Klaus A Siebenrock

• Inselspital, Universitätsspital Bern

The objective was to use convolutional neural networks (CNNs) for automatic segmentation of hip cartilage and labrum based on 3D MRI. In this retrospective single-center study, CNNs with a U-Net architecture were used to develop a fully automated segmentation model for hip cartilage and labrum from MRI. Direct hip MR arthrographies (01/2020-10/2021...

Background Abnormal femoral head anatomy following moderate-to-severe slipped capital femoral epiphysis (SCFE) can lead to femoroacetabular impingement and premature osteoarthritis 4–10 . Surgical correction at the deformity site through capital reorientation has the potential to fully ameliorate this but has traditionally been associated with high...

Background The risk of developing avascular necrosis (AVN) in the setting of an unstable slipped capital femoral epiphysis (SCFE) that is undergoing treatment with the modified Dunn procedure is not well understood. In addition, since the Loder classification of unstable is reportedly different than actual intraoperatively observed instability (tha...

The objective was to use convolutional neural networks (CNNs) for automatic segmentation of hip cartilage and labrum based on 3D MRI. In this retrospective single-center study, CNNs were used to develop a fully automated segmentation model for hip cartilage and labrum from MRI. Direct hip MR arthrographies (01/2020-10/2021) were selected from 100 s...

Current clinical methods of bone health assessment depend to a great extent on bone mineral density (BMD) measurements. However, these methods only act as a proxy for bone strength and are often only carried out after the fracture occurs. Besides BMD, composition and tissue-level mechanical properties are expected to affect the whole bone’s strengt...

Introduction In situ pinning is an accepted treatment for stable slipped capital femoral epiphysis. However, residual deformity of severe slipped capital femoral epiphysis can cause femoroacetabular impingement and forced external rotation. Purpose/questions The aim of this study was to evaluate the (1) hip external rotation and internal rotation...

Femoroacetabular impingement (FAI) patients with reduced femoral version (FV) are poorly understood. The aim of this study is to assess (i) hip pain and range of motion, (ii) subjective satisfaction and (iii) subsequent surgeries of symptomatic patients who underwent rotational femoral osteotomies. A retrospective case series involving 18 patients...

Background: Severe slipped capital femoral epiphysis (SCFE) leads to femoroacetabular impingement and restricted hip motion. We investigated the improvement of impingement-free flexion and internal rotation (IR) in 90 degrees of flexion following a simulated osteochondroplasty, a derotation osteotomy, and a combined flexion-derotation osteotomy in...

(1) Background: To evaluate the performance of a deep learning model to automatically segment femoral head necrosis (FHN) based on a standard 2D MRI sequence compared to manual segmentations for 3D quantification of FHN. (2) Methods: Twenty-six patients (thirty hips) with avascular necrosis underwent preoperative MR arthrography including a coronal...

Aims Frequency of abnormal femoral and acetabular version(AV) and combinations are unclear in patients with developmental dysplasia of the hip (DDH). This study aimed to investigate femoral version(FV), the proportion of increased FV and femoral retroversion, and combined-version(CV, FV+AV) in DDH patients and acetabular-retroversion(AR). Patients...

Introduction: Slipped capital femoral epiphysis (SCFE) is the most common hip disorder in adolescent patients that can result in complex 3 dimensional (3D)-deformity and hip preservation surgery (eg, in situ pinning or proximal femoral osteotomy) is often performed. But there is little information about location of impingement.Purpose/Questions: T...

Background and Objectives: Atraumatic intrapelvic protrusion of the acetabular component following excessive reaming of the acetabulum with a far medial positioning of the cup is a rare, but serious complication of a total hip arthroplasty (THA). This study analyzes the factors contributing to this uncommon complication and presents the outcome aft...

Purpose Preservation surgery can halt the progress of joint degradation, preserving the life of the hip; however, outcome depends on the existing cartilage quality. Biochemical analysis of the hip cartilage utilizing MRI sequences such as delayed gadolinium-enhanced MRI of cartilage (dGEMRIC), in addition to morphological analysis, can be used to d...

Frequencies of combined abnormalities of femoral version (FV) and acetabular version (AV) and of abnormalities of the McKibbin index are unknown. To investigate the prevalence of combined abnormalities of FV and AV and of abnormalities of the McKibbin index in symptomatic patients with femoroacetabular impingement (FAI), a retrospective, Institutio...

