Acetabular Revision Surgery Research Articles

Results of the Novation CrowncupTM porous-coated uncemented acetabular component in total hip arthroplasty: a 10-year clinical and radiological assessment

The aim of this study was to evaluate theclinical, radiological, and survivorship results of a porous-coated uncemented acetabularcup (Novation Crowncup TM Exactech, Gainesville, Florida, USA) in patientsundergoing total hip arthroplasty at the mid to long term follow-up. Weprospectively analyzed 185 consecutivetotal hip replacements in 176 patients during 2009. All the patients received aNovation Crowncup™ uncemented cup. All surgeries were performed by one ofthe 4 joint replacement specialists. Several clinical and radiographic outcomemeasures were evaluated. There was no cupmigration recorded. Six cups (5.2%) had a thin (less than 1 mm) radiolucentline without signs of loosening or clinical manifestation, but under close followup. The wear was not significative at the end of the follow up. The mean HarrisHip Score increased from 45.7 (range = 28 to 65) preoperatively to 89.8 (range= 87 to 96) at the final follow-up. Subjectiveevaluation showed excellent results in 82.6%, good in 8.6%, fair in 5.9%, andpoor in 2.9% of the cases. Eight patients, 3 stems, and 5 cups (5% of the series)were revised, the survival of the series was 95% when the failure was the needfor additional acetabular or femoral revision surgery for any reason. If wedefine failure as the need for an acetabular revision for some reason, thesurvival was (97.5%). When we evaluated survival only for aseptic loosening ofthe cup at 10 years of follow-up, 98.4% of the implants survived. In our series,when we evaluated survival only for aseptic loosening of the cup at 10 years offollow-up, 98.4% of the implants survived. The Crowncup acetabular cup survivalrate was 97.5% including all causes of loosening and 95% including all causesfor revision at 10 years of follow-up. Level IV, Therapeutic Study.

Obtaining optimum screw placement for revision acetabular prostheses using the sciatic notch as reference

BackgroundThe use of transacetabular screws aid greatly in attaining acetabular component stability during acetabular revision surgery. There are, however, definite risks involved when using this technique. Inserting screws in the posterior superior safe zone has been advocated as a way to do this safely, but recent studies have shown that this does not hold true in conditions where acetabular anatomy is distorted or where the hip centre of rotation has moved. A method to insert these screws more accurately and safely is proposed. Questions/Purposes(1) Can using the greater sciatic notch as reference point when inserting transacetabular screws for revision acetabular cups ensure accurate and safe placement of screws? (2) How does this proposed new method compare with the posterior superior safe zone method? MethodsWith the use of an observational anatomic study we have developed a new method for the insertion of long transacetabular screws. This method uses the greater sciatic notch as a reference point. Our method was tested on 16 cadaveric hips (reamed to simulate revision conditions) and compared to the safe zone method. ResultsOur method achieved placement of 1–3 screws in the target area in all hips without penetration into the pelvis or sciatic notch. With the use of the safe zone only as reference the pelvis was penetrated 7 times and the sciatic notch twice. ConclusionUsing the greater sciatic notch as a reference guide enables the surgeon to engage a supportive bar of bone for one or more long home run screws whilst minimizing penetration of the pelvis and sciatic notch. In this study our method was superior to using the safe zone in isolation.

Early Term Radiographic Follow-Up of the Trident Tritanium Acetabular Component

INTRODUCTION: The purpose of this study was to evaluate the two year clinical and radiographic outcomes of patients undergoing a primary total hip arthroplasty (THA) using the Trident Tritanium primary Cup.
 
 METHODS: 197 patients who underwent a direct anterior THA using a Tritanium acetabular component between 2011 and 2015 were retrospectively reviewed by two surgeons from a single institution. The investigators, along with an independent physician, separately reviewed radiographs blinded to clinical data looking for radiolucent lines adjacent to the acetabular cup using the Charnley-DeLee zones. Clinical results were measured using acetabular revision surgery as an end point for failure. According to the American Academy of Orthopaedic Surgeons Levels of Evidence, this study was consistent with a Level III Therapeutic study.
 
