Reconstruction of Massive Bone Defects with Allograft in Revision Total Knee Arthroplasty*

Fabrication and Evaluation of PCL/PLGA/β-TCP Spiral-Structured Scaffolds for Bone Tissue Engineering

Natural bone is a complex material that has been carefully designed. To prepare a successful bone substitute, two challenging conditions need to be met: biocompatible and bioactive materials for cell proliferation and differentiation, and appropriate mechanical stability after implantation. Therefore, a hybrid Poly ε-caprolactone/Poly(lactic-co-glycolide)/β-tricalcium phosphate (PCL/PLGA/β-TCP) scaffold has been introduced as a suitable composition that satisfies the above two conditions. The blended PCL and PLGA can improve the scaffold's mechanical properties and biocompatibility compared to single PCL or PLGA scaffolds. In addition, the incorporated β-TCP increases the mechanical strength and osteogenic potential of PCL/PLGA scaffolds, while the polymer improves the mechanical stability of ceramic scaffolds. The PCL/PLGA/β-TCP scaffold is designed using spiral structures to provide a much better transport system through the gaps between spiral walls than conventional cylindrical scaffolds. Human fetal osteoblasts (hFOBs) were cultured on spiral PCL/PLGA/β-TCP (PPBS), cylindrical PCL/PLGA/β-TCP (PPBC), and cylindrical PCL scaffolds for a total of 28 days. The cell proliferation, viability, and osteogenic differentiation capabilities were analyzed. Compared with PCL and PPBC scaffolds, the PPBS scaffold exhibits great biocompatibility and potential to stimulate cell proliferation and differentiation and, therefore, can serve as a bone substitute for bone tissue regeneration.

Metaphyseal cones combined with diaphyseal impaction grafting provide good outcomes and survival in a complex revision total knee arthroplasty: a matched comparative analysis

PURPOSE

To compare clinical and radiological outcomes, implant survivorship at a minimum of 1-year follow-up using metaphyseal trabecular cones with or without impaction grafting in a complex revision TKA.

METHODS

A retrospective comparative matched analysis was performed and 15 patients who underwent revision surgery using the combination of porous trabecular metaphyseal cone and diaphyseal impaction grafting (MC-IBG) were matched with a group of 13 patients who also underwent revision surgery using metaphyseal cone (MC) without impaction grafting. All included patients presented severe bone defect (AORI 2,3) and a rotating-hinge prosthesis were implanted.

RESULTS

Both groups were comparable regarding the baseline demographic and clinical data. Patients had previously undergone a mean of 4 (range, 2-12) and 3 (range, 2-5) previous procedures in the MC-IBG and MC groups, respectively. The indications for revision were aseptic loosening in 11 (73.3%) and 11 (84.6%) patients; prosthetic joint infection in 4 (26.7%) and 2 (15.4%) in the MC-IBG and MC groups, respectively. There was no significant difference in the mean postoperative Knee Society Score between the study groups (p = 0.806). Overall, 4 patients had further revision. Two patients were revised in the MC-IBG group, one patient for aseptic loosening and the second one after 2 episodes of instability. Two patients in the MC group presented prosthetic joint infection and underwent a two-stage reimplantation. No significant difference was observed between the study groups at comparison (p = 0.92).

CONCLUSION

Trabecular metal cones with diaphyseal impaction grafting provide an alternative technique in a complex revision TKA surgery with early clinical and radiographic success.

Utilization of a Revision Acetabular Shell as a Tibial Cone in a Revision Total Knee Arthroplasty Setting

One of the biggest challenges of a revision total knee arthroplasty is how to obtain adequate tibial metaphyseal fixation in the setting of significant bone loss. There are multiple implants, including stems, metaphyseal cones, and metaphyseal sleeves, that help provide increased fixation and stability. This report demonstrates a case in which a porous tantalum metal revision acetabular shell was used as a large tibial cone, as none of the above options were viable due to the size and position of the tibial defect.

Revision Total Knee Arthroplasty Utilizing Threaded Pins in Cement for Tibial Bone Loss

Introduction: a primary goal in revision total knee arthroplasty is to recreate and restore near-normal knee biomechanics by reapproximating the native anatomy. Tibial bone loss poses a challenge for surgeons. Bone cement, bone allograft, screws-in-cement, metaphyseal sleeves or cones, and metallic augments are some options for addressing bony deficiency, with endoprosthetic proximal tibia replacement a consideration for the most severe cases. Case Description: we present a case for the novel use of threaded Steinmann pins augmented with cement to reconstruct a massive tibial metaphyseal cortical defect during revision knee arthroplasty. A 76-year-old male presented with an infected primary total knee arthroplasty using MSIS (Musculoskeletal Infection Society) criteria and underwent a standard two-stage revision total knee arthroplasty once the knee was confirmed sterile. Intraoperatively, significant posteromedial and metaphyseal tibial bone loss was identified. In order to avoid proximal tibial replacement and the extensor mechanism complications seen with these, coupled with obligate gastrocnemius flap, a metaphyseal cone was utilized in the proximal tibia with four vertical threaded Steinmann pins spaced approximately 1 cm apart at its periphery, subsequently cut flush with the level of the cone after cementation to recreate the tibial cortex. The patient's function and range of motion continue to improve with no evidence of structural complication at 2.5 years of follow-up. Discussion: the implementation of threaded Steinmann pins was utilized in this case to stabilize a cemented metaphyseal cone in the revision of an infected total knee with significant tibial bone loss. The threaded property may help prevent migration of these pins in comparison to smooth pins. Creation of a stable platform in a revision total knee arthroplasty poses a substantial challenge in the context of significant bone loss, and our case depicts a good short-term outcome and another option for surgeons to consider before moving toward endoprostheses.

Tibial periprosthetic fractures in Total Knee Arthroplasty - A scoping review

Background

Periprosthetic tibial fractures in Total Knee Arthroplasty are much less commonly seen than femoral fractures, and there is a paucity of available literature and management recommendation for these fractures. We aimed to identify the relevant and up-to-date literature on this subject to analyse the incidence, risk factors, and management recommendations.

Methods

A literature search was done on the databases of PubMed and SCOPUS using appropriate keywords. All the published literature in the English language was included for this review.

Results

We included 21 studies comprising 260 tibial periprosthetic fractures (91 intra-operative (35%) and 169 (65%) post-operative or delayed fractures). Only 5.9% of these fractures were managed conservatively. Whereas 98 cases (58%) were managed with open reduction and internal fixation (ORIF) with plating, 19 (11.2%) were managed with revision TKA. Seventeen cases (10%) were managed with minimally invasive percutaneous plate osteosynthesis (MIPPO), and 8 (4.7%) were managed with intramedullary nailing. Less than 6% of cases were managed with other means, viz. megaprosthesis (n = 4), arthrodesis (n = 5), amputation (n = 1), and external fixator (n = 1).

