Mixed Reality has the potential to improve accuracy and reduce required dissection for the performance of peri-acetabular osteotomy. The current work assesses initial proof of concept of MR guidance for PAO. A PAO planning module, based on preoperative computed tomography (CT) imaging, allows for the planning of PAO cut planes and repositioning of the acetabular fragment. 3D files (holograms) of the cut planes and native and planned acetabulum positions are exported with the associated spatial information. The files are then displayed on mixed reality head mounted device (HoloLens2, Microsoft) following intraoperative registration using an FDA-cleared mixed reality application designed primary for hip arthroplasty (HipInsight). PAO was performed on both sides of a bone model (Pacific Research). The osteotomies and acetabular reposition were performed in accordance with the displayed holograms. Post-op CT imaging was performed for analysis. Cutting plane-accuracy was evaluated using a best-fit plane and 2D angles (°) between the planned and achieved supra (SA)- and retroacetabular (RA) osteotomy and retroacetabular and ischial osteotomies (IO) were measured. To evaluate the accuracy of acetabular reorientation, we digitized the acetabular rim and calculated the acetabular opening plane. Absolute errors of planned and achieved operative inclination and anteversion (°) of the acetabular fragment, as well as 3D lateral-center-edge (LCE) angles were calculated. The mean absolute difference between the planned and performed osteotomy angles was 3 ± 3°. The mean absolute error between planned and achieved operative anteversion and inclination was 1 ± 0° and 0 ± 0° respectively. Mean absolute error between planned and achieved 3D LCE angle was 0.5 ± 0.7°. Mixed-reality guidance for the performance of pelvic osteotomies and acetabular fragment reorientation was feasible and highly accurate. This solution may improve the current standard of care by enabling reliable and precise reproduction of the desired acetabular realignment.
The aim of this study was to investigate whether anterior pelvic plane-pelvic tilt (APP-PT) is associated with distinct hip pathomorphologies. We asked: is there a difference in APP-PT between young symptomatic patients being evaluated for joint preservation surgery and an asymptomatic control group? Does APP-PT vary among distinct acetabular and femoral pathomorphologies? And does APP-PT differ in symptomatic hips based on demographic factors? This was an institutional review board-approved, single-centre, retrospective, case-control, comparative study, which included 388 symptomatic hips in 357 patients who presented to our tertiary centre for joint preservation between January 2011 and December 2015. Their mean age was 26 years (SD 2; 23 to 29) and 50% were female. They were allocated to 12 different morphological subgroups. The study group was compared with a control group of 20 asymptomatic hips in 20 patients. APP-PT was assessed in all patients based on supine anteroposterior pelvic radiographs using validated HipRecon software. Values in the two groups were compared using an independent-samples Aims
Methods
Hyaline cartilage has a low capacity for regeneration. Untreated osteochondral lesions of the femoral head can lead to progressive and symptomatic osteoarthritis of the hip. The purpose of this study is to analyze the clinical and radiological long-term outcome of patients treated with osteochondral autograft transfer. To our knowledge, this study represents a series of osteochondral autograft transfer of the hip with the longest follow-up. We retrospectively evaluated 11 hips in 11 patients who underwent osteochondral autograft transfer in our institution between 1996 and 2012. The mean age at the time of surgery was 28.6 years (8 to 45). Outcome measurement included standardized scores and conventional radiographs. Kaplan-Meier survival curve was used to determine the failure of the procedures, with conversion to total hip arthroplasty (THA) defined as the endpoint.Aims
Methods
To investigate whether anterior pelvic plane-pelvic tilt (APP-PT) is associated with distinct hip pathomorphologies, we asked: (1) Is there a difference in APP-PT between symptomatic young patients eligible for joint preservation surgery and an asymptomatic control group? (2) Does APP-PT vary between distinct acetabular and femoral pathomorphologies? (3) Does APP-PT differ in symptomatic hips based on demographic factors? IRB-approved, single-center, retrospective, case-control, comparative study in 388 symptomatic hips (357) patients (mean age 26 ± 2 years [range 23 to 29], 50% females) that presented to our tertiary center for joint preservation over a five year-period. Patients were allocated to 12 different morphologic subgroups. The overall study group was compared to a control group of 20 asymptomatic hips (20 patients). APP-PT was assessed in all patients based on AP pelvis X-rays using the validated HipRecon software. Values between overall and control group were compared using an independent samples t-test. Multiple regression analysis was performed to examine the influences of diagnoses and demographic factors on APP-PT. Minimal clinically important difference (MCID) of APP-PT was defined as >1 standard deviation. No significant differences in APP-PT between the control group and overall group (1.1 ± 3.0° [−4.9 to 5.9] vs 1.8 ± 3.4° [−6.9 to 13.2], p = 0.323) were observed. Acetabular retroversion and overcoverage groups showed higher APP-PT compared to the control group (both p < 0.05) and were the only diagnoses with significant influence on APP-PT in the stepwise multiple regression analysis. However, all observed differences were below the MCID. Demographic factors age, gender, height, weight and BMI showed no influence on APP-PT. APP-PT across different hip pathomorphologies showed no clinically significant variation. It does not appear to be a relevant contributing factor in the evaluation of young patients eligible for hip preservation surgery.
