Early Periprosthetic Fractures Research Articles

Outcomes of fixed versus mobile-bearing medial unicompartmental knee arthroplasty.

The optimal bearing surface design for medial unicompartmental knee arthroplasty (UKA) remains controversial. The aim of this study was to compare outcomes of fixed-bearing (FB) and mobile-bearing (MB) UKAs from a single high-volume institution. Prospectively collected data were reviewed for all primary cemented medial UKAs performed by seven surgeons from January 2006 to December 2022. A total of 2,999 UKAs were identified, including 2,315 FB and 684 MB cases. The primary outcome measure was implant survival. Secondary outcomes included 90-day and cumulative complications, reoperations, component revisions, conversion arthroplasties, range of motion, and patient-reported outcome measures. Overall mean age at surgery was 65.7 years (32.9 to 94.3), 53.1% (1,593/2,999) of UKAs were implanted in female patients, and demographics between groups were similar (p > 0.05). The mean follow-up for all UKAs was 3.7 years (0.0 to 15.6). Using revision for any reason as an endpoint, five-year survival for FB UKAs was 97.2% (95% CI 96.4 to 98.1) compared to 96.0% for MB (95% CI 94.1 to 97.9; p = 0.008). The FB group experienced fewer component revisions (14/2,315, 0.6% vs 12/684, 1.8%; p < 0.001) and conversion arthroplasties (38/2315, 1.6% vs 24/684, 3.5%; p < 0.001). A greater number of MB UKAs underwent revision due to osteoarthritis progression (FB = 21/2,315, 0.9% vs MB = 16/684, 2.3%; p = 0.003). In the MB group, 12 (1.8%) subjects experienced bearing dislocations which required revision surgery. There were 15 early periprosthetic tibia fractures (0.6%) in the FB group compared to 0 for MB (p = 0.035). In similar patient populations, FB UKAs demonstrated slightly higher survival than a commonly used MB design. Adverse event profiles differed by bearing type, with an increased risk of bearing dislocation and OA progression with MB designs, and early periprosthetic tibia fractures for FB designs.

COLLARED STEMS ARE A PROTECTIVE FACTOR AGAINST EARLY PERIPROSTHETIC FRACTURES IN TOTAL HIP ARTHROPLASTY: A MULTIVARIATE ANALYSIS IN A COHORT OF 1,623 PATIENTS

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.

Low Rate of Early Periprosthetic Fractures in Direct Anterior Total Hip Arthroplasty with a Triple-Tapered Wedge Stem.

Utilization of the direct anterior approach (DAA) for total hip arthroplasty (THA) has been steadily increasing in recent years. While the DAA may offer some benefits compared to other approaches, there are still risks involved including relatively higher rates of periprosthetic femur fractures, especially when combined with cementless femoral stem use. The purpose of this study is to evaluate the early postoperative femoral complications with a short triple-wedge tapered stem used in primary THA via a DAA. A retrospective review was conducted of the arthroplasty registry of our institution from April 2022 to August 2023 to identify patients who underwent a primary THA via a DAA with the Short Medacta Stem (SMS) (Medacta International, Castel San Pietro, Switzerland). Patients were excluded if the stem was used for a revision surgery, they were within 90 days of surgery, or they refused research consent. Inclusion criteria was met in 262 patients (302 hips). Data was collected after reviewing the chart, and reports and radiographic measurements, including Dorr type and canal fit ratios, were obtained from preoperative and postoperative radiographs, respectively. A total of 302 total hips were included, 161 patients were male (53.3%) and 141 were female (46.7%), with an average age of 66.5 years (27-88, +/- 10.7 years). Average follow up was 0.3 years (range, 0.05-1.71 years). The majority of patients had a Dorr B femur (81.7%). The Median stem size used was an 8 (range, 2-15), and 89.4% of those had a collar. Average canal fill ratio was 0.83 (range, 0.43-0.98, +/- 0.07). Overall, there were two Vancouver B2a periprosthetic femoral shaft fractures (0.66%) that required revision surgery to a modular stem. In addition, there were two Vancouver Ag greater trochanteric fractures (0.66%) with acceptable alignment that did not require revision surgery. Demographic information about the patients with femoral complications is summarized in Table I. Average age of patients with femoral complications was 69.5 years, with an average canal fit ratio of 0.88. We found that the triple-wedge implant had a low rate of early femoral complication in primary THA from an anterior approach and is safe for use in THA from a DAA. More follow up is needed to evaluate continuing implant survivorship and patient outcomes.