Conclusion

Intraoperative fractures accounted for one-third of the fractures in our review. A majority of the delayed periprosthetic fractures were treated with surgical intervention. The most preferred surgical treatment method was ORIF of fractures using locking plates (either open or MIPPO). Revision TKA or megaprosthesis was used in cases with the loosened implants in association with the fracture.

Level of evidence

IV.

Comparison of Different Strategies in Revision Arthroplasty of the Knee with Severe Bone Loss: A Systematic Review and Meta-Analysis of Clinical Outcomes

BACKGROUND

In revision total knee arthroplasty large bone lesions can jeopardize correct implant orientation and fixation. Different strategies have been proposed to tackle this issue. The purpose of this review and meta-analysis is to evaluate the midterm clinical and survivorship results of porous cones and porous-coated sleeves compared to morselized and structural grafts.

METHODS

We performed a systematic review of the literature on the different strategies targeting moderate to large metaphyseal bone defects. The literature was evaluated for methodological quality. We analyzed results on survivorship using logistic regression correcting for follow-up time and number of knees. We compared these results using forest plots for early and midterm follow-up. Clinical outcome was evaluated by comparing standardized mean difference of patient-related outcome measures.

RESULTS

A total of 77 articles analyzing 4,391 knees were included. The logistic regression curve showed a nonsignificant odds ratio (OR) at 10 years of 0.91 (95% confidence interval [CI] 0.699-1.192, P = .49) for failure comparing all porous implants with all grafting procedures. The available clinical reports show a bigger standardized mean difference increase for tantalum cones (OR 3.04, 95% CI 1.71-4.37) than for porous sleeves (OR 1.72, 95% CI 0.88-2.57).

CONCLUSION

Our analysis shows that the size and quality of the literature on metaphyseal bone defects is progressively improving. Porous implants are effective in tackling metaphyseal bone defects showing good survivorship outcome at midterm follow-up. In younger patients with less constrained prosthetic implants, surgeons might still consider the use of grafts without risking worse outcomes.

A Review of Periprosthetic Tibial Fractures: Diagnosis and Treatment

Periprosthetic fracture occurring during or after total knee arthroplasty is a rare injury. Literature concerning periprosthetic tibial factures is sparse, and there is limited guidance for evidence-based management. This review aims to provide readers with an overview of the epidemiology, risk factors, and classification of these fractures. Management includes nonoperative treatment of nondisplaced fractures, fixation for those with stable implants, and revision for those with loose implants.

What Is the Survival of the Telescope Allograft Technique to Augment a Short Proximal Femur Segment in Children After Resection and Distal Femur Endoprosthesis Reconstruction for a Bone Sarcoma?

BACKGROUND

Large, malignant bone tumors and revision limb salvage procedures often result in the resection of extensive lengths of the involved bone segment, leaving a residual segment of bone that may be too short to support a standard intramedullary stem for endoprosthetic reconstruction. Telescope allografting, in which an allograft is used to augment the remaining bone segment by telescoping it into the residual bone segment, was described for situations in which residual bone stock is insufficient after tumor resection or prosthetic revision. Apart from one study that first described the procedure [15], there are no other studies reporting the outcome of this telescopic concept for restoring bone stock.

QUESTIONS/PURPOSES

For patients younger than 18 years who underwent the telescopic allograft technique to augment a short segment of the proximal femur after resection of bone sarcomas who also underwent endoprosthesis reconstruction of the distal femur, we asked: (1) What is the survivorship free from removal of the telescopic allograft and the endoprosthetic stem at 7 years after surgery? (2) What proportion of these reconstructions will heal to the host bone without delayed union or nonunion? (3) What is the functional outcome based on the Musculoskeletal Tumor Society (MSTS) score?

METHODS

We retrospectively studied our institutional database and identified 127 patients younger than 18 years who underwent surgery for a primary malignant bone tumor of the distal femur between December 2008 and October 2018. After excluding 16 patients undergoing amputation and rotationplasty and 57 patients undergoing recycled autograft/allograft reconstruction, 54 patients who underwent primary or revision distal femur endoprosthesis reconstruction were identified. Among these patients, we considered 15 patients who underwent telescopic allograft augmentation of the femur for analysis. One patient was lost to follow-up before 2 years but was not known to have died, leaving 14 for analysis at a median (range) 49 months (24 to 136 months) of follow-up. The indications for telescopic allograft augmentation of the femur in our institution were a proximal femur length of less than 120 mm after resection or resection of more than two-thirds of the total length of the femur. Ten of 14 patients underwent telescopic allograft augmentation as a revision procedure (distal femur resorption in five patients, endoprosthesis stem loosening in three patients, implant fracture in one patient, and infection in one patient), and the remaining four patients underwent telescopic allograft augmentation as a primary limb salvage procedure for large malignant bone tumors of the distal femur. The histologic diagnosis in all patients was osteosarcoma. At the time of telescopic allograft augmentation and reconstruction, the median age of the patients was 14 years (7 to 18 years). The size and the type of bone allograft to be used (femoral shaft or proximal femur) was planned before surgery, with consideration of the extent of resection, level of osteotomy, diameter of the host bone at the osteotomy site, and approximate diameter of the endoprosthesis stem to be used. The segment of the cylindrical allograft used for telescoping was thoroughly washed, prepared, and impacted onto the native femur to achieve telescoping and overlap. Serial digital radiographs were performed once a month for the first 6 months after the procedure, every 2 months until 1 year, and then every 6 months thereafter. Two surgeons in the department (at least one of which was involved in the surgery) retrieved and reviewed clinical notes and radiographs to determine the status of the telescopic allograft and endoprosthesis stem. We defined delayed union as radiological union at the osteotomy site more than 6 months after the procedure without additional surgery; we defined nonunion as no radiological evidence of callus formation at the osteotomy site 9 months after the procedure, necessitating additional surgery. The reviewers did not disagree about the definition of healing time. None of the patients missed radiographic follow-up. Kaplan-Meier survivorship free from removal of telescopic allograft and the endoprosthesis stem at 7 years after surgery was estimated. Patient function was assessed using the 1993 version of the MSTS [9], as determined by chart review of the institutional database performed by one of the surgeons from the department.

RESULTS

The survivorship free from removal of the telescopic allograft and endoprosthesis stem at 7 years after surgery was 80% (95% confidence interval 22% to 96%). The allograft united with the host bone in 100% (14 of 14) of the patients. Though 21% (3 of 14) had delayed union, no nonunions were seen. The median (range) MSTS score at the final follow-up interval was 27 (22 to 30).

