Prosthetic knee replacement after resection of a malignant tumor of the distal part of the femur. Medium to long-term results

Recovery of leg strength based on isokinetic testing after tumor resection and reconstruction with a modular rotating hinge knee system: Prospective cross-sectional study with a minimum follow-up of 24 months

BACKGROUND

While modular reconstruction implants can be used to replace the bone lost after bone tumor resection, tumor excision from the neighboring soft tissues can lead to loss of strength and joint range of motion (ROM), which results in worse knee function. Functional recovery after total knee arthroplasty for osteoarthritis has been extensively documented. But few studies have evaluated the recovery after total knee reconstruction following tumor excision despite the fact that most of these patients are young and have high functional demands. We did a prospective cross-sectional study to: 1) compare muscle strength recovery around the knee with an isokinetic dynamometer after tumor excision and reconstruction with a modular implant to the healthy contralateral knee; 2) determine if the differences in peak torque (PT) in the knee extensors and flexors had a clinical impact.

HYPOTHESIS

Resection of soft tissues during tumor excision around the knee causes strength loss that cannot be fully recovered.

METHODS

The 36 patients who underwent extra- or intra-articular resection of a primary or secondary bone tumor in the knee area followed by reconstruction with a rotating hinge knee system between 2009 and 2021 were eligible for this study. The primary outcome was the ability to actively lock the operated knee. The secondary outcomes were the concentric PT during isokinetic testing at slow (90°/sec) and fast (180°/sec) speeds, flexion-extension ROM, Musculoskeletal Tumor Society (MSTS) score, the IKS, Oxford Knee Score (OKS) and KOOS.

RESULTS

Nine patients agreed to participate in the study, all of whom had regained the ability to lock their knee postoperatively. PT in flexion and extension on the operated knee was less than the healthy knee. The PT ratio for the operated/healthy knee at 60°/sec and 180°/sec in flexion was 56.3%±16.2 [23.2-80.1] and 57.8%±12.3 [37.7-77.4], respectively, which corresponded to a slow-speed strength deficit of 43.7% in the knee flexors. The PT ratio for the operated/healthy knee at 60°/sec and 180°/sec in extension was 34.3%±24.6 [8.6-76.5] and 43%±27.2 [13.1-93.4], respectively, which corresponded to a slow-speed strength deficit of 65.7% in the knee extensors. The mean MSTS was 70%±20 [63-86]. The OKS was 29.9/48±11 [15-45], the mean IKS knee was 149.6±36 [80-178] and the mean KOOS was 67.43±18.5 [35-88.7].

DISCUSSION

Despite all patients having the ability to lock out their knee, there was an imbalance in the strength between opposite muscle groups: 43.7% strength deficit at slow-speed and 42.2% at fast speed for the hamstring muscles, and 65.7% at slow-speed and 57% at fast speed for the quadriceps muscles. This difference is considered pathological with an increased risk of knee injury. Despite this strength deficit, this joint replacement technique, which is free of complications, can preserve good knee function with acceptable knee joint ROM and satisfactory quality of life.

LEVEL OF EVIDENCE

III; prospective cross-sectional case-control study.

What Is the Long-term Survivorship of Primary and Revision Cemented Distal Femoral Replacements for Limb Salvage of Patients With Sarcoma?

BACKGROUND

Cemented endoprosthetic reconstruction after resection of primary bone sarcomas has been in common use for decades. Although multiple studies have reported the survivorship of primary endoprostheses, implant survivorship after revision surgery is less well established. Given that earlier advances in systemic therapy improved survival of patients with sarcoma, the usage of revision endoprostheses can be expected to increase and, as such, understanding revision implant survivorship will help to inform patient and surgeon expectations. Additionally, as new implants are developed that allow alternative reconstruction options, a normative dataset establishing accurate expectations for revision cemented endoprostheses is a critical benchmark by which to measure progress.

QUESTIONS/PURPOSES

(1) What is the implant survivorship free of all-cause revision for primary and revision cemented distal femoral replacements (DFRs) used in the treatment of malignant or benign tumors? (2) What are the most common indications for revision of primary and revision DFRs in an oncology population with mean follow-up of more than 10 years? (3) How does the indication for revision of a primary DFR affect the subsequent risk for and type of revision DFR complication? (4) What patient, tumor, or implant characteristics are associated with improved survivorship free of revision in cemented DFRs used in patients treated initially for primary malignant or benign tumors?

METHODS

This was a retrospective, comparative study using our institution's longitudinally-maintained database of 806 cemented endoprostheses starting in 1980 and assessed through December 31, 2018. In all, 365 DFRs were inserted during this time, but 14% (51 of 365) were placed for nonprimary bone tumors and 1% (5 of 365) were cementless reconstructions, leaving 309 cemented DFRs. Seventy-one percent (218 of 309) were primary implants and 29 percent (91 of 309) were revision implants (used to revise a prior DFR in all patients). During this time period, our strong bias was to use cemented stems and, thus, nearly all of our patients had cemented stems. Six percent (13 of 218) of primary DFRs were implanted more than 2 years before the study end; however, they lacked 2 years of follow-up data and, thus, were considered lost to follow-up, leaving 205 implants in the primary DFR analysis group. Only the first revision after primary DFR revision surgery was included in the revision cohort analysis. Thirty-two percent (29 of 91) of revision DFRs were second or more revision patients and were excluded, leaving 62 implants in the revision analysis group. Most patients in both groups were men (57% [117 of 205] for primary and 71% [44 of 62] for revision) who had been diagnosed with osteosarcoma (75% [153 of 205] and 73% [45 of 62] for primary and revision, respectively). The primary cohort had mean age of 26 ± 16 years with a mean follow-up of 136 ± 122 months, and the revision cohort had mean age of 31 ± 13 years (p = 0.02) with 141 ± 101 months of follow-up. Study endpoints included all-cause implant revision and cause-specific revision for soft tissue complications, aseptic loosening, structural complications (defined as periprosthetic or implant fracture), infection, or tumor progression. Planned surgery for implant lengthening procedures was excluded. Implant survivorship free from all-cause revision was calculated using a competing risk (cumulative incidence) estimator with death as a competing risk. A log-rank test using chi-square analysis was used to evaluate the differences in implant survivorship between primary DFRs and first revisions. The cause-specific incidences of implant revision were tabulated for primary and revision DFRs. Cox regression analysis investigated the odds of subsequent all-cause revision surgery for revision cemented DFRs based on the primary implant complication. A binary logistic regression analysis using age, gender, indication for revision, tumor type, infection, perioperative chemotherapy, and radiation was performed to identify factors associated with a second DFR reoperation. Relative effect sizes are reported as ORs.

RESULTS

The revision DFR cohort had a shorter mean survival to all-cause revision than the primary cohort (mean 10 years [95% CI 7 to 12] versus 18 years [95% CI 15 to 20]; p < 0.001). The most common complications necessitating revision for revision implants were periprosthetic or implant fracture in 37% (23 of 62) and aseptic loosening in 15% (9 of 62), and the type of primary implant complication was not associated with risk of subsequent all-cause revision surgery for revision implants. Stem diameter less than 15 mm was associated with repeat all-cause revision in cemented revision DFRs after controlling for resection length, stem length, implant fabrication (custom or modular), and presence of a porous collar (OR 4 [95% CI 1 to 17]; p = 0.03). No other parameters that we explored, including patient age, gender, chemoradiation history, or primary tumor diagnosis, were associated with repeat revision surgery.

CONCLUSION

Understanding modifiable factors that can improve revision DFR survival is critical to achieving long-term limb salvage for patients with tumors around the knee. Our data suggest that utilizing implants with the largest possible stems-or at a minimum increasing the stem size over the primary implant-is important to revision cemented DFR survivorship and is an important part of our revision practice. Improving revision implants' resistance to aseptic loosening through designs that resist torsion (a common mode of cemented fixation failure)-such as with the use of custom cross-pin fabrication-may be one method to improve survivorship. Another will be improved implant metallurgy that is resistant to fatigue fracture. Next steps may include understanding the optimal ratio of femoral diaphyseal width to implant diameter in patients where anatomic constraints preclude the insertion of cemented stems 15 mm or more in diameter.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Time to Functional Outcome Optimization After Musculoskeletal Tumor Resection

Background

There is ample literature describing surgical outcomes after oncologic musculoskeletal tumor surgery, however, there is limited understanding of the time to optimization of functional outcome scores after resection. The purpose of this study was to identify the time to functional outcome optimization of Musculoskeletal Tumor Society (MSTS) scores after surgery for bone and soft tissue tumors and to identify factors correlated with recovery.

Methods

We retrospectively reviewed 187 patients from April 2016 to May 2021 that had undergone surgical treatment for musculoskeletal tumors. We assessed MSTS scores to determine the time to optimization and evaluated patient-specific and surgical factors for any influence on post-operative recovery.

Results

The majority of patients (92%) achieved their optimized score in one year or less. Eighty-two percent achieved the maximum MSTS score of 30. Osseous tumors, malignancy, adjuvant treatment with radiation and/or chemotherapy, deep location for soft tissue tumors, and bony work required for soft tissue tumors all significantly impacted time to MSTS score optimization.

Conclusion

The majority of patients with musculoskeletal tumors undergoing surgery can be expected to improve up to one year postoperatively. Those with bone tumors, malignant tumors, treatment with radiation and/or chemotherapy, deep soft tissue tumors, and bony work for soft tissue tumors can expect to have a longer recovery time and are at higher risk for not achieving premorbid functionality.

