Pre-operative digital templating in cemented hip hemiarthroplasty for neck of femur fractures

Risk factors for templating mismatch of uncemented stems in bipolar hemiarthroplasty for femoral neck fracture

Preoperative templating needs to be precise to optimize hip arthroplasty outcomes. Unexpected implant mismatches can occur despite meticulous planning. We investigated the risk factors for oversized and undersized stem mismatch during uncemented hemiarthroplasty using a double-tapered wedge rectangular stem for femoral neck fracture. Out of 154 consecutive patients who underwent hemiarthroplasty for femoral neck fracture, 104 patients were divided into three groups: (1) oversized (n = 17; 16.3%), (2) matched (n = 80; 76.9%), and (3) undersized stem group (n = 7; 6.7%). A smaller femoral head offset (odds ratio [OR] = 0.89, 95% confidence interval [95% CI] = 0.81-0.98, P = 0.017), smaller isthmus diameter (OR = 0.57, 95% CI = 0.35-0.92, P = 0.021), and smaller canal flare index (OR = 0.20, 95% CI = 0.04-0.98, P = 0.047) were significantly associated with oversized stem insertion, while older age (OR = 1.18, 95% CI = 1.01-1.39, P = 0.037) was associated with undersized stem insertion in logistic regression. In conclusion, when performing hemiarthroplasty for a femoral neck fracture with a double-tapered wedge rectangular stem, surgeons must pay close attention to proximal femoral geometry and patient age during preoperative planning to avoid stem mismatch.

Preoperative templating in orthopaedic fracture surgery: The past, present and future

Preoperative planning in orthopaedic fracture surgery corroborates with the goal of establishing the best possible surgical result and ensuring a functioning limb for the patient. From placing sketches on overhead projector paper and measuring lengths from anatomical landmarks, ways of preoperative planning have evolved rapidly over the last 100 years. Today, preoperative planning includes methods such as advanced 3-Dimensional (3D) printed models and software programs incorporating entire libraries of osteosynthesis materials that can be shaped and rotated to fit a patient's specific anatomy. Relevant literature was evaluated to review the development of preoperative templating from the past and present, in order to assess its impact on the future of osteosynthesis.We identified studies on 3D-imaging, computer-assisted systems, and 3D-printed fractured bones and drill guides. The use of some of these systems resulted in a reduction in operation time, blood loss, perioperative fluoroscopy and hospital stay, as well as better placement of osteosynthesis material. Only few studies have identified differences in patient morbidity and mortality. Future techniques of preoperative templating are on the rise and the potential is vast. The cost-effectiveness and usefulness of certain methods need to be evaluated further, but the benefit of preoperative templating has the potential of being revolutionary, with the possibility of radical advances within orthopaedic surgery.

A novel method of manual positioning based on anatomical mark (shoulder-to-shoulder) to prevent postoperative leg-length discrepancy for femoral neck fractures in hip arthroplasty

OBJECTIVE

To determine whether the two lower extremities are of equal length after hip arthroplasty for femoral neck fractures, we developed a novel method of manual positioning based on anatomical mark (shoulder-to-shoulder) in hip arthroplasty.

METHODS

Patients with femoral neck fractures requiring hip arthroplasty from July 2020 to March 2022 in the orthopedic department of Jinjiang Municipal Hospital, Fujian Province, China were recruited. Hip arthroplasty was performed using the proposed "shoulder-to-shoulder" method of manual positioning based on anatomical mark in 52 patients with femoral neck fractures who met the inclusion criteria. "Shoulder-to-shoulder" was achieved by alignment of the marked femoral "shoulder" and the "shoulder" of prosthesis stem. There were 16 male and 36 female patients, with 27 undergoing total hip arthroplasty (THA) and 25 undergoing hip hemiarthroplasty (HA). The fractures were categorized according to the Garden classification: type II, type III, and type IV in 5, 11, and 36 patients, respectively. The vertical distance from the apex of the medial margin of the femoral trochanter to the tear drop line on both sides which was regarded as the length of both limbs were compared via postoperative imaging, and the apex-shoulder distance on the ipsilateral side measured via postoperative imaging was compared with those measured intraoperatively.

