The impact of leg length discrepancy on patient satisfaction and functional outcome following total hip arthroplasty

Impact of Offset and Leg Length on Functional Outcomes Post-Total Hip Arthroplasty: How Accurate Should Coronal Reconstruction Be?

BACKGROUND

Accurate hip reconstruction is associated with improved biomechanical behavior following total hip arthroplasty (THA). However, whether this is associated with improved patient-reported outcomes (PROs) is unknown.

HYPOTHESIS/PURPOSE

This study aimed to: 1) describe the ability to reconstruct coronal geometry during THA without advanced technology; 2) assess whether restoration of global offset (GO) and leg length (LL) is associated with improved PROs; and 3) investigate whether increased femoral offset (FO) to compensate for reduced acetabular offset (AO) influences PROs.

METHOD

This was a prospective, multicenter, consecutive cohort study of 500 patients treated with primary THA without robotics or navigation. The Oxford Hip score (OHS) was obtained preoperatively and at 1-year follow-up. Supine anteroposterior pelvic radiographs were analyzed to determine AO, FO, GO, and LL relative to the native contralateral side. Contour plots for ΔOHS based on ΔLL and ΔGO were created, and ΔOHS was calculated within and outside various ranges (±2.5, ±5, or ±10 mm).

RESULTS

In the operated hip, mean FO increased by 3 ± 6 mm (range, -16 to 27), while AO decreased by 2 ± 4 mm (range, -17 to 10). The contour graph for ±2.5 mm zones showed the best outcomes (ΔOHS >25) with GO and LL centered on 0 ± 2.5 mm (P < .01). However, only 10% achieved such reconstruction. When GO and LL differences were within ±10 mm, ΔOHS was superior when both AO and FO were within ±5 mm (mean: 24 ± 10; range, -5 to 40) compared with when FO was above 5 mm to compensate for a reduction in AO (mean: 22 ± 11; range, -10 to 46; P = .040).

CONCLUSIONS

The PROs were associated with biomechanical reconstruction, and the best clinical improvement can be expected when GO and LL differences are both within 2.5 mm. Maintenance of AO is important, as compensation by increasing FO is associated with inferior OHS.

Comparative Study of Alternative Methods for Measuring Leg Length Discrepancy after Robot-Assisted Total Hip Arthroplasty

BACKGROUND

Our study addresses the lack of consensus on measuring leg length discrepancy (LLD) after total hip arthroplasty (THA). We will assess the inter-observer variability and correlation between the five most commonly used LLD methods and investigate the use of trigonometric principles in overcoming the limitations of current techniques.

METHODS

LLD was measured on postoperative AP pelvic radiographs using five conventional methods. CT images created a 3D computer model of the pelvis and femur. The resulting models were projected onto a 2D, used to measure LLD by the five methods. The measurements were evaluated via Taguchi analysis, a statistical method identifying the process's most influential factors. The approach was used to assess the new trigonometric method.

RESULTS

Conventional methods demonstrated poor correlation. Methods referenced to the centers of the femoral heads were insensitive to LLD originating outside the acetabular cup. Methods referencing either the inter-ischial line or the inter-obturator foramina to the lesser trochanter were sensitive to acetabular and femoral components. Trigonometry-based measurements showed a higher correlation.

CONCLUSIONS

Our results underscore clinicians' need to specify the methods used to assess LLD. Applying trigonometric principles was shown to be accurate and reliable, but it was contingent on proper radiographic alignment.

Forgotten joint score associated with prosthesis weight in cementless total hip arthroplasty: a prospective clinical study

Background

This prospective study aimed to investigate the influence of weight difference between implanted prosthesis and removed bone in cementless total hip arthroplasty (THA) on hip awareness and patient-reported outcomes.

Methods

A total of 48 patients (56 hips) who underwent primary THA were prospectively enrolled. Implanted prosthesis and removed bone were weighed intraoperatively. Forgotten Joint Score (FJS) and Western Ontario and McMaster Universities (WOMAC) scores were obtained before and at 1 and 3 months after surgery. Patients were divided into groups A, B, and C according to the percentile of the weight difference.

Results

The mean weight difference of the implanted prosthesis and removed bone was 117.97 ± 47.35 g. A negative correlation was found among the weight differences of the three groups and 1- and 3-month postoperative FJS (correlation coefficients, -0.331 and -0.734, respectively). A positive correlation was found among the weight difference of the three groups and 3-month postoperative WOMAC (correlation coefficient, 0.403). A significant difference in 3-month postoperative FJS and WOMAC scores was found among the three groups. The mean 3-month postoperative FJS (79.00) of group C was significantly lower than that of group A (93.32) (P < 0.05). The mean WOMAC score (15.83) of group A was significantly lower than that of group C (23.67) (P < 0.05).

Conclusion

The implanted prosthesis is larger than the removed bone in cementless THA. The weight difference is negatively correlated with hip function. The weight difference should be minimized to achieve optimal hip joint awareness.

A Novel Approach for Correcting Limb Length Discrepancy in Total Hip Arthroplasty

INTRODUCTION

This study aimed to evaluate the accuracy of the suture technique, along with the utilization of a spirit-level device which is an instrument designed to indicate whether a surface is horizontal or vertical, in comparison to the conventional supraacetabular pin method and caliper measurement for correcting leg length discrepancy (LLD) during total hip arthroplasty (THA). Materials and methods: Consecutive patients who underwent unilateral primary THA between January 2021 and March 2023 were included in the study. The exclusion criteria were severe flexion and adduction contracture that could affect the accuracy of measurements, a history of lower extremity surgery, the presence of lower extremity deformity, and the absence of postoperative full-length radiographs. Patients were allocated into two groups based on the technique employed for correcting LLD during THA. Group 1 (n=62) consisted of patients evaluated using the suture technique with a spirit-level device, while group 2 (n=75) comprised patients who underwent the supraacetabular pin method with caliper measurement. The distance between the inter-teardrop line and the tip of the lesser trochanter was measured for both hips to assess LLD.

RESULTS

The mean preoperative LLD was similar between groups, which was 11.6 ± 9.1 mm in group 1 and 9.5 ± 9.8 mm in group 2 (p=0.191). Postoperatively, group 1 had a significantly lower LLD compared to group 2 (p<0.001).

CONCLUSION

According to the results obtained from this study, the use of a suture technique in conjunction with a spirit-level device to achieve a consistent leg position is an effective method for correcting LLD during THA.

Effect of longer femoral head on leg length, offset, and range of motion in total hip arthroplasty: a simulation study

In this study, we investigated the relationship between head length, leg length, offset, and dislocation resistance using range of motion (ROM) simulations based on computed tomography data to examine if a longer femoral head reduces the risk of dislocation. The femoral components were set to eliminate leg length differences with a + 0 mm head, and variations for + 4-, + 7-, and + 8-mm heads were analyzed. Offset and ROM were assessed when longer heads were used, with the leg length adjusted to be similar to that of the contralateral side. While internal rotation at flexion and external rotation at extension increased with + 4-mm longer heads, the + 7- and + 8-mm heads did not increase dislocation resistance. When adjusting for leg length, the longer heads showed no significant differences in offset and ROM. Enhancing dislocation resistance by solely increasing the offset with a longer head, while simultaneously adjusting the depth of stem insertion, may be a beneficial intraoperative technique. Although a + 4-mm longer head possibly increases ROM without impingement, heads extended by + 7 or + 8 mm may not exhibit the same advantage. Therefore, surgeons should consider this technique based on the implant design.

