Acetabular Prosthesis Research Articles

The accuracy and efficiency of design and development of 3D printed integral anatomical acetabular prosthesis in total hip arthroplasty for Crowe type Ⅱ and Ⅲ developmental dysplasia of the hip

Objective: To compare the accuracy and efficiency between the model development method and the software development method, which design and develop 3D printed integral anatomical acetabular prosthesis to be used in total hip arthroplasty(THA) for patients with Crowe type Ⅱ and Ⅲ developmental dysplasia of the hip(DDH). Methods: Fifteen patients with end-stage hip osteoarthritis due to Crowe type Ⅱ and Ⅲ DDH who underwent THA in the Orthopedics Department of the First Affiliated Hospital of Bengbu Medical College between January 2015 and June 2023 were selected in this study retrospectively. There were 1 male (1 hip) and 14 females (17 hips) with a mean age of (55.1±9.1) years. There were 12 hips with Crowe type Ⅱ, 6 hips with Crowe type Ⅲ. The preoperative pelvis three-dimensional CT data in those patients were used to design integral anatomical acetabular prosthesis. The model development group used 3D printing technology to print life-size pelvis models. The acetabulum was reamed and the acetabulum cup was inserted into the socket according to conventional THA procedures. The bone defect above the acetabulum cup was filled with bone wax. The Mimics and 3-matic software were used to simulate the THA procedures, design and install the integrated anatomical acetabular prosthesis in the software development group. The operation time, the size of the acetabular cup, the volume and surface area of the acetabulum bone defect, the acetabular cup's inclination and anteversion, the horizontal distance and the vertical distance of hip rotation center were compared between the two methods. Results: The study in the two groups were all based on the data of 18 hips in the 15 patients. The horizontal and vertical distances of rotation center in the model development group and software development group was (32.08±1.80) mm, (32.17±2.40) mm and (14.36±1.53) mm, (15.11±1.45) mm, respectively (both P>0.05). The cup size in model development group was (48.56±1.15)mm, and it was (48.77±1.22) mm in the software group (P=0.160). The anteversion and inclination of the acetabular cup in the model and software groups were 23.79°±6.31°, 30.49°±11.03° and 15.17°±0.52°, 40.24°±0.58°, respectively (both P<0.01). The volume and surface area of the acetabulum bone defect in the model development group was (5.06±2.86) mm3 and (8.31±2.21) mm2, respectively, while it was (4.01±2.56)mm3 and (6.83±2.71) mm2, respectively, in the software development group (both P<0.05). The work time in the model development group was (24.43±0.68) h and (0.47±0.12) h in the software development group, respectively (P<0.001). Conclusion: Compared with the 3D printing model development method, the application of Mimics and 3-matic software to design and develop integrated anatomical acetabular prosthesis in total hip arthroplasty for Crowe type Ⅱ and Ⅲ DDH show advantages of convenience, high efficiency and more accuracy.

Precise Acetabular Prosthesis Positioning Using a Novel Robot-Assisted Total Hip Arthroplasty System: A Multicenter, Randomized Controlled Trial.

Total hip arthroplasty (THA) is currently one of the most effective treatment methods for end-stage hip joint disease, and its long-term effectiveness largely depends on the accurate placement of the acetabular prosthesis. In conventional surgery, the placement of the acetabular prosthesis mainly relies on the surgeon's clinical experience and surgical techniques. To further improve the accuracy of prosthesis placement, a new robotic system for THA is designed. The purpose of this study is to verify the effectiveness and safety of THA assisted by this robotic system. A multicenter, prospective, randomized controlled, superiority study design was adopted with statistical methods of t test and Chi-squared test. Participants undergoing primary THA have been enrolled in three centers of joint surgery in China since July 17, 2023. Robotic THA was operated in the experimental group, and conventional instruments were used in the control group. The primary outcome is the proportion of anteversion and inclination angles in the safe zone. The secondary outcomes include operation time, WOMAC score, Harris score, SF-36 health questionnaire, dislocation rate of hip joint, and rates of adverse events and serious adverse events. A total of 138 patients were included in this study. The proportion of both anteversion and inclination angles in the safe zone was 92.2% in the experimental group and 50.8% in the control group, with significant difference (p < 0.01). The average operation time in the experimental group and control group was 116.4 and 80.5 min respectively, with significant difference (p < 0.01). There was no significant difference in WOMAC score, Harris score, and SF-36 between the two groups (6 ± 2) weeks after operation (p > 0.05). The dislocation rate of hip joint in the experimental group and control group were 3.0% and 1.5%, respectively, without significant difference (p > 0.05). The rate of adverse events and severe adverse events in the experimental group and control group also showed no significant difference (p > 0.05). No adverse events or serious adverse events were judged to be "definitely related" to the experimental instruments. Robotic THA could prolong the operation time within an acceptable range, but more precise acetabular prosthesis positioning could be obtained when compared with conventional surgery. Besides, no significant difference was found in function scores, dislocation rate or other adverse events, which indicates that this new robot system shows both good effectiveness and safety in THA. Clinical Trials: NCT05947734.

