Custom-made femoral implants in total hip arthroplasty due to congenital disease of the hip: a review

Optimizing Acetabular Positioning: A Comprehensive Review of Contemporary Strategies in Total Hip Arthroplasty

Total hip arthroplasty (THA) is a widely practiced surgical intervention to alleviate pain and reinstate functionality in individuals afflicted with hip joint pathology. The positioning of the acetabulum assumes paramount significance in determining the efficacy of THA, exerting profound influences on biomechanical dynamics, stability, and the durability of outcomes over time. This comprehensive review meticulously evaluates contemporary methodologies for optimizing acetabular positioning in THA, encompassing advanced technologies such as computer-assisted navigation systems, patient-specific instrumentation, robotic-assisted surgical approaches, image-based planning techniques, and intraoperative fluoroscopy. Crucially, key discoveries underscore the pivotal role of precise acetabular alignment in mitigating complications such as dislocation, component wear, and impingement. Moreover, the implications for clinical practice accentuate the imperative of continuous education and training to ensure effective deployment of sophisticated methodologies. Recommendations for furthering research and enhancing practice development underscore the necessity of scrutinizing long-term prognoses, assessing cost-effectiveness, and embracing technological innovations perpetually refining THA outcomes. Collaborative endeavors among researchers, practitioners, and industry stakeholders emerge as indispensable drivers of advancement in this domain, fostering an environment conducive to elevating the standard of care for individuals undergoing THA.

Accuracy of Positioning and Risk Factors for Malpositioning Custom-Made Femoral Stems in Total Hip Arthroplasty-A Retrospective Multicenter Analysis

Total hip arthroplasty (THA) is commonly performed using off-the-shelf implants. In the case of a severe mismatch between the anatomy of the proximal femur and the geometry of the stem, the use of custom-made stems might become necessary. The goal of this study was to investigate the precision of the implantation of custom-made stems of one manufacturer (CTX stem, AQ Implants) and to determine risk factors for malpositioning. All patients receiving a custom-made CTX stem between 2014 and 2020 at six high-volume academic centers were retrospectively recruited. The achieved position of the stem, as determined by stem version, stem coronal angle, and implantation depth on radiographs, was compared to the plan. The influence of radiographic and demographic parameters on the position was investigated. The results revealed a high variability of the achieved implant position in relation to the preoperative plan. While the stem coronal angle only differed slightly from the intended position, the stem version and the implantation depth showed a high frequency and amount of deviation. Right stems showed significantly higher positions than planned. Surgeons must be aware of this potential problem when implanting custom-made stems.

The torsion of the proximal femur in cementless total hip arthroplasty: a 3-dimensional evaluation

INTRODUCTION

The anatomy of the proximal femur at the time of total hip arthroplasty has been widely studied but the horizontal plane was never considered, or only limited to the torsion of the femoral neck.

METHODS

Using CT-scan images from a group of 178 patients scheduled for cementless total hip arthroplasty (THA), we analysed the evolution of the torsion of the proximal femoral metaphysis, in reference to the posterior bicondylar plane of the femur. The evolution of the torsion, between 20 mm below the centre of the lesser trochanter and 20 mm above, was evaluated.

RESULTS

In cases of primary osteoarthritis, osteonecrosis, rheumatoid arthritis and epiphysiolysis capitis femoris, the mean torsion decreased from 46° to 20° without significant differences in average values between the different diagnoses, but important individual variations were found. In the groups of dysplasia and congenital hip dislocation, the torsion values were significantly higher, decreasing in mean from 59° to 25° and 63° to 34° respectively, and with important individual variations.

CONCLUSIONS

These data are important when using cementless femoral stems, since an ideal fit-and-fill in the proximal femur zone has been shown to positively influence bone ingrowth of the stem. However, a strict adaptation of the stem to the medullary canal, without considering its torsion, can lead to an increased or decreased torsion of the prosthesis neck and thus to an instability of the arthroplasty. For these reasons, if a perfect adaptation of the stem to the intramedullary anatomy and an optimal reconstruction of the extramedullary anatomy are to be achieved, 3-dimensional planning should ideally be obtained for every patient. This will allow the best stem choice adapted to every single patient and every kind of anatomy.

