Survivorship of monoblock trabecular metal cups in primary THA : midterm results

Specific approach to total hip arthroplasty in patients with childhood hip disorders sequelae

Hip arthroplasty in patients with a history of paediatric hip disorders presents a significant challenge for orthopaedic surgeons. These patients are typically younger and have greater functional demands. Therefore, achieving optimal biomechanical conditions is crucial, involving placement of the acetabulum at the ideal centre of rotation and securing a stable femoral component with good offset to preserve abductor muscle function and restore leg length. The altered anatomy in these cases makes total hip arthroplasty more complex, necessitating thorough preoperative imaging and an individualised surgical approach. Various techniques may be employed to optimise biomechanical outcomes. We propose a modified lateral hip approach, offering exceptional visualisation of the acetabulum and femur while preserving the continuity of the abductor muscles without requiring trochanteric osteotomy. To achieve the most biomechanically advantageous acetabular position, cotyloplasty is our preferred method.

Trabecular Metal Augments During Complex Primary Total Hip Arthroplasty

Background

Trabecular metal augments (TMAs) have been extensively used in revision total hip arthroplasty (THA) to address acetabular bone defects. However, limited data exists regarding TMA utilization during primary THA. This study aims to assess the clinical and radiographic outcomes of TMAs used during primary THA.

Methods

A single-institution retrospective case series of primary THA patients treated with TMA between 2010 and 2019 was performed. Patient demographics, complications, and revisions were recorded. Cup position, center of rotation, leg length, and radiolucent lines were assessed radiographically. The Kaplan-Meier method was used to compute implant survivorship.

Results

Twenty-six patients (30 hips) were included with average age of 52.6 ± 15.3 years (range: 22-78) and mean follow-up of 4.1 ± 2.1 years (range: 2.0-8.9). Most TMAs were indicated for developmental dysplasia of the hip (n = 18; 60.0%). On average, hip center of rotation was lowered 1.5 ± 1.3 cm and lateralized 1.2 ± 1.5 cm, while leg length and global offset were increased by 2.4 ± 1.2 cm and 0.4 ± 1.0 cm, respectively. At final follow-up, 3 hips (10.0%) required revision: one (3.3%) for aseptic loosening and 2 (6.7%) for instability. No patients had progressive radiolucent lines at final follow-up. Five-year survival with aseptic loosening and all-cause revision as endpoints was 100% (95% confidence interval: 90.0%-100.0%) and 92.1% (95% confidence interval: 81.3%-100.0%), respectively. One patient required revision for aseptic loosening after the 5-year mark.

Conclusions

Trabecular metal augmentation during primary THA demonstrates satisfactory early to mid-term outcomes. TMA is a viable option for complex primary THA when bone loss is encountered or secondary support is required.

Level of Evidence

Level IV.

Titanium alloy cannulated screws and biodegradable magnesium alloy bionic cannulated screws for treatment of femoral neck fractures: a finite element analysis

Background

Cannulated screws (CS) are one of the most widely used treatments for femoral neck fracture, however, associated with high rate of complications. In this study, we designed a new type of cannulated screws called degradable magnesium alloy bionic cannulated screws (DMBCS) and our aim was to compare the biomechanical properties of DMBCS, the traditionally used titanium alloy bionic cannulated screws (TBCS) and titanium alloy cannulated screws (TTCS).

Methods

A proximal femur model was established based on CT data of a lower extremity from a voluntary healthy man. Garden type III femoral neck fracture was constructed and fixed with DMBCS, TBCS, and TTCS, respectively. Biomechanical effect which three type of CS models have on femoral neck fracture was evaluated and compared using von Mises stress distribution and displacement.

Results

In the normal model, the maximum stress value of cortical bone and cancellous bone was 76.18 and 6.82 MPa, and the maximum displacement was 5.52 mm. Under 3 different fracture healing status, the stress peak value of the cortical bone and cancellous bone in the DMBCS fixation model was lower than that in the TTCS and TBCS fixation, while the maximum displacement of DMBCS fixation model was slightly higher than that of TTCS and TBCS fixation models. As the fracture heals, stress peak value of the screws and cortical bone of intact models are decreasing, while stress peak value of cancellous bone is increasing initially and then decreasing.

Conclusions

The DMBCS exhibits the superior biomechanical performance than TTCS and TBCS, whose fixation model is closest to the normal model in stress distribution. DMBCS is expected to reduce the rates of post-operative complications with traditional internal fixation and provide practical guidance for the structural design of CS for clinical applications.

Peptide-Enriched Silk Fibroin Sponge and Trabecular Titanium Composites to Enhance Bone Ingrowth of Prosthetic Implants in an Ovine Model of Bone Gaps

Osteoarthritis frequently requires arthroplasty. Cementless implants are widely used in clinics to replace damaged cartilage or missing bone tissue. In cementless arthroplasty, the risk of aseptic loosening strictly depends on implant stability and bone–implant interface, which are fundamental to guarantee the long-term success of the implant. Ameliorating the features of prosthetic materials, including their porosity and/or geometry, and identifying osteoconductive and/or osteoinductive coatings of implant surfaces are the main strategies to enhance the bone-implant contact surface area. Herein, the development of a novel composite consisting in the association of macro-porous trabecular titanium with silk fibroin (SF) sponges enriched with anionic fibroin-derived polypeptides is described. This composite is applied to improve early bone ingrowth into the implant mesh in a sheep model of bone defects. The composite enables to nucleate carbonated hydroxyapatite and accelerates the osteoblastic differentiation of resident cells, inducing an outward bone growth, a feature that can be particularly relevant when applying these implants in the case of poor osseointegration. Moreover, the osteoconductive properties of peptide-enriched SF sponges support an inward bone deposition from the native bone towards the implants. This technology can be exploited to improve the biological functionality of various prosthetic materials in terms of early bone fixation and prevention of aseptic loosening in prosthetic surgery.

