JAAOS

JAAOS, Volume 17, No. 2


Ceramic materials as bearing surfaces for total hip arthroplasty.

During the past decade, advances in total hip arthroplasty component design have produced implants with reliable clinical results in regard to fixation. The foremost unresolved challenge has been the development of bearing surfaces that can withstand the higher demands of younger and more active patients. New alternative bearings with superior wear characteristics that minimize debris include ceramic-on-ceramic, metal-on-metal, and highly cross-linked polyethylenes in combination with ceramic or metal. Alumina-on-alumina ceramic bearings are extremely hard and scratch resistant and provide superior lubrication and wear resistance compared with other bearing surfaces in clinical use. Survivorship revision for any reason for the alumina ceramic bearings at 10 years was significantly higher compared with metal-on-polyethylene. Bearings currently being studied because of their encouraging wear performance in the laboratory are an alumina matrix (82% alumina, 17% zirconia, 0.3% chromium oxide), zirconium oxide, and ceramic-on-cobalt-chromium.

    • Keywords:
    • Age Factors|Aluminum Oxide|Arthroplasty

    • Replacement

    • Hip|Ceramics|Chromium Alloys|Equipment Failure|Hip Prosthesis|Humans|Metals|Motor Activity|Noise|Polyethylene|Zirconium

    • Subspecialty:
    • Adult Reconstruction

    • Basic Science

Management of symptomatic lumbar degenerative disk disease.

Symptomatic lumbar degenerative disk disease, or discogenic back pain, is difficult to treat. Patients often report transverse low back pain that radiates into the sacroiliac joints. Radicular or claudicatory symptoms are generally absent unless there is concomitant nerve compression. Physical examination findings are often unremarkable. Radiographic examination may reveal disk space narrowing, end-plate sclerosis, or vacuum phenomenon in the disk; magnetic resonance imaging is useful for revealing hydration of the disk, annular bulging, or lumbar spine end-plate (Modic) changes in the adjacent vertebral bodies. The use of diskography as a confirmatory study remains controversial. Recent prospective, randomized trials and meta-analyses of the literature have helped expand what is known about degenerative disk disease. In most patients with low back pain, symptoms resolve without surgical intervention; physical therapy and nonsteroidal anti-inflammatory drugs are the cornerstones of nonsurgical treatment. Intradiskal electrothermal treatment has not been shown to be effective, and arthrodesis remains controversial for the treatment of discogenic back pain. Nucleus replacement and motion-sparing technology are too new to have demonstrated long-term data regarding their efficacy.

    • Keywords:
    • Anti-Inflammatory Agents

    • Non-Steroidal|Arthroplasty|Humans|Intervertebral Disk|Lumbar Vertebrae|Physical Therapy Modalities|Spinal Diseases|Spinal Fusion

    • Subspecialty:
    • Spine

    • Pain Management

Management of the posttraumatic arthritic knee.

Excellent long-term outcomes can be achieved with contemporary methods of ligament reconstruction and open reduction and internal fixation for injuries around the knee; nevertheless, posttraumatic arthritis frequently develops. Reconstruction options for symptomatic posttraumatic knee arthritis include osteotomy, arthrodesis, and arthroplasty. Surgical challenges include the presence of extensive (often broken) hardware, scarring, stiffness, bony defects, compromised soft tissues, and malalignment. Patient age and activity and the anatomic location and extent of damage to the articular surface must be taken into account when determining the surgical treatment plan. For younger patients, osteotomy, allograft transplantation, or arthrodesis of the knee is considered, whereas older, low-demand patients are usually treated with arthroplasty. Attention to specific technical details and careful surgical technique are necessary to achieve a successful result. Functional improvement is usually seen following arthroplasty and, sometimes, arthrodesis. However, complications are common, and outcomes following arthroplasty are generally inferior to those reported for other diagnoses.

    • Keywords:
    • Arthritis|Arthrodesis|Arthroplasty

    • Replacement

    • Knee|Cartilage

    • Articular|Humans|Knee Injuries|Osteotomy|Treatment Outcome

    • Subspecialty:
    • Adult Reconstruction

Metal-on-metal bearing surfaces.

Metal-on-metal bearing couples remain a popular option in total hip arthroplasty and are the only currently available option for surface replacement arthroplasty. In general, the intermediate-term clinical performance of metal-on-metal bearings has been favorable. There are, however, lingering concerns about the biologic consequences of metal release from these bearings in terms of both local tissue effects, including delayed-type hypersensitivity reactions in a subset of patients, and potential systemic effects as a consequence of chronic elevations in serum cobalt and chromium content. Advances in the understanding of the operant wear mechanisms in these bearings provide strategies for reducing the burden of metal released into the periprosthetic milieu, which in turn will mitigate the concerns about the biologic response to the metal debris. Continued surveillance of patients with these bearings is warranted to determine whether metal-on-metal bearing couples provide a long-term survivorship advantage over other bearing couple options and to evaluate whether chronic elevations in the body burden of cobalt and chromium is well tolerated over the long term.

    • Keywords:
    • Arthroplasty

    • Replacement

    • Hip|Chromium|Chromium Compounds|Cobalt|Hip Prosthesis|Humans|Hypersensitivity

    • Delayed|Metals|Phosphates|Polyethylene

    • Subspecialty:
    • Adult Reconstruction

    • Basic Science

Orthopaedic conditions in the newborn.

The occasional consultation on a neonate can be unfamiliar territory for many orthopaedic surgeons. Just as children are not little adults, newborns are not just little children; rather, they have a unique physiology that affects the presentation of their orthopaedic concerns. Careful physical examination with appropriate understanding of neonatal development is essential to making the proper diagnosis. A flail extremity in the newborn is most commonly attributed to fracture or brachial plexus palsy; however, infection must also be considered and ruled out to prevent long-term morbidity. Metatarsus adductus is the most common foot abnormality, but clubfoot, calcaneovalgus deformity, and congenital vertical talus may also be encountered. Joint contractures that spontaneously improve are normal in the newborn, but it is important to identify and institute proper treatment for early developmental dysplasia of the hip, congenital knee dislocation, and torticollis. Clavicular pseudarthrosis and periosteal reactions may be discovered on radiographic examination. A basic understanding of the relevant conditions will help the orthopaedist with the initial diagnosis and management of orthopaedic issues in the newborn.

    • Keywords:
    • Bone Diseases|Contracture|Dislocations|Foot Deformities

    • Congenital|Fractures

    • Bone|Humans|Infant|Infant

    • Newborn|Orthopedic Procedures

    • Subspecialty:
    • Pediatric Orthopaedics

Pediatric scaphoid fractures.

Fractures of the immature carpal scaphoid can be challenging to manage. The diagnosis may be missed or delayed because of absent or minimal symptoms. Once diagnosed, most pediatric scaphoid fractures can be successfully treated with cast immobilization. However, this is inadequate for difficult and unique cases. Nonunion may occur as a result of a missed diagnosis or delayed presentation as well as in patients who receive appropriate treatment. Because the natural history in children remains incompletely characterized, the optimal treatment of established pediatric scaphoid nonunions is controversial. Surgical intervention should be considered for displaced fractures in patients who are at or near skeletal maturity or in those in whom nonsurgical treatment has failed.

    • Keywords:
    • Adolescent|Biomechanics|Casts

    • Surgical|Child|Child

    • Preschool|Female|Fractures

    • Bone|Fractures

    • Malunited|Humans|Immobilization|Male|Postoperative Complications|Scaphoid Bone

    • Subspecialty:
    • Trauma

    • Pediatric Orthopaedics

    • Hand and Wrist

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