To quantify the acetabular coverage of the femoral head, Lequesne's vertical-center-anterior edge (VCA) angle is used on the false profile view. Lateral coverage is determined by Wiberg's lateral-center-edge (LCE) angle on an ap pelvic view. The delimitation of the weightbearing area is defined by the end of the subchondral sclerosis line for both views. To our knowledge the exact anatomic location of the points used for measurement on the acetabular rim are not known.

Six hips from three cadaver pelvises (3 male and 3 female) were investigated. The anterior and lateral points of interested were identified radiographically using fluoroscopy and marked with 1mm ceramic bullets. Standard false profile views and ap pelvic views in neutral inclination and rotation were taken to check the correct location of the ceramic bullets. A CT of each pelvis was made to locate the ceramic bullets and to define the exact anatomic location of the measurement points on the o'clock position. 6 o‘clock was defined as the midpoint between anteroinferior and the posteroinferior rim edges. Values were normalized for a right hip.

The mean clockface location for the VCA was 1:33 (range, 1:15 to 1:40) and for the LCE 0:38 (range, 0:20 to 0:50).

The LCEA is slightly anterior to the 12 o'clock position and remains useful to quantify the lateral coverage. Surprisingly, the point used for measuring the VCA is only about 30° (1h) anterior of the point used for measuring the LCEA. Its value for determining anterior cover has to be questioned. The discrepancy to other studies in the literature is because this study identifies and measures the end of the weight bearing zone, and not the border of the bony acetabulum.

The definition of osseous instability in radiographic borderline dysplastic hips is difficult. A reliable radiographic tool that aids decision-making specifically, a tool that might be associated with instability-therefore would be very helpful for this group of patients. The aims of this study were:

(1) To compare a new radiographic measurement, which we call the Femoro-Epiphyseal Acetabular Roof (FEAR) index, with the lateral centre-edge angle (LCEA) and acetabular index (AI), with respect to intra- and interobserver reliability; (2) to correlate AI, neck-shaft angle, LCEA, iliocapsularis volume, femoral antetorsion, and FEAR index with the surgical treatment received instable and unstable borderline dysplastic hips; and (3) to assess whether the FEAR index is associated clinical instability in borderline dysplastic hips.

We defined and validated the FEAR index in 10 standardized radiographs of asymptomatic controls using two blinded independent observers. Interrater and intrarater coefficients were calculated, supplemented by Bland-Altman plots. We compared its reliability with LCEA and AI. We performed a case-control study using standardized radiographs of 39 surgically treated symptomatic borderline radiographically dysplastic hips and 20 age-matched controls with asymptomatic hips (a 2:1 ratio), the latter were patients attending our institution for trauma unrelated to their hips but who had standardized pelvic radiographs between January 1, 2016 and March 1, 2016.

Patient demographics were assessed using univariate Wilcoxon two-sample tests. There was no difference in mean age (overall: 31.5 ± 11.8 years [95% CI, 27.7–35.4 years]; stable borderline group: mean, 32.1± 13.3 years [95%CI, 25.5–38.7 years]; unstable borderline group: mean, 31.1 ± 10.7 years [95% CI, 26.2–35.9 years]; p = 0.96) among study groups. Treatment received was either a periacetabular osteotomy (if the hip was unstable) or, for patients with femoroacetabular impingement, either an open or arthroscopic femoroacetabular impingement procedure. The association of received treatment categories with the variables AI, neck-shaft angle, LCEA, iliocapsularis volume, femoral antetorsion, and FEAR index were evaluated first using Wilcoxon two-sample tests (two-sided) followed by stepwise multiple logistic regression analysis to identify the potential associated variables in a combined setting. Sensitivity, specificity, and receiver operator curves were calculated. The primary endpoint was the association between the FEAR index and instability, which we defined as migration of the femoral head either already visible on conventional radiographs or recentering of the head on AP abduction views, a break of Shenton's line, or the appearance of a crescent-shaped accumulation of gadolinium in the posteroinferior joint space at MR arthrography.

The FEAR index showed excellent intra- and interobserver reliability, superior to the AI and LCEA. The FEAR index was lower in the stable borderline group (mean, −2.1 ± 8.4; 95% CI, −6.3 to 2.0) compared with the unstable borderline group (mean, 13.3 ± 15.2; 95% CI, 6.2–20.4) (p < 0.001) and had the highest association with treatment received. A FEAR index less than 5° had a 79% probability of correctly assigning hips as stable and unstable, respectively (sensitivity 78%; specificity 80%).