Low rate of periprosthetic femoral fracture with the Hueter anterior approach using stems cemented according to the 'French paradox'.

The aim of this retrospective study was to assess the incidence of early periprosthetic femoral fracture (PFF) associated with Charnley-Kerboull (CK) femoral components cemented according to the 'French paradox' principles through the Hueter anterior approach (HAA) in patients older than 70 years. From a prospectively collected database, all short CK femoral components implanted consecutively from January 2018 to May 2022 through the HAA in patients older than 70 years were included. Exclusion criteria were age below 70 years, use of cementless femoral component, and approaches other than the HAA. A total of 416 short CK prostheses used by 25 surgeons with various levels of experience were included. All patients had a minimum of one-year follow-up, with a mean of 2.6 years (SD 1.1). The mean age was 77.4 years (70 to 95) and the mean BMI was 25.3 kg/m2 (18.4 to 43). Femoral anatomy was classified according to Dorr. The measured parameters included canal flare index, morphological cortical index, canal-calcar ratio, ilium-ischial ratio, and anterior superior iliac spine to greater trochanter (GT) distance. Among the 416 THAs, two PFFs (0.48% (95% confidence interval 0.13 to 1.74)) were observed, including one Vancouver type B2 fracture 24 days postoperatively and one intraoperative Vancouver type B1 fracture. Valgus malalignment and higher canal bone ratio were found to be associated with PFF. This study demonstrated that short CK femoral components cemented according to the French paradox were associated with a low rate of early PFF (0.48%) in patients aged over 70 years. Longer follow-up is warranted to further evaluate the rate of fracture that may occur during the bone remodelling process and with time.

Hip &amp; Pelvis

The February 2024 Hip &amp; Pelvis Roundup360 looks at: Trial of vancomycin and cefazolin as surgical prophylaxis in arthroplasty; Is preoperative posterior femoral neck tilt a risk factor for fixation failure? Cemented versus uncemented hemiarthroplasty for displaced intracapsular fractures of the hip; Periprosthetic fractures in larger hydroxyapatite-coated stems: are collared stems a better alternative for total hip arthroplasty?; Postoperative periprosthetic fracture following hip arthroplasty with a polished taper slip versus composite beam stem; Is oral tranexamic acid as good as intravenous?; Stem design and the risk of early periprosthetic femur fractures following THA in elderly patients; Does powered femoral broaching compromise patient safety in total hip arthroplasty?

Deep-Learning Automation of Preoperative Radiographic Parameters Associated With Early Periprosthetic Femur Fracture After Total Hip Arthroplasty

BackgroundThe radiographic assessment of bone morphology impacts implant selection and fixation type in total hip arthroplasty (THA) and is important to minimize the risk of periprosthetic femur fracture (PFF). We utilized a deep-learning algorithm to automate femoral radiographic parameters and determined which automated parameters were associated with early PFF. MethodsRadiographs from a publicly available database and from patients undergoing primary cementless THA at a high-volume institution (2016 to 2020) were obtained. A U-Net algorithm was trained to segment femoral landmarks for bone morphology parameter automation. Automated parameters were compared against that of a fellowship-trained surgeon and compared in an independent cohort of 100 patients who underwent THA (50 with early PFF and 50 controls matched by femoral component, age, sex, body mass index, and surgical approach). ResultsOn the independent cohort, the algorithm generated 1,710 unique measurements for 95 images (5% lesser trochanter identification failure) in 22 minutes. Medullary canal width, femoral cortex width, canal flare index, morphological cortical index, canal bone ratio, and canal calcar ratio had good-to-excellent correlation with surgeon measurements (Pearson’s correlation coefficient: 0.76 to 0.96). Canal calcar ratios (0.43 ± 0.08 versus 0.40 ± 0.07) and canal bone ratios (0.39 ± 0.06 versus 0.36 ± 0.06) were higher (P < .05) in the PFF cohort when comparing the automated parameters. ConclusionsDeep-learning automated parameters demonstrated differences in patients who had and did not have early PFF after cementless primary THA. This algorithm has the potential to complement and improve patient-specific PFF risk-prediction tools.