Bilateral Cemented Custom-Made Total Hip Arthroplasty in Paget's Disease with Femoral Cortical Thickening and Canal Narrowing

In this report, we present a case of a 57-year-old man complaining of pain in both his hips. Clinically, the patient reported lameness and reduction in the range of motion of the hips. Radiographic imaging showed a very narrow medullary femoral canal, confirmed by a computed tomography scan. In consideration of the narrowness of the femoral canal and cortex thickening, and due to the rarity of the clinical case, we opted to use a custom-made prosthesis. We performed total hip arthroplasty, initially on the right side. One year later, we repeated the procedure on the left side. One year after the last surgery, the patient reported well-being and continuous improvement in walking, with no complications. This case report highlights the features and the critical issues related to this kind of surgery in patients affected by Paget's disease of the bone and the importance of custom-made implants in challenging cases.

Total Hip Arthroplasty With Trochanteric Ostectomy for Patients With Angular Deformity of the Proximal Femur

BACKGROUND

Total hip arthroplasty (THA) of patients with a proximal femoral deformity is technically demanding. This deformity poses the risk of femoral fracture or perforation; stem malposition; and failed stem fixation. To insert a femoral stem in neutral position with a good fit, we removed the greater trochanter in case of a varus deformity, and the lesser trochanter in case of valgus deformity, while performing THA. We aimed to evaluate stem position, implant stability, clinical results, and radiological changes after THAs using this technique.

METHODS

Fifteen patients (17 hips; 11 varus hips and 6 valgus hips) underwent cementless THA using the trochanteric osteotomy technique in one institution. We evaluated procedure-specific complications: intraoperative femoral fracture, stem malposition, weakness of the abductor power and limp. Modified Harris Hip Score, radiological changes, and the stability of stems were assessed at a mean of 7.1 years of follow-up (range 2.0-15.5).

RESULTS

Femoral fracture occurred during the insertion of the stem in 4 hips. All stems were aligned in neutral position. At the latest follow-up, the mean power of the abductor was 4.3 (range 3-5). Eleven patients had slight limp and 4 patients had moderate limp. All stems had bone-ingrown stability and no stem was revised. The mean modified Harris Hip Score improved from 50 points at the preoperative evaluation to 81 points at the final follow-up.

CONCLUSION

The trochanteric excision enabled neutral insertion of cementless stem in patients with varus/valgus deformity of the proximal femur, and THA using this technique rendered favorable results.

Mid-term results of short-stem total hip arthroplasty in patients with Crowe type I and II developmental dysplasia of the hip

BACKGROUND

This study aimed to evaluate the clinical and radiographic mid-term results of short-stem THA in patients with DDH.

METHODS

We reviewed 32 cases that underwent Metha stem between November 2010 and February 2015. WOMAC scores, Oxford Hip Scores (OHS) and Harris Hip Scores (HHS) were recorded to evaluate the clinical results. The appearance of bone trabeculae development and stress shielding was analyzed.

RESULTS

The mean age of patients was 50.3 years (33-67) with the mean follow-up of 77 months (60-106). According to Crowe classification, 13 cases were graded as Crowe I and 19 cases as Crowe II. According to Dorr classification, 17 cases were graded as Dorr A and 15 cases as Dorr B. The postoperative WOMAC scores decreased, and OHS and HHS increased significantly compared with preoperative (p < 0.001). The caput-column-diaphysis angles decreased significantly (p < 0.001) and limb length discrepancy decreased significantly (p = 0.013) after surgery. The radiographic change around the stem showed bone trabeculae development at zones 1 (93.9%), 2 (93.9%), 3 (25%), 5 (6.3%), 6 (96.9%) and 7 (90.6%). There was grade 1 stress shielding in 30 cases (93.9%). There was no stem subsidence greater than 2 mm in all hips, no sciatic nerve injury or no dislocation. Neither acetabulum nor femoral stem was defined as definite loosening, and none of the implants was revised.