Revision surgeries for tumor endoprostheses around the knee joint: a mid-long-term follow-up of 20 cases

Background

Tumor endoprostheses of the knee joint after limb salvage surgery is associated with high rates of complications, which has introduced great challenges to a delayed revision surgery. The aim of the study was to summarize the failures, functional outcomes and prosthetic survival in revision tumor endoprostheses of the knee joint.

Methods

The clinical data of 20 patients with malignant tumors who received prosthetic revisions after limb salvage surgery from January, 2000 until January, 2018 were retrospectively reviewed. The cohort was constituted of 11 male and 9 female patients with a mean age of 34.1 years (range, 16 to 66 years). Infection cases received two-stage revisions after removing prostheses initially, while all other cases received one-stage revisions. Revision reasons and complications were well documented and analyzed.

Results

All patients received complete follow-up with a mean time of 64.7 months (range, 27 to 155 months). A total of 6 (6/20, 30.0%) patients experienced a second complication after revision surgery, of whom, one patient with deep infection experienced repeated infections after prosthetic revision and received amputation surgery; one patient revised of prosthetic fracture experienced an infection and received a second-stage infection revision; one case revised of prosthetic loosening had deep infection receiving anti-infective therapy with prostheses still in position; one case having wound complication healed after receiving two times of debridement surgery; one MBGCT patient experienced a second aseptic loosening 6 years after the initial loosening thus undergoing a second revision; a recurrent osteosarcoma patient died of pulmonary metastasis 3 years after revision surgery. Kaplan-Meier survival curve indicated a 5-year survival rate of initial prostheses was 75%. The Musculoskeletal Tumor Society (MSTS-93) score [20.9 (range, 15 to 27 scores)] at 1 year after revision surgeries was significantly improved (p < 0.001) when compared with the score [17.2 (range, 13 to 21 scores)] before revisions.

Conclusion

Prosthetic mechanical problems, aseptic loosening and infections were primary reasons for revisions after tumor endoprostheses of the knee joint. Although revision surgeries were complicated while still associated with high risk of failure, which remains the remedy strategy for limb salvage and functional recovery in those patients.

Survivorship, complications, and outcomes following distal femoral arthroplasty for non-neoplastic indications

Aims

Endoprosthetic reconstruction with a distal femoral arthroplasty (DFA) can be used to treat distal femoral bone loss from oncological and non-oncological causes. This study reports the short-term implant survivorship, complications, and risk factors for patients who underwent DFA for non-neoplastic indications.

Methods

We performed a retrospective review of 75 patients from a single institution who underwent DFA for non-neoplastic indications, including aseptic loosening or mechanical failure of a previous prosthesis (n = 25), periprosthetic joint infection (PJI) (n = 23), and native or periprosthetic distal femur fracture or nonunion (n = 27). Patients with less than 24 months’ follow-up were excluded. We collected patient demographic data, complications, and reoperations. Reoperation for implant failure was used to calculate implant survivorship.

Results

Overall one- and five-year implant survivorship was 87% and 76%, respectively. By indication for DFA, mechanical failure had one- and five-year implant survivorship of 92% and 68%, PJI of 91% and 72%, and distal femur fracture/nonunion of 78% and 70% (p = 0.618). A total of 37 patients (49%) experienced complications and 27 patients (36%) required one or more reoperation. PJI (n = 16, 21%), aseptic loosening (n = 9, 12%), and wound complications (n = 8, 11%) were the most common complications. Component revision (n = 10, 13.3%) and single-stage exchange for PJI (n = 9, 12.0 %) were the most common reoperations. Only younger age was significantly associated with increased complications (mean 67 years (SD 9.1)) with complication vs 71 years (SD 9.9) without complication; p = 0.048).

Conclusion

DFA is a viable option for distal femoral bone loss from a range of non-oncological causes, demonstrating acceptable short-term survivorship but with high overall complication rates.

Cite this article: Bone Jt Open 2022;3(3):173–181.

A long-term experience with Mutars tumor megaprostheses: analysis of 187 cases

PURPOSE

Modular megaprostheses have widely replaced allografts, as a reconstructive option; however, failures of these devices remain high. Aim of this study was to analyze outcomes, survival of the implants, incidence and types of complications with Mutars modular endoprostheses at long term.

METHODS

Between 2000 and 2019, 187 Mutars prostheses were implanted in two dedicated centers: 72 upper limbs and 115 lower limbs reconstructions. Diagnoses included 107 primary malignant bone or soft tissue tumors, 65 metastases, 8 benign bone tumors and 7 non-oncologic cases. Silver-coated prostheses were used in 118/187 (63%) cases.

RESULTS

At last follow-up, 76.5% of patients had retained their implant. The overall failure rate was 23.5% at a mean of 1.7 years. There were 22 mechanical failures and 22 non-mechanical failures. The overall implant survival to all types of failure was 68% and 52% at 5 and 10 years, respectively. Infection was the most common mode of failure with an incidence of 6.9%. Implant survival to infection was better for silver-coated implants than for standard implants even if with no significant difference (p = 0.56). Functional results were satisfactory in 97% of patients.

CONCLUSIONS

The overall implant survival at long term was satisfactory with Mutars prostheses. The incidence of complications with Mutars prosthesis is in line with the incidence reported in the literature with other types of tumor prosthesis. The most frequent cause of failure was infection with a lower incidence in silver-coated prostheses; silver coating seems to prevent infection in distal femur and proximal tibia. The silver coating seems to be particularly useful in two-stage revisions with a lower incidence of secondary amputation. In higher risk patients, silver-coated prostheses are the preferable choice for the reduction of the reinfection rate. The functional results of Mutars prostheses were excellent or good in most of cases. The current paper is design to enhance the literature on megaprosthesis in tumor surgery, proven that this system is one of the most used all over the word and one of the best performing.

Is magnetic resonance imaging reliable for assessing osteosarcoma of the knee joint in children?

INTRODUCTION

The study of tumor extension in knee osteosarcomas is an essential diagnostic tool that helps determine the surgical approach. Magnetic resonance imaging (MRI) is the key component in this decision-making process, but the interpretation of signals can be difficult because peritumoral edema and inflammation may be mistaken for the tumor.

HYPOTHESIS

There is a discrepancy between MRI and histopathology findings in the assessment of joint involvement in pediatric osteosarcomas of the knee.

MATERIALS AND METHODS

All children who underwent an extra-articular resection for an osteosarcoma of the knee between 2007 and 2016 were included. This was indicated if there was at least one of the following MRI signs: presence of articular effusion, involvement of either the peripheral capsuloligamentous structures, central pivot or patella, or lesion abutting the articular cartilage.

RESULTS

Nine patients were operated on with a mean age of 13±2.7 years. There were at least two of the described signs, mainly the involvement of the peripheral capsuloligamentous structures (78%) and central pivot (56%). The histopathology confirmed that the resection margins were healthy in all cases, but the indication for extra-articular resection could have been avoided in 89% of them.

DISCUSSION

MRI is the current gold standard for assessing tumor extension, but the signs contraindicating the transarticular approach remain poorly defined. Joint effusion detected by clinical or radiological assessment is the least reliable one. It seems that the tumor's proximity to the articular cartilage, as long as there is no loss of continuity in the latter, or its extension into the central pivot should no longer be considered as relevant signs. The involvement of the peripheral capsuloligamentous structure remains an indication criterion because oncologic resection is otherwise impossible, and the risk of false-negative histopathologic diagnoses is higher. Other MRI sequences could better assess the true extension into the joint space.

LEVEL OF EVIDENCE

IV, retrospective study.

Long-term competing risks for overall and cause-specific failure of rotating-hinge distal femoral arthroplasty for tumour reconstruction

AIMS

Rotating-hinge knee prostheses are commonly used to reconstruct the distal femur after resection of a tumour, despite the projected long-term burden of reoperation due to complications. Few studies have examined the factors that influence their failure and none, to our knowledge, have used competing risk models to do so. The purpose of this study was to determine the risk factors for failure of a rotating-hinge knee distal femoral arthroplasty using the Fine-Gray competing risk model.

METHODS

We retrospectively reviewed 209 consecutive patients who, between 1991 and 2016, had undergone resection of the distal femur for tumour and reconstruction using a rotating-hinge knee prosthesis. The study endpoint was failure of the prosthesis, defined as removal of the femoral component, the tibial component, or the bone-implant fixation; major revision (exchange of the femoral component, tibial component, or the bone-implant fixation); or amputation.

RESULTS

Multivariate Fine-Gray regression analyses revealed different hazards for each Henderson failure mode: percentage of femoral resection (p = 0.001) and extent of quadriceps muscle resection (p = 0.005) for overall prosthetic failure; extent of quadriceps muscle resection (p = 0.002) and fixation of femoral component (p = 0.011) for type 2 failure (aseptic loosening); age (p = 0.009) and percentage of femoral resection (p = 0.019) for type 3 failure (mechanical failure); and type of joint resection (p = 0.037) for type 4 (infection) were independent predictors. A bone stem ratio of > 2.5 reliably predicted aseptic loosening.

CONCLUSION

We identified independent risk factors for overall and cause-specific prosthetic failure after rotating-hinge knee distal femoral arthroplasty using a competing risk Fine-Gray model. A bone stem ratio > 2.5 reliably predicts aseptic loosening. An accurate knowledge of the risks of distal femoral arthroplasty after resection for tumour assists surgical planning and managing patient expectations. Cite this article: Bone Joint J 2021;103-B(8):1405-1413.

