APP-guided assessment of acetabular defects in hip revision arthroplasty: a structured approach to a complex situation

Introduction Acetabular defect recognition and classification remains a challenging field of practice for orthopedic surgeons. Recently, the Acetabular Defect Classification (ADC) has been introduced to provide a reliable, reproducible and intuitive classification system. In order to improve ease of use and efficiency of the ADC, a browser-based application has been created. We hypothesized that the ADC application can improve rating performance of non-specialists (medical students) to achieve good inter- and intra-rater agreement and will compare favorable to the results of specialists (experienced surgeons) without the help of the application. Materials and methods The ADC is based on the integrity of the acetabular rim and the supporting structures. It consists of four main types of defects ascending in severity. These defects are further subdivided in A–C, narrowing down defect location. 80 randomized radiographs were graded according to ADC by three non-specialists (medical students) with help of the ADC application and by three specialists (orthopedic surgeons) without help of the application to evaluate the difference in inter-rater agreement between groups. To account for intra-rater agreement, the rating process was repeated after a reasonable wash-out period. Results Inter-rater and intra-rater agreement within the non-specialist group rated lower when compared to the specialist group while still falling into the good agreement range. The student group presented with k values of 0.61 for inter-rater agreement and 0.68 for intra-rater agreement, while the surgeon group displayed k values of 0.72 for inter-rater agreement and 0.83 for intra-rater agreement. Conclusion The app-guided assessment of acetabular defects offers a promising innovative approach to simplify complex situations. It makes the challenging field of acetabular revision arthroplasty more approachable especially for less experienced surgeons and offers insight and guidance in the planning stage as well as intra-operative setting.

Acetabular revision using ReadiGraft® BLX Putty and cortical/cancellous bone chips

Acetabular bone loss presents a challenge to the revision total hip arthroplasty surgeon. It is described a technique of stressing the acetabular bone intra-operatively to access for pelvic discontinuity and the use of allograft to fill the bone gap. Three radiographic criteria are assessed on the AP radiograph for pre-operative classification according to the Paprosky system. This paper describes the pre-operative assessment, the acetabular defect classification and the surgery to achieve a successful outcome.

Treatment of an extensive acetabular defect in a patient with aseptic instability of a total hip arthroplasty

The aim of the study is to demonstrate, using a clinical example, the possibility of treating a patient with a severe acetabular defect by performing a one-stage revision arthroplasty using an individual design. Materials and methods. A 45-year-old female patient was admitted with complaints of pain, limitation of movement in the right hip joint, and gait disturbance. From anamnesis at the age of 5 years, reconstructive operations of the hip joints were performed. In 1991, CITO performed primary total arthroplasty of the right hip joint with an endoprosthesis from ESKA Implants. In 1998, due to the instability of the acetabular component of the total endoprosthesis of the right hip joint, revision arthroplasty was performed, and the cup was placed with a cement fixation. In 2001, for left-sided dysplastic coxarthrosis, primary total arthroplasty of the left hip joint was performed. In 2012, due to the instability of the total endoprosthesis of the left hip joint, revision arthroplasty was performed using an ESI anti-protrusion ring (ENDOSERVICE) with a cement cup and a Zweimller-type femoral component; the femur defect was repaired using a fresh frozen cortical graft. In October 2019, instability of the total endoprosthesis of the right hip joint was revealed, for which revision endoprosthetics was performed using an individual acetabular component. Results. The HHS index before revision arthroplasty was 21 points, after 1 month after surgery 44 points, after 3 months after surgery 65, after 6 months 82. Quality of life was assessed according to the WOMAC scale: before surgery 73 points, after 1 month after surgery 54 points, after 3 months 31, after 6 months 15 points. At the time of the last consultation, the patient moves with a cane, lameness persists, associated with scar reconstruction and atrophy of the gluteal muscles. Conclusion. The use of individual structures allows to restore the support ability of the lower limb and the function of the hip joint in the case of an extensive defect of the pelvic bones of the pelvic discontinuity type.

