Effect of Helium-Neon (He-Ne) Laser Irradiation on Dog Neoplasm Cells in Culture

The effects of laser light on the cellular proliferation have been extensively characterised. Low-power laser sources, such as the helium–neon (He-Ne) laser irradiation with a wavelength of 632.8 nm, have been found to produce photobiological and photodamaging effects with evidence of interference with cell proliferation functions. The present study has investigated the in vitro effect of He-Ne laser irradiation on the proliferative action of dog tumour cells in culture. Dose–response studies showed that repeated He-Ne irradiation (irradiance 12.8 mW/cm²) once a day for 4 consecutive days in a dose range between 0.13 and 2.08 J/cm² significantly increased with increasing energy density up to a laser dose of 0.26 J/cm², whereas at >1.04 J/cm², the cell proliferation decreased with increasing energy densities. It is concluded that the application of He-Ne laser irradiation at energy densities ranging from 0.13 J/cm² to 2.08 J/cm² produced different effects on cell proliferation in dog tumour cells in culture. Paper received for publication 27 June 1997; accepted following revision 6 February 1998.     

Biological Effect of Helium-Neon (He-Ne) Laser Irradiation on Mouse Myeloma (Sp2-Ag14) Cell Line In Vitro

We examined the effect of helium-neon (He-Ne) laser irradiation with a wavelength of 632.8 nm on cell cycle synchronisation of monolayer growing mouse myeloma (Sp2-Ag14) cell line. The monolayer cultures were exposed to repeated doses of different energy densities (4–64 J/cm²). The nuclear DNA content has been studied by flow cytometry to obtain the cell percentage in each cell cycle phase. Results showed that the He-Ne laser irradiation at energy densities of 8–64 J/cm² produced a significative and different effect on the G0–G1 and S phases of cell cycle over control. In contrast, no significant effect in G2–M phase was produced by He-Ne laser irradiation at any energy density compared with non-treated control. These results support previous observations suggesting that He-Ne laser irradiation of low energy density interferes with cell cycling and may inhibit cell proliferation when irradiation is performed at doses of 8 J/cm² or more. Received for publication 22 July 1997; accepted following revision 6 February 1998.     

Effect of infra-red low-power laser irradiation on regeneration of myelinated axons

The purpose of the present study was to examine the regeneration of myelinated axons under the effect of laser irradiation at various wavelengths and energy densities. Laser irradiation at 890 nm with an energy dose of 0.33 J cm^–2 as well as He-Ne laser irradiation failed to change the number of regenerating myelinated axons in distal nerve stumps on the 30th day after cutting the nerve. An increase of dose delivered to the skin to 9.33 J cm^–2 resulted in a 49% decrease in the number of myelinated axons. A 24% suppression of nerve regeneration was also registered using 1220 nm wavelength laser (dose 0.98 J cm^–2). This phenomenon is likely to be attributed to the stimulating effect of laser irradiation of the near-infra-red range on proliferation of fibroblasts and scar formation. 1220 nm of 7.2 J cm^–2 dose effected neither the growth nor the myelinization of axons in distal nerve stumps on the 20th day following nerve damage.     

Helium-Neon (He-Ne) Laser Irradiation Increases the Incidence of Unreduced Bovine Oocytes During the First Meiotic Division In Vitro

Low power He-Ne laser irradiation was applied to immature bovine oocytes to investigate the incidence of unreduced oocytes (diploid oocytes) during the first meiotic division in vitro. Immature bovine oocytes from cows killed at a slaughterhouse were irradiated with He-Ne laser irradiation at 0.05 and 0.25 J/cm² exposures. An oocyte group was left untreated serving as the control group. All oocytes were matured in TCM-199 medium supplemented with 10% fetal calf serum (FCS). Unreduced oocyte percentages obtained in the irradiated oocytes group were significantly higher (p<0.01 and p<0.001, respectively) than those of the control group. Furthermore, the laser-treated oocytes showed a degeneration rate significantly higher (p<0.01 and p<0.001, respectively) than those observed in the control group. It is concluded that the application of He-Ne laser irradiation at 0.05 and 0.25 J/cm² exposures increased the incidence of unreduced oocytes and the percentage of degenerated oocytes during the in vitro meiosis process of immature bovine oocytes. Received 13 October 1997; accepted following revision 13 January 1998     

Effect of low-power He-Ne laser irradiation on rabbit articular chondrocytes in vitro

