Pseudotumor after Total Wrist Arthroplasty Mimicking a Neoplasm

Abstract

Background  Total wrist arthroplasty can lead to a variation of complications. One of these is the formation of a pseudotumor. Although this complication is well known after total hip arthroplasty, it is rare in patients with wrist implants.

Case Description  A 55-year-old man with a Universal 2 (Integra, Plainsboro, NJ) wrist prosthesis was seen with a progressive mass on the radial side of his wrist since 1 year, initially suspicious for a neoplasm. However, after exploration, histopathology confirmed a particle-induced foreign body reaction.

Literature Review  There is little literature on pseudotumor formation after total wrist arthroplasty. Currently, there is no clear consensus about the etiology of pseudotumors but possible causes may include foreign body reaction, hypersensitivity, and wear debris.

Clinical Relevance  This case report shows that particle debris-induced pseudotumors should be considered when a patient with a wrist prosthesis presents with a mass suspicious for a neoplasm. In addition, treatment options of pseudotumors after wrist arthroplasty in literature is discussed.

A known complication after total wrist arthroplasty (TWA) is periprosthetic osteolysis. ^{1 2} One of the possible causes of periprosthetic osteolysis is the wear debris of the implant, known as periprosthetic osteolysis by small particle disease. ³ An artificial joint implant produces wear particles that are eliminated by the immune system, creating a balance between the particle production and clearance of the particles. ⁴ However, when the particle load exceeds the elimination capacity, an imbalance occurs and a decompensation process begins. ⁴ A complex immunologic reaction is activated, ultimately leading to a disturbed balance between osteoresorption and osteogenesis, with osteoresorption predominating, and eventually resulting in osteolysis. ⁴ Periprosthetic osteolysis is frequently associated with aseptic loosening of the prosthesis but can also occur in isolation. ⁵

Another possible complication of arthroplasty, which has mainly been described after total hip arthroplasty (THA), ⁶ is the formation of a pseudotumor. A pseudotumor is an aseptic, nonmalignant mass ⁷ that is seen in metal-on-metal (MoM), metal-on-polyethylene (MoP), and metal-on-ceramic (MoC) implants. ⁸ Although pseudotumors are a frequently described complication after THA, it has, to our knowledge, only been described once after TWA. ⁹ Recently, we were confronted with a pseudotumor after TWA.

Case Presentation

In 2019, a 55-year-old man presented to our department with a mass on the radial side of his left wrist. In 2003, we performed a TWA with a BIAX (DePuy Orthopaedics, Warsaw, IN) prosthesis, which was replaced in 2007 by the Universal 2 (Integra, Plainsboro, NJ) prosthesis. The procedure was uneventful, and the postoperative X-rays showed a good position ( Fig. 1 ). He was not seen until he presented with the mass in 2019.

Fig. 1.

( A, B ) First presentation in 2003 with a scapholunate advanced collapse wrist. ( C ) Postoperative X-ray after total wrist arthroplasty using the BIAX prosthesis in 2003. ( D, E ) Postoperative radiographs after replacement of the BIAX by the Universal 2 prosthesis in 2007.

The mass emerged 1 year before and was progressive. Physical examination exhibited a fixed, hard mass at the height of the distal radius ( Fig. 2 ). Wrist function was not affected.

Fig. 2.

Clinical appearance at presentation in 2019 seen from ( A ) the palmar, ( B ) radial and ( C ) dorsal side of the wrist.

X-rays of the wrist ( Fig. 3 ) showed soft-tissue swelling with diffuse punctate dense structures on the volar, radial, and dorsal side of the radiocarpal joint. An expansive, predominantly lytic bone lesion with cortical destruction on the dorsal, radial, and volar side of the prosthesis was seen at the distal radius. On the volar side, the bone lesion also showed a more sclerotic (cloud-like) bone matrix. Furthermore, the distal ulna showed a partially similar, mixed lucent and sclerotic aspect with some bone expansion. Both lesions lacked a sharp transition zone from normal to abnormal bone. Because of these radiological findings, a malignant process could not be ruled out. An ultrasound-guided puncture of the mass was taken. However, this showed inflammatory cells and no malignant cells.

