% (CI: 52;89) and 60.5% (CI: 36;85), respectively. Even if at the time of THA all patients and respective health care professionals confirmed abstinence of illicit injecting drug use, five patients reported occasional use. Declared abstinence of less than 1year before THA was associated with higher recurrence rates (p=0.001) and both with higher septic failure rates (p=0.023, p=0.061). Positive serology for human deficiency virus did not increase implant failure rates. Conclusion: We use this unacceptable high failure rate as evidence when counseling patients and their health care professionals about the appropriate treatment of osteoarthritis in patients with a history of illicit drug use. Furthermore, we support the request of hair analysis for drugs documenting abstinence of at least 1year before indicating THA

The direct anterior approach in total hip replacement anatomically offers the chance to minimise soft-tissue trauma because an intermuscular and internervous plane is explored. This motivated us to abandon our previously used transgluteal approach and to adopt the direct anterior approach for total hip replacement. Using MRI, we performed a retrospective comparative study of the direct anterior approach with the transgluteal approach. There were 25 patients in each group. At one year post-operatively all the patients underwent MRI of their replaced hips. A radiologist graded the changes in the soft-tissue signals in the abductor muscles. The groups were similar in terms of age, gender, body mass index, complexity of the reconstruction and absence of symptoms. Detachment of the abductor insertion, partial tears and tendonitis of gluteus medius and minimus, the presence of peri-trochanteric bursal fluid and fatty atrophy of gluteus medius and minimus were significantly less pronounced and less frequent when the direct anterior approach was used. There was no significant difference in the findings regarding tensor fascia lata between the two approaches. We conclude that use of the direct anterior approach results in a better soft-tissue response as assessed by MRI after total hip replacement. However, the impact on outcome needs to be evaluated further.

Introduction Total hip arthroplasty (THA) is one of the most frequently performed procedures in orthopaedics and weakness of external rotators is often recognized thereafter. However, the etiology of lateral hip pain is multifaceted. For the diagnosis of abductor tendon rupture, magnetic resonance imaging (MRI) is the gold standard. As not every patient can be subjected to MRI, a clinical diagnostic test for easy detection of lesions of the abductor tendon is missing. Here, we present the internal rotation lack sign indicating abductor tendon pathology. Methods The patient is placed in lateral position on a stretcher with hips and knees in neutral position. The knee is flexed to 45° and the hip passively abducted and elevated by the investigator. With the foot passively abducted, the patient is then asked to bring his knee in direction to the examination table. This motion is also tested passively. The test is regarded positive, if no internal rotation is possible and/or if this is painful. If groin pain is elicited during either of the exercises, the test is also rated positive. Results We evaluated this test in 20 patients clinically and by magnetic resonance imaging (MRI). All patients demonstrated a positive internal rotation lag sign. Twelve of them lag of internal rotation and evidence of anterior abductor tendon rupture on MRI, 8 with lag of internal rotation and no evidence of abductor tendon rupture. Conclusion The new clinical diagnostic sign presented here may improve the diagnosis of abductor tendon rupture in the future. Level of Evidence: Diagnostic study, level I.

Introduction: The risk that hip preserving surgery may negatively influence the performance and outcome of subsequent total hip replacement (THR) remains a concern. The aim of this study was to identify any negative impact of previous hip arthroscopy on THR. Methods: Out of 1271 consecutive patients who underwent primary THR between 2005 and 2009, 18 had previously undergone ipsilateral hip arthroscopy. This study group (STG) was compared with two control groups (CG, same approach, identical implants; MCG, paired group matched for age, BMI and Charnley categories). Operative time, blood loss, evidence of heterotopic bone and implant loosening at follow-up were compared between the STG and the MCG. Follow-up WOMAC were compared between the three groups. Results: Blood loss was not found to be significantly different between the STG and MCG. The operative time was significantly less (p

