Aim: Experimentally forming a frayed Achilles tendon rupture model in rabbit and repairing the ruptured site with different methods; after the tendon healing, with the help of biomechanical and histopathological analyses, to find out which repair method is the most ideal.

Material and Method: This study was carried out using 34 mature, female New Zealand type of rabbits with weights ranging 2200 to 2900 grams (2429,4 on average). The animals were divided into two groups named P and V, each with 17 rabbits. In each group, Achilles tendon on the right side was employed for the experiment (Pd and Vd) and the other side as a control (Pk and Vk). In the experiment groups, a frayed Achilles tendon rupture was performed. The control groups, however, received no procedures. After the primary repair, the Achilles tendons in the group Pd were augmented with the plantaris tendon. The Achilles tendons in the group Vd were primarily repaired after releasing gastrocnemius aponeurosis using “inverted-V” incision. In both groups, an above-knee cast was applied on the surgically procedured sides. After six weeks of observation, the repaired sites on tendons in the animals alive were analyzed biomechanically and histopathologically. 12 and 3 animals from each group were used respectively for the biomechanical and the histopathological analyses.

Results: The elongation at tendon to rupture was 3,02±0,47 mm for Pd and 2,86±0,35 mm for Vd. The difference between two groups, however, was not statistically significant (p> 0,05). The maximum load at rupture for Pd was 105,88±38,14 N, and it was 71,95±17,44 N for Vd, thus the difference was statistically significant (p< 0,05). The energy needed to initiate a damage to the tendon was 0,1979±0,0902 J for Pd, and 0,1309±0,0368 J for Vd, the difference was also statistically significant (p< 0,05). The elongation, maximum load and energy values were lower in Pd group than in Pk, and in Vd group than in Vk, and the differences between each groups were statistically significant (p< 0,05). In histopathological sense, the tendon healing process in group Pd was faster than in group Vd.

Conclusion: Although the repairs made with the augmentation of plantaris tendon yielded better results; the tendon, no matter which method is used, could not has its former strength. Results are bound to be better with stronger repair, and if the repair as much as supported by adjacent tendinous structures.

Key Words: Achilles tendon, rupture, primary repair, m. plantaris, rabbit

The pineal hormone melatonin was recently shown to have a free radical scavenging ability which reduces lipid peroxidation and has also been shown to scavenge the hydroxyl radical and other reactive oxygen species. Melatonin stimulates several antioxidative enzymes, which increases its efficiency as an antioxidant. Also, melatonin stimulates osteoblast differentiation and mineralization of matrix and it may regulate osteoclastic activity via superoxide dismutase in vitro. Therefore, the effect of melatonin in fracture healing depends in part on the free radical scavenging and osteoblastic-osteoclastic regulatory properties of melatonin.

In this study the effect of melatonin (MEL) on fracture healing in rat tibia model was studied by using biochemical, radiological and histopathologic methods.

Male Sprague-Dawley rats (n=80) were randomized into control and melatonin groups with 8 rats per group according to the day of sacrifice (Days 1, 3, 7, 14, 28). Group B (melatonin group) received 30 mg/kg melatonin intraperitoneally (i.p.) for the duration of the experiment.

Malondialdehyde (MDA) levels in MEL group decreased at days 3, 7, 14, and 28 compared to control values (p< 0.05). Superoxide dismutase (SOD) activity in MEL group decreased at days 3, 7, and 14, and returned to the first day value after 28 days. Myeloperoxidase (MPO) values in MEL group decreased at days 1, 3, and 7 (p< 0.001). Both radiologically and histopathologically fracture healing was significantly more advanced in the MEL group (p< 0.05, p< 0.05 respectively).

We conclude that exogenously administering a pharmacological dose of melatonin has a positive effect on fracture healing and may be beneficial as a supportive agent in fracture cases.

Aim: To biomechanically achieve both the most ideal and the strongest core and periferal suture method by combining 2 and 4 strand core sutures with the simple running and a new locking periferal suture techniques.

Materials and Methods: Fourty flexor digitorum pro-fundus tendons from sheep hindlimbs were studied. The tendons were then repaired using 4 different repair techniques: Group 1 – control, Group 2 – 2 strand modified Kessler’s core suture and simple running periferal suture, Group 3 – 2 strand modified Kessler’s core suture and a new multilocking loop periferal suture, Group 4 – 4 strand modified Kessler’s core suture and simple running periferal suture, Group 5 – 4 strand modified Kessler’s core suture and a new multilocking loop periferal suture. After tenoraphy all fresh sheep cadavers tendons were tested to failure using a distraction rate of 20 mm/min. Maximal strength, 2 mm gap formation force, load to failure, stiffness, method of failure and rate of tendon resistance were assessed. After and before tenoraphy, front – back and side sizes were measured.

Results: Maximal strength was 496, 32, 94, 45 and 100 Newtons for Groups 1, 2, 3, 4 and 5 respectively. There was a significantly statistical difference between the groups (p< 0.0001). Load to 2 mm gap formation was 23, 63, 36 and 72 Newtons for Groups 2, 3, 4 and 5 respectively. There was a significantly statistical difference between the groups (p< 0.0001). Load to failure was 3,783 0,285 0,505 0,41 and 0,572 Joule for Groups 1, 2, 3, 4 and 5 respectively. There was a significantly statistical difference between the groups (p< 0.0001). Tendon stiffness was 42.6, 5.16, 11.2, 5.8 and 12.6 Newton/milimetre for Groups 1, 2, 3, 4 and 5 respectively. There was a significantly statistical difference between the groups (p< 0.0001). The rate of tendon resistance was 0.97, 0.8, 1.0 and 0.91 for Groups 2, 3, 4 and 5 respectively. There was no significantly statistical difference between these groups (p=0.747> 0.05). All the simple running repairs failed by suture pullout, while all the new multilocking loop periferal suture repairs failed by suture breakage.

Conclusion: The new multilocking loop periferal suture was the best performer overall, with greater ultimate strength, load to failure, 2 mm gap formation force and stiffness.

Aims: Immature articular cartilage has a different celularity from mature articular cartilage. Thus, the healing response may be different between these tissues. In this study, we investigated the role of IGF-I in full-thickness articular cartilage defects between immature and mature rabbits. Methods: This study used 36 immature and 36 mature New Zealand rabbits. Full-thickness articular cartilage defects in the medial femoral condyle were created. Spontaneous evolution occurred in 36 animals (18 immature and 18 mature). The other 36 animals were treated with a locally administrated IGF-I. The animals were killed in groups of eight at 4th, 8th and 12th weeks. Macroscopic, histopathologic and biochemical results were evaluated and analyzed statistically. Results: Serum IGF-I levels were signiþcantly higher in the immature group than the mature group (p< 0.001). Serum IGFBP-3 levels were signiþcantly higher in the mature group than the immature group (p< 0.05). Immunuhistochemical investigation showed chondrcyte proliferation in both groups, but duration of cell proliferation and healing process were shorter in the immature groups. The cell morphology was different between the groups. Local IGF-I treated groups had better histological scores than the control groups at all weeks (p< 0.001). Conclusions: The healing response in mature and immature cartilage were similar but the duration of this healing process was shorter in the immature group and repairing cell morphology was similar to that of the normal chondrocyte.