Acetabular revision arthroplasty using so-called jumbo cementless components: an average 7-year follow-up study

AAHKS Surgical Techniques & Technologies Award: Inferior Screw Fixation Decreases Acetabular Component Failure Following Revision Total Hip Arthroplasty

BACKGROUND

Adjunctive screw fixation has been shown to be reliable in achieving acetabular component stability in revision total hip arthroplasty (THA). The purpose of this study was to assess the effect of inferior screw placement on acetabular component failure following revision THA. We hypothesized that inferior screw fixation would decrease acetabular failure rates.

METHODS

We reviewed 250 patients who had Paprosky Type II or III defects who underwent acetabular revision between 2001 and 2021 across three institutions. Demographic factors, the number of screws, location of screw placement (superior versus inferior), use of augments and/or cup-cage constructs, Paprosky classification, and presence of discontinuity were documented. Multivariate regression was performed to identify the independent effect of inferior screw fixation on the primary outcome of aseptic rerevision of the acetabular component.

RESULTS

At a mean follow-up of 53.4 months (range, 12 to 261), 16 patients (6.4%) required re-revision for acetabular loosening. There were 140 patients (56.0%) who had inferior screw fixation, all of whom did not have neurovascular complications during screw placement. Patients who had inferior screws had a lower rate of acetabular rerevision than those who only had superior screw fixation (2.1 versus 11.8%, P = .0030). Multivariate regression demonstrates that inferior screw fixation decreased the likelihood of rerevision for acetabular loosening when compared to superior screw fixation alone (odds ratio: 0.1, confidence interval: 0.03 to 0.5; P = .0071). No other risk factors were identified.

CONCLUSIONS

Inferior screw fixation is a safe and reliable technique to reduce acetabular component failure following revision THA in cases of severe acetabular bone loss.

Impaction bone grafting for contained acetabular defects in total hip arthroplasty

BACKGROUND

Acetabular bone loss is a technical challenge in total hip arthroplasty (THA). This study sought to report the functional and radiological results of acetabular reconstruction using impaction bone grafting (IBG) in patients with acetabular bone deficiency undergoing primary or revision THA.

METHODS

In this prospective study, full history taking, preoperative clinical and radiological evaluation, and preoperative planning and templating were performed. The Paprosky classification and the American Academy of Orthopaedic Surgeons classification were used to assess the acetabular deficiencies. Clinical outcomes were assessed utilizing the Harris hip score (HHS) and a 4-question satisfaction questionnaire. Graft incorporation was evaluated in the last follow-up X-rays.

RESULTS

This study included 50 patients with a mean age of 46.7 ± 15.3 years. The THA was primary in 14 (28%) patients and revision in 36 (72%) patients. The mean HHS improved significantly from 28.8 ± 24.1 preoperatively to 76.6 ± 6.1, with a mean follow-up period of 23 months. Overall, 88% of patients were very satisfied. Complete radiological graft incorporation to host bone was achieved in 35 (70%) patients, and the remaining patients had partial incorporation. Complete graft incorporation was associated more frequently with primary THA, autografts, cementless cups, decreased defect size, and decreased graft layer thickness.

CONCLUSIONS

IBG for acetabular reconstruction in THA can achieve excellent clinical and radiological outcomes with a low complication rate.

LEVEL OF EVIDENCE

Level IV.

SuperPath® vs. direct anterior approach : A retrospective comparison between two minimally invasive approaches in total hip arthroplasty

OBJECTIVE

Minimally invasive approaches are subject to controversy in orthopedic surgery. The aim of the current study was to compare the radiographic parameters between two minimally invasive approaches in total hip arthroplasty.

MATERIAL AND METHODS

Between January 2018 and February 2019, the radiographic parameters of 80 patients undergoing total hip arthroplasty via minimally invasive approaches (DAA: n = 40; SuperPath® SP: n = 40) have been measured. The radiographic analysis was performed with digital software tool mediCad® (HECTEC™ GmbH, Landshut, Germany).

RESULTS

Patients treated with DAA showed significantly higher inclination (SP: 39.7° ± 7.3° vs. DAA: 44.7° ± 5.3°) and significantly lower cup anteversion values (SP: 31.2° ± 7.9° vs. DAA: 27. 5° ± 5.3°, p < 0.001) than patients undergoing THA via SP postoperatively. The horizontal femoral offset was neither preoperatively nor postoperatively higher in DAA than in SP cohort (preoperative: p = 0.71, postoperative: p = 0.25) (preoperative: SP:37.2 mm ± 7.3 vs. DAA 38.2 mm ± 7.5; postoperative: SP: 38.0 mm ± 7.2 vs. DAA: 40.5 mm ± 7.0). At both times, the acetabular offset was significantly higher in DAA cohort than in SP cohort (preoperative: SP: 32.9 mm ± 5.9 vs. DAA: 36.8 mm ± 4.9; postoperative: SP: 28.9 mm ± 4.2 vs. DAA: 33.4 mm ± 3.8) (preoperative: 0.001; postoperative: p < 0.001). The vertical height was preoperatively and postoperatively not significantly higher in SP cohort than in DAA cohort (preoperative: SP: 16.1 mm ± 4.1 vs. DAA: 15.5 mm ± 4.9; postoperative: SP: 16.6 mm ± 4.6 vs. DAA: 16.1 mm ± 4.6) (preoperative: p = 0.77; postoperative: p = 0.58). The preoperatively existing leg length discrepancy of the affected leg could be compensated via surgery without showing significant differences between the two cohorts (preoperative: SP: -3.2 mm ± 5.4 vs. DAA: 1.9 mm ± 4.9; postoperative: SP: 1.5 mm ± 5.4 vs. DAA: 4.8 mm ± 5.6) (preoperative: p = 0.34; postoperative: p = 0.09).

CONCLUSION

The current study demonstrates suitable cup positioning and stem alignment in the coronal plane using minimal-invasive approaches DAA and Superpath®.

Extended Fixation for Paprosky Type III Acetabular Defects in Revision Total Hip Arthroplasty with a Minimum Follow-Up of 2 Years

OBJECTIVE

Revision of total hip arthroplasty for patients with severe acetabular bone defects is challenging. This study aims to report the minimum 2 years outcome of the iliac extended fixation technique in patients with Paprosky type III acetabular defects.

METHODS

Fifty-seven revision total hip arthroplasty patients were retrospectively reviewed who underwent reconstruction with the concept of iliac extended fixation from 2014 to 2017 in our hospital. We proposed a new concept of "iliac extended fixation" in revision total hip arthroplasty as fixation extending superiorly 2 cm beyond the original acetabular rim with porous metal augments, which was further classified into intracavitary and extracavitary fixation. Patients were assessed using the Harris Hip Score and the Western Ontario and McMaster Universities Osteoarthritis Index Score. Radiographs and patient-reported satisfaction were assessed.