Traditional and bionic dynamic hip screw fixation for the treatment of intertrochanteric fracture: a finite element analysis

PURPOSE

The dynamic hip screw (DHS) is widely used for fixing intertrochanteric femur fractures. A porous bionic DHS was developed recently to avoid the stress concentration and risk of post-operative complications associated with titanium alloy DHSs. The purpose of this study was to compare the effects of traditional titanium alloy, bionic titanium alloy, and bionic magnesium alloy DHS fixation for treatment of intertrochanteric fractures using finite element analysis.

METHODS

A three-dimensional model of the proximal femur was established by human computed tomography images. An intertrochanteric fracture was created on the model, which was fixed using traditional and porous bionic DHS, respectively. The von Mises stress, maximum principal stress, and minimum principal stress were calculated to evaluate the effect of bone ingrowth on stress distribution of the proximal femur after fixation.

RESULTS

Stress concentration of the bionic DHS model was lower compared with traditional DHS fixation models. The von Mises stress, maximum principal stress, and minimum principal stress distributions of bionic magnesium alloy DHS models improved, along with simulation of the bone healing process and magnesium alloy degeneration, assumed to biodegrade completely 12 months post-operatively. The distribution of maximum principal stress in the secondary tension zone of the bionic DHS model was close to the intact bone. In the minimum principal stress, the region of minimum stress value less than - 10 MPa was significantly improved compared with traditional DHS models.

CONCLUSION

The bionic magnesium alloy DHS implant can improve the stress distribution of fractured bone close to that of intact bone while reducing the risk of post-operative complications associated with traditional internal fixations.

Porous Tantalum and Titanium in Orthopedics: A Review

Porous metal is metal with special porous structures, which can offer high biocompatibility and low Young's modulus to satisfy the need for orthopedic applications. Titanium and tantalum are the most widely used porous metals in orthopedics due to their excellent biomechanical properties and biocompatibility. Porous titanium and tantalum have been studied and applied for a long history until now. Here in this review, various manufacturing methods of titanium and tantalum porous metals are introduced. Application of these porous metals in different parts of the body are summarized, and strengths and weaknesses of these porous metal implants in clinical practice are discussed frankly for future improvement from the viewpoint of orthopedic surgeons. Then according to the requirements from clinics, progress in research for clinical use is illustrated in four aspects. Various creative designs of microporous and functionally gradient structure, surface modification, and functional compound systems of porous metal are exhibited as reference for future research. Finally, the directions of orthopedic porous metal development were proposed from the clinical view based on the rapid progress of additive manufacturing. Controllable design of both macroscopic anatomical bionic shape and microscopic functional bionic gradient porous metal, which could meet the rigorous mechanical demand of bone reconstruction, should be developed as the focus. The modification of a porous metal surface and construction of a functional porous metal compound system, empowering stronger cell proliferation and antimicrobial and antineoplastic property to the porous metal implant, also should be taken into consideration.

Tritanium Acetabular Cup in Revision Hip Replacement: A Six to Ten Years of Follow-Up Study

BACKGROUND

The use of highly porous acetabular components has shown to produce good results in revision acetabular surgery. Their surface characteristics enhance initial fixation and bone ingrowth which are prerequisites for adequate osseointegration. The purpose of this study is to analyze the mid-term to long-term survival, clinical and radiological outcomes using the Tritanium cup (Stryker, Mahwah, NJ) in revision hip surgery.

METHODS

This is a retrospective review of all patients who underwent acetabular revision surgery using "Tritanium revision cup" between April 2007 and November 2010 at our institution. Sixty-two patients were included with a mean age of 67.5 years (32-86). According to Paprosky classification, 10 patients had type I defect, 8 had type IIA, 27 had type IIB, 7 had type IIC, and 10 suffered from type IIIA defect. A Kaplan-Meier analysis was used to determine the survival of the cup. Functional outcomes were assessed using Oxford Hip Score. Plain radiographs were performed to assess implant fixation and osseointegration.

RESULTS

The acetabular cup aseptic survivorship was 98.4% at a mean follow-up of 87.6 months. The mean Oxford Hip Score improved from 14.5 (3-31) preoperatively to 38.5 (12-48) at the final follow-up. Two cups were revised (3.2%): 1 for aseptic loosening and 1 for infection.

CONCLUSION

Tritanium revision acetabular cup has shown excellent mid-term to long-term clinical and radiographic results with low failure rate and minimal complications. Longer term follow-up would be of value to assess the ongoing survival of this implant construct.

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.

Survivorship of a Porous Tantalum Monoblock Acetabular Component in Primary Hip Arthroplasty With a Mean Follow-Up of 18 Years

BACKGROUND

The use of porous tantalum for the acetabular component in primary total hip arthroplasty (THA) has demonstrated excellent short-term and midterm results. However, long-term data are scarce. The purpose of this prospective study is to report the long-term clinical and radiologic outcome following use of an uncemented porous tantalum acetabular component in primary THA with a minimum follow-up of 17.5 years, in a previously studied cohort of patients.