Computer-Assisted Total Hip Arthroplasty Improves Acetabular Prosthesis Placement Accuracy: A Multicenter, Randomized Controlled Clinical Study.

The long-term effectiveness of total hip arthroplasty (THA) largely depends on the accuracy of acetabular prosthesis placement. To improve the accuracy of acetabular prosthesis placement, we utilized a new surgical navigation system: visual treatment solution (VTS). The purpose of this study was to verify the efficacy and safety of this system in assisting THA. This was a prospective, multicenter, randomized controlled trial. One hundred and twenty-four patients undergoing primary THAs were included. The experimental group underwent VTS-assisted THA, and the control group underwent traditional surgical techniques. The main efficacy evaluation indicators were the proportion of anteversion and inclination angles in the Lewinnek safe zone, and secondary evaluation indicators included operation time, Western Ontario and McMaster University Osteoarthritis index (WOMAC) score, Harris score, short-form-36 (SF-36) score, and hip dislocation rate. Statistical analysis was performed mainly by t-test and chi-square test. The proportion of both anteversion and inclination angles in the safe zone was 93.1% in the experimental group and 50.9% in the control group; the difference was significant (p < 0.01). The average operation time was 112.5 min in the experimental group and 92.6 min in the control group; the difference was significant (p < 0.01). There were no significant differences in WOMAC score, Harris score, or SF-36 score between the experimental and control groups at 3 months after the operation (p > 0.05). The dislocation rate was 0% in the experimental group and 1.6% in the control group; the difference was not significant (p > 0.05). VTS-assisted THA can significantly improve the accuracy of acetabular prosthesis placement. However, there were no differences in short-term clinical outcomes or dislocation rates between the two groups.

Application of Intraoperative Individualized Cup Combination-Cup-on-Cup Technique in Severe Acetabular Defects.

This study aimed to investigate the application of the cup-on-cup technique in revision total hip arthroplasty (THA) and report clinical and radiographic outcomes from a series of case follow-ups. Retrospective analysis of 10 patients who underwent acetabular prosthesis revision with cup-on-cup technique. According to the Paprosky classification of acetabular bone defects, there were 2 cases of type II C, 3 cases of type III A, and 5 cases of type III B. The average follow-up was 54.8 ± 5.1 months, and the Harris score of the hip joint increased from 37.0 ± 9.9 preoperatively to 80.5 ± 3.1 postoperatively at the final follow-up (p < 0.001). Comparing the surgical side's hip center of rotation (COR) to the contralateral side, the preoperative average upward displacement was 33.8 ± 15.0 mm, while the postoperative average upward displacement was 0.2 ± 3.3 mm (p < 0.001). Similarly, the preoperative average inward displacement was 9.1 ± 5.1 mm, while the postoperative average outward displacement was 1.8 ± 1.6 mm (p < 0.001). There was no significant difference (p = 0.71) between the average density values of the contralateral and surgical sides at the final follow-up, which were 127.4 ± 13.7 and 125.0 ± 14.8, respectively. During the follow-up period, all patients achieved satisfactory radiographic outcomes, and no prosthetic loosening was observed. The cup-on-cup technique can reconstruct acetabular bone defects and restore hip COR in revision THA, with favorable clinical and radiographic outcomes.

Long-term computed tomographic osteolytic analysis of highly cross-linked polyethylene prosthesis after total hip arthroplasty