Early Periprosthetic Femur Fractures After Primary Cementless Total Hip Arthroplasty: High Risk of Periprosthetic Joint Infection and Subsequent Reoperation

BackgroundPeriprosthetic femur fracture (PFF) following total hip arthroplasty (THA) is a leading cause of early reoperation. The objective of this study was to compare rates of periprosthetic joint infection (PJI) and reoperation following PFFs occurring early postoperatively to those that occurred late. MethodsWe retrospectively identified 173 consecutive surgically managed PFFs following primary THA. Cases were categorized as “early” if they occurred within 90 days of THA (n = 117) or “late” if they occurred following the initial 90 days (n = 56). Mean age at time of PFF was 68 years (range, 26 to 96) and 60% were women. Mean body mass index was 29 (range, 16 to 52). Mean follow-up was 2 years (range, 0 to 13). Kaplan-Meier survival analysis estimated cumulative incidences of PJI and reoperation. ResultsEarly PFFs had higher 2-year cumulative incidence of PJI (11% versus 0%, P < .001) and reoperation (24% versus 13%, P = .110). Following early PFF, 27 patients required reoperation (ie, 13 for PJI, 5 for instability, 2 for re-fracture, 2 for painful hardware, 2 for non-union, 1 for adverse local tissue reaction, 1 for aseptic loosening, and 1 for leg-length discrepancy). Following late PFF, 5 patients required reoperation (ie, 3 for instability, 1 for re-fracture, and 1 for non-union). ConclusionsThere are greater incidences of PJIs and overall reoperations following early PFFs compared to late PFFs after THA. In addition to focusing efforts on prevention of early PFFs, surgeons should consider antiseptic interventions to mitigate the increased risk of PJI after treatment of early PFF.

How Much Protection Does a Collar Provide? Assessing Risk of Early Periprosthetic Femur Fractures Following Total Hip Arthroplasty in Elderly Patients

BackgroundPeriprosthetic fractures (PPFs) account for approximately 25% of early revisions following total hip arthroplasty (THA). Cemented femoral fixation is associated with a lower-risk of PPF, and collared-cementless stems may reduce the risk as well. The objective of this study was to compare early-PPF rates between cemented, collared-cementless, and non-collared cementless stems in elderly patients. MethodsA consecutieve-series of 11,522 primary THAs performed between 2016 and 2021 at our institution in patients >65 years of age was identified. Stem types used were categorized as cemented, collared-cementless, or non-collared cementless. Patients undergoing THA who had cemented-stems were older, more commonly women, and more likely to have a posterior-approach. To reduce confounding of patient characteristics, we matched patients in the 3 stem-categories according to age, sex, and body mass index. This generated 3-groups (cemented, collared-cementless, and non-collared cementless) consisting of 936 patients per group. The mean age of these 2,808 patients was 73 years, the mean body mass index was 27, and 67% were women. Logistic regressions were used to evaluate risk-factors for early-PPF. In the entire cohort of primary THA in elderly patients, there were 85 early PPFs (0.7%) over the study period. ResultsNon-collared cementless stems were associated with an increased risk of early PPF (OR: 3.11; P = .03) compared to collared-cementless stems. There were no early PPFs in the matched cemented cohort, 6 early PPFs in the matched collared-cementless cohort, and 16 early-PPFs in the matched non-collared cementless cohort (0% versus 0.64% versus 1.71%, P < .001). ConclusionsIn this large-series of patients >65 years of age undergoing primary THA, cemented stem fixation had the lowest incidence of early PPF, but collared-cementless stems had a nearly 3-fold decrease in risk for early PPF compared to non-collared cementless stems.