CONCLUSION

Although this is a small group of patients, we believe that allograft segments help augment short bone stock of the proximal femur after long-segment resections, and the telescopic technique seems to be associated with a low proportion of nonunion or delayed union, which is one of the most common complications of allografts. Maintaining an adequate length of the proximal femur is important in preserving the hip, and this technique may be especially useful for young individuals who may undergo repeated revision procedures.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Is constraint implant with metaphyseal sleeve a viable option for revision TKR with preoperative coronal plane instability and bone defect?

BACKGROUND

Metaphyseal sleeves have been used as metaphyseal filling implants to address bone loss during revision total knee replacements (TKRs). This study aims to compare the 2-year clinical and radiological outcomes of constraint implant with bone defect and constraint implant without or minimal bone defect in revisions TKR with preoperative coronal plane instability.

MATERIALS AND METHODS

Seventeen cases of constraint implants with metaphyseal sleeve matched paired with 34 cases of constrained condylar knee (CCK) prosthesis. Age, gender, body mass index and aetiology for revision surgery were recorded. Clinical outcome measures included Knee Society Knee Score (KSKS), Knee Society Function Score (KSFS), Oxford Knee Score (OKS), physical component summary (PCS) and mental component summary (MCS). Radiological outcome measures included joint line changes, hip-knee-ankle angle (HKA), coronal femoral angle (CFA) and coronal tibial angle (CTA).

RESULT

Patients in sleeve group showed significant improvement in KSKS, KSFS and OKS (38 ± 7, 35 ± 6 and 20 ± 2 points, respectively, p < 0.001), while they were 19 ± 3 and 6 ± 2 points for PCS and MCS, respectively (p < 0.001 and p = 0.021). These postoperative scores after surgery were similar between the two groups at 6 months and 2 years. The sleeve provides comparable result in joint line restoration; the postoperative HKA, CFA and CTA were all comparable between the two groups.

CONCLUSION

Metaphyseal sleeve with constraint implant is a viable option for revision TKR with preoperative coronal plane instability and significant bone defect. It is able to achieve similar clinical outcomes and joint line restoration compared to CCK prosthesis at 2-year follow-up.

Impaction Bone Grafting in Revision Total Knee Arthroplasty-Using Mesh and Cone to Contain the Defect: A Report of 3 Cases

Uncontained tibial bone defects are a challenge in revision total knee arthroplasty. The present study reports on the results of a modified surgical technique for impaction bone grafting using metaphyseal cones and wire mesh. Three patients (2 male, 1 female; average age: 71.3 years) underwent revision total knee arthroplasty. All patients presented with uncontained medial tibial bone defects, one of the patients with an additional posterior cortical tibial split fracture. All cases were treated with a metaphyseal cone and outside mesh to create a contained defect. Between the mesh and cone, fresh frozen cancellous chips mixed with β-tricalcium phosphate were impacted. No evidence of loosening or osteolysis was present at 3.6-year follow-up. Impaction bone grafting using an outside mesh and inside cone for defect containment provides a durable reconstruction of tibial bone defects.

A finite element analysis of tibial tritanium cones without stems in varying bone defects

BACKGROUND

In the UK around 10% of hip and knee arthroplasties are revision operations. At revision total knee arthroplasty (rTKA), bone loss management is critical to achieving a stable bone-implant construct. Though tritanium cones have been used to manage bone defects in rTKA, their biomechanical performance with varying defects remains unknown.

METHODS

Uncontained tibial bone defects at four anatomic locations, with varying depths and widths (Type T2A and T2B) were investigated computationally in a composite tibia which was subjected to four loading scenarios. The ability of the tritanium cone to replace the tibial bone defect was examined using the outcome measures of bone strain distribution and interface micromotions.

RESULTS

It was found that anterior and lateral defects do not significantly alter the strain distribution compared with intact bone. For medial defects, strain distribution is sensitive to defect width; while strain distributions for posterior defects are associated with defect width and depth. In general, micromotions at the bone-implant interface are small and are primarily influenced by defect depth.

CONCLUSIONS

Our models show that the cone is an acceptable choice for bone defect management in rTKA. Since all observed micromotions were small, successful osteointegration would be expected in all types of uncontained defects considered in this study. Tritanium cones safely accommodate uncontained tibial defects up to 10 mm deep and extending up to 9 mm from the centre of the cone. Medial and posteriorly based defects managed with symmetric cones display the greatest bone strains and asymmetric cones may be useful in this context.

Bearing thickness of unicompartmental knee arthroplasty is a reliable predictor of tibial bone loss during revision to total knee arthroplasty

BACKGROUND

Bone defects during revision procedures for failed UKA represent a challenge even for the most experienced surgeons; therefore, an accurate preoperative planning remains essential to prevent dramatic scenarios in the surgical theatre.

HYPOTHESIS

Our hypothesis is that bearing thickness used in original UKA represents a reliable predictor of severe tibial bone loss, requiring a metallic augment or constrained implant, during revision to TKA.

PATIENTS AND METHODS

Forty-two patients who underwent a total knee arthroplasty from failed UKA were identified from our institutional database and evaluated clinically using the Knee Society Score (KSS). A multivariate logistic regression analysis was performed using the presence of tibial augments or the need of varus-valgus constrained (VVC) prosthesis as depend variables, and patients' gender, age at revision procedure, side (medial or lateral), UKA tibial tray (all-polyethylene or metal back), bearing thickness (composite thicknesses of the metal-backed tray and insert or all-polyethylene tibial component ≤8mm or more than 8mm) and cause of failed UKA as independent variables.

RESULTS

A posterior-stabilized prosthesis was used in 27 cases (64.3%). An augment was necessary in 12 patients (28.6%). Initial bearing thickness greater than 8mm was associated with greater likelihood of a VVC implant (OR=11.78, 95% CI, 1.6583 to 83.6484, p=0.0137) and a tibial augment (OR=9.59, 95% CI, 1.327 to 69.395, p=0.0251). Tibial tray design, patients' gender or age during revision surgery, side or cause of failure were not associated to increased risk of augmentation or constrained implants.

DISCUSSION

Surgeons should be aware of the particular challenges that the conversion of a UKA to a TKA presents and be prepared to address them intraoperatively, with particular care to proper bone loss manage. Satisfying results can be achieved at mid-to-long term follow-up, if these procedures are planned accurately, and a precise analysis of failed UKA components, in particular bearing thickness, represents a helpful support in this context.

LEVEL OF EVIDENCE

IV, retrospective case series.

Metaphyseal Fixation Using Highly Porous Cones in Revision Total Knee Arthroplasty: Minimum Two Year Follow Up Study

BACKGROUND

Highly porous metaphyseal cones have been introduced to restore metaphyseal integrity for improved cement interdigitation to achieve durable fixation in revision total knee arthroplasty (TKA). The purpose of this study is to review the survivorship, clinical results, and complications of revision TKA using highly porous 3-dimensionally printed titanium metaphyseal cones.

