Threefold Decrease in Early Periprosthetic Femur Fracture Risk With a Modern, Triple-Tapered, Noncemented, Collared Stem: An American Joint Replacement Registry Study.

Primary total hip arthroplasty (THA) procedures continue to increase. On the basis of data from 2000 to 2014, the frequency of THA in the U.S. is projected to grow to 635,000 procedures per year by 20301. The majority of implants from these procedures are expected to last >20 years. A study of 94,292 total hip replacements from the Finnish Arthroplasty Registry noted a survivorship of 58% at 25 years2. THA complications (especially periprosthetic joint infection [PJI] and dislocation), as well as perioperative management to optimize short stays and outpatient THA while minimizing perioperative complications, continue to draw heavy attention. Implant Design and Related Outcomes In a study evaluating 2016 data from the American Joint Replacement Registry (AJRR) compared with other national registries, the authors found that cementless stem fixation combined with the use of ceramic and 36-mm heads was the current preference in the U.S., while other registries indicated that cemented implants and metal and 32-mm heads were most commonly used3. Cemented Versus Cementless Implants There is evidence that cemented implants outperform cementless counterparts in elderly patients when early complication rates are compared. On the basis of the recent Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) annual report, Tanzer et al. reported that, among patients >75 years of age who underwent THA, those treated with the best-performing cementless femoral stems had more early revisions (<30 days postoperatively) compared with those treated with the best-performing cemented implants4. These early revisions were mainly attributable to the risk of revision for fracture or loosening. This difference disappeared after 90 days following surgery4. Bearing Surfaces Metal-on-Polyethylene (MoP) Studies show better long-term survival with a metal-on-highly-cross-linked-polyethylene (HXLPE) articulation compared with metal-on-conventional, non-cross-linked polyethylene (CPE) in younger patients5-7. In a retrospective review of 101 hips in 84 patients ≤50 years of age, with a duration of follow-up of 15 to 20 years, cobalt-chromium (CoCr)-on-CPE showed a high rate of wear-related revision (13 of 101, 12.9%)5. In contrast, the authors of another report noted excellent 15-year survivorship and functional outcome with no wear-related revision in a cohort of 82 patients (89 hips) ≤50 years of age with CoCr-on-HXLPE6. An observational study from the AOANJRR showed that hips in which XLPE was used (199,131 procedures) had a significantly lower revision rate at 16 years following THA for osteoarthritis compared with hips in which CPE was used (41,171 procedures), regardless of the head material7. Ceramic-on-Ceramic (CoC) or Ceramic-on-Polyethylene (CoP) Clicking or squeaking continues to be present in a small percentage of patients who undergo THA with CoC components. In 1 report, audible noise was present in 6.4% of hips (48 of 749) following THA with use of fourth-generation alumina CoC bearings, although no patient underwent revision for clicking or squeaking8. The selection of CoP recently surpassed MoP as the most popular bearing surface used in THA in the U.S.9. Metal-on-Metal (MoM) A study from Korea demonstrated an acceptable rate of aseptic loosening (cup, 10.5%; stem, 6.1%) in a cohort of 114 hips treated with THA using 28-mm MoM components; the average follow-up was 20 years (range, 17 to 23 years)10. Nonetheless, the use of an MoM articulation continues to decline secondary to persistent concerns for metal debris-induced adverse local tissue reactions. Surface Treatment The authors of a prospective multicenter study reported that, at the 5-year follow-up, titanium alloy (Ti6Al4V) acetabular shells with a porous titanium coating (PTC) had a higher percentage of gaps/radiolucency compared with plasma-sprayed (PS) acetabular shells from the same manufacturer (23% versus 5%). Patients in the PTC group had more patient-reported pain, although none underwent revision for loosening11. Short Versus Standard Stems In a randomized double-blinded study, persistent mid-thigh pain was much more prevalent among patients with a short Collum Femoris Preserving (CFP) stem (LINK) (19%) compared with a full-profile wedge-tapered Alloclassic Zweymüller stem (Zimmer) (7%) at medium-term follow-up. Both cohorts, however, had a high percentage of varus malalignment (14% and 16%, respectively), and the results may not be generalizable to other cementless designs12. The association between periprosthetic femoral fracture and length/geometry of cementless implants was also studied. In a cohort study of 5,090 consecutive, direct-anterior primary THAs performed at a single institution, the incidence of periprosthetic fracture using femoral components with 4 variations in length and geometry was evaluated13. All stems were of a single-taper wedge design from the same manufacturer, with 1 of 4 configurations: full-length, standard profile; full-length, reduced distal profile; short-length, standard profile; and short-length, reduced distal profile. There was a trend toward a higher risk of periprosthetic fracture in the short-length-with-standard-profile group13. It is unclear whether the same trend would hold using other surgical approaches. Head Size In a study using data from the Nordic Arthroplasty Register Association database and including 186,231 patients who underwent MoP THA with use of a 28, 32, or 36-mm head, the authors found that the risk of dislocation was reduced with the use of 32 versus 28-mm heads, although the overall revision risk remained similar. Surprisingly, transitioning from 32 to 36-mm heads was associated with a higher risk of revision for all causes, including the risk of dislocation14. It appeared that 32-mm heads would be the optimal choice for MoP THA. Dual-Mobility Constructs Modular dual-mobility constructs employ a CoCr articular surface liner that locks into an outer shell of titanium. A systematic review of mid-term studies of dual-mobility constructs supports their efficacy in reducing the incidence of dislocation after both primary and revision THA15. The wear rate for contemporary dual-mobility constructs