Bilateral Protrusio Acetabuli in an Elderly Female Patient: The Plain Radiographic Features and a Case Report

Protrusion acetabuli is the medial protrusion of the acetabulum in to the pelvic cavity, also known as arthrokatadysis, more common in females and classified etiologically as primary (idiopathic) and secondary forms. This is a 66-year-old female patient that presented for a plain radiograph of the pelvis and hip joints from a peripheral healthcare center on account of pain and inability to stand and move her waist and hips bilaterally, reduced movement of the legs and pain in the knees for more than three-year duration of onset. The plain radiograph of the pelvis and both hip joints demonstrate reduced density of the demonstrated bones, medial protrusion of the medial wall of the acetabulum in to the pelvic cavity bilaterally (distance between the imaginary Kohler’s line and medial acetabular wall is about 22mm bilaterally; Degree: III), obliteration of the hip joints bilaterally, thickening and sclerosis of the acetabular walls and other articular margins, subarticular cysts on the femur, acetabulum and pelvic bones. The patient had no coexisting condition like rheumatoid arthritis, Marfan’s syndrome and psoriatic arthritis. A diagnosis of bilateral idiopathic protrusio acetabuli was made. The patient was advised on bilateral total hip arthroplasty to improve the symptoms. We report a case of bilateral idiopathic protrusion acetabuli in an elderly female patient in order to describe the features of this condition radiographically.

Is Restoration of Hip Center Mandatory for Total Hip Arthroplasty of Protrusio Acetabuli?

Background: While initial fixation by a press-fit of the acetabular cup is essential for the durability of the component, restoration of the hip center has been known as an attributable factor for implant survival and successful outcome. In protrusio acetabuli (PA), it might be difficult to obtain both restoration of the hip center and the press-fit of the acetabular cup simultaneously during total hip arthroplasty (THA). We tested a hypothesis that medialized cup, if press-fitted, does not compromise the implant stability and outcome after cementless THA of PA. Methods: We reviewed 27 cementless THAs of 23 patients with PA. During THA, we prioritized press-fit of the cup than the hip center restoration. A press-fit was obtained in 24 hips. In the remaining 3 hips, a press-fit could not be obtained, and reinforcement acetabular components were used. The hip center was restored in 18 cups; 15 primary cups and 3 reinforcement components, while it was medialized in 9 cups. We compared implant stability and modified Harris hip score (mHHS) between the 2 groups at a mean of 5.2 (2-16) year follow-up. Results: One restored reinforcement cup was loose. The remaining 26 cups; 17 restored cups and 9 medialized press-fitted cups, remained stable. The final mHHS was similar between the restored group and the medialized group (81.8 ± 10.8 vs 83.6 ± 12.1, p = 0.498). Conclusions: Press-fitted cups, irrespective of hip center restoration, rendered implant stability and favorable results. Initial fixation of the cup is more important than the restoration of hip center.

AUSTIN MOORE PROSTHESIS IN THE MANAGEMENT OF FRACTURE NECK OF FEMUR IN AN ELDERLY POPULATION.

Introduction: Intracapsular fractures of the proximal femur form a major share of fractures in the 77 elderly. Hip replacement arthroplasty (partial or total) is emerging as a most viable treatment option, and in that, hemiarthroplasty with the Austin Moore Prosthesis is among the most commonly employed. In our study, we have made an attempt to assess the functional status at long term follow up after hemiarthroplasty with the AMP, used in the treatment of fracture neck of femur in the elderly population, and to substantiate the use of the prosthesis in modern day orthopaedic practice. Materials and : A retrospective study was carried out in patients above the age of 60 years, who had been diagnosed with non-pathological fracture neck of femur, treated operatively with hemiarthroplasty using the Austin Moore prosthesis in a tertiary care centre. A minimum follow up period of two years was considered. All the patients were evaluated clinically, and wherever possible, radiologically. Functional outcome was assessed based on the Harris Hip scoring system, and the results were analysed. Radiologically, an attempt was made to assess, among others, the amount of protrusio acetabuli at follow up, and femoral offset changes following hemiarthroplasty with the AMP. Results: In our study, we observed a positive functional outcome (excellent or good) in 9(45%) patients, with fair result in 6(30%) and poor in 5(25%). However, when pain alone was taken as criteria for assessment, upto 14(75%) patients had none to slight pain at follow up, and only 1(5%) patient had marked pain. Walking distance was significantly reduced in 6(30%) patients, who were either confined indoors or bedridden, but in only 1(5%) of them, the cause for the decreased ambulatory status was implant or procedure related (pain). Among the complications, 1 patient had a post-operative periprosthetic fracture that healed subsequently, 2 patients had marked osteolysis around the stem of the prosthesis, and only 1 patient had a radiological evidence of protrusio acetabuli. Discussion: Hemiarthroplasty with Austin Moore Prosthesis for fracture neck of femur remains a fairly good treatment option in elderly patients.

