Time elapsed from definitive diagnosis to surgery for osteonecrosis of the femoral head: a nationwide observational study in Japan.

OBJECTIVES: This study documents the time elapsed from the diagnosis of osteonecrosis of the femoral head (ONFH) to surgery, exploring the factors that influence ONFH severity. DESIGN: Retrospective observational study of a nationwide database. SETTING: The Kaplan-Meier method with log-rank tests was applied to examine the period from definitive diagnosis of ONFH to surgery using any surgery as the end point. For bilateral cases, the date of the first surgery was the endpoint. PARTICIPANTS: This study included 2074 ONFH cases registered in 34 university hospitals and highly specialised hospitals of the multicentre sentinel monitoring system of the Japanese Investigation Committee between 1997 and 2018. MAIN OUTCOME MEASURE: The primary outcome was the time from diagnosis to surgery. The secondary outcome was the proportion of subjects remaining without surgery at 3, 6 and 9 months, and at 1, 2 and 5 years after diagnosis. RESULTS: The median time to surgery was 9 months (IQR 4-22 months) after diagnosis of ONFH. The time to surgery was significantly shorter in the alcohol alone group and the combined corticosteroid and alcohol group than in the corticosteroid alone group (p=0.018 and p<0.001, respectively), in early stage ONFH with no or mild joint destruction (stages II and III, p<0.001), and with joint preserving surgery (p<0.001). The proportion without surgery was 75.8% at 3 months, 59.6% at 6 months, 48.2% at 9 months, 40.5% at 1 year, 22.2% at 2 years and 8.3% at 5 years. CONCLUSION: ONFH has been considered to be an intractable disease that often requires surgical treatment, but the fact that surgery was performed in more than half of the patients within 9 months from diagnosis suggests severe disease with a significant clinical impact. TRIAL REGISTRATION NUMBER: Chiba University ID1049.

Does difference in stem design affect accuracy of stem alignment in total hip arthroplasty with a CT-based navigation system?

The efficacy of a computed tomography (CT)-based navigation system to accurately position the stem for intended alignment is unclear. In addition, the influence of stem design on the accuracy of insertion is unknown. We therefore retrospectively compared the accuracy and precision for the intended alignment of two different designs of femoral stem which were implanted with or without the navigation system. Forty-nine total hip arthroplasties (THAs) using a tapered wedge stem and 91 THAs using an anatomic stem were evaluated for the navigation group. Thirty-three THAs using the tapered wedge stem and 15 THAs using the anatomic stem were controls for the non-navigation group. Differences between postoperative measurement and preoperative planning were compared among the groups. In the navigation groups, accuracy (mean absolute difference) and precision (95% limits of agreement) of stem anteversion were 4.3° and ± 10.1° in the tapered wedge stem and 3.1° and ± 6.9° in the anatomic stem. In the non-navigation groups, these were 6.0° and ± 15.2° and 4.8° and ± 12.4°, respectively. The accuracy and precision in the navigation groups were significantly superior to those in the non-navigation group, and those in the anatomic stem group were significantly superior to those in the tapered wedge group. Using the CT-based navigation system, the accuracy and precision for intended stem anteversion were improved. When compared under guidance of navigation system, the accuracy and precision for intended stem anteversion in the anatomic stem were superior to those in the tapered wedge stem.

Effect of improved navigation performance on the accuracy of implant placement in total hip arthroplasty with a CT-based navigation system.

A computed tomography (CT)-based navigation system is one of the support tools to place implant with appropriate alignment and position in total hip arthroplasty (THA). To determine whether the higher performance of the navigation would further improve the accuracy of implant placement in the clinical setting, we retrospectively compared the navigation accuracy of two different versions of a navigation system. The newer version of the navigation system had an upgraded optical sensor with superior positional accuracy. Navigation accuracy, defined as differences between postoperative measurements on CT images and intraoperative records on the navigation system, of 49 THAs performed with the newer version of the navigation system was compared with that of 49 THAs performed with the older version. With the newer version, the mean absolute accuracy (95% limits of agreement) of implant alignment was 1.2° (± 3.3°) for cup inclination, 1.0° (± 2.4°) for cup anteversion, 2.0° (± 4.9°) for stem anteversion, and 1.1° (± 2.4°) for stem valgus angle. The accuracy of the implant position was 1.5 mm (± 3.1 mm), 1.3 mm (± 3.0 mm), and 1.5 mm (± 3.1 mm) for cup x-, y-, and z-axes, respectively, 1.6 mm (± 3.2 mm), 1.4 mm (± 2.9 mm), and 1.5 mm (± 2.7 mm) for stem x-, y-, and z-axes, respectively, and 2.4 mm (± 4.5 mm) for leg length discrepancy. The values for the newer version were significantly more accurate with less variation compared to those of the older version. With upgraded navigation performance, more accurate implant placement was demonstrated in the clinical setting.

