Lesion size measurement in femoral head necrosis.

BACKGROUND: Management of patients with early stages of osteonecrosis of the femoral head remains controversial. Uniform use of an effective method of evaluation and classification, including both stage and lesion size, would allow for comparison and would significantly improve treatment of patients. There is no consensus on how best to determine lesion size. The purpose of this study was to evaluate and compare accuracy and ease of use of different techniques for determining the size of femoral head lesions. METHODS: Twenty-five hips with stages I or II osteonecrosis were evaluated with radiographs and MRI. 3-D MRI measurements of lesion size were used as the standard against which to compare visual estimates and angular measurements: necrotic angle of Kerboul, index of necrosis, and adjusted index of necrosis. RESULTS: 3-D measurements (necrotic volume) showed regular progression from 2.2 to 59.2% of the femoral head. There was a rough correlation with angular measurements; index of necrosis was closer than the necrotic angle. Visual estimates from serial MRI images were as accurate as angular measurements. CONCLUSIONS: Simple visual estimates of lesion size from serial MRI images are reasonably accurate and are satisfactory for clinical use. Angular measurements provide some indication of prognosis and treatment; however, they have limited accuracy, with considerable variability between techniques. 3-D MRI volumetric measurements are the most accurate. Using current techniques and software, they are easier to use, requiring similar time and effort to angular measurements. They should be considered for clinical research and publications when the most accurate measurements are required.

Are we evaluating osteonecrosis adequately?

PURPOSE: It is well recognised that to evaluate a patient with osteonecrosis of the femoral head (ONFH) adequately, it is necessary that the size of the infarct and the extent of femoral head joint involvement be indicated, in addition to the type or stage of the pathological process. The purpose of this study was to determine whether patients with ONFH are being evaluated adequately in studies published during the past 25 years and to see if any trends can be identified. METHODS: Articles describing treatment of patients with ONFH, published between 1985 and 2011, were reviewed to determine the methods used to indicate the type and extent of pathology present on radiographs and magnetic resonance imaging (MRI) studies. The classification systems cited were identified and divided between those which indicated only the stage and those which indicated both stage and extent of involvement. RESULTS: In 208 studies published between 1985 and 2011, specific classification systems were cited 237 times. During this period, non-quantitative systems, which only indicate stage, were cited 139 times (59 %) and quantitative systems, which indicate both stage and extent of involvement were cited 77 times (32 %). Between 2006 and 2011, non-quantitative systems were cited 30 times (48 %) and quantitative systems were cited 27 times (44 %). CONCLUSIONS: During the past 25 years there has been a trend towards the use of more comprehensive and effective methods of evaluating patients with ONFH. However, during the past five years, approximately half of the published studies continued to use limited, non-quantitative methods of evaluation. This should be brought to the attention of the orthopaedic community. Future investigations and publications on ONFH should employ comprehensive methods of classification which include not only the stage of disease but also measurements of the size of the necrotic segment and the extent of femoral head and joint involvement.

A comparison between total hip replacement for osteonecrosis and degenerative joint disease.

There has been some reluctance to perform total hip replacement on younger patients with osteonecrosis because of the poor results reported in the earlier literature. To determine the extent to which advances in surgical technique and prosthesis design have led to improved results, we evaluated 203 total hip replacements performed for osteonecrosis and compared them to 300 performed for degenerative joint disease. The failure rate for all femoral and acetabular components combined was 3.7% (22 of 600), in degenerative joint disease and 10.1% (41 of 406) in osteonecrosis. However, results with the most recently used acetabular component, the noncemented HGP-1, were markedly improved over earlier components in both conditions, with only 1 failure in 235 hips (0.4%). The increased survivorship of THR in osteonecrosis with improved component design and surgical technique is encouraging. Total hip replacement is a good option for patients with advanced stages of osteonecrosis, and similar surgical indications should be used for patients with degenerative joint disease and other disorders.

Determining lesion size in osteonecrosis of the femoral head.

