The prevention of periprosthetic fractures in total hip and knee arthroplasty

When does patient function "Plateau" after total joint arthroplasty? A cohort study

PURPOSE

With over 100,000 procedures completed per year, hip and knee arthroplasty are two of the most common surgical procedures performed in Canada. There has been literature indicating that patient reported outcome measures (PROM) will start to plateau between six and 12 months. The purpose of this paper was to analyze the trajectory of PROMs following total hip and knee arthroplasty (THA and TKA), as well as assess the impact of any potential confounders on this trajectory. The central research question was: At what point do PROMS plateau among patients that undergo elective THA and TKA?

METHODS

This study was a retrospective analysis of data from a prospective database. Patients were eligible if they had undergone an elective, primary THA/TKA with Oxford Scores recorded pre-operatively, and at least at two of the following four time points: six weeks, six months, one year, and two years.

RESULTS

Mean pre-operative Oxford scores were 18.0 (7.8) for THA, and 20.1 (7.5) for TKA. For both THA and TKA, there were statistically significant interval improvements in Oxford scores from six weeks [THA: 33.8 (7.9)/TKA: 28.7 (7.8)] to six months [THA: 40.2 (7.3)/TKA: 35.9 (8.3)], and from six months to one year [THA: 41.0 (7.3)/TKA: 37.3 (8.4)], but not from one to two years [THA: 40.0 (8.5)/TKA: 36.4 (9.6)].

CONCLUSIONS

Patients undergoing either primary THA or TKA can expect clinically meaningful improvements in the first six months after surgery. Beyond this time point, there is a plateau in PROMs. These findings are important for both setting patient expectations in pre-operative discussions, and allowing surgeons to have a realistic understanding of their patients' expected post-operative course.

Coxa valga and antetorta configuration leads to underestimation of the femoral component size: a matched case-control study of patients undergoing cementless total hip arthroplasty

BACKGROUND

Total hip arthroplasty (THA) is the gold standard procedure for patients with end-stage osteoarthritis after failed conservative therapy. Digital templating is commonly employed in preoperative preparation for THA and contributes positively to its outcome. However, the impact of coxa valga and antetorta (CVA) configurations on stem size prediction accuracy remains not reported. Previous studies demonstrated that the size of the lesser trochanter (LT) can be used to determine femoral anteversion on pelvis radiographs. This study investigates the accuracy of preoperative digital templating in predicting stem size in patients with CVA undergoing cementless THA.

METHODS

Preoperative radiographs of 620 patients undergoing cementless THA were retrospectively investigated. Radiographs were standardized with patients standing and the leg internally rotated by 15°. A CVA group was established including patients with a CCD angle greater than 140° and a lesser trochanter (LT) size of at least 10 mm for men and 8 mm for women. For the control group, radiographs with a CCD angle ranging from 125-135° and LT size 3-10 mm for men and 3-8 mm for women were selected. Preoperative templating was performed using mediCAD. To reduce confounding factors, case-control matching was carried out for BMI and body height.

RESULTS

After case-control matching, a total of thirty-one matches were analyzed. Stem size was underestimated in 74% (23/31) in the CVA and 13% (4/31) in the control group (p < 0.001). Moreover, patients with CVA were more likely to be underestimated by two sizes compared to controls (p < 0.004). In contrast, the exact stem size was predicted more frequently in the control group (p < 0.001).

CONCLUSION

Stem size in patients with a CVA configuration are at high risk of being underestimated when using digital templating. These findings can be valuable for guiding in intraoperative decisions and lowering the risk of complications associated with an undersized femoral component.

Two-Dimensional Versus Three-Dimensional Preoperative Planning in Total Hip Arthroplasty

BACKGROUND

Preoperative planning in total hip arthroplasty (THA) involves utilizing radiographs or advanced imaging modalities, including computerized tomography scans, for precise prediction of implant sizing and positioning. This study aimed to compare 3-dimensional (3D) versus 2-dimensional (2D) preoperative planning in primary THA with respect to key surgical metrics, including restoration of the horizontal and vertical center of rotation (COR), combined offset, and leg length.

METHODS

This study included 60 patients undergoing primary THA for symptomatic hip osteoarthritis (OA), randomly allocated to either robotic arm-assisted or conventional THA. Digital 2D templating and 3D planning using the robotic software were performed for all patients. All measurements to evaluate the accuracy of templating methods were conducted on the preoperative computerized tomography scanogram, using the contralateral hip as a reference. Sensitivity analyses explored differences between 2D and 3D planning in patients who had superolateral or medial OA patterns.

RESULTS

Compared to 2D templating, 3D templating was associated with less medialization of the horizontal COR (-1.2 versus -0.2 mm, P = .002) and more accurate restoration of the vertical COR (1.63 versus 0.3 mm, P < .001) with respect to the contralateral side. Furthermore, 3D templating was superior for planned restoration of leg length (+0.23 versus -0.74 mm, P = .019). Sensitivity analyses demonstrated that in patients who had medial OA, 3D planning resulted in less medialization of horizontal COR and less offset reduction. Conversely, in patients who had superolateral OA, there was less lateralization of horizontal COR and less offset increase using 3D planning. Additionally, 3D planning showed superior reproducibility for stem, acetabular cup sizes, and neck angle, while 2D planning often led to smaller stem and cup sizes.

CONCLUSIONS

Our findings indicated higher accuracy in the planned restoration of native joint mechanics using 3D planning. Additionally, this study highlights distinct variances between the 2 planning methods across different OA pattern subtypes, offering valuable insights for clinicians employing 2D planning.

Periprosthetic fracture following arthroplasty for femoral neck fracture: is a cemented stem protective?

BACKGROUND

Periprosthetic femoral fractures (PFF) carry significant morbidity following arthroplasty for femoral neck fracture (FNF). This study assessed fracture complications following arthroplasty for FNF and the effect of cement fixation of the femoral component on intraoperative and post-operative PFF.

METHODS

Between February 2014 and September 2021, 740 patients with a FNF who underwent arthroplasty were analyzed for demographics, surgical management, use of cement for fixation of the femoral component, and subsequent PFF. Variables were compared with Mann-Whitney or Chi-square as appropriate. Multivariate logistic regression was used to assess independent risk factors associated with intraoperative or post-operative PFF.

RESULTS

There were 163 THAs (41% cemented) and 577 HAs (95% cemented). There were 28 PFFs (3.8%): 18 post-operative and 10 intraoperative. Fewer post-operative PFFs occurred with cemented stems (1.63% vs. 6.30%, p = 0.002). Mean time from surgery to presentation with post-operative PFF was 14 months (0-45 months). Mean follow-up time was 10.3 months (range: 0-75.7 months). In multivariate regression, use of cement and THA was independently associated with decreased post-operative PFF (cement: OR 0.112, 95% CI 0.036-0.352, p < 0.001 and THA: OR 0.249, 95% CI 0.064-0.961, p = 0.044). More intraoperative fractures occurred during THA (3.68% vs. 0.69%, p = 0.004) and non-cemented procedures (5.51% vs. 0.49%, p < 0.001). In multivariate regression, use of cement was protective against intraoperative fracture (OR 0.100, CI 0.017-0.571, p = 0.010).

CONCLUSIONS

In patients with a FNF treated with arthroplasty, cementing the femoral component is associated with a lower risk of intraoperative and post-operative PFF. Choice of procedure may be based on patient factors and surgeon preference.

Analyzing the Accuracy of Digital Sizing on Long-Leg Alignment X-rays by Using a 1-Inch Ball Bearing: A Cheap and Effective Method

Background and objective Sizing on digital films is important for implants and planning deformity correction. CT is the most accurate digital measurement method. We use a 1-inch ball bearing (cost: $1) to size our long-leg standing films (LLSFs) when planning deformity correction. In this study, we aimed to assess the accuracy of digital measurements calibrated by this method. Methods We conducted An IRB-approved study involving 25 patients having both an LLSF with a 1-inch ball bearing taped to the inner mid-thigh and a CT scanogram. The longest distance in the axial cut of the bilateral ankle, knee, and femoral heads of the CT images were compared to the same anatomic locations on LLSFs calibrated with the ball bearing using the online digital planning software DetroitBonesetter (DBS) and measurements from our Picture Archiving Communication Software (PACS). Five observers performed each measurement. Results The average measurement differences between the gold standard CT scan and LLSFs calibrated with DBS were as follows: 0.110 ± 0.432 mm (femoral head); 2.173 ± 0.0619 mm (knee); and 3.671 ± 0.30 mm (ankle). In PACS, they were as follows: 5.470 ± 0.381 mm (femoral head); 6.248 ± 0.712 mm (knee); and 1.806 ± 0.548 mm (ankle). The intraclass correlation coefficient for 600 measurements by five observers was 0.972. Conclusions The $1 ball-bearing sizing on DBS using LLSFs provides accuracy to <1 mm for the femoral head, 2 mm at the knee, and 3.7 mm at the ankle. It was significantly better than the PACS system for both the femoral head and knee (<0.001), while PACS was better at the ankle (<0.001).