Distal femoral replacement - Cemented or cementless? Current concepts and review of the literature

Distal femoral endoprosthetic replacement has been successfully used to reconstruct distal femoral defects after tumor resection for over four decades. Despite continued advances, aseptic loosening continues to be the most common failure mode after infection. Debate still exists about a variety of design features and the optimal fixation method remains controversial. To date, no large-scale study or meta-analysis has demonstrated the superiority of one fixation technique over another. While the classic dichotomy of cemented versus cementless stems is well-known, the contemporary surgeon needs to fully understand the optimal clinical setting for each type of fixation technique and additional strategies to maximize implant stability. In clinical practice, the choice of fixation must be tailored to the individual patient. The surgeon must consider whether the operation is being performed for primary sarcoma or metastatic carcinoma, the presence of distant metastases, age, comorbidities, and whether radiotherapy has been previously given or will be required at the site of fixation. The best strategy for each patient optimizes tumor control and appropriately weighs risks of fixation failure versus the expected patient survival. This review will explore cemented and uncemented distal femoral replacement and highlight modern concepts to optimize each technique.

Finn/Orthopaedic Salvage System Distal Femoral Rotating-Hinge Megaprostheses in Oncologic Patients: Long-Term Complications, Reoperations, and Amputations

BACKGROUND

There is a lack of evidence regarding long-term outcomes of rotating-hinge knee prostheses with distal femoral replacement in a large oncologic patient series. In this study, we investigated the proportion of patients experiencing complications requiring surgery in the long term, as well as the cumulative incidence of implant removal/revision and amputation at 5, 10, 15, and 20 years through competing risk analyses.

METHODS

We retrospectively studied 214 patients treated with a Finn/Orthopaedic Salvage System (OSS) knee prosthesis (Zimmer Biomet) after distal femoral resection from 1991 to 2017. The study end points were postoperative complications requiring surgery. Reoperations were classified as major when there was (1) removal of the metal-body femoral component, the tibial component, or the bone-implant fixation; (2) major revision (exchange of the metal-body femoral component, the tibial component, or the bone-implant fixation); or (3) amputation. Minor reoperations were defined as all other reoperations. Competing risk analysis was used to estimate the cumulative incidence of implant removal/revision or amputation.

RESULTS

There were 312 reoperations in 113 patients (98 major reoperations in 68 patients and 214 minor reoperations). Seventeen patients (8%) required ≥5 additional operations, and 21 patients (10%) required >1 major reoperation. Although the number of reoperations decreased over time, major and minor reoperations continuously accrued after 10 years. The cumulative incidences of implant removal or revision for any reason at 5, 10, 15, and 20 years were 22.6%, 30.1%, 34.3%, and 42.5%, respectively. Although most implant removals/revisions occurred in the first 10 years, the risk persisted after 10 years, at a mean of 1.24%/year, mainly due to deep infection (1.06%/year).

CONCLUSIONS

The long-term outcomes of treatment with a Finn/OSS distal femoral rotating-hinge knee prosthesis showed it to be a durable reconstruction technique. The rate of implant removal/revisions after 10 years was gradual (1.24%/year). Deep infection remains a major late-failure mechanism, and lifetime surveillance for prosthetic problems is needed.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Molded, Gamma-radiated, Argon-processed Polyethylene Components of Rotating Hinge Knee Megaprostheses Have a Lower Failure Hazard and Revision Rates Than Air-sterilized, Machined, Ram-extruded Bar Stock Components

BACKGROUND

Megaprostheses are commonly used for reconstruction after distal femoral resection in orthopaedic oncology. The polyethylene bearings in these reconstructions experience wear and wear-related complications that may result in revision surgery. Improved manufacturing and processing of polyethylene has increased the durability of components commonly used for routine arthroplasty. Alterations in the manufacture of polyethylene is expected to reduce the revision risk of oncologic megaprostheses, resulting in fewer revision procedures, but this has not been proven.

QUESTIONS/PURPOSES

Is there a difference in the hazard of polyethylene wear or breakage leading to prosthetic revision between differences in polyethylene manufacture and processing based on a competing risk analysis?

METHODS

This was a single-center, observational, retrospective comparative study of 224 patients who had distal femur megaprostheses with identical rotating hinge articulations and knee kinematics after oncologic surgery from 1993 to 2015. No differences in surgical indications, joint articular components and kinematics, age, sex, diagnosis, BMI, use of chemotherapy, or tumor stage were seen with the patient numbers available. Prosthetic survivorship free from prosthetic revision surgery because of polyethylene wear-related revisions, defined as breakage, increased excursion on varus-valgus stress, or new locking or giving way was compared between two groups of patients: group 1 polyethylene (P1) (66 patients) who had air-sterilized machined ram-extruded bar stock or group 2 polyethylene (P2) (158 patients) molded gamma-radiated argon-processed polyethylene components. The mean follow-up duration for the P1 group (89 ± 55 months) was not different from that of patients with P2 polyethylene (79 ± 63 months; p = 0.24) including 27% (18 of 66) of patients in the P1 group and 25% (40 of 158) of patients in the P2 group followed for more than 10 years. More patients in the P2 group were lost to follow-up (9.2%, 16 of 174) than in the P1 group (5.7%, 4 of 70) but this was not statistically different (chi square; p = 0.37). The hazard of revision because of polyethylene wear or breakage was calculated with a competing risk analysis using the Fine-Gray subdistribution hazard model.

RESULTS

The P1 implants had a higher hazard ratio for revision caused by polyethylene damage at 120 months than did the P2 polyethylene implants (P1 HR 0.24 [95% CI 0.13 to 0.36] versus HR 0.07 [95% CI 0.03 to 0.12]), which represents an estimated absolute risk reduction of 17% (95% CI 6.15 to 27.9).

CONCLUSION

Polyethylene damage can result in megaprosthetic revisions in patients undergoing oncologic procedures. The hazard of polyethylene failure resulting in revision surgery was lower in patients who received recent polyethylene than in patients with polyethylene produced by previous methods, enhancing the durability of distal femoral megaprosthetic reconstructions. Despite improvements in polyethylene manufacture and clinical results, revision solely because of polyethylene damage still occurs in 7% of patients by the 10-year timepoint; thus, more improvement is needed. Patients who receive these implants should be monitored for signs and symptoms of polyethylene damage.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Do irradiated osteo-articular recycled tumor autografts still hold promise for biological joint reconstruction? Our experience with acetabular and proximal ulna ECRT

BACKGROUND

Joint reconstruction following resection of malignant bone tumors is challenging in itself in spite of several options in hand. Ability to restore joint anatomy, function and mobility while achieving optimal oncological outcomes are the requirement of reconstructions today. While biological reconstructions (allograft or recycled tumor autografts) following tumor bone surgery are popular for intercalary resections not involving the joint, their use for osteo-articular reconstructions are associated with concerns over cartilage and joint health. We have used extracorporeal radiation therapy (ECRT) and re-implantation of the osteoarticular segment as a size matched recycled tumor autograft reconstruction after complex acetabular and proximal ulnar resections; owing to the lack of significantly superior reconstruction alternatives in these locations and also review the current literature on other biological/non-biological reconstruction options.

QUESTIONS/PURPOSES

(1) What are the oncological, reconstruction and functional outcomes with osteo-articular reconstruction using ECRT and re-implantation of recycled tumor autograft for the acetabulum and olecranon? (2) Is there an evidence of cartilage loss, joint damage or avascular necrosis resulting from irradiation of the articular autograft?

METHODS

19 patients with primary bone tumors underwent limb salvage surgery with en-bloc resection and reconstruction using the resected articular tumor bone after treating it with extra-corporeal irradiation of 50-60Gy. These included 16 acetabular and 3 proximal ulnar. While all patients were included for oncological assessment; minimum follow-up of 24 months was considered for final outcome assessment of function and joint status.

RESULTS

MSTS scores of the 16 acetabular reconstruction patients with minimum 2 years follow-up was 87% (26/30). Neither delayed union, non-union at osteotomy sites nor was any fractures reported in the irradiated graft. There was no local recurrence within the irradiated graft and only 1 patient required graft excision for uncontrolled infection. All 3 patients of proximal ulna reconstruction achieved healing and full range of movement of the elbow. Scores of MSTS: 100% (30/30), MEPS: 100 and DASH: zero was achieved. Two patients developed osteonecrosis of the femoral head; one requiring a joint replacement and one awaiting replacement. One patient of acetabular reconstruction has joint space narrowing on radiographs with mild clinical symptoms.

CONCLUSIONS

Extracorporeal radiotherapy and re-implantation after osteo-articular resection is an oncologically safe option offering promising outcome in our small series. The availability of size-matched graft, thus avoiding inherent problems of allograft also provides a better economic option over endoprosthesis and its associated complications in select sites. The results can deteriorate over time that may require secondary reconstructive procedures like joint replacement.

LEVEL OF EVIDENCE

Level IV, Therapeutic Study.

Compressive osseointegration for endoprosthetic reconstruction

This review summarizes the biomechanical concepts, clinical outcomes and limitations of compressive osseointegration fixation for endoprosthetic reconstruction. Compressive osseointe - gration establishes stable fixation and integration through a novel mechanism; a Belleville washer system within the spindle applies 400-800 PSI force at the boneimplant interface. Compressive osseointegration can be used whenever standard endoprosthetic reconstruction is indicated. However, its mode of fixation allows for a shorter spindle that is less limited by the length of remaining cortical bone. Most often compressive osseointegration is used in the distal femur, proximal femur, proximal tibia, and humerus but these devices have been customized for use in less traditional locations. Aseptic mechanical failure occurs earlier than with standard endoprosthetic reconstruction, most often within the first two years. Compressive osseointegration has repeatedly been proven to be non-inferior to standard endoprosthetic reconstruction in terms of aseptic mechanical failure. No demographic, device specific, oncologic variables have been found to be associated with increased risk of aseptic mechanical failure. While multiple radiographic parameters are used to assess for aseptic mechanical failure, no suitable method of evaluation exists. The underlying pathology associated with aseptic mechanical failure demonstrates avascular bone necrosis. This is in comparison to the bone hypertrophy and ingrowth at the boneprosthetic interface that seals the endosteal canal, preventing aseptic loosening.

