Radiographic analysis of the restoration of hip joint center following open reduction and internal fixation of acetabular fractures: a retrospective cohort study

Cup-Cage Construct for Treatment of Severe Acetabular Bone Loss in Revision Total Hip Arthroplasty: Clinical and Radiographic Outcomes at a Mean Follow-Up of 7.7 Years

BACKGROUND

Acetabular reconstruction in the context of massive acetabular bone loss is challenging. Achieving implant stability in these situations requires special considerations due to inadequate bone stock around the acetabulum. The cup-cage construct is a treatment option that addresses this issue. This study evaluates survivorship, complications, and functional outcomes using the cup-cage construct.

METHODS

A total of 131 cup-cage implants (129 patients) were identified from our retrospective review of revision total hip arthroplasties from January 2003 to January 2022. Among these cases, 100 (76.3%) were women, the mean age at the time of surgery was 68 years (range, 29 to 92; SD [standard deviation], 12.4), and the mean follow-up was 7.7 years (range, 0.02 to 20.3; SD, 5.1). Kaplan-Meier survivorship analysis was conducted with failure defined as revision surgery and/or failure of the cup-cage reconstruction.

RESULTS

At a mean follow-up of 7.7 years, the cup-cage construct survivorship due to all-cause failure was 83.9% (95% CI [confidence interval]: 77.6 to 90.2) at 5 years with 88 hips at risk, 74.8% (95% CI: 66.2 to 83.4) at 10 years with 38 hips at risk, and 69.8% (95% CI: 59.4 to 80.2) at 15 years with 11 hips at risk. The survivorship due to failure from aseptic loosening was 96.7% (95% CI: 93.6 to 99.8) at 5 years with 88 hips at risk and 95.5% (95% CI: 91.6 to 99.4) at 10 and 15 years with 38 and 11 hips at risk, respectively. The revision rate for aseptic loosening of the cup and/or cage, infection, dislocation, and aseptic loosening of the femoral stem was 5 of 131 (3.8%), 12 of 131 (9.1%), 10 of 131 (7.6%), and 2 of 131 (1.5%). The mean Leg length discrepancy (LLD) improved from 12.2 to 3.9 mm (P < 0.001).

CONCLUSION

The cup-cage construct is a reliable treatment option for the treatment of various acetabular defects. There are favorable survivorship, clinical, and radiographic outcomes, with a satisfactory complication rate.

Cup-cage constructs in revision total hip arthroplasty for pelvic discontinuity

Aims

Pelvic discontinuity is a challenging acetabular defect without a consensus on surgical management. Cup-cage reconstruction is an increasingly used treatment strategy. The present study evaluated implant survival, clinical and radiological outcomes, and complications associated with the cup-cage construct.

Methods

We included 53 cup-cage construct (51 patients) implants used for hip revision procedures for pelvic discontinuity between January 2003 and January 2022 in this retrospective review. Mean age at surgery was 71.8 years (50.0 to 92.0; SD 10.3), 43/53 (81.1%) were female, and mean follow-up was 6.4 years (0.02 to 20.0; SD 4.6). Patients were implanted with a Trabecular Metal Revision Shell with either a ZCA cage (n = 12) or a TMARS cage (n = 40, all Zimmer Biomet). Pelvic discontinuity was diagnosed on preoperative radiographs and/or intraoperatively. Kaplan-Meier survival analysis was performed, with failure defined as revision of the cup-cage reconstruction.

Results

The five-year all-cause survival for cup-cage reconstruction was 73.4% (95% confidence interval (CI) 61.4 to 85.4), while the ten- and 15-year survival was 63.7% (95% CI 46.8 to 80.6). Survival due to aseptic loosening was 93.4% (95% CI 86.2 to 100.0) at five, ten, and 15 years. The rate of revision for aseptic loosening, infection, and dislocation was 3/53 (5.7%), 7/53 (13.2%), and 6/53 (11.3%), respectively. The mean leg length discrepancy improved (p < 0.001) preoperatively from a mean of 18.2 mm (0 to 80; SD 15.8) to 7.0 mm (0 to 35; SD 9.8) at latest follow-up. The horizontal and vertical hip centres improved (p < 0.001) preoperatively from a mean of 9.2 cm (5.6 to 17.5; SD 2.3) to 10.1 cm (6.2 to 13.4; SD 2.1) and 9.3 cm (4.7 to 15.8; SD 2.5) to 8.0 cm (3.7 to 12.3; SD 1.7), respectively.