Primary Cementless Femoral Stems in Conversion Hip Arthroplasty After Failed Fixation of Intertrochanteric Fractures

Salvage conversion hip arthroplasty is a viable solution to restore function and reduce pain after failed intertrochanteric hip fracture fixation. Our primary objective was to assess early outcomes achieved with primary cementless metaphyseal-engaging femoral stems for conversion hip arthroplasty compared with revision diaphyseal-engaging stems. This was a retrospective review of 70 patients with failed intertrochanteric hip fractures subsequently managed with conversion total hip arthroplasty or hemiarthroplasty. Thirty-five patients who underwent conversion using a primary cementless stem were compared with 35 patients who underwent conversion using a revision stem. The groups were similar regarding sex, body mass index, American Society of Anesthesiologists classification, preoperative diagnosis, and implants removed. Clinical and radiographic outcomes and complications were compared over a mean follow-up of 6 years. The primary stem cohort had a shorter mean hospital stay (3.03 vs 4.34 days, P=.028). There were no significant differences between the primary and revision cohorts regarding mean time to conversion (2.26 vs 1.75 years, P=.671), operative time (127 vs 131 minutes, P=.611), incidence of discharge to home (54.3% vs 37.1%, P=.23), postoperative complications (5.71% vs 5.71%, P=1.0), reoperations (5.71% vs 11.4%, P=.669), leg length discrepancy (5.33 vs 7.38 mm, P=.210), subsidence (20.0% vs 23.3%, P=.981), and Hip dysfunction and Osteoarthritis Outcome Score for Joint Replacement (78.6 vs 81.9, P=.723). We report comparable outcomes of conversion hip arthroplasty with the use of primary cementless and revision stems. Current primary cementless femoral stems may be considered for conversion hip arthroplasty for failed intertrochanteric fracture fixation. [Orthopedics. 2024;47(1):e6-e12.].

Assessing Leg Length and Offset in Anterior Total Hip Arthroplasty: Overlay Versus AP Pelvis Intraoperative Radiographic Techniques: A Retrospective Cohort Study

INTRODUCTION

Two intraoperative radiographic techniques to determine leg length and offset during anterior total hip arthroplasty (THA) are the AP pelvis and overlay techniques. The AP pelvis method measures LLDs and offset using AP fluoroscopic images, whereas the overlay method uses printed images of the native and replaced hips. The purpose of this study was to compare these techniques regarding clinical and radiographic LLD and offset discrepancies.

METHODS

Patients of a single surgeon at two hospitals from September 2017 to January 2021 were retrospectively reviewed. Clinically detectable LLD was recorded. Radiographic measurements were obtained from preoperative and postoperative radiographs. LLD was determined based on the vertical distance between the lesser trochanters and the ischial tuberosities. Total offset was measured using a combination of femoral and medial offset. The Student t-test, Fisher exact test, and Wilcoxon rank sum tests were used for statistical analysis.

RESULTS

Seventy-one procedures were done using the overlay technique and 61 used for the AP pelvis technique. No significant differences were observed in mean postoperative LLD (2.66 versus 2.88 mm, P = 0.66) and mean postoperative offset discrepancy (5.37 versus 4.21 mm, P = 0.143) between the overlay versus AP pelvis groups. The mean preoperative to postoperative absolute difference in offset was less than 5 mm in both groups. Clinically detectable LLD was noted in six of 71 patients in the overlay group and one of 61 in the AP pelvis group (P = 0.123).

CONCLUSION

No notable differences were observed in intraoperative leg length and offset discrepancies during direct anterior THA between the AP pelvis and overlay techniques, suggesting they are equally effective in determining LLD and offset intraoperatively. The choice of technique to use anterior THA should be based primarily on the surgeon's preference, comfort, and available resources.

Intraoperative method of femoral head central measurement to prevent leg length discrepancy following hemiarthroplasty

Purpose

This study aimed to introduce and investigate the safety and efficiency of the intraoperative central measurement method of the femoral head (IM-CMFH) to prevent leg length discrepancies (LLD) after hemiarthroplasty.

Methods

Overall, 79 patients aged 75 to 85 years with femoral neck fractures who underwent hemiarthroplasty were divided into two groups: the Control group (n = 46) and the IM-CMFH group (n = 33). The two groups were compared for postoperative LLD and the proportions of patients with greater than 10 mm, 6-10 mm, and within 5 mm, postoperative femoral offset (FO) difference and the proportions of patients within 5 mm, incremental greater than 5 mm and reduction greater than 5 mm. Next, the vertical distance from the center of the femoral head to the tip of the greater trochanter on the anatomical axis of the femur (VD-CFH-TGTAAF), leg length, and FO on the operative and non-operative sides within the IM-CMFH group. Finally, operative time, hemoglobin loss, Harris scores 3 months after surgery, and postoperative complications were analyzed.

Results

Compared with the control group, the postoperative LLD and FO differences were significantly lower in the IM-CMFH group (P = 0.031; P = 0.012), and the proportion of patients with postoperative LLD greater than 10 mm decreased significantly (P = 0.041), while the proportion of patients with FO difference of within 5 mm increased (P = 0.009). In addition, there was no significant difference in the operative time, hemoglobin loss, and Harris score at 3 months postoperatively and postoperative complications between the two groups (P > 0.05). There was no significant difference in FO, leg-length, and VD-CFH-TGTAAF between the operative and non-operative sides within the IM-CMFH group (P > 0.05).

Conclusion

Satisfactory results can be achieved by using the IM-CMFH to prevent LLD following hemiarthroplasty, and there is no increase in operative time, hemoglobin loss, or postoperative complications. This technique is efficient for hemiarthroplasties and is both simple and convenient.

More than a feeling?-Overruling the preoperatively templated offset option leads to a minor offset increase in short stem total hip arthroplasty

PURPOSE

Short stems are increasingly used in total hip arthroplasty (THA) because of advantages in bone and soft tissue preservation and reconstruction of hip geometry. Digital templating is essential in determining the correct offset option and stem size in THA. However, the preoperative template sizes might be intraoperatively overruled.

PATIENTS AND METHODS

We evaluated the effect of intraoperative overruling of the preoperatively templated offset option of a short curved stem on hip offset, leg length, implant positioning, and femoral canal fill index. The overruling was performed in case of intraoperative instability, telescoping, or both. A series of 1052 consecutive THAs with a cementless short curved stem and press-fit cup was retrospectively screened. One hundred patients with unilateral THA and a contralateral native and morphologically healthy hip as a reference met the inclusion criteria. Measurements were carried out on preoperative and 3 months anterior-posterior postoperative radiographs. Patients were divided according to the overruling by offset option or stem size.

RESULTS

Hip offset was increased in all groups, but only with significant increase if an offset option + 1 was used intraoperatively (p = 0.025). LLD was restored without significance in all groups (p = 0.323; p = 0.157).

CONCLUSION

Intraoperative overruling of the preoperative digital template in cementless short stem total hip arthroplasty results in an increase of hip offset compared to a contralateral healthy hip. However, the increase is marginal and clearly under 5 mm compared to the contralateral healthy hip.

High varus stem alignment in short-stem total hip arthroplasty: a risk for reconstruction of femoro-acetabular offset, leg length discrepancy and stem undersizing?

PURPOSE

Short stems are increasingly used in in total hip arthroplasty (THA) because of advantages in bone and soft tissue preservation and reconstruction of hip geometry. Short stems can be inserted in a more varus position compared to conventional straight stems. This poses the risk of final varus misplacement of the femoral component, which is not intended in all femoral short stems.

METHODS

We wanted to evaluate the effect of a high varus stem positioning in MIS THA on hip offset, leg length and femoral canal fill index. A series of 1052 consecutive THAs with a singular cementless femoral short stem and press-fit cup was retrospectively screened for inclusion. One hundred six patients with unilateral THA and a contralateral healthy hip met the inclusion criteria. Measurements were carried out on preoperative and 3 months anterior-posterior postoperative radiographs. Patients were divided into Group A (varus stem alignment ≤ 3°) and Group B (varus stem alignment > 3°).

RESULTS

Hip offset (HO) increased significantly in Group B by 4 mm (p = 0.013). No influence on leg length difference was detected in both groups. Preoperative CCD angle was significantly lower in Group B (p < 0.001). Canal Fill Indices (CFI) were significantly lower in Group B (CFI I: p < 0.001; CFI II p = 0.003; CF III p = 0.002).

CONCLUSION

High varus stem alignment > 3° leads to a statistically significant but minor increase in HO and poses the risk of stem undersizing. A preoperatively low genuine CCD angle pose a risk for varus stem positioning.

Improved hip symmetry with an adjustable fluoroscopic grid during total hip arthroplasty

BACKGROUND

The use of intraoperative fluoroscopy (IF) is common with direct anterior total hip arthroplasty (THA), however image distortion in IF may limit its usefulness. The supplementation of IF with an adjustable grid (AG) may provide consistently better accuracy in component placement. Therefore, the purpose of this study was to compare the accuracy, consistency, and surgical efficiency between IF only and AG supplementation.