A painful hip with a LCEA of 25° or less and FEAR index less than 5° is likely to be stable, and in such a situation, the diagnostic focus might more productively be directed toward femoroacetabular impingement.

Introduction

The limited field of view with less-invasive hip approaches for total hip arthroplasty can make a reliable cup positioning more challenging. The aim of this study was to evaluate the accuracy of cup placement between the traditional transgluteal approach and the anterior approach in a routine setting.

Introduction

Obesity is known to influence surgical risk in total hip replacement (THR), with increased Body Mass Index (BMI) leading to elevated risk of complications and poorer outcome scores. Using a multinational trial data of a single implant, we assess the impact of BMI and regional variations on Harris Hip scores (HHS).

INTRODUCTION

The lifetime of UHMWPE implants may be limited by wear and oxidative degeneration. Wear produced particles are in general biologically active, and may induce osteolysis. As threshold of PE wear rate below which osteolysis is rarely observed is postulated to be less tahn 0.1 mm per year. Moreover, PE delamination and breakage are consequences of the embrittlement of the PE due to oxidation. Both demonstrate, that improving the clinical behaviour of UHMWPE means reduction of wear particles. The first can be achieved by cross-linking the second by the anti-oxidative stabiliser vitamin E. The highly cross-linked PE vitamys ® used for the isoelastic monobloc cup RM Pressfit (Mathys AG Bettlach, Bettlach, Switzerland) is mixed with 0.1% of synthetic vitamin E and is the first and only highly cross-linked PE used in total hip replacement that meets all requirements for the best grade UHMWPE in yield strength, ultimate tensile strength and elongation at break.

Introduction: Periacetabular osteotomy is a complex procedure which is associated with significant complications during the learning period and difficult to maintain such expertise when it is undertaken infrequently. Results were reviewed to determine if this difficult PAO procedure can be safely learnt by a process of mentoring and review.

Methods: A structured mentoring program was adopted by the senior author. A double approach was used in the first 11 cases to enhance exposure and minimise the risk of complications. Fifteen osteotomies have subsequently been undertaken using a single approach. The median patient age was 28 years (13–41 years). The median follow-up was 5 years (2–14 years). The clinical and radiographic results were examined.

Results: Two cases in the double approach series progressed to total hip replacement and there were two other major reoperations. Two cases in the single approach series had an ischial non-union not requiring reoperation. The median Harris hip score at latest review was 82 (35–100) and 80 (26–100) for the double and single approach series respectively. All radiographic indices indicated correction of the acetabulum for both series.

Discussion and Conclusion: A structured program of mentoring and review has allowed a complex surgical procedure to be learnt and surgical expertise maintained at a distant centre while avoiding the complications previously associated with the learning curve and achieving the acetabular correction similar to the originator of the procedure.

Purpose: The purpose of this study was to examine the arthroscopy findings in the hips of patient with persistent pain after surgical hip dislocation for femoroacetabular impingement syndrome.

Type of study: Retrospective, consecutive series of patients

Patients and Methods: Sixteen consecutive patients (6 male/10 female; average age 33,5 years 19–60y) with persistent pain after surgical hip dislocation for the treatment of femoroacetabular impingement were included. At the index surgery, all patients had an osteo-chondroplasty of the head neck junction and a resection of the acetabular rim with reattachment of the labrum in 9 cases. All patients had a preoperative arthro-MRI and were treated with arthroscopy of the hip.

Results: At arthroscopy all reattached labra were stable. In the cases without preservation of the labrum, the joint capsule was attached level with the acetabular rim and had important synovitis. All patients had adhesions between the neck of the femur and joint capsule or between labrum and capsule. In 3 patients the arthroscopic procedure was technically limited by massive thickening of the capsule. Overall 75% (12 of 16) patients showed less pain or were pain free. MDA improved from preoperatively 13 to 16 points at last follow up.

Conclusions: Persistent pain after surgical dislocation of the hip could result from intraarticular adhesions that can be shown in the MRI. Hip arthroscopy after previous surgery can be demanding due to scarring. If the adhesions can be released good results can be achieved. Hip arthroscopy is a save therapeutical tool to treat patients with intraarticulary adhesions after surgical dislocation of the hip for femoroacetabular impingement.

