Acetabular Side Research Articles

Benefits of thin‐shelled acetabular components for metal‐on‐metal hip resurfacing arthroplasty

The theoretical advantage of using thinner acetabular components in hip resurfacing has not yet been clinically verified. Our purpose was to test the hypothesis of bone conservation and assess the effects of using a thinner acetabular component on hip biomechanics and clinical outcome. We compared the bone conservation, biomechanical results, and functional outcomes between hips in 35 patients who received bilateral metal-on-metal resurfacing arthroplasties with acetabular components of 5 mm thickness on one side and 3.5 mm thickness on the other. Acetabular abduction angle and acetabular anteversion were measured using Ein-Bild-Röentgen-Analysis software. Medial acetabular wall thickness and position of the hip center of rotation were measured using Image J software. The change in position of the hip center of rotation was minimal and did not reach significance. Thin-shelled components showed greater bone conservation on the acetabular side measured by an increase in the medial acetabular wall thickness. Bone conservation on the femoral side was achieved as well with thin shells. Range of motion, pain scores, and complication rates were comparable. No appreciable difference was found in bone-cup radiographic appearance between the two types of components. These data suggest that patients can experience good clinical outcomes for resurfacing with either thin or thick-shelled acetabular components. However, thin-shelled components preserve acetabular bone stock and allow the use of a larger femoral component. The use of thinner acetabular components is an improvement in bone conservation for a hip resurfacing design.

Polyethylene in total hip arthroplasty: half a century in the limelight

Polyethylene in total hip arthroplasty: half a century in the limelight

Projection angle for C-arm-assisted insertion of posterior acetabular column screws

Objective To explore the optimal projection angle when cannulated screws are placed into the posterior acetabular column under the help of a C-arm fluoroscopic unit. Methods Twenty acetabular sides in 10 corpses were scanned with CT to find the scan plane which contained the maximum cross section of the femoral head. On this scan plane, we measured angle α which was between the posterior surface of the posterior column and the coronal plane, and angle β which was between the posterior surface of the posterior column and the acetabular fringe plane. Results Angle α was 28. 2°± 2. 3° and angle β was 95.4°± 5.3°. Conclusions When the projection direction is paralleled with the posterior surface of the posterior column, the angle between the bulb and the coronal plane is about 30°, 15° more than the obturator oblique view. Compared with the obturator oblique view, 30° can show more exactly the spatial relation between the screw and the posterior surface of the posterior column. The direction perpendicular to the acetabulum fringe plane can also be considered for projection. Key words: Surgical procedures, minimally invasive; Tomography, spiral computed; Tomography, X-ray computed; Bone nails

Operative treatment for pincer type femoroacetabular impingement:a case report.

Femoroacetabular impingement (FAI) is a condition characterized by the impingement of the femur and acetabulum. In Japan, this disorder has become recognized gradually. Here we report a rare case of surgically treated FAI, associated with an osseous protrusion on the acetabulum of a 30-year-old female. Plain computed tomography (CT) and reconstructive 3D-CT images clearly demonstrated an anterolateral bony protrusion. Hip arthroscopy showed no degeneration of the cartilage on either the femoral or acetabular side, but degeneration at the edge of labrum was observed in the region of the bony protrusion. The complete removal of the bony protrusion under hip arthroscopy was thus considered impracticable, and a small skin incision was therefore made anteriorly to approach the acetabulum. The Short-Form 36-Item Health Survey (SF-36) revealed improvement in all scores.

Antibiotics-impregnated cement spacers in the first step of two-stage revision for infected totally replaced hip joints: report of ten trial cases