Location of Intra- and Extra-articular Hip Impingement Is Different in Patients With Pincer-Type and Mixed-Type Femoroacetabular Impingement Due to Acetabular Retroversion or Protrusio Acetabuli on 3D CT–Based Impingement Simulation

Background: Diagnosis and surgical treatment of hips with different types of pincer femoroacetabular impingement (FAI), such as protrusio acetabuli and acetabular retroversion, remain controversial because actual 3-dimensional (3D) acetabular coverage and location of impingement cannot be studied via standard 2-dimensional imaging. It remains unclear whether pincer hips exhibit intra- or extra-articular FAI. Purpose: (1) To determine the 3D femoral head coverage in these subgroups of pincer FAI, (2) determine the impingement-free range of motion (ROM) through use of osseous models based on 3D-computed tomography (CT) scans, and (3) determine the osseous intra-and extra-articular 3D impingement zones by use of 3D impingement simulation. Study Design: Cross-sectional study; Level of evidence, 3. Methods: This is a retrospective, comparative, controlled study involving 70 hips in 50 patients. There were 24 patients (44 hips) with symptomatic pincer-type or mixed-type FAI and 26 patients (26 hips) with normal hips. Surface models based on 3D-CT scans were reconstructed and compared for hips with acetabular retroversion (30 hips), hips with protrusio acetabuli (14 hips), and normal asymptomatic hips (26 hips). Impingement-free ROM and location of impingement were determined for all hips through use of validated 3D collision detection software based on CT-based 3D models. No abnormal morphologic features of the anterior iliac inferior spine were detected. Results: (1) Mean total femoral head coverage was significantly ( P < .001) increased in hips with protrusio acetabuli (92% ± 7%) and acetabular retroversion (71% ± 5%) compared with normal hips (66% ± 6%). (2) Mean flexion was significantly ( P < .001) decreased in hips with protrusio acetabuli (104°± 9°) and acetabular retroversion (116°± 6°) compared with normal hips (125°± 13°). Mean internal rotation in 90° of flexion was significantly ( P < .001) decreased in hips with protrusio acetabuli (16°± 12°) compared with normal hips (35°± 13°). (3) The prevalence of extra-articular subspine impingement was significantly ( P < .001) higher in hips with acetabular retroversion (87%) compared with hips with protrusio acetabuli (14%) and normal hips (0%) and was combined with intra-articular impingement. The location of anterior impingement differed significantly ( P < .001) between hips with protrusio acetabuli and normal hips. Conclusion: Using CT-based 3D hip models, we found that hips with pincer-type and mixed-type FAI have significantly larger femoral head coverage and different osseous ROM and location of impingement compared with normal hips. Additionally, intra- and extra-articular subspine impingement was detected predominantly in hips with acetabular retroversion. Acetabular rim trimming during hip arthroscopy or open surgical hip dislocation should be performed with caution for these hips. Patient-specific analysis of location of impingement using 3D-CT could theoretically improve diagnosis and planning of surgical treatment.

The Prevalence of Radiographic Findings of Structural Hip Deformities for Femoroacetabular Impingement in Patients With Hip Pain

Background: Radiography is the initial imaging modality used to evaluate femoroacetabular impingement (FAI), and diagnostic radiographic findings are well-established. However, the prevalence of these radiographic findings in patients with hip pain is unknown. Purpose: The purpose was 3-fold: (1) to determine the overall prevalence of radiographic FAI deformities in young patients presenting with hip pain, (2) to identify the most common radiographic findings in patients with cam-type FAI, and (3) to identify the most common radiographic findings in patients with pincer-type FAI. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A geographic database was used to identify patients aged 14 to 50 years with hip pain between the years 2000 to 2016. The following were evaluated on radiographs: cam type: typical pistol grip deformity, alpha angle >55°; pincer type: crossover sign (COS), coxa profunda or protrusio acetabuli, lateral center edge angle (LCEA) ≥40°, Tönnis angle <0°; and mixed type: both cam- and pincer-type features. Posterior wall sign (PWS) and ischial spine sign (ISS) were also evaluated. The prevalence of each was determined. Descriptive statistics were performed on all radiographic variables. Results: There were 1893 patients evaluated, and 1145 patients (60.5%; 1371 hips; 374 male and 771 female; mean age, 28.8 ± 8.4 years) had radiographic findings consistent with FAI. Of these hips, 139 (10.1%) had cam type, 245 (17.9%) had pincer type, and 987 (72.0%) had mixed type. The prevalence of a pistol grip deformity and an alpha angle >55° was 577 (42.1%) and 1069 (78.0%), respectively. The mean alpha angle was 66.9°± 10.5°. The prevalence of pincer-type radiographic findings was the following: COS, 1062 (77.5%); coxa profunda, 844 (61.6%); ISS, 765 (55.8%); PWS, 764 (55.7%); Tönnis angle <0°, 312 (22.8%); LCEA ≥40°, 170 (12.4%); and protrusio acetabuli, 7 (0.5%). Conclusion: The overall prevalence of radiographic findings consistent with FAI in young patients with hip pain was 60.5%. Radiographic findings for mixed-type FAI were the most prevalent. The most common radiographic finding for cam-type FAI was an alpha angle >55°. The most common radiographic finding for pincer-type FAI was the COS.