using an HXLPE design showed substantially larger magnitudes of initial head penetration and wear than those reported for HXLPE in fixed-bearing couples (twice the rate)16. It approaches a steady state after 2 years, making it comparable with traditional fixed bearings; future studies should address the long-term outcomes16. A propensity score-matched study showed that patients with a dual-mobility construct had a lower risk of revision due to dislocation, although there was no difference in the overall risk of revision between the dual-mobility construct group and the MoP/CoP group. The authors speculated that selection bias may have been present, as the dual-mobility construct group also showed a higher risk of revision due to infection17. Patient Factors in Relation to Outcomes Medical Comorbidities Dialysis dependence was demonstrated to be an independent risk factor for 30-day adverse events, intensive care unit (ICU) care, longer length of stay, and rehabilitation needs in patients undergoing total joint arthroplasty (TJA)18. Patients with hepatitis C who received interferon or direct antiviral agents prior to THA appeared to have fewer postoperative complications, especially PJI19. Dorr Type In a matched comparative study, a higher incidence of femoral stem-related complications (mainly periprosthetic femoral fractures) was observed when using double-tapered wedge stems in Dorr type-A compared with type-B femora20. A study correlating proximal femoral morphology and leg length after THA showed that patients with a Dorr type-A femur and a high femoral cortical index (FCI, defined as the ratio of cortical width minus endosteal width to the cortical width at a level 100 mm below the tip of the lesser trochanter on an anteroposterior radiograph of the hip) were at increased risk of leg lengthening while patients with a Dorr type-C femur and a low FCI had an increased probability of shortening21. Body Mass Index (BMI) Several studies showed a higher risk of complications (up to 3 times) among THA patients classified as morbidly obese compared with normal controls22-24. In particular, researchers in the U.K. reported on, to our knowledge, the largest longitudinal cohort study to date analyzing the influence of BMI on THA outcomes (>410,000 patients)25. Patients who were morbidly obese (BMI of 40 to 60 kg/m2) had the highest probability of revision at 10 years (twice that of the underweight group), while 90-day mortality was significantly higher for the underweight group compared with those with normal BMI. Milder obesity (BMI of 25 to 40 kg/m2) seemed to have a protective effect against mortality25. In another study, patients classified as super obese (BMI of ≥45 kg/m2) had a greater risk of reoperation and readmission and greater 90-day costs compared with the nonobese cohort, but they had comparable quality-of-life improvements26. Patients classified as morbidly obese who underwent bariatric surgery prior to TJA showed a reduced comorbidity burden at the time of TJA, with reduced post-TJA complications; however, the risk of revision was not reduced27. While obesity seems to be a major negative predictor of adverse outcomes, some argue that THA is still cost-effective for morbidly obese and super obese groups and recommend against a cutoff threshold to avoid unnecessary loss of health-care access28. Preoperative Opioid Use Opioid use within 3 months preceding THA was an independent predictor of early revision, while obesity and anxiety/depression were also shown to predict early failure of treatment29. Significantly higher 30-day readmission and revision rates were observed among THA/TKA (total knee arthroplasty) patients with a history of long-term preoperative opioid use30. In another study, patients who used opioids preoperatively tended to have significantly lower patient-reported outcome scores and longer hospital stays, and were more likely to be discharged to a rehabilitation facility31. Tobacco Use In a recent study, smokers had a significantly higher risk of deep infection and reoperation after revision THA compared with nonsmokers, and the risk was higher than for primary THA32. The authors of a systematic review and meta-analysis found that former tobacco users had a significantly lower risk of wound complications and PJI compared with current smokers. Smoking cessation counseling prior to total joint arthroplasty is strongly advocated33. A history of smoking was also recently tied to increased risk of nerve injury in patients undergoing THA34. Surgical Approach The optimal surgical approach in primary THA remains controversial. A systematic review and meta-analysis of prospective studies showed less pain and better reported function through 90 days postoperatively for the direct anterior approach compared with the posterior approach35. However, when comparing early revision rates (<5 years from index primary surgery), the direct anterior approach was associated with a significantly higher rate of early revision due to femoral loosening compared with the posterior approach, while the posterior approach demonstrated a higher incidence of early revision due to instability36. A Dutch joint-registry study showed small improvements in the 3-month postoperative patient-reported outcome measure (PROM) for the direct anterior and posterolateral approaches compared with the direct lateral and anterolateral approaches37. Regardless of the different approaches, there are minimal differences in gait mechanics at early or late follow-up38. The long-term prognosis of lateral femoral cutaneous nerve (LFCN) neuropathy was also investigated. One study found that approximately 11% of patients had persistent LFCN neuropathic symptoms even at 6 to 8 years after direct anterior THA, and the most common presentation was numbness (37%). This, however, did not affect hip functional scores39. Complications There is substantial variation in reported THA complication rates among national databases and joint registries. The American College of Surgeons National Surgical Quality Improvement Program (NSQIP) tends to show the lowest rate of complications40. Medical Complications A study of 10-year Hospital Episode Statistics data from the U.K. including 540,623 THAs showed that postoperative medical complications decreased year-after-year despite a steady rise in the