Comparison of preoperative radiographs and intraoperative findings of fixation of hemispheric porous-coated sockets

Cementless total hip arthroplasty with alumina bearings in patients younger than fifty with femoral head osteonecrosis

BACKGROUND

There are conflicting reports with respect to the outcomes of total hip arthroplasties with ceramic bearings in young patients with osteonecrosis of the femoral head. We prospectively investigated the outcomes after cementless total hip arthroplasties with contemporary alumina bearings in patients with osteonecrosis of the femoral head in this age group.

METHODS

We prospectively followed sixty patients (seventy-one hips) with a mean age of 39.1 years for an average of 7.1 years. All procedures were performed at the same institution by one surgeon, and the results were evaluated serially. The clinical evaluations included use of the Harris hip score, and activities of daily living were evaluated with use of the criteria of Johnston et al.

RESULTS

The mean Harris hip score was 97.0 points at the time of final follow-up. Thirteen patients (fourteen hips, 20%) reported noise in the hip. Loosening or osteolysis was not observed in any hip, and no prosthesis had been revised. No hip had dislocated, and no ceramic fracture had occurred.

CONCLUSIONS

After a minimum of six years of follow-up, this cementless total hip arthroplasty with contemporary alumina bearings was found to be a promising procedure for young, active patients with osteonecrosis of the femoral head. However, we remain concerned about the long-term implications of the noise that was reported in these hips.

Metal-on-metal hip arthroplasty does equally well in osteonecrosis and osteoarthritis

Many previous reports suggest total hip arthroplasty performs suboptimally in young patients with osteonecrosis. We retrospectively compared the performance of metal-on-metal articulation in a select group of 107 patients with 112 hips (98 uncemented and 14 cemented stems) 60 years of age or younger with either osteonecrosis (27 patients, 30 hips) or primary osteoarthritis (80 patients, 82 hips). We evaluated all patients with patient-generated Harris hip score forms and serial radiographs. Five mechanical complications were caused by impingement, two with pain, two dislocations, and one liner dissociation. At a minimum followup of 2.2 years (mean, 5.5 years; range, 2.2-11.7 years), we observed no osteolysis or aseptic loosening in the osteonecrosis group, whereas one osteoarthritic hip had cup revision for loosening (none showed evidence of osteolysis). None of the stems were loose. Patients with osteonecrosis or primary osteoarthritis were similar in clinical and radiographic performance. The patients with metal-on-metal hip arthroplasty for osteonecrosis had no revisions for aseptic loosening, but did have one liner change in a cup for painful impingement.

Coralline hydroxyapatite in complex acetabular reconstruction

This retrospective study examined whether a coralline hydroxyapatite bone graft substitute adequately repaired bone defects during complex acetabular reconstructions. Seventeen patients who underwent acetabular revision using Pro Osteon 500 were assessed to determine whether any cups required re-revision, whether bone had incorporated into the coralline hydroxyapatite grafts, and whether the coralline hydroxyapatite grafts resorbed with time. At latest follow-up, no cups required re-revision, but 1 had failed. Radiographic evidence of bone incorporation was observed in every coralline hydroxyapatite graft. Graft resorption was not observed.

The use of plain radiography, subtraction arthrography, nuclear arthrography, and bone scintigraphy in the diagnosis of a loose acetabular component of a total hip prosthesis: a systematic review

This meta-analysis was performed to summarize and compare the diagnostic performance and diagnostic accuracy of radiographic and scintigraphic techniques in the evaluation of patients suspected of having aseptically loose acetabular components. Twenty-eight studies, published between January 1975 and October 2004, presented sufficient data for quantitative analysis. The pooled sensitivity and specificity rates for plain radiography were 70% (95% confidence interval [CI] = 59%-79%) and 80% (95% CI = 73%-86%), respectively; those for subtraction arthrography were 89% (95% CI = 84%-93%) and 76% (95% CI = 68%-82%), respectively; and those for nuclear arthrography were 87% (95% CI = 57%-97%) and 64% (95% CI = 40%-82%), respectively. Finally, bone scintigraphy had a sensitivity of 67% (95% CI = 57%-76%) and a specificity of 75% (95% CI = 64%-83%). We found a significantly higher sensitivity for subtraction arthrography as compared with plain radiography and bone scintigraphy. Therefore, subtraction arthrography is recommended for use as an additional diagnostic technique when plain radiography is found to be inconclusive.