BACKGROUND AND OBJECTIVES: In the orthopaedic field, the repair of articular cartilage is still a difficult problem, because of the physiological characters of cartilaginous tissues and chondrocytes. To find an effective method of stimulating their regeneration, this in vitro study focuses on the biostimulation of rabbit articular chondrocytes by low-power He-Ne laser. STUDY DESIGN/MATERIALS AND METHODS: The articular chondrocytes isolated from the cartilage of the medial condyle of the femur of the rabbit were incubated in DMEM/HamF(12) medium. The second passage culture were spread on 24 petri dishes and were irradiated with laser at power output of 2-12 mW for 6.5 minutes, corresponding to the energy density of 1-6 J/cm(2). Laser treatment was performed three times at a 24-hour interval. After lasering, incubation was continued for 24 hours. Non-irradiated cells were kept under the same conditions as the irradiated ones. The cell proliferation activity was evaluated with a XTT colorimetric method and the cell secretion activity was analyzed by metachromasia and immunocytochemistry. RESULTS: Irradiation of 4-6 J/cm(2) increased the cell numbers and revealed a considerably higher cell proliferation activity comparing to control cultures. Thereinto, the energy density of 4 and 5 J/cm(2) remarkably increased cell growth, with positive effect on synthesis and secretion of extracellular matrix. CONCLUSIONS: The present study showed that a particular laser irradiation stimulates articular chondrocytes proliferation and secretion. These findings might be clinically relevant, indicating that low-power laser irradiation treatment is likely to achieve the repair of articular cartilage in clinic.     

Helium-Neon laser irradiation inhibits the growth of kidney epithelial cells in culture

We have investigated the in vitro action of helium-neon (He-Ne) laser light on the cell cycle and the growth of rat kidney epithelial cell cultures. Dose-response studies showed that repeated He-Ne irradiation (dose rate 40 mW/cm²) once a day in a dose range between 11.9 and 142 J/cm² significantly inhibited cell growth, while daily irradiation with 4.7 J/cm² had no effect. Microscopic examination of nuclear spreads revealed an increased number of cells in mitosis after a single irradiation with 142 J/cm². These results support previous observations suggesting that laser light of low thermal energy interferes with cell cycling and may inhibit cell growth when irradiation is performed at doses of 11.9 J/cm² or more.     

No effect of GA-AS (904 nm) laser irradiation on the intact skin of the injured rat sciatic nerve

We evaluated the electrophysiological and histopathological effects of low-energy gallium arsenide (904 nm) laser irradiation on the intact skin injured rat sciatic nerve. Twenty-four male Wistar rats were divided into three groups (n=8 each). At the level of proximal third of the femur the sciatic nerve was crushed bilaterally with an aneursym clip (Aesculap FE 751, Tuttingen, Germany) for half a second. A gallium arsenide laser (wavelength 904 nm, pulse duration 220 ns, peak power per pulse 27 W, spot size 0.28 cm², pulse repetition rate 16, 128 and 1000 Hz; total applied energy density 0.31, 2.48 and 19 J/cm²) was applied to the right sciatic nerve for 15 min daily at the same time on 7 consecutive days. The same procedure was performed on the left sciatic nerve of same animal, but without radiation emission, and this was accepted as control. Compound muscle action potentials were recorded from right and left sides in all three groups before surgery, just at the end of injury, at the 24th hour and on the 14th and 21st days of injury in all rats using a BIOPAC MP 100 Acquisition System Version 3.5.7 (Santa Barbara, USA). BIOPAC Acknowledge Analysis Software (ACK 100 W) was used to measure CMAP amplitude, area, proximal and distal latency, total duration and conduction velocity. Twenty-one days after injury, the rats were sacrificed. The sciatic nerves of the operated parts were harvested from the right and left sides. Histopathological evaluation was performed by light microscopy. Statistical evaluation was done using analysis of variance for two factors (right and left sides) repeated-measures (CMAP variables within groups) and the Tukey–Kramer Honestly Significant Difference test (CMAP variables between laser groups). The significance was set at p 0.05. No statistically significant difference (p 0.05) was found regarding the amplitude, area, duration and conduction velocity of CMAP for each applied dose (0.31, 2.48 and 19 J/cm²) on the irradiated (right) side and the control (left) side, or between irradiated groups. Twenty-one days after injury there were no qualitative differences in the morphological pattern of the regenerated nerve fibres in either irradiated (0.31, 2.48 and 19 J/cm²) or control nerves when evaluated by light microscopy. This study showed that low-energy GaAs irradiation did not have any effect on the injured rat sciatic nerve.     