RESULTS

All patients completed the surgery successfully. The measurement results for the lower extremities after THA were as follows: contralateral group, 43.87 ± 5.59 mm; ipsilateral group, 44.64 ± 5.43 mm. The measurement results for the lower extremities after HA were as follows: contralateral group, 45.18 ± 7.82 mm; ipsilateral group, 45.16 ± 6.43 mm. The measurement results for the lower extremities after all arthroplasties were as follows: contralateral group, 44.50 ± 6.72 mm; ipsilateral group, 44.89 ± 5.90 mm. The results for the apex-shoulder distance were as follows: postoperative imaging, 19.44 ± 3.54 mm; intraoperative apex-shoulder distance, 27.28 ± 2.84 mm. Statistical analysis results indicated no statistically significant difference in the postoperative bilateral lower extremity length after hip arthroplasty (P = 0.75), while a statistically significant difference was found between the intraoperative and postoperative imaging measurements of the apex-shoulder distance (P < 0.01).

CONCLUSION

The novel method of manual positioning based on anatomical mark (shoulder-to-shoulder) for femoral neck fractures in hip arthroplasty is simple and accurate, making it effective for preventing postoperative bilateral leg length discrepancy.

Digital templating in hip hemiarthroplasty: Is it possible to accurately predict femoral head size from magnification alone?

BACKGROUND

Templating is an integral part of pre-operative planning in elective hip arthroplasty to achieve favourable long-term outcomes, but its applications in trauma surgery remain limited. When templating from radiographs without a calibration marker, there is always an element of magnification which must be accounted for. Our aim was to establish our institute-specific magnification and to determine whether using this to predict femoral head size in hemiarthroplasty was more accurate than using set magnifications previously reported in the literature.

MATERIALS & METHODS

Fifty consecutive patients who underwent hip hemiarthroplasty were retrospectively identified, their pre-operative radiographs reviewed and femoral head measured with templating software. Intra- and inter-observer reliability analyses were performed. Using this value, and two set values of 15% and 21% magnification, we attempted to predict femoral head sizes of our original cohort. The results were compared using paired t-test to ascertain if there was any significant difference in accuracy.

RESULTS

We established our institute-specific magnification as 17%. Inter- and intra-observer reliability were excellent. However, using this magnification we were only able to correctly predict to within ± one femoral head size in 49% of patients. There was no significant difference in accuracy comparing our institute-specific magnification with other magnifications from the literature.

CONCLUSION

We would not recommend using magnification factor in digital templating software as this could potentially lead to errors in predicting final femoral head size in hip hemiarthroplasty and adversely affect patient outcomes.

Pre-operative templating for total hip arthroplasty: How does radiographic technique and calibration marker placement affect image magnification?

INTRODUCTION

Pre-operative templating using digital radiography is an effective method of planning for total hip arthroplasty (THA) and requires a generalised fixed magnification factor (MF) or external calibration markers (ECM). The effect on image magnification when changing source-to-image distance (SID), object-to-image distance (OID) and different imaging conditions is not well described. This study aims to quantify the range of effects manipulation of radiographic parameters can have on image magnification across different body habitus and imaging conditions.

METHODS

A simple phantom study was performed. A 25 mm ECM was placed at eight different OID values along the anterior-posterior phantom plane at three different SID values and imaging conditions, and X-rays were obtained. On each radiograph, the ECM was measured using a line calliper tool by three radiographers and recorded. The MF was calculated and recorded.

RESULTS

The smallest observed image MF was 1.16, for an 8 cm OID, 120 cm SID with the ECM placed within the central ray and the X-ray detector in bucky underneath the X-ray table. The largest image MF was 1.40 for a 15 cm OID, 100 cm SID with the X-ray detector placed underneath an emergency department imaging trolley.

CONCLUSIONS

Digital pre-operative templating for THA relies on accurate radiographic positioning and is dependent of the patient body habitus, radiographic parameters and imaging conditions selected by the radiographer. The use of appropriately positioned ECMs - placed medially between the patient's internally rotated legs at the level of the greater trochanter, lowers the potential for magnification inaccuracies.

Conventional computed tomography software can be used for accurate pre-operative templating in bipolar hip arthroplasty: A preliminary report

BACKGROUND

The aim of this study was to investigate the use of pre-operative templating for bipolar hip arthroplasty (BHA) for displaced femoral neck fracture using multiplanar reconstruction (MPR) of computed tomography (CT) images.

METHODS

Nineteen patients who underwent BHA were enrolled in this study. For pre- and post-operative evaluation, a CT scan was performed from the pelvis to the knee joints. MPR of the CT image was done using software to measure the femoral head cup diameter, offset, stem size, length of the modular neck, distance from the neck osteotomy, and femoral anteversion. We compared these parameters pre- and post-operatively.

