Paul E. Beaulé

Metal-on-Metal Hybrid Surface Arthroplasty: Two to Six-Year Follow-up Study

BACKGROUND Following the reintroduction of metal-on-metal articulating surfaces for total hip arthroplasty in Europe in 1988, we developed a surface arthroplasty prosthetic system using a metal-on-metal articulation. The present study describes the clinical and radiographic results of the first 400 hips treated with metal-on-metal hybrid surface arthroplasties at an average follow-up of three and a half years. METHODS Between November 1996 and November 2000, 400 metal-on-metal hybrid surface arthroplasties were performed in 355 patients. All femoral head components were cemented, but only fifty-nine of the short metaphyseal stems were cemented. The patients had an average age of forty-eight years, 73% were men, and 66% had a diagnosis of osteoarthritis. Clinical and radiographic follow-up were performed at three months postoperatively and yearly thereafter. RESULTS The majority of the patients returned to a high level of activity, including sports, and 54% had activity scores of >7 on the University of California at Los Angeles activity assessment system. Kaplan-Meier survivorship curves demonstrated that the rate of survival of the components at four years was 94.4%. For patients with a surface arthroplasty risk index score of >3, the rate of survival of the components at four years was 89% compared with a rate of 97% for those with a score of </=3. The patients with a higher risk index were 4.2 times more likely to undergo revision to a total hip replacement at four years. Twelve hips (3%) had a revision to a total hip replacement. Seven of the twelve hips were revised because of loosening of the femoral component, and three were revised because of a femoral neck fracture. Substantial radiolucencies were seen around sixteen uncemented metaphyseal femoral stems. No femoral radiolucencies were observed among the hips in which the metaphyseal stem was cemented. The most important risk factors for femoral component loosening and substantial stem radiolucencies were large femoral head cysts (p = 0.029), patient height (p = 0.032), female gender (p = 0.005), and smaller component size in male patients (p = 0.005). CONCLUSIONS The preliminary experience with this hybrid metal-on-metal bearing is encouraging. Optimal femoral bone preparation and component fixation are critical to improving durability. The metal-on-metal hybrid surface arthroplasty is easily revised to a standard femoral component if necessary. LEVEL OF EVIDENCE Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.

A Systematic Approach to the Plain Radiographic Evaluation of the Young Adult Hip

Orthopaedic evaluation of hip pain in the young adult population has undergone a rapid evolution over the past decade1,2. This is in large part due to enhanced awareness of structural hip disorders, including developmental dysplasia of the hip and femoroacetabular impingement1-5. Surgical treatment for these disorders continues to be refined6-9, and our ability to identify patients along the spectrum of disease continues to improve10-15. Yet, despite our advances, obtaining an accurate diagnosis can remain challenging, especially in the setting of mild structural abnormalities. Therefore, radiographic examination is a critical component of the diagnostic evaluation and treatment decision-making process. It is essential that physicians have common and reliable radiographic views as well as parameters for plain radiographic assessment that can serve as a foundation for accurate diagnosis, disease classification, and surgical decision-making. Many different radiographic measurements have been described as indicators of structural disease. In particular, measurements such as the lateral center-edge angle of Wiberg16, the anterior center-edge angle of Lequesne17, the ac-etabular index of depth to width described by Heyman and Herndon18, the femoral head extrusion index19, and the Tonnis angle20 have been used as markers for acetabular dysplasia. Similarly, measurements of acetabular version21, the head-neck offset (initially described by Eijer)3,22, and the alpha angle19 have been used in the diagnosis of femoroacetabular impingement. Nevertheless, there is limited literature that provides comprehensive information regarding the details of radiographic evaluation in the young patient with hip symptoms. This paper summarizes the recommendations of the ANCHOR (Academic Network for Conservational Hip Outcomes Research) study group regarding the most important aspects of radiographic technique and image interpretation to evaluate the symptomatic, skeletally mature hip.

The concept of femoroacetabular impingement: current status and future perspectives.

Femoroacetabular impingement (FAI) is a recently proposed mechanism causing abnormal contact stresses and potential joint damage around the hip. In the majority of cases, a bony deformity or spatial malorientation of the femoral head or head/neck junction, acetabulum, or both cause FAI. Supraphysiologic motion or high impact might cause FAI even with very mild bony alterations. FAI became of interest to the medical field when (1) evidence began to emerge suggesting that FAI may initiate osteoarthritis of the hip and when (2) adolescents and active adults with groin pain and imaging evidence of FAI were successfully treated addressing the causes of FAI. With an increased recognition and acceptance of FAI as a damage mechanism of the hip, defined standards of assessment and treatment need to be developed and established to provide high accuracy and precision in diagnosis. Early recognition of FAI followed by subsequent behavioral modification (profession, sports, etc) or even surgery may reduce the rate of OA due to FAI.