Conclusion

Cup-cage reconstruction provides acceptable outcomes in the management of pelvic discontinuity. One in four constructs undergo revision within five years, most commonly for periprosthetic joint infection, dislocation, or aseptic loosening.

A Novel Digital Templating Method for Total Hip Arthroplasty in Patients With Unilateral Hip Arthrosis

BACKGROUND

Identification of the hip center of rotation (HCOR) before total hip arthroplasty (THA) is crucial for achieving optimal implant position and size, and for restoring native biomechanics around the hip joint. Current techniques for determining the HCOR in cases of abnormal hip anatomy are limited and unreliable. This study presents a novel technique using open-access software for preoperative THA templating for patients with significantly abnormal hip anatomy due to unilateral hip arthrosis. The aim is to reliably predict the HCOR and acetabular implant size compared with a traditional intraoperative method.

MATERIALS AND METHODS

This retrospective study involved 20 patients with unilateral hip arthrosis who underwent THA. Preoperative templating was performed using the experimental technique, and the position of the HCOR was measured on preoperative and postoperative radiographs. The positions of the predicted and actual HCOR were compared, along with the inclination and size of the acetabular component.

RESULTS

The difference between the predicted and actual HCOR positions was insignificant (0.43±0.22 mm vertically and 0.18±0.20 mm horizontally), and there was a positive correlation between them (r=0.78, P<.005; r=0.72, P<.005). The agreement between the predicted and actual acetabular implant sizes was 85%, with near-perfect interobserver agreement (Cohen's kappa=0.827).

CONCLUSION

This novel technique provides a reliable method for predicting HCOR and acetabular implant size for THA in cases of unilateral hip arthrosis. This technique may help optimize biomechanics and improve outcomes in challenging cases. Further research and validation are warranted to establish its broader applicability. [Orthopedics. 2024;47(3):e139-e145.].

The value of digital 3D models in evaluating surgical outcomes using the uninjured contralateral acetabulum after acetabular fracture repair

BACKGROUND

Currently, assessment of acetabular fracture reduction is mainly performed by evaluating 2D slices of 3D CT scans. This subjective method can potentially be improved by using 3D models and objective analysis tools. In order to evaluate the potential value of digital 3D reconstructed models in the assessment of acetabular fracture reduction, 3D reconstructions of the fractured acetabulum were compared to the mirrored healthy contralateral side for both the pre-, and post-surgical setting.

METHODS

Thirteen patients with one-sided acetabular fractures were included in the study. All patients received a pre-, and postoperative CT scan. The similarity between the healthy acetabulum and the contralateral fractured acetabulum was determined by two observers for both the pre-, and postoperative setting by completing the following four steps; (1) mirroring of the fractured acetabulum, (2) initial manual alignment of this mirrored 3D model to the contralateral version, (3) surface-based matching (iterative closest point registration) using the acetabular cartilage surface, and (4) calculating the surface distances between affected and healthy acetabular 3D models. Descriptive statistics showed the surface distance between pre-, and post-surgical reduction, as well as the interobserver variability.

RESULTS

A total of 13 patients with an acetabular fracture were included; 11 males and 2 females with a mean ± SD age of 55.6 ± 14.7 years. Digital mirroring of the fractured acetabula to the healthy acetabula was successful for both preoperative and postoperative situations in all patients. The median distance between both fractured and mirrored healthy contralateral acetabula was significantly larger (p<0.01) for the preoperative group (2.21 mm (interquartile range (IQR): 1.30 mm)) compared to the postoperative group (0.93 mm (IQR: 0.59 mm)). The median distance deviation was not significantly different (p = 0.96) between observers.

