Rotating-Hinge Knee Prosthesis in Treatment of Malignant Tumors Around the Knee Joint: Clinical and Functional Outcomes with A Literature Review

Keywords

Malignant Bone Tumor; Rotating-Hinge Knee; Prosthesis; Outcomes; Complications.

Introduction

Segmental resections and joint reconstruction used to treat malignant tumors around the knee joint offer several advantages including maintenance of motion and early functional restoration [1, 2]. The rotating-hinge knee prosthesis that combines movement in 3 directions (flexion-extension, rotation, and distraction) allows dispersing stresses throughout the components, reduces constraints on the bone-implant interface [3] and permits weight bearing throughout the tibial articulation. We report through this article, the clinical and functional outcomes of 12 patients followed for malignant tumors around the knee, treated by rotatinghinge knee prosthesis during the last 3 years from January 2017 to December 2019.

Patients and Method

In the present study, the authors performed a retrospective study of the outcomes in patients diagnosed with malignant tumor around the knee joint treated in the department of orthopedic surgery B4 of the University Hospital of Fez (Morocco) with rotating-hinge knee prosthesis (Figure 1). There were 12 distal femoral and proximal tibial replacements. The tumor diagnosis was osteosarcoma in 8 cases, chondrosarcoma in 2 cases and malignant giant cell tumor in 2 patients (Figure 2 and 3). According to the TNM classification [4], at the time of the initial diagnosis, 6 patients were stage IB, 5 patients were stage IIB, and 1 patient was stage III [4]. At the time of the initial evaluation, all patients underwent a thorough oncologic examination, which included chest radiography, computed tomography, and magnetic resonance imaging (MRI). There were no distant metastases of the primary musculoskeletal tumor at the time of reconstructive surgery. Excision was performed through a medial parapatellar approach including the previous biopsy site. Uninvolved vastus muscle was spared, and a 2 centimeters bone and muscle margin was taken around the tumor (Figure 4). Preoperative and postoperative chemotherapy was used in 5 patients. Three patients had preoperative radiation therapy. Clinical data were retrieved from the clinical charts, radiographs and outpatient interviews. The median tumor size was 8 cm. Five tumors were epiphyseal and the remainder metaphyseal. Function was assessed by the criteria of the Musculoskeletal Tumor Society (MSTS) [4]. Seven items were analyzed for this, which are movement, pain, stability, deformation, strength, functional activities and emotional acceptance of reconstruction by the patients. Radiographic assessment followed the guidelines proposed by the International Symposium on Limb Salvage (ISOLS) [5] based on 6 parameters, namely, bone remodeling, interface, anchorage, implant body problem, implant articulation, and extracortical bone bridging. In terms of complications, we deplore two cases of skin necrosis associated with early infection and 1 case of aseptic loosening.

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Figure 1:

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Figure 1. Image of Rotating-hinge knee prosthesis.

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Figure 2:

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Figure 2. Intraoperative view of a giant cell malignant tumor of the right knee.

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Figure 3:

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Figure 3. Image of a giant cell tumor of the proximal tibia after resection.

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Figure 4:

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Figure 4. Intraoperative view of Rotating-hinge knee prosthesis in place after tumoral resection and joint reconstruction.

Results

Function

The arc of motion at the latest follow-up ranged from 20° of extension to 130° of flexion with a median of 110°. According to the Musculoskeletal Tumor Society (MSTS) evaluation system, functional score ranged from 12 to 30 with 23 of a mean (Table 1). The salvaged limb was painless in 8 patients (67 %), and 4 patients (33%) had no functional restriction. Two patients who had a resection of an osteosarcoma, presented postoperatively skin necrosis and early infection managed by complete prosthetic exchange and local rotation muscle flap to cover the prosthesis with vascularized tissue. The third patient had a resection of malignant giant cell tumor from the distal femur and developed aseptic loosening of the femoral component at the latest follow-up which was 30 months on average. At the time of last follow-up, 9 patients were continuously disease free, 2 were alive with metastatic disease, and 1 patient had died of disease. None of the patients in the study group developed local recurrences.

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Table 1:

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Table 1. The Mean Musculoskeletal Tumor Society (MSTS) Functional Score.

