Extra-large uncemented hemispherical acetabular components for revision total hip arthroplasty

Oblong Cup in the Management of Aseptic Loosening of the Acetabular Component in Total Hip Replacement

Background and Aims:

At present, revision surgery of a total hip replacement is a major problem that must be dealt with by all orthopedic facilities. Aseptic loosening of the acetabular component is often associated with destruction of the original spherical shape of the acetabulum and the formation of bone defects. An orthopedist faces the challenge of acetabular revision and stable fixation of the new acetabular component in an effort to re-establish the functioning of the hip replacement.

Material and Methods:

The authors evaluated a group of 74 patients in whom they implanted an oblong revision cup due to aseptic loosening of the acetabular component from August 2000 until December 2003. The mean duration of the follow-up period was 63 months (ranging from 38 to 78 months).

Results and Conclusions:

The authors reported very good results from the use of this implant, where osteointegration and good functional outcome evaluated according to the Harris Hip Score (HHS) were achieved in 95% of cases. The long-term outcome should be the subject of further investigation.

Use of Structural Bone Graft for Reconstruction of Acetabular Defects in Primary Total Hip Arthroplasty: A 13-year Experience

Background/Purpose

The purpose of this study was to evaluate the clinical and radiographic outcomes of primary cementless total hip arthroplasty (THA) with acetabular defect reconstruction using structural bone grafts.

Methods

Between 2001 and 2012, 10 hips in eight patients with uncontained superolateral acetabular bone defects were reconstructed with femoral head grafts at the time of primary cementless THA. The mean age at surgery was 61.7 years. Patients were followed-up for a mean of 5.8 years for evaluation.

Results

With either revision or loosening as endpoints, the survival rate of the structural grafts was 100%. Significant improvements in clinical outcomes in terms of the Visual Analogue Scale for Pain (from 9.5 to 3.3, p = 0.005) and Harris Hip Score (from 32.7 to 73.9, p = 0.005) were noted.

Conclusion

Uncontained superolateral acetabular bone defects can be effectively reconstructed with structural bone grafts during primary THA, with excellent short- to midterm survival rate and significantly improved clinical outcomes.

Porous tantalum uncemented acetabular components in revision total hip arthroplasty

Aims

Reconstruction of the acetabulum after failed total hip arthroplasty (THA) can be a surgical challenge in the presence of severe bone loss. We report the long-term survival of a porous tantalum revision acetabular component, its radiological appearance and quality of life outcomes.

Patients and Methods

We reviewed the results of 46 patients who had undergone revision of a failed acetabular component with a Paprosky II or III bone defect and reconstruction with a hemispherical, tantalum acetabular component, supplementary screws and a cemented polyethylene liner.

Results

After a minimum follow-up of ten years (ten to 12), the survivorship of the porous tantalum acetabular component was 96%, with further revision of the acetabular component as the end point. The ten-year survivorship, with hip revision for any reason as the end point, was 92%. We noted excellent pain relief (mean Western Ontario and McMaster Universities Arthritis Index (WOMAC) score pain 92.6, (40 to 100)) and good functional outcomes (mean WOMAC function 90.3 (30.9 to 100), mean University of California Los Angeles activity scale 5 (2 to 10)) and generic quality of life measures (mean Short Form-12 (SF-12) physical component 48.3 (18.1 to 56.8), mean SF-12 mental component 56.7 (32.9 to 70.3)). Patient satisfaction with pain relief, function and return to recreational activities were excellent. Take home message: Uncemented acetabular reconstruction using a tantalum acetabular component gives excellent clinical and quality of life outcomes at a minimum follow-up of ten years. Cite this article: Bone Joint J 2016;98-B:767–71.

The custom triflange cup: build it and they will come

The custom triflange is a patient-specific implant for the treatment of severe bone loss in revision total hip arthroplasty (THA). Through a process of three-dimensional modelling and prototyping, a hydroxyapatite-coated component is created for acetabular reconstruction. There are seven level IV studies describing the clinical results of triflange components. The most common complications include dislocation and infection, although the rates of implant removal are low. Clinical results are promising given the challenging problem. We describe the design, manufacture and implantation process and review the clinical results, contrasting them to other methods of acetabular reconstruction in revision THA.

Outcomes of Custom Flange Acetabular Components in Revision Total Hip Arthroplasty and Predictors of Failure

BACKGROUND

Custom triflange acetabular components (CTAC) have become more popular in the treatment of Paprosky type IIIB defects with an average survivorship of 80% at 4 years. Many studies report survivorship of CTAC, but radiographic parameters of CTAC success or failure have not been previously reported. The purpose of the study was to assess radiographic and patient factors predictive of failure in CTAC.

METHODS

A retrospective review of 63 patients with >24 months of follow-up was completed. Continuous and categorical variables were compared between failed vs successful CTAC using Wilcoxon rank-sum test and Fisher exact test, respectively.

RESULTS

The failure rate of the CTAC was 13.5% over an average follow-up of 4.32 years (±2.94). Patients had a mean of 2 revisions (range, 0-11) before CTAC implantation. Compared with the contralateral hip center of rotation, the failed CTAC group tended to lateralize the hip center by a mean of 18.29 mm (±11.90 mm) compared to a mean of 9.86 mm (±11.89) in the intact group, although this did not reach statistical significance (P = .1029). The Western Ontario and McMaster Universities Osteoarthritis Index function score improved from 38.94 (±14.23) to 71.35 (±21.96) at most recent follow-up (P = .0002). The Western Ontario and MacMaster Universities Osteoarthritis Index scores were not significantly different between intact and failed CTAC groups.

CONCLUSIONS

CTAC tends to lateralize the hip center by approximately 1 cm, and there is a trend toward nearly 2 cm of lateralization in the small subset of failed CTAC. Future efforts should focus on medializing the hip center in CTAC to improve ingrowth and survivorship.

Are Range of Motion Measurements Needed When Calculating the Harris Hip Score?

BACKGROUND

Often the patient-reported outcome (PRO) component of the Harris Hip Score (HHS) is completed, but the physician-assessed range of motion (ROM) component is not. The PRO component only is called a modified Harris Hip Score (mHHS). The purpose of this study was to determine if a statistically significant or clinically meaningful difference existed when calculating the HHS with and without the physician-reported ROM portion.

METHODS

Included patients had complete HHS data (both physician and PRO components). Surgical procedure (primary or revision) was recorded for each subject. American Society of Anesthesiologists score was divided into low and high groups. Body mass index was divided into 4 categories. The study used a repeated measures design.

RESULTS

Data on 483 patients were collected between 12 and 60 months postoperatively (mean follow-up: 32.5 months, mean age: 55.9 ± 13.5 years). A mean difference of 4 points existed between the 2 groups: HHS group average score was 84.56 ± 13.18, and mHHS group average score was 88.74 ± 13.77. American Society of Anesthesiologists score, body mass index, and surgical type demonstrated a significant interaction with the HHS calculation method (P < .001). Primary total joint patients demonstrated a greater difference between the 2 scoring methods compared with revision patients.