Automated digital templating of component sizing is accurate in robotic total hip arthroplasty when compared to predicate software

Accurate pre-operative templating of prosthesis components is an essential factor in successful total hip arthroplasty (THA), including robotically-assisted THA (RA-THA) techniques. We sought to validate the accuracy of a novel, robotic-optimized THA planning software compared to a predicate THA planner for component sizing. We analyzed a series of 199 patients who received manual THA (mTHA) and fluoroscopy-based RA-THA at a single institution. All cases were templated using a predicate pre-operative templating software. For RA-THA cases, the novel robotic-optimized pre-operative planner software was also used for templating. The differences between templated and implanted acetabular cup, femoral head, and stem component sizes were compared based on matching within 1, 2, and ≥3 sizes. Differences in templated and implanted femoral stem implant geometry were also compared. The robot-optimized pre-operative RA-THA plans demonstrated equivalent accuracy to that of predicate pre-operative plans for both RA-THA and mTHA cases. Templated acetabular cups (90.4 vs. 86.8 vs. 82.8; p = 0.421), femoral stems (76.0 vs. 65.1 vs. 67.7; p = 0.096), and femoral heads (91.3 vs. 96.2 vs. 88.2; p = 0.302) were within +/-1 size of implanted components. No significant differences were detected in the proportion of matching templated and implanted stem geometry across the study cohorts.

Accuracy of Personalized Computed Tomographic 3D Templating for Acetabular Cup Placement in Revision Arthroplasty

Background: Revision hip arthroplasty presents a surgical challenge, necessitating meticulous preoperative planning to avert complications like periprosthetic fractures and aseptic loosening. Historically, assessment of the accuracy of three-dimensional (3D) versus two-dimensional (2D) templating has focused exclusively on primary hip arthroplasty. Materials and Methods: In this retrospective study, we examined the accuracy of 3D templating for acetabular revision cups in 30 patients who underwent revision hip arthroplasty. Utilizing computed tomography scans of the patients' pelvis and 3D templates of the implants (Aesculap Plasmafit, B. Braun; Aesculap Plasmafit Revision, B. Braun; Avantage Acetabular System, Zimmerbiomet, EcoFit 2M, Implantcast; Tritanium Revision, Stryker), we performed 3D templating and positioned the acetabular cup implants accordingly. To evaluate accuracy, we compared the planned sizes of the acetabular cups in 2D and 3D with the sizes implanted during surgery. Results: An analysis was performed to examine potential influences on templating accuracy, specifically considering factors such as gender and body mass index (BMI). Significant statistical differences (p < 0.001) in the accuracy of size prediction were observed between 3D and 2D templating. Personalized 3D templating exhibited an accuracy rate of 66.7% for the correct prediction of the size of the acetabular cup, while 2D templating achieved an exact size prediction in only 26.7% of cases. There were no statistically significant differences between the 2D and 3D templating methods regarding gender or BMI. Conclusion: This study demonstrates that 3D templating improves the accuracy of predicting acetabular cup sizes in revision arthroplasty when compared to 2D templating. However, it should be noted that the predicted implant size generated through 3D templating tended to overestimate the implanted implant size by an average of 1.3 sizes.

[Innovative image-based planning in musculoskeletal surgery]

BACKGROUND

For the preparation of surgical procedures in orthopedics and trauma surgery, precise knowledge of imaging and the three-dimensional imagination of the surgeon are of outstanding importance. Image-based, preoperative two-dimensional planning is the gold standard in arthroplasty today. In complex cases, further imaging such as computed tomography (CT) or magnetic resonance imaging is also performed, generating a three-dimensional model of the body region and helping the surgeon in the planning of the surgical treatment. Four-dimensional, dynamic CT studies have also been reported and are available as a complementary tool.

DIGITAL AIDS

Furthermore, digital aids should generate an improved representation of the pathology to be treated and optimize the surgeon's imagination. The finite element method allows patient-specific and implant-specific parameters to be taken into account in preoperative surgical planning. Intraoperatively, relevant information can be provided by augmented reality without significantly influencing the surgical workflow.

Accuracy of digital templating in uncemented primary total hip arthroplasty: which factors are associated with accuracy of preoperative planning?

BACKGROUND

Preoperative planning is a fundamental step for successful total hip arthroplasty (THA). Studies have highlighted the accuracy of preoperative digital templating for estimating acetabular cup and stem size. Stem design such as single-wedge metadiaphyseal (Type 1 stem) versus mid-short stem (microplasty) and surgical approach (anterior, direct lateral or posterior) have not been well investigated as predictors of THA templating accuracy.

METHODS

204 patients (220 hips) who had undergone elective THA between November 2016 and December 2019 and presented a saved preoperative template were retrospectively reviewed. Templates from 5 different surgeons were involved in the analysis. 3 different approaches were used: direct lateral (DL), posterior (PA), direct anterior (DAA). 2 different stem designs were used: single-wedge metadiaphyseal and single-wedge mid-short (Biomet Taperloc Microplasty), while the acetabular component remained the same. Bivariate and multivariate regression analyses were performed to determine predictors of accuracy.

RESULTS

Femoral component size templating accuracy was significantly improved when using the single-wedge mid-short stem (Taperloc Microplasty) design when performing bivariate analysis. Although accuracy of cup sizing was not affected by approach, precision was significantly better in the PA group (p < 0.05). Accuracy of templating was found to be independent of BMI and gender but dependent on presence of calibration marker and stem design (p < 0.05).

CONCLUSIONS

When striving for improved templating accuracy, acetabular and femoral component accuracy were best achieved using a calibration marker and a metaphyseal short femoral stem design.

Cemented Femoral Stem Fixation: Back to the Future

BACKGROUND

Periprosthetic fractures following elective and non-elective hip arthroplasty remain one of the most common modes of early failure.

METHODS

This symposium will explore the current role of cemented fixation and periprosthetic fracture, focusing on history and rationale for cemented stem fixation, registry data and other potential advantages of cemented stem fixation. A meticulous and methodical surgical technique of cemented stem fixation is paramount to the success and will be thoroughly discussed.

RESULTS

The role of stem fixation, and its effect on periprosthetic fracture is well-documented in the literature. Yet despite this, the utilization of cemented stem fixation remains low in the United States. This paradox is multifactorial.

CONCLUSIONS

In addition to a notable reduction in the risk of periprosthetic femur fractures, cemented stem fixation has numerous other advantages and is reproducible with a methodical surgical technique.

Comparison of the Accuracy of 2D and 3D Templating for Revision Total Hip Replacement

Introduction: Revision hip arthroplasty is a challenging surgical procedure, especially in cases of advanced acetabular bone loss. Accurate preoperative planning can prevent complications such as periprosthetic fractures or aseptic loosening. To date, the accuracy of three-dimensional (3D) versus two-dimensional (2D) templating has been evaluated only in primary hip and knee arthroplasty. Methods: We retrospectively investigated the accuracy of 3D personalized planning of reinforcement cages (Burch Schneider) in 27 patients who underwent revision hip arthroplasty. Personalized 3D modeling and positioning of the reinforcement cages were performed using computed tomography (CT) of the pelvis of each patient and 3D templates of the implant. To evaluate accuracy, the sizes of the reinforcement cages planned in 2D and 3D were compared with the sizes of the finally implanted cages. Factors that may potentially influence planning accuracy such as gender and body mass index (BMI) were analyzed. Results: There was a significant difference (p = 0.003) in the accuracy of correct size prediction between personalized 3D templating and 2D templating. Personalized 3D templating predicted the exact size of the reinforcement cage in 96.3% of the patients, while the exact size was predicted in only 55.6% by 2D templating. Regarding gender and BMI, no statistically significant differences in planning accuracy either for 2D or 3D templating were observed. Conclusion: Personalized 3D planning of revision hip arthroplasty using Burch Schneider reinforcement cages leads to greater accuracy in the prediction of the required size of implants than conventional 2D templating.

Intraoperative Fractures of the Tibia and Femur in Knee Revision Surgery

Intra-operative fractures in knee revision surgery are relatively rare and have not been well studied. They may occur during joint exposition, removal of the prosthesis or cement, or implantation of trial or original components. The fractures affect both the metaphyseal area and diaphysis of the tibia and femur. Tibial fractures are slightly more common than femur fractures. On the femur, the medial condyle is most frequently affected, followed by the femur diaphysis. The use of non-cemented stems is associated with a greater risk of intra-operative diaphyseal fractures than that of cemented stems. Overall, women and patients with an osteopenic bone structure have a higher risk of fractures. It is common that fractures are diagnosed post-operatively. In these cases, conservative therapy may be successful, depending on the stability of the prosthesis and bones. The most common surgical fixation options are cerclages and screws, followed by stem extensions for bridging the fracture. Plate fixation or use of strut grafts are also sensible therapy options. Overall, intraoperative fractures have a high healing potential with stable and good joint function. The revision rate is still 15%, which is most often caused by peri-prosthetic infection.

The insidious risk of periprosthetic fracture in clinically functional total hip arthroplasties: A biomechanical study of willed joints

Femoral bone quality is a major risk factor of periprosthetic fracture after total hip arthroplasty (THA), which has mortality similar to native hip fractures but higher short-term morbidity. The goal of this study was to quantify cortical strains at the site of expected Vancouver Type-B periprosthetic fracture as a function of bone mineral density, femoral stem material, and fixation method using a series of 29 autopsy-retrieved, clinically asymptomatic hip joints with THA. Periprosthetic bone mineral content and density was assessed using dual-energy X-ray absorptiometry by Gruen Zone. Specimens then underwent combined cyclic axial and torsional loading, increasing incrementally from 100 N and ±1 Nm to peaks of 700 N and ±5 Nm. All specimens experienced significantly higher strains on the lateral surface than on the anterior surface, indicating that the bending loads in the frontal plane, rather than axial/torsional loads, had the predominant effect. Multiple significant relationships (p = 0.04, p = 0.02) were found between predicted periprosthetic strains calculated from radiographic measurements and observed principal strains. Though THA in the present study were in successful clinical service, the produced results indicated that some femurs with rigid cemented or noncemented implants were potentially at high risk for Vancouver Type-B fractures, which may be predicted radiographically.

