Total knee arthroplasty with fully porous-coated stems for the treatment of large bone defects

Enhanced osseointegration through direct energy deposition porous coating for cementless orthopedic implant fixation

Direct energy deposition (DED) is a newly developed 3D metal printing technique that can be utilized on a porous surface coating of joint implants, however there is still a lack of studies on what advantages DED has over conventional techniques. We conducted a systematic mechanical and biological comparative study of porous coatings prepared using the DED method and other commercially available technologies including titanium plasma spray (TPS), and powder bed fusion (PBF). DED showed higher porosity surface (48.54%) than TPS (21.4%) and PBF (35.91%) with comparable fatigue cycle. At initial cell adhesion, cells on DED and PBF surface appeared to spread well with distinct actin stress fibers through immunofluorescence study. It means that the osteoblasts bind more strongly to the DED and PBF surface. Also, DED surface showed higher cell proliferation (1.27 times higher than TPS and PBF) and osteoblast cell activity (1.28 times higher than PBF) for 2 weeks culture in vitro test. In addition, DED surface showed better bone to implant contact and new bone formation than TPS in in vivo study. DED surface also showed consistently good osseointegration performance throughout the early and late period of osseointegration. Collectively, these results show that the DED coating method is an innovative technology that can be utilized to make cementless joint implants.

Primary complex total knee arthroplasty with severe varus deformity and large bone defects: mid-term results of a consecutive series treated with primary implants

INTRODUCTION

In recent years, the use of constrained implants in complex primary TKA has gained popularity since these implants may better and more easily address severe instability present in complex primary cases (CPC). However, the need for a constrained TKA in CPC is controversial. We hypothesized that a standard TKA may be successful in most of CPC and that an intraoperative switching to a constrained device is rarely need even in the presence of severe instability and bone loss.

MATERIALS AND METHODS

A consecutive series of 24 CPC (28 knees) were analysed retrospectively. Inclusion criteria were a femoro-tibial angle > 12° and bone defect of grade 2-3 (group 1). Forty-eight patients (52 knees) were analysed as controls (group 2). Patients were followed up clinically and radiographically up to a minimum of 5 years.

RESULTS

In group 1, a PS was used in 24 knees and a CR in 4. In no patient, a CCK or RHK was implanted. Bone defect was treated with bone cement plus cortical screws in 15 knees (53.5%), a medial wedge in 8 (28.5%), a medial wedge plus bone grafting with cancellous screws in 5 (17.8%). Metaphyseal sleeve or cone was not used. At the last follow-up, no significant difference was found in the clinical scores between the 2 groups.

CONCLUSION

In CPC with marked varus deformity, instability and bone loss, the use of primary TKA is associated with a clinical outcome comparable to standard cases. Ligamentous balancing may be addressed using primary implants and simple cost-effective techniques may be used to manage an extensive bone loss. In most CPC, an intraoperative switching to a constrained device is not necessary.

TKA-Revision with maintenance of well-fixed metaphyseal sleeves: Indications and surgical technique

Due to the compromised bone situation revision implants need extended fixation options in order to achieve good long-term survival. Over decades this has been achieved with stems, either cemented or uncemented. In the last decade additional fixation options in terms of cementless metaphyseal sleeves or metaphyseal cones have been introduced and widely accepted. Revision of such implants is challenging, in particular if those porous coated parts are well integrated. Therefore, partial revision leaving the well-fixed parts in place can be an option if the indication is allowing it. This can help to preserve bone. In this study we show 2 cases with metaphyseal sleeves, in which we demonstrate when and how revision can be performed leaving sleeves in place. Meticulous pre-Op analysis of the failure mechanism is mandatory to find those few cases in which a partial revision can be recommended. In our cases, it was one patient with persistent tibia stem pain and another patient with secondary instability. In both cases implant fixation was not the problem, and therefore leaving the well-fixed sleeves in place was considered. Before final decision was made, specific information on implants sizes and constraint are needed. In our tibial revision stem thickness was less than 14 mm decision, in this situation the stem can be removed through the sleeve, leaving the sleeve in place. The technique how to do it, is shown in this study. In the second case a traumatic MCL rupture was leading to a secondary instability, needing a revision from a VVC constraint to a rotating hinge. Again, pre-Op analysis and the surgical technique of femoral component removal are described. In the great majority of cases a full revision with complete implant removal is required. In a few cases a partial revision with maintenance of implant parts can be considered but only after careful analysis of the failure mode. Even if the failure mode allows a partial revision specific implant information need to be obtained to clarify whether it is really possible. If it is possible, a specific surgical technique is recommended and described in this study.

