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Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_1 | Pages 84 - 84
1 Jan 2018
Lerch T Steppacher S Ziebarth K Tannast M Siebenrock K
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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.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_20 | Pages 14 - 14
1 Dec 2017
Pflugi S Lerch T Vasireddy R Boemke N Tannast M Ecker TM Siebenrock K Zheng G
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Purpose

To validate a small, easy to use and cost-effective augmented marker-based hybrid navigation system for peri-acetabular osteotomy [PAO] surgery.

Methods

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.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_5 | Pages 139 - 139
1 Mar 2017
Lerch T Todorski I Steppacher S Schmaranzer F Siebenrock K Tannast M
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Introduction

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?

Methods

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).


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_6 | Pages 17 - 17
1 Mar 2017
Steppacher S Milosevic M Lerch T Tannast M Ziebarth K Siebenrock K
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Introduction

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.

Objectives

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.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_5 | Pages 138 - 138
1 Mar 2017
Schmaranzer F Haefeli P Hanke M Lerch T Werlen S Tannast M Siebenrock K
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Objectives

Delayed gadolinium enhanced MRI of cartilage (dGEMRIC) is a novel MRI-based technique with intravenous contrast agent that allows an objective quantification of biochemical cartilage properties. It enables a ‘monitoring' of the loss of cartilage glycosaminoglycan content which ultimately leads to osteoarthritis. Data regarding the longitudinal change of cartilage property after joint preserving hip surgery is sparse. We asked (1) if and how the dGEMRIC-index changes in patients undergoing open/arthroscopic treatment of femoroacetabular impingement (FAI) one year postoperatively compared to a control group of patients with non-operative treatment; (2) and if a change correlates with the clinical short term outcome.

Methods

IRB-approved prospective comparative longitudinal study of two groups involving a total of 61 hips in 55 symptomatic patients with FAI. The ‘operative' group consisted of patients that underwent open/arthroscopic treatment of their pathomorphology. The ‘non-operative' group consisted of conservatively treated patients. Groups were comparable for preoperative radiographic arthritis (Tönnis score), preoperative HOOS- and WOMAC-scores and baseline dGEMRIC indices.

All patients eligible for evaluation had preoperative radiographs and dGEMRIC scans at baseline and repeated dGEMRIC scans using the same scanner and protocol. (1) dGEMRIC indices of femoral and acetabular cartilage were assessed separately on the initial and follow-up dGEMRIC scans. Radial images were reformatted from a 3D T1 map for measurements. Regions of interest were placed manually peripherally and centrally within the cartilage based on anatomical landmarks at the 12 ‘hour' position of the clcok-face with the help of radial high-resolution PD-weighted MR images. (2) Patient-reported outcome was evaluated at baseline and at 1 year follow-up: Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Hip disability and Osteoarthritis Outcome Score (HOOS). Statistical analysis included Student's t-Tests, Mann-Whitney U-tests and Wilcoxon signed-rank tests (p<0.05).


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_4 | Pages 122 - 122
1 Feb 2017
Lerch T Tannast M Steppacher S Siebenrock K
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Introduction

Since its first description in 1988, periacetabular osteotomy has become the gold-standard worldwide in surgical treatment of developmental dysplasia of the hip. Several long-term studies have proven the efficacy of this procedure. In this study, we evaluated the mean 30-years results of this procedure of the first 63 patients (75 hips) operated at the institution where this procedure had been developed.

Objectives

We determined the (1) cumulative 30-year survivorship of symptomatic patients treated with this procedure, determined the (2) clinical and (3) radiographic outcomes of the surviving hips, and (4) identified factors predicting the need for total hip arthroplasty (THA).


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_4 | Pages 121 - 121
1 Feb 2017
Lerch T Tannast M Steppacher S Siebenrock K
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Introduction

Torsional deformities of the femur have been recognized as a cause of femoroacetabular impingement (FAI) and hip pain. High femoral antetorsion can result in decreased external rotation and a posterior FAI, which is typically located extraarticular between the ischium and trochanter minor. Femoral osteotomies allow to correct torsional deformities to eliminate FAI. So far the mid-term clinical and radiographic results in patients undergoing femoral osteotomies for correction of torsional deformities have not been investigated.

Objectives

Therefore, we asked if patients undergoing femoral osteotomies for torsional deformities of the femur have (1) decreased hip pain and improved function and (2) subsequent surgeries and complications?