Can the use of a free mobile phone inclinometer application improve the accuracy of coronal cup position during total hip arthroplasty?

Bibek Banskota; Rajendra Aryal; Ansul Rajbhandari; Deependra Yadav; Ashok K. Banskota

doi:10.1016/j.jorep.2024.100372

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Review Article

2025

:4;

100372

doi:

10.1016/j.jorep.2024.100372

Can the use of a free mobile phone inclinometer application improve the accuracy of coronal cup position during total hip arthroplasty?

Bibek Banskota, Rajendra Aryal, Ansul Rajbhandari, Deependra Yadav, Ashok K. Banskota

Unit 1 Orthopedics, B&B Hospital, Nepal

⁎Corresponding author: Bibek Banskota. bibekbanskota@gmail.com

Received: 2024-3-15, Accepted: 2024-5-13, Published: 2024-5-15

The Authors

Disclaimer:
This article was originally published by Reed Elsevier India Pvt. Ltd. and was migrated to Scientific Scholar after the change of Publisher.

Abstract

Accurate acetabular cup positioning during THA has essential implications for function and long-term prosthesis survival. Low-volume hip arthroplasty surgeon is known to be a risk factor for malpositioning of the acetabular cup. Also, even in a low-volume setting, the surgeon may be required to perform hip arthroplasty for complex primary or revision cases. Thus, any adjunct that has the potential to improve accuracy during surgery should be encouraged to avoid cup malposition and its long-term problems.

A year-long (Jan-2021 to Jan-2022) descriptive cross-sectional study was carried out on all patients receiving primary total hip arthroplasty (THA) at B&B hospital.

There were 36 patients (36 hips) with an average age of 48.53 years (SD 48.53 ± 15.02). There were 21 (58.33 %) males and 15 (41.67 %) females, and the right and left hips were involved in 18 patients each. All acetabular cups were uncemented. The inferential analysis indicated no statistically significant difference in the measurements obtained through the two methods, as reflected by a p-value of 0.99 at a 95 % confidence interval.

The present study compared the values of acetabular inclination measured during surgery using a mobile phone inclinometer application with post-operative values calculated using a standard anteroposterior radiograph of the pelvis to ascertain if the inclinometer app is reliable in predicting the final acetabular inclination. We believe this will provide the surgeon with a safeguard during surgery to achieve the desired acetabular cup inclination.

Keywords

Total hip arthroplasty

Acetabular inclination

Inclinometer

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1 Introduction

Accurate placement of acetabular component in total hip arthroplasty (THA) is determined by acetabular version and inclination.¹ There is a correlation between dislocation, edge loading, increased failure rates, and abnormal radiographic inclination.² It's still difficult to get a good radiographic inclination. Several tools have been employed to help determine intra-operative component cup placement, including mechanical alignment guides, digital and mechanical protractors, computational and robot-assisted navigation systems, and inclinometers.^3–5 An inclinometer is a more precise tool than mechanical alignment guides for measuring the inclination of the acetabular component during surgery (MAGs), and it is simpler and more cost-effective than navigation.⁶^,⁷ Literature shows that low-volume hip arthroplasty surgeon is a risk factor for mispositioned acetabular cups.⁸ The present study compares the intra-operative coronal cup position using an inclinometer with post-operative radiographic measurements.

2 Materials and methods

A descriptive cross-sectional study of all patients undergoing a primary total hip arthroplasty (THA) at B&B hospital over one year (Jan 2021 to Jan 2022) was conducted. Ethical clearance was taken from B&B/HRDC institutional IRC.36 patients who underwent primary total hip arthroplasty (THA) in the study period were included.

The aim was to evaluate the accuracy of an inclinometer application to improve coronal cup position in THA. Intra-operatively, during and after final cup impaction, the acetabular index (AI) was measured using the inclinometer application ("CLINOMETER" mobile phone free app). The inclinometer measurement after the final cup impaction was recorded and compared against the post-operative radiographic measurement of the AI. The mean AI difference between intra-op inclinometer measurement versus post-op radiographic measurement was recorded.