Does Pelvic Sagittal Inclination in the Supine and Standing Positions Change Over 10 Years of Follow-Up After Total Hip Arthroplasty?

BACKGROUND: Functional anteversion and inclination of the cup change as the pelvic sagittal inclination (PSI) changes. The purposes of this study were to investigate the chronological changes of PSI during a 10-year follow-up period after total hip arthroplasty (THA) and to report the characteristics of patients who showed a greater than 10° change in the PSI from the supine to the standing position. METHODS: The subjects were 70 patients who were followed up for 10 years after THA. PSI values in the supine and standing positions were measured by 2D-3D matching using computed tomography images and pelvic radiographs. PSI values before THA and 1, 5, and 10 years after THA were compared in both the supine and standing positions. RESULTS: Supine PSI showed less than 5° of change, whereas standing PSI showed a significant decrease with time over the 10-year period. Although 43% of patients with less than 10° of difference in the PSI between the supine and standing positions before THA increased PSI posteriorly (reclining) more than 10° in standing from the supine position at 10 years, no late dislocation was observed. CONCLUSION: Supine PSI showed no significant change, but standing PSI showed a significant increase posteriorly with time over a 10-year period. However, this PSI change did not reach the level that it caused negative consequences such as late dislocation. The pelvic position in the supine position might still be a good functional reference position of the pelvis for aiming to achieve proper cup alignment at 10 years.

Effects of coordinate-system construction methods on postoperative computed tomography evaluation of implant orientation after total hip arthroplasty.

OBJECTIVE: In total hip arthroplasty, it is important to assess postoperative implant orientation. The computed tomography-based (CT-based) three-dimensional (3D) templating method using 3D preoperative planning software is generally recommended. In this method, postoperative implant orientation within a bony coordinate system can be measured by overlaying a 3D computerized model of the implant on a real postoperative CT image of the implant. The bony coordinate system consists of several reference points (RPs) marked on a CT image of the bone surface. Therefore, preoperative and postoperative coordinate systems do not always match. We investigated how the difference between coordinate systems constructed from RPs chosen by manual methods (M1 and M2) and those constructed by the computer matching method influences the results of measurement validation. METHODS: In M1, postoperative RPs were chosen without a specific tool in a single planning module. In M2, postoperative RPs were chosen with as little deviation as possible from preoperative RPs, verifying preoperative RPs on another monitor. RESULTS: M1 and M2 produced mean errors in acetabular cup inclination of 0.7° ± 0.5° and 0.5° ± 0.3°, respectively, and mean errors in cup anteversion of 1.3° ± 1.2° and 0.5° ± 0.4°, respectively, which were statistically significant differences. M1 and M2 produced mean errors in femoral stem anteversion of 2.4° ± 2.0° and 2.7° ± 2.1°, respectively, not a significant difference, but these errors were larger than errors in cup orientation. DISCUSSION: We recommend referring to preoperative RPs when choosing postoperative RPs. Surgeons must be aware that for evaluation of postoperative stem anteversion, manual methods may produce considerable error.

Hip range of motion during daily activities in patients with posterior pelvic tilt from supine to standing position.

In most patients with hip disorders, the anterior pelvic plane (APP) sagittal tilt does not change from supine to standing position. However, in some patients, APP sagittal tilt changes more than 10° posteriorly from supine to standing position. The purpose of this study was to both examine APP sagittal tilt and investigate the hip flexion and extension range of motion (ROM) required during daily activities in these atypical patients. Patient-specific 4-dimensional (4D) motion analysis was performed for 50 hips from 44 patients who had undergone total hip arthroplasty. All patients divided into two categories, such as atypical patients for whom the pelvis tilted more than 10° posteriorly from supine to standing position preoperatively (19 hips from 18 patients) and the remaining typical patients (31 hips from 26 patients). The required hip flexion and extension angles did not differ significantly between atypical patients and typical patients. In conclusion, the hip flexion ROM during deep bending activities and hip extension ROM during extension activities required in those atypical patients with pelvic tilt more than 10° backward from supine to standing position did not shift in the direction of extension.