To analyze the occurrence of osteolysis in total hip arthroplasty (THA) with highly cross-linked polyethylene prosthesis during a follow-up of more than 15 years. The clinical data of 84 patients (105 hips) treated with THA in the Affiliated Hospital of Kanazawa Medical University in Japan between June 2000 and April 2004 and met the selection criteria was retrospectively analyzed. There were 7 males and 77 females, aged from 41 to 75 years, with an average of 56.4 years. There were 94 hips with secondary hip osteoarthritis, 4 hips after pelvic osteotomy, 2 hips with primary hip osteoarthritis, 2 hips with traumatic hip osteoarthritis, 2 hips with osteonecrosis of the femoral head, and 1 hip with rheumatoid arthritis. According to Crowe classification, there were 79 hips of type Ⅰ, 19 hips of type Ⅱ, 6 hips of type Ⅲ, and 1 hip of type Ⅳ. The highly cross-linked polyethylene acetabular liner combined with a 26 mm zirconia femoral head were used in all patients. X-ray films were taken after operation to analyze the radiation transmission and osteolysis around the acetabular prosthesis. The vertical distance (the distance between the teardrop line at the lower edge of the pelvis and the perpendicular line of the hip rotation center), the horizontal distance (the horizontal distance between the hip rotation center and the interteardrop line and the vertical line at the lower edge of the teardrop), and the acetabular cup anteversion angle were measured at last follow-up. The acetabular and femoral osteolysis was analyzed by CT scan and three-dimensional multiplanar reconstruction (3D-MPR). Combined with X-ray film and CT results, osteolysis was evaluated according to the Narkbunnam score. Deep vein thrombosis of lower limbs occurred in 2 cases. All patients were followed up 15-18 years, with an average of 15.9 years. One hip dislocation and 1 periprosthetic fracture occurred postoperatively, and no acetabular loosening or prosthetic lining ruptures occurred. Except for 1 patient who had a radiolucent line in the acetabulum after operation, the other 83 patients did not show any radiolucent line in the acetabulum or the femur. None of the patients underwent hip revision. X-ray films at last follow-up showed an acetabular cup anteversion angle of -10°-39°, with an average of 22°; a vertical distance of 3.5-47.1 mm, with an average of 24.6 mm; and a horizontal distance of 22.6-48.1 mm, with an average of 31.7 mm. There was no acetabular or femoral osteolysis in all patients on X-ray films and CT 3D-MPR images at last follow-up, and the Narkbunnam score was 0 in any region. Highly cross-linked polyethylene prosthesis does not increase the risk of long-term complications such as osteolysis after THA.

SHORTENING OSTEOTOMIES OF THE FEMUR DURING TOTAL HIP ARTHROPLASTY FOR DEVELOPMENTAL HIP DYSPLASIA

Total hip arthroplasty (THA) for congenital hip dysplasia (CDH) presents a challenge. In high-grade CDH, key surgical targets include cup placement in the anatomical position and leg length equality. Lengthening of more than 4 cm is associated with sciatic nerve injury, therefore shortening osteotomies are necessary. We present our experience of different shortening osteotomies including advantages and disadvantages of each technique.89 hips, in 61 pts (28 bilateral cases), for high CDH were performed by a single surgeon from 1997 to 2022. 67 patients were female and 22 were male. Age ranged from 38 to 68 yrs. In all patients 5–8cm of leg length discrepancy (LLD) was present, requiring shortening femoral osteotomy. 12 patients underwent sequential proximal femoral resection with trochanteric osteotomy, 46 subtrochanteric, 6 midshaft, and 25 distal femoral osteotomies with simultaneous valgus correction were performed. All acetabular prostheses were placed in the true anatomical position. We used uncemented high porosity cups. Patients were followed up for a minimum of 12 months.All osteotomies healed uneventfully except 3 non-unions of the greater trochanter in the proximal femur resection group. No femoral shaft fractures in proximally based osteotomies. No significant LLD compared to the unaffected or reconstructed side. 2 patients suffered 3 and 5 degrees malrotation of the femur in the oblique sub-trochanteric group. 3 patients suffered transient sciatic nerve palsies.Shortening femoral osteotomies in the treatment of DDH are necessary to avoid injury to the sciatic nerve. In our series, we found transverse subtrochanteric osteotomies to be the most technically efficient, versatile and predictable in their clinical outcome, due to the ability to correct rotation and preserve the metaphyseal bone integrity, allowing for better initial stem stability. Distal femoral osteotomies allowed for controllable correction of valgus knee deformity.

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

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. 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. 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. 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.

Revision of metal-on-metal hip replacements with dual-mobility bearings and acetabular component retention.