Quality of life following femoral head-neck osteochondroplasty for femoroacetabular impingement

BACKGROUND Femoroacetabular impingement has been recently described as a common cause of hip pain and labral tears in young adults. We evaluated the early clinical results and quality of life after osteochondroplasty of the femoral head-neck junction for the treatment of femoroacetabular impingement. METHODS Thirty-seven hips in thirty-four patients with persistent hip pain and a mean age of 40.5 years underwent surgical dislocation of the hip and osteochondroplasty of the femoral head-neck junction for the treatment of camtype femoroacetabular impingement. All of the patients had had preoperative evidence of pathological changes in the labrum on imaging. The clinical course and the quality of life were assessed postoperatively. RESULTS The mean score on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) increased from 61.2 points preoperatively to 81.4 points at a mean of 3.1 years postoperatively (p < 0.001), the mean University of California at Los Angeles (UCLA) activity score increased from 4.8 to 7.5 points (p < 0.001), the mean Short Form-12 (SF-12) physical component score increased from 37.3 to 45.6 points (p < 0.001), and the mean SF-12 mental component score increased from 46.4 to 51.2 points (p = 0.031). None of the hips underwent additional reconstructive surgery. There were no cases of osteonecrosis. Nine patients underwent screw removal from the greater trochanter because of persistent bursitis. Six of the thirty-four patients were dissatisfied with the outcome. CONCLUSIONS Cam-type femoroacetabular impingement is associated with insufficient concavity at the anterolateral head-neck junction and with pathological changes in the labrum. Osteochondroplasty of the femoral head-neck junction following surgical dislocation of the hip joint is safe and effective and can provide a significant improvement in the overall quality of life of most patients. LEVEL OF EVIDENCE Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

Metal-on-metal Hip Resurfacing Arthroplasty

The main advantage of hip resurfacing is bone conservation for patients likely to outlive a primary conventional hip replacement. Previous attempts at hip resurfacing failed predominantly because of the consequences of a high amount of wear of thin polyethylene acetabular components and poor femoral component fixation. With correct patient selection, surgeon education, and operative technique, survivorship at five years is comparable with that of traditional hip replacements. Hip resurfacing has its own unique set of complications, including a fractured neck of the femur. It is necessary to understand the risk factors prior to performing the procedure.

Prevalence of associated deformities and hip pain in patients with cam-type femoroacetabular impingement

Femoroacetabular impingement is a cause of hip pain in adults and is potentially a precursor of osteoarthritis. Our aim in this study was to determine the prevalence of bilateral deformity in patients with symptomatic cam-type femoroacetabular impingement as well as the presence of associated acetabular abnormalities and hip pain. We included all patients aged 55 years or less seen by the senior author for hip pain, with at least one anteroposterior and lateral pelvic radiograph available. All patients with dysplasia and/or arthritis were excluded. A total of 113 patients with a symptomatic cam-impingement deformity of at least one hip was evaluated. There were 82 men and 31 women with a mean age of 37.9 years (16 to 55). Bilateral cam-type deformity was present in 88 patients (77.8%) while only 23 of those (26.1%) had bilateral hip pain. Painful hips had a statistically significant higher mean alpha angle than asymptomatic hips (69.9 degrees vs 63.1 degrees , p < 0.001). Hips with an alpha angle of more than 60 degrees had an odds ratio of being painful of 2.59 (95% confidence interval 1.32 to 5.08, p = 0.006) compared with those with an alpha angle of less than 60 degrees . Of the 201 hips with a cam-impingement deformity 42% (84) also had a pincer deformity. Most patients with cam-type femoroacetabular impingement had bilateral deformities and there was an associated acetabular deformity in 84 of 201 patients (42%). This information is important in order to define the natural history of these deformities, and to determine treatment.

Orientation Of The Femoral Component In Surface Arthroplasty Of The Hip: A Biomechanical And Clinical Analysis

BACKGROUND Although the orientation of the femoral component has been shown to influence the outcome of total hip replacement, its effect on the clinical outcome of surface arthroplasty has not been studied, to our knowledge. The purpose of this study was to examine the relationship between femoral component positioning and the outcome of a surface arthroplasty of the hip. METHODS We reviewed the results of ninety-four hybrid metal-on-metal surface arthroplasties in patients who were forty years old or younger at the time of the operation and were followed for a minimum of two years or until the prosthesis failed. Measurements of the hip reconstruction were made on the anteroposterior pelvic radiograph. The correlation between the orientation of the femoral component and the outcome of the arthroplasty was evaluated, as were stresses within the resurfaced femoral head as a function of the orientation of the femoral component. RESULTS The mean duration of follow-up was 4.2 years. Thirteen hips had an adverse outcome, defined as conversion to a total hip replacement, radiolucency of >1 mm in thickness adjacent to the femoral stem, or narrowing of the femoral neck of >10%. The mean femoral stem-shaft angle in the coronal plane was 138 degrees, with the hips that had an adverse outcome having a significantly lower mean angle than the rest of the cohort (133 degrees compared with 139 degrees, p = 0.03). Hips with an angle of <or=130 degrees had an increase in the relative risk of an adverse outcome by a factor of 6.1 (p < 0.004). In the entire cohort, stresses in the superior aspect of the resurfaced femoral head were substantially lower during slow walking than they were during fast walking (7.1 N/mm(2) compared with 14.2 N/mm(2)). CONCLUSIONS Optimizing the femoral stem-shaft angle toward a valgus orientation during the preparation of the femoral head is important when a hip is being reconstructed with a surface arthroplasty because the resurfaced hip transmits the load through a narrow critical zone in the femoral head-neck region and the valgus angulation may reduce these stresses.

