Large tumor endoprostheses and extracortical bone-bridging: 28 patients followed 10-20 years

Short-term clinical outcomes of Kyocera Modular Limb Salvage System designed cementless stems for the endoprosthetic reconstruction of lower extremities: a Japanese Musculoskeletal Oncology Group multi-institutional study

BACKGROUND

The high rate of aseptic loosening of cemented stems has led to their frequent use in endoprosthetic reconstruction. However, problems, such as stem breakage and stress shielding at the insertion site, remain. The Japanese Musculoskeletal Oncology Group (JMOG) has developed Kyocera Modular Limb Salvage System (KMLS) cementless stems with a unique tapered press-fit and short fixation design. This study aimed to clarify the short-term postoperative outcomes of this prosthesis and validate the stem design.

METHODS

One hundred cases of KMLS cementless stems (51 male patients; median age, 49 years; mean follow-up period, 35 months), with a minimum follow-up of 2 years, for the proximal femur (PF), distal femur (DF), and proximal tibia were prospectively registered for use. Prosthesis survival, complication rates, postoperative functional, and radiographical evaluation were analyzed. Complications or failures after insertion of the KMLS endoprostheses were classified into five types and functional results were analyzed according to the MSTS scoring system at postoperative 1 year. The diaphyseal interface and anchorage were graded by the ISOLS system at postoperative 2 years.

RESULTS

The overall prosthesis survival rates at 2 and 4 years were 88.2 and 79.6%, respectively. The prosthesis-specific survival rate excluding infection and tumor recurrence was 90.2 and 87.9%, respectively. Younger age (p = 0.045) and primary tumor (p = 0.057) were associated with poor prognosis of prosthesis-specific survival excluding infection and tumor recurrence. Complications were observed in 31 patients, 13 patients underwent revision surgery. The mean MSTS functional score at 1 year postoperatively was 68%. Early implant loosening was significantly more common in the DF (p = 0.006) and PF/DF straight stem (p = 0.038). The ISOLS radiographic evaluation at 2 years after surgery revealed good bone remodeling and anchorage in most cases (bone remodeling: 90% / excellent and good, anchorage: 97% / excellent and good).

CONCLUSIONS

Tumor endoprosthesis long-term fixation to the diaphysis of the lower extremity remains challenging. The KMLS cementless stem with a unique tapered press fit design showed good short-term results in maintaining bone stock. To prevent early loosening, a curved stem should be used in PF and DF, but long-term follow-up is necessary.

Functional outcome of infected endoprosthesis: A 20-year retrospective analysis

PURPOSE

Bone tumours are increasingly treated with limb-salvage surgeries. However, implant infection is a devastating complication, greatly affecting the functional outcome. Yet, data on functional outcome post-implant infection are scarce. This study aims to determine the functional outcome and implant survival of these patients.

METHODS

Patients' data on endoprosthetic replacement surgeries at our institution (January 1996-December 2016) was retrospectively reviewed. Information was available for 161 patients and was analysed using SPSS and SMART Partial Least Squares. Functional outcome was determined using the Musculoskeletal Tumor Society (MSTS) and Toronto Extremity Salvage Score (TESS) scoring system.

RESULTS

Both mean rank MSTS (33.14 vs 87.02) and TESS (48.17 vs 85.13) scores were significantly lower in the infected group. These differences remained statistically significant after excluding amputation and rotationplasty cases within the infected group. Even after the resolution of infection, both MSTS and TESS remained significantly higher in the non-infected group. However, analysis of the infected group showed no significant differences in functional outcome between persistent and resolved infections (implant in-situ). Age significantly impacted the functional outcome for both the non-infected and infected groups, while local recurrence and metastasis significantly impacted the non-infected cases. Local tumour recurrence was lower in infected endoprosthetic patients (8.3% vs 10.5%). 56% of infected implants were removed; the majority were treated with two-stage revision surgery.