CONCLUSION

No clinically meaningful difference in outcomes was found between the mHHS and the HHS. The calculation of the HHS is dependent on the inclusion of the ROM measurement. However, the small point difference between the HHS and mHHS indicates that the mHHS is still useful as an accurate determinant of patient clinical outcome, and ROM assessment is not essential.

Comparison of Head Center Position and Screw Fixation Options Between a Jumbo Cup and an Offset Center of Rotation Cup in Revision Total Hip Arthroplasty: A Computer Simulation Study

Jumbo acetabular cups are commonly used in revision total hip arthroplasty (THA). A straightforward reaming technique is used which is similar to primary THA. However, jumbo cups may also be associated with hip center elevation, limited screw fixation options, and anterior soft tissue impingement. A partially truncated hemispherical shell was designed with an offset center of rotation, thick superior rim, and beveled anterior and superior rims as an alternative to a conventional jumbo cup. A three dimensional computer simulation was used to assess head center position and safe screw trajectories. Results of this in vitro study indicate that a modified hemispherical implant geometry can reduce head center elevation while permitting favorable screw fixation trajectories into the pelvis in comparison to a conventional jumbo cup.

The jumbo acetabular component for acetabular revision

The ‘jumbo’ acetabular component is now commonly used in acetabular revision surgery where there is extensive bone loss. It offers high surface contact, permits weight bearing over a large area of the pelvis, the need for bone grafting is reduced and it is usually possible to restore centre of rotation of the hip. Disadvantages of its use include a technique in which bone structure may not be restored, a risk of excessive posterior bone loss during reaming, an obligation to employ screw fixation, limited bone ingrowth with late failure and high hip centre, leading to increased risk of dislocation. Contraindications include unaddressed pelvic dissociation, inability to implant the component with a rim fit, and an inability to achieve screw fixation. Use in acetabulae with < 50% bone stock has also been questioned. Published results have been encouraging in the first decade, with late failures predominantly because of polyethylene wear and aseptic loosening. Dislocation is the most common complication of jumbo acetabular revisions, with an incidence of approximately 10%, and often mandates revision. Based on published results, a hemispherical component with an enhanced porous coating, highly cross-linked polyethylene, and a large femoral head appears to represent the optimum tribology for jumbo acetabular revisions.

Cite this article: Bone Joint J 2016;98-B(1 Suppl A):64–7.

THA revisions using impaction allografting with mesh is durable for medial but not lateral acetabular defects

BACKGROUND

Most acetabular revisions are managed with cementless hemispherical or elliptical metal implants relying on bone ingrowth. Nonetheless, loss of acetabular bone stock and inability to achieve secure component fixation represent challenges in the setting of revision total hip arthroplasty. Impaction bone grafting (IBG) using allograft represents one option for treatment of this problem. However, cup migration and bone graft resorption are limitations when IBG is used for large segmental defects, and the precise role of IBG as well as the use of mesh (and the kinds of defects for which mesh does not work well) in this setting remains unknown.

QUESTIONS/PURPOSES

We therefore evaluated patients undergoing acetabular revision surgery using IBG and a cemented cup in large bone defects to determine (1) the frequency with which the hip center could be restored in hips with Paprosky 3A and 3B defects and in hips with or without the use of metallic mesh during surgery; (2) survivorship of IBG acetabular-revision reconstructions in patients with severe Paprosky 3A and 3B defects; and (3) risk factors for failure of the reconstruction, including the use of mesh and defect severity (3A versus 3B).

METHODS

Between 1997 and 2009, we performed 226 acetabular revisions using IBG. During that time, indications for using IBG in this setting included Paprosky 3A and 3B defects without pelvic discontinuity. Of these, 204 (90.2%) were available for followup at a minimum of 5 years (mean, 10 years; range, 5-17 years). There were 100 hips with an intraoperative bone defect of Paprosky 3A and 104 with a 3B. Medial or rim acetabular uncontained defects were treated with medial and/or lateral metallic mesh in 142 hips. We determined the postoperative radiological cup position and acetabular reconstruction of the hip center according to Ranawat in both groups. We assessed the appearance of cup loosening and the possible risk factors with regression analysis.

RESULTS

Mean postoperative acetabular abduction angle and vertical, horizontal, and hip rotation center distances improved (p < 0.001 in all parameters). Nine hips showed radiological loosening in the group with bone defect 3A and 16 in Group 3B. The survival rate for loosening at 15 years was 83% (95% confidence interval [CI], 71%-95%) for Group 3A and 73% (95% CI, 60%-84%) for Group 3B (p = 0.04). The survivorship for loosening when using mesh or not at 15 years was: no mesh 89% (95% CI, 74%-99%), medial mesh 85% (95% CI, 72%-97%), lateral mesh 80% (95% CI, 67%-91%), and medial and lateral meshes 54% (95% CI, 31%-76%) (p = 0.008). After controlling the most relevant confounding variables we found that the most important factor associated with loosening was lateral mesh use (p = 0.008; hazard ratio, 2.942; 95% CI, 1.328-6.516).

CONCLUSIONS

IBG provides an improvement in reconstruction of the hip rotation center in acetabular revision surgery. Although results are good for contained or medial large defects, hips with a rim or lateral segmental defect may need other options for reconstruction of these challenging surgeries.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Use of the Burch-Schneider cage and structural allografts in complex acetabular deficiency: 3- to 10-year follow up

This study aimed to evaluate retrospectively the clinical outcomes and complications of structural allografts and Burch-Schneider antiprotrusio cages to treat severe acetabular defects in revision total hip arthroplasty (THA). Between July 2003 and December 2010, 29 patients (representing 31 hips) underwent revision THA using structural allografts and Burch-Schneider cages for acetabular reconstruction. The patients had a mean age of 59 years (range, 37-79 years). Seventeen hips had a Paprosky IIIA defect, 12 hips had a IIIB defect, and two hips had a pelvic discontinuity (PD) acetabular defect. After a mean follow up of 5.5 years (range, 3.0-10.5 years), all patients, except for two patients with recurrent infections, significantly improved, based on the mean Harris hip score (30 points vs. 67 points, p < 0.001) and the Western Ontario and McMaster Universities Arthritis index (WOMAC) score (65 points vs. 32 points, p < 0.001). Using re-revision surgery as the endpoint, the cage had a survival rate of 76% [95%, confidence interval (CI), 67.4-84.6%] at 5 years and 57% (95% CI, 39.3-74.7%) at 10 years. Other complications included hip dislocation [3 (9.7%) hips]; deep infection [3 (9.7%) hips]; and sciatic nerve impingement, vesicle-acetabular fistula, and leg lengthening [1 (3.2%) hip]. There was a trend toward a higher failure rate in hips with four revisions, compared to hips with three revisions or fewer (p = 0.055). Three hips with a failed cage underwent re-revision surgery using a standard noncemented acetabular component. In conclusion, a structural allograft with Burch-Schneider antiprotrusio cage for complex acetabular defect is a technique-demanding procedure with a 5-year survival rate of 76%. Even with failed cage reconstruction, re-revision surgery with a noncemented acetabular component may be feasible once the allograft has healed.