In metal-on-metal (MoM) hip arthroplasties and resurfacings, mechanically induced corrosion can lead to elevated serum metal ions, a local inflammatory response, and formation of pseudotumours, ultimately requiring revision. The size and diametral clearance of anatomical (ADM) and modular (MDM) dual-mobility polyethylene bearings match those of Birmingham hip MoM components. If the acetabular component is satisfactorily positioned, well integrated into the bone, and has no surface damage, this presents the opportunity for revision with exchange of the metal head for ADM/MDM polyethylene bearings without removal of the acetabular component. Between 2012 and 2020, across two centres, 94 patients underwent revision of Birmingham MoM hip arthroplasties or resurfacings. Mean age was 65.5 years (33 to 87). In 53 patients (56.4%), the acetabular component was retained and dual-mobility bearings were used (DM); in 41 (43.6%) the acetabulum was revised (AR). Patients underwent follow-up of minimum two-years (mean 4.6 (2.1 to 8.5) years). In the DM group, two (3.8%) patients underwent further surgery: one (1.9%) for dislocation and one (1.9%) for infection. In the AR group, four (9.8%) underwent further procedures: two (4.9%) for loosening of the acetabular component and two (4.9%) following dislocations. There were no other dislocations in either group. In the DM group, operating time (68.4 vs 101.5 mins, p < 0.001), postoperative drop in haemoglobin (16.6 vs 27.8 g/L, p < 0.001), and length of stay (1.8 vs 2.4 days, p < 0.001) were significantly lower. There was a significant reduction in serum metal ions postoperatively in both groups (p < 0.001), although there was no difference between groups for this reduction (p = 0.674 (cobalt); p = 0.186 (chromium)). In selected patients with Birmingham MoM hips, where the acetabular component is well-fixed and in a satisfactory position with no surface damage, the metal head can be exchanged for polyethylene ADM/MDM bearings with retention of the acetabular prosthesis. This presents significant benefits, with a shorter procedure and a lower risk of complications.

Application of modified acetabular anteversion and inclination angles test system in patients undergoing total hip arthroplasty after lumbar fusion

To investigate the accuracy and effectiveness of acetabular cup placement in total hip arthroplasty (THA) after lumbar fusion applying of modified acetabular anteversion and inclination angles test system. A clinical data of 45 patients undergoing THA for osteoarthritis between January 2018 and June 2023 was retrospectively analyzed. All patients had previously received lumbar fusion. The modified acetabular anteversion and inclination angle test system was used in 26 cases (observation group) and not used in 19 cases (control group) during THA. There was no significant difference in baseline data such as gender, age, body mass index, operative side, number of lumbar fusion segments, and preoperative Harris score between the two groups ( P>0.05). The position of acetabular prosthesis, hip function (Harris score), and incidence of complications were compared between the two groups. In the observation group, all acetabular cups were in the safe zone (anteversion angle, 25°-30°) during operation, and 1 acetabular cup (3.85%) was not in the safe zone after operation. In the control group, 9 acetabular cups (47.37%) were not in the safe zone. The postoperative difference between the two groups was significant ( P<0.05). There was no significant difference between intra- and post-operative acetabular inclination angles in the observation group ( P>0.05), and the postoperative acetabular inclination angle was significantly smaller in the observation group than in the control group ( P<0.05). All incisions healed by first intention and no infection occurred. All patients were followed up 6 months. There was no significant difference in Harris score between the two groups at different time point ( P>0.05), and there were significant differences between different time points in the two groups ( P<0.05). No joint dislocation occurred in the observation group during follow-up, while dislocation occurred in 2 cases and femoral impingement syndrome occurred in 1 case of the control group. There was no significant difference in the incidence of complications between the two groups ( P>0.05). For THA patients with lumbar fusion, the ideal placement angle of the acetabular cup can be obtained by using the modified acetabular anteversion and inclination angles test system during operation.

EXPERIMENTAL FAILURE OF HIP ARTHROPLASTY UNDER TORSION LOADING

Polymethylmethacrylate (PMMA) bone cement is strong in compression, however it tends to fail under torsion. Sufficient pressurisation and subsequent interdigitation between cement and bone are critical for the mechanical interlock of cemented orthopaedic implants, and an irregular surface on the acetabular cup is necessary for reasonable fixation at the cup-cement interface. There is limited literature investigating discrepancies in the failure mechanisms of cemented all-polyethylene acetabular cups with and without cement spacers, under torsional loading.In vitro experimental comparison of three groups of polyethylene acetabular prosthesis (PAP) cemented into prepared sawbone hemipelvises:* PAP without PMMA spacers maintaining an equal cement mantle circumferentially. (Group 1 n=3)* PAP without PMMA spacers cemented deliberately ‘bottoming-out’ the implant within the acetabulum. (Group 2 n=3)* PAP with PMMA spacers. (Group 3 n=3)The constructs were tested to torstional failure on a custom designed setup, and statistical analysis done by a one-way ANOVA and Tukey-Welsh test.Group 3 demonstrated superior torsional resistance with a statistically significant torque of 145Nm (SD±12Nm) at failure, compared to group 2 (109Nm, SD±7Nm) and group 1 (99Nm, SD±8Nm). Group 3 experienced failure predominantly at the bone-cement interface, in contrast, Groups 1 and 2 exhibited failure predominantly at the cup-cement interface. There was no significant difference between Group 1 and 2. Qualitative analysis of the failure mode indicates the efficient redistribution of stress throughout the cement mantle, consistent with the greater uniformity of cement.PMMA spacers increase the resistance to torsional failure at the implant-cement interface. Acetabular components without spacers (Groups 1 and 2) failed at the implant-cement interface before the cement-bone interface, at a statistically significantly lower level of torque to failure. Although the PMMA spacers may reduce cement interdigitation at the cement-bone interface the torsional forces required to fail are likely supraphysiological.