Background: Acetabular retroversion has been proposed to contribute to the development of osteoarthritis of the hip. For the diagnosis of this condition, conventional AP pelvic radiographs may represent a reliable, easily available diagnostic modality as they can be obtained with a reproducible technique allowing the anterior and posterior acetabular rims to be visible for assessment. This study was designed to

establish a method to directly quantify anatomic acetabular version on AP pelvic radiographs and to

Methods: Using 43 desiccated pelves (86 acetabuli) the anatomic acetabular versions were measured at three different transverse planes (cranially, centrally and caudally). From these pelves, standardized AP pelvic radiographs were obtained. To directly measure central acetabular version (AV), a modified radiographic method is introduced for the use of AP pelvic radiographs. Moreover, the validity of the radiographic “cross-over-sign” to detect cranial acetabular retroversion was determined.

Results: The mean central and caudal anatomic AV were approximately 20°, the mean cranial AV was 8°. Cranial retroversion (AV < 0°) was present in 19 of 86 hips (22%). A linear correlation was found between the central and cranial AV. Below 10° of central AV, all acetabuli were cranially retroverted. Between 10° and 20°, 30% of the acetabuli were cranially retroverted and above 20°, only one of 45 acetabuli was cranially retroverted. The radiographic measurement of the central AV (20.3° ± 6.5) correlated strongly with the anatomic AV (20.1° ± 6.4). The sensitivity of the ‘cross-over-sign’ to detect an cranial acetabular anteversion of less than 4° was 96%, its specificity 95%, and the positive predictive and negative predictive values 90% and 98%, respectively.

Conclusions: The cranial AV is on average 12° lower than the central AV, with the latter directly measurable from AP pelvic radiographs. A central AV of less than 10° was associated with cranial retroversion. The presence of a positive ‘cross-over-sign’ is a highly reliable indicator of cranial AV of < 4°.

Introduction: In the treatment of polytraumatised patients acetabular fractures are challenging because of the necessity of perfect open reduction of the articular surface over an anatomy respecting approach. Luxation of the femoral head with accompanying Pikin fracture, interponated fragments and labral lesions are relevant additional injuries compromising a good result after correct operative treatment. The choice of the approach is a limiting factor for the visualization of the hip joint and is of capital importance for adequate internal fixation. A modified Kocher-Langenbeck- approach with osteotomy of the grater trochanter allows an anatomic reduction under perfect visualization with protection of the soft tissue.

Patients and Methods: This prospective study was accomplished from 1995–2003 including 60 patients (16 female, 16–80years) with an actabulary fracture (posterior wall-, T-type-, and transverse fracture) treated over a modified Kocher-Langenbeck-appraoch with osteotomy of the grater tro-chanter. The included patients had a minimum follow-up of 2 years with clinical and radiological examination. The outcome was assessed with the Merle d’Aubigné-score and degenerative changes with the Tönnis classification.

Results: Within 57 patients an anatomic reduction was achieved. In 3 patients the reduction was not anatomical but satisfactory (1–3mm). Arthrotic changes in the minimujm follow-up of 2 years were observed in 14 patients (8 Ps grade I, 3 Ps grade II, 3 Ps grade III). In 3 patients posttraumatic arthritis had to be treated with THR (1, 3, 8 years postoperatively). A avascular necrosis was not objected.

Conclusion: The treatment of suitable acetabular fractures over a modified Kocher-Langenbeck-approach with a osteotomy of the greater trochanter and dislocation of the femoral head is a safe method for anatomic reduction and internal fixation

Objective: Osteoporotic fractures of the distal forearm are demanding in terms of operative therapy and implants used. Volar fixed angle plating has become a standard procedure for these fractures. Recently intra-medullary nailing was introduced in clinical practice for the use in distal radial fractures. This randomized multi-center study compares both fixation techniques in terms of clinical and radiological outcome as well as quality of life score.

Material and Methods: Up to now a total of 85 patients with extra- and intraarticular unstable fractures of the distal radius were included. 53 patients (Targon DR®, B. Braun-Aesculap: n=24; 2.4 mm plate, Synthes: n=29) completed the 6 months follow-up. Follow up examinations included an osteodensitometry using pQCT, X-ray analysis and a detailed clinical function examination. In addition the SF36 questionaire for quality of life assessment was carried out.