CONCLUSION

Endoprosthesis infection worsens the overall functional outcome. Additional factors affecting functional outcome were age, presence of local recurrence and metastatic disease. Local tumour recurrence was lower amongst infected endoprosthesis cases, and >50% of infected implants were removed.

Biocompatible Customized 3D Bone Scaffolds Treated with CRFP, an Osteogenic Peptide

BACKGROUND

Currently used synthetic bone graft substitutes (BGS) are either too weak to bear the principal load or if metallic, they can support loading, but can lead to stress shielding and are unable to integrate fully. In this study, we developed biocompatible, 3D printed scaffolds derived from µCT images of the bone that can overcome these issues and support the growth of osteoblasts.

METHODS

Cylindrical scaffolds were fabricated with acrylonitrile butadiene styrene (ABS) and Stratasys^® MED 610 (MED610) materials. The 3D-printed scaffolds were seeded with Mus musculus calvaria cells (MC3T3). After the cells attained confluence, osteogenesis was induced with and without the addition of calcitonin receptor fragment peptide (CRFP) and the bone matrix production was analyzed. Mechanical compression testing was carried out to measure compressive strength, stiffness, and elastic modulus.

RESULTS

For the ABS scaffolds, there was a 9.8% increase in compressive strength (p < 0.05) in the scaffolds with no pre-coating and the treatment with CRFP, compared to non-treated scaffolds. Similarly, MED610 scaffolds treated with CRFP showed an 11.9% (polylysine pre-coating) and a 20% (no pre-coating) increase (p < 0.01) in compressive strength compared to non-treated scaffolds.

CONCLUSIONS

MED610 scaffolds are excellent BGS as they support osteoblast growth and show enhanced bone growth with enhanced compressive strength when augmented with CRFP.

Vascularised bone graft is an effective technique for extracortical bone bridging to combat cemented megaprosthesis loosening at the bone-implant junction

INTRODUCTION

The bone-implant junction is a potential site for aseptic loosening. Extracortical bone bridging at the bone-implant junction is advocated to improve implant fixation by forming a biological seal. We propose a novel technique with vascularised bone graft (VBG) to form an extracortical bone bridge at the bone-implant junction to enhance implant stability. We compared the clinical and radiological outcomes for tumour megaprostheses performed (1) with and without bone graft and (2) with non-vascularised versus VBG technique.

METHODS

Forty-six tumour megaprosthesis procedures from 1 June 2007 to 31 October 2017 were identified from hospital records. Twenty-eight operations incorporated bone graft at the bone-implant junction, and 18 did not. Of these 28 bone graft procedures, 13 involved VBG, and 15 did not (non-VBG). The VBG technique involves resecting a short segment of healthy bone beyond the oncological margin with its preserved blood supply, splitting it, then securing it over the junction. Clinical outcomes assessed included loosening, fracture and recurrence. Extracortical bone growth at the bone-implant junction was quantified radiologically at intervals 0-24 months post-operatively. The mean follow-up was 4.27 years.

RESULTS

There were five incidences (27.8%) of loosening in the non-bone graft group compared to zero in the bone graft group (p = 0.03). There was a higher radiological score of extracortical bone growth in the bone graft group compared to no bone graft at 3-24 months post-operatively (p < 0.05). Within the bone graft group, the VBG group fared superior at 6 and 12 months post-operatively compared to non-VBG (p < 0.05), as well as a lower rate of radiological junctional resorption (p = 0.04).

CONCLUSIONS

We recommend bone grafting for its merits of less implant loosening. We propose the VBG technique to combat early aseptic loosening in megaprosthesis replacement as there was a higher radiological score compared to non-VBG.

Assessment of Extra-Cortical Bone Bridge Interface in Cemented Mega Endoprosthesis for Limb Salvage Surgery

Introduction:

Mega endoprosthesis replacement for resection of primary malignant bone tumour requires immediate and long-term stability, particularly in the young and active patient. Extracortical bone bridge interface (EBBI) is a technique whereby autograft is wrapped around the interface junction of bone and porous-coated implant to induce and enhance bone formation for biological incorporation. This procedure increases the mean torsional stiffness and the mean maximum torque, which eventually improves the implant's long-term survival.