Zoledronic Acid for Periprosthetic Bone Mineral Density Changes in Patients With Osteoporosis After Hip Arthroplasty-An Updated Meta-Analysis of Six Randomized Controlled Trials

Introduction: Periprosthetic bone mineral density (BMD) loss following total hip arthroplasty (THA) may threaten the survival of the implant, especially in patients with osteoporosis. Zoledronic acid (ZA) is the representative of the third generation of bisphosphonates, which were effective in reducing bone loss in conditions associated with accelerated bone turnover. The aim of this study was to evaluate the efficacy and safety of ZA in patients with osteoporosis after THA. Methods: Randomized controlled trials (RCTs) associated with ZA and THA were searched from the MEDLINE, PubMed, EMBASE, Wanfang database, and the Web of Science (August 2021). Other methods, such as hand search and email request were also tried. The methodological quality was assessed by the Risk of Bias (RoB) 2.0. Relevant data were abstracted from the included RCTs and authors were contacted when necessary. Results: In this study, six RCTs involving a total of 307 patients were finally included and analyzed. The pooled data demonstrated that significantly less periprosthetic BMD loss in Gruen zone seven had occurred in the ZA-treated patients than in the control patients at 3 months (mean difference [MD] = 4.03%; 95% CI: 0.29-7.76%; P = 0.03), 6 months (MD = 7.04%; 95% CI: 2.12-11.96%; P = 0.005), and 12 months (MD = 7.12%; 95% CI: 0.33-13.92%; P = 0.04). The Harris Hip Score (HHS) was also significantly increased in ZA group at 6 and 12 months after operation (P = 0.03 and P = 0.02, respectively). Influenza-like symptom was found related to the usage of ZA [relative risk (RR) = 7.03, P < 0.0001]. Conclusion: A meta-analysis of six RCTs suggested that ZA was beneficial in maintaining the periprosthetic BMD in patients with osteoporosis at 6 and 12 months after THA. In addition, the HHS was significantly improved in patients treated with ZA. However, the short length of follow-up of the available studies resulted in the lack of analyses regarding the survival of implants including the rate of aseptic loosing, periprosthetic fracture, and revision. It still needs to be determined in research with longer follow-up period. Clinical Trial Registration: Researchregistry.com, identifier: reviewregistry1087.

Zoledronic Acid for Periprosthetic Bone Mineral Density Changes in Patients With Osteoporosis After Hip Arthroplasty-An Updated Meta-Analysis of Six Randomized Controlled Trials

Introduction: Periprosthetic bone mineral density (BMD) loss following total hip arthroplasty (THA) may threaten the survival of the implant, especially in patients with osteoporosis. Zoledronic acid (ZA) is the representative of the third generation of bisphosphonates, which were effective in reducing bone loss in conditions associated with accelerated bone turnover. The aim of this study was to evaluate the efficacy and safety of ZA in patients with osteoporosis after THA.

Methods: Randomized controlled trials (RCTs) associated with ZA and THA were searched from the MEDLINE, PubMed, EMBASE, Wanfang database, and the Web of Science (August 2021). Other methods, such as hand search and email request were also tried. The methodological quality was assessed by the Risk of Bias (RoB) 2.0. Relevant data were abstracted from the included RCTs and authors were contacted when necessary.

Results: In this study, six RCTs involving a total of 307 patients were finally included and analyzed. The pooled data demonstrated that significantly less periprosthetic BMD loss in Gruen zone seven had occurred in the ZA-treated patients than in the control patients at 3 months (mean difference [MD] = 4.03%; 95% CI: 0.29–7.76%; P = 0.03), 6 months (MD = 7.04%; 95% CI: 2.12–11.96%; P = 0.005), and 12 months (MD = 7.12%; 95% CI: 0.33–13.92%; P = 0.04). The Harris Hip Score (HHS) was also significantly increased in ZA group at 6 and 12 months after operation (P = 0.03 and P = 0.02, respectively). Influenza-like symptom was found related to the usage of ZA [relative risk (RR) = 7.03, P < 0.0001].

Conclusion: A meta-analysis of six RCTs suggested that ZA was beneficial in maintaining the periprosthetic BMD in patients with osteoporosis at 6 and 12 months after THA. In addition, the HHS was significantly improved in patients treated with ZA. However, the short length of follow-up of the available studies resulted in the lack of analyses regarding the survival of implants including the rate of aseptic loosing, periprosthetic fracture, and revision. It still needs to be determined in research with longer follow-up period.

Clinical Trial Registration:Researchregistry.com, identifier: reviewregistry1087.

Medial peg position of cementless porous tantalum tibial component affects bone mineral density around the prosthesis after total knee arthroplasty: 2-year follow-up study

BACKGROUND

Use of a porous tantalum tibial component for total knee arthroplasty (TKA) was reported to have beneficial effects on periprosthetic bone mineral density (BMD). In some cases, hexagonal peg is placed close to or in contact with the tibial cortex, which may result in stress-shielding around the peg. However, no studies have analyzed the relationship between peg position and BMD. The aim of this study was to compare the peg position and BMD around the peg in a porous tantalum tibial component after TKA.

METHODS

Twenty-seven patients (27 knees) who underwent primary TKA with a cementless porous tantalum tibial component were investigated. BMD was measured by dual-energy X-ray absorptiometry for 2 years after the operation. The distance between the peg and the tibial cortex (peg distance) was measured on the medial and lateral sides.

RESULTS

BMD was decreased in the medial region after the operation (p < 0.01). Relative change in BMD was lower in the medial region than in the central and lateral regions (p < 0.01). Multiple regression analysis showed that medial peg distance was negatively correlated with relative change of BMD in the medial part of the tibia (p = 0.04, R = 0.402).

CONCLUSIONS

The medial peg position affected the postoperative relative change of BMD in the medial part of the tibia, but did not affect the longevity of the implant. As the tibial medial peg became closer to the medial tibial cortex, the BMD loss became larger in the medial part of the tibia at 2 years postoperatively.

Precision and accuracy of pre-surgical planning of non-cemented total hip replacement with calibrated digital images and acetates

Background

When approaching a joint replacement procedure, pre-surgical planning is essential to predict an accurate estimation of implant size and position. There are currently two methods to achieve it, analog and digital. The present study aims to demonstrate how the hybrid technique is accurate and precise for pre-surgical planning in a non-cemented total hip replacement.

Methods

Concordance-type study is used against a gold standard, as well as inter- and intra-observer consistency evaluation of two orthopedic surgeons and two orthopedic surgery residents. Accuracy was calculated with the intra-class correlation coefficient (ICC). Afterwards, the same calculation was done considering a margin of error with one size more and one less.

Results

Thirty-eight patients were included in the study: 19 women and 19 men. Twenty-two prostheses (57.89%) were right-sided and 16 were left (42.11%). Twelve prostheses (31.57%) were Stryker and 26 Johnson & Johnson (68.43%). Acetabular cup correlation compared with the gold standard was moderate: ICC reported 0.45 (95% CI, 0.15–0.76). When adjusted by ± 1 size, ICC was 0.48 (95% CI, 0.18–0.79). On the other hand, results from the femoral stem reported ICC 0.85 (95% CI, 0.07–0.98). When adjusted by ± 1 size, ICC was 0.86 (95% CI, 0.06–0.99).

Conclusions

Hybrid templating is a reliable substitute for analog or digital planning. It is quick, inexpensive, accurate, and better results are observed in the femoral component regardless the level of expertise of the evaluator.

Level of evidence

Grade IV

Bone Mineral Density Testing in Patients Undergoing Total Ankle Arthroplasty: Should We Pay More Attention to the Bone Quality?

Total ankle arthroplasty (TAA) has become one of the standard treatments for end-stage ankle arthritis. Long-term TAA survivorship is reported from 63% to 95%, with aseptic loosening being the most common mode of failure. Several studies have shown that low bone mineral density (BMD) of the hip affects the longevity of prosthetic implants. The role of Dual energy X-ray absorptiometry for TAA has not been established. The purpose of this review was to define the role of BMD in TAA outcomes and the role of Dual energy X-ray absorptiometry in measuring periprosthetic BMD. There is a paucity of information and published literature regarding the relationship between BMD and TAA. From attempting this systematic review, we hope to highlight that much of the focus in total ankle arthroplasty has emphasized implants and relatively little has focused on the quality of bone into which the prostheses are implanted.

Secondary Osseous Integration of Cementless Unicompartmental Knee Arthroplasty After Internal Fixation of a Felix Type IIIB Fracture: A Case Report

CASE

A 76-year-old man presented with periprosthetic tibial plateau fracture (TPF), with a completely loosened tibial component 3 weeks after cementless unicompartmental knee arthroplasty (UKA). Internal fixation by buttress plating was performed, and the tibial component was retained and left in situ primarily as a spacer. Revision was planned after fracture consolidation, but at 3 months, the patient was able to walk without support, without pain, and with full range of motion. At 1 year, he is free of complaints. The initial loosened tibial component reintegrated.

