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

Does two dimensional templating allow for the use of reduced-size ancillaries in total hip arthroplasty?

PURPOSE

Rising costs in healthcare for total hip arthroplasty (THA) mean that new solutions must be considered, such as the use of single-use ancillaries (SUA). The goal of this study was to assess the accuracy of 2D templating in primary THA for the use of reduced-size SUA. Our hypothesis was that the accuracy of 2D templating in primary THA would be higher than 95%, give or take two sizes.

METHOD

This single-centre prospective study included all primary THAs performed over two years. Templating was carried out using 2D templating on anteroposterior pelvic X-rays. The template sizes were compared to the implant sizes. The primary endpoint was the rate of coincidence between digitally templated estimates and the actual implant sizes. The secondary endpoint was the difference of accuracy based on patient parameters.

RESULTS

We analysed 512 cases of THA. Accuracy within two sizes was 96.9% for acetabular implants and 98.5% for femoral implants. Accuracy was below the 95% threshold only in patients under 55 and over 85 years old. A BMI above 30.0 kg/m2 significantly reduced accuracy but did not fall below the 95% threshold. The operated hip, the type of implant, and the operative indication did not significantly influence templating accuracy.

CONCLUSION

Using reduced-size SUA with five rasps and five reamers depending on template sizes means that THA can be performed in more than 95% of cases allowing the use of compact single use ancillaries.

Accuracy of two-dimensional digital planning in uncemented primary hip arthroplasty: monocentric analysis of eight hundred implants

PURPOSE

In the last decades, there has been a refinement in total hip arthroplasty, which allowed surgeons to achieve the highest performance and better patient outcomes. Preoperative planning in primary hip arthroplasty is an essential step that guides the surgeon in restoring the anatomy and biomechanics of the joint. This study aims to evaluate the accuracy of the 2D digital planning, considering cup sizing, stem sizing, and limb length discrepancy. Additionally, we conducted a multivariable analysis of demographic data and comorbidities to find factors influencing preoperative planning.

METHODS

This retrospective study analyzed the planning accuracy in 800 consecutive uncemented primary total hip arthroplasty. We compared the preoperatively planned total hip arthroplasty with postoperative results regarding the planned component size, the implanted size, and the lower limb length restoration. Therefore, we investigated factors influencing planning accuracy: overweight and obesity, sex, age, past medical history, comorbidities, and implant design. All the surgeries were performed in the posterolateral approach by one expert surgeon who did the preoperative planning. The preoperative planning was determined to be (a) exact if the planned and the implanted components were the same size and (b) accurate if exact ± one size. The restoration of postoperative limb length discrepancy was classified into three groups: ± 3 mm, ± 5 mm, and ± 10 mm. This assessment was performed through a digital method 2D based on a standard hip X-ray.

RESULTS

This court of 800 implants showed that planning was exact in 60% of the cups and 44% of the stems and was accurate in 94% of the cups and 80% of the stems. The postoperative limb length discrepancy was ± 3 mm in 91% and ± 5 mm in 97%.

CONCLUSIONS

This study showed preoperative 2D digital planning great precision and reliability, and we demonstrated that it was accurate in 94% of the cups and 80% of the stems. Therefore, the preoperative limb length discrepancy analysis was essential to guarantee the recovery of the operated limb's correct length.

Surgeon's Experience and Accuracy of Preoperative Digital Templating in Primary Total Hip Arthroplasty

Purpose

Preoperative planning has become essential in performance of total hip arthroplasty (THA). However, data regarding the effect of the planner's experience on the accuracy of digital preoperative planning is limited. The objective of this study was to assess the accuracy of digital templating in THA based on the surgeon's experience.

Materials and Methods

A retrospective study was conducted. An analysis of 98 anteroposterior pelvic radiographs, which were individually templated by four surgeons (two hip surgeons and two orthopaedic residents) using TraumaCad® digital planning, was performed. A comparison of preoperatively planned sizes with implanted sizes was performed to evaluate the accuracy of predicting component size. The results of preoperative planning performed by hip surgeons and orthopaedic residents were compared for testing of the planner's experience.

Results

Femoral stem was precisely predicted in 32.4% of cases, acetabular component in 40.3%, and femoral offset in 76.7%. Prediction of cup size showed greater accuracy than femoral size among all observers. No differences in any variable were observed among the four groups (acetabular cup P=0.07, femoral stem P=0.82, femoral offset P=0.06). All measurements showed good reliability (intraclass correlation coefficient [ICC] acetabular cup: 0.76, ICC femoral stem: 0.79).

Conclusion

The results of this study might suggest that even though a surgeon's experience supports improved precision during the planning stage, it should not be restricted only to surgeons with a high level of experience. We consider preoperative planning an essential part of the surgery, which should be included in training for orthopaedics residents.