Imaging of joint replacement procedures

Joint replacement procedures have improved dramatically during the past 30 years fueled by the changes in techniques for hips and knees. Joint replacements in other anatomic regions also have become more popular. It is essential to understand the importance of pre- and postoperative imaging for evaluating patients. Preoperative images are used in concert with clinical data to select the appropriate patients and components. Postoperative imaging is critical for evaluating position and potential complications. Appropriate selection of imaging modalities is essential to provide optimal, cost-effective patient care.

Radiographic signs of osseointegration in porous-coated acetabular components

There currently is no direct method to radiographically determine osseointegration of an uncemented, porous-coated acetabular component. We defined five radiographic signs for detecting acetabular osseointegration: (1) absence of radiolucent lines; (2) presence of a superolateral buttress; (3) medial stress-shielding; (4) radial trabeculae; and (5) an inferomedial buttress. We assessed their ability to predict acetabular osseointegration by reviewing the postprimary and prerevision radiographs from a series of 119 total hip arthroplasties that had revision surgery. Each sign had a high positive predictive value for the presence of bone ingrowth (range, 92.2-96.3%). The absence of radiolucent lines, presence of superolateral buttresses, and presence of medial stress-shielding were the most sensitive signs for indicating bone ingrowth. Ninety-seven percent of the cups with three to five signs were bone ingrown, whereas 83% of the cups with one or no signs were unstable. When three or more signs were present, the positive predictive value of the radio-graphic test was 96.9%, the sensitivity was 89.6%, and the specificity was 76.9%. The five signs of acetabular osseointegration reliably predicted osseointegration, especially when used in combination. They can be used as a tool for radio-graphically assessing the status of patients with porous-coated uncemented cups.

LEVEL OF EVIDENCE

Diagnostic study, Level III (Study of nonconsecutive patients; without consistently applied reference "gold" standard). See the Guidelines for Authors for a complete description of levels of evidence.

Press fit fixation of cementless cups: how much stability do we need indeed?

INTRODUCTION

Using screws for a better primary and secondary fixation has been discussed in the literature of the recent years, although the principle of press fit has been explained as the principle of a push-button. The authors wanted to compare their own results in patients using X-rays from the postoperative course to decide if it is really safer to use screws or not.

MATERIALS AND METHODS

Two hundred and twenty one consecutive, not selected patients were treated with total hip arthroplasty using a cementless cup type Duraloc. They were followed up over a time of 5 years for radiological changes of the bony acetabulum around the cup ("acetabular zones" according to De Lee and Charnley). One hundred and ten cups were additionally fixed with one to three screws at the upper part in region C1, 101 cups were implanted without the use of screws.

RESULTS

Periprosthetic changes visible on the radiographs (immediate postoperative gaps, subsequent sclerosis and radiolucent lines) were assessed according to the time of their appearance. A gap in zone C2 was seen more often immediately after operation within the group without screws (17.8% vs. 7.3%) and disappeared within the following 25 months. Within the group with screws significantly more often a gap was found in zone C1 and C3 compared to the group without screws (7.3% vs. 1.9%). In the group with screws a sclerosis of the bone in zone C1 developed in 32.7% mostly within the first 5 months. It was followed by a radiolucent line in zone C3 in 28.2% mainly within 5-25 months postoperatively and in zone C1 in 20.9% within 16 months. Significantly less seldom were these phenomena seen at the cups without screw fixation. There was no correlation between lateral or medial positioning and deviations from the ideal inclination to the bony changes around the cups. No signs of loosening occurred in either group.