Results: The operation time for volar plating was significantly longer than for intramedullary nailing (50.3±20.2 min versus 40.2±13.4 min), as was the time in hospital (5.4±1.8 days versus 2.2±0.6 days) (MW±SD; p< 0.05; Student-t-Test, post hoc: Bonferonni). The Gartland an Werley function score averaged 2.7±1.1 versus 1.9±0.8 for volar plating in comparision to treatment with the Targon DR® nail and thus just failed to reach statistical significance (p = 0.052). Radiological Evaluation revealed bony healing in all patients of both groups. Radial length was maintained in all but one patient (96%) in the nailing group and all but 2 patients (93%) in the plating group. A loss of volar tilt −5°was seen in 1 patient in the nailing group (4%) and 3 patients in the plating group (10%). Of interest radiological signs of bony healing developed much faster after intramedullary nailing. The Quality of life as measured by the SF36 was minimaly diminished in both groups (body/social function: Targon DR®: 56.3±25.1/63.4±21.2 points − 2.4 mm plate: 52.8±23.3/60.5±23.3 points). Osteoporotic bone loss was detected in a total of 72% of patients. Osteoporosis had no adverse effects on bony healing or functional parameters. We encountered two complications. One mild CRPS (volar plating) and in one case paraesthesia of the R. superficialis n. radialis (intramedullary nailing).

Conclusion: Both intramedullary nailing with the Targon DR® nail and volar plating using a 2.4 mm volar fixed angle plate allows stable fixation of osteoporotic distal forearm fractures. Lower operation time and minimally invasive operative procedure of intramedullary nailing is accompanied by faster mobilization.

Femoroacetabular impingement recently was recognized as cause for osteoarthritis of the hip. There are two mechanism of impingement: (1) cam impingement caused by a non-spherical head, and (2) pincer impingement due to acetabular overcover. We hypothesized that both mechanism result in different articular damage patterns. Of 302 analyzed hips only 26 had an isolated cam and 16 an isolated pincer impingement. Cam impingement caused anterosuperior acetabular cartilage damage with a separation between labrum and cartilage. During flexion the cartilage is sheared off the bone by the non-spherical part of the femoral head. In pincer impingement the cartilage damage was located circumferentially, invovolving only a narrow strip along the acetabular rim. During motion the labrum is crushed between the acetabular rim and the femoral neck causing degeneration and ossification of the labrum.

Cam and pincer impingement are two basic mechanism that lead to osteoarthrosis of the hip. The articular damage pattern differs substantially. Isolated cam or pincer impingement is rare, in most hips a combination is present. Labral damage indicates ongoing impingement and rarely occurs alone.

Radiodense structures resembling ossicles at the acetabular rim have received multiple names including “Os acetabuli, Os supertilii, Os marginale superius acetabuli, and Os coxae quartum”.

Various theories regarding their origin have been postulated. These structures commonly are observed in dysplastic hips and hips suffering from femoro-acetabular impingement and represent fractures of the acetabular rim. In our series we observed acetabular rim fragments in 4.9% of the dysplastic hips and in 6.4% of the hips with femoro-acetabular impingement.

Two different pathomechanics are responsible for the occurrence of these rim fragments. In dysplasia the short acetabular roof reduces the amount of available loading surface which leads to an overload on the lateral margin of the acetabulum, propagating the development of a fatigue fracture. However, as in all hips additional cysts were visible, it must be postulated, that cysts have to be present additionally and act as stress risers through which the rim bone eventually will fail. In hips with femoro-acetabular impingement the mode of failure is different. The relative anterior overcover in retroverted hips is subjected to stress during flexion of the hip, which is further increased by the frequent presence of an non-spheric extension of the femoral head as seen in cam impingement. The nonspheric femoral head-neck junction is jammed into the rim area. By repetitive traumatization the anterior rim eventually will fracture.

The clinical importance of acetabular rim fractures in the dysplastic hip is readily understood even by an unexperienced observer. However, it has to be considered as a sign that the hip has decompensated and it usually goes with significant articular cartilage damage. Because the radiographic appearance of the hip with femoro-acetabular impingement seems normal at first sight, the mechanism leading to anterior rim fracture may be overlooked. However, recognition and adequate treatment is important to prevent further degeneration of the hip.