CONCLUSION

Internal fixation combined with preserving the loosened tibial component may be a treatment option for TPF involving a cementless UKA.

EOS Imaging is Accurate and Reproducible for Preoperative Total Hip Arthroplasty Templating

BACKGROUND

Templating is a critical part of preoperative planning for total hip arthroplasty (THA). The accuracy of templating on images acquired with EOS is unknown. This study sought to compare the accuracy and reproducibility of templating for THA using EOS imaging to conventional digital radiographs.

METHODS

Forty-three consecutive primary unilateral THAs were retrospectively templated, six months postoperatively, using preoperative 2D EOS imaging and conventional radiographs. Two blinded observers templated each case for acetabular and femoral component size and femoral offset. The retrospectively templated sizes were compared to the sizes selected during surgery. Interobserver agreement was calculated, and the influence of demographic variables was explored.

RESULTS

EOS templating predicted the exact acetabular and femoral size in 71% and 66% of cases, respectively, and to within one size in 98% of cases. The acetabular and femoral component size was more likely to be templated to the exact size using EOS compared to conventional imaging (P < .05). The femoral component offset choice was accurately predicted in 83% of EOS cases compared to 80% of conventional templates (P = .341). Component size and offset were not influenced by patient age, gender, laterality, or BMI. Interobserver agreement was excellent for acetabular (Cronbach's alpha = 0.94) and femoral (Cronbach's alpha = 0.96) component size.

CONCLUSIONS

Preoperative templating for THA using EOS imaging is accurate, with an excellent interobserver agreement. EOS exposes patients to less radiation than traditional radiographs, and its three-dimensional applications should be explored as they may further enhance preoperative plans.

Impact of intraoperative femoral fractures in primary hip arthroplasty: a comparative study with a mid-term follow-up

BACKGROUND

Intraoperative femoral fractures (IFF) during primary total hip arthroplasty (THA) pose a major clinical challenge, and data on mid-term implant performance, functional outcome and patient satisfaction is limited.

METHODS

50 patients who sustained IFFs during primary THA were retrospectively reviewed. A control group of patients who received a primary THA without complications was matched according to gender, age, body mass index and indication for THA. Both groups were followed-up for a minimum duration of 2 years. Average follow-up duration was 5.6 years (range 2-11.8 years) for the fracture group and 6 years (range 4.1-8.3 years) for the control group respectively. The following parameters were assessed and compared: stem revision, Harris Hip Score improvement, pain scale improvement, WOMAC, Tegner Score, UCLA, SF-36, forgotten joint score and patient satisfaction.

RESULTS

There were no stem revisions in the fracture group and 1 stem revision in the control group. Stem survival was 100% and 98.1% respectively (p = 0.447). The mean improvement in Harris hip score was 35.3 and 44.8 respectively. Significantly lower Harris Hip score improvement (p = 0.021) and patient satisfaction (p = 0.01) were observed in the fracture group. All other acquired parameters did not show significant differences.

CONCLUSION

Intraoperative fractures of the proximal femur are a relevant complication that does not lead to higher revision rates but might worsen the functional outcome and negatively impact patient satisfaction in mid-term follow-up even if treated appropriately.

Intra-operative fractures in primary total knee arthroplasty - a systematic review

BACKGROUND

One of the rare complications of primary total knee arthroplasty is intra-operative fracture. Intra-operative fracture during revision knee arthroplasty has been well-documented but there is limited literature on fractures occurring during primary knee arthroplasty. We conducted a systematic review of the literature to compare and contrast the various studies to clearly define the predisposing factors, incidence, and characteristics of the fracture itself and to arrive at a consensus on the management and prevention of intra-operative fractures during primary knee arthroplasty.

METHODS

The PubMed/Medline, Cochrane, Scopus and Embase databases were searched using keywords "intra-operative fracture", "distal femoral fracture", "tibial fracture", "patella fracture" and "primary total knee arthroplasty". A total of 158 articles were retrieved and after further filtration and exclusion processing, 10 articles that evaluated intra-operative fractures in primary total knee arthroplasty were included for the review.

RESULTS

The reported incidence of intra-operative fractures varied from 0.2% to 4.4%. A higher incidence in female patients with a male to female ratio of 0.4 was reported. Posterior stabilized (PS) total knee arthroplasty was associated with higher risk of intra-operative femoral fractures by many authors in this review. Timing of occurrence and location of the intra-operative fractures can vary widely, with femoral fractures occurring more commonly during bone preparation, trialing and impaction of the final implant and tibial fractures occurring during preparation for the tibial keel and impaction of the tibial component.

CONCLUSIONS

Intra-operative fractures during primary total knee arthroplasty are rare with higher risk associated with osteoporosis, rheumatoid arthritis, advanced age, female gender, chronic steroid use, metabolic bone disorders, PS type of femoral implant and difficult surgical exposure of the knee joint due to severe deformities. A plethora of management options have been utilized according to surgeon preference. Standard principles of fracture fixation and arthroplasty principles should be followed to achieve stable internal fixation and any unstable fracture site should be bypassed with the utilization of stemmed components. Satisfactory radiographic and functional outcome can be expected with appropriate treatment.

Total Hip Arthroplasty Digital Templating: Size Predicting Ability and Interobserver Variability

BACKGROUND

During the last century, total hip arthroplasties have become more popular. They have had a huge impact on the quality of life, pain, range of motion, social interaction, and psychological well-being. A number of studies have emphasized the importance of using templates to choose the appropriate implant size when planning the surgery. Our aim is to use MediCad^® software to analyze the ability of the digital template system MediCad^® to predict the size of the implant needed in total hip arthroplasties.

MATERIALS AND METHODS

An arthroplasty preoperative plan was created according to the MediCad^® software guidelines, on anteroposterior hip X-ray by one junior resident, one senior resident, and three experienced hip surgeons.

RESULTS

The median size accuracy was 0.7 (range: 0.27-0.87) for the cup, 0.73 (range: 0.36-0.83) for the stem, and 0.28 (range: -0.14-0.69) for the neck. Interobserver reliability was good (kappa > 0.4) and stronger when measuring the stem than when doing so with the cup. Conclusion: Digital preoperative total hip arthroplasty planning is a good method for predicting component size, restoring hip anatomy (vertical offset and horizontal offset), with good interobserver reliability.

[Periprosthetic fractures of the acetabulum: osteosynthesis]

In most cases periprosthetic fractures of the acetabulum are complex injuries and are extremely challenging for the treating medical team. Over the years the frequency of this overall rare entity has increased due to demographic changes. In recent years several treatment algorithms were published and provided the possibility of developing standardized treatment concepts. The classification of the fractures and a dedicated preoperative strategy are highly important for the quality of patient-centered care. In the literature the frequency of intraoperative fractures was initially given as 0.4%; however, several studies have been published in which a far higher rate of intraoperative fractures was detected by computed tomography (CT), often referred to as so-called occult fractures. The causes are multifactorial and there is significant association with whether cement-free press-fit acetabular cups were used or cemented forms. In approximately 75% of the cases a low energy impact was the cause of the fracture. In these patients systemic processes, such as osteoporotic alterations of the bony substance or the possible presence of low-grade infections should be considered. This article gives an overview of the diagnostics, planning, challenges and osteosynthetic treatment options for periprosthetic fractures of the acetabulum.

Periprosthetic fractures of the proximal femur within first year of the index hip prosthesis

Introduction:

Periprosthetic fractures are a serious complication of implants prosthetic. The aim of this review is to analyze incidence and predisposing factors of periprosthetic fractures of the proximal femur within first year of the index hip prosthesis.

Materials and methods:

Between 1998 and 2017 we have performed 4240 hip replacements (F 2661, M 1579): 2877 total hip arthroplasties (67,9%) and 1363 hemiartrhoplasties (32,1%). Hip replacements with cemented stem were 2173 (51,2%), while cementless ones were 2067 (48,8%). In the same period we admitted 121 hip periprosthetic fractures, 26 of which (0,6%) within the first year of the index surgery. We examined the medical and radiographic records of this last cohort of patients (F 19, M 7) following the Vancouver System, Dorr Classification and Stem Size Index.

Results:

The cause was a low-energy trauma in 25 cases (96.1%); the primary diagnosis was hip fracture in 20 patients (76.9%); 8 patients were taking chronic osteoporosis medication (30.7%); 14 patients were affected by neuropsychiatric disease (53.8%); cementless stems were found in 18 cases, 12 of which were oversized (SSI < 0,8). According to Vancouver System, fractures were classified as follows: 10 type B1, 14 type B2 and 2 type C. As far as the proximal femoral shape, 2 cases were Dorr type A, 7 Dorr type B and 17 Dorr type C.

Conclusions:

The incidence of periprosthetic fractures in the aftermath of stem implant is twice as high with uncemented stems. The Vancouver type B1/B2 is the most common. Predisposing factors are: female sex, hip fracture, chronic osteoporosis medication, neuropsychiatric disease and oversized uncemented stem (SSI < 0.8).The evidence level is IV. (www.actabiomedica.it)

Outcomes of Total Hip Arthroplasty in Patients With Acetabular Protrusio

Background:

Acetabular protrusio (AP) is associated with distorted anatomic landmarks and insufficient bone stock that increases complexity of total hip arthroplasty (THA). This study used a large national database to compare outcomes after THA in patients with and without AP.