 RESULTS: 101 (48.73%) subjects did not exhibit any radiolucent lines around the acetabular component. 53 (26.90%) subjects displayed radiolucency in only one zone. 27 (13.71%) subjects displayed radiolucency in two zones, and 16 (8.12%) displayed radiolucency in all three zones. Radiolucency was most prevalent in zone 1 at 2 years with 83 (42.13%) subjects displaying radiolucency. There were five (2.54%) acetabular failures within two years of the index surgery. Of those 5 subjects, 3 displayed radiolucency in 1 zone, 2 displayed radiolucency in >1 zone, and 2 displayed radiolucencies >1 mm.
 
 CONCLUSION: In our study, the Tritanium Cup demonstrated a 2.54% failure rate for aseptic loosening at 2 year follow-up. In addition, 48.73% of patients displayed a radiolucent line in at least one Charnley-DeLee zone. We also observed a progression of radiolucencies between the 6 month radiographs and the 2 year radiographs.

Clinical and radiological outcomes of acetabular revision surgery with trabecular titanium cups in Paprosky type II and III bone defects

BackgroundThis prospective study aims to evaluate the mid-term clinical outcomes and radiographic stability of two different types of cementless trabecular titanium acetabular components in total hip revision surgery.MethodsBetween December 2008 and February 2017, 104 cup revisions were performed using trabecular titanium revision cups. Mean age of patients was 70 (range 29–90; SD 11) years. The majority of revisions were performed for aseptic loosening (86 cases, 82.69%), but in all the other diagnoses (18 cases), a significant bone loss (Paprosky type II or III) was registered preoperatively. Bone defects were classified according to Paprosky acetabular classification. We observed 53 type II defects and 42 type III defects. Cups were chosen according to the type of defect.ResultsAverage follow-up was 91 (range 24–146) months. Mean Harris Hip Score (HHS) improved from 43.7 (range 25–70; SD 9) preoperatively to 84.4 (range 46–99; SD 7.56) at last follow-up. One (1.05%) cup showed radiographic radiolucent lines inferior to 2 mm and was clinically asymptomatic. One (1.05%) cup was loose and showed periacetabular allograft reabsorption. Kaplan–Meier survivorship was assessed to be 88.54% (95% CI 80.18–93.52%) at 71 months, with failure of the cup for any reason as the endpoint.ConclusionTrabecular titanium revision cups showed good clinical and radiographic results at mid-term follow-up in Paprosky type II and III bone defects.Level of evidenceLevel IV prospective case series

Additively manufactured space-filling meta-implants

The unprecedented properties of meta-biomaterials could pave the way for the development of life-lasting orthopedic implants. Here, we used non-auxetic meta-biomaterials to address the shortcomings of the current treatment options in acetabular revision surgery. Due to the severe bone deficiencies and poor bone quality, it can be very challenging to acquire adequate initial implant stability and long-term fixation. More advanced treatments, such as patient-specific implants, do guarantee the initial stability, but are formidably expensive and may eventually fail due to stress shielding. We, therefore, developed meta-implants furnished with a deformable porous outer layer. Upon implantation, this layer plastically deforms into the defects, thereby improving the initial stability and homogeneously stimulating the surrounding bone. We first studied the space-filling behavior of additively manufactured pure titanium lattices, based on six different unit cells, in a compression test complemented with full-field strain measurements. The diamond, body-centered cubic, and rhombic dodecahedron unit cells were eventually selected for the design of the deformable porous outer layer. Each design came in three different relative density profiles, namely maximum (MAX), functionally graded (FG), and minimum (MIN). After their compression in bone-mimicking molds with simulated acetabular defects, the space-filling behavior of the implants was evaluated using load-displacement curves, micro-CT images, and 3D reconstructions. The meta-implants with an FG diamond infill exhibited the most promising space-filling behavior. However, the required push-in forces exceed the impact forces currently applied in surgery. Future research should, therefore, focus on design optimization, to improve the space-filling behavior and to facilitate the implantation process for orthopedic surgeons. Statement of significanceIdeally, orthopedic implants would last for the entire lifetime of the patient. Unfortunately, they rarely do. Critically sized defects are a common sight in the revision of acetabular cups, and rather difficult to treat. The permanent deformation of lattice structures can be used to create shape-morphing implants that would fill up the defect site, and thereby restore the physiological loading conditions. Bending-dominated structures were incorporated in the porous outer layer of the space-filling meta-implants for their considerable lateral expansion in response to axial compression. A functionally graded density offered structural integrity at the joint while enhancing the deformability at the bone-implant interface. With the use of a more ductile metal, CP-Ti, these meta-implants could be deformed without strut failure.