METHODS

2 cohorts were retrospectively evaluated, including 573 IF only patients and 211 AG patients having undergone unilateral THA between 2011 and 2018. Post-THA radiographic assessment was performed to evaluate the accuracy of component placement, with target placements for global hip offset (GHO) and leg-length differences (LLD) <10 mm and acetabular cup abduction of 45° (±10°). Accuracy and surgical efficiency were evaluated between groups and over time.

RESULTS

The AG group had a significant greater percentage of components placed within the target zone compared to IF only for GHO (99.5%, 92.7%, p < 0.001), LLD (99.1%, 96.5%, p = 0.039) and abduction (99.5%, 96.3%, p = 0.009), with no difference in fluoroscopic time (p = 0.973). Over time, accuracy was significantly different in IF group for GHO (p = 0.008) and abduction (p = 0.002) and trended toward significance for LLD (p = 0.055). There were no significant differences over time for the AG group.

CONCLUSIONS

The addition of an AG to IF significantly increased the accuracy of component placement during direct anterior THA. These results were consistent over 2 years of use and did not decrease surgical efficiency.

Biomechanical compensation mechanisms during stair climbing - The effect of leg length inequalities

BACKGROUND

Stair climbing is a complex and demanding daily activity with increased physical loads. Therefore, analyzing stair climbing abilities is a frequently used diagnostic tool. Leg length inequalities (LLIs) are a common condition in the population, with individual consequences like lower back pain, scoliosis, and osteoarthritis. Despite its high prevalence, the necessary treatment, for mild LLIs, is still controversial. Previously, the focus was to analyze the effects of LLIs during static standing and walking. To create a holistic view on the dynamic effects of LLIs, and since climbing stairs produces a similar biomechanical imbalance as LLIs, the compensation mechanics during stair climbing are of special interest.

RESEARCH QUESTION

What are the biomechanical compensation mechanisms of (simulated) LLIs during ascending and descending stairs?

METHODS

Thirty-five healthy participants were measured with the inertial measurement system MyoMotion during stair climbing with simulated LLIs of 0-3 cm. The maximum estimated lower limb joint angles of the long and short leg were analyzed with statistically repeated measurement models.

RESULTS

The long leg showed significantly increased hip and knee flexion, while the short leg showed decreased hip and knee flexion, decreased dorsiflexion, and significantly increased plantarflexion. Different mechanisms were found in the case of 1 cm LLI when compared to greater LLIs. In the former, increased hip and knee flexion in the short leg accompanied by increased dorsiflexion in the long leg was observed. In the latter, the dorsiflexion of the long leg was reduced.

SIGNIFICANCE

Except for the reduced dorsiflexion of the long leg (LLI >1 cm), during stair climbing compared compensation mechanisms as during walking were presented, with the long leg functionally shortened and the short leg lengthened. Although the feet were already on different levels, during stair climbing with the step-over-step technique, significant compensation mechanisms were found as a consequence of LLIs.

Reliability of a simple fluoroscopic image to assess leg length discrepancy during direct anterior approach total hip arthroplasty

BACKGROUND

Direct anterior approach (DAA) total hip arthroplasty (THA) in a supine position provides a unique opportunity to assess leg length discrepancy (LLD) intra-operatively with fluoroscopy. Reported fluoroscopic techniques are useful but are generally complicated or costly. Despite the use of multiple techniques for leg length assessment, LLD continues to be a major post-operative source of patient dissatisfaction further emphasizing the importance of near-anatomic restoration. The utility of an alternative direct measurement of LLD on an intra-operative fluoroscopic pelvic image during DAA THA has not been reported.

AIM

To determine the reliability of a novel simple intra-operative measurement of LLD using a parallel line technique on a single fluoroscopic digital image of the pelvis.

METHODS

One hundred and seventy-one patients who underwent DAA THA were included for analysis. Intra-operative fluoroscopic and post-operative anterior-posterior radiographs were imported to TraumaCad and calibrated for LLD measurement. LLD was measured on each image using the right-left hip differences in lesser trochanter to pelvic reference line distances. Pelvic reference points included the teardrops and ischia. Fluoroscopic LLD was compared to the gold-standard measurement of LLD measured on a post-operative radiograph.

RESULTS

Mean absolute difference in teardrop referenced LLD between fluoroscopic and post-operative radiographs was 2.17 mm and based on the ischia mean absolute difference was 2.63 mm. Linear regression of fluoroscopic and post-operative radiograph LLD based on teardrop and ischia LLD found r² values of 0.57 and 0.84, respectively. Mean absolute difference between fluoroscopic and post-operative x-ray LLD was within 5 mm in 95% of cases regardless of pelvic reference.

CONCLUSION

This study demonstrates that a single fluoroscopic view obtained during DAA THA for leg length assessment is clinically useful.

A Role for Modern Primary Cementless Femoral Stems in Revision Hip Arthroplasty

BACKGROUND

In revision total hip arthroplasty (THA) cases with preserved femoral metaphyseal bone, tapered proximally porous-coated "primary" femoral stems may be an option. The objective of this study was to compare outcomes of patients with Paprosky I or II femoral bone loss undergoing revision THA with either a primary metaphyseal-engaging cementless stem or a revision diaphyseal-engaging stem.

METHODS

This was a retrospective analysis of 70 patients with Paprosky I or II femoral bone loss who underwent femoral revision. 35 patients who were revised using a primary cementless femoral stem were compared with 35 patients who underwent femoral revision using a revision diaphyseal-engaging stem. The groups were similar regarding age, gender, body mass index, and American Society of Anesthesiologists. Clinical and radiographic outcomes and complications were compared over an average follow-up of 2.9 years (SD 1.4).

RESULTS

Revision THA was most commonly performed for periprosthetic joint infection (N = 27, 38.6%). The groups were similar with regards to Paprosky femoral classification (P = .56), length of stay (P = .68), discharge disposition (P = .461), operative time (P = .20), and complications (P = .164). There were no significant differences between primary and revision femoral stem subsidence (0.12 vs. 0.75 mm, P = .18), leg length discrepancy (2.3 vs. 4.05 mm, P = .37), and Hip Disability and Osteoarthritis Outcome Score Jr (73.1 [SD 21.1] vs. 62.8 [SD 21.7], P = .088). No patient underwent additional revision surgery involving the femoral component.

CONCLUSION

Use of modern primary cementless femoral stems is a viable option for revision hip arthroplasty in the setting of preserved proximal femoral metaphyseal bone. Outcomes are not inferior to those of revision stems and offer potential benefits.

The occurrence rate and clinical application of Osteo-line on the femur neck

Background

This study was done to observe the incidence of Osteo-line on the femur neck and to explore the clinical application of Osteo-line in osteotomy.

Methods

Eighty-nine adult femur specimens were selected to observe the incidence of Osteo-line on the femur neck. From August 2015 to January 2019, a total of 278 patients who completed unilateral hip arthroplasty at the Third Hospital of Hebei Medical University were retrospectively included. Patients who accepted osteotomy via Osteo-line on the femur neck were defined as the experimental group (n = 139), and patients who accepted osteotomy via traditional method (The femoral distance 1.5 cm above the trochanter was retained for osteotomy by visual inspection.) were defined as the control group (n = 139). According to the postoperative pelvic X-ray, Photoshop was used to evaluate the leg length discrepancy (LLD) by the CFR-T-LT method.

Results

Among the 89 specimens, the incidence of anterior Osteo-line was 75.28%, and the incidence of posterior Osteo-line was 100%. According to the clinical application results, the incidence of anterior Osteo-line on the femur neck was 80%, and the incidence of posterior Osteo-line was 100%. The Osteo-line was clearer than those on the femoral specimens. Twenty-six cases had LLD greater than 1 cm (9.29%), including 2 cases in the experimental group and 24 cases in the control group. The average postoperative LLD in the experimental group (0.19 ± 0.38 mm) was significantly shorter than in the control group (0.54 ± 0.51 mm)(P = 0.005).