What Is the 10-year Survivorship of Cemented Distal Femoral Endoprostheses for Tumor Reconstructions and What Radiographic Features Are Associated with Survival?

BACKGROUND

Aseptic loosening is one of the most common causes of revision of distal femoral endoprostheses and is considered a mid- to long-term complication. There are not many reports of 10-year survivorship free from aseptic loosening and all-cause survivorship in cemented stems. To our knowledge, there are no reports on radiographic features that are associated with aseptic loosening of these implants.

QUESTIONS/PURPOSES

(1) What is the 5- and 10-year survivorship free from aseptic loosening in patients undergoing reconstruction with a cemented distal femoral endoprosthesis after a tumor resection? (2) What is the all-cause 5- and 10-year survivorship at in these patients? (3) What radiographic features are associated with aseptic loosening at long-term follow-up?

METHODS

We performed a multicenter retrospective study reviewing aseptic loosening in cemented prostheses to determine radiographic features associated with long-term implant survivorship. Patients who underwent a cemented distal femoral reconstruction with a modular endoprosthesis after resection of a musculoskeletal tumor between 1997 and 2017 were reviewed. A total of 246 patients were identified from five institutions and met initial inclusion criteria. Of those, 21% (51) were lost to follow-up before 2 years, leaving 195 patients available for us to evaluate and analyze the survivorship and radiologic features associated with long-term implant survival. The mean (range) follow-up was 78 months (22 to 257). At the time of this analysis, 69% (135 of 195) of the patients were alive. Osteosarcoma was the most common diagnosis in 43% of patients (83 of 195), followed by metastatic carcinoma 13% (25 of 195). Fifty-six percent (110 of 195) of patients received chemotherapy; 15% (30 of 195) had radiation therapy. Aseptic loosening was diagnosed radiographically and was defined as a circumferential radiolucent line on all views, or subsidence around the stem in the absence of infection. We present 5- and 10-year Kaplan-Meier survivorship free from aseptic loosening, 5- and 10-year all-cause survivorship, and a qualitative assessment of radiographic features potentially associated with aseptic loosening (including the junctional radiolucent area, and cortical expansion remodeling). The junctional radiolucent area was defined as a radiolucent area of the bone starting at the bone-endoprosthesis junction to the tip of the femoral stem, and cortical expansion remodeling was defined as an increased cortical thickness at the stem tip. Although we wished to statistically analyze radiographic factors potentially associated with aseptic loosening, we did not have enough clinical material to do so (only nine patients developed loosening). Instead, we will report a few preliminary qualitative observations, which necessarily are preliminary, and which will need to be confirmed or refuted by future studies. We urge caution in interpreting these findings because of the very small numbers involved.

RESULTS

Kaplan-Meier survivorship free from aseptic loosening of the femoral component at 5 and 10 years were 95% (95% CI 89 to 98) and 93% (95% CI 86 to 97), respectively. Kaplan-Meier survivorship free from revision for any cause at 5 and 10 years were 74% (95% CI 65 to 79) and 64% (95% CI 49 to 70), respectively. Although the numbers were too small to analyze statistically, all patients with aseptic loosening had a junctional radiolucent area more than 20% of the total length of the stem without cortical expansion remodeling at the stem tip. No aseptic loosening was observed if there was cortical ex remodeling, a junctional radiolucent area less than 20%, or curved stems that were 13 mm or greater in diameter. The numbers of patients with aseptic loosening in this series were too small to analyze statistically.

CONCLUSIONS

Cemented distal femoral endoprostheses have a relatively low rate of aseptic loosening and acceptable projected first-decade survivorship. The presence of a radiolucent area more than 20% without cortical expansion remodeling at the stem tip may lead to aseptic loosening in patients with these implants. Close radiographic surveillance and revision surgery may be considered for progressive lucencies and clinical symptoms of pain. If revision is contemplated, we recommend using larger diameter curved cemented stems. These are preliminary and provisional observations based on a low number of patients with aseptic loosening; future studies with greater numbers of patients are needed to validate or refute these findings.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Limb Salvage Using Liquid Nitrogen-Treated Tumour-Bearing Autograft: A Single Institutional Experience of 10 Patients

BACKGROUND

Many reconstruction methods have evolved to offer limb salvage surgery (LSS) to patients with musculoskeletal sarcomas. It can be achieved using endoprosthesis or biological reconstruction methods like allograft or autograft or a combination of both. In carefully selected patients, resected bone can be recycled and reimplanted after sterilisation using methods like irradiation, autoclaving, pasteurisation or liquid nitrogen.

METHODS

From 2010 to 2016, 10 patients with primary musculoskeletal sarcoma underwent limb salvage surgery (LSS) by wide resection of the tumour and reconstruction using recycled autograft treated with liquid nitrogen. Intercalary resection was carried out in six patients and intra-articular in four. The resected bone was dipped in liquid nitrogen for 25 min, thawed at room temperature for 15 min followed by dipping in vancomycin-mixed saline for 10 min. The recycled bone was re-implanted into its original site and stabilised with internal fixation.

RESULTS

At a mean follow-up period of 39.6 months (range 6-97 months), all patients had a good function (mean functional score of 80%) with no evidence of local recurrence in the re-implanted bone or otherwise. Union was achieved at 15 of the 16 osteotomy sites with a mean union time of 5.2 months (range 4-7 months) without any additional surgical interventions. In none of the patient, augmentation with vascularised/non-vascularised fibula was done. No complication like fracture of the autograft, implant failure or deep/superficial infection was reported in any patient.

CONCLUSION

Recycled tumour-bearing autograft after treatment with liquid nitrogen is an anatomical, cost-effective, relatively simpler and reliable technique for reconstruction of bone defect after resection in selective primary musculoskeletal sarcoma patients.

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.

Establishment and validation of a nomogram model for aseptic loosening after tumor prosthetic replacement around the knee: a retrospective analysis

Background

Aseptic loosening has become the main cause of prosthetic failure in medium- to long-term follow-up. The objective of this study was to establish and validate a nomogram model for aseptic loosening after tumor prosthetic replacement around knee.

Methods

We collected data on patients who underwent tumor prosthetic replacements. The following risk factors were analyzed: tumor site, stem length, resection length, prosthetic motion mode, sex, age, extra-cortical grafting, custom or modular, stem diameter, stem material, tumor type, activity intensity, and BMI. We used univariate and multivariate Cox regression for analysis. Finally, the significant risk factors were used to establish the nomogram model.

Results

The stem length, resection length, tumor site, and prosthetic motion mode showed a tendency to be related to aseptic loosening, according to the univariate analysis. Multivariate analysis showed that the tumor site, stem length, and prosthetic motion mode were independent risk factors. The internal validation indicated that the nomogram model had acceptable predictive accuracy.

Conclusions

A nomogram model was developed for predicting the prosthetic survival rate without aseptic loosening. Patients with distal femoral tumors and those who are applied with fixed hinge and short-stem prostheses are more likely to be exposed to aseptic loosening.

Supplying osteogenesis to dead bone using an osteogenic matrix cell sheet

PURPOSE

To evaluate whether osteogenic matrix cell sheets can supply osteogenesis to dead bone.

METHODS

Femur bone fragments (5 mm in length) were obtained from Fisher 344 rats and irradiated by a single exposure of 60 Gy to produce bones that were no longer viable. Osteogenic matrix cell sheets were created from rat bone marrow-derived stromal cells (BMSCs). After wrapping the dead bone with an osteogenic matrix cell sheet, it was subcutaneously transplanted into the back of a rat and harvested after 4 weeks. Bone formation around the dead bone was evaluated by X-ray imaging and histology. Alkaline phosphatase (ALP) and osteocalcin (OC) mRNA expression levels were measured to confirm osteogenesis of the transplanted bone. The contribution of donor cells to bone formation was assessed using the Sry gene and PKH26.

RESULTS

After the cell sheet was transplanted together with dead bone, X-ray images showed abundant calcification around the dead bone. In contrast, no newly formed bone was seen in samples that were transplanted without the cell sheet. Histological sections also showed newly formed bone around dead bone in samples transplanted with the cell sheet, whereas many empty lacunae and no newly formed bone were observed in samples transplanted without the cell sheet. ALP and OC mRNA expression levels were significantly higher in dead bones transplanted with cell sheets than in those without a cell sheet (P < 0.01). Sry gene expression and cells derived from cell sheets labeled with PKH26 were detected in samples transplanted with a cell sheet, indicating survival of donor cells after transplantation.

CONCLUSION

Our study indicates that osteogenic matrix cell sheet transplantation can supply osteogenesis to dead bone.

Implant Survival and Complication Profiles of Endoprostheses for Treating Tumor Around the Knee in Adults: A Systematic Review of the Literature Over the Past 30 Years

BACKGROUND

Endoprosthetic replacement has become the mainstream method of reconstruction after tumor resection around the knee for decades, but there is a lack of comprehensive review evaluating the implant outcomes. We performed a systematic review to analyze the implant survival and complication profiles of distal femoral replacement (DFR) and proximal tibial replacement (PTR) in adults, and to evaluate the effects of different fixation methods and hinge mechanisms.

