Implication of acetabular width on the anteroposterior pelvic radiograph of patients with developmental dysplasia of the hip

A novel intraoperative acetabular reaming center locating method in total hip arthroplasty for Crowe type IV developmental dysplasia of the hip: a retrospective cohort study

PURPOSE

Although the principles of hip reconstruction are consistent, due to lack of reliable anatomical landmarks, how to decide the acetabular cup reaming centre intraoperatively in Crowe IV patients with developmental dysplasia of the hip (DDH) remains unclear. This study aims to address this question.

METHODS

Fifty-eight Crowe IV patients were enrolled from 2017 to 2019. By examining our previous clinical data, we analyzed the anatomical morphology of Crowe IV acetabulum and proposed a method of locating intraoperative reaming centering for implantation of a standard-sized acetabular cup, which is the upper two thirds of the posterior border of the true acetabulum. All patients included in this study were reamed according to this method. The average postoperative follow-up was 4.1 years (3-5 years). The position of the centre of rotation (COR), cup coverage (CC), and optimal range of joint motion (ROM) were examined by 3D computer simulation measurement. Postoperative complications and hip Harris score were collected and analyzed.

RESULTS

The morphology of the type IV DDH true acetabulum was mostly triangular. The intraoperative reaming centre were centered on the upper two thirds of the posterior border of the true acetabulum. The postoperative 3D CC was 80.20% ± 7.63% (64.68-90.24%, 44-48-mm cup size). The patients' mean Harris score improved from 39.7 ± 20.4 preoperatively to 91.5 ± 8.12 at the last follow-up.

CONCLUSION

Our study demonstrated that satisfactory CC and clinical results could be achieved by implanting a standard-sized cup with the reaming centre on the upper two thirds of the posterior border of the true acetabulum.

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.

Effects of different pelvic osteotomies on acetabular morphology in developmental dysplasia of hip in children

Developmental dysplasia of hip seriously affects the health of children, and pelvic osteotomy is an important part of surgical treatment. Improving the shape of the acetabulum, preventing or delaying the progression of osteoarthritis is the ultimate goal of pelvic osteotomies. Re-directional osteotomies, reshaping osteotomies and salvage osteotomies are the three most common types of pelvic osteotomy. The influence of different pelvic osteotomy on acetabular morphology is different, and the acetabular morphology after osteotomy is closely related to the prognosis of the patients. But there lacks comparison of acetabular morphology between different pelvic osteotomies, on the basis of retrospective analysis and measurable imaging indicators, this study predicted the acetabular shape after developmental dysplasia of the hip pelvic osteotomy in order to help clinicians make reasonable and correct decisions and improve the planning and performance of pelvic osteotomy.

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.

Restoring Rotation Center in Total Hip Arthroplasty for Developmental Dysplasia of the Hip with the Assistance of Three Dimensional Printing Technology: A Pilot Study

Objective

To develop a new method to restore hip rotation center exactly and rapidly in total hip arthroplasty (THA) with the assistance of three dimensional (3D) printing technology and evaluate its clinical and radiological outcomes.

Methods

From March 2014 to July 2018, a total of 17 patients (five hips of four men and 16 hips of 13 women) with end‐stage osteoarthritis secondary to developmental dysplasia of the hip who underwent THA were analyzed and followed up retrospectively. The average age is 58.00 ± 8.12 years (range from 45 to 71 years). Simulated operations were performed on 3D printed hip models for preoperative planning. The morphology of Harris fossa and acetabular notches were recognized and restored to locate the acetabular center. The size of bone defect was measured by the bone wax method. The agreement on the size of acetabular cup and bone defect between simulated operations and actual operations were analyzed. Harris Hip Score (HHS) was used to evaluate the recovery of hip joint function. The vertical distance and horizontal distance of the rotation center on the pelvis plain radiograph were measured, which were used to assess the efficacy of restoring hip rotation center and acetabular cup migration.