Cup-on-cup technique: a reliable management solution for severe acetabular bone loss in revision total hip replacement.

The management of acetabular bone loss is a challenging problem in revision total hip arthroplasty (rTHA). The goals of treatment are a stable acetabular fixation, implant stability, and restoration of hip centre of rotation.This study aims to report clinical, radiological outcomes and complications at short-term to mid-term follow-up of the cup-on-cup technique in the management of severe acetabular bone loss in rTHA. We retrospectively reviewed the records of patient receiving rTHA performed with double porous tantalum cup technique in a single Joint Replacement Unit from 2014 to 2017. Objective and subjective clinical scores (Harris Hip Score, Oxford Hip Score, and visual analogue scale), radiological parameters (centre of rotation, leg-length discrepancy, heterotopic ossification, osseointegration, loosening and radiolucencies) and complications were recorded. We analysed the implant survival rate and periprosthetic joint infection rate. We included 9 patients (9 hips) with a mean follow-up of 35.3 ± 10.8 months. Functional scores showed a statistically significant improvement at the final follow-up (p < 0.01). All patients rated their surgery as satisfactory. The cup-on-cup construct demonstrated radiological osseointegration with the centre of rotation restoration and leg length discrepancy improvement. In 1 patient, periprosthetic joint infection was diagnosed and treated with suppressive antibiotic therapy. No patients underwent acetabular components revision surgery for any reason. Cup-on-cup technique is a valid and safe solution for reconstruction of selected Paprosky type IIIA and IIIB bone defects with satisfactory clinical and radiographic results at short-term and mid-term follow-up.

Clinical and radiological survivorship of the Thackray cross plate with rim reinforcement ring for cemented acetabular revision.

Acetabular component revision surgery can be a challenging task due to the encountered bone defects. Both cemented and uncemented techniques are described. We report on the survivorship of the Thackray cross plate with rim reinforcement ring for cemented acetabular revision. This is a retrospective case series of all patients treated with the implant with a minimum follow-up of 2years. Acetabular defects were characterized according to the Paprosky classification. Data on potential risk factors for failure of the construct as well as the Oxford Hip Score (OHS) were collected. Kaplan-Meier survival analysis with radiographic aseptic loosening or revision for aseptic loosening as the end point was performed. From 2000 to 2017, 35 revisions in 18 male and 17 female patients with an average age of 72years were included. Bone allograft was used in 26 cases and additional implants (medial or supero-lateral mesh) in 13. Seven patients have deceased and the fate of all revisions is known. At an average clinical follow-up of 9.7 (2.6 to 19.6) years, there were no further re-revisions for construct failure. Five hips have demonstrated radiological evidence of aseptic loosening. Radiologically loose components were associated with more severe grades of acetabular bone defects (Paprosky Type 3) (60% vs 3%, p = 0.006). Kaplan-Meier survival analysis demonstrates 79.8% overall survivorship at 7years. Survivorship for Type 2 defects was significantly higher compared to Type 3 (90% vs 0% at 7years, Logrank test p = 0.002, Cox proportional hazards p = 0.03). The final median OHS was 38 (12-48) and was not affected by component loosening. This is a cost-effective device that protects the underlying bone graft (81% complete remodeling) and prevents subsidence of the cemented cup (2mm on average). It should be used with caution in high-grade defects and perhaps not advised.

Do trabecular metal cups achieve better results when compared to hemispherical porous titanium cups in acetabular revision surgery?

