The effects of the neodymium laser on meniscal repair in the avascular zone of the meniscus

Low Level Laser Therapy for chronic knee joint pain patients

BACKGROUND AND AIMS

Chronic knee joint pain is one of the most frequent complaints which is seen in the outpatient clinic in our medical institute. In previous studies we have reported the benefits of low level laser therapy (LLLT) for chronic pain in the shoulder joints, elbow, hand, finger and the lower back. The present study is a report on the effects of LLLT for chronic knee joint pain.

MATERIALS AND METHODS

Over the past 5 years, 35 subjects visited the outpatient clinic with complaints of chronic knee joint pain caused by the knee osteoarthritis-induced degenerative meniscal tear. They received low level laser therapy. A 1000 mW semi-conductor laser device was used to deliver 20.1 J/cm(2) per point in continuous wave at 830nm, and four points were irradiated per session (1 treatment) twice a week for 4 weeks.

RESULTS

A visual analogue scale (VAS) was used to determine the effects of LLLT for the chronic pain and after the end of the treatment regimen a significant improvement was observed (p<0.001). After treatment, no significant differences were observed in the knee joint range of motion. Discussions with the patients revealed that it was important for them to learn how to avoid postures that would cause them knee pain in everyday life in order to have continuous benefits from the treatment.

CONCLUSION

The present study demonstrated that 830 nm LLLT was an effective form of treatment for chronic knee pain caused by knee osteoarthritis. Patients were advised to undertake training involving gentle flexion and extension of the knee.

Building an anisotropic meniscus with zonal variations

Toward addressing the difficult problems of knee meniscus regeneration, a self-assembling process has been used to re-create the native morphology and matrix properties. A significant problem in such attempts is the recapitulation of the distinct zones of the meniscus, the inner, more cartilaginous and the outer, more fibrocartilaginous zones. In this study, an anisotropic and zonally variant meniscus was produced by self-assembly of the inner meniscus (100% chondrocytes) followed by cell seeding the outer meniscus (coculture of chondrocytes and meniscus cells). After 4 weeks in culture, the engineered, inner meniscus exhibited a 42% increase in both instantaneous and relaxation moduli and a 62% increase in GAG/DW, as compared to the outer meniscus. In contrast, the circumferential tensile modulus and collagen/DW of the outer zone was 101% and 129% higher, respectively, than the values measured for the inner zone. Furthermore, there was no difference in the radial tensile modulus between the control and zonal engineered menisci, suggesting that the inner and outer zones of the engineered zonal menisci successfully integrated. These data demonstrate that not only can biomechanical and biochemical properties be engineered to differ by the zone, but they can also recapitulate the anisotropic behavior of the knee meniscus.

The knee meniscus: structure-function, pathophysiology, current repair techniques, and prospects for regeneration

Extensive scientific investigations in recent decades have established the anatomical, biomechanical, and functional importance that the meniscus holds within the knee joint. As a vital part of the joint, it acts to prevent the deterioration and degeneration of articular cartilage, and the onset and development of osteoarthritis. For this reason, research into meniscus repair has been the recipient of particular interest from the orthopedic and bioengineering communities. Current repair techniques are only effective in treating lesions located in the peripheral vascularized region of the meniscus. Healing lesions found in the inner avascular region, which functions under a highly demanding mechanical environment, is considered to be a significant challenge. An adequate treatment approach has yet to be established, though many attempts have been undertaken. The current primary method for treatment is partial meniscectomy, which commonly results in the progressive development of osteoarthritis. This drawback has shifted research interest toward the fields of biomaterials and bioengineering, where it is hoped that meniscal deterioration can be tackled with the help of tissue engineering. So far, different approaches and strategies have contributed to the in vitro generation of meniscus constructs, which are capable of restoring meniscal lesions to some extent, both functionally as well as anatomically. The selection of the appropriate cell source (autologous, allogeneic, or xenogeneic cells, or stem cells) is undoubtedly regarded as key to successful meniscal tissue engineering. Furthermore, a large variation of scaffolds for tissue engineering have been proposed and produced in experimental and clinical studies, although a few problems with these (e.g., byproducts of degradation, stress shielding) have shifted research interest toward new strategies (e.g., scaffoldless approaches, self-assembly). A large number of different chemical (e.g., TGF-β1, C-ABC) and mechanical stimuli (e.g., direct compression, hydrostatic pressure) have also been investigated, both in terms of encouraging functional tissue formation, as well as in differentiating stem cells. Even though the problems accompanying meniscus tissue engineering research are considerable, we are undoubtedly in the dawn of a new era, whereby recent advances in biology, engineering, and medicine are leading to the successful treatment of meniscal lesions.