average Charlson Comorbidity Index score. The only 2 exceptions were lower respiratory tract infection and renal failure, which continued to rise41. Venous Thromboembolism (VTE) and Anticoagulation A systematic review found that industry-funded studies assessing thromboprophylaxis reported fewer patients with pulmonary embolism (PE), major bleeding, and mortality compared with nonfunded studies42. A cross-sectional study in 5 countries found that the rate of in-hospital VTE after hip arthroplasty was 0.16% in Canada, 1.41% in France, 0.84% in New Zealand, 0.66% in the U.S. (California), and 0.37% in Switzerland, while the benchmark was 0.58%. French data showed a higher rate, potentially because of the systematic use of ultrasound, which could result in the over-detection of deep venous thrombosis (DVT) but not PE43. A retrospective analysis of the NSQIP data set from 2008 to 2016 demonstrated that the risk of DVT was not associated with obesity in patients undergoing THA. The risk of PE, however, was found to be elevated in THA patients whose BMI was ≥35 kg/m2. The authors concluded that, since current pharmacologic anticoagulation regimens can reduce the DVT rate but have not been demonstrated to affect the rate of PE or death, the data do not support increased DVT anticoagulation in THA patients who are obese but without other VTE risk factors44. Dislocation Spinopelvic pathology dominated the literature on THA dislocation, with important research focused on spine-pelvis-hip radiographs in the sagittal plane and the related functional safe zone45-52. It has been proposed that the spinopelvic relationship be categorized according to 4 groups, as assessed at the preoperative evaluation (1A: normal alignment, normal mobility; 1B: normal alignment, stiff spine; 2A: flatback deformity, normal spine; 2B: flatback deformity, stiff spine). Special attention should be paid to the 2B population, for whom surgeons may consider using a dual-mobility construct with targeted 30° of anteversion relative to the functional pelvic plane (based on standing, rather than supine, anteroposterior pelvic radiography)45. A modified classification system was recently proposed on the basis of supine anteroposterior pelvic, standing anteroposterior pelvic, and sitting and standing lateral spinopelvic radiographs46. The classification system adds a hyperlordosis spinal alignment category (pelvic incidence-lumbar lordosis [PI-LL] mismatch of <–10°) and suggests a new risk assessment tool incorporating sagittal spinal alignment (coded as a number) and spine mobility/stiffness (coded as a letter) to use in revision THA. This new assessment tool was validated in a group of 222 patients who underwent revision hip replacement for recurrent instability. Results for 111 patients who were evaluated using the new spinal function assessment were compared with a matched group of 111 patients who were not evaluated using the system. The dislocation rate was 3% among patients who had the new presurgical assessment compared with 16% for those who did not46. Patients undergoing THA with a history of lumbar spinal fusion (LSF) had a >100% increased risk of dislocation compared with those who had LSF 5 years after THA53. Another study found that fusion to the sacrum as well as multiple levels of lumbar involvement dramatically increased the risk of dislocation in primary THA54. Although there was no increased perioperative spike of dislocation in patients undergoing LSF following an otherwise stable THA, 1 study demonstrated that this population had a sustained elevated risk of dislocation (0.7% per year) compared with those without LSF (0.4% risk per year)55. PJI The past decade saw tremendous effort and focus on preventing PJI in patients undergoing TJA. Current unadjusted 1-year and 5-year risks of PJI following THA were found to be 0.69% and 1.09%, respectively. After adjustment, however, there was no detectable decline in the risk of PJI over time56. Once PJI is confirmed, the 1-year weighted mortality rate was noted to be 4.22%, and 5-year mortality, 21.12%, highlighting the devastating consequence of PJI57. A PJI consortium (International Consensus on Orthopedic Infections) recently published a guideline for comprehensive hip and knee PJI diagnosis, prevention, and treatment58-65. With the new evidence-based and validated PJI criteria in 2018, PJI diagnosis now consists of a scoring system for minor criteria in both preoperative and intraoperative diagnosis66. One recent study found that there is no difference in treatment success as defined by the Delphi criteria between patients meeting minor-only criteria and those meeting a major criterion of PJI diagnosis67. Another PJI scoring model assigns relative weights to the various risk factors for PJI following TJA. A previous open surgical procedure, drug abuse, a revision procedure, and human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) were deemed the most influential factors68. A positive association between postoperative urinary tract infection and PJI after THA or TKA was established in a population-based, retrospective cohort study of 113,061 patients (≥66 years old). No association was found between acute postoperative urinary retention and PJI69. Debate continues regarding the merits of 1-stage versus 2-stage revision for PJI. In a recent Danish study, the authors reported an encouraging 91% infection-free survival rate at a minimum of 2 years of follow-up when using 1-stage cementless revision in the treatment of patients with chronic periprosthetic hip joint infection70. In another study, about 30% of revisions had an increase in the vancomycin minimum inhibitory concentration (MIC) between 2 stages, raising concerns about the potential for the emergence of resistant organisms between the stages of a 2-stage revision71. Postoperative Urinary Retention Risk factors for postoperative urinary retention have been defined, including an age of >60 years, intraoperative fluid administration of >1,350 mL, and intraoperative of an of risk factors related to postoperative urinary retention are and should be Although the percentage probability of periprosthetic femoral fracture using cementless stems was demonstrated to be only at 10 years, this dramatically increased to at years after primary another study the incidence of periprosthetic