CONCLUSIONS

The short stem showed promising mid-term clinical results in patients with DDH. The radiographic results demonstrated that the short stem provided physiological proximal load transfer with less stress shielding, being a useful alternative for femoral reconstruction.

Direct Anterior Approach Versus Posterolateral Approach in Total Hip Arthroplasty: A Systematic Review and Meta-analysis of Randomized Controlled Studies

Objective

To compare the early rehabilitation effects of total hip arthroplasty (THA) with the direct anterior approach (DAA) versus the posterior approach (PA).

Methods

We searched PubMed, Embase, Web of Science, the Cochrane Library, and Google databases from inception to June 2019 to select studies that compared the DAA and PA for THA. Only randomized controlled trials (RCT) were included. Two researchers independently screened studies for inclusion, extracted data, and assessed the methodological quality. A meta‐analysis was conducted using RevMan 5.3 software provided by Cochrane Assisted Network.

Results

A total of 932 patients underwent THA. There were 467 cases in group DAA and 465 cases in group PA. There was a significant difference in the incidence of lateral femoral cutaneous nerve injury between DAA and PA groups (RR = 38.97, 95% CI: 7.89–192.57, P < 0.05). DAA was associated with less pain compared with PA [WMD = −0.65, 95% CI (−0.91–0.38), P < 0.05]. There was no significant difference in operation time, hospitalization stay, and intraoperative bleeding volume. Moreover, in supplementary data, the number of acetabular prostheses in Lewinnek's safety zones in DAA was more than that in the PA group (RR = 1.20, 95% CI [1.04–1.39], P < 0.05), and the time of discontinuation of walking aids in the DAA group was earlier than that in the PA group (WMD = −11.05, 95% CI [−17.79–4.31], P < 0.05).

Conclusion

The DAA total hip arthroplasty has comparable results with PA, with earlier postoperative functional recovery, less postoperative pain scores, and higher incidence of lateral femoral cutaneous nerve injury. The results need to be validated by large‐sample, high‐quality RCT studies, and long‐term follow‐up of complications.

Long-term results of custom-made femoral stems

BACKGROUND

The progress of 3D imaging and manufacturing of implants has made it possible to achieve a custom-made concept in THA. The custom-made cementless femoral stem provides optimal implant stability combined with restoration of the native hip mechanics.

OBJECTIVE

The purpose of this study was to evaluate the long-term survivorship of custom-made hip femoral stems in two populations of patients undergoing THA: patients under 50 years old (young patients group) and patients with high-grade developmental dysplasia of the hip (DDH group).

METHODS

A series of 232 primary custom-made cementless THA stems were retrospectively evaluated in patients less than 50 years old at the time of surgery and at follow-up after an average of 20 years. A second series of 26 custom-made cementless stem THAs for late DDH (21 patients) including only Crowe grade III and grade IV were also retrospectively evaluated with an average follow-up of 16 years. The clinical and radiological evaluations were performed preoperatively and at yearly intervals.

RESULTS

For the young patient group, the follow-up ranged from 14 to 27 years. The HHS and the Merle D'Aubigne-Postel score significantly improved from preoperatively to a mean of 94.1 (range 48-100) and 15.9 (range 9-18), respectively. Taking stem revision for aseptic loosening as an endpoint, survivorship was 96.8% at 20 years (95% confidence interval, CI 95.1-98.5). For the DDH group, the follow-up ranged from 10 to 22 years. The mean HHS increased significantly from preoperative 49 ± 22 points to the most recent follow-up examination with 86 13 points and survivorship was 96.1% (95% CI, 92.7-99.9).

CONCLUSION

Custom-made femoral stems provide good functional outcome and long-term survivorship in two specific populations of patients undergoing THAs: patients under 50 years old with high expectations and patients with high-grade DDH.

