Tendon interposition and ligament reconstruction with ECRL tendon in the late stages of Kienböck's disease: a cadaver study.

BACKGROUND: The optimal surgical treatment for Kienböck's disease with stages IIIB and IV remains controversial. A cadaver study was carried out to evaluate the use of coiled extensor carpi radialis longus tendon for tendon interposition and a strip obtained from the same tendon for ligament reconstruction in the late stages of Kienböck's disease. METHODS: Coiled extensor carpi radialis longus tendon was used to fill the cavity of the excised lunate, and a strip obtained from this tendon was sutured onto itself after passing through the scaphoid and the triquetrum acting as a ligament to preserve proximal row integrity. Biomechanical tests were carried out in order to evaluate this new ligamentous reconstruction. RESULTS: It was biomechanically confirmed that the procedure was effective against axial compression and distributed the upcoming mechanical stress to the distal row. CONCLUSION: Extensor carpi radialis longus tendon has not been used for tendon interposition and ligament reconstruction in the treatment of this disease before. In view of the biomechanical data, the procedure seems to be effective for the stabilization of scaphoid and carpal bones.

[The effect of low-molecular-weight heparin on rat tendon healing]. / Düsük molekül agirlikli heparinin siçan tendon iyilesmesi üzerine etkisi.

OBJECTIVES: We investigated the effect of low-molecular-weight heparin (LMWH) on the healing of tendons. METHODS: Forty-five adult Wistar rats weighing 300 g were randomized into three groups equal in number. All the rats underwent full-thickness surgical incision of the Achilles tendon followed by primary repair. After the operation, two groups received daily subcutaneous LMWH injections (nadroparin calcium) for four weeks at high or low doses (group I, 6 mg/kg, 170 IU AXa; group II, 3 mg/kg, 85 IU AXa). Group III remained untreated as the control group. Histologically, the specimens were examined under light and electron microscopy with regard to the amount of fibrillar collagen synthesis, mitochondrial degeneration, and the composition of the extracellular matrix collagen. Biomechanically, maximum load to failure and correspondent elongation of the tendons were measured. RESULTS: Compared to the control group, histologically, both LMWH-treated groups exhibited increased number of fibroblasts, increased fibrillar collagen formation in the extracellular matrix, and higher counts of granular endoplasmic reticula in cytoplasmic contents of fibroblasts as well as decreased mitochondrial vacuolization and degeneration. Biomechanical assessments showed that tendons in group I had significantly higher maximum load to failure and elongation values than group II and III (31 N vs. 24.6 N and 23.1 N; 25 mm vs. 19.6 mm and 17.3 mm, respectively; p<0.05). Groups II and III did not differ significantly in this respect (p>0.05). CONCLUSION: Daily administration of single dose LMWH improves tendon healing through increasing the number of fibroblasts and fibrillar collagen synthesis and decreasing mitochondrial degeneration.

Mechanical strength of four different biceps tenodesis techniques.

PURPOSE: The aim of this study was to compare the biomechanical properties of 4 different biceps tenodesis techniques. TYPE OF STUDY: Biomechanical experiment. METHODS: Four groups of fresh sheep shoulders (28 total) with similar shape characteristics were used. Biceps tenodesis was performed using the following techniques: group 1 (n = 7), tunnel technique; group 2 (n = 7), interference screw technique; group 3 (n = 7), anchor technique; and group 4 (n = 7), keyhole technique. Each construct was loaded to failure and the groups were compared with respect to maximum load in Newtons and deflection at maximum load in millimeters. The results were statistically analyzed with 1-way analysis of variance, the Bonferroni post hoc test and the Student t test or the nonparametric Mann-Whitney U test. RESULTS: The calculated average maximum loads were 229.2 +/- 44.1 N for the tunnel technique, 243.3 +/- 72.4 N for the interference screw, 129.0 +/- 16.6 N for the anchor technique, and 101.7 +/- 27.9 N for the keyhole technique. Statistical testing showed no statistically significant differences between groups 1 and 2, groups 3 and 4, or groups 2 and 3 with respect to maximum load and deflection at maximum load (P = .09/P = .49, P = .41/P = .79, and P = .06/P = .82 for load/deflection in the 3 comparisons, respectively). However, all other group comparisons revealed significant differences for both parameters (group 1 v group 4 [P < .01/P < .01]; group 1 v group 3[P < .01/P = .01]; and group 2 v group 4 [P = .007/P = .003]). CONCLUSIONS: The strongest construct was made with the interference screw technique, followed by the tunnel, anchor, and keyhole techniques. There were no statistically significant differences between the interference screw and tunnel techniques with respect to maximum load or deflection at maximum load. CLINICAL RELEVANCE: Although it is difficult to extrapolate in vitro data to the clinical situation, the interference screw technique has better initial biomechanical properties and may produce improved clinical outcomes.

Numerical assessment on the effective mechanical stimuli for matrix-associated metabolism in chondrocyte-seeded constructs.