Risk of edge-loading and prosthesis impingement due to posterior pelvic tilting after total hip arthroplasty.

BACKGROUND: Proper implant orientation is essential for avoiding edge-loading and prosthesis impingement in total hip arthroplasty. Although cup orientation is affected by a change in pelvic tilt after surgery, it has been unclear whether surgeons can prevent impingement and edge-loading by proper positioning by taking into account any change in pelvic alignment associated with alteration of hip range of motion. METHODS: We simulated implant orientation without edge-loading and prosthesis impingement, even with a change in pelvic tilt and associated change in hip range of motion after surgery, by collision detection using implant models created with computer-aided design. FINDINGS: If posterior pelvic tilting with a corresponding hyperextension change in hip range of motion after surgery remains within 10°, as occurs in 90% of cases, surgeons can avoid edge-loading and impingement by correctly orienting the implant, even when using a conventional prosthesis. However, if a 20° change occurs after surgery, it may be difficult to avoid those risks. INTERPRETATION: Although edge-loading and impingement can be prevented by performing appropriate surgery in most cases, even when taking into account postoperative changes in pelvic tilt, it may also be important to pay attention to spinal conditions to ensure that pelvic tilting is not extreme because of increasing kyphosis.

Cement Removal from the Femur Using the ROBODOC System in Revision Total Hip Arthroplasty.

Introduction. The perforation and fracture of the femur during the removal of bone cement in revision total hip arthroplasty (THA) are serious complications. The ROBODOC system has been designed to selectively remove bone cement from the femoral canal, but results have not been reported yet. The purpose of our study was to evaluate the clinical and radiographic results of revision THA using the ROBODOC system for cement removal. Materials and Methods. The subjects comprised 19 patients who underwent revision THA using the ROBODOC system. The minimum duration of follow-up was 76 months (median, 109 months; range, 76-150 months). The extent of remaining bone cement on postoperative radiography, timing of weight bearing, and the complications were evaluated. Results. The mean Merle d'Aubigne and Postel score increased from 10 points preoperatively to 14 points by final follow-up. Bone cement was completely removed in all cases. Full weight bearing was possible within 1 week after surgery in 9 of the 19 cases and within 2 months in all remaining cases. No instances of perforation or fracture of the femur were encountered. Conclusions. Bone cement could be safely removed using the ROBODOC system, and no serious complications occurred. Full weight bearing was achieved early in the postoperative course because of circumferential preservation of the femoral cortex.

Accuracy of angle and position of the cup using computed tomography-based navigation systems in total hip arthroplasty.

OBJECTIVE: The objectives of this study were to evaluate the accuracy of computed tomography (CT)-based navigation and to investigate whether the level of surgeon experience affects the accuracy of cup positioning under navigation. METHODS: This study investigated 117 hips in 103 patients who underwent primary total hip arthroplasty (THA) by 7 surgeons using a CT-based navigation system. Pre- and postoperative CT images were matched using a volume registration technique. Postoperative cup angles and positions were then measured using the same pelvic coordinates, and results were compared for experienced and inexperienced surgeons. RESULTS: The mean absolute error of the cup angle was 1.8 ± 1.6° for inclination and 1.2 ± 1.1° for anteversion. The mean absolute errors of cup position were 1.9 ± 1.5 mm, 1.4 ± 1.2 mm, and 1.9 ± 1.3 mm on the x-, y- and z-axes, respectively. No significant differences in accuracy were identified between experienced and inexperienced surgeons. CONCLUSIONS: The absolute spatial error of cup position was ≤ 2 mm for each axis, and the angle error was ≤ 2° for the angles of inclination and anteversion. This navigation system could therefore help surgeons perform accurate cup placement irrespective of the surgeon's level of experience.

Factors predicting change in pelvic posterior tilt after THA.