RESULTS

At an average follow-up of 63 months (range 25-88 months), the postoperative Harris Hip Score and Western Ontario and McMaster Universities Osteoarthritis Index scores were significantly improved at the last follow-up (p < 0.001). The center of rotation was significantly improved (p < 0.05). Fifty-three (93.0%) patients were satisfied with the outcome. The extracavitary iliac extended fixation group had higher rate of osteointegration in zone 1A (the superior lateral zone) than the intracavitary iliac extended fixation group (82.3% vs 55.0%, p = 0.015), and significantly more horizontal screws fixation (5.1 ± 24.7° vs 42.3 ± 36.8°, p < 0.001).

CONCLUSION

Intracavitary and extracavitary iliac extended fixation with porous metal augments and cementless cups are effective in reconstructing severe superior acetabular bone defects. The difference in screw direction might reflect the different biomechanics of augment fixation.

Trabecular titanium cups in acetabular revision arthroplasty: analysis of 10-year survivorship, restoration of center of rotation and osteointegration

AIMS

In case of severe bone loss, acetabular revision can be challenged using extra porous pure trabecular titanium (TT) revision cups designed to ensure enhanced iliac and ischiatic purchase. Aim of the study is to report on the clinical and radiological results of a TT acetabular component, evaluating functional outcome, restoration of the hip center of rotation and osteointegration.

METHODS

85 patients, who underwent acetabular revision with a TT revision cup system between October 2009 and December 2018, were included in a retrospective study. Clinical outcome were assessed with Harris Hip Score (HHS). The hip rotation center was measured using the Pierchon method on the AP pelvis film. Loosening of the cup was determined according to the Kosashvili modification of Gill's criteria. Kaplan- Meier survivorship curve was performed. Results The mean follow-up was 6.12 years. The average HHS improved from 54.7 points to 89.7 points (p < 0.05). Two acetabular components (2.3%) were re-revised after a mean of 5.6 years, for aseptic loosening and for infection, with a progressive radiolucency and a > 5 mm vertical migration, respectively. The radiographic evaluation of the position of the hip rotation center revealed a statistically significant difference (p < 0.05) between the pre- and post-operative values. The hip rotation center was correctly restored within 5% of the reference Pierchon values in a percentage of 85.4% relative to horizontal parameters and within 8% in a percentage of 66.7% relative to vertical parameters. 5-year and 10-year survivorships were, respectively, 100% and 88%.

CONCLUSIONS

In case of severe bone loss, TT revision cup system allows for good restoration of center of rotation and osteointegration showing good 10-year survival rate.

Major acetabular defects: outcomes of first revision total hip arthroplasty using Kerboull cross-plate with allograft and cemented dual mobility cup at a maximum follow-up of fourteen years

BACKGROUND

The use of dual mobility cups (DMC) has been shown to reduce hip instability after revision surgery. For severe acetabular bone loss, reconstruction with a Kerboull cross-plate and bone allograft would contribute to restoring native hip position and bone stock. Only two papers reported on the combination of Kerboull cross-plate with bone allograft and cemented DMC in revision total hip arthroplasty (THA).

METHODS

This is a monocentric retrospective study (28 cases) of first-time revision THA using such a construct in American Association of Orthopaedic Surgeons (AAOS) grade III and IV acetabular bone defect. Detailed demographic, clinical and radiographic results were recorded and evaluated.

RESULTS

With a mean follow-up of six ± 3.63 years, no case of instability was reported. The modified Harris Hip Score (mHHS) was 88.4 ± 10.1. No hook fracture or mechanical failure was observed. Non-progressive radiolucent lines were recorded. Osteointegration of the allografts was observed in all cases with a mean Grodet score of 7.9 ± 0.97.

CONCLUSIONS

In first revision THA, the use of a Kerboull cross-plate with allograft and a cemented DMC in AAOS grade III and IV acetabular bone defects demonstrated excellent clinical and radiological outcomes with no recorded cases of dislocation or mechanical failure.

Design, fabrication, and structural safety validation of 3D-printable biporous bone augments

The use of commercial products such as a cup and liner for total hip arthroplasty for patients with severe bone defects has a high probability of failure. In these patients the cup alone cannot cover the bone defect, and thus, an additional augment or cage is required. In this study, we designed three-dimensional (3D) printable bone augments as an alternative to surgeries using reinforcement cages. Thirty-five sharp-edged bone augments of various sizes were 3D printed. A biporous structure was designed to reduce the weight of the augment and to facilitate bone ingrowth. Two types of frames were used to prevent damage to the augment’s porous structure and maintain its stability during printing. Furthermore, two types of holes were provided for easy augment fixation at various angles. Fatigue tests were performed on a combination of worst-case sizes derived using finite element analysis. The test results confirmed the structural stability of the specimens at a load of 5340 N. Although the porosity of the specimens was measured to be 63.70%, it cannot be said that the porous nature was uniformly distributed because porosity tests were performed locally and randomly. In summary, 3D-printable biporous bone augments capable of bonding from various angles and bidirectionally through angulation and bottom-plane screw holes are proposed. The mechanical results with bone augments indicate good structural safety in patients. However, further research is necessary to study the clinical applications of the proposed bone augment.

Graphic abstract

Clinical and radiological outcomes of jumbo cup in revision total hip arthroplasty: A systematic review

Introduction

Many studies have reported the clinical outcomes of a jumbo cup in revision total hip arthroplasty (rTHA) with acetabular bone defect. We conducted a systematic review to access the survivorship and clinical and radiological outcomes of a jumbo cup in rTHA.

Methods

A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A comprehensive literature search from PubMed, MEDLINE, EMBASE, and the Cochrane Database of Systematic Reviews was performed with the keywords (“revision” OR “revision surgery” OR “revision arthroplasty”) AND (“total hip arthroplasty” OR “total hip replacement” OR “THA” OR “THR”) AND (“jumbo cup” OR “jumbo component” OR “extra-large cup” OR “extra-large component”). Studies reporting the clinical or radiological outcomes were included. The basic information and radiological and clinical results of these studies were extracted and summarized for analysis.

Results

A total of 19 articles were included in the systematic review. The analysis of clinical results included 953 hips in 14 studies. The re-revision-free survivorship of the jumbo cup was 95.0% at a mean follow-up of 9.3 years. Dislocation, aseptic loosening, and periprosthetic joint infection were the top three complications with an incidence of 5.9%, 3.0%, and 2.1%, respectively. The postrevision hip center was relatively elevated 10.3 mm on average; the mean postoperative leg-length discrepancy was 5.4 mm.

Conclusion

A jumbo cup is a favorable option for acetabular bone defect reconstruction in rTHA with satisfying survivorship and acceptable complication rates.

Defining the canal for ischial and pubic screws in cup revision surgery

Purpose

When revising acetabular cups, it is often necessary to provide additional stabilisation with screws. In extensive defect situations, the placement of screws caudally in the ischium and/or pubis is biomechanically advantageous. Especially after multiple revision operations, the surgeon is confronted with a reduced bone stock and unclear or altered anatomy. In addition, screw placement caudally is associated with greater risk. Therefore, the present study aims to identify and define safe zones for the placement of caudal acetabular screws.

