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BACKGROUND: Pseudotumors and muscle atrophy have been associated with metal-on-metal (MoM) resurfacing hip arthroplasty (RHA). We aimed to investigate the influence of the anterolateral (AntLat) and the posterior (Post) surgical approach on the location, grade and prevalence of pseudotumors and muscle atrophy in MoM RHA.PATIENTS AND METHODS: Forty-nine patients were randomized to MoM RHA by the AntLat (n = 25) or the Post (n = 24) approach at Aarhus University Hospital. Patients underwent metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) scans for investigation of location, grade and prevalence of pseudotumors and muscle atrophy. Plain radiographs, metal-ions concentrations and clinical outcome scores were evaluated to compare outcomes of the surgical approaches.RESULTS: MRI-detected pseudotumors were seen in 7 of 18 patients (39%) in the AntLat group and in 12 of 22 patients (55%) in the Post group (p = 0.33). Pseudotumors were mainly located anterolaterally to the hip joint in the AntLat group and postero-lateral to the hip joint in the Post group. Higher grades of muscle atrophy of the caudal part of the gluteus medius and minimus (p 0.08).CONCLUSION: Muscle atrophy and pseudotumor location after MoM RHA follow the surgical approach used for implantation. This knowledge may help differentiate between "normal postoperative appearance" and "MoM disease."

Introduction Little is known about pseudotumor frequency and risk factors for pseudotumor formation among different types of metal-on-metal (MoM) hip arthroplasties. A lower release of chromium and cobalt have been reported in MoM hip arthroplasties with a titanium sleeve compared to MoM designs without a titanium sleeve, but yet it is unknown whether a titanium sleeve reduces the pseudotumor frequency. We conducted a cross-sectional study to investigate: 1) pseudotumor frequency, 2) risk factors of pseudotumor formation 3) and correlations between pseudotumors, serum metal-ions, implant position, and clinical symptoms. Hypothesis We expected a lower pseudotumor frequency in MoM hip articulation with a titanium sleeve than reported in MoM hip articulation designs using chromium-cobalt sleeve. Materials and method A consecutive series of 41 patients/49 hips (31 males), mean age 52 (28–68) years, participated in a 5.5 ± 0.5 (4–6.5) year follow-up study of their M2a_Magnum hip articulation (Biomet Inc., Warsaw, Indiana, USA). Patients were evaluated with magnetic resonance imaging (MRI), measurements of serum metal-ions, plain radiographs, and clinical outcome measures of Harris Hip Score (HHS) and Oxford Hip Score (OHS). Results Eighteen of 47 hips (38%) had MRI-verified pseudotumors, all cystic, with a mean dimension of 10.6 × 25.6 × 41 mm. Digital measurements on plain radiographs revealed a higher cup anteversion in patients with a pseudotumor of mean 28.4° ± 5.05° compared to mean 23.5° ± 6.5° in patients without a pseudotumor (P = 0.009). Serum metal-ion concentrations, acetabular cup inclination and measures of HHS and OHS were similar between patients with and without a pseudotumor (P > 0.46). Conclusion At 5.5 ± 0.5 years after surgery, MRI-verified cystic pseudotumors were frequently observed in M2a_Magnum hip articulations despite the use of titanium sleeves. The pseudotumors were related to high cup anteversion angles but not related to high serum metal-ions or clinical symptoms. Level of evidence IV: cross-sectional study.