Conclusion

The incidence of Osteo-line on the femur neck was high, and patients who accepted osteotomy via Osteo-line on the femur neck can achieve shorter postoperative LLD than the control group.

Changes in patient-perceived leg length discrepancy following total hip arthroplasty

PURPOSE

Leg length discrepancy (LLD) after total hip arthroplasty (THA) prevents functional recovery and reduces patient satisfaction. We investigated impact of changes in patient-perceived LLD on patient satisfaction and walking ability.

METHODS

one hundred and forty-nine patients with unilateral hip osteoarthritis undergoing THA from 2014 to 2017, (125 women, 24 men; average age, 68.5 years) with an objective LLD < 1 cm were included. Outcome measures included the patient-perceived LLD, Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index, 10-m walking speed, and affected leg loading rate, assessed preoperatively and at 3 weeks, 3 months, and 1 year postoperatively.

RESULTS

The absolute patient-perceived LLD (mean ± SD) (the number of patients with perceived LLD > 5 mm) were 6.4 ± 9.6 mm [88 patients (59%)] preoperatively; and 2.2 ± 4.0 mm [48 (32%); p < 0.001], 0.7 ± 2.3 mm [17 (11%); p < 0.001], and 0.4 ± 1.6 mm [10 (7%); p = 0.095] at 3 weeks, 3 months, and 1 year postoperatively, respectively. All outcome measures improved over time. One year postoperatively, a weak positive correlation between the patient-perceived LLD and WOMAC or 10-m walking speed (r = 0.24, 0.23, respectively) was found. The risk of patient-perceived LLD persisting > 1 year postoperatively was 5.5-fold higher in patients who exhibited it at 3 months and those with a WOMAC score > 10 at 3 months postoperatively, using multivariate logistic regression.

CONCLUSION

Achieving a post-THA objective LLD < 1 cm significantly reduced the patient-perceived LLD up to 3 months postoperatively. The residual patient-perceived LLD at 1 year postoperatively was predicted from the WOMAC score or the presence of patient-perceived LLD at 3 months after THA.

LEVEL OF EVIDENCE

Therapeutic level IV.

A Vertical Measurement System to Predict the Change in Leg Length in Total Hip Arthroplasty

The management of leg lengths in total hip arthroplasty continues to challenge orthopaedic surgeons. The aim of this study is to test the reliability of a measuring device used to measure the resected femoral head and how the resulting intra operatively calculated change in leg length compares to the radiographically measured change in leg length. Four orthopaedic surgeons measured 20 femoral heads and the intra class coefficients of the raters were between 0.955 and 0.990 with a mean difference less 1 mm, indicating the reliability of the device. The ‘actual’ radiographic leg length correction of 50 patients and the ‘predicted’ intra operatively calculated correction was analysed with a linear regression model and 47 measurements were within 2 mm and the remaining 3 within 4 mm.

Biomechanical reconstruction parameters obtained after direct anterior approach total hip arthroplasty do not compromise clinical outcome

INTRODUCTION

Accurate reconstruction of biomechanical parameters following total hip arthroplasty (THA) is crucial for good joint function. We investigated how reconstruction parameters achieved by minimally invasive anterior (MIS) THA may influence function and patient-related outcomes.

METHODS

A consecutive series of 95 patients treated by MIS THA for primary osteoarthritis were retrospectively reviewed. Primary outcome measures were Harris Hip Score (HHS), hip disability and osteoarthritis outcome score (HOOS) and EQ-5D. Femoral offset (FO), abductor lever arm (ALA), centre of rotation (CoR), leg length discrepancy (LLD), cup version and stem alignment were measured pre- and post-operatively. Obtained reconstruction parameters compared to the contralateral hip were used as independent variables in a multivariate regression with each primary outcome measure as dependent variable.

RESULTS

Mean age at surgery was 69 years. HHS rated 94.7% of patients as good/excellent and mean EQ-5D was 0.82. Post-operative HOOS subscales showed no statistical difference compared to the Italian benchmark population. Stem alignment averaged 0.2° valgus, mean cup inclination was 37.8° and mean anteversion was 12.8°. When compared to the contralateral side, CoR was post-operatively elevated by 2.6 mm and medialized by 2.4 mm averagely. An average FO reduction of -0.5 mm was observed while FO ratio increased by 1.9% averagely. ALA decreased by -3.3 mm while LLD was 2.3 mm averagely. Multivariate regression analysis revealed a significant contribution of ALA to HHS only.

CONCLUSIONS

Biomechanical parameters achieved by MIS THA are satisfactory with negligible impact on functional results and no impact on patient-related outcomes certifying the high quality achieved in THA.

How is quality of life after total hip replacement related to the reconstructed anatomy? A study with low-dose stereoradiography

PURPOSE

The purpose of this study was to evaluate the relationships between the three-dimensional anatomy of operated hip in standing position using low-dose stereo-radiography imaging system and postoperative hip disability and osteoarthritis outcome score (HOOS) after total hip arthroplasty (THA).

MATERIAL AND METHODS

A total of 123 patients who underwent THA during a one-year period were included. There were 50 men and 73 women with a mean age of 67.3±13.6 (SD) years (range: 19-89 years). All patients underwent pre- and postoperative low-dose stereo-radiography examination and completed a HOOS form (score from 0 to 100, 100 for full satisfaction). We recorded 16 anatomical parameters before THA, and 15 after THA. After binary transformation of HOOS score using 70 as threshold value, outcome was assessed using logistic or generalised linear models.

RESULTS

A total of 103 patients (103/123; 83.7%) had a HOOS score≥70 and were considered as the satisfied group. A significant difference in pelvic incidence (the angle between a line perpendicular to the sacral plate at its midpoint and a line connecting the same point to the centre of the bicoxofemoral axis) was found between the satisfied 56.4±10.4 (SD)° (range: 31-85°) and the unsatisfied group 48.7±8.9 (SD)° (range: 40-65) (P=0.006). The relative variation of offset (distance from the centre of rotation of the femoral head to a line bisecting the long axis of the femur) compared to the contralateral hip was -7% in the satisfied group and 7.2% in the unsatisfied group (P=0.01).

CONCLUSION

Pelvic incidence, a parameter independent of the reconstructed anatomy, probably influences the quality of life of patients with THA, via pelvic compensatory capabilities. A loss of femoral offset negatively influences the satisfaction of patients.

Influencing Factors for Joint Perception After Total Hip Arthroplasty: Asian Cohort Study

BACKGROUND

Perceiving replaced joints as natural is one of the best scenario after total hip arthroplasty (THA). We investigated the distribution of and influencing factors for patient's joint perception after THA in Asian cohort, which is not well known.

METHODS

We mailed a questionnaire to Asian patients who had undergone THA in our institution between 2012 and 2016, and this study included 318 Asian patients. The questionnaire assessed patient's joint perception, Oxford Hip Score (OHS), Short Form-12 Health Survey (SF-12) physical, mental, and role component summaries, and satisfaction score. Leg length discrepancy and global femoral offset before and after THA were measured using radiographs. The patients were divided into 2 groups with patient's joint perception: natural and artificial perception groups. OHS, SF-12, satisfaction, leg length discrepancy, and global femoral offset were compared between natural and artificial perception groups, and which factors significantly influenced joint perception were determined.

RESULTS

Of the 318 patients, 165 patients (51.8%) perceived their replaced joint as a natural joint. OHS, SF-12 physical and role component summaries, and satisfaction score in natural perception group were significantly higher than those in artificial perception group, without significant difference in SF-12 mental component summary. Multivariate analysis showed that less of usual pain, easier to get in or out of a car, and osteoarthritis in the contralateral hip were positively associated with natural joint perception after THA.

CONCLUSION

This study indicated to surgeons that pain relief and improvement in getting in or out of a car after THA could lead to even better patient's joint perception.

Optimizing leg length correction in total hip arthroplasty

PURPOSE

Residual feeling of leg length discrepancy (LLD) is a common cause of patient dissatisfaction following total hip arthroplasty (THA). The purpose of this study is to propose a method for determining an optimal leg length correction goal in THA.

METHODS

We conducted a retrospective study of 132 patients to examine the radiographic LLD (R-LLD), perceived LLD (P-LLD), and whether or not the patient has an uncomfortable feeling about the leg length after THA.