Methods

Forty-three complete CT datasets were used for the evaluation. Sixty-three distinctive 3D points representing bone landmark of interests were defined. The coordinates of these points were then used to calculate all the parameters. For simplified visualisation and intra-operative reproducibility, an analogue clock was used, with 12 o’clock indicating cranial and 6 o’clock caudal.

Results

A consistent accumulation was found at around 4.5 ± 0.3 hours for the ischium and 7.9 ± 0.3 hours for the pubic bone.

Conclusions

The anatomy of the ischium and pubis is sufficiently constant to allow the positioning of screws in a standardised way. The interindividual variation is low — regardless of gender — so that the values determined can be used to position screws safely in the ischium and pubis. The values determined can provide the surgeon with additional orientation intra-operatively when placing caudal acetabular screws.

The application of custom-made 3D-printed titanium augments designed through surgical simulation for severe bone defects in complex revision total hip arthroplasty

Background

With the development of radiology and three-dimensional (3D) printing technology, custom-made 3D-printed titanium augments have been more widely used. However, the radiological and clinical outcomes of custom-made augments lack reports. To better understand the clinical effect of using 3D-printed titanium augments and the significance of accurate placement, the aim of this study was to assess the outcomes when using custom-made 3D-printed titanium augments and to validate the idea that surgical simulation should be done before designing custom-made augments.

Methods

A retrospective review was conducted on 31 surgical simulations and revision total hip arthroplasties using custom-made 3D-printed titanium augments. The safe zone, cup position, and hip rotation center were measured on anteroposterior radiographs. Clinical outcomes were assessed with a mean 21.1 months of follow-up.

Results

All patients were positioned within the safe zone, and none of the acetabular cups nor the custom-made augments had any evidence of migration at the latest follow-up. A strong correlation was found between the planned cup position and the postoperative position. The average vertical position of the center of rotation was significantly increased from 3.55 cm to 2.35 cm. The mean Harris Hip Score was increased from 40.81 preoperatively to 65.46 postoperatively. Complications included gait abnormality, groin pain, fracture of the greater trochanter, and partial palsy of the sciatic nerve. However, patient satisfaction reached 92.3%.

Conclusion

Surgical simulations help to design custom-made augments accurately and improve surgical plans. Acetabular components supported with custom-made 3D-printed augments is a useful method to bridge severe bone deficiencies. In this study, both the radiologic results and clinical outcomes were favorable.

Level of evidence

Level 4.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10195-022-00656-5.

Acetabular Revision Arthroplasty Based on 3-Dimensional Reconstruction Technology Using Jumbo Cups

Background: This study was aimed at evaluating the changes in cup coverage (CC) and hip center of rotation (HCOR) in acetabular defects of various severities treated with acetabular revision using jumbo cups.

Methods: A total of 86 hips were included. The American Academy of Orthopedic Surgeons (AAOS) classification of these patients was as follows: 16 patients, AAOS I; 16 patients, AAOS II; and 16 patients, AAOS III. A three-dimensional (3D) implant simulation technique was used to visualize the placement of jumbo cups during revision arthroplasty. The acetabular anteversion, inclination, CC, and the HCOR were measured.

Results: The inclination and anteversion of simulated acetabular cups in AAOS I–III groups were consistent with the normal acetabular anatomy. Compared with the controls, in AAOS I–III groups, the HCOR was significantly increased and CC was significantly decreased. The HCOR elevation was significantly higher in AAOS III patients than in AAOS I (p = 0.001) and AAOS II patients (p < 0.001). The use of the jumbo cup technology for acetabular revision would decrease the CC in AAOS I–III patients to 86.47, 84.78, and 74.51%, respectively.

Conclusion: Our study demonstrated that in patients with acetabular defects, acetabular revision arthroplasty using jumbo cups will lead to decreased CC and HCOR upshift. Upon classifying these patients according to the AAOS classification, CC decreased with the severity of acetabular defects, and the elevation of the HCOR in AAOS III patients exceeded 10 mm and was significantly higher than in other patients.

Jumbo cup in hip joint renovation may cause the center of rotation to increase

BACKGROUND

Utilizing the large jumbo cup in revision total hip arthroplasty is an effective approach to cure many lacunar and segmental peripheral bone defects. However, with the use of the jumbo cup, the center of the hip joint may become elevated relative to the primary acetabulum, and the diameter of the large cup is greater.

AIM

To study the height and the significance of the elevation of the hip joint center.

METHODS

Eighty-eight patients matched the criteria for this condition and were included in the study. The center height of the hip joint was measured relative to the opposite normal hip joint. The diameter of the jumbo cup was measured and checked according to operation notes, and the diameter of the jumbo cup was measured with a prosthesis label. Then, the horizontal and vertical centers of rotation were measured on the surgical side and opposite side. The average center height of the hip joint on the renovated side and the opposite side and the position of the hip cup relative to the teardrop were compared using a paired t-test.

RESULTS

Radiometric analysis showed that the average hip joint center was elevated by 7.6 mm. The rotational center height delta of the renovated hip was 7.6 ± 5.6 mm, and there was an obvious difference between the two groups (P = 0.00). The difference in horizontal distance was 0.5 ± 5.1 mm (-11.5 -14.0 mm), and there was no obvious difference between the two groups (P = 0.38). According to the foreign standard, the rotational center height delta of the renovated hip was 7.5 ± 6.2 mm, and there was a significant difference between the two groups (P = 0.00). There was no obvious difference between the domestic and foreign standards (P > 0.05) between the two groups.

CONCLUSION

The application of the jumbo cup elevates the rotational center of the hip joint, but it is feasible and effective to use the jumbo cup.

Clinical and Radiological Outcome of Acetabular Reconstruction Rings in Complex Primary and Revision Total Hip Arthroplasty

BACKGROUND

Acetabular reconstruction in complex primary and revision total hip arthroplasty (THA) with bone loss poses a great challenge. We aim to evaluate the medium-term clinical and radiological outcome of reconstruction rings used in these difficult situations.

METHODS

We retrospectively reviewed a consecutive series of acetabular reconstructions with Muller ring or Bursh-Schneider cage from January 2009 to December 2016. The reconstruction rings were used in 66 hips (65 patients). There were 41 complex primary THA and 25 revision THA. The mean follow-up period was 76 months (range, 37-167 months). Clinical evaluation includes the assessment of Harris hip score, visual analogue scale (VAS) score, limb length discrepancy, and activities of daily living. The radiographs were analyzed for any signs of loosening, osteolysis, acetabular migration, and heterotopic ossification.

RESULTS

The overall survival rate was 95% for revision in aseptic loosening and 87% for any reason at an average follow-up of 6.3 years. Twelve patients died and 9 patients were lost to follow-up leaving 45 patients for final functional analysis. Among the 45 patients, excellent to good results were seen in 33 patients, fair results were seen in 5 patients, poor results were seen in seven patients. Two patients had aseptic loosening and another two patients developed deep chronic infection awaiting two-stage revision.