Methods:

The Nationwide Readmissions Database was used to identify patients with and without AP who underwent THA from 2010 to 2014. Primary outcomes analyzed included complications during index hospitalization and within 90 days of THA.

Results:

Propensity score matching generated 4,395 patients without AP and 4,603 patients with AP. Patients with AP were older (68.1 versus 65.2 years, P < 0.0001), more predominantly women (82.1% versus 55.9%), and had more medical comorbidities as measured by the Elixhauser Comorbidity Index (2.29 versus 1.89, P < 0.0001). Patients with AP had an increased risk of requiring bone graft (odds ratio [OR] = 47.97, 95% confidence interval [CI]: 14.27 to 161.22), receiving a blood transfusion (OR = 1.90, 95% CI: 1.57 to 2.29), and suffering a periprosthetic fracture (OR = 2.56, 95% CI: 1.10 to 5.97) within 90 days of THA. Length and cost of index hospitalization were greater for patients with AP (5.0 versus 4.3 days, P = 0.002; $19,211.88 versus $27,736.30, P < 0.0001).

Conclusion:

Given the current emphasis on hospital cost optimization, it is important to ensure that patients with AP are managed appropriately. Attention should be placed on comprehensive preoperative planning and postoperative monitoring in this population.

Reduced periprosthetic fracture rate when changing from a tapered polished stem to an anatomical stem for cemented hip arthroplasty: an observational prospective cohort study with a follow-up of 2 years

Background and purpose - Straight collarless polished tapered stems have been linked to an increased risk for periprosthetic femur fractures in comparison with anatomically shaped stems, especially in elderly patients. Therefore, we evaluated the effect of an orthopedic department's full transition from the use of a cemented collarless, polished, tapered stem to a cemented anatomic stem on the cumulative incidence of postoperative periprosthetic fracture (PPF). Patients and methods - This prospective single-center cohort study comprises a consecutive series of 1,077 patients who underwent a cemented hip arthroplasty using either a collarless polished tapered stem (PTS group, n = 543) or an anatomic stem (AS group, n = 534). We assessed the incidence of PPF 2 years postoperatively and used a Cox regression model adjusted for age, sex, ASA class, cognitive impairment, BMI, diagnosis, and surgical approach for outcome analysis. Results - Mean age at primary surgery was 82 years (49-102), 73% of the patients were female, and 75% underwent surgery for a femoral neck fracture. The PPF rate was lowered from 3.3% (n = 18) in the PTS group to 0.4% (n = 2) in the AS group. The overall complication rate was also lowered from 8.8% in the PTS group to 4.5% in the AS group. In the regression model only cognitive dysfunction (HR 3.8, 95% CI 1.4-10) and the type of stem (PTS vs AS, HR 0.1, CI 0.0-0.5) were correlated with outcome. Interpretation - For elderly patients with poor bone quality use of cemented anatomic stems leads to a substantial reduction in periprosthetic fracture rate without increasing other complications.

Periprosthetic femoral fractures after total hip arthroplasty: An algorithm of treatment

BACKGROUND

Periprosthetic femoral fractures (PFFs) following total hip arthroplasty are becoming more prevalent and management of these fractures is often demanding. The surgeon has to assess in detail implant loosening, bone loss and type of fracture. The aim of the study is to identify the suitability of a treatment algorithm, based on the Vancouver classification that takes into account the activity and comorbidity of each patient.

PATIENTS AND METHODS

This study retrospectively assessed 38 patients who were surgically treated for a PFF around total hip arthroplasty between 2010 and 2014. All fractures were classified according to the Vancouver classification. There were 14 type B1, 8 type B2, 10 type B3 and 6 type C fractures. The data examined were age, sex, mechanism of injury, type of fracture, ASA score, type of surgery and complications. Radiographic evaluations were performed at 1, 3, 6 months and every 12 months thereafter. Clinical results were measured using the Merle-d'Aubigné-Postel score. Treatment options included an ORIF in 22 patients and a stem revision in 16 patients, with or without plates or supplemental cortical strut grafting when required.

RESULTS

The mean duration of follow-up was 3.1 years, mean age was 71.2 years and six patients (15.7%) died. Union was obtained in all patients in a mean of 16 weeks. Three patients required a surgical revision: one for stem loosening and two for re-fracture after a new fall. One patient had varus malunion of the femur. The mean postoperative Merle-d'Aubigné-Postel score was 13.2. Thirteen patients showed excellent results, 14 had a good result, three had a fair outcome and two had a poor result. Twenty patients returned to their baseline mobility status, while 12 patients had either a decline in their ambulatory status or a need for additional assistive devices.

CONCLUSIONS

PFF remains a serious complication of hip arthroplasty that is accompanied by high morbidity and mortality rates. This study shows how patients' comorbidities and functional demand can direct the proper treatment. This is a suitable algorithm for the treatment of PFF, which can provide satisfactory results in terms of pain and function.

Templating Hip Arthroplasty

BACKGROUND:

Different methods have been developed and employed with variable degrees of success in pre-operative templating for total hip arthroplasty. Preoperative templating, especially digital templating, has been claimed to have increased the effectiveness of total hip arthroplasty by improving the precision of prediction of prosthetic implant size.

AIMS:

The overall aim of this systematic review is to identify whether the use of pre-operative templating in total hip arthroplasty procedures has resulted in increased accuracy, reliability and precision of the procedure. Various methods of templating, like traditional acetate overlay and digital method of templating that includes a single radiographic marker and double radiographic marker methods, have been compared to establish the most reliable method of templating.

METHODS:

We searched the PubMed, Google Scholar Cochrane Central Register of Controlled Trials (CENTRAL), and MEDLINE (1966 to present), EMBASE (1980 to present), CINAHL (1982 to present), Psych INFO (1967 to present) and Clinical Trials Gov.

CONCLUSION:

The results of this systemic review suggest that preoperative templating is resulting in an enormous increase in the accuracy of total hip arthroplasty and among various methods, King Mark is the most reliable method.

More reoperations for periprosthetic fracture after cemented hemiarthroplasty with polished taper-slip stems than after anatomical and straight stems in the treatment of hip fractures

Aims

The aim of this large registry-based study was to compare mid-term survival rates of cemented femoral stems of different designs used in hemiarthroplasty for a fracture of the femoral neck.

Patients and Methods

From the Norwegian Hip Fracture Register (NHFR), 20 532 primary cemented bipolar hemiarthroplasties, which were undertaken in patients aged > 70 years with a femoral neck fracture between 2005 and 2016, were included. Polished tapered stems (n = 12 065) (Exeter and CPT), straight stems (n = 5545) (Charnley, Charnley Modular, and Spectron EF), and anatomical stems (n = 2922) (Lubinus SP2) were included. The survival of the implant with any reoperation as the endpoint was calculated using the Kaplan–Meier method and hazard ratios (HRs), and the different indications for reoperation were calculated using Cox regression analysis.

Results

The one-year survival was 96.0% (95% confidence interval (CI) 95.6 to 96.4) for the Exeter stem, 97.0% (95% CI 96.4 to 97.6) for the Lubinus SP2 stem, 97.6% (95% CI 97.0 to 98.2) for the Charnley stem, 98.1% (95% CI 97.3 to 98.9) for the Spectron EF stem, and 96.4% (95% CI 95.6 to 97.2) for the Charnley Modular stem, respectively. The hazard ratio for reoperation after one year was lower for Lubinus SP2 (HR 0.77, 95% CI 0.60 to 0.97), Charnley (HR 0.64, 95% CI 0.48 to 0.86), and Spectron EF stems (HR 0.44, 95% CI 0.29 to 0.67) compared with the Exeter stem. Reoperation for periprosthetic fracture occurred almost exclusively after the use of polished tapered stems.

Conclusion

We were able to confirm that implant survival after cemented hemiarthroplasty for a hip fracture is high. Differences in rates of reoperation seem to favour anatomical and straight stems compared with polished tapered stems, which had a higher risk of periprosthetic fracture.

Costs and Risk Factors for Hospital Readmission After Periprosthetic Knee Fractures in the United States

BACKGROUND

Periprosthetic fractures (PPFX) around total knee arthroplasty (TKA) are devastating complications with significant morbidity. With growing healthcare costs, hospital readmissions have become a marker for quality healthcare delivery. However, little is known about the risk factors or costs associated with readmission after treatment of PPFX. We sought to identify the patient demographics, prevalence of treatment types (open reduction internal fixation [ORIF] vs revision TKA), 30 and 90-day readmission rates, costs of initial treatment and readmission, and risk factors for readmission.

METHODS

We used the 2013 Nationwide Readmissions Database to select patients who underwent TKA, revision TKA, and treatment of PPFX with either ORIF or revision TKA. The 90-day readmission rate was determined through a survival analysis, and risk factors were identified using a cox proportional hazards model that adjusted for patient and hospital characteristics.

RESULTS

We identified 1526 patients with PPFX treated with ORIF and 1458 treated with revision TKA. Ninety-day readmissions were 20.5% and 21.8%, respectively. Patients with ORIF were more often female and had multiple medical comorbidities. Patient factors associated with readmission included advanced age, male gender, comorbidities, discharge to a skilled nursing facility or home with health aide, and Medicare or Medicaid insurance. Treatment at a teaching hospital was the only hospital-associated risk factor identified. ORIF cost USD 25,539 and revision THA cost USD 37,680, with associated readmissions costing 15,269 and 16,806, respectively.

