A higher reliability with a computed tomography scan-based three dimensional technique than with a two dimensional measurement for lower limb discrepancy in total hip arthroplasty planning

A large preoperative pelvic oblique angle affects perception of leg length discrepancy after total hip arthroplasty

BACKGROUND

In some cases, patients feel a perceived leg length discrepancy (P-LLD) despite no radiographic leg length discrepancy (R-LLD) after total hip arthroplasty (THA). We aimed to investigate the rate of postoperative P-LLD and the factors that cause postoperative P-LLD.

METHODS

A retrospective study was conducted on 100 patients with R-LLD ≤5 mm after THA. Patients were classified into two groups based on P-LLD post-THA: group P (with P-LLD) and group E (without P-LLD). Relevant data on the general characteristics and radiological findings between the two groups were compared.

RESULTS

We observed that 25 & 75% of patients belonged to group P and group E, respectively, with no significant difference in patient background. Postoperative Japanese Orthopedic Association (JOA) classification of pain and activities of daily living scores were significantly lower in group P than in group E (37.2 ± 3.9 vs. 39.1 ± 2.2, respectively; P = 0.013, and 16.2 ± 4.2 vs. 18.2 ± 2.2, respectively; P = 0.011). The preoperative pelvic oblique angle (POA) was significantly larger in group P than in group E (3.3 ± 2.3° vs. -0.2 ± 2.1°; respectively; P < 0.01). The pelvis tilted toward the surgical side was significantly higher in group P than in group E(88% vs 57%; respectively; P = 0.013). The preoperative C7 coronal vertical axis (C7 CVA) was significantly larger in group P than in group E (6.7 ± 14.7 mm vs. -0.2 ± 10.3 mm; respectively; P = 0.028). Multivariate logistic analysis revealed that preoperative POA (OR, 3.71; 95% CI: 1.86-8.12; P < 0.01) and the pelvis tilted toward the surgical side (OR, 4.14; 95% CI: 2.07-9.71; P = 0.022) were independent risk factors for P-LLD after THA.

CONCLUSION

Even though there was no postoperative R-LLD, 25% of patients had P-LLD. A large preoperative POA and the pelvis tilted toward the surgical side were independent risk factors for P-LLD after THA.

The Value of Computed Tomography Scan in Three-dimensional Planning and Intraoperative Navigation in Primary Total Hip Arthroplasty

Total hip arthroplasty (THA) is a frequently performed procedure; the objective is restoration of native hip biomechanics and achieving functional range of motion (ROM) through precise positioning of the prosthetic components. Advanced three-dimensional (3D) imaging and computed tomography (CT)-based navigation are valuable tools in both the preoperative planning and intraoperative execution. The aim of this study is to provide a thorough overview on the applications of CT scans in both the preoperative and intraoperative settings of primary THA. Preoperative planning using CT-based 3D imaging enables greater accuracy in prediction of implant sizes, leading to enhancement of surgical workflow with optimization of implant inventory. Surgeons can perform a more thorough assessment of posterior and anterior acetabular wall coverage, acetabular osteophytes, anatomical landmarks, and thus achieve more functional implant positioning. Intraoperative CT-based navigation can facilitate precise execution of the preoperative plan, to attain optimal positioning of the prosthetic components to avoid impingement. Medial reaming can be minimized preserving native bone stock, which can enable restoration of femoral, acetabular, and combined offsets. In addition, it is associated with greater accuracy in leg length adjustment, a critical factor in patients' postoperative satisfaction. Despite the higher costs and radiation exposure, which currently limits its widespread adoption, it offers many benefits, and the increasing interest in robotic surgery has facilitated its integration into routine practice. Conducting additional research on ultra-low-dose CT scans and examining the potential for translation of 3D imaging into improved clinical outcomes will be necessary to warrant its expanded application.

CT validation of intraoperative imageless navigation (Naviswiss) for component positioning accuracy in primary total hip arthroplasty in supine patient position: a prospective observational cohort study in a single-surgeon practice

BACKGROUND

The aim of this study was to report on the validity of the Naviswiss handheld image-free navigation device for accurate intraoperative measurement of THA component positioning, in comparison with the three-dimensional (3D) reconstruction of computed tomography (CT) images as the gold standard.

