Metaphyseal debonding of the Corail collarless cementless stem: report of 18 cases and case-control study

Medium-term outcomes of conventional versus short uncemented femoral stems for primary total hip arthroplasty in patients younger than 55 years

BACKGROUND

Short stems are designed with a bone preservation philosophy in mind. This study aims to compare the outcomes/complications and survival of a collarless fully hydroxyapatite (HA)-coated conventional tapered stem and a HA-coated partial neck-retaining uncemented short stem in patients ⩽55 years old at medium-term follow-up.

METHODS

We retrospectively studied 247 uncemented THAs operated between 2010 and 2014, comparing 146 patients treated with the fully HA-coated collarless stem (Group A) with 101 patients treated with a partial neck preserving, HA-coated short stem (Group B). 87 and 62 males were in groups A and B, respectively (p = 0.11). The mean age of the series was 46 years (17-55) (p =0.16). The mean follow-up of groups A and B were 9.9 (7-12) years and 9.7 (7-12) years, respectively (p =0.21).

RESULTS

Mean Harris Hip Score improved from 55 to 92 in group A (p <0.001) and from 54 to 95 in group B (p <0.001), without differences between groups. Mean femoral neck length preservation in groups A and B was 13.6 (0-28) mm and 26 (11-38) mm, respectively (p =0.001). 13 (8.9%) and 1 (1%) patients in groups A and B presented postoperative complications, respectively (p =0.008). The conventional stem group had more aseptic loosening (Group A 3.4% vs. Group B 0%, p =0.06) along with more Symptomatic radiolucent lines (Group A 3.4% vs. Group B 0%, p =0.06).

CONCLUSIONS

Both conventional and short stems showed excellent implant survival rates and functional outcomes at a mean follow-up of 9.8 years. However, complications and radiolucent lines were more frequent with a collarless conventional-length stem. Bone preservation of the femoral neck and diaphysis may be preferred in active young patients.

Stem size and stem alignment affects periprosthetic fracture risk and primary stability in cementless total hip arthroplasty

The ideal stem size and stem position is important for the success of total hip arthroplasty, since it can affect early implant loosening and periprosthetic fractures (PPF). This study aimed to investigate how small deviations from the ideal stem size and position influences the PPF risk and primary stability. Six experienced surgeons performed preoperative templating based on which the benchmark size for each femur was determined. Consecutive implantations were performed in six cadaveric femur pairs-one side was implanted with an undersized stem followed by the benchmark size and the contralateral side with a benchmark size followed by an oversized stem (Corail, Depuy Synthes). Moreover, three different alignments (six varus, six neutral, six valgus-undersized) were compared using 18 femurs. Cortical strains during broaching and implantation were measured, and laser scans were used to determine final stem position. All specimens underwent dynamic loading. Primary stability was estimated from stem subsidence and pull-out forces. Templated stem size varied between surgeons (±1 size; p = 0.005). Undersizing increased stem subsidence by 320% (p < 0.001). Oversized stems exhibited 52% higher pull-out forces (p = 0.001) and 240% higher cortical strains (p = 0.056). Cortex strains increased with varus alignment (R2  = 0.356, p = 0.011) while primary stability decreased with valgus stem alignment (p = 0.043). Surgeons should be aware that small deviations from the ideal stem size and malalignments of the stem can significantly alter the mechanical situation and affect the success of their surgery.

Survival and performance of a dual tapered-wedge fully HA-coated press fit femoral stem

INTRODUCTION

Fully hydroxyapatite-coated titanium alloy double-tapered stems have been successful implant designs for THA. The Novation Element Stem (Exactech, Gainesville, FL) is one of several of these implants following a modified Corail design philosophy. Although a great deal is known about the results of the Corail stem, little is known about the more recent Corail-inspired implants. The authors evaluated the clinical outcomes, radiographic findings and survival statistics of the collarless version of the Element Stem when used routinely in a diverse patient population.

METHODS

A retrospective review was performed for all primary THR cases from 2010 to 2018. Patient demographics and HHS/OHS/patient satisfaction scores were obtained. Radiographs were evaluated for stem subsidence, radiolucencies, and bone responses to the implant.

RESULTS

One hundred and fifty seven Element Stems were implanted with greater than 2 years of radiographic follow-up, while 105 Element Stems implanted during the study period had a survival of 5 years or more. Average HHS was 91.7 and average OHS was 44.0. 54 of 157 hips had radiolucencies, all of which included a proximal zonal radiolucency. Average subsidence was 3.33 mm; 18 hips had subsidence > 4 mm. There were 8 revisions for: aseptic loosening (4), trauma-related peri-prosthetic fractures, and early proximal-medial fractures. At 5 years, the all-cause survival rate is 92.4%, 96.2% based only on aseptic loosening and 98.1% based only on proximal medial fractures.

CONCLUSION

Clinical outcomes using the collarless Novation Element Stem are good, but early proximal medial fracture is still a factor in patients with poor-quality bone. Proximal radiolucencies progressing to aseptic loosening post-operatively are also a concern. The 11.5% rate of subsidence is comparable to other fully HA-coated collarless stems. This study provides a thorough critical analysis of outcomes and midterm survival data of this dual tapered-wedge fully HA-coated collarless stem used routinely in a diverse patient population.

