Osteotomies of the Talar Neck for Posttraumatic Malalignment

A talar neck malunion is one of the major complications following operative or nonoperative treatment of talar neck fractures. The most common posttraumatic talar malunion results in varus malalignment of the talar neck and can lead to painful overload of the lateral foot and substantial impairment of hindfoot function. Secondary procedures in patients with painful malunited talar neck fracture include salvage procedures and anatomic reconstruction procedures. Anatomic reconstruction of the talar neck is a reliable surgical treatment to regain function, decrease pain, and restore hindfoot alignment and range of motion.

Increased Osseous (99m)Tc-DPD Uptake in End-Stage Ankle Osteoarthritis: Correlation Between SPECT-CT Imaging and Histologic Findings

BACKGROUND

We analyzed the histopathologic findings in end-stage osteoarthritic ankle joint tissue that display increased uptake of bone-seeking radiotracer in single-photon emission computed tomography-computed tomography (SPECT-CT) imaging.

METHODS

Six consecutive patients with end-stage osteoarthritis undergoing total ankle replacement received preoperative SPECT-CT imaging using (99m)Technetium dicarboxypropane diphosphonate ((99m)Tc-DPD). Using imaging data for stratification, osteochondral tissue sections were prepared from SPECT-positive (+) and -negative (-) areas of tibial and talar resection specimens. Histomorphometric analyses of osteoblast numbers, collagen deposition, and cartilage degeneration were performed on hematoxylin and eosin, van Gieson's and Safranin-O stained tissue sections. Osteoclast activity was visualized using tartrate-resistant acid phosphatase (TRAP) staining.

RESULTS

Increased (99m)Tc-DPD uptake was observed exclusively subjacent to the subchondral bone plate of tibial and talar joint compartments. SPECT(-) tissues displayed typical fatty marrow morphology containing mainly collagen-positive blood vessels and few marrow and bone-lining cells. SPECT(+) tissues were characterized by increased numbers of active bone-lining osteoblasts depositing collagen fibers. Collagen area fraction of subchondral bone marrow was significantly increased in SPECT(+) (0.52 ± 0.21) compared with SPECT(-) (0.29 ± 0.13) tissues (P = .30). Multinucleated TRAP(+) osteoclasts were absent from bone formation sites, but associated with vascular structures invading articular cartilage through the subchondral bone plate. Increased (99m)Tc-DPD uptake was specifically and strongly correlated with increased osteoblast numbers (P = .011), and with collagen area fraction (P = .030) but not with Mankin score (P = .202), or with osteoclast number (P = .576).

CONCLUSION

Subchondral bone tissues in SPECT(+) areas of end-stage ankle osteoarthritis were histologically characterized by increased osteoblast-mediated bone formation in the absence of functional osteoclasts, and increased cellularity and collagen deposition in marrow tissues.

CLINICAL SIGNIFICANCE

Our findings suggest a pathologic bone-remodeling process in end-stage ankle OA areas with increased (99m)Tc-DPD uptake.

Intraoperative and perioperative complications during revision arthroplasty for salvage of a failed total ankle arthroplasty

BACKGROUND

Revision of a failed total ankle arthroplasty (TAA) remains a challenge. Advances in total ankle implant design have renewed interest in revision TAA as an alternative to ankle arthrodesis or amputation in the management of a failed TAA. The purpose of our study was to review a series of failed Agility TAA revised to INBONE II TAA and identify reasons for revision as well as perioperative complications.

METHODS

A retrospective review of 35 cases of failed Agility TAA revised to an INBONE II TAA was performed at 1 institution. Patient demographics, indications for revision, radiographs, and complications were reviewed. The average follow-up was 9.1 months (range, 0-28 months). All revisions were performed by 1 of 2 foot and ankle surgeons familiar with both prostheses.

RESULTS

The Agility TAA lasted a mean of 6.7 years prior to revision to an INBONE II TAA. Revision TAA was indicated due to mechanical loosening, osteolysis, periprosthetic fracture, and a dislocated prosthesis. Adjunctive procedures were performed in 31 of 35 cases. There were 6 intraoperative and 5 acute postoperative complications, leading to an overall 31.4% complication rate. There was 1 patient with continued pain postoperatively who underwent a second revision of the INBONE II 20 months postoperatively.

CONCLUSION

Revision TAA was a viable treatment option for failed TAA. A high risk of perioperative complications remains, and physicians should be aware of the challenges that occur during these procedures in order to plan for them preoperatively.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

A vectored measles virus induces hepatitis B surface antigen antibodies while protecting macaques against measles virus challenge

Hepatitis B virus (HBV) acute and chronic infections remain a major worldwide health problem. Towards developing an anti-HBV vaccine with single-dose scheme potential, we engineered infectious measles virus (MV) genomic cDNAs with a vaccine strain background and expression vector properties. Hepatitis B surface antigen (HBsAg) expression cassettes were inserted into this cDNA and three MVs expressing HBsAg at different levels generated. All vectored MVs, which secrete HBsAg as subviral particles, elicited humoral responses in MV-susceptible genetically modified mice. However, small differences in HBsAg expression elicited vastly different HBsAg antibody levels. The two vectors inducing the highest HBsAg antibody levels were inoculated into rhesus monkeys (Macaca mulatta). After challenge with a pathogenic MV strain (Davis87), control naive monkeys showed a classic measles rash and high viral loads. In contrast, all monkeys immunized with vaccine or a control nonvectored recombinant vaccine or HBsAg-expressing vectored MV remained healthy, with low or undetectable viral loads. After a single vaccine dose, only the vector expressing HBsAg at the highest levels elicited protective levels of HBsAg antibodies in two of four animals. These observations reveal an expression threshold for efficient induction of HBsAg humoral immune responses. This threshold is lower in mice than in macaques. Implications for the development of divalent vaccines based on live attenuated viruses are discussed.