Fig. 3.

X-rays taken on the day of presentation in 2019, showing the mass on ( A ) the posteroanterior and ( B ) lateral image. Note that on the ulnar side of the radial component, there is no radiolucency.

At operation, we saw porous bone radially of the implant ( Fig. 4 ). The mass was excised and sent for pathology. A wound culture was taken to rule out infection. The prosthesis was removed and wear was noticed on the polyethylene cap of the implant. A total wrist arthrodesis with a 12-hole dorsal plate, cancellous bone from the iliac crest, and donor femoral head was performed ( Fig. 5 ). Histopathology of the excised tissue showed histiocytic multinucleated giant cell response to foreign body material.

Fig. 4.

Wrist at operation. ( A ) The Universal 2 implant in situ with partially excised tissue. ( B ) The removed tissue. ( C ) The removed Universal 2 wrist prosthesis. Note the wear on the polyethylene cap.

Fig. 5.

( A, B ) Postoperative radiographs after conversion of the Universal 2 prosthesis to an arthrodesis, using a 12-hole plate, with cancellous bone of the iliac crest and a donor femoral head.

Discussion

Currently, there is no clear consensus in literature about the etiology of pseudotumors after arthroplasty. ⁶ Potential causes of pseudotumor formation may include foreign body reaction, hypersensitivity, and wear debris. ¹⁰ Particle debris arises through wear of the implant and may consist of polyethylene, bone, cement, metal, metallic corrosion products, or hydroxyapatite particles. ⁴ The prosthesis used in our patient was the Universal 2. This implant consists of a polyethylene-plated titanium carpal component and a cobalt chrome radial component. ¹¹ The mechanism of pseudotumor formation in polyethylene debris and metal debris appears to be different. ¹⁰ Polyethylene particles are phagocytosed by macrophage giant cells, which release prostaglandin E2, subsequently leading to bone resorption and eventually to a vicious cycle of wear and loosening. ¹⁰ In case of metal debris, it is assumed that cytotoxicity due to high concentration phagocytosed metal nanoparticles in macrophages in periprosthetic tissues cause pseudotumors in patients with MoM hip implants. ¹⁰

There is little literature about pseudotumors after TWA. Taha et al reported a pseudotumor secondary to metallosis after TWA. ⁹ Their patient underwent revision wrist arthroplasty with resection of the pseudotumor to healthy tissue and graft of the defect bone with BioSet Putty. ⁹

On the other hand, periprosthetic osteolysis has been reported in several studies on the outcome of the Universal 2 prosthesis. However, none of these studies report osteolysis mimicking a neoplasm or mention the formation of a pseudotumor. ^{12 13 14} In a recent study, Fischer et al described a radiologic tumor-like presentation of periprosthetic osteolysis after TWA is mentioned. ¹⁵ Although they did not formally mention a pseudotumor, the radiographs are similar to our patient.

In our case, the mass was initially suspected of a neoplasm. Primary malignant bone tumors are rare and are estimated to only represent 0.2% of all newly diagnosed cancer cases in 2020. ¹⁶ Although malignant bone tumors are a rare diagnosis, the clinical and radiographic findings, such as lytic bone, sclerotic (cloud-like) bone, cortical destruction, expansion, involvement of soft tissue and ill-defined transition zone, still suggested a malignant process. Aseptic loosening due to periprosthetic osteolysis was also considered. However, this is seen on X-rays as radiolucent lines or areas around the implant; therefore, this diagnosis did not match our case. ¹⁷

In general, there are three treatment options for failed TWA: total wrist arthrodesis, resection arthroplasty, or revision TWA. ^{18 19 20} In patients with poor remaining bone stock, revision TWA can be challenging, ^{18 19} and after performing total wrist arthrodesis, nonunion can occur. ²¹ Considering the amount of bone loss in our patient, a total wrist arthrodesis was performed. Cancellous bone of the iliac crest and a donor femoral head were placed into the spaces between the remaining bone to maintain adequate length of the tendons.