femoral fracture in stems found that the incidence of periprosthetic femoral fracture continued to increase after the decade and the incidence of aseptic loosening in the decade A study using data from the national found that the annual incidence of periprosthetic femoral fracture in primary THAs increased from of to of the of to In the report, type-C 4 more than and they were more commonly in cemented The incidence of with MoP is and an average of 5 years to metal the ratio have been shown to be higher in MoP (range, or compared with MoM (range, to Another study a level of and a ratio of to be a cutoff threshold for important MoP The levels of and to decline by and 3 months after potential in the femoral nerve was observed in 17 of patients who underwent the direct anterior approach in THA when were against the anterior of the although this was The authors of another recent study of the anterior in a relative safe to the to avoid In a recent retrospective cohort study using the A data was found to be associated with significantly lower rates of dislocation and aseptic revision of the acetabular following primary The authors when their results because of potential by In a double-blinded study in the U.K. that patients undergoing THA or the use of with an and to show a in the rate of surgical infection Current and The past decade has a rise in the incidence of both outpatient and THA, according to a recent comparative and have been for or to be while also patient supports a trend toward better postoperative outcomes when hip replacement is performed by While the majority of primary THAs are performed at surgeons are the majority of these A more relationship was by a New data set of of the was associated with a 2 to increase in the risk of complications, mortality, and revision relative to while hospital was associated with a increase in complications and a 4 to increase in The opioid has has more attention in recent years. regarding opioid after joint replacement surgery show that to of patients continue opioid use even at 1 year have been to reduce opioid without of A study indicated that fewer compared with 90 was associated with a in opioid and decreased opioid without pain scores and patient-reported In a retrospective review of patients who underwent THA and TKA reported a history of those reported and including respiratory and In this study, no patient with a who was an adverse It was also found that, for the patients with a who were or no differences could be found in the rate of Use is now an of the THA to reduce loss and the risk of by including the American Association of and Surgeons and the American of Orthopaedic Surgeons state that no of or time of administration have been shown to A recent randomized study did that multiple postoperative of reduced loss compared with a single preoperative The of 1 preoperative of 2 by 3 postoperative of of loss in Smoking A study from the demonstrated that level of 8 within 1 of TJA could significantly rates of smokers It also to of patients who reported as continued smoking and as more than after surgery among those who and A from demonstrated that the administration of could to for among patients undergoing THA, by a in postoperative pain scores of was also in reducing opioid and The of use in patients with undergoing THA or TKA was recently in a retrospective study of 2 of patients in the group and in the patients who received were not found to have a significantly higher infection rate than to the that PJI is an this study have been with the of with a a mainly a spinal using significantly the length of of patients undergoing THA by 1 Postoperative Current evidence that the postoperative of and levels following THA in patients with a normal preoperative level is the should be by risk factors and Preoperative and levels of and 4 have been as below which should consider postoperative and It has been that consider the use of the in for THA including of patients with THA with a had significantly higher than those without a and among the THA with a was greater for those The of The a of recently published studies related to the system that received a higher of In to in this 4 other with a higher of to hip replacement are to this review after the standard with a about to in an evidence-based in this treatment and risk of or after total hip a cohort study from national Danish Joint This to the knowledge, the largest study using the Danish databases to address the association between perioperative treatment and postoperative 30-day PE, and from all among patients who underwent THA. A total of patients were the study from to among received perioperative and did After use was not found to significantly increase the risk of PE, or The authors were to the of using on patients with previous and other in this of on outcomes after primary and revision total hip at the a cohort study patients who underwent primary or revision THA from through A using 32 factors found in the medical including 17 and of was used to the study population as index of of to and of With to in-hospital complications, differences were found only for wound complications and the and with patients had a significantly higher risk of mortality ratio of dislocation, wound and reoperation within 90 days and 1 year after primary THA. The authors did not a association of with aseptic periprosthetic or prior bariatric surgery outcomes following total joint arthroplasty in the morbidly A This meta-analysis studies from to 2018, with a total of patients who underwent THA or underwent bariatric surgery prior to TJA and the patients with obesity as the group. The study found that bariatric surgery prior to TJA was associated with reduced risks of medical complications, length of stay, and The risks of wound infection or and the long-term risks of dislocation, periprosthetic and revision were not the THA and TKA bariatric surgery was associated with a in the risk of PJI after but not after THA. of of and on in the after total hip the randomized The and in is a Danish study the and of 4 regimens or after THA. The was 1 surgery and 6 for for a total of 4 of the on the postoperative and patients were in the The authors found that significantly reduced compared with in the after The surgical approach versus for the study cohort was not which have the postoperative for

