JAAOS

JAAOS, Volume 6, No. 4


Alternative bearing surfaces for total joint arthroplasty.

The biologic response to polyethylene particulate debris generated from metal-on-polyethylene bearing surfaces is thought to be largely responsible for periprosthetic osteolysis and aseptic loosening in total joint arthroplasty. As a result, there has been an interest in developing polyethylene with improved wear characteristics, as well as a renewed interest in alternative bearing surfaces for total joint arthroplasty, including ceramic-polyethylene, metal-metal, and ceramic-ceramic articulations. These alternative surfaces have demonstrated less friction and lower wear rates than metal-on-polyethylene bearing surfaces in both clinical and laboratory experiments. Clinical results, although only short- to mid-term, have been encouraging. Alternative bearing surfaces, with lower wear rates and less particulate debris formation, may have the potential to improve total joint arthroplasty survivorship by decreasing periprosthetic osteolysis, especially in younger, high-demand patients.

    • Keywords:
    • Arthroplasty

    • Replacement

    • Hip|Arthroplasty

    • Knee|Biocompatible Materials|Ceramics|Chromium Alloys|Hip Prosthesis|Humans|Knee Prosthesis|Osteolysis|Polyethylenes|Prosthesis Design|Prosthesis Failure

    • Subspecialty:
    • Adult Reconstruction

    • Basic Science

Arthroscopic management of rotator cuff disease.

Rotator cuff disease (stage 2 impingement, partial-thickness tears, complete cuff tears, and irreparable tears) is as yet only partially understood, and the role of arthroscopy in its management is still under debate. Stage 2 impingement can be managed satisfactorily with arthroscopic techniques. Arthroscopy allows a complete inspection of the glenohumeral joint, enabling the surgeon to diagnose and treat coexisting intra-articular lesions. A thorough bursectomy, coracoacromial ligament resection, and acromioplasty can be performed without the need for deltoid detachment. Arthroscopic technique appears to offer advantages over open technique in the management of partial-thickness tears by allowing accurate inspection of the articular surface of the rotator cuff. The depth and size of the tear can be determined precisely, allowing an appropriate selection of debridement, decompression, and/or tendon repair. The management of complete tears is currently under investigation, with some advocating complete arthroscopic repair and some preferring arthroscopic acromioplasty and "mini-open" repair; there are merits to both approaches. The arthroscopic management of irreparable tears appears to offer the advantages of an open decompression with decreased morbidity. However, the surgeon's ability to accurately determine reparability may be less precise with arthroscopy.

    • Keywords:
    • Arthroscopy|Endoscopes|Humans|Joint Diseases|Rotator Cuff

    • Subspecialty:
    • Shoulder and Elbow

Cervical spine disorders in infants and children.

The evaluation of children with cervical spine disorders requires an understanding of the anatomic and developmental features that are particular to the pediatric spine. In this article, cervical spine developmental anatomy is briefly reviewed, along with common radiographic features of the pediatric cervical spine. The epidemiology, clinical presentation, and management of congenital cervical anomalies are considered. The evaluation and management of pediatric cervical trauma are also reviewed. Other disorders with common cervical spine involvement, such as skeletal dysplasias, connective tissue disorders, inflammatory arthritides, and storage disorders, are discussed.

    • Keywords:
    • Cervical Vertebrae|Child|Child

    • Preschool|Humans|Infant|Spinal Diseases|Spinal Injuries|Spine

    • Subspecialty:
    • Pediatric Orthopaedics

    • Spine

Hamstring strains in athletes: diagnosis and treatment.

Hamstring strains are among the most common injuries (and reinjuries) in athletes. Studies combining electromyography with gait analysis have elucidated the timing of activity of the three muscles of the hamstring group; they function during the early-stance phase for knee support, during the late-stance phase for propulsion, and during midswing to control the momentum of the leg. Muscle injury, whether partial or complete, occurs at the myotendinous junction, where force is concentrated. The healing response begins with inflammation, associated edema, and localized hemorrhage. After an initial period of reduced tension, the healing muscle regains strength rapidly as long as reinjury does not occur. Although the use of anti-inflammatory medication is a keystone of treatment, a certain degree of inflammation is necessary for removing necrotic muscle fibers and rescaffolding to allow optimal recovery. The protocol of rest, ice, compression, and elevation is still the preferred first-aid approach. After a brief period of immobilization (usually less than 1 week for even the most severe strain), mobilization is begun to properly align the regenerating muscle fibers and limit the extent of connective tissue fibrosis. Concurrent pain-free stretching and strengthening exercises (beginning with isometrics and progressing to isotonics and isokinetics) are essential to regain flexibility and prevent further injury and inflammation. Readiness for return to competition can be assessed by isokinetic testing to confirm that muscle-strength imbalances have been corrected, the hamstring-quadriceps ratio is 50% to 60%, and the strength of the injured leg has been restored to within 10% of that of the unaffected leg. The only indication for surgery is a complete rupture at or near the origin from the ischial tuberosity or distally at its insertion (either soft-tissue avulsion with a large defect or bone avulsion with displacement by 2 cm).

