A dual-center review of compressive osseointegration for fixation of massive endoprosthetics: 2- to 9-year followup

Uncemented Customized Hollow Stems in Tumor Endoprosthetic Replacement-A Good Opportunity to Protect the Adjacent Joint in Children?

This study aimed to retrospectively analyze the follow-up results of cases in which the adjacent joint was preserved using a custom-made uncemented short-stem design (hollow stem) with optional external flanches in tumor endoprosthetic replacement due to bone sarcomas in 13 patients (with an average age of 9.6 years) between 2017 and 2023. Reconstructions were proximal femur (n = 6), intercalary femur (n = 4), intercalary tibia (n = 2), and proximal humerus (n = 1) tumor prostheses. The hollow body was used distally in 10 of the megaprotheses, proximally in 1, and both proximally and distally in 2 of them. The average distance from the joints was 6 cm in stems with flanches and 11.8 cm in stems without flanches. No aseptic loosening or deep infection was observed during an average follow-up of 34 months. Except for one case with a tibial intercalary prosthesis that needed a revision, all cases were well osteointegrated and all lower extremity cases could bear full weight without pain. In cases where the remaining bone stock after bone resection is insufficient for a standard stem implantation, reconstruction with a patient-specific short hollow-stem design appears to be a good alternative to protect healthy joints with high prosthesis survival and low revision rates in the short-term follow-up.

The survival and complication profiles of the Compress® Endoprosthesis: A systematic review and meta-analysis

Background/purpose

This study aimed to summarize the survival and complication profiles of the compress® endoprosthesis (CPS) through a systematic review and meta-analysis.

Methods

Online databases (PubMed, EMBASE and Web of Science) were searched from inception to November 2023. Trials were included that involved the use of CPS for endoprosthetic replacement in patients with massive segmental bone defects. Patients' clinical characteristics and demographic data were extracted using a standardized form. The methodological quality of included 13 non-comparative studies was assessed on basis of the Methodological Index for Non-Randomized Studies (MINORS). All the available Kaplan-Meier curves in the included studies were digitized and combined using Engauge-Digitizer software and the R Project for Statistical Computing.

Results

The meta-analysis of thirteen included studies indicated: the all-cause failure rates of CPS were 26.3 % after surgery, in which the occurrence rates of aseptic loosening were 5.8 %. And the incidences of other complications were as follows: soft tissue failure (1.8 %), structure failure (8.2 %), infection (9.5 %), tumor progression (1.1 %). The 1-, 4-, and 8-year overall survival rates for all-cause failure with 95 % CI were 89 % (86 %-92 %), 75 % (71 %-79 %) and 65 % (60 %-70 %), respectively. The estimated mean survival time of all-cause failure was 145 months (95 % CI, 127-148 months), and the estimated median survival time of all-cause failure was 187 months (95 % CI, 135-198 months). The 1-, 4-, and 8-year overall survival rates of aseptic loosening with 95 % CI were 96 % (94 %-98 %), 91 % (87 %-95 %) and 88 % (83 %-93 %), respectively. The estimated mean survival time of aseptic loosening was 148 months (95 % CI, 137-153 months).

Conclusion

CPS's innovative spring system promotes bone ingrowth by providing immediate and high-compression fixation, thereby reducing the risk of aseptic loosening caused by stress shielding and particle-induced osteolysis. CPS requires less residual bone mass for reconstructing massive segmental bone defects and facilitates easier revision due to its non-cemented fixation. In addition, the survival rate, estimated mean survival time, and complication rates of CPS are not inferior to those of common endoprosthesis.

3D-printed modular prostheses for reconstruction of intercalary bone defects after joint-sparing limb salvage surgery for femoral diaphyseal tumours

Aims

The aim of this study was to investigate the safety and efficacy of 3D-printed modular prostheses in patients who underwent joint-sparing limb salvage surgery (JSLSS) for malignant femoral diaphyseal bone tumours.

Methods

We retrospectively reviewed 17 patients (13 males and four females) with femoral diaphyseal tumours who underwent JSLSS in our hospital.

Results

In all, 17 patients with locally aggressive bone tumours (Enneking stage IIB) located in the femoral shaft underwent JSLSS and reconstruction with 3D-printed modular prostheses between January 2020 and June 2022. The median surgical time was 153 minutes (interquartile range (IQR) 117 to 248), and the median estimated blood loss was 200ml (IQR 125 to 400). Osteosarcoma was the most common pathological type (n = 12; 70.6%). The mean osteotomy length was 197.53 mm (SD 12.34), and the median follow-up was 25 months (IQR 19 to 38). Two patients experienced local recurrence and three developed distant metastases. Postoperative complications included wound infection in one patient and screw loosening in another, both of which were treated successfully with revision surgery. The median Musculoskeletal Tumor Society score at the final follow-up was 28 (IQR 27 to 28).

Conclusion

The 3D-printed modular prosthesis is a reliable and feasible reconstruction option for patients with malignant femoral diaphyseal tumours. It helps to improve the limb salvage rate, restore limb function, and achieve better short-term effectiveness.

Intercalary Prosthetic Reconstruction with Three-Dimensional-Printed Custom-Made Porous Component for Defects of Long Bones with Short Residual Bone Segments After Tumor Resection

BACKGROUND

Intercalary reconstruction for patients with short residual bone segments remains challenging. Three-dimensional (3D)-printed custom-made porous implants are a promising technique for short-segment fixation in these patients. This study aims to evaluate the efficiency of 3D-printed custom-made porous components (3DCPCs) for short-segment fixation, focusing on prosthesis survivorship, radiographic results, and potential complications.

METHODS

This retrospective study involved 39 patients who underwent intercalary prosthetic reconstruction with 3DCPCs after tumor resection of the femur, tibia, or humerus from June 2015 to October 2020. Segment bone loss involved the femur (n = 15), tibia (n = 16), and humerus (n = 8), leaving 78 residual bone segments. There were 46 short segments requiring 46 3DCPCs and 32 segments with the ability to accommodate 32 off-the-shelf standard uncemented stems for prosthesis fixation. Clinical and functional outcomes were evaluated. Prosthesis-overall survivorship and prosthesis-specific survivorship were analyzed using Kaplan-Meier survival analysis. Radiographic results and modes of failure of using this technique were also examined.