Highlights of the 2021 American Joint Replacement Registry Annual Report.

Cemented Femoral Stem Design Is Not Associated With Risk of Revision After Total Hip Arthroplasty in Patients Aged ≥ 65 Years: An Analysis of the American Joint Replacement Registry.

Periprosthetic femur fractures are a known complication after hip hemiarthroplasty (HA) in geriatric patients. The relationship between femoral stem design and fracture risk remains unclear. This study aimed to assess (1) the association between stem geometry and fixation on periprosthetic femur fracture risk and (2) the effect of a femoral stem collar. The American Joint Replacement Registry data were analyzed for HA cases in patients aged 70+ years from 2012 to 2021. We identified 56,828 primary HAs for the diagnosis of femoral neck fracture. Patient demographics and revision surgery for periprosthetic femur fracture in the form of open reduction with internal fixation or revision arthroplasty were documented. Stems were categorized into tapered wedge or fit and fill, and cemented stems were categorized into composite beam or taper slip. Cox models and Benjamini-Hochberg adjustments were used for statistical analysis. Cemented composite beam stems accounted for 38% of implants, followed by fit-and-fill stems at 32%, tapered wedge stems at 29%, and cemented taper slip stems at 1%. A collar was present in all cemented composite beam stems, 23% of tapered wedge stems, and 20% of fit-and-fill stems. After applying inverse probability weighting adjustment, cemented composite beam stems showed a markedly lower periprosthetic femur fracture risk over other stems. Compared with cemented composite beam stems, collarless tapered wedge demonstrated a markedly higher hazard ratio (HR) (3.63; P < 0.001), as did both collarless (HR, 3.4; P < 0.001) and collared fit-and-fill stems (HR, 3.45; P < 0.001). The presence of a collar reduced periprosthetic femur fracture risk across all designs, with the most pronounced reduction seen in tapered wedge stems (0.90% versus 0.41%). For HA in patients aged 70 years and older, cemented composite beam stems with a collar were associated with the lowest risk of periprosthetic femur fractures in the American Joint Replacement Registry database. However, these findings reflect implant utilization patterns up to 2021 and may not fully account for the recent rise in triple taper collared stem use. Surgeons should consider these implants when selecting fixation strategies for HA. Level III.