Inhibitory Effect of Yellow He-Ne Laser Irradiation Mediated by Crystal Violet Solution on Early Plaque Formation in Human Mouth

. The purpose of this study was to evaluate the effect of yellow He-Ne laser irradiation in the presence of crystal violet (CV) solution on dental plaque formation in the human mouth. Four enamel specimens were fixed on a retainer, one of which was placed on both maxillary buccal sites of four subjects. The retainers were assigned randomly to 3- or 7-day experimental periods and the right or left buccal sites for the evaluation of plaque formation on the specimens. Then, the specimens were assigned randomly to four treatments as follows: A, laser irradiation; B, CV application; C, CV application and laser irradiation and D, no treatment (control). At three and seven days after the treatments, the inhibitory effects of plaque formation on the specimens were evaluated by measuring the thickness of the plaque on each section. Analysis of the plaque formation scores revealed that treatment C had a significantly greater inhibitory effect on plaque formation than treatment A, B and D after 3 days, however there were no significant differences among the plaque formation scores of the four treatment groups after 7 days. Analysis of the plaque thickness revealed that at both 3 and 7 days after treatment, the plaque layers after treatment C were significantly thinner than those after treatments A, B and D. These results indicated that yellow He-Ne laser irradiation in the presence of CV had an inhibitory effect of plaque formation in human mouth. Paper received 9 July 1999; accepted after revision 3 February 2000.     

Low-level laser therapy prevents degenerative morphological changes in an experimental model of anterior cruciate ligament transection in rats

The aim of this study was to analyze the effects of low-level laser therapy (LLLT) on the prevention of cartilage damage after the anterior cruciate ligament transection (ACLT) in knees of rats. Thirty male rats (Wistar) were distributed into three groups (n?=?10 each): injured control group (CG); injured laser-treated group at 10 J/cm² (L10), and injured laser-treated group at 50 J/cm² (L50). Laser treatment started immediately after the surgery and it was performed for 15 sessions. An 808 nm laser, at 10 and 50 J/cm², was used. To evaluate the effects of LLLT, the qualitative and semi-quantitative histological, morphometric, and immunohistochemistry analysis were performed. Initial signs of tissue degradation were observed in CG. Interestingly, laser-treated animals presented a better tissue organization, especially at the fluence of 10 J/cm². Furthermore, laser phototherapy was able of modulating some of the aspects related to the degenerative process, such as the prevention of proteoglycans loss and the increase in cartilage area. However, LLLT was not able of modulating chondrocytes proliferation and the immunoexpression of markers related to inflammatory process (IL-1 and MMP-13). This study showed that 808 nm laser, at both fluences, prevented features related to the articular degenerative process in the knees of rats after ACLT.     

Free electron laser ablation of articular and fibro-cartilage at 2.79, 2.9, 6.1, and 6.45 microm: mass removal studies

BACKGROUND AND OBJECTIVE: The wavelength and tissue-composition dependence of cartilage ablation was examined using selected mid-infrared laser wavelengths. STUDY DESIGN/MATERIALS AND METHODS: The mass removal produced by pulsed laser ablation of articular and fibro-cartilage (meniscus) were measured. The wavelengths examined were 2.79, 2.9, 6.1, and 6.45 microm and provided by a free electron laser (FEL) emitting 4 microsecond macropulses consisting of 1-2 picoseconds duration micropulses delivered at 350 picosecond intervals. The measurement of tissue mass removal was conducted using a microbalance during laser ablation. RESULTS: These studies demonstrated that for articular cartilage the highest mass removal was achieved at lambda = 6.1 microm followed by, in order, lambda = 2.79, 2.9, and 6.45 microm. In comparison, the maximum mass removal for fibro-cartilage was achieved using lambda = 6.1 microm radiation with no statistically significant differences in mass removal provided by the other wavelengths. In evaluation of the comparative influence of each wavelength on tissue type, there was no difference in ablation efficiency between articular and fibro-cartilage at lambda = 6.1 microm. However, the ablation efficiency of articular cartilage was higher than that of fibro-cartilage at both lambda = 2.79 and 2.9 microm. By contrast, lambda = 6.45 microm radiation ablated fibro-cartilage more efficiently than articular cartilage at radiant exposures greater than 12 J/cm2. CONCLUSIONS: The mass removal of articular and fibro-cartilage produced by FEL ablation at selected mid-IR wavelengths was measured as a function of incident radiant exposure. The ablation efficiency was found to depend on both wavelength and tissue type. The 6.1 microm wavelength was found to provide the highest ablation efficiency for both articular and fibro-cartilage.     