Trabecular metal (TM) cups were introduced in order to achieve better ingrowth and stability of the cup in acetabular revision surgery. As their use has evolved over time, we have queried whether TM cups would improve results in terms of the rate of aseptic loosening when compared to historical uncemented porous titanium cups used in revision surgery for acetabular bone loss in Hospital La Paz (Madrid, Spain). We retrospectively reviewed 197 acetabular revisions performed between 1991 and 2015. Titanium cups were used in 81 cases and TM cups in 116. The mean follow-up was 8.1 years (range 1-15); 12.0 ± 7.8 for titanium group and 5.4 ± 3.1 for TM group. The most common reason for revision was aseptic loosening. A Kaplan-Meier analysis was used to determine the survival of the cup, with radiological failure and re-revision due to aseptic loosening as the endpoints. Cox multivariate regression analyses were performed to assess different risk factors for failure. 1 TM cup and 1 titanium cup were re-revised due to aseptic loosening (p = 0.61). Radiological cup loosening was observed in 4 TM cups and 2 titanium cups (p = 1.0). At 6 years, the probability of not having radiological cup loosening was 97.4% (95% CI, 93.9-100) for the titanium cups and 95.1% for the TM cups (95% CI, 90.1-99.9) (p = 0.59). Another 5 cups were re-revised due to dislocation. Hips with a greater Paprosky defect showed a higher risk of loosening (p < 0.05, hazard risk (HR) 3.04; 95% CI, 0.97-9.54). This study shows there was no significant difference in re-revision due to aseptic loosening or radiological loosening between titanium and TM cups in revision surgery for acetabular bone loss. Both types of cups demonstrate excellent results with a low failure rate and minimal complications.

How to proceed with asymptomatic modular dual taper hip stems in the case of acetabular revision.

How to proceed with a clinically asymptomatic modular Metha® Ti alloy stem with dual taper CoCr neck adapter in case of acetabular revision? To systematically answer this question the status of research and appropriate diagnostic methods in context to clinically symptomatic and asymptomatic dual taper stem-neck couplings has been evaluated based on a systematic literature review. A retrieval analysis of thirteen Metha® modular dual taper CoCr/Ti alloy hip stems has been performed and a rational decision making model as basis for a clinical recommendation was developed. From our observations we propose that in cases of acetabular revision, that for patients with a serum cobalt level of > 4 µg/L and a Co/Cr ratio > 3.6, the revision of the modular dual taper stem may be considered. Prior to acetabular revision surgery a systematic diagnostic evaluation should be executed, using specific tests such as serum metal (Co, Cr) ion analysis, plain antero-posterior and lateral radiographs and cross-sectional imaging modalities (Metal Artefact Reduction Sequence Magnetic Resonance Imaging). For an asymptomatic Metha® dual taper Ti alloy/CoCr stem-neck coupling at the stage of acetabular revision careful clinical decision making according to the proposed model should be followed and overreliance on any single examination should be avoided, considering the complete individual differential diagnosis and patient situation.

Acetabular defect classification and management : Revision arthroplasty of the acetabular cup based on 3-point fixation.

BackgroundThe purpose of this study was to provide a practicable and contemporary classification system that is reliable and pragmatic with respect to perioperative evaluation, planning, scientific comparison and analysis.Material and methodsThis was a retrospective study of 160 patients who underwent acetabular revision surgery after THR due to loosening of the acetabular cup. The assessment of the acetabular defect was based on intraoperative description of the bony configuration of the acetabulum as well as on standardized preoperative planning images (pelvic overview and axial view of the hip joint). Preoperative computed tomography (CT) was carried out in individual cases.ResultsAcetabular bone defects were classified into 4 types based on whether or not a 3-point fixation of the acetabular cup within the boundaries of the acetabular cavity was possible. Minor segmental defects or cup loosening without bone loss can be treated with standard hemispherical acetabular components. Bone loss can be filled with bone grafts and/or treated by the appropriate acetabular component in order to ensure stable anchorage. When conventional revision cups are no longer suitable a custom made partial pelvic replacement can be used.ConclusionThe proposed classification mainly relies on intraoperative findings which were confirmed by preoperative imaging in 154 cases out of 160 (96.25%); however, meticulous preoperative planning based on X‑ray radiographs must be carried out. In addition, a CT scan must be performed whenever type III or type IV defects are anticipated. Compared to the existing classification systems, we can state that our classification system is practicable and pragmatic and simplifies the assessment of bone defects.