2.1

2.1 Procedural details

The same team led by the first author performed a standard primary THA using the posterior approach on all of the study's patients. On the table, coronal cup inclination measurement by inclinometer app was recorded before and after impaction, and reading after impaction was recorded. A goniometer in standard anteroposterior radiographs of the pelvis measured post-operative acetabular cup inclination. The mobile device was wrapped with a sterile cling drape to maintain sterility using all aseptic techniques. The inclinometer was held perpendicular to the cup impactor, and the final reading was recorded (Fig. 1).

Intra-operative measurement of acetabular inclination using a free mobile phone inclinometer app.

The assistant handling the mobile device wore a sterile glove, which was changed immediately after the device was used. Post-operative measurement was taken on a standard anteroposterior radiograph of the pelvis. The angle between the two lines, the ischial line and the line drawn from the two lips of the acetabulum, was measured with a goniometer and recorded (Fig. 2). The inclinometer and post-operative readings were compared statistically. The mean ± standard deviation (SD) was used to report continuous data, while the number represented categorical data (percentage). Independent Student t-test (two-tailed) was used to analyze the mean difference, and the significance level was set at 0.05 (α).

Post-operative measurement of acetabular inclination in standard anteroposterior pelvis radiograph. The angle between inter ischial line and the line drawn from the two lips of acetabular cup, was measured with a goniometer.

3 Results

Statistical analysis was done using the Independent Student's t-test as a two-tailed analysis to examine mean variations. A 95 percent confidence interval (CI) was established as the significance level to evaluate the statistical significance. Statistical analysis showed that the mean acetabular inclination measured with the inclinometer was 39.63 ± 2.78) degrees, and the mean acetabular inclination measured in plain antero-posterior radiographs of the pelvis was 41.53 ± 3.27) degrees. There was no statistically significant difference between the measurements obtained by these two methods at (p = 0.99 at 95 percent CI). The results suggest that intra-operative inclinometer measurements of cup inclination are not statistically significantly different from post-operative radiographic measurements. Thus, using an inclinometer for accurate coronal acetabular cup positioning provides a reliable safeguard for the surgeon (Table 1).

Table 1 Mean and standard deviation of an acetabular cup using an inclinometer versus a radiograph.

Parameter	Using inclinometer, Mean ± SD	Using plain radiograph, Mean ± SD	P value*
Acetabular inclination, in degrees	39.63 ± 2.78	41.53 ± 3.27	0.99

4 Discussion

Total hip arthroplasty (THA) is a common surgical procedure for treating advanced primary or secondary osteoarthritis of the hip joint. Accurate placement of the acetabular cup is a crucial component that influences the success of total hip arthroplasty (THA) and can have a significant effect on the implant's long-term survival. Improper placement of the acetabular cup can lead to increased wear, instability, and dislocation, resulting in revision surgery, increased costs, and reduced quality of life for the patient. Recent studies have shown that using inclinometers can improve the accuracy of acetabular cup placement in THA, which may ultimately lead to improved patient outcomes.

In their seminal paper investigating risk factors for cup malposition, Callanan et al.⁸ reported low surgeon volume, minimally invasive approaches, and a body mass index of >30 independently predicted malpositioned cups. Of 1823 THAs investigated in this study, 63 % were within the abduction range, 79 % within the version range, and only 50 % were within the range for both. Thus, a strong argument can be made to encourage using any adjunct that can help improve the accuracy of cup position, especially for low-volume centers such as ours.

Lewinnek et al.⁹ described a "safe zone" for cup placement as having an inclination of 40±10° and an anteversion of 15 ±10°. While it is well known that cups placed within the safe zone can dislocate, it can still be used as a rough guide to prevent wide variations in cup positioning.

Several studies have investigated using inclinometers to improve cup position in THA. In a study by Yohei Naito et al.¹⁰ groups of 20 patients underwent THA using an inclinometer to guide cup placement. In contrast, a control group of 20 patients underwent THA without the use of an inclinometer. The researchers found that using the inclinometer resulted in significantly improved cup placement compared to the control group, with a mean cup inclination angle of 41.7° in the inclinometer group versus 48.6° in the control group (p < 0.001). Similarly, a study by Parratte et al.¹¹ found that using an inclinometer improved cup placement accuracy, with a mean cup inclination angle of 43.3° in the inclinometer group versus 47.7° in the control group (p < 0.001).