METHODS

A systematic review of 40 studies with 4748 DFR cases and 1713 PTR cases was performed after searching the PubMed and EMBASE databases. Results of the implant longevity, complications, and other relevant data were extracted, recategorized, and analyzed. An additional review of 227 cases of Compress DFR from 6 studies was also performed.

RESULTS

The mean 5-, 10-, 15-, and 20-year implant survival rates of DFR were 78.3%, 70.1%, 61.6%, and 38.3%, slightly higher than those of PTR (75%, 60%, 55.3%, and 25.1%). Aseptic loosening (8.8%) and infection (8.5%) were the most devastating complications in DFR, while in PTR it was infection (16.8%). Cemented or cementless fixation did not significantly affect implant survival or aseptic loosening rate. Rotating-hinge mechanism might improve long-term implant survival and reduce bushing wear, but not necessarily prevented aseptic loosening. The series Kotz modular femur and tibia replacement system/Howmedica modular replacement system/global modular replacement system was one of the most durable implants. The Compress DFR showed no superiority in implant survival and complication profiles over other brands of endoprostheses.

CONCLUSION

Short-term to mid-term implant survival of adult tumor endoprostheses around the knee is acceptable but long-term outcome remains unsatisfactory. Efforts should be made in reducing loosening and infection.

Comparison between uncemented and cemented fixation for the tibial component in distal femoral replacement: a clinical and radiological study

PURPOSES

We performed a retrospective, cohort study to compare uncemented tibial fixation with cemented tibial fixation in distal femoral replacement (DFR).

METHODS

Sixty-two cases with uncemented tibial fixation and 58 cases with cemented tibial fixation were included. Inter-group comparisons were performed for baseline data, oncological and prosthetic outcomes, and changes of cortical thickness of tibial diaphysis. Radiological signs of bone adaptations around the uncemented tibial stem were identified through evaluation of plain films during follow-up.

RESULTS

Uncemented tibial fixation shortened operative duration by 26 minutes, achieved equivalent oncological and prosthetic outcomes, and helped preserve anterior cortical thickness of tibia compared with the cemented counterpart after a mean follow-up of over 40 months. Radiological signs of osseointegration and reactive line were observed in 64.3 and 17.9% cases with uncemented tibial fixation. The two signs had different patterns of distribution and no significant predisposing factors could be identified.

CONCLUSIONS

For DFR, the uncemented tibial fixation was safe and effective in functional reconstruction and in preservation of anterior cortex of tibial diaphysis. It could achieve osseointegration and might permit adaptive micromotion of the tibial stem post-operatively.

LEVEL OF EVIDENCE

level III Therapeutic.

Surgical and Functional Outcomes After Limb-Preservation Surgery for Tumor in Pediatric Patients: A Systematic Review

BACKGROUND

Limb-salvage surgery and segmental reconstruction for the treatment of lower extremity osseous tumors in the pediatric population have been described in the literature, but there is little consensus regarding the optimal surgical treatment for this patient population.

METHODS

A systematic review of the literature was performed to identify studies focusing on limb-salvage procedures in pediatric patients who were managed with one of three reconstructions with use of a metallic endoprosthesis, allograft, or allograft-prosthesis composite. Data were segregated according to the excised and reconstructed anatomical location (proximal part of the femur, total femur, distal part of the femur, proximal part of the tibia) and were collated to assess modes of failure and functional outcomes of each reconstruction type for each anatomic location.

RESULTS

Sixty articles met the inclusion criteria; all were Level-IV evidence, primarily consisting of small, retrospective case series. Infection was a primary mode of failure across all reconstruction types and locations, whereas allograft reconstructions were susceptible to structural failure as well. The rate of failure in the pediatric population correlated well with previously published results for adults. The incidence of subsequent amputation was lower in the pediatric population (5.2%) than has been reported in adults (9.5%) (p = 0.013). Meaningful growth of expandable metallic endoprostheses was reported in the literature, with an overall rate of leg-length discrepancy of 13.4% being noted at the time of the latest follow-up. The Musculoskeletal Tumor Society (MSTS) questionnaire was the most consistently used outcome measure in the literature, with average scores ranging from 71.0% to 86.8%, depending on reconstruction type and anatomic location.

CONCLUSIONS

The current state of the literature detailing the surgical and functional outcomes of segmental reconstruction for the treatment of pediatric bone tumors is limited to Level-IV evidence and is complicated by under-segregation of the data by age and anatomical location of the reconstruction. Despite these limitations, pediatric limb-salvage surgery demonstrates satisfactory initial surgical and functional outcomes.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Local Control of Soft Tissue and Bone Sarcomas

Sarcomas of soft tissue and bone are mesenchymal malignancies that can arise in any anatomic location, most commonly the extremity, retroperitoneum, and trunk. Even for lower grade histologic subtypes, local recurrence can cause significant morbidity and even disease-related death. Although surgery remains the cornerstone of local control, perioperative radiation and systemic therapy are often important adjuvants. This review will summarize the current therapeutic approaches for local control of soft tissue and bone sarcomas.

Cortical Atrophy Related to Tumor Prosthesis in Skeletally Immature Osteosarcoma Patients

BACKGROUND

Cortical atrophy is commonly observed after prosthetic reconstruction for bone sarcomas. However, relevant literature regarding this phenomenon in skeletally immature patients is limited. Therefore, in this study, we evaluated the incidence and patterns of cortical atrophy. We then assessed its predisposing factors. Finally, we analyzed whether cortical atrophy was associated with poor prosthesis survival.

METHODS

We retrospectively reviewed 31 stems in 19 skeletally immature osteosarcoma patients who were treated with resection and tumor prosthesis surgery. We measured the cortical thickness using plain radiographs annually. The mean patient age was 11 years (range, 6 to 14 y) and the mean follow-up period was 10 years (range, 2 to 14 y).

RESULTS

Cortical atrophy developed in 13 stems, all within 3 years. There were 3 gross types of cortical atrophy: hourglass in 5, sharpening in 4, and shortening atrophy in 4. On multivariate analysis, stem-cortex diameter ratio of ≥0.5 and age of less than 10 years were significantly associated with cortical atrophy (P=0.002 and P=0.019, respectively). Cortical atrophy was significantly associated with eventual prosthesis failure (9/13 in the cortical atrophy group vs. 4/18 in the nonatrophy group, P=0.035).

CONCLUSIONS

Cortical atrophy is common in the skeletally immature patients with tumor prosthesis and is associated with prosthesis failure. Patients with cortical atrophy should be closely monitored for prosthesis failure and appropriately managed to prevent failures.

LEVEL OF EVIDENCE

Level IV-therapeutic study.

En bloc resection, intraoperative extracorporeal irradiation and re-implantation of involved bone for the treatment of limb malignancies

Reconstruction of the defect following limb-sparing resection of malignant bone tumors is controversial and extremely challenging. Extracorporeal irradiation (ECI) and re-implantation have been used for limb salvage surgery for patients, with major advantages, including biological reconstruction, ready availability and preservation of bone stock, over replacement with a megaprosthesis. The purpose of the present study was to present our experience and details of all patients treated with this surgery. Between June 2005 and December 2014, we followed-up 23 patients with limb malignancies who were treated with en bloc excision followed by 50-Gy single dose ECI and re-implantation of involved bone segments. All cases were evaluated based on clinical and radiological examinations, complications and Musculoskeletal Tumor Society (MSTS) score. Mean follow-up period was 77.6 months (range, 17-116 months). A total of 17 patients (73.9%) demonstrated no evidence of disease, 5 (21.7%) patients succumbed to the disease and 1 (4.3%) patient was alive with the disease at the final follow-up. Local recurrence occurred in 3 patients (recurrence rate, 13.0%) in the bed outside of the irradiated graft, and 4 of the 5 patients that lost their lives did so due to associated metastatic disease. The mean value of the MSTS score was 78.8% (50-93.3%). The majority of patients demonstrated solid bony union; however, 3 patients had non-union (13.0%) and 1 had a delayed union (4.3%). Early or late complications occurred in 11 patients (47.8%). Although the complication rate (47.8%) and re-operation rate (39.1%) were high, ECI and re-implantation may be a useful and cheap technique following en bloc resection for limb salvage in appropriately selected patients.

Vascularised fibular grafts for reconstruction of extremity bone defects after resection of bone and soft-tissue tumours : a single institutional study of 49 patients

AIMS

The aims of this study were to analyse the long-term outcome of vascularised fibular graft (VFG) reconstruction after tumour resection and to evaluate the usefulness of the method.

PATIENTS AND METHODS

We retrospectively reviewed 49 patients who had undergone resection of a sarcoma and reconstruction using a VFG between 1988 and 2015. Their mean follow-up was 98 months (5 to 317). Reconstruction was with an osteochondral graft (n = 13), intercalary graft (n = 12), inlay graft (n = 4), or resection arthrodesis (n = 20). We analysed the oncological and functional outcome, and the rate of bony union and complications.

RESULTS

Five- and ten-year overall survival rates were 89% and 86%, respectively. Local recurrence occurred in two patients. Eight patients developed pulmonary metastases. Bone union was achieved in 44 patients (90%). Fracture occurred in six patients (12%), infection in three (6%), and nonunion in five (10%). The mean Musculoskeletal Tumor Society (MSTS) scores were as follows: osteochondral graft 70%; intercalary graft 73%; inlay graft 89%; and resection arthrodesis 83%.

CONCLUSION

Although associated with a relatively high rate of complications, each reconstruction method is useful, with a high rate of successful limb salvage and a good long-term functional outcome. Cite this article: Bone Joint J 2017;99-B:1237-43.

Computer navigation and distal femoral reconstruction in the oncologic patient

OBJECTIVES

As adjuvant treatments for musculoskeletal malignancies improve expectations of preserved function increase. We questioned whether computer navigation for distal femoral reconstruction would improve outcomes.