Self-assembly of fibrochondrocytes and chondrocytes for tissue engineering of the knee meniscus

Chondrocyte self-assembly in high-density scaffoldless culture has shown success in producing articular cartilage constructs, and a similar process could be applied to fibrocartilage tissue engineering. Three cell combinations were compared in self-assembly culture-100% chondrocytes, 100% meniscal fibrochondrocytes, and 50:50 co-cultures of fibrochondrocytes and chondrocytes with the goal of creating a proteoglycan, collagen I, and collagen II matrix similar to native meniscus. Two culture surfaces were also compared for self-assembly: agarose-coated wells and tissue culture plastic. After 4 weeks, the resulting self-assembled chondrocyte constructs were 10.24+/-0.63 mm in diameter and 0.96+/-0.14 mm thick, weighing 84.5+/-7.2 mg. Co-culture constructs were smaller and weighed 22.5+/-1.0 mg. In contrast, the fibrochondrocyte constructs contracted into spheres weighing 1.3+/-0.3 mg. Immunostaining showed collagen II in the chondrocyte constructs, both collagen I and collagen II in the co-cultures, and only collagen I in the fibrochondrocyte constructs. Collagen densities for chondrocyte, co-culture, and fibrochondrocyte constructs were 41+/-3, 38+/-3, and 20+/-2 microg/mg dry weight, and glycosaminoglycan densities were 230+/-2, 80+/-6, and 10+/-1 microg/mg dry weight, respectively. Self-assembled co-cultures, with their mixed collagen I and II matrix and robust gross characteristics, appear promising for tissue engineering of the knee meniscus.

Cell-based therapy for meniscal repair: a large animal study

BACKGROUND

The avascular portion of the meniscus cartilage in the knee does not have the ability to repair spontaneously.

HYPOTHESIS

Cell-based therapy is able to repair a lesion in the swine meniscus.

STUDY DESIGN

Controlled laboratory study.

METHODS

Sixteen Yorkshire pigs were divided into four groups. A longitudinal tear was produced in the avascular portion of the left medial meniscus of 4 pigs. Autologous chondrocytes were seeded onto devitalized allogenic meniscal slices and were secured inside the lesion with two sutures. Identical incisions were created in 12 other pigs, which were used as three separate control groups: 4 animals treated with an unseeded scaffold, 4 were simply sutured, and 4 were left untreated. Meniscal samples were collected after 9 weeks, and the samples were analyzed grossly, histologically, and histomorphometrically.

RESULTS

Gross results showed bonding of the lesion margins in the specimens of the experimental group, whereas no repair was noted in any of the control group specimens. Histological and histomorphometrical analysis showed multiple areas of healing in the specimens of the experimental group.

CONCLUSIONS

This study demonstrated the ability of seeded chondrocytes to heal a meniscal tear.

CLINICAL RELEVANCE

Cell-based therapy could be a potential tool for avascular meniscus repair.

Experimental study on thermal welding for the knee meniscal white zone

It is difficult to repair tears of the meniscus at the white zone by suturing. We considered that there might be an optimal tissue welding temperature when thermally welding the meniscal white zone, so we conducted a thermal welding experiment using bovine and human menisci. The samples prepared after thermal welding were investigated by measuring the tensile strength, analyzing the histological findings of the welded portion and the meniscal parenchyma, and conducting biochemical analyses. In the experiment using human menisci, histological findings were investigated using transmission electron microscopy (TEM). As the findings on the welded tissue in the white zone of the bovine meniscus indicated positive results at 63 degrees C and 69 degrees C, the experiments using human meniscal white zone were conducted at these two temperatures. The highest tensile strength after thermal welding of the human meniscal white zone was 101.4 +/- 2.6 g/cm(2) at 63 degrees C. Although there were no significant differences in the amount of pyridinoline per unit collagen weight [Pyr/Hpr (%)] in the human meniscus after thermal welding between the control group and various temperature groups (55 degrees C, 63 degrees C, 69 degrees C, 75 degrees C), the amount of pyridinoline per unit of collagen weight tended to decline as the welding temperature increased. According to the TEM findings, the internal structure of the nuclei of the cells was preserved in the 63 degrees C group, whereas cells were denatured inside the nuclei in the 69 degrees C group. They exhibited necrosis, making cell regeneration difficult. Therefore, it seems feasible that thermal welding at 63 degrees C can repair tears in the human meniscal white zone.

Marrow stimulating technique to augment meniscus repair

Several techniques exist to increase the rate of healing of meniscal tears after repair. We describe a simple arthroscopic technique of microfracture to the intercondylar notch. This technique can provide marrow elements to the site of meniscus repair to aid in meniscal healing at the time of repair.