BackgroundPeriprosthetic infection is one of the serious complications after total hip arthroplasty (THA). This study analyzed the perioperative and postoperative status of patients who underwent antibiotics-impregnated cement spacer technique in the first step of the two-stage revision. MethodsTen joints of the nine patients (mean age, 65 years; seven women, two men) received two-stage revision as a result of infection that appeared after primary THAs in seven joints, aseptic revision in one, and recurrent type in two. An antibiot-ics-impregnated cement spacer made by a mold system was applied in the femoral side of all joints. An acetabular spacer was made by hand using a cup gauge in eight joints with extensive tissue loss. ResultsThe change of leg length after the first stage was –2.2 mm, and range of hip flexion was 72° on average, respectively. Patients could walk with crutches after the first stage, except one patient with simultaneous infections of both hips and one with fracture of the cement spacer. One fracture of femoral cement spacer, and one dislocation of femoral spacer accompanied by fracture of acetabular cement spacer and curable recurrent infection, were found. in all cases of the second-stage procedure, the acetabular side was reconstructed with allogeneic bone graft with cross plate and that of the femur was by impaction bone grafting method. In the latest follow-up, reconstructed implants were stable. Seven patients could walk without any supportive devices and two could walk with the support of a T-cane. ConclusionsAn antibiotics-impregnated cement spacer in the first step of the two-stage revision was effective not only to compensate tissue loss after removal of the implants and to minimize discrepancy of leg length, but also to contribute to improvement of perioperative and postoperative daily activities of the patient’s life as well as treatment of the infection.

Hip resurfacing: expectations and limitations

Hip resurfacing: expectations and limitations

(ii) Implant removal in revision hip surgery

Implant removal is a major part of revision hip surgery. A complication, such as fracture or perforation during implant removal, more common in the presence of surrounding osteopenia, can compromise subsequent reconstruction. Similarly, care must be taken to avoid additional bone loss during implant removal. Various techniques are available on both the femoral and acetabular sides that can facilitate the procedure. Recent developments in instrumentation can prove helpful. In this article the techniques are reviewed. In addition, the importance of pre-operative planning and exposure is discussed. The techniques used to remove both cemented and uncemented implants are detailed with examples, illustrations and practical tips. The overall aim of the article is to make this potentially complicated procedure less challenging for the surgeon, but more importantly, to reduce complication rates in implant removal, improving clinical outcomes for patients.

Three-dimensional Computerized Tomographic Analysis of the Deformity of Lateral Growth Disturbance of Proximal Femoral Physis

Lateral growth disturbance of the proximal femoral physis after treatment of developmental dysplasia of the hip, also known as type 2 avascular necrosis, has been described in a 2-dimensional (2D) plane with standard radiographs. It is not well described in the 3-dimensional plane using 3D computed tomography (CT) scan. The purpose of this study was to define the anatomy of the proximal femur after the lateral growth disturbance of the proximal femoral physis with 3D CT scans. Ten patients (11 hips) with lateral growth disturbance of the proximal femoral physis after treatment for developmental dysplasia of the hip (9 hips) and extracorporeal membrane oxygenation (2 hips), were studied with 2D and 3D CT methods. CT was done at an average age of 12.5 years (range, 9.8 to 16.69). In addition to the typical valgus configuration in the coronal plane, increased antetorsion of the femur (10 of 11 hips) and increased anteversion of the femoral head (8 of 11 hips) were a common finding seen in the transverse plane. In 6 of 7 hips for which the CT scan was performed before the closure of the capital femoral epiphysis, the physeal bridge was seen to be located in the anterolateral (5 hips) or posterolateral (1 hip) area of the proximal femoral physis. The version of the femoral head was correlated to the location of the physeal bridge. Acetabular dysplasia was seen in 4 hips. In the 3D reconstruction view, flexion deformity of the femoral head was seen in 6 hips and lack of coverage at the anterolateral portion of the femoral head was observed in 6 hips. The treating surgeon should be aware of the often marked antetorsion and also anteversion of the femoral head and neck associated with lateral growth disturbance of the proximal femoral physis. This knowledge allows surgical planning to correct rotational and sagittal plane correction of the proximal femur, which will allow normalizing hip mechanics. Acetabular side correction also may be needed if acetabular dysplasia is present. Level III, diagnostic study.