Femoral Component Undersizing and Alignment are Risk Factors for Early Periprosthetic Femur Fracture.

Known risk factors for early periprosthetic femur fracture (PFF) following total hip arthroplasty (THA) include poor bone quality and the use of cementless implants. The association between femoral component size and alignment and the risk of early PFF is not well described. We evaluated radiographic parameters of femoral component sizing and alignment as risk factors for early PFF. From 16,065 primary cementless THAs, we identified 66 cases (0.41%) of early PFFs (<90 days from index THA) at a single institution between 2016 and 2020. Sixty early PFFs were (1:2) matched to 120 controls based on the femoral component model, offset, surgical approach, age, body mass index (BMI), and gender. Radiographic assessment of preoperative bone morphology and postoperative femoral component orientation included stem alignment, metaphyseal fill, and implant congruence with medial cortical bone. A multivariable logistic regression was built to identify radiographic risk factors associated with early PFF. Markers of preoperative bone quality including canal calcar ratio (P= .003), canal flare index (P < .001), anteroposterior canal bone ratio (CBR) (P < .001), and lateral CBR (P < .001) were statistically associated with PFF. Distance between the medial cortical bone and implant was greater in cases of PFF (2.5 mm vs 1.4 mm) (P < .001). A multivariate analysis demonstrated that a larger lateral metaphyseal CBR (Odds Ratio [OR] 5), valgus implant alignment (OR 5), and medial implant-bone incongruity (OR 2) increased the risk of early PFF. A larger lateral metaphyseal CBR, valgus component alignment, and implant incongruity with medial cortical bone posed the greatest radiographic risk for early PFF following cementless THA.

Survivorship, complications and patient-reported outcomes in calcar-guided short-stem THA: prospective mid-term multicenter data of the first 879 hips

IntroductionShort stems are a bone and soft-tissue preserving alternative to conventional stems. The aim of this multicenter study is to present the mid-term outcomes of a calcar-guided short stem.Materials and methodsThis is a prospective case series of the first 879 total hip arthroplasties performed on 782 patients across 5 centers using identical calcar-guided short stems. In a mid-term follow-up (6 years), rates and reasons for complications and revisions were documented. The Harris Hip Score (HHS) was obtained; patients reported pain and satisfaction using a visual analog scale.ResultsA total of 43 patients died in the study cohort for non-related reasons; 26 patients (3.0%) required at least 1 revision after the index procedure. The survival rate for endpoint stem revision at mid-term was 98.4%. The main reasons for stem revision were aseptic loosening and early periprosthetic fractures. Sex had no influence on stem survival. Older patients or those with a high body mass index showed increased risk for stem revision during follow-up. Dorr type A morphology revealed a significantly lower risk of stem revision than Dorr type B or C (p = 0.0465). The HHS, satisfaction, and load pain at mid-term were 96.5 (SD 8.0), 9.7 (SD 0.9), and 0.5 (SD 1.9), respectively.ConclusionsThis short stem produced highly satisfactory outcomes at mid-term, with 98.4% implant survival for any cause of stem revision and low complication rates. Long-term results are required to further evaluate these promising mid-term results.