RESULTS

Both the femoral head cup diameter and length of the modular neck were found to be significantly different between pre- and post-operative measurements, although the differences were minor. Other parameters, including the femoral offset, were not significantly different between the pre- and post-operative measurements. The size of the femoral stem, cup diameter, and length of the modular neck were consistent with the planned size and accurate (within ±1 size) in more than 84% cases.

CONCLUSION

Our pre-operative templating approach for BHA using MPR of CT has potential clinical utility as a complementary tool for pre-operative planning using three-dimensional templating software. Moreover, this technique could be feasible in most hospitals without additional expenditure.

How Accurate is the Use of Contralateral Implant Size as a Template in Bilateral Hemiarthroplasty?

PURPOSE

Accurately predicting implant size for hemiarthroplasties offers an important contribution to theatre efficiency and patients' intraoperative care. However, pre-operative sizing using templating of implants in hip fracture patients requiring a hemiarthroplasty is often difficult due to non-standard radiographs, absence of a calibration marker, poor marker placement, variable patient position, and in many institutions a lack of templating facilities. In patients who have previously undergone a hemiarthroplasty on the contralateral side, surgeons can use the contralateral implant size for pre-operative planning purposes. However, the accuracy of doing this has not previously been reported. The aim of this study was to investigate the reliability of using an in situ contralateral implant as a predictor of implant size on the contralateral side.

METHODS

A retrospective review of our local neck of femur fracture (NOF) database was undertaken to identify patients who had bilateral hip hemiarthroplasty. Operative records were reviewed to establish the size of prostheses used at operation. Correlation, agreement, and reliability analysis were performed using the least squares, Bland-Altman plot, and intra-class correlation coefficient (ICC) methods, respectively.

RESULTS

Operative records were identified for 45 patients who had bilateral hemiarthroplasties. There was a difference in implant size used in 58% of cases. Of these 77% required a larger implant on the right. Implant sizes were within 1 mm of the contralateral side in 78% and within 2 mm in 91% of patients. However, in 9% of patients, there was a discrepancy greater than 2 mm with some cases having up to 6 mm discrepancy. Correlation coefficient was 0.83 and the ICC 0.90.

CONCLUSIONS

The findings in this study indicated that using the size of a contralateral implant can be used as a reliable indicator of head size in cases of bilateral hemiarthroplasty. However, the surgeon should remain cautious as there is a one in ten chance of there being a 3 mm or more difference in implant size.

Preoperative sizing of hip hemiarthroplasties to accurately estimate head size from non- standardised pelvic radiographs: Can it be done?

BACKGROUND

Preoperative sizing of implants for hip fracture patients requiring a hemiarthroplasty is difficult due to non-standardised radiographs, absence of sizing marker, variable patient position and body habitus. We investigated whether a simple tool could help predict femoral head size, allowing surgeons to safely proceed with surgery when implant stocks are limited, and to potentially improve theatre efficiency.

METHODS

Three independent reviewers measured the maximum width of the contralateral (intact) femoral head using PACS software in 50 cases of intracapsular hip fracture. This was linearly regressed on actual implant size to calculate the average magnification coefficient. Inter- and intra-rater reliability were evaluated using intraclass correlation coefficients (ICC).

RESULTS

The best fitting magnification constant was 118% (95% confidence interval 16.0-19.7%), which achieved a mean error of 1.7 mm. Prediction accuracy was significantly improved by allowing a constant (intercept) as a second parameter in the regression model (p = 0.01), which achieved a mean error of just 1.4 mm from the implant used. The inclusion of the constant reduces errors at the upper and lower extremes of head sizes. ICCs for inter- and intra-rather agreement were 0.94 and 0.98 respectively.

CONCLUSION(S)

We have shown that hip hemiarthroplasty head sizes can be reliably and accurately predicted from non-standardised pre-operative radiographs. We have devised a method which can easily be adopted by other centres and tailored to the characteristics of their radiology department.