Introduction Les performances tribologiques d’un polyethylene sont influencees par sa procedure de fabrication et son mode de fixation. Le but de cette etude retrospective etait d’evaluer a 5 ans minimum de recul les resultats fonctionnels et l’usure sur une serie consecutive d’arthroplasties totales de hanche utilisant un insert en polyethylene hautement reticule de premiere generation dans une cupule metal-back non cimentee. Materiel La serie comportait 80 arthroplasties totales de hanche non cimentees realisees entre aout 2005 et decembre 2007 chez 80 patients (43 femmes et 37 hommes) âges en moyenne de 62,7A 8,9 ans. Pour tous les patients, un couple de frottement associant un insert en polyethylene hautement reticule de premiere generation (irradiation gamma a 100 Mrads, stabilisation a 150 °C, temperature de refroidissement controlee, sterilisation finale a l’oxyde d’ ethylene) et une tete de 28 mm en chrome–cobalt a ete utilise. Le critere majeur d’evaluation etait la penetration de la tete femorale (incluant fluage et usure vraie) dans la cupule mesuree a 5 ans minimum de recul selon la methode de Martel (Hip Suite Analysis 8.0.4). Par ailleurs, une evaluation fonctionnelle selon le score de WOMAC a ete realisee. Resultats Parmi les 80 patients inclus, 67 avaient des donnees cliniques et radiologiques completes a un recul moyen de 5,5 A 0,47 ans (5–6,8). La penetration moyenne a 5 ans de recul de la tete femorale dans l’insert etait de 0,0325 mm et le taux de penetration moyen de 0,0059 mm an. Le score de WOMAC pre operatoire etait en moyenne de 16,5 A 5,93 versus 4,12–5,5 a 5 ans de recul (p Discussion et conclusion Les resultats de cette etude de cohorte retrospective indiquent un faible taux d’usure a 5 ans minimum de recul associe a un insert en polyethylene hautement reticule fortement irradie et refondu. L’utilisation d’un insert en polyethylene hautement reticule dans un metal-back semble etre une option fiable a condition de respecter une epaisseur minimale de polyethylene.

To assess the association between trochanteric surface irregularities seen on conventional radiographs and magnetic resonance (MR) evidence of abductor tendon abnormalities.A total of 150 consecutive patients were evaluated in this retrospective study (age range, 21-88 years; mean age, 58.7 years ± 16.1 [standard deviation]; 57 men, 93 women). Because patients' rights are protected by a procedure in which they are asked to provide general approval for their records and images to be reviewed for scientific purposes, specific approval by the institutional review board was not required. Two readers independently analyzed conventional radiographs and MR images of the hip. Trochanteric surface was graded on conventional radiographs as normal, osseous irregularities extending 1-2 mm, or osseous irregularities extending more than 2 mm. On MR images, the gluteus minimus and gluteus medius tendons were classified as normal or as having tendinopathy or a partial- or full-thickness tear. Logistic regression analysis and the Fisher exact test were used for statistical analysis. Sensitivity, specificity, accuracy, positive and negative predictive values, and positive likelihood ratio were calculated. To assess interobserver agreement, a κ statistic was used.The positive predictive value of surface irregularities larger than 2 mm for MR tendinopathy or a partial- or full-thickness tear was 90% (37 of 41 patients). The sensitivity of radiographic changes was 40%; the specificity, 94%; the accuracy, 61%; the negative predictive value, 49%; and the positive likelihood ratio, 5.8. Interobserver agreement for detection of trochanteric surface irregularities on conventional radiographs ranged from 0.28 to 0.76.Pronounced (2 mm) surface irregularities of the greater trochanter on conventional radiographs were associated with abductor tendon MR abnormalities.

The abductor release sometimes does not heal after a transgluteal approach for hip arthroplasty. Factors influencing the success of subsequent repair are unclear. We used magnetic resonance imaging (MRI) to compare the condition of the gluteus medius with clinical outcome after late repair of abductor dehiscence in 12 total hip patients. Evaluation included a pain rating, gait evaluation, Trendelenburg test, strength grading, and Harris Hip Score. Most had both prerepair and postrepair MRI studies to assess the repair and to grade abductor muscle fatty degeneration. Two repairs without MRI were explored surgically. Although average pain, limp, and strength scores improved significantly, rerupture occurred in 4 subjects and fatty degeneration in the gluteus medius did not improve, even with intact repair. Nine patients were satisfied; 7 of these had an intact repair. Magnetic resonance imaging and operative observations suggest that chronic degeneration in the abductor mechanism is the major impediment to successful repair.