Risk factors of early periprosthetic femoral fracture after total knee arthroplasty

BackgroundPeriprosthetic femoral fracture (PFF) is a serious complication after total knee arthroplasty (TKA). However, the risk factors of PFF in the early postoperative setting are not well documented. This study determines the risk factors of early PFF after primary TKA.MethodsThis study recruited 24 patients who had early PFF within postoperative 3 months and 96 control patients. Demographic data (age, gender, weight, height, body mass index, Deyo-Charlson comorbidity index, diagnosis, operated side, underlying diseases and history of steroid usage intraoperative outcomes), intraoperative outcomes (operative time, surgical approach, type and brand of the prosthesis), and radiographic outcomes (distal femoral width; DFW, prosthesis-distal femoral width ratio; PDFW ratio, anatomical lateral distal femoral angle; LDFA, the change of LDFA, femoral component flexion angle; FCFA and anterior femoral notching; AFN) were recorded and compared between groups. Details of PFF, including fracture pattern, preoperative deformity, and time to PFF were also documented.ResultsIn univariate analysis, the PFF group had significantly older, right side injury, rheumatoid, dyslipidemia, Parkinson patients than the control group (p < 0.05). No cruciate-retaining design was used in PFF group (p = 0.004). Differences between the prosthetic brand used were found in this study (p = 0.049). For radiographic outcomes, PFF group had significantly lower DFW but higher PDFW ratio and postoperative LDFA than the control group (p < 0.05). While the change of LDFA, FCFA and AFN were similar between groups. The fracture patterns were medial condylar (45.8%), lateral condylar (25.0%) and supracondylar fracture (29.2%). The mean overall time to PFF was 37.2 ± 20.6 days (range 8–87 days). Preoperative deformity was significantly different among the three patterns (p < 0.05). When performed multivariate analysis using the logistic regression model, age was only an independent risk factor for early PFF. The cut-off point of age was > = 75 years, with a sensitivity of 75.0% and specificity of 78.1%.ConclusionThis study determined that age was the independent risk factors for early PFF. However, further well-controlled studies with a larger sample size were needed to address this issue.

Varus malalignment of short femoral stem not associated with post-hip arthroplasty fracture.

Periprosthetic femoral fractures are an increasingly common post-operative complication of total hip arthroplasty (THA). Though varus malalignment is known to increase fracture risk in standard-length femoral stems, varus malalignment is not as well studied in short stems. Therefore, the purpose of this study was to determine if varus malalignment contributes to early periprosthetic fracture risk in a cementless taper-wedged, short femoral stem. This retrospective review included 366 consecutive patients (441 THAs) having undergone THA via anterior approach by a single surgeon between July 2014 and December 2016. All patients received the same short, cementless femoral stem. Femoral component angle was measured on 6-week post-THA weight-bearing radiographs, with malalignment defined as a femoral component angle exceeding 0° ± 3°. Periprosthetic femoral fracture and aseptic loosening occurring within 2 years post-THA were recorded. The final data analysis included 426 hips with a mean follow-up time of 32.9 ± 10.2months. Varus and neutral alignment occurred in 84 (19.6%) and 342 (79.9%) of stems, respectively. Three (0.7%) periprosthetic femoral fractures occurred within 2 years, all occurring in patients with neutrally aligned femoral stems. One (0.2%) stem failed due to aseptic loosening and was malaligned. Despite nearly 20% of stems placed in varus alignment, three of the four early complications occurred in a neutrally aligned stem. Based on these results, forceful intraoperative realignment of a short femoral stem with good initial fixation may present an unnecessary increased risk of intraoperative fracture.

Experimental analysis of early periprosthetic femoral fractures with uncemented straight hip stems

BackgroundThe periprosthetic femoral fracture is one of the most severe complications after total hip arthroplasty and is associated with an increased mortality. The underlying causes and the patient- and implant-specific risk factors of periprosthetic femoral fractures remain insufficiently understood. The aim of this study was to gain a more profound understanding of the underlying fracture mechanisms and to provide experimental datasets for validation of computational models. MethodsSix cadaveric femurs were implanted with straight hip stems (Zweymueller design) and loaded until fracture reproducing the clinically relevant load cases stumbling and sideways fall. Displacements and the strain distribution on the surface of the femurs and implants, as well as the fracture load and implant subsidence were measured. FindingsFor the load case stumbling the mean fracture load was 6743 N and two different mechanisms leading to fracture could be identified: high subsidence with low femoral bending and small subsidence with high femoral bending. For the load case sideways fall the mean fracture load was 1757 N and both tested femurs fractured due to a rotation of the hip stem around its own axis. The detailed datasets provided by this study can be used in future computational models. InterpretationWe demonstrated that the underlying fracture mechanisms of periprosthetic femoral fractures can be fundamentally different in the load case stumbling. The seating and exact position of the hip stem in the femur may correlate with implant subsidence and therefore lead to different types of fracture mechanisms resulting in different patient-specific fracture risks.