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. A retrospective study involving 24 patients (37 hips) with FAI and femoral retroversion (femoral version (FV) < 5° per Murphy method) was performed. All patients were symptomatic (mean age 28 years (SD 9)) and had anterior hip/groin pain and a positive anterior impingement test. Cam- and pincer-type subgroups were analyzed. Patients were compared to an asymptomatic control group (26 hips). All patients underwent pelvic CT scans to generate personalized CT-based 3D models and validated software for patient-specific impingement simulation (equidistant method).Aims
Methods
Avascular femoral head necrosis in the context of gymnastics is a rare but serious complication, appearing similar to Perthes’ disease but occurring later during adolescence. Based on 3D CT animations, we propose repetitive impact between the main supplying vessels on the posterolateral femoral neck and the posterior acetabular wall in hyperextension and external rotation as a possible cause of direct vascular damage, and subsequent femoral head necrosis in three adolescent female gymnasts we are reporting on. Outcome of hip-preserving head reduction osteotomy combined with periacetabular osteotomy was good in one and moderate in the other up to three years after surgery; based on the pronounced hip destruction, the third received initially a total hip arthroplasty.Aims
Methods
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. A retrospective institutional review board-approved observational study was performed with 333 symptomatic patients (384 hips) with hip pain due to FAI evaluated for hip preservation surgery. Overall, 142 patients (165 hips) had cam-type FAI, while 118 patients (137 hips) had mixed-type FAI. The allocation to each subgroup was based on reference values calculated on anteroposterior radiographs. CT/MRI-based measurement of FV (Murphy method) and AV were retrospectively compared among five FAI subgroups. Frequency of decreased FV < 10°, severely decreased FV < 5°, and absolute femoral retroversion (FV < 0°) was analyzed.Aims
Methods
Femoral head necrosis in the context of high impact gymnastics of young adolescents is rare but seems a more serious complication compared to a Perthes like necrosis. Between 2017 and 2019, three young females aged from12 to 14 years were referred due incapacitating hip pain and severe collapsing femoral head necrosis. The indication of hip preserving surgery was based on the extent of the necrosis, presence of a vital lateral pillar and joint subluxation. In one of our 3 cases total head involvement made THR necessary, which was performed elsewhere. In the remaining 2 cases, head reduction osteotomy plus periacetabular osteotomy led to a good and a fair result. Repetitive impact between the main supplying vessels on the posterolateral femoral neck and the posterior acetabular wall in hyperextension/ external rotation could be the cause of severe femoral head necrosis in three adolescent female gymnasts we are reporting on. Supra-selective angiography or sonography may be helpful to improve indication. Targeted adaptation of training methods should be discussed. Due to the severe vascular insult, results have to be considered moderate.