Estimation of acetabular cup prosthesis coverage rate in total hip arthroplasty based on X-ray films

To explore the method of accurately estimating the acetabular cup prosthesis coverage rate (hereinafter referred to as "cup coverage rate") in total hip arthroplasty (THA) based on X-ray films, and to determine the effective parameters that can be used to estimate the cup coverage rate. The three-dimensional printed pelvic models were established based on CT data of 16 healthy pelvis, and the acetabular prosthesis were implanted according to conventional THA procedure. The length and width of the uncovered area of the acetabular cup prosthesis were measured by a modified X-ray recording method with a rotating C-arm X-ray machine, and the cup coverage rate was calculated. Then the differences among the traditional anteroposterior X-ray recording method, the modified method, and actual measurement on pelvic model were statistically analyzed. The correlation between the area of the uncovered area of the prosthesis and its width and length was analyzed by using multiple linear regression analysis. The cup coverage rates of traditional method, modified method, and actual measurement were 78.22%±3.36%, 86.74%±3.61%, and 89.62%±2.62%, respectively, with significant differences ( P<0.05). The results of multiple linear regression analysis showed that the width and length were positively linear with the uncovered area of the prosthesis, and the regression equation was as follows: uncovered area of the prosthesis=-21.192+0.248×width+0.140×length, and the coefficient of determination R 2=0.857, P<0.001. Compared with the traditional method, the modified method can more accurately evaluate the cup coverage rate during THA, and the width of the uncovered area of the prosthesis can be used as an effective reference for the cup coverage rate.

A new designed full process coverage robot-assisted total hip arthroplasty: a multicentre randomized clinical trial.

To compare the effect of a new complete robot-assisted total hip arthroplasty (RA-THA) with that of the manual total hip arthroplasty (MTHA) and to verify the accuracy and safety of the former. Overall, 148 patients were enroled from 3 March 2021 to 28 December 2021 in this study and classified into RA-THA ( n =74 patients) and MTHA ( n =74 patients) groups. The sex, age, operative side, BMI, diagnosis, other basic information, operative time, acetabular prosthesis anteversion and inclination, femoral prosthesis anteversion and angulation, femoral prosthesis filling rate, leg length discrepancy (LLD), Harris hip score, and visual analogue scale (VAS) score of the two groups were compared. No significant differences were observed in the two groups regarding sex, age, operative side, BMI, diagnosis, Harris hip score, VAS score, acetabular inclination, acetabular prosthesis anteversion, femoral prosthesis anteversion, combined anteversion, and femoral prosthesis filling rate ( P >0.05). The operative time was significantly longer in the RA-THA group than in the MTHA group (106.71±25.22 min vs. 79.42±16.16 min; t=7.30, P <0.05). The femoral angulation (1.78°±0.64°) and LLD (2.87±1.55mm) in the RA-THA group were significantly lesser than those in the MTHA group (2.22°±1.11° and 5.81±6.27mm, respectively; t=-2.95 and t=-3.88, P <0.05). The complete RA-THA has some advantages over the traditional procedure in restoring the lower limb length and controlling the femoral prosthesis angulation. Thus, this study verifies the accuracy and safety of the robot-assisted system.

Management of acetabular bone loss in revision total hip replacement: a narrative literature review.