Hip Arthroplasty up to the Age of 30 and Considerations in Relation to Subsequent Revision

We reviewed a series of 17 hip arthroplasties in 16 patients performed when the patients were 30 years old or younger who presented to us for consideration of revision. The mean age was 23.1 years (14 to 30) at the initial arthroplasty. At the time of the original procedure there were 4 sequelae of septic arthritis, 7 old traumatic hip injures, 3 cases of developmental dysplasia (DDH), 1 case of rheumatoid arthritis (RA), 1 steroid-induced avascular necrosis, and 1 old slipped upper femoral epiphysis (SUFE) The implants inculded 11 total hip arthroplasties (THA), 3 double cup arthroplasties,1 bipolar arthroplasty,1 monopolar arthroplasty and 1 cup arthroplasty. The cause for revision lay on the acetabular side in 16 cases and on the femoral side in 6 cases (some had failure on both sides of the joint). There was one revision for recurrent dislocation. The patients had undergone a mean of 1.1 procedures (range 0-3) before the primary arthroplasty. There was a mean interval of 10.6 years (2-33)between the arthroplasty and the revision and the patients had a mean of 1.9 further revision procedures(0 to 4). Complications of revision surgery inculded 1 case of sepsis, 2 recurrent dislocations and 8 re-revisions. Postel and Merle d'Aubigne (PMA) score increased from 10.1 to 14.6 at an mean follow-up of 5.4 years (1 to 20). The typical patient was male (11/17) having had the first arthroplasty at age 23 for trauma sequelae (7/17), a revision at 34 (acetabular failure (16/17). At age 46.4, and after 1.9 secondary procedures hip scores were not exceptional. Such generally disappointing results arose from errors in implant selection or technical mistakes. Careful surgery is critical, and the way of life of the patient may need to be modified.

The choice of prosthesis in the second stage revision with infections of artificial hip replacement.

Objective To study surgical technique and choice of prosthesis in the second stage revision with infections of artificial hip replacement. Methods From January 1999 to December 2007, 32 patients with infections after unilateral hip replacement underwent the second stage revision, including 19 males and 13 females, with a mean age of 56 years (32-80 years). Bone defect in acetabular side by Paprosky classification were 13 cases(type Ⅰ), 9 cases(Ⅱ A), 5 cases(Ⅱ C), 1 cases(ⅢA), 4 cases(Ⅲ B). Cemeritless prosthesis was applied in 22 cases with type Ⅰ-Ⅱ A bone defect. Cemented prosthesis was applied in 10 cases with type Ⅱ C-Ⅲ B bone defect followed by acetabular reconstruction by allograft, mesh and cage or ring. Bone defect in femoral side by Paprosky classification were 11 cases(Ⅰ), 4 cases(Ⅱ A), 1 case (Ⅱ B), 5 cases(Ⅱ C), 6 cases(Ⅲ A), 3 cases(Ⅲ B), 2 cases(Ⅲ C). Cemented prosthesis was applied in 8 cases with type Ⅱ C (5 cases) and Ⅲ B(3 cases) bone defect. Cementless prosthesis was applied in the other cases, including proximal fixation(5 cases with type Ⅰ ), extensive prouscoating(6 cases with Ⅰ, 4 cases with Ⅱ A, 1 case with Ⅱ B) and distal fixation (6 cases with Ⅲ A, 2 cases with Ⅲ C). Results All cases were followed up i-10 years. Among them, 2 patients suffered recurrent infections, and underwent debridement and conservative treatment, with sinus tract at final follow-up. Harris score were 65 and 78, respectively. The other 30 cases got satisfactory results. Harris score was increased from average 48 (31-78) preoperatively to 85 (80-95) postoperatively. At final follow-up, 30 prosthesis had no subsidence, migration and loosening on X-ray images. Conclusion The success rate of two stage revision with infections of artificial hip replacement is satisfactory. The key point of revision is to choose proper prosthesis according to bone defect type after the infection is under better control. Key words: Arthroplasty,replacement,hip; Infection; Hip prosthesis; Reoperation

Does Hip Resurfacing Require Larger Acetabular Cups Than Conventional THA?