In total hip arthroplasty, steep cup inclination should be avoided because it increases the risk of edge loading. Pelvic posterior tilt should be carefully monitored because it increases cup inclination and anteversion, leading to edge loading or impingement. The authors evaluated how much the pelvic tilt angle changes from the supine position referenced in planning for cup orientation preoperatively to the standing position 1 year after total hip arthroplasty (Δref). The pelvic tilt angle was measured in 124 patients who underwent total hip arthroplasty due to osteoarthritis, and the mean Δref was -9.5°±5.3° (range, -23° to 5°). Preoperative compression fractures, spondylolisthesis, and disk-space narrowing were predictive of increased pelvic posterior tilt after total hip arthroplasty. The authors mathematically calculated how much change in pelvic posterior tilt was clinically possible with the original cup alignment, which ranged from 40° to 45° of radiographic inclination and 0° to 30° radiographic anteversion to more than 50° of inclination. Even if the maximum posterior tilt (23°) occurred, no edge loading would occur in almost half of those original cups. Surgeons should aim for 40° of inclination. When the original cup inclination was 40°, edge loading was prevented. Edge loading caused by steep cup inclination can be prevented by adjusting the cup orientation to account for predicted pelvic tilting, but spinal alignment must also be considered because lumbar kyphosis can increase postoperative pelvic posterior tilt.

Modular acetabular reconstructive cup in acetabular revision total hip arthroplasty at a minimum ten year follow-up.

PURPOSE: Modular acetabular reconstructive cups have been introduced in an attempt to offer initial rigid fixation by iliac lag screws and ischial pegs, to support bone grafts with a flanged metal socket, and to restore original hip center in acetabular revision. The purpose of this study was to clarify minimum ten year follow-up results of this cup system with morsellised allografts in revision cases. METHODS: We retrospectively investigated 54 acetabular revisions at a mean of 11 years (range, ten to 14 years). The indications were Paprosky's type 2B (eight hip), 2C (eight hips), 3A (23 hips), 3B (nine hips), and 4 (six hips). RESULTS: Using aseptic loosening as the endpoints, the survival rate was 89.3 % (95 % CI 81-98). Radiographically, one type 3A hip, three type 3B hips and one type 4 hip showed aseptic loosening while no type 2 hips or no cemented cups showed loosening. CONCLUSIONS: The modular reconstructive cups for acetabular revision showed bone stock restoration and stable implantation.

Detecting cause of dislocation after total hip arthroplasty by patient-specific four-dimensional motion analysis.

BACKGROUND: Dislocation is a major complication after total hip arthroplasty. Prosthesis impingement is considered to be an important cause of dislocation because impingement marks are more frequently found on retrieved cups or liners in patients who have undergone revision surgery because of dislocation (80%-94%) than in those who have undergone reoperation for other reasons (51%-56%). However, it remains a question whether impingement marks are the cause of dislocation or are instead its result. To clarify the issue, it is necessary to confirm noninvasively whether the point of impingement matches the patient's hip position when dislocation occurs. METHODS: Using four-dimensional patient-specific analysis, we recorded prosthesis impingement in 10 hips with instability after primary total hip arthroplasty when the patients reproduced the dislocation-causing motion. FINDINGS: We found prosthesis impingement to be related to at least instability in 6 of 10 hips with dislocation after primary total hip arthroplasty and in 4 of 4 hips that underwent revision surgery for recurrent dislocation. All impingements occurred between the anterior wall of the liner and the stem neck in posterior dislocation and between the posterior wall of the liner and the stem neck in anterior dislocation. Revision surgery in 1 of those 4 hips revealed 2 impingement marks on the retrieved liner that closely matched the prosthesis impingement point and the dislocation pathway of the metal head on the liner that were detected earlier during motion analysis. INTERPRETATION: Prosthesis impingement is an important factor in dislocation after total hip arthroplasty.

Does CT-based navigation improve the long-term survival in ceramic-on-ceramic THA?