Good implant survival after acetabular revision with extensive impaction bone grafting and uncemented components.

This single-centre observational study aimed to describe the results of extensive bone impaction grafting of the whole acetabular cavity in combination with an uncemented component in acetabular revisions performed in a standardized manner since 1993. Between 1993 and 2013, 370 patients with a median age of 72 years (interquartile range (IQR) 63 to 79 years) underwent acetabular revision surgery. Of these, 229 were more than ten years following surgery and 137 were more than 15 years. All revisions were performed with extensive use of morcellized allograft firmly impacted into the entire acetabular cavity, followed by insertion of an uncemented component with supplementary screw fixation. All types of reoperation were captured using review of radiographs and medical charts, combined with data from the local surgical register and the Swedish Hip Arthroplasty Register. Among patients with possible follow-up of ten and 15 years, 152 and 72 patients remained alive without revision of the acetabular component. The number of deaths was 61 and 50, respectively. Of those who died, six patients in each group had a reoperation performed before death. The number of patients with a reoperation was 22 for those with ten-year follow-up and 21 for those with 15 years of follow-up. The Kaplan-Meier implant survival rate for aseptic loosening among all 370 patients in the cohort was 96.3% (95% confidence interval (CI) 94.1 to 98.5) after ten years and 92.8% (95% CI 89.2 to 96.6) after 15 years. Extensive bone impaction grafting combined with uncemented revision components appears to be a reliable method with favourable long-term survival. This technique offers the advantage of bone stock restoration and disputes the long-standing perception that uncemented components require > 50% of host bone contact for successful implant survival. Cite this article: Bone Joint J 2020;102-B(2):198-204.

Révision isolée de la cupule acétabulaire par chirurgie assistée par ordinateur

BackgroundIn isolated acetabular revision surgery, surgeons must place the cup at an appropriate angle with various retained stem anteversion angles to prevent postoperative dislocation. For accurate acetabular cup position, various navigation systems have been used. Nevertheless, no publications have reported combined cup and stem anteversion and dislocation rates after isolated acetabular revision, especially comparing the use of navigation with manual implantation. Therefore we performed a retrospective comparative study to answer the following questions: 1) What is the combined anteversion after isolated acetabular revision with computed tomography-based navigation? 2) Does navigation improve the accuracy of cup angle and combined anteversion, 3) reduce dislocation rate, and 4) reduce operative time? HypothesisA navigation system makes combined anteversion near the target angle in isolated acetabular revision. Patients and methodsWe conducted a retrospective study of 32 hips in 24 patients who underwent isolated acetabular revision total hip arthroplasty using computed tomography-based navigation system. The control group comprised 8 hips in 8 patients who underwent the same procedure without navigation. ResultsIn the navigation group, average Widmer's combined anteversion was 39.0±8.7 (range, 25.3–56.6). Cup positions were 40.3±2.9 (range, 29.0–49.0) for radiographic abduction angle, 24.3±8.0 (range, 4.6–42.6) for radiographic anteversion. In the control group, Widmer's combined anteversion was 47.2±15.1 (range, 27.0–74.3, p=0.048). The average cup positions for radiographic abduction angle and anteversion were 36.7±8.9 (range, 24.5–54.9) and 29.1±7.3 (range, 17.2–38.8), respectively (p>0.05). Widmer's combined anteversion deviated from the target angle by a smaller amount in the navigation group than in the control group: errors in measurement of Widmer's combined anteversion were 7.2±5.1 (range, 0.74–19.6) in the navigation group and 13.9±11.1 (range, 3.6–37.3) in the control group (p=0.135). Postoperative dislocation occurred in none of the 32 hips (0%) in the navigation group and in one of the 8 hips (12.5%) in the control group (p=0.2). DiscussionUsing the navigation system, combined anteversion is made near the target angle in isolated acetabular revision surgery and more accurately than manual implantation. These results should be considered as preliminary since this is a limited cohort, but it brings new knowledge in navigation considering the very limited number of series using of navigation in isolated cup revision of total hip arthroplasty. In addition, this is the first study to investigate combined cup and stem anteversion in isolated acetabular revision. The use of CT-scan is helpful to diagnose error in stem anteversion and to adapt the orientation of the new cup. Level of evidenceIII, retrospective case control study.