METHODS

This is a review of 62 revision TKAs using metaphyseal tibial cones, with 15 cases utilizing both tibial and femoral cones. The mean age of the patients was 66 years (range 32-84) who had a mean follow-up of 27 months (range 24-34). There were 38 women and 24 men, who had a mean body mass index of 33 (range 18.3-62).

RESULTS

Revision-free survival of the cones was 90.2%. If infection was excluded, survivorship was 100%. There were no cases of aseptic loosening. The mean Knee Society Score improved from 51 points preoperatively to 80 points at the time of latest follow-up. The mean Knee Society Functional Score improved from 48 points preoperatively to 68 points. A total of 15 of the 62 patients (24%) required additional surgery: 10 (16%) for infection, 3 (5%) for contracture, 1 for patellar subluxation, and 1 for quadriceps tendon rupture.

CONCLUSION

Metaphyseal fixation is important for survivorship in revision TKA which can be challenging due to cancellous and structural bone loss encountered at the time of revision. Prosthetic joint infection continues to be the leading cause of failure in revision TKA. The use of highly porous titanium metaphyseal cones produced from 3-dimensionally printed technology used in this study demonstrated excellent short-term results with no cases of aseptic loosening. Further follow-up is required to determine if these results can be durable over a longer period.

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

BACKGROUND

The metaphyseal region of the bone has been recognized by its importance to the overall stability of a revision construct. Porous titanium metaphyseal sleeves to enhance biologic fixation can be used to manage bone loss encountered during revision total knee arthroplasty. While clinical results for metaphyseal sleeves are encouraging, there is little information on the extent to which biologic fixation is achievable with metaphyseal sleeves. We examined retrieved metaphyseal sleeves to determine the amount of bone ongrowth.

MATERIALS AND METHODS

We studied 14 tibial and 11 femoral retrieved metaphyseal sleeves from 16 typical arthroplasty patients. Prerevision radiographs were reviewed for the presence of biologic fixation to the sleeves and the stem canal fill ratio. Bone ongrowth was assessed regionally in the anterior, posterior, medial, and lateral areas of the retrieved implants.

RESULTS

Bone ongrowth covered on average 14.7 ± 3.4% of the entire porous surface of the tibial sleeves. The lateral and anterior surfaces had a significantly greater proportion (P < .05) of bone ongrowth compared with the posterior and medial surfaces of the tibial components. Bone ongrowth covered on average 21.3 ± 2.6% of the entire porous surface of the femoral sleeves. No differences were found in the proportion of bone ongrowth among the posterior, medial, lateral, and anterior surfaces of the femoral. No significant association was found between the clinical, demographic, or radiographic factors and the pattern or quantity of bone ongrowth.

DISCUSSION

This study demonstrates that sufficient fixation can be achieved with only limited amounts of bone ongrowth (14.7% in tibial sleeves and 21.3% in femoral sleeves).

Pre-clinical evaluation of bone allograft toughened with a novel sterilization method: An in vivo rabbit study

Bone allografts often undergo γ-irradiation sterilization to decrease infection risk. However this consequently degrades bone collagen and makes the allograft brittle. Our laboratory has previously found that pre-treatment with ribose ex vivo protects the bone. However, it remains unclear whether or not ribose-treated γ-irradiated allografts are able to unite and remodel in vivo. Using New Zealand White rabbits (NZWr), we aimed to evaluate if ribose-treated allografts can unite with host bone (compared to untreated (fresh-frozen) and conventionally-irradiated allografts). A critically-sized defect was created in the radii of NZWr and reconstructed with allografts fixed with an intramedullary Kirschner wire. Healing and union were assessed at 2, 6, and 12 weeks post operation, with radiographs, µCT, static and dynamic histomorphometry, backscatter electron microscopy, and torsion testing. Intramedullary fixation achieved stable reconstructions and bony union in all groups and no differences were found in the radiographic and biomechanical parameters tested. Interestingly, γ-irradiated allografts had significantly less bone volume due to evident resorption of the grafts. In contrast, ribose pre-treatment protected γ-irradiated allografts from this bone loss, with results similar to the fresh frozen controls. In conclusion, ribose-pretreated γ-irradiated allografts were able to unite in vivo. In addition to achieving bony union with host bone, ribose pre-treatment may protect against allograft resorption. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Periprosthetic Tibial Fractures

Periprosthetic fractures around total knee arthroplasty have become an increasingly common and challenging orthopaedic problem. Appropriate management of these fractures depends on careful scrutiny of radiographs and a thorough clinical history to exclude the diagnosis of a periprosthetic infection. In a periprosthetic tibial fracture with a stable, well-aligned tibial component and well-aligned mechanical tibial axis, the fracture can be successfully managed with closed reduction and cast immobilization; meticulous follow-up is essential to ensure that the alignment is maintained. Major fracture displacement, tibial component instability, and tibial component malalignment are all indications for surgical intervention. The ideal surgical intervention depends on the fracture characteristics and the stability and alignment of the tibial component.

Correlation of tibial bone defect shape with patient demographics following total knee revision

Background

Bone defects of the proximal tibia following revision total knee arthroplasty (TKA) are challenging to manage, but must be addressed to provide lasting stability. This paper will categorize tibial bone defects into shape groups and correlate resulting groups to patient demographic data.

Methods

Retrospective analysis of four hundred and four patients post revision TKA between January 2005 and February 2014 was conducted. One hundred and eighteen met the inclusion criteria and were subcategorized by defect shape on their post-operative lateral and anterior-posterior (AP) radiographs. The subgroups of defect shape were subsequently analyzed with Fisher's exact test and one way ANOVA.

Results

Trapezoidal shaped defects were the most common in both radiographic views, and the magnitude of the defect at the top joint line varied significantly amongst shape groups in both AP and lateral views. Trapezoid shaped defects were correlated with smaller defect top lengths in both views. There was no statistical correlation between defect shape BMI, TIV and reason for revision in lateral view. However, T-bilateral defect shapes were correlated with higher BMIs in AP view.

Conclusion

A volumetric classification system of tibial defects is necessary for preoperative planning in revision TKA. Common tibial bone defect shape groups were identified and analyzed in AP and lateral radiographs after revision TKA. Trapezoidal defects were the most common, and all other shapes followed a pattern of proximal enlargement tapering distally. Trapezoidal defects were smaller than other shapes and AP T-bilateral shaped defects were correlated with higher BMIs.

Do Porous Tantalum Metaphyseal Cones Improve Outcomes in Revision Total Knee Arthroplasty?

BACKGROUND

Some authors have advocated for use of porous tantalum metaphyseal cones to manage bone defects during revision total knee arthroplasty (TKA). The purpose of this study is to compare results with porous metaphyseal cones to results with traditional hybrid stem fixation in revision TKA.

