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
Since its first description in 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).Introduction
Objectives
Magnetic resonance imaging with intraarticular contrast (arthro-MRI) and radial cuts is the gold standard to quantify labral and chondral lesions in the setting of femoroacetabular impingement. To date, no study exists that has evaluated these findings as potential predictors of outcome for the long term follow-up after surgical treatment of FAI. The purpose of this study was to detect potential predictors for failure after surgical hip dislocation for FAI based on specific preoperative arthro-MRI of the hip at a minimum follow-up of 10 years.Introduction
Objectives
Labral refixation has established as a standard in open or arthroscopic treatment for femoroacetabular impingement (FAI). The rationale for this refixation is to maintain the important suction seal in the hip. To date, only few short-term results are available which indicate a superior result in FAI hips with labral refixation compared to labral resection. Scientific evidence of a beneficial effect of labral refixation in the long-term follow-up is lacking. Aim of this study was to evaluate if labral refixation can improve the cumulative 10-year survivorship in hips undergoing surgical hip dislocation for FAI compared to labral resection. We performed a retrospective comparative study of 59 patients treated with surgical hip dislocation for symptomatic FAI between December 1998 and January 2003. We analyzed two matched groups: The ‘resection’ group consisted of 25 hips that were treated consistently by excision of the damaged labrum. The ‘refixation’ group consisted of 34 hips that were treated with labral reattachment. Correction of the osseous deformity (rim trimming/femoral osteochondroplasty) did not differ between the two groups. We then evaluated the clinical (Merle d'Aubigné score) and radiographical results (according to Tönnis) at a follow-up of ten years. We calculated a cumulative Kaplan-Meier survivorship curve with the following factors as endpoints: conversion to total hip arthroplasty (THA), radiographic evidence of osteoarthritis progression, or a poor clinical result (defined as Merle d'Aubigné score of less than 15). The two curves were compared using the Log-rank test.Introduction & Objective
Methods
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. 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?Introduction
Objectives
Correct postoperative leg length restoration is among the most important goals of hip arthroplasty. Therefore, we developed, validated and clinically applied a novel software algorithm based on surgical navigation, which allows the surgeon to restore a defined femur position without establishing a femoral coordinate system or the hip joint center and measure the leg length accurately and simply. This new leg length algorithm was used in 154 hips (145 patients) that underwent CT-based computer-assisted THA (VectorVision Build 274 prototype; BrainLAB AG, Helmstetten, Germany) with a tissue preserving superior capsulotomy. Intraoperatively, a pelvic and a femoral dynamic reference bases (DRB) were applied and the anterior pelvic plane (APP) was set as the pelvic coordinate system. Then, the hip joint was put in a neutral position and this position, and the relative position of the femoral DRB relative to the pelvic DRB, was captured and stored by the navigation system. After implantation of the prosthesis the same above described femoral position with the same amplitude of flexion/extension, abduction/adduction and rotation was restored. Now, any resulting difference was due to linear changes. Validation of this new algorithm was performed by comparing the navigated results to measurements from calibrated antero-posterior pre- and postoperative radiographs. The radiographic results were compared to the mean leg length change measured with the navigation system.Introduction
Material and Methods
Young patients have been reported to have a higher risk of revision following total hip arthroplasty than older cohorts. This was attributed to the higher activity level which led to increased wear, osteolysis, and component fracture. We prospectively assessed the clinical results, wear and osteolysis, the incidence of squeaking, and the survivorship of ceramic on ceramic THA in patients younger than 50 years (mean age of 42 [18–50] years). The series included 425 THAs in 370 patients with 368 hips followed for a minimum of 2 years (mean 7.1 years, range 2–14 years). All patients received uncemented acetabular components with flush-mounted acetabular liners using an 18 degree taper. No osteolysis was observed in any uncemented construct. There was osteolysis around one loose cemented femoral component. The survivorship for reoperation for implant revision was 96.7%. There were only two acetabular liner fractures (0.47%) and one femoral head fracture (0.24%). Two of the three fractures involved a fall from a significant height. There were no hip dislocations. Five patients (1.17%) noted rare or occasional squeaking. None had reproducible squeaking. In summary, the current study shows that ceramic-on-ceramic THAs in the young patient population are extremely reliable with a very low revision rate and an absence of wear-induced osteolysis. In addition, it shows that both bearing fracture in this young patient population typically occurs with polytrauma and squeaking issues that have been raised relative to ceramic bearings occur very rarely with the flush-mounted ceramic liner design used in this study.