CONCLUSION

PPFX results in greater costs compared to primary and revision TKA. This study highlights risk factors for readmission after PPFX treatment.

The Effect of Prophylactic Cerclage Wires in Primary Total Hip Arthroplasty: A Biomechanical Study

BACKGROUND

Despite literature to support the use of various cerclage techniques to address intraoperative femoral fractures in total hip arthroplasty, there are limited data to support prophylactic cerclage wiring of the femur during cementless implant placement. This study aims to evaluate the effect of prophylactic calcar cerclage wires on the biomechanical parameters required to produce periprosthetic femoral fractures and on the morphology of these fracture patterns in stable cementless femoral implants.

METHODS

Ten pairs of matched fresh frozen cadaveric femurs were implanted with anatomic tapered cementless implants with or without the addition of 2 monofilament calcar wires. Specimens were axially loaded and externally rotated to failure. Initial torsional stiffness, rotation and energy to failure, and torque at failure were measured. Statistical significance was set at P < .05. Fracture patterns were classified according to a well-known classification system.

RESULTS

Wired specimens required significantly more rotation (P = .039) and energy to failure (P = .048). No significant difference was detected in initial torsional stiffness (P = .63) or torque at failure (P = .10). All unwired samples developed a Vancouver B2 fracture pattern. Seven of the 8 wired specimens also developed a Vancouver B2 fracture pattern, while the eighth wired specimen developed a Vancouver B1 fracture pattern.

CONCLUSION

Prophylactic cerclage wire placement increases the rotation and energy to failure in well-fixed press-fit femoral implants. The increase in torsional energy needed for failure may reduce the risk of early periprosthetic fracture. Further studies are needed to evaluate cost vs benefit and long-term outcomes of prophylactic wiring. Based on the results of our study, consideration of prophylactic wiring should be addressed on a case-to-case basis.

Risk factors for post-operative periprosthetic fractures following primary total hip arthroplasty with a proximally coated double-tapered cementless femoral component

AIMS

The aim of this study was to identify patient- and surgery-related risk factors for sustaining an early periprosthetic fracture following primary total hip arthroplasty (THA) performed using a double-tapered cementless femoral component (Bi-Metric femoral stem; Biomet Inc., Warsaw, Indiana).

PATIENTS AND METHODS

A total of 1598 consecutive hips, in 1441 patients receiving primary THA between January 2010 and June 2015, were retrospectively identified. Level of pre-operative osteoarthritis, femoral Dorr type and cortical index were recorded. Varus/valgus placement of the stem and canal fill ratio were recorded post-operatively. Periprosthetic fractures were identified and classified according to the Vancouver classification. Regression analysis was performed to identify risk factors for early periprosthetic fracture.

RESULTS

The mean follow-up was 713 days (1 to 2058). A total of 48 periprosthetic fractures (3.0%) were identified during the follow-up and median time until fracture was 16 days, (interquartile range 10 to 31.5). Patients with femoral Dorr type C had a 5.2 times increased risk of post-operative periprosthetic fracture compared with type B, while female patients had a near significant two times increased risk over time for post-operative fracture.

CONCLUSION

Dorr type C is an independent risk factor for early periprosthetic fracture, following THA using a double tapered cementless stem such as the Bi-Metric. Surgeons should take bone morphology into consideration when planning for primary THA and consider using cemented femoral components in female patients with poor bone quality. Cite this article: Bone Joint J 2017;99-B:451-7.

Acetate templating on calibrated standing digital radiograph improves accuracy of preoperative templating for total hip arthroplasty

BACKGROUND

The accuracy of preoperative templating with respect to leg length, femoral offset, and the size of femoral and acetabular components is essential to the success of total hip arthroplasty (THA). Traditionally, templating has been performed using printed film with acetate templates. However, preoperative templating designed by different prosthetic manufacturers cannot be used directly on the film due to varying acetate template amplification ratios. Computer-based templating needs specialized digital templating software, which has cost implications. To address these shortcomings, we bring forward several questions: (1) the accuracy of traditional manual templating combined with the calibrated digital radiograph for preoperative templating, (2) the inter- and intraobserver reliability of this method.

HYPOTHESIS

Using calibrated digital radiograph with traditional manual templating improves the accuracy and reproducibility of preoperative templating for THA.

PATIENTS AND METHODS

We designed a stepwise method that combines the traditional manual templating with standing digital radiograph calibrated by a scaling ball. Two separate observers (XJL, QYG) analyzed data of 82 patients (109 THAs) who had undergone THA with preoperative templating using the calibrated digital templating. The intra- and interobserver reliability was assessed by intraclass correlation coefficient.

RESULTS

The size of the acetate template acetabular based on our method was identical to the actual implanted acetabular size in 55.0% (XJL 110/218 [50.5%]; QYG 130/218 [59.6%]) of the cases indicating moderate accuracy. The intraclass correlation coefficient (ICC) for acetabular templating indicated almost perfect interobserver (ICC=0.918 [95% CI, 0.893-0.937]) and intraobserver agreement (ICC=0.932 [95% CI, 0.912-0.947]). While the exact implanted femoral size was predicted in 55.3% (XJL 122/218 [56.0%]; QYG 119/218 [54.6%]) of the cases. The ICC for femoral component templating indicated almost perfect interobserver (ICC=0.944 [95% CI, 0.927-0.957]) and intraobserver agreement (ICC=0.909 [95% CI, 0.883-0.930]).

DISCUSSION

This new stepwise method may prove to be a more reliable preoperative design choice to accurately calibrate magnification with radiograph, and could solve the incompatibility of the preoperative template designed by different prosthetic companies for direct use with the x-ray film. The method described is practical, convenient, cost-effective and does not require specialized equipment or software, thus making it particularly suitable for use in underdeveloped settings.

LEVEL OF EVIDENCE

Level IV, case series without controls.

Periprosthetic femoral bone loss in total hip arthroplasty: systematic analysis of the effect of stem design

INTRODUCTION

Periprosthetic bone loss may lead to major complications in total hip arthroplasty (THA), including loosening, migration, and even fracture. This study analysed the influence of femoral implant designs on periprosthetic bone mineral density (BMD) after THA.

METHODS

The results of all previous published studies reporting periprosthetic femoral BMD following THA were compiled. Using these results, we compared percent changes in bone loss as a function of: femoral stem fixation, material, and geometry.

RESULTS

The greatest bone loss was in the calcar region (Gruen Zone 7). Overall, cemented stems had more bone loss distally than noncemented stems, while noncemented stems had more proximal bone loss than cemented stems. Within noncemented stems, cobalt-chromium (CoCr) stems had nearly double the proximal bone loss compared to titanium (Ti) alloy stems. Finally, within noncemented titanium alloy group, straight stems had less bone loss than anatomical, tapered, and press-fit designs.

DISCUSSION

The findings from the present study quantified percent changes in periprosthetic BMD as a function of fixation method, alloy, and stem design. While no one stem type was identified as ideal, we now have a clearer understanding of the influence of stem design on load transfer to the surrounding bone.

The Importance of Bone Mineral Density in Hip Arthroplasty: Results of a Survey Asking Orthopaedic Surgeons about Their Opinions and Attitudes Concerning Osteoporosis and Hip Arthroplasty

Objective. In patients scheduled to undergo total joint arthroplasty of the hip, the bone quality around the joint affects the safety of prosthetic implantation. Bone strength is clinically assessed by measuring bone mineral density (BMD); therefore we asked if BMD is important to orthopaedic surgeons performing hip arthroplasty. Methods. In a 14-question survey, we asked about treatment patterns with respect to BMD, osteoporosis work-up, and treatment for patients with low BMD scheduled to undergo hip arthroplasty. Results. 72% of all asked orthopaedics reported to use cementless implants as a standard in hip arthroplasty. Over 60% reported that low BMD is a reason to reconsider operation strategies, but only 4% performed BMD measurement preoperatively. 26% would change their treatment strategy in case of a BMD (T-Score) between −1.5 and −2 and 40% in case of a T-score between −2 and −2.5, and 29% would change their intraoperative strategy if a T-score smaller than −2.5 was measured. Conclusion. The majority of orthopaedic surgeons who responded to the survey reported that they do not perform routine measurement of BMD before arthroplasty. However, most surgeons commented that low bone mineral density will influence their surgical plan and the implant design.

Late onset imminent femoral fatigue fracture associated with intraoperative cement extrusion as a rare cause of thigh pain after total hip replacement

INTRODUCTION

Cement extrusions on the femoral side after total hip replacement can occur in approximately 0.3% of cemented primary total hip replacements. Not recognised until a postoperative x-ray is performed, the willingness to dismiss and treat these extrusions conservatively is high.

METHODS

We report on 3 patients presenting with sudden onset of thigh pain associated with an inability to weight-bear after a 2 to 15 month period of uneventful healthy recovery from cemented total hip replacement. On immediate postoperative x-rays occult cement extrusion in the posterolateral circumference of the femoral component tip were present. X-rays and CT scans showed no fracture signs. Scintigraphy revealed late increased uptake at the extrusion height. With the hypothesis of imminent femoral fatigue fracture, all patients underwent revision surgery. The defect sites were surgically exposed, thoroughly cleaned of cement, filled with iliac crest bone graft and stabilised with tension band plating.