Reverse augmentation technique in hip revision arthroplasty: a new strategy for the management of acetabular reconstruction

Background The principle of acetabular total hip revision (THR) is based on acetabular reconstruction and restoration of the center of rotation. The use of augmentation in high cranial acetabular defects combined with a cementless revision shell was studied sufficiently. This study aimed to report a case with the use of an augment inside a cementless revision shell as a reverse augmentation technique. Methods We describe the case of an 86-year-old female patient with a massive acetabular defect during second revision for total hip arthroplasty (THA). Two problems occurred: (1) a fixed cemented stem with a nonmodular head size of 33 mm and (2) a high acetabular defect with an elevated rotation center. Results With the distraction technique, allograft filling was used to reconstruct the acetabular defect. A cementless revision shell (REDAPT, Smith and Nephew) with a size of 78 mm was used to stabilize the defect. Locking screws placed cranially and distally were used to stabilize the cup for secondary osseointegration. An augment was placed inside the cup to reconstruct the rotation center. A customized polyethylene liner (outer diameter, 54 mm/inner diameter, 33 mm) was positioned below the augment in the revision cup to reconstruct the center of rotation. An 18-month postoperative X-ray analysis showed a stable construct with full secondary osseointegration. Conclusion This is the first report of an augment used for a reverse technique inside a cementless shell to restore the center of rotation with the use of a customized polyethylene liner. This might be a reliable option for reconstruction of the center of rotation in large cementless revision cups in acetabular Paprosky type III defects. This technical note shows the possibility of using an augment as a reverse technique in a cementless revision cup.

Acetabular reaming and sartorius muscle pedicle iliac bone grafting in the treatment of developmental dysplasia of the hip in older children: a retrospective study of 15 patients with more than two years follow-up

Purpose Despite the early diagnosis and treatment of developmental dysplasia of the hip (DDH), some older children still need open reduction. It is usually difficult to get a satisfactory reduction particularly in patients with acetabular defect. The purpose of this study was to evaluate the short-term outcomes of acetabulum reaming and sartorius muscle pedicle iliac bone grafting in the treatment of older children with DDH and acetabular defect. Methods The records of 15 patients with DDH (mean age 113.9 months (sd 29); 17 hips) who were treated with the reported technique between February 2015 and January 2017 were retrospectively reviewed. All patients acquired regular clinical and radiographic follow-ups, and alterations in the acetabular index, centre-edge angle and acetabular head index were measured. Joint function and radiographic results were evaluated with McKay and Severin modified criteria, respectively. Results A total of 15 patients were followed up for mean 32.4 months (sd 6.9). The percentages of excellent and good conditions were 94.1% (16/17) according to the Severin modified criteria and 88.2% (15/17) according to the McKay modified criteria. Avascular necrosis of the femoral head and redislocation only occurred in one hip. No cases of ankylosis or bone graft absorption occurred during the follow-up. Conclusion Reaming the acetabulum and sartorius muscle pedicle iliac bone grafting for repairing the acetabular defect can recover the arcuate structure by increasing the volume of the acetabulum, which is beneficial for achieving a concentric reduction. The short-term outcome was satisfactory, while the long-term results need to be further observed. Level of Evidence IV – retrospective study

Comparison of the Primary Stability of Porous Tantalum and Titanium Acetabular Revision Constructs

Adequate primary stability of the acetabular revision construct is necessary for long-term implant survival. The difference in primary stability between tantalum and titanium components is unclear. Six composite hemipelvises with an acetabular defect were implanted with a tantalum augment and cup, using cement fixation between cup and augment. Relative motion was measured at cup/bone, cup/augment and bone/augment interfaces at three load levels; the results were compared to the relative motion measured at the same interfaces of a titanium cup/augment construct of identical dimensions, also implanted into composite bone. The implants showed little relative motion at all load levels between the augment and cup. At the bone/augment and bone/cup interfaces the titanium implants showed less relative motion than tantalum at 30% load (p < 0.001), but more relative motion at 50% (p = n.s.) and 100% (p < 0001) load. The load did not have a significant effect at the augment/cup interface (p = 0.086); it did have a significant effect on relative motion of both implant materials at bone/cup and bone/augment interfaces (p < 0.001). All interfaces of both constructs displayed relative motion that should permit osseointegration. Tantalum, however, may provide a greater degree of primary stability at higher loads than titanium. The clinical implication is yet to be seen