RESULTS

The mean follow-up was 41 months. The prosthesis-overall survivorship was 87.2% and 84.6% at 2 and 5 years, respectively. The prosthesis-specific survivorship was 92.1% and 89.5% at 2 and 5 years, respectively. There was not a substantial difference in prosthesis survivorship among the femur, tibia, and humerus. The average MSTS score was 26.2, ranging from 22 to 28. The radiographic evaluation results revealed excellent or good interface (38/46) in most of the 46 porous components. A total of 38 of 46 bone segments' remolding demonstrated no change. In total, seven patients (16.3%) had complications requiring further surgery.

CONCLUSION

The prosthesis survivorship of using 3DCPCs for short-segment fixation is similar or better compared to other studies involving intercalary prosthetic reconstruction with short-segment fixation. Radiographic evaluation revealed good osteointegration and avoidance of stress shielding. Overall, intercalary prosthetic reconstruction with 3DCPC is a feasible modality for patients with short residual bone segments after tumor resection.

Durability of intercalary endoprosthesis for humeral reconstruction

INTRODUCTION

The humerus is a common site of metastases and primary tumors. For some patients with a segmental defect and/or diaphyseal cortical destruction a cemented intercalary device may provide a more reliable construct, however data on their use is limited.

METHODS

We reviewed 43 (28 male and 15 female) patients treated with an intercalary humeral spacer at a single tertiary referral center between 1989 and 2022. Humeral lesions were most commonly secondary to metastatic disease (n = 29, 68%), with 25 (58%) patients presenting with a pathologic fracture. Mean age and body mass index were 66 years and 27.9 kg/m2 . First generation taper joint device were used in 22 patients and second-generation lap device in 21 patients.

RESULTS

Following reconstruction the 2-year overall survival was 30%. Mechanical complications occurred in 11 patients, most commonly aseptic loosening (n = 6, 14%). With death as a competing risk, the cumulative incidence of mechanical failure was 28% at 2-years postoperative. Following the procedure, mean Musculoskeletal Tumor Society scores was 70% and mean shoulder elevation was 87°.

CONCLUSION

Reconstruction of the humeral diaphysis with an intercalary endoprosthesis provides restoration of function of the upper extremity, however, is associated with one in four patients having mechanical failure.

3D-printed custom-made short stem with porous structure for fixation of massive endoprosthesis in joint-preserving reconstruction after tumor resection

BACKGROUND

Large malignant bone tumors and revision limb salvage procedures often result in massive bone loss, leaving a short residual bone segment that cannot accommodate a standard stem for endoprosthesis fixation. Three-dimensional-printed (3DP) short stem with porous structure seems to be an alternative for short-segment fixation. This retrospective study aims to evaluate surgical outcomes, radiographical results, limb functions, and complications of using 3DP porous short stems in massive endoprosthesis replacement.

METHODS

Between July 2018 to February 2021, 12 patients with massive bone loss undergoing reconstruction with custom-made, short-stemmed massive endoprostheses were identified. Endoprosthesis replacement involved the proximal femur (n = 4), distal femur (n = 1), proximal humerus (n = 4), distal humerus (n = 1), and proximal radius (n = 2).

RESULTS

The mean percentage of resected bone was 72.4% of the whole length of the bone, ranging from 58.4 to 88.5%. The mean length of 3DP porous short stems was 6.3 cm. The median follow-up was 38 months (range, 22-58 months). The mean MSTS score was 89%, ranging from 77% to 93%. Radiographical assessment results showed bone in-growth to the porous structure in 11 patients, and the implants were well osseointegrated. Breakage of the 3DP porous short stem occurred in one patient intraoperatively. The patient developed aseptic loosening (Type 2) four-month after surgery and underwent revision with a plate applied to assist fixation. The implant survivorship was 91.7% at 2 years. No other complications were detected, such as soft-tissue failures, structural failures, infection, or tumor progression.

CONCLUSIONS

3DP custom-made short stem with porous structure is a viable method for fixation of the massive endoprosthesis in the short segment after tumor resection, with satisfactory limb function, great endoprosthetic stability, and low complication rates.

Telescoping Allograft Prosthetic Composite (APC) Reconstruction of the Femur Following Revision Arthroplasty for Neglected Developmental Dysplasia of the Hip (DDH)

Although uncommon, neglected developmental dysplasia of the hip (DDH) poses a technically demanding problem for treating surgeons. Due to the congenital malformation of the native hip joint and distortion of the surrounding soft tissue, addressing limb-length discrepancy is intricate. Despite detailed planning and meticulous soft tissue handling, complications can be difficult to avoid in these patients even under experienced hands. In this case report, we present a 73-year-old lady with neglected DDH who had undergone initial total hip arthroplasty and subsequent revision surgery that failed due to aseptic loosening. Due to limited length in the distal femur, we used a telescoping allograft prosthetic composite (APC) to provide adequate length to the native distal femur during revision with proximal femur fixation. This technique can help avoid the need for total femur replacement (TFR) surgery, which is more invasive and may require tibia replacement.

Megaprosthetic reconstruction of the distal femur with a short residual proximal femur following bone tumor resection: a systematic review

BACKGROUND

To investigate the risk of postoperative function and complications associated with reconstruction methods in patients with short residual proximal femurs (< 12 cm) after resection of distal femoral bone tumors, we performed a systematic review of studies reporting postoperative function and complications in these patients.

METHODS

Of the 236 studies identified by systematic searches using the Medline, Embase, and Cochrane Central Register of Controlled Trials databases, eight were included (none were randomized controlled trials). In these studies, 106 (68.4%), 12 (7.7%), and 37 (23.9%) patients underwent reconstruction with custom-made megaprostheses with extracortical plates or cross-pins, allograft prosthetic composite (APC), and Compress^® compliant pre-stress (CPS) implants, respectively.

RESULTS

Aseptic loosening occurred slightly more frequently in the APC group than in the other reconstruction methods (APC group, 21%; custom-made megaprosthesis group, 0-17%; CPS implant group, 14%). No differences were noted in the frequencies of implant breakage, fractures, or infections between the three reconstruction methods. Mechanical survival, where endpoint was set as implant removal for any reason, was 80% at seven years in the APC group, 70-77% at 10 years in the custom-made megaprosthesis group, and 68% at nine years in the CPS implant group. Therefore, there appeared to be no difference among the three reconstruction methods with respect to mechanical survival.

CONCLUSIONS

During megaprosthetic reconstruction of the distal femur with a short residual proximal femur after bone tumor resection, similar results were obtained using custom-made megaprostheses, APCs, and CPS implants.

Classification and reconstruction of femoral bone defect in the revision of aseptic loosening of distal femoral endoprostheses: a 10-year multicenter retrospective analysis

Objective

This study proposes a system for classifying the aseptic loosening of distal femoral endoprostheses and discusses reconstruction methods for revision surgery, based on different classification types.