The self-regeneration capacity of articular cartilage is limited, due to its avascular and aneural nature. Loaded explants and cell cultures demonstrated that chondrocyte metabolism can be regulated via physiologic loading. However, the explicit ranges of mechanical stimuli that correspond to favourable metabolic response associated with extracellular matrix (ECM) synthesis are elusive.Unsystematic protocols lacking this knowledge produce inconsistent results. This study aims to determine the intrinsic ranges of physical stimuli that increase ECM synthesis and simultaneously inhibit nitric oxide (NO) production in chondrocyte­agarose constructs, by numerically reevaluating the experiments performed by Tsuang et al. (2008). Twelve loading patterns were simulated with poro-elastic finite element models in ABAQUS. Pressure on solid matrix, von Mises stress, maximum principle stress and pore pressure were selected as intrinsic mechanical stimuli.Their development rates and magnitudes at the steady state of cyclic loading were calculated with MATLAB at the construct level. Concurrent increase in glycosaminoglycan and collagen was observed at 2300 Pa pressure and 40 Pa/s pressure rate. Between 0­1500 Pa and 0­40 Pa/s, NO production was consistently positive with respect to controls, whereas ECM synthesis was negative in the same range. A linear correlation was found between pressure rate and NO production (R =0.77). Stress states identified in this study are generic and could be used to develop predictive algorithms for matrix production in agarose­chondrocyte constructs of arbitrary shape, size and agarose concentration. They could also be helpful to increase the efficacy of loading protocols for avascular tissue engineering.

Biomechanical and histological outcome of combined raloxifene-estrogen therapy on skeletal and reproductive tissues.

Estrogen replacement is a potent therapy for postmenopausal osteoporosis. However, its carcinogenic effects on breasts and the uterus limit its utilization. Raloxifene has estrogen-like effects on bones without the carcinogenic symptoms on breast or uterine tissue. Their individual effects are well characterized, but the results of their interaction remains elusive. In this work, we investigate the consequences of a combined raloxifene/estrogen therapy on bone and uterus with experimental osteoporosis. 40 Wistar rats began treatment 3 months post-ovariectomy. Estrogen and raloxifene were administered 0.03 mg/kg/day and 1.5mg/kg/day separately and together for 5 times per week for 12 weeks. Biomechanical tests and bone mineral density measurements, histology of uterus, and blood markers were analyzed. The co-administration group had higher toughness and ultimate strength than the ovariectomized controls (P<0.01). E+R had better biomechanical properties than the single treatments; yet the differences were not significant. Uterus histology signified high degeneration in the estrogen group. The raloxifene group had less degeneration but higher vascularization. Less immune reaction and vascularization were observed in the group with combined dosage than in those with individual treatments. Hence, the uterus of the combined treatment had fewer side effects than the ones that were individually treated. Mutual antagonization might be possible between raloxifene and estrogen, and that might have caused a decrease in the adverse effects. Overall, combined therapy might be useful to minimize the individual side effects of raloxifene and estrogen on the uterus and still provide bone strength and toughness.

Bone Fracture Healing with Umbilico-Placental Mononuclear Cells: A Controlled Animal Study.

BACKGROUND: Fracture healing is a significant process in orthopedics. In this controlled animal study, our aimis to expose the healing effects of cord blood umbilico-placental mononuclear cells (UPMNCs) on bone fractures. MATERIALS AND METHODS: Caesarean sections were performed on five pregnant New Zealand rabbits at term. Placentas and cords were collected. Standard closed transverse shaft fractures were created on both tibial bones of 15 baby rabbits. The right tibias were given UPMNCs; the left tibias were the control group. Histological examinations, osteoblast and osteoclast cell counts, and mechanical stabilities were compared. Anchorage of the donor cells was shown by the fluorescence in situ hybridization (FISH) technique. RESULTS: In the group injected with UPMNCs, histopathological fracture healing was faster, osteoblast and osteoclast counts were significantly increased, and the maximum load capacity was higher. The presence of XX and XY chromatins on the same slide revealed the anchorage of female donor cells on male tissues. CONCLUSION: The effects of umbilico-placental mononuclear cells on bone healing are histopathological healing priority, increased osteoblastic and osteoclastic activities (bone turnover), and better mechanical stability.

Effects of human granulocyte-colony stimulating factor on fracture healing in rats.

OBJECTIVE: Granulocyte colony stimulation factor (G-CSF) is generally used to prevent and cure the neutropenia associated with chemotherapy and bone marrow transplantation. In addition to its effects on neutrophil function, G-CSF was found to have the characteristic of modulating the cytokines in the inflammatory response. Then, the question to answer is whether it has any effect on fracture healing and to what extent? In this study, we test the effects of G-CSF on the healing of tibia fracture in a rat model. METHODS: This study was performed at Harran University, Sanliurfa, Turkey between July 2003 and August 2004. Twenty female, healthy Sprague-Dawley rats, weighing between 250 and 300 gm were divided into 2 groups, and their tibiae broken. The rats in the G-CSF group were injected subcutaneous with 25 microg/kg/day of recombinant human G-CSF for 7 days, and the ones in the control group with 0.9% sodium chloride. Rats were sacrificed 3 weeks after surgery and then radiological, histological and biomechanical evaluations were performed. Biomechanical tests were performed at the Middle East Technical University, Ankara, Turkey. RESULTS: The median radiographic scores for the control group were calculated as 4.1, and 6.1 for the G-CSF group (p = 0.016). Cortex remodeling, callus formation, bone union and marrow changes values did not differ significantly (p > 0.05). Mechanical parameter (mean max-Load) values for the control group were found to be 24.0 +/- 3.0 N, and 241.5 +/-75.7 N for the G-CSF group (p = 0.001). CONCLUSIONS: We found that G-CSF has an important effect on fracture healing. However, this effect requires further study.