Objective: To develop and assess a technique to evaluate cam type femoroacetabular impingement (FAI) using ultrasound (US). Methods: Fifty patients (24 women, 26 men) were included (mean age: 39.1years; age range: 16-59). US images of the anterior and anterosuperior contour of the femoral neck were obtained and analysed in 50 patients. Non-spherical shape of the head-neck junction (cam deformity), bony protuberances at the femoral neck, shape of the femoral neck (waist deficiency) and alpha angle were assessed. Magnetic resonance (MR) arthrography served as the standard of reference. Diagnostic performance and receiver operating characteristics (ROC) curves were calculated. Results: Based on MR arthrography 28 patients had cam-type FAI. On US, an anterosuperior cam deformity was seen in 40/44 patients (Reader 1/Reader 2; sensitivity 93%/89%, specificity 36%/14%). A bony protuberance anterosuperiorly in 23/13 patients (sensitivity 71%/32%, specificity 86%/82%) and an anterosuperior waist deficiency in 19/35 patients (sensitivity 25%/54%, specificity 100%/54%). Sensitivity and specificity of the other criteria were lower than 70% (average of Reader 1 & 2). Conclusion: A technique to evaluate cam type FAI using US is presented. The detection of an anterosuperior cam deformity is sensitive, and presence of an anterosuperior bony protuberance is specific for cam FAI. Alpha angle measurements are not helpful in establishing the diagnosis

Interest in acetabular version arose from the study of unstable developmental dysplastic hips (DDH). Initial studies and clinical observations described the dysplastic hip as being excessively anteverted. Doubts on this view arose from analysis of complications such as persistent posterior subluxation after acetabular reorienting procedures. Computed tomography fails to determine conclusively whether or not the dysplastic acetabulum is abnormally anteverted. Controversy evolves from different methods of measuring and from the fact that the acetabular opening gradually spirals from mild anteversion proximally to increasing anteversion distally. This renders the measurement of version dependent on pelvic inclination and the level of the transverse CT scan slice. On an orthograde pelvic radiograph, both pelvic inclination and rotation can be controlled. Therefore, acetabular version is best estimated based on the relationship of the anterior and posterior acetabular rims to each other on an orthograde pelvic radiograph. Acetabular retroversion has been found to be a characteristic feature of specific hip disorders such as post-traumatic dysplasia, proximal femoral focal deficiency and bladder exstrophy. In addition, acetabular retroversion has been described in DDH as well as in dysplastic hips in the context of neuromuscular and genetic disorders. Iatrogenic acetabular retroversion can also result from corrective pelvic osteotomies in childhood. Finally, retroverted acetabula may be found in otherwise nondysplastic hips. The relevance of acetabular retroversion is twofold: First, it demands a more individualized approach to acetabular dysplasia because the presence of retroversion will affect the manner in which the corrective osteotomy should be done. Second, the long-term effect of acetabular retroversion is harmful.

The objective of this study was to show model-based economic consequences of minimal invasive surgery total hip arthroplasty (MIS THA). The model is based on hospital and rehabilitation costs and lowering of loss of productivity. This study used conventional THA data from Switzerland and cost-effectiveness MIS THA analysis from the United States. According to our model, a total of € 42.1 – 70.1 million can be saved annually in Switzerland when using MIS THA instead of conventional THA. Annual savings of € 7,8 – 12,9 million result from the significantly shorter hospital stay. The savings potential for rehabilitation costs is € 10,5 – 17,5 million annually. In addition, the productivity loss for the economy is lowered by € 23.8 – 39.7 million annually. According to this economic study we recommend the introduction of MIS techniques in THA. MIS THA surgical techniques may allow the reduction of healthcare costs. Despite the promising economic advantages of MIS THA, clinical studies are necessary to prove long-term benefits.