Radiographic Determination of Hip Rotation Center and Femoral Offset in Japanese Adults: A Preliminary Investigation toward the Preoperative Implications in Total Hip Arthroplasty

The values of hip rotation center (HRC) and femoral offset (FO) evaluated according to Caucasian anatomical landmarks have been regarded as a useful reference also for Japanese patients in total hip arthroplasty (THA). In a strict sense, however, since there can be racial differences among their anatomical morphologies, it is clinically important to reconsider those parameters for the Japanese. In the present study, in order to investigate correlations among hip and pelvic morphometric parameters, frontal radiographs were taken from 98 Japanese adults (60 males and 38 females) without acetabular dysplasia and arthropathy in the standing position. Their mean age was 62.0 ± 16.7 years. The horizontal position of HRC was significantly correlated with the pelvic width in both genders (P = 0.0026 and 0.0010 for the males and the females, resp.). The vertical position of HRC was significantly correlated with the teardrop-sacroiliac distance in the males (P = 0.0003) and with the pelvic cavity height in the females (P = 0.0067). However, in both genders, there were no correlations among FO and the other parameters analyzed in this study. Our present findings might contribute to theoretical implications of an appropriate HRC position for Japanese OA patients in THA.

Treatment algorithm of acetabular periprosthetic fractures

Periprosthetic fractures of the acetabulum represent a rare incident in primary and revision total hip arthroplasty. The management of these fractures can be challenging. At present, there are no reliable guidelines for the treatment of periprosthetic acetabular fractures. Periprosthetic acetabular fractures can occur intra-operatively, in particular during insertion of non-cemented cups or in the context of revision surgery. Post-operative causes for periprosthetic acetabular fractures are traumatic events or, more commonly, pelvic discontinuity due to severe bone loss related to osteolysis. Despite their aetiology, the main objective of surgery is to achieve a stable acetabular component and fracture. While stable fractures and implants could be treated non-operatively, unstable fractures require surgery to achieve component stability and allow appropriate biological fixation of the revision cup. Assessment of the stability plays a crucial role before determining the treatment strategy. There is a large variety of surgical techniques available for the management of these fractures. This review article outlines the epidemiology, aetiology and current classification systems, and provides a distinct diagnostic and therapeutic algorithm for the treatment of periprosthetic acetabular fractures.

Uncemented jumbo cups for revision total hip arthroplasty: a concise follow-up, at a mean of twenty years, of a previous report

Uncemented jumbo cups are commonly used for acetabular revision because they are technically straightforward to implant and provide good intermediate-term results. Understanding long-term survival is particularly important because this method is common and because jumbo cups do not provide notable bone stock restoration. The purpose of the present study was to determine the twenty-year results of jumbo cup use during revision total hip arthroplasty. In the original publication, we reported on eighty-nine patients who underwent revision with an uncemented jumbo cup with a single design (Harris-Galante) prior to 1993. The Harris Hip Score (HHS), radiographic results, and Kaplan-Meier survivorship curves were evaluated. Mean follow-up was twenty years. The mean postoperative HHS was 71 compared with 56 preoperatively (p=0.001). A total of five jumbo cups were revised for aseptic loosening; one, for infection; and one, for recurrent dislocation. Eight liners were revised with retention of the metal acetabular component: six during femoral component revision, one for wear, and one for recurrent dislocations. Twenty-year survivorship was 88% free from aseptic loosening of the metal acetabular component, 85% free from aseptic loosening or radiographic evidence of definite loosening of the metal acetabular component, and 83% free from revision of the metal acetabular component for any reason. The twenty-year results of revision with uncemented jumbo acetabular components demonstrated acceptable clinical outcomes and radiographic stability. These results justify the use of jumbo cups as a common method of acetabular revision.

Continued good results with modular trabecular metal augments for acetabular defects in hip arthroplasty at 7 to 11 years

BACKGROUND

Reconstruction of large acetabular defects remains a substantial challenge in hip arthroplasty. There remains a paucity of data on the long-term results of acetabular trabecular metal augments.

QUESTIONS/PURPOSES

The purpose of this study was to assess the survivorship, clinical outcomes, restoration of center of rotation of the hip, and radiological signs of component fixation of trabecular metal augments in the context of reconstruction of acetabular defects.

METHODS

Between 2002 and 2005, we performed 56 revision (n=53) and primary (n=3) THAs using trabecular metal augments in combination with a trabecular metal acetabular component. Of the 56 patients, 16 (29%) died during followup. Of the 40 surviving patients, 37 (93%) had complete radiological followup, 23 (58%) had complete outcome questionnaire followup, and 17 (42%) provided partial questionnaire responses in the clinic or over the telephone. Median followup was 110 months (range, 88-128 months). During that period, we used these implants when preoperative templating indicated that an augment would be required to achieve acetabular implant stability with restoration of the hip center of rotation. We also chose during surgery to use an augment when we could not achieve a stable acetabular trial component without one. The combination of trabecular metal augments and trabecular metal shells was used in 18% (53 of 292) of our acetabular revisions during that time. Survivorship, functional outcome (WOMAC and Oxford hip score), health status (SF-12), and osseointegration according to the criteria of Moore and presence of radiolucencies were determined.

RESULTS

Survivorship of the augments at 10 years was 92% (95% confidence interval, 81%-97%). Four patients underwent cup revision, one for infection and three for loosening. The mean WOMAC global score was 79 (SD 17), the mean Oxford hip score 76 (SD 18), the mean physical component SF-12 score was 39 (SD 11), and the mean mental component SF-12 score was 52 (SD 9). The center of rotation was corrected from more than 35 mm above the inter-teardrop line in 48 of 56 patients preoperatively to only five of 46 postoperatively. One patient had radiographic findings suggestive of loosening, but this patient was asymptomatic.

CONCLUSIONS

The results of the acetabular trabecular metal augments continue to be encouraging in the medium to long term with low rates of revision or loosening in this complex group of patients. We continue to recommend the use of these augments in the reconstruction of complex acetabular defects.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Revision of type III and type IVB acetabular defects with Burch-Schneider anti-Protrusio cages

Extensive bone loss in severe acetabular deficiencies can make repair with acetabular shells impossible. We retrospectively analyzed mid-term to long-term results of acetabular revision with Burch-Schneider reinforcement cages in 33 hips in patients with a mean age of 59.03years after a mean follow-up period of 6.19years. Under the American Academy of Orthopaedic Surgeons classification, 9 patients had type III acetabular bone defects and 24 had type IVB. Merle D'Aubigné scores improved by a mean of 9.3 points. The prosthesis failure rate was 15.1%, the series complication rate was 21.2%, and the mean survivorship was 11.57years. The Burch-Schneider cage is useful for reconstruction in massive acetabular deficiency, but complication rates are high and long-term mechanical failure is a concern.