METHODS

Forty-nine patients undergoing revision TKA with femoral and/or tibial metaphyseal cones (39 tibial only, 3 femoral only, 7 both) were matched by surgical indication to 49 patients undergoing revision TKA with a traditional hybrid stem (non-cone) technique. Clinical and radiographic outcomes were compared at a minimum of two-year follow-up (mean 3.5 years) with adjustment for baseline characteristics.

RESULTS

Pre-revision bone defects and most baseline demographics were similar between the cone and non-cone cohorts suggesting appropriate matching. Patients in the non-cone cohort had greater pre- to post-operative increases in Knee Society Score (37.2 ± 18.6 vs 28.4 ± 17.8, P = .010) and Knee Society Functional Score (30.4 ± 24.3 vs 13.1 ± 27.6, P = .003). The cohorts did not differ with respect to complications, subsequent reoperation, subsequent revision, patient satisfaction, tibial overhang, the presence of radio-sclerotic lines, cortical hypertrophy around the stems, or tibial subsidence.

CONCLUSION

In this series, metaphyseal cones were not associated with superior outcomes at short-term follow-up. Given the increased cost associated with use of cones compared to traditional techniques, this study cannot support the routine use of metaphyseal cones in revision TKA. Longer-term follow-up will be necessary to determine if construct durability differs over the long term.

Porous-Coated Metaphyseal Sleeves for Severe Femoral and Tibial Bone Loss in Revision TKA

BACKGROUND

Metaphyseal bone loss is commonly encountered in revision total knee arthroplasty (TKA). Anderson Orthopaedic Research Institute types 2 and 3 defects generally require some form of metaphyseal fixation or augmentation. This study evaluates the midterm results of stepped, porous-coated metaphyseal sleeves in revision TKA in the setting of severe bone loss.

METHODS

Patients who underwent revision TKA using metaphyseal sleeves from March 2006 to May 2014 at our institution were identified from a prospective research database. Preoperative patient characteristics and operative data were reviewed. Postoperative outcomes were compared with preoperative values. Primary study outcomes included complications, reoperations, radiographic assessment of sleeve osteointegration, and survivorship.

RESULTS

One hundred sixteen knees (108 patients) underwent revision TKA with 152 metaphyseal sleeves (111 tibial and 41 femoral). Anderson Orthopaedic Research Institute defect classification included 5 type 2A, 89 type 2B, and 17 type 3 tibial defects; and 3 type 2A, 34 type 2B, and 4 type 3 femoral defects. There were 3 intraoperative fractures (1.9%) associated with sleeve preparation and/or insertion. Six knees (5 patients) were lost to follow-up and 5 patients (6 knees) died before 2 years. Of the remaining 104 knees (98 patients, 134 sleeves), mean follow-up was 5.3 years (range 2-9.6 years). Nineteen knees (16.4%) required reoperation, most commonly for recurrent infection. Only one sleeve demonstrated radiographic evidence of failed osteointegration, but did not require revision. Two sleeves (1.5%) required removal and/or resection for recurrent infection.

CONCLUSION

This large retrospective series illustrates the utility of porous metaphyseal sleeves in revision TKA with a low rate of intraoperative complications, excellent osteointegration, and long-term fixation.

Development and Verification of Novel Porous Titanium Metaphyseal Cones for Revision Total Knee Arthroplasty

BACKGROUND

Porous metaphyseal cones are widely used in revision knee arthroplasty. A new system of porous titanium metaphyseal cones has been designed based on the femoral and tibial morphology derived from a computed tomography-based anatomical database. The purpose of this study is to evaluate the initial mechanical stability of the new porous titanium revision cone system by measuring the micromotion under physiologic loading compared with a widely-used existing porous tantalum metaphyseal cone system.

METHODS

The new cones were designed to precisely fit the femoral and tibial anatomy, and 3D printing technology was used to manufacture these porous titanium cones. The stability of the new titanium cones and the widely-used tantalum cones were compared under physiologic loading conditions in bench top test model.

RESULTS

The stability of the new titanium cones was either equivalent or better than the tantalum cones. The new titanium femoral cone construct had significantly less micromotion compared with the traditional femoral cone construct in 5 of the 12 directions measured (P < .05), whereas no statistical difference was found in 7 directions. The new porous titanium metaphyseal tibial cones demonstrated less micromotion in medial varus/valgus (P = .004) and posterior compressive micromotion (P = .002) compared with the traditional porous tantalum system.

CONCLUSION

The findings of this biomechanical study demonstrate satisfactory mechanical stability of an anatomical-based porous titanium metaphyseal cone system for femoral and tibial bone loss as measured by micromotion under physiologic loading. The new cone design, in combination with instrumentation that facilitates surgical efficiency, is encouraging. Long-term clinical follow-up is warranted.

Bone defect animal models for testing efficacy of bone substitute biomaterials

Large bone defects are serious complications that are most commonly caused by extensive trauma, tumour, infection, or congenital musculoskeletal disorders. If nonunion occurs, implantation for repairing bone defects with biomaterials developed as a defect filler, which can promote bone regeneration, is essential. In order to evaluate biomaterials to be developed as bone substitutes for bone defect repair, it is essential to establish clinically relevant in vitro and in vivo testing models for investigating their biocompatibility, mechanical properties, degradation, and interactional with culture medium or host tissues. The results of the in vitro experiment contribute significantly to the evaluation of direct cell response to the substitute biomaterial, and the in vivo tests constitute a step midway between in vitro tests and human clinical trials. Therefore, it is essential to develop or adopt a suitable in vivo bone defect animal model for testing bone substitutes for defect repair. This review aimed at introducing and discussing the most available and commonly used bone defect animal models for testing specific substitute biomaterials. Additionally, we reviewed surgical protocols for establishing relevant preclinical bone defect models with various animal species and the evaluation methodologies of the bone regeneration process after the implantation of bone substitute biomaterials. This review provides an important reference for preclinical studies in translational orthopaedics.

Treatment of severe bone defects during revision total knee arthroplasty with structural allografts and porous metal cones-a systematic review

Aseptic loosening and focal osteolysis are the most common reasons for knee arthroplasty failure. The best treatment remains unclear. We reviewed the literature on the treatment of revision knee arthroplasty using bony structural allografts (476 cases) and porous metal cones (223 cases) to determine if a difference in the revision failure rates was discernable. The failure rates were compared using a logistic regression model with adjustment for discrepancies in FU time and number of grafts used (femoral, tibial, or both). In this analysis, the porous implant shows a significantly decreased loosening rate in AORI 2 and 3 defects. The overall failure rate was also substantially lower in the porous metal group than the structural allograft group; little difference in the infection rates was noted.

Outcome of revision total knee arthroplasty with the use of trabecular metal cone for reconstruction of severe bone loss at the proximal tibia

BACKGROUND

The relative effectiveness of different methods for reconstructing large bone loss at the proximal tibia in revision total knee arthroplasty (rTKA) has not been established. The aim of this study was to evaluate the clinical and radiological outcome after the use of trabecular metal technology (TMT) cones for the reconstruction of tibial bone loss at the time of rTKA.