Revision of double-tapered, titanium, fully hydroxyapatite-coated femoral stems: ease of extraction and subsequent reconstruction

BACKGROUND

Fully hydroxyapatite coated, double-tapered, titanium stems are the most commonly used uncemented implants in the UK with survivorship reported at 96.3% at 23 years however there is no literature on the consequences of revision. We aimed to explore the reasons for failure, ease of stem extraction, extent of bone loss and complexity of the subsequent reconstruction.

METHODS

Between December 2012 and March 2019, 104 cases requiring removal of the Corail^® stem (DePuy Synthes, Warsaw, IN, USA) were identified from the National Joint Registry (NJR) and our local revision database. Indication for revision, surgical/reconstruction technique, complications and follow-up data were reviewed.

RESULTS

The common reasons for revision were aseptic loosening 45.2%, infection 23.5%, instability 4.8% and peri-prosthetic fracture 12.5%. Removal of the implant without extended trochanteric osteotomy (ETO) was achieved in 94.2% of cases. Of those revised for aseptic loosening 23% were proximal, 38% were proximal/mid stem and 38% all zones. Significant bone loss is not a common feature of the failure of this stem with 95% graded as a Paprosky grade 2 or less. In terms of reconstruction, 69.2% were revised to a primary cemented stem.

CONCLUSIONS

In the majority of cases revision can be achieved without an ETO and reconstruction possible using a primary stem as significant bone loss is not a common feature of failure of this stem design. We conclude that this stem is safe to use in younger patients who may outlast any type of primary implant and would inevitably face revision in their lifetime.

Risk Factors for Significant Radiolucent Line Development in a Fully Coated Hydroxyapatite Stem

BACKGROUND

The risk factors for and clinical impact of radiolucent lines (RLLs) in cementless total hip arthroplasty remain contentious. The aim of this work was to describe a method of classification that has clinical significance and to identify risk factors.

METHODS

A cohort of 288 subjects with unrevised Corail stems (DePuy Synthes, Warsaw, IN) were reviewed with radiographs and Oxford Hip Scores at 10 years. Based on clinical experience, three groups were defined; those with no RLLs (NoRLLs), those considered to have benign RLLs (BenRLLs), and those considered to have significant RLLs (SigRLLs). SigRLLs were then compared to BenRLLs and NoRLLs to determine the validity of this classification.

RESULTS

One hundred and nine (37.8%) had NoRLLs, 111 (38.5%) had BenRLLs, and 68 (23.6%) had SigRLLs. No significant difference apart from gender was noted between the occurrence of BenRLLs and NoRLLs after multinomial regression analysis, consequently the NoRLLs and BenRLLs groups were combined (NoSigRLLs) and compared to SigRLLs. Non-cross-linked polyethylene (odds ratio = 4.6, P < .001), collarless stem design (odds ratio = 9.4, P < .001), undersizing (odds ratio = 1.2, P = .028), and male sex (odds ratio = 2.1, P = .008) were risk factors for SigRLLs. Regression analysis also revealed that increasing age at operation decreased the likelihood of SigRLLs (P < .001). Patients with SigRLLs had significantly higher pain scores (P = .005) although overall Oxford Hip Scores were not significantly different (P = .364).

CONCLUSION

The definition of SigRLLs proposed in this study was significantly associated with that of non-cross-linked polyethylene, absence of a collar, undersizing, and higher pain scores.

The fate of sagittal alignment in tapered uncemented femoral components in total hip arthroplasty: 889 hips followed for a minimum of 10 years

PURPOSE

Aseptic loosening is rare after primary total hip arthroplasty (THA) with mostly uncemented tapered stems; however, different factors can modify the results. We question whether 3 different current femoral components and/or the surgical technique affect the clinical and radiological outcome after a minimum follow-up of 10 years.

METHODS

889 uncemented tapered stems implanted from 1999 to 2007 were evaluated for a minimum follow-up of 10 years. Group 1 (273 hips) shared a conical shape and a porous-coated surface, group 2 (286 hips) a conical splined shape and group 3 (330 hips) a rectangular grit-blasted stem. Groups 1 and 2 were implanted through a posterolateral approach and group 3 using an anterolateral approach. Clinical outcomes and anteroposterior and sagittal radiographic analyses were compared.

RESULTS

No thigh pain was reported in unrevised patients. Mean Harris Hip score was lower for patients in group 3 for pain and function at all intervals. 14-year implant survival for aseptic loosening was 98.2% (95% confidence interval [CI] 96.2-100) in group 3. No revision for aseptic loosening was found with the other designs. A stem position outside neutral limits in the sagittal alignment (p = 0.001, hazard ratio: 6.17, 95% CI, 2.05-18.61) was associated with aseptic loosening in group 3.

CONCLUSIONS

Most current uncemented straight tapered femoral components can provide adequate bone fixation in primary THA after 10 years. Conical stems inserted through a posterolateral approach are more reliable than rectangular ones inserted through an anterolateral approach.