RESULTS

This procedure resulted in fully recovered asymptomatic patients at 6 weeks and after a mean follow-up period of 48 months, as demonstrated by their pain level and tolerance of full weight bearing.

CONCLUSIONS

These cases lead us to adopt a low threshold for immediate revision when occult cement extrusion is recognised near the tip of a cemented stem on postoperative films, and to adopt a low threshold for surgical revision when, in the presence of cement extrusion, thigh pain is a complaint. We favour tension band plating and bone grafting over more complex implant revisions since a fast recovery was achieved in these patients.

Epidemiology of periprosthetic femoral fractures in 5417 revision total hip arthroplasties: a 40-year experience

AIMS

The goals of this study were to define the risk factors, characteristics, and chronology of fractures in 5417 revision total hip arthroplasties (THAs).

PATIENTS AND METHODS

From our hospital's prospectively collected database we identified all patients who had undergone a revision THA between 1969 and 2011 which involved the femoral stem. The patients' medical records and radiographs were examined and the relevant data extracted. Post-operative periprosthetic fractures were classified using the Vancouver system. A total of 5417 revision THAs were identified.

RESULTS

There were 668 intra-operative fractures, giving an incidence of 12%. Fractures were three times more common with uncemented stems (19%) than with cemented stems (6%) (p < 0.001). The incidence of intra-operative femoral fracture varied by uncemented stem type: fully-coated (20%); proximally-coated (19%); modular fluted tapered (16%) (p < 0.05). Most fractures occurred during the insertion of the femoral component (35%). One-third involved the diaphysis and 26% were of the calcar: 69% were undisplaced. There were 281 post-operative fractures of the femur (20-year probability = 11%). There was no difference in risk for cemented and uncemented stems. Post-operative fractures were more common in men < 70 years (p = 0.02). Periprosthetic fractures occurred earlier after uncemented revision of the femoral component, but later after a cemented revision. The most common fracture type was a Vancouver B1 (31%). Of all post-operative fractures, 24% underwent open reduction and internal fixation and 15% revision arthroplasty.

CONCLUSION

In revision THA, intra-operative fractures occurred three times more often with an uncemented stem. Many were undisplaced diaphyseal fractures treated with cerclage fixation. While the risk of post-operative fracture is similar between uncemented and cemented components, they occur at notably different times depending on the type of stem fixation.

TAKE HOME MESSAGE

In revision THA, intra-operative periprosthetic femoral fractures occur three times more often with uncemented stems. Many are non-displaced diaphyseal fractures treated with cerclage fixation. While postoperative fracture risks are equivalent between uncemented and cemented components, they occur at notably different time periods based on stem fixation type.

Outcomes of Surgical Treatment of Periprosthetic Femoral Fractures in Cementless Hip Arthroplasty

Purpose

We aimed to evaluate the results of surgical treatment of periprosthetic femoral fractures in cementless total hip arthroplasty (THA).

Materials and Methods

From June 2002 to May 2012, 40 patients who could be followed-up for more than 1 year after surgery were enrolled in this study. The mean duration of follow-up was 28.5 months (range, 15-97 months) and the average age at the time of surgery was 71.5 years (range, 38-89 years). The fracture types were determined by using the Vancouver classification. Among intraoperative fractures, there were type A in 3 hips, type B2 in 2 hips and type B3 in one. Among postoperative fractures, type AG was present in 5 hips, type AL in 2 hips, type B1 in 15 hips, type B2 in 6 hips, type B3 in 3 hips, and type C in 3 hips. Evaluation of the results was based on bony union, stability of the prosthesis, postoperative complications, and Harris hip score at the final follow-up.

Results

Bony union was achieved in all but one case and the average time for bony union was 21 weeks. The mean Harris hip score was 86 at the final follow-up. Clinical results were above good in 34 of 40 hips (85.0%). Stem loosening occurred in one patient with a type B1 fracture treated with open reduction and plate fixation. Nonunion was observed in 1 patient with an AG type fracture.

Conclusion

Open reduction and fixation using a plate with a screw and cerclage wiring provided good results for periprosthetic fractures in patients who had a stable femoral stem without bone defects. Revision surgery with a cementless long stem should be considered in patients with an unstable stem or suspected stability in B1 type of THA using a proximal fixation type.

Bone restoration with cemented Exeter universal stem - Three-years longitudinal DEXA study in 165 hips for femur

BACKGROUND

The pattern of strain distribution in the proximal femur changes following total hip arthroplasty (THA) and decreases in bone mineral density (BMD) occur around the stem following cemented and uncemented THA. We herein prospectively examined changes in BMD for 3 years after THA with a cemented Exeter universal stem.

METHODS

One hundred and sixty five hips from 150 patients who underwent unilateral THA were included as a cohort. Our patients included 20 men (20 hips) and 130 women (145 hips) with a mean age of 63.9 years. BMD was measured 2 weeks postoperatively (baseline) and 3, 6 12, 18, 24, 30, and 36 months (3 years) after surgery using dual-energy X-ray absorptiometry (DEXA) on the lumbar spine and proximal femur of the operated side according to the Gruen zone classification. We quantified longitudinal changes in BMD for more than 3 years after surgery and detected several factors which affected these changes.

RESULTS

In the first year, BMD in the most proximal femur showed a 5.5% reduction at the lateral side (zone 1) and 13% reduction at the medial side (zone 7), with no significant BMD reductions being observed thereafter. BMD reductions at 3 years were the most apparent at the proximal medial part of the femur (zone 7; -10.3%), while BMD ratio change in zone 1 was over the baseline (+2.9%). Especially in zone 7, the BMD ratio decreased with female, decreases in weight, decreases in height, decreases in BMI, and increases in age at the time of surgery.

CONCLUSIONS

Bone restoration is expected with a cemented Exeter universal stem. Male patients, a younger age, a high body weight, being tall, and a high BMI were identified as factors associated with the restoration of BMD in proximal femur.

Local bone quality affects the outcome of prosthetic total knee arthroplasty

Osteoporosis and osteoarthritis commonly coexist in the elderly. In patients undergoing prosthetic total knee arthroplasty (TKA), the bone quality around the knee joint may affect the safety of prosthetic implantation and consequently satisfaction with the surgical outcome. We recruited 50 postmenopausal women undergoing TKA for primary osteoarthritis; 43 completed the study protocol. The bone quality parameters of the operated knee, including bone mineral density assessed using dual-energy X-ray absorptiometry and microarchitecture variables assessed using micro-computed tomography, were determined. Surgical outcomes were assessed according to immediate (<1 week) postoperative pain quantified using the visual analog scale and knee function quantified using the Knee Injury and Osteoarthritis Outcome Score (KOOS) at 2 and 6 months postoperatively. The influence of bone quality parameters on surgical outcomes was analyzed using simple and multiple regression analyses. Volumetric bone mineral density (R(2)  = 0.187-0.234, p < 0.01), the structural model index (R(2)  = 0.103-0.181, p < 0.05), and trabecular separation (R(2)  = 0.289-0.424, p < 0.05) were significantly associated with postoperative pain and improvement according to the KOOS. In conclusion, local bone quality, including mineral content and microarchitecture, affects the surgical outcome of TKA.

Acetate templating on digital images is more accurate than computer-based templating for total hip arthroplasty

BACKGROUND

Templating is an important aspect of preoperative planning for total hip arthroplasty and can help determine the size and positioning of the prosthesis. Historically, templating has been performed using acetate templates over printed radiographs. As a result of the increasing use of digital imaging, surgeons now either obtain additional printed radiographs solely for templating purposes or use specialized digital templating software, both of which carry additional cost.

QUESTIONS/PURPOSES

The purposes of this study was to compare acetate templating of digitally calibrated images on an LCD monitor to digital templating in terms of (1) accuracy; (2) reproducibility; and (3) time efficiency.

METHODS

Acetate onlay templating was performed directly over digital radiographs on an LCD monitor and was compared with digital templating. Five separate observers participated in this study templating on 52 total hip arthroplasties. For the acetate templating, the digital images were magnified to the scaled reference on the templates provided by the manufacturer (ratio 1.2:1) before templating using a 25-mm marker as a reference. Both the acetate and digital templating results were then compared with the actual implanted components to determine accuracy. Interobserver and intraobserver variability was determined by an intraclass correlation coefficient. Observers recorded time to complete templating from the time of complete upload of patients' imaging onto the system to completion of templating.

RESULTS

Both acetate and digital templates demonstrated moderate accuracy in predicting within one size of the eventual implanted acetabular cup (77% [199 of 260]; 70% [181 of 260], respectively; p = 0.050; 95% confidence interval [CI], 0.058-0.32), whereas acetate templating was better at predicting the femoral stem compared to digital templating (75% [195 of 260]; 60% [155 of 260], respectively; p < 0.001; 95% CI, 0.084-0.32). Acetate templating showed moderate to substantial interobserver agreement (cup intraclass correlation coefficient [ICC] = 0.55; 95% CI, 0.14-0.86; femoral ICC = 0.75; 95% CI, 0.39-0.95) and both methods showed almost perfect intraobserver agreement in reproducibility (acetate cup ICC = 0.82; 95% CI, 0.66-0.97; acetate femoral ICC = 0.86; 95% CI, 0.74-0.97; digital cup ICC = 0.82; 95% CI, 0.68-0.97; digital femoral ICC = 0.88; 95% CI, 0.77-1.0). Acetate templating could be performed more quickly (acetate mean 119 seconds; range, 37-220 seconds versus 154 seconds; range, 73-343 seconds; p < 0.001).