In-toeing of the foot was associated with high femoral version (FV), while Out-toeing was associated with femoral-retroversion. Therefore, we report on (i) foot-progression-angle (FPA), (ii) prevalence of In-toeing and Out-toeing, and (iii) clinical outcome of patients treated with femoral-derotation-osteotomy (FDO). We performed a retrospective an...

Background: Slipped capital femoral epiphyses (SCFE) is associated with out-toeing of the foot and external rotation gait. But it is unknown if SCFE patients treated with the modified Dunn procedure have out-toeing at follow up.Therefore, we used instrumented gait analysis and questioned (1) do severe SCFE patients treated with a modified Dunn pro...

Objectives: The crossover-sign (COS) is a radiographic sign for diagnosis of acetabular-retroversion(AR) in patients with femoroacetabular-impingement (FAI) but overestimates AR. Three signs combined with retroversion-index (RI) could potentially improve diagnostic-accuracy. Aims: (1)To calculate central acetabular-version (AV, CT/MRI) in patien...

Objectives To compare the prevalence of pre- and postoperative osseous deformities and intra-articular lesions in patients with persistent pain following arthroscopic femoroacetabular impingement (FAI) correction and to identify imaging findings associated with progressive cartilage damage. Methods Retrospective study evaluating patients with hip...

Background Dynamic 3-dimensional (3D) simulation of hip impingement enables better understanding of complex hip deformities in young adult patients with femoroacetabular impingement (FAI). Deep learning algorithms may improve magnetic resonance imaging (MRI) segmentation. Purpose (1) To evaluate the accuracy of 3D models created using convolutiona...

Aims The effect of pelvic tilt (PT) and sagittal balance in hips with pincer-type femoroacetabular impingement (FAI) with acetabular retroversion (AR) is controversial. It is unclear if patients with AR have a rotational abnormality of the iliac wing. Therefore, we asked: are parameters for sagittal balance, and is rotation of the iliac wing, diffe...

Die periazetabuläre Beckenosteotomie (PAO) nach Ganz ist eine bewährte Operationstechnik zur Neuausrichtung der Hüftgelenkspfanne unter Erhalt der Blutversorgung des frei beweglichen azetabulären Fragmentes. Der hintere Pfeiler und somit die Form und Stabilität des kleinen Beckens bleibt intakt. Indikationen sind die symptomatische residuale Dyspla...

Preoperative evaluation of the pathomorphology is crucial for surgical planning, including radiographs as the basic modality and magnetic resonance imaging (MRI) and case-based additional imaging (e.g. 3D-CT, abduction views). Hip arthroscopy (HAS) has undergone tremendous technical advances, an immense increase in use and the indications are getti...

Background Posterior extra-articular hip impingement has been described for valgus hips with increased femoral version (FV). These patients can present clinically with lack of external rotation (ER) and extension and with a positive posterior impingement test. But we do not know the effect of the combination of deformities, and the impingement loca...

Background Anterior femoroacetabular impingement (FAI) is associated with labral tears and acetabular cartilage damage in athletic and young patients. Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) is an imaging method for detecting early damage to cartilage. Purpose We evaluated the following questions: (1) What is...

Background Often used for T1 mapping of hip cartilage, three-dimensional (3D) dual-flip-angle (DFA) techniques are highly sensitive to flip angle variations related to B1 inhomogeneities. The authors hypothesized that 3D magnetization-prepared 2 rapid gradient-echo (MP2RAGE) MRI would help provide more accurate T1 mapping of hip cartilage at 3.0 T...

Background: Periacetabular osteotomy (PAO) has been shown to be a valuable option for delaying the onset of osteoarthritis in patients with hip dysplasia. Published studies at 30 years of follow-up found that postoperative anterior overcoverage and posterior undercoverage were associated with early conversion to THA. The anterior and posterior wal...

Patient-specific 3D models for patients with severe SCFE facilitate diagnosis and surgical planning simulating the range of motion and location of impingement. Femoral impingement is mostly located anterior. This study could aid in preoperative planning and surgical decision making e.g.what kind of operation should be performed for patients with se...

Automatic MRI-based 3D models can replace CT-based 3D models for patients of childbearing age with hip dysplasia and FAI. Based on these excellent results, we intend to change our clinical practice and we will use automatic reconstruction of MR-based 3D models for future clinical routine instead of CT-based 3D models. This allows radiation-free and...