METHODS

Thirty-six patients had rTKA with the use of a TMT Cone. Bone loss was classified according to the AORI classification and 25% of the patients suffered from T3 AORI defects and 75% of the patients from T2 AORI defects. Implants used were from the NexGen series. At follow-up, radiographs were evaluated according to the Knee Society Roentgenographic Scoring System. Knee and function score was calculated using the Knee Society Clinical Rating System. Average follow-up time was 47 months (range 3-84 months).

RESULTS

Clinical and radiological follow-up data were available in 30 patients and missing in six patients: two died and four patients had re-revision (reinfection (n=2), aseptic loosening (n=1), and knee hyperextension (n=1)). Knee- and function scores (follow-up 43 months (range 12-84 months)) improved from 42 to 77 points (p<0.0005) and 19 to 63 points (p<0.0005) respectively. Twenty-seven patients (follow-up 44 months (range 12-72 months)) showed no signs of radiological loosening of rTKA components.

CONCLUSION

Based on our study, it was concluded that the use of TMT Cones provided an effective treatment in terms of surgical efficacy, clinical results and radiological results and was evidently at least as effective as the other options reviewed in the literature.

LEVEL OF EVIDENCE

IV.

Revision total knee arthroplasty using metaphyseal sleeves at short-term follow-up

The treatment of bone loss in revision total knee arthroplasty (TKA) has involved using revision implants in association with cement, augments, particulate, and structural allograft. Newer metaphyseal augments were introduced to allow for metaphyseal fixation of the prosthesis while managing significant bone loss. The purpose of the current study was to evaluate the outcome of revision TKA using metaphyseal sleeves. The authors prospectively followed 96 knees that underwent revision TKA with metaphyseal sleeves. Eighty-three knees met the minimum 2-year criteria for follow-up. Thirty-six sleeves were used in femoral revisions and 83 sleeves were used in tibial revisions. The defects were classified according to the Anderson Orthopaedic Research Institute classification. Femoral defects were classified as type I in 4 knees, type IIb in 25 knees, and type III in 7 knees. Tibial defects were classified as type I in 9 knees, type IIa in 1 knee, type IIb in 68 knees, and type III in 5 knees. The patients were followed for an average of 2.4 years (range, 2.0-3.7 years). Mean Knee Society function score improved from 47.9 to 61.1 points. Mean Short Form 36 physical score improved from 43.3 to 56.3 points. Mean Western Ontario and McMaster Universities Arthritis Index improved from 55.3 to 25.9 points. None of the implants demonstrated progressive radiolucent lines around the metaphyseal sleeves. At final follow-up, only 2 (2.7%) tibial components required revision for aseptic loosening. At short-term follow-up, revision TKA with metaphyseal sleeves provided reliable fixation. This is especially encouraging given the severe nature of bone loss in the majority of patients in whom a metaphyseal sleeve was used. Long-term follow-up is needed to demonstrate the true effectiveness of these devices.

Use of stepped porous titanium metaphyseal sleeves for tibial defects in revision total knee arthroplasty: short term results

Stepped porous titanium metaphyseal sleeves may provide an option for enhanced fixation in managing challenging tibial defects in revision total knee arthroplasty (TKA). We retrospectively reviewed data on 51 patients who underwent revision TKA utilizing a metaphyseal sleeve for Anderson Orthopaedic Research Institute (AORI) Type II and III tibial defects between June 2007 and July 2011. Of these 51 patients, 36 patients had complete clinical and radiographic data. At final follow-up (mean: 38 months) significant improvements in knee range of motion and Knee Society scores were observed postoperatively (P < 0.001). Four revision procedures were necessary, but none for aseptic implant fixation failure. Radiographic review at final follow-up revealed stable, osteointegrated components without component migration or clinically significant osteolysis. Metaphyseal sleeve use in the management of moderate to severe tibial defects in revision TKA resulted in satisfactory clinical outcomes and is a versatile option for achieving stable fixation.

Use of a trabecular metal cone made of tantalum, to treat bone defects during revision knee arthroplasty

Objectives

the aim of this study was to evaluate the surgical technique and determine the initial results, with a minimum follow-up of two years, from total knee arthroplasty revisions in which trabecular metal cones made of tantalum were used at the Knee Surgery Center of the National Institute of Traumatology and Orthopedics (INTO) or at the authors’ private clinic between July 2008 and December 2010.

Methods

ten patients were included in the study prospectively, through clinical and radiographic evaluations.

Results

seven patients presented evolution without complications relating to the tantalum cones used. Five of these patients said that they did not have any pain and all of them were able to walk without needing crutches. In all the cases, we observed that osseointegration of the tantalum cones had occurred. No migration or loosening of the implants was observed, nor was osteolysis.

Conclusion

use of trabecular metal cones made of tantalum for treating AORI type II or II bone defects was capable of providing efficient structural support to the prosthetic revision implants, in evaluations with a short follow-up.

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.

Supracondylar periprosthetic fractures of the knee in the elderly patients: a comparison of treatment using allograft-implant composites, standard revision components, distal femoral replacement prosthesis

The following study is a review of 3 different treatment methods for treating comminuted distal periprosthetic femur fractures in 23 patients over the age of 70 (average age 80, range 70-90). Reconstruction techniques included 7 allograft prosthesis composite (APC), 9 revision systems (RSA), and 7 distal femur endoprosthesis (DFR). Operative time and blood loss were found to be significantly less in RSA and DFR patients compared to the APC patients. Hospital stay was shortest for the DFR patients. No significant difference was found in the 6-week or 6-month Knee Society Scores. Our preliminary results demonstrate that in experienced hands, distal femur endoprosthesis should be considered in patients with advanced age and poor bone quality who require early mobilization.

Treatment of large bone defects with trabecular metal cones in revision total knee arthroplasty: short term clinical and radiographic outcomes

The early term results of 29 cases of revision total knee arthroplasty using highly porous trabecular metal cone implants for femoral and tibial major bone deficit reconstruction (Anderson Orthopedic Research Institute classification type 2B and 3) have been prospectively analyzed. Indications for revision surgery included: aseptic loosening/wear, staged reimplantation after infection, as well as periprosthetic fracture. At an average follow-up of 33 months (range, 13-73 months) the mean Knee Society Score and functional score statistically improved. Radiological follow-up revealed no evidence of loosening or migration of the constructs. No evidence of complications was noted in correlation with the use of trabecular metal cones. This study supports evidence that trabecular metal cones are an efficient and effective option for dealing with significant bone deficits and obtaining stable biological fixation in revision total knee arthroplasty.