Editorial Commentary: Knee Lateral Femoral Osteochondral Allografts Are Not Recommended for Medial Femoral Condylar Defects: If the Shoe Doesn’t Fit,Don’t Wear It!

Treatment of large articular cartilage defects of the knee is challenging, particularly in young, high-demand patients. Osteochondral allograft (OCA) transplantation is a viable treatment option, providing fully mature articular cartilage during a single operation while avoiding donor site morbidity. Indications are symptomatic, full-thickness articular cartilage defects >3 cm². Contraindications include a “kissing” lesion of the corresponding articular cartilage surface, uncorrected ligamentous instability, malalignment, peripheral osteophytes, joint-space narrowing, or absence of >50% of the meniscus in the affected compartment. Matching for size and contour is crucial; therefore, we use medial femoral condyle (MFC) allografts for MFC lesions and lateral femoral condyle (LFC) allografts for LFC lesions, and do not recommend LFC grafts for the MFC. Survival rates are 78.7% and 72.8% at 10 and 15 years, respectively.     

Helium-neon laser: A contraindication for infected wounds? In vitro study on pseudomonas aeruginosa

The purpose of this investigation was to examine the susceptibility ofPseudomonas aeruginosa to helium-neon (He-Ne) laser in order to gain an insight into the clinical implications for this type of low-level laser therapy (LLLT) in the treatment of infected wounds. Suspensions, in the presence and the absence of methylene blue (MB, 0.001% w/v), were exposed to the light from a 9 mW He-Ne laser for 5 and 50 min. Exposure of samples without MB did not affect the viability of this organism based on the lack of significant differences in the number of colony forming units (CFU) between irradiated and control samples. In the presence of MB, statistically significant mean reductions in CFU of 39.5% (22.6 J cm^-2) and 58.2% (226 J cm^-2) were found, and growth-free zones in irradiated confluent platings could be observed. Since no logarithmic reductions were achieved, the clinical implementation of He-Ne laser as a bactericidal agent seems to be of no relevance yet. Otherwise, no stimulation of bacterial growth was observed. Therefore, infection as a contraindication for LLLT should be excluded.     

Minimally invasive medial hip approach for femoral head fixation: How much can we see and what is the anatomical at risk? – A cadaveric injection study

IntroductionMost Pipkin I and II femoral head fractures are treated with either an anterior or a posterior approach. A medial hip approach is commonly used in children, and some surgeons have suggested it for femoral head fixation. The objectives of this study were to identify the structures at risk with the medial hip approach and to demonstrate the areas of the femoral head exposed using this approach.MethodsThe first part of this study involved vascular injection conducted in four fresh human cadavers using the medial hip approach. The surgical technique was described and the structures at risk, mainly arteries, were identified. The second part was done in 14 hips to identify and measured the maximum exposure area of the femoral head with the medial hip approach.ResultsThe structures at risk with the medial hip approach were the medial femoral circumflex artery (MFCA) after it branches from the deep femoral artery and runs posteromedially across the femoral neck medial to the iliopsoas tendon and the deep branch of the MFCA lies over the posterior hip capsule. The femoral head exposure area in anterior view with anteroinferior articular cartilage exposure was 4.57 ± 1.09 cm². In the medial view with the hip in internal rotation and in external rotation, the inferomedial articular cartilage exposure was 2.50 ± 1.52 cm² and 6.48 ± 2.29 cm², respectively, and the combined area of exposure was 9.49 ± 2.86 cm² . In the posterior view, the posteroinferior articular exposure was 1.69 ± 1.16 cm². The medial hip approach allowed visualization of the small area of the posteroinferior articular cartilage in all specimens. The percentages of visualization of the femoral head articular cartilage in anterior view, medial view and posterior view were 50.07% ± 13.53, 45.56% ± 12.76 and 18.07% ± 11.27%, respectively.ConclusionsThe structures at risk with the medial hip approach is the MFCA along the anterior acetabular rim and the deep branch on the posteromedial aspect of the femoral neck. It is an alternative which provides excellent access in Pipkin I and some part of Pipkin II, but it requires that the MFCA be protected by the use of meticulous surgical techniques.     