Methods

We retrospectively analyzed the data of patients who received revision surgery for aseptic loosening in distal femoral tumor endoprosthesis from January 2008 to December 2020 at 3 bone tumor treatment centers in China. Based on the patient imaging data, we proposed a classification system for the aseptic loosening of distal femoral endoprostheses and discussed its revision surgery strategy for various bone defects.

Results

A total of 31 patients were included in this study, including 21 males and 10 females aged 15–75 y (average: 44.3 y). First-revision surgery was performed on 24 patients, whereas second-revision surgery was conducted on 7 patients. The 31 patients were classified into different types based on the degree of aseptic loosening: Type I, 12 patients (38.7%); Type IIa, 7 patients (22.5%); Type IIb, 7 patients (22.5%); Type III, 4 patient (12.9%); and Type IV, 1 patient (3.2%). For type I, 11 patients underwent revisions with standard longer-stem prostheses (one with the original prosthesis), and one patient had the original prosthesis plus cortical allograft strut. For type II (a and b), 10 patients underwent revisions with original prosthesis or longer-stem prosthesis and 4 patients combined with cortical allograft strut. For type III, one patient underwent revision with a longer-stem prosthesis and the other 3 patients with a custom short-stem prosthesis. For type IV, only one patient underwent revision with a custom short-stem prosthesis.

Conclusions

Aseptic loosening of the distal femoral prosthesis can be divided into 4 types: type I, type II (a, b), type III and type IV. The reconstruction methods of our centers for different types of bone defects can offer some reference value in the revision of aseptic loosening.

Hip-preserving reconstruction using a customized cemented femoral endoprosthesis with a curved stem in patients with short proximal femur segments: Mid-term follow-up outcomes

Background

Short metaphyseal segments that remain following extensive distal femoral tumor resection can be challenging to manage, as the residual short segments may not be sufficient to accept an intramedullary cemented stem of standard length. The present study was developed to detail preliminary findings and experiences associated with an intra-neck curved stem (INCS) reconstructive approach, with a particular focus on mechanical stability.

Method

From March 2013 to August 2016, 11 total patients underwent reconstructive procedures using a customized cemented femoral endoprosthesis (CCFE) with an INCS. Measurements of femoral neck-shaft angle values were made before and after this procedure. Radiological outcomes associated with this treatment strategy over an average 63-month follow-up period were additionally assessed. Functionality was assessed based upon Musculoskeletal Tumor Society (MSTS) scores, while a visual analog scale (VAS) was used to rate pre- and postoperative pain, and any complications were noted.

Results

Relative to the preoperative design, no significant differences in femoral neck–shaft angle were observed after this reconstructive procedure (p = 0.410). Postoperatively, the tip of the stem was primarily positioned within the middle third of the femoral head in both lateral and posterior-anterior radiographic, supporting the accuracy of INCS positioning. The average MSTS score for these patients was 25 (range: 21–28), and VAS scores were significantly reduced after surgery (p &lt; 0.0001). One patient exhibited local disease recurrence and ultimately succumbed to lung metastases, while two patients exhibited aseptic loosening. None of the treated patients exhibited complications such as infections, periprosthetic fractures, or prosthetic fractures as of most recent follow-up.

Conclusion

CCFE with an INCS represents a viable approach to massive femoral diaphyseal defect with short proximal femur repair, as patients can achieve good functional outcomes and early weight-bearing with proper individualized rehabilitative interventions, all while exhibiting low rates of procedure-related complications.

Hip reconstruction using a customized intercalary prosthesis with the rhino horn-designed uncemented stem for ultrashort proximal femur segments following tumor resection: a combined biomechanical and clinical study

Background

Hip-preserved reconstruction for patients with ultrashort proximal femur segments following extensive femoral diaphyseal tumor resection is a formidable undertaking. A customized intercalary prosthesis with a rhino horn-designed uncemented stem was developed for the reconstruction of these extensive skeletal defects.

Methods

This study was designed to analyze and compare the differences in the biomechanical behavior between the normal femur and the femur with diaphyseal defects reconstructed by an intercalary prosthesis with different stems. The biomechanical behavior under physiological loading conditions is analyzed using the healthy femur as the reference. Five three-dimensional finite element models (healthy, customized intercalary prosthesis with four different stems implemented, respectively) were developed, together with a clinical follow-up of 12 patients who underwent intercalary femoral replacement.

Results

The biomechanical results showed that normal-like stress and displacement distribution patterns were observed in the remaining proximal femur segments after reconstructions with the rhino horn-designed uncemented stems, compared with the straight stem. Stem A showed better biomechanical performance, whereas the fixation system with Stem B was relatively unstable. The clinical results were consistent with the FEA results. After a mean follow-up period of 32.33 ± 9.12 months, osteointegration and satisfactory clinical outcomes were observed in all patients. Aseptic loosening (asymptomatic) occurred in one patient reconstructed by Stem B; there were no other postoperative complications in the remaining 11 patients.

Conclusion

The rhino horn-designed uncemented stem is outstanding in precise shape matching and osseointegration. This novel prosthesis design may be beneficial in decreasing the risk of mechanical failure and aseptic loosening, especially when Stem A is used. Therefore, the customized intercalary prosthesis with this rhino horn-designed uncemented stem might be a reasonable alternative for the reconstruction of SSPF following extensive tumor resection.

A comparison of cemented and cementless intra-neck curved stem use during hip-preserving reconstruction following massive femoral malignant tumor removal

Background

Patients who undergo massive femoral malignant tumor (MFMT) resection often exhibit shortened femoral metaphyseal juxta-articular segments. The use of a customized femoral endoprosthesis (CFE) with an intra-neck curved stem (INCS) has emerged as a viable reconstructive surgical strategy for these individuals. Relative to a cemented INCS, it remains unclear as to whether cementless INCS use is associated with improvements in functionality or reconstructive longevity. As such, the present study was conducted to compare functional outcomes, endoprosthetic survival, and endoprosthesis-related complication rates in patients undergoing cemented and cementless INCS implantation.

Methods

A total of 24 patients undergoing lower limb salvage and reconstructive surgical procedures utilizing cemented or cementless INCS endoprostheses were retrospectively included. Patient-functional outcomes, endoprosthetic survival, and complication rates were compared as a function of age; diagnosis; the length of femoral resection; residual proximal femur length; Musculoskeletal Tumor Society (MSTS) scores; visual analog scale (VAS) scores; and the rates of implant breakage, periprosthetic infections, periprosthetic fractures, and aseptic loosening.

