Etiopathogenesis of osteolytic cysts associated with total ankle arthroplasty, a histological study.

BACKGROUND: Osteolytic cyst formation after total ankle arthroplasty has been identified in recent years and is probably an important problem with longer follow-up. The aim of this study is to describe the outcome of a histological analysis of samples from periprosthetic intra-osseous cysts and joint capsules, retrieved during revision surgery after primary total ankle arthroplasty. METHODS: All samples (n=22) were analyzed and scored using a semi-quantitative grading system. The main items of interest were polyethylene (PE) particles, metal particles, histiocytes, and giant cells. RESULTS: All cyst samples contained PE particles. A similar number of PE particles were found in talar and tibial cysts. No significant correlation between the number of PE particles and time to reoperation was found. Metal particles were found in 16 cysts. CONCLUSIONS: We suggest that PE particles are not the primary cause of osteolytic cyst formation but a secondary contributing factor probably accelerating the process of osteolysis. It is likely that implant design, biomechanical factors and local anatomic-physiological factors play an important role.

Management of extensive talar osteolysis with Agility™ total ankle replacement systems using geometric metal-reinforced polymethylmethacrylate cement augmentation.

The Agility™ Total Ankle Replacement System, almost exclusively without polymethylmethacrylate cement fixation, was the most commonly used implant in the United States from 1998 to 2007. Much attention has been given to the intraoperative complications and incision healing-related problems. However, it is the intermediate- and long-term complications, specifically, aseptic osteolysis, talar component loosening, subsidence, and progressive malalignment, that require careful consideration, because the revision options are limited. We describe a technique for management of extensive talar aseptic osteolysis for revision of Agility™ total ankle replacement systems with use of geometric metal-reinforced polymethylmethacrylate cement augmentation. This technique preserves the subtalar joint, provides immediate component stability and restoration of component alignment and height, and is a cost-effective alternative to other available options and still allows for additional revision should late failure occur.

Demineralized bone matrix and platelet-rich plasma do not improve healing of osteochondral defects of the talus: an experimental goat study.

OBJECTIVE: The purpose of this study was to evaluate the effectiveness of demineralized bone matrix (DBM) with and without platelet-rich plasma (PRP) in the treatment of osteochondral defects (OCDs) of the talus. We hypothesized that treatment with DBM would result in more bone formation than no treatment in control OCDs, and that PRP would further enhance the regenerative capacity of DBM. METHOD: A standardized 6-mm OCD was created in each talus of 16 adult goats. According to a randomization scheme, one OCD of each goat was treated with allogeneic DBM hydrated with normal saline (n = 8) or hydrated with autologous PRP (n = 8). The contralateral OCD (n = 16) served as control. After 24 weeks, the animals were euthanized and the tali excised. Various outcome parameters were analyzed with use of macroscopic evaluation, micro-computed tomography (µCT), histology, histomorphometry, and fluorescence microscopy. RESULTS: None of the analyses revealed statistically significant differences between the groups for any of the parameters analyzed in any volume of interest. For example, the mean bone volume fraction (BV/TV) of the defect, as measured by µCT, was 0.56 (95% confidence interval [CI], 0.44-0.68) for DBM hydrated with normal saline and 0.52 (95% CI, 0.40-0.65) for DBM hydrated with PRP, compared to 0.53 (95% CI, 0.45-0.61) and 0.54 (95% CI, 0.44-0.64) for the internal controls, respectively (P > 0.05). CONCLUSION: In contrast to our hypotheses, no beneficial treatment effect of DBM with or without PRP was found for OCDs of the caprine talus.

Use of allograft cellular bone matrix in multistage talectomy with tibiocalcaneal arthrodesis: a case report.

Surgical treatment for traumatic dislocation of the talus is a challenging procedure that is often associated with complications. Application of allograft cellular bone matrix with viable mesenchymal stem and osteoprogenitor cells can eliminate the need for autograft and may increase fusion rates in procedures such as tibiocalcaneal arthrodesis. This report describes the treatment of an adult man who presented with a right ankle fracture and subtalar joint dislocation after a motor vehicle accident. After initial treatment with open reduction and internal fixation, the patient developed avascular necrosis of the talus and septic arthritis of the tibiotalar and subtalar joints. After treatment of the infection, the patient was ultimately treated with multistage talectomy and tibiocalcaneal arthrodesis augmented with a cellular bone allograft. Approximately 3 months after the final operation, plain radiographs and computed tomography confirmed solid fusion at the arthrodesis interface. The patient's recovery was uneventful thereafter, and amputation was avoided. This case, which presented additional challenges because of the large defect created by the infection, suggests that use of an allograft cellular bone matrix has the potential to replicate the bone-healing properties of autograft without the constraints and morbidity associated with autograft harvesting.