Aseptic Loosening of Smaller Corail Stems in Heavy, Active Males: A Report of Three Cases

Recent concerns have been raised regarding a higher failure rate with smaller size Corail stems. This case series examines early aseptic loosening with smaller stems in three large male patients with Dorr A bone. Each stem was fluoroscopically aligned and sized until stable with axial and rotational stress. In each case, failure occurred within six months due to symptomatic metaphyseal debonding. Careful analysis suggests a correlation of failure to small size stems that are comparatively 1) undersized relative to the metaphysis, 2) undersized relative to patient body mass index, and 3) undersized relative to the amount of offset created.

Occult Hip Prosthetic Loosening Diagnosed by [18F] Fluoride-PET/CT

Background

Positron emission tomography using the [18F] fluoride metabolite combined with computerized tomography (F-PET/CT) can be used to analyze the metabolic status of the periprosthetic bone after surgery for total hip arthroplasty.

Methods

To obtain normal PET referent values, 44 patients with 5 models of well-functioning hip prosthetic components were analyzed by F-PET/CT, radiography, and clinical score. Another group of patients having painful total hip arthroplasty, but whose radiography showed no conclusive signs of loosening, was analyzed by F-PET/CT scans before revision surgery.

Results

Preoperative median F-PET scores of the bone metabolic activity were 6.65 (3.3-9.0) for the painful stem group and 1.85 (1.2-3.9) (P < .01) for the referent group having the same stem model. At revision surgery, the stems in the painful group were assessed to be loose. At 2-year follow-up, the revised patients were all pain free.

Conclusion

F-PET/CT may be a new diagnostic tool for assessing occult loose stems that are not seen by radiography.

Mid-term progressive loosening of hydroxyapatite-coated femoral stems paired with a metal-on-metal bearing

Background

Several hydroxyapatite (HA)-coated femoral stems from a single manufacturer were identified to have aseptically loosened at mid-term follow-up despite prior radiographic appearance of osseointegration. Possible causes and associated risk factors for stem loosening were explored through radiographic review and implant retrieval analysis.

Methods

Forty-six retrieved hip stems (Corail, DePuy-Synthes) were identified and grouped by bearing type: metal-on-metal (MoM), metal-on-polyethylene, and ceramic-on-ceramic. Stem lucency was graded on post-operative radiographs up to the time of revision. Stems were examined for stripping of the HA coating, taper corrosion, and bearing wear in metal-on-metal cases. Patient demographics, implant design features, and perioperative data were collected from electronic databases and patient charts.

Results

Aseptic loosening occurred in 37% of cases examined. MoM bearings were associated with 7.25 times greater risk of loosening compared to other bearing types. Stem radiolucency was more prevalent for MoM cases and, although not statistically significant, demonstrated progressive lucency. Taper corrosion appeared more severe for MoM cases and correlated with proximal stem radiolucency. Removal of the HA coating from the stems was associated with both taper corrosion and MoM bearing wear. Length of implantation was a confounding factor for the MoM cases.

Conclusion

This study has demonstrated a high risk of mid-term loosening of previously osseointegrated HA-coated femoral stems when paired with a MoM bearing. The mechanism of loosening appears progressive in nature and related to the MoM bearing, possibly interacting with the HA coating. If such loosening is recognized early, rapid revision may allow for retention of the femoral stem.

Uncemented Total Hip Arthroplasty Through the Direct Anterior Approach: Analysis of a Consecutive Series of 275 Hips With a Minimum Follow-Up of 10 Years

BACKGROUND

The purpose of this study was to document complications, outcomes, and 10-year survivorship of primary total hip arthroplasty (THA) using a direct anterior approach with an uncemented, straight, hydroxyapatite-coated stem and an uncemented cup.

METHODS

A retrospective, consecutive series of 275 primary THAs through a direct anterior approach with traction table using Medacta Versafit cup and Quadra-H stem with a minimum of 10-year follow-up was identified. The cumulative 10-year survival of the implants was estimated using Kaplan-Meier estimator. All complications, reoperations, and failures were analyzed. Subjective and clinical outcomes (Subjective Hip Value, Western Ontario and McMaster Universities Osteoarthritis Index, and Harris Hip Score) were measured.

RESULTS

Of 256 patients (275 hips, 143 men and 113 women) with a mean age of 63 (range, 24-85) years, 48 (19%) patients (52 hips) deceased not related to the surgery after a mean time 49 months (range, 3-118) postoperatively. At >10-year follow-up, 9 THAs were revised. The overall implant survival rate was 96.8% (95% confidence interval, 94.4-98.7) at 10 years. One cup and 1 stem were revised because of aseptic loosening. At the last follow-up, the median Subjective Hip Value was 90% (range, 20-100), the Western Ontario and McMaster Universities Osteoarthritis Index score reached a median of 0.2 points (range, 0-6.3), and the median Harris Hip Score points was 99 (range, 29-100).

CONCLUSION

Primary THA through an anterior minimal invasive approach with the mentioned implants showed low revision rates and good to excellent clinical outcome after at least 10 years.