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

The use of porous titanium acetabular augments in primary total hip arthroplasty for hip dysplasia or rapidly destructive coxopathy

Aims

This study aimed to evaluate the efficacy of porous titanium acetabular augments in primary total hip arthroplasty (THA) for reconstruction of superolateral acetabular bone defects in patients with Crowe II or higher classes of developmental dysplasia of the hip (DDH) or rapidly destructive coxopathy (RDC).

Methods

We conducted a retrospective evaluation of 27 patients (30 hips) who underwent primary THA using cementless cups and porous titanium acetabular augments. The follow-up periods ranged from two to 11 years, with a mean of 5.0 years. The cohort included 22 females (24 hips) and five males (six hips), with a mean age of 67 years (45 to 83) at the time of surgery.

Results

At the final follow-up, there was no radiological evidence of loosening or radiolucency around the cups and augments, indicating successful biological fixation in all cases. Clinically, there was a significant improvement in the Western Ontario and McMaster Universities Osteoarthritis Index score, which improved from a mean of 39.1 (SD 14.7) preoperatively to 5.1 (SD 6.4) postoperatively.

Conclusion

The use of cementless cups and porous acetabular titanium augments in primary THA for patients with DDH and RDC can lead to considerable clinical improvements and reliable biological fixation, suggesting their potential as a viable solution for managing challenging acetabular defects in these conditions.

3D-printed Personalized Porous Acetabular Component to Reconstruct Extensive Acetabular Bone Defects in Primary Hip Arthroplasty

OBJECTIVE

Management of extensive acetabular bone defects in total hip arthroplasty (THA) remains challenging. This study aims to investigate the feasibility and preliminary outcomes of 3D-printed personalized porous acetabular components for the reconstruction of acetabular defects in primary THA.

METHODS

This retrospective study involved seven patients who received 3D-printed acetabular components in primary THA between July 2018 and March 2021. Preoperatively, acetabular bone defects were evaluated by referencing the Paprosky classification. There were two "Paprosky type IIIA" defects and five "Paprosky type IIIB" defects. The acetabular components were custom-made for each patient to reconstruct the extensive acetabular defects. The hip function was assessed according to the Harris hip score (HHS). Clinical and radiographic outcomes were assessed.

RESULTS

The average follow-up period was 40 months, ranging from 26 to 57 months. There were no patients lost to follow-up. The HHS improved from 44 (range: 33-53) before the operation to 88 (range: 79-93) at the final follow-up. Postoperative X-rays showed that the 3D-printed personalized components were properly fitted with the acetabulum. The average center of rotation (COR) discrepancy was 2.3 mm horizontally and 2.1 mm vertically, respectively. Tomosynthesis-Shimadzu metal artifact reduction technology images showed that the implant was in close contact with the host bone. Moreover, no complications were observed during the follow-up period, including loosening, dislocation, or component protrusion.

CONCLUSION

The implantation of 3D-printed personalized acetabular components showed accurate reconstruction, stable mechanical support, and favorable function at short-term follow-up. This may be a viable alternative method for reconstructing extensive acetabular defects in THA.

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.

Survivorship and functional outcome of a cemented acetabular component with bulk roof autograft for severe acetabular dysplasia: 12- to 23-year follow-up

AIMS

Primary aim was to determine survival of a cemented acetabular component with bulk roof autograft with a minimum of 12 years follow-up. The secondary aim was to determine the clinical outcome.

METHODS

A cohort of 62 consecutive patients (74 hips) undergoing cemented total hip arthroplasty with acetabular bulk roof autograft for acetabular dysplasia were retrospectively identified. The group consisted of 57 female patients (67 hips) and 5 male patients (7 hips) with a mean age at operation of 45 years. No patient was lost to follow-up, however 9 patients died had during the study period. The Oxford Hip Score (OHS), Forgotten Joint Score (FJS), EuroQol 5-Dimensional Score (EQ-5D), Short Form (SF-12) physical score and patient satisfaction were used to assess clinical outcome for patients with a surviving prosthesis.