Options for managing severe acetabular bone loss in revision hip arthroplasty. A systematic review

Revision hip arthroplasty in the presence of severe acetabular bone loss is challenging and requires a solid understanding of current techniques. A literature search of multiple databases applying specific criteria revealed a total of 50 articles of level IV scientific evidence comprising 2415 patients (2480 hips) managed with reinforcement devices (roof-reinforcement rings and anti-protrusio cages), custom-made triflanged acetabular components (CTACs), jumbo cups and tantalum metal (TM) systems. Overall, patients had improved postoperative hip scores for each technique. The use of reinforcement devices resulted in a mean revision rate of 8.2% and a mean complication rate of 29.21%. CTACs were associated with a revision rate of 15.9% and had a complication rate of 24.5%. Jumbo cups were revised in 8.8% of patients and had a complication rate of 18.4%. TM systems had an overall revision rate of 8.5% with complications seen in 18.5% of patients. CTACs had considerably higher revision rates compared to the other techniques. Jumbo cups and TM systems had lower complication rates compared to the use of reinforcement devices and CTACs. The most frequently occurring complications seen throughout the series were aseptic loosening, dislocation and infection.

Do jumbo cups cause hip center elevation in revision THA? A radiographic evaluation

BACKGROUND

Acetabular revision THA with use of a large (jumbo) cup is an effective treatment for many cavitary and segmental peripheral bone defects. However, hip center elevation may occur with use of a jumbo cup owing to reaming superiorly and/or because of the increased diameter of the jumbo cup compared with the native acetabulum.

QUESTIONS/PURPOSES

In our jumbo cup revision THAs, we attempted to avoid hip center elevation by placing the inferior edge of the cup at the inferior acetabulum. In this study, we asked (1) how much of an elevation in the hip center is observed radiographically with use of jumbo cups, and (2) how effective was our technique in minimizing hip center elevation during revision THA in clinical practice?

METHODS

We retrospectively reviewed radiographic data for all patients, from one surgeon's practice, who received a jumbo cup (defined as cup size ≥ 66 mm in men, ≥ 62 mm in women) during an acetabular revision between 1998 and 2012 and who had an anatomically placed THA or no THA on the contralateral side (so as to be able to make comparisons); 98 patients were identified and included. The height of the revised hip center was measured relative to the contralateral normal hip. Cup elevation resulting from superior reaming was determined by measuring the distance from the inferior cup edge to the interteardrop line. The mean hip center elevation and cup position relative to the interteardrop line in male and female patients were compared using unpaired t-tests.

RESULTS

Radiographic analysis showed a mean hip center elevation of 11 mm. On average, 1 mm of the measured hip center elevation was the result of cup placement superior to its planned position at the interteardop line.

CONCLUSIONS

Our results indicate that revision THA with a jumbo cup is associated with hip center elevation despite placement of the cup at the inferior acetabulum. An increase in femoral head length may be needed to compensate for hip center elevation with use of a jumbo cup.

LEVEL OF EVIDENCE

Level III, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence.

Evaluation of the fixation of the trabecular metal wedge in patients undergoing revision of total hip arthroplasty

OBJECTIVE

this study aimed to evaluate the fixation of the trabecular metal wedge in patients undergoing revision of total hip arthroplasty.

METHODS

twenty-three cases with minimum grading of Paprosky II-B that were operated between July 2008 and February 2013 were evaluated. These cases were evaluated based on radiographs before the operation, immediately after the operation and later on after the operation. Loss of fixation was defined as a change in the abduction angle of the component greater than 10° or any mobilization greater than 6 mm.

RESULTS

it was found that there was 100% fixation of the acetabula after a mean of 29.5 months. One case underwent removal of the implanted components due to infection.

CONCLUSIONS

there is still no consensus regarding the best option for reconstructing hips with bone loss. However, revision using a trabecular metal wedge has presented excellent short- and medium-term results. This qualifies it as an important tool for achieving a fixed and stable acetabular component.

Outcome of porous tantalum acetabular components for Paprosky type 3 and 4 acetabular defects

Porous tantalum acetabular implants provide a potential solution for dealing with significant acetabular bone loss. This study reviews 24 acetabular revisions using tantalum implants for Paprosky type 3 and 4 defects. The mean Harris Hip Score improved from 35 ± 19 (range, 4-71) to 88 ± 14 (range, 41-100), p < 0.0001. Postoperative radiographs showed radiolucent lines in 14 hips with a mean width of 1.3 ± 1.0 mm (range, 0.27-4.37 mm). No gaps enlarged and 71% of them disappeared at a mean of 13 ± 10 months (range, 3-29 months). At a mean follow-up of 37 ± 14 months (range, 24-66 months), 22 reconstructions showed radiograpic evidence of osseointegration (92%). The two failures were secondary to septic loosening. When dealing with severe acetabular bone loss, porous tantalum acetabular components show promising short-term results.

Acetabular reconstruction using a Kerboull cross-plate, structural allograft and cemented dual-mobility cup in revision THA at a minimum 5-year follow-up

The current study aimed to evaluate the outcome of a continuous and prospective series of 61 revision THAs with AAOS grade III and IV acetabular bone defect reconstruction using a Kerboull cross-plate, structural allograft and cemented dual mobility cup (Saturne, Amplitude, Valence, France). At a 7.5-year mean follow-up, no instability was reported after revision. In addition, no failure of the acetabular reconstruction was observed in 98% of the patients with complete allograft osseointegration and no evidence of mechanical rupture of the Kerboull cross-plate and/or loosening of the cemented dual mobility cup. In conclusion, such reconstruction technique demonstrated excellent results at mid-term follow-up in terms of prevention of instability after revision, restoration of the acetabular bone stock, and stable cemented fixation of the dual mobility cup.

Do jumbo cups cause hip center elevation in revision THA? A computer simulation

BACKGROUND

Acetabular revision THA with use of a large (jumbo) cup is an effective treatment for many cavitary and segmental peripheral bone defects. However, the jumbo cup may result in elevation of the hip center and protrusion through the anterior acetabular wall as a result of the oversized geometry of the jumbo cup compared with the physiologic acetabulum.

QUESTIONS/PURPOSES

The purpose of this computer simulation was to determine how much elevation of the hip center and anterior wall protrusion occurs in revision THA with use of a jumbo cup technique in which the inferior edge of the jumbo cup is placed at the inferior acetabular rim and the superior edge of the jumbo cup is placed against host bone at the superior margin of a posterosuperior bone defect.

METHODS

Two hundred sixty-five pelvic CT scans were analyzed by custom CT analytical software. The computer simulated oversized reaming. The vertical and anterior reamer center shifts were measured, and anterior column bone removal was determined.

RESULTS

The computer simulation demonstrated that the hip center shifted 0.27 mm superiorly and 0.02 mm anteriorly, and anterior column bone removal increased 0.86 mm for every 1-mm increase in reamer diameter.