Pincer FAI can be caused by acetabular overcoverage (protrusio acetabuli) or malorientation (acetabular retroversion). Both can cause anterior hip pain and hip impingement. Using patient-specific 3D models of the patients, 3D simulation of hip impingement showed intra- and extraarticular subspine hip impingement in patients with acetabular retrover...

Deep learning provides fast and automatic bone segmentation for patient-specific 3D models of the hip joint. These 3D models can be used for computer-assisted diagnosis of hip dysplasia and femoroacetabular impingement (FAI). This method allows fast preoperative planning of hip preserving surgery such as hip arthroscopy or open treatment.

At minimum 10 year follow up after prophylactic pinning of the contralateral radiographically normal hip the vast majority of the patients can expect an excellent functional hip specific outcome. However, patients with unilateral SCFE should still be considered to be at risk of developing cam FAI in the contralateral normal hip despite prophylactic...

The modified Dunn procedure for severe SCFE largely corrected slip deformities with little apparent risk of progression to avascular necrosis, OA, THA or hip arthrodesis and high hip scores at longterm followup . However, AVN occurred in 2 hips (5%) and secondary impingement deformities persisted in some hips and of those some underwent further sur...

Severe SCFE Patients that underwent modified Dunn procedure showed normal gait and normal hip function at longterm followup

Location And Pattern Of Femoral Head Necrosis And Intra-Articular Lesions were evaluated using Traction MR Arthrography of the Hip Joint

Posterior extraarticular femoroacetabular impingement (FAI) has been described for valgus hips with increased femoral version (FV) but is poorly understood. These patients present clinically with a lack of external rotation and extension. We analyzed if range of motion (ROM), location of posterior intra-and extraarticular FAI and the prevalence of...

Variations in both acetabular version (AV) and femoral torsion (FT) are becoming increasingly recognized as contributing factors to the development of hip pain in patients with femoroacetabular impingement (FAI) and hip dysplasia. It is still unknown what the true prevalence of acetabular retroversion is in this patient population.

MRI-based 3D dynamic hip Impingement simulation enables patient-specific diagnosis of intra-and extraarticular FAI. But manual segmentation of MRI-based 3D-models is time-consuming, therefore automatic segmentation was investigated.

For surgical planning of complex hips with FAI, CT-based 3D impingement simulation is the current gold standard to determine the location of bony impingement. Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) allows a noninvasive estimation of cartilage composition. Currently it is unclear whether biochemical cartilage damage occurs exactly at...

Femoral derotation osteotomy was performed for patients with posterior hip impingement and high femoral torsion. We investigated, if these patients have postoperative In-Toeing of the foot.

Background: Cam morphologies seem to develop with an increased prevalence in adolescent boys performing high-impact sports. The crucial question is at what age the cam morphology actually develops and whether there is an association with an aberration of the shape of the growth plate at the cam morphology site. Questions/purposes: (1) What is th...

Introduction: Both Hip Dysplasia(DDH) and Femoro-acetabular-Impingement(FAI) are complex three-dimensional hip pathologies causing hip pain and osteoarthritis in young patients. 3D-MRI-based models were used for radiation-free computer-assisted surgical planning. Automatic segmentation of MRI-based 3D-models are preferred because manual segmentati...

Aims The prevalence of combined abnormalities of femoral torsion (FT) and tibial torsion (TT) is unknown in patients with femoroacetabular impingement (FAI) and hip dysplasia. This study aimed to determine the prevalence of combined abnormalities of FT and TT, and which subgroups are associated with combined abnormalities of FT and TT. Methods We...

Classical indications for hip preserving surgery are: femoro-acetabular impingement (FAI) (intra- and extra-articular), hip dysplasia, slipped capital femoral epiphysis, residual deformities after Perthes disease, avascular necrosis of the femoral head. Pre-operative evaluation of the pathomorphology is crucial for surgical planning including radio...

Background Prosthetic joint infection(PJI) is deemed to be the most serious complication following total hip arthroplasty. Obesity and smoking are known risk factors for PJI. However, the influence of these variables on infection free survival, of septic revision hip arthroplasty, is yet to be explored. The aim of this study was to determine the ef...

Introduction: The best treatment of acetabular chondral flaps during surgery for femoroacetabular impingement (FAI) is unknown. We asked if subchondral drilling improves clinical and radiographic outcome and if there are factors predicting failure. Methods: We treated 79 patients with symptomatic FAI and acetabular chondral flaps with surgical h...