Comparison of three-versus two-dimensional pre-operative planning for total hip arthroplasty

Background

A successful clinical outcome for total hip arthroplasty (THA) depends on accurate sizing and positioning of the implants. Using three-dimensional (3-D) pre-operative planning with a computerized tomography (CT) scan has many potential advantages over conventional 2-D planning using radiographs, including potentially more accurate assessments of the size and anteversion of the acetabulum, as well as lateral femoral offset. The purpose of this study was to compare the accuracy of 3-D to 2-D templating with respect to acetabular and femoral size, as well as lateral femoral offset.

Methods

Pre-operative templating data was collected prospectively from a consecutive series of 290 primary THAs (acetabulum on all, femoral component on 255 of the cases using one specific stem). All cases were initially templated on a digital imaging picture archiving and communication (PACS) system with calibrated images to estimate the acetabular size, femoral size, and lateral femoral offset. The 3-D templating was then performed with software based on a CT scan, and the results were compared to what was surgically implanted.

Results

The 3-D templating for the acetabulum was accurate 99.7% of the time based on the final implanted component. The 2-D templating for the acetabulum was accurate 39% of the time, with 46% of cases templating smaller and 15% templating larger. The 3-D templating of the femoral component was accurate 63% of the time, and within one size of final implant in 96% of cases. The 2-D templating of the femoral component was accurate 53% of the time and within one size of final implant in 94% of cases. The 2-D templated femoral offset was accurate 87% of the time and was changed in 13% of cases after 3-D templating.

Conclusion

The CT-based 3-D preoperative planning was superior to 2-D planning for THA with respect to acetabular size, femoral size, and lateral femoral offset. Precise acetabular component sizing conserves bone and allows for a more predictable press fit, while facilitating efficient inventory management. Lateral femoral offset is often difficult to measure on 2-D images, and 3-D templating consistently allows for accurate offset restoration, which is important for normal hip function and stability.

Short-term outcome of artificial intelligence-assisted preoperative three-dimensional planning of total hip arthroplasty for developmental dysplasia of the hip compared to traditional surgery

OBJECTIVES

This study aims to assess the short-term outcome of total hip arthroplasty for treating developmental dysplasia of the hip (DDH) using artificial intelligence (AI)-assisted three-dimensional (3D) preoperative planning technology.

PATIENTS AND METHODS

Between January 2020 and July 2022, a total of 61 patients with DDH (31 males, 30 females, mean age: 59.2±10.4 years; range, 35 to 78 years) were retrospectively analyzed. The patients were divided into two groups as those in the observation group of AI-assisted 3D preoperative planning technology (n=34) and the control group of traditional two-dimensional X-ray template planning technology (n=27). Perioperative data of the patients were recorded and analyzed.

RESULTS

All patients were followed for more than one year, and no hip dislocation, aseptic loosening, periprosthetic fracture, periprosthetic infection or revision occurred. The accuracy of the planning was based on the agreement between the preoperative planning model and the intraoperative model. The accuracy of preoperative planning for the acetabular prosthesis and femoral prosthesis in the observation group was significantly higher than in the control group. No statistically significant difference was found in the postoperative abduction (p=0.416) and anteversion (p=0.225) between the groups. In the observation group, 91.2% of the acetabular cups were implanted within the Lewinnek safe zone (66.7% in the control group) and 88.2% were within the Callanan safe zone (63% in the control group). There was a statistically significant difference between the two groups in terms of the postoperative lower-limb length discrepancy (p=0.004), which was significantly improved in both groups compared to preoperative values (p<0.01 for all). The postoperative Harris hip score in both groups was significantly improved compared to preoperative scores (p<0.01); however, there was no statistically significant difference between the two groups (p=0.098).

CONCLUSION

Our study results suggest that AI-assisted 3D preoperative planning is evidently more successful than traditional 2D X-ray template planning for predicting prosthesis size. This method seems to be advantageous in acetabular cup positioning, as well as in lower-limb length restoration.

Accuracy analysis of artificial intelligence-assisted three-dimensional preoperative planning in total hip replacement

OBJECTIVES

This study aims to assess the outcome of total hip arthroplasty (THA) using artificial intelligence (AI)-assisted three-dimensional (3D) preoperative planning technology in terms of predicting prosthesis size, acetabular cup positioning, and lowerlimb length restoration.

PATIENTS AND METHODS

Between January 2020 and July 2022, a total of 161 patients (101 males, 60 females; mean age: 57.6±10.5 years; range, 31 to 80 years) who underwent primary unilateral THA were retrospectively analyzed. The patients were divided into two groups as those who were treated with AI-assisted 3D preoperative planning technology (the observation group, n=95) and patients who were treated with traditional two-dimensional (2D) X-ray template planning technology (the control group, n=66).