CONCLUSIONS

Acetate onlay templating on digitally calibrated images can be a reliable substitute for digital templating using specialized software. It is quicker to perform and much less expensive. Hospitals and practices need not purchase expensive software, particularly at lower volume centers.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Periprosthetic fractures around the femoral stem: overcoming challenges and avoiding pitfalls

Management of periprosthetic fractures around the femoral stem after total hip arthroplasty (THA) represents a significant challenge and optimal treatment remains controversial. The most common treatment paradigm involves treating fractures around a well-fixed stem with osteosynthesis, whereas fractures around a loose stem require revision arthroplasty and those with poor bone require augmentation with bone graft. Paradoxically, the literature reports a higher rate of failure for osteosynthesis around prostheses considered to be well-fixed. Such a high rate of poor outcomes may result not only from difficult fracture fixation and compromised biologic healing, but also from unrecognized peri-implant pathology. Therefore, proper preoperative and intraoperative evaluation is key, and a subset of patients may benefit from alternative management. We review the appropriate methods for evaluation and treatment of Vancouver type B fractures with particular emphasis on avoiding missteps that can lead to failure.

Treatment of periprosthetic femoral fractures after femoral revision using a long stem

BACKGROUND

Periprosthetic femoral fractures are becoming increasingly common and are a major complication of total hip arthroplasty and hemiarthroplasty. The treatment of periprosthetic femoral fracture after femoral revision using a long stem is more complex and challenging. The purpose of this study was to identify the clinical and radiographical features of periprosthetic femoral fractures after revision using a long stem.

METHODS

We report a retrospective review of the outcomes of treatment of 11 periprosthetic fractures after femoral revision using a long stem. Eleven female patients with a mean age of 79.2 years (70 to 91) were treated for a Vancouver type B1 fracture between 1998 and 2013. The mean numbers of previous surgeries were 3.1 (2 to 5).

RESULTS

The average follow-up was 58.9 months (8 to 180). We found several important features that might influence the outcome of treatment for periprosthetic femoral fractures after femoral revision using a long stem: 1) all cases were classified as Vancouver type B1. 2) 6 patients (55%) had a transverse fracture around the tip of the long stem. 3) 7 patients (64%) had a history of previous fracture of the ipsilateral femur. The type B1 fractures were treated with open reduction and internal fixation in 9 hips, 6 of which were reinforced with bone grafts. Two other periprosthetic fractures were treated with femoral revision. One was revised because of stem breakage, and the other was a transverse fracture associated with poor bone quality, which received a femoral revision with a long stem and a plate. All fractures except one achieved primary union. This failed case had a bone defect at the fracture site, and revision surgery using a cementless long stem and allografts was successful.

CONCLUSIONS

These findings suggest that most cases of type B1 fracture after revision using a long stem have been treated successfully with open reduction and internal fixation. However, a transverse fracture with very poor bone quality might be considered as a type B3 fracture, and femoral revision might be a treatment of choice.

High risk of early periprosthetic fractures after primary hip arthroplasty in elderly patients using a cemented, tapered, polished stem

BACKGROUND AND PURPOSE

Postoperative periprosthetic femoral fracture (PPF) after hip arthroplasty is associated with considerable morbidity and mortality. We assessed the incidence and characteristics of periprosthetic fractures in a consecutive cohort of elderly patients treated with a cemented, collarless, polished and tapered femoral stem (CPT).

PATIENTS AND METHODS

In this single-center prospective cohort study, we included 1,403 hips in 1,357 patients (mean age 82 (range 52-102) years, 72% women) with primary osteoarthritis (OA) or a femoral neck fracture (FNF) as indication for surgery (367 hips and 1,036 hips, respectively). 64% of patients were ASA class 3 or 4. Hip-related complications and need for repeat surgery were assessed at a mean follow-up time of 4 (1-7) years. A Cox regression analysis was used to evaluate risk factors associated with PPF.

RESULTS

47 hips (3.3%) sustained a periprosthetic fracture at median 7 (2-79) months postoperatively; 41 were comminute Vancouver B2 or complex C-type fractures. The fracture rate was 3.8% for FNF patients and 2.2% for OA patients (hazard ratio (HR) = 4; 95% CI: 1.3-12). Patients > 80 years of age also had a higher risk of fracture (HR = 2; 95% CI: 1.1-4.5).

INTERPRETATION

We found a high incidence of early PPF associated with the CPT stem in this old and frail patient group. A possible explanation may be that the polished tapered stem acts as a wedge, splitting the femur after a direct hip contusion. Our results should be confirmed in larger, registry-based studies, but we advise caution when using this stem for this particular patient group.

Incidence and predisposing factors of periprosthetic proximal femoral fractures: a literature review

PURPOSE

The purpose of this review article was to investigate the incidence and predisposing factors for periprosthetic proximal femoral fractures (PFF) following total hip arthroplasty.

METHODS

We performed a comprehensive search of the medical literature in MEDLINE and EMBASE databases to review articles related to PFF, their incidence and risk factors.

RESULTS AND CONCLUSIONS

The incidence of PPF after primary THA was, in general, lower than after revision THA both for intra- and postoperative PFF. The rate of intraoperative PFF ranged from 0.1% to 27.8% and of postoperative PFF from 0.07% to 18%. Predisposing factors for intraoperative PFF are osteoporosis, rheumatoid arthritis, femoral preparation and surgical technique used to insert the rasp or femoral component, the use of press-fit cementless stems, and revision THA. In case of postoperative PFF, the following seem to be significant risk factors: advanced age, female gender, post-traumatic osteoarthritis, osteoporosis and rheumatoid arthritis, proximal femoral deformities, previous surgery of the affected hip, implant type (especially cementless stems and press-fit implantation), technical errors such as cortical perforation, cortical stress risers, low-energy trauma, osteolysis, loosening and revision THA.

Value of computed tomography-based three-dimensional surgical preoperative planning software in total hip arthroplasty with developmental dysplasia of the hip

INTRODUCTION

Preoperative planning with computed tomography (CT)-based three-dimensional templating has been expanded to achieve more precise placement of hip components. However, few reports have addressed the utility of three-dimensional surgical planning software for secondary osteoarthritis cases. This study therefore investigated the value of CT-based three-dimensional templating software for preoperative planning in primary total hip arthroplasty (THA), with an emphasis on developmental dysplasia of the hip.

MATERIALS AND METHODS

We performed a retrospective review of 65 hips in 57 patients who underwent cementless primary THA. The preoperative diagnosis was secondary osteoarthritis in all cases due to developmental dysplasia of the hip. All preoperative planning and postoperative evaluations were completed using CT-based three-dimensional templating software. We analyzed the accuracy of stem size prediction and cup size prediction, the reproducibility of preoperative and postoperative stem anteversion, and the absolute error in preoperative and postoperative stem anteversion using CT-based three-dimensional templating software.

RESULTS

The sizes of 65 % of the femoral stems (42/65) were estimated exactly, and 98 % (63/65) were accurately estimated to within one stem size. The final acetabular cup sizes corresponded exactly to the preoperatively planned size in 92 % of all cases (62/65). 100 % of the cup size estimates were accurate to within one cup size. There was strong reproducibility of preoperative and postoperative stem anteversion (r = 0.88, P < 0.05). The absolute error in stem anteversion was 4.0° ± 3.6°.

CONCLUSIONS

Using CT-based three-dimensional templating software made it possible to achieve reproducible stem anteversion and choose accurate stem and cup sizes in patients with developmental dysplasia of the hip.

Risk factors for the periprosthetic fracture after total hip arthroplasty: a systematic review and meta-analysis

BACKGROUND AND AIMS

A systematic review and meta-analysis was performed to investigate the risk factors associated with periprosthetic fracture after total hip arthroplasty.

MATERIAL AND METHODS

We searched potential studies in the following databases: MEDLINE, Embase, Web of Science, SCOPUS and Cochrane CENTRAL up to December 2013. Newcastle-Ottawa Scale was used to evaluate the methodological quality, and Stata 11.0 was used to perform all the analyses.

RESULTS

Seven studies altogether, including 1069 cases of periprosthetic fractures and 74,776 controls, were included in the meta-analysis. Compared to those absent following demographic or medical conditions, patients involved with female gender (odds ratio, 1.534; p < 0.001), advanced age (>80) (odds ratio: 4.203; p < 0.001), revision (odds ratio: 4.398; p < 0.001), rheumatoid arthritis (odds ratio: 2.503; p < 0.001), osteonecrosis (odds ratio: 1.563; p = 0.009), and implant type of Exeter (odds ratio: 1.511; p = 0.017) were more likely to sustain periprosthetic fractures. Osteoarthritis (vs not) (odds ratio: 0.449; p < 0.001) was identified a protective factor for periprosthetic fractures after total hip arthroplasty. The other factors, including lower ages, American Society of Anesthesiologists ≥ 3, and other implant types, were not significant risk factors for periprosthetic fractures.

CONCLUSIONS

These medical conditions as reminder should be kept in clinicians' mind and close follow-up should be implemented in patients involved for preventing the occurrence of periprosthetic fractures after total hip arthroplasty.