Results

The mean sizes of bone defect in simulated operations and THA were 4.58 ± 2.47 cm² and 4.55 ± 2.57 cm² respectively. There was no significant difference statistically between the sizes of bone defect in simulated operations and the actual sizes of bone defect in THA (t = 0.03, P = 0.97). The sizes of the acetabular cup of simulated operations on 3D print models showed a high rate of coincidence with the actual sizes in the operations (ICC = 0.93). All 17 patients were available for clinical and radiological follow‐up. The average follow‐up time was 18.35 ± 6.86 months (range, 12–36 months. The average HHS of the patients was improved from (38.33 ± 6.07) preoperatively to the last follow‐up (88.61 ± 3.44) postoperatively. The mean vertical and horizontal distances of hip rotation center on the pelvic radiographs were restored to 15.12 ± 1.25 mm and 32.49 ± 2.83 mm respectively. No case presented dislocation or radiological signs of loosening until last follow‐up.

Conclusions

The application of 3D printing technology facilitates orthopedists to recognize the morphology of Harris fossa and acetabular notches, locate the acetabular center and restore the hip rotation center rapidly and accurately.

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

Background

The purpose of this study was to establish the finite element analysis (FEA) model of acetabular bone defect in Crowe type II or III developmental dysplasia of the hip (DDH), which could evaluate the stability of the acetabular cup with different types of bone defects, different diameters of femoral ceramic heads, and the use of screws and analyze the stress distribution of screws.

Methods

The FEA model was based on the CT scan of a female patient without any acetabular bone defect. The model of acetabular bone defect in total hip arthroplasty for Crowe II or III DDH was made by the increasing superolateral bone defect area of the acetabular cup. Point A was located in the most medial part of the acetabular bone defect. A 52 mm PINNACLE cup with POROCOAT Porous coating was implanted, and two screws (the lengths were 25 mm and 40 mm) were implanted to fix the acetabular cup. The stability of the acetabular cup and the von Mises stress of point A and screws were analyzed by a single-legged stance loading applied in 1948 N (normal working). The different diameters of the femoral ceramic head (28 mm, 32 mm, and 36 mm) were also analyzed.

Results

The von Mises stress of point A was gradually increased with the increasing uncoverage values. When the uncoverage values exceeded 24.5%, the von Mises stress of point A without screws increased significantly, leading to instability of the cup. Screws could effectively reduce the von Mises stress of point A with uncoverage values of more than 24.5%. However, the peak von Mises stress in the screws with the uncoverage values that exceeded 24.5% was considerably increased. The diameter of the femoral ceramic head had no significant effect on the von Mises stress and the stability of the acetabular cup.

Conclusions

We recommend that uncoverage values of less than 24.5% with or without screw is safe for patients with Crowe II or III DDH.

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.

Radiographic Underestimation of In Vivo Cup Coverage Provided by Total Hip Arthroplasty for Dysplasia

The accuracy of using 2-dimensional anteroposterior pelvic radiography to assess acetabular cup coverage among patients with developmental dysplasia of the hip after total hip arthroplasty (THA) remains unclear in retrospective clinical studies. A group of 20 patients with developmental dysplasia of the hip (20 hips) underwent cementless THA. During surgery but after acetabular reconstruction, bone wax was pressed onto the uncovered surface of the acetabular cup. A surface model of the bone wax was generated with 3-dimensional scanning. The percentage of the acetabular cup that was covered by intact host acetabular bone in vivo was calculated with modeling software. Acetabular cup coverage also was determined from a postoperative supine anteroposterior pelvic radiograph. The height of the hip center (distance from the center of the femoral head perpendicular to the inter-teardrop line) also was determined from radiographs. Radiographic cup coverage was a mean of 6.93% (SD, 2.47%) lower than in vivo cup coverage for these 20 patients with developmental dysplasia of the hip (P<.001). However, both methods yielded highly correlated measurements for cup coverage (Pearson r=0.761, P<.001). The size of the acetabular cup (P=.001) but not the position of the hip center (high vs normal) was significantly associated with the difference between radiographic and in vivo cup coverage. Two-dimensional radiographically determined cup coverage conservatively reflects in vivo cup coverage and remains an important index (taking 7% underestimation errors and the effect of greater underestimation of larger cup size into account) for assessing the stability of the cup and monitoring for adequate ingrowth of bone. [Orthopedics. 2018; 41(1):e46-e51.].