Background and purpose — Short-term experimental studies have confirmed that there is superior fixation of cementless implants inserted with compaction compared to broaching of the cancellous bone. Patients and methods — 1-stage, bilateral primary THA was performed in 28 patients between May 2001 and September 2007. The patients were randomized to femoral bone preparation with broaching on 1 side and compaction on the other side. 8 patients declined to attend the postoperative follow-up, leaving 20 patients (13 male) with a mean age of 58 (36–70) years for evaluation. The patients were followed with radiostereometric analysis (RSA) at baseline, at 6 and 12 weeks, and at 1, 2, and 5 years, and measurements of periprosthetic bone mineral density (BMD) at baseline and at 1, 2, and 5 years. The subjective part of the Harris hip score (HHS) and details of complications throughout the observation period were obtained at a mean interval of 6.3 (3.0–9.5) years after surgery. Results — Femoral stems in the compaction group had a higher degree of medio-lateral migration (0.21 mm, 95% CI: 0.03–0.40) than femoral stems in the broaching group at 5 years (p = 0.02). No other significant differences in translations or rotations were found between the 2 surgical techniques at 2 years (p > 0.4) and 5 years (p > 0.7) postoperatively. There were no individual stems with continuous migration. Periprosthetic BMD in the 7 Gruen zones was similar at 2 years and at 5 years. Intraoperative femoral fractures occurred in 2 of 20 compacted hips, but there were none in the 20 broached hips. The HHS and dislocations were similar in the 2 groups at 6.3 (3.0–9.5) years after surgery. Interpretation — Bone compaction as a surgical technique with the Bi-Metric stem did not show the superior outcomes expected compared to conventional broaching. Furthermore, 2 periprosthetic fractures occurred using the compaction technique, so we cannot recommend compaction for insertion of the cementless Bi-Metric stem.

Background Pseudotumors are a common finding in metal-on-metal (MoM) total hip arthroplasty (THA) and resurfacing hip arthroplasty (RHA). However, information on pseudotumors in metal-on-polyethylene (MoP) THA is limited. Methods One hundred eleven patients with 148 hip articulations—30 MoM THA, 47 MoM RHA, and 71 MoP THA—participated in a cross-sectional study at mean 7.1 (range: 0.2-21.5) years postoperatively. Patients were evaluated with metal artifact reducing sequence magnetic resonance imaging, measurements of metal ions, clinical scores of Harris Hip Score, Oxford Hip Score, the Copenhagen Hip and Groin Outcome Score, and conventional radiographs. Results Pseudotumors were present in 13 of 30 (43%) MoM THA, 13 of 47 (28%) MoM RHA, and 29 of 71 (41%) MoP THA patients, which was a similar prevalence ( P = .10). The prevalence of mixed or solid pseudotumors was significantly higher in patients with MoP THA (n = 10) compared to MoM THA (n = 3) and MoM THA (n = 0), ( P = .01). Hips with a mixed or solid pseudotumor had significantly poorer scores of Harris Hip Score ( P = .01) and OHS ( P = .002) and higher metal ion levels of cobalt ( P = .0009) compared to hips without a pseudotumor or with a cystic pseudotumor. Conclusion Pseudotumors have primarily been associated with MoM hip articulations, but we found a similar pseudotumor prevalence in MoP THA, which is the most common bearing worldwide. Mixed or solid pseudotumors were more often seen in MoP THA compared with MoM hip articulations, and patients with a mixed or solid pseudotumor had poorer clinical scores and higher metal ion levels than patients without a pseudotumor or with a cystic pseudotumor.

Background: The anterolateral (AntLat) surgical approach may spare the blood supply to the femoral head and improve the accuracy of cup positioning in metal-on-metal hip resurfacing arthroplasty. Thereby, potentially lessen complications such as avascular head necrosis, femoral neck narrowing and fracture, improve implant fixation, and lessen periprosthetic bone mineral density (BMD) loss.Methods: Between November 2008 and January 2012, a randomized clinical trial was performed at Aarhus University Hospital. A total of 49 patients (28 males) were allocated to metal-on-metal hip resurfacing arthroplasty by the AntLat (n = 25) or the posterior (Post; n = 24) surgical approach. Patients were followed with radiostereometric analysis, measurements of periprosthetic BMD, clinical outcome scores of Harris hip score and visual analogue scale, serum metal ions, and conventional radiographs.Results: At 3 months, cups in the AntLat group had higher total translations of mean 1.00 +/- 0.70 mm vs mean 0.64 +/- 0.45 mm in the post group (P = .04), and higher total rotations of mean 2.44 degrees +/- 1.36 degrees vs mean 1.39 degrees +/- 1.17 degrees in the Post group (P = .002). All migrations of cup and stem were similar at 1 and 2 years postoperative (P > .07). At 1 year, periprosthetic BMD since postoperative at the medial side of the stem was reduced to mean 98.45% +/- 8.57% in the AntLat group, and increased to mean 105.57% +/- 11.07% in the Post group (P = .02), but measurements were comparable at 2 years (P = .05).Conclusion: Cups inserted by the AntLat approach migrated more until 3 months postoperative. This illustrates a less good primary cup fixation with the AntLat approach; however, all cups were well-fixed after 3 months' follow-up indicating a good secondary fixation. (C) 2017 Elsevier Inc. All rights reserved.