Half of all acetabular components placed using conventional methods are malpositioned1. The HipSextant™ Navigation System (Surgical Planning Associates, Boston, MA) is a mechanical navigation system, adjusted on a patient-specific basis, designed to achieve appropriate cup alignment as simply and rapidly as possible. The current study assesses the surgeon's ability to register and track the pelvis and align the cup using the system. A bioskills model pelvis (Pacific Research Laboratories, Inc., Vashon, WA) was prepared by placing screws to mark the anterior pelvic plane points and by inserting a long cup alignment pin, simulating a cup insertion handle, into the acetabulum. The bone model was then scanned using CT. The HipSextantTM Navigation System Planning Application was then used to plan the use of the HipSextant for the surgery. This is accomplished by creating a 3D model, designating the AP plane (marked by the screws), and then determining the HipSextant docking points. One of these three points is behind the posterior wall of the acetabulum (the basepoint). The second of these three points is on the lateral aspect of the anterior superior iliac spine. The third point, the landing point, is located on the surface of the ilium and equally distant from the other two points (Figure 1). The two protractors on the HipSextant planning application were then adjusted to be parallel with the cup alignment pin on the bone model. A surgeon and assistant were then asked to dock the HipSextant on the bone model and to visually align the direction indicator to be parallel with the cup alignment pin. The two protractor angles on the instrument were recorded. This allowed for calculation of error in operative anteversion and operative inclination between the plan and the actual alignment that was accomplished. Four pairs of surgeon and assistant each performed the docking and alignment procedure 10 times for a total of 40 measurements.Introduction
Methods
Acetabular component malpositioning is the most common reason for instability and wear resulting in revision total hip arthroplasty (THA). The current study aimed to assess a novel mechanical navigation device which was designed to simply and efficiently indicate appropriate cup orientation during surgery. The accuracy was compared to a series of hip arthroplasties performed using CT-based computer-assisted cup placement. The study group consisted of 70 THAs performed using the mechanical device. The control group consisted of 146 THAs performed using CT-based computer navigation. Postoperative cup positioning was measured using a validated 2D/3D-matching method. An outlier was defined outside a range of ± 10 degrees from the planned inclination or anteversion. In the study group the mean accuracy for inclination was 1.3 ± 3.4 (-6.6 – 8.2) and 1.0 ± 4.1 (-8.8 – 9.5) for anteversion with no outliers for either parameter. In the control group the accuracy for anteversion (3.0 ± 5.8 [-11.8 - 19.6]; p=0.6%) and the percentage of outliers (6.8%; p=3.3%) differed significantly. The accuracy for inclination (3.5 ± 4.1 [-12.7 - 9.5]; p=21.4%) and the percentage of ouliers (4.8%; p=9.9%) did not differ significantly. The use of this mechanical navigation device can result in similar accuracy of acetabular cup orientation compared with CT-based surgical navigation. All cups were placed within a zone of ± 10 degree range of inclination and anteversion. This mechanical navigation device allows accurate cup navigation with minimal additional time and equipment.
The use of less invasive techniques for total hip arthroplasty (THA) has remained controversial with some studies showing a higher incidence of complications. The technique of performing total hip arthroplasty through a superior capsulotomy was developed to maximally preserve the soft tissue envelope surrounding the hip. The current study assesses the recovery and complications of hips replaced using conventional and tissue preserving techniques. 206 hips in 191 patients with a mean follow-up of 4.3 ± 1.0 (range, 3.2 – 5.9) years underwent total hip arthroplasty using the superior capsulotomy technique. The mean age at operation was 55.7 ± 12.9 (19 – 85) years and the operation was performed for 106 hips (51%) in men. The surgical technique involves exposing the superior hip joint capsule posterior to the medius and minimus, and anterior to the short external rotators. The femur is prepared with the femoral head in place and then the femoral head is excised without dislocation. These 206 hips were compared to a cohort of 279 hips replaced using the transgluteal exposure (control group). These 2 series were controlled for complexity and demographic factors. Recovery was evaluated using the Merle d'Aubigné score at 6 and 12 weeks postoperatively.Introduction
Methods
Total hip arthroplasty (THA) in patients with developmental dysplasia of the hip (DDH) has been associated with increased rates of complications and revision. Hip instability and wear-induced osteolysis are among the more common and serious of these problems. The current investigation prospectively assessed the survivorship and clinical results of patients with DDH treated by alumina ceramic-ceramic THA. We investigated 161 consecutive hips in 145 patients with DDH classified as Crowe type I (131 hips, 81%), II (26 hips, 16%), III (2 hips, 1%), and IV (2 hips, 1%). All patients had an uncemented titanium acetabular component with a flush mounted alumina ceramic-ceramic bearing. The mean age at operation was 48.0 ± 12.2 years (range, 18 – 79 years). The preoperative Merle d'Aubigné score was 11.4 ± 1.7 (6 – 15). 27 hips (17%) had at least one previous surgical procedure. 92 hips (57%) were replaced with the use of surgical navigation for acetabular component positioning. The mean cup diameter was 49.9 ± 3.4 mm (46 – 60 mm). 88 (55%) bearings were 28mm and 73 (45%) bearings were 32mm. At a mean follow-up of 6.1 ± 2.5 years (2 – 11.3 years), the mean Merle d'Aubigné score was 17.4 ± 0.9 (14 – 18). There were no cases of osteolysis or dislocation. There was one reoperation of an early displaced cup. In addition, there was one calcar crack that was cerclaged, one intraoperative trochanteric fracture also repaired at surgery. No patient complained of squeaking. 94 patients with 100 hips (61%) completed a questionnaire specifically asking for squeaking. None of these patients reported squeaking. The 10-year Kaplan Meier survivorship of the implants (revision of any component for any reason) was 99.4% (95% confidence interval 98.2-100%). Results of ceramic-ceramic THA in young patients with low to middle graded DDH after two to eleven years follow-up are promising with no radiographic signs of osteolysis or dislocation.