METHODS

We prospectively followed 128 consecutive primary THAs in 140 patients, between November 1997 and June 1999. A press-fit porous tantalum monoblock acetabular component was used in all cases. All patients were followed clinically and radiographically for a mean of 18.1 years (range, 17.5-19 years).

RESULTS

Mean age of patients at the time of operation was 60.4 years. Harris hip score, Oxford hip score, and range of motion were dramatically improved in all cases (P < .001). At last follow-up, all cups were radiographically stable with no evidence of migration, gross polyethylene wear, progressive radiolucencies, osteolytic lesions, or acetabular fractures. The survivorship with reoperation for any reason as end point was 92.8% and the survivorship for aseptic loosening as an end point was 100%.

CONCLUSION

The porous tantalum monoblock cup in primary THA demonstrated excellent clinical and radiographic outcomes with no failures because of aseptic loosening at a mean follow-up of 18.1 years.

Retrieval Analysis of Porous Titanium Glenoid Posts: An Evaluation of Osteointegration

Glenoid component loosening is a commonly encountered complication of total shoulder replacements. Therefore, focus has been placed on glenoid fixation. Porous metal implants, which promote biological fixation through osteointegration, have provided an uncemented alternative to the traditional cemented implant. In this explantation study, the authors examined the bone ingrowth and ongrowth of a specific porous titanium glenoid peg. Six explanted polyethylene glenoid components with porous titanium-coated central pegs were identified in the authors' implant retrieval program via retrospective review. The retrieved implants were sectioned into thirds with a precision saw and underwent scanning electron microscopy for analysis of bone ingrowth and ongrowth. Bone ingrowth was calculated as bone volume fraction, or the fraction of available pore space filled with bone, whereas ongrowth was the percentage of the perimeter of the implant covered with bone. The 6 total shoulders included in the study were revised at an average of 16.3 months (range, 5-48 months) for instability secondary to subscapularis rupture, subscapularis rupture plus infection, or other rotator cuff tear. All glenoid components were grossly stable on retrieval and had an average of 23% bone ingrowth and 54% ongrowth. The preliminary results show that osteointegration into a porous titanium ingrowth glenoid component is possible in the short-term, even in the presence of an unfavorable biomechanical environment, such as instability and rotator cuff dysfunction, as well as infection. [Orthopedics. 2017; 40(4):e703-e707.].

Advances in hip arthroplasty surgery: what is justified?

Total hip arthroplasty (THA) surgery has shown dramatic changes in terms of increased number of procedures and of technical development in recent years. It has been described as “the operation of the 20^th century” for the excellent results, the high satisfaction of the patients and the improvement of the quality of life.

A lot of variations have been introduced over the last few decades in THA especially in terms of indications (both in younger and older patients), techniques and devices (approaches, tissue preservation, biomaterials and industrial finishing), per-operative management (blood loss and pain control) and post-operative protocols (the so called “fast track” surgery). Looking at all these advances the emerging question is: have all of them been justified both in terms of improvement of the results for the patients and of the cost/benefit ratio from an economical point of view?

The purpose of this paper is to critically analyse the advantages and the disadvantages of the theoretically proposed “advances in hip arthroplasty” and attempt to understand which are justified of such “advances” nowadays, based on the international and the European perspective with a focus on the author’s personal clinical experience.

Cite this article: EFORT Open Rev 2017;2. DOI: 10.1302/2058-5241.2.170008. Originally published online at www.efortopenreviews.org

Use of Oversized Highly Porous Cups in Acetabular Revision

This study assessed the efficacy of highly porous cups in revision total hip arthroplasty for Paprosky types II and III acetabular bone loss. The authors identified 33 acetabular revisions in 29 patients from a prospective database (66% type III, 7 with pelvic dissociation). Initial stability was achieved with interference fit between the anterior inferior iliac spine, pubis, and ischium with cups that were 2 to 4 mm larger than the reamed acetabulum and augmented with multiple screw fixations without allograft or wedges. At mean follow-up of 6 years (range, 2.7-7.7 years) after revision surgery, no dislocation, infection, or reoperation was noted. Mean satisfaction score was 6±3.2. Mean anteversion and abduction angles were 43°±4.6° and 21.5°±4.4°, respectively. Complications included limp in 13% of patients, wound issues in 10%, and heterotopic ossification in 17%. Osteointegration was seen in all cups, without any migration. Mean overall osteointegration, based on the average percentage of the 3 zones in both views, was 55%±21% (range, 25%-95%). The most osteointegration was seen in zone I (superior) and zone VI (posterior), and the least osseointegration was seen in zone II (medial) and zone IV (anterior). This method can provide reproducible results in acetabular revision arthroplasty.

Long-Term Clinical and Radiographic Outcomes of Porous Tantalum Monoblock Acetabular Component in Primary Hip Arthroplasty: A Minimum of 15-Year Follow-Up

BACKGROUND

The porous tantalum monoblock cup has demonstrated excellent short-term and midterm clinical and radiographic outcomes in primary THA, but longer follow-up is necessary to confirm the durability of these results into the second decade. The purpose of this study is to report the clinical and radiographic outcomes for this monoblock cup with a minimum 15-year follow-up.