Improving the accuracy of digital templating: achieving success through stakeholder management

The use of a marker ball in digital templating for hip arthroplasty is a well-established method of preoperative planning and is used to overcome the inherent magnification in plain film radiographs. Our hospital policy is to place a marker ball in all anteroposterior pelvic films taken in the emergency department (ED) which have been requested for suspected neck of femur fractures. We carried out a baseline measurement followed by three Plan-Do-Study-Act cycles for all pelvic films taken in ED during July 2016, November 2016, February 2017 and November 2017. Interventions between the baseline measurement and cycle 1 were to educate the lead radiographer and publish the results in the radiology newsletter, and between cycles 1 and 2 was to run a teaching session for radiographers, display posters in the X-ray department and place an electronic prompt on the X-ray machine to alert them of the need to place a marker ball in the X-ray field. Cycle 3 looked to see if improvements were sustained. 16/81 (20%) radiographs complied with the policy in our baseline measurement; 25/51 (46%, p=0.002) in cycle 1; 40/54 (74%, p=0.0056) in cycle 2; and 48/63 (76%) in cycle 3. Our quality improvement project led to large improvements in clinical practice through straightforward, small, but appropriately targeted interventions. Stakeholder management is key to successfully implementing change. The next step is to switch from the VoyantMark to the KingMark marker ball, as it has greater accuracy of templating and is also easier to place within the field of an X-ray.

Hip Hemiarthroplasty in Neurologic or Cognitively Impaired Patients: A Case Series of Post-operative Dislocations

Introduction:

Hemiarthroplasty is the operation of choice for displaced intracapsular neck of femur fracture in elderly patients with low physical demands. Dislocation in this frail patient cohort can have devastating consequences. The patients with neurological and cognitive impairment are at additional risk secondary to imbalance of muscle tone and a reduced ability to engage with rehabilitation.

Case Report:

We present three cases of early post-operative dislocation of hip hemiarthroplasties, all of whom suffered from neurological and cognitive impairment, and highlight the uncontrollable patient factors that contributed to dislocation.

Conclusion:

The posterior approach was associated with all cases of dislocation in patients who also were neurologic or cognitively impaired. Posterior approach is safe to perform in the general population for hip hemiarthroplasty; however, the surgeon should consider avoiding the use of the posterior approach in this high-risk group.

Reliable anatomical landmarks for minimizing leg-length discrepancy during hip arthroplasty using the lateral transgluteal approach for femoral neck fracture

BACKGROUND

The purpose of this study was to describe our experience of a preoperative templating technique, and to investigate the most reliable anatomical reference to minimize leg length discrepancy (LLD) during hip arthroplasty using the lateral transgluteal approach for femoral neck fractures. We hypothesized that the medial fracture tip and greater trochanter would be viable alternative anatomical References METHODS: A total of 156 hip arthroplasty cases were enrolled in the present study (103 women, 114 hemiarthroplasties, 42 total hip arthroplasties). Preoperative acetate overlay templating was conducted based on pelvic anteroposterior radiographs. Three different anatomical references were used to determine the bony resection level, including the uppermost point of the lesser trochanter, uppermost point of the greater trochanter, and medial fracture tip. The accuracy of preoperative templating and the reliability of each anatomical reference for minimizing LLD were assessed.

RESULTS

Significant differences in postoperative LLD after hip arthroplasty between the three groups were identified. Post-hoc analysis showed that postoperative LLD in group A was significantly larger than that in groups B or C in hip arthroplasty.

CONCLUSION

The results of this study suggest that the use of the lesser trochanter as an anatomical reference to determine the level of femoral neck osteotomy should be discouraged, and that the medial fracture tip and greater trochanter may be better alternatives when using the lateral transgluteal approach.

Does restoration of leg length and femoral offset play a role in functional outcome one year after hip hemiarthroplasty?

BACKGROUND

The objective of this study was to evaluate the correlation between specific joint biomechanical parameters and 1year functional outcome scores in elderly patients receiving hemiarthroplasty in the setting of intracapsular hip fractures.

METHODS

This is a retrospective, institutional registry based study. 168 hip hemarthroplasties were captured from October 2013 to June 2015. Patients were excluded based on contralateral hip surgery, perioperative complications or inadequate radiographs. 84 patients were alive at one year follow up. We compared mobility and pain scores to radiographically determined variations of leg lengths and femoral offset. We also compared the performance of fellowship trained arthroplasty surgeons to their non-fellowship trained counterparts.

RESULTS

The operated leg was a mean of 1.12±6.8mm longer than the contralateral. leg length discrepancy (LLD) was less than 10mm in 72 patients. Mean difference in offset between limbs was 0.25±3.3mm. The difference was within 5mm in 79 patients (94%). We found no statistically significant correlation between mobility or pain scores and variations in leg length or offset. We found significantly better performance of the arthroplasty surgeons in restoring leg length but no difference in offset reconstruction or functional benefit for the patient.

CONCLUSIONS

Our study was unable to demonstrate a significant relationship between leg length or femoral offset restoration and the patient's ultimate functional recovery. Arthroplasty surgeons performed better in restoring leg length, but no associated functional advantage was seen.