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Background: Modular revision femoral components allow the surgeon to make more precise intraoperative adjustments in anteversion and sizing, which may afford lower dislocation rates and improved osseointegration, but may not offer distinct advantages when compared with less expensive monoblock revision stems., Questions/purposes: We compared modular and monoblock femoral components for revision of Paprosky Type I to IIIA femoral defects to determine (1) survivorship of the stems; and (2) complications denoted as intraoperative fracture, dislocation, or failure of osseointegration., Methods: Between 2004 and 2010, participating surgeons at three centers revised 416 total hip arthroplasties (THAs) with Paprosky Type I to IIIA femoral defects. Of those with minimum 2-year followup (343 THAs, mean followup 51 ± 13 months), 150 (44%) were treated with modular stems and 193 (56%) were treated with monoblock, cylindrical, fully porous-coated stems. During this time, modular stems were generally chosen when there was remodeling of the proximal femur into retroversion and/or larger canal diameters (usually > 18 mm). A total of 27 patients died (6%) with stems intact before 2 years, 46 THAs (13%) were lost to followup before 2 years for reasons other than death, and there was no differential loss to followup between the study groups. The modular stems included 101 with a cylindrical distal geometry (67%) and 49 with a tapered geometry (33%). Mean age (64 versus 68 years), percentage of women (53% versus 47%), and body mass index (31 versus 30 kg/m(2)) were not different between the two cohorts, whereas there was trend toward a slightly greater case complexity in the modular group (55% versus 65% Type 3a femoral defects, p = 0.06). Kaplan-Meier survivorship was calculated for the endpoint of aseptic revision. Proportions of complications in each cohort (dislocation, intraoperative fracture, and failure of osseointegration) were compared., Results: Femoral component rerevision for any reason (including infection) was greater (OR, 2.01; 95% CI, 1.63-2.57; p = 0.03) in the monoblock group (27 of 193 [14%]) compared with the modular cohort (10 of 150 [7%]). Femoral component survival free from aseptic rerevision was greater in the modular group with 91% survival (95% CI, 89%-95%) at 9 years compared with 86% survival (95% CI, 83%-88%) for the monoblock group in the same timeframe. There was no difference in the proportion of mechanically relevant aseptic complications (30 of 193 [16%] in the monoblock group versus 34 of 150 [23%] in the modular group, p = 0.10; OR, 1.47; 95% CI, 0.86-2.53). There were more intraoperative fractures in the modular group (17 of 150 [11%] versus nine of 193 [5%]; OR, 2.2; 95% CI, 1.68-2.73; p = 0.02). There were no differences in the proportions of dislocation (13 of 193 [7%] monoblock versus 14 of 150 [9%] modular; OR, 0.96; 95% CI, 0.67-1.16; p = 0.48) or failure of osseointegration (eight of 193 [4%] monoblock versus three of 150 [2%] modular; OR, 1.92; 95% CI, 0.88-2.84; p = 0.19) between the two groups with the number of hips available for study., Conclusions: Although rerevisions were less common in patients treated with modular stems, aseptic complications such as intraoperative fractures were more common in that group, and the sample was too small to evaluate corrosion-related or fatigue concerns associated with modularity. We cannot therefore conclude from this that one design is superior to the other. Larger studies and pooled analyses will need to be performed to answer this question, but we believe modularity should be avoided in more straightforward cases if possible., Level of Evidence: Level III, therapeutic study.