To retrospectively assess the frequency and performance of magnetic resonance (MR) arthrography to help diagnose acetabular cartilage delamination in femoroacetabular impingement (FAI).Institutional review board approval and informed consent were waived for this retrospective study. Forty-four consecutive patients with FAI of the cam type were included (mean age, 30.7 years; range, 16-49 years), including 30 men (mean age, 30.5 years; range, 16-49 years) and 14 women (mean age, 31.4 years; range, 18-48 years). The inclusion criteria were no previous surgery, surgery within 3 months after MR imaging, and availability of a detailed surgical report with acetabular cartilage findings. MR arthrographic findings were assessed independently by two blinded readers. Findings at surgery served as reference standard. Sensitivity, specificity, accuracy, and kappa statistics for interobserver agreement were calculated.At surgery, acetabular cartilage delamination was seen in 23 (52%) of 44 patients (mean size of cartilage flap from acetabular rim, 7.6 mm; range, 2-30 mm). At MR, patients with fluid signal intensity under the cartilage delamination had a respective sensitivity, specificity, and accuracy of 22%, 95%, and 57% for reader 1 and 30%, 95%, and 61% for reader 2. A hypointense line in the acetabular cartilage on sagittal three-dimensional double-echo steady-state images with water excitation demonstrated moderate diagnostic performance (respective sensitivity, specificity, and accuracy were 70%, 57%, and 64% for reader 1 and 70%, 62%, and 66% for reader 2). Hypointense areas in the acetabular cartilage were quite specific on both coronal intermediate-weighted fat-saturated images (respective sensitivity, specificity, and accuracy were 52%, 90%, and 70% for reader 1 and 74%, 90%, and 82% for reader 2) and coronal T1-weighted images (respective sensitivity, specificity, and accuracy were 35%, 90%, and 61% for reader 1 and 61%, 95%, and 77% for reader 2).Cartilage delamination is common in patients undergoing surgery for FAI. Fluid under the cartilage delamination is a specific but rare finding. Hypointense areas in the acetabular cartilage seen on intermediate-weighted fat-saturated or T1-weighted images appear to be helpful diagnostic criteria.

Precision is important if small polyethylene wear rates are to be detected early and in small sample sizes. Using an automatic, computerized algorithm relying on a synthetic X-ray generated from a computer-assisted design (CAD) model of the implant may significantly improve precision of linear wear measurements. We compared this method to provide improved in vivo precision compared to the widely used Hip Analysis Suite software (version 8.0.1.7). Two anterior-posterior pelvic X-rays were taken on the same day of 18 total hip implants, and wear was measured by three observers using the two methods. Expected real wear was zero and defined as a reference value. Two sources of variability were estimated: one due to the instrument, and one due to different operators. A Wilcoxon Signed Rank Test was used for statistical comparisons. The overall precision (instrument variability and multioperator variability) given a 95% precision limit was significantly higher (p < 0.001) using the proposed method (+/-0.15 mm) when compared to the Hip Analysis Suite (+/-0.84 mm). Due to the availability of the full CAD data of the implant and to further automation of the measuring process, the newly proposed method provided improved precision in measuring polyethylene wear.

We have reviewed a group of patients with iliopsoas impingement after total hip replacement with radiological evidence of a well-fixed malpositioned or oversized acetabular component. A consecutive series of 29 patients (30 hips) was assessed. All had undergone a trial of conservative management with no improvement in their symptoms. Eight patients (eight hips) preferred continued conservative management (group 1), and 22 hips had either an iliopsoas tenotomy (group 2) or revision of the acetabular component and debridement of the tendon (group 3), based on clinical and radiological findings. Patients were followed clinically for at least two years, and 19 of the 22 patients (86.4%) who had surgery were contacted by phone at a mean of 7.8 years (5 to 9) post-operatively. Conservative management failed in all eight hips. At the final follow-up, operative treatment resulted in relief of pain in 18 of 22 hips (81.8%), with one hip in group 2 and three in group 3 with continuing symptoms. The Harris Hip Score was significantly better in the combined groups 2 and 3 than in group 1. There was a significant rate of complications in group 3. This group initially had better functional scores, but at final follow-up these were no different from those in group 2. Tenotomy of the iliopsoas and revision of the acetabular component are both successful surgical options. Iliopsoas tenotomy provided the same functional results as revision of the acetabular component and avoided the risks of the latter procedure.