RESULTS

The residual discomfort rate in all patients was 9.1% (12/132 patients), and ten of these 12 patients felt uncomfortable due to a longer leg length. When R-LLD was within 7 mm, the rate was 6.8% (8/118 patients), which is nearly equal to the rate of 7.8% (5/64 patients) in cases in which R-LLD was within 2 mm. On the other hand, when R-LLD was 8 mm or more, the rate was 57.1% (4/7 patients).

CONCLUSIONS

The results of our study show that 7 mm may be a reasonable threshold for reducing the residual discomfort. However, even with little or no R-LLD, some patients will continue to experience discomfort. We think that this is because of pre-operative differences between R-LLD and P-LLD in such cases. If the patient has a pelvic declination on the affected hip side and a lumbar scoliosis angle that is convex toward the affected hip side before surgery, the ideal length may be a little shorter than the radiographic isometry, since such patients are likely to feel a longer leg length than that shown radiographically.

Comparison of Clinical Outcomes, Radiological Outcomes and Bone Remodeling Outcomes Between Proximal Coated Single-Wedge New Stem and Full Coated Dual-Wedge Classic Stem in 1-Stage Bilateral Total Hip Arthroplasty

Background

This retrospective study investigated the clinical outcomes, radiological outcomes, and bone remodeling patterns associated with a Medial/Lateral Taper (M/L Taper) stem and Link Classic Uncemented (LCU) stem in 1-stage bilateral total hip arthroplasty (THA).

Material/Methods

The results of 52 patients who underwent 1-stage bilateral THA with a M/L Taper stem on one side and an LCU stem on the other between January 2012 and February 2015 were retrospectively compared. Patients were clinically assessed by the Harris hip score (HHS), visual analogue score (VAS) and incidence of complications. Radiological indicators were measured. Periprosthetic bone remodeling was assessed via bone mineral density (BMD) measurements.

Results

The mean follow-up time was 5.2 years. At each follow-up, there was no difference in the HHS and VAS between the 2 groups. The neck-shaft angle, offset, vertical height of the rotational center and limb lengthening were lower in the M/L Taper group than in the LCU group (P<0.001). The Engh total score was lower in the LCU group (P=0.039). Significantly higher (P<0.001) BMDs were observed in the M/L Taper group in Gruen zones 1, 2, and 6. significantly lower (P<0.001) BMDs were observed in the M/L Taper group in Gruen zones 3 and 5.

Conclusions

Due to the increased postoperative neck-shaft angle, the full coated dual-wedge classic stem was prone to cause lower limb lengthening. The proximal coated single-wedge new stem patients were more likely to have an insufficient postoperative neck length. The new stem achieved load transfer and proximal fixation, leading to better proximal femoral bone preservation is more in line with human biomechanical characteristics.

Effect of placement of acetabular prosthesis on hip joint function after THA

The good recovery of hip function after THA depends on reconstruction of acetabular prosthesis accurately. So we investigated the effect of acetabular prosthesis placement on hip joint function after THA and analyzed the clinical data of 432 patients with unilateral THA retrospectively . The patients were followed-up to evaluate the Harris score and hip range of motion (ROM). The hip ROM, the Harris score and the good rate of Harris score were compared between different groups. Comparison of the good rate of Harris score showed that 85%∼100% group of the rotation center horizontal position ratio was higher than >100% group; 80%∼120% group of the rotation center vertical position ratio was higher than >160% group; and the 90%∼110% group and 110%∼130% group of femoral offset ratio were higher than 90% and >130% groups. Comparison of Harris score showed that 85%∼100% and 70%∼85% groups of rotation center horizontal position ratio were higher than 70% and >100% groups; 80%∼120% group of rotation center vertical position ratio was the highest; and 90%∼110% group and 110%∼130% group of femoral offset ratio were higher than >130% and 90% groups. Comparison of hip ROM showed that 85%∼100% and 70%∼85% groups of the rotation center horizontal position ratio were higher than 70% and >100% groups; 80%∼120% group of the rotation center vertical position ratio was the highest; and hip ROM from high to low are 90%∼110%, 110%∼130%, >130% and 90% groups of femoral offset ratio. These findings indicated that during the early follow-up period of THA, if the horizontal position of femoral head rotation center was reconstructed in 0.85 to 1 times of healthy side when compared with reconstruction >1 times of the healthy side and if the vertical position of femoral head rotation center was reconstructed in 0.8 to 1.2 times of the healthy side when compared with reconstruction in >1.6 times of the healthy side, better hip function recovery and optimal hip ROM were obtained. The optimal reconstruction range of femoral offset is 0.9 to 1.3 times of the healthy side.

A simple method to minimize leg length discrepancy in hip hemiarthroplasty

Purpose

We developed a simple method to minimize leg length discrepancy (LLD) during hip arthroplasty. The purpose of this study is to evaluate the accuracy of the method.

Patients and methods

A total of 47 patients who suffered from unilateral femoral neck fracture and underwent hip hemiarthroplasty between 2015 and 2018 were enrolled in this study. We measured the diameter of the contralateral femoral head (D) and the distance (L) between the center of the femoral head and the top of lesser trochanter in the antero-posterior pelvic X-ray view before the operation, the ratio (R) of D to L was calculated. During the operation, the diameter of the femoral head (d) was measured using a Vernier caliper. Then, the distance should be obtained from the center of the femoral head prosthesis to the lesser trochanter was calculated according to the contralateral ratio R.

Results

The mean LLD was 4.4±3.2 mm (−4.0 to 11.1 mm), 80.9% of the patients had LLD <6 mm, 93.6% of the patients with LLD <10 mm, only 6.4% ≥10 mm LLD.

Conclusion

This method is a simple, cost-effective, fast and accurate way to reduce the postoperative leg length discrepancy.

Does body mass index affect restoration of femoral offset, leg length and cup positioning after total hip arthroplasty? A prospective cohort study

Background

In obese patients, total hip arthroplasty (THA) can be technically demanding with increased perioperative risks. The aim of this prospective cohort study is to evaluate the effect of body mass index (BMI) on radiological restoration of femoral offset (FO) and leg length as well as acetabular cup positioning.

Methods

In this prospective study, patients with unilateral primary osteoarthritis (OA) treated with THA between September 2010 and December 2013 were considered for inclusion. The perioperative plain radiographs were standardised and used to measure the preoperative degree of hip osteoarthritis, postoperative FO, leg length discrepancy (LLD), acetabular component inclination and anteversion.

Results

We included 213 patients (74.5% of those considered for inclusion) with a mean BMI of 27.7 (SD 4.5) in the final analysis. The postoperative FO was improper in 55% and the LLD in 15%, while the cup inclination and anteversion were improper in 13 and 23% of patients respectively. A multivariable logistic regression model identified BMI as the only factor that affected LLD. Increased BMI increased the risk of LLD (OR 1.14, 95% CI 1.04 to 1.25). No other factors included in the model affected any of the primary or secondary outcomes.

Conclusion

Increased BMI showed a negative effect on restoration of post-THA leg length but not on restoration of FO or positioning of the acetabular cup. Age, gender, OA duration or radiological severity and surgeon’s experience showed no relation to post-THA restoration of FO, leg length or cup positioning.

A novel positioner for accurately sitting the acetabular component: a retrospective comparative study

Introduction

In this study, we described a positioner which allows a combination of preoperative plan and intraoperative insertion of the cup to improve the reconstruction of the rotation center of the hip.

Materials and methods

A retrospective study was conducted on 32 consecutive patients (group A) using this positioner and 40 consecutive patients (group B) using conventional method; radiological parameters and clinical measurements before operation and at last follow-up were collected and evaluated.

Results

Group A had a reconstructed center of rotation (COR) that was 0.19 mm closer to the anatomic COR in height (P < 0.005), compared with group B with 3.45 mm vertical dislocation. There were no statistically significant differences in the horizontal displacement between the two groups. The accuracy of cup inclination was 42.14 ± 3.57 in the group A and 38.73 ± 7.65 in the group B (P = 0.015). The accuracy of cup anteversion was 14.82 ± 1.44 in the group A and 13.08 ± 5.95 in the group B (P = 0.082). All cups in the group A were radiologically stable, while one cup in the group B was radiologically unstable and was successfully treated with second-stage revision. Both of the groups obtained a higher mean postoperative Harris Hip Score.