RESULTS

The median follow-up was 16.6 (13.4-19.1) years. 6 revisions were performed during the follow-up period, all of which were due to aseptic loosening of the acetabular component. The all-cause Kaplan Meier survival rate for the acetabular component was 99% at 10 years, 95% at 15 years and 83% at 20 years. Neither age, gender, femoral osteotomy or polyethylene (UHMW vs. cross-linked) were significant predictors of aseptic revision of the acetabular component. There were no case of graft resorption and all grafts were radiologically incorporated. 45 patients were available for functional assessment at a mean follow-up of 18.2 years. The mean OHS was 37.8, FJS was 55.7, EQ5D was 0.73, and SF-12 physical component was 43.2. No patient was dissatisfied, with 2 patients reporting a neutral satisfaction, 7 stating they were satisfied and the remaining 36 were very satisfied.

CONCLUSIONS

A cemented acetabular component with bulk roof autograft for dysplasia offers excellent survival with good to excellent functional outcome with high patient satisfaction in the medium- to long-term.

Early results of a high friction surface coated uncemented socket in revision hip arthroplasty

BACKGROUND

Revision hip arthroplasty with high friction trabecular metal sockets has resulted in good medium-term results. Many manufacturers have therefore introduced higher friction coatings to their implants to meet a growing demand for similar implants. The Pinnacle Gription was introduced in 2007 as an evolution of the standard Pinnacle socket. This study aimed to assess the early results of this socket in a revision setting.

METHODS

Between August 2009 and December 2016, the Gription socket was used in 146 revision hip replacements. The mean age was 63 (19-88) years. Defects were classified as Paprosky Grade 2 in 71(2A [28], 2B [19], 2C [24]) and grade 3 in 20 (3A [18], 3B [2]). Bearing combinations were ceramic-on-ceramic in 23, metal-on-polyethylene in 71, ceramic-on-polyethylene in 52. Screws were used in 112 cases, impaction bone grafting in 34 and metal augments in 1 case. Radiographs were analysed for progressive radiolucent lines and migration.

RESULTS

Mean follow-up was 43.5 (range 25-62) months. There were 6 re-revisions (2 for deep infection, 2 for recurrent dislocation and 2 for aseptic loosening). None of the other cases had evidence of socket migration or progressive radiolucent lines. There were no intraoperative or postoperative periprosthetic fractures. The crude survivorship for all-cause failure was 95.8% and the survivorship for aseptic loosening was 98.6%. at 43.5 months follow-up.

CONCLUSIONS

This is the largest reported series of Gription socket use in revision arthroplasty and demonstrates encouraging early results. We therefore advocate the continued cautious use of this implant.

Influence of outer geometry on primary stability for uncemented acetabular shells in developmental dysplasia of the hip

Excellent primary stability of uncemented acetabular shells is essential to obtain successful clinical outcomes. However, in the case of developmental dysplasia of the hip (DDH), aseptic loosening may be induced by instability due to a decrease of the contact area between the acetabular shell and host bone. The aim of this study was to assess the primary stability of two commercially-available acetabular shells, hemispherical and hemielliptical, in normal and DDH models. Synthetic bone was reamed using appropriate surgical reamers for each reaming condition (normal acetabular model). The normal acetabular model was also cut diagonally at 40° to create a dysplasia model. Stability of the acetabular components was evaluated by the lever-out test. In the normal acetabular model conditions, the maximum primary stabilities of hemispherical and hemielliptical shells were observed in the 1-mm under- and 1-mm over-reamed conditions, respectively, and the resulting stabilities were comparable. The lateral defect in the dysplasia model had an adverse effect on the primary stabilities of the two designs. The lever-out moment of the hemielliptical acetabular shell was 1.4 times greater than that of the hemispherical acetabular shell in the dysplasia model. The hemispherical shell is useful for the normal acetabular condition, and the hemielliptical shell for the severe dysplasia condition, in the context of primary stability.

A new 3D printing porous trabecular titanium metal acetabular cup for primary total hip arthroplasty: a minimum 2-year follow-up of 92 consecutive patients

Background

Aseptic cup loosening is still one of the main reasons leading to acetabular cup failures. 3D printing porous trabecular titanium metal acetabular cup may provide good initial stability and secondary fixation because of its highly interconnected, porous structure. Few large sample studies have reported the clinical outcomes of electron beam melting (EBM) porous titanium acetabular cup in Chinese population.