BACKGROUND: Although navigated THA provides improved precision in implant positioning and alignment, it is unclear whether these translate into long-term implant survival. QUESTIONS/PURPOSES: We compared survivorship, dislocation rate, and incidence of radiographic failures such as loosening and bearing breakage after THA with and without navigation at a minimum 10-year followup. METHODS: We retrospectively reviewed 46 patients (60 hips) and 97 patients (120 hips) receiving THA with or without a CT-based navigation system, respectively, using cementless THA ceramic-on-ceramic bearing couples. There were no differences in age, sex, diagnosis, height, weight, BMI, or preoperative clinical score between groups. We evaluated survivorship, mode of acetabular and femoral component fixation, osteolysis, and implant wear or breakage at a minimum followup of 10 years (average, 11 years; range, 10-13 years). RESULTS: Survival at 13 years was 100% with navigation and 95.6% (95% CI, 88.4%-98.4%) without navigation. With navigation, all cups were placed within a zone of 40° (range, 30°-50°) of radiographic inclination and 15° (range, 5°-15°) of radiographic anteversion; without navigation, 31 cups (26%) were placed outside this zone. Hips treated without navigation had a higher rate of dislocation (8%) than the navigated cases (0%). Revision was performed in four nonnavigated cases, all of which showed evidence of neck impingement on the ceramic liner. Moreover, seven other cases without navigation showed posterior neck erosion on radiographs. These 11 impingement-related mechanical complications correlated with cup malorientation, and the incidence of impingement-related complications was higher in nonnavigated cases. CONCLUSIONS: Navigation reduced the rates of dislocation and impingement-related mechanical complications leading to revision in cementless THA using ceramic-on-ceramic bearing couples over a minimum 10-year followup. LEVEL OF EVIDENCE: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Anatomical hip range of motion after implantation during total hip arthroplasty with a large change in pelvic inclination.

The supine functional pelvic plane is the recommended reference pelvic plane for acetabular cup planning in navigation-assisted total hip arthroplasty. However, it is unclear whether it can be used in patients with a large preoperative positional change in pelvic inclination (PC) from the supine to the standing position because it is unknown whether these patients have a different hip range of motion (ROM). We measured the anatomical hip ROM after implantation by computed tomography-based navigation in 91 patients and found it to be similar between those with a small PC (<10°) and those with a large PC (≥10°). There was no significant correlation between ROM and preoperative PC. The supine functional pelvic plane is adequate for cup planning whether the PC is small or large.

Dynamic measurements of hip movement in deep bending activities after total hip arthroplasty using a 4-dimensional motion analysis system.

Although deep hip bending activities are often required in Asian populations because of traditional lifestyles and religious practices, few have examined the required hip range of motion (ROM) in these activities after total hip arthroplasty (THA). We performed postoperative motion analysis to evaluate the differences in required ROMs between Japanese-style and Western-style deep hip bending activities, to investigate whether prosthetic impingement would occur during these activities and to clarify the necessity for precautions in these activities after THA. Japanese-style activities did not require larger hip ROMs than Western-style ones, and all required hip flexion angles were less than 120°. Prosthetic impingement was not observed, with a safety margin 10° or higher until impingement in any directions of flexion, adduction, or internal rotation for any activities. Thus, particular postoperative precautions for Japanese-style activities are not required.

Eleven- to 14-year follow-up results of cementless total hip arthroplasty using a third-generation alumina ceramic-on-ceramic bearing.

To analyze long-term survivorship of cementless total hip arthroplasties (THAs) with the third-generation alumina ceramic-on-ceramic bearing, 100 consecutive THAs between 1996 and 1998 were reviewed. One cup and 2 stems were revised due to aseptic loosening. Another cup showed chipping of the acetabular liner at 8 years and required cup revision. The remaining hips showed stable bone ingrowth fixation with no osteolysis at the final follow-up. The 14-year survivorship as the end point of revision was 97.9% for the cup, 97.8% for the stem, and 95.7% for the overall implants, respectively. We conclude that cementless THA with the third-generation ceramic-on-ceramic hip bearing provided an excellent survivorship and eliminated periprosthetic osteolysis for 11 to 14 years.

[Successful completion of left total hip arthroplasty by inhibitor neutralization therapy in a hemophilia B patient with high responding inhibitor].

Major surgery in hemophilia patients has been facilitated by the development of coagulation concentrates. However, it is still difficult to manage bleeding during major surgery in patients with inhibitors to FVIII/IX. In addition, there have been few reports of major surgery in hemophilia B with high responding inhibitors. We report a 26-year-old hemophilia B patient with high responding factor IX inhibitor who demonstrated severe hemophiliac arthropathy in his left hip joint. Total hip arthroplasty was performed with a high dose of FIX followed by recombinant FVIIa. His inhibitor titer was decreased from 111 BU/ml to 1.0 BU/ml at surgery by avoiding the use of FIX concentrates. Thus, we could use high dose FIX for the management of surgical bleeding. Anamnestic response occurred on the 7th day after surgery and FIX concentrates were switched to recombinant FVIIa. The whole process was safely managed without any excess bleeding or adverse effects. The successful use of high dose FIX followed by recombinant FVIIa suggests that even major surgery could be safely performed in hemophilia B patients with a low titer of high responding inhibitors.