BACKGROUND: Several studies have documented that the size of the osteonecrotic lesion in the femoral head is an essential parameter in determining prognosis and treatment. There are several methods currently available to measure lesion size, but no general agreement as to which is most useful. In the present study, three different radiographic methods for determining lesion size were evaluated and compared. METHODS: Anteroposterior and lateral radiographs of forty-two hips with osteonecrosis were examined. The extent of osteonecrotic involvement of the femoral head was determined through the use of three different methods: the volume of necrosis by quantitative digital image analysis, and the angular measurements described by Kerboul et al. and Koo and Kim. Graphs were constructed to demonstrate these relationships. RESULTS: Volumetric measurement appeared to be the most reliable. There was only a rough correlation with angular measurements. Several sources of error were noted when simple angular measurements of irregular, three-dimensional lesions were used. The Kerboul method routinely overestimated lesion size and designated 81% of the lesions as "large." The modified Koo and Kim method provided a more even distribution of lesion size and correlated with volumetric measurements in 74% of hips (thirty-one of forty-two hips). CONCLUSIONS: Quantitative volumetric measurements appear to be the most reliable method to measure the true size of a three-dimensional osteonecrotic lesion of the femoral head. Volumetric measurement is more accurate than angular measurement and can be performed easily with modern technology. Angular measurements, although somewhat simpler to use than volumetric measurements, may provide only a rough estimate of lesion size, partly due to the considerable differences in outline or location of the necrotic segments. Nevertheless, determination of lesion size must be part of a comprehensive system of staging of this disease, which includes the evaluation of other parameters, such as the extent and degree of articular surface involvement and the status of the hip joint and the acetabulum. LEVEL OF EVIDENCE: Diagnostic Level III. See Instructions to Authors on jbjs.org for a complete description of levels of evidence.

Systematic analysis of classification systems for osteonecrosis of the femoral head.

BACKGROUND: Multiple classification systems for osteonecrosis of the hip have been developed to assist physicians in the diagnosis and treatment of this potentially debilitating disorder. The purpose of this analysis was to delineate the classification systems utilized in reports published since 1985 and, through a comparison of the most commonly used systems, to identify consistent factors that would allow for cross-publication comparisons to be made. METHODS: We performed a PubMed search for reports of outcome studies concerning treatment methods for osteonecrosis of the hip. All studies of reported outcomes with greater than ten patients were included in the analysis. Various classification systems were tabulated to determine usage frequencies. The four most commonly used systems were then analyzed to determine common factors used for classification. RESULTS: One hundred and fifty-seven studies were available for analysis. Sixteen major classification systems that made use of more than one radiographic factor were identified, and nine of these systems had one to five modifications reported throughout the literature. Additionally, eleven other systems made use of single factors obtained from either magnetic resonance imaging or anatomic data. The review revealed that four classification systems accounted for greater than 85.4% of the reported studies. Parameters for these four systems were stratified to allow for uniformity of patient or study evaluation. CONCLUSIONS: This analysis of the reported classification systems for osteonecrosis of the femoral head revealed several similarities between the most commonly used systems. An analysis of patients can be made with any of the four major systems if specific data are collected according to various magnetic resonance imaging and radiographic findings. This approach will allow for easier comparison of studies across different centers. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions to Authors on jbjs.org for a complete description of levels of evidence.

Osteonecrosis of the femoral head: diagnosis and classification systems.

Osteonecrosis of femoral head is a rare but disabling condition that usually results in progressive femoral head collapse and secondary arthritis necessitating total hip arthroplasty if not treated appropriately in early stages. However, early diagnosis is challenging as the onset of disease is insidious and the symptoms and signs are usually minimal and nonspecific until it becomes advanced. Of several diagnostic modalities, magnetic resonance imaging (MRI) is considered the imaging method of choice with the highest sensitivity and specificity, while detection of potential risk factors is very important as well. Many investigators have developed several different classification systems; however, there still is controversy regarding the optimal classification system. Diagnostic methods and the evolution of different classification systems will be reviewed in this paper.

Early failure of precoated femoral components in primary total hip arthroplasty.

