Distribution of Bone Ongrowth in Metaphyseal Sleeves for Revision Total Knee Arthroplasty: A Retrieval Analysis

Cause for concern? Significant cement coverage in retrieved metaphyseal cones after revision total knee arthroplasty

BACKGROUND

Metaphyseal cones are used to manage bone loss in revision total knee arthroplasty with increasing popularity. Post-operative radiographs and explant procedures suggest that cement may extrude around the cone implant into the cone-bone interface and prevent biologic in- or on-growth. The purpose of this study was to perform a retrieval analysis to describe the pattern of direct cementation onto the porous surface area of metaphyseal cones.

METHODS

Eighteen tibial and femoral cones were identified in an institutional implant retrieval registry. Anterior, posterior, medial and lateral quadrants were digitally mapped for direct cementation, bone ongrowth and fibrous ongrowth were calculated as a percentage of the porous surface area. Plain radiographs from prior to cone explant were analyzed for the presence of cement in all four quadrants and compared with results of the retrieval analysis.

RESULTS

Mean bone ongrowth was 25%, direct cementation was 24% (31% in tibial cones) and fibrous ongrowth was 29% of the porous surface area of the retrieved cones. There were no significant differences when comparing patterns of bone or fibrous ongrowth or cementation between anterior, posterior medial and lateral porous surfaces for tibia cones, femoral cones or all cones grouped together. Plain radiographs significantly underestimated the amount of cement covering the cone (p = 0.02).

CONCLUSION

In this retrieval study, we found significant cement extrusion around the porous surface of metaphyseal cones in revision TKAs. Optimizing the cone-bone interface may reduce the risk of cement extrusion and theoretically reduce the risk of aseptic loosening.

Cementless Porous-Coated Metaphyseal Sleeves Used for Bone Defects in Revision Total Knee Arthroplasty: Short- to Mid-Term Outcomes

OBJECTIVES

While many studies have presented excellent short-term outcomes of the metaphyseal sleeves used in revision total knee arthroplasty (TKA), currently published mid-term results remain limited and some controversial issues remain unresolved. The purpose of this study was to investigate clinical and radiographic mid-term outcomes of the sleeves for the management of metaphyseal bone defects in revision TKAs.

METHODS

From 2015 to 2019, 44 patients (45 knees) who were operated with cementless porous-coated metaphyseal sleeve in revision TKA were included in this study. Bone defects were assessed according to Anderson Orthopaedic Research Institute Classification. On the tibial side, there were 37 type II and six type III, and with regards to the femur, 15 were type II, and four were type III. Through reviewing electronic records, data were collected, including baseline demographics, operative details, information of prothesis, and complications. Clinical and radiographic evaluations were performed, including Knee Society Scores (KSS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), range of motion (ROM), the radiolucent line, level of joint line, and implant survival rate. Statistical analysis was performed by paired t-test for clinical and radiographic indexes.

RESULTS

The mean follow-up time was 4.4 ± 1.4 years. During surgery, sleeve-related fractures were encountered in four (8.9%) knees, including incomplete tibial fracture of lateral cortex in one knee and of medial cortex in two knees, and longitudinal femoral metaphyseal fracture in one knee. Unions were achieved in all cases at the final follow-up. Significant improvements in KSS and WOMAC scores were found at the final follow-up, respectively, from 83.8 ± 29.1 to 152.9 ± 31.0 (t = -12.146, p < 0.001) and from 148.4 ± 42.3 to 88.1 ± 52.5 (t = 6.025, p < 0.001). The mean ROM improved from 88.7 ± 31.9° to 113.7 ± 13.7° (t = -5.370, p < 0.001). A 75 mm length of cementless stem was used in all patients and only one patient was identified as tibial end-of-stem pain. No sleeve-related revision occurred, and one patient was diagnosed with early postoperative infection and was treated with irrigation and debridement, polyethylene liner exchange, and appropriate antibiotic treatment. The overall implant survival was 97.8% with the endpoint reoperation and 100% with the endpoint revision. Osseointegration at the bone-sleeve interface was found in all patients and no loosening happened. Satisfactory alignment between 3° varus and 3° valgus was achieved in all but not in three patients.

CONCLUSION

The use of metaphyseal sleeves in the treatment of bone defects in rTKAs can provide stable fixation and significantly improve the clinical scores at the midterm follow-up. In addition, the rare occurrence of end-of-stem pain suggests routine use of cementless stems. Although there are chances of intraoperative fractures, it has no negative effect on outcome when managed properly.