Preoperative Planning for Total Hip Arthroplasty for Neglected Developmental Dysplasia of the Hip

Developmental dysplasia of the hip (DDH) is accompanied by morphological alterations on both the acetabular and the femoral side. Total hip arthroplasty (THA) provides effective treatment in cases of neglected DDH but requires elaborate preoperative planning. To determine the morphological changes resulting from the dysplasia, the anatomic acetabular position, the height of the femur head dislocation, the height of the femur head dislocation, and the combined anteversion must all be established. In addition, a vital and complicated process of strategizing leg length balance must be conducted in cases of severe DDH. Each type of leg length discrepancy (LLD), including bony and functional and anatomical LLD, should be evaluated in the context of the presence or absence of a fixed pelvic tilt. Moreover, with severe unilateral dislocated hips, a more inferior change in the original rotational center of the hip must be accounted for. Due to these multiple morphological changes, the accurate size of the prosthesis and the cup position are difficult to predict. In comparison with other methods, CT scan‐based 3‐dimensional templating provides the best accuracy. Despite the presence of anatomic alterations, various types of acetabular and femoral prostheses have been developed to treat hip dysplasia. Both cemented and cementless cups are used in DDH cases. In DDH accompanied by insufficient acetabular bone stock, a cemented cup combined with bone graft provides a reliable treatment. Monoblock stems can be used when the combined anteversion is less than 55°, and a modular stem system when this parameter is greater than 55°. Customized stems can be designed for DDH coupled with severe proximal femoral distortion. A ceramic‐on‐ceramic bearing is considered optimal for young DDH patients.

Minimum 10-Year Outcome of One-Stage Total Hip Arthroplasty Without Subtrochanteric Osteotomy Using a Cementless Custom Stem for Crowe III and IV Hip Dislocation

BACKGROUND

Options for total hip arthroplasty (THA) in high dislocated hips include subtrochanteric osteotomy (STO), high hip center positioning, and 2-stage surgery with progressive lowering using an external fixator before THA. We described the long-term results of 1-stage THA performed without STO, using a cementless customized stem associated if necessary with sequential tenotomies and/or greater trochanteric osteotomy.

METHODS

Ninety-eight consecutive THA without STO were performed using this technique. Of those 98 hips, 26 hips with high dislocation (12 class III and 14 class IV according to the Crowe classification) were evaluated at an average follow-up of 16 (10-22) years.

RESULTS

At the time of last follow-up, the mean Harris Hip Score was 86 points (37-100). The mean leg-length discrepancy was 7 ± 5 mm (0-17). Two transient (7.7%) nerve palsies (1 sciatic and 1 femoral) were notified. A revision was required for 6 hips (23.1%). Kaplan-Meier survivorship analysis at 15 years regarding aseptic loosening of the femoral component was 87.5% (95% confidence interval, 76.5-99.1). During the same period, acetabular implant survivorship free from revision for aseptic loosening was 96.1% (95% confidence interval, 92.7-99.9).

CONCLUSION

The combination of intramedullary fit and extramedullary adaptation for offset and anteversion provided by the custom stem can avoid additional procedures associated to THA in high developmental dysplasia of the hip. The clinical function and long-term survival reported in this series is encouraging for THA performed in case of high hip dislocation.

Load transfer and periprosthetic fractures after total hip arthoplasty: Comparison of periprosthetic fractures of femora implanted with cementless distal-load or proximal-load femoral components and measurement of the femoral strain at the time of implantation

BACKGROUND

Little is known about the causes and mechanisms underlying periprosthetic fractures around femoral components particularly in relation to the stem design. In an in vitro study 20 pairs of fresh cadaveric femora were loaded to fracture axially and transversally.

FINDINGS

When proximal femoral strain was measured at the time of impaction of cementless stems the load transfer was determined by the underlying anatomy rather than by the shape of the stem, so that the so-called "load transfer" properties - proximal or distal - ascribed to stem designs are a myth. The axial-load and the transverse-load model were then exposed to loads to failure (fracture) and showed a biphasic pattern throughout independent of the impact direction. In the second phase, the fracture phase proper, the bone behaved like a brittle solid. Failure occurred very rapidly within less than 5 milliseconds. The forces to failure were between 2 and 11 kN. Most of the fractures (82.5%) occurred above the stem tip.

INTERPRETATION

Note that the study was confined to early preosteointegration fractures. Neither the stem design nor the impact direction, i.e. on the knee or on the side of the hip, was related to the fracture morphology.