Abstract

Aims

Femoroacetabular Junction Impingement (FAI) describes abnormalities in the shape of the femoral head–neck junction, or abnormalities in the orientation of the acetabulum. In the short term, FAI can give rise to pain and disability, and in the long-term it significantly increases the risk of developing osteoarthritis. The Femoroacetabular Impingement Trial (FAIT) aims to determine whether operative or non-operative intervention is more effective at improving symptoms and preventing the development and progression of osteoarthritis.

Standard evaluation and diagnosis of pincer-type femoroacetabular impingment (FAI) relies on anteroposterior (AP) radiographs, clinical evaluation, and/or magnetic resonance imaging (MRI). However, the current evaluation techniques do not offer a method for accurately defining the amount of acetabular rim overcoverage in pincer-type FAI. Several studies have remarked on the particular problems with radiographic evaluation, including beam divergence, difficulty with defining the acetabular rim, and pelvic tilt. Some studies have proposed methods to mitigate these issues; however, radiographic analysis still relies on projected and distorted images, making it difficult to acquire an accurate quantitative estimate of the amount of crossover. We propose a technique that utilises computed tomography (CT) data to accurately quantify the amount of acetabular crossover while accounting for known diagnostic problems, specifically pelvic tilt. This work describes a novel method that utilises CT data of a patient's afflicted hip joint region to assess the amount of acetabular overcoverage due to pincer deformity. The amount of overcoverage was assessed using a spline curve defined through the segmentation of the acetabular rim from CT data. To mitigate pelvic tilt, the user selected points to define both the pubic symphysis and the promontory in a lateral digitally reconstructed radiograph. The algorithm corrected the pelvic tilt by adjusting to a defined neutral position (in our case, a 60°), and the user adjusted for slight rotation differences ensuring there was a vertical line connecting the symphysis and the sacrococcygeal joint. After successfully repositioning the pelvis, the algorithm computed the amount of acetabular overcoverage. The algorithm identified the superolateral point of the acetabulum and the most inferior points of the anterior and posterior rim. A line, the mid-acetabular axis, was constructed between the superolateral point and the midpoint of the most inferior points on the anterior and posterior rims; the mid-acetabular axis was extended anterior and posterior to create a plane. Crossover occurred when the anterior rim of the acetabulum intersected this plane. If an intersection occurred, the algorithm measured the length of the mid-acetabular axis, and the length and width of the section representing overcoverage. These points were then projected onto anteroposterior DRRs and again measured to generate a basis of comparison. We tested our method on four cadaveric specimens to analyze the relationship between radiographic assessment and our technique. We simulated varying degrees of impingement in the cadavers by increasing the amount of pelvic tilt and defining that as the neutral position for a given trial. Moreover, we assessed interobserver variability in repositioning the pelvis as to the effect this would have on the final measurement of crossover length and width. The software achieved consistent, quantitative measurements of the amount of acetabular overcoverage due to pincer deformity. When compared with conventional radiographic measurements for crossover, there was a significant different between the two modalities. Specifically, both the ratios of crossover length to acetabular length and crossover width to crossover length were less using the CT-based approach (p < 0.001). Moreover, there were no significant differences between observers using our approach. The proposed technique can form the basis for a new way to diagnosis and measure acetabular overcoverage resulting in pincer impingement. This computational method can help clinicians to accurately correct for tilt and rotation, and subsequently provide consistent, quantitative measurement of acetabular overcoverage

Slipped capital femoral epiphysiolysis (SCFE) is a rare condition with a unknown aetiopathogenesis. An early diagnosis and treatment is essential to minimize premature degeneration of the joint. The authors reviewed the cases treated between 1980 and 2005 in our institution. This study was aimed at evaluating patients with hip epiphysiolysis surgically treated by canullated screws or pinning and previously controlled by short-term follow-up, in order to evaluate radiographic medium/ long term evolution, looking for evidence of degenerative arthritis or femoroacetabular impingement. We performed a retrospective review of the clinical notes and radiographs of all patients with slipped upper femoral epiphysis who were surgically treated at our institution between January 1980 and December 2005. These patients performed radiographs to detect evidence of osteonecrosis, chondrolysis, degenerative arthritis or femoroacetabular impingment. To grade the radiological osteoarthritic changes the grading system of Kellgren and Lawrence was used. These changes were correlated with the existence of femoroacetabular impingement. The radiological results were correlated with the Loder'sclassification of stability and the morphological classification. 43 patients were reviewed, corresponding to 47 treated hips. AP and Lowenstein x-ray views were taken in all patients. The alfa angle and the head-shaft angle were measured in the Lowenstein view (frog-leg). Of 16 patients with impingement only 1 patient didn't present pistol grip deformity. 4 contralateral hips also presented the deformity. The mean alfa angle was 99,4. 43% of the patients with unstable hips have impingment. In stable hips this percentage is of 35%. The Patrick test was positive in 30% of the hips with SCFE and only 17% of the unafected hips. The Kellgren and Lawrence scale was very diferent between trhe SCFE and control groups, with 43% grade 2, 17% grade 3 and 6% grade 4, versus 30% grade 2, 6% grade 3 and 0% grade 4. Some patients show bilateral pistol grip deformity and clinical signs of impingment, despite only having one hip with SCFE

Purpose: The purpose of this study was to examine the arthroscopy findings in the hips of patient with persistent pain after surgical hip dislocation for femoroacetabular impingement syndrome.

Type of study: Retrospective, consecutive series of patients

Patients and Methods: Sixteen consecutive patients (6 male/10 female; average age 33,5 years 19–60y) with persistent pain after surgical hip dislocation for the treatment of femoroacetabular impingement were included. At the index surgery, all patients had an osteo-chondroplasty of the head neck junction and a resection of the acetabular rim with reattachment of the labrum in 9 cases. All patients had a preoperative arthro-MRI and were treated with arthroscopy of the hip.

Results: At arthroscopy all reattached labra were stable. In the cases without preservation of the labrum, the joint capsule was attached level with the acetabular rim and had important synovitis. All patients had adhesions between the neck of the femur and joint capsule or between labrum and capsule. In 3 patients the arthroscopic procedure was technically limited by massive thickening of the capsule. Overall 75% (12 of 16) patients showed less pain or were pain free. MDA improved from preoperatively 13 to 16 points at last follow up.

Conclusions: Persistent pain after surgical dislocation of the hip could result from intraarticular adhesions that can be shown in the MRI. Hip arthroscopy after previous surgery can be demanding due to scarring. If the adhesions can be released good results can be achieved. Hip arthroscopy is a save therapeutical tool to treat patients with intraarticulary adhesions after surgical dislocation of the hip for femoroacetabular impingement.

Open reduction of the prominence at the femoral head-neck junction in femoroacetabular impingement has become an established treatment for this condition. We report our experience of arthroscopically-assisted treatment of femoroacetabular impingement secondary to paediatric hip disease in 14 hips in 13 consecutive patients (seven women, six men) with a mean age of 30.6 years (24 to 39) at the time of surgery. The mean follow-up was 2.5 years (2 to 4).

Radiologically, 13 hips had successful restoration of the normal geometry and only one had a residual deformity. The mean increase in the Western Ontario McMasters Osteoarthritis Index for the series at the last follow-up was 9.6 points (4 to 14). No patient developed avascular necrosis or sustained a fracture of the femoral neck or any other complication.

These findings suggest that femoroacetabular impingement associated with paediatric hip disease can be treated safely by arthroscopic techniques.