Results

The mean follow-up was 56 months. Significant differences in the length of femoral resection (p&lt;0.001) and residual proximal femur length were observed (p&lt;0.001) between the cemented and cementless INCS groups. There were no differences in overall patient survival and aseptic loosening-associated endoprosthesis survival in the cemented and cementless groups. None of the included patients experienced periprosthetic fractures, infections, or implant breakage. Average respective MSTS and VAS scores did not differ between groups.

Conclusion

For patients undergoing treatment for MFMTs, the use of a CFE with an INCS has emerged as a viable approach to hip-preserving reconstructive surgery. With appropriately designed individualized rehabilitative programs, good functional outcomes can be achieved for these endoprostheses, which are associated with low complication rates. Moreover, the selection between cemented or cementless INCS in the clinic should be made based on patient-specific factors, with cementless INCS implementation being preferable in younger patients with good-quality bone, the potential for long-term survival, and the osteotomy site near the lesser trochanter, whereas cemented INCS use should be favored for individuals who are older, have a shorter life expectancy, or have poor bone quality.

What Are the Long-term Surgical Outcomes of Compressive Endoprosthetic Osseointegration of the Femur with a Minimum 10-year Follow-up Period?

BACKGROUND

Endoprosthetic reconstruction after oncologic resection of bone tumors requires stable fixation between the prosthesis and residual host bone. Compressive osseointegration has been developed as an alternative to traditional stemmed implants to address the challenges and complications of achieving this fixation. Sufficient time has now passed from the advent of compressive implants to allow for an assessment of the intermediate-term and long-term results of this form of fixation.

QUESTIONS/PURPOSES

At a minimum follow-up of 10 years after implantation of a compressive osseointegration device for oncologic reconstruction: (1) What is the risk of periprosthetic fracture, aseptic loosening, or implant breakage resulting in revision surgery for endoprosthesis removal? (2) What is the long-term cortical response at the host-endoprosthesis interface as visualized on plain radiographs?

METHODS

A single-center, retrospective study was performed between 2002 and 2010, in which 110 patients with primary bone sarcoma of the proximal or distal femur were considered for oncologic resection and reconstruction. Patients were considered for a compressive osseointegration endoprosthesis if they were 50 years of age or younger, had not previously received femoral radiation, had no metabolic disease impairing bone healing, were not diagnosed with metastatic disease, and had life expectancy greater than six months. Of the 110 patients, 25 were treated with a compressive osseointegration implant of the proximal or distal femur, and 85 patients were treated with conventional stemmed implants or amputation because of older age, advanced disease, metabolic comorbidities, inability to tolerate a nonweightbearing postoperative period, or in the case of rotationplasty, patient preference. All patients who received this device during the period of study were considered eligible for inclusion in this review. The median (range) age was 18 years (7 to 50), and 13 of 25 patients were men. Five patients died of disease before the minimum follow-up duration of 10 years; two underwent amputation due to local recurrence and three died with the implant in situ, leaving 20 patients for complete analysis. Median follow-up was 144 months, and all 20 surviving patients had a minimum follow-up of 10 years (121 to 230 months). The primary endpoint was reoperation and implant removal for periprosthetic fracture, aseptic loosening, or mechanical breakage of any component of the compressive device in the endoprosthesis. In final analysis, death was considered a competing event to revision surgery, and cumulative incidence was reported after competing-event analysis. A secondary aim was radiographic evaluation of the host-implant interface to assess the long-term cortical response to compressive osseointegration.

RESULTS

Spindle fracture or loosening was noted in three patients, and the remaining 17 patients maintained the compression device until the final follow-up. The risk of reoperation for aseptic loosening, periprosthetic fracture, or mechanical breakage of the implant using a competing risks estimator was 12% at 10 years (95% CI 0% to 26%). These complications occurred within 29 months of the index surgery; no patients had implant loosening or mechanical breakdown after this initial period. On radiographic assessment, 14 patients demonstrated cortical hypertrophy of the bone-implant interface, six patients had maintenance of the native cortical contour, and no patients had cortical atrophy or narrowing at the implant interface.Conclusion Long-term follow-up in patients with compressive osseointegrative endoprosthetic devices demonstrated no late revisions because of periprosthetic fracture, aseptic loosening, or implant breakage in this cohort with a minimum 10-year follow-up. There was no evidence of late-onset cortical atrophy or stress shielding at the host-implant interface. This study supports the long-term stability of the interface between host bone and the endoprosthesis in compressive osseointegration devices.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Hip-Preserved Reconstruction Using a Customized Cementless Intercalary Endoprosthesis With an Intra-Neck Curved Stem in Patients With an Ultrashort Proximal Femur: Midterm Follow-Up Outcomes

Background: Hemiarthroplasty is widely used for proximal femoral reconstruction after tumor resection. However, complications of hemiarthroplasty include infection, hip dislocation, and acetabular wear. This study aimed to: (1) evaluate the reliability and validity of a customized cementless intercalary endoprosthesis (CCIE) with an intra-neck curved stem (INCS) to reconstruct femoral diaphyseal defects with an ultrashort proximal femur (UPF); (2) assess the lower extremity function after reconstruction with this endoprosthesis; and (3) identify the postoperative complications associated with the use of this endoprosthesis.

Methods: Between October 2015 and May 2019, 13 patients underwent reconstruction with a CCIE with an INCS. The distance from the center of the femoral head to the midline of the body and the apex of the acetabulum was measured preoperatively. Additionally, the distance from the tip of the INCS to the midline of the body and the apex of the acetabulum was measured postoperatively. The femoral neck–shaft angle was also measured pre- and postoperatively. After an average follow-up duration of 46 months, the radiological outcomes of the CCIE with an INCS were analyzed. Function was evaluated with the Musculoskeletal Tumor Society (MSTS) score. Pain was measured using a paper visual analog scale (VAS) pre- and postoperatively, and complications were recorded.

Results: Compared with our preoperative design, we found no significant difference in the postoperative distance from the tip of the INCS to the body midline (p = 0.187) and the apex of the acetabulum (p = 0.159), or in the postoperative femoral neck–shaft angle (p = 0.793). Thus, the INCS positions were deemed accurate. The average MSTS score was 26 (range: 24–28), and the VAS score was significantly decreased postoperatively compared with preoperatively (p < 0.0001). No patients developed aseptic loosening, infection, periprosthetic fracture, or prosthetic fracture as of the last follow-up.

