Current concepts and techniques in posttraumatic arthritis

Peculiarities in Ankle Cartilage

Posttraumatic osteoarthritis (PTOA) is the most common form of osteoarthritis (OA) of the ankle joint. PTOA occurs as a result of several factors, including the poor regenerative capacity of hyaline articular cartilage as well as increased contact stresses following trauma. The purpose of this article is to review the epidemiology, pathogenesis, and potential targets for treatment of PTOA in the ankle joint. Previous reviews primarily addressed clinical approaches to ankle PTOA, while the focus of the current article will be specifically on the newly acquired knowledge of the cellular mechanisms that drive PTOA in the ankle joint and means for potential targeted therapeutics that might halt the progression of cartilage degeneration and/or improve the outcome of surgical interventions. Three experimental treatment strategies are discussed in this review: (1) increasing the anabolic potential of chondrocytes through treatment with growth factors such as bone morphogenetic protein-7; (2) limiting chondrocyte cell death either through the protection of cell membrane with poloxamer 188 or inhibiting activity of intracellular proteases, caspases, which are responsible for cell death by apoptosis; and (3) inhibiting catabolic/inflammatory responses of chondrocytes by treating them with anti-inflammatory agents such as tumor necrosis factor-α antagonists. Future studies should focus on identifying the appropriate timing for treatment and an appropriate combination of anti-inflammatory, chondro- and matrix-protective biologics to limit the progression of trauma-induced cartilage degeneration and prevent the development of PTOA in the ankle joint.

Dimensionality of measures for severe unilateral ankle arthritis

OBJECTIVE

To analyze the dimensionality of 2 self-report outcome measures (Foot/Ankle Disability Index [FADI] and Short-Form [SF]-36), 3 biomechanical measures (stance and step symmetry measures, gait speed, and step width), 2 physical-performance measures (timed get-up and go [TUG] and 4-square step test [4SST]), and 1 clinician-report outcome measure (American Orthopaedic Foot and Ankle Society [AOFAS] Hindfoot Scale) in a patient population with unilateral ankle arthritis. These measures captured the following functions: mobility and speed, pain and its relationship to function, social integration, and symmetry and efficiency of gait.

DESIGN

Case series design.

SETTING

Biomechanical research laboratory adjacent to a busy orthopedic clinical practice.

PATIENTS

Seventy-nine consecutive patients with unilateral traumatic arthritis who were candidates for a total ankle replacement.

METHODS

An exploratory factor analysis with oblimin rotation was performed to determine the dimensions of the physical performance, biomechanical, self-report, and clinician-report measures.

MAIN OUTCOME MEASUREMENTS

Outcomes measures included the SF-36 and pertinent subscales, gait speed, the 4SST, the TUG, the FADI, the AOFAS Hindfoot Scale, and biomechanical measures of step width, step symmetry, and stance symmetry.

RESULTS

Four distinct dimensions were captured during factor analysis. Factor 1 included the TUG, gait speed, the 4SST, and step width; factor 2 included the FADI, the SF-36 bodily pain score, and the SF-36 physical function score; factor 3 included the biomechanical scores of stance symmetry ratio and the step symmetry ratio; and factor 4 included SF-36 social functioning and the AOFAS Hindfoot Scale.

CONCLUSIONS

Findings suggest that various outcome measures for the ankle capture different dimensions and should be considered when evaluating the presence of disability or long-term change in outcome.

Tissue engineering of bone: material and matrix considerations

When the normal physiologic reaction to fracture does not occur, such as in fracture nonunions or large-scale traumatic bone injury, surgical intervention is warranted. Autografts and allografts represent current strategies for surgical intervention and subsequent bone repair, but each possesses limitations, such as donor-site morbidity with the use of autograft and the risk of disease transmission with the use of allograft. Synthetic bone-graft substitutes, developed in an effort to overcome the inherent limitations of autograft and allograft, represent an alternative strategy. These synthetic graft substitutes, or matrices, are formed from a variety of materials, including natural and synthetic polymers, ceramics, and composites, that are designed to mimic the three-dimensional characteristics of autograft tissue while maintaining viable cell populations. Matrices also act as delivery vehicles for factors, antibiotics, and chemotherapeutic agents, depending on the nature of the injury to be repaired. This intersection of matrices, cells, and therapeutic molecules has collectively been termed tissue engineering. Depending on the specific application of the matrix, certain materials may be more or less well suited to the final structure; these include polymers, ceramics, and composites of the two. Each category is represented by matrices that can form either solid preformed structures or injectable forms that harden in situ. This article discusses the myriad design considerations that are relevant to successful bone repair with tissue-engineered matrices and provides an overview of several manufacturing techniques that allow for the actualization of critical design parameters.