Porous-coated metaphyseal sleeves and MBT implant for severe bone loss in revision total knee arthroplasty: a mean 2.4-year follow-up

Background

Porous-coated metaphyseal sleeves are designed to fill bone loss and facilitate osseo-integration when bone loss occurs during revision total knee arthroplasty (TKA). The purpose of this paper was to evaluate the clinical and radiographic outcomes of porous-coated metaphyseal sleeves for severe bone loss in revision TKA.

Methods

Form December 2014 to March 2018, we retrospectively analyzed 36 patients receiving revision TKAs. They had Anderson Orthopaedic Research Institute (AORI) Type II and III tibial bone loss and were treated with metaphyseal sleeve. The patients were followed up for a mean time of 28.5 months. The Knee Society Score (KSS), the Hospital for Special Surgery (HSS) Knee Score, Visual Analog Scale (VAS) score and the range of motion (ROM), radiographic findings of sleeve osteo-integration were also recorded. The paired t test was used to compare the KSS, the HSS knee score and VAS score before and after the revision TKAs. A value of P < 0.05 was considered statistically significant.

Results

Thirty-six patients had complete clinical and radiographic data. At the final follow-up (mean: 28.5 months), significant improvements in knee range of motion, KSS, HSS score and VAS score were observed postoperatively (P < 0.001 for all). No aseptic implant fixation failure occurred. Radiographic reviews at the final follow-up revealed that components were stable without occurrence of component migration or clinically significant osteolysis.

Conclusions

This short-term retrospective study illustrated that porous-coated metaphyseal sleeves were useful in revision TKA, with a low rate of intraoperative complications, excellent osteo-integration and stable fixation.

Cementless Metaphyseal Sleeve Fixation in Revision Knee Arthroplasty: Our Experience with an Arabic Population at the Midterm

OBJECTIVE

Metaphyseal sleeve (MS) fixation in revision knee arthroplasty (RKA) among Western populations has been reported with very encouraging outcomes. The aim of this study was to report our experience with the use of MS in RKA among an Arabic population. Clinical and radiographic outcomes and implant survivorship were reported at a minimum follow-up of 2 years and a mean follow-up of 4.1 years.

METHODS

A retrospective analysis was conducted on prospectively collected data of patients who underwent RKA with a MS in combination with a cementless stem (femoral or tibial). Range of motion (ROM) and Knee Society Score (KSS) were obtained pre- and postoperatively. Complications, occurrence of stem-tip pain, and implant survival were documented. Knee radiographs were obtained to evaluate the alignment and osseointegration or loosening of the MS.

RESULTS

A total of 52 sleeves (27 tibial and 25 femoral) implanted in 27 RKAs (27 patients) were included. The mean follow-up period was 4.1 ± 1.8 (2-7.5) years. Postoperatively, the ROM improved from 89.3 ± 9.2 to 106.3 ± 11.4 (p = 0.19) and the KSS also significantly improved, from 102.9 ± 35.6 to 130.2 ± 33.7 (p < 0.001). One patient (3.7%) developed heterotopic ossification, and another one (3.7 %) had a stem-tip pain on the tibial side; both were managed conservatively. One patient (3.7 %) sustained a fracture and required reoperation. None of the sleeves showed progressive radiolucent lines, and none required revision. The aseptic survivorship and overall survivorship at a mean of 4.1 years were 100% and 96.3%, respectively.