Material and methods:

The extracortical bone bridge interface's radiological parameter was evaluated at the prosthesis bone junction two years after surgery utilising a picture archiving and communication system (PACS). The radiograph's anteroposterior and lateral view was analysed for both thickness and length in all four cortices. The analysis was done in SPSS Version 24 using One-Way ANOVA and independent T-Test. Results were presented as mean and standard deviation and considered significant when the p-value was < 0.05.

Results:

The mean average thickness was 2.2293mm (SD 1.829), and the mean average length was 31.95% (SD 24.55). We observed that the thickness and length of EBBI were superior in the young patient or patients with giant cell tumour that did not receive chemotherapy, compared to patients treated for osteosarcoma. The distal femur also had better EBBI compared to the proximal tibia. However, the final multivariable statistical analysis showed no significant difference in all variables. EBBI thickness was significantly and positively correlated with EBBI Length (p<0.001). We conclude that, for each 1mm increase in EBBI thickness, the length will increase by 0.06% on average. About 17.2% of patients out of the 29 showed no radiological evidence of EBBI.

Conclusion:

From our study, there were no factors that significantly contributed to the formation and incorporation of EBBI

Comparative Analysis of Early Follow-up of Biologic Fixation and Cemented Stem Fixation for Femoral Tumor Prosthesis

OBJECTIVE

To compare the safety and efficacy between biologic fixation and traditional cement stems for the fixation of distal femoral prostheses for reconstruction following tumor resection.

METHODS

Retrospective analysis was performed of patients who received a first distal femoral tumor prosthesis, with a rotating hinge, in the Department of Orthopaedic Oncology of Beijing Jishuitan Hospital between October 2011 and January 2016. Two hundred and sixty eligible cases were enrolled, with a cemented fixation used in 199 of these cases and a biologic fixation in 61 cases. Survival rates and survival time of prostheses were analyzed, with prosthetic failure considered as the endpoint event for survival time of the prosthesis. Kaplan-Meier survival curve and the log-rank test were used to compare survival rates between the two types of fixation methods, and factors that may affect the survival rate of prosthesis were evaluated.

RESULTS

Of the 260 cases forming our study group, 138 were males and 122 females, with 102 males and 97 females in the cemented fixation group (mean age, 25.8 years; range, 8-72 years) and 36 males and 25 females in the biologic fixation group (mean age, 25.5 years; range, 12-59 years). Osteosarcoma was the most common type of tumor (188 cases, 72.3%), of which 145 cases (72.9%) were in the cemented and 45 cases (72.1%) in the biologic fixation group. Among the 260 cases enrolled into the study group, 13 patients were lost to follow-up. The average duration of follow-up for the remaining 247 cases was 28.8 months (median, 28.8 months; range, 4-61 months). The 3-year overall survival rate of prostheses was 87.2% for the biologic fixation group and 80.4% in the cemented fixation group (P = 0.389). The 3-year mechanical survival rate (excluding cases of infection and oncologic progression) was 100% for the biologic fixation and 97.6% for the cemented fixation group (P = 0.468). Complications were identified in 21 cases: 3 cases (5%) in the biologic and 18 cases (9.6%) in the cemented fixation group (P = 0.264). Two revisions were required in the cemented fixation group, but no revision was required in the biologic fixation group. A total of 10 patients required amputation after prosthesis implantation. Of these, 7 cases (4 cement and 3 biologic) were due to tumor recurrence; 3 cases were due to infection, with all cases occurring in the cement fixation group.

CONCLUSION

The current study provides a baseline reference for future mid-term to long-term follow-up, laying the foundation for further studies and comparison of the incidence of aseptic loosening of both types of prosthesis.