Due to growing numbers of primary total hip replacement (THR), the revision THR burden is also increasing. Common indications for revision are osteolysis, infection, instability, and mechanical failure of implants, which can cause acetabular bone loss. Massive acetabular bone defects and pelvic discontinuity are extremely challenging problems. Many techniques have been utilized to address bone loss while maintaining a stable revision THR. Structural allografts, cemented prosthesis, reconstruction cages, and custom triflanged implants have all been used successfully albeit with relatively high complications rates. We have tried to highlight emerging trends to utilize Custom Made Monoflange or Triflange Acetabular Components to reconstruct massive acetabular defects with favourable midterm implant survival, better functional outcomes, relatively lesser complications, and almost similar cost of prosthesis as compared to conventional reconstruction techniques. However, long-term data and study is still recommended to draw a definitive conclusion. In this narrative review article, we searched PubMed and Cochrane for studies on managing acetabular bone loss in revision THR with a focus on recent literature for mid to long-term outcomes and compared results from various studies on different reconstruction methods. Hemispherical cementless acetabular prosthesis with supplemental screws are commonly utilized to manage mild to moderate acetabular bone loss. Recent trends have shown much interest and paradigm shift in patient specific custom triflange acetabular components (CTAC) for reconstructing massive acetabular defects and pelvic discontinuity. Studies have reported high patient satisfaction, improved patient reported daily functioning, high mid-term implant survival, similar complications, and encouraging all cause re-revision rate. However, more prospective and quality studies with larger sample sizes are needed to validate the superiority of CTACs over conventional acetabular implants. There is no consensus regarding the best option for reconstructing massive acetabular defects. Thorough preoperative workup and planning is an absolute requirement for successful revision THR. While most of the moderate acetabular bone loss can be managed with cementless hemispherical acetabular shells with excellent long-term outcomes, reconstructing massive acetabular bone defects in revision THR remains a challenge. Depending on the size and location of the defect, various constucts have demonstrated long-term success as discussed in this review, but complications are not negligible. CTACs provide a treatment for massive bone loss that may be otherwise difficult to achieve anatomic stability with other constructs. Although long-term data is sparse, the cost and complication rate is comparable to other reconstruction methods.

Long-Term Outcome of Metal-on-Metal Total Hip Arthroplasty with Modular Neck Stem.

Background: This study aimed to report the long-term outcomes of total hip arthroplasty (THA) using a Conserve Plus (Wright Medical, Japan) metal-on-metal (MoM) acetabular prosthesis with a modular neck stem. Methods: This study enrolled 50 patients (10 men and 40 women; mean age, 65.8 (39-87) years) who underwent primary THA using a Conserve Plus MoM acetabular prosthesis with a modular neck stem. The preoperative diagnosis in most patients was osteoarthritis. Clinical function of hip joint outcomes was investigated using the Japanese Orthopedic Association (JOA) hip score preoperatively and at the final follow-up. The perfect JOA hip score was 100, while the worst score was 0. Radiological analyses were evaluated during the final follow-up visit. Magnetic resonance imaging (MRI) images were evaluated to screen for pseudotumors in 43 hips postoperatively. Results: Six patients did not visit before their 10-year follow-up for unknown reasons. Therefore, 44 patients were evaluated at a mean of 11-years of follow-up (10-12 years). The mean (±SD) preoperative JOA hip score of 44.2 (±15.5) improved significantly to 85.1 (±12.9) postoperatively at the final follow-up (n = 36 hips, excluding eight revision cases). One patient underwent femoral fixation for a periprosthetic fracture due to trauma that occurred 4 years postoperatively. Spot welds were identified in 93.2% (41/44 hips) of cases. Severe (third- and fourth-degree) stress shielding was identified in 40.9% (18/44 hips) of cases. Twenty-two patients (51.2%) had pseudotumors attributable to MoM articulation based on MRI results, 2 to 10 years after arthroplasty. Three hips showed cup osteolysis (7%) and three showed trochanteric region osteolysis (7%). There were seven cup and/or three stem revisions for aseptic loosening and/or osteolysis at 4 months (with trauma) and 3.3 to 11 years (with pseudotumor) postoperatively. The Kaplan-Meier survivorship for the THA construct in this group was constant at 93.0% and 75.9% at 10 and 12 years after arthroplasty, respectively. The rates of survivorship of revision and loss of follow-up at 10 and 12 years were 83.9% and 66.8%, respectively. Conclusions: In summary, we reported on the long-term treatment results of MoM THA, precautions based on our cohort's findings, and the measures taken to address these issues, such as revision replacement and its outcomes. Clinical scores revealed good outcomes during the mean 11-year follow-up period. However, the prevalence of pseudotumors (PTs) was 51.2%. Some cases required revisions even after the 10 years following surgery. This is because in MoM THA, PT occurrence increases over time, and as a result, there were cases in which revised THA was required even after 10 years.

Personalized digital simulation‑assisted acetabular component implantation in revision hip arthroplasty.