Conclusion: The CCIE with an INCS was a valid and reliable method for reconstructing femoral diaphyseal defects with a UPF following malignant tumor resection. Postoperative lower extremity function was acceptable, with an appropriate individualized rehabilitation program, and the incidence of complications was low.

Is three-dimensional-printed custom-made ultra-short stem with a porous structure an acceptable reconstructive alternative in peri-knee metaphysis for the tumorous bone defect?

Background

Long-lasting reconstruction after extensive resection involving peri-knee metaphysis is a challenging problem in orthopedic oncology. Various reconstruction methods have been proposed, but they are characterized by a high complication rate. The purposes of this study were to (1) assess osseointegration at the bone implant interface and correlated incidence of aseptic loosening; (2) identify complications including infection, endoprosthesis fracture, periprosthetic fracture, leg length discrepancy, and wound healing problem in this case series; and (3) evaluate the short-term function of the patient who received this personalized reconstruction system.

Methods

Between September 2016 and June 2018, our center treated 15 patients with malignancies arising in the femur or tibia shaft using endoprosthesis with a 3D-printed custom-made stem. Osseointegration and aseptic loosening were assessed with digital tomosynthesis. Complications were recorded by reviewing the patients’ records. The function was evaluated with the 1993 version of the Musculoskeletal Tumor Society (MSTS-93) score at a median of 42 (range, 34 to 54) months after reconstruction.

Results

One patient who experienced early aseptic loosening was managed with immobilization and bisphosphonates infusion. All implants were well osseointegrated at the final follow-up examination. There are two periprosthetic fractures intraoperatively. The wire was applied to assist fixation, and the fracture healed at the latest follow-up. Two patients experienced significant leg length discrepancies. The median MSTS-93 score was 26 (range, 23 to 30).

Conclusions

A 3D-printed custom-made ultra-short stem with a porous structure provides acceptable early outcomes in patients who received peri-knee metaphyseal reconstruction. With detailed preoperative design and precise intraoperative techniques, the reasonable initial stability benefits osseointegration to osteoconductive porous titanium, and therefore ensures short- and possibly long-term durability. Personalized adaptive endoprosthesis, careful intraoperative operation, and strict follow-up management enable effective prevention and treatment of complications. The functional results in our series were acceptable thanks to reliable fixation in the bone-endoprosthesis interface and an individualized rehabilitation program. These positive results indicate this device series can be a feasible alternative for critical bone defect reconstruction. Nevertheless, longer follow-up is required to determine whether this technique is superior to other forms of fixation.

Outcomes of Cemented Distal Femoral Replacement Using "Line to Line" Technique With All-Polyethylene Tibial Implant for Tumors

BACKGROUND

Both cemented and cementless stemmed endoprosthetic implants have been used to reconstruct large skeletal defects after tumor resection with similar outcomes. In this study, we examined the oncologic, clinical, and functional outcomes in patients undergoing distal femur replacement using the French paradox technique.

METHODS

A total of 125 patients who underwent distal femur replacement between 1990 and 2019 using the line-to-line cementation technique were reviewed. Implant failure was recorded as per Henderson's classification. Functional outcomes were analyzed using the Musculoskeletal Tumor Society and Toronto Extremity Salvage Score scoring systems. The mean follow-up was 84 (1-350) months.

RESULTS

Aseptic loosening of the femoral stem was recorded in one patient at 21-years of follow-up. Twenty of 125 patients required bushing exchange for polyethylene wear, all after 10 years. Six tibial bearing component fractures were recorded in four patients while one femoral stem component Morse taper fractured. Two all-polyethylene cemented tibial implants were revised for polyethylene granuloma. Deep surgical site infection occurred in 13 patients, while six patients experienced local recurrence. Kaplan-Meier estimates for implant survival for all-cause revision were 85% at 1 year and 70% at 5 years. These estimates for femur or tibia loosening as an end point were 96% at 10 years and 90% at 15 years. The mean Musculoskeletal Tumor Society and Toronto Extremity Salvage Score scores at the last follow-up were 76% and 74%, respectively. Thirty-five patients died of disease progression.

CONCLUSION

The line-to-line cementation technique, used with all-polyethylene tibial implants, demonstrates low incidence of aseptic loosening at medium and long-term follow-ups.

LEVEL OF EVIDENCE

III.

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

BACKGROUND

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

QUESTIONS/PURPOSES

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

Level IV, therapeutic study.

A Contemporary Classification System of Femoral Bone Loss in Revision Total Hip Arthroplasty

BACKGROUND

Current femoral bone loss classification systems in revision total hip arthroplasty were created at a time when the predominant reconstructive methods used cylindrical porous-coated cobalt-chrome stems. As these stems have largely been replaced by fluted-tapered titanium stems, the ability of these classification systems to help guide implant selection is limited. The purpose of this study was to describe a novel classification system based on contemporary reconstructive techniques.

METHODS

We reviewed the charts of all patients who underwent femoral component revision at our institution from 2007 through 2019. Preoperative images were reviewed, and FBL was rated according to the Paprosky classification and compared to ratings using our institution's NCS. Rates of reoperation at the time of most recent follow-up were determined and compared.

RESULTS

Four-hundred and forty-two femoral revisions in 330 patients with a mean follow-up duration of 2.7 years were identified. Femoral type according to Paprosky and NCS were Paprosky I (36, 8.1%), II (61, 13.8%), IIIA (180, 40.7%), IIIB (116, 26.2%), and IV (49 11.1%) and NCS 1 (35, 7.9%), 2 (364, 82.4%), 3 (8, 1.8%), 4 (27, 6.1%), and 5 (8, 1.8%). Of the 353 nonstaged rTHAs, there were 42 cases requiring unplanned reoperation (11.9%), including infection (18, 5.1%), instability (10, 2.8%), femoral loosening (5, 1.4%), and various other causes (9, 2.5%). The NCS was more predictive of reoperation than the Paprosky classification (Fisher's exact test, P = .008 vs P = ns, respectively).

CONCLUSION

We present a novel femoral classification system that can help guide contemporary implant selection.

Interlocking reconstruction-mode stem-sideplates preserve at-risk hips with short residual proximal femora

AIMS

We have evaluated the survivorship, outcomes, and failures of an interlocking, reconstruction-mode stem-sideplate implant used to preserve the native hip joint and achieve proximal fixation when there is little residual femur during large endoprosthetic reconstruction of the distal femur.