CONCLUSION

Reconstruction rings still place a role in the armamentarium for complex acetabular reconstruction. It helps to reliably restore the bone stock, have an acceptable survival rate and satisfactory functional outcome at medium to long-term follow-up.

Cementless jumbo cups for revision of failed Furlong prosthesis. A case series

BACKGROUND

Revision of failed total hip arthroplasty (THA) presents great challenge to any orthopaedic surgeon especially in the presence of acetabular defects where the main goal is to achieve durable fixation of prosthetic components to bone which is the key to successful revision surgery.

METHODS

Seventeen patients (17 hips) with mean age of 52 (40-61) years had revision surgery for aseptic failure of Furlong hydroxyapatite-ceramic-coated (HAC) prosthesis using cementless jumbo cups. Patients were reviewed clinically and radiographically with mean follow-up of 3.5 years (2-6). No patient was lost to follow up.

RESULTS

All revised acetabular components showed polyethylene wear, severe metallosis, with acetabular defects IIB (4/17), and IIIA (13/17) according to Paprosky classification. The femoral component was well fixed in all cases but one patient had stem revision for femoral fracture mal-union. There was one early post-operative infection; there was no postoperative dislocation, sciatic nerve injury, periprosthetic fracture or deep venous thrombosis. At last follow-up, no progressive radiolucencies or acetabular migration was identified. The mean Harris hip score improved from 42 (24-59) pre-operatively to 85 (72-92).

CONCLUSION

Good clinical results and radiographic stability were obtained at short term follow up after acetabular revision using cementless jumbo cups, which justify its use in revision surgery even in the face of major acetabular defects. Furlong HAC femoral component gives excellent long-term survival in young and active patients with a survival rate of 94% at 18.6 years.

Mid-Term Follow-Up of Acetabular Revision Arthroplasty Using Jumbo Cups

OBJECTIVE

To evaluate the mid-term clinical and radiographic results of revision total hip arthroplasty (THA) using jumbo cups in Chinese patients.

METHODS

We retrospectively studied 61 patients (63 hips; 29 men [30 hips], 32 women [33 hips]) who underwent acetabular revision with jumbo cups between January 2001 and April 2016 at our institution. The mean age at the index operation was 59.4 ± 11.4 years. The mean body mass index of the patients was 24.9 ± 3.8 kg/m² . Clinical evaluation was determined using the Harris hip score preoperatively and at follow up. Major complications (including instability, sepsis, and revision of the femoral or acetabular component) were recorded. Radiographic measurements included inclination and anteversion angles of the acetabular components, and the vertical and horizontal distances of the centers of rotation (V-COR and H-COR, respectively). In the 42 patients with normal contralateral hip joints, the postoperative V-COR and H-COR were compared between right and left sides. Their improvement in leg-length discrepancy (LLD) after revision THA was also evaluated. Cup survival was evaluated using the Kaplan-Meier analysis. Clinical and radiographic outcomes were analyzed.

RESULTS

Mean follow up was 5.7 years (2-16 years). At the latest follow-up, the average Harris hip score (preoperative vs postoperative values) had improved from 46 to 83 (P < 0.001). No acetabular component was radiographically defined as loosened. Four hips (6.3%) had major complications: one hip was revised because of periprosthetic infection (at 3 months); one underwent femoral open reduction and internal fixation (with implant retention) because of a periprosthetic femoral fracture (at 13 months); one operated hip developed a deep infection (at 2.5 years), which was treated with antibiotics; one hip experienced recurrent dislocation (at 4.5 years). The average cup inclination angle was 40.8° ± 6.8° and the average anteversion angle was 14.9° ± 6.6°. Average V-COR decreased from 29.7 ± 10.4 mm to 22.3 ± 7.6 mm (P < 0.001). The average postoperative H-COR was 29.5 ± 3.7 mm compared with 30.8 ± 6.6 mm preoperatively (P = 0.145). Among the 42 patients with normal contralateral hips, the average postoperative V-COR were 22.2 ± 8.3 mm (operated side) and 14.0 ± 3.7 mm (contralateral side) (P < 0.001). LLD improved from -16.8 ± 17.1 mm to -5.6 ± 11.8 mm (P < 0.001). When failure was defined as any reoperation involving the hip, the mean 16-year hip survival was 96.8% (95% confidence interval [CI] 87.9%-99.2%). When defined as any hip reoperation or major complication, it was 92.7% (95%CI 81.2%-97.2%).

CONCLUSION

Use of jumbo cups for revision THA resulted in excellent mid-term cup survival and helped restore the COR.

Clinical and design factors influence the survivorship of custom flange acetabular components

AIMS

Custom flange acetabular components (CFACs) are a patient-specific option for addressing large acetabular defects at revision total hip arthroplasty (THA), but patient and implant characteristics that affect survivorship remain unknown. This study aimed to identify patient and design factors related to survivorship.

PATIENTS AND METHODS

A retrospective review of 91 patients who underwent revision THA using 96 CFACs was undertaken, comparing features between radiologically failed and successful cases. Patient characteristics (demographic, clinical, and radiological) and implant features (design characteristics and intraoperative features) were collected. There were 74 women and 22 men; their mean age was 62 years (31 to 85). The mean follow-up was 24.9 months (sd 27.6; 0 to 116). Two sets of statistical analyses were performed: 1) univariate analyses (Pearson's chi-squared and independent-samples Student's t-tests) for each feature; and 2) bivariable logistic regressions using features identified from a random forest analysis.

RESULTS

Radiological failure and revision rates were 23% and 12.5%, respectively. Revisions were undertaken at a mean of 25.1 months (sd 26.4) postoperatively. Patients with radiological failure were younger at the time of the initial procedure, were less likely to have a diagnosis of primary osteoarthritis (OA), were more likely to have had ischial screws in previous surgery, had fewer ischial screw holes in their CFAC design, and had more proximal ischial fixation. Random forest analysis identified the age of the patient and the number of locking and non-locking screws used for inclusion in subsequent bivariable logistic regression, but only age (odds ratio 0.93 per year) was found to be significant.

CONCLUSION

We identified both patient and design features predictive of CFAC survivorship. We found a higher rate of failure in younger patients, those whose primary diagnosis was not OA, and those with more proximal ischial fixation or fewer ischial fixation options. Cite this article: Bone Joint J 2019;101-B(6 Supple B):68-76.

Use of an offset head center acetabular shell in difficult primary total hip arthroplasties

Several conditions may predispose patients to development of antero-lateral acetabular bone deficiency, including developmental dysplasia of the hip, osteonecrosis, or septic arthritis, among others. This may compromise the ability to gain acetabular component stability and impair reliable fixation. Large acetabular shells have often been used to achieve adequate fixation in scenarios of severe bone loss, however, these techniques have been shown to elevate the center of rotation (COR) of the hip and alter hip biomechanics. Recently, a new acetabular shell was developed with a goal of maintaining the native hip COR while achieving good fixation with standard instrumentation and technique. Previous radiographic studies have demonstrated the efficacy of this shell in lowering hip COR. In this case series, we demonstrate the use of this shell in patients with difficult hip pathologies. We have demonstrated how this offset COR acetabular shell may help bring down the COR of the hip in these quite challenging cases utilizing conventional techniques.