In vivo evaluation of a novel nanocomposite porous 3D scaffold in a rabbit model: histological analysis

The healing of load-bearing segmental defects in long bones is a challenge due to the complex nature of the weight that affects the bone part and due to bending, shearing, axial, and torsional forces. An innovative porous 3D scaffolds implant of CaCO₃ aragonite nanocomposite derived from cockle shell was advanced for substitute bone solely for load-bearing cases. The biomechanical characteristics of such materials were designed to withstand cortical bone strength. In promoting bone growth to the implant material, an ideal surface permeability was formed by means of freeze drying and by adding copolymers to the materials. The properties of coating and copolymers supplement were also assessed for bone-implant connection resolutions. To examine the properties of the material in advanced biological system, an experimental trial in an animal model was carried out. Critical sized defect of bone was created in rabbit's radial bone to assess the material for a load-bearing application with a short and extended period assessment with histological evaluation of the incorporated implanted material to the bone of the host. Trials in animal models proved that the material has the capability of enduring load-bearing conditions for long-term use devoid of breaking or generating stress that affects the host bone. Histological examination further confirmed the improved integration of the implanted materials to the host bone with profound bone development into and also above the implanted scaffold, which was attained with negligible reaction of the tissues to a foreign implanted material.

A systematic review of endoprosthetic replacement for non-tumour indications around the knee joint

BACKGROUND

Endoprosthetic replacement (EPR) for limb salvage is an established treatment modality for orthopaedic malignancies around the knee. Increasingly, they are being used for non-tumour indications such as fractures, bone loss associated with aseptic loosening, septic loosening and ligament insufficiencies.

METHODS

We reviewed the evolution and biomechanics of knee EPRs. MEDLINE was searched using the PubMed interface to identify relevant studies pertaining to the use of knee EPRs in non-tumour conditions. Failures, mortality and knee scores were the main outcome measures. Subgroup analysis in the non-tumour conditions was also performed.

RESULTS

There were nine studies with an average follow-up of 3.3years (Range 1-5years) describing 241 EPRs used in non-tumour conditions. Re-operation for any reason occurred in 17% (41/241) of cases. The most common complication was infection (15%) followed by aseptic loosening (5%) and periprosthetic fractures (5%). The mortality rate averaged 22%. Infected knee arthroplasties were less likely to have a successful outcome when salvaged with an EPR with failure rates up to 33%.

CONCLUSIONS

Endoprosthetic replacement is a limb salvage option when other surgical options are unfeasible, especially in low demand elderly patients with limited life expectancy. They have low rates of failure in the medium term.

LEVEL OF EVIDENCE

Level 1.

Surgical technique: Computer-generated custom jigs improve accuracy of wide resection of bone tumors

BACKGROUND

Manual techniques of reproducing a preoperative plan for primary bone tumor resection using rudimentary devices and imprecise localization techniques can result in compromised margins or unnecessary removal of unaffected tissue. We examined whether a novel technique using computer-generated custom jigs more accurately reproduces a preoperative resection plan than a standard manual technique.

DESCRIPTION OF TECHNIQUE

Using CT images and advanced imaging, reverse engineering, and computer-assisted design software, custom jigs were designed to precisely conform to a specific location on the surface of partially skeletonized cadaveric femurs. The jigs were used to perform a hemimetaphyseal resection.

METHODS

We performed CT scans on six matched pairs of cadaveric femurs. Based on a primary bone sarcoma model, a joint-sparing, hemimetaphyseal wide resection was precisely outlined on each femur. For each pair, the resection was performed using the standard manual technique on one specimen and the custom jig-assisted technique on the other. Superimposition of preoperative and postresection images enabled quantitative analysis of resection accuracy.

RESULTS

The mean maximum deviation from the preoperative plan was 9.0 mm for the manual group and 2.0 mm for the custom-jig group. The percentages of times the maximum deviation was greater than 3 mm and greater than 4 mm was 100% and 72% for the manual group and 5.6% and 0.0% for the custom-jig group, respectively.