Metaphyseal sleeves in revision total knee arthroplasties: Computational analysis of bone remodeling

BACKGROUND

Metaphyseal sleeves help maintain long term stability and reduce revision rate for aseptic loosening in total knee arthroplasty (TKA) revision. However, their performance regarding bone remodeling is still poorly known for the long term. This study aimed to investigate the impact of metaphyseal sleeves on the bone remodeling of the tibia.

METHODS

Five finite element models of a female tibia with different implant configurations (regarding stem length and metaphyseal sleeve application) were developed. Loading conditions included joint reaction force, muscle, and tibia-fibula loads from 6 instances of the gait cycle. The bone remodeling model applied was adapted to the subject under analysis by selecting the bone remodeling parameters that best replicated the bone density distribution of the tibia estimated from the CT data. Changes in bone density after TKA were evaluated in 8 regions of interest.

RESULTS

Global bone loss ranged from -31.16%, in 115 mm stemmed configurations, to -20.93%, in 75 mm stemmed configurations. Apart from the lateral and posterior regions in the proximal tibia, whose bone loss reduced and increased, respectively, due to the incorporation of a metaphyseal sleeve, changes in bone density were similar with and without a metaphyseal sleeve for each stem length.

CONCLUSION

The results suggest that bone remodeling of the tibia is not critically affected by the incorporation of metaphyseal sleeves. Considering that sleeves are believed to present a favorable clinical outcome in stability and osseointegration, reducing the revision rate for aseptic loosening, their advantages seem to outweigh their disadvantages regarding bone remodeling.

Tibial metaphyseal sleeves in primary total knee arthroplasty following high tibial osteotomy and tibial plateau fracture; preliminary mid-term survival and outcome

BACKGROUND

Previous high tibial osteotomy (HTO), and tibial plateau fractures (TPF) may cause problems in subsequent total knee arthroplasty (TKA) due to altered metaphyseal bone structure. Higher rates of loosening of the tibial component have been described. In post-HTO and TPF cases, a more durable fixation could be achieved by tibial sleeves. This study investigates the preliminary short-to-midterm clinical and radiographic results in a cohort of these cases.

METHODS

A cohort of 28 patients was selected, 11 following HTO, and 17 following TPF. Standard clinical and radiologic follow-up was performed at 6 weeks, and one and two years. Revision with removal of primary prosthesis for any reason was the primary outcome. Patient reported pre- and postoperative pain, satisfaction and general health scores were collected at one and two years. Postoperative radiographs were analyzed for radiolucent lines.

RESULTS

There were no cases of aseptic loosening. Survival for all reasons was 96.4% (CI 77.2%-99.5%). One progressive radiolucent line was seen. Numerical rating scale (NRS) for pain with and without weightbearing at 2-year follow-up improved from 8 to 3 and from 5 to 2 points respectively. Overall general health scores improved with a median of 70 at ≥ 2 years, compared to 63 pre-operatively.

CONCLUSION

With no revision for aseptic loosening the use of tibial sleeves in primary TKA seems a safe and reliable method for fixation of the tibial component in metaphyseal bone with altered bone structure at short and mid-term follow-up.

LEVEL OF EVIDENCE

Level IV, cohort study.

Metaphyseal Sleeve Failure in Revision Total Knee Arthroplasty

Introduction

A significant percentage of patients require re-revision surgery regardless of the demonstrated durable short- and mid-term clinical results using metaphyseal sleeves in revision total knee arthroplasty (TKA). The aim of this study was to identify the association between sleeve alignment and contact zones, with loosening in patients with revision TKA.

Materials & Methods

Of a series of 103 patients who underwent revision TKA, at a mean follow-up of eight years, six patients were re-revised for tibial loosening. These patients were compared with 19 unrevised control subjects in a 1:3 ratio. We calculated and compared the cumulative number of contact zones between the porous-coated part of the sleeve and bone on immediate postoperative X-rays between re-revised and unrevised patients. The main hypothesis was that neutral positioning and absolute circumferential contact between trabecular metaphyseal bone and porous-coated part of the sleeve would lead to a better outcome.

Results

The use of a conservative (nonparametric) approach indeed revealed better circumferential contact between trabecular metaphyseal bone and porous-coated part of the sleeve among the survivors, i.e., survivors: median (interquartile range [IQR]): 3 (2-4); failures: 3 (1-3), p = 0.003 (Mann-Whitney [MW] test). The difference was borderline significant for coronal alignment, i.e., survivors: median (IQR): −1 (−4 to 2); failures: 0 (−1 to 3), p = 0.0569 (MW test).

Conclusion

A circumferential bony contact of the metaphyseal sleeve would lead to better survival of the revision implant, whereas the degree of varus fixation did not seem to influence the longevity of the implant.