Methods

We retrospectively collected and analyzed the clinical data of a total of 92 consecutive patients between January 2013 and November 2017, with an average follow-up of 48.2 ± 3.6 months. Clinical outcomes included Harris Hip Score (HHS), the Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index, satisfaction rate, and cup survival rate were evaluated. Radiographic assessments were conducted to evaluate osteointegration.

Results

HHS scores improved significantly while the WOMAC score decreased significantly at the latest follow-up (p < 0.001). The satisfaction rate (prevalence of satisfied or very satisfied) was 91.3%. No acetabular cup failures occurred. Radiolucent lines appeared in 15 cases (18 hips) and disappeared in 6 months. No cup loosening signs found until the last follow-up. The overall survival rate of implantation is 99.1% (cup survival rate 100%).

Conclusion

The new EBM-produced 3D ACT™ cup demonstrated us its favorable short- to mid-term clinical outcomes in Chinese THA patients. It can provide high acetabular cup survival rate, great clinical improvements and excellent biological fixation. Further investigations are needed to confirm its long-term outcomes.

Fixation Stability of Uncemented Acetabular Cups With Respect to Different Bone Defect Sizes

BACKGROUND

In total hip arthroplasty, acetabular press-fit cups require a proper bone stock for sufficient primary implant fixation. The presence of acetabular bone defects compromises the primary fixation stability of acetabular press-fit cups. The aim of the present study is to determine the fixation stability of a cementless acetabular cup regarding standardized bone defects in an experimental setup.

METHODS

An acetabular defect model was developed and transferred to a biomechanical cup-block model. The lack of superior cup coverage was divided into 4 stages of superior rim loss (33%, 50%, 67%, and 83%) in the anterior-posterior direction and into 4 stages of mediolateral wall absence (11%, 22%, 33%, and 50%). This resulted in 11 different defect cavities, which were compared to the intact cavity in push-in and lever-out tests of one press-fit cup design (56 mm outer diameter). Thereby, push-in force, lever-out moment, lever-out angle, and interface stiffness were determined.

RESULTS

The determined lever-out moments range from 15.53 ± 1.38 Nm (intact cavity) to 1.37 ± 0.54 Nm (83%/50% defect). Smaller defects (33%/11%, 33%/22%, and 50%/11%) reduce the lever-out moments by an average of 33.9% ± 2.8%.

CONCLUSION

The lack of mediolateral acetabular coverage of 50% was assessed as critical for cementless cup fixation, whereby the contact zone between implant and bone in the defect is lost. A lack of 20% to 30% mediolateral coverage appears to be acceptable for press-fit cup fixation in the presence of primary stability. A defect of 50%/50% was identified as the threshold for using additional fixation methods.

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.

Changes in acetabular component alignment due to screw fixation in patients with hip dysplasia

INTRODUCTION

Adequate initial stability of the acetabular cup is essential for total hip arthroplasty (THA). However, changes in the alignment of the acetabular component caused by screw fixation are concerning in patients with inadequate bone stock. This study aimed to investigate the effects of screw fixation on the alignment of the acetabular component in THA patients with hip dysplasia.

METHODS

We retrospectively examined 256 hips (range 28-87 years) that underwent THA using a navigation system. Patients were divided into 2 groups based on the presence or absence of changes in the alignment of the intraoperative acetabular cup, and univariate and multivariate analyses were performed to identify factors that were predictive of changes in acetabular component alignment after screw fixation in 2 dimensions: inclination and anteversion.

RESULTS

Screw fixation led to a mean change in inclination of 1.6° (range 0-10°) and a mean change in anteversion of 1.4° (range 0-14°). The Crowe classification, the presence of bone cysts, and the use of an inferior quadrant screw were identified as factors that correlated with acetabular cup alignment changes in inclination (odds ratios, 6.01, 5.94 and 0.03, respectively). Only the Crowe classification was identified as a factor that correlated with intraoperative alignment changes in anteversion (odds ratio, 2.08).