METHODS

A total of 14 patients underwent primary or revision reconstruction of a large femoral defect with a short remaining proximal femur using an interlocking, reconstruction-mode stem-sideplate for fixation after oncological distal femoral and diaphyseal resections. The implant was attached to a standard endoprosthetic reconstruction system. The implant was attached to a standard endoprosthetic reconstruction system. None of the femoral revisions were amenable to standard cemented or uncemented stem fixation. Patient and disease characteristics, surgical history, final ambulatory status, and Musculoskeletal Tumor Society (MSTS) score were recorded. The percentage of proximal femur remaining was calculated from follow-up radiographs.

RESULTS

All 14 at-risk native hip joints were preserved at a mean final follow-up of 6.0 years (SD 3.7), despite a short residual femur, often after proximal osteotomies through the lesser trochanter. Overall, 13 of 14 stems had long-term successful fixation. Eight patients required no reoperation. Three patients required reoperation due to implant-related issues, and three patients required reoperation for wound healing problems or infection. There were no dislocations or fractures. At final follow-up the mean MSTS score was 24.9 (SD 4.1). Nine patients required no ambulation aids, and only one had a Trendelenburg gait.

CONCLUSION

This interlocking, reconstruction-mode stem-sideplate reliably preserves native hip joint anatomy and function after large femoral resection with a short remaining proximal femur, both in the primary and revision setting. This is particularly important for preventing or delaying total femoral arthroplasty in young patients after oncological reconstruction. Hip abductor strength and function could be maintained by this method, and the risk of dislocation eliminated. The success of this technique in this modest series should be verified in a larger collaborative study and will be of interest to revision surgeons and oncologists. Cite this article: Bone Joint J 2021;103-B(2):398-404.

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.

Long term outcomes of total humeral replacement for oncological reconstructions: A single institution experience

BACKGROUND

There is a paucity of data on long-term survivorship and outcomes for total humerus replacements (THR) with only two series reporting 10-year survival.

PATIENTS AND METHODS

A review of 769 consecutive, prospectively collected endoprosthetic reconstructions for oncological diagnoses at a single-center between 1980 and 2019 was performed. Patients with THRs were isolated and analyzed for outcomes, complications, and modes of failure.

RESULTS

Eighteen patients with 20 THR implants were identified. The median follow-up for surviving patients was 148 months (interquartile range [IQR] = 74-194) and 60 months (IQR = 17-155 months) for all patients. Two prostheses required revision for failure, both for symptomatic shoulder dislocation. There were three local recurrences. Revision-free survival at 5, 10, and 15 years was 100%, 86% and 86%, respectively. There were no cases of ulnar component failure, radial nerve palsy, or periprosthetic infection.

CONCLUSIONS

THR prosthesis survivorship is comparable to the previous series, with a longer follow-up than has previously been reported. Symptomatic shoulder instability was common (25%), and was the only cause of revision. Reverse total shoulder could be an important way to address this in the future. Local recurrence rates were high, as has been reported elsewhere for THR.

Radiographic parameter-driven decision tree reliably predicts aseptic mechanical failure of compressive osseointegration fixation

Background and purpose - Compressive osseointegration fixation is an alternative to intramedullary fixation for endoprosthetic reconstruction. Mechanical failure of compressive osseointegration presents differently on radiographs than stemmed implants, therefore we aimed to develop a reliable radiographic method to determine stable integration.Patients and methods - 8 reviewers evaluated 11 radiographic parameters from 29 patients twice, 2 months apart. Interclass correlation coefficients (ICCs) were used to assess test-retest and inter-rater reliability. We constructed a fast and frugal decision tree using radiographic parameters with substantial test-retest agreement, and then tested using radiographs from a new cohort of 49 patients. The model's predictions were compared with clinical outcomes and a confusion matrix was generated.Results - 6 of 8 reviewers had non-significant intra-rater ICCs for ≥ one parameter; all inter-rater ICCs were highly reliable (p < 0.001). Change in length between the top of the spindle sleeve and bottom of the anchor plug (ICC 0.98), bone cortex hypertrophy (ICC 0.86), and bone pin hypertrophy (ICC 0.81) were used to create the decision tree. The sensitivity and specificity of the training cohort were 100% (95% CI 52-100) and 87% (CI 74-94) respectively. The decision tree demonstrated 100% (CI 40-100) sensitivity and 89% (CI 75-96) specificity with the test cohort.Interpretation - A stable spindle length and at least 3 cortices with bone hypertrophy at the implant interface predicts stable osseointegration; failure is predicted in the absence of bone hypertrophy at the implant interface if the pin sites show hypertrophy. Thus, our decision tree can guide clinicians as they follow patients with compressive osseo-integration implants.

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.

Chemotherapy Curtails Bone Formation From Compliant Compression Fixation of Distal Femoral Endoprostheses

BACKGROUND

Modulated compliant compressive forces may contribute to durable fixation of implant stems in patients with cancer who undergo endoprosthetic reconstruction after tumor resection. Chemotherapy effects on bone hypertrophy and osteointegration have rarely been studied, and no accepted radiologic method exists to evaluate compression-associated hypertrophy.

QUESTIONS/PURPOSES

(1) What was the effect of chemotherapy on the newly formed bone geometry (area) at 1 year and the presumed osteointegration? (2) What clinical factors were associated with the degree of hypertrophy? (3) Did the amount of bone formation correlate with implant fixation durability? (4) Was the amount of new bone generation or chemotherapy administration correlated with Musculoskeletal Tumor Society (MSTS) score?

METHODS

Between 1999 and 2013, we performed 245 distal femoral reconstructions for primary or revision oncologic indications. We evaluated 105 patients who received this implant. Ten were excluded because they lacked 2 years of followup and two were lost to followup, leaving 93 patients for review. All underwent distal femur reconstruction with the compliant compressive fixation prosthesis; 49 received postoperative chemotherapy and 44 did not. During this period, the implant was used for oncology patients < 60 years of age without metastases and with > 8 cm of intact, nonirradiated bone distal to the lesser trochanter and ≥ 2.5 mm of cortex. Our cohort included patients with painful loosening of cemented or uncemented stemmed femoral megaprostheses when revision with the compliant compressive device was feasible. Patients with high-grade sarcomas all received chemotherapy, per active Children's Oncology Group protocols, for their tumor diagnosis. At each imaging time point (3, 6, 9, 12, 18, 24 months), we measured the radiographic area of the bone under compression using National Institutes of Health open-access software, any shortening of the spindle-anchor plug segment distance as reflected by the exposed traction bar length, and prosthesis survivorship. Clinical and functional status and MSTS scores were recorded at each followup visit. Duration of prosthesis retention without aseptic loosening or mechanical failure was evaluated using Kaplan-Meier analysis, censoring patients at last followup.