Adapter sleeves are essential for ceramic heads in hip revision surgery

BackgroundRemoving a head during isolated acetabular revision surgery can cause damage to the stem taper surface from extraction tool contact. Implanting a ceramic head on the damaged stem taper might elevate the fracture risk, which can be mitigated with the use of titanium adapter sleeves. The aim of this study was to investigate whether the improved fracture strength of modern generation ceramic heads allows the direct implantation on damaged stem tapers without an adapter sleeve. MethodsFinite element models of taper junctions with and without adapter sleeve were generated. Different stem taper damages were modelled to investigate the influence on the ceramic head fracture load under axial compression. FindingsHeads without adapter sleeves exhibited slightly higher or equal fracture strengths compared with sleeved heads for most scenarios. However, a small metal elevation on the stem taper caused a drastic decrease of the fracture strength if no adapter sleeve was used (−96%). The sleeved head was not influenced by the metal elevation damage. InterpretationAdapter sleeves are essential to ensure patient safety and prosthesis longevity whenever implanting ceramic heads on used stem tapers.

Isolated acetabular revision with femoral stem retention using computed tomography-based navigation

BackgroundIn isolated acetabular revision surgery, surgeons must place the cup at an appropriate angle with various retained stem anteversion angles to prevent postoperative dislocation. For accurate acetabular cup position, various navigation systems have been used. Nevertheless, no publications have reported combined cup and stem anteversion and dislocation rates after isolated acetabular revision, especially comparing the use of navigation with manual implantation. Therefore we performed a retrospective comparative study to answer the following questions: (1) What is the combined anteversion after isolated acetabular revision with computed tomography-based navigation? (2) Does navigation improve the accuracy of cup angle and combined anteversion, (3) reduce dislocation rate, and (4) reduce operative time? HypothesisA navigation system makes combined anteversion near the target angle in isolated acetabular revision. Patients and methodsWe conducted a retrospective study of 32 hips in 24 patients who underwent isolated acetabular revision total hip arthroplasty using computed tomography-based navigation system. The control group comprised 8 hips in 8 patients who underwent the same procedure without navigation. ResultsIn the navigation group, average Widmer's combined anteversion was 39.0°±8.7° (range, 25.3°–56.6°). Cup positions were 40.3°±2.9° (range, 29.0°–49.0°) for radiographic abduction angle, 24.3°±8.0° (range, 4.6°–42.6°) for radiographic anteversion. In the control group, Widmer's combined anteversion was 47.2°±15.1° (range, 27.0°–74.3°, p=0.048). The average cup positions for radiographic abduction angle and anteversion were 36.7°±8.9° (range, 24.5°–54.9°) and 29.1°±7.3° (range, 17.2°–38.8°), respectively (p>0.05). Widmer's combined anteversion deviated from the target angle by a smaller amount in the navigation group than in the control group: errors in measurement of Widmer's combined anteversion were 7.2°±5.1° (range, 0.74°–19.6°) in the navigation group and 13.9°±11.1° (range, 3.6°–37.3°) in the control group (p=0.135). Postoperative dislocation occurred in none of the 32 hips (0%) in the navigation group and in one of the 8 hips (12.5%) in the control group (p=0.2). DiscussionUsing the navigation system, combined anteversion is made near the target angle in isolated acetabular revision surgery and more accurately than manual implantation. These results should be considered as preliminary since this is a limited cohort, but it brings new knowledge in navigation considering the very limited number of series using of navigation in isolated cup revision of total hip arthroplasty. In addition this is the first study to investigate combined cup and stem anteversion in isolated acetabular revision. The use of CT-scan is helpful to diagnose error in stem anteversion and to adapt the orientation of the new cup. Level of evidenceIII, Retrospective case control study.