Mid-Term Results of Graft Augmentation Prosthesis II Cage and Impacted Allograft Bone in Revision Hip Arthroplasty

BACKGROUND

Several techniques have been described for management of severe acetabular bone defects during revision hip surgery including reconstructive cages. The purpose of this study is to analyze the survival and the mid-term clinical and radiological outcome using the Graft Augmentation Prosthesis (GAP II cage) (Stryker Orthopaedics, Mahwah, NJ) in addition to impaction grafting for acetabular defects in revision hip surgery.

METHODS

This is a retrospective review of all patients who underwent acetabular revision hip replacement using GAP II cage and impaction bone grafting between 2009 and 2013 at our institution. Twenty-six patients were included with a mean age of 71 years (49-91). According to Paprosky classification, 2 patients had type IIB defect, 4 had type IIC, and 12 had type IIIA, while 8 suffered from type IIIB defect. The clinical outcome was assessed using Oxford Hip Score. Plain radiographs were used to assess preoperative bone loss, postoperative implant migration, and the incorporation of the bone graft to host bone.

RESULTS

The average Oxford Hip Score improved from 11.3 (2-22) preoperatively to 32.2 (20-48) postoperatively. The revision free survivorship of this construct was 100% at mean follow-up of 49 months (30-78). Three hips had radiological failure of the implant with no clinical consequences.

CONCLUSION

The use of GAP II cage with impaction bone grafting to reconstruct severe acetabular defects had encouraging mid-term results with low failure rate. Graft incorporation with restoration of bone stock may be beneficial should further revision surgery be needed.

11-Year Mean Follow-Up of Acetabular Impaction Grafting With a Mixture of Bone Graft and Hydroxyapatite Porous Synthetic Bone Substitute

BACKGROUND

We report an 11-year mean follow-up of the effectiveness of bone impaction grafting with bone and hydroxyapatite (HA) for large, uncontained acetabular defects in primary and revision hip surgeries.

METHODS

Over 5 years, 47 total hip arthroplasties with uncontained acetabular deficiencies were performed by augmentation using an impaction graft with 50:50 mixture of freeze-dried bone allograft and HA. Ten were primary total hip arthroplasties and 37 revision procedures. X-rays were taken postoperatively, 6 weeks, 3 months, and then annually to assess incorporation of the graft, radiolucent lines, resorption, or migration of components. Functional outcomes were assessed by annual pain and function parts of the Harris Hip Score.

RESULTS

At a mean follow-up of 10 years, the survivorship was 100%. All patients were accounted for; 6 had died. The Harris Hip Score for pain improved from 9 and 17 (primaries and revisions, respectively) to 39 and 41. For function, there was an improvement from 20 and 19 to 32 (both groups). There were lucent lines in 8 cases, 3 cups had minor/stable migration, and one cup had significant migration (>15 mm). Graft incorporation had occurred in 20 hips.

CONCLUSION

This is the longest survivorship of bone impaction grafting with morcellised bone and HA substitute. Although 11-year survivorship, function and pain are excellent, radiological findings of lysis in 8 and migration in 4 cases may be of concern for the immediate future and will need close monitoring. Even in these cases, revision may be easier because of restoration of bone stock.

Acetabular Revision Using Trabecular Metal Augments for Paprosky Type 3 Defects

BACKGROUND

Trabecular Metal (TM) augments are one option when reconstructing bone loss during acetabular side revision surgery.

METHODS

We studied 38 consecutive patients with Paprosky type 3 defects that were revised using a TM shell and one or more augments over a 6-year period. There were 29 Paprosky type 3A defects and 9 Paprosky type 3B defects. The mean age of the patients at the time of surgery was 68.2 years (range 48-84). The mean length of follow-up was 36 months (range 18-74).

RESULTS

The mean preoperative short form 12 health survey improved from 27.7 before operation to 30.1 at the time of final follow-up (P = .001). The mean Western Ontario and McMaster Universities Osteoarthritis Index score improved from 53 preoperatively to a mean of 78.8 at final follow-up (P < .0001). There was evidence of radiographic loosening in 7 of the cup-augment constructs. One patient developed a deep infection requiring re-revision. Two patients required revision for aseptic loosening.

CONCLUSION

The use of TM in complex acetabular reconstruction is associated with good outcome in the short to medium term.

Acetabular Revision Arthroplasty Using an Uncemented Deep Profile Jumbo Component: A Ten to Sixteen Year Follow-Up Study

BACKGROUND

The purpose of this study is to evaluate the outcome of revision total hip arthroplasty using an uncemented deep profile jumbo acetabular component in patients who had been followed for a minimum of 10 years postoperatively.

METHODS

Between 1997 and 2001, 61 revision total hip arthroplasties were performed in 58 patients, with use of the +5 Deep Profile acetabular shell. The outcome with regard to retention vs re-revision of the acetabular component was determined for every hip. At a mean of 13 years (range 10-16) postoperatively, 30 patients (32 hips) were living. The Harris hip score, radiographic results, complications, and Kaplan-Meier survivorship were evaluated.

RESULTS

In the entire cohort of 61 hips, 4 acetabular components have been re-revised. Two shells were re-revised for sepsis: 1 shell was re-revised for aseptic loosening and 1 for recurrent dislocation. In the 32 hips followed for a minimum of 10 years postoperatively, 2 cups have been re-revised: 1 for aseptic loosening and 1 for recurrent dislocation. One additional shell was loose by radiographic criteria. With failure defined as re-revision for any reason, implant survival (95% confidence interval) was 92.6% (81.0-97.2) at 16 years. With failure defined as re-revision for aseptic loosening, implant survival was 97.4% (82.8-99.6) at 16 years.

CONCLUSION

Revision total hip arthroplasty with the +5 Deep Profile acetabular component was associated with a good rate of survival at 16 years.

Novel Acetabular Cup for Revision THA Improves Hip Center of Rotation: A Radiographic Evaluation

BACKGROUND

Bone loss in patients undergoing revision THA poses a considerable challenge for orthopaedic surgeons. Often, to achieve better fixation in remaining bone, larger diameter acetabular components and reaming superiorly may be necessary. However, this is likely to raise the hip center of rotation, which may lead to altered biomechanics, specifically, insufficiency of the abductor muscles, altered gait, and increased risk of dislocation from impingement. More recently, a newer acetabular shell has been designed to more closely replicate the native hip center of rotation in these circumstances while maintaining adequate fixation.

QUESTIONS/PURPOSES

The purpose of this study was to compare the radiographic parameters of this newer design with conventional hemispheric cups in revision THA. Specifically, we assessed the differences in (1) vertical center of rotation (COR) displacement and (2) horizontal COR displacement.