CONCLUSIONS

Screw fixation altered the acetabular cup alignment. The inclination changes were related to the extent of the dysplasia, and the risk was reduced when the inferior quadrant screw was used. Surgeons should use caution during screw fixation in THAs performed on severely dysplastic hips.

Preoperative Planning for Total Hip Arthroplasty for Neglected Developmental Dysplasia of the Hip

Developmental dysplasia of the hip (DDH) is accompanied by morphological alterations on both the acetabular and the femoral side. Total hip arthroplasty (THA) provides effective treatment in cases of neglected DDH but requires elaborate preoperative planning. To determine the morphological changes resulting from the dysplasia, the anatomic acetabular position, the height of the femur head dislocation, the height of the femur head dislocation, and the combined anteversion must all be established. In addition, a vital and complicated process of strategizing leg length balance must be conducted in cases of severe DDH. Each type of leg length discrepancy (LLD), including bony and functional and anatomical LLD, should be evaluated in the context of the presence or absence of a fixed pelvic tilt. Moreover, with severe unilateral dislocated hips, a more inferior change in the original rotational center of the hip must be accounted for. Due to these multiple morphological changes, the accurate size of the prosthesis and the cup position are difficult to predict. In comparison with other methods, CT scan‐based 3‐dimensional templating provides the best accuracy. Despite the presence of anatomic alterations, various types of acetabular and femoral prostheses have been developed to treat hip dysplasia. Both cemented and cementless cups are used in DDH cases. In DDH accompanied by insufficient acetabular bone stock, a cemented cup combined with bone graft provides a reliable treatment. Monoblock stems can be used when the combined anteversion is less than 55°, and a modular stem system when this parameter is greater than 55°. Customized stems can be designed for DDH coupled with severe proximal femoral distortion. A ceramic‐on‐ceramic bearing is considered optimal for young DDH patients.

[Challenges of primary hip arthroplasty with high hip dislocation]

BACKGROUND

Endoprosthetic care of high hip dislocation is a surgical challenge. The hip anatomy is greatly altered in these patients, including a rather flat and small acetabulum with impaired bone quality and a relevant chance of a bony defect of the acetabular roof. Additionally, the front coverage and in some cases even the dorsal coverage of the hip are missing. The proximal femur is characterized with an increased antetorsion, a coxa valga position and an enlarged greater trochanter. The medullary cavity is narrowed, the offset is reduced, and the absolut leg length can be enlarged. Further anatomic variations can have been caused by previous surgeries.

AIM OF THE TREATMENT

The goal of the endoprosthetic care is the re-creation of a hip with an anatomic center of rotation, an anatomic offset and equal leg length.

TREATMENT

This can be achieved by a medial shift of the acetabular cup. An acetabular osteotomy including central cancellous bone graft or a bony graft to reinforce the acetabular roof might be necessary. In cases in which an anatomic acetabular cup placement is not possible, a more cranial placement can be done. Further strategies that are essential in several cases are shortening or re-orientation osteotomies of the femur, reaming of the medullary cavity and correct implant selection. Additionally, thorough soft tissue management is of main importance. Generally, the surgery should be well prepared preoperatively.

Radiolucency around highly porous sockets and hydroxyapatite-coated porous sockets in total hip arthroplasty for hip dysplasia

Studies over the past decade have reported that the use of highly porous sockets in total hip arthroplasty (THA) results in osseointegration and long-term implant stability. However, some reports have raised concerns regarding radiographic evidence of poor osseointegration with features of fibrous tissue ingrowth. The purpose of this study was to compare clinical and radiographic assessments of highly porous sockets with those of hydroxyapatite (HA)-coated porous sockets in THA for hip dysplasia (DDH) at least 1 year after surgery. A total of 127 patients (136 hips) were recruited for the study. Of these, 94 patients (101 hips) received highly porous sockets with clustered screws, while 33 patients (35 hips) received HA-coated porous sockets with clustered screws. There was no difference in clinical outcomes between the two types of sockets. All HA-coated porous sockets were radiographically stable, without radiolucent lines. Fifteen hips had radiolucent lines in two or three DeLee and Charnley zones, accompanied by sclerotic lines along the circumferences of the highly porous sockets. A significant difference in the height of the preoperative osteophyte of the anterior acetabular wall was observed between 86 hips with one or no radiolucent lines and 15 hips with two or three radiolucent lines. In cases of DDH with atrophic bone remodeling pattern, highly porous sockets with multiple screws may be used, while HA-coated porous sockets with clustered screws result in better sealing of the bone–component interface.