METHODS

From June 1998 to December 1999, 61 consecutive patients (63 hips) underwent primary THA with a tantalum monoblock acetabular component. All patients were followed clinically and radiographically for a minimum of 15 years. At a mean of 15.6 years (range, 15-16 years) of follow-up, 5 patients had died, and 4 had been lost to follow-up, leaving 52 patients (54 hips) for analysis. The underlying diagnosis that led to the primary THA was primary osteoarthritis in 43 hips, avascular necrosis in 4, developmental hip dysplasia in 3, rheumatoid arthritis in 3 and post-traumatic osteoarthritis in 1.

RESULTS

One cup was revised for deep infection; at surgery, the cup showed osseointegration. At a mean follow-up of 15.6 years (range, 15-16 years), the survivorship with cup revision for aseptic loosening as end point was 100%. There was no radiographic evidence of loosening, migration, or gross polyethylene wear at last follow-up. The mean Harris Hip Scores improved from 47 points preoperatively to 94 points.

CONCLUSION

The porous tantalum monoblock cup in primary THA demonstrated excellent clinical and radiographic outcomes with no failures because of osteolysis or loosening at a minimum follow-up of 15 years.

The Absence of Hydroxyapatite Coating on Cementless Acetabular Components Does Not Affect Long-Term Survivorship in Total Hip Arthroplasty

BACKGROUND

Hydroxyapatite (HA) has been applied to joint prostheses as a bioactive coating to prolong their durability. However, HA benefits for cup survival in total hip arthroplasty (THA) remain controversial. In this study, we compared the survival of cups with and without HA coating during a minimum follow-up of 18 years.

METHODS

In total, 183 THA cases in 163 patients were analyzed, including 73 cups with HA coating (HA(+) group) and 110 without HA coating (HA(-) group); otherwise, the cups had identical titanium-sprayed rough surfaces and were fixed with screws. In both groups, the same conventional polyethylene liners were applied. Zirconia and alumina ceramic heads were used in the HA(+) and HA(-) groups, respectively. We retrospectively analyzed cup survival based on cup revision for any reason or aseptic loosening as end points.

RESULTS

In total, 7 and 8 revisions were performed in the HA(-) and HA(+) groups with survival rates of 86.3% and 90.1%, respectively. Among them, 3 cups in the HA(-) group and 1 cup in the HA(+) group were revised for aseptic loosening in 20 years (survival rates 94.1% and 98.7%, respectively). No significant difference was detected in cup survival rates between the groups based on both end points. There were no stem revisions during the observation period.

CONCLUSION

The results suggested that HA coating did not have either beneficial or adverse effects on the long-term cup survival in primary cementless THA.

No differences in early results of a hybrid glenoid compared with a pegged implant

BACKGROUND

Glenoid component loosening after total shoulder arthroplasty is one of the most common causes of failure. A hybrid glenoid that uses peripherally cemented pegs and a central press-fit post may improve implant longevity.

QUESTIONS/PURPOSES

We asked, compared with polyethylene pegged glenoid implants, do hybrid glenoid implants with a titanium post provide (1) better ingrowth with fewer radiolucencies, (2) better outcome and pain scores, and (3) lower risk of complications and revisions?

METHODS

Between 2009 and 2010, 126 patients underwent primary total shoulder arthroplasty for osteoarthritis. Patients were included in this retrospective study if they consented for inclusion in a shoulder arthroplasty registry, had complete baseline and 2-year data, and had complete radiographs. Eighty-three (67%) were available at an average followup of 3.2 years (range, 24-45 months). Forty received a conventional all-polyethylene pegged glenoid and 43 received a hybrid component. During the period in question, four of the participating surgeons used only one implant, and four used only the other; there was one high-volume surgeon in each of the study groups. Radiographs were taken at the 2-year followup and analyzed for radiolucent lines. CT scans were obtained randomly for 10 patients with hybrid glenoid implants to assess bone ongrowth. American Shoulder and Elbow Surgeons score, VAS score, complications and revisions were recorded.

RESULTS

At final followup, radiolucent lines between the two study groups were not different (hybrid, 1.0 ± 0.4; pegged, 1.6 ± 0.3; mean difference, 0.6; 95% CI, 0.85-1.72; p = 0.323). Final VAS pain scores were not different (hybrid, 1.2 ± 0.2; pegged, 1.5 ± 0.3; p = 0.056). Change in American Shoulder and Elbow Surgeons scores were not different (hybrid, 33.7 ± 7.3; pegged, 35.5 ± 8.2; p = 0.283). There were no differences in complication risk (hybrid, one of 43 [2.3%]; pegged, three of 40 [7.5%]; relative risk, 2.3; 95% CI, 0.82-3.12; p = 0.061).

CONCLUSIONS

With the numbers available and at early followup, there were no differences between the hybrid and pegged glenoids in terms of fixation, functional outcome, pain scores, and complications. CT scans confirmed bone ongrowth on the porous titanium post in a small subcohort of patients. Further studies are needed to determine how this new implant will perform with time. Until then, its use should be initiated with caution.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Performance of Porous Tantalum vs. Titanium Cup in Total Hip Arthroplasty: Randomized Trial with Minimum 10-Year Follow-Up

Porous tantalum monoblock cups have been proposed to improve survivorship of cementless primary THA. However, there are few direct comparative trials to established implants such as porous-coated titanium cups. 113 patients were randomized into two groups according to the cup: a porous tantalum monoblock cup (TM) or a porous-coated titanium monoblock cup (control). At a mean of 12 years after THA, no implants migrated in both groups. Two TM patients (4%) and 13 control patients (33%) presented with radiolucency around the cup (P<0.001). In the control group, 1 cup (2%) was revised for aseptic loosening. At 12 years post-implantation, porous tantalum monoblock cups demonstrated 100% survivorship, and significantly less radiolucency as compared to porous-coated titanium monoblock cups.