Jumbo Femoral Head for the Treatment of Recurrent Dislocation Following Total Hip Replacement

Background: The purpose of this study was to assess the results of the use of a jumbo femoral head to restore stability in hips that had sustained recurrent dislocations after total hip replacement.Methods: Twelve hips in twelve patients who had had multiple hip operations and recurrent instability of the hip underwent a total hip replacement with use of a femoral head with an average diameter of 44 mm (range, 40 to 50 mm). The average age of the patients was fifty‐nine years (range, twenty‐nine to eighty‐four years). The twelve patients had had an average of four previous operations (range, one to eight operations) and seven dislocations (range, two to twenty dislocations). A bipolar head was used in ten hips that had a femoral stem with a fixed (non-modular) head, and a modular head (unipolar) was used in two hips. (One hip was first treated with a bipolar head and then with a unipolar head.)Results: One patient died of unrelated causes fourteen months postoperatively. The hip had remained stable until the time of death. After an average duration of follow‐up of 6.5 years (range, 3.2 to 11.8 years), ten of the remaining eleven hips had had no additional episodes of instability. One hip dislocated within one week after the revision, necessitating revision surgery to reposition the acetabular component. This hip was found to be stable at the time of follow-up 7.6 years after the revision. There were four other reoperations: one was done because of a fracture of the polyethylene; one, because of entrapment of cement within the articulation; one, because of pain related to loosening of the femoral stem; and one, because of late hematogenous infection. The preoperative and postoperative University of California at Los Angeles hip scores for the series were, respectively, 7 and 9 points for pain, 5 and 7 points for walking, 4 and 6 points for function, and 3 and 5 points for activity.Conclusions: A jumbo-diameter femoral head provided stability and improved function without compromising range of motion in patients with recurrent dislocations following total hip arthroplasty.

Notching of the femoral neck during resurfacing arthroplasty of the hip : A vascular study

During hip resurfacing arthroplasty, excessive valgus positioning or surgical technique can result in notching of the femoral neck. Although mechanical weakening and subsequent fracture of the femoral neck are well described, the potential damage to the retinacular vessels leading to an ischaemic event is relatively unknown. Using laser Doppler flowmetry, we measured the blood flow in 14 osteoarthritic femoral heads during routine total hip replacement surgery, before and after notching of the femoral neck. In ten hips there was a reduction in blood flow of more than 50% from the baseline value after simulated notching of the femoral neck. Our results suggest that femoral head vascularity in the osteoarthritic state is similar to the non-arthritic state, where damage to the extraosseous vessels can predispose to avascular necrosis. Surgeons who perform resurfacing arthroplasty of the hip should pay careful attention to these vessels by avoiding excessive dissection around the femoral neck and/or notching.

Prevention and treatment of dislocation after total hip replacement using large diameter balls.

The purpose of this study was to review safety and efficacy of total hip arthroplasty using large-diameter femoral heads in treatment and prevention of dislocation. One hundred forty hips in 135 patients were replaced using femoral heads at least 36 mm in diameter. The average age of the patients was 61.6 years. The patients were grouped into three categories depending on their diagnoses: recurrent dislocations from previous total hip replacements (Group 1; 29 hips); revision surgeries not including revisions for dislocations (Group 2; 54 hips); and primary surgeries (Group 3; 57 hips). The average followup was 5.5 years (range, 1-17 years). A total of 16 hips were revised: six for instability, four for fracture or disassociation of a conventional polyethylene liner, three for aseptic loosening of the socket, and three for sepsis. One hip from Group 1 dislocated at 12.5 years postoperatively, was treated with closed reduction, and since has been nonrecurring. UCLA hip scores all improved significantly. The prevalence of dislocation varied among the three groups, with 13.7% for Group 1, 1.8% for Group 2, and 3.5% for Group 3. The failure in the six cases that required revision for instability was attributable to poor socket orientation. All the hips became stable after revision without the use of a constrained acetabular liner. Large-diameter femoral heads provide additional stability not only for patients with recurrent dislocations, but also for patients having revision. The new, more wear-resistant bearings now enable the surgeon to extend the use of big femoral heads to primary total hip arthroplasty. Metal-on-metal seems to be the material of choice for a bone-conserving reconstruction with large femoral heads.