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, different in patients with AR compared to a control group?; and is there a correlation between iliac rotation and acetabular version? A retrospective, review board-approved, controlled study was performed including 120 hips in 86 consecutive patients with symptomatic FAI or hip dysplasia. Pelvic CT scans were reviewed to calculate parameters for sagittal balance (pelvic incidence (PI), PT, and sacral slope), anterior pelvic plane angle, pelvic inclination, and external rotation of the iliac wing and were compared to a control group (48 hips). The 120 hips were allocated to the following groups: AR (41 hips), hip dysplasia (47 hips) and cam FAI with normal acetabular morphology (32 hips). Subgroups of total AR (15 hips) and high acetabular anteversion (20 hips) were analyzed. Statistical analysis was performed using analysis of variance with Bonferroni correction.Aims
Methods
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. We retrospectively evaluated symptomatic patients with FAI or hip dysplasia with CT scans performed between September 2011 and September 2016. A total of 261 hips (174 patients) had a measurement of FT and TT. Their mean age was 31 years (SD 9), and 63% were female (165 hips). Patients were compared to an asymptomatic control group (48 hips, 27 patients) who had CT scans including femur and tibia available for analysis, which had been acquired for nonorthopaedic reasons. Comparisons were conducted using analysis of variance with Bonferroni correction.Aims
Methods
Abnormal femoral torsion (FT) is increasingly recognized as an additional cause for femoroacetabular impingement (FAI). It is unknown if in-toeing of the foot is a specific diagnostic sign for increased FT in patients with symptomatic FAI. The aims of this study were to determine: 1) the prevalence and diagnostic accuracy of in-toeing to detect increased FT; 2) if foot progression angle (FPA) and tibial torsion (TT) are different among patients with abnormal FT; and 3) if FPA correlates with FT. A retrospective, institutional review board (IRB)-approved, controlled study of 85 symptomatic patients (148 hips) with FAI or hip dysplasia was performed in the gait laboratory. All patients had a measurement of FT (pelvic CT scan), TT (CT scan), and FPA (optical motion capture system). We allocated all patients to three groups with decreased FT (< 10°, 37 hips), increased FT (> 25°, 61 hips), and normal FT (10° to 25°, 50 hips). Cluster analysis was performed.Aims
Patients and Methods
The modified Dunn procedure has the potential to restore the anatomy in hips with severe slipped capital femoral epiphyses (SCFE). However, there is a risk of developing avascular necrosis of the femoral head (AVN). In this paper, we report on clinical outcome, radiological outcome, AVN rate and complications, and the cumulative survivorship at long-term follow-up in patients undergoing the modified Dunn procedure for severe SCFE. We performed a retrospective analysis involving 46 hips in 46 patients treated with a modified Dunn procedure for severe SCFE (slip angle > 60°) between 1999 and 2016. At nine-year-follow-up, 40 hips were available for clinical and radiological examination. Mean preoperative age was 13 years, and 14 hips (30%) presented with unstable slips. Mean preoperative slip angle was 64°. Kaplan–Meier survivorship was calculated.Aims
Patients and Methods
Posterior extraarticular ischiofemoral hip impingement can be caused by high femoral torsion and is typically located between the ischium and the lesser trochanter. We asked if patients undergoing derotational femoral osteotomies for posterior FAI have (1) decreased hip pain and improved function and evaluated (2) subsequent surgeries and complications? Thirty-three hips undergoing derotational femoral osteotomies between 2005 and 2016 were evaluated retrospectively. Of them 15 hips underwent derotational femoral osteotomies and 18 hips underwent derotational femoral osteotomies combined with varisation (neck-shaft angle >139°). Indication for derotational osteotomies was a positive posterior impingement test in extension and external rotation, high femoral torsion (48° ± 9) on CT scans and limited external rotation. Offset improvement was performed to avoid intraarticular impingement in hips with a cam-type FAI. All patients were female and mean followup was 3 ± 2 (1 – 11) years. At latest followup the positive posterior and anterior impingement test decreased from preoperatively 100% to 5% (p< 0.001) and from preoperatively 85% to 30% (p< 0.001). The mean Merle d'Aubigné Postel score increased from 14 ± 1 (11 – 16) to 16 ± 1 (13 – 17) at latest followup (p< 0.001). At followup 32/33 hips had been preserved and one hip had been converted to a total hip arthroplasty (THA). In two hips (6%) revision osteosynthesis was performed for delayed healing of the femoral osteotomy. Derotational femoral osteotomies for the treatment of posterior extraarticular ischiofemoral impingement caused by high femoral torsion result in decreased hip pain and improved function at midterm followup but had 6% delayed healing rate requiring revision surgery.