CONCLUSIONS

The results of comparing 3D model of fractured acetabula with the contra-lateral healthy acetabula before, and after surgical repair indicate that this method can be a suitable tool to objectively assess acetabular fracture reduction. Further research is needed to confirm the usefulness to predict future arthrosis after surgical repair.

Patients with combined pelvic and spinal injuries have worse clinical and operative outcomes than patients with isolated pelvic injuries analysis of the German Pelvic Registry

Background

Pelvic fractures are often associated with spine injury in polytrauma patients. This study aimed to determine whether concomitant spine injury influence the surgical outcome of pelvic fracture.

Methods

We performed a retrospective analysis of data of patients registered in the German Pelvic Registry between January 2003 and December 2017. Clinical characteristics, surgical parameters, and outcomes were compared between patients with isolated pelvic fracture (group A) and patients with pelvic fracture plus spine injury (group B). We also compared apart patients with isolated acetabular fracture (group C) versus patients with acetabular fracture plus spine injury (group D).

Results

Surgery for pelvic fracture was significantly more common in group B than in group A (38.3% vs. 36.6%; p = 0.0002), as also emergency pelvic stabilizations (9.5% vs. 6.7%; p < 0.0001). The mean time to emergency stabilization was longer in group B (137 ± 106 min vs. 113 ± 97 min; p < 0.0001), as well as the mean time until definitive stabilization of the pelvic fracture (7.3 ± 4 days vs. 5.4 ± 8.0 days; p = 0.147). The mean duration of treatment and the morbidity and mortality rates were all significantly higher in group B (p < 0.0001). Operation time was significantly shorter in group C than in group D (176 ± 81 min vs. 203 ± 119 min, p < 0.0001). Intraoperative blood loss was not significantly different between the two groups with acetabular injuries. Although preoperative acetabular fracture dislocation was slightly less common in group D, postoperative fracture dislocation was slightly more common. The distribution of Matta grades was significantly different between the two groups. Patients with isolated acetabular injuries were significantly less likely to have neurological deficit at discharge (94.5%; p < 0.0001). In-hospital complications were more common in patients with combined spine plus pelvic injuries (groups B and D) than in patients with isolated pelvic and acetabular injury (groups A and C).

Conclusions

Delaying definitive surgical treatment of pelvic fractures due to spinal cord injury appears to have a negative impact on the outcome of pelvic fractures, especially on the quality of reduction of acetabular fractures.

Outcome After Open Reduction Internal Fixation of Acetabular Fractures in the Elderly

OBJECTIVES

(1) Assess outcomes of acetabular open reduction and internal fixation (ORIF) in the elderly, (2) investigate factors influencing outcome, and (3) compare outcomes after low-energy and high-energy mechanisms of injury.

DESIGN

Retrospective case series.

SETTING

Level 1 trauma center.

PATIENTS

Seventy-eight patients older than 60 years (age: 70.1 ± 7.4; 73.1% males).

INTERVENTION

ORIF for acetabular fractures.

MAIN OUTCOME MEASUREMENTS

Complications, reoperation rates, Oxford Hip Score (OHS), and joint preservation and development of symptomatic osteoarthritis. Cases with osteoarthritis, OHS < 34, and those who required subsequent total hip arthroplasty were considered as poor outcome.

RESULTS

At a mean follow-up of 4.3 ± 3.7 years, 11 cases post-ORIF required a total hip arthroplasty. The 7-year joint survival post-ORIF was 80.7 ± 5.7%. Considering poor outcome as failure, the 7-year joint survival was 67.0 ± 8.9%. The grade of reduction was the most significant factor associated with outcome post-ORIF. Female sex (P = 0.03), pre-existing osteoporosis (P = 0.03), low-energy trauma (P = 0.04), and Matta grade (P = 0.002) were associated with poor outcome. Patients with associated both-column fractures were more likely to have nonanatomic reduction (P = 0.008). After low-energy trauma, joint survivorship was 36.6 ± 13.5% at 7 years compared with 75.4 ± 7.4% in the high-energy group when considering poor outcome as an end point (log rank P = 0.006). The cohort's mean OHS was 37.9 ± 9.3 (17-48).