Unrecoverable bi-products of drilling titanium alloy and tantalum metal implants: a pilot study

BACKGROUND

Trabecular metal implants with a porous architecture that allows for the incorporation of bone into the implant during healing are gaining popularity in alloplastic revision procedures. The bi-products of drilling titanium alloy (Ti) and tantalum (Ta) implants have not been previously assessed.

METHODS

Four holes were drilled in each of 2 spatially porous trabecular implants, one Ta and the other Ti alloy (Ti-6Al-7Nb), for this pilot in vitro study. The particles were flushed out with a continuous flow of saline. The particles' weight and the volume were then measured using a Radwag XA 110/2X (USA) laboratory balance. The total volume of the obtained metal fines was measured by titration using a 10 mm³ measurement system.

RESULTS

A cobalt carbide bit was used since the holes could not be made with a standard bone drill. Each Ti and Ta implant lost 1.26 g and 2.48 g of mass, respectively. The volume of free particles recovered after each stage was 280 mm³ and 149 mm³, respectively. Approximately 0.6% of the total implant mass was not recovered after drilling (roughly 2% of the mass of the particles created by drilling), despite the use of 5 µm filters.

CONCLUSIONS

It is technically difficult to drill holes in Ti and Ta implants using standard surgical tools. The drilling process creates a considerable amount of metal particles, which cannot be recovered despite intensive flushing. This may have an adverse influence on the bio-functionality (survival) of the endoprosthesis and present deleterious systemic consequences.

The Use of Porous Tantalum Augments for the Reconstruction of Acetabular Defect in Primary Total Hip Arthroplasty

BACKGROUND

Given the lack of studies of acetabular defect reconstruction in primary total hip arthroplasty (THA) using tantalum augments, this study aims to evaluate clinical and radiographic results for treatment with tantalum augments to reconstruct acetabular defects in primary THA.

METHODS

We retrospectively reviewed 19 patients (19 hips) with acetabular defects who underwent primary THA using tantalum augments, with a minimum follow-up of 2 years. Clinical, radiographic, and surgical data were retrospectively evaluated.

RESULTS

Mean follow-up was 5.1 years (range 2.5-7.6). Harris Hip Score improved from 35.8 (range 19-56) preoperatively to 85.3 (63-98) at last follow-up (P < .01). Oxford Hip Score, University of California Los Angeles activity scale, and Short Form-12 score also improved significantly from presurgery to last follow-up. Mean operation time and blood loss were 124.7 minutes and 530 mL, respectively. Mean hip center position was 2.97 cm (range 2.35-3.58) horizontally and 2.06 cm (1.29-2.92) vertically, and mean acetabular inclination was 38.9° (range 27°-47°) at last follow-up. These parameters were not significantly different from those recorded immediately postoperatively (P > .05). There was no aseptic loosening, cup and augment migration, screw breakage, or presence of hip infection at last follow-up. All hips were radiographically stable.

CONCLUSION

Porous tantalum augments combined with titanium shells lead to satisfactory clinical and radiographic outcomes for the reconstruction of acetabular defect in primary THA at a mean 5.1 years of follow-up. This approach confers anatomical cup placement, simple operation, and a high rate of stable fixation.

An evaluation of the potential consequences of drilling titanium and tantalum implants during surgery - a pilot study

Background

The aim of the study was to evaluate the potential consequences of drilling titanium alloy (Ti) and tantalum (Ta) implants.

Methods

During an in vitro study, four holes were made in each of two spatially porous trabecular implants: one Ta and the other Ti alloy (Ti-6Al-7Nb). The weight and the volume of particles produced during the drilling were then measured using a Radwag XA 110/2X (USA) laboratory balance.