    • Keywords:
    • Athletic Injuries|Clinical Protocols|Humans|Leg Injuries|Muscle

    • Skeletal|Sprains and Strains

    • Subspecialty:
    • Sports Medicine

Injuries to the midtarsal joint and lesser tarsal bones.

Injuries to the midtarsal joint and lesser tarsal bones occur relatively infrequently and often present with a benign appearance on imaging studies. These facts may lead to failure of diagnosis and/or inadequate and improper treatment, with subsequent disability for the patient. The clinician with a general knowledge of the various injury patterns to the midfoot is able to approach these injuries rationally and with an appreciation of their potential severity. This article reviews the mechanism, clinical and radiologic presentation, and treatment of midtarsal joint injuries and midfoot fractures.

    • Keywords:
    • Dislocations|Foot Injuries|Fractures

    • Bone|Humans|Tarsal Bones|Tarsal Joints

    • Subspecialty:
    • Trauma

    • Foot and Ankle

Monteggia fractures in children and adults.

The eponymous term "Monteggia fracture" is most precisely used to refer to dislocation of the proximal radioulnar joint in association with a forearm fracture. It is the character of the ulnar fracture, rather than the direction of radial head dislocation, that is useful in determining the optimal treatment of Monteggia fractures in both children and adults. Stable anatomic reduction of the ulnar fracture results in anatomic reduction of the radial head. The notoriously poor results of treatment of Monteggia fractures in adults improved dramatically after the development of modern techniques of plate-and-screw fixation, which facilitate early mobilization by ensuring anatomic reduction. The relatively good results associated with nonoperative treatment of pediatric Monteggia injuries reflect the prevalence of stable (incomplete) fractures in children. Unstable (complete) ulnar fractures are prone to residual or recurrent displacement and may require operative fixation. Late reconstruction of chronic Monteggia lesions in children can be complicated and unpredictable. The key to a good outcome after a Monteggia-type fracture-dislocation of the forearm remains early recognition of proximal radioulnar dissociation.

    • Keywords:
    • Adult|Child|Fracture Fixation|Humans|Monteggias Fracture|Radius|Ulna

    • Subspecialty:
    • Trauma

    • Pediatric Orthopaedics

Osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is a genetically determined disorder of connective tissue characterized by bone fragility. The disease state encompasses a phenotypically and genotypically heterogeneous group of inherited disorders that result from mutations in the genes that code for type I collagen. The disorder is manifest in tissues in which the principal matrix protein is type I collagen (mainly bone, dentin, sclerae, and ligaments). Musculoskeletal manifestations are variable in severity along a continuum ranging from perinatal lethal forms with crumpled bones to moderate forms with deformity and propensity to fracture to clinically silent forms with subtle osteopenia and no deformity. The differential diagnosis includes other entities with multiple fractures, deformities, and osteopenia. Classification is based on the timing of fractures or on multiple clinical, genetic, and radiologic features. Molecular genetic studies have identified more than 150 mutations of the COL1A1 and COL1A2 genes, which encode for type I procollagen. Various systemic treatments have been attempted; however, these interventions have been ineffective or inconclusive or are still experimental. Gene therapy has the potential to increase the synthesis of type I collagen in mild variants and to correct mutations in severe variants, but there are a great number of technical difficulties to overcome. The goals of treatment of OI are to maximize function, minimize deformity and disability, maintain comfort, achieve relative independence in activities of daily living, and enhance social integration. Attainment of these goals requires a team approach to tailor treatment needs to the severity of the disease and the age of the patient. Nonoperative management is the mainstay of orthopaedic treatment, with the goals of preventing and treating fractures and enhancing locomotion. Operative intervention is indicated for recurrent fractures or deformity that impairs function.

    • Keywords:
    • Chromosomes

    • Human

    • Pair 17|Chromosomes

    • Pair 7|Collagen|Humans|Mutation|Osteogenesis Imperfecta

    • Subspecialty:
    • Pediatric Orthopaedics

    • General Orthopaedics

    • Basic Science

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