METHODS

Between January 2016 and April 2016, five reconstructive surgeons at five institutions utilized a newer highly porous acetabular shell designed with peripheral screw holes and vertically eccentric COR to allow for restoration of center of hip rotation in revision THA. We included all patients who received this device. During this time, the general indications at these sites for using the new device included Paprosky Stage IIA, IIB, IIC, or IIIA acetabular defects. This yielded 29 patients who were subsequently matched (one to two) by cup size and sex to a cohort who underwent revision THA with conventional hemispheric cups between January 2015 and May 2016. To determine hip COR, radiographic measurements were performed. A circle contiguous to the acetabulum was drawn and the center was determined as the hip COR. All measurements were made from the interteardrop line for both the revised and native hips. A line through the teardrops was used for all horizontal measurements. Center position adjustments were made based on the manufacturer-specified values. Comparisons were performed using chi-square tests for categorical and t-tests for continuous variables. There was no difference in the severity of bone loss before the revision in the groups, as evidenced by Paprosky staging of preoperative radiographs.

RESULTS

The mean vertical COR displacement was smaller in patients who had the novel cup (3.5 mm; range, -12 to 15 mm; mean difference, -7.3 mm; 95% confidence interval [CI], -13.2 to -1.5) as compared with those who had the conventional cup (10.5 mm; range, -4 to 50 mm; mean difference, 7.3 mm; 95% CI, -12.5 to -2.2; p = 0.003). There was no difference in mean horizontal displacement between the two groups (-0.06 ± 6.1 versus 1.7 ± 7.1; mean difference, -1.8; p = 0.903).

CONCLUSIONS

Although hip COR was improved based on radiographic measurements with the use of this novel acetabular design, and although this may improve hip biomechanics, more studies are required before its widespread adoption for revision cases of this nature can be recommended. Both implant costs and the risks associated with using a new design in practice will have to be justified by studies that evaluate fixation, clinical function and implant survival, and patient-reported outcome scores, all of which were beyond the scope of this preliminary report.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Use of a revision cup for treatment of Zurich cementless acetabular cup loosening

Loosening of the acetabular cup is one of the most common complications following total hip replacement and has an incidence rate of 1.8% to 36.8%. The objective of this study was to describe the surgical technique for the application of a cementless acetabular component specifically designed for treatment of cup loosening and preliminary clinical experience. The Kyon revision cup is composed of two components; the first is a perforated titanium outer shell with holes for 2.4 mm titanium screws, which is impacted into the acetabulum after removal of the loose cup and reaming of the acetabulum. It is secured with a variable number of screws. The second component is an inner plain titanium cup with an ultra-high-molecular-weight polyethylene insert, which is impacted into the outer shell to obtain press-fit stability. This revision cup was used in 31 dogs with cup loosening and a minimum follow-up period of six months. There were four intra-operative complications and two postoperative complications. The main intra-operative complication was difficulty inserting the inner cup into the outer shell. Postoperative complications included craniodorsal hip luxation in one dog, which was successfully managed, and cup loosening in another dog, which required explantation of the prosthesis. The main advantage of the revision cup appears to be increased implant stability afforded by screw fixation. Our initial clinical results in 31 dogs were promising; all but one dog had a successful clinical outcome.

Structural Allograft Supporting a Trabecular Metal Cup Provides Durable Results in Complex Revision Arthroplasty

BACKGROUND

Revision total hip arthroplasty (THA) is challenging specially in the presence of severe acetabular bone deficiency. We report the use of a highly porous revision shell augmented by structural allograft to provide structural support and coverage to the acetabular component.

METHODS

We identified 56 patients (58 hips) undergoing revision THA, where a trabecular metal revision cup was supported by structural allograft. Mean follow-up was 5.4 years (range 2-12 years). Preoperatively acetabular bone defects were classified as Paprosky 2A in 6 hips (10%), 2B in 12 hips (21%), 2C in 12 hips (21%), 3A in 11 hips (19%), and 3B in 17 hips (29%). Structural allograft configuration was classified as type 1 (flying buttress) in 13 hips, type 2 (dome support) in 23 hips, and type 3 (footings) in 17 hips, with 5 hips having combined configurations.

RESULTS

All hips showed evidence of union between the allograft and host bone at latest follow-up, 14 hips had partial resorption of the allograft that did not affect cup stability. Three acetabular components demonstrated failure of ingrowth. Survivorship-free from radiographic acetabular loosening as end point was 94% at 5 years. The 5-year survivorship with revision for any reason as end point was 90%.

CONCLUSION

Trabecular metal shells combined with structural bone allograft in revision THA demonstrate excellent midterm survival, with 94% of acetabular components obtaining stable union onto host bone at 5 years. Allograft restored bone stock with minimal resorption, and when it occurred did not alter the survivorship of the acetabular component.

The impact of trabecular metal on hip centre of rotation in revision and complex primary hip arthroplasty, a radiological review

INTRODUCTION

Total hip arthroplasty (THA) is a very successful procedure. Revision THA is becoming increasingly common. Recent developments to improve outcomes include the development of large trabecular metal (TM) acetabular cups and augments. There is a paucity of data on the benefit of these new techniques.

METHODS

A single-centre retrospective review consisting of a radiological review of post-op revision THA anteroposterior pelvis. Data collection was performed using the Irish National Orthopaedic Register (INOR) and from a previous project. We used a technique developed by Fessy et al in 1999 to measure the centre of rotation (COR) of the hip. We then compared our study to that of a study measuring the COR of healthy native hips.

RESULTS

127 revision THA analysed. Native COR calculated by Fessy et al showed a mean horizontal (x) axis 33.6 mm (standard deviation [SD] 5.74) and a vertical (y) axis 16.4 mm (SD 4.67). Non-TM revisions showed a mean x axis of 29 mm (SD 3.9) and y axis 17.9 (SD 5.9). TM Augments had a mean x axis 29.2 mm (SD 7.9) and y axis of 21.5 (SD 8.4). TM Cups alone had a mean x axis 27 mm (SD 6.9) and y axis 22 mm (SD 10.18).

CONCLUSIONS

COR of TM implants showed considerable deviation from the norm. Non-TM implants showed a COR within acceptable physiological range. TM components consistently failed to restore a natural COR in our cohort. The implications of this remain uncertain but must be considered in any decision to use TM.

Promising early results for trabecular metal acetabular components used at revision total hip arthroplasty

Aims

The aim of this study was to compare the incidence of aseptic loosening after the use of a cemented acetabular component and a Trabecular Metal (TM) acetabular component (Zimmer Inc., Warsaw, Indiana) at acetabular revision with bone impaction grafting.

Patients and Methods

A total of 42 patients were included in the study. Patients were randomised to receive an all- polyethylene cemented acetabular component (n = 19) or a TM component (n = 23). Radiostereometric analysis and conventional radiographic examinations were performed regularly up to two years post-operatively or until further revision.

Results

The proximal migration was significantly higher in the cemented group. At two years, the median proximal migration was 1.45 mm and 0.25 mm in the cemented and TM groups, respectively (p = 0.02). One cemented component was revised due to dislocation. There were no revisions in the TM group.