Conclusions

Utilizing this positioner helps to restore the COR position more precisely and provides satisfactory radiological and clinical outcomes in the short term, and more studies are required before its widespread adoption for complicated cases.

The association of leg length and offset reconstruction after total hip arthroplasty with clinical outcomes

BACKGROUND

Restoring native hip anatomy and biomechanics is important to create a well-functioning hip arthroplasty. This study investigated the association of hip offset and leg length after hip arthroplasty with clinical outcomes, including patient reported outcome measures, the Trendelenburg Test and gait analysis.

METHODS

In 77 patients undergoing primary hip arthroplasty for osteoarthritis (age mean = 65 SD = 11 years; BMI mean = 27 SD = 5 kg/m²), hip offset and leg length discrepancy were measured on anteroposterior radiographs. The Western Ontario & McMaster Universities Osteoarthritis Index, the Trendelenburg Test and gait were assessed preoperatively, and at 3 and 12 months postoperatively. An inertial measurement unit was used to derive biomechanical parameters, including spatiotemporal gait parameters and tilt angles of the pelvis. Relationships between radiographic and functional outcomes were investigated, and subgroups of patients with >15% decreased and increased femoral offset were analysed separately.

FINDINGS

Patient-reported function scores and clinical tests demonstrated a few significant, weak correlations with radiographic outcomes (Spearman's ρ range = 0.26-0.32; p < 0.05). Undercorrection of femoral offset was associated with lower patient-reported function scores and with more step irregularity as well as step asymmetry during gait. Postoperative leg length inequality was associated with increased frontal plane tilt angle of the pelvis during the Trendelenburg Test and increased sagittal plane motion of the pelvis during gait. Femoral offset subgroups demonstrated no significant differences for patient-reported function scores and outcomes of the Trendelenburg Test and gait analysis.

INTERPRETATION

Reduced hip offset and leg length discrepancy following hip arthroplasty seem to be marginally associated with worse clinical outcomes.

A comparison of radiographic leg-length and offset discrepancies between 2 intraoperative measurement techniques in anterior total hip arthroplasty

BACKGROUND

Anterior total hip arthroplasty (THA) allows the use of intraoperative fluoroscopy to assess leg-length and offset discrepancies. Two techniques to accomplish this are the transverse rod method and the radiographic overlay method. The aim of this study was to determine if they are equally effective options for minimizing postoperative radiologic discrepancies.

METHODS

We completed a retrospective cohort study comparing 106 anterior THAs from 1 surgeon using the transverse rod technique to 94 anterior THAs from another surgeon using the radiograph overlay technique. Radiographic leg-length discrepancy (LLD) and offset discrepancy (OD) were measured independently on postoperative radiographs. Parametric, nonparametric, and categorical statistical tests were used to compare LLD and OD between groups.

RESULTS

Baseline characteristics were similar between groups. The mean LLD of 4.8 mm in the radiograph overlay group was not significantly different from the 4.4 mm mean discrepancy in the transverse rod group (P = .424), and the rates of LLD < 5 mm and LLD < 10 mm were not significantly different (P = .772, P = .179). The mean OD of 5.1 mm in the radiograph overlay group was not significantly different from the 4.8 mm mean discrepancy in the transverse rod group (P = .668), and there was no significant difference in the rates of OD < 5 mm and OD < 10 mm (P = .488, P = .878).

CONCLUSIONS

There was no difference between the measured LLD and OD by the 2 surgeons, suggesting that the techniques are equally effective options.

Leg length discrepancy after total hip arthroplasty: Can leg length be satisfactorily controlled via anterior approach without a traction table? Evaluation in 56 patients with EOS 3D

BACKGROUND

Leg length discrepancy (LLD) occurs in about 25% of cases after total hip arthroplasty (THA) and adversely affects function if greater than 10mm. When using the direct anterior approach (DAA), limb length control is considered easier with a standard operating table than with a traction table. However, this assumption has not been confirmed. More specifically, no studies have used EOS imaging, which is currently the reference for assessing limb length. The objectives of this retrospective study were: (1) to use EOS imaging to determine whether THA via the DAA on a standard table allowed satisfactory limb length control; (2) whether LLD was associated with other parameters such as age, gender, body mass index (BMI), or side; and (3) to compare clinical score values between patients with and without LLD.

HYPOTHESIS

The DAA without a traction table allows satisfactory limb length control as assessed using 3D EOS imaging.

MATERIAL AND METHODS

This retrospective descriptive study included 56 patients who underwent primary THA via the DAA between March 2013 and June 2014. LLD was measured on pre- and post-operative EOS images, using sterEOS™ 3D software. Age, gender, BMI, and side of THA were collected. The 12-item Short Form score, Harris Hip Score, and Postel-Merle d'Aubigné score were determined to look for radio-clinical correlations.

RESULTS

Of the 56 patients, 15 (26.8%) had an LLD >10mm before THA and 12 (21.4%) after THA. Limb length equality was restored in 7 patients with 1 with a shorter and 1 with a longer limb before THA. In 5 patients with equal limb length before THA, the operated limb was lengthened after THA, by a mean of 8.92mm (range, 5.8-10.8mm). Thus, in all, 5/56 (8.9%) patients experienced a detrimental change in limb length due to the surgery. No statistically significant differences were found between patients with and without LLD regarding age, gender, BMI, side, or clinical scores.

DISCUSSION

Although the frequency of LLD after THA in our study was consistent with earlier reports, our results show that good limb length control can be obtained via the DAA with a standard operating table. Thus, 7 of the 11 patients with a shorter limb and 1 of 4 with a longer limb before THA had equal limb lengths after THA, and only 8.9% of patients experienced a detrimental increase in limb length after THA. The DAA without a traction table allows satisfactory intra-operative limb length control based on visualisation of anatomical landmarks (antero-superior iliac spines and medial malleoli). This technique is therefore valuable for limiting the risk of LLD. When combined with 3D EOS planning, it may increase the accuracy of limb length adjustment.

LEVEL OF EVIDENCE

IV, retrospective study with no control group.

The Utilization of Metal Augments Allows Better Biomechanical Reconstruction of the Hip in Revision Total Hip Arthroplasty With Severe Acetabular Defects: A Comparative Study

BACKGROUND

Reconstructing the normal hip biomechanics is important for a successful revision total hip arthroplasty (THA). Little is known about whether using metal augments in revision THA is biomechanically superior to traditional techniques.

METHODS

A retrospective review was conducted on 74 consecutive THAs revised using metal augments with a cementless hemispherical cup and 77 consecutive THAs revised using the jumbo cup, all with a minimum 2-year follow-up. Biomechanical parameters were measured before and immediately after the revision. Radiological and clinical outcomes at follow-ups were also evaluated.

RESULTS

The metal augment group had a reconstructed center of rotation (COR) that was 6.5 mm closer to the anatomic COR in height (P < .001), had 3.6 m smaller cup size (P < .001), and had 5.7 mm less head-cup difference (P < .001). Moreover, there was a reconstructed COR that was much closer to the anatomic COR (vertical distance: 1.8 vs 14.1 mm, P < .001; horizontal distance: -2.1 vs 7.9 mm, P = .013), had 4.1 mm greater femoral offset (P = .006), and had 8 mm less leg length discrepancy (P = .035) in the subgroup of Paprosky type III bone defects when compared to the jumbo cup group. All cup-augment constructs were radiologically stable with a higher mean postoperative Harris Hip Score (P = .012). One jumbo cup was radiologically unstable.

CONCLUSION

In revision THA, utilizing metal augments helps to restore the COR position more precisely, avoid using a larger cup, reduce head-cup difference, rebuild femoral offset, and decrease leg length discrepancy, particularly with Paprosky type III bone defects. Moreover, it provides satisfactory radiological and clinical outcomes in the short term.

Comparison of collum femoris-preserving stems and ribbed stems in primary total hip arthroplasty

Background

This retrospective study investigated the relative benefits of using a collum femoris-preserving prosthesis or ribbed stem during total hip arthroplasty (THA).