Periprosthetic femur fracture is a known complication after THA. The associated risk of cementless femoral component design for periprosthetic femur fracture in a registry population of patients older than 65 years has yet to be clearly identified. (1) Is femoral stem geometry associated with the risk of periprosthetic femur fracture after cementless THA? (2) Is the presence or absence of a collar on cementless femoral implant designs associated with the risk of periprosthetic femur fracture after THA? We analyzed American Joint Replacement Registry data from 2012 to March 2020. Unique to this registry is the high use of cementless femoral stems in patients 65 years and older. We identified 266,040 primary cementless THAs during the study period in patients with a diagnosis of osteoarthritis and surgeries linked to supplemental Centers for Medicare and Medicaid data where available. Patient demographics, procedure dates, and reoperation for periprosthetic femur fracture with revision or open reduction and internal fixation were recorded. The main analysis was performed comparing the Kheir and Chen classification: 42% (112,231 of 266,040) were single-wedge, 22% (57,758 of 266,040) were double-wedge, and 24% (62,983 of 266,040) were gradual taper/metadiaphyseal-filling cementless femoral components, which yielded a total of 232,972 primary cementless THAs. An additional analysis compared cementless stems with collars (20% [47,376 of 232,972]) with those with collarless designs (80% [185,596 of 232,972]). A Cox proportional hazard regression analysis with the competing risk of death was used to evaluate the association of design and fracture risk while adjusting for potential confounders. After controlling for the potentially confounding variables of age, sex, geographic region, osteoporosis or osteopenia diagnosis, hospital volume, and the competing risk of death, we found that compared with gradual taper/metadiaphyseal-filling stems, single-wedge designs were associated with a greater risk of periprosthetic femur fracture (HR 2.9 [95% confidence interval (CI) 2.2 to 3.9]; p < 0. 001). Compared with gradual taper/metadiaphyseal-filling stems, double-wedge designs showed an increased risk of periprosthetic femur fracture (HR 3.0 [95% CI 2.2 to 4.0]; p < 0. 001). Collarless stems showed an increased risk of periprosthetic fracture compared with collared stems (HR 7.8 [95% CI 4.1 to 15]; p < 0. 001). If cementless femoral fixation is used for THA in patients 65 years or older, surgeons should consider using gradual taper/metadiaphyseal-filling and collared stem designs because they are associated with a lower risk of periprosthetic femur fracture. Future investigations should compare gradual taper/metadiaphyseal-filling and collared cementless designs with cemented fixation in this population. Level III, therapeutic study.