Evaluation of the use of microfracturing in the treatment of cartilage lesions of the hip joint

Background The modified Dunn procedure has the potential to restore the anatomy in hips with slipped capital femoral epiphyses (SCFE) while protecting the blood supply to the femoral head and minimizing secondary impingement deformities. However, there is controversy about the risks associated with the procedure and mid- to long-term data on clinic...

This chapter discusses the versatile options for bone repair in orthopedic and trauma surgery including the use of autologous and allogeneic bone grafts as well as bone graft substitutes.

Background: Acetabular retroversion can cause impaction-type femoroacetabular impingement leading to hip pain and osteoarthritis. It can be treated by anteverting periacetabular osteotomy (PAO) or acetabular rim trimming with refixation of the labrum. There is increasing evidence that acetabular retroversion is a rotational abnormality of the enti...

Background: Since the importance of an intact labrum for normal hip function has been shown, labral reattachment has become the standard method for open or arthroscopic treatment of hips with femoroacetabular impingement (FAI). However, no long-term clinical results exist evaluating the effect of labral reattachment. A 2-year followup comparing op...

Purpose: Open surgical management of unstable pelvic ring injuries has been discussed controversially compared to percutaneous techniques in terms of surgical site morbidity especially in older patients. Thus, we assessed the impact of age on the outcome following fixation of unstable pelvic ring injuries through the modified Stoppa approach. Met...

Background Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) allows an objective, noninvasive, and longitudinal quantification of biochemical cartilage properties. Although dGEMRIC has been used to monitor the course of cartilage degeneration after periacetabular osteotomy (PAO) for correction of hip dysplasia, such longitudinal data are curre...

Background Although the etiology of primary femoroacetabular impingement (FAI) is considered developmental, the underlying pathogenic mechanisms remain poorly understood. In particular, research identifying etiologic factors associated with pincer FAI is limited. Knowledge of the physiologic growth patterns of the acetabulum during skeletal maturat...

Background: Magnetic resonance arthrogram (MRA) with radial cuts is presently the best available preoperative imaging study to evaluate chondrolabral lesions in the setting of femoroacetabular impingement (FAI). Existing followup studies for surgical treatment of FAI have evaluated predictors of treatment failure based on preoperative clinical exa...

Purpose. To develop and evaluate a low-cost, surgical navigation solution for periacetabular osteotomy (PAO) surgery. Methods. A commercially available low-cost miniature computer is used together with a camera board (Raspberry Pi 2 Model B, Camera Module PiNoir) to track planar markers (Aruco markers). The overall setup of the tracking unit is sma...

Femoroacetabular impingement (FAI) describes the repetitive painful contact between the acetabulum, the pelvis and the proximal femur. This bony abutment can lead to a characteristic pattern of chondrolabral damage and is one of the main etiological factors in the development of juvenile osteoarthritis of the hip joint. This article describes the c...

Periacetabular osteotomy (PAO) is an effective approach for surgical treatment of hip dysplasia in young adults. The aim of PAO surgery is to increase acetabular coverage of the femoral head and to reduce contact pressures by reorienting the acetabulum fragment during PAO. The success of PAO significantly depends on the surgeon’s experience. Previo...

Background Protrusio acetabuli is a rare anatomic pattern of the hip in which the femoral head protrudes into the true pelvis. The increased depth of the hip and the excessive size of the lunate surface typically lead to severe pincer-type femoroacetabular impingement (FAI); however, to our knowledge, there are no published mid- or long-term studie...

The Bernese periacetabular osteotomy (PAO) is a surgical 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 int...

Background: The aim of this study was to identify the 100 most cited classics in the field of hip research analysing their qualities and characteristics. Methods: Hip joint related articles were identified and the hundred most cited selected for subsequent analysis of citation count, current citation rate, citation density (citations/article age),...

Modern computerized planning tools for periacetabular osteotomy (PAO) use either morphology-based or biomechanics-based methods. The latter relies on estimation of peak contact pressures and contact areas using either patient specific or constant thickness cartilage models. We performed a finite element analysis investigating the optimal reorientat...

Pelvic osteotomies improve containment of the femoral head in cases of developmental dysplasia of the hip or in femoroacetabular impingement due to acetabular retroversion. In the evolution of osteotomies, the Ganz Periacetabular Osteotomy (PAO) is among the complex reorientation osteotomies and allows for complete mobilization of the acetabulum wi...