METHODS

Twenty oncology patients were reviewed after distal femoral reconstruction using navigation. Outcomes included local recurrence, implant revision, patient function, patellofemoral complications and leg-length inequality.

RESULTS

Implant survivorship was 85% at 26 months. There were no local recurrences and 3 failures for aseptic loosening. Good functional outcomes were observed in remaining cases.

CONCLUSION

Computer navigation for distal femoral reconstruction resulted in acceptable functional outcomes and implant survivorship. Reduced local recurrence were observed at intermediate follow-up. Level of Evidence: Level IV.

Leishmania Infection of a Knee Megaprosthesis

This article presents a 19-year old patient with a distal femoral osteosarcoma treated with limb salvage and distal femoral megaprosthetic reconstruction complicated postoperatively by bone leishmaniasis. Bone biopsy was done; bone tissue was sent for cultures and histology. Cultures were negative. Histological sections showed Leishman - Donovan bodies within histiocytes confirming the diagnosis of leishmania infection of the distal femoral megaprosthesis. The patient was administered amphotericin B for a total of 10 days and gradually became afebrile. Two months after treatment the patient was readmitted with high fever, pancytopenia, liver and spleen enlargement, and chest pain. Radiographs of the chest showed lobar pneumonia and pleural effusion; thoracentesis showed Mycobacterium avium intracellulare lung infection. Despite multi-regimen antibiotic therapy and chemotherapy, disease progressed and the patient died 19 months after osteosarcoma resection and distal femoral megaprosthetic reconstruction from cancer-related complications.

Prognostic significance of chemotherapy-induced necrosis in osteosarcoma patients receiving pasteurized autografts

Background

Among various reconstruction methods after wide excision for osteosarcoma, pasteurized autograft is often preferred. While the whole area of the tumor can be assessed for chemotherapy-induced necrosis, one of the important prognostic factors, in other reconstructive techniques, only a portion removed from a wide-resection specimen is available when using pasteurized autograft method. The assessment, therefore, may be unreliable. We analyzed the prognostic significance of the chemotherapy-induced necrosis in osteosarcoma patients who underwent reconstruction with pasteurized autografts.

Patients and methods

We reviewed the records of osteosarcoma patients who underwent treatment in our institution from 1998 to 2013. Cases of reconstruction with pasteurized autografts were defined as the patient group, and the same number of patients who underwent other reconstruction methods served as controls. Chemotherapy-induced necrosis was evaluated for removed extra-osseous and curetted intramedullary tumor tissues.

Results

A total of 22 patients were identified; the median age was 15.5 years, and there were 12 males. The most common tumor location was the distal femur. The most common histological subtype was osteoblastic. Median size was 8.1 cm. Disease status was stage IIB in 13 patients and IIA in 9. Median follow-up was 76 months. No differences between the patient and control groups were observed in potential prognostic factors, overall survival, metastasis-free survival, or recurrence-free survival. Univariate analyses demonstrated that histological response was a significant prognostic factor for metastasis-free survival and also significant for recurrence-free survival.

Conclusion

Chemotherapy-induced necrosis grading, using only available tumor tissues, could be a prognostic factor for osteosarcoma patients receiving pasteurized autografts for reconstructive surgery.

Cost-utility of osteoarticular allograft versus endoprosthetic reconstruction for primary bone sarcoma of the knee: A markov analysis

BACKGROUND

The most cost-effective reconstruction after resection of bone sarcoma is unknown. The goal of this study was to compare the cost effectiveness of osteoarticular allograft to endoprosthetic reconstruction of the proximal tibia or distal femur.

METHODS

A Markov model was used. Revision and complication rates were taken from existing studies. Costs were based on Medicare reimbursement rates and implant prices. Health-state utilities were derived from the Health Utilities Index 3 survey with additional assumptions. Incremental cost-effectiveness ratios (ICER) were used with less than $100 000 per quality-adjusted life year (QALY) considered cost-effective. Sensitivity analyses were performed for comparison over a range of costs, utilities, complication rates, and revisions rates.

RESULTS

Osteoarticular allografts, and a 30% price-discounted endoprosthesis were cost-effective with ICERs of $92.59 and $6 114.77. One-way sensitivity analysis revealed discounted endoprostheses were favored if allografts cost over $21 900 or endoprostheses cost less than $51 900. Allograft reconstruction was favored over discounted endoprosthetic reconstruction if the allograft complication rate was less than 1.3%. Allografts were more cost-effective than full-price endoprostheses.

CONCLUSIONS

Osteoarticular allografts and price-discounted endoprosthetic reconstructions are cost-effective. Sensitivity analysis, using plausible complication and revision rates, favored the use of discounted endoprostheses over allografts. Allografts are more cost-effective than full-price endoprostheses.

Functional assessment of endoprosthesis in the treatment of bone tumors

OBJECTIVES

Evaluate the functional grade of these patients and to identify the types of complications found that influenced the average life span of endoprostheses the functions of the operated limb.

METHODS

We analyzed 14 post-operative cases of endoprosthesis, patients with malignant bone tumors and aggressive benign bone tumors submitted to surgery between 2004 and 2014. The evaluation system used was proposed by Enneking, recommended by the Musculoskeletal Tumor Society (MSTS), in addition to the radiologic evaluation.

RESULTS

Endoprosthesis are excellent choices for the treatment of bone tumors with limb preservation in relation to pain, strength, and patient's emotional acceptance. Another factor for good results is the immediate weight-bearing capacity, generating a greater independence.

CONCLUSION

The authors conclude that all patients classified the therapy as excellent/good, regardless of the type of prosthesis used, extent of injury, and/or type of tumor resection performed.

Knee salvage in revision arthroplasty after massive bone loss of the femur condyles (≥Engh III) with a single-modular-hinged knee revision implant

PURPOSE

Massive bone loss of the femur condyles in revision arthroplasty often requires modular-hinged revision implants to restore a stable joint situation. In the present series, the outcome after knee revision surgery using a single modular-hinged revision implant in patients with severe bone defects (>Engh III) is investigated.

METHODS

Sixty patients with severe bone defects (≥Engh III) after failed primary and revision knee arthroplasty were included. Medium follow-up was 47 (range 10-84) months after knee revision surgery. Medium patient age was 70 (range 33-87) years at the time of surgery. An average of 2.3 prior knee operations per patient was performed. 70 % of the patients required the knee revision implant after two-stage revision because of a deep implant infection.

RESULTS

Estimated 5 year extremity survival was 95 and 65 % implant survival. Reasons for implant revision in decreasing order were reinfection (30 %), aseptic loosening (13 %), and periprosthetic fracture (9.8 %). The average active range of motion in the knee joint was 88° (range 40°-115°) for flexion. An extension deficit of a mean of -6° was (range -50-5° hyper-extension) observed. Patient age influenced the functional results significantly in terms of reduced walking distances and decreased modified WOMAC score.

CONCLUSION

In consideration of this complex study, population acceptable functional results can be achieved using a modular knee revision endoprosthesis. In younger patients (<60 years), satisfying results in terms of walking ability and overall satisfactory can be expected. The outcome in older multimorbid patients is worse. Yet, operation in these patients can be feasible to restore enough mobility for daily household activities.

Is unicondylar osteoarticular allograft still a viable option for reconstructions around the knee?

BACKGROUND

Unicondylar osteoarticular allografts (UOAs) represent a possible technique for reconstructing massive bone defects around the knee when only one condyle is affected. The aim of this retrospective study is to evaluate the outcome of UOAs and describe the possible salvage procedures in case of graft failure.

METHODS

Twenty-five deep-frozen UOAs were implanted at Rizzoli Orthopedic Institute (Bologna, Italy). Twenty-two followed bone tumor resection, two cases were post-traumatic defects and one case followed UOA failure. Mean age at surgery was 33years (range: 15 to 63). Eighteen UOAs were in distal femur, seven in proximal tibia.

RESULTS

Three patients died (only one because of the tumor). One UOA was removed for chondrosarcoma relapse and one for allograft fracture. Mean overall survival with UOA failure as a primary endpoint was 129months (range 12 to 302), with differences in the femur (85%) and in the tibia (40%) at 150months. Six UOAs had to be converted into knee prostheses due to osteoarthritis after a mean follow-up of 146months. No complications were recorded in UOAs converted into knee prostheses after a mean three year follow-up. Fourteen patients with UOAs still in place at the last follow-up (mean 123months) were radiologically and functionally evaluated: no correlation was found between function and the degree of osteoarthritis.

CONCLUSIONS

In selected cases, UOAs offer good clinical results and postpone the need for knee prosthesis. Despite short-term encouraging results, longer-term follow-up is needed in order to evaluate the outcome of knee prosthesis after UOA.

How Often Does Spindle Failure Occur in Compressive Osseointegration Endoprostheses for Oncologic Reconstruction?

BACKGROUND

Compressive osseointegration is a promising modality for limb salvage in distal femoral oncologic tumors. However, few studies have explored short-term survival rates in a large patient cohort of distal femur compressive endoprostheses or highlighted the risk factors for spindle failures.

QUESTIONS/PURPOSES

We asked: (1) What is the frequency of compressive osseointegration spindle failure in distal femoral reconstructions? (2) What are the characteristics of rotational failure cases with distal femur compressive osseointegration endoprostheses? (3) What are the risk factors for mechanical and rotational failure of distal femur compressive osseointegration implantation? (4) What are other modalities of failure or causes of revision surgery, which affect patients undergoing distal femur compressive osseointegration implantation for oncologic reconstruction?