Antibacterial Effect of Yellow He-Ne Laser Irradiation with Crystal Violet Solution on Porphyromonas gingivalis: An Evaluation Using Experimental Rat Model Involving Subcutaneous Abscess

. A study was conducted to evaluate the antibacterial effect of yellow He-Ne laser irradiation with crystal violet solution (CV) on Porphyromonas gingivalis (P.g.). Paper points were soaked with a P.g. suspension (10⁹ ml) with 0.8 mg/l CV added, laser-irradiated for 60 s (laser group), and implanted subcutaneously on the back of rats. Three additional groups were studied: CV group: the paper point was soaked with the P.g. suspension plus 0.8 mg/l CV, but laser irradiation was not performed; P.g. group: the paper point was soaked with the P.g. suspension only and laser irradiation was not performed; control group: the paper point was soaked with sterilised isotonic sodium chloride solution and laser irradiation was not performed. Seven days after implantation, block sections of all implanted sites were examined histologically. The abscess area in the laser group was smaller than in the P.g. group or CV group, but larger than in the control group. The number of inflammatory cells was greatest in the P.g. and CV groups, with fewer in the laser group and still fewer in the control group. The results indicate that a yellow He-Ne laser with 0.8 mg/l CV solution exerts an antibacterial effect in vivo. Paper received 12 July 1999; accepted after revision 24 March 2000.     

Low power laser irradiation alters the rate of regeneration of the rat facial nerve

Low power laser irradiation has been reported to cause biological effects due to the photochemical and/or photophysical action of the radiation. This study determined quantitatively if transcu-taneous low power laser irradiation can affect the regeneration of the rat facial nerve. The facial nerve was crushed unilaterally in anesthetized rats and transcutaneously irradiated daily with a laser beam directed at the area of the crush injury. Laser treatment began on the day of the crush injury and was continued daily for 7, 8, or 9 days. Preliminary experiments determined the most effective wavelength, laser power, length of irradiation, and treatment schedule. The wavelengths examined were 361, 457, 514, 633, 720, and 1064. The laser powers and lengths of irradiation examined ranged from 8.5 to 40 mW and 13 to 120 min. Irradiation treatment was done daily, on alternating days and on the first 4 days postcrush. The most effective laser parameters for the low power treatment included daily irradiation with a helium-neon (HeNe) or argon pumped tunable dye laser a wavelength of 633 nm, with a power of 8.5 mW for 90 minutes (45.9 J, 162.4 J/cm²). The number of horseradish peroxidase (HRP) labeled neurons in the facial motor nucleus was used as an assay of the degree of regeneration. In rats in which the facial nerve was crushed but not irradiated, the average number of HRP labeled neurons in the facial nucleus was 22 on day 7 postcrush, 54 on day 8, 116 on day 9, and 1,149 on day 10. After HeNe or argon pumped tunable dye laser irradiation, the average number of HRP-labeled neurons increased to 34 on day 7 postcrush, 148 on day 8, and 1,725 on day 9. There was a statistically significant difference between the control and irradiated rats on day 9 post-crush (P < 0.01). These data indicate that transcutaneous low power irradiation with the lasers and parameters involved in this study increased the rate of regeneration of rat facial nerve following crush injury. © 1993 Wiley-Liss, Inc.     

Biological effect of low-power helium-neon (HeNe) laser irradiation

The functional effects (activation and cell damage) of low-power, continuous-wave HeNe laser irradiation were studied in different in vitro cultured cell lines. A characteristic dose-dependence was observed between 0.14 and 28.0 J/cm². The functional activation (increased phagocytic activity, immunoglobulin secretion) or cell destruction could not be detected after irradiation by normal monochromatic light of the same wavelength and energy output. The experiments suggested that low-power laser irradiation has a specific influence on the cells which depends on the coherent and polarized physical features of the laser light.     

肢体缺血-再灌注后关节软骨病理变化

目的 了解肢体缺血-再灌注(IR)后关节软骨的病理变化特点，探讨共可能的损伤机制。方法 35只成年健康新西兰大白兔随机分为7组，行左侧后肢缺血8h(右侧为对照)，于再灌注后1d、3d、1周、2周、4周、8周和12周取膝关节胫骨平台软骨组织，行大体、光学显微镜、透射电镜和扫描电镜观察。结果 对照侧肢体关节软骨表面平整，细胞排列整齐，形态正常?肢体缺血．再灌注后1周、2周关节软骨细胞变件、坏死，排列紊乱，数目减少，软骨表面“垄沟”变浅；4周、8周软骨表面粗糙，表层细胞脱落；12周软骨表面溃疡形成，胶原暴露，同时可见新生的软骨细胞。结论 肢体缺血．再灌注可导致关节软骨细胞损伤，软骨形态发生变化，与术后慢性关节炎的形成有密切关系。     