RESULTS

Chemotherapy was associated with the amount of overall bone formation in a time-dependent fashion. In the 12 months after surgery there was more bone formation in patients who did not receive postoperative chemotherapy than those who did (60.2 mm, confidence interval [CI] 49.3-71.1 versus 39.1, CI 33.3-44.9; p = 0.001). Chemotherapy was not associated with prosthesis survival. Ten-year implant survival was 85% with chemotherapy and 88% without chemotherapy (p = 0.74). With the number of patients we had, we did not identify any clinical factors that were associated with the amount (area) of hypertrophy. The hypertrophied area was not associated with the durability of implant fixation. MSTS scores were lower in patients treated with chemotherapy (25 versus 28; p = 0.023), but were not correlated with new bone formation.

CONCLUSIONS

The relationships among chemotherapy, bone formation, and prosthetic survivorship are complex. Because bone formation is less in the first year when the patient is being treated with chemotherapy, it is not clear if the rehabilitation schedule should be different for those patients receiving chemotherapy compared with those who do not. The relationship between early bone formation and the timing of weightbearing rehabilitation should be evaluated in a multicenter study.

LEVEL OF EVIDENCE

Level III, therapeutic study.

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.

Influence of implant length and bone defect situation on primary stability after distal femoral replacement in vitro

BACKGROUND

Aseptic loosening is the major reason for failure of distal femoral replacement using current modular megaprostheses. Although the same stems are used for proximal and distal replacement, survival rates in clinical studies with distal reconstruction were lower within the same system compared to proximal reconstruction. We analyzed whether primary stability as presupposition for long-term fixation can be achieved with a current tapered stem design. Additionally, we hypothesized that stem length affects primary stability depending on bone defect situations.

METHODS

A modular tumor system (Megasystem-C®, Link GmbH, Hamburg, Germany) with two different tapered stems (100 and 160mm) was implanted in eight Sawbones® in two consecutively created defect situations (10 and 20cm proximal to knee joint level). Primary rotational stability was investigated by measuring relative micromotions between implant and bone to identify the main fixation areas and to characterize the fixation pattern.

RESULTS

The fixation differed between the two stem lengths and with respect to both defect situations; however in each case the main fixation area was located at or close to the femoral isthmus. Highest relative micromotions were measured with the 160-mm stem at the distal end within small bone defects and at the proximal end when defects were increased.

CONCLUSIONS

The analyzed design seemed to create sufficient primary stability along the main fixation areas of the implant. Based on these results and with respect to oncologic or potential revision situations, we suggest the use of the shorter stem to be more favorable in case of primary implant fixation.

Use of Compressive Osseointegration Endoprostheses for Massive Bone Loss From Tumor and Failed Arthroplasty: A Viable Option in the Upper Extremity

BACKGROUND

Endoprostheses using principles of compressive osseointegration have shown good survivorship in several studies involving the lower extremity; however, no series to our knowledge have documented the use of this technology in the management of massive bone loss in the upper limb.

QUESTIONS/PURPOSES

(1) What proportion of upper extremity implants using compressive osseointegration fixation principles achieved durable short-term fixation, and what were the modes of failure? (2) What surgical complications resulted from reconstruction using this technique?

METHODS

A multiinstitutional retrospective review identified nine patients (five women; four men) who underwent 13 endoprosthetic replacements between 2003 and 2014 using compressive osseointegration (Compliant^® Pre-stress Device [CPS]; Biomet Inc, Warsaw, IN, USA) in the upper extremity, including two proximal humeri, two humeral diaphyses, seven distal humeri, and two proximal ulna. During the early part of that period, the indication for use of a compressive prosthesis in our centers was revision of a previous tumor reconstruction (allograft-prosthetic composite or stemmed endoprosthetic reconstruction) (three patients; five implants), or revision arthroplasty with massive bone loss (three patients, four implants); more recently, indications became somewhat more permissive and included posttraumatic bone loss (one patient, one implant), primary bone sarcoma, and resections with very short remaining end segments after diaphyseal resections (two patients, three implants). Minimum followup was 24 months; one patient (one implant) was lost to followup before that time with the implant intact at 14 months and no patients have died. The mean age of the patients was 45 years (range, 21-62 years). Mean followup was 68 months (range, 24-141 months). Implant revision for any cause and for failure of the CPS mechanism was recorded. Modes of failure were categorized as soft tissue, aseptic loosening, structural, infection, and tumor progression; CPS modes of failure were defined as lack of fixation, with or without bone or implant fracture.

RESULTS

Of the 12 implants accounted for beyond 2 years, six had undergone revision of any kind. Only two revisions in two patients were attributable to lack of CPS fixation at the bone-implant interface; one of the patients also had periprosthetic and implant fracture develop through the traction bar. Other modes of failure were aseptic loosening of the standard ulnar component (two patients, two implants), bushing wear (one patient; one implant) and infection resulting in two-stage exchange and free soft tissue transfer with retention of the CPS spindle (one patient, one implant). Complications for all nine patients included one transient radial nerve palsy, one ulnar nerve sensory neurapraxia, one superficial infection, and two glenohumeral subluxations, one underwent revision surgery with implantation of a constrained liner.

CONCLUSIONS

A compressive osseointegration endoprosthesis is an option for very difficult revisions or sarcoma resection in the upper extremity in which the remaining segment of host bone is too short for a conventional prosthesis. However, surgeons must inform patients that these are salvage operations, and revision surgery is common. Long-term followup of more patients is necessary to further document the survivorship of these implants in the upper extremity.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

What Factors Are Associated With Failure of Compressive Osseointegration Fixation?

BACKGROUND

Compressive osseointegration is as an alternative to traditional intramedullary fixation. Two- to 10-year survivorship and modes of failure have been reported; however, as a result of relatively small numbers, these studies are limited in their ability to identify risk factors for failure.

QUESTIONS/PURPOSES

(1) What is survivorship free from aseptic mechanical and survivorship free from overall failure of compressive osseointegration fixation? (2) What patient factors (age, sex, body mass index [BMI], anatomic location of reconstruction, indication for reconstruction, radiation, chemotherapy) are associated with increased risk of failure?