METHODS

Between 1996 and 2013, 127 distal femoral reconstructions with the Compress(®) prosthesis were performed in 121 patients. During that time, 116 Compress(®) prostheses were implanted for aggressive primary tumors of the distal femur and/or failure of previous oncologic reconstruction. This approach represented approximately 91% of the distal femoral reconstructions performed during that time. Of the patients with prostheses implanted, four patients (four of 116, 3%) had died, and 37 (37 of 116, 32%) were lost to followup before 24 months. The median followup was 84 months (range, 24-198 months), and 71 patients (66% of all patients) were seen within the last 3 years. A retrospective chart review was performed to determine failure modality as defined by radiographs, clinical history, and intraoperative findings. Risk factors including age, sex, BMI, resection length, and perioperative chemotherapy were analyzed to determine effect on spindle and rotational failure rates. Survival analysis was determined using the Kaplan-Meier estimator. Differences in survival between groups were analyzed using the log rank test. Risk factors were determined using Cox proportional hazard modeling.

RESULTS

Spindle survival at 5 and 10 years was 91% (95% CI, 82%-95%). Survival rates from rotational failure at 5 and 10 years were 92% (95% CI, 83%-96%); the majority of failures occurred within the first 2 years postoperatively and were the result of a twisting mechanism of injury. With the numbers available, none of the potential risk factors examined were associated with mechanical failure. The 5-year and 10-year all-cause revision-free survival rates were 57% (95% CI, 44%-67%) and 50% (95% CI, 36%-61%), respectively.

CONCLUSIONS

Distal femur compressive osseointegration is a viable method for endoprosthetic reconstruction. Rotational failure is rare with the majority occurring early. No variables were found to correlate with increased risk of mechanical failure. More research is needed to evaluate methods of preventing mechanical and rotational failures in addition to other common causes of revision such as infection in these massive endoprosthetic reconstructions.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Revision Distal Femoral Arthroplasty With the Compress(®) Prosthesis Has a Low Rate of Mechanical Failure at 10 Years

BACKGROUND

Patients with failed distal femoral megaprostheses often have bone loss that limits reconstructive options and contributes to the high failure rate of revision surgery. The Compress(®) Compliant Pre-stress (CPS) implant can reconstruct the femur even when there is little remaining bone. It differs from traditional stemmed prostheses because it requires only 4 to 8 cm of residual bone for fixation. Given the poor long-term results of stemmed revision constructs, we sought to determine the failure rate and functional outcomes of the CPS implant in revision surgery.

QUESTIONS/PURPOSES

(1) What is the cumulative incidence of mechanical and other types of implant failure when used to revise failed distal femoral arthroplasties placed after oncologic resection? (2) What complications are characteristic of this prosthesis? (3) What function do patients achieve after receiving this prosthesis?

METHODS

We retrospectively reviewed 27 patients who experienced failure of a distal femoral prosthesis and were revised to a CPS implant from April 2000 to February 2013. Indications for use included a minimum 2.5 mm cortical thickness of the remaining proximal femur, no prior radiation, life expectancy > 10 years, and compliance with protected weightbearing for 3 months. The cumulative incidence of failure was calculated for both mechanical (loss of compression between the implant anchor plug and spindle) and other failure modes using a competing risk analysis. Failure was defined as removal of the CPS implant. Followup was a minimum of 2 years or until implant removal. Median followup for patients with successful revision arthroplasty was 90 months (range, 24-181 months). Functional outcomes were measured with the Musculoskeletal Tumor Society (MSTS) functional assessment score.

RESULTS

The cumulative incidence of mechanical failure was 11% (95% confidence interval [CI], 4%-33%) at both 5 and 10 years. These failures occurred early at a median of 5 months. The cumulative incidence of other failures was 18% (95% CI, 7%-45%) at 5 and 10 years, all of which were deep infection. Three patients required secondary operations for cortical insufficiency proximal to the anchor plug in bone not spanned by the CPS implant and unrelated to the prosthesis. Median MSTS score was 27 (range, 24-30).

CONCLUSIONS

Revision distal femoral replacement arthroplasty after a failed megaprosthesis is often difficult as a result of a lack of adequate bone. Reconstruction with the CPS implant has an 11% failure rate at 10 years. Our results are promising and demonstrate the durable fixation provided by the CPS implant. Further studies to compare the CPS prosthesis and other reconstruction options with respect to survival and functional outcomes are warranted.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Comparison of gait parameters in distal femoral replacement using a metallic endoprosthesis versus allograft reconstruction

BACKGROUND/AIM

Restoration of gait mechanics after reconstruction have been associated with improved functional outcomes and increased longevity of the reconstruction. The goal of this study is to compare the gait mechanics of an allograft reconstruction of the distal femur to both metallic endoprosthetic reconstruction relative to normal control subjects.

METHODS

Gait parameters were captured using motion capture system, and then analyzed and compared for patients with metallic endoprosthetic reconstructions, and patients with allograft reconstructions of the distal femur following resection of malignant bone tumor, with subjects having no history of musculoskeletal disorders serving as a control group.

RESULTS

All reconstructed distal femurs following tumor resection resulted in decreased range of motion reflected in observed flexion/extension angles compared to the normal limbs. The allograft reconstructed knees demonstrated normal patterns of rotation whereas the metal subjects had abnormal patterns of rotation and statistically significant differences in rotational moments.

CONCLUSION

Allograft distal femoral reconstruction after malignant excision remains a viable option for surgeons faced with problems associated with iatrogenic muscle, bone and soft tissue defects.

Megaprostheses in the management of trauma of the knee

OBJECTIVE

Review the outcome of patients with complex fractures around the knee treated with megaprosthesis.

METHOD

Retrospective observational study of 10 patients was undertaken.

RESULTS

Six patients were treated with a distal femoral endoprosthesis (DEFPR) and four with an augmented rotating hinge knee replacement (RHK). The mean post-operative Toronto Extremity Salvage Score (TESS) was 62.5 for the whole cohort (RHK group 79.3, compared with 49.2 in the DFEPR group (p = 0.038), peri-prosthetic fracture group was 46.3, compared with 75.6 in native knee fracture group (p = 0.04)).

CONCLUSION

A megaprosthesis is a viable option in complex fractures around the knee.

A NEW APPROACH TO PARTIALKNEE ENDOPROSTHESIS IN PRIMARY BONE SARCOMAS

Partial knee endoprosthesis to bone sarcomas resections seems to be a good solution to treat this immature skeletal patients. The purpose of this study is to evaluate the functional score in fourteen patients, advantages and the technique indications. Methods: Retrospective analysis was done to assess in this group of patients the functional evolution and the possible complications of the procedure. 14 patients between 10 and 22 years functionally evaluated in Ennekin/ISOLS (International Society of Limb Salvage) criteria, being all of them operated in the same institution by the same surgeon. Were used distal femur and proximal tibia partial endoprosthesis. Results: General analysis demonstrated that the functional results were over than 67 percent (ISOLS criteria) in 78,6 percent of the patients, being considered excellent. 21,4 percent were considered good results, being between 50 and 66 percent. Bone storage was preserved when avoiding the adjacent segment resection. Surgery time was not prolonged in ligament reconstruction. Conclusion: Knee partial endoprosthesis are less damage to bone storage in young patients. The critics about the bad functional results are being supplied by new surgical techniques, excellent rehabilitation protocols, implants technology and the consequent learning curve. This option of treatment permits the preservation of healthy bone and provides the possibility of a revision replacement less aggressive.

Distraction osteogenesis and arthrodesis as a new surgical option for chondrosarcoma in the distal tibia

Recent advances in the management of bone tumors have led to a significant increase in the survival rates of patients with malignant bone tumors. Thus, limb salvage surgery has gained importance for preserving limb function in the management of bone tumors. However, surgery presents unique difficulties in terms of the biomechanics and obtaining a soft-tissue cover, such as when the ankle is involved in the primary malignant bone tumor. We report a case of chondrosarcoma of the distal tibia treated with wide en bloc resection arthrodesis and reconstruction of the defect using distraction osteogenesis, which offers an effective alternative protocol for limb salvage. The patient has remained disease free for 3 years since the initial surgery and can maintain normal limb athletic function.

Osteogenic Matrix Cell Sheets Facilitate Osteogenesis in Irradiated Rat Bone

Reconstruction of large bone defects after resection of malignant musculoskeletal tumors is a significant challenge in orthopedic surgery. Extracorporeal autogenous irradiated bone grafting is a treatment option for bone reconstruction. However, nonunion often occurs because the osteogenic capacity is lost by irradiation. In the present study, we established an autogenous irradiated bone graft model in the rat femur to assess whether osteogenic matrix cell sheets improve osteogenesis of the irradiated bone. Osteogenic matrix cell sheets were prepared from bone marrow-derived stromal cells and co-transplanted with irradiated bone. X-ray images at 4 weeks after transplantation showed bridging callus formation around the irradiated bone. Micro-computed tomography images at 12 weeks postoperatively showed abundant callus formation in the whole circumference of the irradiated bone. Histology showed bone union between the irradiated bone and host femur. Mechanical testing showed that the failure force at the irradiated bone site was significantly higher than in the control group. Our study indicates that osteogenic matrix cell sheet transplantation might be a powerful method to facilitate osteogenesis in irradiated bones, which may become a treatment option for reconstruction of bone defects after resection of malignant musculoskeletal tumors.