CONCLUSIONS

Our results indicate that the jumbo cup technique results in hip center elevation despite placement of the cup adjacent to the inferior acetabulum. For a hypothetical increase from a 54-mm socket to a 72-mm socket, as one might see in the context of the revision of a failed THA, our model would predict an elevation of the hip center of approximately 5 mm and loss of approximately 15 mm of anterior column bone. This suggests that an increase in femoral head length may be needed to compensate for the hip center elevation caused by the use of a large jumbo cup in revision THA. A jumbo cup may also result in protrusion through the anterior wall.

Use of jumbo cups for revision of acetabulae with large bony defects

Several methods of treatment are available for acetabular revision associated with bone loss. Jumbo cups (minimum diameter of 62 mm in women, 66 mm in men, or 10 mm larger than the normal contralateral acetabulum) are often useful for large defects. The purpose of this study is to report a large jumbo cup series with an average 10-year follow-up. A total of 196 jumbo cups in 186 patients with a minimum of 2-year follow-up were available for review. Harris hip score improved from 44 preoperatively to 72 postoperatively. Survivorship was 98% at 4 years and 96% at 16 years. Five revisions and two resection arthroplasties were performed for failure. In conclusion, porous jumbo cup acetabular revision with supplemental screw fixation provides good to excellent intermediate- and long-term outcomes.

Systematic review on outcomes of acetabular revisions with highly-porous metals

PURPOSE

The purpose of this study was to systematically review the literature and report the clinical and radiographic outcomes of highly-porous acetabular cups in revision settings.

METHOD

A literature search of four electronic databases of EMBASE, CINAHL-plus, PubMed, and SCOPUS yielded 25 studies reporting the outcomes of 2,083 revision procedures with highly-porous acetabular components. There was lack of high quality evidence (level I and level II studies) and only two studies with level III evidence, while the remainder were all level IV studies. In addition, a majority of the studies had small sample sizes and had short to mid-term follow-up. The mean age of the patients was 65 years (range, 58-72 years) and the mean follow-up was 3.6 years (range, two to six years). Outcomes evaluated were aseptic survivorship, Harris hip scores, migration rates, incidence of peri-acetabular radiolucencies and radiographic restoration of the hip centre.

RESULTS

The mean aseptic survivorship was 97.2% (range, 80-100%). The Harris hip scores improved from a mean pre-operative score of 42 points, (range, 29-75 points), to a mean postoperative score of 79 points (range, 69-94 points). The mean incidence of cup migration and prevalence of peri-acetabular radiolucencies was 2.4% (range, 0-8.8%) and 4.6% (range, 0-19%), respectively, at final follow-up. The vertical hip centre-of-rotation was restored significantly from a mean of 39.2 mm (range, 27.6-50 mm) pre-operatively, to a mean of 24.1 mm (range, 7.4-47 mm), postoperatively.

CONCLUSION

The short-term clinical and radiographic results of highly-porous metals in revision hip arthroplasty are excellent with a low rate of loosening in the presence of both major and minor bone loss.

Acetabular cup positioning in revision total hip arthroplasty with Paprosky type III acetabular defects: Martell radiographic analysis

PURPOSE

This study evaluates acetabular cup position in the setting of revision total hip arthroplasty (THA) with severe acetabular bone defects.

METHODS

With a definition of safe zone of abduction (30-50°) and anteversion (5-25°), acetabular cup position was measured by a digital image analysis program for 34 patients with Paprosky type III acetabular bone defects.

RESULTS

There were 24 cups (71%) for abduction and 26 cups (76%) for anteversion located in the safe zone. Nineteen cups (56%) were within the safe zone for both abduction and anteversion. There was no dislocation, however one cup out of the safe zone resulted in early cup failure due to aseptic loosening.

CONCLUSIONS

The acetabular cup positioning in patients with Paprosky type III defects was 'optimal' in half of the cases. The prevalence of optimal acetabular cup position was similar to those reported in primary THA, suggesting that the presence of a large acetabular bone defect may not be a significant risk factor for suboptimal acetabular cup positioning in the setting of revision THA.

Short-term results of a custom triflange acetabular component for massive acetabular bone loss in revision THA

Managing severe periacetabular bone loss during revision total hip arthroplasty (THA) is a challenging task. Multiple treatment options have been described. A custom triflanged acetabular component is a recent treatment option. The authors retrospectively reviewed 19 hips in 19 patients with massive periacetabular bone loss (Paprosky types 3A/3B and AAOS types III/IV) treated with custom triflanged acetabular components. Mean patient age at surgery was 58 years (range, 42-79 years).At an average follow-up of 31 months (range, 16-59 months), mean Harris Hip Score had improved from 38 preoperatively to 63 postoperatively, and mean Western Ontario McMaster Osteoarthritis Index scores had improved from 43 preoperatively to 26 postoperatively. Sixty-five percent of cases were considered successful. Three (16%) patients had significant complications; 2 (11%) custom triflanged acetabular components were removed due to failure. At last follow-up, 6 (43%) of 14 patients reported that their ambulatory status was improved vs their preoperative status, 3 (21%) reported no change, and 5 (36%) reported that their ambulatory status was worse than their preoperative status.In this study, the use of a custom triflanged acetabular component for massive periacetabular bone loss in revision THA had less favorable results than in other reports. Use of a custom triflanged acetabular component for massive periacetabular bone loss in revision THA remains a viable option, but surgeon and patient expectations should be realistic.

Implant choices, technique, and results in revision acetabular surgery: a review

Acetabular reconstruction in revision total hip arthroplasty can successfully be achieved with hemispherical components featuring a porous or roughened ingrowth surface and options for placement of multiple screws. Most defects can be reconstructed with large hemispherical or "jumbo" cups. Achieving component stability and sufficient contact area on adequate host bone is mandatory. Defects with greater bony loss or compromised columns require either the use of modular augments combined with a hemispherical shell, reconstruction cages, structural allografts, or custom triflange acetabular components. This paper will detail the necessary pre-operative evaluation, the intra-operative details, and the reported results of these acetabular revisions.

Reconstruction of the rotation center of the hip after oblong cups in revision total hip arthroplasty

BACKGROUND

The preoperative bone defect and the reconstruction of the center of rotation of the hip are critical in acetabular revision surgery. Uncemented oblong cups are employed in order to manage these issues. We analyzed the clinical results and rates of revision of two different uncemented oblong cups, the reconstruction of the center of rotation of the hip, as well as the rate of radiological loosening and possible risk factors.

MATERIALS AND METHODS

Forty-five patients (46 hips) underwent acetabular revision surgery using two different uncemented oblong cups. We assessed the clinical results and the survival rate for revision and aseptic loosening. Intraoperative bone loss was classified according to Paprosky, and acetabular reconstruction was assessed according to Ranawat. The mean follow-up was 7.2 years (range 4-11 years).