Morphological Analysis of True Acetabulum in Hip Dysplasia (Crowe Classes I-IV) Via 3-D Implantation Simulation

BACKGROUND

The purpose of this study was to investigate the 3-dimensional (3D) morphological features of the true acetabulum in patients with developmental dysplasia of the hip (DDH).

METHODS

Seventy-nine hips-53 in patients with developmental dysplasia of the hip (DDH) and 36 normal hips-were included in the present study. According to the Crowe classification, 26 hips were graded as Class I, 31 were Class II or III, and 22 were Class IV. The anterior pelvic plane was defined to standardize the measurements in the study. A selected virtual cup component was implanted into the true acetabulum of a 3D pelvic model of each hip. The acetabular anteversion angle, effective center-edge (CE) angle, effective Sharp angle, and thickness of the medial wall were measured to provide morphological indices of the true acetabulum. Acetabular sector angles and the component coverage ratio were measured to provide coverage indices.

RESULTS

The acetabular anteversion angle increased with the severity of the DDH. Crowe-II/III hips had the smallest effective CE angle and the largest effective Sharp angle. The mean medial wall thickness was greatest in the Crowe-II/III hips (8.72 mm; 95% confidence interval [CI] = 7.52 to 9.92 mm), intermediate in the Crowe-I hips (7.17 mm; 95% CI = 6.24 to 8.11 mm), and smallest in the Crowe-IV hips (6.05 mm; 95% CI = 4.78 to 7.32 mm). The integrated coverage ratio of the Crowe-II/III hips was significantly less than that of the Crowe-I and IV hips.

CONCLUSIONS

The morphological features of the true acetabulum in patients with DDH can be evaluated comprehensively by using 3D implantation simulation. Segmental bone deficiency was prevalent in the dysplastic hips, especially those in the Crowe-II/III group. Both the severity and the individual morphology of the acetabular dysplasia should be carefully considered in preoperative planning.

Does High Hip Center Decrease Range of Motion in Total Hip Arthroplasty? A Computer Simulation Study

BACKGROUND

High placement of a cementless acetabular cup is often required to have sufficient bone coverage in hip dysplasia. We examined whether a high hip center decreases the postoperative range of motion (ROM) in total hip arthroplasty.

METHODS

Using a computer software, ROM and bone coverage were examined in 32 patients with unilateral osteoarthritis of the hip with Crowe type II or III hip dysplasia. The cup was placed at the anatomic hip center and moved vertically in 5-mm increments. Vertical center of rotation (V-COR) was defined as the distance from the head center to the interteardrop line. The required ROM was defined as flexion  ≥110°, internal rotation (IR) at 90° flexion ≥30°, extension ≥30°, and external rotation ≥30°. We determined the V-COR to satisfy the required ROM and cup center-edge angle (Cup-CE) ≥0°.

RESULTS

Only 40.6% of the patients satisfied Cup-CE ≥0° at the anatomic hip center. Bone coverage increased with the peak at 30, 35 mm of V-COR (90.6% satisfied Cup-CE ≥0°) and decreased at ≥40 mm. Higher V-COR resulted in lower range of flexion and IR, but increased the range of extension and external rotation. The cutoff value from the receiver-operating characteristic curve for both flexion and IR was a V-COR of 35 mm.

CONCLUSION

The higher hip center gained more bone coverage but decreased the range of hip flexion and IR. Acceptable V-COR in hip dysplasia was around 35 mm, about 20 mm above the true hip center, in terms of ROM.