Faculty Bibliography

Various arthroscopic meniscal repair techniques have been developed in recent years to preserve meniscal function. We report the case of a patient with a failed arthroscopic meniscal repair demonstrating an inflammatory foreign-body reaction to bioabsorbable meniscal arrows

The treatment of isolated articular cartilage defects is an evolving field in orthopaedic surgery today. We have summarized the basic science and clinical date on the treatment of isolated articular cartilage defects. Further long-term controlled studies are required in order to compare definitively the efficacy of treatments in this difficult clinical area. In future studies, inclusion/exclusion criteria must be detailed, and classification systems need to be standardized Comparative analysis can then be performed to assess the efficacy of various techniques.

We have developed a novel, two-layered, collagen matrix seeded with chondrocytes for repair of articular cartilage. It consists of a dense collagen layer which is in contact with bone and a porous matrix to support the seeded chondrocytes. The matrices were implanted in rabbit femoral trochleas for up to 24 weeks. The control groups received either a matrix without cells or no implant. The best histological repair was seen with cell-seeded implants. The permeability and glycosaminoglycan content of both implant groups were nearly normal, but were significantly less in tissue from empty defects. The type-II collagen content of the seeded implants was normal. For unseeded implants it was 74.3% of the normal and for empty defects only 20%. The current treatments for articular injury often result in a fibrous repair which deteriorates with time. This bilayer implant allowed sustained hyaline-like repair of articular defects during the entire six-month period of observation

The purpose of this study was to observe the difference in healing of full-thickness articular cartilage defects treated with burr arthroplasty versus subchondral drilling. Cartilage was shaved off the medial femoral condyles of 39 rabbits without penetrating the subchondral plate. In left knees, two 2.0-mm holes were drilled into the condyle until bleeding was obtained. Right knees underwent a burr arthroplasty until punctate bleeding was observed. Animals were sacrificed at 6, 12, and 24 weeks postoperatively. Joint resurfacing and degenerative changes were evaluated grossly and histologically. Degenerative changes in the cartilage surface were observed with both treatments. Rabbits undergoing subchondral drilling had increased fibrocartilaginous healing with time, with a slight increase in degenerative changes. With burr arthroplasty, there was significant decrease in cartilaginous coverage of the exposed surface as well as progressive increase in degenerative changes. Although both techniques were suboptimal, histological evidence at 6 months suggests that subchondral drilling may result in a longer-lived repair than abrasion arthroplasty in the treatment of full-thickness lesions

This study was designed to evaluate the potential use of a prototype collagen-chondrocyte allograft in the repair of full-thickness articular cartilage defects. Articular cartilage was harvested from young donor New Zealand White rabbits, enzymatically digested, cultured in monolayer, and passed into a three-dimensional porous type I collagen sponge (American Biomaterials). The composite grafts were incubated for 1 week. (Phase I) Twenty adult NZW rabbits underwent bilateral knee arthrotomies. Three-millimeter full-thickness articular cartilage defects were made in the trochlea of the distal femur. A 4-mm circular punch from the composite cell-seeded grafts was press-fit into the right knee defects. The left knee served as a control (collagen sponge alone or ungrafted defect). Animals were allowed free activity postoperatively and were killed in groups of five at 4, 8, 12, and 24 weeks postoperatively. Defect areas were harvested. Sections were cut at 5-microm thickness and stained with hematoxylin and eosin. The degree as well as quality of healing were assessed and scored with a grading system modified from Salter and O'Driscoll for cartilage repair. (The maximum score was 24 points.) Safranin-O staining as well as polarized light examination of representative sections was undertaken to assess the proteoglycan content and structural characteristics of the repair matrix. (Phase II) An additional 15 NZW rabbits underwent the above procedure but with the addition of fibroblast growth factor (FGF) (100 ng/ml) and insulin (5 microg/ml) to the growth medium of the composite grafts as stimulators of chondrocyte proliferation and proteoglycan synthesis. Control specimens in phase I and II (collagen sponge alone or ungrafted defects) healed with a primarily fibrous or fibrocartilagenous matrix. Defects grafted with cell-seeded collagen sponges demonstrated enhanced healing at all time points examined when compared to controls. There was a strong tendency toward a hyaline appearing matrix with increased Safranin-O staining and birefringence under polarized light more closely resembling the normal native cartilage. Mean histologic score for grafted defects was 18.4 (+/-3.1). Mean scores for collagen sponge alone and ungrafted defects in phase I were 12.7 (+/-4) and 12.7 (+/-3.1) (P<0.01). The addition of FGF and insulin to the growth medium (phase II) resulted in a significantly enhanced repair matrix when compared to the non-FGF-enhanced grafts, with a greater percentage of hyaline appearing tissue at all time points examined (4,8, and 12 weeks). Organization of the chondrocytes was improved at all time points examined as well. Mean histologic score for the FGF-grafted defects was 21.1 (+/-3.0). Mean scores for collagen sponge alone and ungrafted defects in phase II were 14.9 (+/-2.9) and 15.5 (+/-1.9) (p<0.01)

The advancement of the femoral bone plug, with proper orientation through the femoral tunnel is often one of the most difficult maneuvers in the reconstruction of the anterior cruciate ligament using a bone-patellar tendon-bone graft. The authors describe a modification to the procedure featuring the use of methylene blue marker (to make a inverted question markblue dot inverted question mark) to highlight the site of drill holes as well as the anterior bone-tendon junction. The inverted question markblue dot inverted question mark aids the localization of the drill hole with a probe and thus the advancement of the femoral plug through the femoral tunnel.

Most of the investigation of the properties of the anterior cruciate ligament (ACL) has focused on its biomechanical functions. There has been increasing interest in the study of the possible neuroreceptor function of the ACL and its role in providing important proprioceptive feedback. Anatomic and histologic studies in humans have shown the presence of neuroreceptors within the anterior cruciate ligament. Indirect evidence exists that proprioception is diminished in the ACL-deficient knee. However, direct evidence in humans of the actual origin of the afferent impulses from within the ACL itself is lacking. Measurement of direct electrical afferent activity, occurring on stimulation of the ACL, should provide this evidence. Somatosensory evoked potentials (SEP) measure the electric potentials evoked in the cerebral cortex upon stimulation of a peripheral neuroreceptor. Carried by the posterior columns of the spinal cord, they reflect activity of the proprioceptive fibers. During arthroscopic procedures performed on nine patients, the normal ACL was stimulated by the use of electrodes applied to the femoral end, midsubstance, and tibial end, and cortical potentials thus evoked were recorded. In all cases, SEPs were recorded at the cerebral cortex upon stimulation of the ACL. The greatest potentials were reported upon stimulation of the midsubstance of the ligament. These findings provide direct evidence for, and strongly support the presence of, active proprioceptive receptors within the intact anterior cruciate ligament of the human knee.