METHODS

Between 2006 and 2014, surgeons at one center treated 116 patients with 137 Compress^® implants for lower extremity oncologic reconstructions, revision arthroplasty, and fracture nonunion or malunion. One hundred sixteen implants were available for review with a minimum of 2-year followup (mean, 4 years; range, 2-9 years). Kaplan-Meier survival plots were produced to examine survivorship and Cox regression modeling was used to generate hazard ratios (HRs) for potential risk factors for failure. Patient factors (age, sex, BMI, anatomic location of reconstruction, indication for reconstruction, radiation, chemotherapy) were obtained from chart review and an institutional database.

RESULTS

Survivorship free from aseptic mechanical failure was 95% (95% confidence interval [CI], 91%-99%) at 18 months and 93% (95% CI, 86%-99%) at 4 years. Survivorship free from overall failure was 82% (95% CI, 75%-89%) at 18 months and 75% (95% CI, 66%-84%) at 4 years. Risk of overall failure was increased with reconstruction of the proximal tibia (HR, 4.42; 95% CI 0.98-19.9) and distal femur (HR, 1.74; 95% CI, 0.50-6.09) compared to the proximal femur (HR, 1; referent; p = 0.049). Risk of aseptic mechanical failure was increased with reconstruction of the proximal tibia (HR, 1; referent) and distal femur (HR, 0.37; 95% CI, 0.08-1.77) compared with the proximal femur (HR, 0, p = 0.048). Radiation was associated with increased risk of overall failure (HR, 3.85; 95% CI, 1.84-8.02; p < 0.003), but not aseptic mechanical failure. Age, sex, BMI, chemotherapy, and surgical indication were not associated with increased risk of aseptic or overall failure.

CONCLUSIONS

This study questions the use of age as a contraindication for the use of this technology and suggests this technology may be considered in proximal femoral reconstruction and for patients with indications other than primary oncologic reconstructions. Future research should establish long-term survivorship data to compare this approach with conventional intramedullary stems and to evaluate the potential benefits of preventing stress shielding and preserving bone stock in revision situations.

LEVEL OF EVIDENCE

Level III, therapeutic study.

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.

What are the 5-year survivorship outcomes of compressive endoprosthetic osseointegration fixation of the femur?

BACKGROUND

Aseptic complications such as stress shielding leading to bone loss are major problems associated with revision of cemented and uncemented long-stem tumor endoprostheses. Endoprosthetic reconstruction using compressive osseointegration fixation is a relatively new limb salvage technology designed to enhance osseointegration, prevent stress shielding, and provide fixation for short end-segments.

QUESTIONS/PURPOSES

(1) What is the survivorship of this technique at minimum 5-year followup? (2) Were patient factors (age, sex, body mass index), oncological factors, or anatomic locations associated with implant failure? (3) Were there any prosthesis-related variables associated with failure?

METHODS

A single-center, retrospective review of patients with a minimum 5-year followup (mean, 8 years; range, 5-12 years) treated with an osseointegration compressive device for endoprosthetic fixation of proximal and distal femoral limb salvage reconstructions was performed. We have previously published the implant survivorship of this patient cohort with a minimum 2-year followup and are now reporting on the 5-year survivorship data. From 2002 to 2008, we performed 22 such procedures in 22 patients. Four patients died of their disease within 5 years of surgery and all surviving patients (n = 18) had complete followup data at a minimum of 5 years. General indications for this device during that time were pediatric and adult patients requiring primary endoprosthetic reconstructions of the proximal or distal femur for benign and malignant bone lesions. The primary outcome was reoperations for mechanical (aseptic) failures. Secondary outcomes included implant removal for nonmechanical failures and any patient-, oncological-, or implant-related variables associated with implant removal.

RESULTS

At a minimum of 5 years followup, overall mechanical (aseptic) implant survivorship was 16 of 18. Survivorship for all modes of failure (oncological failure, infection, arthrofibrosis, and mechanical failure) was 12 of 18. All mechanical failures occurred early, within the first 30 months. We identified no patient-, oncological-, or implant-related features predictive of failure.

CONCLUSIONS

Our intermediate-term experience with compressive osseointegration fixation for endoprosthetic limb reconstructions demonstrates with longer clinical followup, no additional mechanical failures were observed as compared with our early analysis. Our experience with this fixation at a minimum of 5-years followup adds to a very limited but increasing body of literature demonstrating that after a transient period of increased risk for implant failures, survivorship stabilizes. Assessment of this fixation strategy beyond 10 years of clinical followup is needed.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Novel applications of osseointegration in orthopedic limb salvage surgery

Osseointegration is a biologic process vital to modern endoprosthetic fixation in orthopedic surgery. Numerous engineering advancements have improved the utilization of this technology in orthopedics; however, issues such as stress shielding, aseptic loosening, and bone loss remain an ongoing challenge. These host responses are especially problematic in limb salvage surgery. Novel applications of osseointegration have been developed to address some of these fixation issues with massive tumor endoprostheses. This articles reviews osseointegration and emerging novel applications of this technology in limb salvage surgery and future prosthetics for amputees.

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.

Short-stem reconstruction for megaendoprostheses in case of an ultrashort proximal femur

Background

Tumors of the distal femur and diaphysis with proximal metaphyseal extension into the femur present a challenge for limb salvage. The conventional treatment consists of limb salvage with total femur replacement. This case study aims to present preliminary results and experience with short-stem reconstruction, focusing on the mechanical stability of the procedure.

Methods

Sixteen short stems were implanted in 15 patients. The patients’ mean age was 33,3 years (range 11–73). In 10 patients, the stem was used for distal femur reconstruction, in one patient for diaphyseal reconstruction, and in four for a stump lengthening procedure. All of the patients had a primary sarcoma in their history. The mean follow-up period was 37 months (range 5–95 months). The clinical and functional follow-up data were analyzed.

Results

Ten patients (67%) were still alive at the time of evaluation. Three complications associated with the stem were noted. In one case, there was aseptic loosening after 58 months; in another, aseptic loosening occurred because the diameter of the stem had initially been too small; and in one case, there was breakage of the fixation screw, without any clinical symptoms. The average Musculoskeletal Tumor Society score for all patients was 23 (range 9–28). The mean result for the distal femur replacement was 24 (range 22–28). None of the surviving patients with distal femur replacements needed any crutches or had a Trendelenburg limp. Both living patients who underwent a stump lengthening procedure were able to walk with an exoprosthesis.

Conclusions

The short stem is a good solution that can prevent or delay proximal femur resection in patients with tumors extending into the proximal metaphyseal femur. Additional risks of proximal femur resection, such as dislocation, opening of another oncological compartment, Trendelenburg limp, and chondrolysis can be avoided.