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The treatment of focal full thickness articular defects in the knee has continued to present a challenge, with no traditional treatment method providing consistent acceptable long-term clinical results. Patients with significant chondral defects frequently have persistent joint line pain, swelling, and catching in the knee. In contrast to marrow stimulation treatment techniques, such as abrasion arthroplasty, drilling, or microfracture which populate the defect with pluripotential stem cells, the use of cultured autologous chondrocytes fills the defect with cells of a committed pathway to develop hyaline-like cartilage. This hyaline-like cartilage more closely recreates the wear characteristics and durability of normal hyaline cartilage than the fibrous or fibrocartilage repair tissue formed by pluripotential stem cells. The purpose of this paper is to review the efficacy of available treatment options as well as the basic science rationale, indications, technique, postoperative rehabilitation, and clinical results of using cultured autologous chondrocytes in the treatment of focal full thickness chondral defects of the knee.

Knee joint effusion has been shown to cause a reflex inhibition of the quadriceps musculature. However, the effect of effusion on knee joint proprioception has not been thoroughly investigated. This issue is further clouded by the debate surrounding the role of the muscle spindle and joint mechanoreceptors in providing afferent feedback to the central nervous system. This case study examines the effects of a chronic effusion on knee joint proprioception. Possible suggestions for the results are discussed, and areas for further study are offered.

Reflex response times of the vastus medialis obliquus and vastus lateralis were evaluated in 41 normal subjects and 16 patients with extensor mechanism dysfunction. The reflex response times for both muscles to a patellar tendon tap were evaluated by electromyography. The latencies of the muscles were statistically analyzed in both groups. In normal subjects, one-tailed paired-sample t-tests determined that the vastus medialis obliquus fired significantly faster than the vastus lateralis (P less than 0.001). In the patients, the vastus lateralis fired significantly faster than the vastus medialis obliquus (P less than 0.001). A chi square goodness of fit test demonstrated a dependency between the order of muscle firing and the type of subject (P less than 0.001). Two-tailed independent-sample t-tests revealed that the patients demonstrated a significantly faster vastus lateralis response time than the normal subjects (P less than 0.001), whereas the vastus medialis obliquus times were not significantly different. This increase in vastus lateralis reflex response time may indicate a motor control problem in the patient with extensor mechanism dysfunction. Results indicate that there is a reversal of the normal muscular firing order between the two muscles in these patients. Patients with extensor mechanism dysfunction may be demonstrating a neurophysiologic motor control imbalance that may account for or contribute to their anterior knee pain.