Results

The loss of mass of the Ti and Ta implants was respectively 1.26 g and 2.48 g, and the volume of free particles was respectively 280 mm³ and 149 mm³. The particles were recovered after each stage. Despite the use of 5 μm filters, around 0.6% of the total implant mass from both implants was not recovered after drilling (roughly 2% of the mass of the particles created).

Conclusion

It is technically difficult to make holes in Ti and Ta implants using standard surgical tools, and the process creates a significant amount of metal particles which cannot be removed, despite intensive flushing. This may have a potentially adverse influence on the survival of the implant and result in negative systemic consequences.

Comparative survival analysis of porous tantalum and porous titanium acetabular components in total hip arthroplasty

BACKGROUND

Porous tantalum acetabular components (PoTa) are well-studied, but less is known about widely used porous titanium (PoTi) acetabular components. We performed a comparative survival analysis between PoTi and PoTa acetabular components.

METHODS

Primary or revision THA performed using PoTi (n = 2,976) or PoTa (n = 184) acetabular components with minimum 2-year follow-up (PoTi n = 1,539; PoTa n = 157) were analysed. Univariate and multivariate logistic regression were performed to test the effect of porous metal acetabular component type on revision surgery for aseptic cup loosening. Multivariate model was adjusted for acetabular defect severity according to the Paprosky Classification.

RESULTS

Only PoTi components used in revision THA failed. Survival of the PoTi acetabular component was 98.6% when used in revision THA at mean 48.3-month follow-up. After adjusting for severity of acetabular defect, there was no difference in survival between PoTi and PoTa acetabular components when used in primary or revision THA.

CONCLUSIONS

After adjusting for acetabular defect severity, both PoTa and PoTi acetabular components had excellent survival at mean 44.4-month (range 4.3-91.5 months) follow-up when used in primary and revision THA.

Preoperative Planning and Operative Techniques of the Shorter Tapered Stem Compared to the Metaphyseal Fit Stem in Cementless Total Hip Arthroplasty

BACKGROUND

In order to prevent postoperative dislocation due to prosthetic impingement as a result of total hip arthroplasty (THA), the combined anteversion (CA) theory, which combines the anteversion of the femoral stem and the acetabular socket, has been revised in recent years. Particularly, it is necessary to keep CA within the target zone.

METHODS

The aim of this study was to investigate whether postoperative CA can be kept within the target zone while using the operative technique which prepares the socket first in cementless THA, by estimating the anteversion of the metaphyseal fit stem or the shorter, tapered wedge stem using preoperative 3-dimensional computerized planning, and by adjusting the anteversion of the socket using a navigation system that considers CA. One hundred fourteen patients (118 hips) were recruited for the study.

RESULTS

Postoperative CA in THA using the metaphyseal fit stem was kept within the target zone for 56 of the 60 hips (93.3%). Using the shorter, tapered wedge stem, 49 of the 58 hips (84.4%) were within the target zone. No postoperative dislocations were observed in any hips.

CONCLUSION

We found that the metaphyseal fit stem worked better than the shorter, tapered wedge stem in terms of meeting the planned CA. The shorter, tapered wedge stems were flexible in rotation according to the anatomical configuration of the proximal femur. Therefore, the stem could be placed second with the metaphyseal fit stem, but we recommend placing the stem first with the shorter, tapered wedge stem.

Total Hip Arthroplasty Using Modular Trabecular Metal Acetabular Components for Failed Treatment of Acetabular Fractures: A Mid-term Follow-up Study

Background:

Porous-coated cups have been widely used in acetabular reconstruction after failed treatment of acetabular fractures, and good results have been reported with the use of these cups; however, the durability and functionality of modular trabecular metal (TM) acetabular components in acetabular reconstruction after failed treatment of acetabular fractures remain unclear. This study aimed to examine the radiographic and clinical outcomes associated with the use of modular TM acetabular components for failed treatment of acetabular fractures to assess the durability and functionality of these components in acetabular reconstruction after failed treatment of acetabular fractures.

Methods:

A total of 41 patients (41 hips) underwent total hip arthroplasty (THA) using modular TM acetabular components for failed treatment of acetabular fractures at our hospital between January 2007 and December 2012. Among these patients, two were lost to follow-up. Therefore, 39 patients (39 hips) were finally included in this study. The Harris hip score before and after the surgery, satisfaction level of the patients, and radiographic results were assessed.