Hip resurfacing is femoral bone preserving, but there is controversy regarding the amount of bone removed at the acetabular side. We therefore compared the implanted acetabular cup sizes in primary THAs between two resurfacing devices and a conventional press-fit cup using a series of 2134 THAs (Allofit cup 1643 hips, Durom Hip Resurfacing 249 hips, and Birmingham Hip Resurfacing 242 hips). The effects of patient demographics and cup position in the horizontal plane also were assessed. After controlling for gender, patients were matched for height, weight, body mass index, and age. The mean size for Allofit cups was smaller than the sizes for Durom and Birmingham Hip Resurfacing cups in women (49.9 mm, 51.6 mm, 52.3 mm, respectively) and men (55.1 mm, 56.7 mm, 57.8 mm; respectively). Although patient height was associated with the implanted cup size, the cup position in the horizontal plane had no effect on the size used. Larger cups were used with hip resurfacing than for THA with a conventional press-fit cup. However, additional studies are needed to determine whether these small differences have any clinical implications in the long term. The association of cup size and patient height should be considered in future studies comparing component sizes among different implants. Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Acetabular metal backed fatigue due to severe wear before revision

The polymer UHMWPE is widely applied as bearing element at acetabular side in total hip arthroplasty. In some designs, a metal backed is placed between the polymer and bone. Today, wear of the polymer is the major cause of revisions. In some extreme cases, the metallic cephalic component and the metal backed experience contact wear promoting wear debris, which has catastrophic consequences. In this paper, it was analyzed a retrieved acetabular component of total hip arthroplasty re-revised due to metal backed rupture after gross metal wear. Failure analysis shown fatigue of the metal backed. To simulate the stress distribution over the metal backed and polymer liner, a finite element analysis was performed taking account metal backed wall reduction due to wear. It was observed that the decrease in the metal backed thickness increase stresses at the metal/polymer interface and the stresses which enhance polymer wear. It was also observed that wear produces a change of the location of maximum stress, from the contact periphery to the middle section of the hemispherical wall. This change promotes failure due to bending of the metal backed. Revision of metal backed shall be always made when metal backed wear is observed, even when it is well fixed in the bone.

How Accurately Can the Acetabular Rim Be Trimmed in Hip Arthroscopy for Pincer-Type Femoral Acetabular Impingement: A Cadaveric Investigation

The purpose of this study was to evaluate the precision of central hip arthroscopy in the assessment and treatment of pincer-type femoroacetabular impingement (FAI) avoiding the posterolateral portal, with its close proximity to the main arterial blood supply of the femoral head, the medial circumflex femoral artery. Seven human cadaveric hips underwent arthroscopic trimming of the acetabular labrum and rim along a preoperatively defined 105 degrees arc of resection for treatment of a presumed pincer-type lesion. After the arthroscopic procedure, all specimens were dissected and measured for evaluation of the location, quantity, and quality of the area undergoing resection. The difference between the actual and planned arc of resection was 18.7 degrees +/- 4.7 degrees (range, 2 degrees to 34 degrees). This was mainly because of a lack of accuracy in the presumed posterior starting point (PSP), with a mean deviation of 19 degrees +/- 3.4 degrees (range, 10 degrees to 36 degrees). Correlation analysis showed that variance in the arc of resection was mainly dependent on the PSP (r = 0.739, P = .058). Central hip arthroscopy is a feasible option in treating anterosuperior pincer-type FAI by use of the anterior and anterolateral portals only. This cadaveric study showed that there is a significant risk of underestimating the actual arc of resection compared with the planned arc of resection for posterosuperior pincer-type lesions because of the modest accuracy in determining the PSP of the resection. Accurate preoperative planning and arthroscopic identification of anatomic landmarks at the acetabular side are crucial for the definition of the appropriate starting and ending points in the treatment of pincer-type FAI. Whereas anterosuperior pincer-type lesions can be addressed very precisely with our technique, the actual resection of posterosuperior lesions averaged 19 degrees less than the planned resection, which may have clinical implications.

Hip resurfacing arthroplasty for secondary osteoarthritis after developmental dysplasia of hip

