Till D. Lerch

• MD Phd
• Medical Doctor at 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...

Objectives To compare the prevalence of femoral head decentration (FHD) on different MR imaging planes in patients undergoing direct/indirect hip MR arthrography (MRA) with asymptomatic controls and to evaluate its association with osseous deformities. Methods IRB-approved retrospective single-center study of symptomatic hips undergoing direct or...

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...

Objectives Slipped capital femoral epiphyses (SCFE) is a common pediatric hip disease with the risk of osteoarthritis and impingement deformities, and 3D models could be useful for patient-specific analysis. Therefore, magnetic resonance imaging (MRI) bone segmentation and feasibility of 3D printing and of 3D ROM simulation using MRI-based 3D model...

Background Femoral version deformities have recently been identified as a major contributor to femoroacetabular impingement (FAI). An in-depth understanding of the specific labral damage patterns caused by femoral version deformities may help to understand the underlying pathomorphologies in symptomatic patients and select the appropriate surgical...

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...

Objectives To identify preoperative degenerative features on traction MR arthrography associated with failure after arthroscopic femoroacetabular impingement (FAI) surgery. Methods Retrospective study including 102 patients (107 hips) undergoing traction magnetic resonance arthrography (MRA) of the hip at 1.5 T and subsequent hip arthroscopic FAI...

Objectives To assess the feasibility of flexion-abduction-external rotation (FABER) magnetic resonance imaging (MRI) of the hip to visualize changes in the ischiofemoral interval and ability to provoke foveal excursion over the acetabular rim. Methods IRB-approved retrospective single-center study. Patients underwent non-contrast 1.5-T hip MRI in...

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 The location of posterior hip impingement at maximal extension in patients with posterior femoroacetabular impingement (FAI) is unclear. Purpose To investigate the frequency and area of impingement at maximal hip extension and at 10° and 20° of extension in female patients with increased femoral version (FV) and posterior hip pain. Stu...

More than half of SCFE patients treated with in-situ-pinning had absolute femoral retroversion on postoperative CT scans, ranging from 42% of mild SCFE to 67% of severe SCFE. Femoral retroversion was previously associated with anterior subspinehip impingement. This could help to evaluate subsequent surgery (such as derotationfemoral osteotomy). Rad...

Conclusion: One third of patients with hip dysplasia have normal FT combined with normal AV. Almost a third of patients have decreased FV<10°, while 23% have increased FT>25°. Preoperative hip MRI allows assessment of FT and detection of deformities of FT such as increased or decreased FT for patients with hip dysplasia and hip pain. This is import...

Objective: To utilize hip MRI 3D models for demonstration of location and frequency of impingement during simulated range-of-motion in ischiofemoral impingement (IFI) compared to non-IFI hips. Materials and methods: Sixteen hips (N = 7 IFI, 9 non-IFI) from 8 females were examined with high-resolution MRI. We performed image segmentation and gene...

Purposes 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)....

Background: Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) allows objective and noninvasive assessment of cartilage quality. An interim analysis 1 year after correction of femoroacetabular impingement (FAI) previously showed that the dGEMRIC index decreased despite good clinical outcome. Purpose: To evaluate dGEMRI...

Objective: To compare image quality and diagnostic performance of preoperative direct hip magnetic resonance arthrography (MRA) performed with gadolinium contrast agent and saline solution. Methods: IRB-approved retrospective study of 140 age and sex-matched symptomatic patients with femoroacetabular impingement, who either underwent intra-artic...

Background: Developmental dysplasia of the hip (DDH) is a known reason for hip pain for adolescents and young adults. Preoperative imaging is increasingly recognized as an important factor due to the recent advances in MR imaging. Objectives: The aim of this article is to give an overview of preoperative imaging for DDH. The acetabular version a...

Background: Posterior femoroacetabular impingement (FAI) is poorly understood. Patients with increased femoral anteversion (FV) exhibit posterior hip pain. Purpose: To correlate hip impingement area with FV and with combined version and to investigate frequency of limited external rotation (ER) and hip extension (<40°, <20°, and <0°) due to post...

Background It remains unclear if femoral retroversion is a contraindication for hip arthroscopy in patients with femoroacetabular impingement (FAI). Purpose To compare the area and location of hip impingement at maximal flexion and during the FADIR test (flexion, adduction, internal rotation) in FAI hips with femoral retroversion, hips with decrea...

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...

Purpose Slipped capital femoral epiphysis is a common pediatric hip disease and was associated with femoral retroversion, but femoral version was rarely measured. Therefore, mean femoral version, mean femoral neck version, and prevalence of femoral retroversion were analyzed for slipped capital femoral epiphysis patients. Methods A retrospective o...

(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...

Background Various reduction techniques exist to treat traumatic shoulder dislocation, but best management remains unclear. Aims To investigate the reduction rate of traumatic anteroinferior shoulder dislocations using two sedation-free techniques and success rates of subgroups. Methods A single-center study was performed analysing shoulder dislo...