Evaluation of different treatment protocols for dentin hypersensitivity: an 18-month randomized clinical trial

This randomized and longitudinal in vivo study aimed to assess different protocols for the treatment of dentin hypersensitivity with low-power laser (with different doses), high-power laser, and a desensitizing agent, for a period of 12 and 18 months. The lesions from 32 patients (117 lesions), who were submitted to the inclusion and exclusion criteria, were divided into nine groups (n = 13): G1: Gluma Desensitizer (Heraeus Kulzer), G2: low-power laser with low dose (three points of irradiation in vestibular portion and an apical point 30 mW, 10 J/cm², 9 s per point with the wavelength of 810 nm, with three sessions with an interval of 72 h), G3: low-power laser with high dose (one point in the cervical area, and one apical point 100 mW, 40 J/cm², 11 s per point with the wavelength of 810 nm in three sessions with an interval of 72 h), G4: low-power laser with low dose + Gluma Desensitizer, G5: low-power laser with high dose + Gluma Desensitizer, G6: Nd:YAG laser (Power Laser? ST6, Research® in contact 1.0 W, 10 Hz and 100 mJ, ≈85 J/cm², with the wavelength of 1064 nm), G7: Nd:YAG laser + Gluma Desensitizer, G8: low-power laser with low dose + Nd:YAG laser, and G9: low-power laser with high dose + Nd:YAG laser. The level of sensitivity of each volunteer was assessed by visual analog scale of pain (VAS) with the aid of air from the triple syringe and exploration probe, 12 and 18 months after treatment. All analyses were performed separately for air and probe stimulus. The level of significance was considered for values of p < 0.05. After statistical analysis, all treatments were shown to be effective in reducing dentinal hypersensitivity, and the results were considered not statistically different from those at 12 months. Therefore, until the 18-month evaluation, it could be said that no statistical differences were observed in the sensitivity levels for all treatments.     

Inhibitory effects of low-level laser therapy on skin-flap survival in a rat model

BACKGROUND:Although several studies have demonstrated the effects of low-level laser therapy (LLLT) on skin flap viability, the role of higher doses has been poorly investigated.OBJECTIVE:To investigate the inhibitory effect of the LLLT (λ=670 nm) on the viability of random skin flaps in a rat model using an irradiation energy of 2.79 J at each point.METHODS:Sixteen Wistar rats were randomly assigned into two groups: sham laser irradiation (n=8); and active laser irradiation (n=8). Animals in the active laser irradiation group were irradiated with a 670 nm diode laser with an energy of 2.79 J/point, a power output 30 mW, a beam area of 0.028 cm², an energy density of 100 J/cm², an irradiance of 1.07 W/cm² for 93 s/point. Irradiation was performed in 12 points in the cranial skin flap portion. The total energy irradiated on the tissue was 33.48 J. The necrotic area was evaluated on postoperative day 7.RESULTS:The sham laser irradiation group presented a mean (± SD) necrotic area of 47.96±3.81%, whereas the active laser irradiation group presented 62.24±7.28%. There was a significant difference in skin-flap necrosis areas between groups (P=0.0002).CONCLUSION:LLLT (λ=670 nm) increased the necrotic area of random skin flaps in rats when irradiated with an energy of 2.79 J (100 J/cm²).     

Treatment of articular defects with meniscal allografts in a rabbit knee model

Deep-frozen allogeneic meniscal grafts for the treatment of articular cartilage defects were performed experimentally. Osteochondral defects 3 mm in diameter were created bilaterally on the medial femoral condyles of 50 Japanese white rabbits. A meniscus was then grafted into the defect in the left knee, and the right knee was left untreated. At various periods from 2 to 24 weeks postoperatively, the rabbits were killed and macroscopic and histologic examinations were performed. Two weeks after operation, the grafted meniscus was bonded to the floor of the defect. After 12 weeks, chondrocytes producing matrix granules was shown by electron microscopy. After 24 weeks, a congruous articular surface was formed. With time, cellular elements infiltrated into the graft from the surrounding tissues, and gradually increased in penetration. Weight bearing in the early stage after operation did not degrade the grafted menisci, and no changes were shown in the opposing cartilage of the tibia. Deep-frozen allogeneic menisci may be useful as a biological implant to repair articular cartilage defects in this model.