CONCLUSION

Less radiological changes around the cup if no screws were used and no disadvantages within this group led to the conclusion that an additional screw fixation in principle is not necessary in press-fit cups.

Radiographic evaluation of a monoblock acetabular component: a multicenter study with 2- to 5-year results

Serial radiographs of a porous tantalum monoblock acetabular cup design were evaluated for cup stability and signs of successful osteointegration. Of 574 primary consecutive total hip replacements in 542 patients performed by 9 surgeons at 7 hospitals, 414 cases were available for minimum 2-year follow-up. Follow-up averaged 33 months and ranged from 24 to 58 months. Postoperative radiographs revealed acetabular gaps in 100 zones in 80 (19%) hips: 29 in zone I, 67 in zone II, and 4 in zone III. At last follow-up, 84 (84%) of the zones with gaps completely filled in, and all 4- and 5-mm gaps filled in. There was no progression of any postoperative gap, no evidence of continuous periacetabular interface radiolucencies, no evidence of lysis, and no revisions for loosening. Although these short-term results are encouraging, further follow-up will be required to assess whether the monoblock design and the low modulus of elasticity of porous tantalum will reduce the incidence of periacetabular stress shielding and occurrence of osteolysis.

Outcome of acetabular revision using an uncemented hydroxyapatite-coated component: two- to five-year results and review

This is a retrospective review of 50 uncemented acetabular revisions with porous, hydroxyapatite-coated cups. The acetabulum alone was revised in 22 hips and both components were revised in 28 hips. The majority of hips (26) had type 2A (Paprosky) acetabular bone loss. All the revisions were carried out through a posterior approach. The mean duration of follow-up was 32 months (range, 24-52 months). Clinically, there was significant improvement in pain and moderate improvement in movement and mobility, and there is no radiological sign of failure of any cup so far. Re-revision was performed in 3 hips (6%) for recurrent dislocation. Our early results favor the use of this type of cup in acetabular revisions with moderate bone loss, but longer-term follow-up will be required. Key words: acetabulum, hydroxyapatite, revision, bone deficiency, complications.

An American experience with metal-on-metal total hip arthroplasties: a 7-year follow-up study

This study reviews the clinical performance of 161 hip arthroplasties (154 patients) with the Metasul metal-on-metal articulation and an uncemented modular acetabular component. Between 1995 and 2002 clinical evaluation and radiographic follow-up of patients included Harris hip scores, patient self-assessment, and radiographs. Twelve operative site complications (7.5%) included 6 revision operations, (3.7%) and 3 other complications (1.9%) not needing reoperation. Six revision operations (3.7%) included 1 femoral revision for aseptic loosening (0.06%) and 5 acetabular revisions (3.1%). One cup revision was for recurrent dislocation, 1 for disassociation of the acetabular insert from the cup, 1 for infection, and 2 for unexplained pain. Histologic evidence did not support the diagnosis of metal hypersensitivity in either case of unexplained pain, and 1 had relief following spine surgery. A focal radiolucency, identified as calcar resorption, was observed in 9 patients.

The argument for the use of Metasul as an articulation surface in total hip replacement

Metasul metal-on-metal articulations have been used for 15 years in approximately 300,000 total hip replacements. We have used Metasul articulations in three clinical studies and have shown clinical success as measured by Harris hip scores and patient self-assessment; we also have had the usual mechanical complications. The only complications have been mechanical, including two cup loosenings and 24 dislocations in a total of 582 patients (619 hips; 3.8%) who had Metasul articulations and were included in these studies. In the randomized study, the group who had Metasul articulations had no clinical results or complications different from the control ceramic-on-polyethylene group. Authors of retrieval results in the literature report low annual linear wear rates and no consequences of elevated Co ion levels. Currently, the scientific evidence of the results of using the Metasul articulation would recommend its continued use in any patient who does not have compromised renal function.