BACKGROUND: In an effort to decrease the rate of aseptic loosening, certain cemented femoral components were designed to have a roughened or textured surface with a methylmethacrylate precoating. Reports differ as to whether this step has increased or decreased the rate of failure. This study was designed to evaluate this issue. METHODS: Five hundred and fourteen hips treated with a cemented Harris Precoat stem (Zimmer, Warsaw, Indiana) were evaluated clinically and radiographically and compared with 254 hips treated with an uncoated Harris Design-2 stem (Howmedica, East Rutherford, New Jersey). Prostheses that had been removed at revision were examined. The cementing and surgical techniques were identical and the population demographics were similar for these two groups. RESULTS: The mean durations of follow-up were 8.4 and 13.5 years for the Precoat and uncoated Design-2 stems, respectively. At those times, at least forty-nine (9.5%) of the 514 Precoat components and at least ten (3.9%) of the 254 uncoated Design-2 stems had failed (p = 0.006). Five Precoat stems fractured, and no uncoated Design-2 stems fractured. Component failure was associated with use in young, active, heavy men with a diagnosis of avascular necrosis and generally with the use of smaller components. The cementing technique was satisfactory in the majority of the patients, and there were no qualitative differences in cementing technique between the hips that failed and those that did not. The mechanisms of failure of the Precoat prostheses included bone-cement loosening, focal osteolysis, stem fracture, and prosthesis-cement debonding. Fractures of smaller components occurred as a result of fatigue failure and were associated with good distal fixation but proximal stem loosening. CONCLUSIONS: The rate of failure of roughened, precoated, cemented femoral components was considerably higher and occurred earlier than that of femoral components that were neither textured nor precoated with methylmethacrylate. Younger patients with avascular necrosis had a higher risk of failure; however, this factor alone did not completely explain the differences in outcome between these two components. The causes of aseptic loosening are multifactorial and may be related to component design and size as well as to precoating and surface finish.

Classification systems for osteonecrosis: an overview.

Currently a number of classification systems for osteonecrosis are in use. The use of different systems often leads to confusion and makes it difficult to compare the results of different methods of treatment. Because the management of osteonecrosis is determined in large part by the stage of the disease, it is important to use an effective and reliable method of staging and classification. This article provides an overview of the systems most commonly used so the reader can better understand and compare the outcome of studies that report their results using different methods of classification. The essential features of the ideal system are outlined to enable the reader to decide which of the available classification systems best meets these goals.

Bilateral core decompression for osteonecrosis of the femoral head.

UNLABELLED: Early treatment of osteonecrosis of the femoral head yields better results than late treatment. Because osteonecrosis frequently is bilateral, it often is advisable to treat both hips simultaneously. Core decompression is one of the more common methods of treatment; however the safety of doing simultaneous bilateral core decompression has been questioned. We sought to evaluate the safety and effectiveness of simultaneous bilateral core decompression compared with unilateral core decompression. One hundred ninety-three patients (276 hips) who had core decompression with bone grafting were followed up for 24 to 145 months. One hundred twenty-four procedures were unilateral and 152 were bilateral. Patients were evaluated by change in Harris hip score, radiographic progression, postoperative complications, and conversion to total hip arthroplasty. Total hip arthroplasty was required in 56 of 124 (45%) of hips in the unilateral, and 48 of 152 (32%) of hips in the bilateral group. Postoperative complications were similar. In the unilateral group there were two major and nine minor complications; in the bilateral group there were three major and 10 minor complications. When bilateral core decompression is indicated, it can be done simultaneously on both hips, allowing earlier treatment of the contralateral hip without risk of increased complications and possibly with a better outcome. It requires only one hospitalization and decreases recovery time compared with two separate procedures. Therefore, it provides advantages over procedures that cannot be done simultaneously on both hips. LEVEL OF EVIDENCE: Therapeutic study, Level IV (case series-no common or historical control group). See the Guidelines for Authors for a complete description of levels of evidence.

Does pain predict outcome in hips with osteonecrosis?

It generally is accepted that without specific treatment 70-80% of hips with clinically diagnosed osteonecrosis will progress to collapse. However, there are conflicting reports regarding the relationship between pain and outcome before femoral head collapse. Some surgeons are reluctant to operate on patients with asymptomatic or minimally symptomatic hips, assuming that these patients have a better prognosis than patients with pain. This study reviewed the outcome of 328 hips in 235 patients with nontraumatic osteonecrosis, all treated with core decompression and grafting. The preoperative stage, the extent of necrosis, and the Harris pain scores were correlated with the clinical and radiographic outcomes. Mean followup was 46 months. Patients with hips treated surgically did better as a group than patients with hips treated without surgery. A direct correlation was found between outcome and the stage and size of the necrotic lesion. Hips that had femoral head collapse were more painful than hips that did not have collapse and had a poorer outcome. Before collapse, outcome was correlated with the size of the necrotic lesion but there was no correlation with the preoperative pain level. These findings, although limited to patients with hips which had core decompression and grafting, support the observations of investigators who reported that most asymptomatic hips with osteonecrosis would progress without specific treatment. They also may apply to hips which have other forms of prophylactic treatment. Although several factors must be considered in determining the optimum treatment of hips with early stages of osteonecrosis, prophylactic treatment should not be withheld specifically because of the absence or paucity of pain.