Acetabular Bone Defect in Total Hip Arthroplasty for Crowe II or III Developmental Dysplasia of the Hip: A Finite Element Study

Integrated Acetabular Prosthesis Versus Bone Grafting in Total Hip Arthroplasty for Crowe Type II and III Hip Dysplasia: A Retrospective Case-Control Study

OBJECTIVE

Many methods of acetabular reconstruction with total hip arthroplasty (THA) for Crowe type II and III adult developmental dysplasia of the hip (DDH) acetabular bone defect have been implemented clinically. However, there was no study comparing the results of integrated acetabular prosthesis (IAP) with bone grafting (BG). This study aims to investigate the efficacy of IAP and BG for acetabular reconstruction in Crowe type II and III DDH.

METHODS

The clinical data of 45 patients with unilateral Crowe type II and III DDH who underwent THA from January 2020 to January 2023 were retrospectively analyzed. The patients were divided into two groups: 25 patients using 3D-printed IAP (IAP group) and 20 patients using BG (BG group). The operation time and intraoperative blood loss were recorded. The clinical outcomes were assessed by Harris Hip Score (HHS) and full weight-bearing time. The radiological outcomes were evaluated by the radiological examination. Accordingly, intraoperative and postoperative complications were observed as well. The data between the two groups were compared by independent sample t-tests and the Mann-Whitney U rank sum test.

RESULTS

There were no significant differences between the two groups in Harris Hip Score (HHS) (preoperative, 6 months postoperative, and the last follow-up), leg length discrepancy (LLD), cup inclination, cup anteversion, vertical center of rotation (V-COR), horizontal center of rotation (H-COR) (p > 0.05). The mean HHS in the IAP group was higher than in the BG group at 1 and 3 months postoperative (p < 0.001). The mean surgical time and blood loss in the IAP group were less than in the BG group (p < 0.001). The mean full weight-bearing time in the IAP group was shorter than in the BG group (p < 0.01). No complications were observed in either group during the follow-up period.

CONCLUSION

IAP and BG have similar radiographic outcomes and long-term clinical efficacy in THA for Crowe type II and III DDH, but the IAP technique has higher surgical safety and facilitates the recovery of hip joint function, which is worthy of clinical promotion.

Biomechanical analysis and clinical observation of 3D-printed acetabular prosthesis for the acetabular reconstruction of total hip arthroplasty in Crowe III hip dysplasia

Objective: This study aimed to evaluate the biomechanical effectiveness of 3D-printed integrated acetabular prosthesis (IAP) and modular acetabular prosthesis (MAP) in reconstructing the acetabulum for patients with Crowe III developmental dysplasia of the hip (DDH). The results of this study can provide a theoretical foundation for the treatment of Crowe III DDH in total hip arthroplasty (THA). Methods: Finite element (FE) analysis models were created to reconstruct Crowe III DDH acetabular defects using IAP and MAP. The contact stress and relative micromotion between the acetabular prosthesis and the host bone were analyzed by gradually loading in three increments (210 N, 2100 N, and 4200 N). In addition, five patients with Crowe III DDH who underwent IAP acetabular reconstruction were observed. Results: At the same load, the peak values of IAP contact stress and relative micromotion were lower than those of MAP acetabular reconstruction. Under jogging load, the MAP metal augment's peak stress exceeded porous tantalum yield strength, and the risk of prosthesis fracture was higher. The peak stress in the bone interface in contact with the MAP during walking and jogging was higher than that in the cancellous bone, while that of IAP was higher than that of the cancellous bone only under jogging load, so the risk of MAP cancellous bone failure was greater. Under jogging load, the relative micromotion of the MAP reconstruction acetabular implant was 45.2 μm, which was not conducive to bone growth, while under three different loads, the relative micromotion of the IAP acetabular implant was 1.5-11.2 μm, all <40 μm, which was beneficial to bone growth. Five patients with IAP acetabular reconstruction were followed up for 11.8 ± 3.4 months, and the Harris score of the last follow-up was 85.4 ± 5.5. The imaging results showed good stability of all prostheses with no adverse conditions observed. Conclusion: Compared with acetabular reconstruction with MAP, IAP has a lower risk of loosening and fracture, as well as a better long-term stability. The application of IAP is an ideal acetabular reconstruction method for Crowe III DDH.

The press-fit technique without screws and bone graft can be used as an alternative method in Crowe type II and III hip dysplasia

Background/aim

Developmental dysplasia of the hip (DDH) is the most common cause of secondary hip arthrosis. The primary purpose of this study was to assess the results of an oversized hemispherical cup via the press-fit technique used for Crowe type II and III DDH without screws and to determine if adequate medialization and initial stability of the acetabular component would allow us to avoid screw and graft use.

