Outcomes of modular femoral revision implants and the effect of component design on subsidence

Mid-term results of a cementless hip stem in femoral revision: how much diaphyseal press-fit do we need?

INTRODUCTION

The aim of this retrospective study was to analyze the clinical and functional outcome of a modular tapered revision hip stem after mid-term follow-up with a special focus on the length of the distal bicortical fixation of the cementless hip stem.

MATERIALS AND METHODS

Follow-up examination was carried out for all patients with implantation of the Prevision hip stem between 2014 and 2019 to collect demographic, functional, and radiographic data.

RESULTS

44 patients with stem in situ were examined, and 61 patients could be included in the Kaplan-Meier survival analysis. Oxford's hip score was 37.3 at the mean follow-up of 4.0 years. Two hip stem revisions were performed due to periprosthetic infection, which resulted in a hip stem survival rate of 96.7% (CI: 87.4-99.1%) at the final follow-up of 7.5 years. No aseptic hip stem revision was required. The length of bicortical distal fixation was in the interquartile range of 6.8 to 9.0 cm, which was associated with good bone healing and a low rate of subsidence (4.5%). Implant-associated complications were observed in 10 cases (21.7%).

CONCLUSIONS

The modular revision hip stem provides promising results at medium-term follow-up, with satisfactory clinical and functional outcomes comparable to other modular revision hip stems. The presented length of bicortical distal fixation shows the practice of the study center and was associated with good implant survival, bone healing and radiological results.

REGISTRATION

Clinicaltrials.gov registration: NCT04833634 registered on April 6, 2021.

Long-term Outcomes of Revision Total Hip Arthroplasty Using a Modular Fluted Conical Femoral Stem

BACKGROUND

This study presents minimum 6-year follow-up data on the survival and satisfaction of an uncemented modular revision femoral system, following on from our previously published earlier results.

METHODS

We retrospectively reviewed all revision hip arthroplasties performed at our institution between January 2005 and October 2012, using a single modular femoral revision system. Patient-reported outcomes were collected (satisfaction score and Oxford Hip Score). Preoperative and postoperative radiographs were reviewed for stem subsidence, and Kaplan-Meier analysis was performed for survival. A total of 115 femoral revisions were performed in 106 patients.

RESULTS

All-cause survival was 82% (95% confidence interval 74 to 91%) at 10.8 years, and 96% (95% confidence interval 90 to 100%) excluding septic failure. Of the 19 cases requiring reoperation, 16 were for infection, 2 for aseptic loosening, and 1 for mechanical failure. At final follow-up, 88.5% of patients were "satisfied" or "very satisfied".

CONCLUSIONS

This study showed excellent clinical results of a commonly used revision hip stem with at least 10 years follow-up. Satisfaction rates were high, with few aseptic failures. Stem subsidence was more common in revisions for infection, but did not correlate with lower satisfaction scores.

Clinical and radiographic outcomes of long monoblock, hydroxyapatite-coated stem in revision hip arthroplasty with extended trochanteric osteotomy: a multicenter study

BACKGROUND

The distally fixed stem used in revision total hip arthroplasty (rTHA) with extended trochanteric osteotomy (ETO) is subject to periprosthetic fracture, stem subsidence, and stress shielding. The prospective multicentric study aimed to assess the clinical and radiographic outcomes, and complications of using the Corail revision stem in rTHA with ETO.

METHODS

Sixty-four patients undergoing rTHA with ETO using the Corail revision stem between 2019 and 2020 were enrolled in the study. We performed a postoperative follow-up of the patient and obtained radiographs and Harris hip scores (HHSs). These results were used to analyze ETO union, Engh scores, bone remodeling, stem stability and hip function.

RESULTS

The mean follow-up duration was 34 months (range 23-41). Sixty-two patients who underwent ETOs achieved complete healing at the final follow-up. Fifty-nine hips had bony ingrowth from the osteotomy fragment to the stem without radiolucent lines. The postoperative Engh score was 21.3 ± 3.59 (range 15.5-27.0). Forty-three hips had regeneration in the proximal femur. Two patients had transient thigh pain postoperatively. The postoperative HHS improved from 40.7 ± 16.67 (range 0-67) preoperatively to 82.1 ± 6.83 (range 73-93).

CONCLUSION

Corail revision stems are a viable and reliable option in rTHA with ETO. This stem had excellent clinical and radiographic outcomes, resulting in a high rate of ETO union and stem survival. The revision stem enabled restoration of proximal bone stock in femurs with prerevision bone defects, which were prepared for the next revision operation. Level of evidence Level IIb, Prospective self-control study.

Micromotion and stress shielding between taper fluted and cylindrical femoral stems for Paprosky bone deficiency type IIIB

PURPOSE

Taper fluted and cylindrical femoral stems have been commonly used for revision surgery with femoral bone loss. Shape and material differences between taper fluted and cylindrical confused surgeons whether superiority and inferiority in comparisons especially for type IIIB Paprosky bone deficiency. This study aims to investigate the micromotion between implant and bone interface and stress distribution around the implant in human cadaveric experiments.

METHODS

Paired comparisons of 7 cadavers between taper fluted stem and cylindrical stem were tested under dynamic cyclic loading.

RESULTS

The results showed appropriate bone-implant micromotions for bone osteointegration could be observed between both taper fluted and cylindrical stems (85 ± 10 μm and 113 ± 80 μm respectively, p = 0.59). Taper fluted stem attained the load distribution from the proximal to distal surrounding bone (from 4.92 ± 2.87 MPa to 2.14 ± 1.43 MPa, p = 0.43), while the cylindrical stem type showed the proximal bone stress shielding (from 2.56 ± 0.76 MPa to 5.23 ± 0.77 MPa, p = 0.03).

CONCLUSION

Both taper fluted and cylindrical femoral stems provided an adequate initial stability with a proper micromotions for bone-implant osteointegration for type IIIB Paprosky femoral bone loss. The taper fluted femoral stem had better biomechanical advantage in terms of greater stress transfer to periprosthetic bone.

Save the Greater Trochanter: A Novel Modification to the Extended Trochanteric Osteotomy

The extended trochanteric osteotomy is the workhorse for removal of well-fixed femoral stems during total hip revision arthroplasty. Despite its reliable performance in exposing the implants for removal and accessing the femoral canal, significant complications can occur. Though these complications are rare, trochanteric nonunion, trochanteric escape, and femoral implant subsidence can have a significant negative impact on gait mechanics and patient outcome. If access to the canal was still possible and the greater trochanter could remain in place, these complications could be minimized or possibly even eliminated. This paper describes a novel technique using a lateral cortical window just distal to the greater trochanter that allows removal of a well-fixed stem and leaves the greater trochanter intact.