CONCLUSION

MS provided successful midterm outcomes that were maintained in obese patients with different levels of constraint. Our series supports their use as a viable option in RKA.

The metaphyseal sleeve: an unexplored option in the treatment of complex primary knee osteoarthritis

BACKGROUND

In an ever-aging society that as a whole has become more affluent, significant emphasis has been accorded to an improved quality of life. Knee osteoarthritis is ever-increasingly treated with total knee arthroplasty. The benefits and satisfaction experienced by those who have undergone total knee replacements (TKR) are well documented in the literature. The issue arises when osteoarthritis of the affected knee is more complex than simple osteoarthritis, i.e. the patient has complex primary osteoarthritis. This collective term encompasses conditions such as massive bone loss, ligamentous laxity, coronal defects and those with contractures. There are various classifications to describe massive bone loss but we utilized the Anderson Orthopaedic Research Institute (AORI) classification. Numerous treatment options are available and we report the use of metaphyseal sleeves as a highly successful treatment option.

METHODS

We retrospectively reviewed all the patients at our centre who underwent primary TKR using the metaphyseal sleeves. Patients were assessed on symptoms and functional status, and radiographs were also taken to assess for osseointegration. Only patients who completed 2 years of follow up were included in our study.

RESULTS

The updated (2011) Knee Society Score (KSS) was used in conjunction with radiological assessments at each follow up. Mean KSS scores improved from 53.83 preoperatively to 193.39 postoperatively. All patients demonstrated increasing osseointegration throughout follow up.

CONCLUSION

The metaphyseal sleeve is an excellent treatment option for complex primary osteoarthritic knees with good results objectively, functionally and radiologically and would be a great choice for all orthopaedic surgeons to include in their armamentarium.

Extraction of total knee arthroplasty intramedullary stem extensions

Intramedullary stem extensions will need to be extracted during total knee arthroplasty (TKA) revisions, especially repeated ones. These stems have various designs and lengths, can be straight or offset, cemented (partially or totally) or cementless, smooth or rough. This diversity adds to the difficult of extracting them, which the surgeon must anticipate before starting the revision procedure. Porous metaphyseal metal components (cones, sleeves) are being used increasingly during revision TKA. They pose specific extraction challenges and complicate the extraction of the stems with which they are often associated. The maneuvers used during extraction have a direct impact on the subsequent joint reconstruction methods. These procedures are always long and difficult, with an increased risk of bone-related complications (perforation, fracture) or infection. They must always be carried out at specialized centers by experienced surgeons. The reasons for re-revision are the same as those for TKA revision, mainly aseptic loosening, instability and infection-only the latter requires that all components be removed. The local conditions are often unfavorable: epiphyseal-metaphyseal bone defect, thin cortices, osteoporosis, and in some cases, stiffness. The type of implant to extract and its characteristics must be identified beforehand in case special instruments are needed. An imaging workup is done to specify the relationship of the stem with bone, quality of its fixation, bone lesions and gaps between stem and bone, knowing that extraction is harder when the gaps are smaller. A combination of extended radiolucent lines, purely metaphyseal fixation, and a thin smooth stem may mean that intramedullary extraction is feasible. The extensor mechanism must be released to achieve sufficient exposure. If a tibial tubercle osteotomy is needed, it must be sized to match the extraction. After disassembly of femoral and tibial components-which can be challenging-the epiphyseal components must be released. High performance instruments for cement extraction and metal cutting are essential. Other than simple cases (loosened or partially fixed implants), intramedullary extraction can be dangerous especially when the stem extension is well-fixed, whether cemented or not. A diaphyseal window may be sufficient, but in most cases, an extended osteotomy is needed. This includes detaching the tibial tubercle at the tibia. At the femur, this may require an anterior midline window, an anterior extended ostéotomy or an anterolateral oblique distal femoral osteotomy with fibrous hinge. The extraction of metaphyseal porous components is difficult. Their connection with the bone must be broken - which can be long and risky - before the associated stem is removed. While it is easier to extract when the stem can be removed first, it is not always feasible. Reconstruction depends intimately on the methods used to extract the existing implants. Any diaphyseal discontinuity must be bridged (long stem or plate). The extent of the resulting bone defect after extraction drives the revision methods, which are simplified by using porous metaphyseal metal components and shorter stems when possible.