Other studies have also shown the benefits of inclinometer-guided cup placement in THA. In a randomized controlled trial by Liu et al.,¹² 59 patients underwent THA using an inclinometer. In comparison, a control group of 59 patients underwent THA without the use of an inclinometer. The researchers found that using the inclinometer resulted in significantly improved cup placement accuracy, with a mean cup inclination angle of 43.6° in the inclinometer group versus 48.2° in the control group (p < 0.01). Similarly, a study by Cheng et al.¹³ found that using an inclinometer resulted in improved cup placement accuracy and reduced dislocation and revision surgery rates.

In addition to improving cup placement accuracy, inclinometers may improve patient outcomes and lower the risk of complications in total hip arthroplasty (THA). A study by Xin et al.¹⁴ found that using an inclinometer reduced rates of early dislocation and revision surgery, with a revision rate of 0 % in the inclinometer group versus 5.5 % in the control group (p = 0.04). Similarly, a study by Arthur J Kievit et al.¹⁵ found that using an inclinometer reduced revision surgery rates and improved patient-reported outcomes. Table 2 compares results with similar studies in the literature where an inclinometer or similar device was used to measure the acetabular inclination.

Table 2 Comparison of devices and results with other studies in the literature.

Study	Sample size, N	Measurement Device	AI using inclinometer, Mean ± SD (in degrees)	AI using plain radiograph, Mean ± SD (in degrees)
Present study	36	Digital inclinometer smartphone app (designed by plain code app development, Sternstr. 5, 83,071 Stephanskirchen, Germany)	39.63 ± 2.78	41.53 ± 3.27
Darrith et al ⁵ , 2018	167	AccuAngle Inclinometer (Innomed, Savannah, Georgia)	42.9 ± 7.0	46.5 ± 6.3
Meermans et al ¹⁷ , 2015	100	Digital inclinometer (WR 300 Digital Angle Gauge, Barry Wixey Development, Seattle, Washington)	38.3 ± 4.7	38.5 ± 7.0
O'Niell et al ⁴ , 2018	270	Digital inclinometer (Digi-Pas DWL-80E, DigiPas USA, CT, USA)	34.0 ± 1.6	32.9 ± 2.9
Vendittoli et al ¹⁸ , 2002	50	Steriliseable stainless steel Inclinometer (designed by P-AV, manufactured only for study purpose by Medical Design Inc., Ste-Foy, Canada)	42.2 ± 3.8	44.4 ± 11.4

Contrary to the literature above, certain studies¹⁶ have shown that using an inclinometer did not significantly improve cup placement accuracy, patient outcomes, and dislocation rates (Table 2).

5 Conclusion

Using inclinometers to improve cup position in THA has shown promising results in several studies. Improved cup placement accuracy, reduced dislocation and revision surgery rates, and improved patient-reported outcomes are among the potential benefits of this technique. However, conflicting results in some studies suggest further research to identify the optimal methods and protocols for using inclinometers in THA. The application of inclinometers in THA may be a significant advancement in enhancing the precision and durability of THA implants, which may ultimately result in better patient outcomes and lower medical expenses. To guarantee the best results for their patients, surgeons must remain current on the newest developments in THA techniques and technologies. In our scenario, using an inclinometer may have a particular implication as an aid to the low-volume hip arthroplasty surgeon faced with complex primary or revision cases, with the added benefit of being free of cost.

Ethical approval and consent to participate

The research received ethical approval from the Institutional Review Committee at B&B (B&BIRC-23-57), and informed consent was obtained from each participant.

Consent for publication

Consent for the publication was taken from the patients.

Availability of supporting data

Data is available at the reasonable request.

Funding

No.

Authors' contributions

BB & AKB: Conceived and designed the study, collected andanalyzed data, and drafted the manuscript. BB,RA andAR Contributed to the study design, conducted experiments, andassisted in data analysis. Also critically reviewed and revised the manuscript. DY:Assisted in data collection andanalysis, contributed to the interpretation of results, and participated in manuscript writing and revision. ALL Authors:Contributed to the literature review, data interpretation, and manuscript preparation. Also provided critical feedback during the revision process.

Guardian/patient's consent

We individually obtain written consent from all patients before participating in research. Upon request, we can provide you with copies of the original consent forms which is in Nepali Languages.

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