Mid-term clinical and radiographic outcomes of porous tantalum modular acetabular components for hip dysplasia

It is still challenging to perform successful cementless cup fixation during total hip arthroplasty for hip dysplasia. In this multicenter study we evaluated the clinical results of porous tantalum modular acetabular cups (TM cups) in 45 dysplastic hips with a mean follow-up period of 9.8 years. The mean Japanese Orthopaedic Association hip score improved from 48.2 preoperatively to 92.1 at the most recent follow-up. All of the cups were radiographically stable with no evidence of progressive radiolucencies or osteolysis regardless of bone grafting. Sixteen hips with bone grafts showed the integration of grafted bone without any radiolucencies. There were no revisions of TM cups. The use of TM cups for dysplastic hips provided satisfactory 10-year clinical and radiographic results.

Preliminary analysis on the MD-4® plasma-sprayed titanium acetabular component

Objectives

To evaluate the short-term performance of a type of implant manufactured in Brazil.

Methods

This study analyzed a cohort of 60 patients who underwent implantation of MD-4^® acetabular components during primary hip arthroplasty procedures performed between January 1, 2010, and August 1, 2012. The patients were studied retrospectively with regard to clinical behavior, stability and radiological osseointegration. The patients were followed up for a minimum of 12 months and a maximum of 42 months (mean: 27) and were evaluated by means of the Harris Hip Score, SF-36 questionnaire and serial conventional radiographs.

Results

All the components were radiologically stable, without evidence of migration or progressive radiolucency lines. On average, the Harris Hip Score evolved from 36.1 to 92.1 (p < 0.001) and the SF-36 showed significant increases in all its domains (p < 0.001). No differences were observed among patients with osteoarthrosis, osteonecrosis, hip dysplasia or other conditions.

Conclusions

The short-term results showed clinical and radiological signs of stability and osseointegration of the implants, which may represent a predictive factor regarding medium-term survival of this acetabular component.

Current concept in dysplastic hip arthroplasty: Techniques for acetabular and femoral reconstruction

Adult patients with developmental dysplasia of the hip develop secondary osteoarthritis and eventually end up with total hip arthroplasty (THA) at younger age. Because of altered anatomy of dysplastic hips, THA in these patients represents technically demanding procedure. Distorted anatomy of the acetabulum and proximal femur together with conjoined leg length discrepancy present major challenges during performing THA in patients with developmental dysplasia of the hip. In addition, most patients are at younger age, therefore, soft tissue balance is of great importance (especially the need to preserve the continuity of abductors) to maximise postoperative functional result. In this paper we present a variety of surgical techniques available for THA in dysplastic hips, their advantages and disadvantages. For acetabular reconstruction following techniques are described: Standard metal augments (prefabricated), Custom made acetabular augments (3D printing), Roof reconstruction with vascularized fibula, Roof reconstruction with pedicled iliac graft, Roof reconstruction with autologous bone graft, Roof reconstruction with homologous bone graft, Roof reconstruction with auto/homologous spongious bone, Reinforcement ring with the hook in combination with autologous graft augmentation, Cranial positioning of the acetabulum, Medial protrusion technique (cotyloplasty) with chisel, Medial protrusion technique (cotyloplasty) with reaming, Cotyloplasty without spongioplasty. For femoral reconstruction following techniques were described: Distraction with external fixator, Femoral shortening through a modified lateral approach, Transtrochanteric osteotomies, Paavilainen osteotomy, Lesser trochanter osteotomy, Double-chevron osteotomy, Subtrochanteric osteotomies, Diaphyseal osteotomies, Distal femoral osteotomies. At the end we present author’s treatment method of choice: for acetabulum we perform cotyloplasty leaving only paper-thin medial wall, which we break during acetabular cup impacting. For femoral side first we peel of all rotators and posterior part of gluteus medius and vastus lateralis from greater trochanter on the very thin flake of bone. This method allows us to adequately shorten proximal femoral stump, with possibility of additional resection of proximal femur. Furthermore, several advantages and disadvantages of this procedure are also discussed.

Do the cup surface properties influence the initial stability?

This project tests the relationship between the acetabular cup surface characteristics and their initial stability by comparing uncemented (Trabecular Metal (TM) and Trilogy) and cemented polyethylene shells. We hypothesised that different surface properties of uncemented cups will influence the cup stability. Mounted directly onto host bone, TM and cemented cups were significantly more stable than Trilogy cups (P < 0.01), with minimal difference between TM and cemented cups (P > 0.1). On 100% graft bed, there was marginal difference between all three cup types (P > 0.1). Incremental cavitary and segmental defects resulted in reducing stability, with cemented cups being minimally more stable (P > 0.1). TM cups possess satisfactory initial stability in bone graft constructs. This study demonstrates that TM shells are marginally less stable than cemented cups in the absence of significant host bone contact.