Conclusion

Lower proximal migration in the TM group suggests that this design might be associated with a lower risk of aseptic loosening in the long term compared with an all polyethylene cemented component. Longer follow-up is required to confirm the clinical advantages of using this component at acetabular revision. Cite this article: Bone Joint J 2017;99-B:880–6.

Survivorship Analysis of Eighty Revised Hip Arthroplasties With the Impaction Grafting Technique Using Whole Femoral Head Allografts With the Articular Cartilage

BACKGROUND

Acetabular impaction bone grafting aims to restore anatomy in hip revision surgery. This is an effective but expensive and time-consuming technique. Usually, the articular cartilage is removed from the femoral head allograft. We aimed to reproduce the same results retaining the cartilage of the allograft.

METHODS

Eighty acetabular revisions using impacted morselized bone graft retaining the articular cartilage and a cemented cup were studied retrospectively. Six were lost during follow-up. The mean follow-up was 6.5 years (range 1-13). Clinical and radiological assessment was made using the Oxford Hip Score, Hodgkinson's criteria for socket loosening, and the Gie classification for evaluation of allograft incorporation.

RESULTS

Sixty-three sockets (85.1%) were considered radiologically stable (type 0, 1, and 2 demarcations), 8 (10.8%) were radiologically loose (type 3), and 3 (4.1%) presented with migration. Fifty-one (68.9%) cases showed good trabecular remodeling (grade 3), 20 (27%) showed trabecular incorporation (grade 2), and 3 (4.1%) showed poor allograft incorporation. Mean preoperative hip score was 43 and postoperative score was 28. Six (8.1%) cases presented heterotopic ossification around the revised implants, 2 patients (2.7%) had periprosthetic fractures, and 4 (5.4%) had dislocations. The Kaplan-Meier survivorship at a mean of 6.5 years with revision of the cup for any reason was 95.9% (95% confidence interval 5.6-7.5).

CONCLUSION

The mid-term results of our technique are promising. Particularly when the supply of fresh-frozen allografts and surgical time is limited, using whole femoral head with articular cartilage is both safe and effective.

High proximal migration in cemented acetabular revisions operated with bone impaction grafting; 47 revision cups followed with RSA for 17 years

BACKGROUND

Bone impaction grafting is a biologically and mechanically appealing option in acetabular revision surgery, allowing restitution of the bone stock and restoration of the biomechanics. We analysed differences in proximal migration of the revision acetabular components when bone impaction grafting is used together with a cemented or an uncemented cup.

PATIENTS AND METHODS

43 patients (47 hips), revised due to acetabular loosening and judged to have less than 50% host bone-implant contact were included. The hips were randomised to either an uncemented (n = 20) or a cemented (n = 27) revision cup. Radiostereometry and radiography was performed postoperatively, at 3 and 6 months, 1, 2, 3, 5, 7, 10 and 13 and 17 years postoperatively. Clinical follow-up was performed at 1, 2 and 5 years postoperatively and thereafter at the same interval as in the radiographic follow-up.

RESULTS

There were no differences in the base line demographic data between the 2 groups. At the last follow-up (17 years) 14 hips (10 cemented, 4 uncemented) had been re-revised due to loosening. 3 additional cups (1 uncemented and 2 cemented) were radiographically loose. There was a higher early proximal migration in the cemented cups.

DISCUSSION

Cups operated on with cement showed a higher early migration measured with RSA and also a higher number of late revisions. The reason for this is not known, but factors such as inclusion of cases with severe bone defects, use of smaller bone chips and issues related to the impaction technique might have had various degrees of influence.

[Effect of Jumbo cups for total hip arthroplasty revision on femoral offset and hip center of rotation]

Objective

To investigate the change of the femoral offset and hip center of rotation (COR) after using Jumbo cups in total hip arthroplasty (THA) revision.

Methods

The clinical data of 23 patients who underwent THA revision using Jumbo cups between January 2010 and May 2015 were retrospectively analyzed. Morselized bone graft was performed on 8 cases, morselized bone graft combined with structural bone graft on 10 cases. There were 10 males and 13 females, aged 65.4 years on average (range, 51-77 years). The disease duration was 1-24 years (mean, 8.57 years). The reasons for revision included aseptic loosening in 21 cases and periprosthetic infection in 2 cases. The Harris hip score and visual analogue scale (VAS) were 43.04±5.05 and 5.70±0.97 before operation respectively. According to the Paprosky acetabular defect classification, there were 5 cases of type I, 5 cases of type II A, 3 cases of type II B, 6 cases of type II C, and 4 cases of type III A. The X-ray films showed that the femoral offset was (40.65±4.09) mm for normal side and was (44.04±5.08) mm for affected side at preoperation, showing significant difference ( t=4.098, P=0.000). Ten patients underwent femoral offset reconstruction (43.48%) but 13 patients did not (56.52%) before operation. The COR was reconstructed in 10 cases (43.48%); COR elevation was observed in 11 cases (47.83%), and COR decline in 2 cases (8.69%) before operation.

Results

Primary healing of incision was obtained in all patients, with no complication of infection, vascular injury, deep vein thrombosis, dislocation of the joint, or fracture around prosthesis. All the patients were followed up 12-76 months (mean, 22.48 months). The Harris hip score and VAS were 82.09±4.53 and 0.74±0.62 at 1 year after operation respectively, showing significant differences when compared with preoperative scores ( t=37.831, P=0.000; t=22.318, P=0.000). The X-ray films showed that the femoral offset was (43.87±3.57) mm for affected side at 1 year after operation, showing no significant difference when compared with preoperative one ( t=0.250, P=0.805), but significant difference was found between affected side and normal side ( t=5.591, P=0.000). The femoral offset was restored in 16 patients (69.57%) and was not restored in 7 patients (30.43%) after operation. The COR was restored in 15 patients (65.22%) and was not restored in 8 patients (34.78%).

Conclusion

Using Jumbo cups or combined with morselized or structural bone graft is effective in restoring hip COR and femoral offset at the maximum limit in THA revision, with good short-term outcome and improved stability of acetabular prosthesis.

Use of porous tantalum components in Paprosky two and three acetabular revision. A minimum five-year follow-up of fifty one hips

INTRODUCTION

Recent studies have reported short-term favourable results of tantalum-made components in acetabular revisions with bone loss. However, there is a lack of information regarding the mid to long-term results of such components.

OBJECTIVES

The objective of this study was to analyse the outcome and survivorship of acetabular revision hip arthroplasty using tantalum components for loosening associated with bone loss at a minimum of five-year follow-up.

METHODS

We retrospectively reviewed 51 consecutive patients (51 hips) who had an acetabular revision using porous tantalum components at a minimum follow-up of five years. The mean age was 64 years (range, 31-87). There were 27 males and 24 females, 47 right hips and four left hips. Twenty-five (49 %) included a femoral revision. According to Paprosky's classification 18 hips were classified type 2A, 11 type 2B, ten type 2C, seven type 3A and five type 3B. No bone grafting was performed. Sixteen hips (31.3 %) required the use of additional tantalum-made augments stabilized by screws and cement at the cup-augment interface.