Homologous structural graft for treatment of bone defect during knee revision arthroplasty

Obtaining stable bone-implant interface, correct alignment of the components, proper balance of soft tissues’ tension, maintenance of proper joint interline are fundamental principles for success in surgical revision total knee arthroplasty, which are only obtained with management bone deficiency. However, proper treatment of large defects remains unclear. The aim of this study was to evaluate the clinical and radiographic results of patients that had underwent revision surgery for total knee arthroplasty with use of structural grafts of musculoskeletal tissue bank in the period between January 2002 to December 2010 by the Knee Surgery Center of National Institute of Traumatology and Orthopaedics (INTO). The study included 26 revision arthroplasties with homologous structural bone grafting in 25 patients. Thirty-four structural bone grafts were used during the 26 revision total knee arthroplasty surgeries studied. The proximal tibia and distal femur were the grafts most frequently used. Six patients developed deep infection and in one of them with damage to the extensor mechanism associated. The average score on the WOMAC was 24,9. In the assessment of functional capacity in the SF-36, the average was 52.5. In radiographic evaluation, resorption of the graft occurred in three patients and no cases were observed of osteolysis, fracture of the graft, migration or subsidence of the components. Bone grafting of a musculoskeletal tissue bank is a satisfactory option to the handling of the bone defect in the setting of revision surgery for total knee arthroplasty.

Tantalum cones for major osteolysis in revision knee replacement

We report the results of revision total knee replacement (TKR) in 26 patients with major metaphyseal osteolytic defects using 29 trabecular metal cones in conjunction with a rotating hinged total knee prosthesis. The osteolytic defects were types II and III (A or B) according to the Anderson Orthopaedic Research Institute (AORI) classification. The mean age of the patients was 72 years (62 to 84) and there were 15 men and 11 women. In this series patients had undergone a mean of 2.34 previous total knee arthroplasties. The main objective was to restore anatomy along with stability and function of the knee joint to allow immediate full weight-bearing and active knee movement. Outcomes were measured using Knee Society scores, Oxford knee scores, range of movement of the knee and serial radiographs. Patients were followed for a mean of 36 months (24 to 49). The mean Oxford knee clinical scores improved from 12.83 (10 to 15) to 35.20 (32 to 38) (p < 0.001) and mean American Knee Society scores improved from 33.24 (13 to 36) to 81.12 (78 to 86) (p < 0.001). No radiolucent lines suggestive of loosening were seen around the trabecular metal cones, and by one year all the radiographs showed good osteo-integration. There was no evidence of any collapse or implant migration. Our early results confirm the findings of others that trabecular metal cones offer a useful way of managing severe bone loss in revision TKR.

Cite this article: Bone Joint J 2013;95-B:1069–74.

Tantalum cones in revision total knee arthroplasty. A promising short-term result with 29 cones in 21 patients

Twenty-nine porous tantalum metaphyseal cones were implanted in 21 patients (14 women and 7 men) during revision TKA. The average age at the time of the procedure was 73.3 years. Sixteen revisions were considered aseptic and 5 were reimplantations after sepsis. Eight patients had stemmed revision implants and thirteen primary designs. According to the Anderson Orthopaedic Research Institute bone defect classification, femoral defects were rated as F3 in 14 knees and F2B in 3 knees. Tibial defects were rated as T2A in 3 cases, T2B in 3 cases and T3 in 5 cases. A femoral cone was inserted in 10 patients, a double cone (femur and tibia) in 8, and a single tibial cone in 3. A rotating hinge knee prosthesis (RHK, Zimmer) was inserted in 10 patients and a constrained condylar prosthesis (LCCK, Zimmer) in 11 patients. The diaphysis was cemented in 9 cases and, in 11 cases, just the metaphysis. At an average follow up of 36 months only one reconstruction was removed due to persistent infection. All metaphyseal cones showed evidence of stable osseointegration. According to the Knee Society Score the results were rated as excellent in 12 cases, good in 5 cases, fair in 3 and poor in 1 case. In the short term, porous tantalum metaphyseal cones provided structural support for large femoral and tibial defects. They also provided the environment for bone graft osseointegration, repair of femoral fractures and effective interdigitation of cement mantle into the trabecular metal cone.

Cementless metaphyseal sleeves used for large tibial defects in revision total knee arthroplasty

Revision arthroplasty of large tibial defects remains a challenge. Thirty revision knee arthroplasties using a porous titanium tibial sleeve for Anderson Orthopaedic Research Institute (AORI) Type 2B and Type 3 defects with minimum 2year follow up were retrospectively reviewed. The average Knee Society Score increased from 55 pre-operatively to 92 post-operatively. Six patients had a repeat operation though none were sleeve related. All radiographs at final follow-up showed well fixed components with osseous in-growth. Seven patients had end-of-stem pain, four of which resolved. Our short-term results show that porous titanium sleeves are a promising option when managing large areas of metaphyseal bone loss by filling defects and providing stable construct with biologic fixation.

Biomechanical evaluation of different reconstructive techniques of proximal tibia in revision total knee arthroplasty: An in-vitro and finite element analysis

BACKGROUND

Bone loss and subsequent defects are often encountered in revision total knee arthroplasty. In particular, when the cortical rim of proximal tibia is breached, the surgical decision on the reconstructive options to be taken is challenging due to the variety of defects and the lack of data from clinical or experimental studies that can support it. The purpose of this study is to assess how different reconstructive techniques, when applied to an identical defect and bone condition, can be associated to dissimilar longevity of the revision procedure, and the role of a stem in this longevity.

METHODS

Proximal cortex strains and implant stability were measured in ten reconstructive techniques replicated with synthetic tibiae. The cancellous bone strains under each construct were assessed with finite element models which were validated against experimental strains.

FINDINGS

The measured strains and stability showed that the proximal cortex is not immune to the different reconstructive techniques when applied to an identical defect. The largest cancellous strain differences between modular and non-modular techniques indicate a distinct risk between reconstructive techniques, associated to the supporting capacity of cancellous bone at long term.

INTERPRETATION

The main finding of the present study is the observation that modular augments increases, on a long term basis, the potential risk of bone resorption relative to the non-modular techniques. In addition, the use of a press-fit stem in the scope of non-modular techniques can lead to improved stability and load transfer, which can contribute positively to the life expectancy of these techniques.

