Helen Anwander

Surgical Correction of Cam Deformity in Association with Femoroacetabular Impingement and Its Impact on the Degenerative Process within the Hip Joint

Background: Cam morphology in association with femoroacetabular impingement (FAI) is a recognized cause of hip pain and cartilage damage and proposed as a leading cause of arthritis. The purpose of this study was to analyze the functional and biomechanical effects of the surgical correction of the cam deformity on the degenerative process associated with FAI. Methods: Ten male patients with a mean age of 34.3 years (range, 23.1 to 46.5 years) and a mean body mass index (and standard deviation) of 26.66 ± 4.79 kg/m2 underwent corrective surgery for cam deformity in association with FAI. Each patient underwent a computed tomography (CT) scan to assess acetabular bone mineral density (BMD), high-resolution T1&rgr; magnetic resonance imaging (MRI) of the hips to assess proteoglycan content, and squatting motion analysis as well as completed self-administered functional questionnaires (Hip disability and Osteoarthritis Outcome Score [HOOS]) both preoperatively and 2 years postoperatively. Results: At a mean follow-up of 24.5 months, improvements in functional scores and squat performance were seen. Regarding the zone of impingement in the anterosuperior quadrant of the acetabular rim, the mean change in BMD at the time of follow-up was −31.8 mg/cc (95% confidence interval [CI], −11 to −53 mg/cc) (p = 0.008), representing a 5% decrease in BMD. The anterosuperior quadrant also demonstrated a significant decrease in T1&rgr; values, reflecting a stabilization of the cartilage degeneration. Significant correlations were noted between changes in clinical functional scores and changes in T1&rgr; values (r = −0.86; p = 0.003) as well as between the BMD and maximum vertical force (r = 0.878; p = 0.021). Conclusions: Surgical correction of a cam deformity in patients with symptomatic FAI not only improved clinical function but was also associated with decreases in T1&rgr; values and BMD. These findings are the first, to our knowledge, to show that alteration of the hip biomechanics through surgical intervention improves the overall health of the hip joint. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Erratum to: What MRI Findings Predict Failure 10 Years After Surgery for Femoroacetabular Impingement?

In the study, ‘‘What MRI Findings Predict Failure 10 Years After Surgery for Femoroacetabular Impingement?’’ the overview of the study population in Fig. 1 is incorrect as published. A total of 20 hips underwent MRA at another institution, not eight hips. Additionally, 10 hips had been operated on the contralateral side with a similar appearance, not 22 hips. The corrected Fig. 1 is shown in this erratum. We apologize for the error. Surgical Treatment for Symptomatic FAI July 2001 – March 2003 n = 146

Magnetic Resonance Imaging of the Native Hip Joint

One of the key reasons for the tremendous growth and interest in the operative management of the young adult with hip pain1,2 is advancements in high-resolution magnetic resonance imaging (MRI)3,4. Although radiographs provide critical information with regard to the osseous architecture and should always remain the first line of investigation, they are limited in their capacity to provide a detailed analysis of the other key anatomical components. MRI is the modality that provides the most comprehensive imaging of the hip joint, allowing for visualization of anatomy and detection of pathological conditions of the various structures, including the labrum, articular cartilage, synovium, and bone. The investigations of labral pathological conditions, femoroacetabular impingement, and early hip arthritis areas are studies in which MRI excels over all other imaging modalities. In this article, we review the basic principles of MRI in the evaluation of the native hip joint and the most common pathological conditions of the hip with their characteristic MRI findings. In clinical practice, 1.5 or 3-Tesla (T) field strength MRI scanners are the most commonly used. Higher field strengths can be favorable as they provide higher signal-to-noise and contrast-to-noise ratios5,6. MRI has multiplanar image acquisition capability. It is …

Influence of evolution on cam deformity and its impact on biomechanics of the human hip joint: EVOLUTION OF CAM DEFORMITY

Anatomy and biomechanics of the human hip joint are a consequence of the evolution of permanent bipedal gait. Habitat and behaviour have an impact on hip morphology and significant differences are present even within the same biological family. The forces acting upon the hip joint are mainly a function of gravitation and strength of the muscles. Acetabular and femoral anatomy ensure an inherently stable hip with a wide range of motion. The femoral head in first human ancestors with upright gait was spherical (coxa rotunda). Coxa rotunda is also seen in close human relatives (great apes) and remains the predominant anatomy of present‐day humans. High impact sport during adolescence with open physis however can activate an underlying genetic predisposition for reinforcement of the femoral neck, causing an epiphyseal extension and the formation of an osseous asphericity at the antero‐superior femoral neck (cam deformity). The morphology of cam deformity is similar to the aspherical hips of quadrupeds (coxa recta), with the difference that in quadrupeds the asphericity is posterior. It has been postulated that this is due to the fact that humans bear weight on the extended leg, while quadrupeds bear weight at 90–100° flexion. The asphericity alters the biomechanical properties of the joint and as it is forced into the acetabulum leading to secondary cartilage damage. It is considered a risk factor for later development of osteoarthritis of the hip. Clinically this presents as reduced range of motion, which can be an indicator for the structural deformity of the hip.

Traumatic Avascular Necrosis of the Femoral Head

Avascular necrosis (AVN) of the femoral head is a rare but devastating complication following fractures of the proximal femur or hip dislocation. Traumatic AVN derives from the interruption of the blood flow to the femoral head, which is mainly supplied by the medial circumflex femoral artery (MCFA) in the adult hip [1, 2]. The incidence of AVN depends on the fracture pattern and the integrity of the deep branch of the MCFA. In addition to traumatic interruption of the femoral head blood supply, the MCFA can be injured iatrogenically. Symptoms and radiographic changes in hips with AVN of the femoral head usually occur late and often months after the trauma. There is no curative treatment and therefore prevention is most important. While total hip arthroplasty shows very good clinical results in elderly patients, it is not the treatment of choice in children and adolescents with AVN. For this age group, hip preserving alternatives include core decompression, femoral osteotomies, and various bone grafting techniques.