RESULTS

At a mean followup of 6.8 years (range, 5.1-10 years), the Harris hip score improved from 44 pre- operatively (range, 23-72) to 84 post-operatively (range, 33-98). The mean post-operative hip centre position in relation to the teardrop was 29 mm (range, 20-43 mm) horizontally and 21 mm (range, 8-36 mm) vertically. The mean acetabular inclination was 42° (range, 17-60°). Six hips (11.7 %) required a re-operation without component revision (two for chronic instability, one ossification removal, one haematoma, one deep infection and one periprosthetic femoral fracture). One patient required a cup re-revision for septic loosening. No aseptic loosening occurred. At last followup the radiological analysis showed one evolutive osteolysis and one screw breakage. The global survivorship was 92.3 % at 64 months. If only aseptic loosening was defined as the end-point the survivorship was 100 % at 64 months.

CONCLUSIONS

When facing an acetabular revision with severe bone loss, tantalum-made components can provide a stable fixation. This study at a minimum five-year follow-up compares favourably with other reconstruction techniques, but longer follow-up is still required.

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.

Trabecular Metal Use in Paprosky Type 2 and 3 Acetabular Defects: 5-Year Follow-Up

BACKGROUND

The reconstructive challenge of achieving a stable acetabulum in revision total hip arthroplasties in the presence of major osteolytic lesions has led to debate about the most appropriate surgical strategy to minimize implant-related failures. Trabecular metal (TM) implants have become popular but ongoing surveillance of their performance is required.

METHODS

We reviewed the clinical and radiological outcome of a consecutive series of 52 patients (55 hips) who had undergone revision total hip arthroplasty for Paprosky type 2 or 3 acetabular defects with TM revision acetabular shells between 2002 and 2008.

RESULTS

Four implant failures occurred (2 infections and 2 dislocations). Eleven patients from this cohort died (representing 12 hips) before the 5-year follow-up period giving us a follow-up of 78.2%. Implant survival at 5 years was 92% (95% confidence interval: 80.2%-96.9%). There were no cases of radiological loosening. The mean Oxford hip score was 34 (range, 5-48) at a mean follow-up of 63 months (range, 34-105 months).

CONCLUSIONS

We conclude that the use of TM revision shells for complex acetabular reconstruction yields satisfactory results.

Custom Acetabular Cages Offer Stable Fixation and Improved Hip Scores for Revision THA With Severe Bone Defects

BACKGROUND

Revision THA is particularly challenging in hips with severe acetabular bone loss. When the extent or geometry of the acetabular bone loss precludes more-straightforward techniques such as jumbo hemispheric cementless shells, reconstruction with morselized allograft protected by a custom cage may offer an alternative, but, to our knowledge, few series have reported on results with this approach.

QUESTIONS/PURPOSES

For patients with severe (Paprosky IIIB) defects, we asked: do individualized custom cages result in (1) improved Harris hip scores; (2) restoration of hip center; and (3) a low incidence of surgical complications?

METHODS

Twenty-six patients (26 hips) with a massive acetabular defect were involved in this study from 2003 to 2013. During this period, one patient was lost to followup and one died, leaving 24 patients (eight males, 16 females) in this retrospective analysis. The customized cages were individualized to each patient's bone defect based on rapid-prototype three-dimensional printed models. Mean followup was 67 months (range, 24-120 months). Harris hip scores were assessed before surgery and at each followup. Postoperative radiographs were evaluated for cage position, migration, and graft incorporation. Complications and reoperations were assessed by chart review.

RESULTS

The mean Harris hip score improved from 36 (SD, 8; range, 20-49) to 82 (SD, 18; range, 60-96) (p < 0.001). Individualized custom cages resulted in generally reliable restoration of the hip center. No rerevisions have been performed. None of the cups showed radiographic migration, but one cage was believed to be loose, based on a circumferential 2-mm radiolucent line. Cancellous allografts appeared to be incorporated in 23 of 24 patients. One deep infection and one superficial infection were observed and treated with irrigation, débridement, and vacuum-sealing drainage. One dislocation and one suspected injury of the superior gluteal nerve also were observed and treated conservatively.

CONCLUSIONS

Individualized custom cages using rapid prototyping and three-dimensional printing appeared to provide stable fixation and improved hip scores at short-term followup in this small, single-center series. As further improvements in the design and manufacturing process are made, future studies should evaluate larger patient groups for longer times, and, ideally, compare this approach with alternatives for these complex bone defects.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

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.

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.

Revision hip arthroplasty using impacted cancellous bone and cement: a long-term follow-up study

Acetabular bone deficiency is one of the many challenging problems encountered in revision hip arthroplasty. A variety of surgical options and techniques are available including impaction bone grafting. We present our long-term experience of 68 consecutive cups in 64 patients, using impacted cancellous bone grafting with bone cement. With a mean follow-up of 10.5 year (IQR 7.5-12.9) after revision surgery, three implants had undergone further revision. Three patients had subsequent femoral peri-prosthetic fractures, and none of these three required further acetabular revision. Survival of the acetabular components was 95.5 % for all causes and 100 % for aseptic loosening as the end point, with a further four patients showing radiographic, but asymptomatic loosening. A significant correlation was found between previous revision and re-revision (early failure) (p = 0.01) as well as progression of lytic lesion and re-revision (p = 0.01). The median Harris hip score at final follow-up was 79.5 (IQR 67.9-80.4). The use of impacted morcellised allograft bone with a cemented cup is an effective technique to achieve longevity and restoration of bone stock in acetabular revision arthroplasty. Our series has shown good clinical and radiological outcome with survivorship of the prosthesis exceeding 95 % at 10 years.

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.

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.

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.

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.

Acetabular revision surgery with the uncemented oblong BOFOR Cup--early to midterm results

INTRODUCTION

Failure of acetabular components frequently leads to bone loss with extensive elongated defects in the surrounding bone. In these cases the use of an oblong cup has been described as an option for acetabular reconstruction. We report the longest follow up results obtained with this implant to date.

MATERIALS AND METHODS

A prospective study was conducted to evaluate the results of the BOFOR oblong revision cup. Between 2001 and 2006, 15 acetabular revisions were performed for aseptic loosening of the acetabular cup. The acetabular defects were classified as type 2A to 3A, according to Paprosky's criteria. No allografts were used in any of the cases. The mean follow-up was 90 months (range 60-120 months).

RESULTS

Clinical assessment at follow-up showed a significantly improved mean Harris Hip Score from 39 points preoperatively to 84 points postoperatively and a mean Oxford Hip Score from 55 points preoperatively to 22 points postoperatively. Only one case underwent re-revision due to aseptic loosening in a patient with severe ankylosing spondylitis. There were no cases of dislocation or infection. One patient had a sciatic nerve neurapraxia. After an average follow up of 7.5 years, 93% of the investigated implants remained in-situ without further revision.

CONCLUSION

This study shows that the BOFOR cup provided good clinical results and showed satisfactory stability at early to midterm follow-up.

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.

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.