RESULTS

The accuracy of the planning was based on the consistency of the preoperative planning and intraoperative models. The difference between the observation group and the control group was statistically significant in terms of the accuracy of the preoperative planning of acetabular prostheses (54% vs. 38%, p=0.048) and femoral prostheses (64% vs. 44%, p=0.011), with both values significantly higher in the observation group. The mean inclination angle, anteversion angle, and limb length discrepancy (LLD) in the observation group were 36.85°±4.82°, 12.10°±5.33°, and 2.18±2.70 mm, respectively, while those in the control group were 35.06°±6.07°, 10.95°±5.09°, and 4.42±3.85 mm, respectively. There was a statistically significant difference between the two groups in terms of inclination angle and LLD (p<0.05 for both), but there was no significant difference in terms of anteversion angle (p>0.05). In the observation group, 86.3% (82/95) of acetabular cups were implanted within the Lewinnek safe zone (72.7% [48/66] in the control group), while 83.2% (79/95) were within the Callanan safe zone (69.7% [46/66] in the control group), with both values higher in the observation group (p<0.05).

CONCLUSION

Overall, AI-assisted 3D preoperative planning is superior to traditional 2D X-ray template planning for predicting prosthesis size, and it also has the advantage in terms of acetabular cup positioning and lower-limb length restoration.

A Study Investigating Whether BMI Is Associated With Acetabular Bone Size: Big Bones or a Big Myth?

Background

There is a common conception held by patients with a high body mass index (BMI) that they have “big bones”. Some people hold the assumption that their weight is attributed to larger bone stock rather than adipose tissue. It was the suspicion of the surgeons at our unit that this is often not the case. We therefore conducted a study investigating if there is any association between BMI and acetabular bone size.

Methods

We conducted a retrospective chart review of all patients undergoing total hip arthroplasty using the Trident acetabular system from Stryker at our tertiary level 1 trauma centre between September 2016 and August 2020. Patient demographic and surgical data were collected, and the association of BMI, height, and weight, with acetabular cup size was investigated using Pearson’s correlation coefficient and chi-square test for independence.

Results

A total of 418 patients were included in this study (52.4% female; age: 20-93 years; mean age: 62.51 years), with a mean BMI of 29.55 kg/m²(range: 14.95-52.32 kg/m²). A weak positive association between BMI and cup size, which was statistically significant (r = 0.107; n = 418; p = 0.02). The chi-square test for independence was used to study the association between obesity and cup size (large vs small), which demonstrated no significant difference (p = 0.08). There was a moderately strong positive association between height and cup size (r = 0.551; n = 418; p < 0.01). There was a weak positive association between weight and cup size, which was statistically significant (r = 0.355; n = 418; p < 0.01).

Conclusion

Our study suggests that there is indeed a weakly positive linear association between BMI and cup size among total hip arthroplasty patients. This effect was, however, more significant for height and weight, and there was no significant association between obese and non-obese groups with small versus large cup size implanted. We therefore conclude that clinically there is no significant relationship between obesity and acetabular bone size and that the “big bones” claim is indeed fallacious.

The accuracy and reliability of preoperative digital 2D templating in prosthesis size prediction in uncemented versus cemented total hip arthroplasty: a systematic review and meta-analysis

The purpose of this study was to compare the accuracy and the inter- and intra-observer reliability of preoperative digital 2D templating in prosthesis size prediction for the planning of cemented or uncemented THA.

This study was registered in the NIHR PROSPERO database (ID: CRD42020216649) and conducted according to the PRISMA guidelines. A search of electronic databases in March 2021 found 29 papers overall. The quality of evidence was assessed using the IHE Quality Appraisal of Case Series Studies Checklist and the CASP Randomised Controlled Trials Checklist. A meta-analysis was conducted, and the accuracy was presented as proportions and the inter- and intra-observer reliability were measured using intraclass correlation coefficients (ICC).

Accuracy within one prosthesis size (±1) for cemented stems was 0.89 (95% confidence interval (CI) 0.83–0.95), cemented cups 0.78 (95% CI 0.67–0.89), uncemented stems 0.74 (95% CI 0.66–0.82) and uncemented cups 0.73 (95% CI 0.67–0.79) (test of group differences: p = 0.010). Inter-observer reliability (ICC) for uncemented cups was 0.88 (95% CI 0.85–0.91), uncemented stems 0.86 (95% CI 0.81–0.91), cemented stems 0.69 (95% CI 0.54–0.84) and cemented cups 0.68 (95% CI 0.55–0.81) (test of group differences: p = 0.004). Due to lack of data, intra-observer reliability (ICC) could only be calculated for uncemented prostheses, which for the stems was 0.90 (95% CI 0.88–0.92) and for the cups was 0.87 (95% CI 0.83–0.90) (test of group differences: p = 0.124).

The accuracy of preoperative digital templating is greater for cemented prostheses, but the inter-observer reliability is greater for uncemented prostheses. The intra-observer reliability showed a high level of agreement for uncemented prostheses.

Cite this article: EFORT Open Rev 2021;6:1020-1039. DOI: 10.1302/2058-5241.6.210048