CONCLUSIONS

We recommend ORIF whenever an anatomic reduction is feasible. However, achievement and maintenance of anatomic reduction are a challenge in the elderly, specifically in those with low-energy fractures involving both columns, prompting consideration for alternative management strategies.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Total hip arthroplasty for failed acetabular fracture: a double-center comparative study on failed proximal femur fracture

PURPOSE

This study aimed to compare the clinical and radiological outcomes of patients who underwent total hip arthroplasty (THA) after failed osteosynthesis of acetabular fractures vs. fractures of the proximal femur.

METHODS

This is a retrospective comparative study in two centers. A total of 110 patients who underwent THA after osteosynthesis of acetabular or proximal femur fractures were categorized into groups: group 1 (53 patients with acetabular fracture) and group 2 (57 patients with proximal femur fracture). The mean follow-up period was 6.3 (range 2-16.5) years. The Harris hip scores (HHSs), complications, radiological results, and Kaplan-Meier survival curves were evaluated.

RESULTS

The mean preoperative HHSs of 39.4 (group 1) and 41.2 (group 2) were improved to 83.6 and 84.7 at the final follow-up (p < 0.001 and p < 0.001, respectively). There were two cases of aseptic cup loosening, two cases of septic cup loosening, two cases of deep infection, two cases of dislocation, two cases of sciatic nerve palsy, and one case of periprosthetic fracture in group 1, and one case of dislocation and two cases of infection in group 2, which showed a statistical difference in complication rate (p = 0.021). Total cup migration was significantly higher in group 1 (p = 0.015). After a mean follow-up period of 6.3 years, the survival rate was significantly lower in group 1 (69.4% vs. 97.1%, p = 0.015).

CONCLUSION

THA following osteosynthesis of acetabular fracture showed poorer survival, higher complication rate, and higher migration of the acetabular cup than THA following osteosynthesis of proximal femur fracture.

Exploring partial intrinsic and extrinsic symmetry in 3D medical imaging

We present a novel methodology to detect imperfect bilateral symmetry in CT of human anatomy. In this paper, the structurally symmetric nature of the pelvic bone is explored and is used to provide interventional image augmentation for treatment of unilateral fractures in patients with traumatic injuries. The mathematical basis of our solution is based on the incorporation of attributes and characteristics that satisfy the properties of intrinsic and extrinsic symmetry and are robust to outliers. In the first step, feature points that satisfy intrinsic symmetry are automatically detected in the Möbius space defined on the CT data. These features are then pruned via a two-stage RANSAC to attain correspondences that satisfy also the extrinsic symmetry. Then, a disparity function based on Tukey's biweight robust estimator is introduced and minimized to identify a symmetry plane parametrization that yields maximum contralateral similarity. Finally, a novel regularization term is introduced to enhance similarity between bone density histograms across the partial symmetry plane, relying on the important biological observation that, even if injured, the dislocated bone segments remain within the body. Our extensive evaluations on various cases of common fracture types demonstrate the validity of the novel concepts and the accuracy of the proposed method.

Efficacy of total hip arthroplasty after operatively treated acetabular fracture

INTRODUCTION

We evaluated the clinical and radiological outcomes of patients following total hip arthroplasty (THA) for acetabular fracture.

MATERIALS AND METHODS

This was a retrospective cohort study in a single center. The medical records of patients who underwent THA from March 2002 to March 2017 were reviewed. Inclusion criteria were THA and a history of open reduction and internal fixation of acetabular fractures. Thirty-seven patients with a mean age of 56.2 years were enrolled. The Harris hip score (HHS), acetabular fracture classification, time interval between acetabular fracture and THA, cause of THA, surgical approach, implant type, complications, radiographic results, and Kaplan-Meier survival curves were analyzed.