Results:

The mean Harris hip score increased from 34 (range, 8–52) before surgery to 91 (range, 22–100) at the latest follow-up examination (P < 0.001). The results were excellent for 28 hips, good for six, fair for three, and poor for two. Among the 39 patients, 25 (64%) and 10 (26%) were very satisfied and somewhat satisfied, respectively. All cups were found to be fully incorporated, and no evidence of cup migration or periacetabular osteolysis was noted.

Conclusions:

Despite the technically demanding nature of the procedure, THA using modular TM acetabular components showed good durability and functionality and may be an effective reconstruction option for failed treatment of acetabular fractures.

A 2- to 7-Year Follow-Up of a Modular Iliac Screw Cup in Major Acetabular Defects: Clinical, Radiographic and Survivorship Analysis With Comparison to the Literature

BACKGROUND

Inadequate acetabular bone stock is a major issue in total hip arthroplasty, and several treatment options are available. Stemmed cups have been used in this scenario with variable results. A novel modular polyaxial uncemented iliac screw cup (HERM-BS-Sansone cup-Citieffe s.r.l., Calderara di Reno, Bologna, Italy) has been recently introduced to overcome the drawbacks of stemmed cups. In this retrospective study, we report the results of this cup in patients with large acetabular bone defects at 2- to 7-year follow-up.

METHODS

We evaluated a consecutive series of 121 hips (118 revisions and 3 complex primary arthroplasties) treated with this novel cup at a mean follow-up of 46 months. Kaplan-Meier survival analysis was performed with implant revision for any reason as a primary end point. Further survival analysis was performed excluding septic failures. Clinical outcome was assessed with the Harris Hip Score.

RESULTS

There had been 7 reoperations: 1 for aseptic loosening, 5 for deep infection, and 1 for recurrent dislocation. In 5 cases, the cup was removed; estimated survival rate at 5-year follow-up with implant removal for any reason was 95.6% (95% confidence interval = 91-99), and 98.3% (95% CI = 96-100) excluding those failed for infection. Mean Harris Hip Score at latest follow-up was 77 points (range, 44-95; standard deviation = 11.9).

CONCLUSION

The present findings show the short-term efficacy of the iliac screw cup with respect to implant survival. A longer follow-up and a larger number of patients are necessary to confirm the encouraging preliminary results.

Favorable Results of Primary Total Hip Arthroplasty With Acetabular Impaction Bone Grafting for Large Segmental Bone Defects in Dysplastic Hips

BACKGROUND

The aim of the present study was to assess midterm results after acetabular impaction bone grafting (IBG) in primary total hip arthroplasty (THA) for developmental dysplasia of the hip (DDH) with large acetabular segmental defect.

METHODS

Primary THA with IBG for DDH with large acetabular segmental defect was performed in 40 hips of 38 patients. The average age was 61.6 years (range: 33-82 years), and the average follow-up period was 7.5 years (range: 3-10.3 years). The Merle d'Aubigné and Postel hip score and complications were assessed. For radiological assessment, postoperative location of the hip rotation center, the socket inclination angle, and the socket center-edge angle were assessed. Kaplan-Meier survival analysis was performed with the end points of any type of reoperation and aseptic acetabular loosening.

RESULTS

The mean Merle d'Aubigné and Postel hip score improved from 10.4 points to 16.2 points at the final follow-up. Reoperation was performed in 1 case for acute infection without loosening. In 39 out of 40 hips (97.5%), the center of hip rotation was located beneath the "high hip center." The average socket inclination angle was 39.3° (range: 30°-54°), and the average socket center-edge angle was -11.8° (range: -23° to 9°). Survival rate of acetabular component at 8 years with the end point of any reoperation and of aseptic loosening was 96.6% (95% confidence interval: 89.9%-100%) and 100%, respectively.

CONCLUSION

Acetabular IBG represents one of the useful options for restoring a normal hip center and acetabular bone stock in primary THA for DDH with large acetabular defect.