RESULTS

There were four re-revisions (three due to aseptic loosening); the survival rate for re-revision due to aseptic loosening was 60.1 % at seven years. The mean distance between the center of the femoral head prosthesis and the approximate center of the femoral head improved from 21.5 to 10.2 mm. Thirteen cups showed radiological loosening; the survival rate for radiological loosening at seven years was 40.54 %. A smaller postoperative horizontal distance was correlated with cup loosening.

CONCLUSIONS

Although optimal acetabular reconstruction can be achieved by using oblong uncemented cups in revision hip surgery, the clinical and radiological results are not encouraging. Excessive medialization of the cup may increase the rate of loosening.

Use of porous trabecular metal augments with impaction bone grafting in management of acetabular bone loss

BACKGROUND

The use of impaction grafting in revisions with larger acetabular bone defects has mixed outcomes and sometimes high failures rates.

PATIENTS AND METHODS

This prospective, single-center study involved a consecutive series of 24 patients who underwent complex reconstruction of the acetabulum using a trabecular metal augment, impaction bone grafting, and a cemented high-density polyethylene cup. Patients were followed for median 5 (3-7) years.

RESULTS

The 2-year WOMAC pain, function, and stiffness scores improved, as did certain components (bodily pain, physical function, role physical, role emotional, physical component score, and social function) of the SF-36 (p < 0.05). 23 of the patients were very satisfied with the overall outcome of the surgery and would have undergone the surgery again for a similar problem, and 19 reported great improvement in their quality of life after surgery. Radiographs at the latest follow-up revealed incorporation of the augment with mean change in acetabular component inclination of less than 1 degree (p > 0.05) and cup migration of less than 5 mm in both horizontal and vertical axes (p > 0.05). 1 patient required further revision at 13 months and was found to have a fractured augment at re-revision.

INTERPRETATION

This study shows that trabecular metal augments are effective in filling the bone defect and provide a stable foundation for impaction bone grafting. We found satisfactory clinical and radiographic results using this technique, with low failure rate at a median follow-up time of 5 years.

Revision total hip arthroplasty without bone graft of high-grade acetabular defects

Mixed results have been reported with bulk and cancellous bone graft to fill defects during acetabular revision arthroplasty. Jumbo cups have been used to maximize host bone contact, and if adequate initial stability can be achieved, this approach may provide a superior long-term outcome. We retrospectively reviewed a consecutive series of 107 acetabular revisions performed using jumbo cups without bone graft. Bone defects were assessed using a validated radiographic classification system that yielded 64 hips with significant bone defects for inclusion. Mean change in American Academy of Orthopaedic Surgeons lower extremity core and pain scores and in Short Form-12 scores showed increases of 22.01, 37.52, and 17.08 points, respectively. Postoperative radiographs consistently demonstrated host bone ingrowth into the jumbo acetabular shells, except for 3 failures. Careful incremental reaming up to a size that optimizes host bone support and contact may eliminate the need for bone graft in most acetabular revision arthroplasties.

Revision total hip arthroplasty using a reconstruction cage device and a cemented dual mobility cup

INTRODUCTION

The main causes of total hip arthroplasty (THA) revisions are loosening and instability. Dual mobility cups were introduced to prevent instability, but their behavior during revisions with acetabular reconstruction has not been assessed.

HYPOTHESES

Use of a dual mobility cup cemented in a acetabular reconstruction cage device limits the risk of instability and does not hinder the acetabular fixation during THA revisions.

OBJECTIVES

The objective of this study was to test this hypothesis on a retrospective series of 96 revisions.

PATIENTS AND METHODS

At a mean follow-up of 41 months (range, 1-101 months), we analyzed a continuous series of 96 revisions using a reconstruction device (70 Kerboull™ cross-plates, six Burch-Schneider™ antiprotrusio cages, 20 custom-fit Novae ARM™ cages associated in all cases with a Novae Stick dual mobility cup cemented into the cage). Fifteen patients died at a mean follow-up of 22 months (range, 1-66 months) and four patients were lost to follow-up at a mean follow-up of 16 months (range, 9-27 months). These were acetabular revisons involving major bone loss, with 62 stage III and 26 stage IV cases on the SOFCOT classification. Eighty-seven patients (87.5%) underwent structural bone allografting.

RESULTS

The mean Merle d'Aubigné score increased from 9.6 ± 3.06 (range, 2-16) preoperatively to 15.5 ± 2.32 (range, 7-18) at the follow-up. Ten dislocations (10.4%) occurred, five of which were delayed over three months after the index procedure (5.2%), but there were no intraprosthetic dislocations. At the follow-up, the X-rays showed eight hardware failures, including one cross-plate fracture, one hook fracture, and one flange fracture. Analysis of the radiological position of the cup showed a mean lowering of 15.6mm and a 9.4mm lateralization compared to the preoperative position. One revision for aseptic loosening and another for septic loosening were performed. Taking all-cause acetabular component exchange as a criterion, the survival rate at 8 years was 95.6% (95% CI, 93.3-97.7%) and 99.3% (95% CI, 98.9-99.6%) if the endpoint was aseptic acetabular exchange.

DISCUSSION

This study confirms the advantage of dual mobility cups during acetabular reconstruction cemented in antiprotrusio cages as a way to limit, without eliminating, the risk of dislocation. Therefore cemented fixation of dual mobility cups in cages appears to be a reliable short-term option.

Trabecular metal used for major bone loss in acetabular hip revision

The purpose of this study was to evaluate the outcome of trabecular metal (TM) acetabular components used in revision hip arthroplasty with major bone deficiency. We retrospectively reviewed the records of 46 patients undergoing revision hip arthroplasty with severe acetabular bone loss. Clinical outcomes were assessed using Harris Hip Score, Western Ontario and McMaster Universities, and Short-Form 12. Mean follow-up was 50 months. All patients had Paprosky type IIc or III acetabular bone deficiency. Major complications included 1 infection, 2 dislocations, and 1 arterial bleeding. Average Harris Hip Score was 78.2. Short-Form 12 scores were within population-based age-matched averages. Western Ontario and McMaster Universities scores were mainly in the 2 lowest disability categories. Porous tantalum shows promising results in revision arthroplasty with severe acetabular bone loss.

Management of acetabular bone loss in revision total hip arthroplasty

Most acetabular revisions can be managed with a hemispherical component with screw fixation. Areas of segmental bone loss that preclude acetabular component stability may be managed with structural allograft or second-generation porous metal augments. Acetabular cages have a limited application but can be a useful tool in the management of massive bone loss and pelvic discontinuity.

Revisions of extensive acetabular defects with impaction grafting and a cement cup

BACKGROUND

Loosening of acetabular components often leads to bony defects. Management of extensive acetabular bone loss in hip revision arthroplasty can be a tremendous challenge.

QUESTIONS/PURPOSES

We asked whether a reconstruction with impacted bone grafts will provide a durable and pain-free function in extensive acetabular defects. We specifically determined the (1) survival rates with the end point of revision for any reason, aseptic revision, and radiographic loosening; (2) visual analog scale (VAS) pain score, Harris hip score (HHS), and the Oxford Hip Questionnaire score (OHQS); (3) number of repeat revisions; (4) complications; and (5) radiographic loosening, wear, and radiolucencies.