Background: The bimodular femoral neck implant (modularity in the neck section and prosthetic head) offers several implant advantages to the surgeon performing THAs, however, there have been reports of failure of bimodular femoral implants involving neck fractures or adverse tissue reaction to metal debris. We aimed to assess the results of the bimodular implants used in the THAs we performed., Questions/purposes: We asked: (1) What is the survivorship of the PROFEMUR(®) bimodular femoral neck stems? (2) What are the modes of failure of this bimodular femoral neck implant? (3) What are the major risk factors for the major modes of failure of this device?, Methods: Between 2003 and 2009, we used one family of bimodular femoral neck stems for all primary THAs (PROFEMUR(®) Z and PROFEMUR(®) E). During this period, 277 THAs (in 242 patients) were performed with these implants. One hundred seventy were done with the bimodular PROFEMUR(®) E (all are accounted for here), and when that implant was suspected of having a high risk of failure, the bimodular PROFEMUR(®) Z was used instead. One hundred seven THAs were performed using this implant (all are accounted for in this study). All bearing combinations, including metal-on-metal, metal-on-polyethylene, and ceramic-on-ceramic, are included here. Data for the cohort included patient demographics, BMI, implant dimensions, type of articular surface, length of followup, and C-reactive protein serum level. We assessed survivorship of the two stems using Kaplan-Meier curves and determined the frequency of the different modes of stem failure. For each of the major modes of failure, we performed binary logistic regression to identify associated risk factors., Results: Survivorship of the stems, using aseptic revision as the endpoint, was 85% for the patients with the PROFEMUR(®) E stems with a mean followup of 50 months (range, 1-125 months) and 85% for the PROFEMUR(®) Z with a mean followup of 50 months (range, 1-125 months)(95% CI, 74-87 months). The most common modes of failure were loosening (9% for the PROFEMUR(®) E), neck fracture (6% for the PROFEMUR(®) Z and 0.6% for the PROFEMUR(®) E), metallosis (1%), and periprosthetic fracture (1%). Only the bimodular PROFEMUR(®) E was associated with femoral stem loosening (odds ratio [OR] =1.1; 95% CI, 1.04-1.140; p = 0.032). Larger head (OR = 3.2; 95% CI, 0.7-14; p = 0.096), BMI (OR = 1.19; 95% CI, 1-1.4; p = 0.038) and total offset (OR = 1.83; 95% CI, 1.13-2.9; p = 0.039) were associated with neck fracture., Conclusion: Bimodular neck junctions may be potentiated by long neck lengths, greater offset, and larger head diameters. These factors may contribute to bimodular neck failure by creating a larger moment about the neck's insertion in the stem. The PROFEMUR(®) E implant is associated with high periprosthetic loosening. Based on our experience we cannot recommend the use of bimodular femoral neck implants., Level of Evidence: Level III, therapeutic study.

Background: Total hip arthroplasty (THA) is often performed in patients who are older and may take bisphosphonates to treat a variety of conditions, most commonly osteoporosis. However, the clinical effects of bisphosphonate use on patients who have undergone THA are not well described., Questions/purposes: (1) Is bisphosphonate use in patients with osteoarthritis undergoing primary THA associated with a change in the risk of all-cause revision, aseptic revision, or periprosthetic fracture compared with patients not treated with bisphosphonates? (2) Does the risk of bisphosphonate use and revision and periprosthetic fracture vary by patient bone mineral density and age?, Methods: A retrospective cohort study of 12,878 THA recipients for the diagnosis of osteoarthritis was conducted; 17.8% of patients were bisphosphonate users. Data sources for this study included a joint replacement registry (93% voluntary participation) and electronic health records and an osteoporosis screening database with complete capture of cases as part of the Kaiser Permanente integrated healthcare system. The endpoints for this study were revision surgery for any cause, aseptic revision, and periprosthetic fracture. The exposure of interest was bisphosphonate use; patients were considered users if prescriptions were continuously refilled for a period equal to or longer than 6 months. Bone quality (based on dual-energy x-ray absorptiometery ordered based on the National Osteoporosis Foundation's clinical guidelines taken within 5 years of the THA) and patient age (< 65 versus ≥ 65 years) were evaluated as effect modifiers. Patient, surgeon, and hospital factors were evaluated as confounders. Cox proportional hazards models were used. Hazard ratios (HRs) and 95% confidence intervals (CIs) were determined., Results: Age- and sex-adjusted risks of all-cause (HR, 0.50; 95% CI, 0.33-0.74; p < 0.001) and aseptic revision (HR, 0.53; 95% CI, 0.34-0.81; p = 0.004) was lower in bisphosphonate users than in nonusers. The adjusted risk of periprosthetic fractures in patients on bisphosphonates was higher than in patients not on bisphosphonates (HR, 1.92; 95% CI, 1.13-3.27; p = 0.016). Lower risks of all-cause revision and aseptic revision were observed in patients with osteopenia (HR, 0.49; 95% CI, 0.29-0.84; and HR, 0.53; 95% CI, 0.29-0.99, respectively) and osteoporosis (HR, 0.22; 95% CI, 0.08-0.62; and HR, 0.33; 95% CI, 0.11-0.99, respectively)., Conclusions: Patients considered bisphosphonate users who underwent THA had a lower risk for revision surgery. Bisphosphonate use was associated with a higher risk of periprosthetic fractures in younger patients with normal bone quantity. Evaluation of bone quality and bisphosphonate use for the diagnosis of osteoporosis is encouraged in patients with osteoarthritis who are candidates for primary THA. Further research is required to determine the optimal duration of therapy because long-term bisphosphonate use has been associated with atypical femur fractures., Level of Evidence: Level III, therapeutic study.