METHODS

A series of patients presenting to a single-surgeon clinic with end-stage hip osteoarthritis received primary hip arthroplasty with the anterolateral muscle-sparing surgical approach in the supine position. Imageless navigation was applied during the procedure with bone-mounted trackers applied to the greater trochanter and ASIS. Patients underwent routine CT scans before and after surgery and these were analyzed by using three-dimensional reconstruction to generate cup orientation, offset and leg length changes, which were compared to the intraoperative measurements provided by the navigation system. Estimates of agreement between the intraoperative and image-derived measurements were assessed with and without correction for bias and declared cases with potential measurement issues.

RESULTS

The mean difference between intraoperative and postoperative CT measurements was within 2° for angular measurements and 2 mm for leg length. Absolute differences for the two indices were between 5° and 4 mm. Mean bias was 1.9°-3.6° underestimation for cup orientation and up to 2 mm overestimation for leg length change, but absolute thresholds of 10° and 10 mm were not exceeded by 95% limits of agreement (LOA), especially after correction for bias. Four cases (12%) were declared intraoperatively for issues with fixation on the greater trochanter. Inclusion of these cases generated acceptable accuracy overall and their omission failed to improve between-case variability in accuracy or LOA for both offset and leg length.

CONCLUSIONS

The accuracy of the Naviswiss system applied during primary THA in a supine position and anterolateral surgical approach falls within clinically acceptable recommendations for acetabular cup placement, femoral offset, and length. With refinements to surgical technique to adapt to the navigation hardware, the system could be further improved with regression-based bias correction.

TRIAL REGISTRATION

Registered with the Australian New Zealand Clinical Trials Registry (ACTRN12618000317291).

Feasibility and anteversion accuracy of a patient-specific instrument for femoral prosthesis implantation in total hip arthroplasty

BACKGROUND

The aim of this study was to evaluate the precision and feasibility of patient-specific instruments (PSI) in total hip arthroplasty (THA) as compared to the traditional free-hand (FRH) approach.

METHODS

During the period of January 1, 2021 to December 31, 2022, a randomized allocation was used for patients receiving unilateral primary THA to either the PSI or conventional operation group. The placement and size of the PSI were specifically chosen to guide femoral neck resection and prosthesis implantation. The study analyzed component positions and evaluated radiographic and clinical outcomes in 30 patients who received PSI-assisted THAs and 30 patients who received FRH THAs. This study was registered at China Clinical Trial Registry (number: ChiCTR2300072325) on June 9th, 2023.

RESULTS

The use of PSI in THA resulted in significantly higher precision in achieving the desired component position as compared to the FRH approach. The PSI group showed significantly smaller absolute errors of femoral anteversion (p < 0.001). No significant differences were found in operation time, intra-operative blood loss, hospitalization duration, or time to walk after surgery.

CONCLUSION

In conclusion, the application of patient-specific instruments in THA provides a simple and reliable solution to enhance the precision of femoral prosthesis placement with high accuracy and feasibility. This study highlights the potential benefits of using the PSI in THA.

Measurement Techniques for Leg Length Discrepancy in Total Hip Arthroplasty: A Systematic Review of Reliability and Validity

BACKGROUND

Total hip arthroplasty (THA) carries a substantial litigative burden. THA may introduce leg length discrepancy (LLD), necessitating a valid and reliable technique for LLD measurement. This study investigates the reliability and validity of techniques quantitively measuring LLD in both pre- and post-THA.

METHODS

Embase and MEDLINE databases were searched following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for articles assessing either the validity or reliability of LLD measurement techniques. Data was pooled using random effects meta-analysis to derive reliability estimates. Study quality was assessed using the Brink and Louw checklist.

RESULTS

Forty-two articles with 2059 participants were included. Thirty-three investigated reliability and 25 validity. Reliability displayed high heterogeneity. Poor to excellent intra-rater reliability was reported for antero-posterior pelvis radiographs, moderate to excellent for computed tomography scanograms, and good to excellent for clinical methods and teleradiography, and excellent for bi-planar radiography (BPR). Poor to excellent inter-rater reliability was reported for antero-posterior pelvis radiographs and clinical methods, moderate to excellent for teleradiography, good to excellent for computed tomography scanogram and excellent for BPR. The tape measure method is a valid clinical measure of LLD whilst markerless motion analysis and the block method are not. Imaging techniques are appropriately cross-validated with the exception of BPR.

CONCLUSION

The reported intra- and inter-rater reliability for most measurement techniques vary widely. The tape measure method is a valid clinical measurement of LLD. Imaging techniques have been appropriately cross-validated, with the exception of BPR, although they lack validation against a common reference technique.