Modular neck for prevention of prosthetic impingement in cases with excessively anteverted femur.

BACKGROUND: It is important to adjust stem anteversion in cases of excessive femoral version to avoid prosthetic impingement-related complications in total hip arthroplasty. Although modular necks are considered an effective solution, their application in cases with wide variations in femoral anteversion remains to be elucidated. This study aimed to simulate the effects of different modular necks on prevention of prosthetic impingement due to excessive femoral anteversion. METHODS: We investigated range of motion without prosthetic impingement by collision detection using implant computer-aided design models of the ANCA-Fit system. FINDINGS: Modular necks could provide an adequate range of motion in cases with up to 60° of femoral anteversion. However, few alternative necks were available in cases with excessive femoral anteversion, while many options could be used for femoral offset and version control in cases with average amounts of femoral anteversion without prosthetic impingement. INTERPRETATION: We conclude that modular necks might provide a marginal advantage over other options such as cemented, conical or modular stems for cases with an excessively anteverted femur, although they could help to maintain the femoral offset in some cases with average femoral anteversion.

Cementless modular total hip arthroplasty with subtrochanteric shortening osteotomy for hips with developmental dysplasia.

BACKGROUND: The purpose of this retrospective study was to analyze the functional and radiographic results of cementless, modular total hip arthroplasty combined with subtrochanteric osteotomy for the treatment of patients who had had Crowe Group-IV developmental dysplasia of the hip as a child. METHODS: Twenty-five consecutive patients (thirty-three hips) who had previously had Crowe Group-IV developmental dysplasia of the hip were treated with a modular cementless prosthesis at a mean age of sixty years. The mean follow-up period was eight years (range, five to eleven years). The acetabular cup was placed in the position of the anatomical hip center in every patient. Subtrochanteric femoral shortening osteotomy was performed with use of a step-cut design. RESULTS: The mean Merle d'Aubigné and Postel hip score improved from 9 to 16 points (out of a maximum of 18 points). The mean limb-length discrepancy in seventeen patients with unilateral involvement was reduced from 5.1 cm (range, 3.7 to 6.5 cm) to 2.8 cm (range, 1.4 to 4.6 cm). Two patients had a positive Trendelenburg sign, and three had a slight limp at the time of the latest follow-up. No cases of nonunion or nerve palsy were encountered. Postoperative dislocations occurred in two hips. One hip showed progressive radiolucent lines around the proximal femoral sleeve within two years after the surgery, and this was followed by progressive stem subsidence. Only one femoral stem was revised. CONCLUSIONS: Cementless, modular total hip arthroplasty combined with subtrochanteric osteotomy for the treatment of patients with prior Crowe Group-IV developmental dysplasia of the hip resulted in satisfactory outcomes. Hips with poor bone quality and a developmentally short femoral neck present technical challenges with regard to achieving sufficient rotatory stability, following osteotomy, for osseointegration of the modular implants. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

Non-destructively differentiating the roles of creep, wear and oxidation in long-term in vivo exposed polyethylene cups.

Wear of polyethylene acetabular cups in patients of total hip arthroplasty is routinely deduced from the penetration of the femoral head into the acetabular liner as observed in the radiographs. However, the linear penetration thus measured represents the cumulative contribution of two components, one due to wear, and the other due to creep or irreversible deformation of the polyethylene structure. The erroneous attribution to wear of the entire penetration displacement of the head in the cup might lead to misinterpretation of the actual performance of acetabular cups. The aim of this study was to quantify the head displacement components due to wear and to creep, as they occur in vivo in acetabular cups, and to relate them to the oxidation state of the material by means of advanced Raman spectroscopy procedures. Throughout the investigation, we compared the behaviors on the molecular scale of acetabular cups subjected to different sterilization methods (i.e., γ-irradiation and ethylene oxide treatment).