Osteonecrosis of the femoral head

Symptomatic hip osteonecrosis is a disabling condition with a poorly understood aetiology and pathogenesis. Numerous treatment options for hip osteonecrosis are described, which include non-operative management and joint preserving procedures, as well as total hip replacement (THR). Non-operative or joint preserving treatment may improve outcomes when an early diagnosis is made before the lesion has become too large or there is radiographic evidence of femoral head collapse. The presence of a crescent sign, femoral head flattening, and acetabular involvement indicate a more advanced-stage disease in which joint preserving options are less effective than THR. Since many patients present after disease progression, primary THR is often the only reliable treatment option available. Prior to the 1990s, outcomes of THR for osteonecrosis were poor. However, according to recent reports and systemic reviews, it is encouraging that with the introduction of newer ceramic and/or highly cross-linked polyethylene bearings as well as highly-porous fixation interfaces, THR appears to be a reliable option in the management of end-stage arthritis following hip osteonecrosis in this historically difficult to treat patient population.

Cite this article: Bone Joint J 2013;95-B, Supple A:46–50.

Acetabular reconstruction in patients with low and high dislocation: 20- to 32-year survival of an impaction grafting technique (named cotyloplasty)

We report the results at a mean of 24.3 years (20 to 32) of 61 previously reported consecutive total hip replacements carried out on 44 patients with severe congenital hip disease, performed with reconstruction of the acetabulum with an impaction grafting technique known as cotyloplasty. The mean age of the patients at operation was 46.7 years (23 to 68) and all were women. The patients were followed post-operatively for a mean of 24.3 years (20 to 32), using the Merle d'Aubigné and Postel scoring system as modified by Charnley, and with serial radiographs. At the time of the latest follow-up, 28 acetabular components had been revised because of aseptic loosening at a mean of 15.9 years (6 to 26), and one at 40 days after surgery because of repeated dislocations. The overall survival rate for aseptic failure of the acetabular component at ten years was 93.1% (95% confidence interval (CI) 86.5 to 96.7) when 53 hips were at risk, and at 23 years was 56.1% (95% CI 49.4 to 62.8), when 22 hips remained at risk. These long-term results are considered satisfactory for the reconstruction of an acetabulum presenting with inadequate bone stock and circumferential segmental defects.

Excellent results of primary THA using a highly porous titanium cup

Cementless acetabular cups for primary total hip arthroplasty have had excellent results, with failure rates typically less than 5% at up to 10-year follow-up. Tritanium is a 3-dimensional metal interface that has been used for porous biological fixation. The purpose of this study was to review the clinical and radiographic results of the use of Tritanium cups (Stryker Orthopaedics, Mahwah, New Jersey) for primary total hip arthroplasty. Two hundred eighty-eight total hip arthroplasties performed using a porous titanium acetabular cup in 252 patients between 2008 and 2010 were reviewed. One hundred thirty-three men and 119 women with a mean age of 58 years (range, 18-88 years) were included. Mean follow-up was 36 months (range, 24-56 months). Outcomes evaluated were implant survivorship, Harris Hip Score, complications, and radiographic outcomes. At final follow-up, no cup failures had occurred. Mean Harris Hip Score improved from 53 points (range, 33-82 points) preoperatively to 91 points (range, 64-100 points) postoperatively. One complication occurred; a 64-year-old woman with recurrent postoperative effusions underwent hip exploration and required abductor mechanism repair. On radiologic evaluation, no signs existed of progressive radiolucencies or changes in cup position. The survivorship of the Tritanium cup and the low complication rate is comparable with previous studies using other porous-metal prostheses. Longer follow-up study is needed and assessment of the results of using this implant in the revision setting is important.

Smoking may be a harbinger of early failure with ultraporous metal acetabular reconstruction

BACKGROUND

Smoking is considered a risk factor for surgical complications in total hip arthroplasty (THA) and has been linked to a higher rate of aseptic loosening in uncemented acetabular components. Acetabular reconstruction with newer ultraporous metals in both complex primary and revision THA has increased survivorship but it is unclear whether smoking affects survival of these implants.

QUESTIONS/PURPOSES

We reviewed our early experience with THA using ultraporous acetabular components to assess the incidence and etiology of early failure and examine if any preoperative variables, including smoking, related to failure.

METHODS

We used ultraporous acetabular components in 498 patients (534 hips), beginning with one case each in 1999 and 2004, 17 in 2005, and the majority from 2006 through March 2010. There were 159 complex primary and 375 revision cases. Of these patients, 17% were smokers (averaging 35 pack-years), 31% previous smokers (averaging 29 pack-years), 41% nonsmokers, and 1% unknown. Failure modes possibly related to smoking were infection, aseptic loosening, or periacetabular fracture and unrelated were dislocation and implant breakage. Minimum followup was 1 month (average, 32 months; range, 1-78 months).

RESULTS

There were 34 cup failures (6%): 17 infections, 14 aseptic loosening, and one each liner breakage, dislocation, and periacetabular fracture. The failure rate (uncontrolled for potentially confounding variables) was 10% in both current (9 of 89) and prior smokers (17 of 167) and 3% in nonsmokers 8 of 271).

CONCLUSION

With ultraporous metal technology in complex primary and revision THA, smoking, both past and current, may be a risk factor for early failure.