The development of degradable bone cements with a mineral composition similar to natural bone was investigated using highly reactive calcium phosphate phases as starting materials. Mixtures of XRD-amorphous, glassy tricalcium phosphate (amorphous-TCP) nanoparticles of 25–60 nm size and micron sized, milled α-TCP were set by hydration with sodium phosphate buffer and investigated for possible application as single component calcium phosphate cements (CPCs). Isothermal calorimetry allowed a precise tracking of the setting process. Amorphous-TCP nanoparticles converted into calcium deficient hydroxyapatite with cement setting times below 12 min. The total energy release by the material during hardening corroborated the importance of high specific surface area and phase composition, that is, amorphous state of the nanometric starting material as repeatedly suggested earlier. The phase composition of the resulting CPCs was characterized by X-ray diffraction before and after setting. The morphology was investigated by nitrogen adsorption, scanning, and transmission electron microscopy and revealed the formation of highly porous calcium deficient hydroxyapatite with specific surface areas of up to 160 m2 g−1 after setting. In contrast to the very fast reaction time and highest specific surface area, the mechanical stability of the resulting CPC is still insufficient and requires further improvement. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2007

The aim of this study has been to explore and verify whether the use of a previously designed Analysis-by-Synthesis algorithm is capable to precisely measuring implant wear. The abrasion of polyethylene particles is seen as the main reason for the loosening of prosthetic components in the hip. It lies in the sub-millimeter range, and precision is a crucial point in wear measurement. In the Analysis-by-Synthesis algorithm, the synthetic X-ray image of the implant is matched to its original X-ray projection. This intensity based approach and the use of X-ray images with their inherent high resolution allow principally precise measurements. Wear has been defined based on the estimated implant parameters and under minimization of the impact of the main sources of error. The latter was theoretically studied in a sensitivity analysis. The use of the algorithm was tested in vitro as well as in vivo. In experimental data, the accuracy and the impact of the pelvic position and orientation were studied. The precision was assessed using dual radiographs of 20 patients with total hip replacement. A standard deviation of 49 lm was found. � 2006 Elsevier B.V. All rights reserved.

The aim of the study was to evaluate prospectively the technical feasibility and discomfort of two different injection techniques for MR arthrography of the hip. Sixty-one consecutive patients undergoing MR arthrography of the hip (68 hips) were randomly injected either at the femoral head (36 hips) or the femoral neck (32 hips). The patients rated discomfort during and 0-72 h after arthrography using a visual analogue scale (VAS, 0="did not feel anything", 100="unbearable"). The volume injected, the distance between the needle tract and the neurovascular bundle, the duration of the procedure and the extra-articular contrast leakage were measured. No significant differences were found for the volume injected, the distance between the needle tract and the neurovascular bundle, or the procedure duration. Volume of extra-articular contrast leakage was statistically significantly different (head 1+/-2 cm(3), neck 3+/-5 cm(3), P=0.024). The VAS score for needle advancement was significantly different (head 25+/-20, neck 19+/-23, P=0.031). No significant differences were found for the VAS score regarding delayed discomfort. Before the examination the arthrography-related discomfort was overestimated by 74% (50/68), correctly anticipated by 22% (15/68) and underestimated by 4% (3/68) of the patients. MR-related discomfort was overestimated by 32% (22/68), correctly anticipated by 57% (39/68) and underestimated by 10% (7/68) of the patients. Both hip puncture techniques were well tolerated. The neck injection technique produced less discomfort and was associated with greater extra-articular contrast leakage.