Comparison of 10-year clinical wear of annealed and remelted highly cross-linked polyethylene: A propensity-matched cohort study

No previous studies comparing the clinical wear rates of the two different kinds of cross-linked ultra-high-molecular-weight polyethylene (XLPE), annealed and remelted, are available. We compared the creep and steady wear rates of 36 matched pairs (72 hips in total) adjusting for baseline characteristics with propensity score matching techniques. Zirconia femoral heads with 26-mm diameter were used in all cases. The femoral-head cup penetration was measured digitally on radiographs. Significantly greater creep (p=0.006) was detected in the remelted (0.234mm) than annealed (0.159mm) XLPE. However, no significant difference (p=0.19) was found between the steady wear rates (0.003 and 0.008mm/year, respectively) of the annealed and remelted XLPE. Multiple regression analyses showed that remelted XLPE is significant independent variable (p<0.001) that is positively associated with creep. However, the patient age and body weight, cup size, the liner thickness, cup inclination, follow-up periods, and postoperative Merle d'Aubigné hip score had no significant effects (p>0.05) on the steady wear rates. No patients exhibited above the osteolysis threshold of 0.1mm/year, progressive radiolucencies, osteolysis, or polyethylene fracture. This　propensity-matched cohort study document no significant difference in wear resistant performances of annealed and remelted XLPE over an average period of 10 years.

Clinical and radiographic outcomes of a trabecular titanium™ acetabular component in hip arthroplasty: results at minimum 5 years follow-up

Background

Aim of this prospective study was to evaluate mid-term clinical and radiographic outcomes in total hip arthroplasty using an acetabular cup made of an innovative biomaterial, Trabecular Titanium™, whose highly porous structure and mechanical properties have been designed to mimic those of the natural bone, thus promoting a more physiological load transfer and a more durable fixation.

Methods

Between September 2007 and November 2009, 134 total hip replacements and eight revisions were carried out using DELTA-TT primary cups (Lima Corporate, Villanova di San Daniele del Friuli, Italy) in 133 consecutive patients. Mean age was 57.5 ± 14.7 SD (18–92) years. Diagnosis was primarily hip osteoarthritis in 85 (63 %) cases, developmental dysplasia of the hip (DDH) in 24 (18 %) and hip avascular necrosis (AVN) in 10 (7 %). All the revision procedures were due to aseptic loosening of the original implant. Approval of the Institutional Review Board of the IRCCS Policlinico San Matteo in Pavia was obtained for this study.

Results

Mean follow-up was 72.7 ± 7.9 SD (60–86) months. Average Harris Hip Score (HHS) significantly increased from 44.2 ± 5.4 SD (35–52) preoperatively to 95.9 ± 3.5 SD (88–100) at the last follow-up. No major post-operative complications were observed. 99.3 % of the acetabular components were radiographically stable at the last follow-up, without any radiolucent lines, sclerotic areas or periprosthetic osteolysis. Kaplan-Meier survival rate was 99.3 % at 5 years (95 % confidence interval).

Conclusions

This first account on the mid-term clinical performance of the DELTA-TT cup shows primary and secondary stability, thus representing an optimal solution for patients with high demands or affected by severe hip conditions.

[Arthroplasty for osteoarthritis secondary to hip dysplasia: Problem-oriented treatment strategies]

BACKGROUND

Because of anatomical variations total hip arthroplasty (THA) can be demanding in patients with osteoarthritis secondary to hip dysplasia.

OBJECTIVES

Depending on the degree of bony deformation, hip dislocation and soft tissue alteration numerous treatment strategies are available. This review describes current approaches that address frequent deformities.

MATERIALS AND METHODS

Review of relevant clinical studies, meta-analyses, and presentation of our own approach.

RESULTS

Pre-operative planning (based on a thorough clinical and radiographic examination) is essential. Acetabular reconstruction close to the primary acetabulum should always be intended. Roof augmentation and/or cup medialization can support stable bony implant fixation. Subtrochanteric shortening osteotomy of the femur is a demanding but reliable technique that avoids nerve damage in cases where inappropriate lengthening would be necessary (i.e., high riding dislocation).

CONCLUSIONS

Although the post-operative complication rate is elevated after THA for dysplastic hips compared with primary osteoarthritis, the overall functional results and implant survival are comparable.