PATIENTS AND METHODS

We retrospectively followed 25 patients (27 hips) with extensive acetabular defects. No patient was lost to followup. Two patients died during followup. Minimum followup was 3 years (mean, 8.8 years; range, 3-14.1 years).

RESULTS

Three patients (three hips) underwent repeat revision surgery and another two patients (two hips) had radiographically loose hips. The 10-year survival rate was 88% (95% confidence interval, 74.2%-100%) with the end point acetabular revision for any reason and 95% (95% confidence interval, 86.0%-100%) with the end point acetabular revision for aseptic loosening. The mean HHSs were 55 points before surgery and 72 points postoperatively.

CONCLUSIONS

Acetabular reconstruction with impaction bone grafting and a cemented cup is a reliable technique with a 10-year survival rate of 88% in patients with extensive acetabular deficiencies.

LEVEL OF EVIDENCE

Level IV, case series. See the Guidelines for Authors for a complete description of levels of evidence.

Cementless acetabular revision: past, present, and future. Revision total hip arthroplasty: the acetabular side using cementless implants

BACKGROUND

Acetabular revision is probably the most difficult aspect of hip reconstructive surgery. Although the majority of acetabular revisions can be performed using an uncemented hemispherical acetabular device with ancillary fixation, patients with severe acetabular deficiencies and poor bone quality require more complex alternatives for revision. The limitations of traditional cementless acetabular implants has promoted the development of improved methods of fixation and revision techniques. Highly porous metals have been introduced for clinical use in arthroplasty surgery over the last decade. Their higher porosity and surface friction are ideal for acetabular revision, optimising biological fixation. The use of trabecular metal cups in acetabular revision has yielded excellent clinical results.

PURPOSE

This review focuses on the use of cementless implants for acetabular revision. The use of trabecular metal cups, augments, jumbo cups, oblong cups, cages, and structural grafting are also discussed.

[Standardized reconstruction of acetabular bone defects using the cranial socket system]

OBJECTIVE

Management of primary or secondary acetabular bone loss (D'Antonio type I-IV ). Implantation and stable fixation using a cementless, cranially extended oval press-fit cup to restore painless joint function and loading capacity.

INDICATIONS

Septic or aseptic loosening of the acetabular component after total hip arthroplasty. Acetabular bone loss after tumor resection. Primary acetabular bone defects in developmental dysplasia of the hip.

CONTRAINDICATIONS

Persistent deep infection. Bone defects including the parts of the iliac bone adjoining the sacrum (fixation of the stem in the ilium is not possible any more).

SURGICAL TECHNIQUE

Complete exposure of the acetabular defect using a standard approach. Removal of the loose cup. Excision of soft and granulation tissue from the acetabular ground and the rim. Reaming of the acetabulum with sequentially larger hemispheric reamers until an adequate bony bed is created for the insertion of the cranial socket. Eccentric cranial sockets without a craniolateral flap are preferable for use in type I and II defects with teardrop lysis mostly involving the craniolateral acetabulum, if a trihedral press-fit fixation can be achieved. Supplementary screw fixation through the acetabular ground, is possible. If a type III defect is present, the authors recommend the use of cranial sockets with an anatomic flap in order to increase primary stability by supplementary screw fixation. This is especially recommended for the management of deficiencies in the medial or posterior wall. If there is pelvic discontinuity (type IV), adequate acetabular reconstruction with primary stability of the component can only be achieved by a supplementary intramedullary structured stem fixed in the dorsal part of the ilium.

POSTOPERATIVE MANAGEMENT

Partial loading of the operated limb with 10 kg for a period of 6-12 weeks. Then increased loading with 10 kg per week. Thrombosis prophylaxis until full weight bearing. Physiotherapy and gait training.

RESULTS

A total of 50 cup revisions using the ESKA cranial socket system were clinically and radiologically analyzed with an average follow-up of 65.7+/-28.5 months (26-123 months). Defects were classified according to D'Antonio. There were 21 type II, 23 type III, and six type IV defects. The Harris Hip Score increased from 40 preoperatively to 68.3 points postoperatively. Four patients had recurrent hip dislocation requiring replacement of the inlay. In four cases of aseptic loosening, the acetabular component had to be revised. With revision of the acetabular component as an endpoint, implant survival was 92% after an average of 5.4 years.

Results of isolated femoral component revision with well-fixed acetabular implant retention

The present study was undertaken to evaluate the clinical and radiological results of isolated femoral revisions conducted while retaining well-fixed cementless acetabular sockets. Thirty-nine patients that underwent isolated femoral stem revisions were reviewed. Mean age at time of surgery was 60.5 years, and mean follow-up duration was 4.2 years. Decisions to retain acetabular sockets were based on clinical and radiographic findings and intraoperative stabilities. During revisions, polyethylene liners were exchanged for metal-inlay polyethylene liners to have a metal-on-metal bearing surface in 23 cases. Mean Harris hip score improved from 58 points preoperatively to 85 points at final follow-up (P < .001). With the exception of one patient, no increases in acetabular radiolucent line numbers or thicknesses were observed during follow-up visits. Isolated femoral stem revisions with acetabular socket retention were found to provide excellent clinical and radiographic results.

Porous-coated cementless acetabular components without bulk bone graft in revision surgery

We previously reported the average 9.3-year (range, 5-13 years) results of 74 patients (83 hips) with porous-coated acetabular components that were placed without bulk bone graft at revision surgery. Since the previous report, 7 patients (7 hips) died before the minimum follow-up of 10 years, and 1 patient (1 hip) was lost to follow-up. We now report the average 15.6-year (range, 10-20 years) results for 66 patients (75 hips). Three additional acetabular components were removed or revised again: 2 for infection and 1 for dislodgement of the polyethylene liner from the metal shell. Overall, 7 (7%) components required removal or repeat revision. No shell was revised for aseptic loosening, and none was categorized as loose during the entire follow-up period.

Revision of failed total hip arthroplasty acetabular cups to porous tantalum components: a 5-year follow-up study

We reviewed 263 consecutive patients with failed acetabular components after total hip arthroplasty that were revised using porous tantalum acetabular components and augments when necessary. The mean follow-up was 73.6 months (range, 60-84 months). The improvement of mean Harris hip score, Western Ontario and McMaster Osteoarthritis Index, and University of California Los Angeles activity scales were statistically significant (P < .001). Subjective assessments showed that 87.3% of patients reported "improvement" and 85.9% were "very or fairly pleased" with the results. At the most recent follow-up, all acetabular components were radiographically stable and none required rerevision for loosening. The acetabular revision was considered successful in 87% of cases. From this study, we conclude that the acetabular component used was reliable in creating a durable composite without failure for a minimum of 5 years.