Femoroacetabular impingement (FAI) is a dynamic conflict of the hip defined by a pathological, early abutment of the proximal femur onto the acetabulum or pelvis. In the past two decades, FAI has received increasing focus in both research and clinical practice as a cause of hip pain and prearthrotic deformity. Anatomical abnormalities such as an as...

Periacetabular Osteotomy (PAO) is a joint preserving surgical intervention intended to increase femoral head coverage and thereby to improve stability in young patients with hip dysplasia. Previously, we developed a CT-based, computer-assisted program for PAO diagnosis and planning, which allows for quantifying the 3D acetabular morphology with par...

To evaluate a low-cost, inertial sensor-based surgical navigation solution for periacetabular osteotomy (PAO) surgery without the line-of-sight impediment. Two commercial inertial measurement units (IMU, Xsens Technologies, The Netherlands), are attached to a patient's pelvis and to the acetabular fragment, respectively. Registration of the patient...

The pararectus approach has been validated for managing acetabular fractures. We hypothesised it might be an alternative approach for performing periacetabular osteotomy (PAO). Using four cadaver specimens, we randomly performed PAO through either the pararectus or a modified Smith-Petersen (SP) approach. We assessed technical feasibility and safet...

Background The iliocapsularis muscle is an anterior hip structure that appears to function as a stabilizer in normal hips. Previous studies have shown that the iliocapsularis is hypertrophied in developmental dysplasia of the hip (DDH). An easy MR-based measurement of the ratio of the size of the iliocapsularis to that of adjacent anatomical struc...

• A broad spectrum of hip pathological conditions, including ischemic, traumatic, inflammatory, arthritic, and neoplastic etiologies, can be detected by magnetic resonance imaging (MRI). • Alteration of fluid content in tissue can be visualized by fluid-sensitive sequences such as T2, proton density, and short tau inversion recovery (STIR). • Anato...

There is a decades-long tradition at the University of Bern to pioneer new ideas and surgical techniques through courses and symposia. In the early years, under the guidance of Maurice E. Müller, Bernese hip courses focused on hip replacement. In time, many instructional courses were held in different languages. Gradually, the focus of these hip co...

The periacetabular osteotomy procedure reorients a retroverted acetabulum into a more anatomically appropriate position. A periacetabular osteotomy is indicated for patients with substantial acetabular retroversion who present with a combination of radiographic findings (Fig. 1): a positive crossover sign (with a retroversion index exceeding 30%),...

Residual acetabular dysplasia is seen in combination with femoral pathomorphologies including an aspherical femoral head and valgus neck-shaft angle with high antetorsion. It is unclear how these femoral pathomorphologies affect range of motion (ROM) and impingement zones after periacetabular osteotomy. (1) Does periacetabular osteotomy (PAO) resto...

In some hips with cam-type femoroacetabular impingement (FAI), we observed a morphology resembling a more subtle form of slipped capital femoral epiphysis (SCFE). Theoretically, the morphology in these hips should differ from hips with a primary cam-type deformity. We asked if (1) head-neck offset; (2) epiphyseal angle; and (3) tilt angle differ am...

Background: Both acetabular undercoverage (hip dysplasia) and overcoverage (pincer-type femoroacetabular impingement) can result in hip osteoarthritis. In contrast to undercoverage, there is a lack of information on radiographic reference values for excessive acetabular coverage. Questions/purposes: (1) How do common radiographic hip parameters...

Background: Severe femoral head deformities in the frontal plane such as hips with Legg-Calvé-Perthes disease (LCPD) are not contained by the acetabulum and result in hinged abduction and impingement. These rare deformities cannot be addressed by resection, which would endanger head vascularity. Femoral head reduction osteotomy allows for reshapin...

Background Complex proximal femoral deformities, including an elevated greater trochanter, short femoral neck, and aspherical head-neck junction, often result in pain and impaired hip function resulting from intra-/extraarticular impingement. Relative femoral neck lengthening may address these deformities, but mid-term results of this approach hav...

Pelvic discontinuity is a complex problem in revision total hip arthroplasty. Although rare, the incidence is likely to increase due to the ageing population and the increasing number of total hip arthroplasties being performed. The various surgical options available to solve this problem include plating, massive allografts, reconstruction rings, c...