Background — The mechanism of failure of metal-on-metal (MoM) total hip arthroplasty (THA) has been related to a high rate of metal wear debris, which is partly generated from the head-trunnion interface. However, it is not known whether implant fixation is affected by metal wear debris. Patients and methods — 49 cases of MoM THA in 41 patients (10 women) with a mean age of 52 (28–68) years were followed with stereoradiographs after surgery and at 1, 2, and 5 years to analyze implant migration by radiostereometric analysis (RSA). Patients also participated in a 5- to 7-year follow-up with measurement of serum metal ions, questionnaires (Oxford hip score (OHS) and Harris hip score (HHS)), and measurement of cup and stem positions and systemic bone mineral density. Results — At 1–2 years, mean total translation (TT) was 0.04 mm (95% CI: –0.07 to 0.14; p = 0.5) for the stems; at 2–5 years, mean TT was 0.13 mm (95% CI: –0.25 to –0.01; p = 0.03), but within the precision limit of the method. For the cups, ther...

Background: Short-term experimental and animal studies have confirmed superior fixation of cement-less implants inserted with compaction compared to broaching of the cancellous bone.Methods: Forty-four hips in 42 patients (19 men) were randomly operated using cementless hydroxyapatite-coated Bi-Metric stems. Patients were followed with radiostereometric analysis at baseline, 6 and 12 weeks, 1, 2, and 5 years, and measurements of periprosthetic bone mineral density at baseline, 1, 2, and 5 years. Complications during the study period and clinical outcome measures of Harris Hip Score were recorded at mean 7 years (5-8.8) after surgery.Results: Absolute migrations of medio/lateral translations between the broaching group and the compaction group of mean 0.14 mm (standard deviation [SD] 0.10) vs mean 0.30 mm (SD 0.27) (P = .01) at 1 year, and of mean 0.13 mm (SD 0.10) vs 0.34 mm (0.31) (P = .01) at 5 years were different. Absolute valgus/varus rotations of mean 0.12 degrees (SD 0.13 degrees) in the broaching group were less than mean 0.35 degrees (0.45 degrees) in the compaction group (P .13). The compaction group had significantly less bone loss than the broaching group in Gruen zone 3 (distal-lateral to the stem) at 1 and 5 years. No further differences in bone mineral density changes were found between groups up to 5 years after surgery. Complications throughout the period and clinical outcome measures of Harris Hip Score were similar at 7 years (5-8.8) after surgery.Conclusion: We found increased migration when preparing the bone with compaction compared with broaching in cementless femoral stems. (C) 2017 Elsevier Inc. All rights reserved.