Methods

The clinical results were compared of patients who underwent THA, between January 2010 and December 2012, with either a CFP prosthesis or a ribbed stem (66 and 75 patients, respectively, aged 43.4 ± 10.8 and 42.3 ± 9.8 years). Patients were assessed using the Harris Hip Score (HHS), Western Ontario and McMaster University Osteoarthritis Index (WOMAC), 12-Item Short Form Health Survey (SF-12), and physical component summary (PCS) score. Intraoperative and postoperative complications and leg-length differences were noted.

Results

The mean follow-up times of the CFP and ribbed groups were 67.2 ± 7.5 and 68.3 ± 7.2 months, respectively. The HHS, SF-12 MCS, SF-12 PCS, and WOMAC scores of the two groups were similar. The rates of periprosthetic femoral fractures and leg-length differences > 10 mm in the CFP group (10.6% and 13.6%, respectively) were significantly higher than those in the ribbed group (1.3% and 2.7%). The groups were similar regarding complications of osteolysis, ectopic ossification, dislocation, deep infection, deep venous thrombosis, thigh pain, and aseptic loosening. The survival rates of the CFP and ribbed groups were comparable (98.5% and 97.8%).

Conclusion

The clinical results of the CFP and ribbed prostheses in young patients given THA were similar for Chinese patients. However, the CFP stem should be used with caution, given the high incidence of technical problems associated with implantation especially for Chinese patients.

Measurement of Patient's Perception on Limb-Length Discrepancy Compared With Weight-Bearing Orthoroentgenography in Total Hip Arthroplasty: A Prospective Study

BACKGROUND

Aims of this study included providing a comparison of the measurement of limb-length discrepancy after primary total hip arthroplasty between patient's perception and weight-bearing orthoroentgenographic measurement. A comparison between patient's perception and pelvic radiographic measurement was examined as well.

METHODS

This prospective study comprised patients who had already undergone total hip arthroplasty and were receiving postoperative outpatient care between April 2017 and July 2017. Block test was used to assess patient's perception on limb-length discrepancy. Weight-bearing orthoroentgenography and pelvic radiography were used for radiographic measurement. These 3 measurements were compared to find the difference, correlation, and reliability.

RESULTS

Evaluations were carried out on 68 patients subsequent to primary total hip arthroplasty. The prevalence of limb-length discrepancy by orthoroentgenographic, patient's perception, and pelvic radiographic measurements was 60%, 57.35%, and 52.94%, respectively. Mean difference of limb-length discrepancy between the 3 measurements were not statistically significant. When compared with orthoroentgenography, sensitivity and specificity of patient's perception measurement were 60.98% and 48.15%, respectively. Likewise, sensitivity and specificity of pelvic radiographic measurement were 78.05% and 85.19%, respectively. Poor correlation and reliability were found between orthoroentgenographic and patient's perception measurement (concordance correlation coefficient = 0.21, intraclass correlation coefficient = 0.22). However, good correlation and reliability were found between orthoroentgenographic and pelvic radiographic measurement (concordance correlation coefficient = 0.85, intraclass correlation coefficient = 0.85).

CONCLUSION

Patient's perception on limb-length discrepancy had poor correlation and reliability, low sensitivity and specificity when compared with orthoroentgenographic measurement. A physician should additionally perform measurement by orthoroentgenography or pelvic radiography.

Additive Influence of Hip Offset and Leg Length Reconstruction on Postoperative Improvement in Clinical Outcome After Total Hip Arthroplasty

BACKGROUND

There is a lack of prospective studies investigating the additive effect of both acetabular and femoral reconstruction parameters on the functional outcome following total hip arthroplasty (THA).

METHODS

The aim of this prospective cohort study was to determine the combined influence of hip geometry reconstruction and component positioning on the clinical outcome following primary THA for unilateral osteoarthritis. We prospectively assessed the clinical outcome and radiographic parameters for hip geometry reconstruction, component position, and orientation using validated measurements for the operated hip compared to the contralateral native hip in a consecutive series of 113 patients with primary unilateral cementless THA. The correlation of reconstruction parameters was investigated using a multivariate polynomial regression model for the dependent variable ΔHHS (difference between the Harris hip scores preoperatively and 2.0-4.8 years postoperatively). Target zones for hip reconstruction and component positioning were investigated for an association with superior clinical outcome.

RESULTS

The regression model demonstrated a significant correlation for the ΔHHS and both hip offset (HO) reconstruction and leg length difference. Patients with accurate to slightly increased HO reconstruction combined with balanced leg length demonstrated a significantly higher ΔHHS than patients outside this zone (HO: 5 ± 5 and LLD: 0 ±5 mm, P = .029). This finding could be confirmed for 2 enlarged zones (zone 1: HO, 7.5 ± 7.5 and LLD, 2.5 ± 7.5 mm, P = .028; zone 2: HO, 7.5 ± 7.5 and LLD, 7.5 ± 7.5 mm, P = .007).

CONCLUSION

HO and leg length reconstruction demonstrated an additive effect on clinical outcome and surgeons should aim for high accuracy in the reconstruction of both factors.

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.

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.

Effect of Preoperative Leg Length Discrepancy on Functional Outcome and Patient Satisfaction After Total Hip Arthroplasty in Cases of Osteonecrosis of the Femoral Head

BACKGROUND

Severe preoperative leg length discrepancy (LLD) can lead to poor preoperative functional status in patients with extensive osteonecrosis of the femoral head (ONFH). This study aimed to assess the effect of preoperative LLD on functional outcomes and patient satisfaction post-total hip arthroplasty (THA) in ONFH patients.

METHODS

Twenty-two patients with severe LLD (≥15 mm) and 44 patients with mild LLD (<15 mm) on preoperative radiographs were enrolled as the study group and control group, respectively. All 66 patients were diagnosed with unilateral ONFH. Patients' functional outcomes (Harris Hip Score [HHS], Oxford Hip Score [OHS], patient-perceived LLD, Visual Analogue Scale [VAS] pain score, and Limping Assessment]) and satisfaction (self-administered patient satisfaction scale) were evaluated at 3 and 12 months after THA.

RESULTS

At 3 months after THA, the study group had poorer outcomes in terms of the HHS (P = .002) and OHS (P = .002), a higher prevalence of patient-perceived LLD (P = .002), and worse limping (P < .001) than the control group, but the self-administered patient satisfaction scale and VAS pain scores did not differ. However, improvements in the HHS and OHS from preoperative assessment to 3 months were comparable in both groups. At 12 months after THA, there were no significant differences in functional outcomes or self-satisfaction, and the study group showed significantly greater improvements from preoperative assessment to 12 months (P < .05).

CONCLUSION

Patients with severe LLD experienced similar improvement at 3 months after THA as those with mild LLD in terms of the HHS and OHS but showed greater improvement at 12 months postoperatively than patients with mild LLD.

Leg length discrepancy in computer navigated total hip arthroplasty - how accurate are we?

INTRODUCTION

The success of total hip arthroplasty (THA) depends on the restoration of 2 important parameters - hip offset and leg length. Leg length discrepancy (LLD) after THA is associated with back pain, gait disorder, general patient dissatisfaction and aseptic loosening. Hence it is of utmost importance to minimise LLD.

METHODS

This is a retrospective study where we compared the reproduction of leg lengths between navigated THA group (152 patients) and nonnavigated THA group (57 patients). The leg lengths were measured radiologically using Ranawat technique on AP pelvic radiograph.

RESULTS

In the navigated group, the leg lengths of the reconstructed hips were restored to within 6 mm of the opposite leg in 146 patients (96.05%) while 6 patients (3.94%) had LLD of more than 6 mm. In the nonnavigated group, 29 patients (51%) had their leg lengths restored within 6 mm of the opposite leg while the remaining 28 patients (49%) had their LLD greater than 6 mm. Statistical analysis of the 2 pairs of LLD measurements (navigated hip and nonnavigated group) using Mann-Whitney U-test revealed significant difference between these two groups (p&lt;0.001).

CONCLUSIONS

Based on our results we conclude that computer navigation is an excellent tool to facilitate the successful reproduction of leg length in THA.