RESULTS

All patients were followed up for an average of 6.6 years. The mean preoperative HHS of 42.5 had improved to 83.5 at the final follow-up (p < 0.05). There were 29 cases of post-traumatic arthritis, 6 cases of avascular necrosis, and 4 cases of non-union. The average interval from injury to THA was 58 months (range 4-336 months). The re-admission rate was 18.9%. Patients who underwent conversion to THA due to post-traumatic arthritis combined with non-union acetabular fracture developed clinical failure more frequently than patients with post-traumatic arthritis (p = 0.037). At 12 years, 83.4% of patients were free from revision of femoral and acetabular components.

CONCLUSION

THA secondary to an operatively treated acetabular fracture provides good symptomatic relief, but shows relatively inferior survival rates, and clinical failure was related to post-traumatic arthritis with acetabular non-union.

The value of 3D reconstructions in determining post-operative reduction in acetabular fractures: a pilot study

Background

In patients with acetabular fractures, the reconstructed three-dimensional (3D) model of the contralateral acetabulum could be used as a mirrored template for the anatomical configuration of the affected joint. This has not been validated.

Objective

To investigate whether the right and left acetabula, as reconstructed 3D models, are valid mirrored duplicates that can be used as a reference model for the contralateral side.

Methods

CT scans of twenty patients with unaffected acetabula were used. The symmetry of the generated 3D models was evaluated through: (1) mirroring of the acetabulum; (2) initial rough matching; (3) automatic optimisation of the matching via surface-based matching; (4) calculation of distances between surfaces by evaluating the Euclidean (straight-line) error distance between the closest points between left and right. The percentages of surface points of the left and right acetabulum with a distance smaller than 0.5, 1.0, 1.5 and 2.0 mm were calculated and evaluated, in relation to Matta’s criteria, for acetabular fracture reductions.

Results

The mean distance deviation was less than 0.75 mm in all 40 comparisons. The calculated distances in 90.7% of the surface points of the left and right acetabulum were below the tolerance threshold of 1.0 mm, based on Matta’s anatomical reduction criteria, and 98.7% of the surface points scored below Matta’s imperfect tolerance threshold of 2.0 mm.

Conclusion

This study demonstrates 3D reconstructed models of healthy left and right acetabula are highly similar and could potentially be used as mirrored duplicates. The next step will be to investigate these results in patients with reduced acetabular fractures.

Single versus double column fixation in transverse fractures of the acetabulum: A randomised controlled trial

INTRODUCTION

Biomechanical studies have compared fixation methods in transverse acetabular fractures, yet there is not enough clinical data to suggest an optimal fixation method. The aim of this randomized controlled trail was to compare fracture stability in posterior plating alone versus posterior plating and anterior column lag-screw fixation in treatment of transverse and transverse with posterior wall acetabular fractures.

METHODS

Thirty patients were randomized to one of two groups, either posterior fixation alone (single column group), or posterior plating and anterior fixation with percutaneous anterior column screw (double column group). Patients were followed up with serial radiographic assessments documenting any loss of reduction, utilizing Matta's radiological criteria, measuring the roof arc angles and by measuring any change in the femoral head offset.

RESULTS

Fifteen patients were randomized to each group. Mean patient age was 31 years, mean follow up period was 19 months (range 12-24). There was no significant differences between the two groups with regards the quality of post-operative reduction, blood loss, hospital stay and functional score using the modified Merle D'Aubinge and Postel score. The operative time was significantly longer in the double column fixation group (130 min versus 104 min). There was no loss of reduction observed in either of the two groups.

CONCLUSION

Single poster column fixation in transverse and transverse posterior wall fractures showed similar result to double column fixation, in terms of fractures stability in the follow up period, quality of reduction and early functional outcome.

Learning Curve for Surgical Treatment of Acetabular Fractures: A Retrospective Clinical Study of a Practical and Theoretical Training Course

Background

Surgical treatment of acetabular fracture and the anatomic reconstruction of the hip joint are difficult to achieve due to the complex pelvic anatomy, and surgical training requires a prolonged and steep learning curve. The aim of this study was to evaluate the effects of an applied training course, including cadaveric dissection, for the surgical treatment of acetabular fractures.