Two stage cementation and screw augmentation of large acetabular defects in low demand patients: Early results and surgical technique

IntroductionThe reconstruction of large acetabular defects in revision hip arthroplasty represents a challenge to the surgeon and increases the complexity of the case. There are different options to overcome the problem of acetabular deficiency. In the elderly low demand patients, the main objective of revision surgery is to provide pain relief, allow immediate full weight bearing, and an early return to function. MethodsThis article presents our experience in acetabular revision surgery using a novel technique of two stage cementation and screw augmentation in low demand patients. We report on the surgical technique and present the early results in 10 patients. ResultsThere were 6 females and 4 males with average age of 83.8 years. Patients were followed up for an average of 18.1 months. All patients were pain free and full weight bearing at the time of the final follow up with radiographs showing maintenance of implant position. None of the patients underwent revision surgery and there were no radiographic signs of failure detected in the early follow-up period. ConclusionThis is a suitable technique in the management of large acetabular defects in revision hip arthroplasty, especially in the low demand patient population. It is a simple cost-effective technique that reduces the complexity of the acetabular revision, operative time, and morbidity associated with prolonged complex revision surgery.

Measuring bone defects for acetabular revision surgery for choosing an appropriate reconstruction strategy: A concept study on plastic models

BackgroundBone defects can be filled with autografts, allografts and artificial bone-materials. The aim of this study was to evaluate whether the digitization of known defect models with a navigation system is a reliable measurement method for estimating the size of a bone defect. MethodsSix preformed, cylindrical and cone-shaped defects on an artificial hip-bone were digitalized by six different observers. Reference volumes were gathered by measuring the depth of the defects, using an alginate impression material to fill out the defects and calculating the volumes from a CT scan. ResultsOne out of the six preformed defects showed a statistically significant difference between the digitalization and the calculation, four showed a significant difference between the digitalization and the mould as well as between the digitalization and the CT calculation. ConclusionsThis technique offers satisfactory results and consistent reproducibility when digitalizing big defects with relatively simple shape. Decreasing size and increasing complexity of the defects leads to more imprecise measurements.

A single centre study of 41 cases on the use of porous tantalum metal implants in acetabular revision surgery

BackgroundThis study aims at investigating cup survival of porous tantalum revision cups and identifies risk factors for failure.MethodsWe retrospectively reviewed 41 patients treated between 2010 and 2012. Main indications were aseptic loosening in 83% and two-stage exchange after periprosthetic joint infection in 17% of cases. Mean follow-up period was 72 months. Femoral megaprostheses were used in 13% of cases. Most defects were classified as Paprosky 3b (29%). Function was assessed using the Harris Hip score.ResultsAseptic cup survivorship was 80% at 104 months (95% Confidence Interval 67.4–92.4). Overall implant survival was 73%. Major bone loss defects (Paprosky types 2c to 3b) were associated with a significantly higher rate of failure than minor defects (P = 0.002). There were eight cases of aseptic loosening (19.5%) and two of infection (4.9%). Previous surgeries, indication for acetabular revision, patient-related risk factors and use of megaprostheses did not significantly influence implant survival. The Harris Hip Score improved from a median of 40 (Interquartile range 31–45) to 82 (interquartile range 65–88) postoperative (P < 0.0001).ConclusionsIn summary, the use of porous tantalum metal implants in acetabular revision surgery achieves good to excellent short- term and mid-term functional results and an acceptable complication rate relative to the extent of defect and previous surgery. However, one should be aware of potential limitations of the implants in addressing large defects and discontinuity.

Management of pelvic discontinuity in revision arthroplasty : Cementless acetabular cup with iliac stem and cranial strap.