Materials and methods

Between February 2012 and May 2020, the current study analyzed 43 hips with Crowe type II and III DDH treated with a porous-coated cup by placing the press-fit technique or screw. The acetabular cup was fixed with the press-fit technique without additional screws in 27 hips and with screws in 16 hips. The inclusion criterion in this study was a minimum 2-year-period after the surgery.

Results

The mean duration of follow-up was 6.83 ± 2.67 years in the press-fit group and 6.21 ± 2.01 years in the screw group. The mean age of the patients was 47.96 ± 12.37 years in the press-fit group and 50.5 ± 12.37 years in the screw group. Measurements revealed that the hip center of rotation (HCR) was located more medially and superiorly postoperatively than preoperatively in both groups. The mean cup coverage in the screw group was 85.58% ± 7.51% (75.3%-97.2%), while it was less than 90.41% ± 6.15% (76.3%-98.2%) in the press-fit group (p = 0.038). No component was revised because of loosening, and all of the implants were radiologically stable within the observation period. No statistically significant differences were observed regarding the postoperative limp-length discrepancy between the groups (p = 0.496).

Conclusion

Press-fit implantation of a porous-coated acetabular component without screws can also be used as an alternative method for THA in Crowe type II and III DDH. The initial stability was obtained using the press-fit technique with a small cup positioned more medially and superiorly, which may allow the surgeon to avoid screw and graft use.

Extended mechanical loads for the analysis of acetabular cages

To analyse the strength and mechanical behaviour of hip implants, it is essential to employ an appropriate loading model. Generating computational models supplemented with muscle forces is a complicated task, especially in the initial phase of implant development. This research aims to expand the possibilities of the simpler acetabular cage model based on joint loads without significantly increasing the demand for computing resources. A Python script covered and grouped the loads from daily activities. The ten calculated major loads were compared with the maximum of the walking and stair climbing loads through the finite element analyses of a custom-made acetabular cage. Sensitivity analyses were performed for the surrounding bones' elastic modulus and the pelvis boundary conditions. The major loads can geometrically cover the entire load spectrum of daily activities. The effect of many high-magnitude force vectors is uncertain in the approach that uses the most common maximum loads. Using these resultant major loads, a new stress concentration area could be detected on the acetabular cage, besides the stress concentration areas induced by the loads reported in the literature. The qualitative correctness of the results is also supported by a control computed tomography scan: a fracture occurred in an extensive, high-stress zone. The results are not sensitive to changes in the elastic modulus of the surrounding bone and the boundary conditions of the model. The presented load vectors and the algorithm make more extensive static analyses possible with little computational overhead. The proposed method can be used for checking the static strength of similar implants.

Acetabular Diameter Assessment and Three-Dimensional Simulation for Acetabular Reconstruction in Dysplastic Hips

BACKGROUND

This study aimed to investigate the relationship between acetabular width, three-dimensional (3D) simulation, and surgical results in total hip arthroplasty patients who have developmental dysplasia of the hip (DDH).

METHODS

This retrospective study included 216 DDH cases. Inner and outer acetabular width (OAW) was measured at the plane passing through the center of acetabular fossa. 3D simulation and 2D standard templating were performed. The actual cup size and the use of augments during surgery were recorded. Association among the indices and their distribution in different types of DDH were analyzed.

RESULTS

A difference of 13 to 14 millimeters (mm) was found between the inner acetabular width and actual cup size used in type II, III, and IV cases, while the difference was 0.2 to 3.6 mm for OAW. The accuracy of 2D templating and 3D simulation in predicting cup size was comparable in Crowe type I (86.5 versus 76%, P = .075), type II (72.7 versus 51.5%, P = .127), and type III (93.3 versus 66.7%, P = .169). The 3D simulation was significantly more accurate in Crowe type IV (89.1% versus 60.9%, P = .001). Augments and bone grafts were significantly more commonly used in type II (25%) than in the other types (0 to 6.5%).

CONCLUSION

OAW more accurately predicted actual cup size than inner acetabular width. The supero-lateral acetabular bone defects in type II cases require additional attention. Compared with 2D templating, 3D simulation is more accurate in predicting actual cup size in dysplastic hips with severe deformity and may be recommended in these selected cases, especially for Crowe IV patients.

The application of additive manufacturing technology in pelvic surgery: A bibliometrics analysis