To study the clinical results of metal on metal hip resurfacing arthroplasty for developmental dysplasia patients. From March 2005 to December 2006, 34 cases of developmental dysplasia patients (Crowe I, Crowe II) were attempted to have metal on metal hip resurfacing arthroplasty. There were 29 females (32 hips), 5 males (5 hips). The average age was 45 (26 - 57) years old. Radiographic and clinical evaluations were taken at 6 weeks, 3 months, 1 year and then once a year postoperatively. The average Harris score was 35 (25 - 44). Hip flexion was 101 degrees , abduction 24 degrees , adduction 15 degrees . Three patients were turned to total hip arthroplasty during operations. Thirty-one patients (34 hips) received hip resurfacing surgery. These 31 patients were followed for average 21.4 months (12 - 33 months). The average Harris score was 94 (82 - 100) at the latest follow-up, and there was statistical difference compared with the preoperative score (P < 0.01). Hip flexion increased to 133 degrees , abduction to 48 degrees , adduction to 26 degrees . No radiolucency line was found at both acetabular and femoral sides in all the patients. The average abduction angle of acetabular cup was 43 degrees (40 degrees - 53 degrees ), and the average stem shaft angle was 139 degrees (130 degrees - 145 degrees ). The short term result is excellent. While the mid to long term results for hip resurfacing arthroplasty in developmental dysplasia patients are still looking forward, and the meticulous surgical technique and strict patient selection are the key of the good results.

Current management of femoro-acetabular impingement

Summary Femoro-acetabular impingement (FAI) is a common cause of hip pain in young adults. The condition can result in labral tears, articular cartilage lesions and eventual osteoarthritis of the hip. FAI results from an abnormal bony shape of the femoral head / neck or the acetabular rim or both, which causes contact (impingement) between the neck and acetabular rim during movement of the hip joint. Two different mechanisms are described, although a combination of the two mechanisms is frequent. Cam impingement is caused by an abnormality of the femoral head and neck; principally a reduction in offset between the head and the neck. Pincer impingement is caused by an abnormality on the acetabular side, with either excessive retroversion of the acetabulum or an unduly prominent anterior wall. Either problem is associated with the development of chondral lesions (especially in the acetabulum) and labral pathology. Patients with FAI usually present with deep groin pain exacerbated by hip flexion. X-rays typically show an anterior impingement bump on the anterior femoral neck on a horizontal beam lateral, abnormalities of head/neck offset or an excessively prominent anterior acetabular wall. Surgery is the treatment of choice and this involves open or arthroscopic bony resection to improve femoral head-neck clearance with either resection or refixation of the damaged labrum. Both the femoral head/neck junction and the acetabular rim may require bony resection. Such surgery yields good symptomatic relief, but whether the surgery prevents the development of osteoarthritis in the hip in the long term is currently unknown.

The use of a dual-articulation acetabular cup system to prevent dislocation after primary total hip arthroplasty: analysis of 384 cases at a mean follow-up of 15 years

The concept of a dual articulation acetabular cup was developed by Prof. Bousquet in 1974. This concept has been shown to provide high stability after revision and primary total hip arthroplasty. The aim of our study was to evaluate the incidence of prosthetic instability in a consecutive homogeneous series of 384 primary dual mobility cups. Incidence of instability and implant survival were evaluated. Mean follow-up was 15.3 years (range, 12-20). There was no early or late instability. On the acetabular side there were 13 aseptic loosenings, 14 intraprosthetic dislocations, and seven polyethylene wear cases that required replacement of the liner. The cumulative survival rate of the dual-articulation acetabular cup using surgical revision for aseptic loosening as the endpoint was 95.9% +/- 4.1% at 18 years postoperatively. Our series proves the good long term behaviour of dual-articulation acetabular components in primary arthroplasty. Their excellent survivorship rate and the absence of episodes of prosthetic instability increase our confidence in this concept.

Improved Accuracy and Low Fracture and Dislocation Rate with the Two-Incision Total Hip Replacement Technique

We report our early experience with the two-incision hip replacement technique. On the acetabular side, we studied whether a nonoriginating surgeon early in his experience with the minimally invasive two-incision technique for total hip arthroplasty could place components with appropriate accuracy. Thirty-five consecutive hip replacements performed using the two-incision technique were closely matched by height and weight with an equal number of control small-incision arthroplasties. Both leg-length accuracy and abduction angle were significantly superior with the two-incision technique. We also studied our rate of intraoperative femoral calcar or shaft fracture, and early complication rate in 120 two-incision arthroplasties. No displaced shaft or calcar fractures occurred, though two calcar cracks occurred in the first 10, and one nondisplaced shaft split occurred which required no operative treatment. No hip dislocated, and no early infections or femoral or sciatic nerve palsies occurred.