Pelvic discontinuity causes severe destruction of the acetabular bony walls and is particularly difficult to manage. This article reports the short-term results and complications encountered in the management of loosening of the acetabular cup with pelvic discontinuity using an acetabular cup with an intramedullary iliac stem combined with an extramedullary iliac plate. As part of this monocentric retrospective case analysis all patients who underwent acetabular revision surgery after THR due to loosening of the acetabular cup with pelvic discontinuity in this clinic from January 2016 to June 2017 were identified (n = 16). All patients underwent routine clinical and radiological follow-up. In addition, the Harris hip score (HHS) and the Western Ontario and McMaster Universities osteoarthritis index (WOMAC) were evaluated as part of a1-year follow-up. All patients were treated with an acetabular revision cup of appropriate size with intramedullary iliac stem combined with an anatomical extramedullary iliac plate. On clinical follow-up at 1 year (median follow-up time 14.5 ± 3.3months), the average HHS was 69.3 ± 14.1 and the average WOMAC was 79.3 ± 11.7. Complications were registered in 7 out of the 16patients whereby 1 showed aseptic loosening of the revision cup, dislocations were reported in 4cases and infections in 2cases. In the case of the two patients with infections aGirdlestone resection arthroplasty had to be performed. The overall complications and postoperative outcome in revision surgery after THR reported in the literature were compared to the results of this study. Compared to the results of salvage procedures using large or bipolar heads and Girdlestone resection arthroplasty, satisfactory results were obtained using the acetabular cup with an intramedullary iliac stem combined with an extramedullary iliac plate.

Burch-Schneider ring associated with morselized bone allografts, survival and clinical outcomes after acetabular revision surgery

Introduction and objectivesAcetabular revision surgery is a challenge due to the appearance of bone defects that make primary fixation of implants difficult when extracting loosened components. Reinforcement rings, such as Burch-Schneider (BS), have been shown to be allies in moderate or severe bone defects. The objective of the study is to evaluate the results and survival of these types of implants in acetabular revision surgery in the medium follow-up. Material and methodsRetrospective study on a cohort of 64 patients (67 replacements) with BS rings associated with morselized bone allografts in a 2 years minimum follow-up. Data were collected regarding clinical outcomes, graft incorporation, implant mobilization, survival and complications. ResultsThe mean follow-up was 5.06 years (R=2.2–12). The Merle scale improved from 8 points to 15 points at the end of follow-up (p<.0001) with 76.11% of good or excellent results. Reproduction of the anatomical centre of rotation was associated with a better result (p<.05). There was total or subtotal incorporation of the bone allograft in 97% of the patients, although this did not prevent a significant migration of the ring according to Gill criteria in 6 cases. We observed an overall survival of the implant for any cause of 93.4% at 5 years, and 84.6% at 10 years. ConclusionsThe BS reinforcement ring shows good results in the medium and long term enabling anatomical reconstruction in revision surgery as well as replacement of the bone stock. These results are also comparable and are a vast improvement on other rings.

Anillo de Burch-Schneider asociado a injerto óseo triturado, supervivencia y resultados clínicos en revisión acetabular

Introduction and objectivesAcetabular revision surgery is a challenge due to the appearance of bone defects that make primary fixation of implants difficult when extracting loosened components. Reinforcement rings, such as Burch-Schneider (BS), have been shown to be allies in moderate or severe bone defects. The objective of the study is to evaluate the results and survival of these types of implants in acetabular revision surgery in the medium follow-up. Material and methodsRetrospective study on a cohort of 64 patients (67 replacements) with BS rings associated with morselized bone allografts in a 2 years minimum follow-up. Data were collected regarding clinical outcomes, graft incorporation, implant mobilization, survival and complications. ResultsThe mean follow-up was 5.06 years (R=2.2-12). The Merle scale improved from 8 points to 15 points at the end of follow-up (P<.0001) with 76.11% of good or excellent results. Reproduction of the anatomical centre of rotation was associated with a better result (P<.05). There was total or subtotal incorporation of the bone allograft in 97% of the patients, although this did not prevent a significant migration of the ring according to Gill criteria in 6 cases. We observed an overall survival of the implant for any cause of 93.4% at 5 years, and 84.6% at 10 years. ConclusionsThe BS reinforcement ring shows good results in the medium and long term enabling anatomical reconstruction in revision surgery as well as replacement of the bone stock. These results are also comparable and are a vast improvement on other rings.