Low rate of early periprosthetic fractures in cementless short-stem total hip arthroplasty using a minimally invasive anterolateral approach

PurposeMinimally invasive (MIS) approaches in combination with short stems have gained popularity in recent years in total hip arthroplasty (THA). A decreased risk for periprosthetic femoral fractures (PFFs) is reported for cementless short-stem THA, but in contrast to other approaches, the risk factors for PFFs for short-stem THA using MIS anterolateral approach in supine position are not described in literature.MethodsA single-center consecutive series of 1052 hips in 982 patients, performed between 2014 and 2019 with a short curved stem and a press fit using an MIS anterolateral approach in supine position, was retrospectively screened for inclusion. Fourteen patients were lost to follow-up. Therefore, 1038 THAs in 968 patients were included. Risk factors for intra- and postoperative PFFs within 90 days were analyzed. We investigated for sex, age, body mass index (BMI), diagnosis, and laterality.ResultsIn total, 18 PFFs (1.7%) occurred. Intraoperative fracture occurred in ten cases ( 0.9%), with another eight cases (0.8%) occurring postoperatively. Increased American Society of Anesthesiologists (ASA) Score was a significant risk factor for PFF (p = 0.026), whereas sex (p = 0.155), age (p = 0.161), BMI (p = 0.996), and laterality (p = 1.000) were not. Seven PFFs (0.7%) required revision arthroplasty.ConclusionCementless short-stem THA using the MIS anterolateral approach is a procedure with a low number of PFFs within 90 days from index surgery. Fracture rates are comparable to other MIS approaches, and comparable femoral short stems are used. Age, sex, and BMI were not identified as risk factors of PFF, while risk for PFF increased with ASA Score.Level of EvidenceLevel IV

Uncemented total hip arthroplasty; increased risk of early periprosthetic fracture requiring revision surgery in elderly females

PurposeThe preferred method of stem fixation in total hip arthroplasty (THA) remains debatable. Uncemented THA favors a lower rate of aseptic loosening but has an increased risk of early periprosthetic fractures (EPF). We hypothesize that routine placement of uncemented THA by experienced surgeons diminishes this EPF-risk. The purpose of this study is to investigate the effect of age, gender, ASA classification and BMI of THA performed by experienced surgeons on the risk of EPF. MethodsA retrospective cohort study including all primary THAs and revision surgeries performed between 2012 and 2018. Possible predictive factors included are age, gender, BMI, ASA classification, presence of osteoporosis, Dorr classification, revision surgery type and clinical outcome. A number needed to treat (NNT) analysis was conducted assuming that cementing THA prevents EPF. Results2635 primary THAs were performed. Indications for 70 revisions included 18 EPF in uncemented THA female patients. Periprosthetic fractures without a relevant trauma occurred within six weeks in 16 patients. There was a statistically significant correlation between EPF-risk and age (P = 0.032), female gender (P = 0.001) and ASA classification (P = 0.015). For age ≥75, there was an increase in EPF (P = 0.047). With the assumption that cementing would prevent EPF, the NNT is 48. No statistically significant correlation was found between EPF and BMI, osteoporosis or Dorr classification. ConclusionFemale patients aged ≥75 have an increased EPF-risk after uncemented THA and would therefore benefit from treatment with a cemented stem. An ASA score of III-IV is an independent risk factor for EPF after uncemented THA.

Effect of stem position and length on bone-stem constructs after cementless hip arthroplasty.