Aims Femoroacetabular impingement (FAI) patients report exacerbation of hip pain in deep flexion. However, the exact impingement location in deep flexion is unknown. The aim was to investigate impingement-free maximal flexion, impingement location, and if cam deformity causes hip impingement in flexion in FAI patients. Methods A retrospective stud...

Aims: To compare (a) the change in radiological bony morphology between participants with femoroacetabular impingement (FAI) syndrome who underwent arthroscopic hip surgery compared to physiotherapist-led non-surgical care and (b) the change in radiological bony morphology between participants with FAI syndrome who underwent arthroscopic hip surge...

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...

Posterior extraarticular ischiofemoral hip impingement was associated with increased femoral version in female patients. The Purpose of this study was to investigate frequency of impingement in maximal extension in female patients with increased femoral version.

Aims To evaluate how abnormal proximal femoral anatomy affects different femoral version measurements in young patients with hip pain. Methods First, femoral version was measured in 50 hips of symptomatic consecutively selected patients with hip pain (mean age 20 years (SD 6), 60% (n = 25) females) on preoperative CT scans using different measurem...

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 Symptomatic patients with femoroacetabular impingement (FAI) have limitations in daily activities and sports and report the exacerbation of hip pain in deep flexion. Yet, the exact impingement location in deep flexion and the effect of femoral version (FV) are unclear. Purpose To investigate the acetabular and femoral locations of intra...

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...

Aims The frequency of severe femoral retroversion is unclear in patients with femoroacetabular impingement (FAI). This study aimed to investigate mean femoral version (FV), the frequency of absolute femoral retroversion, and the combination of decreased FV and acetabular retroversion (AR) in symptomatic patients with FAI subtypes. Methods A retros...

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...

Zusammenfassung Instabilität und Impingement stellen die Hauptpathomechanismen dar, die bereits bei jungen Patienten durch erhöhten mechanischen Stress zu chondrolabralen Schäden, schmerzhafter Bewegungseinschränkung und frühzeitiger Coxarthrose führen können. Ziele der gelenkerhaltenden Chirurgie an der Hüfte sind die Korrektur der knöchernen Defo...

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...

The etiology of hallux rigidus remains a controversial issue in foot and ankle surgery, i.e. the relationship between metatarsus primus elevatus (MPE) and hallux rigidus. The purpose of this study was to evaluate several radiographic parameters including first metatarsal elevation in patients with hallux rigidus compared to a matched control group....

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...

Unsupervised domain adaptation (UDA) for cross-modality medical image segmentation has shown great progress by domain-invariant feature learning or image appearance translation. Feature-level adaptation based methods learn good domain-invariant features in classification tasks but usually cannot detect domain shift at the pixel level and are not ab...

The primary purpose was to answer the following question: What is the location and pattern of necrosis and associated chondrolabral lesions and can they be accurately detected on traction MR arthrography compared with intra-operative findings in patients undergoing hip preservation surgery for femoral head necrosis (FHN)? Retrospective, diagnostic...

Background One of the values determined during the assessment of knee issues is the posterior tibial slope (PTS). A new option for measuring the PTS is the EOS 3D imaging system, which provides anteroposterior (AP) and lateral long leg radiographs (LLRs) using less radiation than a conventional LLR. We investigated the reliability of the EOS 3D ima...

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: Arthroscopic treatment of symptomatic femoroacetabular impingement (FAI) has promising short-term to mid-term results. In addition to treating acute pain or impaired function, the goal of hip-preserving surgery is to achieve a lasting improvement of hip function and to prevent the development of osteoarthritis. Long-term results are ne...

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...

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.

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 1)To determine the 3D femoral head coverage in these subgroups of pincer FAI, (2)To determine the impingement-free range of motion using osseous models based on 3D CT scans, (3)And to determine the osseous intra-and extraarticular 3D impingement zones located using 3D impingement simulation. Patients and Methods This is a retrospective, compa...

Unsupervised domain adaptation (UDA) for cross-modality medical image segmentation has shown great progress by domain-invariant feature learning or image appearance translation. Adapted feature learning usually cannot detect domain shifts at the pixel level and is not able to achieve good results in dense semantic segmentation tasks. Image appearan...

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...

Hip cartilage damage is a major predictor of the clinical outcome of surgical correction for femoroacetabular impingement (FAI) and hip dysplasia. Automatic segmentation for hip cartilage is an essential prior step in assessing cartilage damage status. Deep Convolutional Neural Networks have shown great success in various automated medical image se...

Aims To assess (1) hip pain and function and ROM; (2) subsequent surgeries, complications; and (3) subjective satisfaction and PROMs in patients undergoing femoral derotation osteotomies. Methods Femoral derotation subtrochanteric osteotomies to treat symptomatic posterior extraarticular ischiofemoral hip impingement were performed in 23 patients...