Purpose: The purpose of this study was to evaluate the ability of 2 new photoactive naphthalimide compounds to repair a lesion in the avascular zone of the meniscus. Type of Study: In vivo animal study. Methods: Ten Barbados sheep were used as the animal model. Under anesthesia, the left knee joint was opened and 2 identical lesions were produced in the avascular zone of the medial meniscus. The posterior horn lesion was left alone and used as the control and the lesion in the anterior horn was repaired using the photoactive laser technique. The photoactive laser technique involved placing small amounts of a naphthalimide compound into the lesion and then irradiating the site with a laser (457 nm and 1.8 W/cm(2)) for 6 minutes. Two different versions of the naphthalimide compound were produced and divided between the 10 animals. The joint was then flushed with normal saline and closed in layers with resorbable sutures. Four animals were euthanized at the end of 1 month and 6 animals were euthanized at the end of 3 months. After death, the medial meniscus was exposed, dissected free, and then placed in 10% buffered fonnalin for histologic preparation and staining. Results: At 1 month, the control lesions grossly showed no repair and the photochemically repaired lesions appeared to be bonded. The photochemically repaired lesions showed some bridging by an eosinophilic amorphous-appearing substance. The previous cleft within the fibrocartilaginous structure had disappeared, and early formation of connective tissue fibers was identified. However, some reduction in cellularity was seen in these tissue sections. At 3 months, again the control lesions did not show any repair response, while the photochemically repaired lesions showed results similar to the animals at 1 month, but with a less consistent pattern of tissue bonding and remodeling. The reduced tissue cellularity was still noted. There was no discernible difference between the naphthalimide compounds. Conclusions: These preliminary results demonstrate the potential usefulness of this photochemical bonding for the treatment of avascular meniscal lesions. Additional research will be necessary to fully understand the mechanism of this repair and optimize its use before any human trials. Clinical Relevance: This is a preliminary animal study investigating the short-term in vivo effects of a novel photochemical compound for the repair of meniscal lesions. This repair may someday be valuable in the repair of avascular meniscal lesions.

Certain substituted naphthalimides have been shown to produce, on photochemical activation, mechanically viable bonds between a variety of tissue surfaces. It is believed that these compounds act as photochemically activated oxidants, catalyzing the formation of reactive intermediates in the extracellular matrices of approximated tissue surfaces. The condensation of these intermediates results in the formation of crosslinks between the intimate surfaces. Of particular interest is the application of this technique to the repair of tears in the typically unrepairable avascular zone of menisci. The menisci are collagen-rich fibrocartilaginous tissues that support up to 90% of the load across the knee joint and participate in important functions including shock absorption, joint stabilization, hyperextension prevention, and lubrication of the knee. Preliminary ex vivo and in vivo work in our laboratories has demonstrated that photochemically activated naphthalimides have significant potential for the repair of meniscal lesions. We describe preliminary ex vivo studies assessing the relative abilities of a variety of water-soluble monomeric 4-amino-1,8-naphthalimides to bond bovine knee meniscal tissue on visible light irradiation.

PURPOSE A clinically and arthroscopically oriented staging system based on the severity of the degenerative process has been used in the assessment of the results of arthroscopic lavage and debridement of osteoarthritic (OA) knees. TYPE OF STUDY Retrospective case series. METHODS For eighteen months, commencing January 1995, every case of previously untreated OA referred for definitive treatment was clinically classified into 1 of 4 stages of increasing degeneration. Excluded were patients who were treated nonoperatively, by replacement arthroplasty or marrow stimulation techniques. A group of 121 cases treated by arthroscopic lavage and debridement were available for review with a 4 to 6 year follow-up. RESULTS Arthroscopic lavage and debridement carried out in the earlier stages of the degenerative process resulted in significant relief of symptoms for reasonably long periods of time. The more advanced stages of degeneration commonly experienced some temporary relief from arthroscopic lavage and debridement, but the amount of improvement was unpredictable. CONCLUSIONS The surgeon's armamentarium for the treatment of degenerative arthritis unresponsive to conservative treatment methods should involve minimal interventional arthroscopy at an earlier, rather than a later stage in the disease process. It is recommended that the arthroscopist be conservative in the surgical debridement, removing only the fibrillated and scaling fragments of articular cartilage.

Sherk, Henry H. MD; Vangsness, C. Thomas MD; Thabit, George III MD; Jackson, Robert W. MD Author Information

Arthroscopic synovectomy of the knee is a technique used for the treatment of the patient whose problems with synovitis and effusion are unsuccessfully treated by nonsurgical means. It offers multiple advantages when compared with open synovectomy but requires attention to detail and the surgeon should follow a set routine. A proven technique and routine are presented.

Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 15, No 6 (September), 1999: pp 680–685