LEVEL OF EVIDENCE

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

Ten- to 15-year clinical and radiographic results for a compression molded monoblock elliptical acetabular component

The aim of this study was to report the long-term results from a previously published midterm follow-up of a titanium monoblock, elliptical acetabular component. A total of 258 primary total hip arthroplasties (212 patients) with a monoblock, acetabular component were followed up for a mean period of 11.1 years (10-15). Average yearly wear rate was 0.08 mm/y (0.0009-0.32). Acetabular radiolucencies were present in 6 hips (2.4%); all were nonprogressive and present in acetabular zone I. Acetabular osteolysis was present in 5 patients (5 hips, 1.9%); all cups were stable. Four acetabular components were revised, 3 because of recurrent instability. No acetabular components were revised for polyethylene wear or dissociation, acetabular osteolysis, loosening, or deep infection. This monoblock design demonstrates excellent long-term survival and low rate of osteolysis.

Osseous integration in porous tantalum implants

Porous tantalum is a biomaterial that was recently introduced in orthopedics in order to overcome problems related to implant loosening. It is found to have osteoconductive, and possibly, osteoinductive properties hence useful in difficult cases with severe bone defects. So, it is of great interest to shed light on the mechanisms through which this material leads to new bone formation, after being implanted. Porous tantalum is biologically relatively inert, with restricted bonding capacity to the bone is restricted. In order to overcome this obstacle, it undergoes thermal processing in an alkaline environment. This process leads to extensive hydroxyapatite formation on its surface, and thus, to better integration of porous tantalum implants. Apart from this, new bone tissue formation occurs inside the pores of the porous tantalum after its implantation and this new bone retains the characteristics of the normal bone, that is, bone remodeling and Haversian systems formation. This finding is enhanced by the observation that porous tantalum is an appropriate substrate for osteoblast adherence, proliferation, and differentiation. Furthermore, the finding that osteoblasts derived from old women (> 60 years old) and cultivated on porous tantalum may grow faster than osteoblasts taken from younger women (< 45 years old) and cultivated on other substrates, can partially explain porous tantalum's good performance in cases of patients with severe bone defects. In conclusion, porous tantalum's chemical and mechanical properties are those that probably define the already noticed good performance of this material. However, further research is needed to totally clarify the mechanisms.

Survival of uncemented acetabular monoblock cups: evaluation of 210 hips in the Swedish Hip Arthroplasty Register

BACKGROUND AND PURPOSE

Monoblock acetabular cups represent a subtype of uncemented cups with the polyethylene liner molded into a metal shell, thus eliminating-or at least minimizing-potential backside wear. We hypothesized that the use of monoblock cups could reduce the incidence of osteolysis and aseptic loosening, and thus improve survival compared to modular designs.

PATIENTS AND METHODS

We identified all 210 primary total hip arthroplasty (THA) procedures in the Swedish Hip Arthroplasty Register that used uncemented monoblock cups during the period 1999-2010. Kaplan-Meier and Cox regression analyses with adjustment for age, sex, and other variables were used to calculate survival rates and adjusted hazard ratios (HRs) of the revision risk for any reason. 1,130 modular cups, inserted during the same time period, were used as a control group.

RESULTS

There was a nearly equal sex distribution in both groups. Median age at the index operation was 47 years in the monoblock group and 56 years in the control group (p < 0.001). The cumulative 5-year survival with any revision as the endpoint was 95% (95% CI: 91-98) for monoblock cups and 97% (CI: 96-98) for modular cups (p = 0.6). The adjusted HR for revision of monoblock cups compared to modular cups was 2 (CI: 0.8-6; p = 0.1). The use of 28-mm prosthesis heads rather than 22-mm heads reduced the risk of cup revision (HR = 0.2, CI: 0.1-0.5; p = 0.001).

INTERPRETATION

Both cups showed good medium-term survival rates. There was no statistically significant difference in revision risk between the cup designs. Further review of the current patient population is warranted to determine the long-term durability and risk of revision of monoblock cup designs.

Clinical and radiographic evaluation of total hip arthroplasties using porous tantalum modular acetabular components: 5-year follow-up of clinical trial

OBJECTIVES

Porous tantalum is a biomaterial newly applied for artificial joints. We present here 5-years follow-up report of a multicenter clinical trial of total hip arthroplasties (THA) with porous tantalum modular acetabular component (modular PTC).

METHODS

Study participants received 82 hips in 79 cases, with 61.2 months follow-up on average. Age at operation was 60.9 years. Clinical results were evaluated using Merle d'Aubigne Postel score. Presence of implant loosening, periacetabular radiolucency, osteolysis, and gap filling were examined for radiographic results.

RESULTS

Merle d'Aubigne Postel score improved from 10.0 to 16.4 points. All PTC were radiographically stable, with no evidence of progressive radiolucencies. Average polyethylene wear rate was 0.004 mm/year, with no periacetabular osteolysis. Fifteen hips (18.3%) showed a gap >1 mm; however, all showed bone filling within 12 months. PTC with oversized reaming was significantly less likely to have a gap. No implant failure was noted related to modularity. Resulting survival rate of modular PTC was 100% at 5 years.

CONCLUSIONS

Modular PTC showed excellent results at 5-years of follow-up. Some hips showed periacetabular gaps, which were filled with bone within 1 year. Further follow-up was needed to determine long-term efficacy.