CONCLUSIONS

Our findings suggest that custom-jig technology substantially improves the accuracy of primary bone tumor resection, enabling a surgeon to reproduce a given preoperative plan reliably and consistently.

Haptic robot-assisted surgery improves accuracy of wide resection of bone tumors: a pilot study

BACKGROUND

Accurate reproduction of the preoperative plan at the time of surgery is critical for wide resection of primary bone tumors. Robotic technology can potentially help the surgeon reproduce a given preoperative plan, but yielding control of cutting instruments to a robot introduces potentially serious complications. We developed a novel passive ("haptics") robot-assisted resection technique for primary bone sarcomas that takes advantage of robotic accuracy while still leaving control of the cutting instrument in the hands of the surgeon.

QUESTIONS/PURPOSES

We asked whether this technique would enable a preoperative resection plan to be reproduced more accurately than a standard manual technique.

METHODS

A joint-sparing hemimetaphyseal resection was precisely outlined on the three-dimensionally reconstructed image of a representative Sawbones femur. The indicated resection was performed on 12 Sawbones specimens using the standard manual technique on six specimens and the haptic robotic technique on six specimens. Postresection images were quantitatively analyzed to determine the accuracy of the resections compared to the preoperative plan, which included measuring the maximum linear deviation of the cuts from the preoperative plan and the angular deviation of the resection planes from the target planes.

RESULTS

Compared with the manual technique, the robotic technique resulted in a mean improvement of 7.8 mm of maximum linear deviation from the preoperative plan and 7.9° improvement in pitch and 4.6° improvement in roll for the angular deviation from the target planes.

CONCLUSIONS

The haptic robot-assisted technique improved the accuracy of simulated wide resections of bone tumors compared with manual techniques.

CLINICAL RELEVANCE

Haptic robot-assisted technology has the potential to enhance primary bone tumor resection. Further bench and clinical studies, including comparisons with recently introduced computer navigation technology, are warranted.

Long term results of fixed-hinge megaprostheses in limb salvage for malignancy

We retrospectively studied the files of 669 patients with musculoskeletal tumors treated with limb salvage and reconstruction using fixed-hinge knee megaprostheses. We used the KMFTR® prosthesis from 1983 to 1989 in 126 patients, and the HMRS® prosthesis thereafter in 543 patients because of the anatomical femoral stem with one lateral flange for improved stress-shielding, the new hinge design and new generation polyethylene placed centrally in the metallic hinge, and the improved function compared to the former prosthesis. Distal femoral reconstructions were done in 474, proximal tibia in 163, extrarticular knee joint in nine, and total femoral in 23 patients. At 10 and 20 years follow-up, survival to breakage was 95% and 85%, to aseptic loosening 94% and 82%, to infection 90% and 82%, and to polyethylene wear 95% and 37%. A statistically significant higher survival to breakage of the HMRS® prostheses was observed. No statistical difference of survival to breakage regarding the site of reconstruction, aseptic loosening, infection, polyethylene wear and mean functional score between the two types of prostheses was observed.

In vivo testing of knee stability after rotating-hinge total knee arthroplasty: a comparison of 2 knee systems

Rotating-hinge knee prostheses are used for reconstruction in cases of severe articular compromise and major bone loss. Biomechanical studies revealed that rotating-hinge designs with long and cylindrical pegs are more stable than devices with short and more tapered ones. Twenty-five patients underwent clinical examination using ultrasound, radiographs, and 3 different rating systems to examine the in vivo stability and functional outcome of 2 rotating-hinge knee systems. Overall, the study revealed that a stable reconstruction could be achieved with both tested devices, with good functional outcome. The results for medial and lateral lift-off during flexion and extension in ultrasonography were comparable, whereas the measured distraction of the Limb Preservation System (LPS/M.B.T.; DePuy, Warsaw, Indiana) was lower compared with the S-ROM Noiles prostheses (DePuy). The implant, the new formed capsule, and the remaining soft tissues have to maintain joint stability. Soft tissue reconstruction, especially the medial gastrocnemius flap, and the newly formed periprosthetic scar seems to prevent distraction of several millimeters. In addition, determining the lift-off with ultrasonography showed that the shape of the peg does not influence implant's stability against lateral directed forces.