Patrick-Patel R, MacDonald D, Breusch SJ. Total hip replacement: increasing femoral offset improves functional outcome

INTRODUCTION

The aim of this study was to assess the independent effect of radiographic measures of implant position, relative to pre-operative anatomical assessment, on the functional outcome of total hip arthroplasty according to change in the Oxford hip score (OHS) 1 year post surgery.

METHODS

A prospective cohort study was preformed to assess whether improvement in functional outcome (change in OHS at 1 year) and the relationship with femoral offset and length, and acetabular offset and height. After a power calculation 359 patients were recruited to the study and radiographic measures were performed by blinded observers. Regression analysis was used to assess the independent effect of the four radiographic measurements after adjusting for confounding variables.

RESULTS

There was a significant (p < 0.001) decrease in acetabular offset [5.3 mm, 95 % confidence interval (CI) 4.4-6.2] and increase in femoral offset (6.1 mm, 95 % CI 5.4-6.8). Hence there was no significant change in overall offset. Femoral offset was the only radiographic measure to be achieved statistical significance (r = 0.198, 95 % CI 0.063-0.333, p = 0.004) in relation to clinical outcome, with increasing offset being associated with a greater improvement in the OHS. On combining femoral and acetabular offset increasing offset was associated with a greater improvement in the OHS (r = 0.10, 95 % CI 0.01-0.19, p = 0.04).

CONCLUSION

This study supports the long-held biomechanical theory of medialisation of the acetabular component with compensatory increased femoral offset results in improved functional outcome.

Depression and anxiety before and after limb length discrepancy correction in patients with unilateral developmental dysplasia of the hip

OBJECTIVE

Limb length discrepancy (LLD) is common in patients with developmental dysplasia of the hip (DDH) and may influence the psychological status of these patients. The present study aims to investigate depression and anxiety in DDH patients with different extents of LLD and to assess the effect of LLD correction on these two psychological factors.

METHODS

161 patients with DDH were recruited and divided into two groups based on whether they could perceive LLD preoperatively. The patients who could not perceive LLD were assigned to group N, and those who could perceive LLD were assigned to group P. Depression/anxiety, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores and LLD were assessed one week before, six months and two years after total hip arthroplasty (THA).

RESULTS

Depression and anxiety were significantly higher in group P patients compared to group N patients. The patients in group N presented significant improvement in depression and anxiety six months after arthroplasty, while DDH patients in group P did two years after arthroplasty. Correlation analyses revealed their improvement was associated with pain relief and improved hip function in both groups of patients and was also related to changes in the perception of LLD in group P patients.

CONCLUSIONS

Depression and anxiety levels were higher in DDH patients with perceived LLD. Their improvement was related to pain relief and improved hip function following THA. In DDH patients with perceived LLD, a change in the perception of LLD also played a part in their improvement.

Comparison of Acetabular Bone Resection, Offset, Leg Length and Post Operative Function Between Hip Resurfacing Arthroplasty and Total Hip Arthroplasty

Controversy exists regarding the amount of acetabular bone resection, biomechanics and function of patients receiving either total hip arthroplasty (THA) or hip resurfacing arthroplasty (HRA). A cohort of patients undergoing 36 mm ceramic-on-ceramic THA (89) or metal-on-metal HRA (86) were compared. No difference was observed when the ratio of native femoral head size was compared to the implanted acetabular component size (1.15 ± 0.1 HRA c.f. 1.13 ± 0.1 THA). No difference was observed in acetabular offset, vertical centre of rotation or function (OHS mean 47 in both groups) but leg length discrepancy (1.8 mm c.f. 5.5 mm) and femoral offset did differ (0.6 mm c.f. 4.1 mm). This demonstrates that 36 mm ceramic-on-ceramic THA is not associated with more bone resection than HRA and achieves equivalent function whilst avoiding the problems of metal-on-metal bearings.

The Influence of Leg Length Discrepancy after Total Hip Arthroplasty on Function and Quality of Life: A Prospective Cohort Study

We investigated whether patients with lengthening (> 9 mm), restoration (between 9 mm lengthening and 5 mm shortening) or shortening (> 5 mm) of the operated leg after total hip arthroplasty (THA) had different function (WOMAC score), quality of life (EQ-5D), residual hip pain, use of shoe lift and walking aid and leg length discrepancy (LLD) awareness, 12-15 months postoperatively. All patients had a significant postoperative improvement in WOMAC and EQ-5D regardless the LLD. However, the lengthening group showed less improvement in WOMAC, more use of shoe lift, residual hip pain and LLD awareness compared with the other two groups. No differences in EQ-5D were found. In spite of the improvement in function and quality of life, lengthening had adverse effects and should therefore be avoided.

The Exeter technique can lead to a lower incidence of leg-length discrepancy after total hip arthroplasty

We evaluated an operative technique, described by the Exeter Hip Unit, to assist accurate introduction of the femoral component. We assessed whether it led to a reduction in the rate of leg-length discrepancy after total hip arthroplasty (THA). A total of 100 patients undergoing THA were studied retrospectively; 50 were undertaken using the test method and 50 using conventional methods as a control group. The groups were matched with respect to patient demographics and the grade of surgeon. Three observers measured the depth of placement of the femoral component on post-operative radiographs and measured the length of the legs. There was a strong correlation between the depth of insertion of the femoral component and the templated depth in the test group (R = 0.92), suggesting accuracy of the technique. The mean leg-length discrepancy was 5.1 mm (0.6 to 21.4) pre-operatively and 1.3 mm (0.2 to 9.3) post-operatively. There was no difference between Consultants and Registrars as primary surgeons. Agreement between the templated and post-operative depth of insertion was associated with reduced post-operative leg-length discrepancy. The intra-class coefficient was R ≥ 0.88 for all measurements, indicating high observer agreement. The post-operative leg-length discrepancy was significantly lower in the test group (1.3 mm) compared with the control group (6.3 mm, p < 0.001). The Exeter technique is reproducible and leads to a lower incidence of leg-length discrepancy after THA.

Modular tapered implants for severe femoral bone loss in THA: reliable osseointegration but frequent complications

BACKGROUND

Modular tapered stems have been suggested as the optimal implants for patients with severe femoral bone loss (Paprosky Type IIIB and IV) undergoing revision total hip arthroplasty (THA); however, there are few data describing survivorship and hip scores associated with this treatment.

QUESTIONS/PURPOSES

At minimum 2 years, we sought to determine the (1) survivorship of these implants; (2) radiographic evidence of osseointegration; and (3) the Harris hip scores of patients revised with a modular tapered stem for severe femoral bone loss including the complications associated with their use.

METHODS

Between 1999 and 2010, we performed 1124 femoral revisions; of those, 135 (12%) were performed using a modular tapered stem. General indications for use of this device included bone loss, poor quality bone, leg length discrepancy, difficulty adjusting version, proximal femoral remodeling, and ectatic medullary canals in the setting of revision THA. This report reviewed 70 of those that were performed in Type IIIB and IV femurs. Of those 70 patients, 11 had died and one was lost before 2-year followup; the remaining 58 (83%, 33 with a Type IIIB femur and 25 with a Type IV femur) were followed for a minimum of 24 months (average, 67 months; range, 24-151 months). Survivorship free from revision, radiographic analysis for signs of subsidence or stem loosening, and Harris hip scores were tallied.

RESULTS

One patient underwent stem revision for early subsidence followed by failure of ingrowth for a survivorship free from repeat revision of 98% (57 of 58 patients). Five other stems (for a total of six [10%]) subsided early but nonetheless achieved radiographic signs of ingrowth and were not revised again. All other stems demonstrated osseointegration without subsidence and remained radiographically well fixed. In patients with surviving implants, the mean Harris hip score improved from 34 (range, 11-49) preoperatively to 74 (range, 14-100; p<0.001) postoperatively. Overall, 15 of 58 patients (26%) experienced a complication, of whom 10 (17%) underwent reoperation.

CONCLUSIONS

We found that modular tapered stems resulted in 98% survivorship at a mean of 67 months in patients with Type IIIB and IV femurs undergoing femoral revision, although the overall complication rate in this complex subset of patients is high.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.