Congenital hip disease in adults: terminology, classification, pre-operative planning and management

This paper reviews the current knowledge relating to the management of adult patients with congenital hip disease. Orthopaedic surgeons who treat these patients with a total hip replacement should be familiar with the arguments concerning its terminology, be able to recognise the different anatomical abnormalities and to undertake thorough pre-operative planning in order to replace the hip using an appropriate surgical technique and the correct implants and be able to anticipate the clinical outcome and the complications.

Uncemented and cemented primary total hip arthroplasty in the Swedish Hip Arthroplasty Register

BACKGROUND AND PURPOSE

Since the introduction of total hip arthroplasty (THA) in Sweden, both components have most commonly been cemented. A decade ago the frequency of uncemented fixation started to increase, and this change in practice has continued. We therefore analyzed implant survival of cemented and uncemented THA, and whether the modes of failure differ between the two methods of fixation.

PATIENTS AND METHODS

All patients registered in the Swedish Hip Arthroplasty Register between 1992 and 2007 who received either totally cemented or totally uncemented THA were identified (n = 170,413). Kaplan-Meier survival analysis with revision of any component, and for any reason, as the endpoints was performed. Cox regression models were used to calculate risk ratios (RRs) for revision for various reasons, adjusted for sex, age, and primary diagnosis.

RESULTS

Revision-free 10-year survival of uncemented THA was lower than that of cemented THA (85% vs. 94%, p < 0.001). No age or diagnosis groups benefited from the use of uncemented fixation. Cox regression analysis confirmed that uncemented THA had a higher risk of revision for any reason (RR = 1.5, 95% CI: 1.4-1.6) and for aseptic loosening (RR = 1.5, CI: 1.3-1.6). Uncemented cup components had a higher risk of cup revision due to aseptic loosening (RR = 1.8, CI: 1.6-2.0), whereas uncemented stem components had a lower risk of stem revision due to aseptic loosening (RR = 0.4, CI: 0.3-0.5) when compared to cemented components. Uncemented stems were more frequently revised due to periprosthetic fracture during the first 2 postoperative years than cemented stems (RR = 8, CI: 5-14). The 5 most common uncemented cups had no increased risk of revision for any reason when compared with the 5 most commonly used cemented cups (RR = 0.9, CI: 0.6-1.1). There was no significant difference in the risk of revision due to infection between cemented and uncemented THA.

INTERPRETATION

Survival of uncemented THA is inferior to that of cemented THA, and this appears to be mainly related to poorer performance of uncemented cups. Uncemented stems perform better than cemented stems; however, unrecognized intraoperative femoral fractures may be an important reason for early failure of uncemented stems. The risk of revision of the most common uncemented cup designs is similar to that of cemented cups, indicating that some of the problems with uncemented cup fixation may have been solved.

[Acetabular defect reconstruction in revision surgery of the hip. Autologous, homologous or metal?]

The treatment of periprosthetic bone defects of the acetabulum is a therapeutic challenge in hip revision surgery. The aims are the biological reconstruction of osseous acetabular defects and the restoration of a load-bearing acetabular bone stock as well as restoring the physiological joint biomechanics and achieving primary and load-stable fixation of the revision graft in the vital pelvic bone. The biological reconstruction of the acetabular bone stock should include what is referred to as "down-grading" of the acetabular defect situation in case a repeat revision procedure becomes necessary.Nowadays, a large variety of grafts and reconstruction procedures are available for the reconstruction of acetabular defects. The choice of suitable materials (osseous or metallic) for the restoration of a load-bearing acetabular bone stock is currently the subject of controversial discussion.This article reviews the various options for the reconstruction of acetabular bone defects taking into consideration the current findings in the scientific literature.

Trabecular Metal cups for acetabular defects with 50% or less host bone contact

Acetabular component revision in the context of large contained bone defects with less than 50% host bone contact traditionally have been treated with roof reinforcement or antiprotrusio cages. Trabecular Metal cups (Zimmer, Inc, Warsaw, IN) may offer a reasonable treatment alternative. We evaluated the clinical and radiographic outcome of this mode of treatment. We prospectively followed 53 hip revision acetabular arthroplasty procedures performed with Trabecular Metal cups for contained defects with 50% or less contact with native bone. All patients were clinically and radiographically evaluated for evidence of loosening or failure. Minimum followup was 24 months (average, 45 months; range, 24-71 months). Contact with host bone ranged from 0% to 50% (average, 19%). The mean postoperative Merle d'Aubigne-Postel score was 10.6 (range, 1-12), with a mean improvement of 5.2 (range, -4-10) compared to the preoperative score. Two failed cups (4%) were revised. Two additional cups (4%) had radiographic evidence of probable loosening. Complications included four dislocations and one sciatic nerve palsy. The data suggest treatment of cavitary defects with less than 50% host bone contact using Trabecular Metal cups, without structural support by augments or structural bone grafts, is a reasonable option.

Case reports: Tantalum debris dispersion during revision of a tibial component for TKA

Porous tantalum nonmodular tibial components for TKA were introduced in 1999. We revised three well-fixed tantalum tibial trays. For removal, we used osteotomes and revision oscillating saw blades. Removal of the components was laborious and resulted in generation of abundant tantalum debris that seeded the periarticular soft tissues despite meticulous protection with gauze. The retained metallic debris that is visible on postoperative radiographs has the potential for generation of third-body wear. We alert the orthopaedic community about this phenomenon and recommend minimizing the use of motorized revision instruments for removal of trabecular metal implants.