Is stemless implant fixation a valid option in total knee revision arthroplasty - Review of in vitro and in vivo studies

Metaphyseal sleeves have shown an improved fixation in Revision Total Knee Arthroplasty (R-TKA) leading to a reduced aspetic loosening rate compared to other stem based fixation options. In the majority of these studies sleeve have been used with stems. Due to that is was not clear how much of this improved fixation could be rated to the sleeve and how much to the additional sleeves. In this review article we analysed the results of sleeve-only obtained in in-vitro or in-vivo studies. In Vitro models showed independent of the set-up a dominant fixation of the sleeve, an additional stem was not adding a lot to the overall fixation. Undersized additional stems showed an increased micromotion and the stem tip, while distal engaging stems showed a proximal stress shielding effect. Very interestingly an increased BMI had not a significant effect on primary fixation of the sleeve. Reduced bone quality on the other hand had and this effect was increased in cases with an increased BMI. In vivo results of sleeve-only patients showed comparable good results to sleeve and stem constructs. In particular on the femoral side the use of an additional stem is required only in a few scenarios. It has to be stated that the numbers of sleeves-only in rotating hinges is too low, to give any recommendation for this high constraint implants. Majority of cases was done with PS and VVC constraint. So far no in vivo data exist on the limitations of sleeve-only in patients with reduced bone quality and increased body weight. In conclusion we can state, that Sleeve-only is an option for R-TKA. In majority of cases the aspetic loosening rate is as low as with additional stems. The borderlines in terms of constraint, bone quality and body weight need to be investigated in future in vivo studies. The in vitro results look so far encouraging.

Role of metaphyseal sleeves in revision total knee arthroplasty: Rationale, indications and long-term outcomes

Metaphyseal sleeves have become an integral part of surgeons' armamentarium in dealing with complex revision knee arthroplasty. They offer the advantages of addressing bone defects with biological fixation techniques, efficient surgical preparation providing a stable tibial platform which optimises joint line positioning and gap balancing leading to excellent long-term survivorship and clinical outcomes. Here, we review the concept of metaphyseal fixation, indications of metaphyseal sleeves and their limitations with our surgical tips on how to remove well-fixed sleeves. We also present our tertiary experience and review clinical outcome studies of metaphyseal sleeves in revision knee arthroplasty literature.

Femoral revision knee Arthroplasty with Metaphyseal sleeves: the use of a stem is not mandatory of a structural point of view

PURPOSE

Although metaphyseal sleeves are usually used with stems, little is known about the exact contribution/need of the stem for the initial sleeve-bone interface stability, particularly in the femur, if the intramedullary canal is deformed or bowed. The aim of the present study is (1) to determine the contribution of the diaphyseal-stem on sleeve-femur interface stability and (2) to determine experimentally the strain shielding effect on the metaphyseal femur with and without diaphyseal-stem. It is hypothesised that diaphyseal-stem addition increases the sleeve-femur interface stability and the strain-shielding effect on the metaphyseal femur relatively to the stemless condition.

MATERIAL AND METHODS

The study was developed through a combined experimental and finite-element analysis approach. Five synthetic femurs were used to measure cortex strain (triaxial-rosette-gages) behaviour and implant cortex micromotions (Digital Image Correlation) for three techniques: only femoral-component, stemless-sleeve and stemmed-sleeve. Paired t-tests were performed to evaluate the statistical significance of the difference of cortex strains and micromotions. Finite-element models were developed to assess the cancellous bone strain behaviour and sleeve-bone interface micromotions; these models were validated against the measurements.

RESULTS

Cortex strains are significantly reduced (p < 0.05) on the stemmed-sleeve with a 150 μstrain mean reduction at the medial and lateral distal sides which compares with a 60 μstrain mean reduction (p > 0.05) on the stemless condition. Both techniques presented a mean cancellous bone strain reduction of 700 μstrain (50%) at the distal region and a mean increase of 2500 μstrain (4x) at the sleeve proximal region relative to the model only with the femoral component. Both techniques presented sleeve-bone micromotions amplitude below 50-150 μm, suitable for bone ingrowth.

CONCLUSIONS

The use of a supplemental diaphyseal-stem potentiates the risk of cortex bone resorption as compared to the stemless-sleeve condition; however, the stem is not essential for the enhancement of the initial sleeve-bone stability and has minor effect on the cancellous bone strain behaviour. Based on a purely structural point view, it appears that the use of a diaphyseal-femoral-stem with the metaphyseal sleeve is not mandatory in the revision TKA, which is particularly relevant in cases where the use of stems is impracticable.