The number of artificial total hip revision arthroplasties is increasing yearly in China, and >50% of these cases have acetabular defects. Accurately locating and quantifying the bone defect is one of the current challenges of this surgery. Thus, the objective of the present study was to simulate acetabular implantation with the aid of Mimics 17.0 software (Materialise NV) in patients with loosened acetabular prosthesis, to evaluate the 'ideal acetabular center' and the 'actual acetabular center' to guide the choice of prosthesis and surgical method. From January 2017 to June 2021, the present study included 10 hips from 10 patients [seven men (seven hips) and three women (three hips)]. In all patients, the Mimics software was applied to simulate the dislocation of the femoral prosthesis and acetabular prosthesis implantation before surgery; calculate the height difference between the 'ideal acetabular center' and the 'actual acetabular center' to assess the bone defect; confirm the size of the acetabular prosthesis, abduction angle, anteversion angle and bone coverage of the acetabular cup; and measure the intraoperative bleeding and postoperative follow-up Harris score of the hip joint. After statistical analysis, the present study revealed that digital simulation assistance could improve the accuracy of hip revision acetabular prosthesis implantation, reduce postoperative shortening of the affected limb, especially for surgeons with relatively little experience in hip revision surgery, and greatly reduce the occurrence of complications such as hip dislocation because of poor postoperative prosthesis position.

Digital protractor as an intraoperative guide to cup anteversion in total hip arthroplasty

IntroductionTo explore if digital protractor could guide the anteversion of acetabular cup during primary THA and make it consistent with preoperative.MethodsWe retrospectively reviewed 172 cases of primary THA with direct anterior approach (DAA) over 2 years. The anteversion of acetabular cup were measured from computed tomography (CT) scan preoperative and de-identified plain radiographs postoperative by two blinded investigators who were not involved in the surgery. The effect of the digital protractor on the anteversion was determined using regression analysis.ResultsThe mean anteversion for the THAs in digital protractor group was 15.5°and 21.4°in control group (P < 0.01). The mean anteversion bias for the THAs in digital protractor group was 1.59° and 6.63° in control group (P < 0.01).Regression analysis identified a 10.7% difference in anteversion due to the use of digital protractor (P < 0.01), and THAs performed without digital protractor were six times more likely to result in anteversion of > 25°. The correlation coefficient for the interobserver reliability of the measurement of the two investigators was 0.94.ConclusionThe digital protractor is a practical tool in the DAA for THA to determine the anteversion of the acetabular prosthesis.

Development and validation of multiple linear regression models for predicting total hip arthroplasty acetabular prosthesis

PurposeTo establish a multivariate linear equation to predict the diameter (outer diameter) of the acetabular prosthesis used in total hip arthroplasty.MethodsA cohort of 258 individuals who underwent THA at our medical facility were included in this study. The independent variables encompassed the patients' height, weight, foot length, gender, age, and surgical access. The dependent variable in this study was the diameter of the acetabular prosthesis utilized during the surgical procedure. The entire cohort dataset was randomly partitioned into a training cohort and a validation cohort, with a ratio of 7:3, employing the SPSS 26.0 software. Pearson correlation analysis was conducted to examine the relationships between the patients' height, weight, foot length, gender, age, surgical access, and the diameter of the acetabular prosthesis in the training cohort. Additionally, a multiple linear regression equation was developed using the independent variables from the training cohort and the diameter of the acetabular prosthesis as the dependent variable. This equation aimed to predict the diameter of the acetabular prosthesis based on the patients' characteristics. The accuracy of the equation was evaluated by substituting the data of the validation cohort into the multiple linear equation. The predicted acetabular prosthesis diameters were then compared with the actual diameters used in the operation.ResultsThe correlation analysis conducted on the training cohort revealed that surgical access (r = 0.054) and age (r = −0.120) exhibited no significant correlation with the diameter of the acetabular prosthesis utilized during the intraoperative procedure. Conversely, height (r = 0.687), weight (r = 0.654), foot length (r = 0.687), and sex (r = 0.354) demonstrated a significant correlation with the diameter of the acetabular prosthesis used intraoperatively. Furthermore, a predictive equation, denoted as Y (acetabular prosthesis diameter in mm) = 20.592 + 0.548 × foot length (cm) + 0.083 × height (cm) + 0.077 × weight (kg), was derived. This equation accurately predicted the diameter within one size with an accuracy rate of 64.94% and within two sizes with an accuracy rate of 94.81%.ConclusionAnthropometric data can accurately predict the diameter of acetabular prosthesis during total hip arthroplasty.