Autologous matrix-induced chondrogenesis aided reconstruction of a large focal osteochondral lesion of the talus.

The aim of this case report is to describe a novel technique for treatment of large osteochondral lesions of the talus using autologous matrix-induced chondrogenesis with a collagen I/III membrane.

Metal-reinforced cement augmentation for complex talar subsidence in failed total ankle arthroplasty.

There are limited options for failed total ankle arthroplasty (TAA) with major talar bone loss and component subsidence. Surgical options for this condition include revision arthroplasty, salvage arthrodesis, or amputation. Revision arthroplasty generally has been considered in situations of loose components with minimal bone loss or use of expensive custom-fabricated prosthetic components with elongated stems. Historically, failure that involves major talar bone loss has been considered resistant to reconstruction, and responsive only to complex arthrodesis or amputation. In this report, we describe a unique method of restoring talar support and preserving ankle function after failed TAA with major talar bone loss and component subsidence. Talar reconstruction using metal-reinforced bone cement augmentation is combined with the Inbone (Wright Medical Technology, Inc., Arlington, TN) total ankle system to restore talar height and ligamentous support. This technique has been used successfully in the last 4 years for various patterns of talar bone loss and obviates the need for custom components. When successfully performed, the revision technique results in restoration of mechanical alignment, anatomic height, and component support, in addition to providing substantial symptomatic relief.

Novel metallic implantation technique for osteochondral defects of the medial talar dome. A cadaver study.

BACKGROUND AND PURPOSE: A metallic inlay implant (HemiCAP) with 15 offset sizes has been developed for the treatment of localized osteochondral defects of the medial talar dome. The aim of this study was to test the following hypotheses: (1) a matching offset size is available for each talus, (2) the prosthetic device can be reproducibly implanted slightly recessed in relation to the talar cartilage level, and (3) with this implantation level, excessive contact pressures on the opposite tibial cartilage are avoided. METHODS: The prosthetic device was implanted in 11 intact fresh-frozen human cadaver ankles, aiming its surface 0.5 mm below cartilage level. The implantation level was measured at 4 margins of each implant. Intraarticular contact pressures were measured before and after implantation, with compressive forces of 1,000-2,000 N and the ankle joint in plantigrade position, 10 dorsiflexion, and 14 plantar flexion. RESULTS: There was a matching offset size available for each specimen. The mean implantation level was 0.45 (SD 0.18) mm below the cartilage surface. The defect area accounted for a median of 3% (0.02-18) of the total ankle contact pressure before implantation. This was reduced to 0.1% (0.02-13) after prosthetic implantation. INTERPRETATION: These results suggest that the implant can be applied clinically in a safe way, with appropriate offset sizes for various talar domes and without excessive pressure on the opposite cartilage.

Giant Cell Tumor of Bone in the Talus Treated by Extended Curettage and Synthetic Bone SubstituteReport of a Rare Case.

Giant cell tumor of bone is extremely rare in the talus and is usually observed in the third decade of life. Herein, we report a case of a 19-year-old male with a giant cell tumor of bone in the talus mimicking a simple bone cyst that was treated by intralesional curettage and, for the first time, bone grafting with a synthetic bone substitute. The patient had no evidence of recurrence at 7-year follow-up but did have non-progressing mild degenerative joint disease and slightly limited range of movement at the ankle joint.

Fatty metamorphosis and other patterns in fibrous dysplasia.

BACKGROUND: Interpretation of small biopsy fragments from suspected lesions of fibrous dysplasia with unusual clinical and/or radiological features may be challenging due to wide histomorphological spectrum of stromal appearances. Awareness of these variations should improve diagnostic confidence. METHODS: We retrospectively studied 26 cases of fibrous dysplasia (F- 19, M- 7; Ages ranged from 10 to 53 years) with confirmed diagnosis. The sites of the lesions were skull bones (9), humerus (1), femur (8), tibia (2), fibula (3), talus (1), mandible (1), and maxilla (1). RESULTS: Different stromal patterns, variably admixed with the classical pattern, were observed in 58%(15/26) of the cases. 20%(3/15) of these had more than one pattern. Focal fatty metamorphosis as groups of fat cells in the central portion of the lesion in the stroma of fibrous dysplasia between osseous trabeculae was observed in 23%(6/26) cases. Other patterns included myxoid stroma in 16%(4/26), collagenization of stroma in 12%(3/26), stroma rich pattern (with paucity of trabeculae) in 12%(3/26), foci of few foam cells in 23% (6/26), and calcified spherules in 12%(3/26). Focal osteoblastic rimming of trabeculae was observed only in 4%(1/26). CONCLUSIONS: Various stromal variations and previously unreported fatty metamorphosis were frequently observed in fibrous dysplasia.