Femorotibial bone loss during revision total knee arthroplasty

Bone loss (BL) is frequent during revision total knee arthroplasty (TKA). It is underestimated in X-rays. Most classifications distinguish contained from uncontained BL but the most frequently used classification is that of Engh, which does not take into account this element. Reconstruction should result in resistant support for the revision TKA. It helps correct malalignment, restore satisfactory ligament tension and height of the joint line. Several techniques have been suggested: cement, augments, bone grafts, modular metaphyseal sleeves and cones and megaprostheses. Cement is only used with small BL, especially in elderly patients. Augments allow rapid filling of small peripheral BL with good mid-term results but frequent radiolucent lines. Morselized allografts can be incorporated and remodeled. They are a good alternative in young patients. Structural allografts are resistant but there is a risk of fracture and resorption. Modular metaphyseal sleeves and cones incorporate with host bone and are attached to the prosthesis by a mechanical interface or cement. They may also be more durable. Megaprostheses are only indicated in severe BL in elderly subjects. Reconstruction is just one aspect of revision TKA and it should respect the technical requirements of the procedure in particular fixation with a stem, which is important in determining the outcome of reconstruction.

Factors affecting outcome of massive intercalary bone allografts in the treatment of tumours of the femur

We retrospectively reviewed 101 consecutive patients with 114 femoral tumours treated by massive bone allograft at our institution between 1986 and 2005. There were 49 females and 52 males with a mean age of 20 years (4 to 74). At a median follow-up of 9.3 years (2 to 19.8), 36 reconstructions (31.5%) had failed. The allograft itself failed in 27 reconstructions (24%).

Mechanical complications such as delayed union, fracture and failure of fixation were studied. The most adverse factor on the outcome was the use of intramedullary nails, followed by post-operative chemotherapy, resection length > 17 cm and age > 18 years at the time of intervention. The simultaneous use of a vascularised fibular graft to protect the allograft from mechanical complications improved the outcome, but the use of intramedullary cementing was not as successful.

In order to improve the strength of the reconstruction and to advance the biology of host–graft integration, we suggest avoiding the use of intramedullary nails and titanium plates, but instead using stainless steel plates, as these gave better results. The use of a supplementary vascularised fibular graft should be strongly considered in adult patients with resection > 17 cm and in those who require post-operative chemotherapy.

Revision total knee arthroplasty: clinical outcome comparison with and without the use of femoral head structural allograft

The use of femoral head structural allograft (FHSA) for the management of massive bony defects during revision total knee arthroplasty (TKA) is well documented in the literature. The purpose of this study was to compare the clinical outcomes of patients undergoing revision (TKA) with FHSA to those without. All patients undergoing revision TKA between January 2000 and August 2005 were reviewed. Two cohorts were generated: a study cohort--revision TKA using FHSA (n = 24)--and control cohort--revision TKA without FHSA (n = 48). The 2 study cohorts groups were comparable. All patients completed validated outcome questionnaires. The FHSA cohort was found to have significantly better outcome scores. This study demonstrates improved clinical outcomes for patients undergoing revision TKA using a structural allograft compared with those without.

Early results of the use of tantalum femoral cones for revision total knee arthroplasty

BACKGROUND

The optimum treatment method for large femoral bone defects during revision knee replacement has not been established. The purpose of the present study was to determine the initial results associated with the use of porous tantalum metaphyseal cones for the treatment of severe femoral bone loss at the time of revision total knee arthroplasty.

METHODS

Porous tantalum metaphyseal cones were implanted during twenty-four revision total knee replacements. The study group included thirteen women and eleven men with a mean age of sixty-four years at the time of the procedure. The indications for the revision procedure included aseptic loosening of the femoral component (eleven patients), second-stage reimplantation for the treatment of deep infection (seven patients), severe osteolysis around a well-fixed femoral component (three patients), periprosthetic femoral fracture (two patients), and severe knee instability (one patient).

RESULTS

The patients were followed for an average of thirty-three months (range, twenty-four to fifty months). Overall, the average Knee Society clinical score improved from 55 points preoperatively to 81 points at the time of the latest follow-up. Radiographic evaluation was completed for twenty patients after a mean duration of follow-up of thirty-five months. All femoral cones appeared well fixed radiographically, with no evidence of complications related to the cone.

CONCLUSIONS

At the time of short-term follow-up, the porous tantalum metaphyseal femoral cones effectively provided structural support for the femoral implants of a revision total knee arthroplasty in this series. The potential for long-term biologic fixation may provide durability for reconstructions. Long-term follow-up and comparison with alternative reconstructive techniques will be required to evaluate the true effectiveness of this implant.

USE OF AUTOLOGOUS BONE GRAFT ASSOCIATED WITH SUPPORT OSTEOSYNTHESIS FOR TIBIAL EDGE BONE LOSSES IN TOTAL KNEE PROSTHESES

Objective: To report the initial results from the use of a new technique for fixation of bone grafts in uncontained tibial bone defects in patients undergoing total knee prosthesis implantation. Methods: Six patients with severe varus deformity of the knee who, after cuts and ligament balancing had been performed, still presented bone deficiencies that reached the edge of the tibial cut and compromised the implant stability, underwent a new fixation technique. Results: Five of the patients had good-clinical results, with integration of the graft within 12 weeks. One patient presented clinical complications with wound dehiscence and implant exposure, which evolved to the need for implant removal and knee arthrodesis. Conclusion: Support osteosynthesis as a graft fixation method is a viable option for treating tibial bone deficiencies. The proposed technique certainly needs further studies for its validation.

Management and outcome of periprosthetic fractures after total knee arthroplasty

BACKGROUND

The incidence of periprosthetic fractures after total knee arthroplasty is continuously rising because of an increasing number of knee joint replacements and an enhanced survivorship of the elderly population after knee arthroplasty. The purpose of this study was to analyze the practicability and effectiveness of the various treatment methods for management of periprosthetic fractures after total knee arthroplasty, and to determine the clinical and radiographic long-term results of patients following surgical and nonoperative treatment of these injuries.

METHODS

We reviewed the clinical and radiographic records of 41 patients (31 women and 10 men; average age, 78.6 years) with periprosthetic fractures after total knee arthroplasty between 1992 and 2008. Thirty-seven patients showed a periprosthetic fracture of the distal femur, and four patients had a periprosthetic proximal tibial fracture. Thirty-six patients underwent operative stabilization by plate fixation (n = 18), intramedullary nailing (n = 15) or revision arthroplasty (n = 3), and five patients were treated nonoperatively by long-term cast immobilization.

RESULTS

Twenty-eight patients returned to their preinjury activity level and were satisfied with their clinical outcome. In 10 patients, we saw a relevant decrease of knee function and severe limitations in gait and activities of daily living. Three patients died related to surgery. Successful fracture healing within 6 months was achieved in 33 (87%) of 38 patients. Failures of reduction or fixation occurred in 8 (21%) of 38 patients. Reoperation due to technical failures was necessary in three patients.

CONCLUSIONS

Compared with current data in literature, we had a satisfactory outcome in following individualized treatment of periprosthetic fractures after knee joint replacement. Referring to the wide field of treatment options and high rates of complications, periprosthetic femoral fractures around the knee commonly constitute a challenging problem for the treating surgeons and require an adequate analysis of fracture etiology and a corresponding transfer into an individual treatment concept.