Effect of simulated early weight bearing on micromotion and pullout strength of uncemented distal femoral stems

The effect of simulated early weight bearing on both micromotion and pullout strength of uncemented distal femoral stems was evaluated in this study. The effect of stem endosteal contact and bone quality on implant pullout strength was also analyzed. A randomized matched-pair study was performed using 8 bilateral pairs of fresh human cadaveric femoral specimens. Each specimen pair was dual-energy x-ray absorptiometry scanned, uniformly implanted, fluoroscopically imaged, and randomly assigned to the cycled or uncycled group. The cycled group received 5000 cycles of axial compressive loading (to 700 N) and the contralateral side was not cycled. Micromotion was monitored during cycling and compared with a failure threshold (150 µm), and all implants underwent direct axial distraction (pullout) testing. During cycling, minimal micromotion was observed with an asymptotic decrease in differential motion between the first and last 50 cycles. Both cycled and uncycled groups demonstrated no statistical difference in average pullout force (4888±2124 N vs 4367±1154 N; P=.43). The percentage of cortical contact for each implant was determined from panoramic fluoroscopy images using digital image analysis software. Contact area for the distal third of the stem showed the highest correlation with pullout force and with predicting pullout force. Bone quality did not correlate with pullout force (r(2)=0.367) or stem contact area (r(2)=0.394). In sum, press-fit uncemented femoral stems did not loosen or demonstrate decreased pullout strength with early weight bearing simulated by cyclical axial compressive loading.

Reconstruction with modular megaprostheses for sarcomas of the lower extremity

Limb-preserving surgery using modular megaprostheses for the reconstruction of large skeletal defects is currently the preferred treatment for sarcomas. The authors report the postoperative outcomes after skeletal resection for lower extremity sarcomas and the use of the METS cemented modular implant system (Stanmore Implants, Hertfordshire, United Kingdom) for reconstruction. They retrospectively studied 52 consecutive patients operated on from 2003 to 2012. There were 27 distal femur prostheses, 13 proximal femur, 11 proximal tibia, and 1 total femur implants. Patients were followed for a mean of 4.3 years. Overall patient survival, prosthesis survival, limb salvage rate, and secondary complications were documented. Five years postoperatively, prosthesis survival was 79%. Complications warranting implant revision surgery were documented in 15% of patients, whereas complications warranting surgery of any kind were observed in 27% of the patients. Nonmechanical complications, namely local relapse of the tumor and prosthetic infection, were the most common cause of prosthetic failure, accounting for 88% of major revision surgeries and 100% of amputations. Mechanical complications were rare, observed in only 6% of patients. No patients required secondary revision surgery. The limb salvage rate was 89%. Overall patient survival was 79% at 5 years and 71% at 10 years. The low risk for mechanical complications and the high limb salvage rate support the use of the METS modular megaprostheses for the reconstruction of skeletal defects following lower limb sarcoma surgery.

View-Angle Tilting and Slice-Encoding Metal Artifact Correction for Artifact Reduction in MRI: Experimental Sequence Optimization for Orthopaedic Tumor Endoprostheses and Clinical Application

BACKGROUND

MRI plays a major role in follow-up of patients with malignant bone tumors. However, after limb salvage surgery, orthopaedic tumor endoprostheses might cause significant metal-induced susceptibility artifacts.

PURPOSES

To evaluate the benefit of view-angle tilting (VAT) and slice-encoding metal artifact correction (SEMAC) for MRI of large-sized orthopaedic tumor endoprostheses in an experimental model and to demonstrate clinical benefits for assessment of periprosthetic soft tissue abnormalities.

METHODS

In an experimental setting, tumor endoprostheses (n=4) were scanned at 1.5T with three versions of optimized high-bandwidth turbo-spin-echo pulse sequences: (i) standard, (ii) VAT and (iii) combined VAT and SEMAC (VAT&SEMAC). Pulse sequences included coronal short-tau-inversion-recovery (STIR), coronal T1-weighted (w), transverse T1-w and T2-w TSE sequences. For clinical evaluation, VAT&SEMAC was compared to conventional metal artifact-reducing MR sequences (conventional MR) in n=25 patients with metal implants and clinical suspicion of tumor recurrence or infection. Diameters of artifacts were measured quantitatively. Qualitative parameters were assessed on a five-point scale (1=best, 5=worst): "image distortion", "artificial signal changes at the edges" and "diagnostic confidence". Imaging findings were correlated with pathology. T-tests and Wilcoxon-signed rank tests were used for statistical analyses.

RESULTS

The true size of the prostheses was overestimated on MRI (P<0.05). A significant reduction of artifacts was achieved by VAT (P<0.001) and VAT&SEMAC (P=0.003) compared to the standard group. Quantitative scores improved in the VAT and VAT&SEMAC group (P<0.05). On clinical MR images, artifact diameters were significantly reduced in the VAT&SEMAC-group as compared with the conventional-group (P<0.001). Distortion and artificial signal changes were reduced and diagnostic confidence improved (P<0.05). In two cases, tumor-recurrence, in ten cases infection and in thirteen cases other pathologies were diagnosed.

CONCLUSIONS

Significant reduction of metallic artifacts was achieved by VAT and SEMAC. Clinical results suggest, that these new techniques will be beneficial for detecting periprosthetic pathologies during postoperative follow-up.

Which is the best method of sterilization for recycled bone autograft in limb salvage surgery: a radiological, biomechanical and histopathological study in rabbit

Background

Limb salvage surgery is a treatment of choice for sarcomas of the extremities. One of the options in skeletal reconstruction after tumour resection is by using a recycled bone autograft. The present accepted methods of recycling bone autografts include autoclaving, pasteurization and irradiation. At the moment there is lack of studies that compare the effectiveness of various sterilization methods used for recycling bone autografts and their effects in terms of bone incorporation. This study was performed to determine the effects of different methods of sterilization on bone autografts in rabbit by radiological, biomechanical and histopathological evaluations.

Methods

Fresh rabbit cortical bone is harvested from the tibial diaphysis and sterilized extracorporeally by pasteurization (n = 6), autoclaving (n = 6), irradiation (n = 6) and normal saline as control group (n = 6). The cortical bones were immediately reimplanted after the sterilization process. The subsequent process of graft incorporation was examined over a period of 12 weeks by serial radiographs, biomechanical and histopathological evaluations. Statistical analysis (ANOVA) was performed on these results. Significance level (α) and power (β) were set to 0.05 and 0.90, respectively.

Results

Radiographic analysis showed that irradiation group has higher score in bony union compared to other sterilization groups (p = 0.041). ANOVA analysis of ‘failure stress’, ‘modulus’ and ‘strain to failure’ demonstrated no significant differences (p = 0.389) between treated and untreated specimens under mechanical loading. In macroscopic histopathological analysis, the irradiated group has the highest percentage of bony union (91.7 percent). However in microscopic analysis of union, the pasteurization group has significantly higher score (p = 0.041) in callus formation, osteocytes percentage and bone marrow cellularity at the end of the study indicating good union potential.

Conclusions

This experimental study shown that both irradiation and pasteurization techniques have more favourable outcome in terms of bony union based on radiographic and histopathological evaluations. Autoclaving has the worst outcome. These results indicate that extracorporeal irradiation or pasteurization of bone autografts, are viable option for recycling bone autografts. However, pasteurization has the best overall outcomes because of its osteocytes preservation and bone marrow cellularity.

Bone-prosthesis composite with rotating hinged-knee prosthesis in limb salvage surgery for high-grade sarcoma around the knee

Bone prosthesis composite (BPC) had been widely-used in reconstruction after wide excision of malignant tumors around the knee. However, implant selection for BPC remains a dilemma. Forty-one patients with high-grade malignant bone tumors around the knee who underwent excision and reconstruction with BPC and rotating hinged knee (RHK) prosthesis were included. The mean follow-up time was 54 months (range, 31-78 months). The average Musculoskeletal Tumor Society Rating score was 93.4% (range, 73-100%). The mean range of motion was 125°. Complications included 2 local recurrences, 2 nonunions, and 1 peri-prosthetic fracture. The reconstruction with BPC using the RHK prosthesis provided consistently good functional results with a low complication rate. The RHK prosthesis is a promising choice for BPC reconstruction.

Antirotation pins improve stability of the compress limb salvage implant: a biomechanical study

BACKGROUND

Limb salvage implants that rely on compliant compression osseointegration to achieve bone fixation may achieve longer survivorship rates compared with traditional cemented or press-fit stemmed implants; however, failures resulting from rotational instability have been reported. The effect of using antirotation pins on the rotational stability of the fixation has not been well studied.

QUESTIONS/PURPOSES

We asked the following question: When tested in a cadaver model, does the use of antirotation pins increase the torque required to cause implant failure or rotation?

METHODS

Thirty-two cadaver femurs were divided into four groups of eight femurs. We compared the torque to failure among groups containing zero, one, two, three, and four pins using a servohydraulic testing device.

RESULTS

Adding antirotation pins increased the torque required to cause failure (R(2) = 0.77; p < 0.001). This increase was most notable in groups comparing zero pins with one pin (14 N-m, [95% CI, 10.9-17.1] versus 23 N-m, [95% CI 22.5-23.48]; p = 0.01) and two compared with three pins (29 N-m, [95% CI, 21.7-36.3] versus 42 N-m, [95% CI, 37.8-46.2]; p = 0.35).

CONCLUSIONS

It appears that the use of antirotation pins improves rotational stability of the compliant compression endoprosthesis. Although these findings need to be verified in a clinical study, the addition of antirotation pins may improve osteointegration and we have changed our practice to use a minimum of three antirotation pins when implanting this device.

CLINICAL RELEVANCE

Improvements in implant technology and surgical techniques may lead to improved clinical outcomes and patient quality of life. Addition of antirotation pins appears to improve implant stability and may decrease the need for revision surgery.