Fixation and osteolysis with Metasul metal-on-metal articulation

The purpose of this study was to report the prevalence of osteolysis and loss of fixation using Metasul metal-on-metal articulation couples. Ninety-two patients with 96 hips with Metasul articulation couples were followed for 5 to 11 years. By patient self-assessment, 89 (93%) patients scored themselves as good or excellent. The occurrence of osteolysis and the grading of fixation were obtained from plain radiographs. The clinical evaluation for these patients was performed by patient self-assessment. With the use of plain radiographs, there was no osteolysis observed in these 96 hips other than calcar resorption (6 hips [6.3%]). All components were fixed, except for 1 loose cup that was revised, and this level of fixation allowed a fair evaluation for osteolysis around well-functioning implants.

A comparison of radiographic and scintigraphic techniques to assess aseptic loosening of the acetabular component in a total hip replacement

BACKGROUND

The diagnosis of a loose total hip prosthesis is often established with use of radiographic and nuclear medicine techniques, but there is controversy about the relative utility of plain radiography, subtraction arthrography, nuclear arthrography, and bone scintigraphy. In this retrospective study, we evaluated the sensitivity, specificity, and interobserver reliability of these imaging modalities in patients suspected of having aseptic loosening of the acetabular component.

METHODS

From 1994 to 1999, eighty-six consecutive patients with pain after a total hip arthroplasty were evaluated for possible loosening of the components. The imaging evaluation included plain radiography followed by a one-day protocol that included bone scintigraphy, subtraction arthrography, and nuclear arthrography. For this study, two experienced nuclear medicine physicians and two experienced radiologists, all of whom were blinded with respect to the clinical pretest data and the clinical outcome, retrospectively interpreted the diagnostic images. The sensitivity and the specificity of each imaging modality were established by comparing the findings obtained with each technique with those found at surgery or during the subsequent clinical course of the patient. Interobserver variability was determined with the intraclass correlation coefficient.

RESULTS

Plain radiography had a sensitivity of 85% (95% confidence interval, 71 to 94) and a specificity of 85% (95% confidence interval, 66 to 96) in detecting aseptic loosening of the acetabular component, but it had only fair interobserver variability (intraclass correlation coefficient, 0.37). For subtraction arthrography, the sensitivity was 72% (95% confidence interval, 57 to 84), the specificity was 70% (95% confidence interval, 50 to 86), and there was good interobserver variability (intraclass correlation coefficient, 0.71). For nuclear arthrography, the sensitivity was 57% (95% confidence interval, 41 to 71), the specificity was 67% (95% confidence interval, 46 to 84), and there was fair interobserver variability (intraclass correlation coefficient, 0.24). For bone scintigraphy, the sensitivity was 83% (95% confidence interval, 69 to 92), the specificity was 67% (95% confidence interval, 46 to 84), and there was moderate interobserver variability (intraclass correlation coefficient, 0.43).

CONCLUSIONS

Plain radiography had the highest diagnostic accuracy in the evaluation of aseptic loosening of the acetabular component. The diagnostic accuracy was increased when plain radiography was combined with bone scintigraphy or subtraction arthrography. However, we found considerable interobserver variability in image interpretation, even with experienced radiologists and nuclear medicine physicians.

Cementing a liner into a stable cementless acetabular shell: the double-socket technique

BACKGROUND

During revision hip replacement surgery, the cementless acetabular shell is often well fixed but the locking mechanism may be ineffective. Cementing a new liner into the existing acetabular shell (the double-socket technique) can provide a simple solution. The purposes of the present study were to review our initial clinical results and to define the potential limitations of this technique.

METHODS

Thirty-two hips with a preexisting well-fixed acetabular socket that had been in situ for an average of 8.6 years were treated with the insertion of a new polyethylene liner (seventeen hips) or a metal liner (fifteen hips) with use of cement. The indication for this technique was a deficient locking mechanism in twenty-two hips and the unavailability of a matching liner in ten hips. Anteroposterior radiographs of all hips were analyzed by a single independent reviewer.