Trabecular metal endoprosthetic limb salvage reconstruction of the lower limb

Currently, porous tantalum (trabecular metal) implants are widely accepted and frequently used for primary and revision hip and knee replacement surgery. This study examines the results of porous tantalum endoprostheses used to reconstruct large skeletal defects following resection of bone tumors. Seven custom tantalum implants were used to reconstruct 7 patients following resection for skeletal sarcomas in the femur and proximal tibia. Patient ages ranged from 13 to 71, with a mean of 34 years. Minimum patient follow-up was 6 years. The average Musculoskeletal Tumor Society functional evaluation score was 95 % of normal. There were no infections, hardware failures, or adverse events. One implant was revised 98 months post insertion because of fibrosis, loss of motion and loosening. In this small clinical series, the use of porous tantalum for limb salvage reconstruction is shown to be safe, to successfully provide osteointegration and soft tissue ingrowth, and to facilitate return of limb girdle muscle function.

Pasteurized autograft-prosthesis composite for reconstruction of proximal tibia in 13 sarcoma patients

BACKGROUND

The purpose of this study is to ascertain the survival of the pasteurized autograft-prosthesis composite and functional outcome of this procedure, and to evaluate the complications including nonunion, infection, loosening, bony resorption, and fracture.

METHODS

We retrospectively reviewed 13 proximal tibial sarcoma patients who underwent tibia reconstructions with using a pasteurized autograft-prosthesis between 1993 and 2003.

RESULTS

Four patients underwent removal of the composite with a minimum follow-up of 11 months (average: 43 months, range: 11-75 months). The survival rate of the 13 composites, as calculated by the Kaplan-Meier method, was 76.9% at 5 years. The primary cause of removing the composite was infection in three patients and loosening in one patient. The average MSTS functional score of 11 patients was 23.6 +/- 3.3 (79%). Nonunion was identified in four patients, while infection developed in three patients. Loosening of the stem and resorption of the pasteurized bone was detected in one case each. No patient developed fracture of autograft.

CONCLUSIONS

Our data suggest that the pasteurized autograft-prosthesis has comparable functional outcome and complication rates as other methods, such as endoprosthesis and allograft-prosthetic composite and it offers a reconstructive option for surgeons who do not have access to large allograft banks.

Pasteurized autograft-prosthesis composite for distal femoral osteosarcoma

BACKGROUND

We examined the survivorship and functional outcome of the pasteurized autograft-prosthesis composite for distal femoral osteosarcoma. We also evaluated complications including nonunion, loosening, bony resorption, infection, and fracture.

METHODS

We retrospectively reviewed 15 distal femoral osteosarcoma patients who underwent reconstructions using pasteurized autograft-prosthesis composite between 1993 and 2003.

RESULTS

No patient required graft removal during a minimum follow-up of 35 months (average 56 months; range 35-78 months). The average Musculoskeletal Tumor Society System (MTSS) functional score was 86%. Nonunion developed in five patients, and three of them subsequently showed loosening of the stem. No patient experienced infection or fracture.

CONCLUSIONS

Our data suggest that the pasteurized autograft-prosthesis composite could be an easily accessible alternative for the reconstruction of large skeletal defects in the distal femur because of the satisfactory functional outcome with a low rate of ultimate failure and complications in this study.