Bone Loss in Revision Total Knee Arthroplasty: Evaluation and Management

With the increasing number of total knee arthroplasty (TKA) procedures being performed annually, the burden of revision surgery is also expected to increase. Addressing bone loss during revision TKA is a considerable challenge that requires proper preoperative evaluation and surgical planning. In addition to an assessment of femoral and tibial bone loss, a systematic approach to the management of bone loss associated with TKA includes careful implant selection, adherence to the general principles of revision TKA, and an understanding of the available reconstruction options. These options include cement with screws, morcellized allograft, bulk structural allograft, modular wedges, block augments, porous metal cones or sleeves, and megaprostheses.

Tapered modular fluted titanium stems for femoral fixation in revision total knee arthroplasty

Consensus regarding femoral stem fixation options in revision total knee arthroplasty remains controversial. Tapered, modular, fluted titanium (TMFT) stems have an excellent track record in total hip arthroplasty for their ability to provide axial and rotational stability in situations of compromised host bone. We present 3 successfully treated cases in which the Food & Drug Administration granted permission to use custom TMFT stems in situations of failed femoral fixation in multiple revised knees. These stems hold promise to achieve stable fixation in revision total knee arthroplasty where host metadiaphyseal bone is deficient. Implant manufactures should consider dedicating future resources to create adapters that can link existing successful TMFT stems currently used in hip arthroplasty to revision total knee components when host bone is severely compromised.

Knee arthrodesis with a long intramedullary nail as limb salvage for complex periprosthetic infections

BACKGROUND

Periprosthetic infection following total knee arthroplasty is a devastating complication, which is not always satisfactorily resolved by revision surgery. Arthrodesis is a salvage alternative to above-knee amputation or permanent resection arthroplasty. Fixation options include internal compression plating, external fixation, and intramedullary nails.

METHODS

We retrospectively reviewed twelve consecutive cases (9 males, 3 females; mean age, 67 years) of knee arthrodesis with a long intramedullary nail, performed at a single institution between 2003 and 2014. Desired outcomes were the ability to mobilize without pain, solid radiographic fusion, and the eradication of infection.

RESULTS

Mean follow-up was 48.5 months (range, 9-120 months). Eleven patients (92 %) demonstrated stable fusion, ten patients (83 %) were ambulatory without pain, and ten patients (83 %) remained without infection at most recent follow-up. Eight patients (67 %) achieved union at an average of 12 months; three required repeat procedures, achieving union at an average of 9 months. There was a significant difference (P < 0.01) between the numbers of previous operations amongst the eight patients who initially achieved union (mean, 3.25) and three who subsequently required repeat procedures (mean, 8.33).

CONCLUSIONS

In contrast to similar studies, we performed a single-stage exchange where possible, while comparable ambulatory and fusion rates were observed. Numerous previous attempts at revision arthroplasty, co-morbidities, and infections with highly resistant organisms have been associated with further complications. Although technically challenging, knee arthrodesis with a long intramedullary nail offers an acceptable limb salvage procedure for carefully selected patients with complex periprosthetic infections.

Metal metaphyseal sleeves in revision total knee replacement

Bone loss in the proximal tibia and distal femur is frequently encountered in revision knee replacement surgery. The various options for dealing with this depend on the extent of any bone loss. We present our results with the use of cementless metaphyseal metal sleeves in 103 patients (104 knees) with a mean follow-up of 43 months (30 to 65). At final follow-up, sleeves in 102 knees had good osseointegration. Two tibial sleeves were revised for loosening, possibly due to infection. The average pre-operative Oxford Knee Score was 23 (11 to 36) and this improved to 32 (15 to 46) post-operatively. These early results encourage us to continue with the technique and monitor the outcomes in the long term.