RESULTS

The mean duration of follow-up was 5.1 years. Six hips required a reoperation after a mean of 29.7 months; the reasons for the reoperations included aseptic failure of the acetabular construct (four hips), instability (one hip), and sepsis (one hip). The University of California at Los Angeles hip scores improved significantly (p < 0.001) compared with the preoperative values; specifically, the mean score improved from 6.2 to 9.1 for pain, from 6.3 to 8.3 for walking, from 6.2 to 7.8 for function, and from 4.7 to 5.8 for activity. The prevalence of dislocation was 22%. Kaplan-Meier analysis with revision as the end point revealed a five-year survival rate of 78% (95% confidence interval, 55% to 91%).

CONCLUSIONS

The double-socket technique is a good alternative to acetabular socket removal for suitable candidates who have a well-fixed cementless socket with an inner diameter that is larger than the outer diameter of the cemented liner. This technique preserves acetabular bone stock and permits conversion to alternate bearing surfaces. We believe, however, that removal of a well-fixed acetabular shell or the use of a constrained liner should be strongly considered for patients with a history of hip instability.

The painful total hip replacement

Total hip replacement is one of the most common and successful orthopaedic procedures. However, evaluation and treatment of the painful total hip replacement is one of the most difficult challenges for the arthroplasty surgeon. The differential diagnosis includes causes that are intrinsic and extrinsic to the hip. A thorough history and physical examination provide the basis for a focused, efficient workup of the painful total hip replacement. The temporal onset, duration, severity, site, and character of the pain all provide important clues in determining the cause of the painful total hip replacement. The physical examination should focus on tests and maneuvers that reproduce the patient's symptoms. Laboratory tests and radiographic evaluation are used selectively as indicated by the history and physical examination findings. With a careful and thorough evaluation, the cause of the painful total hip replacement can be determined in most patients, and the appropriate treatment can be initiated.

Fate of cementless acetabular components retained during revision total hip arthroplasty

BACKGROUND

Removal of a well-fixed cementless acetabular component can result in increased operative time and postoperative morbidity. The objectives of this retrospective study were to determine whether retention of a well-fixed acetabular component at the time of isolated femoral revision was compatible with long-term socket survival.

METHODS

The records of eighty-three consecutive patients (ninety hips) in whom a well-fixed cementless socket had been retained during revision of a femoral component were reviewed. The mean age of the patients was 48.7 years at the time of the primary arthroplasty and 54.1 years at the time of femoral revision. The radiographic analysis was based on anteroposterior radiographs and was performed by a single independent reviewer. The intraoperative criterion for stability of the socket was the absence of movement at the bone-implant interface during the application of direct pressure to the edges of the socket in four quadrants with use of a metallic pusher.

RESULTS

At the time of the isolated femoral revision, no socket demonstrated a radiolucent line measuring >1 mm in any two zones and forty of the ninety hips had periacetabular osteolysis. The mean size of the osteolytic lesions was 5.71 cm(2) (range, 0.4 to 24.2 cm(2)), and twenty-eight of the forty hips underwent bone-grafting. The mean duration of follow-up was 9.7 years after the isolated femoral revision and 14.9 years after the primary arthroplasty. Five acetabular sockets were revised at a mean of 6.8 years after the femoral revision. Only one of these sockets had failed because of aseptic loosening. With revision of the acetabular component for any reason as the end point, the survival rate was 98.7% at five years and 93.5% at ten years after the femoral revision and 100% at ten years and 93.9% at fifteen years after the primary arthroplasty. No hip showed recurrence or expansion of periacetabular osteolysis. The prevalence of dislocation was 16% (fourteen of ninety).

CONCLUSIONS

Revision of a stable, cementless acetabular component solely on the basis of its duration in vivo or the presence of periacetabular osteolysis does not appear to be warranted. Retention of the socket with grafting of larger periacetabular osteolytic lesions appears to be consistent with satisfactory socket longevity.