AimsThere are concerns regarding initial stability and early periprosthetic fractures in cementless hip arthroplasty using short stems. This study aimed to investigate stress on the cortical bone around the stem and micromotions between the stem and cortical bone according to femoral stem length and positioning.MethodsIn total, 12 femoral finite element models (FEMs) were constructed and tested in walking and stair-climbing. Femoral stems of three different lengths and two different positions were simulated, assuming press-fit fixation within each FEM. Stress on the cortical bone and micromotions between the stem and bone were measured in each condition.ResultsStress concentration was observed on the medial and lateral interfaces between the cortical bone and stem. With neutral stem insertion, mean stress over a region of interest was greater at the medial than lateral interface regardless of stem length, which increased as the stem shortened. Mean stress increased in the varus-inserted stems compared to the stems inserted neutrally, especially at the lateral interface in contact with the stem tip. The maximum stress was observed at the lateral interface in a varus-inserted short stem. All mean stresses were greater in stair-climbing condition than walking. Each micromotion was also greater in shorter stems and varus-inserted stems, and in stair-climbing condition.ConclusionThe stem should be inserted neutrally and stair-climbing movement should be avoided in the early postoperative period, in order to preserve early stability and reduce the possibility of thigh pain, especially when using a shorter stem.Cite this article: Bone Joint Res 2021;10(4):250–258.

Periprosthetic early insufficiency fracture after total knee arthroplasty: a retrospective case series

Background: Early periprosthetic insufficiency fracture after total knee arthroplasty (TKA) is a rare, yet serious debilitating condition. Identification of the risk factors predisposing patients to this fracture is crucial to reduce its incidence. We aimed to investigate if patients who experienced early periprosthetic insufficiency fracture after TKA shared any specific characteristics. Methods: In a retrospective study, the characteristic features of 17 patients with early periprosthetic insufficiency fracture were reviewed. The index TKA was performed using a medial parapatellar approach and a cemented posterior-stabilized prosthesis. The demographic characteristics of the patients, including body mass index (BMI), preoperative alignment deformity, and postfracture bone mineral density (BMD), were evaluated. Results: The study population included 14 women and three men with the mean age of 71.4±7.2 yr. All patients returned with sudden sharp knee pain and inability to walk after the surgery. The mean time from surgery to the diagnosis of fracture was 23±13.3 days. Preoperative varus and valgus deformities were detected in 16 (94.1%) and one (5.9%) patient, respectively. The fracture occurred in the lateral condyle in all patients with varus deformity and the medial condyle in the patient with valgus deformity. All patients were identified with osteoporosis based on the post-fracture BMD evaluation. Thirteen (76.4%) patients were categorized as obese, and four patients as overweight. The size of the femoral condyle was small in the majority of patients. Conclusions: Severe knee deformity, osteoporosis, high BMI, and small size of the femoral condyle were the main risk factors of early periprosthetic insufficiency fracture. Level of Evidence: Level IV.

Use of a monoblock dual-mobility acetabular component in primary total hip arthroplasty in patients at high risk of dislocation.

Dislocation is amongst the most common complications following total hip arthroplasty (THA). Dual-mobility bearings have been suggested as one way to reduce the risk of dislocation, particularly among patients at increased risk. The purpose of this study was to determine the outcomes of a monoblock dual-mobility shell for patients at high risk for dislocation following primary THA. A total of 155 primary THAs with a monoblock, cementless dual-mobility acetabular component were performed in patients at high risk for dislocation. Two patients died prior to their two-year follow-up. The remaining 153 THAs were followed for a mean of 5.1 years (range: 2.1 to 9.3). There were no dislocations; however, four patients underwent revision surgery: one for an early periprosthetic acetabular fracture, one for an early periprosthetic femoral fracture, one for a late periprosthetic femoral fracture, and one for leg-length discrepancy. Intraoperative complications included one periprosthetic acetabular fracture treated with protected weight-bearing and one intraoperative proximal femoral fracture treated with cerclage wiring. Harris Hip Scores improved from a mean of 42.4 points preoperatively to a mean of 82.4 points postoperatively (p < 0.001). No cups were radiographically loose. At a mean follow-up of 5.1 years, survivorship of the acetabular component was 99.3% (95% CI, 98.1-100%) and survivorship without any reoperation was 97.4% (95% CI, 95.9-100%). Although there were no dislocations in this high-risk population, periprosthetic fractures of the femur and acetabulum were common with the implants utilised.