[Refixation of osteochondral fragments using absorbable implants. First results of a retrospective study]. / Refixation osteochondraler Fragmente mit resorbierbaren Implantaten. Erste Ergebnisse einer retrospektiven Studie.

An osteochondral lesion in a weight bearing joint causes therapeutic problems. Surgical therapy focuses on the restoration of the articular surface, unlimited motion of the joint and prevention of cartilaginous degeneration. A causal therapy to prevent posttraumatic osteoarthritis is the fixation of osteochondral fragments. Various absorbable implants for the purpose of refixation are available, but only a few have proved to be biocompatible. This retrospective study presents the preliminary results after refixation of osteochondral fragments of the ankle and knee joints. We used self-reinforced absorbable pins, nails and screws made of polylactide acid. The results for 15 patients with 17 fractures of 16 joints were evaluated. All patients were scored by the Tegner-activity-level, the McDermott-score and the DGKKT-score, and 13 of them were monitored by postoperative magnetic resonance imaging (MRI). The follow-up extended for an average of 14.3 months (range: 4-43 months). The clinical results for all patients were good (McDermott-score: Ø 89 points, DGKKT-score: Ø 78.8 points, Tegner: pre-op vs post-op=Ø 4.6 vs Ø 5.1) and the surgical therapy proved to be successful. The MRI showed the complete incorporation and vitality of the fragment as well as a congruence of the joint surface. The clinical course and the MRI gave little reference to an inflammatory reaction due to the implants that complicated the course of two patients. These results indicate that absorbable implants made of polylactide acid are biocompatible and effective in the fixation of osteochondral fragments.

Osteochondral defects of the talus: a novel animal model in the goat.

Osteochondral defects of the talus pose a difficult therapeutic challenge. An experimental animal model of the ankle joint is not available. The aim of this study was to test a newly developed animal model for osteochondral defects of the ankle in vivo. Osteochondral defects were created in the talus of goat hind legs using a posterolateral surgical approach. The defects were filled with either autologous cancellous bone or donor demineralized bone matrix or left empty as control. After 12 weeks of healing, the specimens were analyzed with radiography, macroscopy, microcomputed tomography, histology, histomorphometry, and fluorescence microscopy. It was possible to create a standardized defect in each talus. The implanted material remained in place. The analyses showed that most bony tissue was generated in the defects filled with autologous bone and least in the control defects. Our findings show that a standard osteochondral defect can be created in the talus by a relatively simple procedure in a large animal that allows qualitative and quantitative evaluation. The model can be used in future experiments to investigate alternative treatment methods before they are introduced into clinical practice.

The treatment effect of porous titanium alloy rod on the early stage talar osteonecrosis of sheep.

Osteonecrosis of the talus (ONT) may severely affect the function of the ankle joint. Most orthopedists believe that ONT should be treated at an early stage, but a concise and effective surgical treatment is lacking. In this study, porous titanium alloy rods were prepared and implanted into the tali of sheep with early-stage ONT (IM group). The curative effect of the rods was compared to treatment by core decompression (DC group). No significant differences in bone reconstruction were observed between the two groups at 1 month after intervention. After 3 months, the macroscopic view of gross specimens of the IM group showed ordinary contours, but the specimens of the DC group showed obvious partial bone defects and cartilage degeneration. Quantitative analysis of the reconstructed trabeculae by micro-CT and histological study suggested that the curative effect of the IM group was superior to that of the DC group at 3 months after intervention. These favorable short-term results of the implantation of porous titanium alloy rods into the tali of sheep with early-stage ONT may provide insight into an innovative surgical treatment for ONT.

Failure of the Agility total ankle replacement system and the salvage options.

The Agility total ankle replacement system was the most commonly performed implant in the United States for more than 20 years and has undergone four generations and seven phases of improvement. Much attention has been placed on intraoperative complications, such as malleolar fracture; nerve or tendon injury; and incision healing-related problems, such as wound coverage and infection. However, it is the intermediate- and long-term complications (ie, aseptic osteolysis, subsidence, component loosening, and progressive malalignment) that require careful consideration, because the revision options remain limited. This article reviews the history of the Agility total ankle replacement system in detail, to understand the revision possibilities available.