With the development of material science, additive manufacturing technology has been employed for pelvic surgery, addressing the challenges, such as the complex structure of the pelvis, difficulty in exposing the operative area, and poor visibility, of the traditional pelvic surgery. However, only limited studies have been done to review the research hotspots and trends of the additive manufacturing technology applied for pelvic surgery. In this study, we comprehensively analyzed the literatures related to additive manufacturing technology in pelvic surgery by a bibliometrics analysis and found that additive manufacturing technology is widely used in several aspects of preoperative diagnosis, preoperative planning, intraoperative navigation, and personalized implants for pelvic surgery. Firstly, we searched and screened 856 publications from the Web of Science Core Collection (WoSCC) with TS = (3D printing OR 3D printed OR three-dimensional printing OR additive manufacturing OR rapid prototyping) AND TS = (pelvis OR sacrum OR ilium OR pubis OR ischium OR ischia OR acetabulum OR hip) as the search strategy. Then, 565 of these were eliminated by evaluating the titles and abstracts, leaving 291 pieces of research literature whose relevant information was visually displayed using VOSviewer. Furthermore, 10 publications with high citations were selected by reading all publications extensively for carefully evaluating their Titles, Purposes, Results, Limitations, Journal of affiliation, and Citations. Our results of bibliometric analysis demonstrated that additive manufacturing technology is increasingly applied in pelvic surgery, providing readers with a valuable reference for fully comprehending the research hotspots and trends in the application of additive manufacturing technology in pelvic surgery.

Mid-term outcomes after total hip arthroplasty in 106 Crowe II/III hips: different hip center positions

BACKGROUND

Under the obvious acetabular superolateral bone defect of Crowe II/III hips, this study aimed to investigate the difference in surgical technique of different hip center positions from the surgical data and clinical outcomes.

METHODS

From July 2007 to December 2016, 87 patients (106 Crowe II/III hips) consecutively received total hip arthroplasty (THA). The minimum follow-up time was 5 years. The mean limb length discrepancy was 1.97 ± 1.81 cm. Twenty-four hips had surgical histories. The patients were divided into three groups according to the acetabular prosthesis positions, depending on the Crowe classification, respectively, group 1 (Crowe I), group 2 (Crowe II) and group 3 (Crowe III). The surgical data and clinical results were used to evaluate the outcome of different surgical techniques of different hip center positions, including surgical time, blood loss, blood transfusion, number of osteotomy hips, osteotomy length, the distribution of prothesis, postoperative inpatient days, Harris hip scores, Visual Analogue Scale (VAS), Back Pain Function Scale (BPFS) and complications.

RESULTS

The mean follow-up time was 8.93 ± 2.55 years. Nineteen hips performed intraoperative osteotomy. From group 1 to group 3, the mean osteotomy length were 0.53 ± 1.11 cm, 0.05 ± 0.22 cm, and 0.00 ± 0.00 cm, respectively (p = 0.083); the surgical time were 142.57 ± 57.94 min, 118.4 ± 41.22 min, and 120.00 ± 84.85 min, respectively (p = 0.324); the blood loss were 498.21 ± 368.53 mL, 333.33 ± 167.62 mL, and 350.00 ± 212.13 mL, respectively (p = 0.255); the blood transfusion were 288.48 ± 381.68 mL, 128.00 ± 235.17 mL, and 385.00 ± 219.20 mL, respectively (p = 0.199); the postoperative inpatient days were 7.95 ± 4.42 d, 7.47 ± 4.29 d, and 6.50 ± 0.71 d, respectively (p = 0.831). Among the groups, the distribution of acetabular prosthesis, acetabular liner, acetabular prosthesis sizes, femoral head sizes and femoral prothesis distal sizes were not significantly different (p > 0.05). Only the distribution of femoral prosthesis was significantly different (p = 0.046); the Harris, VAS, BPFS, and the distribution of complications were not significantly different (p > 0.05).

CONCLUSIONS

We provided a framework to guide decision-making in Crowe II/III hips for surgeons: the surgical technique of different hip center positions was stable and had good outcomes, but the acetabular prothesis position and femoral prothesis should be determined according to the intraoperative situation.

LEVEL OF EVIDENCE

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Biomechanical effect of metal augment and bone graft on cup stability for acetabular reconstruction of total hip arthroplasty in hip dysplasia: a finite element analysis

Background

Different methods of acetabular reconstruction with total hip arthroplasty (THA) for Crowe II and III of adult developmental dysplasia of the hip (DDH) acetabular bone defect have been implemented clinically. However, the biomechanical effect of different augmented materials for acetabular reconstruction in THA on shell stability has never been discussed.

Methods

In the present study, autologous bone graft (BG)and metal (Ti6Al4V) augment (MA) were simulated with several acetabular bone defect models of DDH in THA. The contact pressure and micromotion between the shell and host bone were measured for evaluating the shell stability using a finite element method.

Results

The peak contact stress between shell and host bone was higher in the MA situation (12.45 vs 8.71 MPa). And the load transfer path was different, for BG models, the high local contact stresses were found at the junction of bone graft and host bone while for MA models the concentrated contact stresses were at the surface of MA. The peak relative micromotion between shell and host bone was higher in the MA situation (12.61 vs 11.13 µm). However, the peak micromotion decreased in the contact interface of MA and cup compared to the BG models.

Conclusions

The higher micromotion was found in MA models, however, enough for bone ingrowth, and direct stronger fixation was achieved in the MA-cup interface. Thus, we recommended the MA can be used as an option, even for Crowe III, however, the decision should be made from clinical follow-up results.