To validate a small, easy to use and cost-effective augmented marker-based hybrid navigation system for peri-acetabular osteotomy [PAO] surgery. A cadaver study including 3 pelvises (6 hip joints) undergoing navigated PAO was performed. Inclination and anteversion of two navigation systems for PAO were compared during acetabular reorientation. The hybrid system consists of a tracking unit which is placed on the patient's pelvis and an augmented marker which is attached to the patient's acetabular fragment. The tracking unit sends a video stream of the augmented marker to the host computer. Simultaneously, the augmented marker sends orientation output from an integrated inertial measurement unit (IMU) to the host computer. The host computer then computes the pose of the augmented marker and uses it (if visible) to compute acetabular orientation. If the marker is not visible, the output from the IMU is used to update the orientation. The second system served as ground truth and is a previously developed and validated optical tracking-based navigation system.Purpose
Methods
The aims of this study were to determine the cumulative ten-year
survivorship of hips treated for acetabular fractures using surgical
hip dislocation and to identify factors predictive of an unfavourable
outcome. We followed up 60 consecutive patients (61 hips; mean age 36.3
years, standard deviation (Aims
Patients and Methods
Acetabular retroversion is an accepted cause of Pincer-type femoroacetabular impingement. There is increasing evidence that acetabular retroversion is rather a rotational abnormality of the pelvis than an overgrowth of the acetabular wall or even a dysplasia of the posterior wall. Initially, patients with a retroverted acetabulum were treated with an open rim trimming through a surgical hip dislocation (SHD) based on the early understanding of the pathomorphology. Theoretically, the reduction of the anterior wall can decrease the already small joint contact area in retroverted hips to a critical size. Based on the most recent literature, anteverting periacetabular osteotomy (PAO) seems to be the more appropriate surgical treatment. With this technique, the anterior impingement conflict can be treated efficiently without compromising the joint contact area. However, it is unknown whether this theoretical advantage in turn results in better mid term results of treatment. We asked if anteverting PAO results in better clinical and radiographical mid term results compared to rim trimming through a surgical hip dislocation.Introduction
Objectives
Torsional deformities are increasingly recognized as an additional factor in young patients with hip pain resulting from pincer- and cam-deformities. For example decreased femoral torsion can worsen an anterior Femoroacetabular impingement (FAI) conflict while an increased torsion can be beneficial with the same configuration. It is unknown how often torsional deformities are present in young patients presenting with hip pain that are eligible for joint preserving surgery. We questioned (1) what is the prevalence of a pathological femoral torsion in hips with FAI or hip dysplasia? (2) which hip disorders are associated with an abnormal torsion? An IRB-approved retrospective study of 463 consecutive symptomatic FAI patients (538 hips) and a MRI or CT scan on which femoral torsion could be measured was performed (‘study group'). Out of 915 MRI we excluded 377 hips. The study group was divided into 11 groups: Dysplasia (< 22° LCE), retroversion, anteverted hips, overcoverage (LCE angle 36–39°), severe overcoverage (LCE>39°), cam (>50° alpha angle), mixed FAI, varus- (<125° CCD angle), valgus- (>139° CCD), Perthes-hips and hips with no obvious pathology. The ‘control group' of normal hips consisted of 35 patients (35 hips) without radiographic signs of osteoarthritis or hip pain wich was used for a previous study. Femoral antetorsion was measured according to Tönnis et al. as the angle between the axis of the femoral neck and the posterior axis of the femoral condyles. Normal femoral torsion was defined by Tönnis et al. as angles 10–25° while decreased resp. increased torsion was defined as <5° and >25°. Statistical analysis was performed using analysis of variances (ANOVA).Introduction
Methods
Hips following in-situ pinning for slipped capital femoral epiphysis (SCFE) have an altered morphology of the proximal femur with cam type deformity. This deformity can result in femoroacetabular impingement and early joint degeneration. The modified Dunn procedure allows to reorientate the slipped epiphysis to restore hip morphology and function. To evaluate (1) hip pain and function, (2) 10-year survival rate and (3) subsequent surgeries and complications in hips undergoing modified Dunn procedure for SCFE.Introduction
Objectives
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. We asked if the (1) accuracy, (2) precision, and (3) number of outliers of the prosthetic cup orientation differed between three study groups: the anterior approach in supine position, the anterior approach in lateral decubitus position, and the transgluteal approach in lateral decubitus position.Introduction
Objectives
Navigation in total hip arthroplasty (THA) has the goal to improve accuracy of cup orientation. Measurement of cup orientation on conventional pelvic radiographs is susceptible to error due to pelvic malpositioning during acquisition. A recently developed and validated software using a postoperative radiograph in combination with statistical shape modelling allows calculation of exact 3-dimensional cup orientation independent of pelvic malpositioning. We asked (1) what is the accuracy of computer-navigated cup orientation (inclination and anteversion) and (2) what is the percentage of outliers (>10° difference to aimed inclination and anteversion) using postoperative measurement of 3-dimensional cup orientation.Introduction
Objectives