Management of clinically stable hips with an increased age-related acetabular index (AI) remains controversial. The authors' purpose was to document the natural history of such hips. Sixty-eight clinically stable hips with an increased age-related AI were followed up for a mean of 9.5 years. Four patterns of evolution were observed: type 1 (25 hips) had rapid progression to normal range in the first 2 years; type 2 (19 hips) had slow improvement, with AI values reaching the normal range between 4 and 11 years; type 3 (20 hips) had improved hip morphology with persistence of minor deviations from the normal values; and type 4 (4 hips) showed no improvement. Initially, none of the hips with type 1, 2, or 3 pattern showed radiologic signs of displacement; in contrast, all our type 4 hips were radiologically eccentered. Clinically stable and radiologically well-centered hips with an increased age-related AI improved spontaneously without treatment. For these cases, clinical and radiologic follow-up is all that is needed.

Retroversion of the acetabular dome has been associated with hip pain and osteoarthritis in several studies. Nevertheless, this acetabular alignment received little attention when studying the radiological outcome of pelvic osteotomies in childhood. We therefore reviewed the charts and X-rays of 73 patients with congenital dislocations, who underwent 97 pelvic osteotomies in childhood. We focussed our attention on anterior overcoverage or retroversion of the acetabular dome, respectively. Eighty-six Salter and 11 LeCoeur osteotomies were performed on patients with a mean age of 4.8 years. The mean age at last X-ray documentation was 16.5 years. The version of the acetabular dome was estimated qualitatively from the relationship of the anterior and posterior border to each other and measured semiquantitatively using templates developed by Hefti. According to Lequesne's criteria 94% of the hips were normal or borderline at maturity. A retroverted acetabular dome was present in 27% and averaged -15 degrees. It was more frequent (60% versus 24%) and more pronounced (-16 degrees versus +5 degrees) after Le Coeur's than after Salter's osteotomy and in the residually dysplastic hips (83% versus 22%; -15 degrees versus +3 degrees). It is suggested that anterior overcoverage of the femoral head results from ignorance, when choosing the type and performing the pelvic osteotomy, of where coverage needs to be improved in an individual hip. We question the long-term outcome of these hips because such rotational misalignment has been suggested to be associated with early hip pain and osteoarthritis. In order to avoid such misalignment, preoperative evaluation of where coverage needs to be improved in an individual hip and efforts for better intraoperative control of acetabular reorientation should be made.

Introduction Little attention is paid to insertion site morbidity associated with antegrade femoral nailing. However, residual peritrochanteric pain after nailing is not uncommon. Additionally, the end branches of the medial femoral circumflex artery (m.f.c.a.) supplying the femoral head are in close proximity to the insertion site of the nail, and the occurrence of avascular necrosis of the femoral epiphysis after nailing in adolescents is rather frequent. Objective The aim of this study was to assess iatrogenic soft tissue injuries at the site of nail insertion. Materials and methods Nailing with a reamed AO universal femoral nail was performed on sixteen adult cadavers followed by dissection of the proximal part of the femur to assess possible damage to the soft tissues. Three entry portals were defined. (A) entry portal lateral to the junction of the neck and the greater trochanter; (B) entry portal at the base of the greater trochanter anterior to a line along the longitudinal axis of the femoral neck; and (C) entry portal at the base of the greater trochanter posterior to a line along the axis of the femoral neck (at the piriformis fossa). Results In Group A, partial avulsion of the piriformis and the obturator internus tendon were present in four and in one of five specimens, respectively. Group B showed injuries to the piriformis tendon in two and to the gluteus minimus tendon in one of four cases. In Group C, partial avulsion of the piriformis, obturator internus, and obturator externus tendon were encountered in five, six, and two of seven specimens, respectively. Anterior branches of the ramus profundus of the m.f.c.a. within the synovial fold were damaged in all of these cases. Conclusion To select the best nail entry portal, the ease of nail insertion must be weighed against the resulting soft tissue damage at the site of insertion. The nail entry portal at the piriformis fossa, although geometrically ideal and most recommended, causes the most significant damage to muscle and tendons as well as to the blood supply to the femoral head. Therefore, even if reported only once, the occurrence of avascular necrosis of the femoral head after nailing in adults is a possible complication of this nail entry portal. The authors therefore prefer to avoid this entry portal in every case. The nail entry portal anterior to the longitudinal axis of the femoral neck, as in group B, although better with respect to the soft tissue damage, has the worst geometric and biomechanical disadvantages. The results of the current study favor the nail entry portal lateral at the greater trochanter as in Group A, which is equal to the entry portal B with respect to the soft tissue damage but allows introduction of the nail into the medullar cavity without difficulties.