Is American Joint Replacement Registry Data Consistent With International Survivorship in Hip and Knee Arthroplasty? A Comparative Analysis

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. 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. 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. 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 30days, 1year, 5years, and 10years, 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 90days and 7.4% (range, 4.7%-10.4%) at 10years compared with probabilities of 0.3% (range, 0.1%-0.5%) at 90days and 1.6% (range, 0.8%-2.5%) at 10years 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 60years 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. 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 III, therapeutic study.

Perioperative Periprosthetic Femur Fractures are Strongly Correlated With Fixation Method: an Analysis From the American Joint Replacement Registry

The stem design in total hip arthroplasty (THA) is constantly evolving. The impact of the collar on the risk of periprosthetic fracture remains controversial. This study aimed to determine whether adding a collar to the femoral stem impacts the early periprosthetic fracture risk within 90 days of surgery.This retrospective study included 1,623 patients who underwent primary total hip arthroplasty in a single orthopedic department between January 2010 and December 2020. The inclusion criteria were uncemented stem with or without a collar, in a primary intention, without previous hip surgery with a similar “corail like” design. The assessed data were demographic characteristics (age, gender, number of obese (BMI &gt; 30)), single or dual mobility, the surgical approach, the early complication, particularly the periprosthetic femoral fractures. Of the 1,623 patients, 1,380 received a collared stem (85%), and 243 received a collarless stem (15%). A multivariate analysis was performed to determine the collar's effect on the risk of early periprosthetic fracture (&lt;90 days).Nine (0.55%) early periprosthetic fractures were identified in the whole cohort. There were four fractures (1.65%) in the collarless stem group and five fractures (0.36%) in the collared stem group (p=0,005). One patient required revision surgery in the collared stem group, while two patients required revision surgery in the collarless stem group. The multinomial logistic regression model indicated a statistically significant lower (p&lt;0.05) risk of early periprosthetic fracture within 90 days of surgery in the collared stems group. No other risk factor for early periprosthetic fractures has been identified.Using collared stems in cementless THA protects early periprosthetic femoral fractures within 90 days of surgery.