Background: Postoperative periprosthetic femur fractures are an increasing concern after primary total hip arthroplasty (THA). Identifying and understanding predisposing factors are important to mitigating future risk. Femoral stem design may be one such factor., Questions/purposes: The goals of our study were to compare the (1) frequency of periprosthetic femur fracture and implant survivorship; (2) time to fracture in those patients who experienced periprosthetic femur fracture; and (3) predictive risk factors for periprosthetic femur fracture between a unique stem design with an exaggerated proximal taper angle and other contemporary cementless, proximally fixed, tapered stems., Methods: We reviewed all hips in which a femoral hip component with a uniquely exaggerated proximal taper angle (ProxiLock) was implanted during primary THA at a single academic institution. That group of patients was compared with a cohort of patients who underwent primary THA during the same time interval (1995-2008) in which any other cementless, proximally fixed, tapered stem design was used. The two groups differed somewhat in terms of sex, age, and body mass index, although these differences were of unclear clinical significance. During the study, 3964 primary THAs were performed using six different designs of cementless, proximally fixed, tapered femoral hip prostheses. There were 736 stems in the ProxiLock (PL) patient group and 3228 stems in the non-ProxiLock (non-PL) group. In general, the stem highlighted in this study became the routine cementless stem used for primary THA for three arthroplasty surgeons without specific patient or radiographic indications. Periprosthetic fractures were identified within each group. The incidence, timing, type, and treatment required for each fracture were analyzed. The Kaplan-Meier method was used to determine study patient survival free of any postoperative fracture. Radiographs and the electronic medical record of each patient who sustained a fracture were reviewed. Followup was comparable between groups at all time points., Results: The Kaplan-Meier estimate for fracture-free patient survival was worse in the PL group at all time points with survival of 98.4% (range, 97.4%-99.3%), 97.1% (range, 95.9%-98.3%), 95.4% (range, 93.8%-97.0%), and 92.6% (range, 89.6%-95.3%) at 30 days, 1 year, 5 years, and 10 years, respectively, for the PL patient group compared with 99.8% (range, 99.7%-99.9%), 99.6% (range, 99.3%-99.8%), 99.3% (range, 99.0%-99.6%), and 98.4% (range, 97.5%-99.1%) in the non-PL patient group (p < 0.001). Patients in the PL group had increased cumulative probability of both early and late fractures with cumulative probabilities of fracture of 2.5% (range, 1.3%-3.6%) at 90 days and 7.4% (range, 4.7%-10.4%) at 10 years compared with probabilities of 0.3% (range, 0.1%-0.5%) at 90 days and 1.6% (range, 0.8%-2.5%) at 10 years in the non-PL group (p < 0.001). Patients in the PL group had an increased risk of postoperative periprosthetic femur fracture (hazard ratio [HR], 5.6; 95% confidence interval [CI], 3.4-9.1; p < 0.001); fracture requiring reoperation (HR, 8.4; 95% CI, 4.4-15.9); p < 0.001); and fracture requiring stem revision (HR, 9.1; 95% CI, 4.5-18.5; p < 0.001). Age older than 60 years was also a risk factor for fracture (HR, 3.7; 95% CI, 2.1-6.4), but sex, body mass index, and preoperative diagnosis were not predictive., Conclusions: Hips implanted with an uncemented femoral stem, which has a uniquely exaggerated proximal taper angle, had an increased risk of both early and late postoperative periprosthetic femur fracture. The majority of patients with a fracture underwent reoperation or stem revision. The unique proximal geometry, lack of axial support from the smooth cylindrical distal stem as well as resorption of the hydroxyapatite coating and poor ongrowth with subsequent subsidence may contribute to increased risk of fracture. Although this particular stem has recently been discontinued by the manufacturer, these findings are important in regard to followup care for patients with this stem implanted as well as for future cementless stem design in general., Level of Evidence: Level III, therapeutic study.