Purpose Mild slipped capital femoral epiphyses (SCFE) nevertheless show significant femoral head–neck deformities which may put cartilage and acetabular labrum at risk. Whether this deformity can be restored to normal has not yet been described in the literature. Methods In a prospective follow-up study, 14 patients with mild SCFE underwent in situ fixation with a single 6.5-mm cancellous, partially threaded screw. In 14 patients arthroscopic osteochondroplasty was performed, and in 13 patients pre- and postoperative measurements of the α-angle were made using antero-superior radial magnetic resonance imaging. Results After arthroscopic osteochondroplasty, the mean α-angle decreased from 57° (range 50°–74°) to 37° (range 32°–47°; p < 0.001). Six patients showed beginning degenerative intra-articular changes (four antero-superior cartilage and three antero-superior labrum lesions) at the time of hip arthroscopy. No intra-operative complications occurred. In one patient, arthroscopic debridement was necessary due to arthrofibrosis and persistent pain. Conclusion Arthroscopic osteochondroplasty can successfully correct the antero-superior α-angle in patients with mild SCFE to normal values. Clinical randomized controlled studies with long-term follow-up are required to find evidence of improved functional and radiographic mid- and long-term outcome compared to in situ fixation alone.

Background In recent years, the number of lung transplants has increased rapidly, with higher quality of life and improved survival rates in transplant recipients, including patients with advanced age. This, in turn, means that more transplant recipients will seek musculoskeletal care to treat degenerative joint disease and also trauma incidents. Safety concerns regarding elective and posttraumatic hip arthroplasty in transplant patients include an increased risk of infection, wound healing problems, periprosthetic fractures and loosening of the implants. Methods Clinical outcomes and safety aspects were retrospectively reviewed for five primary total hip arthroplasties (THA) in lung transplant recipients with minimal follow-up of two years at average of 2.6 (2–11) years. Patients were recruited from the Zurich Lung Transplant Center comprising of a cohort of 253 patients between January 1st, 2004 and December 31st, 2013. Results All five patients subjectively reported excellent outcomes after THA with a final average Harris Hip Score of 97 (86–100). One 71-year-old patient died 26 months after THA unrelated to arthroplasty. One superficial wound healing disturbance was documented. No periprosthetic fractures, no dislocations, no periprosthetic infections, no further revision surgery, no implant loosening was observed. Conclusions In conclusion, THA can be safely and successfully performed even in lung transplant patients under long-term immunosuppressive therapy and polymedication, provided a multidisciplinary approach can be granted.

During recent years the acetabular labrum has gained increased interest because its degeneration frequently is found in association with early osteoarthritis of the hip. To determine spatial distribution of labral degeneration in the aged hip and to identify the pathologic features triggering this event, an anatomic postmortem and an intraoperative in vivo study were done in 30 cadavers (range, 60-90 years) and in 18 elderly patients (range, 69-97 years) who had hemiarthroplasty for displaced femoral neck fractures. In both groups, no gross anatomic or radiographic abnormalities suggesting advanced osteoarthritis were present. All cadaveric acetabuli (30 of 30) revealed labrum and cartilage damage. Labrum damage (17 of 18) and cartilage lesions (16 of 18) occurred less frequently and were smaller in the elderly patients. Peripheral joint degeneration was most frequent at the superior acetabular rim close to the anterior inferior iliac spine. More centrally localized cartilage lesions were present in 47% of cadavers and in 28% of patients. The majority of femurs (cadavers) (80%) showed reduced narrowing at the anteromedial femoral head-neck junction causing impingement against the corresponding acetabular rim or squeezing of this area into the joint during flexion, whereas the femoral head cartilage appeared normal in all but one hip. Acetabular rim degeneration is a constant finding in the aged hip, which seems to be triggered by femoroacetabular impingement.