Seasonality of Periprosthetic Femur Fractures in 12,700 Primary and Revision Total Hip Arthroplasties

Decreased Revision Risk With Cementless Collared Metadiaphyseal-Filling Stems Compared to Cemented Fixation in Patients 65 Years and Older.

The American Academy of Orthopaedic Surgeons American Joint Replacement Registry (AJRR) is the largest registry of total hip and knee arthroplasty (THA and TKA) procedures performed in the United States. The purpose of this study was to examine whether AJRR data are representative of the national experience with hip and knee arthroplasty as represented in the National (Nationwide) Inpatient Sample (NIS). All patients undergoing a THA or TKA procedure between 2012 to 2018 (AJRR) and 2012 to 2016 (NIS) were identified. Cohen d effect sizes were computed to ascertain the magnitude of differences in demographics, hospital volume (in 50 patient increments), and geographic characteristics between the AJRR and NIS databases. The study included (NIS: 2,316,345 versus AJRR: 557,684) primary THA and (NIS: 3,417,700 versus AJRR: 809,494) TKA procedures. The magnitude of distribution, as determined by the Cohen d effect size, showed that the proportions of AJRR and NIS patients were similar based on overall sex (THAs [d = 0.03] and TKAs [d = 0.02]) and age (THAs [d = 0.17] and TKAs [d = 0.12]). Similarly, only small differences (d = 0.34 or less) were identified between databases considering hospital volume and geography. The AJRR was underrepresented in Southern regions and hospitals with low procedure volume and overrepresented in Northern hospitals and those with larger volume. Both the NIS and the AJRR followed a similar overall trend, with most procedures performed at hospitals with <50 cases per year. Distributions across hospital volume, age, and geography were proportionally similar between the AJRR and NIS databases, supporting the generalizability of AJRR findings to the larger US cohort.

The aim of this study was to estimate the 90-day risk of revision for periprosthetic femoral fracture associated with design features of cementless femoral stems, and to investigate the effect of a collar on this risk using a biomechanical in vitro model. A total of 337 647 primary total hip arthroplasties (THAs) from the United Kingdom National Joint Registry (NJR) were included in a multivariable survival and regression analysis to identify the adjusted hazard of revision for periprosthetic fracture following primary THA using a cementless stem. The effect of a collar in cementless THA on this risk was evaluated in an in vitro model using paired fresh frozen cadaveric femora. The prevalence of early revision for periprosthetic fracture was 0.34% (1180/337 647) and 44.0% (520/1180) occurred within 90 days of surgery. Implant risk factors included: collarless stem, non-grit-blasted finish, and triple-tapered design. In the in vitro model, a medial calcar collar consistently improved the stability and resistance to fracture. Analysis of features of stem design in registry data is a useful method of identifying implant characteristics that affect the risk of early periprosthetic fracture around a cementless femoral stem. A collar on the calcar reduced the risk of an early periprosthetic fracture and this was confirmed by biomechanical testing. This approach may be useful in the analysis of other uncommon modes of failure after THA. Cite this article: Bone Joint J 2019;101-B:779-786.

Introduction of a New Treatment Algorithm Reduces the Number of Periprosthetic Femoral Fractures After Primary Total Hip Arthroplasty in Elderly Females

Cemented Femoral Fixation in Total Hip Arthroplasty Reduces the Risk of Periprosthetic Femur Fracture in Patients 65 Years and Older: An Analysis From the American Joint Replacement Registry