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

BackgroundIncreasing global usage of cementless prostheses in total hip arthroplasty (THA) presents a challenge, especially for elderly patients. To reduce the risk of early periprosthetic femoral fractures (PFFs), a new treatment algorithm for females older than 60 years undergoing primary THA was introduced. The aim of this study was to determine the impact of the new treatment algorithm on the early risk of perioperative and postoperative PFFs and guideline compliance. MethodsA total of 2405 consecutive THAs that underwent primary unilateral THA at our institution were retrospectively identified in the period January 1, 2013-December 31, 2018. A new treatment algorithm was introduced on April 1, 2017 with female patients aged older than 60 years intended to receive cemented femoral components. Before this, all patients were scheduled to receive cementless femoral components. Demographic data, number of perioperative and postoperative PFFs, and surgical compliance were recorded, analyzed, and intergroup differences compared. ResultsThe utilization of cemented components in female patients older than 60 years increased from 12.3% (n = 102) to 82.5% (n = 264). In females older than 60 years, a significant reduction in the risk in early postoperative and intraoperative PFF after introduction of the new treatment algorithm was seen (4.57% vs 1.25%; P = .007 and 2.29% vs 0.31%; P = .02, respectively). Overall risk for postoperative and intraoperative fractures combined was also reduced in the entire cohort (4.1% vs 2.0%; P = .01). ConclusionUse of cemented fixation of the femoral component in female patients older than 60 years significantly reduces the number of PFFs. Our findings support use of cemented femoral fixation in elderly female patients.

Postoperative 30-day complications after cemented/hybrid versus cementless total hip arthroplasty in osteoarthritis patients > 70 years

Background and purpose — The use of cementless total hip arthroplasty (THA) in elderly patients is debated because of increased risk of early periprosthetic femoral fractures. However, cemented femoral components carry a risk of bone cement implantation syndrome. Hence, we compared in-hospital complications, complications leading to readmission and mortality ≤ 30 days postoperatively between hybrid/cemented (cemented femoral component) vs. cementless THA in osteoarthritis patients > 70 years.Patients and methods — This is a prospective observational cohort study in 9 centers from January 2010 to August 2017. We used 30-day follow-up from the Danish National Patient Registry, patient records, and data from the Danish Hip Arthroplasty Register. Only THAs performed as a result of osteoarthritis were included.Results — 3,368 (42%) of the THAs were cemented/hybrid and 4,728 (58%) cementless. The in-hospital complication risk was 7.7% after cemented/hybrid vs. 5.3% after cementless THA (< 0.001), statistically not significant when adjusting for comorbidities (p = 0.1). There were similar risks of complications causing readmission (5.7% vs. 6.2%) and mortality ≤ 30 days (0.2% vs. 0.3%). 15 cases (0.4%) of pulmonary embolism (PE) were found after cemented/hybrid vs. 4 (0.1%) after cementless THA (p = 0.001); none occurred within 24 hours postoperatively. 2 of the PEs after cementless THA led to mortality. Cemented/hybrid THA remained significantly associated with risk of PE (RR 3.9, p = 0.02), when adjusting for comorbidities. BMI > 35 was associated with highest risk of PE (RR 5.7, p = 0.003). The risk of periprosthetic femoral fracture was 0.2% after cemented/hybrid vs. 1.5% after cementless THA (p < 0.001) and the risk of dislocations was 1.2% after cemented/hybrid THA vs. 1.8% after cementless THA (p = 0.04).Interpretation — The higher risk of PE after cemented/hybrid THA and higher risk of periprosthetic femoral fractures and dislocations after cementless THA highlights that both medically and surgically complications are related to fixation technique and have to be considered.