Custom-made implants for massive acetabular bone loss: accuracy with CT assessment

BackgroundCustom-made implants are a valid option in revision total hip arthroplasty to address massive acetabular bone loss. The aim of this study was to assess the accuracy of custom-made acetabular implants between preoperative planning and postoperative positioning using CT scans.MethodsIn a retrospective analysis, three patients who underwent an acetabular custom-made prosthesis were identified. The custom-made designs were planned through 3D CT analysis considering surgical points of attention. The accuracy of intended implants positioning was assessed by comparing pre- and postoperative CT analyzing the center of rotation (CoR), anteversion, inclination, screws, and implant surface in contact with the bone.ResultsThe three cases presented satisfactory accuracy in positioning. A malpositioning in the third case was observed due to the posterization of the CoR of the implant of more than 10 mm. The other CoR vectors considered in the third patient and all vectors in the other two cases fall within 10 mm. All the cases were positioned with a difference of less than 10° of anteversion and inclination with respect to the planning.ConclusionsThe current case series revealed promising accuracy in the positioning of custom-made acetabular prosthesis comparing the planned implant in preoperative CT with postoperative CT.

Accuracy analysis of artificial intelligence-assisted three-dimensional preoperative planning in total hip replacement.

This study aims to assess the outcome of total hip arthroplasty (THA) using artificial intelligence (AI)-assisted three-dimensional (3D) preoperative planning technology in terms of predicting prosthesis size, acetabular cup positioning, and lowerlimb length restoration. Between January 2020 and July 2022, a total of 161 patients (101 males, 60 females; mean age: 57.6±10.5 years; range, 31 to 80 years) who underwent primary unilateral THA were retrospectively analyzed. The patients were divided into two groups as those who were treated with AI-assisted 3D preoperative planning technology (the observation group, n=95) and patients who were treated with traditional two-dimensional (2D) X-ray template planning technology (the control group, n=66). The accuracy of the planning was based on the consistency of the preoperative planning and intraoperative models. The difference between the observation group and the control group was statistically significant in terms of the accuracy of the preoperative planning of acetabular prostheses (54% vs. 38%, p=0.048) and femoral prostheses (64% vs. 44%, p=0.011), with both values significantly higher in the observation group. The mean inclination angle, anteversion angle, and limb length discrepancy (LLD) in the observation group were 36.85°±4.82°, 12.10°±5.33°, and 2.18±2.70 mm, respectively, while those in the control group were 35.06°±6.07°, 10.95°±5.09°, and 4.42±3.85 mm, respectively. There was a statistically significant difference between the two groups in terms of inclination angle and LLD (p<0.05 for both), but there was no significant difference in terms of anteversion angle (p>0.05). In the observation group, 86.3% (82/95) of acetabular cups were implanted within the Lewinnek safe zone (72.7% [48/66] in the control group), while 83.2% (79/95) were within the Callanan safe zone (69.7% [46/66] in the control group), with both values higher in the observation group (p<0.05). Overall, AI-assisted 3D preoperative planning is superior to traditional 2D X-ray template planning for predicting prosthesis size, and it also has the advantage in terms of acetabular cup positioning and lower-limb length restoration.

Short-term outcome of artificial intelligence-assisted preoperative three-dimensional planning of total hip arthroplasty for developmental dysplasia of the hip compared to traditional surgery.

This study aims to assess the short-term outcome of total hip arthroplasty for treating developmental dysplasia of the hip (DDH) using artificial intelligence (AI)-assisted three-dimensional (3D) preoperative planning technology. Between January 2020 and July 2022, a total of 61 patients with DDH (31 males, 30 females, mean age: 59.2±10.4 years; range, 35 to 78 years) were retrospectively analyzed. The patients were divided into two groups as those in the observation group of AI-assisted 3D preoperative planning technology (n=34) and the control group of traditional two-dimensional X-ray template planning technology (n=27). Perioperative data of the patients were recorded and analyzed. All patients were followed for more than one year, and no hip dislocation, aseptic loosening, periprosthetic fracture, periprosthetic infection or revision occurred. The accuracy of the planning was based on the agreement between the preoperative planning model and the intraoperative model. The accuracy of preoperative planning for the acetabular prosthesis and femoral prosthesis in the observation group was significantly higher than in the control group. No statistically significant difference was found in the postoperative abduction (p=0.416) and anteversion (p=0.225) between the groups. In the observation group, 91.2% of the acetabular cups were implanted within the Lewinnek safe zone (66.7% in the control group) and 88.2% were within the Callanan safe zone (63% in the control group). There was a statistically significant difference between the two groups in terms of the postoperative lower-limb length discrepancy (p=0.004), which was significantly improved in both groups compared to preoperative values (p<0.01 for all). The postoperative Harris hip score in both groups was significantly improved compared to preoperative scores (p<0.01); however, there was no statistically significant difference between the two groups (p=0.098). Our study results suggest that AI-assisted 3D preoperative planning is evidently more successful than traditional 2D X-ray template planning for predicting prosthesis size. This method seems to be advantageous in acetabular cup positioning, as well as in lower-limb length restoration.