Material/Methods

This retrospective study included 35 patients who underwent surgical treatment for acetabulum fractures between 2012–2016. Patients were divided into three groups during two training courses, for the first two years and second two years. The surgical treatment was performed through single or combined standard approaches, according to the fracture pattern. The radiological outcome was evaluated using Matta’s criteria to grade postoperative reduction and final radiological outcome and the restoration of the hip joint center (HJC). The clinical outcome was evaluated using the modified the Merle d’Aubigné-Postel (DAP) hip score.

Results

Both post-course groups had statistically better functional and radiological outcomes compared with the pre-course group. Depending on the learning curve, the mean duration of surgery decreased from 153 minutes to 82.3 minutes. Although there was no statistical difference between groups in the vertical shift of the HJC, there was a statistically significant in the amount of horizontal shift of the HJC in the second two years of training, compared with the other groups.

Conclusions

Functional and radiological outcome of surgical treatment of acetabular fracture may be improved with increased training, depending on the learning curve.

The Central Dislocation of Femoral Head in the Transverse and Both Column Acetabular Fractures: Is It Really Medialized?

Purpose

We hypothesized that the central dislocation of the femoral head does generally not occur in transverse acetabular fractures, although it does usually occur in both column fractures.

Materials and Methods

Fifty-two transverse and both column acetabular fracture cases were evaluated retrospectively. The distances between (a) the sciatic notch on the fracture side and the vertical axis of the pelvis (VA line) and (b) the contralateral intact sciatic notch and the VA line were measured. The a/b ratio corresponded to the superior iliac segment displacement or rotation. The ratio of the distance between the fracture side femoral head and the VA line (c) and the distance between the contralateral intact femoral head and the VA line (d) corresponded to the femoral head displacement. The width of ischium (e) on fractured side and (f) contralateral side were measured. The e/f ratio increment reflected ischiadic fragment mobility.

Results

The median value of femoral head displacement (c/d) of the transverse fracture group (n=25) was 1.02 (1.000-1.07). Ischiadic fragment rotation (e/f ratio) of the transverse fracture group was 1.000. The median value of femoral head displacement (c/d) of the both column fractures (n=27) was 0.78 (0.64-0.85). Ischiadic fragment rotation (e/f ratio) of the both-column group was 1.15 (1.06-1.23). The differences between groups according to measurements were statistically significant.

Conclusion

In contrary to Letournel description, our findings showed no medialization of femoral head in transverse acetabular fractures in general. This might be an illusion resulting from external rotation of the superior iliac segment.

Revision Total Hip Arthroplasty Using Tantalum Augment in Patients with Paprosky III or IV Acetabular Bone Defects: A Minimum 2-year Follow Up Study

PURPOSE

The purpose of this study is to report the short-term outcomes of revision total hip arthroplasty (THA) using tantalum augments in patients with severe acetabular bone defects.

MATERIALS AND METHODS

We retrospectively analyzed 15 revision THAs performed in 15 patients using tantalum augments between June 2010 and December 2013. Acetabular bone defects were Paprosky type IIIA in 7 hips, type IIIB in 7, and type IV in 1. The causes of revision surgery were aseptic loosening in 12 hips and deep infection in 3. Revisions were first in 1 hip, second in 3, and third in 11. Six patients were male and 9 female with a mean age of 59 years (range, 48-75 years). Mean follow-up was 29 months (range, 24-48 months).

RESULTS

Mean Harris hip score was improved from 34 points (range, 12-54 points) preoperatively to 84 points (range, 38-90 points) at final follow-up. On the final follow-up radiographs, there were 12 hips (80.0%) with stable fixation of the acetabular cup, 2 (13.3%) with secondary stability after mild acetabular protrusion, and 1 (6.7%) with radiolucency around the acetabular cup without mechanical symptoms. Complications included one patient with acute hematogenous infection managed by surgical debridement and long-term antibiotic therapy. There were no cases with nerve palsy or dislocation during the follow-up period.

CONCLUSION

The present study showed satisfactory clinical and radiographic outcomes of revision THA using tantalum augments due to severe acetabular bone defects of Paprosky type III or IV at a minimum follow-up of 2 years.