Constrained acetabular liners cemented into cages during total hip revision arthroplasty

The combination of acetabular bone loss and hip instability is challenging. Sixteen patients underwent revision total hip arthroplasty using constrained acetabular liners cemented into cages. The average follow-up was 28 months (range, 24-60 months). Clinical evaluation was obtained using the Harris hip score along with radiographic data. At latest follow-up, 13 patients were available for evaluation. Although the average postoperative Harris hip score was 62 points, which was better than the preoperative score of 27 points, the overall radiographic failure rate was 23%. The combination of poor acetabular bone stock and altered stresses from the increased constraint likely led to the poor outcome. We would only recommend use of a cemented, constrained acetabular liner in combination with a protrusio cage as a bail out or salvage procedure.

Cementless acetabular socket revisions using Metasul metal-on-metal bearings

Thirty-four hips were treated with cementless acetabular socket revisions using a metal-on-metal bearing. The causes of revision were aseptic loosening in 33 hips and septic loosening in 1 hip. Revisions were performed for acetabular sockets in 28 hips and for acetabular sockets and femoral stems in 6 hips. Mean follow-up duration was 6.2 years (range, 4.0-9.1 years), and mean Harris Hip Scores improved from 56 to 92 points. No hip required further revision for aseptic loosening. Focal femoral osteolysis newly developed in zone I in 1 hip, which was treated by curettage and bone grafting. The authors suggest that second-generation metal-on-metal bearings in cementless acetabular socket revisions can achieve good medium-term clinical and radiographic results.

Results of the cementless Plasmacup in revision total hip arthroplasty: a retrospective study of 72 cases with an average follow-up of eight years

BACKGROUND

There are multiple revision implant systems currently available for socket revision in revision total hip arthroplasty. Up until now, not all of these systems have been followed up with regards to their long-term use as a revision implantation.For the first time, this study presents the hemispherical porous-coated socket Plasmacup SC, produced by Aesculap, Tuttlingen, Germany, and the clinical and radiological mid-term results of this revision cup implant.

METHODS

Over a period of ten years the Plasmacup SC press-fit-cup was used as a revision implant in 72 consecutive aseptic cases which were included in this retrospective study. The mean follow-up period was 8 years. Bone graft transplantation was performed in 32% of all cases. In 90%, the cup was fixed with additional screws. The follow-up radiographs were analysed with regards to cup migration, osteointegration and osteolysis in the DeLee zones using a computer aided program taking the teardrop figure as a main point of reference. For clinical evaluation the Harris-Hip-Score and the WOMAC-Score were utilized.

RESULTS

At the follow up examination, the mean Harris-Hip-Score was 83.5 points and the mean WOMAC-Score 34.7 points. 93% of all patients were satisfied with the result of the operation. No aseptic cup loosening could be observed and only one cup had to be removed due to infection. No significant longitudinal or transversal cup migration could be observed.

CONCLUSION

Aesculap's Plasmacup SC is suitable as a cementless cup revision implant. There is stable cup osteointegration, post press-fit implantation, even in the case of major acetabular bone defects.

Impaction bone grafting for acetabular reconstruction: mean 5.5-year results in Japanese patients

INTRODUCTION

We performed a retrospective outcome study on 23 consecutive acetabular reconstructions involving impaction bone grafting in Japanese patients.

METHOD

Two hips had cavitary defects, and 21 hips had combined segmental and cavitary defects. The mid-term follow-up was performed at a mean of 5.5 years postoperatively. The mean Merle d'Aubigné and Postel hip score had improved from 11.5 to 15.7 points at the final follow-up. Two hips showed migration at 30 months after surgery, and one of these was a candidate for re-revision due to symptomatic cup migration.

RESULTS

The Kaplan-Meier survival rate of the cup, with loosening and re-operation as the end points, was 91.3 and 95.7% at 5 years, respectively.

CONCLUSION

Acetabular impaction bone grafting is a reproducible technique in which surgeons should strictly follow the recommended technical procedure.

Tantalum components in difficult acetabular revisions

Although porous-coated hemispherical components are usually successful in acetabular revisions, the rate of failure is increased in hips with severe bone loss. Tantalum acetabular implants are characterized by higher friction, higher porosity, and greater osteoconductivity than titanium mesh or chrome-cobalt beads. We asked whether these components would provide stable short-term fixation without radiographic loosening in revisions at higher risk for failure. We prospectively followed 37 patients (39 hips) who had an acetabular revision with tantalum acetabular components. The minimum followup time was 2 years (mean, 3.3 years; range, 2-7 years). The acetabular defects were classified as Paprosky et al. Type 3 in 26, Type 2 in 11, and Type 1 in two hips. The mean postoperative Harris hip score was 86. Thirty-eight of the 39 (97%) tantalum components were radiographically well fixed. There was one mechanical failure at 6 months, rerevised with a larger tantalum component. Bone ingrowth was apparent in 38 hips and four hips had a radiolucent line. There were six other reoperations, three recurrent dislocations (constrained liners leaving the shell in place), two infections that seeded to the hip from elsewhere and treated with drainage, and one supracondylar femur fracture, but the tantalum component was left in place. Tantalum acetabular components provide stable fixation in difficult acetabular revisions.

LEVEL OF EVIDENCE

Level IV, case series. See Guidelines for Authors for a complete description of levels of evidence.

The management of severe acetabular bone defects in revision hip arthroplasty using modular porous metal components

We investigated the early results of modular porous metal components used in 23 acetabular reconstructions associated with major bone loss. The series included seven men and 15 women with a mean age of 67 years (38 to 81), who had undergone a mean of two previous revisions (1 to 7). Based on Paprosky's classification, there were 17 type 3A and six type 3B defects. Pelvic discontinuity was noted in one case. Augments were used in 21 hips to support the shell and an acetabular component-cage construct was implanted in one case. At a mean follow-up of 41 months (24 to 62), 22 components remained well fixed. Two patients required rerevision of the liners for prosthetic joint instability. Clinically, the mean Harris Hip Score improved from 43.0 pre-operatively (14 to 86) to 75.7 post-operatively (53 to 100). The mean pre-operative Merle d'Aubigné score was 8.2 (3 to 15) and improved to a mean of 13.7 (11 to 18) post-operatively. These short-term results suggest that modular porous metal components are a viable option in the reconstruction of Paprosky type 3 acetabular defects. More data are needed to determine whether the system yields greater long-term success than more traditional methods, such as reconstruction cages and structural allografts.

[Comparison of different cup revision systems]

Aseptic loosening of hip cups results in cranial and medial migration, which induces bone resorption and defects. Despite these defects, it is the aim in cup revision arthroplasty to get a stable fixation and a restoration of the hip center. Depending on the size of the defect, which can be classified by different scoring systems, various strategies requiring an experienced surgeon can be used to reach this aim. If defects are localized, bigger primary cemented or cement-free cups can be used. Larger defects may need bone transplantation or special designs such as oval cups or reinforcement rings. They can be used with or without plates in combination with cement for inlay fixation. In the case of bigger defects or pelvic discontinuity, modular systems or a socket cup may be necessary.