Radiographic Evaluation

Radiographs were available for all patients. The analysis was rated as good to excellent scores with regard to bone remodeling, interface radiolucent lines and anchorage. Nine patients were rated as excellent and good with regard to bone remodeling. The patient who had revision surgery for aseptic loosening was rated as poor with regard to the prosthetic-bone interface. Magnetic resonance imaging (MRI) for detection of local recurrence and chest computed tomography (CT) for lung metastasis were routinely arranged every 3 months in the first 2 years and every 6 months beyond. In our series, the prosthetic survival without clinical or radiographic failure was 75% at 3 years.

Discussion

Reconstruction for malignant tumors around the knee after wide resection remains a challenging problem. In this context, prosthetic replacement offers several advantages including early stability and mobilization which are especially important for patients with life-threatening malignant bone tumors. Since 1975, many various models of hinge knee prostheses were developed and used.

From a biomechanical point of view, Ward et al., [6] reported in 2003 an analysis of the third generation of rotating hinge Total Knee Arthroplasty (TKA). The study showed that prosthesis with shorter and markedly tapered pegs could become unstable under mild joint distraction. In 2013, Friesenblicher et al., [7] evaluated stability of rotating hinge knee prostheses (Figure 3). They found that the long and cylindrical pegs offer the highest stability at any given level of distraction.

In their beginning, tumor prostheses were produced in monoblock form of cast steel alloys. Then material evolution was made towards titanium and cobalt-chrome molybdenum. To address of requisites in resistance to corrosion, biocompatibility, resistance to fatigue fractures and higher potential of osteointegration, the development of the metallurgical industry and prosthesis design have providing a variety of coatings, fixing materials and implant geometry which have significantly improved stability and longevity of prostheses [8, 9].

The complication rate after prosthetic replacement remains high. The rate of infection ranged from 3% to 22% in previous reports [10, 11]. Haijie et al., [12] showed that the mean incidence of infection was 8.5% and 16.8% for respectively distal femoral and proximal tibial replacement.

Structural failures are not an uncommon complication after tumor prosthesis implantation. The most common site of breakage often reported is the stem collar junction. In this context, Agarwal et al., [13] identified 28 breakages in 266 megaprosthetic knee arthroplasties which achieves a rate of 10%. Capanna et al., [14] evaluated 200 megaprostheses in lower limb reconstruction after tumor resection at a minimum follow-up of two years. The authors observed structural failures in 7% of the cases. Bus et al [15] reported at the same time 14% of structural failure after a mean of three years.

In most cases following wide excision of high-grade sarcomas, soft tissue stability is difficult to maintain. In these cases, rotating- hinge knee prostheses provide the stability required for arthroplasty. When there is greater force transmitted to the fixation interfaces, premature aseptic loosening is highly favored [16, 17]. In various studies, the rate of this complication varied between 5 and 48% [18-21].

Skin necrosis is one of the most daunting complications of reconstruction for malignant tumors around the knee after wide resection. Postoperative wound complications developed more frequently after extra articular resections. The incidence of skin complications is around 12.5% for Kawai et al., [21] and ranges from 0.33% to 10.5% for Galat et al., [23] and Gaine et al [23]. Factors that increase the risk of skin necrosis after tumor prosthesis can be systemic including smoking, diabetes mellitus, increasing patient age, obesity, immunocompromised state, preexisting peripheral vascular disease, malnutrition, chronic renal insufficiency, and chemotherapy, or local factors represented by dystrophic skin, hematoma, prior surgery on the affected knee, and prior skin irradiation.

Regarding implant survival, the values are very variable. Many reports described 5 year overall survival rates of 32% to 44.5%. At 10 years, Kalra et al., [10] reported a survival rate of 37%. Otherwise, survival rates were higher in other series such as that of Shehadeh et al [18] which reported 84% at 5 years, 72% at 10 years and 37% at 20 years. In terms of factors influencing implant survival, the authors reported surgery methods, lung metastasis, clinical stage and cycles of chemotherapy [24-26].

In the present study, tumoral resection and joint reconstruction using rotating-hinge knee prosthesis were performed safely and successfully. Our clinical and functional outcomes obtained were comparable to those of the literature. It was the same for the rate of infection, skin necrosis, structural failures and aseptic loosening. As a reminder our prosthetic survival without clinical or radiographic failure was 75% at 3 years.

Conclusion

Rotating-hinge knee prostheses represent a gold standard in oncologic orthopedic surgery, as they facilitate efficient reconstruction of large skeletal resection, combined with high limb salvage rate. With great conviction, we adopt this saving attitude offering a good quality of life to the patients with a view to a prospective study with longer following up and a greater number of patients.