OBJECTIVE: The relationship between metal wear debris, pseudotumor formation and metal hypersensitivity is complex and not completely understood. The purpose of this study was to assess the prevalence of pseudotumor formation in a consecutive series of metal-on-metal (MoM) total hip arthroplasty (THA) and to investigate its relationship to serum metal-ion levels and hypersensitivity to metal.METHODS: Forty-one patients (31 males), mean age 52 (28-68) years, with a total of 49 large-head MoM THA participated in a 5-7-year follow-up study. Patients underwent ultrasonography, serum metal-ion concentrations were measured, metal allergy and atopic dermatitis were evaluated, and the questionnaires of the Oxford Hip Score (OHS), Harris Hip Score (HHS) and the Short-Form Health Survey (SF-36) were completed.RESULTS: Pseudotumors were found in eight patients, but they were asymptomatic and their serum metal-ion levels were similar to those observed in patients with no pseudotumors (p > 0.36). The capsule-stem distance of mean 8.6 mm (SD 3.82, 95 % CI: 5.40-11.79) was wider (p = 0.02) in patients with pseudotumours than in patients without pseudotumors of mean 5.6 mm (SD 2.89, 95 % CI: 4.68-6.58). Positive patch test reactions were seen in three patients. Higher serum metal-ion levels of chromium and cobalt were significantly correlated with steeper cup inclination and smaller femoral head sizes, and were associated with female gender (p CONCLUSION: We found no association between pseudotumor formation, serum metal-ion levels, metal patch test reactivity, and atopic dermatitis. However, clinicians should be aware of asymptomatic pseudotumors, and we advise further exploration into the mechanisms involved in the pathogenesis of pseudotumors.

BACKGROUND: Metal-on-metal articulations mimic the human hip anatomy, presumably lower dislocation rates and increase the range-of-motion. This study aims to measure the muscle mass and power of both legs in patients with unilateral metal-on-metal total hip arthroplasty, and to investigate their effect on block-step test, spatio-temporal gait parameters and self-reported function.METHODS: Twenty-eight patients (7 women), mean age 50 (28-68) years, participated in a 5-7 year follow-up. Patients had received one type unilateral large-head metal-on-metal total hip articulation, all of which were well-functioning at follow-up. Mean muscle mass was measured by the total-body Dual energy X-ray Absorption scans, and muscle power was measured in a leg extensor power rig. Block-step test and spatio-temporal gait parameters were measured with an inertial measurement unit. Self-reported function was assessed by the Hip Disability and Osteoarthritis Outcome Score.FINDINGS: We found a significant difference between the mean muscle mass of the implant-side leg and the non-implant-side leg in hip, thigh and calf areas (PINTERPRETATIONS: Young patients have not fully regained muscle mass, muscle power and function 5-7 years after metal-on-metal total hip arthroplasty.

Introduction Little is known about pseudotumor frequency and risk factors for pseudotumor formation among different types of metal-on-metal (MoM) hip arthroplasties. A lower release of chromium and cobalt have been reported in MoM hip arthroplasties with a titanium sleeve compared to MoM designs without a titanium sleeve, but yet it is unknown whether a titanium sleeve reduces the pseudotumor frequence. We conducted a cross-sectional study to investigate: (1) pseudotumor frequency; (2) risk factors of pseudotumor formation; (3) and correlations between pseudotumors, serum metal-ions, implant position, and clinical symptoms. Hypothesis We expected a lower pseudotumor frequency in MoM hip articulation with a titanium sleeve than reported in MoM hip articulation designs using chromium-cobalt sleeve. Materials and method A consecutive series of 41 patients/49 hips (31 males), mean age 52 (28–68) years, participated in a 5.5 ± 0.5 (4–6.5) year follow-up study of their M2a_Magnum hip articulation (Biomet Inc., Warsaw, Indiana, USA). Patients were evaluated with magnetic resonance imaging (MRI), measurements of serum metal-ions, plain radiographs, and clinical outcome measures of Harris Hip Score (HHS) and Oxford Hip Score (OHS). Results Eighteen of 47 hips (38%) had MRI-verified pseudotumors, all cystic, with a mean dimension of 10.6 × 25.6 × 41 mm. Digital measurements on plain radiographs revealed a higher cup anteversion in patients with a pseudotumor of mean 28.4° ± 5.05° compared to mean 23.5° ± 6.5° in patients without a pseudotumor ( P = 0.009). Serum metal-ion concentrations, acetabular cup inclination and measures of HHS and OHS were similar between patients with and without a pseudotumor ( P > 0.46). Conclusion At 5.5 ± 0.5 years after surgery, MRI-verified cystic pseudotumors were frequently observed in M2a_Magnum hip articulations despite the use of titanium sleeves. The pseudotumors were related to high cup anteversion angles but not related to high serum metal-ions or clinical symptoms. Level of evidence IV: cross-sectional study.