Second generation of metal-on-metal cemented total hip replacements: 12 years of clinical and biological follow-up

The second generation of metal-on-metal prostheses appeared at the end of the 1980’s as a serious alternative to metal on polyethylene bearing couples. Short-term clinical results were promising; however certain questions remain concerning clinical, radiological and biological aspects. Release of chromium and cobalt from the bearing couple is one of these aspects. The aim of this study is to analyse the results of a series of 97 cemented total hip prostheses comprising a titanium femoral stem and the Metasul® metal-metal bearing couple. Mean follow-up was nine years (7–12 years). Complications were marked by 12 revisions, out of which two were for recurrent early dislocations, eight for clinical and radiological failure, and two for worrying radiological alterations. During these revisions, we observed a serious infiltration of metal debris four times, leading to an alternative strategy using an alumina-alumina bearing couple. Three more revisions are planned for rapidly evolving radiological alterations. Thirty implants showed radiological signs of preoccupying deterioration on the acetabular side. Eight segmentary femoral osteolysis have been observed. Twelve patients suffer from recurrent subluxation. Concerning the global evolution of metal serum levels, cobalt remains stable after five years. The values are three to four times above those of a non-exposed subject, but largely below toxic ratios. The evolution of serum chromium levels is similar to cobalt. Implantation of two prostheses in one same patient leads to significant increase in serum metal ratios. This series raises questions concerning the reliability of the metal-on-metal bearing couple. Osteolysis is an unsolved problem. Today, cemented fixation is debatable although this series doesn’t allow this parameter to be held directly responsible. Nothing points to any shortcomings concerning the taper fixation or the metallurgy of the femoral stem. The study of the serum metal levels seems a good indicator of the impingement situations and the functioning of the bearing couple.

Hydroxyapatite coating has no interest on grit-blasted Alloclassic-CSF titanium threaded cups

Hydroxyapatite (HA) coating is not a sine qua non condition to achieve long-lasting acetabular cup fixation on the acetabular side of cementless primary THA, where HA acts only as an adjuvant for early osteo-integration, but is not a guarantee for a long-lasting bone-implant anchorage. Of a series of 633 Alloclassic-CSF grit blasted and non-HA-coated titanium threaded cups, ten only were revised for all causes (five for infection) with no aseptic loosening. Thirteen-year survivorship with acetabular cup revision for any reason and aseptic loosening as end point was 98% (95% confidence interval, 86.9–99.7%) and 100% (90.4–100%), respectively. Failure of non-smooth cementless acetabular components might not be related to unability to achieve secure early osteo-integration, but to the difficulty to maintain it with time, either due to: 1) poor liner locking mechanism; 2) conventional PE wear; or mainly 3) to acetabular bone stress shielding that could weaken the supporting bone at longer follow-up. None of these three factors can be addressed by HA coating. In fact, better strain distribution to the acetabular bone to prevent stress shielding osteopenia and the bearing materials really matter.

Fatigue in cemented acetabular replacements

The long-term stability of cemented total hip replacements critically depends on the lasting integrity of the bond between the cement and the bone, often referred to as fixation. In vitro assessment of fatigue behaviour of cemented acetabular, as opposed to femoral, replacements is of particular interest due to the more aggressive nature of late “loosening” found in acetabular replacements, reported to be three times that in femoral cases. Quantitative assessment of fatigue behaviour of cement fixation on acetabular side has been difficult due to the complexity of the pelvic bone geometry and the associated loading conditions. The purpose of this work was to develop a framework for in vitro assessment of fatigue integrity of cement fixation in acetabular replacements. To this end, a newly developed hip simulator was utilised, where the direction and the magnitude of the hip contact force (Bergmann et al., 2001) under typical physiological loading conditions including normal walking and stair climbing were simulated for the first time. Preliminary hip simulator experimental results seem to be consistent with those from constant amplitude fatigue tests, in that debonding at the bone–cement interface is identified as the main failure mechanism, although the numbers of cycles to failure are significantly reduced in samples tested in the hip simulator. Finite element analysis of implanted bone samples was carried out, where the effects of loading mode on the stress distribution in the cement mantle and at the bone–cement interface were evaluated. The effects of model geometry on the stress state and failure modes were also examined and discussed based on the results of the present and previously published work.