Megaprostheses for the treatment of malignant bone tumours of the lower limbs

Lower limb salvage surgery remains a challenge in orthopaedic oncology. Both cemented and cementless, modular, endoprosthetic systems are widely used to treat defects of different sizes. The systems have changed over the years, and each major orthopaedic company offers a modular tumour and revision system for the lower extremities. All systems have worse long-term results compared to conventional total hip or total knee systems. This is due to the large defects that need to be bridged with a more difficult fixation in the diapyhsis of the femur and tibia and a more complex restoration of joint biomechanics. This article summarises the results of several clinical studies with different systems. Newer systems without clinical follow-up are described. We previously reported a prospective study of 50 consecutive patients treated with the MUTARS endoprostheses. The follow-up was 2-7 years. Clinical evaluation showed good results compared to other systems. The review of the literature and our own results do not validate the support or favouring of one specific system. The surgeon should choose a system with which he/she is familiar and that provides the modularity needed intraoperatively to bridge any defect in the lower limbs.

Uncemented short-length diaphyseal segmental replacement prosthesis fixation--finite element analysis and long-term results

INTRODUCTION

Extensively porous coated segmental replacement prostheses with intramedullary cementless fixation to bone over the whole length of stem often exhibit resorption of the surrounding bone due to stress-shielding. This makes them particularly susceptible to aseptic loosening.

STUDY

A finite element analysis of the state of loading of a short-length fixation in a new prosthetic stem design has shown a definite advantage over long-length fixation. The stress pattern within the bone surrounding the prosthesis confirmed that shortening of the ongrowth area in length increases the stress values at the resection level significantly. This stem (Endlock) has been used for diaphyseal anchorage in the treatment of tumors in combination with an artificial joint of proven design in order to reduce stress shielding.

RESULTS

No Endlock stem fractures or aseptic loosenings were observed at recent follow-up. The early clinical results comply with the theoretical assumptions.

CONCLUSIONS

A short-length fixation system based on intramedullary anchorage of segmental replacement endoprostheses would possibly support physiologic adaptive processes more than fixation over the full length of the stem.

The modular segmental kinematic rotating hinge for nonneoplastic limb salvage

From January 1980 to July 1998, 25 patients (26 knees) were treated with an arthroplasty using a Modular Segmental Kinematic Rotating Hinge total knee prosthesis for nonneoplastic limb salvage. The indications included: nonunion of a periprosthetic femur fracture (11 knees), severe bone loss and ligamentous instability (eight knees), nonunion of a supracondylar femur fracture (four knees), acute periprosthetic fracture (one knee), fracture of a previous hinge (one knee), and prior resection arthroplasty (one knee). The average age of the patients was 72.3 years. Twenty-two arthroplasties were revisions. The average followup was 58.5 months. At the latest followup, knee extension averaged 2.4 degrees and flexion averaged 93.6 degrees. The Knee Society knee score improved from an average of 45.4 preoperatively to 75.5. Preoperatively, functional scores averaged 8.6 and improved to 25. Complications occurred in eight patients. The most common was deep infection (five patients). The use of the Modular Kinematic Rotating Hinge for nonneoplastic limb salvage represents a small proportion (0.14%) of all primary and revision knee arthroplasties done at our institution. The indications for the surgery are for a highly complex and small subset of patients. The patients in the current study gained significant improvement in overall range of motion, Knee Society knee scores, and functional scores when this prosthesis was used.

Knee arthrodesis after infected tumor mega prosthesis of the knee using an intramedullary nail for callus distraction

BACKGROUND

Infected tumor endoprosthesis of the knee in young patients can prove to be challenging. Common procedures are débridement and prosthesis reimplantation, amputation, revision arthroplasty, and arthrodesis.

CASE PRESENTATION

We report the case of a 44-year-old man treated by arthrodesis followed by callus distraction after removal of an infected tumor mega prosthesis (Kotz type). Callus distraction was performed over a distance of 11 cm in 4 months using a femorotibial intramedullary nail with an external traction rope-winch system.

METHODS AND FOCUS

The clinical, radiological, technical, and therapeutic features are discussed.